Hydrogeochemical and isotopic evidences of groundwater salinization in coastal aquifers: A case study in Jeju volcanic island, Korea

NASA Astrophysics Data System (ADS)

Kim, Y.; Lee, D.; Lee, K.; Koh, D.; Lee, S.; Park, W.; Koh, G.; Woo, N.

2001-12-01

In order to clearly identify the origin of saline groundwaters in the eastern part of Jeju volcanic island, Korea the hydrogeochemical and isotopic studies have been carried out for 18 observation wells located in east and southeast coastal regions. The total dissolved solid (TDS) contents of groundwater samples are highly variable (77 to 21,782 mg/L). Most of the groundwaters in the study area are classified into Na-Cl type except a few samples showing Ca-Cl type. Hydrochemical characteristics based on bivariate and triangular diagrams of major ions show that the changes of chemical compositions of groundwaters were mainly controlled by the salinization process linked to cation-exchange reactions. The oxygen, hydrogen, sulfur, and strontium isotopic data explicitly show a simple mixing trend of groundwater and seawater. Using two-components fractional mixing model on the basis of 18O contents as well as Br and Cl contents, the proportion of seawater in fresh groundwater was quantitatively determined as high as 60 %. Sr isotopic compositions and Br/Cl ratios strongly suggest that the source of groundwater salinization is present-day seawater intrusion rather than paleoseawater or formation water, which can also be supported by the I/Cl ratios. The highly permeable aquifers in the east coastal region characterized by low hydraulic gradient and recharge rate and high hydraulic conductivity comparing with other regions are advantageous to the groundwater salinization. Based on the Cl, ¥ä18O, and 87Sr/86Sr it was determined that seawater has intruded into inland 2.5 km from coastline.

Checklist of the tidal pool fishes of Jeju Island, Korea

PubMed Central

Kwun, Hyuck Joon; Park, Jinsoon; Kim, Hye Seon; Kim, Ju-Hee; Park, Hyo-Seon

2017-01-01

Abstract Seventy-six species of fishes, representing 60 genera and 34 families, were recorded from tidal pools on Jeju Island, southern Korea. The major families in terms of species were the Gobiidae (11 species), Pomacentridae (8 species), Blenniidae (6 species), and Labridae (5 species). Thirty-nine species were classified as tropical, 26 as temperate and 11 as subtropical. PMID:29118640

Power system analysis of Hanlim superconducting HVDC system using real time digital simulator

NASA Astrophysics Data System (ADS)

Won, Y. J.; Kim, J. G.; Kim, A. R.; Kim, G. H.; Park, M.; Yu, I. K.; Sim, K. D.; Cho, J.; Lee, S.; Jeong, K. W.; Watanabe, K.

2011-11-01

Jeju island is located approximately 100 km south from the mainland of Korea, and had a peak load of about 553 MW in 2008. The demand increases 7.2% a year over the last 5 years. Since the wind profiles of Jeju island are more favorable than mainland of Korea, many companies have shown interest in the wind power business at the Jeju island. Moreover KEPCO has a plan for renewable energy test too whose power will be delivered by HVDC system. One kilometer length of total 8 km was designed as superconducting DC cable. Rest 7 km will be the conventional overhead line. In this paper, the authors have developed a simulation model of the power network around 8 km HVDC system using real time digital simulator (RTDS).

Late-Holocene vegetation and climate change in Jeju Island, Korea and its implications for ENSO influences

NASA Astrophysics Data System (ADS)

Park, Jungjae; Shin, Young Ho; Byrne, Roger

2016-12-01

Several recent studies suggest the hypothesis that the El Niño-Southern Oscillation (ENSO) is an important factor controlling the Holocene East Asian Monsoon (EAM). However, the mechanism underlying this influence remains unclear due to the lack of high-resolution paleoclimate records from the coast of East Asia. Here, we provide a new record of late Holocene climate change in coastal East Asia based on multi-proxy evidence (pollen, organic content, magnetic susceptibility, grain size) obtained from a sediment core from Jeju Island, South Korea. As Jeju Island is strongly influenced by the Kuroshio flow, our sediment proxy records contain ENSO signals from the tropical Pacific. The study area was affected by dry/cool conditions in the western tropical Pacific (WTP) between 4350 and 1920 cal yr BP when El Niños were frequent, and by rapid warming/wetting and forestation since 1920 cal yr BP when La Niñas were more common. Jeju Island was relatively dry/cool between 2100 and 1600, 1300-1200, 1100-1000, 800-650, and 300-50 cal yr BP, as opposed to the Galápagos Islands, which were relatively wet/warm, reflecting the ENSO-related negative correlation between eastern and western margins of Pacific. Wet conditions may have prevailed during the early Little Ice Age (LIA) (620-280 cal yr BP) despite consistent cooling. This period of high precipitation may have been associated with the increased landfall of typhoons and with warmer Kuroshio currents under La Niña-like conditions. According to our results, EAM on the East Asian coastal margin was predominantly driven by ENSO activity, rather than by the precession effect. Paleoclimatic data from Jeju Island, with its insular position and closeness to warm Kuroshio currents, provide clear evidence of these ENSO influences.

Lahar flow simulation using Laharz_py program: Application for the Mt. Halla volcano, Jeju, Korea

NASA Astrophysics Data System (ADS)

Chang, C.; Yun, S. H.; Yi, W.

2017-12-01

Lahar, one of catastrophic events, has the potential to cause the loss of life and damage to infrastructure over inhabited areas. This study using Laharz_py, was performed schematic prediction on the impact area of lahar hazards at the Mt. Halla volcano, Jeju island. In order to comprehensively address the impact of lahar for the Mt. Halla, two distinct parameters, H/L ratio and lahar volume, were selected to influence variable for Laharz_py simulation. It was carried out on the basis of numerical simulation by estimating a possible lahar volumes of 30,000, 50,000, 70,000, 100,000, 300,000, 500,000 m3 according to H/L ratios (0.20, 0.22 and 0.25) was applied. Based on the numerical simulations, the area of the proximal hazard zone boundary is gradually decreased with increasing H/L ratio. The number of streams which affected by lahar, tended to decrease with increasing H/L ratio. In the case of H/L ratio 0.20, three streams (Gwangryeong stream, Dogeun stream, Han stream) in the Jeju-si area and six streams (Gungsan stream, Hogeun stream, Seohong stream, Donghong stream, Bomok stream, Yeong stream-Hyodon stream) in the Seogwipo-si area are affected. In the case of H/L ratio 0.22, two streams (Gwangryeong stream and Han stream) in the Jeju-si area and five streams (Gungsan stream, Seohong stream, Donghong stream, Bomok stream, Yeong stream-Hyodon stream) in the Seogwipo-si area are affected. And in the case of H/L ratio 0.25, two streams (Gwangryeong stream and Han stream) in the Jeju-si area and one stream (Yeong stream-Hyodon stream) in the Seogwipo-si area are affected. The results of this study will be used as basic data to create a risk map for the direct damage that can be caused due to volcanic hazards arising from Mt. Halla. This research was supported by a grant [MPSS-NH-2015-81] through the Disaster and Safety Management Institute funded by Ministry of Public Safety and Security of Korean government.

Molecular and morphological data reveal hybrid origin of wild Prunus yedoensis (Rosaceae) from Jeju Island, Korea: implications for the origin of the flowering cherry.

PubMed

Cho, Myong-Suk; Kim, Chan-Soo; Kim, Seon-Hee; Kim, Ted Oh; Heo, Kyoung-In; Jun, Jumin; Kim, Seung-Chul

2014-11-01

The subgenus Cerasus of the genus Prunus includes several popular ornamental flowering cherries. Of the hundreds of cultivars, P. ×yedoensis ('Somei-yoshino') is the most popular and familiar cultivar in Korea and Japan and is considered to be of hybrid origin. However, the hybrid origin of P. ×yedoensis and its relationship to wild P. yedoensis, naturally occurring on Jeju Island, Korea, are highly controversial. We extensively sampled wild P. yedoensis, cultivated P. ×yedoensis, and numerous individuals from other species belonging to subgenus Cerasus on Jeju Island. Samples from 71 accessions, representing 13 species and one cultivar (P. ×yedoensis), were sequenced for nrDNA ITS/ETS (952 characters) and seven noncoding cpDNA regions (5421 characters) and subjected to maximum parsimony and maximum likelihood analysis. Additive polymorphisms in the ITS/ETS regions were confirmed by cloning amplicons from representative species. The nuclear (ITS/ETS and G3pdh) and cpDNA data, along with several morphological characteristics, provide the first convincing evidence for the hybrid origin of wild P. yedoensis. The maternal parent was determined to be P. spachiana f. ascendens, while the paternal parent was unresolved from the taxonomically complex P. serrulata/P. sargentii clade. The presence of two kinds of ribotypes was confirmed by cloning, and the possible origin of cultivated P. ×yedoensis from wild populations on Jeju Island was also suggested. Bidirectional and multiple hybridization events were responsible for the origin of wild P. yedoensis. Extensive gene flow was documented in this study, suggesting an important role of reticulate evolution in subgenus Cerasus. © 2014 Botanical Society of America, Inc.

Molecular genetic analysis of ancient cattle bones excavated from archaeological sites in Jeju, Korea.

PubMed

Kim, Jae-Hwan; Oh, Ju-Hyung; Song, Ji-Hoon; Jeon, Jin-Tae; Han, Sang-Hyun; Jung, Yong-Hwan; Oh, Moon-You

2005-12-31

Ancient cattle bones were excavated from archaeological sites in Jeju, Korea. We used molecular genetic techniques to identify the species and establish its relationship to extant cattle breeds. Ancient DNA was extracted from four sources: a humerus (Gonae site, A.D. 700-800), two fragments of radius, and a tooth (Kwakji site, A.D. 0-900). The mitochondrial DNA (mtDNA) D-loop regions were cloned, sequenced, and compared with previously reported sequences of various cattle breeds (9 Asian, 8 European, and 3 African). The results revealed that these bones were of the breed, Bos taurus, and a phylogenetic tree indicated that the four cattle bones formed a monophyletic group with Jeju native black cattle. However, the patterns of sequence variation and reports from archaeological sites suggest that a few wild cattle, with a different maternal lineage, may have existed on Jeju Island. Our results will contribute to further studies of the origin of Jeju native cattle and the possible existence of local wild cattle.

A new species of the genus Ammonicera (Prosobranchia, Omalogyridae) in a coralline algae community from Jeju Island, off the south coast of Korea

NASA Astrophysics Data System (ADS)

Waki, Tsukasa; Rolán, Emilio; Noseworthy, Ronald G.; Kang, Hyun-Sil; Choi, Kwang-Sik

2017-12-01

A species of the genus Ammonicera Vayssière, 1893 collected from coralline algae communities in Jeju Island, South Korea, is described as a new species, A. aurea, for science. Its morphological characters are described and illustrated by SEM micrographs. This new species can be clearly distinguished from other Ammonicera species from the Pacific Ocean by the presence of a spiral cord and about 25 slightly-elevated axial ribs, resulting in about 25 nodules at intersecting points of the cord and ribs on the last whorl of the teleoconch.

Prevalence and severity of atopic dermatitis in Jeju Island: a cross-sectional study of 4,028 Korean elementary schoolchildren by physical examination utilizing the three-item severity score.

PubMed

Kim, Dae Suk; Lee, Ju Hee; Lee, Kwang Hoon; Lee, Min-Geol

2012-09-01

The objective of this study was to evaluate the precise prevalence of atopic dermatitis (AD) in schoolchildren in Jeju Island in South Korea examined in 2009. Nine elementary schools were randomly selected from Jeju Island and a total of 4,028 schoolchildren were examined by a dermatologist. AD was diagnosed based on the Korean Atopic Dermatitis Research Group criteria for the disease. The severity of AD was measured with the three-item severity score (TIS). The point prevalence of AD was 9.5% overall. The prevalence among higher graders (age 9-12 years) was significantly lower than that in lower graders (age 6-9 years) (7.5% vs. 11.9%, < 0.00001). AD prevalence in girls (11.1%) was higher than that in boys (8.1%) (<0.005). In each grade, more than 50% of those affected had the mild form (TIS score 1 or 2). There were no apparent differences in severity of AD between grades or genders. This is the first Asian study of prevalence in schoolchildren using TIS score for evaluating AD severity.

Marmoricola scoriae sp. nov., isolated from volcanic ash.

PubMed

Lee, Dong Wan; Lee, Soon Dong

2010-09-01

A novel Gram-stain-positive, coccoid actinobacterium, designated strain Sco-D01(T), was isolated from volcanic ash collected from Oreum (a parasitic volcanic cone) on Jeju Island, Republic of Korea. Cells were aerobic, oxidase-negative and catalase-positive. Colonies were vivid yellow, circular, smooth and convex. The diagnostic diamino acid in the cell wall was ll-diaminopimelic acid. The predominant menaquinone was MK-8(H(4)). The polar lipids were phosphatidylinositol, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine and an unknown phospholipid. The fatty acid profile was represented by large amounts of saturated, unsaturated, 10-methyl and hydroxyl components. The DNA G+C content of strain Sco-D01(T) was 72.0 mol%. 16S rRNA gene sequence analysis revealed that strain Sco-D01(T) belonged to the family Nocardioidaceae and formed a distinct sublineage within the radiation of the genus Marmoricola. The level of DNA-DNA relatedness between strain Sco-D01(T) and its closest phylogenetic relative, Marmoricola aurantiacus DSM 12652(T), was 30.2 % (35.4 % in duplicate measurements). On the basis of phenotypic and DNA-DNA hybridization data, strain Sco-D01(T) is considered to represent a novel species of the genus Marmoricola, for which the name Marmoricola scoriae sp. nov. is proposed. The type strain is Sco-D01(T) (=KCTC 19597(T)=DSM 22127(T)).

Analysis of the natural radioactivity concentrations of the fine dust samples in Jeju Island, Korea and the annual effective radiation dose by inhalation.

PubMed

Han, Chung Hun; Park, Jae Woo

2018-01-01

This study analyzed the concentrations of potassium, thorium and uranium of the atmospheric PM 10 aerosols which were collected at Gosan of Jeju Island during the year of 2014. The mean mass concentration of PM 10 was 47.31 μg/m 3 . The mean radioactive concentrations of 40 K, 232 Th and 238 U were 7.89, 0.25 and 0.30 μBq/m 3 , respectively. The 232 Th/ 238 U activity concentration ratio of PM 10 was 0.830. The 232 Th/ 238 U ratio during Asian Dust days is 1.073, which is higher than those in other atmospheric conditions. The concentration ratio of 232 Th/ 238 U was 0.902 in China continent.

Effects of obesity and obesity-induced stress on depressive symptoms in Korean elementary school children.

PubMed

Park, Chul-Min; Kim, Moon-Doo; Hong, Seong-Chul; Kim, Yeol; Hyun, Mi-Youl; Kwak, Young-Sook; Lee, Chang-In; Park, Min-Jeong; Jang, Yun-Hee; Moon, Ji-Hyun; Seok, Eun-Mi; Song, Young-Ja; Hyeon Ju Kim

2009-07-01

Obesity is becoming prevalent in Korean children. Because body image is becoming increasingly important, it is likely that obesity-induced stress has a significant effect on childhood depression. To examine the correlation between obesity-induced stress and depressive symptoms in Korean elementary school students. The study participants were 2,305 elementary school children and their parents in the districts of Jeju-si, Seogwipo-si, Namjeju-gun and Bukjeju-gun on Jeju Island, Korea, who completed questionnaires involving demographic information, an obesity-induced stress scale and the Korean form of Kovacs' Children's Depression Inventory (CDI) from September to December 2006. After controlling for significant independent variables that are wellknown correlates of depressive symptoms in children (e.g. age, gender, residence, family monthly income, obesity status of both parents, family history of chronic illness, and time spent with mother), obesity-induced stress had an odds ratio of 1.128 (95% CI 1.111-1.146). Reducing the prevalence of depressive symptoms in elementary school children in Jeju Island will require special attention, particularly the development of coping strategies to resolve obesity-induced stress in various areas including school, family and society.

The occurrence of Clithon retropictus (v. Martens, 1879) (Gastropoda: Neritidae) in an unusual habitat, northern Jeju Island, Republic of Korea

NASA Astrophysics Data System (ADS)

Noseworthy, Ronald G.; Lee, Hee-Jung; Choi, Kwang-Sik

2013-09-01

Clithon retropictus is a neritid gastropod inhabiting mainly brackish water. Currently this species has been listed as a second grade endangered species of wildlife in Korea by the Ministry of Environment, due to the decrease in its population size. C. retropictus has previously been identified from estuaries on the south coast of Korea. In Jeju Island, this species has been reported only from the south coast. However, a population has recently been discovered on the north coast of the island in an apparently new type of habitat, under rocks adjacent to a dry riverbed on a muddy substrate. C. retropictus was found to be aggregated under some of the larger rocks, and the habitat was located near the high tide line. The present study reports some possible reasons for the occurrence of the population in this unusual habitat, and provides useful information on the biometry and population size which can be used in the management of this endangered species.

The association between wind-related variables and stroke symptom onset: A case-crossover study on Jeju Island.

PubMed

Kim, Jayeun; Yoon, Khyuhyun; Choi, Jay Chol; Kim, Ho; Song, Jung-Kook

2016-10-01

Although several studies have investigated the effects of ambient temperature on the risk of stroke, few studies have examined the relationship between other meteorological conditions and stroke. Therefore, the aim of this study was to analyze the association between wind-related variables and stroke symptoms onset. Data regarding the onset of stroke symptoms occurring between January 1, 2006, and December 31, 2007 on Jeju Island were collected from the Jeju National University Hospital stroke registry. A fixed-strata case-crossover analysis based on time of onset and adjusted for ambient temperature, relative humidity, air pressure, and pollutants was used to analyze the effects of wind speed, the daily wind speed range (DWR), and the wind chill index on stroke symptom onset using varied lag terms. Models examining the modification effects by age, sex, smoking status, season, and type of stroke were also analyzed. A total of 409 stroke events (381 ischemic and 28 hemorrhagic) were registered between 2006 and 2007. The odds ratios (ORs) for wind speed, DWR, and wind chill among the total sample at lag 0-8 were 1.18 (95% confidence interval (CI): 1.06-1.31), 1.08 (95% CI: 1.02-1.14), and 1.22 (95% CI: 1.07-1.39) respectively. The ORs for wind speed, DWR, and wind chill for ischemic stroke patients were slightly greater than for patients in the total sample (OR=1.20, 95% CI: 1.08-1.34; OR=1.09, 95% CI: 1.03-1.15; and OR=1.22, 95% CI: 1.07-1.39, respectively). Statistically significant season-specific effects were found for spring and winter, and various delayed effects were observed. In addition, age, sex, and smoking status modified the effect size of wind speed, DWR, and wind chill. Our analyses showed that the risk of stroke symptoms onset was associated with wind speed, DWR, and wind chill on Jeju Island. Copyright © 2016 Elsevier Inc. All rights reserved.

Factor analysis and multiple regression between topography and precipitation on Jeju Island, Korea

NASA Astrophysics Data System (ADS)

Um, Myoung-Jin; Yun, Hyeseon; Jeong, Chang-Sam; Heo, Jun-Haeng

2011-11-01

SummaryIn this study, new factors that influence precipitation were extracted from geographic variables using factor analysis, which allow for an accurate estimation of orographic precipitation. Correlation analysis was also used to examine the relationship between nine topographic variables from digital elevation models (DEMs) and the precipitation in Jeju Island. In addition, a spatial analysis was performed in order to verify the validity of the regression model. From the results of the correlation analysis, it was found that all of the topographic variables had a positive correlation with the precipitation. The relations between the variables also changed in accordance with a change in the precipitation duration. However, upon examining the correlation matrix, no significant relationship between the latitude and the aspect was found. According to the factor analysis, eight topographic variables (latitude being the exception) were found to have a direct influence on the precipitation. Three factors were then extracted from the eight topographic variables. By directly comparing the multiple regression model with the factors (model 1) to the multiple regression model with the topographic variables (model 3), it was found that model 1 did not violate the limits of statistical significance and multicollinearity. As such, model 1 was considered to be appropriate for estimating the precipitation when taking into account the topography. In the study of model 1, the multiple regression model using factor analysis was found to be the best method for estimating the orographic precipitation on Jeju Island.

Mcare 2017

NASA Astrophysics Data System (ADS)

Kim, Do-Heyoung; Yong, Kijung; Im, Yeonho; Kim, Woojae; Lee, Doh Chang

2018-01-01

The Materials Challenges in Alternative and Renewable Energy Conference (MCARE 2017) was aimed at providing a forum for closely interactive communication and collaboration between leading experts from various fields related with materials in alternative and renewable energy. MCARE 2017 was held on Jeju Island, Korea on February 20-24, 2017. At this beautiful site, about 450 participants joined the conference and 459 papers were presented. About 110 foreign participants from all over the world particpated. MCARE 2017 was hosted by the Korea Institute of Chemical Engineers (KIChE) and was organized by the Materials Division of KIChE and the American Ceramic Society. Financial support was given by Lotte Chemical, LG Hausys, Jeju Convention & Visitors Bureau, and Korea Tourism Organization, Flexible Thermoelectric Semiconductor Device Technology Center, Super Ultra Low Energy and Emission Vehicle Center, Korea Institute of Materials Science, Jeju Techno Park, Center for Future Energy Materials and Devices and Korea Institute for Rare Metals.

Serologic survey of toxoplasmosis in Seoul and Jeju-do, and a brief review of its seroprevalence in Korea.

PubMed

Lim, Hyemi; Lee, Sang-Eun; Jung, Bong-Kwang; Kim, Min-Ki; Lee, Mi Youn; Nam, Ho-Woo; Shin, Jong-Gyun; Yun, Cheong-Ha; Cho, Han-Ik; Shin, Eun-Hee; Chai, Jong-Yil

2012-12-01

Knowledge of the prevalence of human Toxoplasma gondii infection is required in the Republic of Korea. In this study, we surveyed the seroprevalence of T. gondii infection and analyzed the risk factors associated with seropositivity among residents in 2 administrative districts; Seoul and the island of Jeju-do, which have contrasting epidemiologic characteristics. Sera and blood collected from 2,150 residents (1,114 in Seoul and 1,036 in Jeju-do) were checked for IgG antibody titers using ELISA and for the T. gondii B1 gene using PCR. In addition, participants completed a questionnaire that solicited information on gender, age, occupation, eating habits, history of contact with animals, and travel abroad. The T. gondii B1 gene was not detected in all residents examined. However, ELISA showed 8.0% (89 of 1,114 sera) positive for IgG antibodies against T. gondii in Seoul and 11.3% (117 of 1,036 sera) in Jeju-do. In both districts, the positive rates were higher in males than in females, and those 40-79 years of age showed higher rates than other ages. In Seoul, residents older than 70 years of age showed the highest positive rate, 14.9%, whereas in Jeju-do the highest prevalence, 15.6%, was in those in their sixties. The higher seropositive rate in Jeju-do than in Seoul may be related to eating habits and occupations. The present results and a review of related literature are indicative of an increased seroprevalence of T. gondii in Korea in recent years.

Intersexuality of Scomberomorus niphonius from the Coastal Area around Jeju Island, Korea (Teleostei: Scombridae)

PubMed Central

Kim, Jong Bin; Chang, Dae Soo; Kim, Hyejin; Jeon, Mi Ae; Ku, Kayeon; Lee, Jung Sick

2013-01-01

This study histologically describes the intersexuality of Scomberomorus niphonius collected from the coastal area near Jeju Island. A total of 126 S. niphonius, collected from March to July 2012 with a total length of 62.4 cm (±17.5) and a total weight of 1,701.9 g (±1,528.9) were used for analyses. From a histological perspective, two types of intersex were confirmed. One type had scattered germ cells from the opposite sex within the gonad. The second type developed germ cells from the opposite sex in the connective tissue of the outer gonadal membrane. The intersexuality was 14.3% (n=18/126), with females (21.3%; n=16/75) exhibiting a higher rate than males (3.9%; n=2/51). There was no displayed correlation between intersexuality and the total length and weight. PMID:25949123

Diversity and enzyme activity of Penicillium species associated with macroalgae in Jeju Island.

PubMed

Park, Myung Soo; Lee, Seobihn; Oh, Seung-Yoon; Cho, Ga Youn; Lim, Young Woon

2016-10-01

A total of 28 strains of 19 Penicillium species were isolated in a survey of extracellular enzyme-producing fungi from macroalgae along the coast of Jeju Island of Korea. Penicillium species were identified based on morphological and β-tubulin sequence analyses. In addition, the halo-tolerance and enzyme activity of all strains were evaluated. The diversity of Penicillium strains isolated from brown algae was higher than the diversity of strains isolated from green and red algae. The commonly isolated species were Penicillium antarcticum, P. bialowiezense, P. brevicompactum, P. crustosum, P. oxalicum, P. rubens, P. sumatrense, and P. terrigenum. While many strains showed endoglucanase, β-glucosidase, and protease activity, no alginase activity was detected. There was a positive correlation between halo-tolerance and endoglucanase activity within Penicillium species. Among 19 Penicillium species, three species-P. kongii, P. olsonii, and P. viticola-have not been previously recorded in Korea.

Complete chloroplast genome of Prunus yedoensis Matsum.(Rosaceae), wild and endemic flowering cherry on Jeju Island, Korea.

PubMed

Cho, Myong-Suk; Hyun Cho, Chung; Yeon Kim, Su; Su Yoon, Hwan; Kim, Seung-Chul

2016-09-01

The complete chloroplast genome sequences of the wild flowering cherry, Prunus yedoensis Matsum., which is native and endemic to Jeju Island, Korea, is reported in this study. The genome size is 157 786 bp in length with 36.7% GC content, which is composed of LSC region of 85 908 bp, SSC region of 19 120 bp and two IR copies of 26 379 bp each. The cp genome contains 131 genes, including 86 coding genes, 8 rRNA genes and 37 tRNA genes. The maximum likelihood analysis was conducted to verify a phylogenetic position of the newly sequenced cp genome of P. yedoensis using 11 representatives of complete cp genome sequences within the family Rosaceae. The genus Prunus exhibited monophyly and the result of the phylogenetic relationship agreed with the previous phylogenetic analyses within Rosaceae.

Geomagnetic field intensity determination from Pleistocene trachytic lava flows in Jeju Geopark

NASA Astrophysics Data System (ADS)

Jeong, Doohee; Yu, Yongjae; Liu, Qingsong; Jiang, Zhaoxia; Koh, Gi Won; Koh, Dong-Chan

2014-03-01

A composite of 28 trachytic lava flows were recovered from the Jeju Geopark Drilling Project (JGDP) in Jeju Geopark, one of the new seven wonders of Nature declared by UNESCO in 2011. Each trachytic lava flow has a tendency to increase in magnetic grain size from the rapidly cooled brecciated margin and vesicle streaked zone downward into the massive crystalline flow interiors. The brecciated margin and vesicle streaked zone of individual trachytic lava flow contains exclusively fine-grained magnetite as inclusions in plagioclase. High-fidelity paleointensity determinations were obtained from 26 (out of 224 examined) samples from JGDP cores. Temporal variation of virtual axial dipole moments (VADMs) calculated from the absolute paleointensity estimates follows the trend of sint-800 data for the interval from ˜80 to ˜360 ka. High VADM from flow 21 possibly represents real intensity peak, as previously recognized high VADM in Japan at ˜336 ka, in Trans-Mexican volcanism ˜339, and in Hawaii ˜340-350 ka. Perhaps such a strong magnetic intensity near ˜325-350 ka might be smoothed out in relative paleointensity records.

New polymorphic microsatellite markers derived from hemocyte cDNA library of Manila clam Ruditapes philippinarum challenged by the protozoan parasite Perkinsus olseni

NASA Astrophysics Data System (ADS)

Kang, Hyun-Sil; Hong, Hyun-Ki; Park, Kyung-Il; Cho, Moonjae; Youn, Seok-Hyun; Choi, Kwang-Sik

2017-03-01

Manila clam Ruditapes philippinarum is one of the most important benthic animals in the coastal north Pacific region, where clam populations have been mixed genetically through trade and aquaculture activities. Accordingly, identification of the genetically different clam populations has become one of the most important issues to manage interbreeding of the local and introduced clam populations. To identify genetically different populations of clam populations, we developed 11 expressed sequence tag (EST)-microsatellite loci (i.e., simple sequence repeat, SSR) from 1,128 clam hemocyte cDNA clones challenged by the protozoan parasite Perkinsus olseni. Genotype analysis using the markers developed in this study demonstrated that clams from a tidal flat on the west coast contained 6 to 19 alleles per locus, and a population from Jeju Island had 4 to 20 alleles per locus. The expected heterozygosity of the 2 clam populations ranged from 0.472 to 0.919 for clams from the west coast, and 0.494 to 0.919 for clams from Jeju Island, respectively. Among the 11 loci discovered in this study, 7 loci significantly deviated from the Hardy-Weinberg equilibrium after Bonferroni correction. The 5 loci developed in this study also successfully amplified the SSRs of R. variegatus, a clam species taxonomically very close to R. philippinarum, from Hong Kong and Jeju Island. We believe that the 11 novel polymorphic SSR developed in this study can be utilized successfully in Manila clam genetic diversity analysis, as well as in genetic discrimination of different clam populations.

Regional atmospheric emissions determined from measurements at Jeju Island, Korea: Halogenated compounds from China

NASA Astrophysics Data System (ADS)

Kim, Jooil; Li, Shanlan; Kim, Kyung-Ryul; Stohl, Andreas; Mühle, Jens; Kim, Seung-Kyu; Park, Mi-Kyung; Kang, Dong-Jin; Lee, Gangwoong; Harth, Christina M.; Salameh, Peter K.; Weiss, Ray F.

2010-06-01

High-frequency in-situ measurements of a wide range of halogenated compounds including chlorofluorocarbons (CFCs), halons, hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), perfluorinated compounds (PFCs), sulfur hexafluoride (SF6), and other chlorinated and brominated compounds have been made at Gosan (Jeju Island, Korea). Regional emissions of HCFC-22 (CHClF2) calculated from inverse modeling were combined with interspecies correlation methods to estimate national emissions for China, a major emitter of industrial halogenated gases. Our results confirm the signs of successful phase-out of primary ozone-depleting species such as CFCs, halons and many chlorinated or brominated compounds, along with substantial emissions of replacement HCFCs. Emissions derived for HFCs, PFCs, and SF6 were compared to published estimates and found to be a significant fraction of global totals. Overall, Chinese emissions of the halogenated compounds discussed here represent 19(14-17)% and 20(15-26)% of global emissions when evaluated in terms of their Ozone Depletion Potentials and 100-year Global Warming Potentials, respectively.

Porcine abortion outbreak associated with Toxoplasma gondii in Jeju Island, Korea.

PubMed

Kim, Jae Hoon; Kang, Kyung Il; Kang, Wan Cheul; Sohn, Hyun Joo; Jean, Young Hwa; Park, Bong Kyun; Kim, Yongbaek; Kim, Dae Yong

2009-06-01

This report deals with the acute onset of an abortion outbreak and high sow mortality in one pig herd consisted of 1,200 pigs and 120 sows on Jeju Island, Korea. Affected pregnant sows showed clinical signs, including high fever, gradual anorexia, vomiting, depression, recumbency, prostration, abortion, and a few deaths. Four dead sows, five aborted fetuses from the same litter, and 17 sera collected from sows infected or normal were submitted to the Pathology Division of the National Veterinary Research and Quarantine Service for diagnostic investigation. Grossly, hepatomegaly and splenomegaly were observed in sows. Multiple necrotic foci were scattered in the lungs, liver, spleen, and lymph nodes. Microscopically, multifocal necrotizing lesions and protozoan tachyzoites were present in the lesions. Tachyzoites of Toxoplasma (T.) gondii were detected immunohistochemically. Latex agglutination showed that the sera of 7 of 17 (41.2%) sows were positive for antibody to T. gondii. The disease outbreak in this herd was diagnosed as epizootic toxoplasmosis. To our knowledge, this is the first report of porcine toxoplasmosis with a high abortion rate and sow mortality in Korea.

Population genetic structure of eelgrass (Zostera marina) on the Korean coast: Current status and conservation implications for future management

PubMed Central

Kim, Jae Hwan; Kang, Ji Hyoun; Jang, Ji Eun; Choi, Sun Kyeong; Kim, Min Ji; Park, Sang Rul; Lee, Hyuk Je

2017-01-01

Seagrasses provide numerous ecosystem services for coastal and estuarine environments, such as nursery functions, erosion protection, pollution filtration, and carbon sequestration. Zostera marina (common name “eelgrass”) is one of the seagrass bed-forming species distributed widely in the northern hemisphere, including the Korean Peninsula. Recently, however, there has been a drastic decline in the population size of Z. marina worldwide, including Korea. We examined the current population genetic status of this species on the southern coast of Korea by estimating the levels of genetic diversity and genetic structure of 10 geographic populations using eight nuclear microsatellite markers. The level of genetic diversity was found to be significantly lower for populations on Jeju Island [mean allelic richness (AR) = 1.92, clonal diversity (R) = 0.51], which is located approximately 155 km off the southernmost region of the Korean Peninsula, than for those in the South Sea (mean AR = 2.69, R = 0.82), which is on the southern coast of the mainland. South Korean eelgrass populations were substantially genetically divergent from one another (FST = 0.061–0.573), suggesting that limited contemporary gene flow has been taking place among populations. We also found weak but detectable temporal variation in genetic structure within a site over 10 years. In additional depth comparisons, statistically significant genetic differentiation was observed between shallow (or middle) and deep zones in two of three sites tested. Depleted genetic diversity, small effective population sizes (Ne) and limited connectivity for populations on Jeju Island indicate that these populations may be vulnerable to local extinction under changing environmental conditions, especially given that Jeju Island is one of the fastest warming regions around the world. Overall, our work will inform conservation and restoration efforts, including transplantation for eelgrass populations at the southern tip of the Korean Peninsula, for this ecologically important species. PMID:28323864

Population genetic structure of eelgrass (Zostera marina) on the Korean coast: Current status and conservation implications for future management.

PubMed

Kim, Jae Hwan; Kang, Ji Hyoun; Jang, Ji Eun; Choi, Sun Kyeong; Kim, Min Ji; Park, Sang Rul; Lee, Hyuk Je

2017-01-01

Seagrasses provide numerous ecosystem services for coastal and estuarine environments, such as nursery functions, erosion protection, pollution filtration, and carbon sequestration. Zostera marina (common name "eelgrass") is one of the seagrass bed-forming species distributed widely in the northern hemisphere, including the Korean Peninsula. Recently, however, there has been a drastic decline in the population size of Z. marina worldwide, including Korea. We examined the current population genetic status of this species on the southern coast of Korea by estimating the levels of genetic diversity and genetic structure of 10 geographic populations using eight nuclear microsatellite markers. The level of genetic diversity was found to be significantly lower for populations on Jeju Island [mean allelic richness (AR) = 1.92, clonal diversity (R) = 0.51], which is located approximately 155 km off the southernmost region of the Korean Peninsula, than for those in the South Sea (mean AR = 2.69, R = 0.82), which is on the southern coast of the mainland. South Korean eelgrass populations were substantially genetically divergent from one another (FST = 0.061-0.573), suggesting that limited contemporary gene flow has been taking place among populations. We also found weak but detectable temporal variation in genetic structure within a site over 10 years. In additional depth comparisons, statistically significant genetic differentiation was observed between shallow (or middle) and deep zones in two of three sites tested. Depleted genetic diversity, small effective population sizes (Ne) and limited connectivity for populations on Jeju Island indicate that these populations may be vulnerable to local extinction under changing environmental conditions, especially given that Jeju Island is one of the fastest warming regions around the world. Overall, our work will inform conservation and restoration efforts, including transplantation for eelgrass populations at the southern tip of the Korean Peninsula, for this ecologically important species.

Spatio-temporal distribution and sources of Pb identified by stable isotopic ratios in sediments from the Yangtze River Estuary and adjacent areas.

PubMed

Chen, Bin; Liu, Jian; Hu, Limin; Liu, Ming; Wang, Liang; Zhang, Xilin; Fan, Dejiang

2017-02-15

To understand the spatio-temporal distribution and sources of Pb in the sediments of the Yangtze River Estuary and its adjacent areas, 25 surface sediments and 1 sediment core were collected from the study areas. The concentrations of Al and Pb of these sediments exhibit a decreasing trend from the nearshore towards the offshore, with higher concentrations in the coastal areas of the East China Sea (ECS) and southwest of Jeju Island. According to the stable isotopic ratios of Pb, in combination with the elemental ratios and clay mineral data, it is inferred that sedimentary Pb in the surface sediments of the coastal areas of the ECS may come primarily from the Yangtze River, while the Pb southwest of Jeju Island is probably derived from both the Yangtze and Yellow Rivers. The particulate Pb derived from the Yangtze River was possibly dispersed along two paths: the path southward along the coastline of the ECS and the path eastward associated with the Changjiang Diluted Water (CDW), which crosses the shelf of the ECS towards the area southeast of Jeju Island. Although the Yangtze River Basin witnessed rapid economic development during the period from the late 1970s to the middle 1990s, the influence of human activity on Pb concentration remained weak in the Yangtze River Estuary. Since the early 2000s, however, sedimentary Pb has been significantly increasing in the coastal mud areas of the ECS due to the increasing influence of human activity, such as the increase in atmospheric emission of anthropogenic Pb in China, construction of the Three Gorges Dam (TGD), and the construction of smaller dams in the upper reaches of the Yangtze River. Coal combustion and the smelting of non-ferrous metals are possible anthropogenic sources for the sedimentary Pb in the Yangtze River Estuary. Copyright © 2016. Published by Elsevier B.V.

Mucilaginibacter vulcanisilvae sp. nov., isolated from a volcanic forest.

PubMed

Baek, Kyunghwa; Ok Jeon, Che

2015-07-01

A Gram-stain-negative, strictly aerobic, pale-pink-pigmented bacterium, designated strain G27(T), was isolated from a volcanic forest of Jeju Island, South Korea. Cells were catalase- and oxidase-positive, non-motile rods producing exopolysaccharide and flexirubin-type and pale pink pigments. Growth of strain G27(T) was observed at 4-30 °C (optimum, 25 °C) and pH 5.0-8.0 (optimum, pH 7.0). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain G27(T) formed a phyletic lineage within the genus Mucilaginibacter of the family Sphingobacteriaceae. Strain G27(T) was related most closely to Mucilaginibacter gossypii Gh-67(T) at 96.5% 16S rRNA gene sequence similarity. Strain G27(T) contained menaquinone 7 (MK-7) as the sole isoprenoid quinone and summed feature 3 (comprising C16:1ω7c/C16:1ω6c), iso-C15:0, C16:0, C16:1ω5c and C16:1ω5c as the major cellular fatty acids. Phosphatidylethanolamine was identified as the major polar lipid. The G+C content of the genomic DNA was 46.5 mol%. On the basis of phenotypic, chemotaxonomic and molecular properties, strain G27(T) represents a novel species of the genus Mucilaginibacter, for which the name Mucilaginibacter vulcanisilvae sp. nov. is proposed. The type strain is G27(T) ( = KACC 18231(T) = JCM 30363(T)).

Classical Swine Fever Outbreak after Modified Live LOM Strain Vaccination in Naive Pigs, South Korea

PubMed Central

Je, Sang H.; Kwon, Taeyong; Yoo, Sung J.; Lee, Dong-Uk; Lee, SeungYoon; Richt, Juergen A.

2018-01-01

We report classical swine fever outbreaks occurring in naive pig herds on Jeju Island, South Korea, after the introduction of the LOM vaccine strain. Two isolates from sick pigs had >99% identity with the vaccine stain. LOM strain does not appear safe; its use in the vaccine should be reconsidered. PMID:29553332

Daily intake of Jeju groundwater improves the skin condition of the model mouse for human atopic dermatitis.

PubMed

Tanaka, Akane; Jung, Kyungsook; Matsuda, Akira; Jang, Hyosun; Kajiwara, Naoki; Amagai, Yosuke; Oida, Kumiko; Ahn, Ginnae; Ohmori, Keitaro; Kang, Kyung-goo; Matsuda, Hiroshi

2013-03-01

Drinking water is an important nutrient for human health. The mineral ingredients included in drinking water may affect the physical condition of people. Various kinds of natural water are in circulation as bottled water in developed countries; however, its influence on clinical conditions of patients with certain diseases has not been fully evaluated. In this study, effects of the natural groundwater from Jeju Island on clinical symptoms and skin barrier function in atopic dermatitis (AD) were evaluated. NC/Tnd mice, a model for human AD, with moderate to severe dermatitis were used. Mice were given different natural groundwater or tap water for 8 weeks from 4 weeks of age. Clinical skin severity scores were recorded every week. Scratching analysis and measurement of transepidermal water loss were performed every other week. The pathological condition of the dorsal skin was evaluated histologically. Real-time polymerase chain reaction analysis was performed for cytokine expression in the affected skin. The epidermal hyperplasia and allergic inflammation were reduced in atopic mice supplied with Jeju groundwater when compared to those supplied with tap water or other kinds of natural groundwater. The increase in scratching behavior with the aggravation of clinical severity of dermatitis was favorably controlled. Moreover, transepidermal water loss that reflects skin barrier function was recovered. The early inflammation and hypersensitivity in the atopic skin was alleviated in mice supplied with Jeju groundwater, suggesting its profitable potential on the daily care of patients with skin troubles including AD. © 2013 Japanese Dermatological Association.

NASA Satellite Tracks Underwater Volcanic Eruption in Canary Islands

NASA Image and Video Library

2011-11-02

In July 2011, volcanic tremors began on the Island of El Hierro in the Canary Islands; by September, many tourists evacuated the resort island, fearing a volcanic eruption. This image is from NASA Terra spacecraft.

Reprint of “Performance analysis of a model-sized superconducting DC transmission system based VSC-HVDC transmission technologies using RTDS”

NASA Astrophysics Data System (ADS)

Dinh, Minh-Chau; Ju, Chang-Hyeon; Kim, Sung-Kyu; Kim, Jin-Geun; Park, Minwon; Yu, In-Keun

2013-01-01

The combination of a high temperature superconducting DC power cable and a voltage source converter based HVDC (VSC-HVDC) creates a new option for transmitting power with multiple collection and distribution points for long distance and bulk power transmissions. It offers some greater advantages compared with HVAC or conventional HVDC transmission systems, and it is well suited for the grid integration of renewable energy sources in existing distribution or transmission systems. For this reason, a superconducting DC transmission system based HVDC transmission technologies is planned to be set up in the Jeju power system, Korea. Before applying this system to a real power system on Jeju Island, system analysis should be performed through a real time test. In this paper, a model-sized superconducting VSC-HVDC system, which consists of a small model-sized VSC-HVDC connected to a 2 m YBCO HTS DC model cable, is implemented. The authors have performed the real-time simulation method that incorporates the model-sized superconducting VSC-HVDC system into the simulated Jeju power system using Real Time Digital Simulator (RTDS). The performance analysis of the superconducting VSC-HVDC systems has been verified by the proposed test platform and the results were discussed in detail.

Performance analysis of a model-sized superconducting DC transmission system based VSC-HVDC transmission technologies using RTDS

NASA Astrophysics Data System (ADS)

Dinh, Minh-Chau; Ju, Chang-Hyeon; Kim, Sung-Kyu; Kim, Jin-Geun; Park, Minwon; Yu, In-Keun

2012-08-01

The combination of a high temperature superconducting DC power cable and a voltage source converter based HVDC (VSC-HVDC) creates a new option for transmitting power with multiple collection and distribution points for long distance and bulk power transmissions. It offers some greater advantages compared with HVAC or conventional HVDC transmission systems, and it is well suited for the grid integration of renewable energy sources in existing distribution or transmission systems. For this reason, a superconducting DC transmission system based HVDC transmission technologies is planned to be set up in the Jeju power system, Korea. Before applying this system to a real power system on Jeju Island, system analysis should be performed through a real time test. In this paper, a model-sized superconducting VSC-HVDC system, which consists of a small model-sized VSC-HVDC connected to a 2 m YBCO HTS DC model cable, is implemented. The authors have performed the real-time simulation method that incorporates the model-sized superconducting VSC-HVDC system into the simulated Jeju power system using Real Time Digital Simulator (RTDS). The performance analysis of the superconducting VSC-HVDC systems has been verified by the proposed test platform and the results were discussed in detail.

Phylogenetic, histological and age determination for investigation of non-native tropical black-lip pearl oyster, Pinctada margaritifera, settled in jeju, Korea

NASA Astrophysics Data System (ADS)

Oh, Chulhong; Kim, Jin-Kyoung; Son, Young-Baek; Ju, Se-Jong; Jeung, Hee-Do; Yang, Hyun-Sung; Choi, Kwang-Sik; Le Moullac, Gilles; Kang, Do-Hyung

2017-12-01

This study reports the first finding of tropical blacklip pearl (BLP) oyster, Pinctada margaritifera, in Korean waters. One BLP oyster was found and sampled from Beom-seom islet (33°13'N, 126°33'E) in the southern coast of Jeju Island, Korea in February, 2011. The taxonomic status of the specimen was confirmed by nucleotide sequences of the mitochondrial gene cytochrome oxidase I and 28S ribosomal DNA. Oxygen isotopic analysis (δ18Osh) and histology were used to determine the specimen's age and reproductive stage, which were 3.5 years and ripe male, respectively. This BLP oyster most likely originated in an area in the subtropics or tropics, such as the Okinawa archipelagic or Micronesian regions. We suggest that intensive monitoring surveys are necessary for confirming the northward expansion of BLP oyster in Korean waters in the near future.

Tracing atmospheric transport of soil microorganisms and higher plant waxes in the East Asian outflow to the North Pacific Rim by using hydroxy fatty acids: Year-round observations at Gosan, Jeju Island

NASA Astrophysics Data System (ADS)

Tyagi, Poonam; Kawamura, Kimitaka; Kariya, Tadashi; Bikkina, Srinivas; Fu, Pingqing; Lee, Meehye

2017-04-01

Atmospheric transport of soil microorganisms and higher plant waxes in East Asia significantly influences the aerosol composition over the North Pacific. This study investigates the year-round atmospheric abundances of hydroxy fatty acids (FAs), tracers of soil microorganisms (β-isomers), and plant waxes (α- and ω-isomers), in total suspended particles collected at Gosan, Jeju Island, during April 2001 to March 2002. These hydroxy FAs showed a pronounced seasonality, higher concentrations in winter/spring and lower concentrations in summer/autumn, which are consistent with other tracers of soil microbes (trehalose), resuspended dust (nss-Ca2+), and stable carbon isotopic composition (δ13C) of total carbon. The molecular distributions of β-hydroxy FAs (predominance of C12 and C16 in winter/spring and summer/autumn, respectively) are consistent with those from a remote island (Chichijima) in the North Pacific and Asian dust standards (CJ-1 and CJ-2). This observation together with back trajectories over Gosan reveal that desert sources in China during winter and arid regions of Mongolia and Russian Far East during spring are the major contributors of soil microbes over the North Pacific. Predominance of ω-isomers (83%) over β-hydroxy FAs (16%) revealed a major contribution of terrestrial lipids from higher plant waxes over soil microbes in the East Asian outflow.

Population and forensic genetic analyses of mitochondrial DNA control region variation from six major provinces in the Korean population.

PubMed

Hong, Seung Beom; Kim, Ki Cheol; Kim, Wook

2015-07-01

We generated complete mitochondrial DNA (mtDNA) control region sequences from 704 unrelated individuals residing in six major provinces in Korea. In addition to our earlier survey of the distribution of mtDNA haplogroup variation, a total of 560 different haplotypes characterized by 271 polymorphic sites were identified, of which 473 haplotypes were unique. The gene diversity and random match probability were 0.9989 and 0.0025, respectively. According to the pairwise comparison of the 704 control region sequences, the mean number of pairwise differences between individuals was 13.47±6.06. Based on the result of mtDNA control region sequences, pairwise FST genetic distances revealed genetic homogeneity of the Korean provinces on a peninsular level, except in samples from Jeju Island. This result indicates there may be a need to formulate a local mtDNA database for Jeju Island, to avoid bias in forensic parameter estimates caused by genetic heterogeneity of the population. Thus, the present data may help not only in personal identification but also in determining maternal lineages to provide an expanded and reliable Korean mtDNA database. These data will be available on the EMPOP database via accession number EMP00661. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Site Amplification Characteristics of the Several Seismic Stations at Jeju Island, in Korea, using S-wave Energy, Background Noise, and Coda waves from the East Japan earthquake (Mar. 11th, 2011) Series.

NASA Astrophysics Data System (ADS)

Seong-hwa, Y.; Wee, S.; Kim, J.

2016-12-01

Observed ground motions are composed of 3 main factors such as seismic source, seismic wave attenuation and site amplification. Among them, site amplification is also important factor and should be considered to estimate soil-structure dynamic interaction with more reliability. Though various estimation methods are suggested, this study used the method by Castro et. al.(1997) for estimating site amplification. This method has been extended to background noise, coda waves and S waves recently for estimating site amplification. This study applied the Castro et. al.(1997)'s method to 3 different seismic waves, that is, S-wave Energy, Background Noise, and Coda waves. This study analysed much more than about 200 ground motions (acceleration type) from the East Japan earthquake (March 11th, 2011) Series of seismic stations at Jeju Island (JJU, SGP, HALB, SSP and GOS; Fig. 1), in Korea. The results showed that most of the seismic stations gave similar results among three types of seismic energies. Each station showed its own characteristics of site amplification property in low, high and specific resonance frequency ranges. Comparison of this study to other studies can give us much information about dynamic amplification of domestic sites characteristics and site classification.

Efficiency of producing anion and relative humidity of the indigenous woody plants in Jeju islands

NASA Astrophysics Data System (ADS)

Son, S.-G.; Kim, K.-J.; Kim, H.-J.; Kim, C.-M.; Byun, K.-O.

2009-04-01

This study is to evaluate the ability of interior plants to produce anion and relative humidity that can purify polluted indoor air. Four indigenous woody plants in Jeju islands such as Sarcandra glaber (Thunb.) Nakai, Illicium anisatum L, Cleyera japonica Thunb. and Ilex rotunda Thunb. were used. Sansevieria trifasciata cv. Laurentii was also used as a comparative plant. The amount of anion and increment of relative humidity produced by five species of indoor plants was assessed by anion measurement (ITC-201A)in a sealed acryl chamber (118Ã-118Ã-119.5cm). The highest amount of anion was 515 ea/cm3produced by I. rotunda. The amounts of anion were 293 ea/cm3, 273 ea/cm3, and 211 ea/cm3 in S. glaber, I. anisatum and C. japonica, respecively while it was 220 ea/cm3 in S. trifasciata. The increment of relative humidity was highest in I. anisatum as 27.4% while it was lowest in S. trifasciata as 14.0%. This result suggested that all four indigenous plants tested were more effective to purify the indoor polluted air than S. trifasciata. Key words: interior plant, S. glaber, I. anisatum, C. japonica, I. rotunda, indoor polluted air

Long term volcanic hazard analysis in the Canary Islands

NASA Astrophysics Data System (ADS)

Becerril, L.; Galindo, I.; Laín, L.; Llorente, M.; Mancebo, M. J.

2009-04-01

Historic volcanism in Spain is restricted to the Canary Islands, a volcanic archipelago formed by seven volcanic islands. Several historic eruptions have been registered in the last five hundred years. However, and despite the huge amount of citizens and tourist in the archipelago, only a few volcanic hazard studies have been carried out. These studies are mainly focused in the developing of hazard maps in Lanzarote and Tenerife islands, especially for land use planning. The main handicap for these studies in the Canary Islands is the lack of well reported historical eruptions, but also the lack of data such as geochronological, geochemical or structural. In recent years, the use of Geographical Information Systems (GIS) and the improvement in the volcanic processes modelling has provided an important tool for volcanic hazard assessment. Although this sophisticated programs are really useful they need to be fed by a huge amount of data that sometimes, such in the case of the Canary Islands, are not available. For this reason, the Spanish Geological Survey (IGME) is developing a complete geo-referenced database for long term volcanic analysis in the Canary Islands. The Canarian Volcanic Hazard Database (HADA) is based on a GIS helping to organize and manage volcanic information efficiently. HADA includes the following groups of information: (1) 1:25.000 scale geologic maps, (2) 1:25.000 topographic maps, (3) geochronologic data, (4) geochemical data, (5) structural information, (6) climatic data. Data must pass a quality control before they are included in the database. New data are easily integrated in the database. With the HADA database the IGME has started a systematic organization of the existing data. In the near future, the IGME will generate new information to be included in HADA, such as volcanological maps of the islands, structural information, geochronological data and other information to assess long term volcanic hazard analysis. HADA will permit having enough quality information to map volcanic hazards and to run more reliable models of volcanic hazards, but in addition it aims to become a sharing system, improving communication between researchers, reducing redundant work and to be the reference for geological research in the Canary Islands.

Tectonic Evolution and Midplate Volcanism in the South Pacific

DTIC Science & Technology

1999-02-01

documented in the South- ern Austral Island region of the South Pacific. A twelve degree clock- wise change in Pacific-Farallon relative motion occurred...and spreading fabric orientation. At the southeastern end of the Cook-Austral Island chain, multiple episodes of volcanism have left a diverse...in the flexural moat of the Austral Islands , probably associated with Austral Islands volcanism, which may contribute a significant amount of

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

NASA Astrophysics Data System (ADS)

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

2016-04-01

"Canary Islands: A volcanic window in the Atlantic Ocean" is an educational program born from the need to inform and educate citizens residing in the Canary Islands on the various hazards associated to volcanic phenomena. The Canary Islands is the only territory of Spain that hosts active volcanism, as is shown by the 16 historical eruptions that have occurred throughout this territory, being the last one a submarine eruption taking place on October 12, 2011, offshore El Hierro Island. In the last 7 years, ITER as well as INVOLCAN have been performing an educative program focused on educating to the population about the benefits of a volcanic territory, volcanic hazards, how to reduce volcanic risk and the management of volcanic risk in the Canary Islands. "Canary Islands: A volcanic window in the Atlantic Ocean" consists of three units, the first two dedicated to the IAVCEI/UNESCO videos "Understanding Volcanic Hazards" and "Reducing Volcanic Risk" and the third one dedicated to the management of volcanic risk in the Canary Islands, as well as some other aspects of the volcanic phenomena. Generally the three units are shown consecutively on Tuesday, Wednesday and Thursday. This educative program has been roaming all around the 88 municipalities of the archipelago since this initiative started in 2008. The total number of attendees since then amounts to 18,911 people. The increase of assistance was constant until 2011, with annual percentages of 7.8, 17.1 and 20.9 respectively, regarding to ratio assistant/municipality. Despite the heterogeneity of the audience, the main audience is related to aged people of 45 years and older. This could be related to the memories of the recent eruptions occurred at La Palma Island in 1949 and 1971. It is important to point out that many of those people attending the educative program are representatives of local government (i.e. civil protection). Regarding the interest of the audience, the educational program attendees have shown special interest on the possibility that a lateral collapse may occur in the volcanic edifices of Teide in Tenerife and Cumbre Vieja in La Palma. In addition, a volcanic trivial is provided to the attendees before the educative program starts. They have to answer to several questions directly related to each unit before and after the unit is taught, so it's possible to estimate the impact of the program. It's also important to highlight that after each unit ends, the rates of success in the answers sharply increase. Therefore, the ultimate goal of this educational program is to contribute to a better organized and informed community in relation to volcanic risk in Canary Islands and become much less vulnerable than a community that does not know or ignores volcanic hazards, and it is not organized to respond to them.

Earth observations taken from shuttle orbiter Atlantis during STS-84 mission

NASA Image and Video Library

1997-05-15

STS084-721-014 (15-24 May 1997) --- The island of Oahu is the third largest and most populated of the Hawaiian islands. The Koolau mountain range on the windward (northeastern) side of the island is obscured by clouds. Diamond Head, a circular feature on the southeastern end of the island is the result of volcanic activity more than 10,000 years ago. Honolulu International Airport is visible along the southern shore. The Waialua Mountains on the southwestern side of the island are also obscured by clouds. Pearl Harbor is at the center of the view. The Hawaiian islands, including Oahu are a product of hot spot volcanism, where a deep mantle plume generated by slow convective currents punches through the overlying plate, creating volcanic islands. Since Oahu has passed over this hot spot it is no longer volcanically active.

Symbiodinium spp. associated with high-latitude scleractinian corals from Jeju Island, South Korea

NASA Astrophysics Data System (ADS)

De Palmas, S.; Denis, V.; Ribas-Deulofeu, L.; Loubeyres, M.; Woo, S.; Hwang, S. J.; Song, J. I.; Chen, C. A.

2015-09-01

Most studies on endosymbiotic dinoflagellate algae (genus Symbiodinium) associated with scleractinian corals focus on tropical and sub-tropical reefs. Their diversity in outlying, non-reef coral communities at high latitudes is still not fully documented. In this study, we analyzed the Symbiodinium diversity associated with five scleractinian species collected at eight sites around Jeju Island (South Korea, 33.4°N) between 5 and 15 m depth. Denaturing gradient gel electrophoresis of amplified internal transcribed spacer region 2 distinguished five Symbiodinium types. We observed a high level of specificity between host genera and Symbiodinium spp. despite existing in an environment with large seasonal oscillations in temperature and light. Psammocora albopicta and Psammocora profundacella were associated with C1 and Montipora millepora with C17. Alveopora japonica was associated exclusively with an unusual F-type, the only known clade F representative functionally important to a scleractinian coral. Oulastrea crispata was associated with Symbiodinium boreum (type D15), occasionally co-occurring with type C3 (in 4 % of specimens). In addition to increasing the knowledge of Symbiodinium diversity in high-latitude coral communities, this study constitutes an important baseline upon which the effects of projected environmental change in the near future can be assessed. A better understanding of high-latitude coral communities is critical for understanding how a warming planet will affect the tempo and mode of shifts in the composition of temperate marine communities.

Topographic stress and catastrophic collapse of volcanic islands

NASA Astrophysics Data System (ADS)

Moon, S.; Perron, J. T.; Martel, S. J.

2017-12-01

Flank collapse of volcanic islands can devastate coastal environments and potentially induce tsunamis. Previous studies have suggested that factors such as volcanic eruption events, gravitational spreading, the reduction of material strength due to hydrothermal alteration, steep coastal cliffs, or sea level change may contribute to slope instability and induce catastrophic collapse of volcanic flanks. In this study, we examine the potential influence of three-dimensional topographic stress perturbations on flank collapses of volcanic islands. Using a three-dimensional boundary element model, we calculate subsurface stress fields for the Canary and Hawaiian islands to compare the effects of stratovolcano and shield volcano shapes on topographic stresses. Our model accounts for gravitational stresses from the actual shapes of volcanic islands, ambient stress in the underlying plate, and the influence of pore water pressure. We quantify the potential for slope failure of volcanic flanks using a combined model of three-dimensional topographic stress and slope stability. The results of our analysis show that subsurface stress fields vary substantially depending on the shapes of volcanoes, and can influence the size and spatial distribution of flank failures.

Barren Island west of Malaysia as seen from STS-67 Endeavour

NASA Image and Video Library

1995-03-14

Barren Island, a small volcanic island which is part of the Andaman Island group in the Andaman Sea west of Malaysia, began a new eruptive phase late in 1994. The STS-67 crew noticed the volcanic plume early in their flight, and had several opportunities to document the on-going eruption. This view, taken March 14, 1995, shows a healthy volcanic plume rising several thousand feet into the atmosphere. The main plume drifts westward over Andaman Island, although a smaller plume close to the ground is being dispersed to the south.

Morphology and molecular characterization of the epiphytic dinoflagellate Prorocentrum cf. rhathymum in temperate waters off Jeju Island, Korea

NASA Astrophysics Data System (ADS)

Lim, An Suk; Jeong, Hae Jin; Jang, Tae Young; Kang, Nam Seon; Lee, Sung Yeon; Yoo, Yeong Du; Kim, Hyung Seop

2013-03-01

Prorocentrum spp. are planktonic and/or benthic species. Benthic Prorocentrum species are of primary concern to scientists and the public because some of them are toxic. We established clonal cultures of 3 strains of Prorocentrum species that were collected from the thalli of a macroalga in the coastal waters off Jeju Island, located at the southern end of Korea. The Korean strains of P. cf. rhathymum, which are morphologically almost identical to the Virgin Island strain of P. rhathymum, were different from P. mexicanum because the former dinoflagellate has one simple collar-like spine in the periflagellar area, while the latter dinoflagellate has a 2- or 3-horned spine. In addition, the sequences of the small subunit (SSU) rDNA of the Korean strains were identical to those of the Malaysian and Floridian strains of P. rhathymum, while the sequences of the large subunit (LSU) rDNA of the Korean strains were 0.1-0.9% different from those of the Iranian and Malaysian strains of P. rhathymum. In phylogenetic trees based on the SSU rDNA sequences, the Korean strains of P. rhathymum formed a clade with the Malaysian and Floridian strains of P. rhathymum and the Vietnamese and Polynesian strains of P. mexicanum. However, in phylogenetic trees based on the LSU rDNA sequences, the Korean strains of P. rhathymum formed a clade with the Iranian strain of P. rhathymum and the Spanish and Mexican strains of P. mexicanum. Therefore, the molecular characterization of the Korean strains does not allow us to clearly classify them as P. rhathymum, nor P. mexicanum, although their morphology has so far been reported to be closer to that of P. rhathymum than P. mexicanum and thus we designated them as P. cf. rhathymum.

Submarine geology and geomorphology of active Sub-Antarctic volcanoes: Heard and McDonald Islands

NASA Astrophysics Data System (ADS)

Watson, S. J.; Coffin, M. F.; Whittaker, J. M.; Lucieer, V.; Fox, J. M.; Carey, R.; Arculus, R. J.; Bowie, A. R.; Chase, Z.; Robertson, R.; Martin, T.; Cooke, F.

2016-12-01

Heard and McDonald Islands (HIMI) are World Heritage listed sub-Antarctic active volcanic islands in the Southern Indian Ocean. Built atop the Kerguelen Plateau by Neogene-Quaternary volcanism, HIMI represent subaerial exposures of the second largest submarine Large Igneous Province globally. Onshore, processes influencing island evolution include glaciers, weathering, volcanism, vertical tectonics and mass-wasting (Duncan et al. 2016). Waters surrounding HIMI are largely uncharted, due to their remote location. Hence, the extent to which these same processes shape the submarine environment around HIMI has not been investigated. In early 2016, we conducted marine geophysical and geologic surveys around HIMI aboard RV Investigator (IN2016_V01). Results show that volcanic and sedimentary features prominently trend east-west, likely a result of erosion by the eastward flowing Antarctic Circumpolar Current and tidal currents. However, spatial patterns of submarine volcanism and sediment distribution differ substantially between the islands. >70 sea knolls surround McDonald Island suggesting substantial submarine volcanism. Geophysical data reveals hard volcanic seafloor around McDonald Island, whereas Heard Island is characterised by sedimentary sequences tens of meters or more thick and iceberg scours - indicative of glacial processes. Differences in submarine geomorphology are likely due to the active glaciation of Heard Island and differing rock types (Heard: alkali basalt, McDonald: phonolite), and dominant products (clastics vs. lava). Variations may also reflect different magmatic plumbing systems beneath the two active volcanoes (Heard produces larger volumes of more focused lava, whilst McDonald extrudes smaller volumes of more evolved lavas from multiple vents across the edifice). Using geophysical data, corroborated with new and existing geologic data, we present the first geomorphic map revealing the processes that shape the submarine environment around HIMI.

Earth Observations taken by the Expedition 17 Crew

NASA Image and Video Library

2008-05-13

ISS017-E-006820 (13 May 2008) --- Isla de la Palma in the Canary Islands is featured in this image photographed by an Expedition 17 crewmember on the International Space Station. The Canary Islands, a group of volcanic islands, lie just off the west coast of Morocco in the Atlantic Ocean; at the northwest end of the chain of islands is Isla de la Palma. According to scientists, the island started forming as a submarine volcano approximately 3-4 million years ago. Subaerial (above the water surface) volcanic activity and island formation began around 2 million years ago. Most geologists believe the Canary Islands formed over the remnants of an old "hotspot" in the mantle, or mantle plume. The residual hotspot melting produced the magma that resulted in the Canary Island volcanoes. While there is little evidence to support the current existence of a mantle plume, volcanic activity is still taking place -- the most recent lava flows on Isla de Palma were erupted in 1971. In addition to volcanic hazards, the Canary Islands are also subject to occasional dust storms originating in the Sahara Desert. This view highlights volcanic landforms on the southern portion of Isla de Palma. The elongated, 1949-meter high Cumbre Vieja volcanic center is characterized by numerous cinder cones, craters, and gray lava flows that punctuate the green vegetated hillslopes. To the north, the cities of El Paso and Los Llanos de Aridanes nestle against collapsed fragments of the Caldera Taburiente (left), formed by massive slope failure of an older volcanic center to the north. Tourism is a major component of the local economy, but the high mountains and clear air of Isla de la Palma are also attractive to astronomers -- several large observatories (not shown) are located along the northern edge of the Caldera Taburiente.

Lu-Hf and Sm-Nd isotope systematics of Korean spinel peridotites: A case for metasomatically induced Nd-Hf decoupling

NASA Astrophysics Data System (ADS)

Choi, Sung Hi; Mukasa, Samuel B.

2012-12-01

We determined the Lu-Hf and Sm-Nd isotope compositions of spinel peridotite xenoliths in alkali basalts from Baengnyeong and Jeju islands, South Korea, to constrain the timing of melt-depletion events and stabilization of the lithospheric mantle beneath the region. Equilibration temperatures estimated by two-pyroxene thermometry range from 780 to 950 °C, and from 960 to 1010 °C for Baengnyeong and Jeju peridotites, respectively. The Baengnyeong peridotite clinopyroxenes are characterized by extremely radiogenic Hf in association with isotopically less extreme Nd, resulting in strong Nd-Hf decoupling referenced to the mantle array. This is in stark contrast to the well-correlated isotopic compositions of Hf and Nd in the Jeju peridotite clinopyroxenes, which plot along the Nd-Hf mantle array. The Hf abundances and isotopic compositions of the Baengnyeong clinopyroxenes were less affected by relatively recent secondary enrichments that overprinted the light rare earth element abundances and Nd isotopes, causing the decoupling of the Nd-Hf isotopes. The Nd-Hf isotopic compositions of the Jeju peridotites appear to have been re-equilibrated, probably as a result of efficient diffusion at the relatively higher temperatures of the Jeju peridotites. Lu-Hf tie lines for clinopyroxene and orthopyroxene from four of the Korean peridotites have negative slopes on a Lu-Hf isochron diagram, yielding negative ages. This is interpreted to indicate recent isotopic exchange in orthopyroxene by reaction with metasomatic agents having low 176Hf/177Hf components. Secondary overprinting in orthopyroxene was facilitated by the considerably lower Hf concentrations than in co-located clinopyroxene. Baengnyeong lherzolite clinopyroxenes yield a Lu-Hf errorchron age of 1.9 ± 0.1 Ga, which is independently supported by a model Os age (based on Re depletion or TRD) of 1.8 Ga on a refractory Baengnyeong peridotite. We interpret this age range to mark the time of stabilization of the mantle section beneath this area by major melt extraction. This Proterozoic melt removal coincided in time with widespread ca. 2.1 to 1.8 Ga tectonothermal events documented throughout the Korean Peninsula. These observations indicate that the Lu-Hf system can be used to date mantle melting events recorded in lherzolite xenoliths.

Lu-Hf and Sm-Nd isotope systematics of Korean spinel peridotites: A case for metasomatically induced Nd-Hf decoupling

NASA Astrophysics Data System (ADS)

Choi, S.; Mukasa, S. B.

2012-12-01

We determined the Lu-Hf and Sm-Nd isotope compositions of spinel peridotite xenoliths in alkali basalts from Baengnyeong and Jeju islands, South Korea, to constrain the timing of melt-depletion events and stabilization of the lithospheric mantle beneath the region. Equilibration temperatures estimated by two-pyroxene thermometry range from 780 to 950°C, and from 960 to 1010°C for Baengnyeong and Jeju peridotites, respectively. The Baengnyeong peridotite clinopyroxenes are characterized by extremely radiogenic Hf in association with isotopically less extreme Nd, resulting in strong Nd-Hf decoupling referenced to the mantle array. This is in stark contrast to the well-correlated isotopic compositions of Hf and Nd in the Jeju peridotite clinopyroxenes, which plot along the Nd-Hf mantle array. The Hf abundances and isotopic compositions of the Baengnyeong clinopyroxenes were less affected by relatively recent secondary enrichments that overprinted the light rare earth element abundances and Nd isotopes, causing the decoupling of the Nd-Hf isotopes. The Nd-Hf isotopic compositions of the Jeju peridotites appear to have been re-equilibrated, probably as a result of efficient diffusion at the relatively higher temperatures of the Jeju peridotites. Lu-Hf tie lines for clinopyroxene and orthopyroxene from four of the Korean peridotites have negative slopes on a Lu-Hf isochron diagram, yielding negative ages. This is interpreted to indicate recent isotopic exchange in orthopyroxene by reaction with metasomatic agents having low 176Hf/177Hf components. Secondary overprinting in orthopyroxene was facilitated by the considerably lower Hf concentrations than in co-located clinopyroxene. Baengnyeong lherzolite clinopyroxenes yield a Lu-Hf errorchron age of 1.9 ± 0.1 Ga, which is independently supported by a model Os age (based on Re depletion or TRD) of 1.8 Ga on a refractory Baengnyeong peridotite. We interpret this age range to mark the time of stabilization of the mantle section beneath this area by major melt extraction. This Proterozoic melt removal coincided in time with widespread ca. 2.1 to 1.8 Ga tectonothermal events documented throughout the Korean Peninsula. These observations indicate that the Lu-Hf system can be used to date mantle melting events recorded in lherzolite xenoliths.

Draft genome of agar-degrading marine bacterium Gilvimarinus agarilyticus JEA5.

PubMed

Lee, Youngdeuk; Lee, Su-Jin; Park, Gun-Hoo; Heo, Soo-Jin; Umasuthan, Navaneethaiyer; Kang, Do-Hyung; Oh, Chulhong

2015-06-01

Gilvimarinus agarilyticus JEA5, which effectively degrades agar, was isolated from the seawater of Jeju Island, Republic of Korea. Here, we report the draft genome sequence of G. agarilyticus JEA5 with a total genome size of 4,179,438bp from 2 scaffolds (21 contigs) with 53.15% G+C content. Various polysaccharidases including 11 predicted agarases were observed from the draft genome of G. agarilyticus JEA5. Copyright © 2015 Elsevier B.V. All rights reserved.

Origin of seamount volcanism in northeast Indian Ocean with emphasis on Christmas Island

NASA Astrophysics Data System (ADS)

Taneja, R.; O'Neill, C.; Rushmer, T. A.; Jourdan, F.; Blichert-Toft, J.; Turner, S.; Lackie, M. A.

2012-12-01

The Northeast Indian Ocean has been a central point of research in the recent past due to its intraplate geophysical and geochemical characteristics. It is dominated by sub-aerial volcanic islands and submerged guyots and two islands, namely, Cocos (Keeling) Island and Christmas Island. Christmas Island, the focus of this study, consists of limestone and mafic intraplate volcanics. The origin of most of the features in northeast Indian Ocean is not fully understood. Christmas Island has experienced multiple stages of intraplate volcanic activity as previously established by 40Ar/39Ar radioisotopic analyses of basalts from the island (Hoernl et al., 2011). Here, we present new 40Ar/39Ar ages where the rock samples from Waterfall Spring (WS), Ethel Beach (EB) & Dolly Beach (DB) on the east coast of the island yielded plateau and mini-plateau ages of 37.75±0.77 Ma, 37.10±0.66 Ma and 43.37±0.45 Ma respectively, whereas a sample from Flying Fish Cove (FFC) in the north of the island yielded a minimum age of 38.6±0.5 Ma. All these units are part of the Lower Volcanics Series. The samples from the west coast (Winifred Beach, WB) are younger with an age of 4.32 ± 0.17 Ma, and are part of the Upper Volcanic Series. This confirms two stages of volcanism at the island with a gap of around 38 Ma. The 40Ar/39Ar radioisotopic ages were overlayed on Gplates and seismic tomography models to determine its paleo motion. The present position of the island is 10.5°S, 105.5°E. During Eocene its reconstructed position was 30°S latitude. Seismic tomography models have highlighted a low velocity zone beneath the island during Eocene. Geochemically, the two volcanic suites (Upper & Lower) are mostly similar in their major and trace element composition. The majority of localities (WS, EB, and WB) are basanites; where as that from Dolly Beach is basaltic. The Dale's (west coast), are trachyte and appear evolved with high SiO2. They also have low Ba and Sr ~25ppm, whereas those from east coast have 550 - 900 ppm Sr. Despite an age difference of more than 38 Ma, there is no significant difference between Hf, Nd and Pb isotopic signatures of the Upper Volcanic and Lower Volcanic series which show an enriched component, interpreted by Hoernle et.al (2011) to be due to contamination by continental material. This signifies a common homogenous source for a period of more than 40 Ma in contrast to many OIBs. Dale's do have a distinct isotopic character from the Lower Volcanic Series and this signature is still under study. These geochemical analyses from the island broadly lie within those sampled by Hoernle et al. (2011) from their regional study. Here, we are looking at the island in detail. We present geochronological, geophysical and geochemical data from the island which addresses this model using Christmas Island as an example. Ref: Hoernle et al., 2011, Origin of Indian Ocean Seamount Province by shallow recycling of continental lithosphere, Nature Geoscience 4: 883-887

New 40Ar / 39Ar age and geochemical data from seamounts in the Canary and Madeira volcanic provinces: Support for the mantle plume hypothesis

NASA Astrophysics Data System (ADS)

Geldmacher, J.; Hoernle, K.; Bogaard, P. v. d.; Duggen, S.; Werner, R.

2005-08-01

The role of mantle plumes in the formation of intraplate volcanic islands and seamount chains is being increasingly questioned. Particular examples are the abundant and somewhat irregularly distributed island and seamount volcanoes off the coast of northwest Africa. New 40Ar / 39Ar ages and Sr-Nd-Pb isotope geochemistry of volcanic rocks from seamounts northeast of the Madeira Islands (Seine and Unicorn) and northeast of the Canary Islands (Dacia and Anika), however, provide support for the plume hypothesis. The oldest ages of shield stage volcanism from Canary and Madeira volcanic provinces confirm progressions of increasing age to the northeast. Average volcanic age progression of ∼1.2 cm/a is consistent with rotation of the African plate at an angular velocity of ∼0.20° ± 0.05 /Ma around a common Euler pole at approximately 56° N, 45° W computed for the period of 0-35 Ma. A Euler pole at 35° N, 45° W is calculated for the time interval of 35-64 Ma. The isotope geochemistry further confirms that the Madeira and Canary provinces are derived from different sources, consistent with distinct plumes having formed each volcanic group. Conventional hotspot models, however, cannot easily explain the up to 40 m.y. long volcanic history at single volcanic centers, long gaps in volcanic activity, and the irregular distribution of islands and seamounts in the Canary province. A possible explanation could involve interaction of the Canary mantle plume with small-scale upper mantle processes such as edge-driven convection. Juxtaposition of plume and non-plume volcanism could also account for observed inconsistencies of the classical hotspot concept in other volcanic areas.

Nannofossils in 2011 El Hierro eruptive products reinstate plume model for Canary Islands

NASA Astrophysics Data System (ADS)

Zaczek, Kirsten; Troll, Valentin R.; Cachao, Mario; Ferreira, Jorge; Deegan, Frances M.; Carracedo, Juan Carlos; Soler, Vicente; Meade, Fiona C.; Burchardt, Steffi

2015-01-01

The origin and life cycle of ocean islands have been debated since the early days of Geology. In the case of the Canary archipelago, its proximity to the Atlas orogen led to initial fracture-controlled models for island genesis, while later workers cited a Miocene-Quaternary east-west age-progression to support an underlying mantle-plume. The recent discovery of submarine Cretaceous volcanic rocks near the westernmost island of El Hierro now questions this systematic age-progression within the archipelago. If a mantle-plume is indeed responsible for the Canaries, the onshore volcanic age-progression should be complemented by progressively younger pre-island sedimentary strata towards the west, however, direct age constraints for the westernmost pre-island sediments are lacking. Here we report on new age data obtained from calcareous nannofossils in sedimentary xenoliths erupted during the 2011 El Hierro events, which date the sub-island sedimentary rocks to between late Cretaceous and Pliocene in age. This age-range includes substantially younger pre-volcanic sedimentary rocks than the Jurassic to Miocene strata known from the older eastern islands and now reinstate the mantle-plume hypothesis as the most plausible explanation for Canary volcanism. The recently discovered Cretaceous submarine volcanic rocks in the region are, in turn, part of an older, fracture-related tectonic episode.

Nannofossils in 2011 El Hierro eruptive products reinstate plume model for Canary Islands.

PubMed

Zaczek, Kirsten; Troll, Valentin R; Cachao, Mario; Ferreira, Jorge; Deegan, Frances M; Carracedo, Juan Carlos; Soler, Vicente; Meade, Fiona C; Burchardt, Steffi

2015-01-22

The origin and life cycle of ocean islands have been debated since the early days of Geology. In the case of the Canary archipelago, its proximity to the Atlas orogen led to initial fracture-controlled models for island genesis, while later workers cited a Miocene-Quaternary east-west age-progression to support an underlying mantle-plume. The recent discovery of submarine Cretaceous volcanic rocks near the westernmost island of El Hierro now questions this systematic age-progression within the archipelago. If a mantle-plume is indeed responsible for the Canaries, the onshore volcanic age-progression should be complemented by progressively younger pre-island sedimentary strata towards the west, however, direct age constraints for the westernmost pre-island sediments are lacking. Here we report on new age data obtained from calcareous nannofossils in sedimentary xenoliths erupted during the 2011 El Hierro events, which date the sub-island sedimentary rocks to between late Cretaceous and Pliocene in age. This age-range includes substantially younger pre-volcanic sedimentary rocks than the Jurassic to Miocene strata known from the older eastern islands and now reinstate the mantle-plume hypothesis as the most plausible explanation for Canary volcanism. The recently discovered Cretaceous submarine volcanic rocks in the region are, in turn, part of an older, fracture-related tectonic episode.

Hawaiian Island Archipelago

NASA Image and Video Library

1985-06-24

The entire Hawaiian Island Archipelago (21.5N, 158.0W) is seen in this single view. The islands are a favorite international resort and tourist attraction drawing visitors from all over the world to enjoy the tropical climate, year round beaches and lush island flora. Being volcanic in origin, the islands' offer a rugged landscape and on the big island of Hawaii, there is still an occasional volcanic eruption of lava flows and steam vents.

Introduction - The impacts of the 2008 eruption of Kasatochi Volcano on terrestrial and marine ecosystems in the Aleutian Islands, Alaska

USGS Publications Warehouse

DeGange, Anthony R.; Byrd, G. Vernon; Walker, Lawrence R.; Waythomas, C.F.

2010-01-01

The Aleutian Islands are situated on the northern edge of the so-called “Pacific Ring of Fire,” a 40,000-km-long horseshoe-shaped assemblage of continental landmasses and islands bordering the Pacific Ocean basin that contains many of the world's active and dormant volcanoes. Schaefer et al. (2009) listed 27 historically active volcanoes in the Aleutian Islands, of which nine have had at least one major eruptive event since 1990. Volcanic eruptions are often significant natural disturbances, and ecosystem responses to volcanic eruptions may vary markedly with eruption style (effusive versus explosive), frequency, and magnitude of the eruption as well as isolation of the disturbed sites from potential colonizing organisms (del Moral and Grishin, 1999). Despite the relatively high frequency of volcanic activity in the Aleutians, the response of island ecosystems to volcanic disturbances is largely unstudied because of the region's isolation. The only ecological studies in the region that address the effects of volcanic activity were done on Bogoslof Island, a remote, highly active volcanic island in the eastern Aleutians, which grew from a submarine eruption in 1796 (Merriam, 1910; Byrd et al., 1980; Byrd and Williams, 1994). Nevertheless, in the 214 years of Bogoslof's existence, the island has been visited only intermittently.Kasatochi Island is a small (2.9 km by 2.6 km, 314 m high) volcano in the central Aleutian Islands of Alaska (52.17°N latitude, 175.51°W longitude; Fig. 1) that erupted violently on 7-8 August 2008 after a brief, but intense period of precursory seismic activity (Scott et al., 2010 [this issue]; Waythomas et al., in review). The island is part of the Aleutian arc volcanic front, and is an isolated singular island. Although the immediate offshore areas are relatively shallow (20–50 m water depth), the island is about 10 km south of the 2000 m isobath, north of which, ocean depths increase markedly. Kasatochi is located between the deepwater basin of the Bering Sea to the north and shallower areas of intense upwelling in Atka and Fenimore Passes in the North Pacific Ocean to the south. This area apparently produces high marine productivity based on concentrations of feeding marine birds and mammals (see Drew et al., 2010 [this issue]). Kasatochi is about 85 km northeast of Adak, the nearest community and a regional transportation hub, and about 19 km northwest of the western end of Atka Island. The nearest historically active volcanoes are Great Sitkin volcano, about 35 km to the west, and Korovin volcano on Atka Island, about 94 km to the east. Koniuji Island, another small volcanic island, is located about 25 km east of Kasatochi (Fig. 1).

Improving communication during volcanic crises on small, vulnerable islands

NASA Astrophysics Data System (ADS)

McGuire, W. J.; Solana, M. C.; Kilburn, C. R. J.; Sanderson, D.

2009-05-01

Increased exposure to volcanic hazard, particularly at vulnerable small islands, is driving an urgent and growing need for improved communication between monitoring scientists, emergency managers and the media, in advance of and during volcanic crises. Information gathering exercises undertaken on volcanic islands (Guadeloupe, St. Vincent and Montserrat) in the Lesser Antilles (eastern Caribbean), which have recently experienced - or are currently experiencing - volcanic action, have provided the basis for the compilation and publication of a handbook on Communication During Volcanic Emergencies, aimed at the principal stakeholder groups. The findings of the on-island surveys point up the critical importance of (1) bringing together monitoring scientists, emergency managers, and representatives of the media, well in advance of a volcanic crisis, and (2), ensuring that procedures and protocols are in place that will allow, as far as possible, effective and seamless cooperation and coordination when and if a crisis situation develops. Communication During Volcanic Emergencies is designed to promote and encourage both of these priorities through providing the first source-book addressing working relationships and inter-linkages between the stakeholder groups, and providing examples of good and bad practice. While targeting the volcanic islands of the eastern Caribbean, the source-book and its content are largely generic, and the advice and guidelines contained therein have equal validity in respect of improving communication before and during crises at any volcano, and have application to the communication issue in respect of a range of other geophysical hazards.

Seasonal variations of diacids, ketoacids, and α-dicarbonyls in aerosols at Gosan, Jeju Island, South Korea: Implications for sources, formation, and degradation during long-range transport

NASA Astrophysics Data System (ADS)

Kundu, Shuvashish; Kawamura, Kimitaka; Lee, Meehye

2010-10-01

Aerosol samples (n = 84) were collected continuously from April 2003 to April 2004 at Gosan site in Jeju Island, South Korea. The samples were analyzed for diacids, ketoacids, and α-dicarbonyls, as well as organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and water-soluble inorganic ions. Oxalic acid (C2) was the most abundant followed by malonic acid (C3) in all the seasons. The mean concentration (784 ng m-3) of total diacids (C2-C12) and their relative abundances in total organic species detected, OC and WSOC were found to be the highest in summer, whereas those of ketoacids and dicarbonyls were the highest in winter. The annual mean contributions of diacids, ketoacids, and dicarbonyls to WSOC are 12, 1, and 0.4%, respectively. They are several times higher than those reported in East Asia from which air masses are transported to Gosan, indicating an importance of photochemical processing of aerosols during a long-range transport. Diacids and related compounds show different seasonal variations, suggesting their season-specific sources and photochemical processing. This study demonstrates an enhanced photochemical production and degradation of water-soluble organics in summer. In contrast, higher positive correlations between combustion tracers (non-sea-salt K+ and EC) and diacids and related compounds were observed in the winter, pointing out higher emission of diacids and related compounds or their precursors from fossil fuel/biomass burning.

Historic hydrovolcanism at Deception Island (Antarctica): implications for eruption hazards

NASA Astrophysics Data System (ADS)

Pedrazzi, Dario; Németh, Károly; Geyer, Adelina; Álvarez-Valero, Antonio M.; Aguirre-Díaz, Gerardo; Bartolini, Stefania

2018-01-01

Deception Island (Antarctica) is the southernmost island of the South Shetland Archipelago in the South Atlantic. Volcanic activity since the eighteenth century, along with the latest volcanic unrest episodes in the twentieth and twenty-first centuries, demonstrates that the volcanic system is still active and that future eruptions are likely. Despite its remote location, the South Shetland Islands are an important touristic destination during the austral summer. In addition, they host several research stations and three summer field camps. Deception Island is characterised by a Quaternary caldera system with a post-caldera succession and is considered to be part of an active, dispersed (monogenetic), volcanic field. Historical post-caldera volcanism on Deception Island involves monogenetic small-volume (VEI 2-3) eruptions such forming cones and various types of hydrovolcanic edifices. The scientific stations on the island were destroyed, or severely damaged, during the eruptions in 1967, 1969, and 1970 mainly due to explosive activity triggered by the interaction of rising (or erupting) magma with surface water, shallow groundwater, and ice. We conducted a detailed revision (field petrology and geochemistry) of the historical hydrovolcanic post-caldera eruptions of Deception Island with the aim to understand the dynamics of magma-water interaction, as well as characterise the most likely eruptive scenarios from future eruptions. We specifically focused on the Crimson Hill (estimated age between 1825 and 1829), and Kroner Lake (estimated age between 1829 and 1912) eruptions and 1967, 1969, and 1970 events by describing the eruption mechanisms related to the island's hydrovolcanic activity. Data suggest that the main hazards posed by volcanism on the island are due to fallout, ballistic blocks and bombs, and subordinate, dilute PDCs. In addition, Deception Island can be divided into five areas of expected activity due to magma-water interaction, providing additional data for correct hazard assessment on the island.

Earth Observations taken by the Expedition 17 Crew

NASA Image and Video Library

2008-06-20

ISS017-E-009734 (20 June 2008) --- Island of Ischia, Italy is featured in this image photographed by an Expedition 17 crewmember on the International Space Station. The island of Ischia is located approximately 30 kilometers to the southwest of Naples, in the western Bay of Naples (part of the Tyrrenhian Sea). While the island's rocks are volcanic in origin, much of the island's geology and current appearance is characterized by uplifted -- horst -- and downdropped -- graben -- fault structures. For example, the highest point on the island of Ischia is Monte Epomeo (789 meters). The mountain is not a volcanic cone, but rather is composed of erupted materials uplifted by faulting. The green slopes of Monte Epomeo are enclosed by urban development (light grey speckled areas) that rings the island. According to scientists, the last volcanic activity on Ischia took place in 1302. The neighboring island of Procida (top right) was formed from the same magma sources as Ischia, and scientists believe it likely shared the same volcanic "plumbing system". Today, the island of Ischia is a popular tourist destination due to its hot springs, hot mud baths, and the hiking opportunities afforded by Monte Epomeo. Several boat wakes are visible around both islands in this view.

Geology of a Stable Intraplate Region: The Cape Verde/Canary Basin,

DTIC Science & Technology

1982-03-01

reflection records indicate a possible Eocene age up- lifting. Extensive island volcanism and sill and dike emplacement occurred during Miocene. Many abyssal...hills and small scale faults are related to this Miocene tectonic phase. Island volcanism has a con- tinuing influence on the sedimentary sections. The...Plate is capable of generating zones of weak- nesses. These weakness zones could be expected to localize island volcanism , create north/south-trending

Improved ROS defense in the swimbladder of a facultative air-breathing erythrinid fish, jeju, compared to a non-air-breathing close relative, traira.

PubMed

Pelster, Bernd; Giacomin, Marina; Wood, Chris M; Val, Adalberto L

2016-07-01

The jeju Hoplerythrinus unitaeniatus and the traira Hoplias malabaricus are two closely related erythrinid fish, both possessing a two-chambered physostomous swimbladder. In the jeju the anterior section of the posterior bladder is highly vascularized and the swimbladder is used for aerial respiration; the traira, in turn, is a water-breather that uses the swimbladder as a buoyancy organ and not for aerial oxygen uptake. Observation of the breathing behavior under different levels of water oxygenation revealed that the traira started aquatic surface respiration only under severe hypoxic conditions and did not breathe air. In the jeju air-breathing behavior was observed under normoxic conditions, and the frequency of air-breathing was significantly increased under hypoxic conditions. Unexpectedly, even under hyperoxic conditions (30 mg O2 L(-1)) the jeju continued to take air breaths, and compared with normoxic conditions the frequency was not reduced. Because the frequently air-exposed swimbladder tissue faces higher oxygen partial pressures than normally experienced by other fish tissues, it was hypothesized that in the facultative air-breathing jeju, swimbladder tissue would have a higher antioxidative capacity than the swimbladder tissue of the water breathing traira. Measurement of total glutathione (GSSG/GSH) concentration in anterior and posterior swimbladder tissue revealed a higher concentration of this antioxidant in swimbladder tissue as compared to muscle tissue in the jeju. Furthermore, the GSSG/GSH concentration in jeju tissues was significantly higher than in traira tissues. Similarly, activities of enzymes involved in the breakdown of reactive oxygen species were significantly higher in the jeju swimbladder as compared to the traira swimbladder. The results show that the jeju, using the swimbladder as an additional breathing organ, has an enhanced antioxidative capacity in the swimbladder as compared to the traira, using the swimbladder only as a buoyancy organ.

Long-term (17 Ma) turbidite record of the timing and frequency of large flank collapses of the Canary Islands

NASA Astrophysics Data System (ADS)

Hunt, J. E.; Talling, P. J.; Clare, M. A.; Jarvis, I.; Wynn, R. B.

2014-08-01

Volcaniclastic turbidites on the Madeira Abyssal Plain provide a record of large-volume volcanic island flank collapses from the Canary Islands. This long-term record spans 17 Ma, and comprises 125 volcaniclastic beds. Determining the timing, provenance and volumes of these turbidites provides key information about the occurrence of mass wasting from the Canary Islands, especially the western islands of Tenerife, La Palma and El Hierro. These turbidite records demonstrate that landslides often coincide with protracted periods of volcanic edifice growth, suggesting that loading of the volcanic edifices may be a key preconditioning factor for landslide triggers. Furthermore, the last large-volume failures from Tenerife coincide with explosive volcanism at the end of eruptive cycles. Many large-volume Canary Island landslides also occurred during periods of warmer and wetter climates associated with sea-level rise and subsequent highstand. However, these turbidites are not serially dependent and any association with climate or sea level change is not statistically significant.

Assessing qualitative long-term volcanic hazards at Lanzarote Island (Canary Islands)

NASA Astrophysics Data System (ADS)

Becerril, Laura; Martí, Joan; Bartolini, Stefania; Geyer, Adelina

2017-07-01

Conducting long-term hazard assessment in active volcanic areas is of primary importance for land-use planning and defining emergency plans able to be applied in case of a crisis. A definition of scenario hazard maps helps to mitigate the consequences of future eruptions by anticipating the events that may occur. Lanzarote is an active volcanic island that has hosted the largest (> 1.5 km3 DRE) and longest (6 years) eruption, the Timanfaya eruption (1730-1736), on the Canary Islands in historical times (last 600 years). This eruption brought severe economic losses and forced local people to migrate. In spite of all these facts, no comprehensive hazard assessment or hazard maps have been developed for the island. In this work, we present an integrated long-term volcanic hazard evaluation using a systematic methodology that includes spatial analysis and simulations of the most probable eruptive scenarios.

Tenarife Island, Canary Island Archipelago, Atlantic Ocean

NASA Technical Reports Server (NTRS)

1991-01-01

Tenarife Island is one of the most volcanically active of the Canary Island archipelago, Atlantic Ocean, just off the NW coast of Africa, (28.5N, 16.5W). The old central caldera, nearly filled in by successive volcanic activity culminating in two stratocones. From those two peaks, a line of smaller cinder cones extend to the point of the island. Extensive gullies dissect the west side of the island and some forests still remain on the east side.

Tenarife Island, Canary Island Archipelago, Atlantic Ocean

NASA Image and Video Library

1991-08-11

Tenarife Island is one of the most volcanically active of the Canary Island archipelago, Atlantic Ocean, just off the NW coast of Africa, (28.5N, 16.5W). The old central caldera, nearly filled in by successive volcanic activity culminating in two stratocones. From those two peaks, a line of smaller cinder cones extend to the point of the island. Extensive gullies dissect the west side of the island and some forests still remain on the east side.

The Lanzarote Geodynamic Laboratory: new capabilities for monitoring of volcanic activity at Canary Islands

NASA Astrophysics Data System (ADS)

Arnoso, J.; Vélez, E. J.; Soler, V.; Montesinos, F. G.; Benavent, M.

2012-04-01

The volcanic island of Lanzarote is located at the northeastern end of the Canary Islands. Together with Fuerteventura Island, Lanzarote constitutes the emergent part of the East Canary Ridge, which presents a NNE-SSW volcanic alignment. Last eruptive events took place in 1824 and during the period 1730-1736, which is the largest to occur in the archipelago and throw out about 1.3 km3 of volcanic materials. The Lanzarote Geodynamic Laboratory (LGL) was created in 1986 with the idea of making Lanzarote as a natural laboratory to carry out studies in order to acquire more knowledge about its origin, present status and evolution (Vieira et al., 1991; 2006). The LGL has a multidisciplinary scientific purpose and, among others, various objectives are devoted to investigate mass distribution in the Earth system and surface displacements associated to volcanic and/or seismic activity in the island. The influence of LGL is extended throughout the whole geographical area of Lanzarote, including small islands located at the north. The laboratory has 3 observing modules distributed along the island according to its infrastructure and scientific objectives, where more than 70 sensors are recording continuously gravity variations, ground deformations, sea level, seismic activity, meteorological parameters, etc. All these observations are supplemented by periodic measurement of geodetic and geophysical networks that allow us to make studies at local, insular and regional scales. The application of geodetic and geophysical techniques to identify geodynamic signals related to volcanic processes is then a permanent research activity of the laboratory. Nowadays, this fact becomes more interesting due to the ongoing volcanic eruption that is taking place in other island of the Canary Archipelago, El Hierro, since past July 2011. That is, the multidisciplinary research carry on up to now at the LGL allow us to apply multiparameter observations of different kinds of volcanic manifestations at the surface level, and to compare geodynamic processes associated with an active area of the Earth's crust. In turn, the results obtained can provide new inputs for studying precursor of volcanic activity and also contribute to volcanic hazard mitigation. The LGL aims to be a permanent status of renewal, using new technologies for data recording and real time transmission, as well as for testing new sensors, scientific equipment and observational techniques related to monitoring and observation of volcanic activity. All these capabilities are necessary when high-resolution ground based observations must provide us the basis for studying the sources of volcanic deformation. The laboratory is thus open to support and to enhance the collaboration among scientists, as well as national and international institutions involved in research at active volcanic areas.

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

USGS Publications Warehouse

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

2014-01-01

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

Non-Hawaiian lithostratigraphy of Louisville seamounts and the formation of high-latitude oceanic islands and guyots

NASA Astrophysics Data System (ADS)

Buchs, David M.; Williams, Rebecca; Sano, Shin-ichi; Wright, V. Paul

2018-05-01

Guyots are large seamounts with a flat summit that is generally believed to form due to constructional biogenic and/or erosional processes during the formation of volcanic islands. However, despite their large abundance in the oceans, there are still very few direct constraints on the nature and formation of guyots, in particular those formed at high latitude that lack a thick cap of shallow-marine carbonate rocks. It is largely accepted based on geophysical constraints and surficial observations/sampling that the summit platform of these guyots is shaped by wave abrasion during post-volcanic subsidence of volcanic islands. Here we provide novel constraints on this hypothesis and the summit geology of guyots with a lithostratigraphic analysis of cores from three Louisville seamounts (South Pacific) collected during Expedition 330 of the Integrated Ocean Drilling Program (IODP). Thirteen lithofacies of sedimentary and volcanic deposits are described, which include facies not previously recognized on the top of guyots, and offer a new insight into the formation of high-latitude oceanic islands on a fast-moving plate. Our results reveal that the lithostratigraphy of Louisville seamounts preserves a very consistent record of the formation and drowning of volcanic islands, with from bottom to top: (i) volcaniclastic sequences with abundant lava-fed delta deposits, (ii) submarine to subaerial shield lava flows, (iii) post-volcanic shallow to deeper marine sedimentary rocks lacking thick reef deposits, (iv) post-erosional rejuvenated volcanic rocks, and (v) pelagic sediments. Recognition of erosional boundaries between subaerial lava flows and shallow-marine sedimentary rocks provides novel support for post-volcanic wave planation of guyots. However, the summit geology of Louisville seamounts is dissimilar to that of high-latitude Hawaiian-Emperor guyots that have emplaced in a similar tectonic and environmental setting and that include thicker lava stacks with apparently little lava-fed delta deposits. To explain observed lithostratigraphic discrepancy we propose that Louisville seamounts represent a distinct type of intraplate ocean volcano characterized by formation of a smaller island, with a central shield volcano surrounded by extended shallow-marine shelves formed by lava-fed deltas. In this interpretation the summit platform of Louisville-type guyots results from early (syn-volcanic) subaerial to shallow-marine constructional volcanic processes and marine erosion, enhanced by later (post-volcanic) wave planation. This contrasts with larger Hawaiian edifices that are capped by thicker shield volcanoes, and that develop an extended wave planation surface during post-volcanic subsidence (in the absence of efficient coral growth). The difference between Hawaiian- and Louisville-type volcanic islands and guyots can be explained by contrasted dynamic disequilibrium between magmatic growth, erosion, and subsidence during the island-building stage. Unlike Hawaiian-type volcanoes, Louisville seamounts are characterized by alkaline magmatism that extends from the late seamount to island stages. This supports more limited magmatic growth during the formation of Louisville islands, and we hypothesize that this promotes the formation of ephemeral shallow-marine platforms and extended lava-fed deltas. Hawaiian-type volcanoes and guyots are unusually large in the population of intraplate ocean volcanoes. Louisville-type guyots as defined in this study could therefore represent a very common but yet poorly documented mode of oceanic island formation in the Pacific Ocean and other similar fast-moving plate settings.

Earth observations taken from shuttle orbiter Atlantis during STS-84 mission

NASA Image and Video Library

1997-05-20

STS084-712-003 (15-24 May 1997) --- Early morning sun highlights the volcanic features on Onekotan Island which is one of several volcanic islands in the Russian owned Kurile Island chain. Onekotan lies just south of Kamchatka. Two volcanoes are active on the island -- the small island surrounded by a moat-like lake in the south (Tao-Rusyr caldera) last erupted in 1952, and the cone-shaped peak at the north end of the island, Nemo peak, erupted in 1938.

Island of Timor, Indonesia

NASA Image and Video Library

1989-11-27

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

Geochemical Characterization of Endmember Mantle Components

DTIC Science & Technology

2005-06-01

from the oceanic crust and volcanic edifice beneath Gran Canaria (Canary Islands); consequences for crustal contamination of ascending magmas, Chemical...Enriched Mantle II (EM2) Endmember: Evidence from the Samoan Volcanic Chain .................................................... 19 Abstract...DMM). On the other hand, ocean island basalts (OIBs), erupted by hotspot volcanism , are isotopically heterogeneous in terms of most radiogenic

Volcanic Island Appears Near Tonga

NASA Astrophysics Data System (ADS)

Zielinski, Sarah

2006-11-01

A volcano known as Home Reef is now believed to be the source of a small island that appeared recently in Tonga, accordingto scientists from the Smithsonian Institution's Global Volcanism Program who had initially placed the location of the eruption and resulting island at nearby Metis Shoal. Mariners onboard the yacht Maiken

Molecular distribution, seasonal variation, chemical transformation and sources of dicarboxylic acids and related compounds in atmospheric aerosols at remote marine Gosan site, Jeju Island

NASA Astrophysics Data System (ADS)

Kundu, S.; Kawamura, K.; Lee, M.

2009-12-01

: A homologous series of C2-C12 α, ω-dicarboxylic acids, ω-oxocarboxylic acids (C2-C9), pyruvic acid and α-dicarbonyls (C2-C3) were detected in atmospheric aerosols collected between April 2003 and April 2004 from remote marine Gosan site (33°29‧ N, 126°16‧ E) located in Jeju Island, South Korea. They were determined using a GC-FID and GC/MS. Total diacid concentration ranged from 130 to 1911 ng m-3 (av. 642 ng m-3), whereas total oxoacid concentration ranged from 7 to 155 ng m-3 (av. 43 ng m-3), and pyruvic acid and α-dicarbonyls ranged from 0.5 to 15 ng m-3 (av. 5 ng m-3) and 2-108 ng m-3 (av. 17.3 ng m-3), respectively. Oxalic (C2) acid was the most abundant in all seasons followed by malonic (C3) or succinic (C4) acid, and phthalic (Ph) acid. The concentration of diacids decreased with an increase in carbon number except for azelaic (C9) acid, which was more abundant than suberic (C8) acid. Glyoxylic acid was predominant ω-oxoacid contributing to 92% of total ω-oxoacid. Total diacids, oxoacids and dicarbonyls showed maximum concentrations in spring and occasionally in winter, while minimum concentrations were observed in summer. Air mass trajectory analysis suggests that either spring or winter maxima can be explained by strong continental outflow associated with cold front passages, while summer minima are associated with warm southerly flows, which transport clean marine air from low latitudes to Jeju Island. The comparison between total diacid concentration level of this study and other study results of urban and remote sites of East Asia reveals that Gosan site is more heavily influenced by the continental outflow from China. The seasonal variation of malonic/succinic (C3/C4), malic/succinic (hC4/C4), fumaric/maleic (F/M), oxalic/pyruvic (C2/Py) and oxalic/Glyoxal (C2/Gly) ratios showed maxima in summer due to an enhanced photo-production and degradation of diacids and related compounds. Throughout all seasons C3/C4 ratio at Gosan site, located between Chinese cities and Chichi-jima Island in Japan was observed higher than those in Chinese cities and lower than that of the Chichi-jima Island, pointing to the formation of diacid during long range transport. The lowest values of adipic/azelaic (C6/C9) and phthalic/azelaic (Ph/C9) were observed as a result of the overwhelming biogenic emission of the precursors (e.g., unsaturated fatty acids) of azelaic acid in summer.In this study, we will also discuss the sources and transport pathways of diacids and related compounds resolved using a hybrid receptor model, potential source contribution function (PSCF) and model results will be compared with available in-situ observations in East Asia.

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

NASA Astrophysics Data System (ADS)

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

2014-12-01

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

Paleomagnetism of the Late Triassic Hound Island Volcanics: Revisited

USGS Publications Warehouse

Haeussler, Peter J.; Coe, Robert S.; Onstott, T.C.

1992-01-01

The collision and accretion of the Alexander terrane profoundly influenced the geologic history of Alaska and western Canada; however, the terrane's displacement history is only poorly constrained by sparse paleomagnetic studies. We studied the paleomagnetism of the Hound Island Volcanics in order to evaluate the location of the Alexander terrane in Late Triassic time. We collected 618 samples at 102 sites in and near the Keku Strait, Alaska, from the Late Triassic Hound Island Volcanics, the Permian Pybus Formation, and 23-Ma gabbroic intrusions. We found three components of magnetization in the Hound Island Volcanics. The high-temperature component (component A) resides in hematite and magnetite and was found only in highly oxidized lava flows in a geographically restricted area. We think it is primary, or acquired soon after eruption of the lavas, principally because the directions pass a fold test. The paleolatitude indicated by this component (19.2° ± 10.3°) is similar to those determined for various portions of Wrangellia, consistent with the geologic interpretation that the Alexander terrane was with the Wrangellia terrane in Late Triassic time. We found two overprint directions in the Hound Island Volcanics. Component B was acquired 23 m.y. ago due to intrusion of gabbroic dikes and sills. This interpretation is indicated by the similarity of upper-hemisphere directions in the Hound Island Volcanics to those in the gabbro. Component C, found in both the Hound Island Volcanics and the Permian Pybus Formation, is oriented northeast and down, fails a regional fold test, and was acquired after regional deformation around 90 to 100 Ma. This overprint direction yields a paleolatitude similar to, but slightly higher than, slightly older rocks from the Coast Plutonic Complex, suggesting that the Alexander terrane was displaced 17° in early Late Cretaceous time. The occurrence of these two separate overprinting events provides a satisfying explanation of the earlier puzzling results from the Hound Island Volcanics (Hillhouse and Grommé, 1980). Finally, great-circle analysis of the paleomagnetic data from the Pybus Formation suggests the Alexander terrane may have been in the northern hemisphere in Permian time.

Earth Observations taken by the Expedition 23 Crew

NASA Image and Video Library

2010-05-12

ISS023-E-041934 (12 May 2010) --- Southern Paramushir Island in the Kuril island chain in Russia is featured in this image photographed by an Expedition 23 crew member on the International Space Station. The Kuril island chain consists of a line of volcanoes, many of which have been historically active, that extends from the Kamchatka Peninsula to northern Japan. This line of island volcanoes is known to geologists as an island arc. Island arcs form along an active geologic boundary, typically marked by a deep undersea trench, between two tectonic plates with one being driven beneath the other (a process called subduction). Magma generated by this process feeds volcanoes ? and eventually, volcanic islands ? over the subduction boundary. Paramushir Island in the northern Kurils is an example of a large island built by several volcanoes over geologic time. This photograph shows the southern end of Paramushir Island after a snowfall. There are four major volcanic centers that form this part of the island. Fuss Peak (center left) is an isolated stratovolcano connected to the main island via an isthmus. The last recorded historical eruption of Fuss Peak was in 1854. The southern tip of the island is occupied by the Karpinsky Group of three volcanic centers. A minor eruption of ash following an earthquake occurred on this part of the island in 1952. The Lomonosov Group to the northeast (center) includes four cinder cones and a lava dome that produced several lava flows extending from the central ridge to the east, northeast, west, and southeast. There have been no recorded historical eruptions from the Lomonosov Group of volcanoes. The most recent volcanic activity (in 2008) occurred at the Chikurachki cone located along the northern coastline of the island at top center. The summit of this volcano (1816 meters above sea level) is the highest on Paramushir Island. Much of the Sea of Okhotsk visible in the image is covered with low clouds that typically form around the islands in the Kuril chain. The clouds are generated by moisture-laden air passing over the cool sea/ocean water and typically wrap around the volcanic islands.

Mantle heterogeneities beneath the Northeast Indian Ocean as sampled by intra-plate volcanism at Christmas Island

NASA Astrophysics Data System (ADS)

Taneja, Rajat; Rushmer, Tracy; Blichert-Toft, Janne; Turner, Simon; O'Neill, Craig

2016-10-01

The intra-plate region of the Northeast Indian Ocean, located between the Ninetyeast Ridge and the North West Shelf of Australia, contains numerous submerged seamounts and two sub-aerially exposed volcanic island groups. While the Cocos (Keeling) Archipelago is a coral atoll, Christmas Island is the only sub-aerially exposed volcanic island and contains Late Cretaceous, Eocene and Pliocene lavas. The lavas are predominantly basaltic in composition, except for one sampled flow that is trachytic. Although the evolution of the western margin of Australia, and the seismicity in the intra-plate region, has received considerable attention, the origin of the seamount province in the Northeast Indian Ocean is still a matter of debate. In order to constrain the origin of volcanism on Christmas Island and the associated Seamount Province we analysed 14 Christmas Island samples for major and trace element abundances and 12 of these for Nd, Hf and Pb isotope compositions. The trace element patterns of the lavas are similar to many ocean island basalts, while high 208Pb/204Pb and 207Pb/204Pb at a given 206Pb/204Pb suggest affiliation with the DUPAL anomaly. The reconstructed position of Christmas Island during the Eocene (44-37 Ma) places the island in close proximity to the (present-day) upper mantle low-seismic velocity anomalies. Moreover, an enriched mantle (EM-2) type component in addition to the DUPAL anomaly is observed in the Eocene volcanic phase. The younger Pliocene ( 4 Ma) sequences at Christmas Island are inferred to be the product of partial melting of existing material induced by lithospheric flexure.

U.S. Geological Survey (USGS) Western Region Kasatochi Volcano Coastal and Ocean Science

USGS Publications Warehouse

DeGange, Anthony

2010-01-01

Alaska is noteworthy as a region of frequent seismic and volcanic activity. The region contains 52 historically active volcanoes, 14 of which have had at least one major eruptive event since 1990. Despite the high frequency of volcanic activity in Alaska, comprehensive studies of how ecosystems respond to volcanic eruptions are non-existent. On August 7, 2008, Kasatochi Volcano, in the central Aleutian Islands, erupted catastrophically, covering the island with ash and hot pyroclastic flow material. Kasatochi Island was an annual monitoring site of the U.S. Fish and Wildlife Service, Alaska Maritime National Wildlife Refuge (AMNWR); therefore, features of the terrestrial and nearshore ecosystems of the island were well known. In 2009, the U.S. Geological Survey (USGS), AMNWR, and University of Alaska Fairbanks began long-term studies to better understand the effects of the eruption and the role of volcanism in structuring ecosystems in the Aleutian Islands, a volcano-dominated region with high natural resource values.

An interdisciplinary approach to volcanic risk reduction under conditions of uncertainty: a case study of Tristan da Cunha

NASA Astrophysics Data System (ADS)

Hicks, A.; Barclay, J.; Simmons, P.; Loughlin, S.

2013-12-01

This research project adopted an interdisciplinary approach to volcanic risk reduction on the remote volcanic island of Tristan da Cunha (South Atlantic). New data were produced that: (1) established no spatio-temporal pattern to recent volcanic activity; (2) quantified the high degree of scientific uncertainty around future eruptive scenarios; (3) analysed the physical vulnerability of the community as a consequence of their geographical isolation and exposure to volcanic hazards; (4) evaluated social and cultural influences on vulnerability and resilience. Despite their isolation and prolonged periods of hardship, islanders have demonstrated an ability to cope with and recover from adverse events. This resilience is likely a function of remoteness, strong kinship ties, bonding social capital, and persistence of shared values and principles established at community inception. While there is good knowledge of the styles of volcanic activity on Tristan, given the high degree of scientific uncertainty about the timing, size and location of future volcanism, a qualitative scenario planning approach was used as a vehicle to convey this information to the islanders. This deliberative, anticipatory method allowed on-island decision makers to take ownership of risk identification, management and capacity building within their community. This paper demonstrates the value of integrating social and physical sciences with development of effective, tailored communication strategies in volcanic risk reduction.

Spawning Behavior and Egg Development of Aplysia kurodai Inhabiting the Coastal Waters of Jeju Island, Korea

PubMed Central

Lee, Chi-Hoon; Kaang, Bong-Kiun; Lee, Young-Don

2014-01-01

This study was investigated spawning behavior, structure of egg masses and egg development in Aplysia kurodai inhabiting the coastal waters of Jeju Island, Korea. The mating and courtship behavior of A. kurodai occurred in the form of unilateral copulating with chain formation. In chain copulation, only the first animal acted as a female; the second and succeeding animals acted as males (sperm donors) to the animals in front and as females to the animals behind. The fertilized eggs were packaged in capsules that are embedded in jelly to form a cylindrical string called an egg masses. The number of capsule per cm of the egg masses was 55 to 60 capsules and each capsule within the egg masses held 15 to 25 eggs. After spawning, the egg masses were bright yellow or orange in color. This egg masses color not changed until embryos developed into trochophore stage. Thereafter, as embryo developed from trochophore stage to veliger stage the egg masses color became brownish. The fertilized eggs were spherical, with a diameter of approximately 80±1 μm at spawning. At 5 to 6 days after spawning, the embryo developed into trochophore stage and began to rotate within the egg capsule. In the trochophore stage, the precursor of the velum, called the prototroch or prevelum, developed. At 10 days after spawning, the prevelum is transformed into the velum, and the trochophore developed into veliger stage. Between 10 to 15 days after spawning, the veligers broke out of the egg capsule, and hatched as free-swimming larvae. PMID:25949168

Prodigious submarine landslides during the inception and early growth of volcanic islands.

PubMed

Hunt, James E; Jarvis, Ian

2017-12-12

Volcanic island inception applies large stresses as the ocean crust domes in response to magma ascension and is loaded by eruption of lavas. There is currently limited information on when volcanic islands are initiated on the seafloor, and no information regarding the seafloor instabilities island inception may cause. The deep sea Madeira Abyssal Plain contains a 43 million year history of turbidites among which many originate from mass movements in the Canary Islands. Here, we investigate the composition and timing of a distinctive group of turbidites that we suggest represent a new unique record of large-volume submarine landslides triggered during the inception, submarine shield growth, and final subaerial emergence of the Canary Islands. These slides are predominantly multi-stage and yet represent among the largest mass movements on the Earth's surface up to three or more-times larger than subaerial Canary Islands flank collapses. Thus whilst these deposits provide invaluable information on ocean island geodynamics they also represent a significant, and as yet unaccounted, marine geohazard.

Subsurface mapping of the Ross Island flexural basin, southwest Antarctica

NASA Astrophysics Data System (ADS)

Wenman, Christopher P.

Ross Island is a post-Miocene (< 4.6 Ma) volcanic island located in the Ross Sea region of southwest Antarctica. This region of Antarctica borders the western edge of the West Antarctic Rift System, along the Transantarctic Mountain front. Marine and over-ice multi-channel seismic reflection surveys and borehole studies targeting the Ross Sea region over the last 30+ years have been used in this study to develop a seismic stratigraphic model of the development and evolution of the Ross Island flexural basin. Four key stratigraphic horizons were identified and mapped to fully capture the basin-fill, as well as strata lying above and below the flexural basin. From oldest to youngest these horizons are named RIB-m, RIM-g, RIM-b and RIB-r. Time structure, isochron and isochore maps were created for the horizons and the stratigraphic intervals they bound. The seismic stratigraphic record shows the Ross Island flexural moat formation post-dates the main tectonic subsidence phase within the Victoria Land Basin. The maps presented here are the first to fully illustrate the evolution of the Ross Island flexural basin. The maps highlight depositional patterns of two distinct periods of flexural subsidence and basin-filling superimposed on the older N-S trending Victoria Land Basin depocenter. Two units of flexural basin fill, Unit FFI between horizons RIM-g and RIM-b (the oldest flexural basin fill), and Unit FFII between horizons RIM-b and RIB-r (the youngest flexural basin fill) are associated with the two periods of flexural subsidence. Flexural moat subsidence and subsequent filling occurred episodically during periods of active volcanism on the island. Unit FFI is estimated to range from ca. 4 to 2 Ma, corresponding with formation of the Mt. Bird volcanic edifice on Ross Island. Unit FFII ranges in age from ca. 2 to 1 Ma, and is related to Mt. Terror, Mt. Erebus, and Hut Point Peninsula volcanism. The isochore maps suggest the depocenter of the flexural basin during both time intervals was located north of the island, instead of directly beneath the Ross Island topographic load. Factors contributing to the northerly location of the depocenter include i) volcanic loading by McMurdo Volcanic Group subsea volcanic features north of the island, ii) partial compensation of the main Ross Island load by low-density, partially molten rock beneath the island, iii) extensional faulting within the Terror Rift, and iv) seaward-thickening shelf sediments transported from the Ross Ice Shelf. The seismic data show that the onset of filling of the flexural moat around Ross Island coincided with the end of ice grounding events in the area. We infer that this was caused by flexural subsidence of the seafloor to accommodate the Ross Island load.

Technical progress report of biological research on the Volcanic Island Surtsey and its environs for the period 1965--1978

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fridriksson, S.

Progress is reported on the following research projects: changes in shoreline and surface of the island due to volcanic activity; colonization of microorganisms, algae, lichens, and vascular plants; introduction of insects and other arthropods by wind, water, and man; transport of invertebrates to the island by flotsam of the sea; species and nesting habits of birds on the island; behavior of seals on beaches of the island; and future trends of Surtsey ecosystems. (HLW)

The emergence of volcanic oceanic islands on a slow-moving plate: The example of Madeira Island, NE Atlantic

NASA Astrophysics Data System (ADS)

Ramalho, Ricardo S.; Brum da Silveira, António; Fonseca, Paulo E.; Madeira, José; Cosca, Michael; Cachão, Mário; Fonseca, Maria M.; Prada, Susana N.

2015-02-01

The transition from seamount to oceanic island typically involves surtseyan volcanism. However, the geological record at many islands in the NE Atlantic—all located within the slow-moving Nubian plate—does not exhibit evidence for an emergent surtseyan phase but rather an erosive unconformity between the submarine basement and the overlying subaerial shield sequences. This suggests that the transition between seamount and island may frequently occur by a relative fall of sea level through uplift, eustatic changes, or a combination of both, and may not involve summit volcanism. In this study, we explore the consequences for island evolutionary models using Madeira Island (Portugal) as a case study. We have examined the geologic record at Madeira using a combination of detailed fieldwork, biostratigraphy, and 40Ar/39Ar geochronology in order to document the mode, timing, and duration of edifice emergence above sea level. Our study confirms that Madeira's subaerial shield volcano was built upon the eroded remains of an uplifted seamount, with shallow marine sediments found between the two eruptive sequences and presently located at 320-430 m above sea level. This study reveals that Madeira emerged around 7.0-5.6 Ma essentially through an uplift process and before volcanic activity resumed to form the subaerial shield volcano. Basal intrusions are a likely uplift mechanism, and their emplacement is possibly enhanced by the slow motion of the Nubian plate relative to the source of partial melting. Alternating uplift and subsidence episodes suggest that island edifice growth may be governed by competing dominantly volcanic and dominantly intrusive processes.

The emergence of volcanic oceanic islands on a slow-moving plate: The example of Madeira Island, NE Atlantic

USGS Publications Warehouse

Ramalho, Ricardo; da Silveira, António Brum; Fonseca, Paulo; Madeira, Jose; Cosca, Michael A.; Cachão, Mário; Fonseca, Maria M.; Prada, Susana

2015-01-01

The transition from seamount to oceanic island typically involves surtseyan volcanism. However, the geological record at many islands in the NE Atlantic—all located within the slow-moving Nubian plate—does not exhibit evidence for an emergent surtseyan phase but rather an erosive unconformity between the submarine basement and the overlying subaerial shield sequences. This suggests that the transition between seamount and island may frequently occur by a relative fall of sea level through uplift, eustatic changes, or a combination of both, and may not involve summit volcanism. In this study, we explore the consequences for island evolutionary models using Madeira Island (Portugal) as a case study. We have examined the geologic record at Madeira using a combination of detailed fieldwork, biostratigraphy, and 40Ar/39Ar geochronology in order to document the mode, timing, and duration of edifice emergence above sea level. Our study confirms that Madeira's subaerial shield volcano was built upon the eroded remains of an uplifted seamount, with shallow marine sediments found between the two eruptive sequences and presently located at 320–430 m above sea level. This study reveals that Madeira emerged around 7.0–5.6 Ma essentially through an uplift process and before volcanic activity resumed to form the subaerial shield volcano. Basal intrusions are a likely uplift mechanism, and their emplacement is possibly enhanced by the slow motion of the Nubian plate relative to the source of partial melting. Alternating uplift and subsidence episodes suggest that island edifice growth may be governed by competing dominantly volcanic and dominantly intrusive processes.

Muria Volcano, Island of Java, Indonesia

NASA Technical Reports Server (NTRS)

1991-01-01

This view of the north coast of central Java, Indonesia centers on the currently inactive Muria Volcano (6.5S, 111.0E). Muria is 5,330 ft. tall and lies just north of Java's main volcanic belt which runs east - west down the spine of the island attesting to the volcanic origin of the more than 1,500 Indonesian Islands.

Evolution of a volcanic island on the shoulder of an oceanic rift and geodynamic implications: S. Jorge Island on the Terceira Rift, Azores Triple Junction

NASA Astrophysics Data System (ADS)

Marques, F. O.; Hildenbrand, A.; Hübscher, C.

2018-07-01

The S. Jorge Island in the Azores lies on a peculiar setting, the southern shoulder of the Terceira Rift (TR), which raises a series of questions that we address in this study. We first established the main volcanic stratigraphy by recognizing, in the field, the main unconformities/discontinuities and their meaning (major erosion surfaces and faults), then we collected critical samples, and finally dated them by K/Ar to calibrate the stratigraphy and the age of inferred large-scale flank collapses. Based on field, geochronological and marine geophysical data: (1) we found much older rocks in S. Jorge than in previous studies (ca. 1.85 Ma), and established a new volcanic stratigraphy (from bottom to top): Old Volcanic Complex (ca. 1.9-1.2 Ma), cropping out in the eastern third of the island; Intermediate Volcanic Complex (ca. 0.8-0.2 Ma), cropping out in the western two thirds of the island and separated from the underlying complex by a major fault; Young Volcanic Complex (

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

NASA Astrophysics Data System (ADS)

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

2015-05-01

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

Earth Observations taken by the Expedition 17 Crew

NASA Image and Video Library

2008-06-24

ISS017-E-009777 (24 June 2008) --- Aeolian Islands, Italy are featured in this image photographed by an Expedition 17 crewmember on the International Space Station. The Aeolian Islands formed from a chain of volcanoes in the Tyrrhenian Sea to the north of the island of Sicily. The islands have been studied by geologists and vulcanologists since the 18th century, and were accorded UNESCO World Heritage Site status in 2000 in recognition of their continuing value to study of volcanic processes. Two types of volcanic eruption, Vulcanian and Strombolian, were defined based on study and observation of geologic processes on the islands of Vulcano and Stromboli (not shown). This detailed view features the island of Lipari and the northern portion of the island of Vulcano. Tan, speckled areas on both islands are urban areas and towns. Lipari is the largest of the Aeolian Islands, and is a popular tourist destination due to its rugged volcanic topography and beaches (several boat wakes are visible in the image around the islands). White pumice beaches and caves are located along the northern and northeastern coastlines of Lipari; black sand beaches derived from lava flows can also be found on the island. The most recent eruptive activity on Lipari took place between approximately 580-729. The island of Vulcano (right) is comprised of two calderas -- large craters formed when explosive eruptions empty a magma chamber, followed by collapse of the overlying material into the newly-formed void -- the Caldera della Fossa to the north and the Caldera del Piano to the south. The volcanic cone of La Fossa, located with the Caldera della Fossa, has been the site of much of the historical eruptive activity on the island. The last eruption on Vulcano Island took place during 1898-1900.

Youngest volcanism about 1 million years ago at Kahoolawe Island, Hawaii

USGS Publications Warehouse

Sano, H.; Sherrod, D.R.; Tagami, Takahiro

2006-01-01

Young volcanic deposits in Kahoolawe Island, cutting up through the caldera-filling lava, colluvium and talus in the west wall of Kanapou Bay, had long been stratigraphically considered the rejuvenated-stage products. New K-Ar ages, combined with magnetic polarity data, show that young volcanism was at about 0.98-1.04 Ma and indicate no substantial quiescence between the filling of the caldera and the young volcanism. This result, and the tholeiitic characteristics of the young deposits, suggest they are a component of late shield-stage volcanism. ?? 2005 Elsevier B.V. All rights reserved.

Long-term volcanic hazard assessment on El Hierro (Canary Islands)

NASA Astrophysics Data System (ADS)

Becerril, L.; Bartolini, S.; Sobradelo, R.; Martí, J.; Morales, J. M.; Galindo, I.

2014-07-01

Long-term hazard assessment, one of the bastions of risk-mitigation programs, is required for land-use planning and for developing emergency plans. To ensure quality and representative results, long-term volcanic hazard assessment requires several sequential steps to be completed, which include the compilation of geological and volcanological information, the characterisation of past eruptions, spatial and temporal probabilistic studies, and the simulation of different eruptive scenarios. Despite being a densely populated active volcanic region that receives millions of visitors per year, no systematic hazard assessment has ever been conducted on the Canary Islands. In this paper we focus our attention on El Hierro, the youngest of the Canary Islands and the most recently affected by an eruption. We analyse the past eruptive activity to determine the spatial and temporal probability, and likely style of a future eruption on the island, i.e. the where, when and how. By studying the past eruptive behaviour of the island and assuming that future eruptive patterns will be similar, we aim to identify the most likely volcanic scenarios and corresponding hazards, which include lava flows, pyroclastic fallout and pyroclastic density currents (PDCs). Finally, we estimate their probability of occurrence. The end result, through the combination of the most probable scenarios (lava flows, pyroclastic density currents and ashfall), is the first qualitative integrated volcanic hazard map of the island.

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

USGS Publications Warehouse

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

2008-01-01

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

Hydrogeological Report, Lajes Field, Azores, Portugal

DTIC Science & Technology

2005-02-01

fractured volcanic rocks and has groundwater levels near sea level. 2. Numerous discontinuous perched aquifers that occur in areas where precipitation...insular region that includes also the archipelagos of Madeira, Selvagens, Canary, and Cape Verde Islands. Terceira Island is built by tree volcanic ...area are predominantly typical Andosols. These volcanic soils are characterized by a high permeability up to 70 percent in some cases (Faria, 1974

What, When, Where, and Why of Secondary Hawaiian Hotspot Volcanism

NASA Astrophysics Data System (ADS)

Garcia, M. O.; Ito, G.; Applegate, B.; Weis, D.; Swinnard, L.; Flinders, A.; Hanano, D.; Nobre-Silva, I.; Bianco, T.; Naumann, T.; Geist, D.; Blay, C.; Sciaroni, L.; Maerschalk, C.; Harpp, K.; Christensen, B.

2007-12-01

Secondary hotspot volcanism occurs on most oceanic island groups (Hawaii, Canary, Society) but its origins remain enigmatic. A 28-day marine expedition used multibeam bathymetry and acoustic imagery to map the extent of submarine volcanic fields around the northern Hawaiian Islands (Kauai, Niihau and Kaula), and the JASON2 ROV to sample many volcanoes to characterize the petrology, geochemistry (major and trace elements, and isotopes) and ages of the lavas from these volcanoes. Our integrated geological, geochemical and geophysical study attempts to examine the what (compositions and source), where (distribution and volumes), when (ages), and why (mechanisms) of secondary volcanism on and around the northern Hawaiian Islands. A first-order objective was to establish how the submarine volcanism relates in space, time, volume, and composition to the nearby shield volcanoes and their associated onshore secondary volcanism. Our surveying and sampling revealed major fields of submarine volcanoes extending from the shallow slopes of these islands to more than 100 km offshore. These discoveries dramatically expand the volumetric importance, distribution and geodynamic framework for Hawaiian secondary volcanism. New maps and rock petrology on the samples collected will be used to evaluate currently proposed mechanisms for secondary volcanism and to consider new models such as small-scale mantle convection driven by thermal and melt-induced buoyancy to produce the huge volume of newly discovered lava. Our results seem to indicate substantial revisions are needed to our current perceptions of hotspot dynamics for Hawaii and possibly elsewhere.

Novel alpha-glucosidase inhibitors, CKD-711 and CKD-711a produced by Streptomyces sp. CK-4416. I. Taxonomy, fermentation and isolation.

PubMed

Kim, Jong-Gwan; Chang, Hung-Bae; Kwon, Young-In; Moon, Seung-Kee; Chun, Hyoung-Sik; Ahn, Soon Kil; Hong, Chung Il

2002-05-01

New alpha-glucosidase inhibitors, CKD-711 and CKD-711a were produced from the fermentation broth of Streptomyces sp. CK-4416 which was isolated from a forest soil of Jeju Island, South Korea. CKD-711 and CKD-711a were purified by Dowex 50W-2X and Sephadex G-10 column chromatography. In in vitro studies, CKD-711 showed a potent inhibitory activity against a-glucosidase from mammalian, but less inhibition against a-amylase from microorganism and mammalian. CKD-711a showed a lower inhibitory activity than CKD-711.

Seafloor morphology and coral habitat variability in a volcanic environment: Kaloko-Honokohau National Park, Hawaii, USA

USGS Publications Warehouse

Gibbs, Ann E.; Cochran, Susan A.

2011-01-01

Kaloko–Honokohau National Historical Park (KAHO) is one of three National Park lands along the leeward, west, or Kona, coast of the island of Hawaii, USA. The park includes 596 acres (2.4 km2) of submerged lands and marine resources within its official boundaries. The offshore region of KAHO, part of the insular shelf of the island of Hawaii, comprises a volcanic embayment that extends nearly 3.5 km alongshore and varies in width between 120 and 875 m from the shoreline to the 40 m isobath, the limit of the high-resolution bathymetry. Multiple Holocene volcanic flows coalesce within Kaloko-Honokohau National Historical Park (KAHO) on the island of Hawaii to create a complex offshore morphology. The volcanic-dominated morphology includes flat to gently sloping volcanic benches, boulder fields, cliffs and ledges, pinnacles, ridges, arches, and steep shelf escarpments. Each of these environments provide distinct habitat zones for coral species, ranging from isolated heads of Porites lobata and Pocillopora meandrina to dense thickets of Porites compressa. In contrast to coral habitat elsewhere in the Hawaiian Islands, where coral typically populates relict carbonate platforms, coral cover in KAHO is typically only a thin veneer of live coral and rubble on exposed volcanic pavement. In only a few locations does coral or accreted carbonate reef obscure the underlying volcanic surface.

Exploring Volcanism with Digital Technology in Undergraduate Education

NASA Astrophysics Data System (ADS)

McCoy, F. W.; Parisky, A.

2016-12-01

Volcanism as one of the most dynamic geological processes on this planet is also one of the most dramatic for attracting students to the earth sciences. At the University of Hawaii (UH) volcanism is used to attract students into the geosciences, coupled with its significant association to Hawaiian culture and contemporary issues such as those associated with related hazards - example: during the past century five towns were buried by lava flows on the Big Island, another recently threatened with destruction. To bring this dynamism into undergraduate education, UH focuses on field trips and courses to all islands; at Windward Community College (WCC/UH) a focus is provided through a series of field courses (1 credit) to all islands, especially the Big Island. Critical to the WCC effort are computer-generated animations and descriptions of volcanological processes for illustrating concepts undergraduate students find difficult: tumescence as an indicator of an eruption, fractional crystallization, collapse of volcanic edifices, explosive eruptions, weathering processes, hazards and mitigation, all embedded in the evolutionary story of mid-ocean volcanic islands such as those in Hawaii. Field courses require intense field labs, which are significantly assisted by digital platforms that include computer-generated illustrations, descriptions, animations, and more. The consequence for developing geoscientists has been outstanding.

Quantitative volcanic susceptibility analysis of Lanzarote and Chinijo Islands based on kernel density estimation via a linear diffusion process

PubMed Central

Galindo, I.; Romero, M. C.; Sánchez, N.; Morales, J. M.

2016-01-01

Risk management stakeholders in high-populated volcanic islands should be provided with the latest high-quality volcanic information. We present here the first volcanic susceptibility map of Lanzarote and Chinijo Islands and their submarine flanks based on updated chronostratigraphical and volcano structural data, as well as on the geomorphological analysis of the bathymetric data of the submarine flanks. The role of the structural elements in the volcanic susceptibility analysis has been reviewed: vents have been considered since they indicate where previous eruptions took place; eruptive fissures provide information about the stress field as they are the superficial expression of the dyke conduit; eroded dykes have been discarded since they are single non-feeder dykes intruded in deep parts of Miocene-Pliocene volcanic edifices; main faults have been taken into account only in those cases where they could modified the superficial movement of magma. The application of kernel density estimation via a linear diffusion process for the volcanic susceptibility assessment has been applied successfully to Lanzarote and could be applied to other fissure volcanic fields worldwide since the results provide information about the probable area where an eruption could take place but also about the main direction of the probable volcanic fissures. PMID:27265878

Quantitative volcanic susceptibility analysis of Lanzarote and Chinijo Islands based on kernel density estimation via a linear diffusion process.

PubMed

Galindo, I; Romero, M C; Sánchez, N; Morales, J M

2016-06-06

Risk management stakeholders in high-populated volcanic islands should be provided with the latest high-quality volcanic information. We present here the first volcanic susceptibility map of Lanzarote and Chinijo Islands and their submarine flanks based on updated chronostratigraphical and volcano structural data, as well as on the geomorphological analysis of the bathymetric data of the submarine flanks. The role of the structural elements in the volcanic susceptibility analysis has been reviewed: vents have been considered since they indicate where previous eruptions took place; eruptive fissures provide information about the stress field as they are the superficial expression of the dyke conduit; eroded dykes have been discarded since they are single non-feeder dykes intruded in deep parts of Miocene-Pliocene volcanic edifices; main faults have been taken into account only in those cases where they could modified the superficial movement of magma. The application of kernel density estimation via a linear diffusion process for the volcanic susceptibility assessment has been applied successfully to Lanzarote and could be applied to other fissure volcanic fields worldwide since the results provide information about the probable area where an eruption could take place but also about the main direction of the probable volcanic fissures.

Quantitative volcanic susceptibility analysis of Lanzarote and Chinijo Islands based on kernel density estimation via a linear diffusion process

NASA Astrophysics Data System (ADS)

Galindo, I.; Romero, M. C.; Sánchez, N.; Morales, J. M.

2016-06-01

Risk management stakeholders in high-populated volcanic islands should be provided with the latest high-quality volcanic information. We present here the first volcanic susceptibility map of Lanzarote and Chinijo Islands and their submarine flanks based on updated chronostratigraphical and volcano structural data, as well as on the geomorphological analysis of the bathymetric data of the submarine flanks. The role of the structural elements in the volcanic susceptibility analysis has been reviewed: vents have been considered since they indicate where previous eruptions took place; eruptive fissures provide information about the stress field as they are the superficial expression of the dyke conduit; eroded dykes have been discarded since they are single non-feeder dykes intruded in deep parts of Miocene-Pliocene volcanic edifices; main faults have been taken into account only in those cases where they could modified the superficial movement of magma. The application of kernel density estimation via a linear diffusion process for the volcanic susceptibility assessment has been applied successfully to Lanzarote and could be applied to other fissure volcanic fields worldwide since the results provide information about the probable area where an eruption could take place but also about the main direction of the probable volcanic fissures.

Morpho-structural evolution of a volcanic island developed inside an active oceanic rift: S. Miguel Island (Terceira Rift, Azores)

NASA Astrophysics Data System (ADS)

Sibrant, A. L. R.; Hildenbrand, A.; Marques, F. O.; Weiss, B.; Boulesteix, T.; Hübscher, C.; Lüdmann, T.; Costa, A. C. G.; Catalão, J. C.

2015-08-01

The evolution of volcanic islands is generally marked by fast construction phases alternating with destruction by a variety of mass-wasting processes. More specifically, volcanic islands located in areas of intense regional deformation can be particularly prone to gravitational destabilisation. The island of S. Miguel (Azores) has developed during the last 1 Myr inside the active Terceira Rift, a major tectonic structure materializing the present boundary between the Eurasian and Nubian lithospheric plates. In this work, we depict the evolution of the island, based on high-resolution DEM data, stratigraphic and structural analyses, high-precision K-Ar dating on separated mineral phases, and offshore data (bathymetry and seismic profiles). The new results indicate that: (1) the oldest volcanic complex (Nordeste), composing the easternmost part of the island, was dominantly active between ca. 850 and 750 ka, and was subsequently affected by a major south-directed flank collapse. (2) Between at least 500 ka and 250 ka, the landslide depression was massively filled by a thick lava succession erupted from volcanic cones and domes distributed along the main E-W collapse scar. (3) Since 250 kyr, the western part of this succession (Furnas area) was affected by multiple vertical collapses; associated plinian eruptions produced large pyroclastic deposits, here dated at ca. 60 ka and less than 25 ka. (4) During the same period, the eastern part of the landslide scar was enlarged by retrogressive erosion, producing the large Povoação valley, which was gradually filled by sediments and young volcanic products. (5) The Fogo volcano, in the middle of S. Miguel, is here dated between ca. 270 and 17 ka, and was affected by, at least, one southwards flank collapse. (6) The Sete Cidades volcano, in the western end of the island, is here dated between ca. 91 and 13 ka, and experienced mutliple caldera collapses; a landslide to the North is also suspected from the presence of a subtle morphologic scar covered by recent lava flows erupted from alignments of basaltic strombolian cones. The predominance of the N150° and N75° trends in the island suggest that the tectonics of the Terceira Rift controlled the location and the distribution of the volcanism, and to some extent the various destruction events.

Geodetic Volcano Monitoring Research in Canary Islands: Recent Results

NASA Astrophysics Data System (ADS)

Fernandez, J.; Gonzalez, P. J.; Arjona, A.; Camacho, A. G.; Prieto, J. F.; Seco, A.; Tizzani, P.; Manzo, M. R.; Lanari, R.; Blanco, P.; Mallorqui, J. J.

2009-05-01

The Canarian Archipelago is an oceanic island volcanic chain with a long-standing history of volcanic activity (> 40 Ma). It is located off the NW coast of the African continent, lying over a transitional crust of the Atlantic African passive margin. At least 12 eruptions have been occurred on the islands of Lanzarote, Tenerife and La Palma in the last 500 years. Volcanism manifest predominantly as basaltic strombolian monogenetic activity (whole archipelago) and central felsic volcanism (active only in Tenerife Island). We concentrate our studies in the two most active islands, Tenerife and La Palma. In these islands, we tested different methodologies of geodetic monitoring systems. We use a combination of ground- and space-based techniques. At Tenerife Island, a differential interferometric study was performed to detect areas of deformation. DInSAR detected two clear areas of deformation, using this results a survey-based GPS network was designed and optimized to control those deformations and the rest of the island. Finally, using SBAS DInSAR results weak spatial long- wavelength subsidence signals has been detected. At La Palma, the first DInSAR analysis have not shown any clear deformation, so a first time series analysis was performed detecting a clear subsidence signal at Teneguia volcano, as for Tenerife a GPS network was designed and optimized taking into account stable and deforming areas. After several years of activities, geodetic results served to study ground deformations caused by a wide variety of sources, such as changes in groundwater levels, volcanic activity, volcano-tectonics, gravitational loading, etc. These results proof that a combination of ground-based and space-based techniques is suitable tool for geodetic volcano monitoring in Canary Islands. Finally, we would like to strength that those results could have serious implications on the continuous geodetic monitoring system design and implementation for the Canary Islands which is under development nowadays.

Sea floor morphology of the Ebro Shelf in the region of the Columbretes Islands, Western Mediterranean

NASA Astrophysics Data System (ADS)

Muñoz, A.; Lastras, G.; Ballesteros, M.; Canals, M.; Acosta, J.; Uchupi, E.

2005-12-01

Widespread volcanism off eastern Spain in the western Mediterranean is associated with Cenozoic crustal attenuation and sinistral motion along the Trans-Moroccan-Western Mediterranean-European mega shear, extending from northern Morocco to the North Sea via the Alboran Basin, eastern Iberia, the Valencian and Lyons basins, France and Germany. The Quaternary Columbretes Islands volcanic field is the most prominent example of this volcanism associated with this mega shear. The islands are located in the Ebro continental shelf on top of a structural horst probably made of Paleozoic metamorphic rocks. Surrounding the emerged islands are volcanic structures and associated flows partially mantled by a sediment drift whose morphology is controlled by the southwestward flowing Catalan Current. This association is rather unique and appears to have never been described from a continental shelf in the Mediterranean Sea or outside the sea. The morphology of both kinds of structures, obtained by means of swath bathymetry data and very-high resolution seismic profiles, is presented in this study. They provide striking images of this previously unstudied part of the western Mediterranean seafloor. These images suggest that the volcanic structures are intruded into the surficial Holocene sediments indicating that volcanism in the Columbretes has extended into Holocene.

Population demographic history of a temperate shrub, Rhododendron weyrichii (Ericaceae), on continental islands of Japan and South Korea.

PubMed

Yoichi, Watanabe; Tamaki, Ichiro; Sakaguchi, Shota; Song, Jong-Suk; Yamamoto, Shin-Ichi; Tomaru, Nobuhiro

2016-12-01

Continental islands provide opportunities for testing the effects of isolation and migration on genetic variation in plant populations. In characteristic of continental islands is that the geographic connections between these islands, which are currently distinguished by seaways, have experienced fluctuations caused by sea-level changes due to climate oscillations during the Quaternary. Plant populations on the islands have migrated between these islands via the exposed seafloors or been isolated. Here, we examined the demographic history of a temperate shrub, Rhododendron weyrichii , which is distributed in the southwestern parts of the Japanese archipelago and on an island of South Korea, using statistical phylogeographic approaches based on the DNA sequences of two chloroplast and eight nuclear loci in samples analyzed from 18 populations on eight continental islands, and palaeodistribution modeling. Time estimates for four island populations indicate that the durations of vicariance history are different between these populations, and these events have continued since the last glacial or may have predated the last glacial. The constancy or expansion of population sizes on the Japanese islands, and in contrast a bottleneck in population size on the Korean island Jeju, suggests that these islands may have provided different conditions for sustaining populations. The result of palaeodistribution modeling indicates that the longitudinal range of the species as a whole has not changed greatly since the last glacial maximum. These results indicate that exposed seafloors during the glacial period formed both effective and ineffective migration corridors. These findings may shed light on the effects of seafloor exposure on the migration of plants distributed across continental islands.

Forecasting the 2011 El Hierro submarine eruption (Canary Islands) on the basis of soil He degassing surveys

NASA Astrophysics Data System (ADS)

Padrón, E.; Pérez, N. M.; Hernández, P. A.; Melián, G. V.; Padilla, G. D.; Barrancos, J.; Dionis, S.; Rodríguez, F.; Nolasco, D.; Calvo, D.; Hernández, I.; Peraza, M. D.

2012-04-01

El Hierro Island is the southwesternmost and the youngest island of the Canary archipelago. Since 16 July, an anomalous seismicity at El Hierro island was recorded by IGN seismic network. After the occurrence of more than 10,000 seismic events, volcanic tremor was recorded since 05:15 of the October 10, by all of the seismic stations on the island, with highest amplitudes recorded in the southernmost station. During the afternoon of 12 October a large light-green coloured area was observed in the sea to the souht of La Restinga village (at the southernmost part of El Hierro island), suggesting the existence of a submarine eruption. Since October 12, frequent episodes of, turbulent gas emission and foaming, and the appearance of steamy lava fragments has been observed on the sea surface. As part of the volcanic surveillance of the island, the Instituto Volcanologico de Canarias (INVOLCAN) geochemical monitoring program is carrying out diffuse helium surveys on the surface environment of El Hierro (soil atmosphere). This nobel gas has been investigated because it has been considered an almost ideal geochemical indicator because it is chemically inert, physically stable, nonbiogenic, sparingly soluble in water under ambient conditions and almost non-adsorbable. At each survey, 600 sampling sites covering the whole island and following an homogeneous distribution are selected for helium measurements in the soil gases, The helium concentration gradients with respect to its value on air (5.24 ppm) allow us to estimate a pure diffusive emission rate of helium throughout the island. The first survey was carried out on the summer of 2003, when the island was on a quiescence period. At this survey, the amount of helium released by the volcanic system of El Hierro was estimated in 6 kg/d. Since the beginning of the seismic unrest, 13 helium emission surveys have been carried out. The helium emission rate has shown an excellent agreement with the evolution of the volcanic crisis of the island, reaching 30 kg/d on November 6, several days before the occurrence of the submarine eruption. A significant decrease to 13 kg/d was estimated almost 10 days after the beginning of the eruption, followed by a sudden increase to 38 kg/d several days before the largest seismic event of the volcanic crisis (M = 4.6) occurred on November 11. The results of the soil helium surveys performed at El Hierro Island prior and during a volcanic unrest period suggest that the emission of this noble gas is strongly controlled by the volcanic activity and its presence on the surface environment responds to the changes on the gas pressure at depth produced by the ascent of magma bodies.

Volcanic complexes in the eastern ridge of the Canary Islands: the Miocene activity of the island of Fuerteventura

NASA Astrophysics Data System (ADS)

Ancochea, E.; Brändle, J. L.; Cubas, C. R.; Hernán, F.; Huertas, M. J.

1996-03-01

Fuerteventura has been since early stages of its growth the result of three different adjacent large volcanic complexes: Southern, Central and Northern. The definition of these volcanic complexes and their respective growing episodes is based on volcano-stratigraphic, morphological and structural criteria, particularly radial dyke swarms. Each complex has its own prolonged history that might be longer than 10 m.y. During that time, several periods of activity alternating with gaps accompanied by important erosion took place. The evolution of each volcanic complex has been partially independent but all the three are affected by at least three Miocene tectonic phases that controlled considerably their activity. The volcanic complexes are deeply eroded and partially submerged. In the core of the Northern and the Central volcanic complexes there is a set of submarine and plutonic rocks intensely traversed by a dyke swarm, known as the Basal Complex. The Basal Complex has been interpreted in different ways but all previous authors have considered it to be prior to the subaerial shield stage of the island. Here we advance the idea that the Basal Complex represent the submarine growing stage of the volcanic complexes and the hypabyssal roots (plutons and dykes) of their successive subaerial growing episodes. Two seamounts situated nearby, southwest of the island, might be interpreted as remains of two other major volcanoes. These two volcanoes, together with those forming the present emerged island of Fuerteventura, and finally those of Famara and Los Ajaches situated further north on Lanzarote constitute a chain of volcanoes located along a lineation which is subparallel to the northwestern African coastline and which may relate to early Atlantic spreading trends in the area.

Copious, Long-lived Rejuvenated Volcanism in the Northern Hawaiian Islands

NASA Astrophysics Data System (ADS)

Garcia, M. O.; Weis, D.; Hanano, D. W.; Jicha, B. R.; Ito, G.

2015-12-01

New marine surveying and submersible sampling of Kaul'a Volcano, located 100 km off the axis of the Hawaiian Chain, have revealed widespread areas of young volcanism. New 40Ar/39Ar and geochemical analyses of the olivine-phyric submarine and subaerial volcanic rocks show that Kaul'a is shrouded with young alkalic basalts (1.9 to 0.5 Ma). The ages and chemistry of these rocks overlap with rejuvenated lavas from nearby shields Ni'ihau, Kaua'i and South Kaua'i Swell. Collectively, rejuvenated lavas cover a vast area (~7000 km2) in the northern Hawaiian Islands. Kaul'a rejuvenated lavas show a much larger (5x) variation of incompatible elements than those from adjacent Ni'ihau but comparable to Honolulu rejuvenated lavas. Unlike both suites, heavy REE elements in Kaul'a lavas are pinned at Ybn 10, indicating a strong garnet signature in the source. Rejuvenated lavas from the Kaua'i Ridge have slightly higher radiogenic Pb isotope ratios than those from the southern Hawaiian Islands (Maui to O'ahu) and partly straddle the LOA-KEA boundary. Rejuvenated volcanism was nearly coeval occurrence from ~0.3 to 0.6 Ma along a 450 km segment of the Hawaiian Islands (West Maui to north of Ni'ihau), which is inconsistent with most models for rejuvenated volcanism except the Ballmer et al.2 dynamic melting model. This model invokes increasing pyroxenite contributions and the interaction with scale-scale convection rolls in the lithosphere to enhance the volume and duration of rejuvenation volcanism. Thus, a pyroxenite-bearing, mixed Kea-Loa source component may have contributed to the prolonged and extensive rejuvenated volcanism in the northern Hawaiian Islands. 1Robinson & Eakins 2006, J. Vol. Geotherm. Res., 151, 309-317; 2Ballmer et al. 2011, Nat. Geosc. 4, 457-460.

Erosion of volcanic ocean islands: insights from modeling, topographic analyses, and cosmogenic exposure dating

NASA Astrophysics Data System (ADS)

Huppert, K.; Perron, J. T.; Ferrier, K.; Mukhopadhyay, S.; Rosener, M.; Douglas, M.

2016-12-01

With homogeneous bedrock, dramatic rainfall gradients, paleoshorelines, and datable remnant topography, volcanic ocean islands provide an exceptional natural experiment in landscape evolution. Analyses traversing gradients in island climate and bedrock age have the potential to advance our understanding of landscape evolution in a diverse range of continental settings. However, as small, conical, dominantly subsiding, and initially highly permeable landmasses, islands are unique, and it remains unclear how these properties influence their erosional history. We use a landscape evolution model and observations from the Hawaiian island of Kaua'i and other islands to characterize the topographic evolution of volcanic ocean islands. We present new measurements of helium-3 concentrations in detrital olivine from 20 rivers on Kaua'i. These measurements indicate that minimum erosion rates over the past 3 to 48 kyr are on average 2.6 times faster than erosion rates averaged over the past 3.9 to 4.4 Myr estimated from the volume of river canyons. This apparent acceleration of erosion rates on Kaua'i is consistent with observations on other islands; erosion rates estimated from the volume of river canyons on 31 islands worldwide, combined with observations of minimal incision on young island volcanoes, suggest a progressive increase in erosion rates over the first few million years of island landscape development. Using a landscape evolution model, we perform a set of experiments to quantify the contribution of subsidence, climate change, and initial geometry to changes in island erosion rates through time. We base these experiments on the evolution of Kaua'i, and we use measured erosion rates and the observed topography to calibrate the model. We find that progressive steepening of island topography by canyon incision drives an acceleration of erosion rates over time. Increases in mean channel and hillslope gradient with island age in the global compilation suggest this may be a general trend in the topographic evolution of volcanic ocean islands.

The nearshore benthic community of Kasatochi Island, one year after the 2008 volcanic eruption

USGS Publications Warehouse

Jewett, S.C.; Bodkin, James L.; Chenelot, H.; Esslinger, George G.; Hoberg, M.K.

2010-01-01

A description is presented of the nearshore benthic community of Kasatochi Island 10–12 months after a catastrophic volcanic eruption in 2008. The eruption extended the coastline of the island approximately 400 m offshore, mainly along the south, southeast, and southwest shores, to roughly the 20 m isobath. Existing canopy kelp of Eualaria (Alaria) fistulosa, as well as limited understory algal species and associated fauna (e.g., urchin barrens) on the hard substratum were apparently buried following the eruption. Samples and observations revealed the substrate around the island in 2009 was comprised almost entirely of medium and coarse sands with a depauperate benthic community, dominated by opportunistic pontogeneiid amphipods. Comparisons of habitat and biological communities with other nearby Aleutian Islands, as well as with the Icelandic volcanic island of Surtsey, confirm dramatic reductions in flora and fauna consistent with an early stage of recovery from a large-scale disturbance event.

Enhancement of orographic precipitation in Jeju Island during the passage of Typhoon Khanun (2012)

NASA Astrophysics Data System (ADS)

Lee, Jung-Tae; Ko, Kyeong-Yeon; Lee, Dong-In; You, Cheol-Hwan; Liou, Yu-Chieng

2018-03-01

Typhoon Khanun caused over 226 mm of accumulated rainfall for 6 h (0700 to 1300 UTC), localized around the summit of Mt. Halla (height 1950 m), with a slanted rainfall pattern to the northeast. In this study, we investigated the enhancement mechanism for precipitation near the mountains as the typhoon passed over Jeju Island via dual-Doppler radar analysis and simple trajectory of passive tracers using a retrieved wind field. The analysis of vertical profiles of the mountain region show marked features matching the geophysical conditions. In the central mountain region, a strong wind (≥ 7 m s- 1) helps to lift low-level air up the mountain. The time taken for lifting is longer than the theoretical time required for raindrop growth via condensation. The falling particles (seeder) from the upper cloud were also one of the reasons for an increase in rainfall via the accretion process from uplifted cloud water (feeder). The lifted air and falling particles both contributed to the heavy rainfall in the central region. In contrast, on the leeward side, the seeder-feeder mechanism was important in the formation of strong radar reflectivity. The snow particles (above 5 km) were accelerated by strong downward winds (≤-6 m s- 1). Meanwhile, the nonlinear jumping flow (hydraulic jump) raised feeders (shifted from the windward side) to the upper level where particles fall. To support these development processes, a numerical simulation using cloud-resolving model theoretically carried out. The accreting of hydrometeors may be one of the key reasons why the lee side has strong radar reflectivity, and a lee side weighted rainfall pattern even though lee side includes no strong upward air motion.

Age-Related Incidence of Cervical Spondylosis in Residents of Jeju Island

PubMed Central

Yoon, Min-Geun; Park, Bong-Keun; Park, Min-Suk

2016-01-01

Study Design Cervical spine radiograms of 460 Jeju islanders. Purpose To investigate the age-matched incidences and severity of the cervical disc degeneration and associated pathologic findings. Overview of Literature Several related studies on the incidences of disc and Luschka's and facet joint degeneration have provided some basic data for clinicians. Methods Cervical radiographs of 460 (220 males and 240 females) patients in their fourth to ninth decade were analyzed. Ninety patients in their third decade were excluded because of absence of spondylotic findings. Results Overall incidence of cervical spondylosis was 47.8% (220 of 460 patients). The percentile incidences of spondylosis in the fourth, fifth, sixth, seventh, eighth and ninth decade was 13.2% (10 of 76 patients), 34.6% (37 of 107 patients), 58.9% (66 of 112 patients), 58.8% (50 of 85 patients), 70.3% (45 of 64 patients) and 75.0% (12 of 16 patients), respectively. The percentile incidences of one, two, three, four and five level spondylosis among 220 spondylosis patients was 45.5% (n=100), 34.1% (n=75), 15.0% (n=33), 4.5% (n=10), and 0.9% (n=2). Severity of disc degeneration ranged from ± to ++++, and was ± in 6.0% (24 segments), + in 49.6% (198 segments), ++ in 35.3% (141 segments), +++ in 9.0% (36 segments) and ++++ in 0.25% (one segment). Spurs and anterior ligament ossicle formed at the spondylotic segments, mostly at C4~6. The rate of posterior corporal spurs formation was very low. Olisthesis and ossification of the posterior longitudinal ligament were rarely combined with spondylosis. Cervical lordotic curve decreased gradually according to the progress of severity of spondylosis. Conclusions The incidence of cervical spondylosis and number of spondylotic segments increase, and degeneration gradually becomes more severe with age. PMID:27790313

First report of the epiphytic dinoflagellate Gambierdiscus caribaeus in the temperate waters off Jeju Island, Korea: morphology and molecular characterization.

PubMed

Jeong, Hae Jin; Lim, An Suk; Jang, Se Hyeon; Yih, Won Ho; Kang, Nam Seon; Lee, Sung Yeon; Yoo, Yeong Du; Kim, Hyung Seop

2012-01-01

Gambierdiscus spp. are epiphytic, benthic dinoflagellates. Some species have been shown to be toxic and cause ciguatera fish poisoning. We report, for the first time, the occurrence of Gambierdiscus caribaeus isolated from the waters off Jeju Island in Korea. Its morphology was similar to that of the original Belize strains of G. caribaeus. Gambierdiscus caribaeus has been reported in the tropical and subtropical waters of the Pacific, Gulf of Mexico, Caribbean Sea, and Floridian coast. Our report extends its range to the North Pacific Ocean. The plates of the Korean strain were arranged in a Kofoidian series of Po, 3', 7'', 6c, 6s, 5''', 1p, and 2'''', morphologically closer to other strains of G. caribaeus than to G. carpenteri. When properly aligned, its small subunit (SSU) rDNA was 0.5% different from those of Gambierdiscus sp. C-1, a strain that was isolated from the waters off eastern Japan, but was 2.4-4.0% different from those of the NOAA strains of G. caribaeus and 3.1-3.4% different from those of the NOAA strains of G. carpenteri. Additionally, the D1-D3 large subunit (LSU) rDNA sequence of the Korean strain of G. caribaeus was 4.7-5.3% different from those of the NOAA strains of G. caribaeus and 7.1-7.5% different from those of all reported G. carpenteri strains, including the NOAA strains. In phylogenetic trees based on SSU and LSU rDNA sequences, our Korean strain was basal to the clade consisting of the NOAA strains of G. caribaeus, which in turn was sister clade to all reported G. carpenteri strains. © 2012 The Author(s) Journal of Eukaryotic Microbiology © 2012 International Society of Protistologists.

Temporal and spatial variability of groundwater recharge on Jeju Island, Korea

USGS Publications Warehouse

Mair, Alan; Hagedorn, Benjamin; Tillery, Suzanne; El-Kadi, Aly I.; Westenbroek, Stephen M.; Ha, Kyoochul; Koh, Gi-Won

2013-01-01

Estimates of groundwater recharge spatial and temporal variability are essential inputs to groundwater flow models that are used to test groundwater availability under different management and climate conditions. In this study, a soil water balance analysis was conducted to estimate groundwater recharge on the island of Jeju, Korea, for baseline, drought, and climate-land use change scenarios. The Soil Water Balance (SWB) computer code was used to compute groundwater recharge and other water balance components at a daily time step using a 100 m grid cell size for an 18-year baseline scenario (1992–2009). A 10-year drought scenario was selected from historical precipitation trends (1961–2009), while the climate-land use change scenario was developed using late 21st century climate projections and a change in urban land use. Mean annual recharge under the baseline, drought, and climate-land use scenarios was estimated at 884, 591, and 788 mm, respectively. Under the baseline scenario, mean annual recharge was within the range of previous estimates (825–959 mm) and only slightly lower than the mean of 902 mm. As a fraction of mean annual rainfall, mean annual recharge was computed as only 42% and less than previous estimates of 44–48%. The maximum historical reported annual pumping rate of 241 × 106 m3 equates to 15% of baseline recharge, which is within the range of 14–16% computed from earlier studies. The model does not include a mechanism to account for additional sources of groundwater recharge, such as fog drip, irrigation, and artificial recharge, and may also overestimate evapotranspiration losses. Consequently, the results presented in this study represent a conservative estimate of total recharge.

Volcano-tectonic evolution of a linear volcanic ridge (Pico-Faial Ridge, Azores Triple Junction) assessed by paleomagnetic studies

NASA Astrophysics Data System (ADS)

Silva, Pedro F.; Henry, Bernard; Marques, Fernando O.; Hildenbrand, Anthony; Lopes, Ana; Madureira, Pedro; Madeira, José; Nunes, João C.; Roxerová, Zuzana

2018-02-01

The morphology of volcanic oceanic islands results from the interplay between constructive and destructive processes, and tectonics. In this study, the analysis of the paleomagnetic directions obtained on well-dated volcanic rocks is used as a tool to assess tilting related to tectonics and large-scale volcano instability along the Pico-Faial linear volcanic ridge (Azores Triple Junction, Central-North Atlantic). For this purpose, 530 specimens from 46 lava flows and one dyke from Pico and Faial islands were submitted to thermal and alternating magnetic fields demagnetizations. Detailed rock magnetic analyses, including thermomagnetic analyses and classical high magnetic field experiments revealed titanomagnetites with different Ti-content as the primary magnetic carrier, capable of recording stable remanent magnetizations. In both islands, the paleomagnetic analysis yields a Characteristic Remanent Magnetization, which presents island mean direction with normal and reversed polarities in agreement with the islands location and the age of the studied lava flows, indicating a primary thermo-remanent magnetization. Field observations and paleomagnetic data show that lava flows were emplaced on pre-existing slopes and were later affected by significant tilting. In Faial Island, magmatic inflation and normal faults making up an island-scale graben, can be responsible for the tilting. In Pico Island, inflation related to magma intrusion during flow emplacement can be at the origin of the inferred tilting, whereas gradual downward movement of the SE flank by slumping processes appears mostly translational.

Effects of volcanic ash on the forest canopy insects of Montserrat, West Indies.

PubMed

Marske, Katharine A; Ivie, Michael A; Hilton, Geoff M

2007-08-01

The impact of ash deposition levels on canopy arthropods was studied on the West Indian island of Montserrat, the site of an ongoing volcanic eruption since 1995. Many of the island's natural habitats have been buried by volcanic debris, and remaining forests regularly receive volcanic ash deposition. To test the effect of ash on canopy arthropods, four study sites were sampled over a 15-mo period. Arthropod samples were obtained using canopy fogging, and ash samples were taken from leaf surfaces. Volcanic ash has had a significant negative impact on canopy arthropod populations, but the decline is not shared equally by all taxa present, and total population variation is within the variance attributed to other aboitic and biotic factors. The affected populations do not differ greatly from those of the neighboring island of St. Kitts, which has not been subject to recent volcanic activity. This indicates that observed effects on Montserrat's arthropod fauna have a short-term acute response to recent ash deposition rather than a chronic depression caused by repeated exposure to ash over the last decade.

Palaeo-islands as refugia and sources of genetic diversity within volcanic archipelagos: the case of the widespread endemic Canarina canariensis (Campanulaceae).

PubMed

Mairal, M; Sanmartín, I; Aldasoro, J J; Culshaw, V; Manolopoulou, I; Alarcón, M

2015-08-01

Geographical isolation by oceanic barriers and climatic stability has been postulated as some of the main factors driving diversification within volcanic archipelagos. However, few studies have focused on the effect that catastrophic volcanic events have had on patterns of within-island differentiation in geological time. This study employed data from the chloroplast (cpDNA haplotypes) and the nuclear (AFLPs) genomes to examine the patterns of genetic variation in Canarina canariensis, an iconic plant species associated with the endemic laurel forest of the Canary Islands. We found a strong geographical population structure, with a first divergence around 0.8 Ma that has Tenerife as its central axis and divides Canarian populations into eastern and western clades. Genetic diversity was greatest in the geologically stable 'palaeo-islands' of Anaga, Teno and Roque del Conde; these areas were also inferred as the ancestral location of migrant alleles towards other disturbed areas within Tenerife or the nearby islands using a Bayesian approach to phylogeographical clustering. Oceanic barriers, in contrast, appear to have played a lesser role in structuring genetic variation, with intra-island levels of genetic diversity larger than those between-islands. We argue that volcanic eruptions and landslides after the merging of the palaeo-islands 3.5 Ma played key roles in generating genetic boundaries within Tenerife, with the palaeo-islands acting as refugia against extinction, and as cradles and sources of genetic diversity to other areas within the archipelago. © 2015 John Wiley & Sons Ltd.

Landslides density map of S. Miguel Island, Azores archipelago

NASA Astrophysics Data System (ADS)

Valadão, P.; Gaspar, J. L.; Queiroz, G.; Ferreira, T.

The Azores archipelago is located in the Atlantic Ocean and is composed of nine volcanic islands. S. Miguel, the largest one, is formed by three active, E-W trending, trachytic central volcanoes with caldera (Sete Cidades, Fogo and Furnas). Chains of basaltic cinder cones link those major volcanic structures. An inactive trachytic central volcano (Povoação) and an old basaltic volcanic complex (Nordeste) comprise the easternmost part of the island. Since the settlement of the island early in the 15th century, several destructive landslides triggered by catastrophic rainfall episodes, earthquakes and volcanic eruptions occurred in different areas of S. Miguel. One unique event killed thousands of people in 1522. Houses and bridges were destroyed, roads were cut, communications, water and energy supply systems became frequently disrupted and areas of fertile land were often buried by mud. Based on (1) historical documents, (2) aerial photographs and (3) field observations, landslide sites were plotted on a topographic map, in order to establish a landslide density map for the island. Data obtained showed that landslide hazard is higher on (1) the main central volcanoes where the thickness of unconsolidated pyroclastic deposits is considerable high and (2) the old basaltic volcanic complex, marked by deep gullies developed on thick sequences of lava flows. In these areas, caldera walls, fault scarps, steep valley margins and sea cliffs are potentially hazardous.

Volcanic hazard assessment for the Canary Islands (Spain) using extreme value theory, and the recent volcanic eruption of El Hierro

NASA Astrophysics Data System (ADS)

Sobradelo, R.; Martí, J.; Mendoza-Rosas, A. T.; Gómez, G.

2012-04-01

The Canary Islands are an active volcanic region densely populated and visited by several millions of tourists every year. Nearly twenty eruptions have been reported through written chronicles in the last 600 years, suggesting that the probability of a new eruption in the near future is far from zero. This shows the importance of assessing and monitoring the volcanic hazard of the region in order to reduce and manage its potential volcanic risk, and ultimately contribute to the design of appropriate preparedness plans. Hence, the probabilistic analysis of the volcanic eruption time series for the Canary Islands is an essential step for the assessment of volcanic hazard and risk in the area. Such a series describes complex processes involving different types of eruptions over different time scales. Here we propose a statistical method for calculating the probabilities of future eruptions which is most appropriate given the nature of the documented historical eruptive data. We first characterise the eruptions by their magnitudes, and then carry out a preliminary analysis of the data to establish the requirements for the statistical method. Past studies in eruptive time series used conventional statistics and treated the series as an homogeneous process. In this paper, we will use a method that accounts for the time-dependence of the series and includes rare or extreme events, in the form of few data of large eruptions, since these data require special methods of analysis. Hence, we will use a statistical method from extreme value theory. In particular, we will apply a non-homogeneous Poisson process to the historical eruptive data of the Canary Islands to estimate the probability of having at least one volcanic event of a magnitude greater than one in the upcoming years. Shortly after the publication of this method an eruption in the island of El Hierro took place for the first time in historical times, supporting our method and contributing towards the validation of our results.

Investigating volcanic hazard in Cape Verde Islands through geophysical monitoring: network description and first results

NASA Astrophysics Data System (ADS)

Faria, B.; Fonseca, J. F. B. D.

2014-02-01

We describe a new geophysical network deployed in the Cape Verde Archipelago for the assessment and monitoring of volcanic hazards as well as the first results from the network. Across the archipelago, the ages of volcanic activity range from ca. 20 Ma to present. In general, older islands are in the east and younger ones are in the west, but there is no clear age progression of eruptive activity as widely separated islands have erupted contemporaneously on geological timescales. The overall magmatic rate is low, and there are indications that eruptive activity is episodic, with intervals between episodes of intense activity ranging from 1 to 4 Ma. Although only Fogo Island has experienced eruptions (mainly effusive) in the historic period (last 550 yr), Brava and Santo Antão have experienced numerous geologically recent eruptions, including violent explosive eruptions, and show felt seismic activity and geothermal activity. Evidence for recent volcanism in the other islands is more limited and the emphasis has therefore been on monitoring of the three critical islands of Fogo, Brava and Santo Antão, where volcanic hazard levels are highest. Geophysical monitoring of all three islands is now in operation. The first results show that on Fogo, the seismic activity is dominated by hydrothermal events and volcano-tectonic events that may be related to settling of the edifice after the 1995 eruption; in Brava by volcano-tectonic events (mostly offshore), and in Santo Antão by volcano-tectonic events, medium-frequency events and harmonic tremor. Both in Brava and in Santo Antão, the recorded seismicity indicates that relatively shallow magmatic systems are present and causing deformation of the edifices that may include episodes of dike intrusion.

Investigating volcanic hazard in Cape Verde Islands through geophysical monitoring: network description and first results

NASA Astrophysics Data System (ADS)

Faria, B.; Fonseca, J. F. B. D.

2013-09-01

We describe a new geophysical network deployed in the Cape Verde archipelago for the assessment and monitoring of volcanic hazards, and the first results from the network. Across the archipelago, the ages of volcanic activity range from ca. 20 Ma to present. In general, older islands are in the east and younger ones are in the west, but there is no clear age progression and widely-separated islands have erupted contemporaneously on geological time scales. The overall magmatic rate is low, and there are indications that eruptive activity is episodic, with intervals between episodes of intense activity ranging from 1 to 4 Ma. Although only Fogo island has experienced eruptions (mainly effusive) in the historic period (last 550 yr), Brava and Santo Antão have experienced numerous geologically recent eruptions including violent explosive eruptions, and show felt seismic activity and geothermal activity. Evidence for recent volcanism in the other islands is more limited and the emphasis has therefore been on monitoring of the three critical islands of Fogo, Brava and Santo Antão, where volcanic hazard levels are highest. Geophysical monitoring of all three islands is now in operation. The first results show that in Fogo the seismic activity is dominated by hydrothermal events and volcano-tectonic events that may be related to settling of the edifice after the 1995 eruption; in Brava by volcano-tectonic events (mostly offshore), and in Santo Antão by volcano-tectonic events, medium frequency events and harmonic tremor. Both in Brava and in Santo Antão, the recorded seismicity indicates that relatively shallow magmatic systems are present and causing deformation of the edifices that may include episodes of dike intrusion.

Hazard Potential of Volcanic Flank Collapses Raised by New Megatsunami Evidence

NASA Astrophysics Data System (ADS)

Ramalho, R. S.; Winckler, G.; Madeira, J.; Helffrich, G. R.; Hipólito, A.; Quartau, R.; Adena, K.; Schaefer, J. M.

2015-12-01

Large-scale gravitational flank collapses of steep volcanic islands are hypothetically capable of triggering megatsunamis with highly catastrophic effects. Yet evidence for the existence and impact of collapsed-triggered megatsunamis and their run-up heights remains scarce and/or is highly contentious. Therefore a considerable debate still exists over the potential magnitude of collapse-triggered tsunamis and their inherent hazard. In particular, doubts still remain whether or not large-scale flank failures typically generate enough volume flux to result in megatsunamis, or alternatively operate by slow-moving or multiple smaller episodic failures with much lower tsunamigenic potential. Here we show that one of the tallest and most active oceanic volcanoes on Earth - Fogo, in the Cape Verde Islands - collapsed catastrophically and triggered a megatsunami with devastating near-field effects ~73,000 years ago. Our deductions are based on the recent discovery and cosmogenic 3He dating of tsunamigenic deposits - comprising fields of stranded megaclasts, chaotic conglomerates, and sand sheets - found on the adjacent Santiago Island, which attest to the impact of this megatsunami and document wave run-up heights exceeding 270 m. The evidence reported here implies that Fogo's flank failure involved at least one sudden and voluminous event that resulted in a megatsunami, in contrast to what has been suggested before. Our work thus provides another line of evidence that large-scale flank failures at steep volcanic islands may indeed happen catastrophically and are capable of triggering tsunamis of enormous height and energy. This new line of evidence therefore reinforces the hazard potential of volcanic island collapses and stands as a warning that such hazard should not be underestimated, particularly in areas where volcanic island edifices are close to other islands or to highly populated continental margins.

High-resolution K-Ar dating of a complex magmatic system: The example of Basse-Terre Island (French West Indies)

NASA Astrophysics Data System (ADS)

Ricci, J.; Quidelleur, X.; Pallares, C.; Lahitte, P.

2017-10-01

For the first time in the Lesser Antilles volcanic arc, we combine for one island, 123 K-Ar ages, with 133 major and trace elements geochemical analyses, in order to better constrain the volcanic history of Basse-Terre Island. In this study, nine new ages have been obtained from the southern part of the island, and complemented with eighty-three new major and trace element analyses of samples collected across the island. The southern part of Basse-Terre Island has been the loci of volcanic activity since the last 200 kyr. It is characterized by the construction of the Grande-Découverte Volcanic Complex (GDVC) composed by the Grande-Découverte - Soufrière (GDS) and the Trois-Rivières Madeleine Field (TRMF). After the onset of construction at least at 205 ± 28 ka, the GDVC displays strikingly continuous activity between 140 ± 13 and 56 ± 3 ka, followed by a 30 kyr volcanic hiatus, which is coeval with the hiatus also observed for the TRMF activity. Two new ages of 125 ± 14 and 140 ± 13 ka obtained on a lava flow from the Grande-Découverte caldera wall suggest the presence of a depression, resulting of a major flank collapse and/or explosive event, before 140 ka. Finally, a new age of 9 ± 6 ka, obtained from outcrops exposed on the edge of the Class River, in the north of the GDVC, allows us to calculate channel incision rates between 11 and 56 mm/yr. These values are consistent with incision rates determined on other volcanic islands with similar climates. In a broad sense, the petrology and geochemistry of Basse-Terre Island rocks appear fairly homogeneous, with mainly andesite and basaltic-andesite rocks and typical features of volcanic-arc lavas. Nevertheless, in detail, various magmatic processes can be discerned. Most variations are principally controlled by crystal-melt fractionation-accumulation, but major and trace elements also highlight episodic magmatic recharge, involving magma mixing. There are also indications for assimilation of crustal rocks with continental affinity, as well as mantle input of slab-derived fluids. Trace element ratios suggest the presence of at least two different magmatic sources characterized by different partial melting rates and different continental contributions for Basse-Terre Island. Different massifs show a bimodal behavior, with the Basal Complex, the Axial Chain (Piton de Bouillante and Southern Axial Chain), the Monts-Caraïbes volcanoes and the Sans-Toucher volcano in the first group, and the Septentrional Chain, and the Grande-Découverte Volcanic Complex (GDS and TRMF) in the second. Given the unique amount of time-constrained geochemical data, this study provides a complete and detailed investigation of volcanic evolution in the central part of the Lesser Antilles active arc.

Widespread Neogene and Quaternary Volcanism on Central Kerguelen Plateau, Southern Indian Ocean

NASA Astrophysics Data System (ADS)

Duncan, R. A.; Falloon, T.; Quilty, P. G.; Coffin, M. F.

2016-12-01

We report new age determinations and compositions for rocks from 18 dredge hauls collected from eight submarine areas across Central Kerguelen Plateau (CKP). Sea knolls and volcanic fields with multiple small cones were targeted over a 125,000 km2 region that includes Heard and McDonald islands. Large early Miocene (16-22 Ma) sea knolls rise from the western margin of the CKP and are part of a NNW-SSE line of volcanic centers that lie between Îles Kerguelen and Heard and McDonald islands. A second group of large sea knolls is aligned E-W across the center of this region. We see evidence of much younger activity (5 Ma to present) in volcanic fields to the north of, and up to 300 km NE of Heard Island. Compositions include basanite, basalt, and trachybasalt, that are broadly similar to plateau lava flows from nearby Ocean Drilling Program (ODP) Site 1138, lower Miocene lavas at Îles Kerguelen, dredged rocks from the early Miocene sea knolls, and Big Ben lavas from Heard Island. Geochemical data indicate decreasing fractions of mantle source melting with time. The western line of sea knolls has been related to hotspot activity now underlying the Heard Island area. In view of the now recognized much larger area of young volcanic activity, we propose that a broad region of CKP became volcanically active in Neogene time due to incubation of plume material at the base of the relatively stationary overlying plateau. The presence of pre-existing crustal faults promotes access for melts from the Heard mantle plume to rise to the surface.

Diffuse CO_{2} degassing monitoring of the oceanic active volcanic island of El Hierro, Canary Islands, Spain

NASA Astrophysics Data System (ADS)

Hernández, Pedro A.; Norrie, Janice; Withoos, Yannick; García-Merino, Marta; Melián, Gladys; Padrón, Eleazar; Barrancos, José; Padilla, Germán; Rodríguez, Fátima; Pérez, Nemesio M.

2017-04-01

Even during repose periods, volcanoes release large amounts of gases from both visible (fumaroles, solfataras, plumes) and non-visible emanations (diffuse degassing). In the last 20 years, there has been considerable interest in the study of diffuse degassing as a powerful tool in volcano monitoring programs, particularly in those volcanic areas where there are no visible volcanic-hydrothermal gas emissions. Historically, soil gas and diffuse degassing surveys in volcanic environments have focused mainly on CO2 because it is, after water vapor, the most abundant gas dissolved in magma. As CO2 travels upward by advective-diffusive transport mechanisms and manifests itself at the surface, changes in its flux pattern over time provide important information for monitoring volcanic and seismic activity. Since 1998, diffuse CO2 emission has been monitored at El Hierro Island, the smallest and south westernmost island of the Canarian archipelago with an area of 278 km2. As no visible emanations occur at the surface environment of El Hierro, diffuse degassing studies have become the most useful geochemical tool to monitor the volcanic activity in this volcanic island. The island experienced a volcano-seismic unrest that began in July 2011, characterized by the location of a large number of relatively small earthquakes (M<2.5) beneath El Hierro at depths between 8 and 15 km. On October 12, 2011, a submarine eruption was confirmed during the afternoon of October 12, 2011 by visual observations off the coast of El Hierro, about 2 km south of the small village of La Restinga in the southernmost part of the island. During the pre-eruptive and eruptive periods, the time series of the diffuse CO2 emission released by the whole island experienced two significant increases. The first started almost 2 weeks before the onset of the submarine eruption, reflecting a clear geochemical anomaly in CO2 emission, most likely due to increasing release of deep seated magmatic gases to the surface. The second one, between October 24 and November 27, 2011, before the most energetic seismic events of the volcanic-seismic unrest (Melián et al., 2014. J. Geophys. Res. Solid Earth, 119, 6976-6991). The highest CO2 degassing rate measured in the last three years (1684 t/d) was observed during a seismo-volcanic unrest. This value decreased until close to background value (˜422 t/d, Melián et al., 2014) contemporaneously with the decline of the seismic activity during the first half of 2013. The last diffuse CO2 degassing survey was carried out in the summer of 2016, showing a emission rate of 854 t/d. Discrete surveys of diffuse CO2 emission have provided important information to optimize the early warning system in the volcano monitoring programs of El Hierro and to monitor the evolution of an ongoing volcanic eruption, even though is a submarine eruption.

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

NASA Technical Reports Server (NTRS)

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

1991-01-01

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

2015 Volcanic activity in Alaska—Summary of events and response of the Alaska Volcano Observatory

USGS Publications Warehouse

Dixon, James P.; Cameron, Cheryl E.; Iezzi, Alexandra M.; Wallace, Kristi

2017-09-28

The Alaska Volcano Observatory (AVO) responded to eruptions, volcanic unrest or suspected unrest, and seismic events at 14 volcanic centers in Alaska during 2015. The most notable volcanic activity consisted of continuing intermittent ash eruptions from Cleveland and Shishaldin volcanoes in the Aleutian Islands. Two eruptive episodes, at Veniaminof and Pavlof, on the Alaska Peninsula ended in 2015. During 2015, AVO re-established the seismograph network at Aniakchak, installed six new broadband seismometers throughout the Aleutian Islands, and added a Multiple component Gas Analyzer System (MultiGAS) station on Augustine.

Diffuse Helium Emission as a Precursory Sign of Volcanic Unrest

NASA Astrophysics Data System (ADS)

Padron, E.; Perez, N.; Hernandez Perez, P. A.; Sumino, H.; Melian Rodriguez, G.; Barrancos, J.; Nolasco, D.; Padilla, G.; Dionis, S.; Rodriguez, F.; Hernandez, I.; Calvo, D.; Peraza, M.; Nagao, K.

2012-12-01

Since July 16, 2011, an anomalous seismicity at El Hierro island, the youngest and smallest of the Canary Islands, was recorded by IGN seismic network. After the occurrence of more than 10,000 seismic events, volcanic tremor was recorded since 05:15 of the October 10, by all of the seismic stations on the island, with highest amplitudes recorded in the southernmost station. During the afternoon of October 12 a large light-green coloured area was observed in the sea to the souht of La Restinga village (at the southernmost part of El Hierro island), suggesting the existence of a submarine eruption. Since October 12, frequent episodes of, turbulent gas emission and foaming, and the appearance of steamy lava fragments has been observed on the sea surface. As part of the volcanic surveillance of the island, the Instituto Volcanologico de Canarias (INVOLCAN) geochemical monitoring program is carrying out diffuse helium surveys on the surface environment of El Hierro (soil atmosphere). This nobel gas has been investigated because it has been considered an almost ideal geochemical indicator because it is chemically inert, physically stable, nonbiogenic, sparingly soluble in water under ambient conditions and almost non-adsorbable. At each survey, 600 sampling sites covering the whole island and following an homogeneous distribution are selected for helium measurements in the soil gases, The helium concentration gradients with respect to its value on air (5.24 ppm) allow us to estimate a pure diffusive emission rate of helium throughout the island. The first survey was carried out on the summer of 2003, when the island was on a quiescence period. At this survey, the amount of helium released by the volcanic system of El Hierro was estimated in 6 kg/d. Since the beginning of the seismic unrest, 13 helium emission surveys have been carried out. The helium emission rate has shown an excellent agreement with the evolution of the volcanic crisis of the island, reaching 30 kg/d on November 6, several days before the occurrence of the submarine eruption. A significant decrease to 13 kg/d was estimated almost 10 days after the beginning of the eruption, followed by a sudden increase to 38 kg/d several days before the largest seismic event of the volcanic crisis (M = 4.6) occurred on November 11. High volcanic-gas pressure in a magma surrounded by a less deformed and fractured crust could be responsible for the high magmatic-helium emission rate and eventual submarine eruption during the first segment of activity, whereas the second segment causing extensive crustal deformation and fracturing resulted in a low gas pressure on the magma and relatively low magmatic-helium diffuse emission rates. The energy loss in the system from the release of volcanic gases might be responsible for the observed decrease in the seismic energy released and the absence of a second volcanic eruption. The system continued to degas for one month, producing a gradual decrease in the helium emission rate. Helium emission data shown in this report demonstrate that diffuse helium surveys is a powerful tool for volcano monitoring. The geochemical parameters presented here are extremely important for forecasting the onset of volcanic unrest and subsequent volcanic eruptions, mainly when magma migrates aseismically, i.e., silently, toward the surface.

Tarakan, Kalimantan, Borneo, Indonesia

NASA Technical Reports Server (NTRS)

1989-01-01

Situated on the NW coast of Borneo, the island city of Tarakan (4.0N, 117.5E) in the Kalimantan state of Borneo, Indonesia, dominates the entrance to the estuary. Like all Pacific islands, Borneo is volcanic in origin and much of it's volcanic past can still be observed today. The large volcano just to the north of the delta is Mt. Magdalena and a line of older, almost eroded volcanic features can be seen extending east and northeast to the coast.

Winds, Eddies and Flow through Straits

DTIC Science & Technology

2010-01-01

driven origin of the Philippine dipole eddies. By contrast, in other volcanic island regions of the world (including the Hawaiian, Cabo Verde, and... volcanic island regions of the world. By contrast in the Hawaiian, Cabo Verde and Canary Islands, the driving mechanism in the eddy dynamics is...J. Aristegui, and F. Herrera (2000), Lee region of Gran Canaria , J. Geophys. Res., 105(C7), 17173-17193. Chang, C.-P., Z. Wang, and H. Hendon

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

USGS Publications Warehouse

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

1998-01-01

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

Jeju ground water containing vanadium induced immune activation on splenocytes of low dose γ-rays-irradiated mice.

PubMed

Ha, Danbee; Joo, Haejin; Ahn, Ginnae; Kim, Min Ju; Bing, So Jin; An, Subin; Kim, Hyunki; Kang, Kyung-goo; Lim, Yoon-Kyu; Jee, Youngheun

2012-06-01

Vanadium, an essential micronutrient, has been implicated in controlling diabetes and carcinogenesis and in impeding reactive oxygen species (ROS) generation. γ-ray irradiation triggers DNA damage by inducing ROS production and causes diminution in radiosensitive immunocytes. In this study, we elucidate the immune activation capacities of Jeju water containing vanadium on immunosuppression caused by γ-ray irradiation, and identify its mechanism using various low doses of NaVO(3). We examined the intracellular ROS generation, DNA damage, cell proliferation, population of splenocytes, and cytokine/antibody profiles in irradiated mice drinking Jeju water for 180 days and in non-irradiated and in irradiated splenocytes both of which were treated with NaVO(3). Both Jeju water and 0.245 μM NaVO(3) attenuated the intracellular ROS generation and DNA damage in splenocytes against γ-ray irradiation. Splenocytes were significantly proliferated by the long-term intake of Jeju water and by 0.245 μM NaVO(3) treatment, and the expansion of B cells accounted for the increased number of splenocytes. Also, 0.245 μM NaVO(3) treatment showed the potency to amplify the production of IFN-γ and total IgG in irradiated splenocytes, which correlated with the expansion of B cells. Collectively, Jeju water containing vanadium possesses the immune activation property against damages caused by γ-irradiation. Copyright © 2012 Elsevier Ltd. All rights reserved.

Reconsideration of evolutionary model of the Hawaiian-type volcano: 40Ar/39Ar ages for lavas from deep interior of Oahu Island and alkali basalts from the North Arch volcanic field

NASA Astrophysics Data System (ADS)

Uto, K.; Ishizuka, O.; Garcia, M. O.; Clague, D. A.; Naka, J.

2002-12-01

Growth history of Hawaiian-type volcanoes is typified into four stages: pre-shield, shield-forming, post-shield and rejuvinated. Duration of volcanism from pre-shield to post-shield stage is considered to be at most two million years, and is followed by the rejuvinated-stage after the dormance of one to two million years. There are, however, considerable amount of volcanic products hidden beneath the surface, and the above model may not be real due to the limited observation. US-Japan joint research on Hawaiian volcanism using ROV {\\KAIKO} and submersible {\\SHINKAI6500} of JAMSTEC has revealed many unknown volcanic processes of Hawaii. We challenge the well-established growth model of Hawaiian volcanoes from 40Ar/39Ar dating on rocks collected from the deep root of the submarine cliff of Oahu Island and from the widespread lava field off the coast of Oahu. Northern slope of Oahu Island is a deeply dissected steep wall from the ridge 1,000 m above the sea level to 3,000 m beneath the sea level. We expected to discover the deeper part of volcanic products forming Oahu Island. We obtained 6 40Ar/39Ar ages for tholeiitic lavas collected from 3,000 m to 2,600 m below the sea level. Ages are 5.7 and 6 Ma for two samples from the depth of 2,800 - 3,000 m, 4 Ma for a sample from 2,630 m, 3 Ma for a rock dredged between 2,500 and 2,800m, and 2.2 Ma for a sample from 2,602 m. Ages between 2.2 and 4 Ma are compatible with existing ages on subaerial shield-forming lavas on Koolau and Waianae volcano on Oahu, but ages of 5.7 and 6 Ma are about two million years older. Duplicate analyses gave concordant results and isochron ages have atmospheric 40Ar/36Ar initials. We, therefore, consider that these ages represent eruptive ages of samples. Current results suggest that tholeiitic volcanism forming Oahu Island continued almost 4 million years, which is far longer than ever considered. Considering the 8.7 cm/y of plate velocity, volcanism continued while Oahu Island moved 350 km from the place it was born. This may suggest the dimension of Hawaiian plume if it had been fixed to the earth, or may indicate the some temporal swing of the plume. North Arch volcanic field is a wide-spread flat lava flow field of extremely silica undersaturated alkali basalts existing about 200 km north from the Hawaiian volcanic chain. Six lavas taken by {\\SHINKAI6500} and four samples dredged by USGS are dated. Ages are continuously ranging from 1.4 to 0.5 Ma, suggesting that the volcanism continued at least one million years contemporaneously with rejuvinated-stage volcanism on the islands of Oahu, Niihau, Kauai and Molokai. Chemical compositions of North-Arch lavas are within the variation of these rejuvinated-stage alkali basalts. The similarities in ages and chemistry question the origin of rejuvinated-stage volcanism. These lavas may not be peripheral products of Hawaiian plume, but represent marginal volcanoes of much larger North Arch volcanic field.

New determinations of 40Ar/39Ar isotopic ages and flow volumes for Cenozoic volcanism in the Terror Rift, Ross Sea, Antarctica

NASA Astrophysics Data System (ADS)

Rilling, S.; Mukasa, S.; Wilson, T.; Lawver, L.; Hall, C.

2009-12-01

This study provides new determinations of 40Ar/39Ar isotopic ages and flow volumes for submarine and subaerial Neogene volcanism developed within the Terror Rift, Ross Sea, Antarctica, the youngest segment of the West Antarctic Rift System. The study is based on the first dredged samples from seven seamounts north of Ross Island, as well as new data from Franklin and Beaufort Islands. The sampled foidite and basanitic lavas range in age from Quaternary (90 ± 66 ka) on a small seamount ˜10 km north of Franklin Island to 6.80 ± 0.05 Ma on Beaufort Island. These ages are consistent with ages of volcanism in both the Melbourne and Erebus Volcanic Provinces and significantly expand the documented area of Neogene magmatism in Victoria Land. There is no geographic progression of volcanism through time, but volcanism was voluminous in the Pliocene and particularly widespread during the Pleistocene. Two of the dredges sampled edifices comprised of less than 0.2 km3 of volcanic materials. The largest seamount in the study area has 58.8 km3 of volcanic material and represents growth over a period of several thousand years. Estimated minimum eruption rates range from 2 × 10-4 km3 y-1 to 2 × 10-3 km3 y-1, consistent with rates proposed for other rift systems and nearby Mt. Erebus. Recent estimates of extension magnitude for the Terror Rift correspond to minimal decompression of only 0.10 to 0.22 GPa and therefore limited melt output of a typical peridotite source.

Outbreaks of Gastroenteritis That Occurred during School Excursions in Korea Were Associated with Several Waterborne Strains of Norovirus

PubMed Central

Kim, Sung-Han; Cheon, Doo-Sung; Kim, Jin-Hyeun; Lee, Dong-Han; Jheong, Won-hwa; Heo, Young-Joo; Chung, Hyen-Mi; Jee, Youngmee; Lee, Joo-Shil

2005-01-01

In May 2004, 97 of 309 (31%) and 97 of 207 (47%) school students from geographically distant areas were affected by acute gastroenteritis during excursions to neighboring hotels. The two hotels were 300 m apart, on Jeju Island, South Korea. Several strains of norovirus, including both genogroup I and genogroup II viruses, were identified in stool samples from the students and food handlers and in groundwater from the hotels. Of these several strains of norovirus, the nucleotide sequences for one strain were identical for samples from the students, food handlers, and groundwater. PMID:16145153

Earth Observations taken by the Expedition 17 Crew

NASA Image and Video Library

2008-05-17

ISS017-E-007156 (17 May 2008) --- Volcanic plumes and volcanic fog in Hawaii are featured in this image photographed by an Expedition 17 crewmember on the International Space Station. For 25 years, Kilauea volcano on Hawaii's Big Island has been erupting continuously. Recent explosive activity that started in March 2008 is producing increased emissions of sulfur dioxide (SO2). These emissions result in a widespread caustic volcanic fog -- known as vog -- that, depending on local winds, drifts as much as 200 miles up the volcanic chain, burning throats and eyes, and inducing asthma attacks as far away as Honolulu, on the island of Oahu. An oblique view of the Hawaiian islands taken from the International Space Station -- viewed looking towards the southwest, rather than "straight down" relative to the station -- on a hazy spring day includes a regional view of three volcanic plumes from Kilauea that contribute to the vog: the plume from Halema'uma'u crater near the summit, a plume from Pu'u O'o vent along the east rift, and a plume from where lava enters the ocean on the coast outside of the park boundaries. At the time this image was taken, doctors throughout the state of Hawaii were reporting an increased caseload of people with respiratory problems. Aside from the vog, this view captures cloud formations indicative of both the large-scale air flow and the local wind patterns around the islands. The parallel lines of clouds aligned roughly northeast to southwest reveal the direction of the region's prevailing trade winds; that flow is disrupted around the islands (between Hawaii and Maui, at right), and further influenced by the local land/sea breeze which at that time had driven the cloud formations offshore and circling the islands. In addition to the Kilauea plumes, the volcanoes of Mauna Loa and Mauna Kea are also visible on the island of Hawaii (center). The uninhabited island of Kaho'olawe is just visible to the southwest of Maui.

Development and recent activity of the San Andrés landslide on El Hierro, Canary Islands, Spain

NASA Astrophysics Data System (ADS)

Klimeš, Jan; Yepes, Jorge; Becerril, Laura; Kusák, Michal; Galindo, Inés; Blahut, Jan

2016-05-01

Extremely voluminous landslides with a long run-out (also known as megalandslides) on oceanic volcanic islands are infrequent denudational processes on such islands. At the same time, they represent a major geological hazard that must be looked into to avoid negative consequences for the inhabitants of these islands. Their occurrence can be related to periods of intense seismo-volcanic activity, similar to that which occurred on El Hierro Island over 2011-2012. Landslides on volcanic islands are studied using onshore and offshore geological, geophysical and geomorphological records, considering their unique triggering conditions (e.g. lava intrusions, eruptive vents, magma chamber collapses). Previous work has pointed out similarities between specific cases of landslides on volcanic islands and deep-seated gravitational slope deformations (DSGSDs) which are typical in high mountain settings. Nevertheless, the methodological approaches and concepts used to investigate DSGSDs are not commonly applied on volcanic islands studies, even though their use may provide new information about the development stage, recent movements and future hazards. Therefore, this approach for studying the San Andrés landslide (SAL) on El Hierro (Canary Islands) has been developed applying a detailed morphological field mapping, an interpretation of digital elevation models, structural measurements, kinematic testing, and a precise movement monitoring system. The acquired information revealed a strong structural influence on the landslide morphology and the presence of sets of weakened planes acting as the sliding surfaces of the SAL or secondary landslides within its body. The presence of secondary landslides, deep erosive gullies, coastal cliffs and high on-shore relative relief also suggests a high susceptibility to future landslide movement. Direct monitoring on the landslide scarps and the slip plane, performed between February 2013 and July 2014, using an automated optical-mechanical crack gauge with a precision of up to 10- 2 mm, detected creep movement in the order of 1 mm yr- 1 with a persistent sinistral component as well as episodic horizontal and a subtle vertical movement. This monitoring will continue in the future in order to verify the initial observations, which instead of long-term movement patterns, could represent a landslide response to the period of an intense seismo-volcanic activity during 2011-12.

Integrated studies of the recent evolution of Deception Island in the geodynamic setting of the Bransfield Basin opening (Antarctica): GEOMAGDEC Project

NASA Astrophysics Data System (ADS)

Maestro, Adolfo; Gil-Imaz, Andrés.; Gil-Peña, Inmaculada; Galindo-Zaldívar, Jesús; Rey, Jorge; Soto, Ruth; López-Martínez, Jerónimo; Llave, Estefanía.; Bohoyo, Fernando; Rull, Fernando; Martínez-Frías, Jesús; Galán, Luis; Casas, David; Lunar, Rosario; Ercilla, Gemma; Somoza, Luis

2010-05-01

Deception Island shows the most recent active volcanism, evidence of several eruptions since the late 18th century, and well-known eruptions in 1967, 1969, and 1970 at the western end of the volcanic ridge of the Bransfield Trough, between the South Shetland Islands and the Antarctic Peninsula. The recent tectonic activity of the Bransfield Trough is not well defined, and it presents a controversial origin. It is currently explained by two different models: (1) Opening of the basin may be related to passive subduction of the former Phoenix Plate and subsequent rollback of the South Shetland Trench; or (2) an oblique extension along the Antarctic Peninsula continental margin generated by the sinistral movement between the Antarctic and Scotia plates. This extension develops the Bransfield Trough and spread away the South Shetland tectonic block. The GEOMAGDEC project involves a multidisciplinary and integrated research of the Deception Island based on geophysical and geological methods. The purpose of this project, funded by the Spanish research agency, is the understanding of the main processes that govern the evolution of the Deception Island into the development of Bransfield Basin during recent times. Main aims are: (1) Study of the anisotropy of the magnetic susceptibility of volcanic deposits of emerged area of Deception Island to determine the relationship between magmatism (intrusive and extrusive) with the recent tectonic activity. This task allows the reconstruction of igneous flow directions of the different volcanic units established in the island, dikes emplacement modelling in active tectonic regime, and the integration of the results obtained in a kinematic and dynamic emplacement model of the different volcanic units of the Deception Island into recent geodynamic setting of Bransfield Basin opening. (2) Lito- and crono-stratigraphy analysis of the quaternary sedimentary units that filled Port Foster (inner bay of Deception Island) on the basis of the ultra-high seismic profiles and gravity cores data acquired during oceanographic campaigns carried out using the RV. BIO/HESPERIDES. (3) Recovery of the Hydrothermal Precipitation Cells (HPCs) emplaced in Port Foster during 2001 austral summer and the mineralogical and geochemical analysis of the precipitate deposits located in the inner walls of the HPCs. The analysis of these samples will provide important information about the recent volcanic activity.

Water prospection in volcanic islands by Time Domain Electromagnetic (TDEM) surveying: The case study of the islands of Fogo and Santo Antão in Cape Verde

NASA Astrophysics Data System (ADS)

Martínez-Moreno, F. J.; Monteiro-Santos, F. A.; Madeira, J.; Bernardo, I.; Soares, A.; Esteves, M.; Adão, F.

2016-11-01

Water demand in islands, focused in agriculture, domestic use and tourism, is usually supplied by groundwater. Thus the information about groundwater distribution is an important issue in islands water resources management. Time Domain Electromagnetic (TDEM) provides underground resistivity distribution at greater depths and is of easier application than other methods. In this study TDEM technique was used for groundwater prospection in two volcanic islands with water supply problems, the islands of Fogo and Santo Antão in the Republic of Cape Verde. The 10 islands of Cape Verde Archipelago, located off the coast of Senegal (W Africa), present a semi-arid climate and thus suffer from irregular and scarce precipitation. In the Island of Fogo 26 TDEM soundings, presenting an area distribution, were performed on the SW flank of the volcanic edifice. These allowed obtaining a 3D model composed of 5 layers parallel to the topographic surface separated by 50 m depth down to - 250 m. The results indicate the presence of the water-table at a depth of 150 m in the lower ranges of the W flank of the island, and at > 200 m depth in the area above 250 m above sea level (a.s.l.). In the Island of Santo Antão 32 TDEM soundings, distributed along 5 linear profiles, were obtained on the north-eastern half of the island. The profiles are located in two regions exposed to different humidity conditions to the N and S of the main water divide. The northern flank receives the dominant trade winds first and most of the precipitation and, therefore, the water-table is shallower ( 50 m depth) than in the S ( 100 m depth). Our study demonstrates the applicability and usefulness of the TDEM method for groundwater prospection in high resistivity contexts such as in volcanic islands.

Time-space mapping of Easter Chain volcanism

NASA Astrophysics Data System (ADS)

O'Connor, John M.; Stoffers, Peter; McWilliams, Michael O.

1995-12-01

New 40Ar/ 39Ar and published K sbnd Ar ages show that the locus of volcanism along the Easter Volcanic Chain (EVC) has shifted systematically from the Nazca Ridge, at about 26 m.y., to the recently active Sala y Gomez Island/Easter Island region. This indicates a plume rather than a hotline (i.e., mantle roll) origin for the EVC. The time-space distribution of ages, combined with published ages for the Galapagos and Juan Fernandez volcanic chains, is used to reconstruct Nazca plate velocities over the past 26 m.y. A plume now located in the region of Sala y Gomez Island is most compatible with these data. West of the plume, the EVC records neither Nazca nor Pacific plate motions. This section of the EVC may be related to westward channeling of plume material to the Pacific-Nazca spreading boundary region.

Soufriere Hills, Montserrat, West Indies

NASA Technical Reports Server (NTRS)

2002-01-01

Volcanic activity on the West Indian island of Montserrat has remained high for several years-the current activity started in 1995. However, remote sensing of the island has been difficult because of frequent cloud cover. The International Space Station crew flew north of the island on a clear day in early July (July 9, 2001) and recorded a vigorous steam plume emanating from the summit of Soufriere Hills. The image also reveals the extensive volcanic mud flows (lahars) and new deltas built out from the coast from the large amounts of volcanic debris delivered downstream by the rivers draining the mountain. As a small island (only 13 x 8 km), all of Montserrat has been impacted by the eruptions. Sources of Information: Smithsonian Global Volcanism Program Italy's Volcanoes Montserrat Volcano Observatory Digital photograph number ISS002-E-9309 was taken on 9 July 2001 from Space Station Alpha and was provided by the Earth Sciences and Image Analysis Laboratory at Johnson Space Center. Additional images taken by astronauts and cosmonauts can be viewed at the NASA-JSC Gateway to Astronaut Photography of Earth.

Monitoring and Modelling the Rapid Evolution of Earth's Newest Volcanic Island: Hunga Tonga Hunga Ha'apai (Tonga) Using High Spatial Resolution Satellite Observations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garvin, James B.; Slayback, Daniel A.; Ferrini, Vi

2018-04-16

We have monitored a newly-erupted surtseyan volcanic island in the Kingdom of Tonga, unofficially known as Hunga Tonga Hunga Ha’apai (HTHH), by means of very high-resolution satellite observations. The new ~1.8 km2 island formed as a tuff cone over the course of a month-long hydro-volcanic eruption in early 2015 in the Tonga-Kermadec Islands volcanic arc. Such tephra-dominated eruptions usually produce fragile subaerial landscapes that wash away rapidly due to marine abrasion, as documented in 2009. Our measured rates of erosion are five to twenty times greater than observed at Surtsey (Iceland). Preliminary measurements of the topographic expression of the primarymore » tuff cone from the past ~ 30 months suggest an extended lifetime of at least ~ 6.5 years (and potentially up to 29 years), documenting details of its landscape evolution using satellite and ship-based remote sensing approaches never-before available at such scales for this type of newly-formed island. A new volcanic island in the southwestern Pacific Ocean that formed by means of an eruption style similar to that of Surtsey (Iceland) was monitored and observed via high resolution satellite imaging for over ~30 months since its time of formation in early 2015. This island, unofficially named Hunga Tonga Hunga Ha'apai (HTHH), was not expected to persist as land for more than a few months, but our observations have documented its lifetime for 30 months. Using topography derived from high resolution satellite images, the above-sea-level volume of the island was measured over time, leading to a "volumetric" erosion rate that was compared with other oceanic islands. The HTHH island is disappearing five times (or more) faster than Surtsey, but much slower than typical models predict, allowing detailed measurement of its erosional history at new spatial scales. Regional submarine topography (bathymetry) shows that shallow-water topology may be an important factor in explaining the unexpected lifetime of this new island, together with the likelihood of internal strengthening by hydrothermal mineralization. The stages of erosion of the HTHH island may have implications for similar landforms discovered on Mars and their formation and evolution.« less

Monitoring and Modeling the Rapid Evolution of Earth's Newest Volcanic Island: Hunga Tonga Hunga Ha'apai (Tonga) Using High Spatial Resolution Satellite Observations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garvin, J. B.; Slayback, D. A.; Ferrini, V.

We have monitored a newly-erupted surtseyan volcanic island in the Kingdom of Tonga, unofficially known as Hunga Tonga Hunga Ha’apai (HTHH), by means of very high-resolution satellite observations. The new ~1.8 km2 island formed as a tuff cone over the course of a month-long hydro-volcanic eruption in early 2015 in the Tonga-Kermadec Islands volcanic arc. Such tephra-dominated eruptions usually produce fragile subaerial landscapes that wash away rapidly due to marine abrasion, as documented in 2009. Our measured rates of erosion are five to twenty times greater than observed at Surtsey (Iceland). Preliminary measurements of the topographic expression of the primarymore » tuff cone from the past ~ 30 months suggest an extended lifetime of at least ~ 6.5 years (and potentially up to 29 years), documenting details of its landscape evolution using satellite and ship-based remote sensing approaches never-before available at such scales for this type of newly-formed island. A new volcanic island in the southwestern Pacific Ocean that formed by means of an eruption style similar to that of Surtsey (Iceland) was monitored and observed via high resolution satellite imaging for over ~30 months since its time of formation in early 2015. This island, unofficially named Hunga Tonga Hunga Ha'apai (HTHH), was not expected to persist as land for more than a few months, but our observations have documented its lifetime for 30 months. Using topography derived from high resolution satellite images, the above-sea-level volume of the island was measured over time, leading to a "volumetric" erosion rate that was compared with other oceanic islands. The HTHH island is disappearing five times (or more) faster than Surtsey, but much slower than typical models predict, allowing detailed measurement of its erosional history at new spatial scales. Regional submarine topography (bathymetry) shows that shallow-water topology may be an important factor in explaining the unexpected lifetime of this new island, together with the likelihood of internal strengthening by hydrothermal mineralization. The stages of erosion of the HTHH island may have implications for similar landforms discovered on Mars and their formation and evolution.« less

Earth Observations taken by the Expedition 18 Crew

NASA Image and Video Library

2009-02-28

ISS018-E-038182 (28 Feb. 2009) --- Mawson Peak, Heard Island is featured in this image photographed by an Expedition 18 crewmember on the International Space Station. Heard Island is located in the southern Indian Ocean, approximately 1,550 kilometers to the north of Antarctica. The island is a visible part of the Kerguelen Plateau, a submerged feature on the seafloor formed by large amounts of volcanic rock erupted over a geologically short time period within an oceanic tectonic plate ? features like these are termed large igneous provinces by geologists. Most of Heard Island is formed from volcanic rocks associated with the Big Ben stratovolcano. The northeastern slopes of the volcano are visible in shadow at the top left of this detailed astronaut photograph. Recent observed volcanic activity at Heard Island has occurred at 2,745 meters high Mawson Peak, which sits within a breached caldera (collapsed and empty magma chamber beneath a volcano) on the southwestern side of the Big Ben volcano ? the shadow cast by Mawson Peak in the image points directly to the crescent-shaped caldera rim. Detailed geologic study of the Big Ben volcano is made difficult by the presence of several glaciers, including Gotley and Lied Glaciers on the southwestern slopes. This image, taken during Southern Hemisphere summer, also reveals some of the non-glaciated, light to dark brown volcanic rock forming the island on either side of Gotley Glacier.

A survey of Enterobius vermicularis infection among children on western and southern coastal islands of the Republic of Korea

PubMed Central

Park, Jae-Hwan; Han, Eun-Taek; Kim, Won-Hee; Shin, Eun-Hee; Guk, Sang-Mee; Kim, Jae-Lip

2005-01-01

To determine the status of Enterobius vermicularis infection among children living on western and southern coastal islands of the Republic of Korea, children (3-10 years) in 39 kindergartens and primary schools were examined using the cello-tape anal swab method, during July and August 2000. Of 1,661 children examined, 307 (18.5%) were found to be positive for E. vermicularis eggs. The highest infection rate (59.3%) was found in a kindergarten and a branch school of Shinyang primary school on Chujado, Jeju-do (Province). Remarkable differences in egg positive rates were observed in different localities. The egg positive rate for boys (21.3%) was significantly higher than that of girls (15.4%) (P = 0.02). However, positive rates were not significantly dependent on age. The results of the present study show that E. vermicularis infection is highly prevalent among pre-school and primary school children living on the western and southern coastal islands of the Republic of Korea, and indicate the need for efforts to control this infection. PMID:16340301

Volcanism in slab tear faults is larger than in island-arcs and back-arcs.

PubMed

Cocchi, Luca; Passaro, Salvatore; Tontini, Fabio Caratori; Ventura, Guido

2017-11-13

Subduction-transform edge propagators are lithospheric tears bounding slabs and back-arc basins. The volcanism at these edges is enigmatic because it is lacking comprehensive geological and geophysical data. Here we present bathymetric, potential-field data, and direct observations of the seafloor on the 90 km long Palinuro volcanic chain overlapping the E-W striking tear of the roll-backing Ionian slab in Southern Tyrrhenian Sea. The volcanic chain includes arc-type central volcanoes and fissural, spreading-type centers emplaced along second-order shears. The volume of the volcanic chain is larger than that of the neighbor island-arc edifices and back-arc spreading center. Such large volume of magma is associated to an upwelling of the isotherms due to mantle melts upraising from the rear of the slab along the tear fault. The subduction-transform edge volcanism focuses localized spreading processes and its magnitude is underestimated. This volcanism characterizes the subduction settings associated to volcanic arcs and back-arc spreading centers.

Preliminary volcano-hazard assessment for the Tanaga volcanic cluster, Tanaga Island, Alaska

USGS Publications Warehouse

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

2007-01-01

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

Constraints on the diversity and distribution of coral-reef assemblages in the volcanic Northern Mariana Islands

NASA Astrophysics Data System (ADS)

Houk, P.; Starmer, J.

2010-03-01

A central problem for jurisdictional scientists and managers is to reconcile how multiple environmental regimes, encompassing continuous, intermittent and human disturbances, influence pertinent ecological management targets. The presence of heterogeneous environments throughout the volcanic Northern Mariana Islands (NMI), coupled with the availability of descriptive physical data, form the basis examining environmental-ecological relationships. Since 2003, coral abundances and macrobiota (all visibly recognizable taxa greater than 2 cm) occurrences have been estimated at 42 reef slopes along the volcanic archipelago. Analyses showed that reef types acted as surrogates of coral growth capacity and the modern assemblages residing upon them, being highest and most favorable, respectively, where relatively high salinity levels, low-to-moderate wave exposure, and an absence of volcanic activity for ~90 years existed. However, island size was the greatest constraint on species richness overall, but relations with corals were dampened by volcanic activity and increased for sponges and algae where greater connection with the island aquifer existed (i.e., relatively low salinity levels). The number of years since volcanic activity has occurred was positively related to the residuals of species-area relationships and coral cover, with a ~90-year time frame predicted for recovery. Notably, no relationships with watershed characteristics or distance from CNMI’s main fishing port and coral-reef assemblages or species richness were found. Further examination of specific management concerns, such as fisheries and feral animal populations, should be designed to account for the inherent differences in driving environmental regimes. Management strategies focused upon conserving biodiversity and ecosystem function should be centered at the island level, matching the operational scale of dominant environmental-ecological relationships. Marine reserves represent a strategy pertinent for the remote NMI; a spatial structure is discussed.

Fine-scale crustal structure of the Azores Islands from teleseismic receiver functions

NASA Astrophysics Data System (ADS)

Spieker, K.; Rondenay, S.; Ramalho, R. S.; Thomas, C.; Helffrich, G. R.

2016-12-01

The Azores plateau is located near the Mid-Atlantic Ridge (MAR) and consists of nine islands, most of which lie east of the MAR. Various methods including seismic reflection, gravity, and passive seismic imaging have been used to investigate the crustal thickness beneath the islands. They have yielded thickness estimates that range between roughly 10 km and 30 km, but until now models of the fine-scale crustal structure have been lacking. A comparison of the crustal structure beneath the islands that lie west and east of the MAR might give further constraints on the evolution of the islands. For example, geochemical studies carried out across the region predict the existence of volcanic interfaces that should be detected seismically within the shallow crust of some of the islands. In this study, we use data from ten seismic stations located on the Azores Islands to investigate the crustal structure with teleseismic P-wave receiver functions. We query our resulting receiver functions for signals associated with the volcanic edifice, the crust-mantle boundary, and potential underplated layers beneath the various islands. The islands west of the MAR have a crustal structure comprising two discontinuities - an upper one at 1-2 km depth marking the base of the volcanic edifice, and a lower one at 10 km depth that we interpret as crust-mantle boundary. The islands east of the MAR can be subdivided into two groups. The central islands that are closer to the MAR exhibit a crustal structure similar to that of the western islands, with a volcanic edifice reaching a depth of 2 km and an average crust-mantle boundary at around 12 km depth. The easternmost islands, located on the oldest lithosphere, exhibit a more complex crustal structure with evidence for a mid-crustal interface and an underplated layer, yielding an effective crust-mantle boundary at >15 km depth. The difference in structure between proximal and distal islands might be related to the age of the plate at the time of emplacement of the islands, with an older plate providing conditions that are more favourable for basaltic underplating.

Ogasawara Islands, Japan

NASA Image and Video Library

2012-11-12

This image, acquired by NASA Terra spacecraft, is of the volcanic Ogasawara Islands. The islands were listed as a UNESCO World Heritage site, in recognition of an outstanding example of ongoing evolutionary processes in oceanic island ecosystems.

Time Evolution of the Basse Terre Island (Guadeloupe, French West Indies) Effusive Volcanism from New K-Ar Cassignol-Gillot Ages.

NASA Astrophysics Data System (ADS)

Samper, A.; Quidelleur, X.; Mollex, D.; Komorowski, J. C.; Boudon, G.

2004-12-01

Radiometric dating and geochemistry of effusive volcanics have been combined with geomorphological observations in order to provide a general evolution model of the volcanic island of Basse Terre, Guadeloupe (French West Indies). More than forty new Cassignol-Gillot K-Ar ages distributed within the entire island, together with the twenty ages (Blanc, 1983; Carlut et al., 2000) previously obtained with the same technique, makes the Guadeloupe Island the best place to study the evolution of volcanic processes within the Lesser Antilles Arc. Dating was performed on the carefully separated groundmass in order to avoid K loss due to weathering and excess argon carried by mafic minerals. Ages obtained are relatively younger than previously thought on Basse Terre and range from a few ka to 2.79+-0.04 Ma. When available, the paleomagnetic polarity of the dated flows agree with the GPTS and a very good coherence of ages is observed for each massif. Our results demonstrate the general north to south migration of volcanism through time. It correlates with the main volcanic stages previously identified. The 2.75 Ma Basal Complex, the 1.81+-0.03 _ 1.15+-0.02 Ma Septentrional Chain, the 1.02+-0.02 Ma _ 0.606+-0.02 Ma Axial Chain, the 442+-6 _ 207+-28 ka Mateliane _ Sans Toucher Complex and the < 200 ka Complex of La Grande Decouverte, which outlines a relative continuity in the Basse Terre magmatism. Lavas are mainly basaltic andesites and andesites although a few basalt and dacite have also been dated. All of them are characterized by low MgO values (< 6 %), tholeiitic to calc-alkaline REE chondrite-normalized patterns and are of both low K and medium K affinity. Lavas display geochemical characteristics similar to that of the central islands of the Lesser Antilles arc. Within Basse Terre, geochemical characteristics are relatively constant through time, indicating no major change of volcanic processes during the whole subaerial activity. Finally the detailed chronological framework now available provides new constraints for estimating rates of edification and destruction at the island scale and, more generally, to help better understand the evolution of the still active Guadeloupe island Soufriere volcano.

Geology of the island of Hawaii

NASA Technical Reports Server (NTRS)

Macdonald, G. A.

1974-01-01

The account of the geology of the individual Hawaiian islands is only a progress report based very largely on the uppermost, visible parts of the Hawaiian volcanic range. The island of Hawaii today consists of five volcanic mountains. All of them are very young, and three of the volcanoes have been active in historic times. At least two other volcanoes which helped to build the island have been buried by more recent ones. Rocks exposed in the cliffs on the northeastern side of Kohala Mountain have been shown by the potassium-argon method to be about 700,000 years old.

Influence of successive phases of volcanic construction and erosion on Mayotte Island's hydrogeological functioning as determined from a helicopter-borne resistivity survey correlated with borehole geological and permeability data

NASA Astrophysics Data System (ADS)

Vittecoq, B.; Deparis, J.; Violette, S.; Jaouën, T.; Lacquement, F.

2014-02-01

The purpose of this study is to show how a multidisciplinary approach that combines geophysics, geology and hydrogeology has made it possible to: (a) significantly improve our understanding of the hydrogeological regime of the volcanic island of Mayotte, and (b) provide a new set of geophysical measurement calibration data. In 2010 a helicopter-borne geophysical survey (SkyTEM) was flown over the entire island (374 km2) with a measurement density hitherto unheard of in a volcanic environment. In addition, a database was compiled containing the geological logs of 55 boreholes. 52 of these boreholes have hydrogeological information like aquifer position and piezometric level. 21 of the boreholes have transmissivity values. Correlations were made between the inverted resistivities as obtained from the helicopter-borne TDEM profiles and the nature, age and hydrodynamic properties of the formations as obtained from the borehole data. Five hydrogeological units were mapped. These are characterized by an alternation between phases of dominant volcanic construction, with the emplacement of basaltic lavas, phonolite massifs and pyroclastic deposits, and phases of dominant erosion with the deposition of volcaniclastic material (colluvium, breccias, basaltic lavas and phonolite blocks and all materials resulting from slope slides) along the slopes and in the topographic depressions. It has also been possible to assign resistivity and permeability ranges to four of these units. Ranges that are also dependent on the age of the deposits: the younger the formation is, the greater its resistivity and the higher its permeability. The hydrogeological regime is marked by the phases of volcanic construction and erosion that succeeded one another during the geological history of Mayotte over the last 10 Ma. A conceptual model adapted to the specific geological context of this island, and differing from the Canarian and Hawaiian models, is also put forward. This model is marked by the island's “fragmented” character resulting from its geological history (several volcanic edifices, several phases of construction and erosion), and is applicable to an old volcanic island in an advanced stage of erosion and weathering, with a volcanic history similar to that of Mayotte, i.e. with climate variations and erosion periods long enough to register volcaniclastic deposits.

Tracing the origin of dissolved organic matter (DOM) in subterranean estuaries using colored DOM and amino acids

NASA Astrophysics Data System (ADS)

Kim, T.; Kwon, E.; Kim, G.

2011-12-01

In order to determine the origin of dissolved organic matter (DOM) in the subterranean estuary (STE), the mixing zone of fresh terrestrial groundwater and recirculating seawater in a coastal permeable aquifer, we conducted water sampling from two STEs with different geological settings: (1) Jeju Island beaches (Hwasun and Samyang), which are composed of volcanic rocks and sandy sediments, and (2) Hampyeong beach, which is located in a large intertidal, sandy flat zone. The distributions of salinity, total hydrolysable amino acids (THAA), dissolved organic carbon (DOC), and colored DOM (CDOM) were measured for groundwater samples in these STEs. In the Hwasun STE, the humic-like peak decreases with increasing salinity, whereas the protein-like peak does not show a clear relationship with salinity. In contrast, in the Samyang STE, both humic-like peak and protein-like peak increase with increasing salinity. These contrasting results indicate that DOM in the Hwasun STE originates mainly from terrestrial inputs, while that in the Samyang STE originates mainly from biological and/or microbial activities. In the Hampyeong STE, we observed good correlations among the biodegradation index, alanine D/L ratios, THAA concentrations, DOC, and CDOM index (both humic-like and protein-like). Together with their geographical distribution patterns, these correlations indicate that DOM in the Hampyeong STE is mainly derived from marine sediments in the course of seawater recirculation. Our study shows that CDOM and amino acids are excellent tracers of DOM in the STE where DOM is derived from diverse sources.

Reconstructing the Vulcano Island evolution from 3D modeling of magnetic signatures

NASA Astrophysics Data System (ADS)

Napoli, Rosalba; Currenti, Gilda

2016-06-01

High-resolution ground and marine magnetic data are exploited for a detailed definition of a 3D model of the Vulcano Island volcanic complex. The resulting 3D magnetic imaging, obtained by 3-D inverse modeling technique, has delivered useful constraints both to reconstruct the Vulcano Island evolution and to be used as input data for volcanic hazard assessment models. Our results constrained the depth and geometry of the main geo-structural features revealing more subsurface volcanic structures than exposed ones and allowing to elucidate the relationships between them. The recognition of two different magnetization sectors, approximatively coincident with the structural depressions of Piano caldera, in the southern half of the island, and La Fossa caldera at the north, suggests a complex structural and volcanic evolution. Magnetic highs identified across the southern half of the island reflect the main crystallized feeding systems, intrusions and buried vents, whose NNW-SSE preferential alignment highlights the role of the NNW-SSE Tindari-Letojanni regional system from the initial activity of the submarine edifice, to the more recent activity of the Vulcano complex. The low magnetization area, in the middle part of the island may result from hydrothermally altered rocks. Their presence not only in the central part of the volcano edifice but also in other peripheral areas, is a sign of a more diffuse historical hydrothermal activity than in present days. Moreover, the high magnetization heterogeneity within the upper flanks of La Fossa cone edifice is an imprint of a composite distribution of unaltered and altered rocks with different mechanical properties, which poses in this area a high risk level for failure processes especially during volcanic or hydrothermal crisis.

Precursory diffuse CO2 emission signature of the 2011 El Hierro submarine eruption, Canary Islands

NASA Astrophysics Data System (ADS)

Pérez, N. M.; Padilla, G. D.; Padrón, E.; Hernández, P. A.; Melián, G. V.; Barrancos, J.; Dionis, S.; Rodríguez, F.; Nolasco, D.; Calvo, D.; Hernández, I.; Peraza, M. D.

2012-04-01

El Hierro is the youngest and southernmost island of the Canarian archipelago and represents the summit of a volcanic shield elevating from the surrounding seafloor at depth of 4000 m to up to 1501 m above sea level. The island is believed to be near the present hotspot location in the Canaries with the oldest subaerial rocks dated at 1.12 Ma. The subaerial parts of the El Hierro rift zones (NE, NW and S Ridges) are characterized by tightly aligned dyke complexes with clusters of cinder cones as their surface expressions. Since 16 July, an anomalous seismicity at El Hierro Island was recorded by IGN seismic network. Volcanic tremor started at 05:15 on 10 October, followed on the afternoon of 12 October by a green discolouration of seawater, strong bubbling and degassing, and abundant bombs on a decimetre scale found floating on the ocean surface offshore, southwest of La Restinga village, indicating the occurrence of a submarine volcanic eruption at approximately 2 km far the coast line of La Restinga. Further episodes have occurred during November, December 2011 and January 2012, with turbulent water, foam rings, and volcanic material again reaching the sea surface. In order to improve the volcanic surveillance program of El Hierro Island and to provide a multidisciplinary approach, a continuous geochemical station to measure CO2 efflux was installed on September 2003 in Llanos de Guillen, the interception center of the three volcanic-rift zones of the island, with the aim of detecting changes in the diffuse emission of CO2 related to the seismic or volcanic activity. The station measures on an hourly basis the CO2 and H2S efflux, the CO2 and H2S air concentrations, the soil water content and temperature and the atmospheric parameters: wind speed and direction, air temperature and humidity and barometric pressure. The meteorological parameters together with the air CO2 concentration are measured 1 m above the ground and the soil water content and soil temperature are measured 40-cm deep, and recorded contemporaneously with CO2 efflux. Although time series of CO2 efflux showed background (4-5 g m-2 d-1) values before the July 16, when the seismic unrest started, and still August 30, some significant increases up to 10 g m-2 d-1 was measured prior the occurrence of peaks on the seismic energy release. Since the end of August, coinciding with a migration of the hypocenters of the seismic activity toward the south part of the island, the CO2 efflux time series started a relatively constant increase during 1 month, reaching a maximum of 19 g m-2 d-1 one week before the occurrence of the submarine volcanic eruption. Since October 5 till present, including the whole eruptive period, the CO2 efflux time series have shown a general decrease trend but with some significant emission peaks prior the occurrence of important seismic energy release episodes. This station has revealed as an important observation point to evaluate the volcanic activity of El Hierro Island since diffuse degassing of carbon dioxide seems to be associated with fluid pressure fluctuations in the volcanic system. These results demonstrated the potential of applying continuous monitoring of soil CO2 efflux to improve and optimize the detection of early warning signals of future volcanic unrest episodes at El Hierro.

"Mediterranean volcanoes vs. chain volcanoes in the Carpathians"

NASA Astrophysics Data System (ADS)

Chivarean, Radu

2017-04-01

Volcanoes have always represent an attractive subject for students. Europe has a small number of volcanoes and Romania has none active ones. The curricula is poor in the study of volcanoes. We want to make a parallel between the Mediterranean active volcanoes and the old extinct ones in the Oriental Carpathians. We made an comparison of the two regions in what concerns their genesis, space and time distribution, the specific relief and the impact in the landscape, consequences of their activities, etc… The most of the Mediterranean volcanoes are in Italy, in the peninsula in Napoli's area - Vezuviu, Campi Flegrei, Puzzoli, volcanic islands in Tirenian Sea - Ischia, Aeolian Islands, Sicily - Etna and Pantelleria Island. Santorini is located in Aegean Sea - Greece. Between Sicily and Tunisia there are 13 underwater volcanoes. The island called Vulcano, it has an active volcano, and it is the origin of the word. Every volcano in the world is named after this island, just north of Sicily. Vulcano is the southernmost of the 7 main Aeolian Islands, all volcanic in origin, which together form a small island arc. The cause of the volcanoes appears to be a combination of an old subduction event and tectonic fault lines. They can be considered as the origin of the science of volcanology. The volcanism of the Carpathian region is part of the extensive volcanic activity in the Mediterranean and surrounding regions. The Carpathian Neogene/Quaternary volcanic arc is naturally subdivided into six geographically distinct segments: Oas, Gutai, Tibles, Calimani, Gurghiu and Harghita. It is located roughly between the Carpathian thrust-and-fold arc to the east and the Transylvanian Basin to the west. It formed as a result of the convergence between two plate fragments, the Transylvanian micro-plate and the Eurasian plate. Volcanic edifices are typical medium-sized andesitic composite volcanoes, some of them attaining the caldera stage, complicated by submittal or peripheral domes or dome complexes. Dacitic volcanoes are smaller in size and consist of lava dome complexes, in places with associated pyroclastic cones and volcanic aprons. The volcanic history of Carpathian volcanic chain lasts since ca. 15 Ma, with the youngest occurring in the southern chain-terminus; the last eruption of Ciomadu volcano (Harghita) was ca. 10000 years ago. Using the knowledge acquired during the compulsory curriculum and complementary activities we we consider that the outdoor education is the best way to establish a relationship between the theory and the landscape reality in the field. As a follow up to our theoretical approach for the Earth's crust we organized two study trips in our region. During the first one the students could walk in a real crater, see scoria deposits and admire the basalt columns from Racos. In the second activity they could climb the Ciomadu volcano and go down to observe the crater lake St. Anna, the single volcanic lake in central Europe.

Complete Genome Sequence of Leptospirillum ferrooxidans Strain C2-3, Isolated from a Fresh Volcanic Ash Deposit on the Island of Miyake, Japan

PubMed Central

Fujimura, Reiko; Sato, Yoshinori; Nishizawa, Tomoyasu; Oshima, Kenshiro; Kim, Seok-Won; Hattori, Masahira; Kamijo, Takashi

2012-01-01

A diazotrophic, acidophilic, iron-oxidizing bacterium, Leptospirillum ferrooxidans, known to be difficult to cultivate, was isolated from a fresh volcanic ash deposit on the island of Miyake, Japan. Here, we report the complete genome sequence of a cultured strain, C2-3. PMID:22815442

Complete genome sequence of Leptospirillum ferrooxidans strain C2-3, isolated from a fresh volcanic ash deposit on the island of Miyake, Japan.

PubMed

Fujimura, Reiko; Sato, Yoshinori; Nishizawa, Tomoyasu; Oshima, Kenshiro; Kim, Seok-Won; Hattori, Masahira; Kamijo, Takashi; Ohta, Hiroyuki

2012-08-01

A diazotrophic, acidophilic, iron-oxidizing bacterium, Leptospirillum ferrooxidans, known to be difficult to cultivate, was isolated from a fresh volcanic ash deposit on the island of Miyake, Japan. Here, we report the complete genome sequence of a cultured strain, C2-3.

Soil gas radon and volcanic activity at El Hierro (Canary Islands) before and after the 2011-2012 submarine eruption

NASA Astrophysics Data System (ADS)

Barrancos, J.; Padilla, G.; Hernandez Perez, P. A.; Padron, E.; Perez, N.; Melian Rodriguez, G.; Nolasco, D.; Dionis, S.; Rodriguez, F.; Calvo, D.; Hernandez, I.

2012-12-01

El Hierro is the youngest and southernmost island of the Canarian archipelago and represents the summit of a volcanic shield elevating from the surrounding seafloor at depth of 4000 m to up to 1501 m above sea level. The island is believed to be near the present hotspot location in the Canaries with the oldest subaerial rocks dated at 1.12 Ma. The subaerial parts of the El Hierro rift zones (NE, NW and S Ridges) are characterized by tightly aligned dyke complexes with clusters of cinder cones as their surface expressions. Since July 16, 2011, an anomalous seismicity at El Hierro Island was recorded by IGN seismic network. Volcanic tremor started at 05:15 hours on October 10, followed on the afternoon of October 12 by a green discolouration of seawater, strong bubbling and degassing indicating the initial stage of submarine volcanic eruption at approximately 2 km off the coast of La Restinga, El Hierro. Soil gas 222Rn and 220Rn activities were continuously measured during the period of the recent volcanic unrest occurred at El Hierro, at two different geochemical stations, HIE02 and HIE03. Significant increases in soil 222Rn activity and 222Rn/220Rn ratio from the soil were observed at both stations prior the submarine eruption off the coast of El Hierro, showing the highest increases before the eruption onset and the occurrence of the strongest seismic event (M=4.6). A statistical analysis showed that the long-term trend of the filtered data corresponded closely to the seismic energy released during the volcanic unrest. The observed increases of 222Rn are related to the rock fracturing processes (seismic activity) and the magmatic CO2 outflow increase, as observed in HIE03 station. Under these results, we find that continuous soil radon studies are important for evaluating the volcanic activity of El Hierro and they demonstrate the potential of applying continuous monitoring of soil radon to improve and optimize the detection of early warning signals of future volcanic unrest episodes at El Hierro Island.

A Proposed Community Network For Monitoring Volcanic Emissions In Saint Lucia, Lesser Antilles

NASA Astrophysics Data System (ADS)

Joseph, E. P.; Beckles, D. M.; Robertson, R. E.; Latchman, J. L.; Edwards, S.

2013-12-01

Systematic geochemical monitoring of volcanic systems in the English-speaking islands of the Lesser Antilles was initiated by the UWI Seismic Research Centre (SRC) in 2000, as part of its volcanic surveillance programme for the English-speaking islands of the Lesser Antilles. This programme provided the first time-series observations used for the purpose of volcano monitoring in Dominica and Saint Lucia, permitted the characterization of the geothermal fluids associated with them, and established baseline studies for understanding of the hydrothermal systems during periods of quiescence (Joseph et al., 2011; Joseph et al., 2013). As part of efforts to improve and expand the capacity of SRC to provide volcanic surveillance through its geothermal monitoring programme, it is necessary to develop economically sustainable options for the monitoring of volcanic emissions/pollutants. Towards this effort we intend to work in collaboration with local authorities in Saint Lucia, to develop a monitoring network for quantifying the background exposure levels of ambient concentrations of volcanic pollutants, SO2 in air and As in waters (as health significant marker elements in the geothermal emissions) that would serve as a model for the emissions monitoring network for other volcanic islands. This programme would facilitate the building of local capacity and training to monitor the hazardous exposure, through the application and transfer of a regionally available low-cost and low-technology SO2 measurement/detection system in Saint Lucia. Existing monitoring technologies to inform evidence based health practices are too costly for small island Caribbean states, and no government policies or health services measures currently exist to address/mitigate these influences. Gases, aerosols and toxic elements from eruptive and non-eruptive volcanic activity are known to adversely affect human health and the environment (Baxter, 2000; Zhang et al., 2008). Investigations into the impact of volcanic emissions on health have been almost exclusively focused on acute responses, or the effects of one-off eruptions (Horwell and Baxter, 2006). However, little attention has been paid to any long-term impacts on human health in the population centers around volcanoes as a result of exposure to passive emissions from active geothermal systems. The role of volcano tourism is also recognized as an important contributor to the economy of volcanic islands in the Lesser Antilles. However, if it is to be promoted as a sustainable sector of the tourism industry tourists, tour guides, and vendors must be made aware of the potential health hazards facing them in volcanic environments.

Earth Observations taken by the Expedition 14 crew

NASA Image and Video Library

2007-01-11

ISS014-E-11872 (11 Jan. 2007) --- Pagan Island, Northern Mariana Islands, is featured in this image photographed by an Expedition 14 crewmember on the International Space Station. According to scientists, the Mariana Islands are part a volcanic island arc -- surface volcanoes formed from magma generation as one tectonic plate is overridden (or subducted) beneath another. In the case of the Mariana Islands, the Pacific Plate is being subducted beneath the Philippine Plate along the famously deep Mariana Trench (more than 11 kilometers below sea level). Pagan Island (right) is comprised of two stratovolcanoes (tall, typically cone-shaped structures formed by layers of dense crystallized lava and less-dense ash and pumice) connected by a narrow isthmus of land. Mount Pagan, the larger of the two volcanoes, forms the northeastern portion of the island and has been the most active historically. The most recent major eruption took place in 1981, but since then numerous steam- and ash-producing events have been observed at the volcano -- the latest reported one occurring between Dec. 5-8, 2006. This image records volcanic activity on Jan. 11, 2007 that produced a thin plume (most probably steam, say NASA scientists, possibly with minor ash content) that extended westwards away from Mount Pagan. The island is sparsely populated, and monitored for volcanic activity by the United States Geological Survey and the Commonwealth of the Mariana Islands.

A great volcanic eruption around AD 1300 recorded in lacustrine sediment from Dongdao Island, South China Sea

NASA Astrophysics Data System (ADS)

Yang, Zhongkang; Long, Nanye; Wang, Yuhong; Zhou, Xin; Liu, Yi; Sun, Liguang

2017-02-01

The contents of Ti, Al and Fe 2 O 3 in a lacustrine sediment core (DY6) collected from Dongdao Island, South China Sea (SCS), were determined to be much higher than those in the three major sediment end-members (coral sand, guano and plants), and their likely sources include terrigenous dust and volcanic ash. At 61 cm (˜AD 1300), the contents of Ti, Al and Fe 2 O 3 have an abnormally high spike, which cannot be explained by terrigenous dust. The Sr and Nd isotope compositions at 61 cm are in excellent agreement with those in volcanic materials, but they are significantly different from those in terrigenous dust, implying a possible material input from historical volcanic eruptions in the lacustrine sediment DY6. The documented great Samalas volcanic eruption at AD 1257 in Indonesia is likely the candidate for this volcanic eruption.

Geothermal surveys in the oceanic volcanic island of Mauritius

NASA Astrophysics Data System (ADS)

Verdoya, Massimo; Chiozzi, Paolo; Pasqua, Claudio

2017-04-01

Oceanic island chains are generally characterised by young volcanic systems that are predominately composed of basaltic lavas and related magmatic products. Although hot springs are occasionally present, the pervasive, massive, recent outpourings of basaltic lavas are the primary manifestation of the existence of geothermal resources. These islands may have, in principle, significant potential for the exploitation of geothermal energy. In this paper, we present results of recent investigations aimed at the evaluation of geothermal resources of the island of Mauritius, that is the emerging portion of a huge submarine, aseismic, volcanic plateau extending in the SW part of the Indian Ocean. The plateau is related to a long-lived hotspot track, whose present-day expression is the active volcano of La Réunion Island, located about 200 km SW of Mauritius. The island does not show at present any volcanic activity, but magmatism is quite recent as it dates from 7.8 to 0.03 Myr. Geochemical data from water samples collected from boreholes do not indicate the presence of mature water, i.e. circulating in high-temperature geothermal reservoirs, and argue for short-term water-rock interaction in shallow hydrogeological circuits. However, this cannot rule out that a deep magmatic heat source, hydraulically insulated from shallow aquifers, may occur. To evaluate the geothermal gradient, a 270-m-deep hole was thus drilled in the island central portion, in which the most recent volcanic activity (0.03 Myr) took place. Temperature-depth profiles, recorded after complete thermal equilibration, revealed a thermal gradient of 40 mK/m. Attempts of extracting additional thermal information were also made by measuring the temperature in a 170-m-deep deep water hole, no longer used. The results were consistent with the gradient hole, i.e. pointing to a weak or null deep-seated thermal anomaly beneath Mauritius and low geothermal potential. The deep thermal process (mantle plume) invoked to occur in the hotspot area thus seems to yield no particular thermal signature.

Alkalic marine tephra layers at ODP Site 1241 - Major explosive eruptions from an oceanic volcano in a pre-shield stage?

NASA Astrophysics Data System (ADS)

Schindlbeck, J. C.; Kutterolf, S.; Freundt, A.; Andrews, G. D. M.; Wang, K.-L.; Völker, D.; Werner, R.; Frische, M.; Hoernle, K.

2016-12-01

We report a series of fourteen marine tephra layers that are the products of large explosive eruptions of Subplinian to Plinian intensities and magnitudes (VEI > 4) from Cocos Island, Costa Rica. Cocos Island is a volcanic island in the eastern Central Pacific Ocean 500 km offshore Costa Rica, and is situated on the northwestern flank of the aseismic Cocos Ridge. Geochemical fingerprinting of Pleistocene ( 2.4-1.4 Ma) marine tephra layers from Ocean Drilling Project (ODP) Leg 202 Site 1241 using major and trace element compositions of volcanic glass shards demonstrates unequivocally their origin from Cocos Island rather than the Galápagos Archipelago or the Central American Volcanic Arc (CAVA). Cocos Island and the adjacent seamounts of the Cocos Island Province have alkalic compositions and formed on young (≤ 3 Ma) oceanic crust from an extinct spreading ridge bounded by a transform fault against the older and thicker crust of the aseismic Cocos Ridge. Cocos Island has six times the average volume of the adjacent seamounts although all appear to have formed during the 3-1.4 Ma time period. Cocos Island lies closest to the transform fault and we explain its excessive growth by melts rising from garnet-bearing mantle being deflected from the thick Cocos Ridge lithosphere toward the thinner lithosphere on the other side of the transform, thus enlarging the melt catchment area for Cocos Island compared to the seamounts farther away from the transform. This special setting favored growth above sea level and subaerial explosive eruptions even though the absence of appropriate compositions suggests that the entirely alkalic Cocos Island (and seamounts) never evolved through the productive tholeiitic shield stage typical of other Pacific Ocean islands, possibly because melt production rates remained too small. Conditions of magma generation and ascent resembled Hawaiian pre-shield volcanoes but persisted for much longer (< 1 m.y.) and formed evolved, trachytic magmas. Therefore Cocos Island may be a unique example for a volcanic ocean island that did not pass through the typical growth stages.

Spiders on a Hot Volcanic Roof: Colonisation Pathways and Phylogeography of the Canary Islands Endemic Trap-Door Spider Titanidiops canariensis (Araneae, Idiopidae).

PubMed

Opatova, Vera; Arnedo, Miquel A

2014-01-01

Studies conducted on volcanic islands have greatly contributed to our current understanding of how organisms diversify. The Canary Islands archipelago, located northwest of the coast of northern Africa, harbours a large number of endemic taxa. Because of their low vagility, mygalomorph spiders are usually absent from oceanic islands. The spider Titanidiops canariensis, which inhabits the easternmost islands of the archipelago, constitutes an exception to this rule. Here, we use a multi-locus approach that combines three mitochondrial and four nuclear genes to investigate the origins and phylogeography of this remarkable trap-door spider. We provide a timeframe for the colonisation of the Canary Islands using two alternative approaches: concatenation and species tree inference in a Bayesian relaxed clock framework. Additionally, we investigate the existence of cryptic species on the islands by means of a Bayesian multi-locus species delimitation method. Our results indicate that T. canariensis colonised the Canary Islands once, most likely during the Miocene, although discrepancies between the timeframes from different approaches make the exact timing uncertain. A complex evolutionary history for the species in the archipelago is revealed, which involves two independent colonisations of Fuerteventura from the ancestral range of T. canariensis in northern Lanzarote and a possible back colonisation of southern Lanzarote. The data further corroborate a previously proposed volcanic refugium, highlighting the impact of the dynamic volcanic history of the island on the phylogeographic patterns of the endemic taxa. T. canariensis includes at least two different species, one inhabiting the Jandia peninsula and central Fuerteventura and one spanning from central Fuerteventura to Lanzarote. Our data suggest that the extant northern African Titanidiops lineages may have expanded to the region after the islands were colonised and, hence, are not the source of colonisation. In addition, T. maroccanus may harbour several cryptic species.

Spiders on a Hot Volcanic Roof: Colonisation Pathways and Phylogeography of the Canary Islands Endemic Trap-Door Spider Titanidiops canariensis (Araneae, Idiopidae)

PubMed Central

Opatova, Vera; Arnedo, Miquel A.

2014-01-01

Studies conducted on volcanic islands have greatly contributed to our current understanding of how organisms diversify. The Canary Islands archipelago, located northwest of the coast of northern Africa, harbours a large number of endemic taxa. Because of their low vagility, mygalomorph spiders are usually absent from oceanic islands. The spider Titanidiops canariensis, which inhabits the easternmost islands of the archipelago, constitutes an exception to this rule. Here, we use a multi-locus approach that combines three mitochondrial and four nuclear genes to investigate the origins and phylogeography of this remarkable trap-door spider. We provide a timeframe for the colonisation of the Canary Islands using two alternative approaches: concatenation and species tree inference in a Bayesian relaxed clock framework. Additionally, we investigate the existence of cryptic species on the islands by means of a Bayesian multi-locus species delimitation method. Our results indicate that T. canariensis colonised the Canary Islands once, most likely during the Miocene, although discrepancies between the timeframes from different approaches make the exact timing uncertain. A complex evolutionary history for the species in the archipelago is revealed, which involves two independent colonisations of Fuerteventura from the ancestral range of T. canariensis in northern Lanzarote and a possible back colonisation of southern Lanzarote. The data further corroborate a previously proposed volcanic refugium, highlighting the impact of the dynamic volcanic history of the island on the phylogeographic patterns of the endemic taxa. T. canariensis includes at least two different species, one inhabiting the Jandia peninsula and central Fuerteventura and one spanning from central Fuerteventura to Lanzarote. Our data suggest that the extant northern African Titanidiops lineages may have expanded to the region after the islands were colonised and, hence, are not the source of colonisation. In addition, T. maroccanus may harbour several cryptic species. PMID:25494329

Volcanic hazards of North Island, New Zealand-overview

NASA Astrophysics Data System (ADS)

Dibble, R. R.; Nairn, I. A.; Neall, V. E.

1985-10-01

In October 1980, a National Civil Defence Planning Committee on Volcanic Hazards was formed in New Zealand, and solicited reports on the likely areas and types of future eruptions, the risk to public safety, and the need for special precautions. Reports for eight volcanic centres were received, and made available to the authors. This paper summarises and quantifies the type and frequency of hazard, the public risk, and the possibilities for mitigation at the 7 main volcanic centres: Northland, Auckland, White Island, Okataina, Taupo, Tongariro, and Egmont. On the basis of Recent tephrostratigraphy, eruption probabilities up to 20% per century (but commonly 5%), and tephra volumes up to 100 km 3 are credible.

Vaccination history in elementary school children enrolled in the varicella epidemic investigations held in Jeju-si, Korea in the first half of 2017.

PubMed

Oh, Hyun-Suk; Bae, Jong-Myon

2017-01-01

The reported incidence rate of varicella infection in Jeju-do is higher compared with the national average. This study aimed to examine varicella vaccination history and evaluate clinical manifestation of varicella cases in Jeju-do. Based on the guideline suggested by the Korea Centers for Disease Control and Prevention (KCDC), two epidemic investigations for varicella infection were conducted in the first half of 2017. The history of varicella vaccination was confirmed using the Integrated Control System for Diseases and Health operated by the KCDC. Out of a total of 60 elementary school children as the study subjects, all had been previously vaccinated against varicella. Twenty cases (33%) showed mild clinical manifestations and no complications. As the government of Jeju-do has supplied a single-labeled vaccine since 2011, there is a need to evaluate the type of vaccination failure such as primary or secondary.

Digital database of the geologic map of the island of Hawai'i [Hawaii

USGS Publications Warehouse

Trusdell, Frank A.; Wolfe, Edward W.; Morris, Jean

2006-01-01

This online publication (DS 144) provides the digital database for the printed map by Edward W. Wolfe and Jean Morris (I-2524-A; 1996). This digital database contains all the information used to publish U.S. Geological Survey Geologic Investigations Series I-2524-A (available only in paper form; see http://pubs.er.usgs.gov/pubs/i/i2524A). The database contains the distribution and relationships of volcanic and surficial-sedimentary deposits on the island of Hawai‘i. This dataset represents the geologic history for the five volcanoes that comprise the Island of Hawai'i. The volcanoes are Kohala, Mauna Kea, Hualalai, Mauna Loa and Kīlauea.This database of the geologic map contributes to understanding the geologic history of the Island of Hawai‘i and provides the basis for understanding long-term volcanic processes in an intra-plate ocean island volcanic system. In addition the database also serves as a basis for producing volcanic hazards assessment for the island of Hawai‘i. Furthermore it serves as a base layer to be used for interdisciplinary research.This online publication consists of a digital database of the geologic map, an explanatory pamphlet, description of map units, correlation of map units diagram, and images for plotting. Geologic mapping was compiled at a scale of 1:100,000 for the entire mapping area. The geologic mapping was compiled as a digital geologic database in ArcInfo GIS format.

Multi-stage volcanic island flank collapses with coeval explosive caldera-forming eruptions.

PubMed

Hunt, James E; Cassidy, Michael; Talling, Peter J

2018-01-18

Volcanic flank collapses and explosive eruptions are among the largest and most destructive processes on Earth. Events at Mount St. Helens in May 1980 demonstrated how a relatively small (<5 km 3 ) flank collapse on a terrestrial volcano could immediately precede a devastating eruption. The lateral collapse of volcanic island flanks, such as in the Canary Islands, can be far larger (>300 km 3 ), but can also occur in complex multiple stages. Here, we show that multistage retrogressive landslides on Tenerife triggered explosive caldera-forming eruptions, including the Diego Hernandez, Guajara and Ucanca caldera eruptions. Geochemical analyses were performed on volcanic glasses recovered from marine sedimentary deposits, called turbidites, associated with each individual stage of each multistage landslide. These analyses indicate only the lattermost stages of subaerial flank failure contain materials originating from respective coeval explosive eruption, suggesting that initial more voluminous submarine stages of multi-stage flank collapse induce these aforementioned explosive eruption. Furthermore, there are extended time lags identified between the individual stages of multi-stage collapse, and thus an extended time lag between the initial submarine stages of failure and the onset of subsequent explosive eruption. This time lag succeeding landslide-generated static decompression has implications for the response of magmatic systems to un-roofing and poses a significant implication for ocean island volcanism and civil emergency planning.

Discovering Volcanoes in the Azores - A Field Trip

NASA Astrophysics Data System (ADS)

Brandão, Susana; Fernandes, Fátima

2013-04-01

The Azores islands are located in the North Atlantic Ocean near a triple junction, between the African, Eurasian and North American plates, at about 1500 km from the European continent and 3900 km from the North America east coast. It is formed by nine volcanic islands and a few islets dispersed along a 600 km NW-SE direction axis. The complex geological and geodynamic setting of the Azores explains its significant seismic and volcanic activity, including eruptions and degassing processes. Important landslides triggered either by earthquakes, volcanic eruptions, extreme meteorological conditions and/or coastal erosion processes frequently affect the islands, and tsunamis related with earthquakes and landslides were reported to have occurred in the past. The national curriculum for the school subject of Biology and Geology sees the Azores as a laboratory for the earth sciences and many topics revolve around it. For these reasons, we organised a field trip to the island of São Miguel, with pupils of the 11th grade who live in the Portuguese mainland, in a region that is geologically very different. During the six days of this trip, we attended training sessions in the Centre for Volcanology and Geological Risks Assessment (CVARG) of the Azores University. This multidisciplinary research unit organises activities around the prediction and prevention of disasters and natural hazards in the fields of volcanology and correlated phenomena, including volcanic eruptions, earthquakes, volcanic fumes, air pollution and water contaminants, landslides, floods and tsunamis, among others. The pupils explored volcanic calderas, lava caves, fumaroles and hot springs. They also collected and analysed extremophile bacteria that live in local hot springs.

Kaersutite-bearing xenoliths and megacrysts in volcanic rocks from the Funk Seamount in the souhtwest Indian Ocean

NASA Technical Reports Server (NTRS)

Reid, Arch M.; Le Roex, Anton P.

1988-01-01

The petrography, mineral chemistry, and whole-rock compositions of volcanic rocks dredged from the Funk Seamount, located 60 km NW of Marion Island in the southwestern Indian Ocean, are presented together with the mineral chemistry of their inclusions. On the basis of these characteristics, the possible relationships between the Funk Seamount's volcanic rocks and the megacrysts and xenoliths in these rocks are discussed. It is argued that the Funk Seamount lavas derive from a similar mantle source region as that of the Marion Island and Prince Edward Island hotspot lavas. The geochemical signature of these lavas implies derivation from a source that is enriched (e.g., in Ti, K, P, and Nb) over the depleted mantle source regions for the adjacent mid-ocean ridge basalts.

Bodotria jejuensis sp. nov. (Crustacea, Cumacea, Bodotriidae), a new Korean cumacean.

PubMed

Lee, Chang-Mok; Kim, Sung-Hyun; Kim, Young-Hyo

2016-09-06

A new species of Cumacea belonging to the genus Bodotria Goodsir, 1843 was collected from the Jeju-do Island, Korea. The new speices, Bodotria jejuensis sp. nov. is similar to B. similis Calman, 1907, B. rugosa Gamô, 1963, B. carinata Gamô, 1964, and B. biplicata Gamô, 1964 in having a pitted carapace, prominent dorso-lateral carina, and unarticulated endopod of uropod. However, longish elliptical shape of carapace, well-developed dorso-lateral carina and distinct lateral ridge are the major characteristics which serve to distinguish the new species from its congeners. The new species is fully illustrated and extensively compared with related species. A key to the Korean Bodotria species is also provided.

FIRST HIGH RESOLUTION 3D VELOCITY STRUCTURE OF THE VOLCANIC TENERIFE ISLAND (CANARY ISLANDS, SPAIN)

NASA Astrophysics Data System (ADS)

García-Yeguas, A.; Ibáñez, J.; Koulakov, I.; Sallares, V.

2009-12-01

A 3D detailed velocity model of the Tenerife Island has been obtained for first time using high resolution traveltime seismic tomography. Tenerife is a volcanic island (Canary Island, Spain) located in the Atlantic Ocean. In this island is situated the Teide stratovolcano (3718 m high) that is part of the Cañadas-Teide-Pico Viejo volcanic complex. Las Cañadas is a caldera system more than 20 kilometers wide where at least four distinct caldera processes have been identified.In January 2007, a seismic active experiment was carried out as part of the TOM-TEIDEVS project. 6850 air gun shots were fired on the sea and recorded on a dense local seismic land network consisting of 150 independent (three component) seismic stations. The good quality of the recorded data allowed identifying P-wave arrivals up to offsets of 30-40 km obtaining more than 63000 traveltimes used in the tomographic inversion. Two different codes were used in the tomographic inversion, FAST and ATOM_3D, to validate the final 3D velocity models. The main difference between them consists in the ray tracing methods used in the forward modeling, finite differences and ray bending algorithms, respectively. The velocity models show a very heterogeneous upper crust that is usual in similar volcanic environment. The tomographic images points out the no-existence of a magmatic chamber near to the surface. The ancient Las Cañadas caldera borders are clearly imaged featuring relatively high seismic velocity. Several resolution and accuracy test were carried out to quantify the reliability of the final velocity models. Checkerboard tests show that the well-resolved are located up to 6-8 km depth. We also carried out synthetic test in which we succesfully reproduce single anomalies observed in the velocity models.The uncertainties associated to the inverse problem were studied by means of a Monte Carlo-type analysis. The analysis proceeded inverting N random velocity models with random errors (velocity and traveltimes assuming the equiprobability of all of them). These tests assure the uniqueness of the first 3D velocity model that characterizes the internal structure of the Tenerife Island. As main conclusions of our work we can remark: a) This is the first 3-D velocity image of the area; b) we have observed low velocity anomalies near to surface that could be associated to the presence of magma, water reservoirs and volcanic landslides; c) high velocity anomalies could be related to ancient volcanic episodes or basement structures; d) our results could help to resolve many questions relate to the evolution of the volcanic system, as the presence or not of big landslides, calderic explosions or others; e) this image is a very important tool to improve the knowledge of the volcanic hazard, and therefore volcanic risk.

Anomalous increase of diffuse CO_{2} emission from Brava (Cape Verde): evidence of volcanic unrest or increase gas release from a stationary magma body?

NASA Astrophysics Data System (ADS)

García-Merino, Marta; García-Hernández, Rubén; Montrond, Eurico; Dionis, Samara; Fernandes, Paulo; Silva, Sonia V.; Alfama, Vera; Cabral, Jeremías; Pereira, Jose M.; Padrón, Eleazar; Pérez, Nemesio M.

2017-04-01

Brava (67 km2) is the southwestern most and the smallest inhabited island of the Cape Verde archipelago. It is located 18 km west of Fogo Island and rises 976 m from the sea level. Brava has not any documented historical eruptions, but its Holocene volcanism and relatively high seismic activity clearly indicate that it is an active volcanic island. Since there have been no historic eruptions in Brava, volcanic hazard awareness among the population and the authorities is very low; therefore, its volcano monitoring program is scarce. With the aim of helping to provide a multidisciplinary monitoring program for the volcanic surveillance of the island, diffuse CO2 emission surveys have been carried out since 2010; approximately every 2 years. Soil CO2 efflux measurements are periodically performed at ˜ 275 observation sites all over the island and after taking into consideration their accessibility and the island volcano-structural characteristics. At each sampling site, soil CO2 efflux measurement was performed by means of a portable NDIR sensor according to the accumulation chamber method. To quantify the total diffuse CO2 emission from Brava volcanic system, soil CO2 efflux maps were constructed using sequential Gaussian simulations (sGs). An increase trend of diffuse CO2 emission rate from 42 to 681 t d-1at Brava was observed; just one year prior the 2014-2015 Fogo eruption and almost three years before the anomalous seismic activity recorded on August 2016 with more than 1000 seismic events registered by the INMG on August 1st, 2016 (Bruno Faria, personal communication). Due to this anomalous seismic activity, a diffuse CO2 emission survey at Brava was performed from August 2 to 10, 2016, and the estimated degassing rate yield a value about 72 t d-1; typical background values. An additional survey was carried out from October 22 to November 6, 2016. For this last survey, the estimated diffuse CO2 emission from Brava showed the highest observed value with a degassing rate about 1.700 t d-1. These observed changes on diffuse CO2 emission are geochemical evidences which seem to support a volcanic unrest for the recent anomalous seismic activity registered at Brava.

Physico-chemical changes of the ground waters related to the 2011 El Hierro magmatic reactivation

NASA Astrophysics Data System (ADS)

Dionis, S.; Melián, G.; Padrón, E.; Padilla, G.; Nolasco, D.; Rodríguez, F.; Hernández, I.; Peraza, D.; Barrancos, J.; Hernández, P.; Calvo, D.; Pérez, N.

2012-04-01

The island of El Hierro (278 Km2), is the smallest, the southwesternmost and the youngest island (˜1.12 My) of the Canarian archipelago. The main geological characteristics of El Hierro consist on the presence of three convergent ridges of volcanic cones on a truncated trihedron shape and giant landslides between the three rift zones, being the most recent El Golfo on the northwest flank of the island. On July 2011 an anomalous seismic activity at Hierro Island started and suggested the initial stage of a volcanic unrest in the volcanic system. On October 10, after the occurrence of more than 10,000 earthquakes, a submarine eruption started. Evidences of this submarine volcanic eruption were visible on the sea surface to the south of La Restinga village, at the south of the island, in the form of large light-green coloured area, turbulent gas emission and the appearance of steamy volcanic fragments three days later. As part of its volcanic surveillance activities, the Instituto Volcanologico de Canarias (INVOLCAN) started a hydrogeochemical monitoring program on August 2011 in order to evaluate the temporal evolution of several physico-chemical parameters of the ground water system of El Hierro. Four observation sites were selected: three wells on the north of the island, where the seismic activity was located at the beginning of the volcano-seismic unrest (SIMO, FRON and PADO) and one horizontal well (gallery) in the south (TACO). Ground water sampling is being regularly collected, three times per week, at each observation site, and in-situ measurements of pH, conductivity and temperature measurements are performed. After 6 month of monitoring, no significant changes have been observed on pH and temperature measurements from all the observation sites. However, clear sharp decrease of conductivity was observed at SIMO on October 10 when the seismic tremor started. In addition, the strongest conductivity decrease pattern was observed later on at SIMO and PADO on November 4; one week earlier of the largest seismic event registered during this volcanic crisis on November 11 (M = 4.6). This observed physico-chemical changes in the ground water system might be explained as a result of the changes on the strain/stress field due to the seismic activity enhancing mixing of water bodies with different conductivities.

Influence of the submarine volcanic eruption off El Hierro (Canary Islands) on the mesopelagic cephalopod's metal content.

PubMed

Lozano-Bilbao, Enrique; Gutiérrez, Ángel José; Hardisson, Arturo; Rubio, Carmen; González-Weller, Dailos; Aguilar, Natacha; Escánez, Alejandro; Espinosa, José María; Canales, Paula; Lozano, Gonzalo

2018-04-01

This work investigates whether a submarine volcanic eruption off El Hierro (Canary Islands) in October 2011 influenced the metal contents of two deep water cephalopod species: Abraliopsis morisii and Pyroteuthis margaritifera. This was assessed by comparing metal contents in specimens collected off the island of El Hierro and in the neighbouring islands of La Palma and Tenerife during an experimental deep water fishing trip. The concentration of 20 heavy metals was analyzed in 180 specimens of A. morisii and P. margaritifera collected around the three islands to test for inter-island differences for each species and metal. While both species showed geographical differences in metal concentrations, the main finding was that A. morisii could be a bioindicator species for metals such as Li, Sr and Ca. Copyright © 2017 Elsevier Ltd. All rights reserved.

Impacts of a volcanic eruption on the forest birdcommunity of Montserrat, Lesser Antilles.

Treesearch

B. DALSGAARD; G. M. HILTON; G. A. L. GRAY; L. AYMER; J. BOATSWAIN; J. FENTON DALEY; J. MARTIN; L. MARTIN; P. MURRAIN; W. J. ARENDT; W. OLESEN GIBBONSD

2007-01-01

Volcanic eruptions are an important and natural source of catastrophic disturbance to ecological communities. However, opportunities to study them are relatively rare. Here we report on the effects of the eruption of the Soufrière Hills volcano on the forest bird community of the Lesser Antillean island of Montserrat. The island’s species-poor avifauna includes 11...

Volcanic structures and oral traditions of volcanism of Western Samoa (SW Pacific) and their implications for hazard education

NASA Astrophysics Data System (ADS)

Németh, Károly; Cronin, Shane J.

2009-10-01

The Samoan Islands have experienced > 2 million years of volcanism, culminating in historic eruptions at both the east and western ends of the chain including a major lava-producing episode on the island of Savai'i from AD 1905-1911. Upolu in Western Samoa has several areas mapped as early Holocene in age (> 5 ka), but here we present new evidence for fresh volcanic landforms and deposits, supported by a radiocarbon date of 1915 ± 65 yrs B.P., giving a maximum age to a phreatomagmatic tuff cone offshore of Cape Tapaga, east Upolu. In addition, we report on a parallel investigation of the oral traditions of communities surrounding fresh volcanic landforms that may reflect distant "volcanic memories" passed down over generations. To accommodate Samoan cultural structures, oral traditional knowledge was sought through semi-structured interviews with small groups (3-4) or individuals. Samoan facilitators focused on high-ranking and traditionally respected (particularly elderly) individuals for explanations of the origins of local features, including their genesis, use and any related geo-hazards. Areas targeted were those where young eruptions (< 3500 yr BP) were suspected from geological mapping. In stark contrast to communities in Vanuatu, Papua New Guinea or the Solomon Islands, the village communities show extremely limited knowledge of their volcanic heritage. Youthful volcanic landforms are often not recognised as such and appear to play little role in everyday life. Few, if any, legends are attached to any volcanic feature. Instead, oral traditions deal primarily with the origins of Samoans (overlain by strong Christian teachings), and past disputes/battles and wrongdoings between tribes/neighbours. The only exceptions to this were identified in legends from East Upolu, where offshore islands (tuff cones) are associated with late Holocene explosive phreatomagmatic volcanism. Maps drawn by individuals and groups interviewed, highlighted the resources and landscapes important in their lives. The majority of these were prepared as 3D oblique-view sketches, rather than plan-views, showing little in common with typical hazard maps used in the area. In addition, maps were commonly restricted strictly to boundaries of local communities, ignoring major features (such as fresh volcanic cones) that were in the territory of "next door" villages. These perspectives need to be focused upon in future iterations of hazard maps and hazard-education programmes for Samoa and similar Polynesian communities.

Quantification of the CO2 emitted from volcanic lakes in Pico Island (Azores)

NASA Astrophysics Data System (ADS)

Andrade, César; Cruz, José; Viveiros, Fátima; Branco, Rafael

2017-04-01

This study shows the results of the diffuse CO2 degassing surveys performed in lakes from Pico volcanic Island (Azores archipelago, Portugal). Detailed flux measurements using the accumulation chamber method were made at six lakes (Capitão, Caiado, Paul, Rosada, Peixinho and Negra) during two field campaigns, respectively, in winter (February 2016) and late summer (September 2016). Pico is the second largest island of the Azores archipelago with an area of 444.8 km2; the oldest volcanic unit is dated from about 300,000 years ago. The edification of Pico was mainly due to Hawaiian and Strombolian type volcanic activity, resulting in pahoehoe and aa lava flows of basaltic nature, as well as scoria and spatter cones. Three main volcanic complexes are identified in the island, namely (1) the so-called Montanha Volcanic Complex, corresponding to a central volcano located in the western side of the island that reaches a maximum altitude of 2351 m, (2) the São Roque-Piedade Volcanic Complex, and (3) the Topo-Lajes Volcanic Complex, this last one corresponding to the remnants of a shield volcano located in the south coast. The studied lakes are spread along the São Roque-Piedade Volcanic Complex at altitudes between 785 m and 898 m. Three are associated with depressions of undifferentiated origin (Caiado, Peixinho, Negra), two with depressions of tectonic origin (Capitão, Paul), while Rosada lake is located inside a scoria cone crater. The lakes surface areas vary between 1.25x10-2 and 5.38x10-2 km2, and the water column maximum depth is 7.9 m (3.5-7.9 m). The water storage ranges between 3.6x104 to 9.1x104 m3, and the estimated residence time does not exceed 1.8x10-1 years. A total of 1579 CO2 flux measurements were made during both surveys (868 in summer and 711 in the winter campaign), namely 518 in Caiado lake (293; 225), 358 in Paul (195; 163), 279 in Capitão (150, 129), 200 in Rosada (106, 94), 171 in Peixinho (71, 100) and 53 measurements in Negra lake. Negra Lake was only sampled in the summer season. The CO2 flux values range between 0.68 g m-2 d-1 (Paul lake) and 20.47 g m-2 d-1 (Negra). The total CO2 emission varies between 0.03 t d-1 (Negra and Peixinho lakes) and 0.30 t d-1 (Caiado lake) for the summer surveys, and between 0.04 t d-1 (Rosada lake) and 0.26 t d-1 (Caiado lake) for the winter data. The higher CO2 emission is observed for Rosada lake (8.89 t km-2 d-1) during summer and the lower corresponds to the Negra lake (1.67 t km-2 d-1) during summer. Considering the set of the studied volcanic lakes, the CO2 emission sums up to 64 t d-1 (winter campaign) and 72 t d-1 (summer). These emissions are probably mainly associated to a biogenic source, but the characterization of the CO2 emission in these volcanic lakes during periods of quiescence is relevant for any seismo-volcanic monitoring programme. Key words: volcanic lakes, CO2 flux, diffuse degassing, Pico Island, Azores

Relationship between subsidence and volcanic load, Hawaii

USGS Publications Warehouse

Moore, J.G.

1970-01-01

A computer analysis of tide-gage records in the northeast Pacific indicates that the active volcanic islands of eastern Hawaii are subsiding at a rate considerably faster than the eustatic rise of sea level. The rate of absolute subsidence increases progressively toward the center of current activity on the Island of Hawaii. Honolulu, Oahu, appears to be stable; Kahului, Maui, is subsiding at 1.7 mm per year; and Hilo, Hawaii, is subsiding at 4.8 mm per year. This subsidence is apparently related to downbowing of the crust throughout a zone 400 km in diameter by the weight of volcanic material added to the crust by active volcanoes, principally Mauna Loa and Kilauea on the Island of Hawaii. The Hawaiian Arch encircles the subsiding zone and may be uplifted by material moving down and outward from the zone of subsidence. The annual volume of subsidence is about 270??106 m3, whereas the average annual volume of erupted basalt on the Island of Hawaii (based on historic records back to about 1820) is about 50??106 m3. The great excess of subsidence over volcanic addition cannot be reconciled by isostatic models, and is apparently the result of other processes operating in the volcano and its basement thet are poorly understood. Probably the more important of these processes are intrusions and submarine volcanism, both of which are providing additional unseen load on the volcanoes. Furthermore, the rate of eruption may be uplifted by material moving down and outward from the zone of subsidence may be overestimated due to localized downslope movement of the margins of the islands. ?? 1970 Stabilimento Tipografico Francesco Giannini & Figli.

Monitoring quiescent volcanoes by diffuse He degassing: case study Teide volcano

NASA Astrophysics Data System (ADS)

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

2016-04-01

Tenerife (2,034 km2), the largest of the Canary Islands, is the only island that has developed a central volcanic complex (Teide-Pico Viejo stratovolcanoes), characterized by the eruption of differentiated magmas. This central volcanic complex has been built in the intersection of the three major volcanic rift-zones of Tenerife, where most of the historical volcanic activity has taken place. The existence of a volcanic-hydrothermal system beneath Teide volcano is suggested by the occurrence of a weak fumarolic system, steamy ground and high rates of diffuse CO2 degassing all around the summit cone of Teide (Pérez et al., 2013). Diffuse emission studies of non-reactive and/or highly mobile gases such as helium have recently provided promising results to detect changes in the magmatic gas component at surface related to volcanic unrest episodes (Padrón et al., 2013). The geochemical properties of He minimize the interaction of this noble gas on its movement toward the earth's surface, and its isotopic composition is not affected by subsequent chemical reactions. It is highly mobile, chemically inert, physically stable, non-biogenic, sparingly soluble in water under ambient conditions, almost non-adsorbable, and highly diffusive with a diffusion coefficient ˜10 times that of CO2. As part of the geochemical monitoring program for the volcanic surveillance of Teide volcano, yearly surveys of diffuse He emission through the surface of the summit cone of Teide volcano have been performed since 2006. Soil He emission rate was measured yearly at ˜130 sampling sites selected in the surface environment of the summit cone of Teide volcano (Tenerife, Canary Islands), covering an area of ˜0.5 km2, assuming that He emission is governed by convection and diffusion. The distribution of the sampling sites was carefully chosen to homogeneously cover the target area, allowing the computation of the total He emission by sequential Gaussian simulation (sGs). Nine surveys have been carried out since 2006, showing an average emission rate of 8.0 kg/d. This value showed an anomalous increase up to 29 kg/d in the summer of 2010. The number of seismic events registered in and around Tenerife Island by the National Geographic Institute (IGN) reached also the highest value (1,176) in 2010. This excellent agreement between both times series suggest that the anomalous seismicity registered in 2010 was likely due to strain/stress changes caused by input of magmatic fluids beneath the central volcanic system of the island. These results suggest that monitoring of He degassing rates in oceanic volcanic islands is an excellent early warning geochemical precursory signal for volcanic unrest. References Padrón et al., 2013. Geology, DOI: 10.1130/G34027.1. Pérez et al., 2013. J. Geol. Soc., DOI: 10.1144/jgs2012-125.

Ustica Island (Tyrrhenian Sea, Italy): from shoaling to emergent stage

NASA Astrophysics Data System (ADS)

Marinoni, L. B.; Pasquaré, G.; Vezzoli, L.

2003-04-01

Ustica is a volcanic island located in the southern Tyrrhenian sea, ~60 km NW of Sicily. As usual for volcanic ocean islands, its exposed part (8.6 km2, 248 m max elevation, mostly of Pleistocene age), is a small fraction of the whole edifice which rises from ~2000 m depth. Its 5-pointed-star shape is slightly elongated in a NE direction. A new geological field survey was carried out at scale 1:10000 and locally at 1:2000, establishing informal stratigraphic units that on the whole fit a common scheme of evolution for volcanic ocean islands. In this framework, the whole pre-existing stratigraphy has been revised. Ustica has a variety of volcanic deposits from submarine (basaltic effusive to explosive) to subaereal (effusive, explosive and highly explosive -Plinian?). Moreover, Ustica is one of the few places in the world where a transition of deposits from shoaling to emergent stage crop out. In fact, its oldest deposits consist of: (a) a flank-facies association of submarine lavas (variably-shaped pillows, pillow breccias and hyaloclastites) with biocalcarenite-biocalcirudite lenses, dipping coastward in the E, S and W outer parts of the island; this association is arranged in steep foreset beds (lava deltas) and is capped by flat-lying transitional to subaereal massive lava flows and surf-shaped boulder conglomerates; the geometry of this association may suggest a progressive island uplift or sea lowering during this period; (b) shallow-water to emergent tuff cone deposits in the NW part of the island. In the centre of the island, subsequent activity built a pile, now deeply eroded, of subaereal basaltic lava flows capped by a scoria cone. A previously unknown outcrop where a pumice fall layer is exposed, allows a distinction into two members of a unit that was known as formed by pyroclastic surges only. Higher in the succession, the Ustica Pumice formation (for which 4 members are defined) is underlain by a palaeosoil, and is likely the remnant of a caldera-forming eruption, which possibly dismantled the northern part of the island. It may be suggested that a later flank collapse affected the W side of the island, exposing seamount-stage deposits and allowing small fissural eruptions. The northern part of the island was then rebuilt by hydro-magmatic littoral deposits, subaereal aa flows, and thick columnar lava flows. At the NE corner of the island, a littoral tuff cone (the only cone of the island which is roughly preserved in its original shape) gave the last volcanic activity in Ustica. Acknowledgement: LBM benefited of a grant from Milan University under the supervision of Prof. G.Pasquaré in the framework of a joint venture with SGN.

Air-breathing behavior, oxygen concentrations, and ROS defense in the swimbladders of two erythrinid fish, the facultative air-breathing jeju, and the non-air-breathing traira during normoxia, hypoxia and hyperoxia.

PubMed

Pelster, Bernd; Wood, Chris M; Jung, Ellen; Val, Adalberto L

2018-05-01

The jeju Hoplerythrinus unitaeniatus and the traira Hoplias malabaricus are two neighboring genera from the family of erythrinid fish, both possessing a two-chambered physostomous swimbladder. In the jeju the anterior section of the posterior bladder is highly vascularized, and the swimbladder is used for aerial respiration; the traira, in turn, is a water-breather that uses the swimbladder as a buoyancy organ and not for aerial oxygen uptake. Measurement of swimbladder oxygen partial pressure (PO 2 ) of fish kept at 26 °C in normoxic, hyperoxic (28-32 mg O 2 L - 1 ) or hypoxic (1-1.5 mg O 2 L - 1 ) water revealed constant values in traira swimbladder. Under normoxic conditions in the jeju swimbladder PO 2 was higher than in traira, and the PO 2 significantly increased under hyperoxic conditions, even in the absence of air breathing. In jeju, air-breathing activity increased significantly under hypoxic conditions. Hypoxic air-breathing activity was negatively correlated to swimbladder PO 2 , indicating that the swimbladder was intensely used for gas exchange under these conditions. In traira, the capacity of the ROS defense system, as assessed by measurement of activities of enzymes involved in ROS degradation and total glutathione (GSH + GSSG) concentration, was elevated after 4 h of hyperoxic and/or hypoxic exposure, although swimbladder PO 2 was not affected. In jeju, experiencing a higher variability in swimbladder PO 2 due to the air-breathing activity, only a reduced responsiveness of the ROS defense system to changing environmental PO 2 was detected.

High resolution bathymetric and sonar images of a ridge southeast of Terceira Island (Azores plateau)

NASA Astrophysics Data System (ADS)

Lourenço, N.; Miranda, J. M.; Luis, J.; Silva, I.; Goslin, J.; Ligi, M.

2003-04-01

The Terceira rift is a oblique ultra-slow spreading system where a transtensive regime results from differential movement between Eurasian and African plates. So far no classical ridge segmentation pattern has here been observed. The predominant morphological features are fault controlled rhombic shaped basins and volcanism related morphologies like circular seamounts and volcanic ridges. We present SIMRAD EM300 (bathymetry + backscatter) images acquired over one of these ridges located SE of Terceira Island, during the SIRENA cruise (PI J. Goslin), which complements previous TOBI mosaics performed over the same area during the AZZORRE99 cruise (PI M. Ligi). The ridge presents a NW-SE orientation, it is seismically active (a seismic crisis was documented in 1997) and corresponds to the southern branch of a V shape bathymetric feature enclosing the Terceira Island and which tip is located west of the Island near the 1998 Serreta ridge eruption site. NE of the ridge, the core of the V, corresponds to the North Hirondelle basin. All this area corresponds mainly to Brunhes magnetic epoch. The new bathymetry maps reveal a partition between tectonic processes, centred in the ridge, and volcanism present at the bottom of the North Hirondelle basin. The ridge high backscatter surface is cut by a set of sub-parallel anastomosed normal faults striking between N130º and N150º. Some faults present horse-tail terminations. Fault splays sometimes link to neighbour faults defining extensional duplexes and fault wedge basins and highs of rhombic shape. The faulting geometry suggests that a left-lateral strike slip component should be present. The top of the ridge consists on an arched demi-.horst, and it is probably a volcanic structure remnant (caldera system?), existing prior to onset of the tectonic stage in the ridge. Both ridge flanks display gullies and mass wasting fans at the base of the slope. The ridge vicinities are almost exclusively composed of a grayish homogeneous acoustic facies interpreted as pelagic and volcanic sediment. The numerous untectonized volcanic cones present to NE, in the northern flank of the North Hirondelle basin, align-up with the three volcanic systems of the Terceira Island (progressively less eroded towards west) and the Serreta ridge, thus suggesting propagation of a melt/thermal anomaly westwards through time. This volcanic area contrasts strongly with the highly fractured pattern observed in the ridge.

Linear island and seamount chains, aseismic ridges and intraplate volcanism: Results from DSDP

USGS Publications Warehouse

Clague, David A.

1981-01-01

The Deep Sea Drilling Project drilled a substantial number of sites that bear on the origin of linear island and seamount chains, aseismic ridges and other more regional expressions of intraplate volcanism. Drilling in the Emperor Seamounts during Leg 55 was particularly successful. Results from this leg include: 1) the volcanoes of the Hawaiian-Emperor chain continue to increase in age away from Kilauea as predicted. 2) Suiko Seamount formed at a paleolatitide of 26.9±3.5°N, 7° north of present-day Hawaii, but far south of its present latitude of 44.8°N. 3) the volcanic rock types recovered include hawaiite, mugearite, alkalic basalt and tholeiitic basalt in the sequence and relative volume expected for Hawaiian volcanoes. 4) the tholeiitic and alkalic basalts recovered are geochemically similar to those in the Hawaiian Islands, only the ratio of 87Sr/86Sr appears to change through time. All the lavas appear to be derived from a source that has small-scale heterogeneities, but is homogeneous on a large scale. 4) The Emperor Seamounts were once volcanic islands that underwent subaerial and shallow marine erosion, and deposition of shallow-water biogenic carbonate sediments that capped all or most of each volcano.Drilling in other regions has yielded less conclusive results. For example, it is uncertain if the Line Islands are an age progressive chain (hot-spot trace) or result from some other type of intraplate volcanism. The mid-Pacific Mountains also show evidence of originating from a regional episode of volcanism in the mid-Cretaceous. Drilling in the Nauru Basin encountered a voluminous mid-Cretaceous volcanic flow-sill complex that overlies Jurassic magnetic anomalies, yet is composed of depleted tholeiite. In the Indian Ocean, drilling on the Ninety-East Ridge established that it 1) is volcanic in origin; 2) is older to the north; 3) formed in shallow water, and 4) formed further south and has moved northward. It appears that the Ninety-East Ridge, like the Hawaiian-Emperor chain, is a hot spot trace. In the Atlantic Ocean, drilling on the Iceland-Faeroe Ridge and the Rio Grande Rise-Walvis Ridge suggests that all these aseismic ridges are hot spot traces generated by the Iceland and Tristan de Cunha hot-spots.

USGS-NoGaDat - A global dataset of noble gas concentrations and their isotopic ratios in volcanic systems

USGS Publications Warehouse

Abedini, Atosa A.; Hurwitz, S.; Evans, William C.

2006-01-01

The database (Version 1.0) is a MS-Excel file that contains close to 5,000 entries of published information on noble gas concentrations and isotopic ratios from volcanic systems in Mid-Ocean ridges, ocean islands, seamounts, and oceanic and continental arcs (location map). Where they were available we also included the isotopic ratios of strontium, neodymium, and carbon. The database is sub-divided both into material sampled (e.g., volcanic glass, different minerals, fumarole, spring), and into different tectonic settings (MOR, ocean islands, volcanic arcs). Included is also a reference list in MS-Word and pdf from which the data was derived. The database extends previous compilations by Ozima (1994), Farley and Neroda (1998), and Graham (2002). The extended database allows scientists to test competing hypotheses, and it provides a framework for analysis of noble gas data during periods of volcanic unrest.

Volcanic alert system (VAS) developed during the 2011-2014 El Hierro (Canary Islands) volcanic process

NASA Astrophysics Data System (ADS)

García, Alicia; Berrocoso, Manuel; Marrero, José M.; Fernández-Ros, Alberto; Prates, Gonçalo; De la Cruz-Reyna, Servando; Ortiz, Ramón

2014-06-01

The 2011 volcanic unrest at El Hierro Island illustrated the need for a Volcanic Alert System (VAS) specifically designed for the management of volcanic crises developing after long repose periods. The VAS comprises the monitoring network, the software tools for analysis of the monitoring parameters, the Volcanic Activity Level (VAL) management, and the assessment of hazard. The VAS presented here focuses on phenomena related to moderate eruptions, and on potentially destructive volcano-tectonic earthquakes and landslides. We introduce a set of new data analysis tools, aimed to detect data trend changes, as well as spurious signals related to instrumental failure. When data-trend changes and/or malfunctions are detected, a watchdog is triggered, issuing a watch-out warning (WOW) to the Monitoring Scientific Team (MST). The changes in data patterns are then translated by the MST into a VAL that is easy to use and understand by scientists, technicians, and decision-makers. Although the VAS was designed specifically for the unrest episodes at El Hierro, the methodologies may prove useful at other volcanic systems.

First report of the epiphytic benthic dinoflagellates Coolia canariensis and Coolia malayensis in the waters off Jeju Island, Korea: morphology and rDNA sequences.

PubMed

Jeong, Hae Jin; Yih, Wonho; Kang, Nam Seon; Lee, Sung Yeon; Yoon, Eun Young; Yoo, Yeong Du; Kim, Hyung Seop; Kim, Jong Hyeok

2012-01-01

Coolia spp. are epiphytic and benthic dinoflagellates. Herein, we report for the first time, the occurrence of Coolia canariensis and Coolia malayensis in Korean waters. The morphology of the Korean strains of C. canariensis and C. malayensis isolated from the waters off Jeju Island, Korea was similar to that of the original Canary lslands strains and Malaysian strains, respectively. We found several pores and a line of small knobs on the pore plate, and perforations within the large pores of both C. canariensis and C. malayensis. The plates of the Korean strains of C. canariensis and C. malayensis were arranged in a Kofoidian series of Po, 3', 7'', 6c, 6s, 5''', and 2'''', and Po, 3', 7'', 7c, 6-7s, 5''', and 2'''', respectively. When properly aligned, the large subunit (LSU) rDNA sequence of the Korean strain of C. canariensis was identical to that of the Biscayan strains, but it was 2-3% different from the Canary lslands strain VGO0775 and the Australian strain. In addition, the sequences of small subunit (SSU) and/or LSU rDNA from the two Korean strains of C. malayensis were < 1% different from the Malaysian strains of C. malayensis and the Florida strain CCMP1345 and New Zealand strain CAWD39 ("Coolia monotis"). In phylogenetic trees based on LSU rDNA sequences, the Korean strains of C. malayensis belonged to a clade including the Malaysian strains and these two strains. Therefore, based on genealogical analyses, we suggest that the Korean strain of C. canariensis is closely related to two Atlantic strains and the Australian strain, whereas the Korean strains of C. malayensis are related to the Malaysian strains of C. malayensis and the Florida and New Zealand strains. © 2012 The Author(s) Journal of Eukaryotic Microbiology © 2012 International Society of Protistologists.

Vegetation and climate variability in East Asia driven by low-latitude oceanic forcing during the middle to late Holocene

NASA Astrophysics Data System (ADS)

Lim, Jaesoo; Fujiki, Toshiyuki

2011-09-01

At centennial to millennial timescales, little is known of C 3 and C 4 plant productivity's responses to past regional climate changes and the dominant forcing factors during the Holocene, although large-scale changes in glacial-interglacial periods have been attributed to changes in aridity, temperature, and CO 2 concentration. We investigated the δ 13C of TOC, C/N ratios, and pollen in samples from a wetland on Jeju Island, Korea. The bulk isotopic signal ranging from -17‰ to -29‰ was partitioned into C 3 and C 4 plant signals by using a binary mixing model and calculating separate organic carbon-accumulation rates for C 3 and C 4 plants (OCAR 3 and OCAR 4) during the last 6500 years. Pollen data indicated that the temperate deciduous broadleaved trees replaced grassland dominated by Artemisia, dry-tolerant grass, and further expanded in the maar. The long-term decreasing trend of Artemisia-dominated grassland was similar to those of δ 13C values and OCAR 4. The multi-centennial to millennial variability superimposed on the gradual increasing trend of OCAR 3 was inversely correlated with those of the sea surface temperature (SST) in the western tropical Pacific (WTP) and El Niño-Southern Oscillation (ENSO) activity, suggesting that C 3 plants have stronger sensitivity to regional climate change driven by oceanic forcing. Our data suggest that vegetation changes in a coastal area in East Asia were affected by monsoonal changes coupled with SST in WTP and ENSO activity. The vegetation change on Jeju Island varied quite differently from change in the westerly pathway, suggesting only a weak influence from high-latitude-driven atmospheric circulation changes. We conclude that centennial- to millennial-scale climate changes in coastal regions of East Asia during the mid- to late-Holocene may have been mainly controlled by low-latitudinal oceanic forcing, including forcing by SST and ENSO activity.

Geographic Variation in Advertisement Calls in a Tree Frog Species: Gene Flow and Selection Hypotheses

PubMed Central

Jang, Yikweon; Hahm, Eun Hye; Lee, Hyun-Jung; Park, Soyeon; Won, Yong-Jin; Choe, Jae C.

2011-01-01

Background In a species with a large distribution relative to its dispersal capacity, geographic variation in traits may be explained by gene flow, selection, or the combined effects of both. Studies of genetic diversity using neutral molecular markers show that patterns of isolation by distance (IBD) or barrier effect may be evident for geographic variation at the molecular level in amphibian species. However, selective factors such as habitat, predator, or interspecific interactions may be critical for geographic variation in sexual traits. We studied geographic variation in advertisement calls in the tree frog Hyla japonica to understand patterns of variation in these traits across Korea and provide clues about the underlying forces for variation. Methodology We recorded calls of H. japonica in three breeding seasons from 17 localities including localities in remote Jeju Island. Call characters analyzed were note repetition rate (NRR), note duration (ND), and dominant frequency (DF), along with snout-to-vent length. Results The findings of a barrier effect on DF and a longitudinal variation in NRR seemed to suggest that an open sea between the mainland and Jeju Island and mountain ranges dominated by the north-south Taebaek Mountains were related to geographic variation in call characters. Furthermore, there was a pattern of IBD in mitochondrial DNA sequences. However, no comparable pattern of IBD was found between geographic distance and call characters. We also failed to detect any effects of habitat or interspecific interaction on call characters. Conclusions Geographic variations in call characters as well as mitochondrial DNA sequences were largely stratified by geographic factors such as distance and barriers in Korean populations of H. japoinca. Although we did not detect effects of habitat or interspecific interaction, some other selective factors such as sexual selection might still be operating on call characters in conjunction with restricted gene flow. PMID:21858061

Seasonal variations of stable carbon isotopic composition of bulk aerosol carbon from Gosan site, Jeju Island in the East China Sea

NASA Astrophysics Data System (ADS)

Kundu, Shuvashish; Kawamura, Kimitaka

2014-09-01

This study explores the usefulness of stable isotopic composition (δ13C) along with other chemical tracers and air mass trajectory to identify the primary and secondary sources of carbonaceous aerosols. Aerosol samples (n = 84) were collected continuously from April 2003 to April 2004 at Gosan site in Jeju Island, South Korea. The concentrations of total carbon (TC), HCl fumed carbonate-free total carbon (fumed-TC) and their δ13C were measured online using elemental analyzer interfaced to isotope ratio mass spectrometer (EA-IRMS). Similar concentrations of TC and fumed-TC and their similar δ13C values suggest the insignificant contribution of inorganic carbon to Gosan aerosols. The monthly averaged δ13CTC showed the lowest in April/May (-24.2 to -24.4‰), which is related with the highest concentrations of oxalic acid (a secondary tracer). The result indicates an enhanced contribution of TC from secondary sources. The monthly averaged δ13CTC in July/August (-23.0 to -22.5‰) were similar to those in January/February (-23.1‰ to -22.7‰). However, chemical tracers and air mass transport pattern suggest that the pollution source regions in January/February are completely different from those in July/August. Higher δ13C values in July/August are aligned with higher concentration ratios of marine tracers (azelaic acid/TC and methanesulfonate/TC), suggesting an enhanced contribution of marine organic matter to the aerosol loading. Higher δ13C values in January/February are associated with higher concentrations of phthalic acid and K+/TC, indicating more contributions of carbonaceous aerosols from fossil fuel and C4-plant biomass combustion. This study demonstrates that δ13CTC, along with other chemical tracers and air mass trajectory, can be used as a tracer to understand the importance of primary versus secondary pollution sources of carbonaceous aerosols in the atmosphere.

Enhanced concentrations of citric acid in spring aerosols collected at the Gosan background site in East Asia

NASA Astrophysics Data System (ADS)

Jung, Jinsang; Kawamura, Kimitaka

2011-09-01

In order to investigate water-soluble dicarboxylic acids and related compounds in the aerosol samples under the Asian continent outflow, total suspended particle (TSP) samples ( n = 32) were collected at the Gosan site in Jeju Island over 2-5 days integration during 23 March-1 June 2007 and 16-24 April 2008. The samples were analyzed for water-soluble dicarboxylic acids, ketocarboxylic acids, and α-dicarbonyls using a capillary gas chromatography technique. We found elevated concentrations of atmospheric citric acid (range: 20-320 ng m -3) in the TSP samples during mid- to late April of 2007 and 2008. To specify the sources of citric acid, dicarboxylic acids and related compounds were measured in the pollen sample collected at the Gosan site (Pollen_Gosan), authentic pollen samples from Japanese cedar ( Cryptomeria) (Pollen_cedar) and Japanese cypress ( Chamaecyparis obtusa) (Pollen_cypress), and tangerine fruit produced from Jeju Island. Citric acid (2790 ng in unit mg of pollen mass) was found as most abundant species in the Pollen_Gosan, followed by oxalic acid (2390 ng mg -1). Although citric acid was not detected in the Pollen_cedar and Pollen_cypress as major species, it was found as a dominant species in the tangerine juice while malic acid was detected as major species in the tangerine peel, followed by oxalic and citric acids. Since Japanese cedar trees are planted around tangerine farms to prevent strong winds from the Pacific Ocean, citric acid that may be directly emitted from tangerine is likely adsorbed on pollens emitted from Japanese cedar and then transported to the Gosan site. Much lower malic/citric acid ratios obtained under cloudy condition than clear condition suggest that malic acid may rapidly decompose to lower molecular weight compounds such as oxalic and malonic acids (

Living with marginal coral communities: Diversity and host-specificity in coral-associated barnacles in the northern coral distribution limit of the East China Sea.

PubMed

Chan, Benny K K; Xu, Guang; Kim, Hyun Kyong; Park, Jin-Ho; Kim, Won

2018-01-01

Corals and their associated fauna are extremely diverse in tropical waters and form major reefs. In the high-latitude temperate zone, corals living near their distribution limit are considered marginal communities because they are particularly extremely sensitive to environmental and climatic changes. In this study, we examined the diversity and host usage of coral-associated barnacles on Jeju Island, Korea, the northern coral distribution limit in the East China Sea. In this study, only three coral-associated barnacles-from two genera in two subfamilies-were collected. The Pyrgomatinid barnacles Cantellius arcuatus and Cantellius cf. euspinulosum were found only on the corals Montipora millepora and Alveopora japonica, respectively. The Megatrematinid barnacle Pyrgomina oulastreae, relatively a generalist, was found on Psammocora spp. (both profundacella and albopicta) and Oulastrea crispata corals. The host usage of these three barnacles does not overlap. DNA barcode sequences of the C. arcuatus specimens collected in the present study matched those collected in Kochi in Japan, Taiwan, Malaysia and Papua New Guinea, suggesting that this species has a wide geographical distribution. C. arcuatus covers a wider host range in Taiwan waters, inhabiting Montipora spp. and Porites spp., which suggests that the host specificity of coral-associated barnacles varies with host availability. C. cf. euspinulosum probably has a very narrow distribution and host usage. The sequences of C. cf. euspinulosum on Jeju Island do not match those of any known sequences of Cantellius barnacles in the Indo-Pacific region. P. oulastreae probably prefers cold water because it has been reported in temperate regions. Coral-associated barnacles in marginal communities have considerably lower diversity than their subtropical and tropical counterparts. When host availability is limited, marginal coral-associated barnacles exhibit higher host specificity than those in subtropical and tropical reef systems.

Living on the edge: demographic and phylogeographical patterns in the woodlouse-hunter spider Dysdera lancerotensis Simon, 1907 on the eastern volcanic ridge of the Canary Islands.

PubMed

Bidegaray-Batista, Leticia; Macías-Hernández, Nuria; Oromí, Pedro; Arnedo, Miquel A

2007-08-01

The Eastern Canary Islands are the emerged tips of a continuous volcanic ridge running parallel to the northeastern African coast, originated by episodic volcanic eruptions that can be traced back to the Miocene and that, following a major period of quiescence and erosion, continued from the Pliocene to the present day. The islands have been periodically connected by eustatic sea-level changes resulting from Pleistocene glacial cycles. The ground-dwelling spider Dysdera lancerotensis Simon, 1907 occurs along the entire ridge, except on recent barren lavas and sand dunes, and is therefore an ideal model for studying the effect of episodic geological processes on terrestrial organisms. Nested clade and population genetic analyses using 39 haplotypes from 605 base pairs of mitochondrial DNA cytochrome c oxidase I sequence data, along with phylogenetic analyses including two additional mitochondrial genes, uncover complex phylogeographical and demographic patterns. Our results indicate that D. lancerotensis colonized the ridge from north to south, in contrast to what had been expected given the SSW-NNE trend of volcanism and to what had been reported for other terrestrial arthropods. The occurrence of several episodes of extinction, recolonization and expansion are hypothesized for this species, and areas that act as refugia during volcanic cycles are identified. Relaxed molecular clock methods reveal divergence times between main haplotype lineages that suggest an older origin of the northern islets than anticipated based on geological evidence. This study supports the key role of volcanism in shaping the distribution of terrestrial organisms on oceanic islands and generates phylogeographical predictions that warrant further research into other terrestrial endemisms of this fascinating region.

Bioactive compounds in bee propolis for drug discovery

NASA Astrophysics Data System (ADS)

Kumazawa, Shigenori

2018-02-01

Propolis is a natural resinous product collected by honeybees. It has been used in folk medicine since ancient times because of its numerous biological properties such as antioxidant, antimicrobial, anti-cancer, and anti-inflammatory activities. Studies of the chemical composition of propolis have demonstrated that its compositional variability depends on the source plant. We have studied the chemistry and biological activities of various types of propolis from Apis mellifera. The studies of propolis collected in Brazil, Japan, Korea, the Solomon Island and Senegal are summarized. Brazilian green propolis contained high levels of artepillin C (3,5-diprenyl-4-hydroxycinnamic acid), which has a potent apoptosis-inducing agent as well as an angiogenesis inhibitor. The several phenolic compounds with potent antibacterial activity in Brazilian red propolis were found. The propolis from Okinawa, Japan, contained some prenylflavonoids with antioxidant and antimicrobial activities. The propolis from the Solomon Islands and Hawaii have the same compounds as Okinawan propolis. The propolis from Jeju Island, Korea had the promotion effect on nerve growth factor (NGF) secretion in human glioblastoma T98G cells. The compounds isolated from Senegalese propolis showed high anti-inflammatory activity due to their inhibition of the liposaccharide (LPS)-induced expression of inducible NO synthase (iNOS).

Radiocarbon ages of lacustrine deposits in volcanic sequences of the Lomas Coloradas area, Socorro Island, Mexico

NASA Technical Reports Server (NTRS)

Farmer, J. D.; Farmer, M. C.; Berger, R.

1993-01-01

Extensive eruptions of alkalic basalt from low-elevation fissures and vents on the southern flank of the dormant volcano, Cerro Evermann, accompanied the most recent phase of volcanic activity on Socorro Island, and created the Lomas Coloradas, a broad, gently sloping terrain comprising the southern part of the island. We obtained 14C ages of 4690 +/- 270 BP (5000-5700 cal BP) and 5040 +/- 460 BP (5300-6300 cal BP) from lacustrine deposits that occur within volcanic sequences of the lower Lomas Coloradas. Apparently, the sediments accumulated within a topographic depression between two scoria cones shortly after they formed. The lacrustine environment was destroyed when the cones were breached by headward erosion of adjacent stream drainages. This was followed by the eruption of a thin basaltic flow from fissures near the base of the northernmost cone. The flow moved downslope for a short distance and into the drainages that presently bound the study area on the east and west. The flow postdates development of the present drainage system and may be very recent. Our 14C data, along with historical accounts of volcanic activity over the last century, including submarine eruptions that occurred a few km west of Socorro in early 1993, underscore the high risk for explosive volcanism in this region and the need for a detailed volcanic hazards plan and seismic monitoring.

Camera formation and more, but what comes next? an analysis of volcanic threat of Nisyros island, Greece

NASA Astrophysics Data System (ADS)

Winson, A.; Kinvig, H.; Gottsmann, J.; Partington, E.; Geyer, A.

2008-10-01

We present an analysis of volcanic threat of Nisyros island (Greece) based on a catalogue of questions compiled for the USGS National Volcano Early Warning System (NVEWS). We find that the score puts Nisyros in the league of volcanoes posing a very high threat. US volcanoes with a comparable threat level include Mt. St. Helens, Augustine and the Long Valley caldera.

Microsatellite analysis of genetic divergence among populations of giant Galápagos tortoises.

PubMed

Ciofi, Claudio; Milinkovitch, Michel C; Gibbs, James P; Caccone, Adalgisa; Powell, Jeffrey R

2002-11-01

Giant Galápagos tortoises represent an interesting model for the study of patterns of genetic divergence and adaptive differentiation related to island colonization events. Recent mitochondrial DNA work elucidated the evolutionary history of the species and helped to clarify aspects of nomenclature. We used 10 microsatellite loci to assess levels of genetic divergence among and within island populations. In particular, we described the genetic structure of tortoises on the island of Isabela, where discrimination of different taxa is still subject of debate. Individual island populations were all genetically distinct. The island of Santa Cruz harboured two distinct populations. On Isabela, populations of Volcan Wolf, Darwin and Alcedo were significantly different from each other. On the other hand, Volcan Wolf showed allelic similarity with the island of Santiago. On Southern Isabela, lower genetic divergence was found between Northeast Sierra Negra and Volcan Alcedo, while patterns of gene flow were recorded among tortoises of Cerro Azul and Southeast Sierra Negra. These tortoises have endured heavy exploitation during the last three centuries and recently attracted much concern due to the current number of stochastic and deterministic threats to extant populations. Our study complements previous investigation based on mtDNA diversity and provides further information that may help devising tortoise management plans.

Spatial and temporal variations of diffuse CO_{2} degassing at the N-S volcanic rift-zone of Tenerife (Canary Islands, Spain) during 2002-2015 period

NASA Astrophysics Data System (ADS)

Alonso, Mar; Ingman, Dylan; Alexander, Scott; Barrancos, José; Rodríguez, Fátima; Melián, Gladys; Pérez, Nemesio M.

2016-04-01

Tenerife is the largest of the Canary Islands and, together with Gran Canaria Island, is the only one with a central volcanic complex that started to grow at about 3.5 Ma. Nowadays the central complex is formed by Las Cañadas caldera, a volcanic depression measuring 16×9 km that resulted from multiple vertical collapses and was partially filled by post-caldera volcanic products. Up to 297 mafic monogenetic cones have been recognized on Tenerife, and they represent the most common eruptive activity occurring on the island during the last 1 Ma (Dóniz et al., 2008). Most of the monogenetic cones are aligned following a triple junction-shaped rift system, as result of inflation produced by the concentration of emission vents and dykes in bands at 120o to one another as a result of minimum stress fracturing of the crust by a mantle upwelling. The main structural characteristic of the southern volcanic rift (N-S) of the island is an apparent absence of a distinct ridge, and a fan shaped distribution of monogenetic cones. Four main volcanic successions in the southern volcanic rift zone of Tenerife, temporally separated by longer periods (˜70 - 250 ka) without volcanic activity, have been identified (Kröchert and Buchner, 2008). Since there are currently no visible gas emissions at the N-S rift, diffuse degassing surveys have become an important geochemical tool for the surveillance of this volcanic system. We report here the last results of diffuse CO2 efflux survey at the N-S rift of Tenerife, performed using the accumulation chamber method in the summer period of 2015. The objectives of the surveys were: (i) to constrain the total CO2 output from the studied area and (ii) to evaluate occasional CO2 efflux surveys as a volcanic surveillance tool for the N-S rift of Tenerife. Soil CO2 efflux values ranged from non-detectable up to 31.7 g m-2 d-1. A spatial distribution map, constructed following the sequential Gaussian simulation (sGs) procedure, did not show an apparent relation between higher diffuse CO2 emission values and the main N-S axis of the rift. The total CO2 output released to the atmosphere in a diffuse way has been estimated at 707 t d-1, which represents a value three times higher than the average of the three studies conducted previously. This observed increase suggests the occurrence of an episodic enhanced magmatic (endogenous) contribution. This also confirms the need of periodic diffuse emission surveys in the area as a powerful volcanic surveillance tool, mainly in volcanic systems where visible gas emanations are absent. References: Dóniz et al., 2008. J. Volcanol. Geotherm. Res. 173, 185. Kröchert and Buchner, 2008. Geol. Mag. 146, 161.

Space Radar Image of Reunion Island

NASA Image and Video Library

1999-04-15

This radar image shows the volcanic island of Reunion, about 700 km 434 miles east of Madagascar in the southwest Indian Ocean. The southern half of the island is dominated by the active volcano, Piton de la Fournaise.

Satellite Observations of New Volcanic Island in Tonga

NASA Astrophysics Data System (ADS)

Vaughan, R. Greg; Abrams, Michael J.; Hook, Simon J.; Pieri, David C.

2007-01-01

A rising volcanic plume from an unknown source was observed on 9-11 August 2006 in the Vava'u Island group in the northernmost islands of Tonga [Matangi News Online, 2006]. On 12 August, the crew on board the yacht Maiken, sailing west from Vava'u to Fiji, encountered ``a vast, many miles wide, belt of densely packed pumice'' floating on the water (F. Fransson personal communication, 2006). Later, the crew sailed south and discovered that the source of the pumice was a newly erupting submarine volcano near Home Reef (18.991°S, 174.767°W) (Figure 1a).

Satellite Observations of New Volcanic Island in Tonga

NASA Technical Reports Server (NTRS)

Vaughan, R. Greg; Abrams, Michael J.; Hook, Simon J.; Pieri, David C.

2007-01-01

A rising volcanic plume from an unknown source was observed on 9-11 August 2006 in the Vava'u Island group in the northernmost islands of Tonga [Matangi News Online, 2006]. On 12 August, the crew on board the yacht Maiken, sailing west from Vava'u to Fiji, encountered 'a vast, many miles wide, belt of densely packed pumice' floating on the water (F. Fransson personal communication, 2006). Later, the crew sailed south and discovered that the source of the pumice was a newly erupting submarine volcano near Home Reef (18.991 deg S, 174.767 deg W).

Perspective View of Shaded Relief with Color as Height, Miyake-Jima, Japan

NASA Image and Video Library

2000-08-10

This 3D perspective view shows the Japanese island called Miyake-Jima viewed from the northeast. This island - about 180 kilometers south of Tokyo - is part of the Izu chain of volcanic islands that runs south from the main Japanese island of Honshu.

Earth Observations taken by the Expedition 17 Crew

NASA Image and Video Library

2008-04-20

ISS017-E-005037 (19 April 2008) --- Santorini Volcano, Greece is featured in this image photographed by an Expedition 17 crewmember on the International Space Station. According to scientists, one of the largest volcanic eruptions in the past 10,000 years occurred approximately 1620 BC on the volcanic island of Santorini in the Aegean Sea. This view illustrates the center of Santorini Volcano, located approximately 118 kilometers to the north of Crete (not shown). Prior to 1620 BC, the island of Santorini -- now known as Thera -- had been built up by layers of lava created by overlapping shield volcanoes, and had experienced three significant eruptions that formed overlapping calderas, or collapsed magma chambers. Around 1620 BC, the fourth (and latest) major eruption created the present-day islands and caldera bay of Santorini Volcano. The caldera rim is clearly visible in this image as a steep cliff forming the western shoreline of the island of Thera. Following the 1620 BC eruption, much of the previous island of Santorini was destroyed or submerged. The white rooftops of cities and towns trace the caldera rim on the island of Thera, and overlook the young central islands of Nea Kameni and Palaea Kameni -- both, according to scientists, formed from lava domes and flows that started erupting approximately 1400 years after the last major caldera-forming event. Several of these flows are visible in the image as brown to dark-brown irregular masses forming Nea Kameni (left). The most recent volcanic activity in the Kameni islands occurred in 1950, and included some small explosions and production of lava. The extent of development and location of an airport (upper right) on Thera illustrate the popularity of Santorini Volcano as a tourist destination. Today, volcanic activity is closely monitored by the Institute for the Study and Monitoring of the Santorini Volcano, or ISMOSAV.

Paleomagnetic Study of Azores Archipelago: Volcano-Tectonic Implications

NASA Astrophysics Data System (ADS)

Silva, P. F.; Henry, B.; Marques, F. O.; Madureira, P.; Miranda, J. M. A.; Lourenco, N. V.; Madeira, J.; Hildenbrand, A.; Nunes, J. C.; Roxerová, Z.

2014-12-01

Oceanic islands are by nature unstable volcanic buildings generally marked by rapid growth that alternates with destruction due to a variety of mass-wasting processes, including giant sector collapses, vertical caldera subsidence, fault generation/propagation, shallow landslides and coastal erosion. Due to its diverse volcanic and tectonic frameworks, the Azores archipelago represents an excellent case study for geophysical and geological proposes. Main results of a paleomagnetic study, conducted on oriented samples from approximately 60 accessible lava piles of three islands of Azores archipelago central group (Faial, Pico and Terceira islands) and covering as much as possible spatially and temporally these islands are: i) The paleomagnetic polarity is in close agreement with the radiometric results known for these islands; ii) Onshore volcanic activity began during the Matuyama geochron for Faial and during Brunhes for Terceira and Pico; iii) The mean ChRMs from Terceira and Pico islands result in a paleomagnetic pole similar to the ones retrieved from the studies of Johnson et al (1998) and Silva et al (2012), from S. Miguel and S. Jorge islands (other islands of Azores archipelago), respectively; iv) ChRMs from Faial show an elliptical distribution perpendicular to the WNW-ESE grabben that is the major structure of the island, suggesting tilting towards SSW of the southern wall and towards NNE of the northern one. The presence of listric faults plunging towards the middle of the grabben and aligned along the N110º azimuth could explain the elliptical distribution of paleomagnetic directions. This study is a contribution for the research project REGENA (PTDC/GEO-FIQ/3648/2012). References Johnson, C.L., Wijbrans, J.R., Constable, C.G., Gee, J., Staudigel, H., Tauxe, L., Forjaz, V.-H., Salgueiro, M., 1998. 40Ar/39Ar ages and paleomagnetism of S. Miguel lavas,Azores, Earth planet. Sci. Lett., 160, 637-649. Silva, PF; Henry, B; Marques, FO; Hildenbrand, A., Madureira, P., Mériaux, C; Kratinová, Z. Palaeomagnetic study of a sub-aerial volcanic ridge (São Jorge Island, Azores) for the past 1.3 Myr: evidence for the Cobb Mountain Subchron, volcano flank instability and tectono-magmatic implications. Geophysical Journal International, 188, 3, 959-978, 2012

Earth observations of the Canary Islands taken from OV-105 during STS-99

NASA Image and Video Library

2000-03-27

STS099-720-014 (11-22 February 2000) ---One of the STS-99 astronauts aboard the Space Shuttle Endeavour recorded this 70mm image of Tenerife Island, the largest in the Canary Island archipelago. Tenerife is approximately 50 miles (80 kilometers) long and 32 miles (54 kilometers) at its widest point. With Pico de Teide, its volcanic peak, rising 12,198 feet (3,718 meters) above the sea, Tenerife has the distinction of having the highest elevation in the Atlantic Ocean. This near-vertical photograph of the entire island, except for the northeastern tip, showcases the prominent caldera, which measures approximately 10 miles (16 kilometers) by 7 miles (11 kilometers). Within the large caldera, young volcanic cones and small craters rise from the older volcano that was probably destroyed by a gigantic explosion millions of years ago. The classic radial erosion drainage pattern is obvious around the old volcanic cone. Scientist say that the island, with its precipitous coastline, has a mild and pleasant climate. However, meteorologists report that it is subject to severe drought and occasional tornadoes. The fertile soils produce a variety of crops—date palms, grapes, fruits, sugarcane, grains, and cotton.

Diffuse degassing He/CO2 ratio before and during the 2011-12 El Hierro submarine eruption, Canary Islands

NASA Astrophysics Data System (ADS)

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

2015-04-01

El Hierro Island (278 km2) is the youngest and the SW-most of the Canary Islands. On July 16, 2011, a seismic-volcanic crisis started with the occurrence of more than 11,900 seismic events and significant deformation along the island, culminating with the eruption onset in October 12. Since at El Hierro Islands there are not any surface geothermal manifestation (fumaroles, etc), we have focused our studies on soil degassing surveys. Between July 2011 to March 2012, seventeen diffuse CO2 and He emissions soil gas surveys were undertaken at El Hierro volcanic system (600 observation sites) with the aim to investigate the relationship between their temporal variations and the volcanic activity (Padrón et al., 2013; Melián et al., 2014). Based on the diffuse He/CO2 emission ratio, a sharp increase before the eruption onset was observed, reaching the maximum value on September 26 (6.8×10-5), sixteen days before the occurrence of the eruption. This increase coincided with an increase in seismic energy release during the volcanic unrest and occurred together with an increase on the 3He/4He isotopic ratio in groundwaters from a well in El Hierro Island (Padrón et al., 2013; from 2-3 RA to 7.2 RA where RA = 3He/4He ratio in air), one month prior to the eruption onset. Early degassing of new gas-rich magma batch at depth could explain the observed increase on the He/CO2 ratio, causing a preferential partitioning of CO2 in the gas phase with respect to the He, due to the lower solubility of CO2 than that of He in basaltic magmas. During the eruptive period (October 2011-March 2012) the prevalence of a magmatic CO2-dominated component is evident, as indicated by the generally lower He/CO2 ratios and high 3He/4He values (Padrón et al., 2013). The onset of the submarine eruption might have produced a sudden release of volcanic gases, and consequently, a decrease in the volcanic gas pressure of the magma bodies moving beneath the island, reflected by a drastic decrease in the diffuse helium emissions measured after the eruption onset. Therefore, this study shows that higher diffuse He/CO2 emission ratios preceded the 2011-2012 El Hierro submarine eruption, clearly show the critical role that both gas species can play in the prediction of major volcanic events and demonstrates the importance of performing soil He and CO2 surveys as a useful geochemical monitoring tool in active volcanic regions. Padrón et al. (2013) Geology 41(5), 539-542; Melián et al. (2014) JGR, 119: 6976-6991, doi:10.1002/2014JB011013

Volcanic gases create air pollution on the Island of Hawai’i

USGS Publications Warehouse

Sutton, J.; Elias, T.

1993-01-01

The current eruption of Kilauea produces large quantities of volcanic gases that contribute to "volcanic air pollution." In this article we discuss the nature of the gases released from Kilauea, hoe we study them, and what happened to the gases in the environment after they are released. 

Isabela, Galapagos Islands as seen from STS-59

NASA Technical Reports Server (NTRS)

1994-01-01

Space Radar Laboratory (SRL) scientists will use these photographs of Isabela in the Galapagos island chain, with the radar iamagery, to discriminate among different ages of basalt flows, and different ecosystems of shrub communities, on these equatorial volcanic islands.

An active seismic experiment at Tenerife Island (Canary Island, Spain): Imaging an active volcano edifice

NASA Astrophysics Data System (ADS)

Garcia-Yeguas, A.; Ibañez, J. M.; Rietbrock, A.; Tom-Teidevs, G.

2008-12-01

An active seismic experiment to study the internal structure of Teide Volcano was carried out on Tenerife, a volcanic island in Spain's Canary Islands. The main objective of the TOM-TEIDEVS experiment is to obtain a 3-dimensional structural image of Teide Volcano using seismic tomography and seismic reflection/refraction imaging techniques. At present, knowledge of the deeper structure of Teide and Tenerife is very limited, with proposed structural models mainly based on sparse geophysical and geological data. This multinational experiment which involves institutes from Spain, Italy, the United Kingdom, Ireland, and Mexico will generate a unique high resolution structural image of the active volcano edifice and will further our understanding of volcanic processes.

Composition of island arcs and continental growth.

NASA Technical Reports Server (NTRS)

Jakes, P.; White, A. J. R.

1971-01-01

Island arc volcanism has contributed and is still contributing to continental growth, but the composition of island arcs differs from that of the upper continental crust in its lower abundance of Si, K, Rb, Ba, Sr and light rare earth elements. In their advanced stage of evolution, island arcs contain more than 80% of tholeiitic and 15% of ?island arc' calc-alkaline rocks with varied SiO2 contents. The larger proportion of tholeiitic rocks is in the lower crustal levels. The high stratigraphical levels of the island arcs are composed of tholeiitic plus calc-alkaline and/or high potash (shoshonitic) associations with higher abundances of K, Rb, Sr, and Ba. Stratification of the island arc crust is accentuated by another type of calc-alkaline volcanism (Andean type) originating at a late stage of arc evolution, probably by partial melting at the base of the crust. This causes enrichment of the upper crust in K, Rb, Ba and REE and accounts for upper crustal abundances of these elements as well as of SiO2.

The effect of giant flank collapses on magma pathways and location of volcanic vents

NASA Astrophysics Data System (ADS)

Maccaferri, Francesco; Richter, Nicole; Walter, Thomas

2017-04-01

Flank collapses have been identified at tall volcanoes and ocean islands worldwide. They are recurrent processes, significantly contributing to the morphological and structural evolution of volcanic edifices, and they often occur in interaction with magmatic activity. Moreover, it has been observed that the intrusion pathways and eruption's sites often differ before and after flank collapses. While it is understood that dyke intrusions might destabilise a volcano flank, and a moving flank might create the space needed for further intrusions, the effect of collapses on the magma pathways has been rarely addressed. Here we use a boundary element model for dyke propagation to study the effect of the stress redistribution due to a flank collapse on the location of eruptive vents. We use our model to simulate the path of magmatic intrusion after the collapse of the eastern flank of Fogo Volcano, Cabe Verde. We find that the competition between loading stress due to the volcanic edifice and unloading due to the collapse of a flank favours magmatic activity to cluster within the collapse scar, displaced with respect to the pre-collapse volcanic centre. Our results are compared with geomorphological observations at Fogo Island and are discussed in the general context of the long-term evolution intraplate volcanic ocean islands worldwide.

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

NASA Astrophysics Data System (ADS)

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

2010-05-01

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.

Earth Observations taken by the Expedition 18 Crew

NASA Image and Video Library

2009-01-27

ISS018-E-024351 (27 Jan. 2009) --- Tetiaroa Island in French Polynesia is featured in this image photographed by an Expedition 18 crewmember on the International Space Station. This island, part of the Society Islands archipelago in the southern Pacific Ocean, is also known as ?Marlon Brando?s Island?. The late film star purchased the island ? more correctly, an atoll comprised of thirteen small islets (or motus) from the French Polynesian government for a total of 70,000 over 1966-1967. While the motus were his property, the government retained the rights to the coral reefs and lagoons to preserve control of marine resources. Following Brando?s death in 2004, ownership of the approximately 8 kilometers?wide atoll passed into other private hands, and there are now plans to build a luxury resort amongst the islets. This view illustrates the typical circular appearance of a fully-developed atoll. The ring of islands ? covered in green vegetation and white to tan sandy beaches ? develops on coral reefs, which originally form around a volcanic island. As the volcanic island gradually disappears due to subsidence and erosion, the coral reefs continue to grow upwards. Over time, the central volcanic island is completely submerged, leaving a ring of coral reefs and islands that surround a lagoon. The shallow lagoon waters appear blue-green in this image, and contrast with darker ? and deeper ? Pacific Ocean waters surrounding the atoll. One of the motus in the southern portion of the atoll, Tahuna Rahi, is a protected bird sanctuary, and is the nesting site of red- and brown-footed boobies, frigatebirds, and terns (among other species). Access to the atoll is via boat, as the airstrip was closed in 2004 due to safety and security concerns.

The complex emplacement dynamics and tsunami genesis of the 1888 Ritter Island sector collapse from 3D seismic data

NASA Astrophysics Data System (ADS)

Urlaub, M.; Karstens, J.; Berndt, C.; Watt, S. F.; Micallef, A.; Klaucke, I.; Klaeschen, D.; Brune, S.; Kühn, M.

2017-12-01

On March 13 1888, a large sector of the subaerial and submarine edifice of Ritter Island (Papua New Guinea) collapsed and slid into the Bismarck Sea, triggering a tsunami with run-up heights of more than 25 m on the neighboring islands. The tsunami traveled for more than 600 km and caused destruction in several settlements. German colonists described in detail the timing of the arriving waves. During research cruise SO252 onboard RV Sonne, we collected a comprehensive set of multibeam and sediment echosounder data, seafloor video footage, rock samples, 2D seismic profiles, and a 60 km2 high-resolution Pcable 3D seismic cube. This dataset, combined with the historic eyewitness accounts, allows detailed reconstruction of the large-scale volcanic sector collapse and the associated tsunami genesis. The 3D seismic cube reveals a change of emplacement dynamics during the collapse of the volcanic edifice. The initial failure occurred along a deep slide plane extending from the volcanic cone up to 300 m deep into the seafloor sediments adjacent to the volcanic edifice. Movement of large, intact sediment blocks and shortening characterize this deep-rooted mass-movement. In contrast to the well-preserved mobilization structures in the deep part of the volcanic edifice related to the initial phase of mass movement, there are hardly any deposits of the upper part of the volcanic cone comprising of well-stratified volcaniclastic layers. The 2 km3 cone was mobilized in the final stage of the sector collapse and its highly energetic slide mass eroded deeply into the previously emplaced slide deposits. The fast moving mass was channelized between two volcanic ridges, transported into the basin west of Sakar Island, and then deposited more than 30 km away from its source. We interpret the separation into two phases as the result of decoupling of the sliding mass of the cone from the deeper volcanic edifice. This process may be explained by gravitational acceleration of the sliding mass or a phreatomagmatic explosion due to the contact of the magmatic conduit with seawater.

Canary Islands

NASA Technical Reports Server (NTRS)

1992-01-01

This easterly looking view shows the seven major volcanic islands of the Canary Island chain (28.0N, 16.5W) and offers a unique view of the islands that have become a frequent vacation spot for Europeans. The northwest coastline of Africa, (Morocco and Western Sahara), is visible in the background. Frequently, these islands create an impact on local weather (cloud formations) and ocean currents (island wakes) as seen in this photo.

Structural, Geochemical, and Isotopic Studies on Magmatic Dyke Swarms of the South Shetland Islands Volcanic Arc, West Antarctica - Revealing the Geodynamic History

NASA Astrophysics Data System (ADS)

Kraus, S.; Miller, H.

2003-12-01

Between 2000 and 2002 areas of up to 100,000 m2 have been mapped at several locations of the South Shetland Islands, mainly on King George and Livingston Islands. A structural analysis of the dykes and the host rocks was undertaken, and about 250 dykes were sampled for geochemical studies. On Livingston Island six different strike directions were identified, yielding a reliable relative time sequence as deduced from field-relationships. Geochemically, these dykes can be separated into five different groups, correlating with the different strike directions, one of those groups comprising two directions. Analysis of the structural data shows, that at least on Livingston Island only minor changes of the tensional situation occurred. Geochemical data reveal that all dykes of the South Shetland Islands belong to a calc-alkaline, arc-related suite, ranging from primitive basalts to highly differentiated rhyolites. Interpretation of Sr isotopic data of the dykes proves difficult, as there are indications for sea-water induced Sr-alteration. Nd isotopic analysis yield better results, revealing a three-stage development from the oldest dykes (ɛ Nd -0.2 to 0.6) on Livingston Island towards a second, younger group (ɛ Nd 2.8 to 4.2, also Livingston), terminating with a third one (ɛ Nd 5.2 to 7.6), which includes the youngest dykes on Livingston and all dykes on King George and also Penguin Island. Either two mantle sources were involved, or the amount of crustal contamination changed considerately with time. It may have been high during initial arc volcanism, because of a still unstretched crust, then decreasing continually with progressing volcanism. In any case, the pattern reflects a chronological sequence corresponding with other authors' hypothesis of a migrating arc volcanism from SW to NE, i.e. from Livingston (older dykes) towards King George Island (younger dykes). Pb isotopic data, plottet together with MORB- and sediment-samples dredged from the Drake Passage, indicate a three-component mixture of the arc magma. Mixing of MORB- and sediment-sources alone cannot explain the observed pattern. An additional source, maybe the crust underlying the South Shetland block, was involved.

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

NASA Astrophysics Data System (ADS)

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

2012-04-01

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

Eighteen years of geochemical monitoring at the oceanic active volcanic island of El Hierro (Canary Islands, Spain)

NASA Astrophysics Data System (ADS)

Asensio-Ramos, María; Alonso, Mar; Sharp, Emerson; Woods, Hannah; Barrancos, José; Pérez, Nemesio M.

2016-04-01

We report herein the latest results of a diffuse CO2 efflux survey at El Hierro volcanic system carried out during the summer period of 2015 to constrain the total CO2 output from the studied area a during post-eruptive period. El Hierro Island (278 km2) is the youngest and the SW-most of the Canary Islands. On July 16, 2011, a seismic-volcanic crisis started with the occurrence of more than 11,900 seismic events and significant deformation along the island. On October 10, 2011, the dominant character of seismicity changed dramatically from discrete earthquakes to continuous tremor, a clear indication that magma was rapidly approaching the surface immediately before the onset of the eruption, October 12. Eruption was declared over on 5 March, 2012. In order to monitor the volcanic activity of El Hierro Island, from 1998 to 2015 diffuse CO2 emission studies have been performed at El Hierro volcanic system in a yearly basis (˜600 observation sites) according to the accumulation chamber method. Spatial distribution maps were constructed following the sequential Gaussian simulation (sGs) procedure. To quantify the total CO2 emission from the studied area, 100 simulations for each survey have been performed. During the eruption period, soil CO2 efflux values range from non-detectable (˜0.5 g m-2 d-1) up to 457 g m-2 d-1, reaching in November 27, 2011, the maximum CO2 output estimated value of all time series, 2,398 t d-1, just before the episodes of maximum degassing observed as vigorous bubbling at the sea surface and an increment in the amplitude of the tremor signal. During the 2015 survey, soil CO2 efflux values ranged from non-detectable up to 41 g m-2 d-1. The spatial distribution of diffuse CO2 emission values seemed to be controlled by the main volcano structural features of the island. The total diffuse CO2 output released to atmosphere was estimated at 575 ± 24 t d-1, value slightly higher that the background CO2 emission estimated at 422 t d-1 (Melián et al., 2014). The above data demonstrate that discrete surveys of diffuse CO2 emission provide important information to optimize the early warning system in volcano monitoring programs and to monitor the evolution of an ongoing volcanic eruption, even though it is a submarine eruption. References: Melián et al., 2014. J. Geophys. Res. DOI: 10.1002/2014JB011013.

Chronology of volcanic events in the eastern Philippine Sea

NASA Astrophysics Data System (ADS)

Meijer, Arend; Reagan, Mark; Ellis, Howard; Shafiqullah, Muhammad; Sutter, John; Damon, Paul; Kling, Stanley

Radiometric and paleontologic ages of samples from chiefly volcanic sections exposed on Guam, Saipan, and in the Palau Islands were determined to provide an improved temporal framework for tectonic and petrologic models for the evolution of the eastern Philippine Sea. The oldest arc related volcanic rocks found in this area are from the Facpi formation on Guam dated at 43.8±1.6 m.y. B.P. (late middle Eocene). Evidence for late Eocene, early Oligocene, and middle Miocene arc volcanism was also found in the Mariana fore arc. The Palau Islands contain volcanic units of late Eocene(?), early Oligocene and early Miocene age. A minimum age of 1.3±0.2 m.y. has been established for the Mariana active arc. Overall, the new data are consistent with Karig's (1971) model for the tectonic evolution of the eastern Philippine Sea. Whether or not arc volcanism and interarc basin spreading can take place at the same time has not been resolved, although no evidence of synchroneity has been found for at least the Parece Vela Basin—South Honshu Ridge arc system.

Geology and geochemistry of epithermal precious metal vein systems in the intra-oceanic arcs of Palau and Yap, western Pacific

USGS Publications Warehouse

Rytuba, J.J.; Miller, W.R.

1990-01-01

The Palau and Yap arcs are part of an intra-oceanic island-arc-trench system which separates the Pacific and Philippine plates in the western Pacific Ocean. The 350-km-long Palau arc consists of over 200 islands while the 400-km-long Yap arc located to the north has only four major islands exposed. Four of the largest islands in Palau are composed primarily of early Eocene to mid-Miocene volcanic rocks and the four islands comprising Yap contain only Miocene volcanic rocks. Basalt and basaltic andesites of the Babelthuap Formation are the oldest volcanic rocks in Palau and are characterized by high MgO, Ni and Cr and low TiO2 and have a boninitic affinity. They form the central and southeastern parts of Babelthuap Island. Oligocene arc tholeiite flows having an age of 34-35.5 Ma comprise most of the three smaller volcanic islands in Palau and the western part of Babelthuap. The youngest volcanic rocks are dacitic intrusions having an age of 22.7-23.2 Ma. The Yap arc is unusual in that metamorphic rocks up to amphibolite grade form most of the islands. These are underlain by a melange composed of igneous and volcanic clasts as well as clasts from a dismembered copper-gold skarn deposit. Miocene volcanic rocks consisting of flows and volcaniclastic deposits overlie the melange and metamorphic complex. An epithermal precious-metal vein system hosted by flows and flow breccias of the Babelthuap Formation occurs in an area 1.5 km by 1 km on the southeast side of Babelthuap Island. Over 50 veins and mineralized breccias ranging up to 2 m in width and having a strike length up to 500 m contain from trace to 13.0 ppm gold. The veins consist of quartz with varying amounts of sulfides and iron oxides after sulfides and the mineralized breccias consist of brecciated country rock cemented by quartz and iron oxides after sulfides. The veins and mineralized breccias generally dip within 15?? of vertical and have two preferred orientations, north-northwest and north-northeast. Hydrothermal alteration of the host rocks consists of a widespread weak to moderately strong propylitic alteration and a more restricted sericitic alteration adjacent to the veins and shear zones. Sulfide minerals in the veins consist primarily of pyrite accompanied by lesser amounts of sphalerite, chalcopyrite, galena, acanthite, native silver, cerargyrite, and iodyrite in partly oxidized parts of the vein system. Gold is typically fine-grained, 1-20 microns, and occurs as native gold, electrum and gold-silver-telluride. Elements correlated with high gold concentrations include molybdenum, tellurium, bismuth, lead, silver, copper, zinc and arsenic. In Yap a similar vein system to that present in Palau is hosted by the Miocene Tomil Volcanics on the islands of Maap and Gagil Tamil. The quartz veins and quartz-cemented breccias contain up to 3.7 ppm gold and trace elements associated with the gold include tellurium, copper, silver and vanadium. Within the mineralized area an unusually iron-rich (3-20%), 4-m-thick, hot-spring deposit contains up to 1.04 ppm gold and high concentrations of tellurium, copper and vanadium. Hydrothermal eruption breccia beds are present within the deposit. The presence of the hot-spring deposit and banded and comb textures of the vein quartz suggest that the vein system presently exposed formed at a shallow level. The vein systems in Palau and Yap have similar textures, geochemical suites and alteration assemblages. Both vein systems formed late in the volcanic evolution of the intra-oceanic arc. Media tested for their effectiveness in geochemical exploration in the tropical, deeply weathered environment of Palau and Yap included stream sediments, heavy-mineral concentrates from stream sediments, and sediment from the mangrove coastal environment which is well developed around most of the islands of Yap and Palau. Geochemical surveys in both Yap and Palau of mangrove sediment show that adjacent to areas of gold mineralization, gold and tellu

Structural interpretation of El Hierro (Canary Islands) rifts system from gravity inversion modelling

NASA Astrophysics Data System (ADS)

Sainz-Maza, S.; Montesinos, F. G.; Martí, J.; Arnoso, J.; Calvo, M.; Borreguero, A.

2017-08-01

Recent volcanism in El Hierro Island is mostly concentrated along three elongated and narrow zones which converge at the center of the island. These zones with extensive volcanism have been identified as rift zones. The presence of similar structures is common in many volcanic oceanic islands, so understanding their origin, dynamics and structure is important to conduct hazard assessment in such environments. There is still not consensus on the origin of the El Hierro rift zones, having been associated with mantle uplift or interpreted as resulting from gravitational spreading and flank instability. To further understand the internal structure and origin of the El Hierro rift systems, starting from the previous gravity studies, we developed a new 3D gravity inversion model for its shallower layers, gathering a detailed picture of this part of the island, which has permitted a new interpretation about these rifts. Previous models already identified a main central magma accumulation zone and several shallower high density bodies. The new model allows a better resolution of the pathways that connect both levels and the surface. Our results do not point to any correspondence between the upper parts of these pathways and the rift identified at the surface. Non-clear evidence of progression toward deeper parts into the volcanic system is shown, so we interpret them as very shallow structures, probably originated by local extensional stresses derived from gravitational loading and flank instability, which are used to facilitate the lateral transport of magma when it arrives close to the surface.

The relationship between eruptive activity, flank collapse, and sea level at volcanic islands: A long-term (>1 Ma) record offshore Montserrat, Lesser Antilles

NASA Astrophysics Data System (ADS)

Coussens, Maya; Wall-Palmer, Deborah; Talling, Peter. J.; Watt, Sebastian. F. L.; Cassidy, Michael; Jutzeler, Martin; Clare, Michael A.; Hunt, James. E.; Manga, Michael; Gernon, Thomas. M.; Palmer, Martin. R.; Hatter, Stuart. J.; Boudon, Georges; Endo, Daisuke; Fujinawa, Akihiko; Hatfield, Robert; Hornbach, Matthew. J.; Ishizuka, Osamu; Kataoka, Kyoko; Le Friant, Anne; Maeno, Fukashi; McCanta, Molly; Stinton, Adam. J.

2016-07-01

Hole U1395B, drilled southeast of Montserrat during Integrated Ocean Drilling Program Expedition 340, provides a long (>1 Ma) and detailed record of eruptive and mass-wasting events (>130 discrete events). This record can be used to explore the temporal evolution in volcanic activity and landslides at an arc volcano. Analysis of tephra fall and volcaniclastic turbidite deposits in the drill cores reveals three heightened periods of volcanic activity on the island of Montserrat (˜930 to ˜900 ka, ˜810 to ˜760 ka, and ˜190 to ˜120 ka) that coincide with periods of increased volcano instability and mass-wasting. The youngest of these periods marks the peak in activity at the Soufrière Hills volcano. The largest flank collapse of this volcano (˜130 ka) occurred toward the end of this period, and two younger landslides also occurred during a period of relatively elevated volcanism. These three landslides represent the only large (>0.3 km3) flank collapses of the Soufrière Hills edifice, and their timing also coincides with periods of rapid sea level rise (>5 m/ka). Available age data from other island arc volcanoes suggest a general correlation between the timing of large landslides and periods of rapid sea level rise, but this is not observed for volcanoes in intraplate ocean settings. We thus infer that rapid sea level rise may modulate the timing of collapse at island arc volcanoes, but not in larger ocean-island settings.

Volcanic geomorphosites and geotourism in Las Cañadas del Teide National Park, Tenerife, Canary Islands, Spain

NASA Astrophysics Data System (ADS)

Dóniz-Paéz, Javier; Becerra-Ramírez, Rafael; González-Cárdenas, Elena; Rodriguez, Fátima

2017-04-01

Geomorphosites and geoturism studies are increasing for the high scientific, societal, cultural, and aesthetic values of the relief. Volcanic areas are exciting targets for such studies for their geodiversity. The aim of these study is an inventory of volcanic geomorphosites and its relationship to geotourism. Las Cañadas del Teide National Park (LCTNP) is a volcanic complex area located in the central part of Tenerife island (Canary Islands, Spain). This area is a volcanic paradise rich in spectacular landforms: stratovolcanoes, calderas, cinder cones, craters, pahoehoe, aa, block and balls lavas, gullies, etc. The national park is registered in the world heritage list (UNESCO) in 2007 as a natural site. The LCTNP receives more than 2,5 million tourists per year and it has 21 main pahts and 14 secondary ones. For the selection of the geomophosites the LCTNP was divided into four geomorphological units (Teide-Pico Viejo stratovolcanoes, Las Cañadas Caldera wall, the bottom of Las Cañadas and the basaltic volcanic field) and each one of them is selected the most representative geomorphosites by its geodiversity, because of its geomorphological heritage, its landscapes and its tourist potential with the paths. All selected geomorphosites are within areas where public use is allowed in the park. The inventory classifies the 23 geomorphosites in two main categories: (a) direct volcanic with 17 geomorphosites (stratovolcanoes, domes, cinder cones, pahoehoe, aa and bloc lava flows, etc.) and (b) eroded volcanic landforms with 6 (wall of Las Cañadas caldera, talusees, foodplains, etc.). The Teide-Pico Viejo unit is which has more geomorphosites with 8 and the Las Cañadas wall unit possessing less with 5. The assessment evaluates the scientific, cultural/historical, and use values and helps to define priorities in site management. These geomorphosites demonstrate the volcanic history and processes of the LCTNP.

Ages and geochemical comparison of coeval plutons and volcanics from the central and eastern Aleutian arc

NASA Astrophysics Data System (ADS)

Cai, Y.; Kelemen, P. B.; Goldstein, S. L.; Yogodzinski, G. M.; Hemming, S. R.; Rioux, M. E.; Cooperdock, E. H. G.

2016-12-01

On average, arc volcanics are compositionally different from the bulk continental crust. The relatively little known plutonic part of intra-oceanic arcs is more similar to continental crust, and may play a significant role for understanding continental crust formation. Our pilot study [1] demonstrated that in the central and eastern Aleutian islands, predominantly tholeiitic Quaternary volcanic rocks have statistically different Pb-Nd-Sr-Hf isotopic signatures than predominantly calc-alkaline Miocene and older plutonic rocks, showing that these plutonics and volcanics were derived from compositionally different sources. However, studies of older volcanics are needed to determine whether (1) there was a change in magma chemistry in the central and eastern Aleutian arc between the Miocene and the present-day, or (2) coeval plutonics and volcanics are compositionally different, and formed by different processes. For example, silica- and water-rich calc-alkaline magmas may preferentially stall and form plutons after extensive degassing and rapid viscosity increase in the mid-crust, while silica- and water-poor tholeiitic magmas tend to erupt at the surface. Here we report new geochronological and geochemical results on samples collected during the 2015 GeoPRISMS shared logistics field campaign. We collected more than 500 volcanic and plutonic samples from Unalaska, Umnak and Atka islands, including pillow lavas, sills, and larger plutons. A subset of 50 samples has been analyzed for major and trace element chemistry, Pb-Nd-Sr-Hf isotopes, and Ar-Ar geochronology. So far,40Ar/39Ar cooling dates measured for the volcanics span a wide range, from zero to 35 Ma, which is comparable to the age distribution of the plutons ( 9 Ma to 39 Ma) from these islands. The forthcoming, combined geochronology and geochemistry of coeval plutonics and volcanics will contribute to our understanding of the connections between arc magmatism and continental crust formation. [1] Cai et al., EPSL, 2015, vol 431, pp. 119-126.

Island of Hawaii, State of Hawaii seen from Skylab

NASA Technical Reports Server (NTRS)

1974-01-01

A vertical view of the Island of Hawaii, State of Hawaii (19.5N, 155.5W), as photographed from the Skylab space station in Earth orbit by a Skylab 4 crewman. This photograph, taken on January 8, 1974, is very useful in studies of volcanic areas. Prominent volcanic features such as the summit caldera on Mauna Loa, the extinct volcano Mauna Kea, the Kilauea caldera, and the pit crater at Halo Mau Mau within the caldera are easily identified. Kilauea was undergoing frequent eruption during the mission. Detailed features such as the extent and delineation of historic lava flows on Mauna Loa can be determined and are important parameters in volcanic studies.

Aeromagnetic anomalies reveal the link between magmatism and tectonics during the early formation of the Canary Islands.

PubMed

Blanco-Montenegro, Isabel; Montesinos, Fuensanta G; Arnoso, José

2018-01-08

The 3-D inverse modelling of a magnetic anomaly measured over the NW submarine edifice of the volcanic island of Gran Canaria revealed a large, reversely-magnetized, elongated structure following an ENE-WSW direction, which we interpreted as a sill-like magmatic intrusion emplaced during the submarine growth of this volcanic island, with a volume that could represent up to about 20% of the whole island. The elongated shape of this body suggests the existence of a major crustal fracture in the central part of the Canary Archipelago which would have favoured the rapid ascent and emplacement of magmas during a time span from 0.5 to 1.9 My during a reverse polarity chron of the Earth's magnetic field prior to 16 Ma. The agreement of our results with those of previous gravimetric, seismological and geodynamical studies strongly supports the idea that the genesis of the Canary Islands was conditioned by a strike-slip tectonic framework probably related to Atlas tectonic features in Africa. These results do not contradict the hotspot theory for the origin of the Canary magmatism, but they do introduce the essential role of regional crustal tectonics to explain where and how those magmas both reached the surface and built the volcanic edifices.

A spaceborne inventory of volcanic activity in Antarctica and southern oceans, 2000-10

USGS Publications Warehouse

Patrick, Matthew R.; Smellie, John L.

2015-01-01

Of the more than twenty historically active volcanoes in Antarctica and the sub-Antarctic region only two, to our knowledge, host any ground-based monitoring instruments. Moreover, because of their remoteness, most of the volcanoes are seldom visited, thus relegating the monitoring of volcanism in this region almost entirely to satellites. In this study, high temporal resolution satellite data from the Hawaii Institute of Geophysics and Planetology's MODVOLC system using MODIS (Moderate Resolution Imaging Spectroradiometer) are complemented with high spatial resolution data (ASTER, or Advanced Spaceborne Thermal Emission and Reflection Radiometer, and similar sensors) to document volcanic activity throughout the region during the period 2000–10. Five volcanoes were observed in eruption (Mount Erebus, Mount Belinda, Mount Michael, Heard Island and McDonald Island), which were predominantly low-level and effusive in nature. Mount Belinda produced tephra, building a cinder cone in addition to an extensive lava field. Five volcanoes exhibited detectable thermal, and presumed fumarolic, activity (Deception, Zavodovski, Candlemas, Bristol, and Bellingshausen islands). A minor eruption reported at Marion Island was not detected in our survey due to its small size. This study also discovered a new active vent on Mount Michael, tracked dramatic vent enlargement on Heard Island, and provides an improved picture of the morphology of some of the volcanoes.

Spatial vent opening probability map of El Hierro Island (Canary Islands, Spain)

NASA Astrophysics Data System (ADS)

Becerril, Laura; Cappello, Annalisa; Galindo, Inés; Neri, Marco; Del Negro, Ciro

2013-04-01

The assessment of the probable spatial distribution of new eruptions is useful to manage and reduce the volcanic risk. It can be achieved in different ways, but it becomes especially hard when dealing with volcanic areas less studied, poorly monitored and characterized by a low frequent activity, as El Hierro. Even though it is the youngest of the Canary Islands, before the 2011 eruption in the "Las Calmas Sea", El Hierro had been the least studied volcanic Island of the Canaries, with more historically devoted attention to La Palma, Tenerife and Lanzarote. We propose a probabilistic method to build the susceptibility map of El Hierro, i.e. the spatial distribution of vent opening for future eruptions, based on the mathematical analysis of the volcano-structural data collected mostly on the Island and, secondly, on the submerged part of the volcano, up to a distance of ~10-20 km from the coast. The volcano-structural data were collected through new fieldwork measurements, bathymetric information, and analysis of geological maps, orthophotos and aerial photographs. They have been divided in different datasets and converted into separate and weighted probability density functions, which were then included in a non-homogeneous Poisson process to produce the volcanic susceptibility map. Future eruptive events on El Hierro is mainly concentrated on the rifts zones, extending also beyond the shoreline. The major probabilities to host new eruptions are located on the distal parts of the South and West rifts, with the highest probability reached in the south-western area of the West rift. High probabilities are also observed in the Northeast and South rifts, and the submarine parts of the rifts. This map represents the first effort to deal with the volcanic hazard at El Hierro and can be a support tool for decision makers in land planning, emergency plans and civil defence actions.

Geochronological constraints on the evolution of El Hierro (Canary Islands)

NASA Astrophysics Data System (ADS)

Becerril, Laura; Ubide, Teresa; Sudo, Masafumi; Martí, Joan; Galindo, Inés; Galé, Carlos; Morales, Jose María; Yepes, Jorge; Lago, Marceliano

2016-01-01

New age data have been obtained to time constrain the recent Quaternary volcanism of El Hierro (Canary Islands) and to estimate its recurrence rate. We have carried out 40Ar/39Ar geochronology on samples spanning the entire volcanostratigraphic sequence of the island and 14C geochronology on the most recent eruption on the northeast rift of the island: 2280 ± 30 yr BP. We combine the new absolute data with a revision of published ages onshore, some of which were identified through geomorphological criteria (relative data). We present a revised and updated chronology of volcanism for the last 33 ka that we use to estimate the maximum eruptive recurrence of the island. The number of events per year determined is 9.7 × 10-4 for the emerged part of the island, which means that, as a minimum, one eruption has occurred approximately every 1000 years. This highlights the need of more geochronological data to better constrain the eruptive recurrence of El Hierro.

Geology and Geochemistry of Magmatic Rocks from the Southern Part of the Kyushu-Palau Ridge in the Philippine Sea

NASA Astrophysics Data System (ADS)

Lelikov, E. P.; Sedin, V. T.; Pugachev, A. A.

2018-03-01

The paper reports the results of a geochemical study of volcanogenic rocks from the southern part of the Kyushu-Palau Ridge. Volcanic structures, such as plateaulike rises, mountain massifs, and single volcanoes, are the major relief-forming elements of the southern part of the Kyushu-Palau Ridge. They are divided into three types according to the features of the relief and geological structure: shield, cone-shaped, and dome-shaped volcanoes. The ridge was formed on oceanic crust in the Late Mesozoic and underwent several stages of evolution with different significance and application of forces (tension and compression). Change in the geodynamic conditions during the geological evolution of the ridge mostly determined the composition of volcanic rocks of deep-mantle nature. Most of the ridge was formed by the Early Paleogene under geodynamic conditions close to the formation of oceanic islands (shield volcanoes) under tension. The island arc formed on the oceanic basement in the compression mode in the Late Eocene-Early Oligocene. Dome-shaped volcanic edifices composed of alkaline volcanic rocks were formed in the Late Oligocene-Early Miocene under tension. Based on the new geochemical data, detailed characteristics of volcanic rocks making up the shield, cone-shape, and dome-shape stratovolcanoes resulting in the features of these volcanic edifices are given for the first time. Continuous volcanism (with an age from the Cretaceous to the Late Miocene and composition from oceanic tholeiite to calc-alkaline volcanites of the island arc type) resulting in growth of the Earth's crust beneath the Kyushu-Palau Ridge was the major factor in the formation this ridge.

Building and Characterizing Volcanic Landscapes with a Numerical Landscape Evolution Model and Spectral Techniques

NASA Astrophysics Data System (ADS)

Richardson, P. W.; Karlstrom, L.

2016-12-01

The competition between constructional volcanic processes such as lava flows, cinder cones, and tumuli compete with physical and chemical erosional processes to control the morphology of mafic volcanic landscapes. If volcanic effusion rates are high, these landscapes are primarily constructional, but over the timescales associated with hot spot volcanism (1-10 Myr) and arcs (10-50 Myr), chemical and physical erosional processes are important. For fluvial incision to occur, initially high infiltration rates must be overcome by chemical weathering or input of fine-grained sediment. We investigate lava flow resurfacing, using a new lava flow algorithm that can be calibrated for specific flows and eruption magnitude/frequency relationships, into a landscape evolution model to complete two modeling experiments to investigate the interplay between volcanic resurfacing and fluvial incision. We use a stochastic spatial vent distribution calibrated from the Hawaiian eruption record to resurface a synthetically produced ocean island. In one experiment, we investigate the consequences of including time-dependent channel incision efficiency. This effectively mimics the behavior of transient hydrological development of lava flows. In the second experiment, we explore the competition between channel incision and lava flow resurfacing. The relative magnitudes of channel incision versus lava flow resurfacing are captured in landscape topography. For example, during the shield building period for ocean islands, effusion rates are high and the signature of lava flow resurfacing dominates. In contrast, after the shield building phase, channel incision begins and eventually dominates the topographic signature. We develop a dimensionless ratio of resurfacing rate to erosion rate to characterize the transition between these processes. We use spectral techniques to characterize volcanic features and to pinpoint the transition between constructional and erosional morphology on modeled landscapes and on the Big Island of Hawaii.

Volcanic tsunamis and prehistoric cultural transitions in Cook Inlet, Alaska

USGS Publications Warehouse

Beget, J.; Gardner, C.; Davis, K.

2008-01-01

The 1883 eruption of Augustine Volcano produced a tsunami when a debris avalanche traveled into the waters of Cook Inlet. Older debris avalanches and coeval paleotsunami deposits from sites around Cook Inlet record several older volcanic tsunamis. A debris avalanche into the sea on the west side of Augustine Island ca. 450??years ago produced a wave that affected areas 17??m above high tide on Augustine Island. A large volcanic tsunami was generated by a debris avalanche on the east side of Augustine Island ca. 1600??yr BP, and affected areas more than 7??m above high tide at distances of 80??km from the volcano on the Kenai Peninsula. A tsunami deposit dated to ca. 3600??yr BP is tentatively correlated with a southward directed collapse of the summit of Redoubt Volcano, although little is known about the magnitude of the tsunami. The 1600??yr BP tsunami from Augustine Volcano occurred about the same time as the collapse of the well-developed Kachemak culture in the southern Cook Inlet area, suggesting a link between volcanic tsunamis and prehistoric cultural changes in this region of Alaska. ?? 2008 Elsevier B.V.

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

USGS Publications Warehouse

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

2014-01-01

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

Trace element geochemistry of Archean volcanic rocks

NASA Technical Reports Server (NTRS)

Jahn, B.-M.; Shih, C.-Y.; Murthy, V. R.

1974-01-01

The K, Rb, Sr, Ba and rare-earth-element contents of some Archean volcanic rocks from the Vermilion greenstone belt, northeast Minnesota, were determined by the isotopic dilution method. The characteristics of trace element abundances, supported by the field occurrences and major element chemistry, suggest that these volcanic rocks were formed in an ancient island arc system.

Major and trace element abundances in volcanic rocks of orogenic areas.

NASA Technical Reports Server (NTRS)

Jakes, P.; White, A. J. R.

1972-01-01

The composition of recent island-arc volcanic rocks in relation to their geographic and stratigraphic relations is discussed. The differences in composition between volcanic rocks and those in continental margins are pointed out. Trace elements and major elements are shown to suggest a continuous gradational sequence from tholeiites through calc-alkaline rocks to shoshonites.

Russian eruption warning systems for aviation

USGS Publications Warehouse

Neal, C.; Girina, O.; Senyukov, S.; Rybin, A.; Osiensky, J.; Izbekov, P.; Ferguson, G.

2009-01-01

More than 65 potentially active volcanoes on the Kamchatka Peninsula and the Kurile Islands pose a substantial threat to aircraft on the Northern Pacific (NOPAC), Russian Trans-East (RTE), and Pacific Organized Track System (PACOTS) air routes. The Kamchatka Volcanic Eruption Response Team (KVERT) monitors and reports on volcanic hazards to aviation for Kamchatka and the north Kuriles. KVERT scientists utilize real-time seismic data, daily satellite views of the region, real-time video, and pilot and field reports of activity to track and alert the aviation industry of hazardous activity. Most Kurile Island volcanoes are monitored by the Sakhalin Volcanic Eruption Response Team (SVERT) based in Yuzhno-Sakhalinsk. SVERT uses daily moderate resolution imaging spectroradiometer (MODIS) satellite images to look for volcanic activity along this 1,250-km chain of islands. Neither operation is staffed 24 h per day. In addition, the vast majority of Russian volcanoes are not monitored seismically in real-time. Other challenges include multiple time-zones and language differences that hamper communication among volcanologists and meteorologists in the US, Japan, and Russia who share the responsibility to issue official warnings. Rapid, consistent verification of explosive eruptions and determination of cloud heights remain significant technical challenges. Despite these difficulties, in more than a decade of frequent eruptive activity in Kamchatka and the northern Kuriles, no damaging encounters with volcanic ash from Russian eruptions have been recorded. ?? Springer Science+Business Media B.V. 2009.

Estimating flexural rigidity and load magnitude required for formation of Ross Island flexure moat

NASA Astrophysics Data System (ADS)

Jha, S.; Harry, D. L.; Wenman, C. P.

2017-12-01

Lithospheric flexural subsidence around Ross Island in West Antarctica led to formation of the Ross Island flexure moat. This subsidence was caused by two major volcanic phases on Ross Island. The first phase saw the first surficial expression of Ross Island and volcanism at Mt. Bird to the north of Ross Island, which lasted from 5.2 - 2.9 Ma. The second phase lasted from 1.78 Ma to present and is comprised of eruptions from Mt. Terror to the east, Mt. Erebus to the west and Hut Point Peninsula (HPP) to the south of Ross Island. Flexural subsidence of the lithosphere due to volcanism on Ross Island led to formation of a sedimentary moat around the island, which is preserved in stratigraphy imaged on seismic reflection profiles. We identified 5 unconformities (from deepest upward Ri, RMU1, RMU2, RMU3, RMU4) in the seismic surveys which correspond to flexural subsidence episodes around Ross Island since early Pliocene. Ri (4.4 Ma) lies near the bottom of the flexural moat and RMU4 near the seafloor and top of the moat fill. These unconformities were used to make isopach maps to constrain flexure modeling of the area. Isopach maps show circular or semi-circular flexure basins around Ross Island which is approximated using a continuous plate, point load flexure model. We used Ri - sea floor isopach to constrain flexure models for 5 profiles centered on 4 volcanic centers and trending radially out of Ross Island. Flexure models along two profiles beginning on Mt. Bird and one profile off HPP show a flexural rigidity range of 1.47 - 6.44 x 1018 Nm with load center of mass on Mt. Bird and on HPP, respectively. A similar model along a profile initiating on Mt. Terror, passing through Mt Erebus and extending west of Ross Island across the moat, yielded a higher flexural rigidity estimate of 2.03 x 1019 Nm with load centered at Mt. Erebus. A flexure model to the north east of Ross Island along a profile beginning at Mt Terror and trending north, provide the highest flexural rigidity estimate of 6.9 x 1019 Nm. The load magnitudes determined from these flexure models lie in the range of 4.6 x 1015 N - 4.3 x 1016 N. This is less than the topographic load (6.9 x 1017 N estimated from BEDMAP2) produced by the island by one to two orders of magnitude. The difference in load magnitudes suggest anomalously low densities caused by high lower crust and mantle temperatures in the region.

Submarine glacial landforms and interactions with volcanism around Sub-Antarctic Heard and McDonald Islands

NASA Astrophysics Data System (ADS)

Picard, K.; Watson, S. J.; Fox, J. M.; Post, A.; Whittaker, J. M.; Lucieer, V.; Carey, R.; Coffin, M. F.; Hodgson, D.; Hogan, K.; Graham, A. G. C.

2017-12-01

Unravelling the glacial history of Sub-Antarctic islands can provide clues to past climate and Antarctic ice sheet stability. The glacial history of many sub-Antarctic islands is poorly understood, including the Heard and McDonald Islands (HIMI) located on the Kerguelen Plateau in the southern Indian Ocean. The geomorphologic development of HIMI has involved a combination of construction via hotspot volcanism and mechanical erosion caused by waves, weather, and glaciers. Today, the 2.5 km2 McDonald Islands are not glacierised; in contrast, the 368 km2 Heard Island has 12 major glaciers, some extending from the summit of 2813 m to sea level. Historical accounts from Heard Island suggest that the glaciers were more extensive in the 1850s to 1870s, and have retreated at least 12% (33.89 km2) since 1997. However, surrounding bathymetry suggests a much more extensive previous glaciation of the HIMI region that encompassed 9,585 km2, likely dating back at least to the Last Glacial Maximum (LGM) ca. 26.5 -19 ka. We present analyses of multibeam bathymetry and backscatter data, acquired aboard RV Investigator in early 2016, that support the previous existence of an extensive icecap. These data reveal widespread ice-marginal and subglacial features including moraines, over-deepened troughs, drumlins and crag-and-tails. Glacial landforms suggest paleo-ice flow directions and a glacial extent that are consistent with previously documented broad scale morphological features. We identify >660 iceberg keel scours in water depths ranging from 150 - 530 m. The orientations of the iceberg keel scours reflect the predominantly east-flowing Antarctic Circumpolar Current and westerly winds in the region. 40Ar/39Ar dating of volcanic rocks from submarine volcanoes around McDonald Islands suggests that volcanism and glaciation coincided. The flat-topped morphology of these volcanoes may result from lava-ice interaction or erosion by glaciers post eruption during a time of extensive ice-sheet cover and/or wave base erosion during sea level low stands. The prevalence and range of glacial landforms around HIMI suggest extensive past glaciation, and that glaciers have exerted a major influence on submarine geomorphology.

A preliminary evaluation of ERTS-1 images on the volcanic areas of Southern Italy

NASA Technical Reports Server (NTRS)

Cassinis, R.; Lechi, G. M.

1973-01-01

The test site selected for the investigation covers nearly all the regions of active and quiescent volcanism in southern Italy, i.e. the eastern part of the island of Sicily, the Aeolian Islands and the area of Naples. The three active European volcanoes (Etna, Stromboli and Vesuvius) are included. The investigation is in the frame of a program for the surveillance of active volcanoes by geophysical (including remote sensing thermal methods) and geochemical methods. By the multispectral analysis of ERTS-1 data it is intended to study the spectral behavior of the volcanic materials as well as the major geological lineaments with special reference to those associated with the volcanic region. Secondary objectives are also the determination of the hydrographic network seasonal behavior and the relationship between the vegetation cover and the different type of soils and rocks.

Infrasonic Influence of Volcanos

NASA Astrophysics Data System (ADS)

Hosman, Ashley

2014-03-01

My presentation will consist of a poster on the use of ring laser interferometers to detect infrasound. The research was performed during the summer of 2013 and it focused on the finding infrasound emissions created by volcanic activity. I will explain how a ring laser works and discuss how I analyze the collected data using Fast Fourier Transforms. Due to the extreme distances over which infrasound can travel, I will also stress the need to compare the detected responses to specific volcanic eruptions. Finally, I will purpose practical applications of my research. One of the more promising applications is to use ring lasers to detect volcanic activity in remote areas such as parts of the Aleutian Islands. There is considerable air traffic over the Aleutian Islands. Volcanic plumes are a significant aviation hazard and can damage jet engines to the extent that they will no longer operate. Thank you to the NSF ans NASA foundations for providing funding for this reseach.

Use of Low-Cost Acquisition Systems with an Embedded Linux Device for Volcanic Monitoring

PubMed Central

Moure, David; Torres, Pedro; Casas, Benito; Toma, Daniel; Blanco, María José; Del Río, Joaquín; Manuel, Antoni

2015-01-01

This paper describes the development of a low-cost multiparameter acquisition system for volcanic monitoring that is applicable to gravimetry and geodesy, as well as to the visual monitoring of volcanic activity. The acquisition system was developed using a System on a Chip (SoC) Broadcom BCM2835 Linux operating system (based on DebianTM) that allows for the construction of a complete monitoring system offering multiple possibilities for storage, data-processing, configuration, and the real-time monitoring of volcanic activity. This multiparametric acquisition system was developed with a software environment, as well as with different hardware modules designed for each parameter to be monitored. The device presented here has been used and validated under different scenarios for monitoring ocean tides, ground deformation, and gravity, as well as for monitoring with images the island of Tenerife and ground deformation on the island of El Hierro. PMID:26295394

Use of Low-Cost Acquisition Systems with an Embedded Linux Device for Volcanic Monitoring.

PubMed

Moure, David; Torres, Pedro; Casas, Benito; Toma, Daniel; Blanco, María José; Del Río, Joaquín; Manuel, Antoni

2015-08-19

This paper describes the development of a low-cost multiparameter acquisition system for volcanic monitoring that is applicable to gravimetry and geodesy, as well as to the visual monitoring of volcanic activity. The acquisition system was developed using a System on a Chip (SoC) Broadcom BCM2835 Linux operating system (based on DebianTM) that allows for the construction of a complete monitoring system offering multiple possibilities for storage, data-processing, configuration, and the real-time monitoring of volcanic activity. This multiparametric acquisition system was developed with a software environment, as well as with different hardware modules designed for each parameter to be monitored. The device presented here has been used and validated under different scenarios for monitoring ocean tides, ground deformation, and gravity, as well as for monitoring with images the island of Tenerife and ground deformation on the island of El Hierro.

Fracture and damage localization in volcanic edifice rocks from El Hierro, Stromboli and Tenerife.

PubMed

Harnett, Claire E; Benson, Philip M; Rowley, Pete; Fazio, Marco

2018-01-31

We present elastic wave velocity and strength data from a suite of three volcanic rocks taken from the volcanic edifices of El Hierro and Tenerife (Canary Islands, Spain), and Stromboli (Aeolian Islands, Italy). These rocks span a range of porosity and are taken from volcanoes that suffer from edifice instability. We measure elastic wave velocities at known incident angles to the generated through-going fault as a function of imposed strain, and examine the effect of the damage zone on P-wave velocity. Such data are important as field measurements of elastic wave tomography are key tools for understanding volcanic regions, yet hidden fractures are likely to have a significant effect on elastic wave velocity. We then use elastic wave velocity evolution to calculate concomitant crack density evolution which ranges from 0 to 0.17: highest values were correlated to the damage zone in rocks with the highest initial porosity.

Episodic eruptions of volcanic ash trigger a reversible cascade of nuisance species outbreaks in pristine coral habitats.

PubMed

Schils, Tom

2012-01-01

Volcanically active islands abound in the tropical Pacific and harbor complex coral communities. Whereas lava streams and deep ash deposits are well-known to devastate coral communities through burial and smothering, little is known about the effect of moderate amounts of small particulate ash deposits on reef communities. Volcanic ash contains a diversity of chemical compounds that can induce nutrient enrichments triggering changes in benthic composition. Two independently collected data sets on the marine benthos of the pristine and remote reefs around Pagan Island, Northern Mariana Islands, reveal a sudden critical transition to cyanobacteria-dominated communities in 2009-2010, which coincides with a period of continuous volcanic ash eruptions. Concurrently, localized outbreaks of the coral-killing cyanobacteriosponge Terpios hoshinota displayed a remarkable symbiosis with filamentous cyanobacteria, which supported the rapid overgrowth of massive coral colonies and allowed the sponge to colonize substrate types from which it has not been documented before. The chemical composition of tephra from Pagan indicates that the outbreak of nuisance species on its reefs might represent an early succession stage of iron enrichment (a.k.a. "black reefs") similar to that caused by anthropogenic debris like ship wrecks or natural events like particulate deposition from wildfire smoke plumes or desert dust storms. Once Pagan's volcanic activity ceased in 2011, the cyanobacterial bloom disappeared. Another group of well-known nuisance algae in the tropical Pacific, the pelagophytes, did not reach bloom densities during this period of ash eruptions but new species records for the Northern Mariana Islands were documented. These field observations indicate that the study of population dynamics of pristine coral communities can advance our understanding of the resilience of tropical reef systems to natural and anthropogenic disturbances.

Water resources of the Truk Islands

USGS Publications Warehouse

Van der Brug, Otto

1983-01-01

The Truk Islands, part of the Caroline Islands in the western Pacific, consist of 19 volcanic islands and about 65 coral islets. The volcanic islands and some of the coral islets are scattered in an 820-square-mile lagoon enclosed by a 125-mile long barrier reef. Moen, although not the largest, is by far the most developed island and is the adminstrative, commercial, educational, and transporation center of the islands. Monthly rainfall records for most years are available since 1903. Rainfall-runoff comparisons show that about half the annual rainfall runs off as surface water into Truk Lagoon. Flow characteristics of the major streams, based on more than 11 years of record, are provided and the application of data for possible use in the design of reservoirs and rain catchments is included. Historical and present development of all water sources is given. The chemical analyses of surface and ground water on Moen, with the exception of water from well 9, show the good quality of the water sources. This report summarizes all hydrologic data collected and provides interpretations that can be used for development and management of the water resources. (USGS)

Unusual Volcanic Tremor Observations in Fogo Island, Cape Verde

NASA Astrophysics Data System (ADS)

Custodio, S. I.; Heleno, S. I.

2004-12-01

Volcanic tremor is a ground motion characterized by well-defined frequencies, and has traditionally been explained by the movement of fluids, namely magma, in conduits or cracks (Chouet, 1996). Thus tremor has the potential to reveal key aspects of volcanic structure and dynamics. Two types of previously unreported seismic signals have been observed in Fogo volcano: a) tide-modulated seismic noise and volcanic tremor, and b) high-frequency low-attenuation harmonic tremor. Amplitude modulation of seismic noise can be detected by simple eye-inspection of raw data in some stations of the VIGIL Network, Fogo Volcano. A more detailed analysis shows that certain frequency bands which we interpret as volcanic tremor, mainly in the range 2.0-3.0Hz, are preferentially modulated. The main frequency of modulation is 1.93 c.p.d., which corresponds to M2, the semi-diurnal lunar harmonic. Air pressure and temperature, which are continuously monitored in Fogo Island, have been analyzed and cannot explain the observed periodicity. Thus we conclude that seismic noise and tremor amplitudes are controlled by tides (Custodio et al., 2003). A relation between the tidal modulation and hydrothermal systems activity is suspected and under investigation. High-frequency (HF) tremor (5-20 Hz) has been recorded simultaneously in several stations in Fogo Island and even in different islands of the Cape Verde archipelago (up to distances of 120 km). In volcanic environments high-frequency motions are normally recorded in a small area close to the source, due to the strong attenuation of seismic waves. Non-volcanic origins for HF tremor were examined: cultural noise, whale vocalizations, ship noise, electronic/processing artifacts and path and/or site effects were all considered and dismissed. Emergent arrivals and strong site effects render source location a difficult task, but the analysis of wave polarizations and amplitude distributions seems to point to an offshore source. Two alternative mechanisms are presently being considered: a) propagation in the ocean sound channel of T-waves generated by resonance in a shallow conduit/chamber, and b) existence of a deep strong source, such as a large fluid-filled crack, capable of producing tremor with a complex pattern that propagates to large distances.

Volcanic hazard assessment for the Canary Islands (Spain) using extreme value theory

NASA Astrophysics Data System (ADS)

Sobradelo, R.; Martí, J.; Mendoza-Rosas, A. T.; Gómez, G.

2011-10-01

The Canary Islands are an active volcanic region densely populated and visited by several millions of tourists every year. Nearly twenty eruptions have been reported through written chronicles in the last 600 yr, suggesting that the probability of a new eruption in the near future is far from zero. This shows the importance of assessing and monitoring the volcanic hazard of the region in order to reduce and manage its potential volcanic risk, and ultimately contribute to the design of appropriate preparedness plans. Hence, the probabilistic analysis of the volcanic eruption time series for the Canary Islands is an essential step for the assessment of volcanic hazard and risk in the area. Such a series describes complex processes involving different types of eruptions over different time scales. Here we propose a statistical method for calculating the probabilities of future eruptions which is most appropriate given the nature of the documented historical eruptive data. We first characterize the eruptions by their magnitudes, and then carry out a preliminary analysis of the data to establish the requirements for the statistical method. Past studies in eruptive time series used conventional statistics and treated the series as an homogeneous process. In this paper, we will use a method that accounts for the time-dependence of the series and includes rare or extreme events, in the form of few data of large eruptions, since these data require special methods of analysis. Hence, we will use a statistical method from extreme value theory. In particular, we will apply a non-homogeneous Poisson process to the historical eruptive data of the Canary Islands to estimate the probability of having at least one volcanic event of a magnitude greater than one in the upcoming years. This is done in three steps: First, we analyze the historical eruptive series to assess independence and homogeneity of the process. Second, we perform a Weibull analysis of the distribution of repose time between successive eruptions. Third, we analyze the non-homogeneous Poisson process with a generalized Pareto distribution as the intensity function.

Continuous monitoring of the C isotope composition of CO_{2}-rich subsurface degassing at Tenerife, Canary Islands

NASA Astrophysics Data System (ADS)

Melián, Gladys; Asensio-Ramos, María; Padrón, Eleazar; Barrancos, José; Hernández, Pedro A.; Pérez, Nemesio M.

2017-04-01

Tenerife is the largest island of the Canarian archipelago and several volcanic eruptions have occurred in the last 500 years, the last one in 1909. The main volcano-tectonic features of Tenerife Island are three main volcano-tectonic rifts trending N-E, N-W and N-S where, at the interception center is located Las Cañadas caldera and the stratovolcano Teide-Pico Viejo. Due to the approximately 1,500 wells and water galleries (1650 km) drilled during the last 150 years tapping the island's volcanic aquifer at different depths, Tenerife is a unique natural-scale laboratory for hydrological studies in oceanic volcanic islands. Ground waters are mainly Na+-HCO3- water type, mainly due to the continuous volcanic CO2 supply from the volcanic-hydrothermal system. A signi?cant number of these galleries show a CO2-rich inner atmosphere, and gas bubbling has also been detected inside some galleries. Since 2002, an automatic geochemical station installed at the entrance of the horizontal drilling "Fuente del Valle" (TFE02 station), Arona, Tenerife, measures the activities of 222Rn and 220Rn in the gas discharged from a CO2-rich gas bubbling spot located at 2.850 m depth. Interesting variations were recorded in the 222Rn/220Rn ratio after the period of 2004 anomalous seismicity and it has been demonstrated that this is a good control spot for volcanic surveillance (Pérez et al., 2007). Thus, in November 2016, a new type of laser based isotopic analyzer, a DeltaRayTM (Thermo Fisher Scientific) was installed in the TFE02 station to measure δ13C(CO2) directly in the gas discharged from the water. The gas, collected by means of an inverted funnel, is pumped (3 L min-1) towards the gallery entrance, where the instrumentation is located, through a polyamide pipe. During the study period the recorded data show a range of δ13C(CO2) from -6.2 to -4.2‰ vs. VPDB, with an average value of -5.1‰Ṫhese values are comparable to those ones measured in the gas sampled directly at the gas bubbling spot (˜-4.7‰ unpublished data) and analyzed with a Thermo Finnigan MAT 253 isotope ratio mass spectrometer, which supports the validity of the analytical method used. This is the first time that this type of instrumentation is used to continuously monitor the δ13C(CO2) isotopic composition of the gas discharged from a gas bubbling in a horizontal drill as a geochemical tool to evaluate the volcanic activity, in particular in Tenerife, a unique natural-scale laboratory for hydrological studies in oceanic volcanic islands. To correlate temporal variations in the δ13C(CO2) isotopic composition with changes in the seismic-volcanic activity of Tenerife, a longer observation period will be required. References: Pérez et al., 2007. Pure Appl. Geophys. DOI 10.1007/s00024-007-0280

Detecting the brightness temperature from Landsat-8 thermal infra red scanner preceding the Rinjani strombolian eruption 2015

NASA Astrophysics Data System (ADS)

Suwarsono, Hidayat, Suprapto, Totok; Prasasti, Indah; Parwati, Rokhis Khomarudin, M.

2017-07-01

At the end of October to early November 2015, Rinjani Volcano that is located in Lombok Island was erupted and has catapulted the ash, pyroclastic and lava flow. The dispersion of this volcanic ash in the atmosphere has been disrupting flights and the three closest airports to be closed for a while. The existence of Rinjani Volcano geographically plays an important role in the survival of life on the island of Lombok, because large areas of land on the island are a part of the Rinjani Volcano landscape. Based on the experience of violent eruptions that have occurred in the 13th century ago, the monitoring of the volcanism activity of this volcano needs to be done intensively and continuously. This is something important to do an early detection efforts of the volcanic eruption. These efforts need to be done as a preparedness effort in order to minimize adverse impacts that may occur as a result of this eruption. This research tries to detect the volcanic eruption precursor based on changes in temperature conditions of the crater and the surrounding area. We use the medium resolution satellite data, Thermal Infra Red Scanner (TIRS), on board Landsat-8, to monitor the brightness temperature as a representative of surface temperature of the volcanic region. The results showed that the brightness temperature derived from Landsat-8 TIRS is very usefull to predict the strombolian eruption which will occur in the near future. The use of multitemporal image data is important to understand the dynamics of volcanism activity over time.

Analyses of TIMS and AVIRIS data, integrated with field and laboratory spectra, for lithological and mineralogical interpretation of Vulcano Island, Italy

NASA Technical Reports Server (NTRS)

Buongiorno, M. Fabrizia; Bogliolo, M. Paola; Salvi, Stefano; Pieri, David C.; Geneselli, Francesco

1995-01-01

Vulcano Island is part of the Eolian archipelago, located about 25 km from the northeast coast of Sicily. The archipelago comprises seven major volcanic islands, two of which are active volcanoes (Vulcano and Stromboli). Vulcano covers an area of about 50 square km, and is about 10 km long. Explosive volcanic activity has predominated in the geological evolution of Vulcano Island, and there is no evidence that this pattern has ceased. Rather, the current situation is one of unrest, so a strict regimen of continuous geophysical and geochemical monitoring has been undertaken over the last decade. Though the year-round population of Vulcano is small (under 1000), during the summer the island becomes a very popular resort, and has thousands of additional tourists at any time throughout the high season, thus substantially increasing the number of people potentially at risk from an explosive eruption or other hazards such as noxious gas emissions (e.g., CO2, H2S, SO2). During the past ten years, remote sensing data have been repetitively acquired with optical and microwave airborne sensors. The present work shows the preliminary results of a study based on the integration of various remote sensing data sets with field spectroscopy, and other laboratory analyses, for the geological and geomorphological mapping of the island. It is hoped that such work will also usefully contribute to the evaluation of the volcanic hazard potential of the islands as well as to the evaluation of the status of its current activity.

Geochemical evidence for African dust inputs to soils of western Atlantic islands: Barbados, the Bahamas, and Florida

USGS Publications Warehouse

Muhs, D.R.; Budahn, J.R.; Prospero, J.M.; Carey, S.N.

2007-01-01

We studied soils on high-purity limestones of Quaternary age on the western Atlantic Ocean islands of Barbados, the Florida Keys, and the Bahamas. Potential soil parent materials in this region, external to the carbonate substrate, include volcanic ash from the island of St. Vincent (near Barbados), volcanic ash from the islands of Dominica and St. Lucia (somewhat farther from Barbados), the fine-grained component of distal loess from the lower Mississippi River Valley, and wind-transported dust from Africa. These four parent materials can be differentiated using trace elements (Sc, Cr, Th, and Zr) and rare earth elements that have minimal mobility in the soil-forming environment. Barbados soils have compositions that indicate a complex derivation. Volcanic ash from the island of St. Vincent appears to have been the most important influence, but African dust is a significant contributor, and even Mississippi River valley loess may be a very minor contributor to Barbados soils. Soils on the Florida Keys and islands in the Bahamas appear to have developed mostly from African dust, but Mississippi River valley loess may be a significant contributor. Our results indicate that inputs of African dust are more important to the genesis of soils on islands in the western Atlantic Ocean than previously supposed. We hypothesize that African dust may also be a major contributor to soils on other islands of the Caribbean and to soils in northern South America, central America, Mexico, and the southeastern United States. Dust inputs to subtropical and tropical soils in this region increase both nutrient-holding capacity and nutrient status and thus may be critical in sustaining vegetation. Copyright 2007 by the American Geophysical Union.

Ship-wave-shaped wave clouds induced by Kuril Islands

NASA Image and Video Library

2015-06-09

The Kuril Islands are a string of volcanically-formed islands that stretch between Russia and Japan, separating the North Pacific Ocean from the Sea of Okhotsk. Subject to the cold, moist breezes from the North Atlantic, and the frigid air from Siberia, the climate is severe, with frequent storms, and ever-present winds, which often reach hurricane strength. Cloudy, windy conditions are common. On June 1, 2015 the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Aqua satellite captured this true-color image as it passed over the Kuril Islands. Clouds curl into the center of a storm system, bringing strong winds to the region. As the winds scrape over the tall volcanic peaks of the Kuril Islands, they become turbulent air behind the islands. The turbulence disturbs the cloudbank, etching its passage into a striking pattern that can be seen from space. This particular pattern is called “ship-waved-shaped wave clouds”, because the pattern can be likened to that formed behind a ship cutting through a smooth ocean. On the windward side of the Kuril Islands, the cloud bank is generally smooth, with streaks that are lined up parallel to the movement of the wind, blowing from the west and towards the east. Behind the tall volcanic peaks of the islands, V’s fan out on the leeward side, illustrating the flow of the turbulent air. Image Credit: Jeff Schmaltz, MODIS Land Rapid Response Team, NASA GSFC NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

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

PubMed

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

2014-01-02

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

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

PubMed Central

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

2014-01-01

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

Mystery #9

Atmospheric Science Data Center

2013-04-22

... lichens and mosses.   B.   The island is of volcanic origin and located at the intersection of oceanic ridges.   C.   A ...   E.   The island's seals were declared to be protected species.   5.   What is the name of the island and to which country ...

Jurassic-Paleogene intra-oceanic magmatic evolution of the Ankara Mélange, North-Central Anatolia, Turkey

NASA Astrophysics Data System (ADS)

Sarifakioglu, E.; Dilek, Y.; Sevin, M.

2013-11-01

Oceanic rocks in the Ankara Mélange along the Izmir-Ankara-Erzincan suture zone (IAESZ) in North-Central Anatolia include locally coherent ophiolite complexes (~179 Ma and ~80 Ma), seamount or oceanic plateau volcanic units with pelagic and reefal limestones (96.6 ± 1.8 Ma), metamorphic rocks with ages of 187.4 ± 3.7 Ma, 158.4 ± 4.2 Ma, and 83.5 ± 1.2 Ma, and subalkaline to alkaline volcanic and plutonic rocks of an island arc origin (~67-63 Ma). All but the arc rocks occur in a shaly-graywacke and/or serpentinite matrix, and are deformed by south-vergent thrust faults and folds that developed in the Middle to Late Eocene due to continental collisions in the region. Ophiolitic volcanic rocks have mid-ocean ridge (MORB) and island arc tholeiite (IAT) affinities showing moderate to significant LILE enrichment and depletion in Nb, Hf, Ti, Y and Yb, which indicate the influence of subduction-derived fluids in their melt evolution. Seamount/oceanic plateau basalts show ocean island basalt (OIB) affinities. The arc-related volcanic rocks, lamprophyric dikes and syeno-dioritic plutons exhibit high-K shoshonitic to medium-to high-K calc-alkaline compositions with strong enrichment in LILE, REE and Pb, and initial ϵNd values between +1.3 and +1.7. Subalkaline arc volcanic units occur in the northern part of the mélange, whereas the younger alkaline volcanic rocks and intrusions (lamprophyre dikes and syeno-dioritic plutons) in the southern part. The Early to Late Jurassic and Late Cretaceous epidote-actinolite, epidote-chlorite and epidote-glaucophane schists represent the metamorphic units formed in a subduction channel in the Northern Neotethys. The Middle to Upper Triassic neritic limestones spatially associated with the seamount volcanic rocks indicate that the Northern Neotethys was an open ocean with its MORB-type oceanic lithosphere by the Early Triassic. The Latest Cretaceous-Early Paleocene island arc volcanic, dike and plutonic rocks with subalkaline to alkaline geochemical affinities represent intraoceanic magmatism that developed on and across the subduction-accretion complex above a N-dipping, southward-rolling subducted lithospheric slab within the Northern Neotethys. The Ankara Mélange thus exhibits the record of ~120-130 million years of oceanic magmatism in geological history of the Northern Neotethys.

Depleted arc volcanism in the Alboran Sea and shoshonitic volcanism in Morocco: geochemical and isotopic constraints on Neogene tectonic processes

NASA Astrophysics Data System (ADS)

Gill, R. C. O.; Aparicio, A.; El Azzouzi, M.; Hernandez, J.; Thirlwall, M. F.; Bourgois, J.; Marriner, G. F.

2004-12-01

Samples of volcanic rocks from Alborán Island, the Alboran Sea floor and from the Gourougou volcanic centre in northern Morocco have been analyzed for major and trace elements and Sr-Nd isotopes to test current theories on the tectonic geodynamic evolution of the Alboran Sea. The Alborán Island samples are low-K tholeiitic basaltic andesites whose depleted contents of HFS elements (˜0.5×N-MORB), especially Nb (˜0.2×N-MORB), show marked geochemical parallels with volcanics from immature intra-oceanic arcs and back-arc basins. Several of the submarine samples have similar compositions, one showing low-Ca boninite affinity. 143Nd/ 144Nd ratios fall in the same range as many island-arc and back-arc basin samples, whereas 87Sr/ 86Sr ratios (on leached samples) are somewhat more radiogenic. Our data point to active subduction taking place beneath the Alboran region in Miocene times, and imply the presence of an associated back-arc spreading centre. Our sea floor suite includes a few more evolved dacite and rhyolite samples with ( 87Sr/ 86Sr) 0 up to 0.717 that probably represent varying degrees of crustal melting. The shoshonite and high-K basaltic andesite lavas from Gourougou have comparable normalized incompatible-element enrichment diagrams and Ce/Y ratios to shoshonitic volcanics from oceanic island arcs, though they have less pronounced Nb deficits. They are much less LIL- and LREE-enriched than continental arc analogues and post-collisional shoshonites from Tibet. The magmas probably originated by melting in subcontinental lithospheric mantle that had experienced negligible subduction input. Sr-Nd isotope compositions point to significant crustal contamination which appears to account for the small Nb anomalies. The unmistakable supra-subduction zone (SSZ) signature shown by our Alboran basalts and basaltic andesite samples refutes geodynamic models that attribute all Neogene volcanism in the Alboran domain to decompression melting of upwelling asthenosphere arising from convective thinning of over-thickened lithosphere. Our data support recent models in which subsidence is caused by westward rollback of an eastward-dipping subduction zone beneath the westernmost Mediterranean. Moreover, severance of the lithosphere at the edges of the rolling-back slab provides opportunities for locally melting lithospheric mantle, providing a possible explanation for the shoshonitic volcanism seen in northern Morocco and more sporadically in SE Spain.

Volcano-Tectonic Activity at Deception Island Volcano Following a Seismic Swarm in the Bransfield Rift (2014-2015)

NASA Astrophysics Data System (ADS)

Almendros, J.; Carmona, E.; Jiménez, V.; Díaz-Moreno, A.; Lorenzo, F.

2018-05-01

In September 2014 there was a sharp increase in the seismic activity of the Bransfield Strait, Antarctica. More than 9,000 earthquakes with magnitudes up to 4.6 located SE of Livingston Island were detected over a period of 8 months. A few months after the series onset, local seismicity at the nearby (˜35 km) Deception Island volcano increased, displaying enhanced long-period seismicity and several outbursts of volcano-tectonic (VT) earthquakes. Before February 2015, VT earthquakes occurred mainly at 5-20 km SW of Deception Island. In mid-February the numbers and sizes of VT earthquakes escalated, and their locations encompassed the whole volcanic edifice, suggesting a situation of generalized unrest. The activity continued in anomalously high levels at least until May 2015. Given the spatial and temporal coincidence, it is unlikely that the Livingston series and the Deception VT swarm were unrelated. We propose that the Livingston series may have produced a triggering effect on Deception Island volcano. Dynamic stresses associated to the seismic swarm may have induced overpressure in the unstable volcanic system, leading to a magmatic intrusion that may in turn have triggered the VT swarm. Alternatively, both the Livingston earthquakes and the VT swarm could be consequences of a magmatic intrusion at Deception Island. The Livingston series would be an example of precursory distal VT swarm, which seems to be a common feature preceding volcanic eruptions and magma intrusions in long-dormant volcanoes.

Lidar Observations of Stratospheric Aerosol Layer After the Mt. Pinatubo Volcanic Eruption

NASA Technical Reports Server (NTRS)

Nagai, Tomohiro; Uchino, Osamu; Fujimoto, Toshifumi

1992-01-01

The volcano Mt. Pinatubo located on the Luzon Island, Philippines, had explosively erupted on June 15, 1991. The volcanic eruptions such as volcanic ash, SO2 and H2O reached into the stratosphere over 30 km altitude by the NOAA-11 satellite observation and this is considered one of the biggest volcanic eruptions in this century. A grandiose volcanic eruption influences the atmosphere seriously and causes many climatic effects globally. There had been many impacts on radiation, atmospheric temperature and stratospheric ozone after some past volcanic eruptions. The main cause of volcanic influence depends on stratospheric aerosol, that stay long enough to change climate and other meteorological conditions. Therefore it is very important to watch stratospheric aerosol layers carefully and continuously. Standing on this respect, we do not only continue stratospheric aerosol observation at Tsukuba but also have urgently developed another lidar observational point at Naha in Okinawa Island. This observational station could be thought valuable since there is no lidar observational station in this latitudinal zone and it is much nearer to Mt. Pinatubo. Especially, there is advantage to link up these two stations on studying the transportation mechanism in the stratosphere. In this paper, we present the results of lidar observations at Tsukuba and Naha by lidar systems with Nd:YAG laser.

Magnetotelluric imaging of the resurgent caldera on the island of Ischia (southern Italy): inferences for its structure and activity

NASA Astrophysics Data System (ADS)

Di Giuseppe, M. G.; Troiano, A.; Carlino, S.

2017-12-01

The island of Ischia (located in the Bay of Naples, Italy) represents a peculiar case of a well-exposed caldera that has experienced a large (>800 m) and rapid resurgence, accompanied by volcanic activity. What drives the resurgence of calderas is a crucial issue to investigate, because this process is associated with potential eruptions and high risk to people living within and around such large active volcanic systems. To improve the knowledge of volcano-tectonic processes affecting the caldera of Ischia, electromagnetic imaging of the structures associated with its resurgence was performed and integrated with available geological information. A magnetotelluric (MT) survey of the island was carried out along two main profiles through the central-western sector, providing an electrical resistivity map to a depth of 3 km. These resistivity cross sections allowed us to identify the presence of a very shallow magmatic intrusion, possibly a laccolith, at a depth of about 1 km, which was responsible for both the resurgence and the volcanic activity. Furthermore, the tectonic structures bordering the resurgent area and the occurrence of a large thermal anomaly in the western sector of the caldera also provided a signature in the resistivity cross sections, with the magma intrusion producing advection of hot fluids with high geothermal gradients (>150 °C km-1) in the southern and western sectors. All of these data are fundamental for the assessment of the island's volcano-tectonic dynamics and their associated hazards. The structure and activity of the island have been controlled by the process of resurgence associated with the arrival of new magma and the progressive intrusion of a laccolith at a shallow depth. The reactivation of such a shallow system may imply imminent eruption which would pose a major volcanic hazard.

Middle Pleistocene volcanic activity dated by red thermoluminescence (RTL) - a case study from Lanzarote (Canary Islands)

NASA Astrophysics Data System (ADS)

von Suchodoletz, H.; Blanchard, H.; Rittner, S.; Radtke, U.; Fuchs, M.; Dietze, M.; Zöller, L.

2009-04-01

On Lanzarote (Canary Islands) soils were baked by Quaternary lava flows. This offers the possibility to date phases of eruptive activity by red thermoluminescence (RTL). We dated soil material baked by two different lava flows originating from the "Las Calderetas de Guatiza" volcanic chain in the northeast of the island by RTL. Furthermore, three samples of Helicidae-mollusk shells overlying one of the lava flows (site Mála) were dated using electron spin resonance (ESR). RTL datings were carried out using quartz grains 63-200 µm from baked material that were originally brought by eolian transport from the nearby Saharan desert. It appears that in spite of a baking temperature < 550°C the RTL-signal was sufficiently annealed and thus dating by RTL was possible. RTL ages of ca. 170 ka show good agreement with each other, however, ESR ages are up to 40 % higher than the corresponding RTL age of the lava flow in Mála. Despite this disagreement these results demonstrate that eruptive activity of the volcanic chain occurred during the Middle Pleistocene rather than during the Early Holocene/Late Pleistocene as supposed based on geomorphologic features. Furthermore, they show that 14C-ages of mollusk shells originating from Mála are underestimating volcanic activity up to a factor of 10, a problem often recorded in arid areas. These results demonstrate the value of luminescence and ESR datings on the semi arid Eastern Canary Islands. The successful dating of lava-baked soils on Lanzarote by RTL thus offers the possibility to further investigate the yet fragmentary Middle and Late Quaternary eruptive history of these islands.

Volcano-ice age link discounted

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kerr, R.A.

1996-05-10

Speculation that huge volcanic eruptions may have caused an immediate `volcanic winter` that devastated early humans and accelerated a slide into the Ice Age. However, further information from the Greenland ice sheet about the Toba errumption on the island of Sumatra 70,000 years ago, seems to indicate that such volcanic actions wasn`t a major climatic catalyst. This article discusses the evidence and further possibilities.

Monitoring the Sumatra volcanic arc with InSAR

NASA Astrophysics Data System (ADS)

Chaussard, E.; Hong, S.; Amelung, F.

2009-12-01

The Sumatra volcanic arc is the result of the subduction of the Indo-Australian plate under the Sunda plate. The arc consists of 35 known volcanic centers, subaerials on the west coast of the Sumatra and Andaman Islands and submarines between these islands. Six active centers are known in the Sumatra volcanic arc. Surface deformation in volcanic areas usually indicates movement of magma or hydrothermal fluids at depth. Here we present a satellite-based Interferometric synthetic aperture radar (InSAR) survey of the Sumatra volcanic arc using ALOS data. Spanning the years 2007 to beginning of 2009, our survey reveals the background level of activity of the 35 volcanoes. We processed data from 40 tracks (24 in descending orbit and 16 in ascending orbit) to cover the whole Sumatra arc. In the first results five of these six known active centers show no sign of activity: Dempo, Kaba, Marapi, Talang and Peuet. The remaining active volcano, Mount Kerinci, has an ambiguous signal. We used pair-wise logic and InSAR time series of the available ALOS data to determine if the observed InSAR signal is caused by ground deformation or by atmospheric delays.

Monitoring diffuse degassing in monogentic volcanic field during magmatic reactivation: the case of El Hierro (Canary Islands, Spain)

NASA Astrophysics Data System (ADS)

Morales-Ocaña, C.; Feldman, R. C.; Pointer, Z. R.; Rodríguez, F.; Asensio-Ramos, M.; Melián, G.; Padrón, E.; Hernández, P. A.; Pérez, N. M.

2017-12-01

El Hierro (278 km2), the younger, smallest and westernmost island of the Canarian archipelago, is a 5-km-high edifice constructed by rapid constructive and destructive processes in 1.12 Ma, with a truncated trihedron shape and three convergent ridges of volcanic cones. It experienced a submarine eruption from 12 October, 2011 and 5 March 2012, off its southern coast that was the first one to be monitored from the beginning in the Canary Islands. As no visible emanations occur at the surface environment of El Hierro, diffuse degassing studies have become a useful geochemical tool to monitor the volcanic activity in this volcanic island. Diffuse CO2 emission has been monitored at El Hierro Island since 1998 in a yearly basis, with much higher frequency in the period 2011-2012. At each survey, about 600 sampling sites were selected to obtain a homogeneous distribution. Measurements of soil CO2 efflux were performed in situ following the accumulation chamber method. During pre-eruptive and eruptive periods, the diffuse CO2 emission released by the whole island experienced significant increases before the onset of the submarine eruption and the most energetic seismic events of the volcanic-seismic unrest (Melián et al., 2014. J. Geophys. Res. Solid Earth, 119, 6976-6991). The soil CO2 efflux values of the 2017 survey ranged from non-detectable to 53.1 g m-2 d-1. Statistical-graphical analysis of the data show two different geochemical populations; background (B) and peak (P) represented by 77.6% and 22.4% of the total data, respectively, with geometric means of 1.8 and 9.2 g m-2 d-1, respectively. Most of the area showed B values while the P values were mainly observed at the interception center of the three convergent ridges and the north of the island. To estimate the diffuse CO2 emission for the 2017 survey, we ran about 100 sGs simulations. The estimated 2017 diffuse CO2 output released to atmosphere by El Hierro was at 1,150 ± 42 t d-1, value higher than the background average of CO2 emission estimated on 422 t d-1 and slightly higher than the background range of 181 t d-1 (-1σ) and 930 t d-1 (+1σ) estimated at El Hierro volcano during the quiescence period 1998-2010 (Melián et al., 2014, JGR). Monitoring the diffuse CO2 emission has proven to be a very effective tool to detect early warning signals of volcanic unrest at El Hierro.

Seafloor geomorphology and geology of the Kingman Reef-Palmyra Atoll region, Central Pacific Ocean

NASA Astrophysics Data System (ADS)

Eakins, Barry; Barth, Ginger; Scheirer, Dan; Mosher, Dave; Armstrong, Andy

2017-04-01

Kingman Reef and Palmyra Atoll are the exposed summits of two seamounts within the Line Islands Volcanic Chain in the Central Pacific Ocean. Both are U.S. Territories, and the Exclusive Economic Zone around the islands was partially surveyed in 1991 with GLORIA sidescan sonar and seismic reflection profiling. New multibeam swath sonar surveys were conducted in 2010, 2015, and 2016 around the islands, in support of U.S. Extended Continental Shelf investigations. Numerous transits through the region by research vessels have collected additional multibeam swath sonar data. We present new, detailed maps of bathymetry, sidescan sonar imagery, geology, and sediment isopachs of the seafloor surrounding the islands, and how these have informed our understanding of the islands' margins. The islands are the last subaerial remnants of a complex, horse-shoe-shaped volcanic platform spanning roughly 200 km in diameter. The elevated platform from which the seamounts arise comprises at least 10 individual volcanic centers that have heights exceeding 3000m above the nearby abyssal plains. Gravity modeling suggests that the elevated platform is compensated by thickened crust. Strong carbonate caps and voluminous sediment accumulations flanking the platform indicate that the volcanoes were once shallow-water or emergent systems. These systems produced vast quantities of carbonate sediment that were shed to a deep interior basin to the east of Palmyra Atoll, and to nearby abyssal plains. The identification of mass failures, sediment reworking and bedforms, and channel networks provide evidence for extensive sedimentary processes around these volcanic centers. Analysis of the seamounts atop the elevated platform and in the seamount province to the northwest shows that flat-topped seamounts ("guyots") are principally found at depths shallower than 1300 meters, while peaked seamounts are almost exclusively found at greater depths. This constrains the amount of regional subsidence that has occurred since guyot formation.

Volcanism at Rifts.

ERIC Educational Resources Information Center

White, Robert S.; McKenzie, Dan P.

1989-01-01

Investigates the nature of catastrophic volcanism and the rifting process. Describes two kinds of evidence: quantitative descriptions of rock melting and a wide range of observations. Discusses examples of continent growth in the North Atlantic, India and the Seychelles islands, and the South Atlantic. (YP)

210 Study on the Sensitization Rates to Airbone Pollen and Mold in Children

PubMed Central

Park, So Hyun; Lim, Dae Hyun; Son, Byong Kwan; Kim, Jeong Hee; Oh, In Bo; Kim, Yang Ho; Lee, Keun Hwa; Kim, Su Young; Hong, Sung Chul

2012-01-01

Background Aeroallergens are important causative factors for allergies such as allergic rhinitis, allergic conjunctivitis and asthma. Previous studies for the sensitization rate to aeroallergen were based on those patient groups who had visited the pediatric allergy clinic. Compared to that, we inquired into the sensitization rates based on general school aged student population group in the city of Incheon, Jeju and Ulsan. Methods With informed consent, skin prick tests were performed on 5,094 students between April and June, 2010. Common 21 aeroallergens were used on elementary school student while middle and high school students were tested upon 28 allergens. 28 allergen list as positive control (1%Histamine), negative control (Normal saline), D.pteronyssinus, D.farinae, Citrus red mite, pollen (Birch, Alder, Oak, Japanese cedar, Pine, Willow, Elm, Maple, Bermuda grass, Timothy grass, Rye grass, Orchard, Meadow grass, Vernal grass, Mugwort, Japanese hop, Fat hen, Ragweed, Plantain), mold (Penicillatum, Asperugillus, Cladosporium, Alternaria) and 21 kinds of allergens that were used on elementary school students count as same as above except Elm, Rye grass, Orchard, Meadow grass, Vernal grass, Fat hen, Plantain. Results If arranged in rates of higher sensitization were D. pteronyssinus (25.79%), D. farinae (18.66%), Mugwort (6.20%), Willow (4.07%) in Incheon, D. pteronyssinus (33.35%), D. farinae (24.78%), Japanese cedar (15.36%), Alternaria (7.33%) in Jeju, D. pteronyssinus (32.79%), D. farinae (30.27%), Alder (10.13%), Birch (8.68%) in Ulsan respectively. The sensitization rate of Japanese cedar was statistically significantly higher in Jeju. The sensitization rate of Birch, Alder, Oak was higher in Ulsan. The sensitization rate of Ragweed was 0.99% in Incheon, 1.07% in Jeju, 0.81% in Ulsan. The sensitization rate of Mugwort in Incheon was 6.20% which was meaningfully higher in comparison to 2.32% of Jeju and 2.73% of Ulsan. The sensitization rate of Alternaria was 2.98% in Incheon, 7.33% in Jeju, 2.39% in Ulsan and as we can see it was higher in Jeju. The sensitization rate of Dermatophagoides had an increasing tendency with increasing age. Conclusions Changes in exposure rate to allergens with increasing ages brings changes in sensitization rates. And because there are changes in sensitization rates due to different regional living environmental status and discrepancies of surrounding biologic species, this would leave us there lies needs for subsequent studies and nationwide researches.

Canary Island Archipelago

NASA Technical Reports Server (NTRS)

1989-01-01

This nearly vertical view of the Canary Archipelago (28.5N, 16.5W) shows five of the seven islands: Grand Canary, Tenerife, Gomera, Hierro and La Palma. The largest island in view is Tenerife. Island cloud wakes evident in this photo are the result of southerly winds giving rise to cloud banks on the lee side especially on Tenerife which has the highest volcanic peaks. Island water wakes and internal waves are also evident but not as apparent.

A 3D joint interpretation of magnetotelluric and seismic tomographic models: The case of the volcanic island of Tenerife

NASA Astrophysics Data System (ADS)

García-Yeguas, Araceli; Ledo, Juanjo; Piña-Varas, Perla; Prudencio, Janire; Queralt, Pilar; Marcuello, Alex; Ibañez, Jesús M.; Benjumea, Beatriz; Sánchez-Alzola, Alberto; Pérez, Nemesio

2017-12-01

In this work we have done a 3D joint interpretation of magnetotelluric and seismic tomography models. Previously we have described different techniques to infer the inner structure of the Earth. We have focused on volcanic regions, specifically on Tenerife Island volcano (Canary Islands, Spain). In this area, magnetotelluric and seismic tomography studies have been done separately. The novelty of the present work is the combination of both techniques in Tenerife Island. For this aim we have applied Fuzzy Clusters Method at different depths obtaining several clusters or classes. From the results, a geothermal system has been inferred below Teide volcano, in the center of Tenerife Island. An edifice hydrothermally altered and full of fluids is situated below Teide, ending at 600 m below sea level. From this depth the resistivity and VP values increase downwards. We also observe a clay cap structure, a typical feature in geothermal systems related with low resistivity and low VP values.

View of Oahu, Hawaii from STS-67 Endeavour

NASA Technical Reports Server (NTRS)

1995-01-01

This is an unusually full view of the island of Oahu in the Hawaiian chain of islands. Oahu's volcanic origins are hinted at by the volcanic crater at Diamond Head, clearly visible on the southern shore. The city of Honolulu stretches from Diamond Head to the inlet of Pearl Harbor. Honolulu's large international airport can be seen off the shore. The dense forestation of the highlands is visible below the cloud cover, and waves can be seen breaking along the northern shore where famous surfing beaches, such as Pipeline, are found.

Gravitational, erosional and depositional processes on volcanic ocean islands: Insights from the submarine morphology of Madeira Archipelago

NASA Astrophysics Data System (ADS)

Quartau, Rui; Ramalho, Ricardo S.; Madeira, José; Santos, Rúben; Rodrigues, Aurora; Roque, Cristina; Carrara, Gabriela; Brum da Silveira, António

2018-01-01

The submarine flanks of volcanic ocean islands are shaped by a variety of physical processes. Whilst volcanic constructional processes are relatively well understood, the gravitational, erosional and depositional processes that lead to the establishment of large submarine tributary systems are still poorly comprehended. Until recently, few studies have offered a comprehensive source-to-sink approach, linking subaerial morphology with near-shore shelf, slope and far-field abyssal features. In particular, few studies have addressed how different aspects of the subaerial part of the system (island height, climate, volcanic activity, wave regime, etc.) may influence submarine flank morphologies. We use multibeam bathymetric and backscatter mosaics of an entire archipelago - Madeira - to investigate the development of their submarine flanks. Crucially, this dataset extends from the nearshore to the deep sea, allowing a solid correlation between submarine morphologies with the physical and geological setting of the islands. In this study we also established a comparison with other island settings, which allowed us to further explore the wider implications of the observations. The submarine flanks of the Madeira Archipelago are deeply dissected by large landslides, most of which also affected the subaerial edifices. Below the shelf break, landslide chutes extend downslope forming poorly defined depositional lobes. Around the islands, a large tributary system composed of gullies and channels has formed where no significant rocky/ridge outcrops are present. In Madeira Island these were likely generated by turbidity currents that originated as hyperpycnal flows, whilst on Porto Santo and Desertas their origin is attributed to storm-induced offshore sediment transport. At the lower part of the flanks (-3000 to -4300 m), where seafloor gradients decrease to 0.5°-3°, several scour and sediment wave fields are present, with the former normally occurring upslope of the latter. Sediment waves are often associated with the depositional lobes of the landslides but also occur offshore poorly-developed tributary systems. Sediment wave fields and scours are mostly absent in areas where the tributary systems are well developed and/or are dominated by rocky outcrops. This suggests that scours and sediment wave fields are probably generated by turbidity currents, which experience hydraulic jumps where seafloor gradients are significantly reduced and where the currents become unconfined. The largest scours were found in areas without upslope channel systems and where wave fields are absent, and are also interpreted to have formed from unconfined turbidity currents. Our observations show that tributary systems are better developed in taller and rainy islands such as Madeira. On low-lying and dry islands such as Porto Santo and Desertas, tributary systems are poorly developed with unconfined turbidite currents favouring the development of scours and sediment wave fields. These observations provide a more comprehensive understanding of which factors control the gravitational, erosional, and depositional features shaping the submarine flanks of volcanic ocean islands.

Spatial and temporal variations of diffuse CO2 degassing at El Hierro volcanic system: Relation to the 2011-2012 submarine eruption

NASA Astrophysics Data System (ADS)

Melián, Gladys; Hernández, Pedro A.; Padrón, Eleazar; Pérez, Nemesio M.; Barrancos, José; Padilla, Germán.; Dionis, Samara; Rodríguez, Fátima; Calvo, David; Nolasco, Dacil

2014-09-01

We report herein the results of extensive diffuse CO2 emission surveys performed on El Hierro Island in the period 1998-2012. More than 17,000 measurements of the diffuse CO2 efflux were carried out, most of them during the volcanic unrest period that started in July 2011. Two significant precursory signals based on geochemical and geodetical studies suggest that a magma intrusion processes might have started before 2011 in El Hierro Island. During the preeruptive and eruptive periods, the time series of the diffuse CO2 emission released by the whole island experienced two significant increases. The first started almost 2 weeks before the onset of the submarine eruption, reflecting a clear geochemical anomaly in CO2 emission, most likely due to increasing release of deep-seated magmatic gases to the surface. The second one, between 24 October and 27 November 2011, started before the most energetic seismic events of the volcanic-seismic unrest. The data presented here demonstrate that combined continuous monitoring studies and discrete surveys of diffuse CO2 emission provide important information to optimize the early warning system in volcano monitoring programs and to monitor the evolution of an ongoing volcanic eruption, even though it is a submarine eruption.

Vertical Motions of Oceanic Volcanoes

NASA Astrophysics Data System (ADS)

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

2006-12-01

Oceanic volcanoes offer abundant evidence of changes in their elevations through time. Their large-scale motions begin with a period of rapid subsidence lasting hundreds of thousands of years caused by isostatic compensation of the added mass of the volcano on the ocean lithosphere. The response is within thousands of years and lasts as long as the active volcano keeps adding mass on the ocean floor. Downward flexure caused by volcanic loading creates troughs around the growing volcanoes that eventually fill with sediment. Seismic surveys show that the overall depression of the old ocean floor beneath Hawaiian volcanoes such as Mauna Loa is about 10 km. This gross subsidence means that the drowned shorelines only record a small part of the total subsidence the islands experienced. In Hawaii, this history is recorded by long-term tide-gauge data, the depth in drill holes of subaerial lava flows and soil horizons, former shorelines presently located below sea level. Offshore Hawaii, a series of at least 7 drowned reefs and terraces record subsidence of about 1325 m during the last half million years. Older sequences of drowned reefs and terraces define the early rapid phase of subsidence of Maui, Molokai, Lanai, Oahu, Kauai, and Niihau. Volcanic islands, such as Maui, tip down toward the next younger volcano as it begins rapid growth and subsidence. Such tipping results in drowned reefs on Haleakala as deep as 2400 m where they are tipped towards Hawaii. Flat-topped volcanoes on submarine rift zones also record this tipping towards the next younger volcano. This early rapid subsidence phase is followed by a period of slow subsidence lasting for millions of years caused by thermal contraction of the aging ocean lithosphere beneath the volcano. The well-known evolution along the Hawaiian chain from high to low volcanic island, to coral island, and to guyot is due to this process. This history of rapid and then slow subsidence is interrupted by a period of minor uplift lasting a few hundred thousand years as the island migrates over a broad flexural arch related to isostatic compensation of a nearby active volcano. The arch is located about 190±30 km away from the center of volcanic activity and is also related to the rejuvenated volcanic stage on the islands. Reefs on Oahu that are uplifted several tens of m above sea level are the primary evidence for uplift as the islands over-ride the flexural arch. At the other end of the movement spectrum, both in terms of magnitude and length of response, are the rapid uplift and subsidence that occurs as magma is accumulated within or erupted from active submarine volcanoes. These changes are measured in days to years and are of cm to m variation; they are measured using leveling surveys, tiltmeters, EDM and GPS above sea level and pressure gauges and tiltmeters below sea level. Other acoustic techniques to measure such vertical movement are under development. Elsewhere, evidence for subsidence of volcanoes is also widespread, ranging from shallow water carbonates on drowned Cretaceous guyots, to mapped shoreline features, to the presence of subaerially-erupted (degassed) lavas on now submerged volcanoes. Evidence for uplift is more limited, but includes makatea islands with uplifted coral reefs surrounding low volcanic islands. These are formed due to flexural uplift associated with isostatic loading of nearby islands or seamounts. In sum, oceanic volcanoes display a long history of subsidence, rapid at first and then slow, sometimes punctuated by brief periods of uplift due to lithospheric loading by subsequently formed nearby volcanoes.

Magnetic imaging of the feeding system of oceanic volcanic islands: El Hierro (Canary Islands)

NASA Astrophysics Data System (ADS)

Blanco-Montenegro, Isabel; Nicolosi, Iacopo; Pignatelli, Alessandro; Chiappini, Massimo

2008-04-01

El Hierro is the youngest of the Canary Islands, a volcanic archipelago in the central Atlantic, near the African coast. The subaerial part of the island shows the characteristic shape of three convergent ridges that has been interpreted as a triple-arm rift system. At least four giant landslides formed wide, horseshoe embayments that separate these ridges. Recent studies based on high-resolution bathymetry, however, showed that the submarine rift structure is much more complex. We analysed an aeromagnetic anomaly data set acquired in 1993 by the Spanish National Geographic Institute in order to obtain a structural model of the island from a magnetic point of view. A digital elevation model of the volcanic edifice was divided into a mesh of prismatic cells, each of them with a top corresponding to the topographic height (or bathymetric depth in the marine area) and a bottom at a constant depth of 4000 m below sea level. A three-dimensional (3-D) inversion algorithm and forward modelling along representative profiles provided us with a magnetization distribution containing valuable information about the inner structure of the island. The magnetic model cast new light on the rift structure of El Hierro. In particular, high magnetization values have been mainly interpreted as intrusive complexes on which rift zones are rooted. Their location confirms the hypothesis of a complex rift structure in the marine area. The inverse magnetization that characterizes the NE submarine rift area implies that this part of the volcanic edifice formed during the Matuyama and, therefore, predates the NW submarine rift zone, which is normally magnetized. The N-S rift zone extending southwards from the island seems to be shifted to the west with respect to the bathymetric high in this area. This result suggests that the original rift zone was located in the area where the highest magnetizations presently occur so that the present morphology may reflect the westward collapse of the original ridge. In addition, very low magnetizations characterize the areas affected by giant landslides, indicating that magnetic anomalies can provide important constraints on the distribution of these catastrophic events.

Ambient Seismic Noise Interferometry on the Island of Hawai`i

NASA Astrophysics Data System (ADS)

Ballmer, Silke

Ambient seismic noise interferometry has been successfully applied in a variety of tectonic settings to gain information about the subsurface. As a passive seismic technique, it extracts the coherent part of ambient seismic noise in-between pairs of seismic receivers. Measurements of subtle temporal changes in seismic velocities, and high-resolution tomographic imaging are then possible - two applications of particular interest for volcano monitoring. Promising results from other volcanic settings motivate its application in Hawai'i, with this work being the first to explore its potential. The dataset used for this purpose was recorded by the Hawaiian Volcano Observatory's permanent seismic network on the Island of Hawai'i. It spans 2.5 years from 5/2007 to 12/2009 and covers two distinct sources of volcanic tremor. After applying standard processing for ambient seismic noise interferometry, we find that volcanic tremor strongly affects the extracted noise information not only close to the tremor source, but unexpectedly, throughout the island-wide network. Besides demonstrating how this long-range observability of volcanic tremor can be used to monitor volcanic activity in the absence of a dense seismic array, our results suggest that care must be taken when applying ambient seismic noise interferometry in volcanic settings. In a second step, we thus exclude days that show signs of volcanic tremor, reducing the dataset to three months, and perform ambient seismic noise tomography. The resulting two-dimensional Rayleigh wave group velocity maps for 0.1 - 0.9 Hz compare very well with images from previous travel time tomography, both, for the main volcanic structures at low frequencies as well as for smaller features at mid-to-high frequencies - a remarkable observation for the temporally truncated dataset. These robust results suggest that ambient seismic noise tomography in Hawai'i is suitable 1) to provide a three-dimensional S-wave model for the volcanoes and 2) to be used for repeated time-sensitive tomography, even though volcanic tremor frequently obscures ambient noise analyses. However, the noise characteristics and the wavefield in Hawai'i in general remain to be investigated in more detail in order to measure unbiased temporal velocity changes.

Imaging an Active Volcano Edifice at Tenerife Island, Spain

NASA Astrophysics Data System (ADS)

Ibáñez, Jesús M.; Rietbrock, Andreas; García-Yeguas, Araceli

2008-08-01

An active seismic experiment to study the internal structure of Teide volcano is being carried out on Tenerife, a volcanic island in Spain's Canary Islands archipelago. The main objective of the Tomography at Teide Volcano Spain (TOM-TEIDEVS) experiment, begun in January 2007, is to obtain a three-dimensional (3-D) structural image of Teide volcano using seismic tomography and seismic reflection/refraction imaging techniques. At present, knowledge of the deeper structure of Teide and Tenerife is very limited, with proposed structural models based mainly on sparse geophysical and geological data. The multinational experiment-involving institutes from Spain, the United Kingdom, Italy, Ireland, and Mexico-will generate a unique high-resolution structural image of the active volcano edifice and will further our understanding of volcanic processes.

Biological responses of Crested and Least auklets to volcanic destruction of nesting habitat in the Aleutian Islands, Alaska

USGS Publications Warehouse

Drew, Gary S.; Piatt, John F.; Williams, Jeffrey C.

2018-01-01

Crested Auklets (Aethia cristatella) and Least Auklets (A. pusilla) are crevice-nesting birds that breed in large mixed colonies at relatively few sites in the Aleutian Island archipelago, Bering Sea, Gulf of Alaska, and Sea of Okhotsk. Many of these colonies are located on active volcanic islands. The eruption of Kasatochi volcano, in the central Aleutians, on August 7, 2008, completely buried all crevice-nesting seabird habitat on the island. This provided an opportunity to examine the response of a large, mixed auklet colony to a major geological disturbance. Time-lapse imagery of nesting habitat indicated that both species returned to the largest pre-eruption colony site for several years, but subsequently abandoned it within 5 yr after the eruption. In 2010, a rockfall site in a cove north of the old colony site began to accumulate talus, and groups of auklets were observed using the site in 2011. Use of the new colony appeared to coincide with the abandonment of the old colony site by both species, though surface counts suggested that Least Auklets shifted to the new colony sooner than Crested Auklets. At-sea surveys of seabirds before and after the eruption indicated that both Crested and Least auklets shifted their at-sea distributions from the waters around Kasatochi Island to nearby Koniuji Island. In combination, at-sea counts and colony time-lapse imagery indicated that Crested and Least auklets using Kasatochi responded to the volcanic disturbance and complete loss of nesting habitat at the main colony on Kasatochi with dispersal either to newly created habitat on Kasatochi or to an alternate colony on a nearby island.

Canary Islands

NASA Image and Video Library

2013-12-30

On December 10, 2013 the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Terra satellite flew across the central Atlantic Ocean and captured a true-color image of the Canary Islands. Lying off of the coast of Western Sahara and Morocco, the islands were created by successive submarine volcanic eruptions which raised the ocean floor vertically until some of land rose above sea level. The oldest islands lie in the east and the youngest in the west. From east to west, the major islands seen in this image are: Lanzarote, Fuerteventura, Gran Canaria, Tenerife, La Gomera, La Palmera and El Hierro. While the creation of the islands began in the Late Cretaceous Period (70 – 80 million years ago), active volcanic activity continues. In 2011, a spectacular submarine eruption occurred just off the shore of El Hierro. The volcano became quiet again, but very recently increasing earthquakes and changing height of El Hierro suggested the volcano may again be entering an active eruptive phase. On December 27 the island’s volcano monitoring agency had raised the volcanic eruption risk for El Hierro to “yellow” – a code that means increasing activity but no eruption imminent. That afternoon a magnitude 5.1 earthquake struck offshore at El Hierro. The epicenter was 9 miles (15 km) deep, and it was one of the largest quakes ever recorded at the island. Credit: NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Island of Hawaii, State of Hawaii seen from Skylab

NASA Image and Video Library

1974-01-08

SL4-139-3997 (8 Jan. 1974) --- A vertical view of the Island of Hawaii, State of Hawaii, as photographed from the Skylab space station in Earth orbit by a Skylab 4 crewman. The camera used was a hand-held Hasselblad camera, with SO-368 medium-speed Ektachrome film. This photograph, taken on Jan. 8, 1974, is very useful in studies of volcanic areas. Prominent volcanic features such as the summit caldera on Mauna Loa, the extinct volcano Mauna Kea, the Kilauea caldera, and the pit crater at Halo mau mau within the caldera are easily identified. (Kilauea was undergoing frequent eruption during the mission). Detailed features such as the extent and delineation of historic lava flows on Mauna Loa can be determined and are important parameters in volcanic studies. Photo credit: NASA

The tsunami effects of a volcanic island flank collapse on a semi-enclosed basin: The Pico-São Jorge channel in the Azores archipelago

NASA Astrophysics Data System (ADS)

Quartau, R.; Omira, R.; Ramalho, I.; Baptista, M. A.; Mitchell, N. C.

2015-12-01

The Azores archipelago is a set of nine volcanic islands in the middle of the North Atlantic, close to the triple junction between the North American, Eurasian and African plates. Due to their location, the islands are seismic and volcanically active, which makes them especially vulnerable to these types of hazards that could eventually trigger flank collapses, capable of generating destructive tsunamis. However, solid evidence of large-scale flank collapses has only been found recently in Pico Island (Costa et al., 2014; Quartau et al., 2015). This study investigates for the first time the tsunami effects of a flank collapse of the northeastern subaerial slope of Pico Island that occurred more than 70 ka ago. We first reconstructed the pre-event sub-aerial morphology of the island, and then numerically model the flank failure involving an estimated volume of ~8 km3, its flow toward and under the sea of ~14 km, and the subsequent tsunami generation and propagation. The modelling suggests that the collapse of Pico created a mega-tsunami that significantly impacted the coast of adjacent São Jorge Island only after 7 minutes after generation, with wave run-up reaching a maximum of 50 m at some coastlines. Most of the tsunami energy became trapped in the semi-enclosed basin between Pico and São Jorge Islands, with only relatively little energy escaping to neighboring islands. Acknowledgments The author wishes to acknowledge the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 603839 (Project ASTARTE - Assessment, Strategy and Risk Reduction for Tsunamis in Europe)" for its major contribution for the success of this study. Publication supported by project FCT UID/GEO/50019/2013 - Instituto Dom Luiz. The author also acknowledges Fundação Luso-Americana para o Desenvolvimento for supporting the participation in the meeting.

Single-particle characterization of atmospheric aerosols collected at Gosan, Korea, during the Asian Pacific Regional Aerosol Characterization Experiment field campaign using low-Z (atomic number) particle electron probe X-ray microanalysis.

PubMed

Geng, Hong; Cheng, Fangqin; Ro, Chul-Un

2011-11-01

A quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA), namely low-Z (atomic number) particle EPMA, was used to characterize the chemical compositions of the individual aerosol particles collected at the Gosan supersite, Jeju Island, Korea, as a part of the Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia). On 4-10 April 2001 just before a severe dust storm arrived, seven sets of aerosol samples were obtained by a seven-stage May cascade impactor with a flow rate of 20 L/min. Overall 11,200 particles on stages 1-6 with cutoff diameters of 16, 8, 4, 2, 1, and 0.5 microm, respectively, were examined and classified based on their secondary electron images and X-ray spectra. In general, sea salt particles were the most frequently encountered, followed by mineral dust, organic carbon (OC)-like, (NH4)2SO4/NH4HSO4-containing, elemental carbon (EC)-like, Fe-rich, and K-rich particles. Sea salt and mineral dust particles had a higher relative abundance on stages 1-5, whereas OC-like, (NH4)2SO4/NH4HSO4-containing, Fe-rich, and K-rich particles were relatively abundant on stage 6. The analysis on relative number abundances of various particle types combined with 72-hr backward air mass trajectories indicated that a lot of reacted sea salt and reacted mineral dust (with airborne NOx and SO2 or their acidic products) and OC-like particles were carried by the air masses passing over the Yellow Sea (for sample "10 April") and many NH4HSO4/ (NH4)2SO4-containing particles were carried by the air masses passing over the Sea of Japan and Korea Strait (for samples "4-9 April"). It was concluded that the atmosphere over Jeju Island was influenced by anthropogenic SO2 and NOx, organic compounds, and secondary aerosols when Asian dust was absent.

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

NASA Astrophysics Data System (ADS)

Kalacheva, Elena; Taran, Yuri; Kotenko, Tatiana

2015-04-01

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

Contrasting P-T paths of shield and rejuvenated volcanism at Robinson Crusoe Island, Juan Fernández Ridge, SE Pacific

NASA Astrophysics Data System (ADS)

Reyes, Javier; Lara, Luis E.; Morata, Diego

2017-07-01

A remarkable expression of intraplate volcanism is the occurrence of evolutionary stages with important variations of magmatic processes and products. Plumbing systems and storage conditions seem to be different for shield and rejuvenated volcanism, two classical stages notably preserved in Robinson Crusoe Island, Juan Fernández Ridge in the SE Pacific Ocean. We here present first order geochemical features for rocks from both shield and rejuvenated stages and through geothermobarometry and textural analysis we unravel their contrasting ascent and storage history. The shield stage ( 3.8 Ma) is represented by a 900 m thick sequence of basalt, picrobasalt and picrite lava flows forming subsets according their chemistry and mineralogy: 'differentiated', 'near-primitive' and 'olivine-rich' lavas. Pressure estimates for in equilibrium assemblages are < 3.2 kbar, and temperature ranges around 1321 °C for the 'near-primitive' and 1156-1181 °C for the 'differentiated' groups. Volcanic rocks from the rejuvenated stage ( 0.9 Ma) fill the eroded morphology of the shield pile with basanite and picrite lava flows with two compositional varieties: the primitive 'high-Mg' group that crystallized clinopyroxene at pressures < 3.7 kbar and olivine at temperatures in the range 1316-1354 °C; and the 'low-Mg' group that carries notably zoned crystals formed at a wide range of pressures (0-10.8 kbar) and temperatures (1256-1295 °C). This allows us to infer contrasting patterns of ascent and storage during these archetypical stages in Robinson Crusoe Island, which also controlled volcanic processes on surface and finally shaped the island. We propose the existence of shallow magmatic reservoirs in the shield stage, where the ascending magmas would have been stored and differentiated. On the other hand, rejuvenated magmas experimented rapid ascent with polybaric crystallization and sometimes short-time storage in low-volume reservoirs. Similar conditions have been proposed in other oceanic islands suggesting that shallow reservoirs in the shield stage and deeper crystallization of more alkaline magmas in the rejuvenated stage seems to describe a global pattern.

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

NASA Astrophysics Data System (ADS)

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

2010-12-01

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

End-Cretaceous extinction in Antarctica linked to both Deccan volcanism and meteorite impact via climate change

PubMed Central

Petersen, Sierra V.; Dutton, Andrea; Lohmann, Kyger C.

2016-01-01

The cause of the end-Cretaceous (KPg) mass extinction is still debated due to difficulty separating the influences of two closely timed potential causal events: eruption of the Deccan Traps volcanic province and impact of the Chicxulub meteorite. Here we combine published extinction patterns with a new clumped isotope temperature record from a hiatus-free, expanded KPg boundary section from Seymour Island, Antarctica. We document a 7.8±3.3 °C warming synchronous with the onset of Deccan Traps volcanism and a second, smaller warming at the time of meteorite impact. Local warming may have been amplified due to simultaneous disappearance of continental or sea ice. Intra-shell variability indicates a possible reduction in seasonality after Deccan eruptions began, continuing through the meteorite event. Species extinction at Seymour Island occurred in two pulses that coincide with the two observed warming events, directly linking the end-Cretaceous extinction at this site to both volcanic and meteorite events via climate change. PMID:27377632

Geomorphological features in the southern Canary Island Volcanic Province: The importance of volcanic processes and massive slope instabilities associated with seamounts

NASA Astrophysics Data System (ADS)

Palomino, Desirée; Vázquez, Juan-Tomás; Somoza, Luis; León, Ricardo; López-González, Nieves; Medialdea, Teresa; Fernández-Salas, Luis-Miguel; González, Francisco-Javier; Rengel, Juan Antonio

2016-02-01

The margin of the continental slope of the Volcanic Province of Canary Islands is characterised by seamounts, submarine hills and large landslides. The seabed morphology including detailed morphology of the seamounts and hills was analysed using multibeam bathymetry and backscatter data, and very high resolution seismic profiles. Some of the elevation data are reported here for the first time. The shape and distribution of characteristics features such as volcanic cones, ridges, slides scars, gullies and channels indicate evolutionary differences. Special attention was paid to recent geological processes that influenced the seamounts. We defined various morpho-sedimentary units, which are mainly due to massive slope instability that disrupt the pelagic sedimentary cover. We also studied other processes such as the role of deep bottom currents in determining sediment distribution. The sediments are interpreted as the result of a complex mixture of material derived from a) slope failures on seamounts and submarine hills; and b) slides and slumps on the continental slope.

End-Cretaceous extinction in Antarctica linked to both Deccan volcanism and meteorite impact via climate change.

PubMed

Petersen, Sierra V; Dutton, Andrea; Lohmann, Kyger C

2016-07-05

The cause of the end-Cretaceous (KPg) mass extinction is still debated due to difficulty separating the influences of two closely timed potential causal events: eruption of the Deccan Traps volcanic province and impact of the Chicxulub meteorite. Here we combine published extinction patterns with a new clumped isotope temperature record from a hiatus-free, expanded KPg boundary section from Seymour Island, Antarctica. We document a 7.8±3.3 °C warming synchronous with the onset of Deccan Traps volcanism and a second, smaller warming at the time of meteorite impact. Local warming may have been amplified due to simultaneous disappearance of continental or sea ice. Intra-shell variability indicates a possible reduction in seasonality after Deccan eruptions began, continuing through the meteorite event. Species extinction at Seymour Island occurred in two pulses that coincide with the two observed warming events, directly linking the end-Cretaceous extinction at this site to both volcanic and meteorite events via climate change.

End-Cretaceous extinction in Antarctica linked to both Deccan volcanism and meteorite impact via climate change

NASA Astrophysics Data System (ADS)

Petersen, Sierra V.; Dutton, Andrea; Lohmann, Kyger C.

2016-07-01

The cause of the end-Cretaceous (KPg) mass extinction is still debated due to difficulty separating the influences of two closely timed potential causal events: eruption of the Deccan Traps volcanic province and impact of the Chicxulub meteorite. Here we combine published extinction patterns with a new clumped isotope temperature record from a hiatus-free, expanded KPg boundary section from Seymour Island, Antarctica. We document a 7.8+/-3.3 °C warming synchronous with the onset of Deccan Traps volcanism and a second, smaller warming at the time of meteorite impact. Local warming may have been amplified due to simultaneous disappearance of continental or sea ice. Intra-shell variability indicates a possible reduction in seasonality after Deccan eruptions began, continuing through the meteorite event. Species extinction at Seymour Island occurred in two pulses that coincide with the two observed warming events, directly linking the end-Cretaceous extinction at this site to both volcanic and meteorite events via climate change.

Earth Observations taken by the Expedition 17 Crew

NASA Image and Video Library

2008-09-13

ISS017-E-016161 (13 Sept. 2008) --- Bouvet Island in the South Atlantic Ocean is featured in this image photographed by an Expedition 17 crewmember on the International Space Station. Bouvet Island is known as the most remote island in the world. Antarctica, over 1600 kilometers to the south, is the nearest land mass. Located near the junction between the South American, African, and Antarctic tectonic plates, the island is mostly formed from a shield volcano -- a broad, gently sloping cone formed by thin, fluid lavas -- that is almost entirely covered by glaciers. The prominent Kapp (Cape) Valdivia on the northern coastline is a peninsula formed by a lava dome -- a volcanic feature built by viscous lavas with a high silica content. It is only along the steep cliffs of the coastline that the underlying dark volcanic rock is visible against the white snow and ice blanketing the island. Bouvet Island was discovered by the French Captain Lozier-Bouvet in 1739, and was subsequently visited by representatives of different nations several times during the 19th century. The island was annexed by the Kingdom of Norway in 1927 following a Norwegian expedition's stay on the island. Bouvet is uninhabited, and its extremely harsh environment precludes anything but short-duration stays. Nevertheless, the island supports some flora (such as lichens) and fauna (seabirds and seals). Abundant sea ice surrounds the island in this view (center).

3-D linear inversion of gravity data: method and application to Basse-Terre volcanic island, Guadeloupe, Lesser Antilles

NASA Astrophysics Data System (ADS)

Barnoud, Anne; Coutant, Olivier; Bouligand, Claire; Gunawan, Hendra; Deroussi, Sébastien

2016-04-01

We use a Bayesian formalism combined with a grid node discretization for the linear inversion of gravimetric data in terms of 3-D density distribution. The forward modelling and the inversion method are derived from seismological inversion techniques in order to facilitate joint inversion or interpretation of density and seismic velocity models. The Bayesian formulation introduces covariance matrices on model parameters to regularize the ill-posed problem and reduce the non-uniqueness of the solution. This formalism favours smooth solutions and allows us to specify a spatial correlation length and to perform inversions at multiple scales. We also extract resolution parameters from the resolution matrix to discuss how well our density models are resolved. This method is applied to the inversion of data from the volcanic island of Basse-Terre in Guadeloupe, Lesser Antilles. A series of synthetic tests are performed to investigate advantages and limitations of the methodology in this context. This study results in the first 3-D density models of the island of Basse-Terre for which we identify: (i) a southward decrease of densities parallel to the migration of volcanic activity within the island, (ii) three dense anomalies beneath Petite Plaine Valley, Beaugendre Valley and the Grande-Découverte-Carmichaël-Soufrière Complex that may reflect the trace of former major volcanic feeding systems, (iii) shallow low-density anomalies in the southern part of Basse-Terre, especially around La Soufrière active volcano, Piton de Bouillante edifice and along the western coast, reflecting the presence of hydrothermal systems and fractured and altered rocks.

Geologic map of Mount Gareloi, Gareloi Island, Alaska

USGS Publications Warehouse

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

2012-01-01

As part of an effort to both monitor and study all historically active volcanoes in Alaska, the Alaska Volcano Observatory (AVO) undertook a field program at Mount Gareloi in the summer of 2003. During a month-long period, seismic networks were installed at Mount Gareloi and the neighboring Tanaga volcanic cluster. During this time, we undertook the first geologic field study of the volcano since Robert Coats visited Gareloi Island for four days in 1946. Understanding the geology of this relatively small island is important from a hazards perspective, because Mount Gareloi lies beneath a heavily trafficked air route between North America and Asia and has frequently erupted airborne ash since 1760. At least two landslides from the island have deposited debris on the sea floor; thus, landslide-generated tsunamis are also a potential hazard. Since seismic instruments were installed in 2003, they have detected small but consistent seismic signals from beneath Mount Gareloi's edifice, suggesting an active hydrothermal system. Mount Gareloi is also important from the standpoint of understanding subduction-related volcanism, because it lies in the western portion of the volcanically active arc, where subduction is oblique to the arc front. Understanding the compositional evolution of Mount Gareloi fills a spatial gap in along-arc studies.

An interdisciplinary approach to volcanic risk reduction under conditions of uncertainty: a case study of Tristan da Cunha

NASA Astrophysics Data System (ADS)

Hicks, A.; Barclay, J.; Simmons, P.; Loughlin, S.

2014-07-01

The uncertainty brought about by intermittent volcanic activity is fairly common at volcanoes worldwide. While better knowledge of any one volcano's behavioural characteristics has the potential to reduce this uncertainty, the subsequent reduction of risk from volcanic threats is only realised if that knowledge is pertinent to stakeholders and effectively communicated to inform good decision making. Success requires integration of methods, skills and expertise across disciplinary boundaries. This research project develops and trials a novel interdisciplinary approach to volcanic risk reduction on the remote volcanic island of Tristan da Cunha (South Atlantic). For the first time, volcanological techniques, probabilistic decision support and social scientific methods were integrated in a single study. New data were produced that (1) established no spatio-temporal pattern to recent volcanic activity; (2) quantified the high degree of scientific uncertainty around future eruptive scenarios; (3) analysed the physical vulnerability of the community as a consequence of their geographical isolation and exposure to volcanic hazards; (4) evaluated social and cultural influences on vulnerability and resilience; and (5) evaluated the effectiveness of a scenario planning approach, both as a method for integrating the different strands of the research and as a way of enabling on-island decision makers to take ownership of risk identification and management, and capacity building within their community. The paper provides empirical evidence of the value of an innovative interdisciplinary framework for reducing volcanic risk. It also provides evidence for the strength that comes from integrating social and physical sciences with the development of effective, tailored engagement and communication strategies in volcanic risk reduction.

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

USGS Publications Warehouse

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

2006-01-01

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

Petrology and geochronology of lavas from Ka'ula Volcano: Implications for rejuvenated volcanism of the Hawaiian mantle plume

NASA Astrophysics Data System (ADS)

Garcia, Michael O.; Weis, Dominique; Jicha, Brian R.; Ito, Garrett; Hanano, Diane

2016-07-01

Marine surveying and submersible sampling of Ka'ula Volcano, located 100 km off the axis of the Hawaiian chain, revealed widespread areas of young volcanism. New 40Ar/39Ar and geochemical analyses of the olivine-phyric submarine and subaerial volcanic rocks show that Ka'ula is shrouded with 1.9-0.5 Ma alkalic basalts. The ages and chemistry of these rocks overlap with rejuvenated lavas on nearby, northern Hawaiian Island shields (Ni'ihau, Kaua'i and South Kaua'i Swell). Collectively, these rejuvenated lavas cover a vast area (∼7000 km2), much more extensive than any other area of rejuvenated volcanism worldwide. Ka'ula rejuvenated lavas range widely in alkalinity and incompatible element abundances (e.g., up to 10× P2O5 at a given MgO value) and ratios indicating variable degrees of melting of a heterogeneous source. Heavy REE elements in Ka'ula lavas are pinned at a mantle normalized Yb value of 10 ± 1, reflecting the presence of garnet in the source. Trace element ratios indicate the source also contained phlogopite and an Fe-Ti oxide. The new Ka'ula ages show that rejuvenated volcanism was nearly coeval from ∼0.3 to 0.6 Ma along a 450 km segment of the Hawaiian Islands (from West Maui to north of Ka'ula). The ages and volumes for rejuvenated volcanism are inconsistent with all but one geodynamic melting model proposed to date. This model advocates a significant contribution of pyroxenite to rejuvenated magmas. Analyses of olivine phenocryst compositions suggest a major (33-69%) pyroxenite component in Ka'ula rejuvenated lavas, which correlates positively with radiogenic Pb isotope ratios for Ka'ula. This correlation is also observed in lavas from nearby South Kaua'i lavas, as was reported for Atlantic oceanic islands. The presence of pyroxenite in the source may have extended the duration and volume of Hawaiian rejuvenated volcanism.

Breeding Double-crested Cormorants and Wading Birds on Isla Alcatraz, Sonora, México

Treesearch

Jennifer N. Duberstein; Virginia Jimenez-Serrania; Tad A. Pfister; Kirsten E. Lindquist; Lorayne Meltzer

2005-01-01

Isla Alcatraz is a small volcanic island in the Eastern Midriff Island region of the Gulf of California, approximately 1.4 km from the fishing community of Bahía de Kino, Sonora, México. The island falls under the protection of the Gulf Island Reserve system for wildlife and migratory birds. Isla Alcatraz is home to one of the largest Double-crested Cormorant (

Hydrogeology of the Hawaiian islands

USGS Publications Warehouse

Gingerich, Stephen B.; Oki, Delwyn S.; Cabrera, Maria del Carmen; Lambán, Luis Javier; Valverde, Margarida

2011-01-01

Volcanic-rock aquifers are the most extensive and productive aquifers in the Hawaiian Islands. These aquifers contain different types of groundwater systems depending on the geologic setting in which they occur. The most common groundwater systems include coastal freshwater-lens systems in the dike-free flanks of the volcanoes and dike-impounded systems within the dike-intruded areas of the volcanoes. In some areas, a thick (hundreds of meters) freshwater lens may develop because of the presence of a coastal confining unit, or caprock, that impedes the discharge of groundwater from the volcanic-rock aquifer, or because the permeability of the volcanic rocks forming the aquifer is low. In other areas with low groundwater-recharge rates and that lack a caprock, the freshwater lens may be thin or brackish water may exist immediately below the water table. Dike-impounded groundwater systems commonly have high water levels (hundreds of meters above sea level) and contribute to the base flow of streams where the water table intersects the stream. Recent numerical modeling studies have enhanced the conceptual understanding of groundwater systems in the Hawaiian Islands.

Jurassic-Paleogene intraoceanic magmatic evolution of the Ankara Mélange, north-central Anatolia, Turkey

NASA Astrophysics Data System (ADS)

Sarifakioglu, E.; Dilek, Y.; Sevin, M.

2014-02-01

Oceanic rocks in the Ankara Mélange along the Izmir-Ankara-Erzincan suture zone (IAESZ) in north-central Anatolia include locally coherent ophiolite complexes (∼ 179 Ma and ∼ 80 Ma), seamount or oceanic plateau volcanic units with pelagic and reefal limestones (96.6 ± 1.8 Ma), metamorphic rocks with ages of 256.9 ± 8.0 Ma, 187.4 ± 3.7 Ma, 158.4 ± 4.2 Ma, and 83.5 ± 1.2 Ma indicating northern Tethys during the late Paleozoic through Cretaceous, and subalkaline to alkaline volcanic and plutonic rocks of an island arc origin (∼ 67-63 Ma). All but the arc rocks occur in a shale-graywacke and/or serpentinite matrix, and are deformed by south-vergent thrust faults and folds that developed in the middle to late Eocene due to continental collisions in the region. Ophiolitic volcanic rocks have mid-ocean ridge (MORB) and island arc tholeiite (IAT) affinities showing moderate to significant large ion lithophile elements (LILE) enrichment and depletion in Nb, Hf, Ti, Y and Yb, which indicate the influence of subduction-derived fluids in their melt evolution. Seamount/oceanic plateau basalts show ocean island basalt (OIB) affinities. The arc-related volcanic rocks, lamprophyric dikes and syenodioritic plutons exhibit high-K shoshonitic to medium- to high-K calc-alkaline compositions with strong enrichment in LILE, rare earth elements (REE) and Pb, and initial ɛNd values between +1.3 and +1.7. Subalkaline arc volcanic units occur in the northern part of the mélange, whereas the younger alkaline volcanic rocks and intrusions (lamprophyre dikes and syenodioritic plutons) in the southern part. The late Permian, Early to Late Jurassic, and Late Cretaceous amphibole-epidote schist, epidote-actinolite, epidote-chlorite and epidote-glaucophane schists represent the metamorphic units formed in a subduction channel in the northern Neotethys. The Middle to Upper Triassic neritic limestones spatially associated with the seamount volcanic rocks indicate that the northern Neotethys was an open ocean with its MORB-type oceanic lithosphere by the early Triassic (or earlier). The latest Cretaceous-early Paleocene island arc volcanic, dike and plutonic rocks with subalkaline to alkaline geochemical affinities represent intraoceanic magmatism that developed on and across the subduction-accretion complex above a N-dipping, southward-rolling subducted lithospheric slab within the northern Neotethys. The Ankara Mélange thus exhibits the record of ∼ 120-130 million years of oceanic magmatism in geological history of the northern Neotethys.

Tephro- and chemo-stratigraphy of the Vulcanello Peninsula (Vulcano, Aeolian Islands)

NASA Astrophysics Data System (ADS)

Rosi, M.; Fusillo, R.; di Traglia, F.; Pistolesi, M.; Todman, A.; Menzies, M. A.

2009-12-01

New stratigraphic studies of the Vulcanello Peninsula have been used to better define the small-scale evolution of this young (1000 AD and 325±100 BP) volcanic center and to re-investigate the last 1000 years of volcanic history for the Island of Vulcano (Aeolian Islands, Southern Italy). Vulcanello Peninsula is the northern-most part of the Island of Vulcano. It comprises a shoshonitic lava platform and a volcanic edifice made up of three overlying cones, which are shoshonitic to trachytic in composition. Volcanic activity in this area was coeval with the recent eruptions of the La Fossa Cone, the present-day active center of the island. Our goal is to constrain the recent volcanic development of this mafic volcano and to focus on the historic eruptive activity of the two other recent or active centres in the southern Aeolian Islands, Mt. Pilato (Island of Lipari) and La Fossa Cone. In order to do so, we reconstructed the stratigraphical setting of the proximal deposits of the three Vulcanello cones, through the investigation of 25 outcrops. We analyzed the stratigraphy of the tephra blankets deposited on the lava platform, studying 10 trenches. Our intention is to integrate morphological, textural and chemical data in order to correlate these deposits with the Vulcanello, La Fossa Cone or Mt Pilato. LA-MC-ICPMS (RHUL) analysis of juvenile clasts is underway in order to investigate the evolution of the Vulcanello juvenile clasts. In addition 14C dating is planned on selected organic matter from the volcanostratigraphic sections. Our preliminary data for the Vulcanello proximal deposits suggest that each of the three cones experienced several eruptions, with a wide spectrum of eruptive styles and a diversity of chemistry. The oldest cone (Vulcanello I) is characterised by four different eruptions separated by minor unconformities or reworking material indicative of little or not time breaks in the eruptive cycle. The eruptions shift from Violent Strombolian to Hawaiian in style, testifying to a reduction in fragmentation and dispersal. The second cone (Vulcanello II), contains volcanic deposits from Strombolian eruptions only. The third cone (Vulcanello III), displays a complex evolution with an initial effusive episode of a trachytic lava flow, followed by phreatic explosions, evident as altered fine ash layers. These deposits are interbedded with scoriaceous fall deposits, attesting the occurrence of some mild explosive activity during this eruptive phase. This detailed study of the effusive and explosive products from Vulcanello reveals rapid evolution of Vulcanello during the initial phases (1000 AD to 1200 AD) with voluminous mafic eruptions, both effusive and explosive. A progressive reduction in emitted volume is apparent. The presence of abundant explosive deposits related to phreatic explosions during the Vulcanello III phase, is related to the presence of water, a reduction in magma volume and the presence of intense hydrothermal activity in the latter stage of the evolution of Vulcanello evolution until 1878. This may indicate the presence of a stable shallow thermal anomaly.

Long-term landscape evolution of the Basal Complexes of Fuerteventura and La Gomera Islands, Canary Archipelago

NASA Astrophysics Data System (ADS)

Mansour, Sherif; Glasmacher, Ulrich A.; Albinger, Marie; Stoeckli, Daniel F.

2014-05-01

The Canarias archipelago consists from seven volcanic islands located at the northwestern African margin. Among them only Fuerteventura and La Gomera islands show distinctive wide exposures of the basal complex (BC) that is characteristic with complex geological history. The basal complex was exposed on the western part of Fuerteventura and northwestern sector of La Gomera because of giant landslide(s) which have removed most of the shield stage volcanic rocks (Ancochea et al., 1996; 2006; Stillman, 1999). Generally, landslides are a common feature in the earlier constructive stages of the entire archipelago and many other volcanic islands (McGuire, 1996). Integration of low temperature thermochronological data, and time-Temperature (t-T) numerical modelling have proven to be a powerful tool for reconstructing the thermal and tectonic history, defining and quantifying long-term landscape evolution in variety of geological settings. Therefore, zircon and apatite fission-track techniques and t-T paths modelling were applied to 36 samples representing the main rock units of the BC on both islands. Fuerteventura BC has experienced two very rapid cooling/exhumation events. While, La Gomera BC shows one long-lived very fast cooling/exhumation event. Interestingly, these very rapid cooling/exhumation events are synchronous with these major landslides. There are many reasons for the major landslides on such a volcanic island (see e.g. McGuire, 1996)., But, the most sufficient triggers for these huge mass wasting/landslides events on Fuerteventura and La Gomera are recommended to be the continuous igneous intrusions and dikes which have the potential to decrease the edifice stability, igneous extrusions which add new materials at the surface leading to over-steeping and overloading (McGuire, 1996), and major climatic changes of the Middle Miocene Climatic Optimum (Herold et al., 2011). References Ancochea, E., Brändle, J.L., Cubas, C.R.,Hernán, F.,Huertas, M.J., 1996. Volcanic complexes in the eastern ridge of the Canary Islands: the Miocene activity of the Island of Fuerteventura. Journal of Volcanology and Geothermal Research 70, 183-204. Ancochea, E., Hernán, F., Huertas, M.J., Brändle, J.L., Herrera, R., 2006. A new chronostratigraphical and evolutionary model for La Gomera: implications for the overall evolution of the Canarian Archipelago. Journal of Volcanology and Geothermal Research 157, 271-293. Herold, N., Huber, M., Greenwood, D.R., Müller, R.D., Seton, M., 2011. Early to Middle Miocene monsoon climate in Australia. Geology 39, 3-6. McGuire, W.J., 1996. Volcano instability: a review of contemporary themes. In: McGuire, W.J., Jones, A.P., Neuberg, J. (Eds.), Volcano Instability on the Earth and Terrestrial Planets. Geological Society of London, Special Publication 110, 1-23. Stillman, C.J., 1999. Giant Miocene landslides and the evolution of Fuerteventura, Canary Islands. Journal of Volcanology and Geothermal Research 94, 89-104.

Dental fluorosis linked to degassing of Ambrym volcano, Vanuatu: a novel exposure pathway.

PubMed

Allibone, Rachel; Cronin, Shane J; Charley, Douglas T; Neall, Vince E; Stewart, Robert B; Oppenheimer, Clive

2012-04-01

Ambrym in Vanuatu is a persistently degassing island volcano whose inhabitants harvest rainwater for their potable water needs. The findings from this study indicate that dental fluorosis is prevalent in the population due to fluoride contamination of rainwater by the volcanic plume. A dental survey was undertaken of 835 children aged 6-18 years using the Dean's Index of Fluorosis. Prevalence of dental fluorosis was found to be 96% in the target area of West Ambrym, 71% in North Ambrym, and 61% in Southeast Ambrym. This spatial distribution appears to reflect the prevailing winds and rainfall patterns on the island. Severe cases were predominantly in West Ambrym, the most arid part of the island, and the most commonly affected by the volcanic plume. Over 50 km downwind, on a portion of Malakula Island, the dental fluorosis prevalence was 85%, with 36% prevalence on Tongoa Island, an area rarely affected by volcanic emissions. Drinking water samples from West Ambrym contained fluoride levels from 0.7 to 9.5 ppm F (average 4.2 ppm F, n = 158) with 99% exceeding the recommended concentration of 1.0 ppm F. The pathway of fluoride-enriched rainwater impacting upon human health as identified in this study has not previously been recognised in the aetiology of fluorosis. This is an important consideration for populations in the vicinity of degassing volcanoes, particularly where rainwater comprises the primary potable water supply for humans or animals.

219 The Revised Edition of Korean Calendar for Allergenic Pollens

PubMed Central

Oh, Jae-won; Kim, Joo-Hwa; Kim, Seong-Won; Kang, Im-Joo; Kim, Bong-Seong; Kook, Myung-Hee; Park, Kang-Seo; Lee, Ha-Baik; Kim, Kyu Rang; Choi, Young-Jean

2012-01-01

Background The old version of pollen calendar was used until this year in South Korea. That calendar did not reflect current pollen distribution and concentrations that can be influenced by changes in weather and environment. A new pollen calendar of allergenic pollens was made based on the data on pollen concentrations obtained in 8 regions nationwide between 1997 and 2009 in South Korea. Methods The distribution of pollen grains was assessed every day at 8 areas (Seoul, Guri, Busan, Daegu, Jeonju, Kwangju, Kangneung, and Jeju) nationwide for 12 years between July 1, 1997 and June 30, 2009. Pollen were collected by using Burkard 7-day sampler (Burkard manufacturing Co Ltd, Hertfordshire, UK), and the collected pollens were sent every week to Hanyang Guri Hospital. Then pollens were strained with Calberla's fuchsin staining solution and were identified. The number of pollen grains per m3 was calculated. Results Alder, birch and Japanese cedar started to appear in February. Japanese cedar showed a highest pollen concentration in Jeju. Pine became the highest pollen in May, and the pollen concentrations of oak and birch also became high. Common ragweed appeared in the middle of August and showed the highest pollen concentration in the middles of September. Japanese hop showed a high concentration between the middle of August and the end of September, and mugwort appeared in the middles of August and its concentration increased up until early September. Birch appeared earlier in Kangneung, and pine showed a higher pollen concentration than in the other areas. In Daegu, Oriental thuja, alder and juniper produced a large concentration of pollens. Pine produced a large concentration of pollens between the middle of April and the end of May. Weeds showed higher concentrations in September and mugwort appeared earlier than common ragweed. In Busan where is the southeast city, the time of flowering is relatively early, and alder and Oriental thuja appeared earliest among all areas. In Kwangju, Oriental thuja and hazelnut appeared in early February. In Jeju which is the end of southern island, Japanese cedar showed a higher pollen concentration than the other areas Conclusions New information on pollen distributions and concentrations should be provided for the general publics or allergic patients through the website in order to prevent the occurrence of pollinosis.

2014 volcanic activity in Alaska: Summary of events and response of the Alaska Volcano Observatory

USGS Publications Warehouse

Cameron, Cheryl E.; Dixon, James P.; Neal, Christina A.; Waythomas, Christopher F.; Schaefer, Janet R.; McGimsey, Robert G.

2017-09-07

The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, volcanic unrest or suspected unrest, and seismic events at 18 volcanic centers in Alaska during 2014. The most notable volcanic activity consisted of intermittent ash eruptions from long-active Cleveland and Shishaldin Volcanoes in the Aleutian Islands, and two eruptive episodes at Pavlof Volcano on the Alaska Peninsula. Semisopochnoi and Akutan volcanoes had seismic swarms, both likely the result of magmatic intrusion. The AVO also installed seismometers and infrasound instruments at Mount Cleveland during 2014.

Digital Holography and 3D Imaging: introduction to the joint feature issue in Applied Optics and Journal of the Optical Society of America B.

PubMed

Banerjee, Partha P; Osten, Wolfgang; Picart, Pascal; Cao, Liangcai; Nehmetallah, George

2017-05-01

The OSA Topical Meeting on Digital Holography and 3D Imaging (DH) was held 25-28 July 2016 in Heidelberg, Germany, as part of the Imaging Congress. Feature issues based on the DH meeting series have been released by Applied Optics (AO) since 2007. This year, AO and the Journal of the Optical Society of America B (JOSA B) jointly decided to have one such feature issue in each journal. This feature issue includes 31 papers in AO and 11 in JOSA B, and covers a large range of topics, reflecting the rapidly expanding techniques and applications of digital holography and 3D imaging. The upcoming DH meeting (DH 2017) will be held from 29 May to 1 June in Jeju Island, South Korea.

Anticoagulant activity of marine green and brown algae collected from Jeju Island in Korea.

PubMed

Athukorala, Yasantha; Lee, Ki-Wan; Kim, Se-Kwon; Jeon, You-Jin

2007-07-01

Twenty-two algal species were evaluated for their potential anticoagulant activities. Hot water extracts from selected species, Codium fragile and Sargassum horneri showed high activated partial thromboplastin time (APTT). Ultraflo extract of C. fragile and S. horneri exhibited the most potent anticoagulant activity. Furthermore, in both algal species, active compounds were mainly concentrated in >30kDa faction. The crude polysaccharide fraction (>30kDa; CpoF) of C. fragile composed of approximately 80% carbohydrate and approximately 19% of protein; the crude polysaccharide fraction (>30kDa; CpoF) of S. horneri was composed of 97% of carbohydrate and approximately 2% of protein. Therefore, most probably the active compound, or compounds of the algal species were related to high molecular weight polysaccharide, or a complex form with carbohydrate and protein (proteoglycan).

Christmas Island, Line Island Group, Pacific Ocean

NASA Technical Reports Server (NTRS)

1990-01-01

Christmas Island (2.0N,158.0W), mid central Pacific Ocean, is considered to be the largest atoll in the world, about 25 km in diameter, and is part of the Line Island Group, a northwest-southeast trending chain of volcanic islands on some of the oldest ocean crust in the Pacific. The lagoon is nearly filled with reef growth leaving only a narrow entrance from the sea and large cocoanut groves are found along the fringes of the lagoon.

A new Volcanic managEment Risk Database desIgn (VERDI): Application to El Hierro Island (Canary Islands)

NASA Astrophysics Data System (ADS)

Bartolini, S.; Becerril, L.; Martí, J.

2014-11-01

One of the most important issues in modern volcanology is the assessment of volcanic risk, which will depend - among other factors - on both the quantity and quality of the available data and an optimum storage mechanism. This will require the design of purpose-built databases that take into account data format and availability and afford easy data storage and sharing, and will provide for a more complete risk assessment that combines different analyses but avoids any duplication of information. Data contained in any such database should facilitate spatial and temporal analysis that will (1) produce probabilistic hazard models for future vent opening, (2) simulate volcanic hazards and (3) assess their socio-economic impact. We describe the design of a new spatial database structure, VERDI (Volcanic managEment Risk Database desIgn), which allows different types of data, including geological, volcanological, meteorological, monitoring and socio-economic information, to be manipulated, organized and managed. The root of the question is to ensure that VERDI will serve as a tool for connecting different kinds of data sources, GIS platforms and modeling applications. We present an overview of the database design, its components and the attributes that play an important role in the database model. The potential of the VERDI structure and the possibilities it offers in regard to data organization are here shown through its application on El Hierro (Canary Islands). The VERDI database will provide scientists and decision makers with a useful tool that will assist to conduct volcanic risk assessment and management.

Crustal Deformation in the Eastern Snake River Plain and Yellowstone Plateau Observed by SAR Interferometry

NASA Astrophysics Data System (ADS)

Aly, M. H.; Hughes, S. S.; Rodgers, D. W.; Glenn, N. F.; Thackray, G. D.

2007-12-01

The Snake River Plain-Yellowstone tectono-volcanic province was created when North America migrated over a fixed hotspot in the mantle. Synthetic Aperture Radar Interferometry (InSAR) has been applied in this study to address the recent tectono-volcanic activity in the Eastern Snake River Plain (ESRP) and the southwestern part of Yellowstone Plateau. InSAR results show that crustal deformation across the tectono-volcanic province is episodic. An episode of uplift (about 1 cm/yr) along the ESRP axial volcanic zone, directly southwest of Island Park, has been detected from a time-series of independent differential interferograms created for the 1993-2000 period. Episodes of subsidence (1 cm/yr) during 1997-2000 and uplift (3 cm/yr) during 2004-2006 have been also detected in the active Yellowstone caldera, just northeast of Island Park. The detected interferometric signals indicate that deformation across the axial volcanic zone near Island Park is inversely linked to deformation in the active Yellowstone caldera. One explanation is that the inverse motions reflect a flexure response of the ESRP crust to magma chamber activity beneath the active caldera, although other interpretations are possible. The time-series of differential interferograms shows that no regional deformation has occurred across the central part of ESRP during the periods of observations, but local surface displacements of 1-3 cm magnitude have been detected in the adjacent Basin-Range province. Differential surface movements of varying rates have been also detected along Centennial, Madison, and Hebgen faults between 1993 and 2006.

Is volcanic phenomena of fractal nature?

NASA Astrophysics Data System (ADS)

Quevedo, R.; Lopez, D. A. L.; Alparone, S.; Hernandez Perez, P. A.; Sagiya, T.; Barrancos, J.; Rodriguez-Santana, A. A.; Ramos, A.; Calvari, S.; Perez, N. M.

2016-12-01

A particular resonance waveform pattern has been detected beneath different physical volcano manifestations from recent 2011-2012 period of volcanic unrest at El Hierro Island, Canary Islands, and also from other worldwide volcanoes with different volcanic typology. This mentioned pattern appears to be a fractal time dependent waveform repeated in different time scales (periods of time). This time dependent feature suggests this resonance as a new approach to volcano phenomena for predicting such interesting matters as earthquakes, gas emission, deformation etc. as this fractal signal has been discovered hidden in a wide typical volcanic parameters measurements. It is known that the resonance phenomenon occurring in nature usually denote a structure, symmetry or a subjacent law (Fermi et al., 1952; and later -about enhanced cross-sections symmetry in protons collisions), which, in this particular case, may be indicative of some physical interactions showing a sequence not completely chaotic but cyclic provided with symmetries. The resonance and fractal model mentioned allowed the authors to make predictions in cycles from a few weeks to months. In this work an equation for this waveform has been described and also correlations with volcanic parameters and fractal behavior demonstration have been performed, including also some suggestive possible explanations of this signal origin.

Spatial and temporal variations of diffuse CO_{2} degassing at the Tenerife North-South Rift Zone (NSRZ) volcano (Canary Islands) during the period 2002-2016

NASA Astrophysics Data System (ADS)

Rodríguez, Fátima; McCollum, John J. K.; Orland, Elijah D. M.; Barrancos, José; Padilla, Germán D.; Calvo, David; Amonte, Cecilia; Pérez, Nemesio M.

2017-04-01

Subaerial volcanic activity on Tenerife (2034 km2), the largest island of the Canary archipelago, started 14 My ago and 4 volcanic eruptions have occurred in historical times during the last 300 years. The main volcano-structural and geomorphological features of Tenerife are (i) the central volcanic complex, nowadays formed by Las Cañadas caldera, a volcanic depression measuring 16×9 km that resulted from multiple vertical collapses and partially filled by post-caldera volcanic products and (ii) the triple junction-shaped rift system, formed by numerous aligned monogenetic cones. Up to 297 mafic monogenetic cones have been recognized on Tenerife, and they represent the most common eruptive activity occurring on the island during the last 1 My (Dóniz et al., 2008). The North-South Rift Zone (NSRZ) of Tenerife comprises at least 139 cones. The main structural characteristic of the NSRZ of the island is an apparent absence of a distinct ridge, and a fan shaped distribution of monogenetic cones. Since there are currently no visible gas emissions at the NSRZ, diffuse degassing surveys have become an important geochemical tool for the surveillance of this volcanic system. Five diffuse CO2 degassing surveys have been carried out at NSRZ of Tenerife since 2002, the last one in the summer period of 2016, to evaluate the spatio-temporal variations of CO2 degassing as a volcanic surveillance tool for the NSRZ of Tenerife. At each survey, around 600 sampling sites were selected to cover homogenously the study area (325 km2) using the accumulation chamber method. The diffuse CO2 output ranged from 78 to 707 t/d in the study period, with the highest emission rate measured in 2015. The backgroung emission rate was estimated in 300 t/d. The last results the soil CO2 efflux values ranged from non-detectable up to 24.7 g m-2 d-1. The spatial distribution map, constructed following the sequential Gaussian simulation (sGs) procedure, showed the highest CO2 values as multiple isolated anomalies and did not show a clear relation with the main volcano-structural features of the area. The CO2 output released to the atmosphere in a diffuse way has been estimated at 524 t d-1, which represents a value lower than the previous one (707 t d-1 at summer of 2015) but higher than the background emission rate. These changes in the temporal series confirm the need of periodic diffuse emission surveys in the area as a powerful volcanic surveillance tool in volcanic systems where visible gas emanations are absent. References: Dóniz et al., 2008. J. Volcanol. Geotherm. Res. 173, 185.

Earth Observations taken by Expedition 38 crewmember

NASA Image and Video Library

2013-11-15

ISS038-E-003612 (15 Nov. 2013) --- Islands of the Four Mountains are featured in this image photographed by an Expedition 38 crew member on the International Space Station. Morning sunlight illuminates the southeast-facing slopes of the islands in the photograph. The islands, part of the Aleutian Island chain, are actually the upper slopes of volcanoes rising from the sea floor; Carlisle, Cleveland, Herbert, and Tana. Carlisle and Herbert volcanoes are distinct cones and form separate islands. Cleveland volcano and the Tana volcanic complex form the eastern and western ends respectively of Chuginadak Island; a cloud bank obscures the connecting land mass in this image. Cleveland volcano (peak elevation 1,730 meters above sea level) is one of the most active in the Aleutian chain, with its most recent activity--eruptions and lava flow emplacement--taking place in May of 2013. The northernmost of the islands, Carlisle volcano's (peak elevation 1,620 meters above sea level) last confirmed eruption occurred in 1828, with unconfirmed reports of activity in 1987. Herbert volcano (peak elevation 1,280 meters above sea level) to the southwest displays a classic cone structure breached by a two-kilometer wide summit caldera (upper right), but there are no historical records of volcanic activity. The easternmost peak, Tana (1,170 meters above sea level) is a volcanic complex comprised of two east-west trending volcanoes and associated younger cinder cones; like Herbert volcano, there is no historical record of activity at Tana. A layer of low clouds and/or fog obscures much of the lower elevations of the islands and the sea surface, but the clouds also indicate the general airflow pattern around and through the islands. Directly to the south-southeast of Cleveland volcano a Von Karman vortex "street" is visible. Shadows cast by the morning sun extend from the peaks towards the northwest. The peaks of all of the Four Islands have snow cover; this is distinct from the clouds due to both higher brightness (white versus gray) and specific location on the landscape.

From 3D to 4D seismic tomography at El Hierro Island (Canary Islands, Spain)

NASA Astrophysics Data System (ADS)

Garcia-Yeguas, A.; Koulakov, I.; Jakovlev, A.; Ibáñez, J. M.

2012-04-01

In this work we are going to show the advantages of a dynamic tomography 4D, versus a static image 3D related with a volcanic reactivation and eruption at El Hierro island (Canary Islands, Spain). In this process a high number of earthquakes before and during the eruptive processes have been registered. We are going to show a 3D image as an average of the velocity structure and then the characteristics and physical properties on the medium, including the presence or not of magma. This image will be complemented with its evolution along the time, observing its volcanic dynamic and its influence over the medium properties, including its power as an important element on early warnings protocols. After more than forty years of quiet at Canary Islands, since 1971 with Teneguía eruption at La Palma Island, and more than 200 years on El Hierro Island (The last eruption known at El Hierro took place in 1793, volcán de Lomo Negro), on 19th July on 2011 the Spanish seismic national network, administered by IGN (Instituto Geográfico Nacional), detected an increase of local seismic activity below El Hierro island (Canary Islands, Spain). Since this moment an intense swarm took place, with more than 11000 events, until 11th December, with magnitudes (MLg) from 0.2 to 4.4. In this period two eruptive processes have been declared in front of the South coast of El Hierro island, and they have not finished yet. This seismic swarm has allowed carrying out a 3D seismic tomography, using P and S waves traveltimes. It has showed a low velocity from the North to the South. On the other hand, we have performed a 4D seismic tomography, taking the events occurred at different intervals of time. We can observe the evolution of the negative anomaly along the time, from the North to the South, where has taken place La Restinga submarine eruption. 4D seismic tomography is an innovative and powerful tool able to show the evolution in time of a volcanic process.

The GEOTREF program, a new approach for geothermal investigation

NASA Astrophysics Data System (ADS)

Gérard, Frédéric; Viard, Simon; Garcia, Michel

2017-04-01

The GEOTREF is an R&D program supported by the ADEME, French environmental agency and by the «Investissement d'Avenir », a French government program to found innovative projects. The GEOTREF program aims to develop an integrated analysis of high temperature geothermal reservoir in volcanic context. It is a collaborative program between nine research laboratories and two industrial partners. This program is supported for four years and funds 12 PhDs and 5 post-doctoral grants in various fields: geology, petrography, petrophysics, geophysics, geochemistry, reservoir modelling. The first three years are dedicated to the exploration phases that will lead to the drilling implantation. The project has two main objectives. 1.- Developing innovative and interactive methods and workflows leading to develop prospection and exploration in per volcanic geothermal target. This objective implicates: Optimization of the targeting to mitigate financial risks Adapting oil and gas exploration methods to geothermal energy, especially in peri-volcanic context. 2.- Applying this concept to different prospects in the Caribbean and South America The first target zone is located in Guadeloupe, an island of the active arc of the subduction zone where the Atlantic plate subducts under the Caribbean one. The GEOTREF prospect zone is on the Basse Terre Island in its south part closed to the Soufriere volcano, the active volcanic system. On the same island a geothermal field is exploited in Bouillante, just northward from the GEOTREF targeting area.

An Alternative Georoute: Approaching the Geological Heritage of the SE Part of Milos Island, Greece, via Hiking, Kayaking and Snorkeling

NASA Astrophysics Data System (ADS)

Mavrogonatos, Constantinos; Galanopoulos, Evangelos; Anastasatou, Marianthi; Chadjimpaloglou, Petros; Xydous, Stamatios

2015-04-01

Milos Island is located at the southwest edge of the Cyclades island complex, in the central part of the Aegean archipelago. It is part of the modern South Aegean Volcanic Arc (SAVA), which belongs to the Hellenic subduction zone. This on-going process has resulted in the coexistence of complex geological formations and geodynamic phenomena with sceneries of incomparable natural beauty, in many areas along the arc. Among them, Milos Island is widely known to be a place of astonishing geological and natural wealth, combined with a cultural heritage that dates back to the 8th millennium BC. As geotourism has been rapidly evolving worldwide over the last years, Milos Island was among the first places in Greece that developed a network of geotrails and featured many sites of special interest in terms of geology, volcanology and geoarchaeology. This study proposes an original georoute through land and sea, which aims t? emerge both overland and underwater areas of special interest. It is a novel way to approach the geological and cultural wealth of Milos and focuses on the Aghia Kiriaki area, at the South part of the island. This alternative georoute includes hiking, kayaking and snorkeling, and anyone who follows it, can be guided to a significant number of important geological, volcanic, morphological and geoarcheological sites, in a relatively narrow area, combining athletic activities as well. The proposed georoute has a total length of 3,2 km and an estimated time of completion of about 4 hours. It starts from Aghia Kiriaki area, where visitors can see remnants of one of the island's collapsed calderic domes in a panoramic view towards the East. In the same site, volcanic emanations create impressive scenery, which introduces the participants to aspects of the island's geologic and volcanic history. After about 800 meters of hiking, throughout an area that is dominated by products of phreatic eruptions, Aghia Kiriaki beach is the next stop. Impressive findings of roman pottery can be observed in this site. At this point, hiking alters to kayaking eastwards along the coastline until the third stop, Psarovolada beach. Extended outcrops of the metamorphic basement of the island, along with submerged hot springs are also observed in the area, while not far away from this point, the most daring participants can dive and enjoy the underwater view of the hot springs at the bottom of the sea. The kayaks are used for further 150m until the unique site of the pre-volcanic formations of the island. From this point, georoute continues and visitors have again the opportunity to dive and approach another submerged hot springs location, just by swimming approximately 20 m eastwards. The sea trip ends at Sirocco, which is located in the center of the Paleochori Beach, where visitors can evaluate their experience. The proposed georoute aims to highlight that preservation of the geological heritage fosters values that promote society and geotourism is an excellent motivation of implementation.

Onekotan Island, Kurile Chain, Russia as seen from STS-59

NASA Technical Reports Server (NTRS)

1994-01-01

The narrow end of Onekotan Island is to the north by northeast. This is one of several volcanic islands extending south by southwest between the southern tip of Kamchatka and Japan. The exposure was stopped down to provide extremely fine detail in the totally snow-covered landscape, at the same time making the dark sea look completely black.

Analysis of surface deformation during the eruptive process of El Hierro Island (Canary Islands, Spain): Detection, Evolution and Forecasting.

NASA Astrophysics Data System (ADS)

Berrocoso, M.; Fernandez-Ros, A.; Prates, G.; Martin, M.; Hurtado, R.; Pereda, J.; Garcia, M. J.; Garcia-Cañada, L.; Ortiz, R.; Garcia, A.

2012-04-01

The surface deformation has been an essential parameter for the onset and evolution of the eruptive process of the island of El Hierro (October 2011) as well as for forecasting changes in seismic and volcanic activity during the crisis period. From GNSS-GPS observations the reactivation is early detected by analizing the change in the deformation of the El Hierro Island regional geodynamics. It is found that the surface deformation changes are detected before the occurrence of seismic activity using the station FRON (GRAFCAN). The evolution of the process has been studied by the analysis of time series of topocentric coordinates and the variation of the distance between stations on the island of El Hierro (GRAFCAN station;IGN network; and UCA-CSIC points) and LPAL-IGS station on the island of La Palma. In this work the main methodologies and their results are shown: •The location (and its changes) of the litospheric pressure source obtained by applying the Mogi model. •Kalman filtering technique for high frequency time series, used to make the forecasts issued for volcanic emergency management. •Correlations between deformation of the different GPS stations and their relationship with seismovolcanic settings.

Isotopic composition of reduced and oxidized sulfur in the Canary Islands: implications for the mantle S cycle

NASA Astrophysics Data System (ADS)

Beaudry, P.; Longpre, M. A.; Wing, B. A.; Bui, T. H.; Stix, J.

2017-12-01

The Earth's mantle contains distinct sulfur reservoirs, which can be probed by sulfur isotope analyses of volcanic rocks and gases. We analyzed the isotopic composition of reduced and oxidized sulfur in a diverse range of volcanically derived materials spanning historical volcanism in the Canary Islands. Our sample set consists of subaerial volcanic tephras from three different islands, mantle and sedimentary xenoliths, as well as lava balloon samples from the 2011-2012 submarine El Hierro eruption and associated crystal separates. This large sample set allows us to differentiate between the various processes responsible for sulfur isotope heterogeneity in the Canary archipelago. Our results define an array in triple S isotope space between the compositions of the MORB and seawater sulfate reservoirs. Specifically, the sulfide values are remarkably homogeneous around d34S = -1 ‰ and D33S = -0.01 ‰, while sulfate values peak at d34S = +4 ‰ and D33S = +0.01 ‰. Lava balloons from the El Hierro eruption have highly enriched sulfate d34S values up to +19.3 ‰, reflecting direct interaction between seawater sulfate and the erupting magma. Several sulfate data points from the island of Lanzarote also trend towards more positive d34S up to +13.8 ‰, suggesting interaction with seawater sulfate-enriched lithologies or infiltration of seawater within the magmatic system. On the other hand, the modal values and relative abundances of S2- and S6+ in crystal separates suggest that the Canary Island mantle source has a d34S around +3 ‰, similar to the S-isotopic composition of a peridotite xenolith from Lanzarote. We infer that the S2- and S6+ modes reflect isotopic equilibrium between those species in the magmatic source, which requires 80 % of the sulfide to become oxidized after melting, consistent with measured S speciation. This 34S enrichment of the source could be due to the recycling of hydrothermally-altered oceanic crust, which has been previously suggested for the Canary Island hotspot on the basis of radiogenic isotope characteristics.

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

NASA Astrophysics Data System (ADS)

Elias, T.; Sutton, A. J.

2003-12-01

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

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

PubMed Central

Searl, A; Nicholl, A; Baxter, P

2002-01-01

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

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

PubMed

Searl, A; Nicholl, A; Baxter, P J

2002-08-01

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. 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 PM(10) at fixed sites and also to provide information about exposures to airborne particles associated with selected activities. 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. 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.

Temporal evolution of the Western and Central volcanism of the Aeolian Island Arc (Italy, southern Tyrhhenian Sea)

NASA Astrophysics Data System (ADS)

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

2009-04-01

The Aeolian Archipelago is a volcanic arc in the Southern Tyrrhenian Sea located on the continental margin of the Calabro-Peloritan basement. The Aeolian volcanism occurs in a very complex geodynamic setting linked to the convergence of the European and African plates. For that reason, it is strongly related to regional tectonic lineaments, such as the NW-SE trending Tindari-Letojani (TL) fault. The archipelago consists of seven main islands and several seamounts, which extend around the Marsili Basin, forming a ring-like shape, typical for an island arc. While the seamounts began their activities around 1 Ma , the emerged part is active since about 400 ka. The magmatic products of the whole arc range from typical island arc calc-alkaline (CA) and shoshonitic series, to slightly silica undersaturated potassic alkaline series that are typical of post-collisional settings. Furthermore, the TL fault, along which the Lipari and Vulcano islands are developed, separates a calc-alkaline western sector (Alicudi, Filicudi and Salina islands) from the calc-alkaline to potassic eastern system (Panarea and Stromboli islands) (Peccerillo,1999). This makes of the Aeolian Islands a complex volcanism, with a still controversial origin. In this context, the aim of this work is to constrain the sources and spatio-temporal evolution of this magmatism. We present here new K-Ar ages based on the accurate Cassignol-Gillot technique devoted to the dating of very young rocks (Gillot et Cornette, 1986). These geochronological data were used together with new geochemical data on the same samples. In this study, we attempt to understand the origin of those magmatic events and the relationship between the deep processes and the shallow structures. Our results allow us to define specific periods of very quick geomechemical changes. In the case of Filicudi island, the first rocks range in composition from CA basalts to andesites. This period ended with the edification of the Mte Guardia at 189±4 ka. Then the activity was followed by the construction of the Mte Terrione at 168±4 ka (Gillot 1987), which is matched by High K-Ca andesites emplaced in the Chiumento crater. Therefore, two different magmatic series took place in only 15 ka. The last eruption of Filicudi built the High K-CA dacite lava dome of Mte Montagnola. For Lipari island, the same event is observed around 120-100 ka. In fact, the emitted products evolved from CA andesitic basalts, that emplaced from 256±8 ka (Monte Chirica) to 119±7 ka (Monterosa), to High K-CA andesite after 100 ka. The rocks becam more and more differentiated to achieve High K-CA rhyolite composition during the last 40 ka. At the same time, the Monte Fossa delle Felci of Salina island shows a geochemical "excursion" around 100 ka, characterised by High K-CA dacite. The lower limit of Pollara explosive eruption, that emitted High K-CA rhyolite products, is constrain by a Monte dei Porri lava flow affected by Pollara crater and dated at 13±2 ka. Thus, all these magmatic changes correlate with morphological and volcanic variations. Finally, our first results confirm that the Aeolian arc volcanism is generated in a complex source, with important roles of both arc-type and anorogenic-type compositions. Datings on key samples show that role of different mantle sources change within a very short time span, especially in the central portion of the arc, along the TL lithosheric fault system. This work also gives new geochronological constrains on the duration of magmatic evolution and eruptive phases.

Late Jurassic - Early Cretaceous convergent margins of Northeastern Asia with Northwestern Pacific and Proto-Arctic oceans

NASA Astrophysics Data System (ADS)

Sokolov, Sergey; Luchitskaya, Marina; Tuchkova, Marianna; Moiseev, Artem; Ledneva, Galina

2013-04-01

Continental margin of Northeastern Asia includes many island arc terranes that differ in age and tectonic position. Two convergent margins are reconstructed for Late Jurassic - Early Cretaceous time: Uda-Murgal and Alazeya - Oloy island arc systems. A long tectonic zone composed of Upper Jurassic to Lower Cretaceous volcanic and sedimentary rocks is recognized along the Asian continent margin from the Mongol-Okhotsk thrust-fold belt on the south to the Chukotka Peninsula on the north. This belt represents the Uda-Murgal arc, which was developed along the convergent margin between Northeastern Asia and Northwestern Meso-Pacific. Several segments are identified in this arc based upon the volcanic and sedimentary rock assemblages, their respective compositions and basement structures. The southern and central parts of the Uda-Murgal island arc system were a continental margin belt with heterogeneous basement represented by metamorphic rocks of the Siberian craton, the Verkhoyansk terrigenous complex of Siberian passive margin and the Koni-Taigonos late Paleozoic to early Mesozoic island arc with accreted oceanic terranes. At the present day latitude of the Pekulney and Chukotka segments there was an ensimatic island arc with relicts of the South Anyui oceanic basin in backarc basin. Alazeya-Oloy island arc systems consists of Paleozoic and Mesozoic complexes that belong to the convergent margin between Northeastern Asia and Proto-Artic Ocean. It separated structures of the North American and Siberian continents. The Siberian margin was active whereas the North American margin was passive. The Late Jurassic was characterized by termination of a spreading in the Proto-Arctic Ocean and transformation of the latter into the closing South Anyui turbidite basin. In the beginning the oceanic lithosphere and then the Chukotka microcontinent had been subducted beneath the Alazeya-Oloy volcanic belt

Geochemical Interpretation of Collision Volcanism

NASA Astrophysics Data System (ADS)

Pearce, Julian

2014-05-01

Collision volcanism can be defined as volcanism that takes place during an orogeny from the moment that continental subduction starts to the end of orogenic collapse. Its importance in the Geological Record is greatly underestimated as collision volcanics are easily misinterpreted as being of volcanic arc, extensional or mantle plume origin. There are many types of collision volcanic province: continent-island arc collision (e.g. Banda arc); continent-active margin collision (e.g. Tibet, Turkey-Iran); continent-rear-arc collision (e.g. Bolivia); continent-continent collision (e.g. Tuscany); and island arc-island arc collision (e.g. Taiwan). Superimposed on this variability is the fact that every orogeny is different in detail. Nonetheless, there is a general theme of cyclicity on different time scales. This starts with syn-collision volcanism resulting from the subduction of an ocean-continent transition and continental lithosphere, and continues through post-collision volcanism. The latter can be subdivided into orogenic volcanism, which is related to thickened crust, and post-orogenic, which is related to orogenic collapse. Typically, but not always, collision volcanism is preceded by normal arc volcanism and followed by normal intraplate volcanism. Identification and interpretation of collision volcanism in the Geologic Record is greatly facilitated if a dated stratigraphic sequence is present so that the petrogenic evolution can be traced. In any case, the basis of fingerprinting collision terranes is to use geochemical proxies for mantle and subduction fluxes, slab temperatures, and depths and degrees of melting. For example, syn-collision volcanism is characterized by a high subduction flux relative to mantle flux because of the high input flux of fusible sediment and crust coupled with limited mantle flow, and because of high slab temperatures resulting from the decrease in subduction rate. The resulting geochemical patterns are similar regardless of collision type with extreme LILE and significant HFSE enrichment relative to MORB and with large negative Nb-Ta and Ti anomalies. Post-collision volcanism is usually ascribed to combinations of slab detachment, delamination, and slab roll back (orogenic) and extension (post-orogenic). The magma source is typically conductively-heated, sub-continental mantle lithosphere with composition and depth of melting depending on the nature and evolution of the collision zone in question. Geochemical patterns may be similar to those of syn-collision basalts or of intraplate, continental basalts - or transitional between these. This variability in space and time, though problematic for geochemical fingerprinting, can give clues to the polarity and development of the collision zone, for example by highlighting the distribution of subduction-modified mantle lithosphere and hence of pre-collision subduction zones. One characteristic common to this setting is a high crustal input resulting from the presence of a hot, thick 'crustal chemical filter' which is evident on geochemical projections that highlight AFC-type processes. Using this, and other, geochemical features it is possible to develop methodologies to at least partly see through the complexity of collision terranes.

Constraints on the structure of the crust and lithosphere beneath the Azores Islands from teleseismic receiver functions

NASA Astrophysics Data System (ADS)

Spieker, Kathrin; Rondenay, Stéphane; Ramalho, Ricardo; Thomas, Christine; Helffrich, George

2018-05-01

The Azores Archipelago is located near the Mid-Atlantic Ridge (MAR) and consists of nine islands, resting on both sides of the ridge. Various methods including seismic reflection, gravity and passive seismic imaging have previously been used to investigate the crustal thickness beneath the islands. They have yielded thickness estimates that range between roughly 10 and 30 km, but until now models of the more fine-scale crustal structure have been lacking. Pending questions include the thickness of the volcanic edifice beneath the islands and whether crustal intrusions or even underplating can be observed beneath any island. In this study, we use data from nine seismic stations located on the Azores Islands to investigate the crustal structure with teleseismic P-wave receiver functions. Our results indicate that the base of the volcanic edifice is located approximately 1 to 4 km depth beneath the different islands and that the crust-mantle boundary has an average depth of ˜17 km. There is strong evidence for magmatic underplating beneath the island of São Jorge, and indications that the underplating is also present beneath São Miguel and possibly Santa Maria. Additionally, the seismological lithosphere-asthenosphere boundary, defined as a seismic velocity drop in the uppermost mantle, seems to deepen with increasing distance from the MAR. It has a depth of ˜45 km beneath the islands close to the MAR, compared to depths >70 km beneath the more distal islands.

New chronological and geochemical constraints on the genesis and geological evolution of Ponza and Palmarola Volcanic Islands (Tyrrhenian Sea, Italy)

NASA Astrophysics Data System (ADS)

Cadoux, Anita; Pinti, Daniele L.; Aznar, Cyril; Chiesa, Sergio; Gillot, Pierre-Yves

2005-04-01

A new geochronological and geochemical study of the volcanic rocks of the Ponza and Palmarola Islands, Pontine Archipelago, has been carried out. This archipelago is located along the boundary between the Italian continental shelf and the opening Tyrrhenian basin. It is a key area to study volcanism related to the opening of the Tyrrhenian Sea. Ponza is the oldest felsic magmatic manifestation in the central Tyrrhenian area. Previous studies suggested that Ponza volcanic activity began before 5 Ma. Twenty-five new K-Ar ages constrain the volcanic activity (rhyolitic hyaloclastites and dykes) to the last 4.2 Ma, with two episodes of quiescence between 3.7 and 3.2 Ma and between 2.9 and 1.0 Ma. A new volcanic episode dated at 3.2-2.9 Ma has been identified on the central and southern Ponza, with emplacement of pyroclastic units. At 1.0 Ma, a trachytic episode ended the volcanic activity. The near island of Palmarola exhibits rhyolitic hyaloclastites and domes dated between 1.6 and 1.5 Ma, indicating that the island was entirely built during the Early Pleistocene in a short span of time of ca. 120 ka. Although only 6-8 km apart, the two islands display significantly different geochemical signatures. Ponza rhyolites show major and trace element compositions representative of orogenic magmas of subduction/collision zones: high-K calc-alkaline and metaluminous rhyolites (Agpaitic Index [AI] and Alumina Saturation Index [ASI] <1), high LILE/HFSE (Th/Ta=16-21) and LREE/HFSE ratios (La/Nb>3), and Nb-Ta negative anomalies. In Palmarola, the orogenic character is also present, but much less marked than in Ponza: rhyolites have a peralkaline character (AI>1), lower LILE/HFSE (Th/Ta=11-15), low LREE/HFSE ratios (La/Nb=1-2) close to those of anorogenic lavas, and the Nb-Ta negative anomalies are almost absent. Y/Nb ratios indicate different magmatic sources, one similar to island-arc or active continental margin basalts for Ponza rhyolites, and the others probably involving an OIB type component for Palmarola rhyolites and Ponza trachytes. Palmarola volcanics represent a transitional magmatism: although a preserved collisional geochemical imprint, they show geochemical features approaching those of anorogenic lavas erupted in a within-plate context. The change of magmatism evidenced in this study can be related to the tectonic evolution of the area. Indeed, Hf, Ta and Rb contents suggest that the oldest Pliocene rhyolites of Ponza would emplace in a syn- to late-collisional setting, while the younger Pleistocene rhyolites of Palmarola would be emplaced in a post-collisional setting in which the orogenic character (Th/Ta) decreases and mantle influence (Nb/Ta) increases. Geochemical modeling strongly suggests that the Palmarola rhyolites represent the waning stages of a subduction-related magmatism. The K-Ar datings allow us to estimate precisely the transition of magmatism to last less than 1.3 Ma. The transitional magmas may be the result of the upwelling of asthenospheric mantle inducing melting of a metasomatized lithospheric mantle and the mixing between these two sources. This upwelling could occur during the extension of the Tyrrhenian basin, caused by the slab retreat and steepening, or during a process of slab break-off starting in the Pliocene.

Trench curvature initiation: Upper plate strain pattern and volcanism Insights from the Lesser Antilles arc, St Barthélemy Island, FWI.

NASA Astrophysics Data System (ADS)

Philippon, M. M.; Legendre, L.; Münch, P.; Léticée, J. L.; Lebrun, J. F.; Maincent, G.; Mazabraud, Y.

2017-12-01

Upper plate deformation pattern reflect the mechanical behavior of subduction zones. In this study, we focus on the consequence of the entrance of a buoyant plateau within the Caribbean subduction zone during Eocene by studying the oldest cropping out rocks of the Lesser Antilles volcanic arc. Based on novel geochronological ages and available bio-stratigraphic data we show that St Barthélemy Island was built during three successive volcanic events over the Mid- Eocene to Oligo-Miocene time span. We show that magmatism is mainly Oligocene, not Eocene. Moreover, we demonstrate that tholeitic and calc-alkaline magmatism co-existed all along the arc activity. And ultimately we evidence a westward migration of the volcanism at the island scale. Furthermore, We demonstrate that during 21 Ma, the built of theses volcanoes, the stress regime evolves from pure to radial extension with a sub-horizontal σ3 showing N30° mean trend. To conclude, our novel results invalidate the chronological, geochemical and spatial evolution of the island arc magmatism formerly proposed in the early eighties. Indeed, arc magmatism in St Barthélemy was mainly related to the West-dipping Lesser Antilles subduction zone and not to the South-dipping Greater Antilles subduction and upper plate deformation evolution observed at local scale reflects large scale mechanical behavior of the Lesser Antilles subduction zone. A two steps restoration of the regional deformation shows that the switch from pure parallel to the trench extension to radial extension within the Caribbean upper plate reflects trench curvature that followed the entrance of the Bahamas bank in the Greater Antilles subduction zone and its collision.

Geochemistry and petrology of basaltic rocks from the Marshall Islands

USGS Publications Warehouse

Davis, Alice S.; Schwab, William C.; Haggerty, Janet A.

1986-01-01

A variety of volcanic rock was recovered from the flanks of seamounts, guyots, atolls, and islands in the Ratak chain of the Marshall Islands on the U.S. Geological Survey cruise L9-84-CP. The main objective of this cruise was to study the distribution and composition of ferromanganese oxide crusts. Preliminary results of managanese crust composition are reported by Schwab et al. (1985) and detailed studies are in preparation (Schwab et al., 1986). A total of seven seafloor edifices were studied using 12 khz, 3.5 khz and air gun seismic reflection, chain dredge and box corer. Bathymetry and ship track lines are presented by Schwab and Bailey (1985). Of the seven edifices surveyed two support atolls (Majuro and Taongi) and one is a tiny island (Jemo). Dredge locations and water depths are given in Table 1 and dredge locations are shown in Figure 1. Due to equipment failures depths of dredge hauls were limited to shallow depth for all except the first two sites occupied. Recovery consisted mostly of young, poorly-consolidated limestone of fore-reef slope deposit and minor volcanogenic breccia and loose talus. The breccia and pieces of talus are thickly encrusted with ferromanganese oxide, whereas the young limestone is only coated by a thin layer. Four of the seven sites surveyed yielded volcanic rock. The volcanic rock, volumetrically a minor part of each dredge haul, consists mostly of lapilli and cobble-size clasts in a calcareous matrix or as loose talus. Most clasts show evidence of reworking, being sub- to well rounded, sometimes with a thin ferromanganese crust of their own. This paper reports preliminary findings on the petrology and geochemistry of volcanic rock recovered.

Origin, transport, and emplacement of an exotic island-arc terrane exposed in eastern Kamchatka, Russia

USGS Publications Warehouse

Geist, Eric L.; Vallier, Tracy L.; Scholl, David W.

1994-01-01

The regional stratigraphy of eastern Kamchatka includes an exotic, Early-Late Cretaceous ophiolite and Late Cretaceous island-arc volcanic sequence. Integrating the existing geologic and geophysical data, we examine the origin, transport, emplacement, and postemplacement deformation of the island-arc terrane, which is named the Olyutorsky island arc. Results from several paleomagnetic studies consistently indicate that the island-arc terrane originated >1000 km to the south of where it is presently exposed. Although the formative paleolatitudes of the island-arc rocks approximately correspond to the location of the Izanagi-Farallon subduction zone, the age of the volcanic rocks postdates the cessation of Izanagi-Farallon convergence, thus indicating that an unnamed plate or back-arc basin existed in the northwest Pacific during Late Cretaceous time. We examine two possible models for northward transport of the island-arc terrane to Kamchatka: (1) infra-oceanic transport with the Pacific or Kula plates and (2) coastwise translation of the island-arc terrane after accretion to the Eurasian margin far to the south of Kamchatka. For both models, the dominant Eocene and Miocene deformation ages observed in eastern Kamchatka are used as two possible age limits for the cessation of northward transport. Although the observed paleolatitudes from paleomagnetic data correspond best with the infra-oceanic transport model, the provenance of the Paleogene "transport" stratigraphy indicates a near-shore sediment supply. Our preferred interpretation is that the island-arc terrane (1) accreted onto the Eurasian margin concurrent with cessation of island-arc volcanism (Maastrichtian-Danian) and (2) underwent northward coastwise translation along a major strike-slip fault zone ending by middle-late Eocene time (43-50 Ma). It is unclear whether the ophiolite was exposed during arc-continent collision or whether the ophiolite was obducted onto the island arc prior to collision. A consequence of either infra-oceanic transport or coastwise translation is that an open corridor between the western terminus of the Aleutian Arc and Kamchatka must have existed until middle to late Eocene time. Spreading within the Komandorsky Basin, subduction of sea-mounts, and collision of the Aleutian Arc with Kamchatka are proposed to have instigated the second Miocene phase of deformation, which uplifted and reexposed the island-arc terrane.

New Insights on Submarine Volcanism in the Western Galapagos Archipelago from High Resolution Sonar and Magnetic Surveys

NASA Astrophysics Data System (ADS)

Glass, J. B.; Fornari, D. J.; Tivey, M. A.; Hall, H. F.; Cougan, A. A.; Berkenbosch, H. A.; Holmes, M. L.; White, S. M.; de La Torre, G.

2006-12-01

We combine high-resolution MR-1 sidescan sonar and EM-300 bathymetric data collected on four cruises (AHA-Nemo2 in 2000 (R/V Melville), DRIFT4 in 2001 (R/V Revelle), TN188 and TN189 in January 2006 (R/V Thompson) to study volcanic platform-building processes on the submarine flanks of Fernandina, Isabela, Roca Redonda and Santiago volcanoes, in the western Galapagos. Three primary volcanic provinces were identified including: rift zones (16, ranging from 5 to 20 km in length), small submarine volcanic cones (<3 km in diameter and several 100 m high) and deep (>3000 m), long (>10 km), large-area submarine lava flows. Lengths of the Galapagos rift zones are comparable to western Canary Island rift zones, but significantly shorter than Hawaiian submarine rift zones, possibly reflecting lower magma supply. A surface-towed magnetic survey was conducted over the NW Fernandina rift on TN189 and Fourier inversions were performed to correct for topographic effects. Calculated magnetization was highest (up to +32 A/m) over the shallow southwest flank of the rift, coinciding with cone fields and suggesting most recent volcanism has focused at this portion of the rift. Small submarine volcanic cones with various morphologies (e.g., pointed, cratered and occasionally breached) are common in the submarine western Galapagos both on rift zones and on the island flanks where no rifts are present, such as the northern flank of Santiago Island. Preliminary study of these cones suggests that their morphologies and depth of occurrence may reflect a combination of petrogenetic and eruption processes. Deep, long large-area lava flow fields in regions of low bathymetric relief have been previously identified as a common seafloor feature in the western Galapagos by Geist et al. [in press], and new EM300 data show that a number of the deep lava flows originate from small cones along the mid-lower portion of the NW submarine rift of Fernandina. Our high-resolution sonar data suggest that submarine volcanism in the western Galapagos occurs both on and off rift zones. Volcanic cones are prevalent on the Galapagos volcanic platform and long lava flows dominate in the deep regions west and north of the platform, possibly representing the foundation upon which the next Galapagos volcanoes will be constructed.

Distributions of fossil fuel originated CO2 in five metropolitan areas of Korea (Seoul, Busan, Daegu, Daejeon, and Gwangju) according to the Δ14C in ginkgo leaves

NASA Astrophysics Data System (ADS)

Park, J. H.; Hong, W.; Park, G.; Sung, K. S.; Lee, K. H.; Kim, Y. E.; Kim, J. K.; Choi, H. W.; Kim, G. D.; Woo, H. J.

2013-01-01

We collected a batch of ginkgo (Ginkgo biloba Linnaeus) leaf samples at five metropolitan areas of Korea (Seoul, Busan, Daegu, Daejeon, and Gwangju) in 2009 to obtain the regional distribution of fossil fuel originated CO2 (fossil fuel CO2) in the atmosphere. Regions assumed to be free of fossil fuel CO2 were also selected, namely Mt. Chiak, Mt. Kyeryong, Mt. Jiri, Anmyeon Island, and Jeju Island and ginkgo leaf samples were collected in those areas during the same period. The Δ14C values of the samples were measured using Accelerator Mass Spectrometry (AMS) and the fossil fuel CO2 ratios in the atmosphere were obtained in the five metropolitan areas. The average ratio of fossil fuel CO2 in Seoul was higher than that in the other four cities. The leaves from the Sajik Tunnel in Seoul recorded the highest FFCTC (fossil fuel CO2 over total CO2 in atmosphere), 13.9 ± 0.5%, as the air flow of the surrounding neighborhood of the Sajik Tunnel was blocked.

Whole-genome analyses of Korean native and Holstein cattle breeds by massively parallel sequencing.

PubMed

Choi, Jung-Woo; Liao, Xiaoping; Stothard, Paul; Chung, Won-Hyong; Jeon, Heoyn-Jeong; Miller, Stephen P; Choi, So-Young; Lee, Jeong-Koo; Yang, Bokyoung; Lee, Kyung-Tai; Han, Kwang-Jin; Kim, Hyeong-Cheol; Jeong, Dongkee; Oh, Jae-Don; Kim, Namshin; Kim, Tae-Hun; Lee, Hak-Kyo; Lee, Sung-Jin

2014-01-01

A main goal of cattle genomics is to identify DNA differences that account for variations in economically important traits. In this study, we performed whole-genome analyses of three important cattle breeds in Korea--Hanwoo, Jeju Heugu, and Korean Holstein--using the Illumina HiSeq 2000 sequencing platform. We achieved 25.5-, 29.6-, and 29.5-fold coverage of the Hanwoo, Jeju Heugu, and Korean Holstein genomes, respectively, and identified a total of 10.4 million single nucleotide polymorphisms (SNPs), of which 54.12% were found to be novel. We also detected 1,063,267 insertions-deletions (InDels) across the genomes (78.92% novel). Annotations of the datasets identified a total of 31,503 nonsynonymous SNPs and 859 frameshift InDels that could affect phenotypic variations in traits of interest. Furthermore, genome-wide copy number variation regions (CNVRs) were detected by comparing the Hanwoo, Jeju Heugu, and previously published Chikso genomes against that of Korean Holstein. A total of 992, 284, and 1881 CNVRs, respectively, were detected throughout the genome. Moreover, 53, 65, 45, and 82 putative regions of homozygosity (ROH) were identified in Hanwoo, Jeju Heugu, Chikso, and Korean Holstein respectively. The results of this study provide a valuable foundation for further investigations to dissect the molecular mechanisms underlying variation in economically important traits in cattle and to develop genetic markers for use in cattle breeding.

Whole-Genome Analyses of Korean Native and Holstein Cattle Breeds by Massively Parallel Sequencing

PubMed Central

Stothard, Paul; Chung, Won-Hyong; Jeon, Heoyn-Jeong; Miller, Stephen P.; Choi, So-Young; Lee, Jeong-Koo; Yang, Bokyoung; Lee, Kyung-Tai; Han, Kwang-Jin; Kim, Hyeong-Cheol; Jeong, Dongkee; Oh, Jae-Don; Kim, Namshin; Kim, Tae-Hun; Lee, Hak-Kyo; Lee, Sung-Jin

2014-01-01

A main goal of cattle genomics is to identify DNA differences that account for variations in economically important traits. In this study, we performed whole-genome analyses of three important cattle breeds in Korea—Hanwoo, Jeju Heugu, and Korean Holstein—using the Illumina HiSeq 2000 sequencing platform. We achieved 25.5-, 29.6-, and 29.5-fold coverage of the Hanwoo, Jeju Heugu, and Korean Holstein genomes, respectively, and identified a total of 10.4 million single nucleotide polymorphisms (SNPs), of which 54.12% were found to be novel. We also detected 1,063,267 insertions–deletions (InDels) across the genomes (78.92% novel). Annotations of the datasets identified a total of 31,503 nonsynonymous SNPs and 859 frameshift InDels that could affect phenotypic variations in traits of interest. Furthermore, genome-wide copy number variation regions (CNVRs) were detected by comparing the Hanwoo, Jeju Heugu, and previously published Chikso genomes against that of Korean Holstein. A total of 992, 284, and 1881 CNVRs, respectively, were detected throughout the genome. Moreover, 53, 65, 45, and 82 putative regions of homozygosity (ROH) were identified in Hanwoo, Jeju Heugu, Chikso, and Korean Holstein respectively. The results of this study provide a valuable foundation for further investigations to dissect the molecular mechanisms underlying variation in economically important traits in cattle and to develop genetic markers for use in cattle breeding. PMID:24992012

Psychological aspects in a volcanic crisis: El Hierro Island eruption (October, 2011).

NASA Astrophysics Data System (ADS)

Lopez, P.; Llinares, A.; Garcia, A.; Marrero, J. M.; Ortiz, R.

2012-04-01

The recent eruption on the El Hierro Island (Canary Islands, Spain) has shown that Psychology plays an important role in the emergence management of a natural phenomenon. However, Psychology continues to have no social coverage it deserves in the mitigation of the effects before, during and after the occurrence of a natural phenomenon. Keep in mind that an unresolved psychological problem involves an individual and collective mismatch may become unrecoverable. The population of El Hierro has been under a state of alert since July 2011, when seismic activity begins, until the occurrence of submarine eruption in October 2011 that is held for more than three months. During this period the inhabitants of the small island have gone through different emotional states ranging from confusion to disappointment. A volcanic eruption occurs not unexpectedly, allowing to have a time of preparation / action before the disaster. From the psychological point of view people from El Hierro Island have responded to different stages of the same natural process. Although the island of El Hierro is of volcanic origin, the population has no historical memory since the last eruption occurred in 1793. Therefore, the educational system does not adequately address the formation in volcanic risk. As a result people feel embarrassment when the seismovolcanic crisis begins, although no earthquakes felt. As an intermediate stage, when the earthquakes are felt by the population, scientists and operational Emergency Plan care to inform and prepare actions in case of a possible eruption. The population feel safe despite the concerns expressed by not knowing where, how and when the eruption will occur. Once started the submarine eruption, taking into account that all the actions (evacuation, relocation, etc.) have worked well and that both their basic needs and security are covered there are new states of mind. These new emotional states ranging from disenchantment with the phenomenology of the phenomenon (submarine and no subaerial eruption) to exhaustion for the duration of the phenomenon. In addition, there are parallel factors directly involved in the population: the media, everyday problems, economic losses, political, and so on. In this paper, after a detailed description of the situation experienced in El Hierro Island, are possible alternative psychological action to different behavioral manifestations of the population before the occurrence of a natural phenomenon that, at the moment, has not had serious consequences.

Early signs of geodynamic activity before the 2011-2012 El Hierro eruption

NASA Astrophysics Data System (ADS)

López, Carmen; García-Cañada, Laura; Martí, Joan; Domínguez Cerdeña, Itahiza

2017-02-01

The potential relation between mantle plume dynamics, regional tectonics and eruptive activity in the Canary Islands has not been studied yet through the analysis of long-time series of geophysical observational data. The existence of highly reliable seismic and geodetic data has enabled us to study from 1996 to 2014 the geodynamic evolution of the North Atlantic Azores-Gibraltar region (including the NW African margin) and its relationship with recent volcanic activity in El Hierro (Canary Islands). We compiled a new and unified regional seismic catalog and used long time-series of digital 3D surface displacements recorded by permanent GPS stations in the region. A joint regional- and local-scale analysis based on these data enabled us to identify signs of anomalous tectonic activity from 2003 onwards, whose intensity increased in 2007 and finally accelerated three months before the onset of the volcanic eruption on El Hierro in October 2011. Activity included the occurrence of regional extension and an uplift process affecting the southern Iberian Peninsula, NW Africa, and the Canary Islands. We interpret these observations as early signs of the geodynamic activity, which led to El Hierro eruption and the subsequent episodes of magma intrusion. Results point to the significant contribution of the mantle plume dynamics (i.e. external forces) in this renewed volcanic activity in the Canary Islands and emphasize the role of mantle dynamics in controlling regional tectonics.

Early signs of geodynamic activity before the 2011-2012 El Hierro eruption

NASA Astrophysics Data System (ADS)

López, Carmen; García-Cañada, Laura; Martí, Joan; Domínguez Cerdeña, Itahiza

2017-04-01

The potential relation between mantle plume dynamics, regional tectonics and eruptive activity in the Canary Islands has not been studied yet through the analysis of long-time series of geophysical observational data. The existence of highly reliable seismic and GNSS data has enabled us to study from 1996 to 2014 the geodynamic evolution of the North Atlantic Azores-Gibraltar region and its relationship with recent volcanic activity in El Hierro (Canary Islands, Spain). We compiled a new and unified regional seismic catalog and used long time-series of surface displacements recorded by permanent GNSS stations in the region. A regional- and local-scale analysis based on these data enabled us to identify signs of anomalous tectonic activity from 2003 onwards, whose intensity increased in 2007 and finally accelerated three months before the onset of the volcanic eruption on El Hierro in October 2011. This activity includes a regional extension and an uplift process that affects the southern Iberian Peninsula, NW Africa, and the Canary Islands. We interpret these observations as early signs of the geodynamic activity, which led to El Hierro eruption and the subsequent episodes of magma intrusion. Results point to the significant contribution of the mantle plume dynamics (i.e. external forces) in this renewed volcanic activity in the Canary Islands and emphasize the role of mantle dynamics in controlling regional tectonics.

Seismic tomography of Basse-Terre volcanic island, Guadeloupe, Lesser Antilles, using earthquake travel times and noise correlations

NASA Astrophysics Data System (ADS)

Barnoud, Anne; Coutant, Olivier; Bouligand, Claire; Massin, Frédérick; Stehly, Laurent

2015-04-01

We image the volcanic island of Basse-Terre, Guadeloupe, Lesser Antilles, using both earthquake travel times and noise correlations. (1) A new earthquake catalog was recently compiled for the Lesser Antilles by the CDSA/OVSG/IPGP (Massin et al., EGU General Assembly 2014) and allows us to perform classical travel time tomography to obtain smooth 3D body wave velocity models. The geometrical configuration of the volcanic arc controls the resolution of the model in our zone of interest. (2) Surface wave tomography using noise correlations was successfully applied to volcanoes (Brenguier et al., Geophys. Res. Lett. 2007). We use seismic noise recorded at 16 broad-band stations and 9 short-period stations from Basse-Terre over a period of six years (2007-2012). For each station pair, we extract a dispersion curve from the noise correlation to get surface wave velocity models. The inversion of the dispersion curves produces a 3D S-wave velocity model of the island. The spatial distribution of seismic stations accross the island is highly heterogeneous, leading to higher resolution near the dome of the Soufrière of Guadeloupe volcano. Resulting velocity models are compared with densities obtained by 3D inversion of gravimetric data (Barnoud et al., AGU Fall Meeting 2013). Further work should include simultaneous inversion of seismic and gravimetric datasets to overcome resolution limitations.

Earth Observations taken by Expedition 30 crewmember

NASA Image and Video Library

2012-03-06

ISS030-E-122047 (6 March 2012) --- Pagan Island, Northern Marianas is featured in this image photographed by an Expedition 30 crew member on the International Space Station. A steam plume flows south from the peak of Pagan Island’s northernmost volcano in this photograph. Pagan is part of the Commonwealth of the Northern Marianas, an island chain of volcanoes that form the margin between the Pacific Ocean (to the east) and the Philippine Sea (to the west). Pagan is made up of two stratovolcanoes separated by an isthmus, and is one of the more volcanically active islands. The last eruption was in 2010, but the island was completely evacuated in 1981 when a large eruption forced the small Micronesian community to flee. According to NASA scientists, the islands themselves mark the tectonic boundary where the old, cold Pacific plate is subducted beneath the younger, less dense Philippine Sea crust at the Marianas Trench. The subduction results in substantial volcanic activity on the upper plate, forming the island arc of the Marianas. Considered to be one of the type examples for an oceanic subduction zone, the Marianas Trench includes the deepest spot in Earth’s oceans (more than 10,000 meters). The foreshortened appearance of the island is due to the viewing angle and distance from the space station, which was located over the Pacific Ocean approximately 480 kilometers to the southeast of Pagan Island when the image was taken.

Earth Observation taken by Expedition 33 crew

NASA Image and Video Library

2012-10-18

ISS033-E-012648 (18 Oct. 2012) --- Isla Santiago is featured in this image photographed by an Expedition 33 crew member on the International Space Station. The island of Santiago is located near the center of the Galapagos Islands off the coast of Ecuador. The Galapagos Islands are situated near the equator, and were formed from volcanism related to a large mantle plume (also known as a hot spot). This hot spot is very close to the tectonic boundary between the Galapagos Ridge, a plate boundary that is also an oceanic spreading center, and the Nazca and Cocos plates. This combination of mantle plumes and tectonic plate movements produces a unique geological environment, including underwater ridges of volcanoes that influence the water circulation around the Galapagos. All of these aspects contribute to the geology and biology of the Galapagos. Isla Santiago itself is formed from a shield volcano also called Santiago. This type of volcanic structure is recognized by low, flat summits surrounded by extensive flow fields of lava; the lava is not very viscous, so it can flow for great distances from the source vents. Several dark lava flow fields are visible in this photograph, the largest along the eastern, western, and southern coastlines. The small Isla Rabida to the south of Isla Santiago is the peak of another, mostly submerged shield volcano. In addition to the lava flows, other volcanic features known as tuff cones are visible on the eastern and western sides of the island. These cones are formed from the rapid interaction of hot flowing lava and water. The water underneath the lava flow flashes to steam explosively, and this both fragments the lava and rapidly cools it, leading to the formation of cones of glassy, relatively fine-grained volcanic material. The most recent volcanic activity on Isla Santiago occurred during 1904 – 1906. The summit ridge of the Santiago shield volcano is located in the northwestern part of the island (center). Also at center is a large but isolated region of green vegetation primarily located on the south-facing slope below the summit ridge. This image was taken during the dry, or garua, season that lasts from June to November. The season is dominated by cooler air transported by the Southeast Trade winds and cooler waters from the Humboldt and Cromwell currents. The combination of cool air and water results in rain falling only in the island highlands, with south- and east-facing slopes receiving the most precipitation. Despite the favorable topographic location, the yellow green color of the vegetation may indicate water (or other) stress.

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

NASA Astrophysics Data System (ADS)

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

2003-12-01

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

Evaluating Topographic Effects on Ground Deformation: Insights from Finite Element Modeling

NASA Astrophysics Data System (ADS)

Ronchin, Erika; Geyer, Adelina; Martí, Joan

2015-07-01

Ground deformation has been demonstrated to be one of the most common signals of volcanic unrest. Although volcanoes are commonly associated with significant topographic relief, most analytical models assume the Earth's surface as flat. However, it has been confirmed that this approximation can lead to important misinterpretations of the recorded surface deformation data. Here we perform a systematic and quantitative analysis of how topography may influence ground deformation signals generated by a spherical pressure source embedded in an elastic homogeneous media and how these variations correlate with the different topographic parameters characterizing the terrain form (e.g., slope, aspect, curvature). For this, we bring together the results presented in previous published papers and complement them with new axisymmetric and 3D finite element (FE) model results. First, we study, in a parametric way, the influence of a volcanic edifice centered above the pressure source axis. Second, we carry out new 3D FE models simulating the real topography of three different volcanic areas representative of topographic scenarios common in volcanic regions: Rabaul caldera (Papua New Guinea) and the volcanic islands of Tenerife and El Hierro (Canary Islands). The calculated differences are then correlated with a series of topographic parameters. The final aim is to investigate the artifacts that might arise from the use of half-space models at volcanic areas due to diverse topographic features (e.g., collapse caldera structures, prominent central edifices, large landslide scars).

A decade of global volcanic SO2 emissions measured from space

NASA Astrophysics Data System (ADS)

Carn, S. A.; Fioletov, V. E.; McLinden, C. A.; Li, C.; Krotkov, N. A.

2017-03-01

The global flux of sulfur dioxide (SO2) emitted by passive volcanic degassing is a key parameter that constrains the fluxes of other volcanic gases (including carbon dioxide, CO2) and toxic trace metals (e.g., mercury). It is also a required input for atmospheric chemistry and climate models, since it impacts the tropospheric burden of sulfate aerosol, a major climate-forcing species. Despite its significance, an inventory of passive volcanic degassing is very difficult to produce, due largely to the patchy spatial and temporal coverage of ground-based SO2 measurements. We report here the first volcanic SO2 emissions inventory derived from global, coincident satellite measurements, made by the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite in 2005-2015. The OMI measurements permit estimation of SO2 emissions from over 90 volcanoes, including new constraints on fluxes from Indonesia, Papua New Guinea, the Aleutian Islands, the Kuril Islands and Kamchatka. On average over the past decade, the volcanic SO2 sources consistently detected from space have discharged a total of ~63 kt/day SO2 during passive degassing, or ~23 ± 2 Tg/yr. We find that ~30% of the sources show significant decadal trends in SO2 emissions, with positive trends observed at multiple volcanoes in some regions including Vanuatu, southern Japan, Peru and Chile.

The volcanoes of an oceanic arc from origin to destruction: A case from the northern Luzon Arc

NASA Astrophysics Data System (ADS)

Lai, Yu-Ming; Song, Sheng-Rong

2013-09-01

Volcanoes were created, grew, uplifted, became dormant or extinct, and were accreted as part of continents during continuous arc-continent collision. Volcanic rocks in Eastern Taiwan's Coastal Range (CR) are part of the northern Luzon Arc, an oceanic island arc produced by the subduction of the South China Sea Plate beneath the Philippine Sea Plate. Igneous rocks are characterized by intrusive bodies, lava and pyroclastic flows, and volcaniclastic rocks with minor tephra deposits. Based on volcanic facies associations, Sr-Nd isotopic geochemistry, and the geography of the region, four volcanoes were identified in the CR: Yuemei, Chimei, Chengkuangao, and Tuluanshan. Near-vent facies associations show different degrees of erosion in the volcanic edifices for Chimei, Chengkuangao, and Tuluanshan. Yuemei lacks near-vent rocks, implying that Yuemei's main volcanic body may have been subducted at the Ryukyu Trench with the northward motion of the Philippine Sea Plate. These data suggest a hypothesis for the evolution of volcanism and geomorphology during arc growth and ensuing arc-continent collision in the northern Luzon Arc, which suggests that these volcanoes were formed from the seafloor, emerging as islands during arc volcanism. They then became dormant or extinct during collision, and finally, were uplifted and accreted by additional collision. The oldest volcano, Yuemei, may have already been subducted into the Ryukyu Trench.

A decade of global volcanic SO2 emissions measured from space

PubMed Central

Carn, S. A.; Fioletov, V. E.; McLinden, C. A.; Li, C.; Krotkov, N. A.

2017-01-01

The global flux of sulfur dioxide (SO2) emitted by passive volcanic degassing is a key parameter that constrains the fluxes of other volcanic gases (including carbon dioxide, CO2) and toxic trace metals (e.g., mercury). It is also a required input for atmospheric chemistry and climate models, since it impacts the tropospheric burden of sulfate aerosol, a major climate-forcing species. Despite its significance, an inventory of passive volcanic degassing is very difficult to produce, due largely to the patchy spatial and temporal coverage of ground-based SO2 measurements. We report here the first volcanic SO2 emissions inventory derived from global, coincident satellite measurements, made by the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite in 2005–2015. The OMI measurements permit estimation of SO2 emissions from over 90 volcanoes, including new constraints on fluxes from Indonesia, Papua New Guinea, the Aleutian Islands, the Kuril Islands and Kamchatka. On average over the past decade, the volcanic SO2 sources consistently detected from space have discharged a total of ~63 kt/day SO2 during passive degassing, or ~23 ± 2 Tg/yr. We find that ~30% of the sources show significant decadal trends in SO2 emissions, with positive trends observed at multiple volcanoes in some regions including Vanuatu, southern Japan, Peru and Chile. PMID:28275238

A Decade of Global Volcanic SO2 Emissions Measured from Space

NASA Technical Reports Server (NTRS)

Carn, S. A.; Fioletov, V. E.; McLinden, C. A.; Li, C.; Krotkov, N. A.

2017-01-01

The global flux of sulfur dioxide (SO2) emitted by passive volcanic degassing is a key parameter that constrains the fluxes of other volcanic gases (including carbon dioxide, CO2) and toxic trace metals (e.g., mercury). It is also a required input for atmospheric chemistry and climate models, since it impacts the tropospheric burden of sulfate aerosol, a major climate-forcing species. Despite its significance, an inventory of passive volcanic degassing is very difficult to produce, due largely to the patchy spatial and temporal coverage of ground-based SO2 measurements. We report here the first volcanic SO2 emissions inventory derived from global, coincident satellite measurements, made by the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite in 2005-2015. The OMI measurements permit estimation of SO2 emissions from over 90 volcanoes, including new constraints on fluxes from Indonesia, Papua New Guinea, the Aleutian Islands, the Kuril Islands and Kamchatka. On average over the past decade, the volcanic SO2 sources consistently detected from space have discharged a total of approximately 63 kt/day SO2 during passive degassing, or approximately 23 +/- 2 Tg/yr. We find that approximately 30% of the sources show significant decadal trends in SO2 emissions, with positive trends observed at multiple volcanoes in some regions including Vanuatu, southern Japan, Peru and Chile.

A decade of global volcanic SO2 emissions measured from space.

PubMed

Carn, S A; Fioletov, V E; McLinden, C A; Li, C; Krotkov, N A

2017-03-09

The global flux of sulfur dioxide (SO 2 ) emitted by passive volcanic degassing is a key parameter that constrains the fluxes of other volcanic gases (including carbon dioxide, CO 2 ) and toxic trace metals (e.g., mercury). It is also a required input for atmospheric chemistry and climate models, since it impacts the tropospheric burden of sulfate aerosol, a major climate-forcing species. Despite its significance, an inventory of passive volcanic degassing is very difficult to produce, due largely to the patchy spatial and temporal coverage of ground-based SO 2 measurements. We report here the first volcanic SO 2 emissions inventory derived from global, coincident satellite measurements, made by the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite in 2005-2015. The OMI measurements permit estimation of SO 2 emissions from over 90 volcanoes, including new constraints on fluxes from Indonesia, Papua New Guinea, the Aleutian Islands, the Kuril Islands and Kamchatka. On average over the past decade, the volcanic SO 2 sources consistently detected from space have discharged a total of ~63 kt/day SO 2 during passive degassing, or ~23 ± 2 Tg/yr. We find that ~30% of the sources show significant decadal trends in SO 2 emissions, with positive trends observed at multiple volcanoes in some regions including Vanuatu, southern Japan, Peru and Chile.

Stable isotope compositions and water contents of boninite series volcanic rocks from Chichi-jima, Bonin Islands, Japan

USGS Publications Warehouse

Dobson, P.F.; O'Neil, J.R.

1987-01-01

Measurements of stable isotope compositions and water contents of boninite series volcanic rocks from the island of Chichi-jima, Bonin Islands, Japan, confirm that a large amount (1.6-2.4 wt.%) of primary water was present in these unusual magmas. An enrichment of 0.6??? in 18O during differentiation is explained by crystallization of 18O-depleted mafic phases. Silicic glasses have elevated ??18O values and relatively low ??D values indicating that they were modified by low-temperature alteration and hydration processes. Mafic glasses, on the other hand, have for the most part retained their primary isotopic signatures since Eocene time. Primary ??D values of -53 for boninite glasses are higher than those of MORB and suggest that the water was derived from subducted oceanic lithosphere. ?? 1987.

Mauna Iki and the Kaju Desert: Kilauea Volcano, Hawaii

NASA Technical Reports Server (NTRS)

Cruikshank, D. P.

1974-01-01

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

Geology and origin of the late Proterozoic Darb Zubaydah ophiolite, Kingdom of Saudi Arabia

USGS Publications Warehouse

Quick, J.E.

1990-01-01

The Darb Zubaydah ophiolite, north-central Arabian Shield, preserves a largely intact section consisting of ultramafic rocks, gabbro, diabase, granodiorite, and interbedded volcanic and sedimentary rocks. Formation of these rocks within or near an island arc is indicated by the absence of pelagic sediments and the abundance of pillow basalt, turbiditic sediments, lahar deposits, and basaltic to rhyolitic tuff. The oldest extrusive rocks formed in a young, relatively unevolved island arc or in a back-arc basin sufficiently close to an arc to receive calc-alkaline lava flows and coarse-grained, arc-derived detritus. Overlying turbidites and lahar deposits of the Kaffan sandstone point to the initiation of a rifting event. High-Ti basalts, which erupted above the Kaffan sandstone, and related diabase are interpreted to be magmatic products of incipient intra-arc rifting. Renewed arc volcanism produced calc-alkaline volcanic rocks that interfingered with the high-Ti basalt and later dominated the section as the volcanic apron of the arc prograded basinward. Extrusion of voluminous calc-alkaline tuff may have been contemporaneous with intrusion of granodiorite and gravity-driven landsliding. -from Author

Phylogeography of the Asian lesser white-toothed shrew, Crocidura shantungensis, in East Asia: role of the Korean Peninsula as refugium for small mammals.

PubMed

Lee, Seo-Jin; Lee, Mu-Yeong; Lin, Liang-Kong; Lin, Y Kirk; Li, Yuchun; Shin, E-Hyun; Han, Sang-Hoon; Min, Mi-Sook; Lee, Hang; Kim, Kyung Seok

2018-04-01

Many peninsulas in the temperate zone played an important role as refugia of various flora and fauna, and the southern Korean Peninsula also served as a refugium for many small mammals in East Asia during the Pleistocene. The Asian lesser white-toothed shrew, Crocidura shantungensis, is a widely distributed species in East Asia, and is an appropriate model organism for exploring the role of the Korean Peninsula as a refugium of small mammals. Here, we investigated phylogenetic relationships and genetic diversity based on the entire sequence of the mitochondrial cytochrome b gene (1140 bp). A Bayesian tree for 98 haplotypes detected in 228 C. shantungensis specimens from East Asia revealed the presence of three major groups with at least 5 subgroups. Most haplotypes were distributed according to their geographic proximity. Pairwise F ST 's and analysis of molecular variance (AMOVA) revealed a high degree of genetic differentiation and variance among regions as well as among populations within region, implying little gene flow among local populations. Genetic evidence from South Korean islands, Jeju-do Island of South Korea, and Taiwan leads us to reject the hypothesis of recent population expansion. We observed unique island-type genetic characteristics consistent with geographic isolation and resultant genetic drift. Phylogeographic inference, together with estimates of genetic differentiation and diversity, suggest that the southern most part the Korean Peninsula, including offshore islands, played an important role as a refugium for C. shantungensis during the Pleistocene. However, the presence of several refugia on the mainland of northeast Asia is also proposed.

Alfred E. Bergeat (1866-1924): a distinguished volcanologist and ore deposit researching scientist at the mining academies of Freiberg (Saxony) and Clausthal (Harz mountains) in Germany

NASA Astrophysics Data System (ADS)

Pfaffl, Fritz A.

2010-06-01

Alfred E. Bergeat, originated from a family, who produced gold-glance in a factory (porcelain painting), studied mineralogy and geology at the University of Munich from 1886 to 1892. Due to the results of his habilitation work on the volcanism of island arcs, especially of the Stromboli volcanic island in the Tyrrhenian Sea, he became a recognized volcanologist and specialist in volcanic petrography. He further became an explorer of syngenetic, epigenetic and deuterogenic ore deposits at the mining academies (Bergakademien) of Freiberg (Saxony) and Clausthal (Harz mountains). He described these ore deposits in a two-volume manual (1904-1906) which was summarized again in 1913. After his early death in 1924, the two manuals “Die Vulkane” (1925) and “Vulkankunde” (1927) were posthumously published by his colleague and friend Karl Sapper (1866-1945).

Recent volcanism and mitochondrial DNA structuring in the lizard Gallotia atlantica from the island of Lanzarote.

PubMed

Bloor, P; Kemp, S J; Brown, R P

2008-02-01

The phylogeography of the lacertid lizard Gallotia atlantica from the small volcanic island of Lanzarote (Canary Islands) was analysed based on 1075 bp of mitochondrial DNA (mtDNA) sequence (partial cytochrome b and ND2) for 157 individuals from 27 sites (including three sites from neighbouring islets). Levels of sequence divergence were generally low, with the most distant haplotypes separated by only 14 mutational steps. MtDNA divergence appears to coincide with formation of the middle Pleistocene lowland that united formerly separate ancient islands to form the current island of Lanzarote, allowing rejection of a two-island model of phylogeographical structure. There was evidence of large-scale population expansion after island unification, consistent with the colonization of new areas. A nested clade phylogeographical analysis (NCPA) revealed significant phylogeographical structuring. Two-step and higher-level clades each had disjunct distributions, being found to the east and west of a common area with a north-south orientation that extends between coasts in the centre-east of the island (El Jable). Other clades were almost entirely restricted to the El Jable region alone. Bayesian Markov chain Monte Carlo analyses were used to separate ongoing gene flow from historical associations. These supported the NCPA by indicating recent (75,000-150,000 years ago) east-west vicariance across the El Jable region. Lava flows covered El Jable and other parts of the central lowland at this time and likely led to population extinctions and temporary dispersal barriers, although present-day evidence suggests some populations would have survived in small refugia. Expansion of the latter appears to explain the presence of a clade located between the eastern and western components of the disjunct clades. Direct relationships between mtDNA lineages and morphology were not found, although one of two morphological forms on the island has a disjunct distribution that is broadly concordant with east-west components of the phylogeographical pattern. This work demonstrates how recent volcanic activity can cause population fragmentation and thus shape genetic diversity on microgeographical scales.

Deception Island, Antarctica, harbors a diverse assemblage of wood decay fungi.

PubMed

Held, Benjamin W; Blanchette, Robert A

2017-02-01

Very little is known about fungal diversity in Antarctica as compared to other biomes and how these important organisms function in this unusual ecosystem. Perhaps one of the most unusual ecosystems is that of Deception Island; an active volcanic island part of the South Shetland Islands of the Antarctic Peninsula. Here we describe the fungal diversity associated with historic wood from structures on the island, which reveals a diverse fungal assemblage of known wood decay fungi as well as the discovery of undescribed species. The major group of wood decay fungi identified were species of Cadophora and as shown in previous studies in other geographic regions of Antarctica, they caused a soft-rot type of decay in the introduced woods. Additionally, unlike other areas of Antarctica that have been studied, filamentous basidiomycetes (Hypochniciellum spp. and Pholiota spp.) were also identified that have different modes of degradation including brown and white rot. Matches of fungal sequences to known species in temperate regions likely introduced on building materials indicates human influences and volcanic activity have greatly impacted fungal diversity. Lahars (mudslides from volcanic activity) have partially buried many of the structures and the buried environment as well as the moist, warm soils provided conditions conducive for fungal growth that are not found in other regions of Antarctica. The diverse assemblage of decay fungi and different forms of wood decomposition add to the difficulty of conserving wooden structures at these important polar heritage sites. Copyright © 2016 British Mycological Society. Published by Elsevier Ltd. All rights reserved.

Excess europium content in Precambrian sedimentary rocks and continental evolution

NASA Technical Reports Server (NTRS)

Jakes, P.; Taylor, S. R.

1974-01-01

It is proposed that the europium excess in Precambrian sedimentary rocks, relative to those of younger age, is derived from volcanic rocks of ancient island arcs, which were the source materials for the sediments. Precambrian sedimentary rocks and present-day volcanic rocks of island arcs have similar REE patterns, total REE abundances, and excess Eu, relative to the North American shale composite. The present upper crustal REE pattern, as exemplified by that of sediments, is depleted in Eu, relative to chondrites. This depletion is considered to be a consequence of development of a granodioritic upper crust by partial melting in the lower crust, which selectively retains europium.

An Overview of Geodetic Volcano Research in the Canary Islands

NASA Astrophysics Data System (ADS)

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

2015-11-01

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

Soil genesis on the island of Bermuda in the Quaternary: the importance of African dust transport and deposition

USGS Publications Warehouse

Muhs, Daniel R.; Budahn, James R.; Prospero, Joseph M.; Skipp, Gary; Herwitz, Stanley R.

2012-01-01

The origin of terra rossa, red or reddish-brown, clay-rich soils overlying high-purity carbonate substrates, has intrigued geologists and pedologists for decades. Terra rossa soils can form from accumulation of insoluble residues during dissolution of the host limestones, addition of volcanic ash, or addition of externally derived, long-range-transported (LRT) aeolian particles. We studied soils and paleosols on high-purity, carbonate aeolianites of Quaternary age on Bermuda, where terra rossa origins have been debated for more than a century. Potential soil parent materials on this island include sand-sized fragments of local volcanic bedrock, the LRT, fine-grained (N/YbN, GdN/YbN that can be distinguished from African dust and lower Mississippi River valley loess. Bermuda soils have Sc-Th-La, Cr-Ta-Nd, and Eu/Eu*, LaN/YbN, GdN/YbN that indicate derivation from a combination of LRT dust from Africa and local volcanic bedrock. Our results indicate that soils on islands in a very broad latitudinal belt of the western Atlantic margin have been influenced by African LRT dust inputs over much of the past –500 ka.

Ecosystem respiration, vegetation development and soil nitrogen in relation to breeding density of seagulls on a pristine volcanic island, Surtsey, Iceland

NASA Astrophysics Data System (ADS)

Sigurdsson, B. D.; Magnusson, B.

2009-08-01

Since its birth in 1963 by volcanic eruption in the North Atlantic Ocean off Iceland, Surtsey has been a unique natural laboratory on how organisms colonize volcanic islands and form ecosystems with contrasting structure and function. In July, 2004, ecosystem respiration rate, soil properties and surface cover of vascular plants were measured on 21 plots distributed among the main plant communities found 40 years after the primary succession started. The plots could be divided into two groups, inside and outside seagull (Larus sp.) colonies found on the island. Vegetation cover of the plots was strongly related to the density of seagull nests within and around them. The occurrence of seagull nests and increased vegetation also coincided with significant increase in ecosystem respiration, soil carbon and nitrogen, and with significantly lower soil pH and soil temperatures. The ecosystem respiration was high inside the gull colonies, similar to the highest fluxes measured in drained wetlands or agricultural fields in Iceland. The most important factor for vegetation succession and ecosystem function on Surtsey seems to be the amount of nitrogen, which was mainly brought in by the seagulls.

Complex population genetic structure in the endemic Canary Island pine revealed using chloroplast microsatellite markers.

PubMed

Gómez, A; González-Martínez, S C; Collada, C; Climent, J; Gil, L

2003-10-01

The Canary archipelago, located on the northwestern Atlantic coast of Africa, is comprised of seven islands aligned from east to west, plus seven minor islets. All the islands were formed by volcanic eruptions and their geological history is well documented providing a historical framework to study colonization events. The Canary Island pine ( Pinus canariensis C. Sm.), nowadays restricted to the westernmost Canary Islands (Gran Canaria, Tenerife, La Gomera, La Palma and El Hierro), is considered an old (Lower Cretaceous) relic from an ancient Mediterranean evolutionary centre. Twenty seven chloroplast haplotypes were found in Canary Island pine but only one of them was common to all populations. The distribution of haplotypic variation in P. canariensis suggested the colonization of western Canary Islands from a single continental source located close to the Mediterranean Basin. Present-day populations of Canary Island pine retain levels of genetic diversity equivalent to those found in Mediterranean continental pine species, Pinus pinaster and Pinus halepensis. A hierarchical analysis of variance (AMOVA) showed high differentiation among populations within islands (approximately 19%) but no differentiation among islands. Simple differentiation models such as isolation by distance or stepping-stone colonization from older to younger islands were rejected based on product-moment correlations between pairwise genetic distances and both geographic distances and population-age divergences. However, the distribution of cpSSR diversity within the islands of Tenerife and Gran Canaria pointed towards the importance of the role played by regional Pliocene and Quaternary volcanic activity and long-distance gene flow in shaping the population genetic structure of the Canary Island pine. Therefore, conservation strategies at the population level are strongly recommended for this species.

Megatsunami Generation From Giant Submarine Landslides on Oceanic Islands: New Insights Gained From the Hawaii Evidence and Modeling

NASA Astrophysics Data System (ADS)

McMurtry, G. M.; Tappin, D. R.; Fryer, G. J.; Watts, P.

2003-12-01

High-elevation marine gravels on the Hawaiian islands of Lanai and Molokai either mark uplifted shorelines or are deposits from massive tsunamis. The subsidence history of those islands has been too ambiguous to differentiate these causes, leading to controversy over the deposit's origins and to confusion over the impacts, or even the existence of megatsunamis generated from giant submarine landslides (GSL) mapped offshore. U-series ages of these deposits that correlate with sealevel high stands have added to the confusion. Landslide tsunami simulations have now advanced to the point where the tsunamigenic potential of GSLs can be affirmed. We show that megatsunamis are a sufficient explanation for the observed pattern of debris height of calcareous marine deposits on the southeast Hawaiian islands. Further, our tsunami simulations, using the Alika GSL as example, can be used to reduce the considerable uncertainty in subsidence history of the different Hawaiian islands. Modeled runups of 800 m occurred directly landward of the Alika 2 slide on west Hawaii and were up to 300 m on west Lanai, in agreement with previous deposit estimates there (Moore & Moore, 1984, 1988). Recently, we rediscovered calcareous marine deposits on Kohala volcano on Hawaii island, where continuous subsidence is well established from its stairway of submerged reefs. On Kohala, we found a marine fossiliferous basalt boulder conglomerate from 1.5 to 61 m above present sea level exposed at the coast and up to 1 km inland. U-series dates of corals from the deposit are approximately the same age, 100 to 120 ka, as the giant Alika 2 landslide from nearby Mauna Loa volcano, directly dated using sediment stratigraphy (McMurtry et al., 1999). The present depth of the 120-ka shoreline implies that the deposit was left by a tsunami whose runup at 6 km inland exceeded 490 m. For the late Pleistocene, large volcanic failures and exposed marine deposits both correlate foremost with sea level high stands, and in particular with the onset of interglacial conditions that are reflected in Hawaii by the apex ages of the low-stand fringing reefs. We show that such large volcanic failures inevitably generate megatsunamis, and we conclude that persistent climate effects during sea level high stands eventually unleash large volcanic failures and megatsunamis amongst the Hawaiian islands and perhaps all volcanically active oceanic islands, with invariable propagation toward the continental coasts.

A new multi-disciplinary model for the assessment and reduction of volcanic risk: the example of the island of Vulcano, Italy

NASA Astrophysics Data System (ADS)

Simicevic, Aleksandra; Bonadonna, Costanza; di Traglia, Federico; Rosi, Mauro

2010-05-01

Volcanic eruptions are accompanied by numerous hazards which pose short- and long-term threats to people and property. Recent experiences have shown that successful responses to hazard events correlate strongly with the degree to which proactive policies of risk reduction are already in place before an eruption occurs. Effective proactive risk-reduction strategies require contributions from numerous disciplines. A volcanic eruption is not a hazard, per se, but rather an event capable of producing a variety of hazards (e.g. earthquakes, pyroclastic density currents, lava flows, tephra fall, lahars, landslides, gas release, and tsunamis) that can affect the built environment in a variety of ways, over different time scales and with different degrees of intensity. Our proposed model for the assessment and mitigation of exposure-based volcanic risk is mainly based on the compilation of three types of maps: hazard maps, hazard-specific vulnerability maps and exposure-based risk maps. Hazard maps identify the spatial distribution of individual volcanic hazard and it includes both event analysis and impact analysis. Hazard-specific vulnerability maps represent the systematic evaluation of physical vulnerability of the built environment to a range of volcanic phenomena, i.e. spatial distribution of buildings vulnerable to a given hazard based on the analysis of selected building elements. Buildings are classified on the basis of their major components that are relevant for different volcanic hazards, their strength, their construction materials and are defined taking into account the potential damage that each group of building elements (e.g. walls, roof, load-bearing structure) will suffer under a volcanic hazard. All those factors are enumerated in a checklist and are used for the building survey. Hazard-specific vulnerability maps are then overlapped with hazard maps in order to compile exposure-based risk maps and so quantify the potential damage. Such quantification is the starting point of the identification of suitable mitigation measures which will be analyzed through a cost-benefit analysis to assess their financial feasibility. Information about public networks is also recorded in order to give an overall idea of the built environment condition of the island. The vulnerability assessment of the technical systems describes the potential damages that could stress systems like electricity supply, water distribution, communication networks or transport systems. These damages can also be described as function disruption of the system. The important aspect is not only the physical capacity of a system to resist, but also its capacity to continue functioning. The model will be tested on the island of Vulcano in southern Italy. Vulcano is characterized by clear signs of volcanic unrest and is the type locality for a deadly style of eruption. The main active system of Vulcano Island (La Fossa cone) is known to produce a variety of eruption styles and intensities, each posing their own hazards and threats. Six different hazard scenarios have been identified based on a detailed stratigraphic work. The urbanization on Vulcano took place in the 1980s with no real planning and its population mostly subsists on tourism. Our preliminary results show that Vulcano is not characterized by a great variability of architectural typologies and construction materials. Three main types of buildings are present (masonry with concrete frame, masonry with manufactured stone units, masonry with hollow clay bricks) and no statistically significant trends were found between physical and morphological characteristics. The recent signs of volcanic unrest combined with a complex vulnerability of the island due to an uncontrolled urban development and a significant seasonal variation of the exposed population in summer months result in a high volcanic risk. As a result, Vulcano represents the ideal environment to test a multi-hazard based risk model and to study the transition between micro (building) and macro (urban environment) scale of analysis, which is still an unexplored field in the study of volcanic risk. Different levels of vulnerability need to be analyzed in order to increase the level of preparedness, plan a potential evacuation, manage a potential volcanic crisis and assess the best mitigation measures to put in place and reduce the volcanic risk.

Participatory methods of incorporating scientific with traditional knowledge for volcanic hazard management on Ambae Island, Vanuatu

NASA Astrophysics Data System (ADS)

Cronin, Shane J.; Gaylord, David R.; Charley, Douglas; Alloway, Brent V.; Wallez, Sandrine; Esau, Job W.

2004-10-01

Ambae Island is the largest of Vanuatu’s active volcanoes. It is also one of the nation’s potentially most dangerous, with 60 million m3 of lake-water perched at over 1340 m in the summit caldera and over the active vent. In 1995, small phreatic explosions, earthquake swarms and heightened gas release led to calls for evacuation preparation and community volcanic hazard awareness programs for the ~9500 inhabitants. Differences in perspective or world-view between the island dwellers adhering to traditional beliefs (Kastom) and external scientists and emergency managers led to a climate of distrust following this crisis. In an attempt to address these issues, rebuild dialogue and respect between communities, outside scientists and administrators, and move forward in volcanic hazard education and planning for Ambae, we adapted and applied Participatory Rural Appraisal (PRA) approaches. Initial gender-segregated PRA exercises from two representative communities provided a mechanism for cataloguing local traditional viewpoints and hazard perceptions. Ultimately, by combining elements of these viewpoints and perceptions with science-based management structures, we derived volcanic hazard management guidelines, supported by an alert system and map that were more readily accepted by the test communities than the earlier “top-down” plans imposed by outside governmental and scientific agencies. The strength of PRA approaches is that they permit scientists to understand important local perspective issues, including visualisations of volcanic hazards, weaknesses in internal and external communication systems, and gender and hierarchy conflicts, all of which can hinder community emergency management. The approach we describe has much to offer both developing and industrialised communities that wish to improve their awareness programs and mitigative planning. This approach should also enhance communication and understanding between volcanologists and the communities they serve.

First results of the Piton de la Fournaise STRAP 2015 experiment: multidisciplinary tracking of a volcanic gas and aerosol plume

NASA Astrophysics Data System (ADS)

Tulet, Pierre; Di Muro, Andréa; Colomb, Aurélie; Denjean, Cyrielle; Duflot, Valentin; Arellano, Santiago; Foucart, Brice; Brioude, Jérome; Sellegri, Karine; Peltier, Aline; Aiuppa, Alessandro; Barthe, Christelle; Bhugwant, Chatrapatty; Bielli, Soline; Boissier, Patrice; Boudoire, Guillaume; Bourrianne, Thierry; Brunet, Christophe; Burnet, Fréderic; Cammas, Jean-Pierre; Gabarrot, Franck; Galle, Bo; Giudice, Gaetano; Guadagno, Christian; Jeamblu, Fréderic; Kowalski, Philippe; Leclair de Bellevue, Jimmy; Marquestaut, Nicolas; Mékies, Dominique; Metzger, Jean-Marc; Pianezze, Joris; Portafaix, Thierry; Sciare, Jean; Tournigand, Arnaud; Villeneuve, Nicolas

2017-04-01

The STRAP (Synergie Transdisciplinaire pour Répondre aux Aléas liés aux Panaches volcaniques) campaign was conducted over the entire year of 2015 to investigate the volcanic plumes of Piton de La Fournaise (La Réunion, France). For the first time, measurements at the local (near the vent) and at the regional scales were conducted around the island. The STRAP 2015 campaign has become possible thanks to strong cross-disciplinary collaboration between volcanologists and meteorologists. The main observations during four eruptive periods (85 days) are summarised. They include the estimates of SO2, CO2 and H2O emissions, the altitude of the plume at the vent and over different areas of La Réunion Island, the evolution of the SO2 concentration, the aerosol size distribution and the aerosol extinction profile. A climatology of the volcanic plume dispersion is also reported. Simulations and measurements show that the plumes formed by weak eruptions have a stronger interaction with the surface of the island. Strong SO2 mixing ratio and particle concentrations above 1000 ppb and 50 000 cm-3 respectively are frequently measured over a distance of 20 km from Piton de la Fournaise. The measured aerosol size distribution shows the predominance of small particles in the volcanic plume. Several cases of strong nucleation of sulfuric acid have been observed within the plume and at the distal site of the Maïdo observatory. The STRAP 2015 campaign provides a unique set of multi-disciplinary data that can now be used by modellers to improve the numerical parameterisations of the physical and chemical evolution of the volcanic plumes.

Earth Observations taken by the Expedition 14 crew

NASA Image and Video Library

2007-04-02

ISS014-E-18844 (2 April 2007) --- A plume at Mt. Bagana, Bougainville Island is featured in this image photographed by an Expedition 14 crewmember on the International Space Station. Bougainville Island, part of the Solomon Islands chain to the east of Papua New Guinea, is typical of many Pacific Rim islands in that volcanism has played a large part in both its geological and recorded history. The island hosts three large volcanoes along its northwest-southeast trending axis: Mt. Balbi, Mt. Bagana, and the Mt. Takuan volcanic complex. Mt. Bagana (near center) is the only volcano on the island that has been historically active. Light green stressed vegetation, and brown lobate lava flows mark the 1,750 meter high lava cone of Mt. Bagana within the verdant landscape of Bougainville Island. The eruptive style of the volcano is typically non-explosive, producing thick lobes of andesitic lava that run down the flanks and maintain a dome in the summit crater. Occasional pyroclastic flows have also been noted. The most recent phase of activity, which began on March 7, has been characterized by vapor plumes with occasional ash-producing emissions. This photograph, acquired almost one month (twenty days) after the last reported activity at Bagana, records a diffuse white vapor plume extending west-southwest from the summit. The Solomon Island region experiences other effects due to the geologic setting: earlier this week, a large but shallow earthquake shook the region and induced a tsunami that hit the western part of the Solomon Island chain.

First high resolution P wave velocity structure beneath Tenerife Island, (Canary Islands, Spain)

NASA Astrophysics Data System (ADS)

Garcia-Yeguas, Araceli; Ivan, Koulakov; Ibañez Jesus, M.; Valenti, Sallarès.

2010-05-01

3D velocity structure distribution has been imaged for first time using high resolution traveltime seismic tomography of the active volcano of Tenerife Island (Canary Islands, Spain). It is located in the Atlantic Ocean. In this island is situated the Teide stratovolcano (3718 m high) that is part of the Cañadas-Teide-Pico Viejo volcanic complex. Las Cañadas is a caldera system more than 20 kilometers wide where at least four distinct caldera processes have been identified. Evidence for many explosive eruptions in the volcanic complex has been found; the last noticeable explosive eruption (sub-plinean) occurred at Montaña Blanca around 2000 years ago. During the last 300 years, six effusive eruptions have been reported, the last of which took place at Chinyero Volcano on 18 November 1909. In January 2007, a seismic active experiment was carried out as part of the TOM-TEIDEVS project. About 6850 air gun shots were fired on the sea and recorded on a dense local seismic land network consisting of 150 independent (three component) seismic stations. The good quality of the recorded data allowed identifying P-wave arrivals up to offsets of 30-40 km obtaining more than 63000 traveltimes used in the tomographic inversion. The images have been obtained using ATOM-3D code (Koulakov, 2009). This code uses ray bending algorithms in the ray tracing for the forward modelling and in the inversion step it uses gradient methods. The velocity models show a very heterogeneous upper crust that is usual in similar volcanic environment. The tomographic images points out the no-existence of a magmatic chamber near to the surface and below Pico Teide. The ancient Las Cañadas caldera borders are clearly imaged featuring relatively high seismic velocity. Moreover, we have found a big low velocity anomaly in the northwest dorsal of the island. The last eruption took place in 1909 in this area. Furthermore, in the southeast another low velocity anomaly has been imaged. Several resolution and accuracy tests were carried out to quantify the reliability of the final velocity models. Checkerboard tests show that the well-resolved are located up to 6-8 km depth. Also we carried out synthetic tests in which we successfully reproduce single anomalies observed in the velocity models. Especially we have study carefully the low velocity anomalies found in the NW and SE, which have been recovered successfully. The jack-knife technique have been used and our results are stable if we remove the 50% of the data for different stations, but if we reject all the data for some stations, the velocity models can change. These tests assure the uniqueness of the first 3D velocity model that characterizes the internal structure of the Tenerife Island. As main conclusions of our work we can remark: a) This is the first 3-D velocity image of the area; b) we have observed low velocity anomalies near to surface that could be associated to the presence of magma, water reservoirs and volcanic landslides; c) high velocity anomalies could be related to ancient volcanic episodes or basement structures; d) our results could help to resolve many questions relate to the evolution of the volcanic system, as the presence or not of big landslides, calderic explosions or others; e) this image is a very important tool to improve the knowledge of the volcanic hazard, and therefore volcanic risk. We would like to highlight the importance of take into account the risk of eruption in other areas besides Pico Teide-Las Cañadas system.

Chemical Composition Characteristics of Atmospheric Aerosols in Relation to Haze, Asian Dust and Mixed Haze-Asian Dust Episodes at Background Site of Korea in 2013

NASA Astrophysics Data System (ADS)

KO, H.; Song, J. M.; Cha, J. W.; Kang, C. H.; Kim, J.; Ryoo, S. B.

2016-12-01

The PM10 and PM2.5 aerosols were collected at the Gosan site of Jeju Island, Korea in 2013 and analyzed, in order to examine the variation characteristics of chemical compositions in relation to haze, Asian dust, and mixed haze-Asian dust episodes. For the haze event, nitrate concentrations increased highly as 8.8 and 25.1 times for PM10 and PM2.5, respectively, possibly caused by the inflow of air mass stagnated in eastern parts of China into Jeju area. For the Asian dust event, the concentrations of nss-Ca2+, NO3- and nss-SO42- increased 6.0, 1.5, 1.8 times for PM10, and 2.3, 1.3, 1.6 times for PM2.5, respectively. Meanwhile, for the mixed haze-Asian dust event, the concentrations of nss-Ca2+ and NO3- increased 13.4 and 3.2 times for PM10, and 1.8 and 3.4 times for PM2.5, respectively. The NH4NO3 content was higher than that of (NH4)2SO4 during the haze event, however it was relatively low during the mixed haze-Asian dust event. NO3-/nss-SO42- concentration ratios of Asian Dust in PM10 and PM2.5 were 0.4 and 0.2, showing less significant effect from automobile and local pollution sources. The aerosols were acidified mostly by inorganic acids, especially the nitric acid contributed highly to the acidification during both haze and mixed haze-Asian dust events. Meanwhile, the neutralization by ammonia was noticeably high during haze event when the stagnated air mass moved from China.

The 2011 volcanic crisis at El Hierro (Canary Islands): monitoring ground deformation through tiltmeter and gravimetric observations

NASA Astrophysics Data System (ADS)

Arnoso, J.; Montesinos, F. G.; Benavent, M.; Vélez, E. J.

2012-04-01

El Hierro is an ocean island located at the western end of the Canary Islands, and along with Tenerife and La Palma islands have been the most geologically active in the recent past. The island has a triple armed rift and, presently, is at the stage of growth, representing the summit of a volcanic shield elevating from the seafloor at depth of 4000 m up to 1501 m above the sea level (Münn et al., 2006; Carracedo et al., 1999). Since July 19th, 2011 seismic activity has produced more than 11950 events up to date. The seismic crisis resulted in a volcanic eruption that began on October 10th, being still currently active. The new volcano is located 2 km off the coast and about 300 m depth, in the submarine flank of the southern rift of the island, which is extended some 40 km length. Since September 2004 until November 2010 two continuous tilt stations were installed at the north, Balneario site (BA), and at the center of the island, Aula de la Naturaleza (AU) site. Both stations were used to assess the pattern of local ground movements in the island. When seismic swarm started on past July 2011, we have reinstalled both tilt stations (BA and AU) and 2 new ones located at the south of the island, namely Montaña Quemada (MQ) and Restinga (RE) sites. We have used short base platform tiltmeters that measure ground tilts with resolutions varying from 0.1 up to 0.01 microradians (µrad). On October 8th, a 4.4 magnitude earthquake took place and is supposed that fractured the ocean crust at some 8-10 km off the south coast of the island and about 1000 m depth. Typical spike signals were observed at the tilt stations. Two days after, the eruption onset was recorded also at tilt stations through a remarkable increase of the high frequency signal, being of large amplitude the components (radial) orientated towards the new volcano edifice. When compared with previous tiltmeter records in the island, tilt pattern were clearly modified several times at the stations when strong and shallow earthquakes happened, producing in some cases large tilt variations of tens of µrad. By other side, in 2003 we established a control gravity network that was measured again in 2004 and 2008. After the beginning of the eruption on October 2011, we have carried out gravity measurements in various points of the network as well as other new points to attain more accurate control of the possible variations of gravity or/and altitude. Gravity data are still under study although some results about observed gravity changes could reflect the ground deformations pattern according to tiltmeter records and GPS measurements, or a change in the subsurface mass distribution as consequence of the new emplacement the magmatic material in the area with volcanic and seismic activity.

Regional Geological Maps of the Northeast Pacific - Standard Navy Ocean Area NP-9

DTIC Science & Technology

1978-01-01

creates the next Washington, and British Columbia. All the land area, except island in the chain. Thus, many island chains, for example. the that seaward of...the San Andreas Fault of California, is part of Hawaiian Islands , seem to indicate the path of the plate over the North American Plate. such "hot...turbiditc deposition from the nearby been deposited by bottom currents, volcanic sources such as the Hawaiian Islands and from the deposition of sediments

Short-term volcano-tectonic earthquake forecasts based on a moving mean recurrence time algorithm: the El Hierro seismo-volcanic crisis experience

NASA Astrophysics Data System (ADS)

García, Alicia; De la Cruz-Reyna, Servando; Marrero, José M.; Ortiz, Ramón

2016-05-01

Under certain conditions, volcano-tectonic (VT) earthquakes may pose significant hazards to people living in or near active volcanic regions, especially on volcanic islands; however, hazard arising from VT activity caused by localized volcanic sources is rarely addressed in the literature. The evolution of VT earthquakes resulting from a magmatic intrusion shows some orderly behaviour that may allow the occurrence and magnitude of major events to be forecast. Thus governmental decision makers can be supplied with warnings of the increased probability of larger-magnitude earthquakes on the short-term timescale. We present here a methodology for forecasting the occurrence of large-magnitude VT events during volcanic crises; it is based on a mean recurrence time (MRT) algorithm that translates the Gutenberg-Richter distribution parameter fluctuations into time windows of increased probability of a major VT earthquake. The MRT forecasting algorithm was developed after observing a repetitive pattern in the seismic swarm episodes occurring between July and November 2011 at El Hierro (Canary Islands). From then on, this methodology has been applied to the consecutive seismic crises registered at El Hierro, achieving a high success rate in the real-time forecasting, within 10-day time windows, of volcano-tectonic earthquakes.

Volcanic hazard communication using maps: an evaluation of their effectiveness

NASA Astrophysics Data System (ADS)

Haynes, Katharine; Barclay, Jenni; Pidgeon, Nick

2007-11-01

Hazard maps are considered essential tools in the communication of volcanic risk between scientists, the local authorities and the public. This study investigates the efficacy of such maps for the volcanic island of Montserrat in the West Indies using both quantitative and qualitative research techniques. Normal plan view maps, which have been used on the island over the last 10 years of the crisis, are evaluated against specially produced three-dimensional (3D) maps and perspective photographs. Thirty-two demographically representative respondents of mixed backgrounds, sex, education and location were interviewed and asked to complete a range of tasks and identification on the maps and photographs. The overall results show that ordinary people have problems interpreting their environment as a mapped representation. We found respondents’ ability to locate and orientate themselves as well as convey information relating to volcanic hazards was improved when using aerial photographs rather than traditional plan view contour maps. There was a slight improvement in the use of the 3D maps, especially in terms of topographic recognition. However, the most striking increase in effectiveness was found with the perspective photographs, which enabled people to identify features and their orientation much more readily. For Montserrat it appears that well labelled aerial and perspective photographs are the most effective geo-spatial method of communicating volcanic risks.

Characterization of Early Microbial Communities on Volcanic Deposits along a Vegetation Gradient on the Island of Miyake, Japan

PubMed Central

Guo, Yong; Fujimura, Reiko; Sato, Yoshinori; Suda, Wataru; Kim, Seok-won; Oshima, Kenshiro; Hattori, Masahira; Kamijo, Takashi; Narisawa, Kazuhiko; Ohta, Hiroyuki

2014-01-01

The 2000 eruption of Mount Oyama on the island of Miyake (Miyake-jima) created a unique opportunity to study the early ecosystem development on newly exposed terrestrial substrates. In this study, bacterial and fungal communities on 9- and 11-year-old volcanic deposits at poorly to fully vegetation-recovered sites in Miyake-jima, Japan, were characterized by conventional culture-based methods and pyrosequencing of 16S rRNA and 18S rRNA genes. Despite the differences in the vegetation cover, the upper volcanic deposit layer samples displayed low among-site variation for chemical properties (pH, total organic carbon, and total nitrogen) and microbial population densities (total direct count and culturable count). Statistical analyses of pyrosequencing data revealed that the microbial communities of volcanic deposit samples were phylogenetically diverse, in spite of very low-carbon environmental conditions, and their diversity was comparable to that in the lower soil layer (buried soil) samples. Comparing with the microbial communities in buried soil, the volcanic deposit communities were characterized by the presence of Betaproteobacteria and Gammaproteobacteria as the main bacterial class, Deinococcus- Thermus as the minor bacterial phyla, and Ascomycota as the major fungal phyla. Multivariate analysis revealed that several bacterial families and fungal classes correlated positively or negatively with plant species. PMID:24463576

Impact of Magmatism on the Geodynamic Evolution of Southern Georgia on the Example of the Lesser Caucasus Artvin-Bolnisi Block.

NASA Astrophysics Data System (ADS)

Sadradze, Nino; Adamia, Shota; Zakariadze, Guram; Beridze, Tamara; Khutsishvili, Sophio

2017-04-01

The Georgian region occupies the central part of the collisional zone between the Eurasian and Africa-Arabian continents and is actually a collage of lithospheric fragments of the Tethyan Ocean and its northern and southern continental margins. Magmatic evolution is an important event in the formation and development of the geological structure of Southern Georgia, where several reliably dated volcanogenic and volcanogenic-sedimentary formations are established. The region represents a modern analogue of continental collision zone, where subduction-related volcanic activity lasted from Paleozoic to the end of Paleogene. After the period of dormancy in the Early-Middle Miocene starting from the Late Miocene and as far as the end of the Pleistocene, primarily subaerial volcanic eruptions followed by formation of volcanic highlands and plateaus occurred in the reigon. The Upper Miocene to Holocene volcanic rocks are related to the transverse Van-Transcaucasian uplift and belong to post-collisional calc- alkaline basalt-andesite-dacite-rhyolite series. A system of island arc and intra-arc rift basins (Artvin-Bolnisi and Achara-Trialeti) have been interpreted as characteristic of the pre-collisional stage of the region development, while syn- post-collisional geodynamic events have been attributed to intracontinental stage. Outcrops of the postcollisional magmatic rocks are exposed along the boundaries of the major tectonic units of the region. The Artvin-Bolnisi unit forms the northwestern part of the Lesser Caucasus and represents an island arc domain of so called the Somkheto-Karabakh Island Arc or Baiburt-Garabagh-Kapan belt. It was formed mainly during the Jurassic-Eocene time interval on the southern margin of the Eurasian plate by nort-dipping subduction of the Neotethys Ocean and subsequent collision to the Anatolia-Iranian continental plate. The Artvin-Bolnisi unit, including the Bolnisi district, was developing as a relatively uplifted island arc-type unit with suprasubduction extrusive and intrusive events. Volcanogenic complexes are characterized by variable lateral and vertical regional stratigraphic relationships and are subdivided into several formations, dominated by volcanic rocks: basalts, andesites, dacites, and rhyolites of calc-alkaline-subalkaline series. Volcanic rocks are of shallow-marine to subaerial type. The peculiarities of magmatic activity and geodynamic development of the region stipulated synchronous formation of significant base and precious metals deposits of the Bolnisi ore district.

Using Nd and Sr isotopes to trace dust and volcanic inputs to soils on French Guadeloupe Island

NASA Astrophysics Data System (ADS)

Guo, J.; Pereyra, Y.; Ma, L.; Gaillardet, J.; Sak, P. B.; Bouchez, J.

2017-12-01

Soil is at the central part of the Critical Zone for its important roles in sustaining ecosystems and agriculture. At French Guadeloupe, a tropical humid volcanic island, previous studies have shown that the mineral nutrient elements such as K, Na, Ca, and Mg are highly depleted in the surface soil. And mineral nutrients introduced by dusts are an important mineral nutrient source for vegetation growth in this area. It is important to understand and quantify the sources of the mineral dust added to surface soils. Nd isotope ratios, due to their distinct signatures between two unique end-members in soils for this area: the young volcanic areas like Guadeloupe and the dust source region from the old continental shields like Sahara Desert, can be a robust tracer to understand this critical process. Nevertheless, Sr isotope ratios can trace the inputs of marine aerosols. Here we present a new Nd isotope study on Guadeloupe soil depth profiles, combined with previous Sr isotope data, to fingerprint the sources of dust and volcanic inputs into soils. Soil samples from three surface profiles (0 - 1000cm deep) at different locations of the Guadeloupe Island were systematically analyzed. The results show distinct depth variations for Nd isotope signature along profiles. For all profiles, deep soils are relatively consisted with bedrock value (ɛNd: 5.05). But in surface soils (0-600cm), unlike Sr isotope ratios that are significantly modified by marine aerosol input, Nd isotope ratios show similar decrease (to ɛNd:-10) and frequent fluctuations toward the surface, suggesting dust is the dominant source of Nd in these soils. This conclusion is further supported by REE and other trace element data. Thus, with a simplified two end-member model, Sahara dust contributes the Nd percentages in soils varying from 10.7% at the deepest profiles to 69.5% on surface, showing a significant amount of Nd on the surface soil came from dust source. The deep soil profiles are also characterized by the presence of Nd isotope spikes with negative values, suggesting dust signatures at depth. Such a feature could be related to the presence of a paleo-soil surface at the spike depth that was buried by later volcanic eruption. Both Nd and Sr isotopes hence show dust and volcanic inputs are important factors for soil developments on French Guadeloupe Island.

Magmatic evolution of the Easter microplate-Crough Seamount region (South East Pacific)

USGS Publications Warehouse

Hekinian, R.; Stoffers, P.; Akermand, D.; Binard, N.; Francheteau, Jean; Devey, C.; Garbe-Schonberg, D.

1995-01-01

The Easter microplate-Crough Seamount region located between 25?? S-116?? W and 25?? S-122?? W consists of a chain of seamounts forming isolated volcanoes and elongated (100-200 km in length) en echelon volcanic ridges oriented obliquely NE (N 065??), to the present day general spreading direction (N 100??) of the Pacific-Nazca plates. The extension of this seamount chain into the southwestern edge of the Easter microplate near 26??30??? S-115?? W was surveyed and sampled. The southern boundary including the Orongo fracture zone and other shallow ridges ( 0.25) MORBs which are similar in composition to other more recent basalts from the Southwest and East Rifts spreading axes of the Easter microplate. Incompatible element ratios normalized to chondrite values [(Ce/Yb)N = 1-2.5}, {(La/Sm)N = 0.4-1.2} and {(Zr/Y)N = 0.7-2.5} of the basalts are also similar to present day volcanism found in the Easter microplate. The volcanics from the Easter microplate-Crough region are unrelated to other known South Pacific intraplate magmatism (i.e. Society, Pitcairn, and Salas y Gomez Islands). Instead their range in incompatible element ratios is comparable to the submarine basalts from the recently investigated Ahu and Umu volcanic field (Easter hotspot) (Scientific Party SO80, 1993) and centered at about 80 km west of Easter Island. The oblique ridges and their associated seamounts are likely to represent ancient leaky transform faults created during the initial stage of the Easter microplate formation (??? 5 Ma). It appears that volcanic activity on seamounts overlying the oblique volcanic ridges has continued during their westward drift from the microplate as shown by the presence of relatively fresh lava observed on one of these structures, namely the first Oblique Volcanic Ridge near 25?? S-118?? W at about 160 km west of the Easter microplate West Rift. Based on a reconstruction of the Easter microplate, it is suggested that the Crough seamount (< 800 m depth) was formed by earlier (7-10 Ma) hotspot magmatic activity which also created Easter Island. ?? 1995 Kluwer Academic Publishers.

Petrography and geochemistry of clastic rocks within the Inthanon zone, northern Thailand: Implications for Paleo-Tethys subduction and convergence

NASA Astrophysics Data System (ADS)

Hara, Hidetoshi; Kunii, Miyuki; Hisada, Ken-ichiro; Ueno, Katsumi; Kamata, Yoshihito; Srichan, Weerapan; Charusiri, Punya; Charoentitirat, Thasinee; Watarai, Megumi; Adachi, Yoshiko; Kurihara, Toshiyuki

2012-11-01

The provenance, source rock compositions, and sediment supply system for a convergence zone of the Paleo-Tethys were reconstructed based on the petrography and geochemistry of clastic rocks of the Inthanon Zone, northern Thailand. The clastic rocks are classified into two types based on field and microscopic observations, the modal composition of sandstone, and mineral compositions: (1) lithic sandstone and shale within mélange in a Permo-Triassic accretionary complex; and (2) Carboniferous quartzose sandstone and mudstone within the Sibumasu Block. Geochemical data indicate that the clastic rocks of the mélange were derived from continental island arc and continental margin settings, which correspond to felsic volcanic rocks within the Sukhothai Zone and quartz-rich fragments within the Indochina Block, respectively. The results of a mixing model indicate the source rocks were approximately 35% volcanic rocks of the Sukhothai Zone and 65% craton sandstone and upper continental crust of the Indochina Block. In contrast, Carboniferous quartzose sedimentary rocks within the Sibumasu Block originated from a continental margin, without a contribution from volcanic rocks. In terms of Paleo-Tethys subduction, a continental island arc in the Sukhothai Zone evolved in tandem with Late Permian-Triassic forearc basins and volcanic activity during the Middle-early Late Triassic. The accretionary complex formed contemporaneously with the evolution of continental island arc during the Permo-Triassic, supplied with sediment from the Sukhothai Zone and the Indochina Block.

Metrosideros polymorpha Gaudich

Treesearch

James A. Allen

2002-01-01

Metrosideros is a genus of about 50 species. With the exception of one species found in South Africa, all grow in the Pacific from the Philippines, through Papua New Guinea, to New Zealand and on high volcanic islands (Wagner and others 1990). Five species occur in the Hawaiian Islands (Wagner and others 1990). Metrosideros polymorpha...

Digital Holography and 3D Imaging: introduction to the joint feature issue in Applied Optics and Journal of the Optical Society of America A.

PubMed

Kang, Hoonjong; Lee, Byoungho; Kozacki, Tomasz; Picart, Pascal; Situ, Guohai

2018-01-01

The OSA Topical Meeting on Digital Holography and 3D Imaging (DH) was held 29 May to 1 June 2017 in Jeju Island, South Korea. Feature issues based on the DH meeting series have been released by Applied Optics (AO) since 2007. This year, AO and the Journal of the Optical Society of America A (JOSA A) jointly decided to have one such feature issue in each journal. This feature issue includes 33 papers in AO and 9 in JOSA A and covers a large range of topics, reflecting the rapidly expanding techniques and applications of digital holography and 3D imaging. The upcoming DH meeting (DH 2018) will be held 25-28 June 2018 in Orlando, Florida, USA, as part of the OSA Imaging and Applied Optics Congress.

Digital Holography and 3D Imaging: introduction to the joint feature issue in Applied Optics and Journal of the Optical Society of America A.

PubMed

Kang, Hoonjong; Lee, Byoungho; Kozacki, Tomasz; Picart, Pascal; Situ, Guohai

2018-01-01

The OSA Topical Meeting on Digital Holography and 3D Imaging (DH) was held 29 May to 1 June 2017 on Jeju Island, South Korea. Feature issues based on the DH meeting series have been released by Applied Optics (AO) since 2007. This year, AO and the Journal of the Optical Society of America A (JOSA A) jointly decided to have one such feature issue in each journal. This feature issue includes 33 papers in AO and 9 in JOSA A and covers a large range of topics, reflecting the rapidly expanding techniques and applications of digital holography and 3D imaging. The upcoming DH meeting (DH 2018) will be held 25-28 June 2018 in Orlando, Florida, as part of the OSA Imaging and Applied Optics Congress.

The Line Islands revisited: New 40Ar/39Ar geochronologic evidence for episodes of volcanism due to lithospheric extension

NASA Astrophysics Data System (ADS)

Davis, A. S.; Gray, L. B.; Clague, D. A.; Hein, J. R.

2002-03-01

New 40Ar/39Ar ages of mineral separates and whole rock samples from nine volcanic edifices in the northern Line Islands region, between latitudes 20°N and 6°N, are incompatible with single or multiple hot spot models. Instead, two major episodes of volcanism, each lasting ~5 Ma and separated by ~8 Ma, occurred synchronously over long distances, not just along the main chain but also at nonaligned edifices. Volcanism during the older episode (81-86 Ma) extended over a distance of at least 1200 km along the eastern part of the complex seamount chain. Volcanism during the younger episode (68-73 Ma) was concentrated in the western part of the chain and may have extended over a distance of >4000 km. Chemical analyses of 68 samples represent a compositionally diverse suite, including tholeiitic, transitional, and alkalic basalt, strongly alkalic basanite and nephelinite, and alkalic differentiates ranging from hawaiite to trachyte. The most diverse assemblage of rocks was recovered from a cross-trending seamount chain south of Johnston Atoll. Although compositions of rocks from the two volcanic episodes overlap, compositions from the younger episode generally are more alkalic and include a larger proportion of highly differentiated compositions. None of the samples from the older episode, but many from the younger one, contain hydrous mineral phases such as amphibole and biotite. Extensive coeval volcanism along major segments of the chain is compatible with decompressional melting of heterogeneous mantle due to diffuse lithospheric extension along pre-existing zones of weakness. Episodes of volcanism are probably related to broad upwarping of the Superswell region in the eastern South Pacific, where these lavas originated.

Neogene Fault and Feeder Dike Patterns in the Western Ross Sea

NASA Astrophysics Data System (ADS)

Magee, W. R.; Wilson, T. J.

2010-12-01

In Antarctica, where much of the continent is covered by water and ice, geophysical data from the Antarctic submarine continental shelf is a fundamental part of reconstructing geological history. Multibeam sonar from the western Ross Sea has revealed elongate volcanic edifices and fields of elongate submarine hills on the seafloor. Origin of the submarine hills as carbonate mounds and drumlins have been proposed. The hills are up to ~8000m long and ~3500m wide, and rise 50-100m above the seafloor. Morphometric analysis of the hills shows they are elongate, with axial ratios ranging from 1.2:1 to 2:1, and some hills are linked to form elongate ridges. Seismic profiles show significant pull-ups directly below the hills, consistent with narrow, higher-density magmatic bodies; thus we favor an origin as volcanic seamounts above subsurface feeder dikes. If this volcanic hypothesis is correct, feeder dikes below the hills and elongate volcanic ridges may document magmatically-forced extension within the Terror Rift. The seamount field forms part of a regional en echelon array of volcanic ridges extending NNW from Beaufort Island toward Drygalski Ice Tongue. The ridges and elongate seamount cluster trend NNE, subparallel to mapped fault trends in this sector of the Terror Rift. This geometry is compatible with right-lateral transtension along this zone, as previously proposed for the Terror Rift as a whole. Volcanic islands and dredged volcanic ridges within the en echelon array are dated at ~7-4 Ma, implying Neogene deformation. We are completing a detailed analysis of orientation patterns and cross-cutting relations between faults and volcanic hills and their feeder systems to test this model for Neogene rift kinematics.

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

USGS Publications Warehouse

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

2009-01-01

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

New insights from IODP Expedition 340 offshore Montserrat: First drilling of large volcanic island landslides

NASA Astrophysics Data System (ADS)

Talling, Peter; Le Friant, Anne; Ishizuka, Osamu; Watt, Sebastian; Coussens, Maya; Jutzeler, Martin; Wall-Palmer, Deborah; Palmer, Martin; Cassidy, Michael; Kataoka, Kyoko; Endo, Daisuko; McCanta, Molly; Trofimovs, Jessica; Hatfield, Robert; Stinton, Adam; Lebas, Elodie; Boudon, Georges; Expedition 340 Shipboard Science Party, IODP

2015-04-01

Montserrat now provides one of the most complete datasets for understanding the character and tempo of hazardous events at volcanic islands. Much of the erupted material ends up offshore, and this offshore record may be easier to date due to intervening hemiplegic sediments between event beds. The offshore dataset includes the first scientific drilling of volcanic island landslides during IODP Expedition 340, together with an unusually comprehensive set of shallow sediment cores and 2-D and 3-D seismic surveys. Most recently in 2013, Remotely Operated Vehicle (ROV) dives mapped and sampled the surface of the main landslide deposits. This contribution aims to provide an overview of key insights from ongoing work on IODP Expedition 340 Sites offshore Montserrat.Key objectives are to understand the composition (and hence source), emplacement mechanism (and hence tsunami generation) of major landslides, together with their frequency and timing relative to volcanic eruption cycles. The most recent major collapse event is Deposit 1, which involved ~1.8 km cubed of material and produced a blocky deposit at ~12-14ka. Deposit 1 appears to have involved not only the volcanic edifice, but also a substantial component of a fringing bioclastic shelf, and material locally incorporated from the underlying seafloor. This information allows us to test how first-order landslide morphology (e.g. blocky or elongate lobes) is related to first-order landslide composition. Preliminary analysis suggests that Deposit 1 occurred shortly before a second major landslide on the SW of the island (Deposit 5). It may have initiated English's Crater, but was not associated with a major change in magma composition. An associated turbidite-stack suggests it was emplaced in multiple stages, separated by at least a few hours and thus reducing the tsunami magnitude. The ROV dives show that mega-blocks in detail comprise smaller-scale breccias, which can travel significant distances without complete disintegration. Landslide Deposit 2 was emplaced at ~130ka, and is more voluminous (~8.4km cubed). It had a much more profound influence on the magmatic system, as it was linked to a major explosive mafic eruption and formation of a new volcanic centre (South Soufriere Hills) on the island. Site U1395 confirms a hypothesis based on the site survey seismic data that Deposit 2 includes a substantial component of pre-existing seafloor sediment. However, surprisingly, this pre-existing seafloor sediment in the lower part of Deposit 2 at Site U1395 is completely undeformed and flat lying, suggesting that Site U1395 penetrated a flat lying block. Work to date material from the upper part of U1396, U1395 and U1394 will also be summarised. This work is establishing a chronostratigraphy of major events over the last 1 Ma, with particularly detailed constraints during the last ~250ka. This is helping us to understand whether major landslides are related to cycles of volcanic eruptions.

Patterns of natural and anthropogenic disturbance of the mangroves on a small Pacific island.

Treesearch

James A. Allen; Katherine C. Ewel; Jason Jack

2001-01-01

Mangroves in many parts of the world are subjected to frequent, large-scale disturbances. A possible exception is Kosrae, Federated States of Micronesia (FSM), a small volcanic island in the west-central Pacific Ocean. Relative sea level has been stable for most of the last 1000 years and the last tropical cyclone to affect the island was in 1905. Many trees on Kosrae...

Isabela, Galapagos Islands as seen from STS-59

NASA Image and Video Library

1994-04-14

STS059-213-019 (9-20 April 1994) --- SRL scientists will use these photographs with the radar imagery to discriminate among different ages of basalt flows, and different ecosystems of shrub communities, on these equatorial volcanic islands. Aims are twofold: to understand the history of physical and biological systems on the islands themselves, and to extend what is learned to other, less-well-known areas globally. Hasselblad photograph.

Roots of the Hawaiian Hotspot. Northwestern Hawaiian Islands Exploration--Grades 9-12 (Earth Science). Seismology and Geological Origins of the Hawaiian Islands.

ERIC Educational Resources Information Center

National Oceanic and Atmospheric Administration (DOC), Rockville, MD.

This activity is designed to introduce to students the processes of plate tectonics and volcanism that resulted in the formation of the Hawaiian Islands and the difference between S waves and P waves. Students are expected to explain how seismic data recorded at different locations can be used to determine the epicenter of an earthquake, infer a…

Strategic Planning Implementation in Indonesia’s Transmigration Plan.

DTIC Science & Technology

1984-06-01

archipelago has a highly complex geolog - ical history . This effected the nation’s volcanic soil conditicns, numerous mountain systems, and a variety of...distinctive area caused by its geological structure. The islands of Java, Sumatra, and Kalimantan , together with the small islands in between, stand on the...continents, that of Asia and Australia. This formation has made the straits between the islands strategically important throughout history . because of

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

USGS Publications Warehouse

Neal, Christina A.; McGimsey, Robert G.

2002-01-01

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

Earth Observations taken by Expedition 26 crewmember

NASA Image and Video Library

2011-01-09

ISS026-E-016287 (9 Jan. 2011) --- Onekotan Island, part of the Russian Federation in the western Pacific Ocean, is featured in this image photographed by an Expedition 26 crew member on the International Space Station. Snow cover highlights calderas and volcanic cones that form the northern and southern ends of the island. Calderas are depressions formed when a volcano empties its magma chamber in an explosive eruption, followed by collapse of the overlaying material into the newly evacuated space. The northern end of the island is dominated by the Nemo Peak volcano that began forming within an older caldera approximately 9,500 years ago, according to scientists. The last recorded eruptive activity at Nemo Peak occurred in the early 18th century. The southern end of the island is formed by the 7.5 kilometer wide Tao-Rusyr Caldera. The caldera is filled by Kal’tsevoe Lake and Krenitzyn Peak, a volcano that has only erupted once in recorded history during 1952. Extending between northeastern Japan and the Kamchatka Peninsula of Russia, the Kuril Islands are an island arc located along the Pacific “Ring of Fire”. Island arcs form along an active boundary between two tectonic plates where one plate is being driven beneath the other (subduction). Magma generated by the subduction process feeds volcanoes—which eventually form volcanic islands—over the subduction boundary.

Aeromagnetic maps and second vertical derivative maps of Great Sitkin Island, Northern Adak Island, and part of northeastern Umnak Island, Alaska

USGS Publications Warehouse

Zietz, Isidore; Henderson, Roland G.

1949-01-01

The eight attached maps were constructed from data taken on Project Volcano in the summer of 1947. The project was sponsored by the Office of Naval Research and conducted by the U.S. Geological Survey in cooperation with the Naval Ordnance Laboratory. Field work was done by Fred Keller, Jr., and J. L. Meuschke, Geophysicists of the U.S. Geological Survey, and by L. R. Alldredge, Physicist of the Naval Ordnance Laboratory. The instrument used was a modified AN/ASQ-3A flux-gate type total field magnetometer mounted in the tailcone of a PBY-5A aircraft. It is hoped that observation of the magnetic fields over volcanic areas over a period of years, may lead to prognostication of volcanic activity. These maps represent the results of the first of such surveys.

A model of tephra dispersal from an early Palaeogene shallow submarine Surtseyan-style eruption(s), the Red Bluff Tuff Formation, Chatham Island, New Zealand

NASA Astrophysics Data System (ADS)

Sorrentino, Leonor; Stilwell, Jeffrey D.; Mays, Chris

2014-03-01

The Red Bluff Tuff Formation, an early Palaeogene volcano-sedimentary shallow marine succession from the Chatham Islands (New Zealand), provides a unique framework, in eastern 'Zealandia', to explore tephra dispersal processes associated with ancient small phreatomagmatic explosions (i.e. Surtseyan-style eruptions). Detailed sedimentological mapping, logging and sampling integrated with the results of extensive laboratory analyses (i.e. grain-size, componentry and applied palaeontological methods) elucidated the complex mechanisms of transport and deposition of nine identified resedimented fossiliferous volcaniclastic facies. These facies record the subaqueous reworking and deposition of tephra from the erosion and degradation of a proximal, entirely submerged ancient Surtseyan volcanic edifice (Cone II). South of this volcanic cone, the lowermost distal facies provides significant evidence of deposition as water-supported volcanic- or storm-driven mass flows (e.g. turbidity currents and mud/debris flows) of volcaniclastic and bioclastic debris, whereas the uppermost distal facies exhibit features of tractional sedimentary processes caused by shallow subaqueous currents. Further north, within the proximity of the volcanic edifice, the uppermost facies are represented by an abundant, diverse, large, and well preserved in situ fauna of shallow marine sessile invertebrates (e.g. corals and sponges) that reflect the protracted biotic stabiliszation and rebound following pulsed volcanic events. Over a period of time, these stable and wave-eroded volcanic platforms were inhabited by a flourishing and diversifying marine community of benthic and sessile pioneers (corals, bryozoans, molluscs, brachiopods, barnacles, sponges, foraminifera, etc.). This succession exhibits a vertical progression of sedimentary structures (i.e. density, cohesive and mass flows, and cross-bedding) and our interpretations indicate a shallowing upwards succession. This study reports for the first time mechanisms of degradation of a Surtseyan volcano on Chatham Islands and contributes to a better understanding of complex ancient volcano-sedimentary subaqueous terrains. This model of deposition (i.e. onlapping/overlapping features onto the remains of volcanic edifice(s), a vertical transition of structures from deeper- to shallower-marine environments, disaster faunas and subsequent preferential colonisation of diverse biota, including large in situ sessile invertebrates, on the summit), characterises an extraordinary example to be applied to other ancient subaqueous volcanic environments.

Impacts of Dust on Tropical Volcanic Soil Formation: Insights from Strontium and Uranium-Series Isotopes in Soils from Basse-Terre Island, French Guadeloupe

NASA Astrophysics Data System (ADS)

Pereyra, Y.; Ma, L.; Sak, P. B.; Gaillardet, J.; Buss, H. L.; Brantley, S. L.

2015-12-01

Dust inputs play an important role in soil formation, especially for thick soils developed on tropical volcanic islands. In these regions, soils are highly depleted due to intensive chemical weathering, and mineral nutrients from dusts have been known to be important in sustaining soil fertility and productivity. Tropical volcanic soils are an ideal system to study the impacts of dust inputs on the ecosystem. Sr and U-series isotopes are excellent tracers to identify sources of materials in an open system if the end-members have distinctive isotope signatures. These two isotope systems are particularly useful to trace the origin of atmospheric inputs into soils and to determine rates and timescales of soil formation. This study analyzes major elemental concentrations, Sr and U-series isotope ratios in highly depleted soils in the tropical volcanic island of Basse-Terre in French Guadeloupe to determine atmospheric input sources and identify key soil formation processes. We focus on three soil profiles (8 to 12 m thick) from the Bras-David, Moustique Petit-Bourg, and Deshaies watersheds; and on the adjacent rivers to these sites. Results have shown a significant depletion of U, Sr, and major elements in the deep profile (12 to 4 m) attributed to rapid chemical weathering. The top soil profiles (4 m to the surface) all show addition of elements such as Ca, Mg, U, and Sr due to atmospheric dust. More importantly, the topsoil profiles have distinct Sr and U-series isotope compositions from the deep soils. Sr and U-series isotope ratios of the top soils and sequential extraction fractions confirm that the sources of the dust are from the Saharan dessert, through long distance transport from Africa to the Caribbean region across the Atlantic Ocean. During the transport, some dust isotope signatures may also have been modified by local volcanic ashes and marine aerosols. Our study highlights that dusts and marine aerosols play important roles in element cycles and nutrient sources in the highly depleted surface soils of tropical oceanic islands.

Distribution and tectonic implications of Cretaceous-Quaternary sedimentary facies in Solomon Islands

NASA Astrophysics Data System (ADS)

Turner, C. C.; Hughes, G. W.

1982-08-01

Sedimentary rocks of the Solomon Islands-Bougainville Arc are described in terms of nine widespread facies. Four facies associations are recognised by grouping facies which developed in broadly similar sedimentary environments. A marine pelagic association of Early Cretaceous to Miocene rocks comprises three facies. Facies Al: Early Cretaceous siliceous mudstone, found only on Malaita, is interpreted as deep marine siliceous ooze. Facies A2: Early Cretaceous to Eocene limestone with chert, overlies the siliceous mudstone facies, and is widespread in the central and eastern Solomons. It represents lithified calcareous ooze. Facies A3: Oligocene to Miocene calcisiltite with thin tuffaceous beds, overlies Facies A2 in most areas, and also occurs in the western Solomons. This represents similar, but less lithified calcareous ooze, and the deposits of periodic andesitic volcanism. An open marine detrital association of Oligocene to Recent age occurs throughout the Solomons. This comprises two facies. Facies B1 is variably calcareous siltstone, of hemipelagic origin; and Facies B2 consists of volcanogenic clastic deposits, laid down from submarine mass flows. A third association, of shallow marine carbonates, ranges in age from Late Oligocene to Recent. Facies C1 is biohermal limestone, and Facies C2 is biostromal calcarenite. The fourth association comprises areally restricted Pliocene to Recent paralic detrital deposits. Facies D1 includes nearshore clastic sediments, and Facies D2 comprises alluvial sands and gravels. Pre-Oligocene pelagic sediments were deposited contemporaneously with, and subsequent to, the extrusion of oceanic tholeiite. Island arc volcanism commenced along the length of the Solomons during the Oligocene, and greatly influenced sedimentation. Thick volcaniclastic sequences were deposited from submarine mass flows, and shallow marine carbonates accumulated locally. Fine grained graded tuffaceous beds within the marine pelagic association are interpreted as products of this volcanism, suggesting that the Santa Isabel-Malaita-Ulawa area, where these beds are prevalent, was relatively close to the main Solomons chain at this time. A subduction zone may have dipped towards the northeast beneath this volcanic chain. Pliocene to Pleistocene calcalkaline volcanism and tectonism resulted in the emergence of all large islands and led to deposition of clastic and carbonate facies in paralic, shallow and deep marine environments.

Detailed Ar-Ar Geochronology of Volcanism at Minna Bluff, Antarctica: Two-Phased Growth and Influence on Ross Ice Shelf

NASA Astrophysics Data System (ADS)

Ross, J. I.; McIntosh, W. C.; Wilch, T. I.

2012-12-01

Minna Bluff has been a significant topographic barrier to the flow of the Ross Ice Shelf since the mid-Miocene. Detailed Ar-Ar analyses of kaersutite and sanidine phenocrysts, and groundmass concentrates from volcanic units indicate an overall west to east progression of volcanic activity. Eruptions of basaltic to intermediate lavas, domes, and scoria cones started at ~12 Ma in at what is now the eastern most point of Minna Bluff, "Minna Hook." Activity was centered in this area for ~4 Ma, constructing a pre-Minna Bluff island. Multiple glacial unconformities found at Minna Hook suggest repeated interaction with large warm-based, erosive ice sheets. Activity migrated westward from Minna Bluff Island at 7-8 Ma closing the gap created by the island and the mainland. Significant edifice construction continued until 4-5 Ma with sporadic and parasitic scoria cone eruptions, possibly associated with Mt. Discovery activity, continuing until 2 Ma. The orientations of Minna Bluff's two major axes are strongly controlled by regional tectonic features. Minna Bluff's E-W axis, McIntosh Cliffs, is sub-parallel to the Radial Lineament and the N-S axis, Minna Hook, appears as extension of faulting bounding the Terror Rift. The constructional evolution of the 70km long volcanic complex has an important role in interpreting the climate signals recovered by the ANDRILL Project. Minna Bluff influenced the material delivered to the AND-1B drill site (ANDRILL MIS 2006-2007) in three critical ways: 1) Minna Bluff diverted upstream material, 2) provided a pinning and stabilizing point for the Ross Ice Shelf, possible controlling the calving line prior to the emergence of Ross Island, and 3) was a significant source of fresh volcanic material throughout much of the period recovered by ANDRILL MIS. For example, a kaersutite-bearing clast recovered from 822.78 mbsf in AND-1B yielded an age of 8.53±0.51 Ma, and was likely derived from Minna Bluff. The results from this study can be incorporated into detailed glacier and ice-sheet models of the McMurdo Sound region, a critical area in the Ross Ice Sheet and global climate system.

Tephra compositions from Late Quaternary volcanoes around the Antarctic Peninsula

NASA Astrophysics Data System (ADS)

Kraus, S.

2009-12-01

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.

Seismic Stratigraphy of the Ross Island Flexural Basin, West Antarctica

NASA Astrophysics Data System (ADS)

Wenman, C. P.; Harry, D. L.; Jha, S.

2014-12-01

Marine seismic reflection data collected over the past 30+ years in the Ross Sea region of southwest Antarctica has been tied to the ANDRILL and CIROS boreholes to develop a seismic stratigraphic model that constrains the spatial and temporal evolution of the flexural basin surrounding Ross Island. Ross Island was formed from 4.6 Ma to present by extrusive volcanism in the Ross Sea at the southern end of the Terror Rift. Preliminary mapping has identified a hinge zone trending northeastward from Mt. Bird, separating the well-developed flexural moat on the west side of the island from sub-horizontal strata on the northeast and east sides. The flexural moat on the west and north-northwest sides of the island is approximately 40-45 km wide with sediment fill thickness of roughly 1100 m. Seismic lines to the east and northeast of the island do not indicate the presence of a flexural moat. Instead, the thickness of strata on the east side of the island that are time-equivalent to the infill of the flexural moat on the west side remains constant from the Coulman High westward to within ~28 km of Ross Island (the landward extent of the seismic data coverage). The concordant post-Miocene strata on the east and northeast sides of Ross Island imply either that the flexural basin does not extend more than ~28 km eastward from the Ross Island shoreline, or that the flexural basin is not present on that side of the island. The first scenario requires that the elastic strength of the lithosphere differ on either side of the hinge. The second scenario can be explained by a mechanical rupture in the lithosphere beneath Ross Island, with Ross Island acting as an end-load on a mechanical half-plate that forms the lithosphere beneath Ross Island and westward. In this model, the lithosphere east of Ross Island and the hinge forms a second half-plate, bearing little or none of the Ross Island volcanic load.

The Eggøyan eruption in 1732, Jan Mayen; an emerging ankaramitic surtseyjan type eruption

NASA Astrophysics Data System (ADS)

Gjerlxw, E.; Hoskuldsson, A.; Pedersen, R. B.; Thorseth, I. H.

2011-12-01

Jan Mayen is a volcanic island situated at 71°N and 8°W. The Island is build up of two main edifices, Sør Jan and Nord Jan (Beerenberg). Volcanic activity on the island is little known, and however at least 4 eruptions are documented at the island since early 18th century. An expedition to the island in summer 2011 reveals that first of these eruptions formed the tuffcone Eggøyan in 1732 AD. The Eggøyan tuffcone is situated at the north east foot of Beerenberg volcano, about 2.5 km from the coastline marked by Valberget. The tuffcone is about 1.5 km in diameter and emerges from about 35 m depth to reach the altitude of at least 217 m above sea level. Pre Eggøyan Lava flows on the sandy coast west of the edifice are covered by up to 1.6 m of ash some 3 km from the vent. These lava flows have been suggested to be formed in the 1732 eruption and the 1818 eruption of Jan Mayen. However, they are covered with the Eggøyan tephra and thus considerable older. Volcanic tephra from the Eggøyan eruption forms the uppermost tephra layer on the Eastern flanks of Beerenberg. Contemporary description of the 1732 eruption, tell of violent explosive eruption at the east side of Beerenberg observed by German whalers for 28 hours, while sailing past the island in May that year. A Dutch wailer group arriving to the island in June that year, report fine ash covering the island in such a way they sink up to mid leg into it. Our study this summer shows that the only eruption these descriptions can report to are the Eggøyan eruption, dating it precisely to the spring 1732. The eruptive products are made up of frothy glass and ol, cpx and opx crystals, which characterize the flank eruptions of Beerenberg. In this presentation we shall present first results of intense fragmentation of deep gas rich ankaramitic magma from the Jan Mayen are and its interaction with seawater in shallow coastal settings.

Earth Observation taken by the Expedition 29 crew

NASA Image and Video Library

2011-10-04

ISS029-E-041836 (4 Oct. 2011) --- South Shetland Islands and Antarctic Peninsula are featured in this image photographed by an Expedition 29 crew member on the International Space Station (ISS). The inclined equatorial orbit of the space station limits nadir Earth views?looking ?straight down? at the surface from the spacecraft?to latitudes between approximately 52 North and 52 South. When viewing conditions are ideal, the crew can obtain detailed oblique imagery?looking outwards at an angle from the space station?of regions at higher latitudes such as Greenland or, in this image, Antarctica. While the bulk of the continent of Antarctica is currently situated over the South Pole, the narrow Antarctic Peninsula extends like a finger towards the southern tip of South America. The northernmost part of the Peninsula is known as Graham Land, a small portion of which (located at approximately 64 South latitude) can be seen at top left in this photograph. Two of the South Shetland Islands that lay off the coast of Graham Land to the north-northwest, Livingston Island and Deception Island, are visible in the image. While both islands have a volcanic origin, active volcanism at Deception Island has been recorded since 1800; the last verified eruptive activity occurred in 1970. Closer to the coastline of Graham Land, Brabant Island (not considered to be part of the South Shetlands) also includes numerous outcrops of volcanic rock attesting to the complex tectonic history of the region. The space station was located over the South Atlantic Ocean, approximately 1,800 kilometers to the northeast in terms of its ground track, when this image was taken. This long viewing distance, combined with the highly oblique viewing angle, accentuates shadowing of the ground surface and provides a sense of the topography similar to the view one gets from an airplane. It also causes foreshortening of features visible in the image, making them appear closer to each other than they actually are ? for example, the actual distance between Livingston and Deception Islands is approximately 20 kilometers.

Seismic and gravity signature of the Ischia Island Caldera (Italy)

NASA Astrophysics Data System (ADS)

Capuano, P.; de Matteis, R.; Russo, G.

2009-04-01

The Campania (Italy) coasts are characterized by the presence of several volcanoes. The island of Ischia, located at the northwestern end of the Gulf of Naples, belongs to the Neapolitan Volcanic District together with Phlegrean Fields and Vesuvius, having all these Pleistocene volcanoes erupted in historical times, and it is characterized by diffuse hydrothermal phenomena The island represents the emergent part of a more extensive volcanic area developed mainly westward of the island, with underwater volcanoes aligned along regional fault patterns. The activity of Ischia volcano is testified by the occurrence of eruptions in historical times, the presence of intense hydrothermal phenomena, and by seismic activity (e.g. the 1883 Casamicciola earthquake). Ischia is populated by about 50,000 inhabitants increasing, mainly in the summer, due to thriving tourism business, partially due to its active volcanic state. Hazard assessment at active, densely populated volcanoes is critically based on knowledge of the volcanoes past behavior and the definition of its present state. As a contribution to the definition of the present state of the Ischia island volcano, we obtain a model of the shallow crust using geophysical observables through seismic tomography and 3D gravity inversion. In particular we use travel times collected during the Serapis experiment on the island and its surroundings and free air anomaly. A new 3D gravity inversion procedure has been developed to take better into account the shape and the effects of topography approximating it by a triangular mesh. Below each triangle, a sequence of triangular prisms is built, the uppermost prism having the upper face coincident with the triangle following the topography. The inversion is performed searching for a regularized solution using the minimum norm stabilizer. The main results inferable from the 3D seismic and gravity images are the definition of the caldera rims hypothesize by many authors along the perimeter of the island, with a less evidence on the southern part, and the presence of an high velocity/density area inside the caldera that is consistent with the lateral extension of a resurgent block affecting the most recent dynamic of the island

Volcanic ash plume identification using polarization lidar: Augustine eruption, Alaska

USGS Publications Warehouse

Sassen, Kenneth; Zhu, Jiang; Webley, Peter W.; Dean, K.; Cobb, Patrick

2007-01-01

During mid January to early February 2006, a series of explosive eruptions occurred at the Augustine volcanic island off the southern coast of Alaska. By early February a plume of volcanic ash was transported northward into the interior of Alaska. Satellite imagery and Puff volcanic ash transport model predictions confirm that the aerosol plume passed over a polarization lidar (0.694 mm wavelength) site at the Arctic Facility for Atmospheric Remote Sensing at the University of Alaska Fairbanks. For the first time, lidar linear depolarization ratios of 0.10 – 0.15 were measured in a fresh tropospheric volcanic plume, demonstrating that the nonspherical glass and mineral particles typical of volcanic eruptions generate strong laser depolarization. Thus, polarization lidars can identify the volcanic ash plumes that pose a threat to jet air traffic from the ground, aircraft, or potentially from Earth orbit.

A GIS-based methodology for the estimation of potential volcanic damage and its application to Tenerife Island, Spain

NASA Astrophysics Data System (ADS)

Scaini, C.; Felpeto, A.; Martí, J.; Carniel, R.

2014-05-01

This paper presents a GIS-based methodology to estimate damages produced by volcanic eruptions. The methodology is constituted by four parts: definition and simulation of eruptive scenarios, exposure analysis, vulnerability assessment and estimation of expected damages. Multi-hazard eruptive scenarios are defined for the Teide-Pico Viejo active volcanic complex, and simulated through the VORIS tool. The exposure analysis identifies the elements exposed to the hazard at stake and focuses on the relevant assets for the study area. The vulnerability analysis is based on previous studies on the built environment and complemented with the analysis of transportation and urban infrastructures. Damage assessment is performed associating a qualitative damage rating to each combination of hazard and vulnerability. This operation consists in a GIS-based overlap, performed for each hazardous phenomenon considered and for each element. The methodology is then automated into a GIS-based tool using an ArcGIS® program. Given the eruptive scenarios and the characteristics of the exposed elements, the tool produces expected damage maps. The tool is applied to the Icod Valley (North of Tenerife Island) which is likely to be affected by volcanic phenomena in case of eruption from both the Teide-Pico Viejo volcanic complex and North-West basaltic rift. Results are thematic maps of vulnerability and damage that can be displayed at different levels of detail, depending on the user preferences. The aim of the tool is to facilitate territorial planning and risk management in active volcanic areas.

2006 Volcanic Activity in Alaska, Kamchatka, and the Kurile Islands: Summary of Events and Response of the Alaska Volcano Observatory

USGS Publications Warehouse

Neal, Christina A.; McGimsey, Robert G.; Dixon, James P.; Manevich, Alexander; Rybin, Alexander

2008-01-01

The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, and volcanic unrest at or near nine separate volcanic centers in Alaska during 2006. A significant explosive eruption at Augustine Volcano in Cook Inlet marked the first eruption within several hundred kilometers of principal population centers in Alaska since 1992. Glaciated Fourpeaked Mountain, a volcano thought to have been inactive in the Holocene, produced a phreatic eruption in the fall of 2006 and continued to emit copious amounts of volcanic gas into 2007. AVO staff also participated in hazard communication and monitoring of multiple eruptions at seven volcanoes in Russia as part of its collaborative role in the Kamchatka and Sakhalin Volcanic Eruption Response Teams.

Heterogeneity of hydrodynamic properties and groundwater circulation of a coastal andesitic volcanic aquifer controlled by tectonic induced faults and rock fracturing - Martinique island (Lesser Antilles - FWI)

NASA Astrophysics Data System (ADS)

Vittecoq, B.; Reninger, P. A.; Violette, S.; Martelet, G.; Dewandel, B.; Audru, J. C.

2015-10-01

We conducted a multidisciplinary study to analyze the structure and the hydrogeological functioning of an andesitic coastal aquifer and to highlight the importance of faults and associated rock fracturing on groundwater flow. A helicopter-borne geophysical survey with an unprecedented resolution (SkyTEM) was flown over this aquifer in 2013. TDEM resistivity, total magnetic intensity, geological and hydrogeological data from 30 boreholes and two pumping tests were correlated, including one which lasted an exceptional 15 months. We demonstrate that heterogeneous hydrodynamic properties and channelized flows result from tectonically-controlled aquifer compartmentalization along the structural directions of successive tectonic phases. Significant fracturing of the central compartment results in enhanced hydrodynamic properties of the aquifer and an inverse relationship between electrical resistivity and transmissivity. Basalts within the fractured compartment have lower resistivity and higher permeability than basalts outside the compartment. Pumping tests demonstrate that the key factor is the hydraulic conductivity contrast between compartments rather than the hydrodynamic properties of the fault structure. In addition, compartmentalization and associated transmissivity contrasts protect the aquifer from seawater intrusion. Finally, unlike basaltic volcanic islands, the age of the volcanic formations is not the key factor that determines hydrodynamic properties of andesitic islands. Basalts that are several million years old (15 Ma here) have favorable hydrodynamic properties that are generated or maintained by earthquakes/faulting that result from active subduction beneath these islands, which is superimposed on their primary permeability.

An extended monitoring network for the volcanoes of St. Eustatius and Saba, the Caribbean Netherlands.

NASA Astrophysics Data System (ADS)

de Zeeuw-van Dalfsen, Elske; Sleeman, Reinoud; Evers, Läslo G.

2017-04-01

The volcanoes of the Quill (St. Eustatius) and Mt. Scenery (Saba) are part of the Lesser Antilles volcanic island arc in the West Indies, which hosts seventeen active volcanoes. The last eruptive activity at the Quill occurred 1600-1800 years ago but Mt. Scenery erupted as recent as in 1640. The existence of heated groundwater at St. Eustatius and hot springs at Saba indicate that both the Quill and Mt. Scenery are active, but quiet, rather than extinct. Volcanic hazard is therefore present and monitoring of these volcanoes of utmost importance. Especially considering the fact that Soufrière Hills volcano, at the neighbouring island of Montserrat and of comparable nature to Mt. Scenery, started to erupt in 1995 after 450 years of quietness. Currently, a network of four broadband seismometers is operational at each island. Seismic data are transmitted in real-time to the Royal Netherlands Meteorological Institute (KNMI), where they are (automatically) analysed. We plan to extend this monitoring effort by adding integrated geodetic observations (campaign and continuous GPS, InSAR) and temperature measurements of the hot springs. Furthermore we intend to improve our understanding of the terrain and surface geology by thorough analysis of a TanDEM-X DEM. An improved geophysical characterization of the islands is of great importance both for the population and local governments. These combined efforts will greatly improve the chance to observe the onset and follow the evolution of a future volcanic crisis.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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

Gravity anomalies of the Northern Hawaiian Islands: Implications on the shield evolutions of Kauai and Niihau

NASA Astrophysics Data System (ADS)

Flinders, Ashton F.; Ito, Garrett; Garcia, Michael O.

2010-08-01

New land and marine gravity data reveal two positive residual gravity anomalies in the Northern Hawaiian Islands: one over Kaua'i, the other between the islands of Kaua'i and Ni'ihau. These gravitational highs are similar in size and magnitude to those of other Hawaiian volcanoes, indicating local zones of high-density crust, attributed to olivine cumulates in solidified magma reservoirs. The residual gravity high over Kaua'i is located in the Līhu'e Basin, offset 8-12 km east of Kaua'i's geologically mapped caldera. This offset suggests that the mapped caldera is a collapsed feature later filled in with lava and not the long-term center of Kaua'i shield volcanism. A second residual gravity high, in the submarine channel between Kaua'i and Ni'ihau, marks the volcanic center of the Ni'ihau shield volcano. This second residual gravity anomaly implies that Ni'ihau's eastern boundary extended ˜20 km east of its present location. Through inversion, the residual gravity anomalies were modeled as being produced by two solidified magma reservoirs with average densities of 3100 kg/m3 and volumes between 2470 and 2540 km3. Considering the locations and sizes of the residual gravity anomalies/magma reservoirs, the extent of the two islands' paleoshorelines and potassium-argon dating of shield-stage lavas, we conclude that the two islands were not connected subaerially during their respective shield stages and that Ni'ihau's topographic summit was removed by an eastern flank collapse between 4.3 and 5.6 Ma. Continued constructional volcanism on western Kaua'i likely covered much of the submerged remains of eastern Ni'ihau.

Dissolved gas geochemical signatures of the ground waters related to the 2011 El Hierro magmatic reactivation

NASA Astrophysics Data System (ADS)

Rodríguez, F.; Hernández, P. A.; Padrón, E.; Pérez, N. M.; Sumino, H.; Melián, G. V.; Padilla, G. D.; Barrancos, J.; Dionis, S.; Nolasco, D.; Calvo, D.; Hernández, I.; Peraza, M. D.

2012-04-01

El Hierro Island is the south westernmost and the youngest island of the Canary archipelago (<1.2 My). Since 16 July, an anomalous seismicity at El Hierro Island was recorded by IGN seismic network. After the occurrence of more than 10,000 seismic events, volcanic tremor was recorded since 05:15 on October 10, by all of the seismic stations on the island, with highest amplitudes recorded in the southernmost station. During the afternoon of 12 October a large light-green coloured area was observed in the sea to the south of La Restinga village (at the southernmost part of El Hierro island), suggesting the existence of a submarine eruption. Since October 12, frequent episodes of, turbulent gas emission and foaming, and the appearance of steamy lava fragments has been observed on the sea surface. Instituto Volcanologico de Canarias (INVOLCAN) started a hydrogeochemical program on August 2011 in order to evaluate the temporal evolution of dissolved gases on four different observation points (vertical and horizontal wells) of El Hierro. Three wells are located on the north of the island (where the seismic activity occurred at the beginning of the volcano-seismic unrest) and one horizontal well (gallery) in the south. At each observation point the concentration of dissolved helium, CO2, N2, O2 and Ar and the isotopic composition of He, C-CO2 and Ar have been measured three times per week. Significant increases on the dissolved gases content, mainly on CO2 and He/CO2 ratio, have been measured at all the observation points prior to the increasing of released seismic energy. Isotopic composition of dissolved helium, measured as 3He/4He ratio, showed an significant increase (from 1-3 RA up to 7.2 RA, being RA the isotopic 3He/4He ratio on air) at all the observation points 20 days before the occurrence of the submarine eruption and these relatively high 3He/4He values have been maintained along the volcanic unrest period. The isotopic composition of CO2 has showed also significant changes in relation to the release of seismic energy. The results observed on this dissolved gases study have been tremendously beneficial on the volcanic surveillance tools to study and forecast the evolution of the seismic-volcanic crisis.

Mineralogical and Biogeochemical Characteristics of Rhodolith from Wu Island, Jeju-do, Korea

NASA Astrophysics Data System (ADS)

Roh, Y.; Kang, S.; Roh, E. H.

2012-12-01

This study focused on investigation of mineralogical and biogeochemical characteristics of the rhodoliths and examination of the rhodolith origin whether they were formed by chemical or biological processes. Rhodoliths are free-living forms of calcareous, coralline red algae formed under specific environmental conditions, but their formation processes are still controversial. The rhodoliths and sea water were sampled at Seogwang-ri coast in the western part of Wu Island, Jeju-do, Korea. The chemical compositions and pHs of sea water were measured by ICP-AES and pH meter. Microorganisms enriched from rhodoliths were aerobically cultured at room temperature in D-1 media containing various concentrations (0, 30, 100 mM) of Ca and Mg-acetate, and the microorganisms were analyzed by 16S rRNA gene DGGE analysis to confirm microbial diversity. Mineralogical characteristics of the rhodoliths and precipitates formed by the enriched microorganisms were determined by XRF, XRD, and SEM-EDS analyses. The sea water had a range of pH 6 to 7, and consisted of approximately 400 mg/L of Ca and 1200 mg/L of Mg which are low to form carbonate minerals by chemical process in natural environments. XRF and XRD analyses showed the rhodoliths mainly consisted of 46% CaO and 5 % MgO and mineralogy is Mg-rich calcite. A 16S rRNA sequence analysis showed the enriched microorganisms contained a carbonate forming microorganism, Proteus mirabilis. The enriched microorganisms precipitated carbonate minerals using D-1 media containing Ca- and Mg-acetate (30, 100 mM) and mineralogy of the precipitated carbonate mineral was Mg-rich calcite, whereas the microorganisms did not form carbonate minerals without Ca- and Mg-acetate in D-1 media. SEM-EDS analyses showed that the Mg-rich calcite formed by the microorganisms had a rhombohedron shape. And the Mg-rich calcite consisted of Ca, Si and Mg with extracellular polymeric substance (EPS). These results indicate that the rhodoliths at Seogwang-ri coast could be formed biologically and the microorganisms induce precipitation of Mg-rich calcite on the cell walls and EPS via the accumulation of Ca and/or Mg ions on the cells. The study of the natural analogues, rhodolith beach, complements laboratory experiments and possibly provides opportunity to constrain the mechanisms for CO2-bearing phases to form via biological processes.

Preliminary paleomagnetic and rock magnetic results from 17 to 22 ka sediment of Jeju Island, Korea: Geomagnetic excursional behavior or rock magnetic anomalies?

NASA Astrophysics Data System (ADS)

Ahn, Hyeon-Seon; Sohn, Young Kwan; Lee, Jin-Young; Kim, Jin Cheul

2018-05-01

Paleomagnetic and rock magnetic investigations were performed on a 64-cm-thick section of nonmarine unconsolidated muddy sediment from the Gosan Formation on Jeju Island, Korea. This sediment was recently dated to have been deposited between 22 and 17 kyr BP calibrated, with a sedimentation rate of 13-25 cm/kyr, based on many radiocarbon ages. Interestingly, stepwise alternating field (AF) demagnetization revealed characteristic natural remanent magnetizations with anomalous directions, manifested by marked deviations from the direction of today's axial dipole field, for some separate depth levels. On the other hand, stepwise thermal (TH) demagnetization showed more complex behavior, resulting in the identification of multiple remanence components. For all TH-treated specimens, consistently two different components are predominant: a low-temperature component unblocked below 240-320 °C entirely having normal-polarity apparently within the secular variation range of the Brunhes Chron, and a high-temperature component with unblocking temperatures (Tubs) between 240-320 and 520-580 °C that have anomalous directions, concentrated in the 13-34-cm-depth interval ( 17-19 ka in inferred age) and possibly below 53 cm depth (before 20 ka). Rock magnetic results also infer the dominance of low-coercivity magnetic particles having 300 and 580 °C Curie temperature as remanence carriers, suggestive of (titano)maghemite and/or Ti-rich titanomagnetite and magnetite (or Ti-poor titanomagnetite), respectively. A noteworthy finding is that AF demagnetizations in this study often lead to incomplete separation of the two remanence components possibly due to their strongly overlapping AF spectra. The unusual directions do not appear to result from self-reversal remanences. Then, one interpretation is that the low-temperature components are attributable to post-depositional chemical remanences, associated possibly with the later formation of the mineral phase having Tub 300 °C, whereas the high-temperature components are of primary detrital origin that survived later chemical influence. Accordingly, the unusual directions might record geomagnetic instability within the 17-22 ka period manifested by multiple excursional swings, partly associated with the Tianchi/Hilina Pali excursion. However, further work is needed to verify this interpretation and distinguish it from alternative explanations that invoke rock magnetic complexities as the cause of the unusual directions.[Figure not available: see fulltext.

Anti-inflammatory activity of a sulfated polysaccharide isolated from an enzymatic digest of brown seaweed Sargassum horneri in RAW 264.7 cells.

PubMed

Sanjeewa, Kalu Kapuge Asanka; Fernando, Ilekkuttige Priyan Shanura; Kim, Eun-A; Ahn, Ginnae; Jee, Youngheun; Jeon, You-Jin

2017-02-01

Sargassum horneri is an edible brown alga that grows in the subtidal zone as an annual species along the coasts of South Korea, China, and Japan. Recently, an extreme amount of S. horneri moved into the coasts of Jeju Island from the east coast of China, which made huge economic and environmental loss to the Jeju Island. Thus, utilization of this biomass becomes a big issue with the local authorities. Therefore, the present study was performed to evaluate the anti-inflammatory potential of crude polysaccharides (CPs) extracted from S. horneri China strain in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. CPs were precipitated from S. horneri digests prepared by enzyme assistant extraction using four food-grade enzymes (AMG, Celluclast, Viscozyme, and Alcalase). The production levels of nitric oxide (NO) and pro-inflammatory cytokines, including tumor necrosis factor (TNF)-α and interleukin (IL)-1β were measured by Griess assay and enzyme-linked immunosorbent assay, respectively. The levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), nuclear factor (NF)-κB, and mitogen-activated protein kinases (MAPKs) were measured by using western blot. The IR spectrums of the CPs were recorded using a fourier transform infrared spectroscopy (FT-IR) spectrometer. The polysaccharides from the Celluclast enzyme digest (CCP) showed the highest inhibition of NO production in LPS-stimulated RAW 264.7 cells (IC 50 value: 95.7 µg/mL). Also, CCP dose-dependently down-regulated the protein expression levels of iNOS and COX-2 as well as the production of inflammatory cytokines, including TNF-α and IL-1β, compared to the only LPS-treated cells. In addition, CCP inhibited the activation of NF-κB p50 and p65 and the phosphorylation of MAPKs, including p38 and extracellular signal-regulated kinase, in LPS-stimulated RAW 264.7 cells. Furthermore, FT-IR analysis showed that the FT-IR spectrum of CCP is similar to that of commercial fucoidan. Our results suggest that CCP has anti-inflammatory activities and is a potential candidate for the formulation of a functional food ingredient or/and drug to treat inflammatory diseases.

Anti-inflammatory activity of a sulfated polysaccharide isolated from an enzymatic digest of brown seaweed Sargassum horneri in RAW 264.7 cells

PubMed Central

Sanjeewa, Kalu Kapuge Asanka; Fernando, Ilekkuttige Priyan Shanura; Kim, Eun-A; Jee, Youngheun

2017-01-01

BACKGROUND/OBJECTIVES Sargassum horneri is an edible brown alga that grows in the subtidal zone as an annual species along the coasts of South Korea, China, and Japan. Recently, an extreme amount of S. horneri moved into the coasts of Jeju Island from the east coast of China, which made huge economic and environmental loss to the Jeju Island. Thus, utilization of this biomass becomes a big issue with the local authorities. Therefore, the present study was performed to evaluate the anti-inflammatory potential of crude polysaccharides (CPs) extracted from S. horneri China strain in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. MATERIALS/METHODS CPs were precipitated from S. horneri digests prepared by enzyme assistant extraction using four food-grade enzymes (AMG, Celluclast, Viscozyme, and Alcalase). The production levels of nitric oxide (NO) and pro-inflammatory cytokines, including tumor necrosis factor (TNF)-α and interleukin (IL)-1β were measured by Griess assay and enzyme-linked immunosorbent assay, respectively. The levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), nuclear factor (NF)-κB, and mitogen-activated protein kinases (MAPKs) were measured by using western blot. The IR spectrums of the CPs were recorded using a fourier transform infrared spectroscopy (FT-IR) spectrometer. RESULTS The polysaccharides from the Celluclast enzyme digest (CCP) showed the highest inhibition of NO production in LPS-stimulated RAW 264.7 cells (IC50 value: 95.7 µg/mL). Also, CCP dose-dependently down-regulated the protein expression levels of iNOS and COX-2 as well as the production of inflammatory cytokines, including TNF-α and IL-1β, compared to the only LPS-treated cells. In addition, CCP inhibited the activation of NF-κB p50 and p65 and the phosphorylation of MAPKs, including p38 and extracellular signal-regulated kinase, in LPS-stimulated RAW 264.7 cells. Furthermore, FT-IR analysis showed that the FT-IR spectrum of CCP is similar to that of commercial fucoidan. CONCLUSIONS Our results suggest that CCP has anti-inflammatory activities and is a potential candidate for the formulation of a functional food ingredient or/and drug to treat inflammatory diseases. PMID:28194259

Subsidence and current strain patterns on Tenerife Island (Canary Archipelago, Spain) derived from continuous GNSS time series (2008-2015)

NASA Astrophysics Data System (ADS)

Sánchez-Alzola, A.; Martí, J.; García-Yeguas, A.; Gil, A. J.

2016-11-01

In this paper we present the current crustal deformation model of Tenerife Island derived from daily CGPS time series processing (2008-2015). Our results include the position time series, a global velocity estimation and the current crustal deformation on the island in terms of strain tensors. We detect a measurable subsidence of 1.5-2 mm/yr. in the proximities of the Cañadas-Teide-Pico Viejo (CTPV) complex. These values are higher in the central part of the complex and could be explained by a lateral spreading of the elastic lithosphere combined with the effect of the drastic descent of the water table in the island experienced during recent decades. The results show that the Anaga massif is stable in both its horizontal and vertical components. The strain tensor analysis shows a 70 nstrain/yr. E-W compression in the central complex, perpendicular to the 2004 sismo-volcanic area, and 50 nstrain/yr. SW-NE extension towards the Northeast ridge. The residual velocity and strain patterns coincide with a decline in volcanic activity since the 2004 unrest.

Source identification of soil mercury in the Spanish islands.

PubMed

Rodríguez Martín, José Antonio; Carbonell, Gregoria; Nanos, Nikos; Gutiérrez, Carmen

2013-02-01

This study spatially analysed the relation between mercury (Hg) content in soil and Hg in rock fragment for the purpose of assessing natural soil Hg contribution compared with Hg from human inputs. We present the Hg content of 318 soil and rock fragment samples from 11 islands distributed into two Spanish archipelagos (the volcanic Canary Islands [Canaries] and the Mediterranean Balearic [Balearic] islands). Assumedly both are located far enough away from continental Hg sources to be able to minimise the effects of diffuse pollution. Physical and chemical soil properties were also specified for the samples. Hg contents were significantly greater in the Balearic limestone soils (61 μg kg(-1)) than in the volcanic soils of the Canaries (33 μg kg(-1)). Hg levels were also greater in topsoil than in rocky fragments, especially on the Balearics. The soil-to-rock ratios varied between 1 and 30. Interestingly, the highest topsoil-to-rock Hg ratio (>16 ×) was found in the vicinity of a coal-fired power plant in Majorca, whereas no similar areas in the Canary archipelago were identified.

Post-eruption legacy effects and their implications for long-term recovery of the vegetation on Kasatochi Island, Alaska

USGS Publications Warehouse

Talbot, S. S.; Talbot, S.L.; Walker, L.R.

2010-01-01

We studied the vegetation of Kasatochi Island, central Aleutian Islands, to provide a general field assessment regarding the survival of plants, lichens, and fungi following a destructive volcanic eruption that occurred in 2008. Plant community data were analyzed using multivariate methods to explore the relationship between pre- and post-eruption plant cover; 5 major vegetation types were identified: Honckenya peploides beach, Festuca rubra cliff shelf, Lupinus nootkatensisFestuca rubra meadow, Leymus mollis bluff ridge (and beach), and Aleuria aurantia lower slope barrens. Our study provided a very unusual glimpse into the early stages of plant primary succession on a remote island where most of the vegetation was destroyed. Plants that apparently survived the eruption dominated early plant communities. Not surprisingly, the most diverse post-eruption community most closely resembled a widespread pre-eruption type. Microhabitats where early plant communities were found were distinct and apparently crucial in determining plant survival. Comparison with volcanic events in related boreal regions indicated some post-eruption pattern similarities. ?? 2010 Regents of the University of Colorado.

Geothermal exploration in Indonesia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Radja, V.T.

1984-03-01

Indonesia is blessed with geothermal resources. This fortunate aspect is directly related to the fact that the archipelago is an island arc created by a subduction zone. Evidence of geothermal activity is common throughout the Islands. Among the islands' many active volcanos are numerous geothermal phenomena. Almost half of the volcanic centers in Indonesia (88 out of 177 centers) contain fumarole and sulfatare features. A brief history of the exploration for geothermal energy in Indonesia is presented.

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

NASA Astrophysics Data System (ADS)

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

2013-12-01

Three oceanic volcano islands in the west of the Cape Verde archipelago are considered to have the highest levels of volcanic hazard in the archipelago: Fogo, Brava, and Santo Antao. Fogo has had frequent mainly effusive eruptions in historic time, the most recent in 1995, whilst Brava and Santo Antao have ongoing geothermal activity and felt earthquakes, and have experienced geologically recent violent explosive eruptions. Therefore, these three islands have been the focus of recent efforts to set up seismic networks to monitor their activity. Here we present the first results from these networks, and propose interpretations of the monitored seismic activity in terms of subsurface volcano structures, near-surface intrusive activity and seasonal controls on geothermal activity. In Fogo, most recorded seismic events are hydrothermal events. These show a strong seasonal variation, increasing during the summer rain season and decreasing afterwards. Rare volcano-tectonic (VT) events (0.1

Volcanic air pollution over the Island of Hawai'i: Emissions, dispersal, and composition. Association with respiratory symptoms and lung function in Hawai'i Island school children.

PubMed

Tam, Elizabeth; Miike, Rei; Labrenz, Susan; Sutton, A Jeff; Elias, Tamar; Davis, James; Chen, Yi-Leng; Tantisira, Kelan; Dockery, Douglas; Avol, Edward

2016-01-01

Kilauea Volcano on the Island of Hawai'i has erupted continuously since 1983, releasing approximately 300-12000metrictons per day of sulfur dioxide (SO2). SO2 interacts with water vapor to produce an acidic haze known locally as "vog". The combination of wind speed and direction, inversion layer height, and local terrain lead to heterogeneous and variable distribution of vog over the island, allowing study of respiratory effects associated with chronic vog exposure. We characterized the distribution and composition of vog over the Island of Hawai'i, and tested the hypotheses that chronic vog exposure (SO2 and acid) is associated with increased asthma prevalence, respiratory symptoms, and reduced pulmonary function in Hawai'i Island schoolchildren. We compiled data of volcanic emissions, wind speed, and wind direction over Hawai'i Island since 1992. Community-based researchers then measured 2- to 4-week integrated concentrations of SO2 and fine particulate mass and acidity in 4 exposure zones, from 2002 to 2005, when volcanic SO2 emissions averaged 1600metrictons per day. Concurrently, community researchers recruited schoolchildren in the 4th and 5th grades of 25 schools in the 4 vog exposure zones, to assess determinants of lung health, respiratory symptoms, and asthma prevalence. Environmental data suggested 4 different vog exposure zones with SO2, PM2.5, and particulate acid concentrations (mean±s.d.) as follows: 1) Low (0.3±0.2ppb, 2.5±1.2μg/m(3), 0.6±1.1nmolH+/m(3)), 2) Intermittent (1.6±1.8ppb, 2.8±1.5μg/m(3), 4.0±6.6nmolH+/m(3)), 3) Frequent (10.1±5.2ppb, 4.8±1.9μg/m(3), 4.3±6.7nmolH+/m(3)), and 4) Acid (1.2±0.4ppb, 7.2±2.3μg/m(3), 25.3±17.9nmolH+/m(3)). Participants (1957) in the 4 zones differed in race, prematurity, maternal smoking during pregnancy, environmental tobacco smoke exposure, presence of mold in the home, and physician-diagnosed asthma. Multivariable analysis showed an association between Acid vog exposure and cough and strongly suggested an association with FEV1/FVC <0.8, but not with diagnosis of asthma, or chronic persistent wheeze or bronchitis in the last 12months. Hawai'i Island's volcanic air pollution can be very acidic, but contains few co-contaminants originating from anthropogenic sources of air pollution. Chronic exposure to acid vog is associated with increased cough and possibly with reduced FEV1/FVC, but not with asthma or bronchitis. Further study is needed to better understand how volcanic air pollution interacts with host and environmental factors to affect respiratory symptoms, lung function, and lung growth, and to determine acute effects of episodes of increased emissions. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Petrology and Geochronology of Kaula Volcano lavas: An off-axis window into the Hawaiian Mantle Plume

NASA Astrophysics Data System (ADS)

Garcia, M. O.; Weis, D.; Jicha, B. R.; Tree, J. P.; Bizimis, M.

2014-12-01

The Hawaiian Islands extend NW for 625 km from Lō'ihi to Ka'ula island. One anomalous feature cross-cutting the Hawaiian Islands is the Kaua'i Ridge, a 165 km-long bathymetric high with three well-defined gravity highs. These gravity highs are centered under or near the islands of Ka'ula, Ni'ihau and Kaua'i, and represent the cores of three shield volcanoes whose volumes decrease dramatically with distance from the axis of the Hawaiian Chain (Kaua'i, 58 x 103 km3, Ni'ihau x 103 km, Ka'ula 10 x 103 km; Robinson and Eakins 2006). Ka'ula Volcano, on the SW end of the Kaua'i Ridge, is centered 100 km off the axis of the Hawaiian mantle plume. The volcano is capped by a small island, which is a remnant of a nephelinitic tuff cone. The cone contains abundant accidental bombs of lava (tholeiite, phonolite and basanite), peridotite and pyroxenite, and unexploded ordnance from US military bombing. Two JASON dives on the flanks of Ka'ula recovered only alkalic lavas. Three stage of Ka'ula volcanism have been identified from sampling the volcanic bombs and flanks of the volcano. These rocks were dated using 40Ar/39Ar methods for the basalts and K-Ar for the phonolites. A tholeiitic shield basalt yielded an age of 6.2 Ma, the oldest reliable age for any Hawaiian Island tholeiite. Post-shield phonolites gave ages of 4.0 to 4.2 Ma (Garcia et al., 1986) and rejuvenation stage alkalic basalts yielded ages of 1.9 to 0.5 Ma. These ages are nearly identical to those for the same stages for adjacent Ni'ihau volcano but slightly older than on Kauai, 100 km to the NE (Sherrod et al. 2007). Thus, volcanism was nearly simultaneous along Kaua'i Ridge. The new age results extend to 420 km the distance within the Hawaiian Islands that experienced coeval rejuvenated volcanism. Geochemically, the rejuvenated and tholeiitic lavas from the Kaua'i Ridge are very similar with mixed source signatures of Loa and Kea trend compositions. Mixed Loa-Kea sources have been found for many other Hawaiian volcanoes. These results indicate that the Hawaiian mantle plume was broadly homogeneous over 100 km distance but also heterogeneous on a fine scale. Garcia et al., 1986. Contr. Mineral. Petrol. 94, 461-471; Robinson and Eakins, 2006. J. Volcanol. Geotherm. Res. 151, 309-317; Sherrod et al., 2007. USGS Open-File Rept. 2007-1089.

On the carcinogenic polycyclic aromatic hydrocarbon benzo(a)pyrene in volcano exhausts.

PubMed

Ilnitsky, A P; Belitsky, G A; Shabad, L M

1976-05-01

The content of benzo(a)pyrene in the juvenile ashes of the volcano Tyatya (Kunashir Island, Kuriles) and in the soil, vegetation and volcanic mud collected near volcanos in Kamchatka was studied. It was concluded that volcanic activity does not play a large role in forming the background level of this carcinogen in the human environment.

Petrogenesis of Late Cretaceous lava flows from a Ceno-Tethyan island arc: The Raskoh arc, Balochistan, Pakistan

NASA Astrophysics Data System (ADS)

Siddiqui, Rehanul Haq; Qasim Jan, M.; Asif Khan, M.

2012-10-01

The Raskoh arc is about 250 km long, 40 km wide and trends in an ENE direction. The oldest rock unit in the Raskoh arc is an accretionary complex (Early to Late Jurassic), which is followed in age by Kuchakki Volcanic Group, the most wide spread unit of the Raskoh arc. The Volcanic Group is mainly composed of basaltic to andesitic lava flows and volcaniclastics, including agglomerate, volcanic conglomerate, breccia and tuff, with subordinate shale, sandstone, limestone and chert. The flows generally form 3-15 m thick lenticular bodies but rarely reach up to 300 m. They are mainly basaltic-andesites with minor basalts and andesites. The main textures exhibited by these rocks are hypocrystalline porphyritic, subcumulophyric and intergranular. The phenocrysts comprise mainly plagioclase (An30-54 in Nok Chah and An56-64 in Bunap). They are embedded in a micro-cryptocrystalline groundmass having the same minerals. Apatite, magnetite, titanomagnetite and hematite occur as accessory minerals. Major, trace and rare earth elements suggest that the volcanics are oceanic island arc tholeiites. Their low Mg # (42-56) and higher FeO (total)/MgO (1.24-2.67) ratios indicate that the parent magma of these rocks was not directly derived from a mantle source but fractionated in an upper level magma chamber. The trace element patterns show enrichment in LILE and depletion in HFSE relative to N-MORB. Their primordial mantle-normalized trace element patterns show marked negative Nb anomalies with positive spikes on K, Ba and Sr which confirm their island arc signatures. Slightly depleted LREE to flat chondrite normalized REE patterns further support this interpretation. The Zr versus Zr/Y and Cr versus Y studies show that their parent magma was generated by 20-30% melting of a depleted mantle source. The trace elements ratios including Zr/Y (1.73-3.10), Ti/Zr (81.59-101.83), Ti/V (12.39-30.34), La/YbN (0.74-2.69), Ta/Yb (0.02-0.05) and Th/Yb (0.11-0.75) of the volcanics are more consistent with oceanic island arcs rather than continental margin arcs. It is suggested that the Raskoh arc is an oceanic island arc which formed due to the intra-oceanic convergence in the Ceno-Tethys during the Late Cretaceous rather than constructed on the southern continental margin of the Afghan block, as claimed by previous workers. It is further suggested that the Semail, Zagros, Chagai-Raskoh, Muslim Bagh, and Waziristan island arcs were developed in a single but segmented Cretaceous Ceno-Tethyan convergence zone.

Suprasubduction volcanic rocks of the Char ophiolite belt, East Kazakhstan: new geochemical and first geochronological data

NASA Astrophysics Data System (ADS)

Safonova, Inna; Simonov, Vladimir; Seltmann, Reimar; Yamamoto, Shinji; Xiao, Wenjiao

2016-04-01

The Char ophiolite belt is located in the western Central Asian Orogenic Belt, a world largest accretionary orogen, which has evolved during more than 800 Ma. The Char belt formed during Kazakhstan - Siberia collision. It has been known for hosting fragments of Late Devonian-Early Carboniferous oceanic crust, MORB, OPB and OIB, of the Paleo-Asian Ocean (Safonova et al., 2012). The Char is surrounded by two Paleozoic island-arc terranes: Zharma-Saur in the west and Rudny Altai in the east, however, until recent times, no island-arc units have been found within it. We were the first to find island-arc units as tectonic sheets occurring adjacent to those consisting of oceanic rocks. In places, island-arc andesites cut oceanic basalts. The Char volcanic and subvolcanic rocks of a probable suprasubduction origin are basalt, microgabbro, dolerite, andesite, tonalite and dacite. The mafic to andesitic volcanics possessing low TiO2 (0.85 wt.%av.) and show MgO vs. major elements crystallization trends suggesting two magma series: tholeiitic and calc-alkaline. The tholeiitic varieties are less enriched in incompatible elements then the calc-alkaline ones. Two samples are high-Mg and low-Ti andesibasalts similar to boninites. The rocks possess moderately LREE enriched rare-earth element patterns and are characterized by negative Nb anomalies present on the multi-element spectra (Nb/Lapm = 0.14-0.47; Nb/Thpm = 0.7-1.6).The distribution of rare-earth elements (La/Smn = 0.8-2.3, Gd/Ybn = 0.7-1.9) and the results of geochemical modeling in the Nb-Yb system suggest high degrees of melting of a depleted harzburgite-bearing mantle source at spinel facies depths. Fractional crystallization of clinopyroxene, plagioclase and opaque minerals also affected the final composition of the volcanic rocks. Clinopyroxene monomineral thermometry indicates crystallization of melts at 1020-1180°C. Melt inclusion composition based numerical calculations show that primary melts were derived at 1350-1530°C and 14-26 kbar and crystallized at 1150-1190°C (Simonov et al., 2010). All these features are indicative of a supra-subduction origin of rocks. The age of gabbro, dolerite, andesite and tonalite was determined by LA ICP MS U-Pb zircon dating performed in the University of Kyoto, Japan. The andesites and tonalites yielded Carboniferous ages of ca. 322-336 Ma and the gabbro and dolerite appeared Devonian (387-395 Ma). Thus, the Char volcanic rocks possess geochemical signatures of supra-subduction magmas and could be derived at high degree melting of relatively shallow mantle sources. The volcanic units probably formed at one or two island-arcs or at an intra-oceanic arc and continental margin arc during the Middle Devonian - Mississippian. Later, the island-arc units were probably accreted to the active margin of the Kazakhstan continent. The work was supported by RFBR Project no. 16-05-00313. Contribution to IGCP#592 of UNESCO-IUGS. Safonova, I.Yu., Simonov V.A., Kurganskaya E.V., Obut O.T., Romer R.L., Seltmann R., 2012. Late Paleozoic oceanic basalts hosted by the Char suture-shear zone, East Kazakhstan: geological position, geochemistry, petrogenesis and tectonic setting. Journal of Asian Earth Sciences 49, 20-39. Simonov V.A., Safonova I.Yu., Kovyazin S.V., 2010. Petrogenesis of island-arc complexes of the Char zone, East Kazakhstan. Petrology 18, 59-72.

Maximum Historical Seismic Intensity Map of S. Miguel Island (azores)

NASA Astrophysics Data System (ADS)

Silveira, D.; Gaspar, J. L.; Ferreira, T.; Queiroz, G.

The Azores archipelago is situated in the Atlantic Ocean where the American, African and Eurasian lithospheric plates meet. The so-called Azores Triple Junction located in the area where the Terceira Rift, a NW-SE to WNW-ESE fault system with a dextral component, intersects the Mid-Atlantic Ridge, with an approximate N-S direction, dominates its geological setting. S. Miguel Island is located in the eastern segment of the Terceira Rift, showing a high diversity of volcanic and tectonic structures. It is the largest Azorean island and includes three active trachytic central volcanoes with caldera (Sete Cidades, Fogo and Furnas) placed in the intersection of the NW-SE Ter- ceira Rift regional faults with an E-W deep fault system thought to be a relic of a Mid-Atlantic Ridge transform fault. N-S and NE-SW faults also occur in this con- text. Basaltic cinder cones emplaced along NW-SE fractures link that major volcanic structures. The easternmost part of the island comprises an inactive trachytic central volcano (Povoação) and an old basaltic volcanic complex (Nordeste). Since the settle- ment of the island, early in the XV century, several destructive earthquakes occurred in the Azores region. At least 11 events hit S. Miguel Island with high intensity, some of which caused several deaths and significant damages. The analysis of historical documents allowed reconstructing the history and the impact of all those earthquakes and new intensity maps using the 1998 European Macrosseismic Scale were produced for each event. The data was then integrated in order to obtain the maximum historical seismic intensity map of S. Miguel. This tool is regarded as an important document for hazard assessment and risk mitigation taking in account that indicates the location of dangerous seismogenic zones and provides a comprehensive set of data to be applied in land-use planning, emergency planning and building construction.

Volcanic air pollution hazards in Hawaii

USGS Publications Warehouse

Elias, Tamar; Sutton, A. Jeff

2017-04-20

Noxious sulfur dioxide gas and other air pollutants emitted from Kīlauea Volcano on the Island of Hawai‘i react with oxygen, atmospheric moisture, and sunlight to produce volcanic smog (vog) and acid rain. Vog can negatively affect human health and agriculture, and acid rain can contaminate household water supplies by leaching metals from building and plumbing materials in rooftop rainwater-catchment systems. U.S. Geological Survey scientists, along with health professionals and local government officials are working together to better understand volcanic air pollution and to enhance public awareness of this hazard.

Volcanic Air Pollution - A Hazard in Hawai'i

USGS Publications Warehouse

Sutton, Jeff; Elias, Tamar; Hendley, James W.; Stauffer, Peter H.

1997-01-01

Noxious sulfur dioxide gas and other pollutants emitted from Kilauea Volcano on the Island of Hawai'i react with oxygen and atmospheric moisture to produce volcanic smog (vog) and acid rain. Vog poses a health hazard by aggravating preexisting respiratory ailments, and acid rain damages crops and can leach lead into household water supplies. The U.S. Geological Survey's Hawaiian Volcano Observatory is closely monitoring gas emissions from Kilauea and working with health professionals and local officials to better understand volcanic air pollution and to enhance public awareness of this hazard.

Accelerating late Quaternary uplift of the New Georgia Island Group (Solomon island arc) in response to subduction of the recently active Woodlark spreading center and Coleman seamount

NASA Astrophysics Data System (ADS)

Mann, Paul; Taylor, Frederick W.; Lagoe, Martin B.; Quarles, Andrew; Burr, G.

1998-10-01

The New Georgia Island Group of the Solomon Islands is one of four places where an active or recently active spreading ridge has subducted beneath an island arc. We have used coral reef terraces, paleobathymetry of Neogene sedimentary rocks, and existing marine geophysical data to constrain patterns of regional Quaternary deformation related to subduction of the recently active Woodlark spreading center and its overlying Coleman seamount. These combined data indicate the following vertical tectonic history for the central part of the New Georgia Island Group: (1) subsidence of the forearc region (Tetepare and Rendova Islands) to water depths of ˜1500 m and deposition of marine turbidites until after 270 ka; (2) late Quaternary uplift of the forearc to sea level and erosion of an unconformity; (3) subsidence of the forearc to ˜500 m BSL and deposition of bathyal sediments; and (4) uplift of the forearc above sea level with Holocene uplift rates up to at least 7.5 mm/yr on Tetepare and 5 mm/yr on Rendova. In the northeastern part of the New Georgia Island Group, our combined data indicate a slightly different tectonic history characterized by lower-amplitude vertical motions and a more recent change from subsidence to uplift. Barrier reefs formed around New Georgia and Vangunu Islands as they subsided >300 m. By 50-100 ka, subsidence was replaced by uplift that accelerated to Holocene rates of ˜1 mm/yr on the volcanic arc compared with rates up to ˜7.5 mm/yr in the forearc area of Tetepare and Rendova. Uplift mechanisms, such as thermal effects due to subduction of spreading ridges, tectonic erosion, or underplating of deeply subducted bathymetric features, are not likely to function on the 270-ka period that these uplift events have occurred in the New Georgia Island Group. A more likely uplift mechanism for the post-270-ka accelerating uplift of the forearc and volcanic arc of the New Georgia Island Group is progressive impingement of the Coleman seamount or other topographically prominent features on the subducting plate. Regional effects we relate to this ongoing subduction-related process include: (1) late Quaternary (post-270 ka), accelerating uplift of the Rendova-Tetepare forearc area in response to initial impingement of the Coleman seamount followed by exponentially increasing collisional contact between the forearc and seamount; (2) later Quaternary propagation of uplift arcward to include the volcanic arc as the area of collisional contact between the forearc and seamount increased; and (3) large-wavelength folding that has produced regional variations in late Holocene uplift rates observed in both forearc (southern Rendova, Tetepare) and volcanic arc (New Georgia Island) areas. We propose that the dominant tectonic effect of Coleman seamount impingement is horizontal shortening of the forearc and arc crust that is produced by strong coupling between the subducting seamount and the unsedimented crystalline forearc of the New Georgia Island Group. The horizontal forces due to mechanical resistance to subducting rugged ridge and seamount topography may have terminated spreading of the Woodlark spreading center entering the trench (Ghizo ridge) and converted it to a presently active strike-slip fault zone.

40Ar-39Ar Age Constraints on Volcanism and Tectonism in the Terror Rift of the Ross Sea, Antarctica

USGS Publications Warehouse

2007-01-01

Volcanic sills and dikes inferred from seismic reflection profiles and geophysical studies of the Ross Sea are thought to be related to the rift basins in the region, and their emplacement to be coeval with extension. However, lack of precise geochronology in the Terror Rift of the Ross Sea region has left these inferred relationships poorly constrained and has hindered neotectonic studies, because of the large temporal gaps between seismic reflectors of known ages. New 40Ar/39Ar geochronology presented here for submarine volcanic rocks provides better age constraints for neotectonic interpretations within the Terror Rift. Several samples from seamounts yielded young ages between 156 ± 21 and 122 ± 26 Ka. These ages support interpretations that extension within the Terror Rift was active at least through the Pleistocene. Three evenly spaced samples from the lowermost 100 m of Franklin Island range in age from 3.28 ± 0.04 to 3.73 ± 0.05 Ma. These age determinations demonstrate that construction of a small volcanic edifice such as Franklin Island took at least several hundred thousand years, and therefore that much larger ones in the Erebus Volcanic Province are likely to have taken considerably longer than previously inferred. This warrants caution in applying a limited number of age determinations to define the absolute ages of events in the Ross Sea region

Paleomagnetic investigation of some volcanic rocks from the McMurdo volcanic province, Antarctica

USGS Publications Warehouse

Mankinen, E.A.; Cox, A.

1988-01-01

Paleomagnetic data for lava flows from sporadic but long-lived eruptions in the McMurdo Sound region are combined with previously published geologic and geochronologic data to determine the general eruptive sequence of the area. Lava flows in the Walcott Bay area were erupted during the Gauss Normal, Matuyama Reversed, and Brunhes Normal Polarity Chrons. The youngest flows on Black Island probably erupted near the boundary between the Gilbert and Gauss chrons. The most recent activity was concentrated on the volcanic edifices of Mounts Morning and Discovery and on Ross Island sampled during this study with those of eight flows that were published previously yields a mean paleomagnetic pole at 87.3??N, 317.3??E (??95 = 6.3??). The ancient geomagnetic field dispersion about this mean pole is 23.5??, with upper and lower limits of 95% confidence equal to 27.4?? and 20.5??, respectively. This value probably is a reasonable estimate of secular variation for the Antarctic continent during Pliocene and Pleistocene time. -Authors

Seismic stability of the Duwamish River Delta, Seattle, Washington

USGS Publications Warehouse

Kayen, Robert E.; Barnhardt, Walter A.

2007-01-01

The delta front of the Duwamish River valley near Elliott Bay and Harbor Island is founded on young Holocene deposits shaped by sea-level rise, episodic volcanism, and seismicity. These river-mouth deposits are highly susceptible to seismic soil liquefaction and are potentially prone to submarine landsliding and disintegrative flow failure. A highly developed commercial-industrial corridor, extending from the City of Kent to the Elliott Bay/Harbor Island marine terminal facilities, is founded on the young Holocene deposits of the Duwamish River valley. The deposits of this Holocene delta have been shaped not only by relative sea-level rise but also by episodic volcanism and seismicity. Ground-penetrating radar (GPR), cores, in situ testing, and outcrops are being used to examine the delta stratigraphy and to infer how these deposits will respond to future volcanic eruptions and earthquakes in the region. A geotechnical investigation of these river-mouth deposits indicates high initial liquefaction susceptibility during earthquakes, and possibly the potential for unlimited-strain disintegrative flow failure of the delta front.

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

NASA Astrophysics Data System (ADS)

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

2014-06-01

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

Ground-based and airborne measurements of volcanic gas emissions at White Island in New Zealand

NASA Astrophysics Data System (ADS)

Tirpitz, Jan-Lukas; Poehler, Denis; Bobrowski, Nicole; Christenson, Bruce; Platt, Ulrich

2017-04-01

Quantitative understanding of volcanic gas emissions has twofold relevance for nature and society: 1) Variation in gas emission and/or in emitted gas ratios are tracers of the dynamic processes in the volcano interior indicating its activity. 2) Volcanic degassing plays an important role for the Earth's climate, for local sometimes even regional air quality and atmospheric chemistry. In autumn 2015, a campaign to White Island Volcano in New Zealand was organized to perform ground-based as well as airborne in-situ and remote sensing gas measurements of sulfur dioxide (SO2), carbon dioxide (CO2) and bromine monoxide (BrO). For all three gases the ratios and total emission rates were determined in different plume types and ages. An overview over the data will be presented with focus on the two most notable outcomes: 1) The first determination of the BrO/SO2 ratio in the White Island plume and a minimum estimate of the volcano's bromine emission rate; two of many parameters, which are important to assess the impact of volcanic degassing on the atmospheric halogen chemistry. 2) In-situ SO2 data was very successfully recorded with the PITSA, a prototype of a portable and cost-effective optical instrument. It is based on the principle of non-dispersive UV absorption spectroscopy and features different advantages over the customary electrochemical sensors, including a sub second response time, negligible cross sensitivities to other gases, and inherent calibration. The campaign data demonstrates the capabilities and limitations of the PITSA and shows, that it can be well applied as substitute for conventional electrochemical systems.

Constraint on the magma sources in Luzon Island Philippines by using P and S wave local seismic tomography

NASA Astrophysics Data System (ADS)

Nghia, N. C.; Huang, B. S.; Chen, P. F.

2017-12-01

The subduction of South China Sea beneath the Luzon Island has caused a complex setting of seismicity and magmatism because of the proposed ridge subduction and slab tearing. To constrain the validity of slab tearing induced by ridge subduction and their effect, we performed a P and S wave seismic tomography travel time inversion using LOTOS code. The dataset has been retrieved from International Seismological Centre from 1960 to 2008. A 1D velocity inverted by using VELEST with a Vp/Vs ratio of 1.74 is used as the starting input velocity for tomographic inversion. Total of 20905 P readings and 8126 S readings from 2355 earthquakes events were used to invert for velocity structure beneath Luzon Island. The horizontal tomographic results show low-velocity, high Vp/Vs regions at the shallow depth less than 50 km which are interpreted as the magmatic chambers of the volcanic system in Luzon. At the suspected region of slab tearing at 16oN to 18oN, two sources of magma have been indentified: slab window magma at shallow depth (< 50 km) and magma induced by mantle wedge partial melting from higher depth. This slab melting may have changed the composition of magmatic to become more silicic with high viscosity, which explains the volcanic gap in this region. At the region of 14oN to 15oN, large magma chambers under active volcanos are identified which explain the active volcanism in this region. Contrast to the region of slab tearing, in this region, the magma chambers are fed by only magma from partial melting of mantle wedge from the depth higher than 100 km. These observations are consistent with previous work on the slab tearing of South China Sea and the activities of volcanism in the Luzon Island.

Origin of three-armed rifts in volcanic islands: the case of El Hierro (Canary Islands)

NASA Astrophysics Data System (ADS)

Galindo Jiménez, Inés; Becerril Carretero, Laura; Martí Molist, Joan; Gudmundsson, Agust

2015-04-01

Rifts zones in volcanic oceanic islands are common structures that have been explained through several theories/models. However, despite all these models it is as yet unclear whether it is the intense intrusive activity or the sector collapses that actually control the structural evolution and geometry of oceanic-island rift zones. Here we provide a new hypothesis to explain the origin and characteristics of the feeding system of oceanic-island rift zones based on the analysis of more than 1700 surface, subsurface (water galleries), and submarine structural data from El Hierro (Canary Islands). El Hierro's geological structure is primarily controlled by a three-armed rift-zone, the arms striking NE, WSW and S. Between the rift axes there are three valleys formed during huge landslides: El Golfo, El Julan, and Las Playas. Our results show: (1) a predominant NE-SW strike of structural elements, which coincides with the main regional trend of the Canary Archipelago as a whole; (2) a clear radial strike distribution of structural elements for the whole volcanic edifice (including submarine flanks) with respect to the centre of the island; (3) that the rift zones are mainly subaerial structures and do not propagate through the submarine edifice; (4) that it is only in the NE rift that structures have a general strike similar to that of the rift as a whole, and; (5) that in the W and S rifts there is not clear main direction, showing the structural elements in the W rift a fan distribution coinciding with the general radial pattern in the island as a whole. Based on these data, we suggest that the radial-striking structures reflect comparatively uniform stress fields that operated during the constructive episodes, mainly conditioned by the combination of overburden pressure, gravitational spreading, and magma-induced stresses. By contrast, in the shallower parts of the edifice, that is, the NE-SW, N-S and WNW-ESE-striking structures, reflect local stress fields related to the formation of mega-landslides and mask the general radial pattern. Thus, the rift zones on El Hierro are shallow structures that commonly capture and divert ascending magma towards different parts of the island but do not condition magma ascent at depth.

Rejuvenescent Volcanism on San Cristóbal Island, Galápagos: A Late "Plumer"

NASA Astrophysics Data System (ADS)

Mahr, J.; Harpp, K. S.; Kurz, M. D.; Geist, D.; Bercovici, H.; Pimentel, R.; Cleary, Z.; Córdova Aguilar, M. D.

2016-12-01

Nestled between the two volcanoes of San Cristóbal Island in the Galápagos is a series of curiously young basaltic lava flows. These flows are not vegetated and have well-preserved flow tops, indicating that they are a rejuvenescent phase of volcanism. The young lava region covers 70 km2 of the NW coast and consists of five flow fields from 5 to 17 km2. We report new cosmogenic helium exposure ages that indicate emplacement occurred 9 to 15 ka, and that the surrounding area was active since 174 ka; a hiatus in activity may have occurred between 174 and 15 ka. These dates contrast with the fact that San Cristóbal is one of the oldest islands in the archipelago, with several K-Ar ages >2 Ma. Petrographically, the young lavas are mostly olivine-phyric (1-5 mm, average 5% abundance). Plagioclase phenocrysts are small (<1 mm) and rarely exceed 3% in abundance. Some flows range in their crystal cargo over rather short distances (<30 m). Compositional variation of this small set of young flows encompasses the compositional range exhibited by lavas from across the island. Rare earth element patterns are flat to LREE-enriched, even within the same flow field. Incompatible trace element ratios (e.g., La/Sm) indicate a wide range in extents of melting at relatively shallow depths (e.g., low Sm/Yb), comparable to conditions observed at Floreana Island. Compositions are consistent with a source that is a mixture of Galápagos plume and ancient, recycled oceanic crust (FLO source of Harpp and White, 2001). The contribution from the plume source is notable given the island's location in the eastern archipelago, where plume influence is normally lower than in the western islands. The young lavas are primitive compared to the majority of the archipelago and to other lavas on San Cristóbal, having only crystallized olivine and sparse CPX. These observations are consistent with a model in which melts pass through the crust relatively quickly, without extensive fractionation or homogenization prior to eruption. Because late stage lavas in the Galápagos have similar source compositions to the rest of the island, we propose that the mechanism for rejuvenescent volcanism in the Galápagos differs from that proposed for other ocean island systems, such as Hawai'i.

Diffuse CO2 fluxes from Santiago and Congro volcanic lakes (São Miguel, Azores archipelago)

NASA Astrophysics Data System (ADS)

Andrade, César; Cruz, José; Viveiros, Fátima; Branco, Rafael

2017-04-01

Diffuse CO2 degassing occurring in Santiago and Congro lakes, both located in depressions associated to maars from São Miguel Island (Azores, Portugal), was studied through detailed flux measurements. Four sampling campaigns were developed between 2013 and 2016 in each water body, split by the cold and wet seasons. São Miguel has an area of 744.6 km2, being the largest island of the archipelago. The geology of the island is dominated by three quiescent central volcanoes (Sete Cidades, Fogo and Furnas), linked by volcanic fissural zones (Picos and Congro Fissural Volcanic systems). The oldest volcanic systems of the island are located in its eastern part (Povoação-Nordeste). Santiago lake, with a surface area of 0.26 km2 and a depth of 30.5 m, is located inside a maar crater in the Sete Cidades volcano at an altitude of 355 m. The watershed of the lake has an area of 0.97 km2 and a surface flow estimated as 1.54x10 m3/a. A total of 1612 CO2 flux measurements using the accumulation chamber method were made at Santiago lake, 253 in the first campaign (November 2013), and 462, 475 and 422 in the three other campaigns, respectively, in April 2014, September 2016 and December 2016. The total CO2 flux estimated for this lake varies between 0.4 t d-1 and 0.59 t d-1, for the surveys performed, respectively, in November 2013 and September 2016; higher CO2 outputs of 1.57 and 5.87 t d-1 were calculated for the surveys carried out in April 2014 and December 2016. These higher CO2 emissions were associated with a period without water column stratification. Similarly to Santiago lake, Congro lake is located inside a maar, in the Congro Fissural Volcanic system, and has a surface area of 0.04 km2 with 18.5 m depth and a storage of about 2.4x105 m3/a. The lake, located at an altitude of 420 m, is fed by a watershed with an area of 0.33 km2 and a runoff estimated as about 8x104 m3/a. In Congro lake a total of 713 CO2 flux measurements were performed during four surveys from November 2013 to February 2016. The CO2 flux output was estimated as ranging between 0.06 t d-1 and 0.31 t d-1; the lower CO2 emission occurred in July 2015 and should reflect the stratification of the water column that prevents the CO2 flux release at the lake surface. Considering both volcanic lakes, the mean CO2 emissions, standardized per area, in the cold season were ˜14.9 t km-2 d-1 and ˜7.1 t km-2 d-1, respectively, for Santiago and Congro lakes. During summer period, CO2 emissions were lower in both lakes (˜1.9 t km-2 d-1 and ˜4.1 t km-2 d-1 for Santiago and Congro, correspondingly), what is explained by the lake stratification. Due to the organic processes that occur in the lakes, the CO2 emission is mostly associated to a biogenic origin, but a volcanic influence cannot be excluded and further research using carbon isotopic data is crucial to discriminate the CO2 sources. Key words: volcanic lakes, CO2 flux, maars, São Miguel Island

The autonomic control and functional significance of the changes in heart rate associated with air breathing in the jeju, Hoplerythrinus unitaeniatus.

PubMed

McKenzie, D J; Campbell, H A; Taylor, E W; Micheli, M; Rantin, F T; Abe, A S

2007-12-01

The jeju is a teleost fish with bimodal respiration that utilizes a modified swim bladder as an air-breathing organ (ABO). Like all air-breathing fish studied to date, jeju exhibit pronounced changes in heart rate (fH) during air-breathing events, and it is believed that these may facilitate oxygen uptake (MO2) from the ABO. The current study employed power spectral analysis (PSA) of fH patterns, coupled with instantaneous respirometry, to investigate the autonomic control of these phenomena and their functional significance for the efficacy of air breathing. The jeju obtained less than 5% of total MO2 (MtO2) from air breathing in normoxia at 26 degrees C, and PSA of beat-to-beat variability in fH revealed a pattern similar to that of unimodal water-breathing fish. In deep aquatic hypoxia (water PO2)=1 kPa) the jeju increased the frequency of air breathing (fAB) tenfold and maintained MtO2 unchanged from normoxia. This was associated with a significant increase in heart rate variability (HRV), each air breath (AB) being preceded by a brief bradycardia and then followed by a brief tachycardia. These fH changes are qualitatively similar to those associated with breathing in unimodal air-breathing vertebrates. Within 20 heartbeats after the AB, however, a beat-to-beat variability in fH typical of water-breathing fish was re-established. Pharmacological blockade revealed that both adrenergic and cholinergic tone increased simultaneously prior to each AB, and then decreased after it. However, modulation of inhibitory cholinergic tone was responsible for the major proportion of HRV, including the precise beat-to-beat modulation of fH around each AB. Pharmacological blockade of all variations in fH associated with air breathing in deep hypoxia did not, however, have a significant effect upon fAB or the regulation of MtO2. Thus, the functional significance of the profound HRV during air breathing remains a mystery.

Seventeen years of monitoring diffuse CO2 emission from the Tenerife North-West Rift Zone (NWRZ) volcano, Canary Islands

NASA Astrophysics Data System (ADS)

Padilla, Germán D.; Evans, Bethany J.; Provis, Aaron R.; Asensio, María; Alonso, Mar; Calvo, David; Hernández, Pedro; Pérez, Nemesio M.

2017-04-01

Tenerife together and Gran Canaria are the central islands of the Canarian archipelago, which have developed a central volcanic complex characterized by the eruption of differentiated magmas. Tenerife is the largest of the Canary Islands (2100 km2) and at present, the North-West Rift-Zone (NWRZ) is one of the most active volcanic structures of the three volcanic rift-zone of the island, which has hosted two historical eruptions (Arenas Negras in 1706 and Chinyero in 1909). In order to monitor the volcanic activity of NWRZ, since the year 2000, 49 soil CO2 efflux surveys have been performed at NWRZ (more than 300 observation sites each one) to evaluate the temporal an spatial variations of CO2 efflux and their relationships with the volcanic-seismic activity. Measurements were performed in accordance with the accumulation chamber method. Spatial distribution maps were constructed following the sequential Gaussian simulation (sGs) procedure. To quantify the total CO2 emission from the studied area, 100 simulations for each survey have been performed. We report herein the results of the last diffuse CO2 efflux surveys at the NWRZ undertaken in July and October 2016 to constrain the total CO2 output from the studied area. During July and October 2016 surveys, soil CO2 efflux values ranged from non-detectable up to 32.4 and 53.7 g m-2 d-1, respectively. The total diffuse CO2 output released to atmosphere were estimated at 255 ± 9 and 338 ± 18 t d-1, respectively, values higher than the background CO2 emission estimated on 144 t d-1. Since 2000, soil CO2 efflux values have ranged from non-detectable up to 141 g m-2 d-1, with the highest values measured in May 2005 whereas total CO2 output ranged between 52 and 867 t d-1. Long-term variations in the total CO2 output have shown a temporal correlation with the onsets of seismic activity at Tenerife, supporting unrest of the volcanic system, as is also suggested by anomalous seismic activity recorded in the studied area during April 22-29, 2004 and also during October 2-3, 2016. Spatial distribution of soil CO2 efflux values also showed changes in magnitude and amplitude, with higher CO2 efflux values measured along a trending WNW-ESE zone. Subsurface magma movement is proposed as a cause for the observed changes in the total output of diffuse CO2 emission as well as for the spatial distribution of soil CO2 efflux. The increasing trend of total CO2 output suggests increasing pressurization of the volcanic-hydrothermal system, a mechanism capable of triggering dyke intrusion along the NWRZ of Tenerife in the near future or futures changes in the seismicity. This study demonstrates the importance of performing soil CO2 efflux surveys as an effective surveillance volcanic tool.

Spatial distribution of helium isotopes in volcanic gases and thermal waters along the Vanuatu (New Hebrides) volcanic arc

NASA Astrophysics Data System (ADS)

Jean-Baptiste, P.; Allard, P.; Fourré, E.; Bani, P.; Calabrese, S.; Aiuppa, A.; Gauthier, P. J.; Parello, F.; Pelletier, B.; Garaebiti, E.

2016-08-01

We report the first helium isotope survey of volcanic gases, hot springs and some olivine phenocrysts along the Vanuatu island arc, from Tanna in the south to Vanua Lava in the north. Low CO2 content and low 3He/4He ratios in thermal fluids of Epi (4.0 ± 0.1 Ra), Efate (4.5 ± 0.1 Ra) and Pentecost (5.3 ± 0.5 Ra) islands coherently indicate reduced mantle gas leakage and crustal contamination by radiogenic helium on these extinct volcanic systems of the former (Pliocene) arc. Instead, presently active Vanuatu volcanoes display 3He/4He and C/3He ratios typical of subduction-related volcanic arcs: 3He/4He ratios range from 6.4 ± 0.5 Ra in southernmost Tanna and 7.23 ± 0.09 Ra in northernmost Vanua Lava to typical MORB values in the central islands of Gaua (7.68 ± 0.06 Ra), Ambrym (7.6 ± 0.8 Ra) and Ambae (7 ± 2 Ra in groundwaters, 7.9 ± 1.4 Ra in olivine phenocrysts, and 8.0 ± 0.1 Ra in summit fumaroles of Aoba volcano). On Ambrym, however, we discover that hydrothermal manifestations separated by only 10-15 km on both sides of a major E-W transverse fault zone crossing the island are fed by two distinct helium sources, with different 3He/4He signatures: while fluids in southwest Ambrym (Baiap and Sesivi areas) have typical arc ratios (7.6 ± 0.8 Ra), fluids on the northwest coast (Buama Bay area) display both higher 3He/4He ratios (9.8 ± 0.2 Ra in waters to 10.21 ± 0.08 Ra in bubbling gases) and lower C/3He ratios that evidence a hotspot influence. We thus infer that the influx of Indian MORB mantle beneath the central Vanuatu arc, from which Ambrym magmas originate, also involves a 3He-rich hotspot component, possibly linked to a westward influx of Samoan hotspot material or another yet unknown local source. This duality in magmatic He source at Ambrym fits with the bimodal composition and geochemistry of the erupted basalts, implying two distinct magma sources and feeding systems. More broadly, the wide He isotopic variations detected along the Vanuatu arc further verify the complex tectonic and magmatic framework of this intra-oceanic island arc.

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

USGS Publications Warehouse

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

2011-01-01

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

New Data on the Composition of Cretaceous Volcanic Rocks of the Alazeya Plateau, Northeastern Yakutia

NASA Astrophysics Data System (ADS)

Tsukanov, N. V.; Skolotnev, S. G.

2018-02-01

This work presents new data on the composition of volcanics, developed within the Alazeya Plateau of the Kolyma-Indigirka fold area (Northeast Russia), which indicate essential differences in their composition and, accordingly, different geodynamic settings of the formation of rocks. The studied igneous rocks are subdivided into two groups. Volcanics of the first group of the Late Cretaceous age, which are represented by differentiated volcanic rock series (from andesitobasalts to dacites and rhyolites), were formed under island arc conditions in the continent-ocean transition zone. Volcanics of the second group are ascribed to the tholeiitic series and were formed under the other geodynamic setting, which is associated with the regime of extension and riftogenesis, manifested in the studied area probably at the later stage.

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

USGS Publications Warehouse

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

2011-01-01

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

Comments on: Palaeoclimatic considerations of talus flatirons and aeolian deposits in Northern Fuerteventura volcanic island (Canary Islands, Spain). Mateo Gutiérrez-Elorza, Pedro Lucha, F.-Javier Gracia, Gloria Desir, CintaMarín, Nicole Petit-Maire

NASA Astrophysics Data System (ADS)

Faust, Dominik; Zöller, Ludwig; von Suchodoletz, Hans

2018-01-01

We would like to compliment the authors on this interesting description of some geomorphic elements found on the Canary Island of Fuerteventura. In addition, this paper is a wonderful review of some geomorphological work done in this part of the world, as based on selected papers and field work.

The Ischia volcanic island (Southern Italy): Inferences from potential field data interpretation

NASA Astrophysics Data System (ADS)

Paoletti, V.; Di Maio, R.; Cella, F.; Florio, G.; Motschka, K.; Roberti, N.; Secomandi, M.; Supper, R.; Fedi, M.; Rapolla, A.

2009-01-01

In this paper we present a study of the structural setting of the volcanic island of Ischia by the analysis and interpretation of high-resolution aeromagnetic and self-potential data recently acquired over the island. The magnetic data allowed us to locate the main anomaly sources and lineaments of the island and its offshore surroundings, while the self-potential (SP) data provided information on both the structural pattern of the resurgent caldera and the high-temperature fluid circulation. An inversion of the acquired magnetic and SP data, and a joint modelling of the magnetic data and of a previous gravity data set along a SW-NE profile allowed us to build a model of the island. The model is characterized by the presence of an igneous-very likely trachytic-structure, whose top is located at 1200-1750 m b.s.l. Such a body, possibly formed by several neighbouring intrusions, has a density contrast with the pyroclastic cover of about 0.4 gr/cm 3 and its central-western part, below Mt. Epomeo, seems to be demagnetized. The demagnetization should be connected to the high geothermal gradient measured in this portion of the island and may be due to hydro-chemical alteration processes and/or to the possible presence of partially melted spots within the intrusion. Our outcome is consistent with the results of previous geophysical, geo-volcanological and geothermal studies.

Helium and methane sources and fluxes of shallow submarine hydrothermal plumes near the Tokara Islands, Southern Japan

PubMed Central

Wen, Hsin-Yi; Sano, Yuji; Takahata, Naoto; Tomonaga, Yama; Ishida, Akizumi; Tanaka, Kentaro; Kagoshima, Takanori; Shirai, Kotaro; Ishibashi, Jun-ichiro; Yokose, Hisayoshi; Tsunogai, Urumu; Yang, Tsanyao F.

2016-01-01

Shallow submarine volcanoes have been newly discovered near the Tokara Islands, which are situated at the volcanic front of the northern Ryukyu Arc in southern Japan. Here, we report for the first time the volatile geochemistry of shallow hydrothermal plumes, which were sampled using a CTD-RMS system after analyzing water column images collected by multi-beam echo sounder surveys. These surveys were performed during the research cruise KS-14-10 of the R/V Shinsei Maru in a region stretching from the Wakamiko Crater to the Tokara Islands. The 3He flux and methane flux in the investigated area are estimated to be (0.99–2.6) × 104 atoms/cm2/sec and 6–60 t/yr, respectively. The methane in the region of the Tokara Islands is a mix between abiotic methane similar to that found in the East Pacific Rise and thermogenic one. Methane at the Wakamiko Crater is of abiotic origin but affected by isotopic fractionation through rapid microbial oxidation. The helium isotopes suggest the presence of subduction-type mantle helium at the Wakamiko Crater, while a larger crustal component is found close to the Tokara Islands. This suggests that the Tokara Islands submarine volcanoes are a key feature of the transition zone between the volcanic front and the spreading back-arc basin. PMID:27671524

Helium and methane sources and fluxes of shallow submarine hydrothermal plumes near the Tokara Islands, Southern Japan.

PubMed

Wen, Hsin-Yi; Sano, Yuji; Takahata, Naoto; Tomonaga, Yama; Ishida, Akizumi; Tanaka, Kentaro; Kagoshima, Takanori; Shirai, Kotaro; Ishibashi, Jun-Ichiro; Yokose, Hisayoshi; Tsunogai, Urumu; Yang, Tsanyao F

2016-09-27

Shallow submarine volcanoes have been newly discovered near the Tokara Islands, which are situated at the volcanic front of the northern Ryukyu Arc in southern Japan. Here, we report for the first time the volatile geochemistry of shallow hydrothermal plumes, which were sampled using a CTD-RMS system after analyzing water column images collected by multi-beam echo sounder surveys. These surveys were performed during the research cruise KS-14-10 of the R/V Shinsei Maru in a region stretching from the Wakamiko Crater to the Tokara Islands. The 3 He flux and methane flux in the investigated area are estimated to be (0.99-2.6) × 10 4 atoms/cm 2 /sec and 6-60 t/yr, respectively. The methane in the region of the Tokara Islands is a mix between abiotic methane similar to that found in the East Pacific Rise and thermogenic one. Methane at the Wakamiko Crater is of abiotic origin but affected by isotopic fractionation through rapid microbial oxidation. The helium isotopes suggest the presence of subduction-type mantle helium at the Wakamiko Crater, while a larger crustal component is found close to the Tokara Islands. This suggests that the Tokara Islands submarine volcanoes are a key feature of the transition zone between the volcanic front and the spreading back-arc basin.

Geochemical evidence of Saharan dust parent material for soils developed on Quaternary limestones of Caribbean and western Atlantic islands

USGS Publications Warehouse

Muhs, D.R.; Bush, C.A.; Stewart, K.C.; Rowland, T.R.; Crittenden, R.C.

1990-01-01

Most previous workers have regarded the insoluble residues of high-purity Quaternary limestones (coral reefs and oolites) as the most important parent material for well-developed, clay-rich soils on Caribbean and western Atlantic islands, but this genetic mechanism requires unreasonable amounts of limestone solution in Quaternary time. Other possible parent materials from external sources are volcanic ash from the Lesser Antilles island arc and Saharan dust carried across the Atlantic Ocean on the northeast trade winds. Soils on Quaternary coral terraces and carbonate eolianites on Barbados, Jamaica, the Florida Keys (United States), and New Providence Island (Bahamas) were studied to determine which, if either, external source was important. Caribbean volcanic ashes and Saharan dust can be clearly distinguished using ratios of relatively immobile elements ( Al2O3 TiO2, Ti Y, Ti Zr, and Ti Th). Comparison of these ratios in 25 soils, where estimated ages range from 125,000 to about 870,000 yr, shows that Saharan dust is the most important parent material for soils on all islands. These results indicate that the northeast trade winds have been an important component of the regional climatology for much of the Quaterary. Saharan dust may also be an important parent material for Caribbean island bauxites of much greater age. ?? 1990.

Geology and ground-water resources of the island of Molokai, Hawaii

USGS Publications Warehouse

Stearns, Harold T.; Macdonald, Gordon A.

1947-01-01

The island of Molokai is the fifth largest of the Hawaiian Islands, with an area of 250 square miles. It lies 25 miles southeast of Oahu, and 8.5 miles northwest of Maui. It consists of two principal parts, each a major volcanic mountain. East Molokai rises to 4,970 feet altitude. It is built largely of basaltic lavas, with a thin cap of andesites and a little trachyte. The volcanic rocks of East Molokai are named the East Molokai volcanic series, the basaltic part being separated as the lower member of the series, and the andesites and trachytes as the upper member. Large cinder cones and bulbous domes are associated with the lavas of the upper member. Thin beds of ash are present locally in both members. The lavas of the lower member are cut by innumerable dikes lying in two major rift zones trending eastward and northwestward. A large caldera, more than 4 miles long, and a smaller pit 0.8 mile across existed near the summit of the volcano. The rocks formed in and under the caldera are separated on plate 1 as the caldera complex. Stream erosion has cut large amphitheater-headed valleys into the northern coast of East Molokai, exposing the dikes and the caldera complex.West Molokai is lower than East Molokai, rising to 1,380 feet altitude. It was built by basaltic lavas erupted along rift zones trending southwestward and northwestward. Many of the flows were unusually fluid. The volcanic rocks of West Molokai Volcano are named the West Molokai volcanic series. Along its eastern side, the mountain is broken by a series of faults along which its eastern edge has been dropped downward. West Molokai Volcano became extinct earlier than East Molokai Volcano, and its flank is partly buried beneath lavas of East Molokai.Both volcanic mountains were built upward from the sea floor probably during Tertiary time. Following the close of volcanic activity stream erosion cut large canyons on East Molokai, but accomplished much less on drier West Molokai. Marine erosion attacked both parts of the island, producing high sea-cliffs on the windward coast. In late Tertiary or early Pleistocene time the island was submerged to a level at least 560 feet above the present shore line, then reemerged. Later shifts of sea level, probably partly resulting from Pleistocene glaciation and deglaciation, ranged from 300 feet below to 100 feet or more above present sea level. Marine deposits on the southern slope extend to an altitude of at least 200 feet. Eruption of the Kalaupapa basalt built a small lava cone at the foot of the northern cliff, forming Kalaupapa peninsula; and a small submarine eruption off the eastern end of Molokai built the Mokuhooniki tuff cone, the fragments of which now form Hooniki and Kanaha Islands. Deposition of marine and fluviatile sediments has built a series of narrow flats close to sea-level along the southern coast. Nearly the entire island is underlain, close to sea level, by ground water of the basal zone of saturation. Beneath West Molokai, the Hoolehua Plain between West and East Molokai, and the southern coastal area of East Molokai, the basal water is brackish. Beneath much of East Molokai, fresh basal water is obtainable. Small amounts of fresh water are perched at high levels in East Molokai by thin poorly permeable ash beds. Fresh water is confined at high levels in permeable compartments between poorly permeable dikes in the rift zones of East Molokai, and can be developed by tunnels. Projects to bring the abundant surface and ground water of the large wind ward valleys to the Hoolehua Plain are described. Future developments are suggested. All wells and water-development tunnels are described in tables.

Catalog of the historically active volcanoes of Alaska

USGS Publications Warehouse

Miller, T.P.; McGimsey, R.G.; Richter, D.H.; Riehle, J.R.; Nye, C.J.; Yount, M.E.; Dumoulin, Julie A.

1998-01-01

Alaska hosts within its borders over 80 major volcanic centers that have erupted during Holocene time (< 10,000 years). At least 29 of these volcanic centers (table 1) had historical eruptions and 12 additional volcanic centers may have had historical eruptions. Historical in Alaska generally means the period since 1760 when explorers, travelers, and inhabitants kept written records. These 41 volcanic centers have been the source for >265 eruptions reported from Alaska volcanoes. With the exception of Wrangell volcano, all the centers are in, or near, the Aleutian volcanic arc, which extends 2500 km from Hayes volcano 145 km west of Anchorage in the Alaska-Aleutian Range to Buldir Island in the western Aleutian Islands (fig. 1). The volcanic arc, a subduction-related feature associated with underthrusting of the Pacific plate beneath the North American plate is divided between oceanic island arc and continental margin segments, the boundary occurring at about 165° W longitude (fig. 1). An additional 7 volcanic centers in the Aleutian arc (table 2; fig. 1 A) have active fumarole fields but no reported historical eruptions.This report discusses the location, physiography and structure, eruptive history, and geology of those volcanoes in Alaska that have experienced one or more eruptions that have been recorded in the written history (i.e., in historical time). It is part of the group of catalogs entitled Catalogue of Active Volcanoes of the World published beginning in 1951 under the auspices of the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI). A knowledge of the information contained in such catalogs aids in understanding the type and scale of activity that might be expected during a particular eruption, the hazards the eruption may pose, and even the prediction of eruptions. The catalog will thus be of value not only to the inhabitants of Alaska but to government agencies concerned with emergency response, air traffic operations, and weather, as well as to industry and scientists. The combination of the hazard posed by volcanic ash to jet aircraft and the heavy use of international air routes located parallel to, and on either side of, the Aleutian volcanic arc means that even remote volcanoes in Alaska now pose significant hazards to life and property.Although this report is concerned with historical eruptions from Alaskan volcanoes, other volcanoes in Alaska have erupted in the past 10,000 years and might therefore be expected to erupt again. Several Holocene volcanic centers in the Aleutian arc have no reported historical activity. Elsewhere in Alaska the Bering Sea basalt fields cover large areas of the Yukon Delta, Seward Peninsula, and several of the islands of the Bering Sea. Holocene centers also occur in the Wrangell Mountains and in isolated occurrences in the interior and southeastern Alaska. Eruptions from these centers have occurred within the past several hundred years but none were transcribed in the written record. Moodie and others (1992), however, report oral traditions among the Northern Athapaskan Indians of the southwestern Yukon Territory that may record the second and younger deposition of the White River Ash circa A.D. 720. This lobe of the White River Ash was deposited during the paroxysmal eruption of Churchill volcano in the Wrangell Mountains of eastcentral Alaska (McGimsey and others, 1992; Richter and others, 1995).

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

USGS Publications Warehouse

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

2014-01-01

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

Physical Environment of the Pacific Missile Range Facility, Kauai, Hawaii,

DTIC Science & Technology

1984-03-01

Macdonald, Davis, and Cox (1960), the island of Kauai and the adjacent island of Niihau are lava domes located at the top of one large marine volcanic...tidal current. 35 z Hnalei B. ~ IV* KAUAI 220 NIIHAU MnaP N Koeno P OAHU V, 0 10 20 -3.0 Scale in Nautical Miles Approx. * LEGEND ~-FLOOD CURRENT

Soil microbial structure and function post-volcanic eruption on Kasatochi Island and regional controls on microbial heterogeneity

NASA Astrophysics Data System (ADS)

Zeglin, L. H.; Rainey, F.; Wang, B.; Waythomas, C.; Talbot, S. L.

2013-12-01

Microorganisms are abundant and diverse in soil and their integrated activity drives nutrient cycling on the ecosystem scale. Organic matter (OM) inputs from plant production support microbial heterotrophic life, and soil geochemistry constrains microbial activity and diversity. As vegetation and soil develops over time, these factors change, modifying the controls on microbial heterogeneity. Following a volcanic eruption, ash deposition creates new surfaces where both organismal growth and weathering processes are effectively reset. The trajectory of microbial community development following this disturbance depends on both organic matter accumulation and geochemical constraints. Also, dispersal of microbial cells to the sterile ash surface may determine microbial community succession. The Aleutian Islands (Alaska, USA) are a dynamic volcanic region, with active and dormant volcanoes distributed across the volcanic arc. One of these volcanoes, Kasatochi, erupted violently in August 2008, burying a small lush island in pryoclastic flows and fine ash. Since, plants and birds are beginning to re-establish on developing surfaces, including legacy soils exposed by rapid erosion of pyroclastic deposits, suggesting that recovery of microbial life is also proceeding. However, soil microbial diversity and function has not been examined on Kasatochi Island or across the greater Aleutian region. The project goal is to address these questions: How is soil microbial community structure and function developing following the Kasatochi eruption? What is the relative importance of dispersal, soil OM and geochemistry to microbial community heterogeneity across the Aleutians? Surface mineral soil (20-cm depth) samples were collected from Kasatochi Island in summer 2013, five years after the 2008 eruption, and from eight additional Aleutian islands. On Kasatochi, pryoclastic deposits, exposed legacy soils supporting regrowth of remnant dune wild-rye (Leymus mollis) and mesic meadow plant communities, and soils impacted by recovering seabird rookeries were sampled. On the other islands, soils supporting both Leymus and mesic meadow communities (representative of dominant vegetation types on Kasatochi pre-eruption) were sampled. For each soil category and island combination, three transects of soil cores at 10-cm, 50-cm, 1-m, 5-m and 10-m distance were collected; with distances between sites and islands included (up to >700 km), the range of geographic distance examined covers over 7 orders of magnitude. For all samples, data on fundamental geochemical and OM factors, bacterial and fungal biomass, activity and diversity (via QPCR, extracellular enzyme potential assays and T-RFLP) are being collected. Covariance analysis is being used to evaluate the scale of maximum spatial heterogeneity in microbial structure and function, and ordination and matrix correlation analyses are being used to identify the key environmental covariates with heterogeneity. We hypothesize that heterogeneity at small (cm) scales will reflect predominant geochemical controls, at medium (m) scales will reflect predominant OM (vegetation) controls and at large (km) scales will reflect dispersal-related controls on microbial community structure and function.

Evidence for a Dying Magma Chamber at Rábida Island, Galápagos

NASA Astrophysics Data System (ADS)

Bercovici, H.; Geist, D.; Harpp, K. S.; Almeida, M.

2015-12-01

Rábida Island in the Galapagos has experienced both explosive and effusive volcanism. It is located to the east of the most active volcanoes of the Galapagos, and previously determined ages range from 0.9 to 1.1 Ma. An unusually curved escarpment cuts the western sector of the island, which might be part of a caldera wall, although its radius of curvature is much greater than that of the island. Lavas range from basalt to rhyolite, and there are also several intermediate compositions, which are unique in the archipelago. A welded ignimbrite crops out in northeast sector, the only such deposit known in the entire region. The volumetric proportion of evolved rocks is unusually high; 25% of the rocks in our comprehensive sample set are intermediate to felsic. The siliceous rocks occur in two clusters in the southern and southwestern sections of the island, suggesting two separate sources. The intermediate rocks are concentrated in the center and northwestern parts of the island. Despite these foci of more siliceous lavas, basalt is the most widespread rock type across the island. It is notable that Rabida is immediately east of Volcan Alcedo, which is the only active Galápagos volcano that has also erupted rhyolite, and south of Santiago Island, which erupted the trachyte dome observed by Charles Darwin in 1835. These observations, in conjunction with the cumulate xenoliths observed in Rábida explosive deposits, are consistent with the evolved rocks resulting from fractional crystallization of a dying magma chamber, as the volcano is carried away from the hotspot.

Geochemical Investigations In Soils And Waters Of Ischia Island (southern Italy)

NASA Astrophysics Data System (ADS)

Avino, R.; Capaldi, G.; Di Matteo, V.; Pece, R.

The island of Ischia is localized in the Gulf of Naples and is a volcanic field belonging to the volcanic district of the Phlegraean Fields. It covers an area of about 42 Km2 and is characterized by a complex system of faults and fractures of tectonic and volcano- tectonic origin. The highest peak of the island is Mt Epomeo (787 m), situated in the central part of Ischia. The last eruption on this island took place in 1302 (Arso) and from that time the volcanic activity has reduced only to hydrothermal manifestations (fumaroles and thermal springs) localized especially along the faults that border Mt Epomeo. So the area around the Epomeo is an area of great interest for geochemical investigations, and in fact in this place high concentration of mercury, carbon dioxide and radon have been measured. In this work are presented the data of a study on the concentration of CO2 and mercury and of the activity of radon in the soils and in the waters of the island of Ischia. For these investigations 184 samples of soils have been collected and analyzed in laboratory to calculate the concentration of mercury using the Jerome 511 Mercury Vapor Analyzer. In the same sampling sites measurements of CO2 and of the activity of radon-222 in the soils have also been made using the Track- etch@ method. As regards the waters, a sampling of 50 wells localized all around the coast of the island has been carried out. In these waters measures of mercury and of the activity of some radioactive elements have been done. The measures of radioactivity has been carried out by gamma spectrometry with a HPE Ge detector. All the investigations (in soils and in waters) allow to have preliminary information about the concentrations of these investigated elements and will be a starting-point for a more detailed sampling in those place where anomalies have been found. This set of data can also help to better understand the degassing process of these elements through the principal structures of the island giving information on the nature of the deep fluids.

On the detectability of Teide volcano magma chambers (Tenerife, Canary Islands) with magnetotelluric data

NASA Astrophysics Data System (ADS)

Piña-Varas, Perla; Ledo, Juanjo; Queralt, Pilar; Marcuello, Alex; Perez, Nemesio

2018-01-01

Tenerife has been the subject of numerous studies covering a wide range of fields. Many studies have been focused on characterising the magmatic plumbing system. Even so, a controversy still exists regarding the location and size of the current magma chambers. Several magnetotelluric (MT) surveys have been carried out in the island, but no conductivity anomalies associated with the chambers have been detected. We report the results of a set of tests conducted against the 3-D resistivity model of the island, to determine the characteristics of the detectable chambers with the MT data. The most remarkable results indicate that the MT dataset is incompatible with a large-scale mafic reservoir located at shallower depths than 8 km b.s.l. However, shallower phonolitic chambers smaller than 3 × 3 × 1 km3 could be undetected by the existing MT sites and new data should be acquired to confirm or not their existence. This new information is essential in volcanic islands like Tenerife, since many volcanic hazards are related to the size and depth of the sources of magma. Additionally, a joint interpretation of the obtained results together with other information is summarised in a hypothetical model, allowing us to better understand the internal structure of the island.[Figure not available: see fulltext.

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

NASA Image and Video Library

2000-08-10

Mount Oyama is a 820-meter-high (2,700 feet) volcano on the island of Miyake-Jima, Japan. In late June 2000, a series of earthquakes alerted scientists to possible volcanic activity. On June 27, authorities evacuated 2,600 people, and on July 8 the volcano began erupting and erupted five times over that week. The dark gray blanket covering green vegetation in the image is the ash deposited by prevailing northeasterly winds between July 8 and 17. This island is about 180 kilometers (110 miles) south of Tokyo and is part of the Izu chain of volcanic islands that runs south from the main Japanese island of Honshu. Miyake-Jima is home to 3,800 people. The previous major eruptions of Mount Oyama occurred in 1983 and 1962, when lava flows destroyed hundreds of houses. An earlier eruption in 1940 killed 11 people. This image is a perspective view created by combining image data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) aboard NASA's Terra satellite with an elevation model from the Shuttle Radar Topography Mission (SRTM). Vertical relief is exaggerated, and the image includes cosmetic adjustments to clouds and image color to enhance clarity of terrain features. http://photojournal.jpl.nasa.gov/catalog/PIA02771

Petrology and age of alkalic lava from the Ratak Chain of the Marshall Islands

USGS Publications Warehouse

Davis, A.S.; Pringle, M.S.; Pickthorn, L.-B.G.; Clague, D.A.; Schwab, W.C.

1989-01-01

Volcanic rock dredged from the flanks of four volcanic edifices in the Ratak chain of the Marshall Islands consist of alkalic lava that erupted above sea level or in shallow water. Compositions of recovered samples are predominantly differentiated alkalic basalt and hawaiite but include strongly alkalic melilitite. Whole rock 40Ar/39Ar total fusion and incremental heating ages of 87.3 ?? 0.6 Ma and 82.2 ?? 1.6 Ma determined for samples from Erikub Seamount and Ratak Guyot, respectively, are within the range predicted by plate rotation models but show no age progression consistent with a simple hot spot model. Variations in isotopic and some incompatible element ratios suggest interisland heterogeneity. -from Authors

Exciting (and modulating) very-long-period seismic signals on White Island, New Zealand

NASA Astrophysics Data System (ADS)

Neuberg, Jurgen; Jolly, Art

2014-05-01

Very-long-period seismic signals (VLP) on volcanoes can be used to fill the gap between classic seismology and deformation studies. In this contribution we reiterate the principal processing steps to retrieve from a velocity seismogram 3D ground displacement with tiny amplitudes far beyond the resolution of GPS. As a case study we use several seismic and infrasonic signals of volcanic events from White Island, New Zealand. We apply particle motion analysis and deformation modelling tools to the resulting displacement signals and exam the potential link between ground displacement and the modulation of harmonic tremor, in turn linked to a hydrothermal system. In this way we want to demonstrate the full potential of VLPs in monitoring and modelling of volcanic processes.

Earth Observation taken by the Expedition 19 crew

NASA Image and Video Library

2009-04-28

ISS019-E-011922 (28 April 2009) --- Mauna Kea Volcano in Hawaii is featured in this image photographed by an Expedition 19 crewmember on the International Space Station. The island of Hawaii is home to four volcanoes monitored by volcanologists ? Mauna Loa, Hualalai, Kilauea, and Mauna Kea. Mauna Kea is depicted in this view; of the four volcanoes, it is the only one that has not erupted during historical times. The Hawaiian Islands chain, together with the submerged Emperor Chain to the northwest, form an extended line of volcanic islands and seamounts that is thought to record passage of the Pacific Plate over a ?hotspot? (or thermal plume) in the Earth?s mantle. Areas of active volcanism in the southern Hawaiian Islands today mark the general location of the hotspot. This detailed photograph illustrates why the volcano is called Mauna Kea (?white mountain? in Hawaiian). While the neighboring Mauna Loa volcano is a classic shield volcano comprised of dark basaltic lava flows, Mauna Kea experienced more explosive activity during its last eruptive phase. This covered its basalt lava flows with pyroclastic deposits that are visible as the light brown area surrounding snow on the summit (center). Numerous small red to dark gray cinder cones are another distinctive feature of Mauna Loa. The cinder cones represent the most recent type of volcanic activity at the volcano. A small area of buildings and roadways at upper right is the Pohakuloa Training Area. This is the largest US Department of Defense facility in the state of Hawaii. The site is used for U.S. Army and Marine Corps exercises.

Spatial variations in effective elastic thickness in the Western Pacific Ocean and their implications for Mesozoic volcanism

NASA Astrophysics Data System (ADS)

Kalnins, L. M.; Watts, A. B.

2009-08-01

We have used free-air gravity anomaly and bathymetric data, together with a moving window admittance technique, to determine the spatial variation in oceanic elastic thickness, Te, in the Western Pacific ocean. Synthetic tests using representative seamounts show that Te can be recovered to an accuracy of ± 5 km for plates up to 30 km thick, with increased accuracy of ± 3 km for Te ≤ 20 km. The Western Pacific has a T e range of 0-50 km, with a mean of 9.4 km and a standard deviation of 6.8 km. The T e structure of the region is dominated by relatively high Te over the Hawaiian-Emperor Seamount Chain, intermediate values over the Marshall Islands, Gilbert Ridge, and Marcus-Wake Guyots, and low values over the Line Islands, Mid-Pacific Mountains, Caroline Islands, Shatsky Rise, Hess Rise, and Musician Seamounts. Plots of Te at sites with radiometric ages suggest that Te is to first order controlled by the age of the lithosphere at the time of loading. In areas that backtrack into the South Pacific Isotopic and Thermal Anomaly (SOPITA), Te may be as low as the depth to the 180 ± 120 °C isotherm at least locally. In the northern part of the study area including the Hawaiian-Emperor Seamount Chain, Te correlates with the depth to 310 ± 120 °C. These best-fitting isotherms imply peak rates of volcanism during 100-120 Ma (Early Cretaceous) and 140-150 Ma (Late Jurassic). The corresponding addition of 8 × 10 6 km 3 and 4 × 10 6 km 3 of volcanic material to the surface of the oceanic crust would result in long-term sea-level rises of 20 m and 10 m respectively. The Late Jurassic volcanic event, like the later Early Cretaceous event, appears to have influenced the tectonic evolution of the Pacific plate convergent boundaries, resulting in increased volcanism and orogenesis.

Implications of new stratigraphic data on volcanic hazard assessment for Nisyros volcano, Greece

NASA Astrophysics Data System (ADS)

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

2003-04-01

The active quaternary Nisyros volcano, at the eastern end of the Aegean volcanic arc, is composed of a succession of lava flows, tephra layers and interbedded epiclastic deposits. The volcano is topped by a recent caldera, on average 4 km in diameter and 200 m in depth. A detailed geological map including 35 stratigraphic units (lava flows, tephra layers and epiclastic deposits) has been recently completed at the 1:10'000 scale, based on new stratigraphical data. Based on the identification of new plinian sequences (Lakki and Melisseri pyroclastic series) in the lowermost section of the reconstructed stratigraphical succession, on the re-interpretation of previously described deposits and on the discovery of eruptive facies, we construct a set of hazard maps for volcanic events at Nisyros. Sequences of sub-marine lavas to subaerial epiclastites combined with the occurrence of a marine terrace deposit in the north-western sector of the island highlight the potential for rapid vertical movements, in particular in the area of Mandraki. A period of intense off-centred strombolian to phreatomagmatic activity occurred in quite recent times on Nisyros along the major tectonic trends (N^o030, No070, N^o120 and N^o340), building up several scoria cones and tuff cones all around the island. A number of these tectonic trends are still active, as demonstrated by faults cutting through recent deposits (including the youngest deposits of the hydrothermal eruptions, inside the present caldera of Nisyros). This implies that not only intra-caldera phreatic eruptions, but also potential magmatic eruption may occur along the island’s major zones of weakness, with increased hazards where magma/water interaction may take place. Finally a newly recognized debris avalanche deposit (the so-called Vunàri debris avalanche), affecting a wide sector in the northern part of the island, unveils a new type of volcanic hazard on Nisyros, related to flank collapse and destruction of the volcanic edifice.

Systematic Satellite Observations of the Impact of Aerosols from Passive Volcanic Degassing on Local Cloud Properties

NASA Technical Reports Server (NTRS)

Ebmeier, S.K.; Sayer, Andrew M.; Grainger, R. G.; Mather, T. A.; Carboni, E.

2014-01-01

The impact of volcanic emissions, especially from passive degassing and minor explosions, is a source of uncertainty in estimations of aerosol indirect effects. Observations of the impact of volcanic aerosol on clouds contribute to our understanding of both present-day atmospheric properties and of the pre-industrial baseline necessary to assess aerosol radiative forcing. We present systematic measurements over several years at multiple active and inactive volcanic islands in regions of low present-day aerosol burden. The timeaveraged indirect aerosol effects within 200 kilometers downwind of island volcanoes are observed using Moderate Resolution Imaging Spectroradiometer (MODIS, 2002-2013) and Advanced Along-Track Scanning Radiometer (AATSR, 2002- 2008) data. Retrievals of aerosol and cloud properties at Kilauea (Hawaii), Yasur (Vanuatu) and Piton de la Fournaise (la Reunion) are rotated about the volcanic vent to be parallel to wind direction, so that upwind and downwind retrievals can be compared. The emissions from all three volcanoes - including those from passive degassing, Strombolian activity and minor explosions - lead to measurably increased aerosol optical depth downwind of the active vent. Average cloud droplet effective radius is lower downwind of the volcano in all cases, with the peak difference ranging from 2 - 8 micrometers at the different volcanoes in different seasons. Estimations of the difference in Top of Atmosphere upward Short Wave flux upwind and downwind of the active volcanoes from NASA's Clouds and the Earth's Radiant Energy System (CERES) suggest a downwind elevation of between 10 and 45 Watts per square meter at distances of 150 - 400 kilometers from the volcano, with much greater local (less than 80 kilometers) effects. Comparison of these observations with cloud properties at isolated islands without degassing or erupting volcanoes suggests that these patterns are not purely orographic in origin. Our observations of unpolluted, isolated marine settings may capture processes similar to those in the pre-industrial marine atmosphere.

Volcanoes, Central Java, Indonesia

NASA Technical Reports Server (NTRS)

1992-01-01

The island of Java (8.0S, 112.0E), perhaps better than any other, illustrates the volcanic origin of Pacific Island groups. Seen in this single view are at least a dozen once active volcano craters. Alignment of the craters even defines the linear fault line of Java as well as the other some 1500 islands of the Indonesian Archipelago. Deep blue water of the Indian Ocean to the south contrasts to the sediment laden waters of the Java Sea to the north.

Living on Active Volcanoes - The Island of Hawai'i

USGS Publications Warehouse

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

1997-01-01

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

Leveraging America’s Aircraft Carrier Capabilities. Exploring New Combat and Noncombat Roles and Missions for the U.S. Carrier Fleet

DTIC Science & Technology

2006-01-01

There is always volcanic activity on the Hawaiian Islands. This vignette assumes that the volcano of Kilauea on the Big Island ( Hawaii ) erupts with...has occurred in Hawaii and to the volca- no’s internal configuration that could result in an explosive eruption. Usually, the Kilauea volcano , unlike...seismic activity on Hawaii , the “Big Island,” picks up considerably. In turn, the Kilauea volcano begins a series of vio- lent eruptions of

Volcanoes, Central Java, Indonesia

NASA Image and Video Library

1992-08-08

The island of Java (8.0S, 112.0E), perhaps better than any other, illustrates the volcanic origin of Pacific Island groups. Seen in this single view are at least a dozen once active volcano craters. Alignment of the craters even defines the linear fault line of Java as well as the other some 1500 islands of the Indonesian Archipelago. Deep blue water of the Indian Ocean to the south contrasts to the sediment laden waters of the Java Sea to the north.

Tristan da Cunha Island

NASA Image and Video Library

2018-05-25

Tristan da Cunha is both a remote group of volcanic islands in the south Atlantic, and the main island. It is the most remote inhabited island group in the world, 2400 km from the nearest inhabited land. Tristan has a population of about 250 inhabitants, and is part of the British overseas territory of Saint Helena, Ascension and Tristan da Cunha. In 1961 the eruption of Queen Mary's Peak forced the evacuation of the entire population for two years. The image was acquired October 7, 2017, and is located at 37.1 degrees south, 12.3 degrees west. https://photojournal.jpl.nasa.gov/catalog/PIA22506

Earth observations taken from shuttle orbiter Columbia

NASA Image and Video Library

1995-11-02

STS073-745-055 (2 November 1995) --- This photograph in color infrared highlights the different vegetation zones on the island of Maui, Hawaii. The dark red tropical forests live on the steep volcanic slopes on the north side of the island, and the fertile lowlands support large sugar cane plantations, which are the red and black checkered pattern. The Wailuku and Kahului area near the center on the north shore of the island was formerly a whaling center. Much of the eastern part of the island is Haleakala National Park, including the spectacular Haleakala Crater (under clouds).

The timing and origin of pre- and post-caldera volcanism associated with the Mesa Falls Tuff, Yellowstone Plateau volcanic field

NASA Astrophysics Data System (ADS)

Stelten, Mark E.; Champion, Duane E.; Kuntz, Mel A.

2018-01-01

We present new sanidine 40Ar/39Ar ages and paleomagnetic data for pre- and post-caldera rhyolites from the second volcanic cycle of the Yellowstone Plateau volcanic field, which culminated in the caldera-forming eruption of the Mesa Falls Tuff at ca. 1.3 Ma. These data allow for a detailed reconstruction of the eruptive history of the second volcanic cycle and provide new insights into the petrogenesis of rhyolite domes and flows erupted during this time period. 40Ar/39Ar age data for the biotite-bearing Bishop Mountain flow demonstrate that it erupted approximately 150 kyr prior to the Mesa Falls Tuff. Integrating 40Ar/39Ar ages and paleomagnetic data for the post-caldera Island Park rhyolite domes suggests that these five crystal-rich rhyolites erupted over a centuries-long time interval at 1.2905 ± 0.0020 Ma (2σ). The biotite-bearing Moonshine Mountain rhyolite dome was originally thought to be the downfaulted vent dome for the pre-caldera Bishop Mountain flow due to their similar petrographic and oxygen isotope characteristics, but new 40Ar/39Ar dating suggest that it erupted near contemporaneously with the Island Park rhyolite domes at 1.2931 ± 0.0018 Ma (2σ) and is a post-caldera eruption. Despite their similar eruption ages, the Island Park rhyolite domes and the Moonshine Mountain dome are chemically and petrographically distinct and are not derived from the same source. Integrating these new data with field relations and existing geochemical data, we present a petrogenetic model for the formation of the post-Mesa Falls Tuff rhyolites. Renewed influx of basaltic and/or silicic recharge magma into the crust at 1.2905 ± 0.0020 Ma led to [1] the formation of the Island Park rhyolite domes from the source region that earlier produced the Mesa Falls Tuff and [2] the formation of Moonshine Mountain dome from the source region that earlier produced the biotite-bearing Bishop Mountain flow. These magmas were stored in the crust for less than a few thousand years before being erupted contemporaneously along a 30 km long, structurally controlled vent zone related to extracaldera Basin and Range faults. These data highlight the rapidity with which magma can be generated and erupted over large distances at Yellowstone.

A consideration of the availableness of MODIS data to assess a volcanic ash fall

NASA Astrophysics Data System (ADS)

Tomiyama, N.; Yonezawa, C.; Yamakoshi, T.

It is important to grasp the situation of the ash fall at short interval for a volcanic disaster-prevention. Clouds and volcanic smokes reduce the opportunities to observe a volcano by a satellite's optical sensor. Therefore it is preferable to use data of a sensor that is able to observe same area with high frequency. MODIS sees every point on the earth every 1-2 days and provides NDVI data with 250m spatial resolutions. The purpose of this study is to consider the availableness of MODIS data to assess the situation of the volcanic ash fall. The test site is Miyake-jima, one of the active volcanic island in Japan. It is verified that a rate of change of NDVI between before and after erruptions correlates with the amounts of ash fall.

Earth Observations taken by Expedition 38 crewmember

NASA Image and Video Library

2013-11-11

ISS038-E-000232 (11 Nov. 2013) --- One of the Expedition 38 crew members aboard the International Space Station used a 180mm lens to photograph this oblique image featuring the Galapagos Islands or Islas Galapagos, distributed on either side of the Equator in the eastern Pacific Ocean. An archipelago of volcanic islands, the group?s official name is Archipielago de Colon.

Hydrogeological settings of a volcanic island (San Cristóbal, Galapagos) from joint interpretation of airborne electromagnetics and geomorphological observations

NASA Astrophysics Data System (ADS)

Pryet, A.; d'Ozouville, N.; Violette, S.; Deffontaines, B.; Auken, E.

2012-12-01

Many volcanic islands face freshwater stress and the situation may worsen with climate change and sea level rise. In this context, an optimum management of freshwater resources becomes crucial, but is often impeded by the lack of data. With the aim of investigating the hydrogeological settings of southern San Cristóbal Island (Galapagos), we conducted a helicopter-borne, transient electromagnetic survey with the SkyTEM system. It provided unprecedented insights into the 3-D resistivity structure of this extinct basaltic shield. Combined with remote sensing and fieldwork, it allowed the definition of the first hydrogeological conceptual model of the island. Springs are fed by a series of perched aquifers overlying a regional basal aquifer subject to seawater intrusion. Dykes, evidenced by alignments of eruptive cones at the surface, correspond to sharp sub-vertical contrasts in resistivity in the subsurface, and impound groundwater in a summit channel. Combined with geomorphological observations, airborne electromagnetics are shown to be a useful for hydrogeological exploratory studies in complex, poorly known environments. They allow optimal development of land-based geophysical surveys and drilling campaigns.

Lack of impact of the El Hierro (Canary Islands) submarine volcanic eruption on the local phytoplankton community.

PubMed

Gómez-Letona, M; Arístegui, J; Ramos, A G; Montero, M F; Coca, J

2018-03-16

The eruption of a submarine volcano south of El Hierro Island (Canary Islands) in October 2011 led to major physical and chemical changes in the local environment. Large amounts of nutrients were found at specific depths in the water column above the volcano associated with suboxic layers resulting from the oxidation of reduced chemical species expelled during the eruptive phase. It has been suggested that the fertilization with these compounds enabled the rapid restoration of the ecosystem in the marine reserve south of the island once the volcanic activity ceased, although no biological evidence for this has been provided yet. To test the biological fertilization hypothesis on the pelagic ecosystem, we studied the evolution and variability in chlorophyll a, from in situ and remote sensing data, combined with information on phytoplankton and bacterial community structure during and after the eruptive episode. Remote sensing and in situ data revealed that no phytoplankton bloom took place neither during nor after the eruptive episode. We hypothesize that the fertilization by the volcano did not have an effect in the phytoplankton community due to the strong dilution of macro- and micronutrients caused by the efficient renewal of ambient waters in the zone.

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

USGS Publications Warehouse

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

2012-01-01

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

Diffuse volcanic emissions of carbon dioxide from Vulcano Island, Italy.

PubMed

Baubron, J C; Allard, P; Toutain, J P

1990-03-01

RECENT investigations on Mount Etna (Sicily)(1-3) have revealed that volcanoes may release abundant carbon dioxide not only from their active craters, but also from their flanks, as diffuse soil emanations. Here we present analyses of soil gases and air in water wells on Vulcano Island which provide further evidence of such lateral degassing. Nearly pure carbon dioxide, enriched in helium and radon, escapes from the slopes of the Fossa active cone, adding a total output of 30 tonnes per day to the fumarolic crater discharge ( 180 tonnes CO(2) per day). This emanation has similar He/CO(2) and (13)C/(12)C ratios to those of the crater fumaroles (300%ndash;500 degrees C) and therefore a similar volcanic origin. Gases rich in carbon dioxide also escape at sea level along the isthmus between the Fossa and Vulcanello volcanic cones, but their depletion in both He and (13)C suggests a distinct source. Diffuse volcanic gas emanations, once their genetic link with central fumarole degassing has been demonstrated, can be used for continuous volcano monitoring, at safe distances from active craters. Such monitoring has been initiated at Vulcano, where soil and well emanations of nearly pure CO(2) themselves represent a threat to the local population.

Subsurface Structure Interpretation Beneath of Mt. Pandan Based on Gravity Data

NASA Astrophysics Data System (ADS)

Santoso, D.; Wahyudi, E. J.; Alawiyah, S.; Nugraha, A. D.; Widiyantoro, S.; Kadir, W. G. A.; Supendi, P.; Wiyono, S.; Zulkafriza

2017-04-01

Mt. Pandan is one of the volcano that state as dormant volcano. On the other hand, Smyth et al. (2008) defined that Mt. Pandan is an active volcano. This volcano is apart a volcanic chain in Java island which is trending east-west along the island. This volcanic chain known as present day volcanic arc. Mt. Wilis is located in the south and it relatively much bigger compare to Mt. Pandan. There were earthquakes activity experienced in the surrounding Mt. Pandan area in the past several years. This event is interesting, because Mt. Pandan is not classify as the active volcano according to the list of volcanoes in Indonesia. On the otherhand Smyth et. al. (2008) mentioned that G. Pandan as modern volcanic which is located in Kendeng Zone of East Java. Gravity measurement around Mt. Pandan area was done in order to understand subsurface structure of Mt. Pandan. Gravity interpretation results shows that there is a low density structure beneath Mt. Pandan. It could be interpreted as existing of magma body below the surface. Some indication of submagmatic activities were found as hot spring and warm ground. Therefore it could be concluded that there is a possibility of magmatic activity below the Mt. Pandan.

Tertiary sedimentary history and structure of the Valencia trough (western Mediterranean)

NASA Astrophysics Data System (ADS)

Maillard, A.; Mauffret, A.; Watts, A. B.; Torné, M.; Pascal, G.; Buhl, P.; Pinet, B.

1992-03-01

We present here main results of the Common Depth Point (CDP) data acquired during the Valsis 2 Cruise in 1988 in the Valencia trough. The profiles are tied in with industrial well data and this correlation allows the sedimentary and structural history of the region to be deduced. The Valsis Cruise seismic profiles have been supplemented by a very dense grid of industrial seismic lines and these data permit us to establish an accurate depth to basement map. The formation of the initial grabens, coeval with those of the Gulf of Lions, is related to the Early Miocene opening of the northwestern Mediterranean basin and the Barcelona graben is filled by the same sedimentary layers, including evaporites, as that of the Provençal region. Nevertheless, the Valencia-Catalan grabens have been reactivated by young extensional tectonics which could be a consequence of the convergence of Africa relative to Europe. The Valencia trough is segmented by transfer faults which trend NW-SE. These faults, which have a more accentuated structural expression than the Valencia and Catalonia grabens, may act as transform faults separating the individual Balearic Islands. The transfer faults are in strike with volcanic ridges which have been sampled during the DSDP Leg 13. The dense seismic grid allows us to delineate several widespread volcanic features in the Valencia trough which have been active from the Early Miocene to the Pleistocene. However, we note that the volcanic features are mainly Miocene in age whereas the recent volcanism is restricted to a narrow zone (Columbretes Islands). The compressional tectonics which deformed the Balearic Islands does not appear to extend far towards the North. We delineate the compressional front north of Ibiza, but we failed to determine any thrust or fold north of Mallorca, whereas an extensional tectonics is evident.

Eocene to Oligocene volcanism in the Mariana fore-arc and crustal melting

NASA Astrophysics Data System (ADS)

Hartman, B.; Reagan, M.; Hickey-Vargas, R.; Hanan, B.; Blichert-Toft, J.

2003-04-01

Recently collected volcanic rocks from the Mariana fore-arc islands of Saipan and Rota provide evidence that the genesis of silicic magmas in the IBM system involves extensive crustal melting. Rhyolites from the island of Saipan are unusually high in silica for an oceanic island arc setting. They also are unique in the Izu-Bonin-Mariana (IBM) system in that they erupted during the earliest stages of subduction (45--46 Ma), but have "mature arc" major element, trace element, and isotopic compositions. For example, the rhyolites have flat REE patterns and pronounced negative Nb anomalies. These trace element patterns are nearly identical to those Oligocene (36--32 Ma) "early arc" andesites and dacites on Saipan, Guam, and Rota. All of the aforementioned lavas also have similar 207Pb/204Pb and 208Pb/204Pb values that plot along a trend that stretches from West Philippine basin basalt compositions toward those Pacific siliceous sediments. In contrast, Eocene volcanic rocks from other locations in the IBM arc are basaltic to boninitic and have U-shaped REE patterns and small to nonexistent Nb anomalies. The Pb isotopic compositions of these samples are similar to Pacific basin volcanics and volcanogenic sediments. Mathematical modeling suggests that the Saipan rhyolites were most likely derived by partial melting of an arc-like amphibolite crust and not through crystal fractionation of a "protoarc" boninite series magma. The data and these modelings suggest that a piece of preexisting arc-like amphibolite crust was trapped in the Mariana fore-arc early in its evolution. The Saipan rhyolites were produced by melting this crust at relatively shallow depths.

Earth Observation taken by the STS-125 Crew

NASA Image and Video Library

2009-05-13

S125-E-006569 (13 May 2009) --- Hawaiian vog from Kilauea volcano, on the island of Hawaii, has been erupting continuously since 1983. This image, taken by the crew of Space Shuttle Atlantis (after completing the capture of the Hubble Space Telescope), shows the volcanic plumes from Kilauea rising up from Halema`uma`u Crater and along the coastline from lava flows entering the ocean from the East rift zone. The volcanic activity has created a blanket of volcanic fog, called vog that envelops the island. The Hawaii Volcano Observatory (HVO) maintains a website (including webcams) that continuously monitors and updates reports on the volcanic activity. Recent maps indicate expanded lava coverage along the coastal plain. In addition, Hawaii?s Department of Health maintains daily vog alerts, and publishes advisories for vog conditions around the ?big island? of Hawaii and the state. When this image was acquired, the region west of Hawaii Volcanoes National Park (downwind from the coastal plumes) had a vog advisory for people with respiratory sensitivities. The Volcano Observatory also reported that ?Lava from east rift zone vents continues to flow through tubes to the coast and is entering the ocean at two locations west of Kalapana. Sulfur dioxide emission rates from the Halema`uma`u and Pu`u `O`o vents remain elevated. Sulfur dioxide emission rates remain elevated and variable; the most recent rate measurement was 1,200 tonnes/day on May 12, compared to the 2003-2007 average rate of 140 tonnes/day. Small amounts of mostly ash-sized tephra continue to be produced consisting mostly of Pele's hair -- irregular pieces of vesicular glass -- and a few hollow spherules.?

Halocarbons and other trace heteroatomic organic compounds in volcanic gases from Vulcano (Aeolian Islands, Italy)

NASA Astrophysics Data System (ADS)

Schwandner, Florian M.; Seward, Terry M.; Giże, Andrew P.; Hall, Keith; Dietrich, Volker J.

2013-01-01

Adsorbent-trapped volcanic gases, sublimates and condensates from active vents of the La Fossa crater on the island of Vulcano (Aeolian Islands, Italy) as well as ambient and industrial air were quantitatively analyzed by Short-Path Thermal Desorption-Solid Phase Microextraction-Cryotrapping-Gas Chromatography/Mass Spectrometry (SPTD-SPME-CF-GC-MS). Among the over 200 detected and quantified compounds are alkanes, alkenes, arenes, phenols, aldehydes, carboxylic acids, esters, ketones, nitriles, PAHs and their halogenated, methylated and sulfonated derivatives, as well as various heterocyclic compounds including thiophenes and furans. Most compounds are found at concentrations well above laboratory, ambient air, adsorbent and field blank levels. For some analytes (e.g., CFC-11, CH2Cl2, CH3Br), concentrations are up to several orders of magnitude greater than even mid-latitudinal industrial urban air maxima. Air or laboratory contamination is negligible or absent on the basis of noble gas measurements and their isotopic ratios. The organic compounds are interpreted as the product of abiogenic gas-phase radical reactions. On the basis of isomer abundances, n-alkane distributions and substitution patterns the compounds are thought to have formed by high-temperature (e.g., 900 °C) alkyl free radical reactions and halide electrophilic substitution on arenes, alkanes and alkenes. The apparent abiogenic organic chemistry of volcanic gases may give insights into metal transport processes during the formation and alteration of hydrothermal ore deposits, into the natural volcanic source strength of ozone-depleting atmospheric trace gases (i.e., halocarbons), into possibly sensitive trace gas redox pairs as potential early indicators of subsurface changes on volcanoes in the state of imminent unrest, and into the possible hydrothermal origin of early life on Earth, as indicated by the presence of simple amino acids, nitriles, and alkanoic acids.

Vertical tectonics at an active continental margin

NASA Astrophysics Data System (ADS)

Houlié, N.; Stern, T. A.

2017-01-01

Direct observations of vertical movements of the earth's surface are now possible with space-based GPS networks, and have applications to resources, hazards and tectonics. Here we present data on vertical movements of the Earth's surface in New Zealand, computed from the processing of GPS data collected between 2000 and 2015 by 189 permanent GPS stations. We map the geographical variation in vertical rates and show how these variations are explicable within a tectonic framework of subduction, volcanic activity and slow slip earthquakes. Subsidence of >3 mm/yr is observed along southeastern North Island and is interpreted to be due to the locked segment of the Hikurangi subduction zone. Uplift of 1-3 mm/yr further north along the margin of the eastern North Island is interpreted as being due to the plate interface being unlocked and underplating of sediment on the subduction thrust. The Volcanic Plateau of the central North Island is being uplifted at about 1 mm/yr, which can be explained by basaltic melts being injected in the active mantle-wedge at a rate of ∼6 mm/yr. Within the Central Volcanic Region there is a 250 km2 area that subsided between 2005 and 2012 at a rate of up to 14 mm/yr. Time series from the stations located within and near the zone of subsidence show a strong link between subsidence, adjacent uplift and local earthquake swarms.

Regional Climate Modeling of Volcanic Eruptions and the Arctic Climate System: A Baffin Island Case Study

NASA Astrophysics Data System (ADS)

Losic, M.; Robock, A.

2010-12-01

It is well-understood that the effects of volcanic aerosol loading into the stratosphere are transient, with global cooling lasting only a few years after a single large eruption. Geological evidence collected from Northern Baffin Island, Canada, suggests ice cap growth began soon after a succession of several large eruptions in the 13th century, and they did not start to melt until roughly a century ago. We investigate which feedbacks allowed these ice caps to be maintained long after the transient forcing of the volcanic aerosols, by conducting sensitivity studies with the Weather Research and Forecasting (WRF) Model and Polar WRF, a version of WRF developed specifically for the polar regions. Results from an ensemble of month-long regional simulations over Baffin Island suggest that better treatment of snow and ice in Polar WRF improves our regional climate simulations. Thus, sensitivity test results from decade-long runs with imposed changes to boundary condition temperatures and carbon dioxide concentrations using Polar WRF are presented. Preliminary findings suggest that not only large scale but localized climate feedbacks play an important role in the responses of the ice caps after temperature and carbon dioxide forcings are applied. The results from these and further sensitivity tests will provide insight into the influence of regional feedbacks on the persistence of these ice caps long after the 13th century eruptions.