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1

Chaotic deposition by a giant wave, Molokai, Hawaii  

USGS Publications Warehouse

A coral-basalt breccia-conglomerate is exposed >60m above present sea level and nearly 2km inland from the present shoreline on the southwest side of East Molokai Volcano. This deposits was apparently laid down by a giant wave that broke over an outer reef, similar to the present fringing reef, and advanced as a turbulent bore over the back-reef flat, picking up a slurry of carbonate-rich debris and depositing it on the slopes inland as the wave advanced. U-series dating of coral fragments indicates that the age of this deposit is 240-200 ka. This giant wave was most likley caused by one of the many large submarine landslides that have been identified on the lower slopes of the major Hawaiian Islands. -from Authors

Moore, J. G.; Bryan, W. B.; Ludwig, K. R.

1994-01-01

2

Estimating the longevity of the LUSI mud volcano, East Java  

Microsoft Academic Search

The LUSI mud volcano in East Java has been erupting mud (composition approximately 70% water) at average daily volumes estimated to be on the order of 90,000m3 since May 2006. The mud now covers an area of 7.0 Km2 in a densely populated region. How long the eruption will continue as a high-volume event has been estimated using available subsurface

R. E. Swarbrick; R. Davies; M. R. Tingay

2009-01-01

3

Do Off-ridge Volcanoes on the East Pacific Rise Originate from the Moho Transition Zone?  

Microsoft Academic Search

A large number of intraplate volcanoes erupted two to several hundred kilometers off the fast-spreading East Pacific Rise(EPR) . These volcanoes consist of large lava fields, monogenet- ic volcanoes, and linear chains of monogenetic volcanoes and volcanic ridges. Large lava fields of 7?26 km 3 in volume are known at 8° N, 14° S, and 16° S within 2?19 km

Susumu UMINO; Nobuo GESHI; Hidenori KUMAGAI; Kiyoyuki KISIMOTO

2008-01-01

4

Estimating the longevity of the LUSI mud volcano, East Java  

NASA Astrophysics Data System (ADS)

The LUSI mud volcano in East Java has been erupting mud (composition approximately 70% water) at average daily volumes estimated to be on the order of 90,000m3 since May 2006. The mud now covers an area of 7.0 Km2 in a densely populated region. How long the eruption will continue as a high-volume event has been estimated using available subsurface data combined with Monte Carlo simulation applied to the input variables. Since the subsurface pressures are well known from the nearest deep borehole penetration (Porong-1 well) and the continuous, high volume eruption indicates a large connected aquifer pore volume supplying the water to the eruption, the principal uncertainty to govern the longevity estimate is the connectivity of the reef complex across its mapped area and the associated aquifer pore volume. Estimates of the longevity of LUSI range from 10 to more than 100 years, with a best estimate of 30-35 years. The best estimate indicates the need for long-term planning to control the expected volumes to be erupted in this densely populated area of East Java, as well as the impact of subsidence when the crater collapses.

Swarbrick, R. E.; Davies, R.; Tingay, M. R.

2009-12-01

5

The East Java mud volcano (2006 to present): An earthquake or drilling trigger?  

Microsoft Academic Search

On May 29th 2006 a mud volcano, later to be named ‘Lusi’, started to form in East Java. It is still active and has displaced >30,000 people. The trigger mechanism for this, the world's largest and best known active mud volcano, is still the subject of debate. Trigger mechanisms considered here are (a) the May 27th 2006 Yogyakarta earthquake, (b)

Richard J. Davies; Maria Brumm; Michael Manga; Rudi Rubiandini; Richard Swarbrick; Mark Tingay

2008-01-01

6

Cyclic activity of the LUSI mud volcano (East Java, Indonesia)  

NASA Astrophysics Data System (ADS)

Mud volcanoes often release fluids in a pulsating fashion, with periodic timescales ranging from minutes to days. These oscillations, common in natural systems of multi-phase fluid flow, are thought to result from some combination of complex feedback mechanisms between conduit and source geometry, and such factors as: fluid compressibility, viscosity and density, changes in lithostatic stresses, reservoir pressure, or vent conditions. The LUSI mud volcano is in a densely populated district of the Sidoarjo regency (East Java, Indonesia), and has been erupting since May 2006. Crisis management workers and local residents have reported observations of pulsating eruptive cycles lasting a few hours during the first two years of the eruption, and possibly beyond. Since 2010, however, the activity has shifted to individual transient eruptions recurring at intervals of a few minutes. In the summer of 2011, we documented this cyclic behavior at LUSI using a combination of high-resolution time-lapse photography, webcam, and thermal infrared imagery. The imagery reveals that hot mud and gases were released from three individual sources within the 150 m wide vent pond. The mud, consisting of at least 70% water, is erupted at temperatures close to boiling. Released gases consist principally of water vapor, carbon dioxide and methane. Eruptions ejected mud some 20 m above the vent in an unsteady fountain and formed 50 m-high plumes of hot gas. Pulses, on average 50 s in duration, were characterized by sharp onsets and exponential decays in intensity. We observed explosion periods ranging from 1 to 3 minutes during this campaign, the median period was 100 s, and pulses were separated by periods of apparent quiescence. Each vent was characterized by a different dominant period, indicating that parameters controlling activity vary among the vents. Potential conceptual eruptive models are gas accumulation and release, slug flow, or oscillations in pressure at depth to account for the eruption cyclicity. Our field measurements of periodicity, column height and, in time, gas flux, coupled with estimates of mud viscosity and conduit geometry, are thus crucial parameters that can be used to test the various models and ultimately constrain conditions in the deeper parts of the LUSI system.

Vanderkluysen, L.; Clarke, A. B.; Hartnett, H. E.

2011-12-01

7

New geophysical views of Mt.Melbourne Volcano (East Antarctica)  

NASA Astrophysics Data System (ADS)

Mt. Melbourne volcano is located along the transition between the Transantarctic Mountains and the West Antarctic Rift System. Recent volcanic activity is suggested by the occurrence of blankets of pyroclastic pumice and scoria fall around the eastern and southern flanks of Mt Melbourne and by pyroclastic layers interbedded with the summit snows. Geothermal activity in the crater area of Mount Melbourne may be linked to the intrusion of dykes within the last 200 years. Geophysical networks suggest that Mount Melbourne is a quiescent volcano, possibly characterised by slow internal dynamics. During the 2002-2003 Italian Antarctic campaign a high-resolution aeromagnetic survey was performed within the TIMM (Tectonics and Interior of Mt. Melbourne area) project. This helicopter-borne survey was flown at low-altitude and in drape-mode configuration (305 m above terrain) with a line separation less than 500 m. Our new high-resolution magnetic maps reveal the largely ice-covered magmatic and tectonic patters in the Mt. Melbourne volcano area. Additionally, in the frame of the UK-Italian ISODYN-WISE project (2005-06), an airborne ice-sounding radar survey was flown. We combine the sub-ice topography with images and models of the interior of Mt. Melbourne volcano, as derived from the high resolution aeromagnetic data and land gravity data. Our new geophysical maps and models also provide a new tool to study the regional setting of the volcano. In particular we re-assess whether there is geophysical evidence for coupling between strike-slip faulting, the Terror Rift, and Mount Melbourne volcano.

Armadillo, E.; Gambetta, M.; Ferraccioli, F.; Corr, H.; Bozzo, E.

2009-05-01

8

The 12 September 1999 Upper East Rift Zone dike intrusion at Kilauea Volcano, Hawaii  

Microsoft Academic Search

Deformation associated with an earthquake swarm on 12 September 1999 in the Upper East Rift Zone of Kilauea Volcano was recorded by continuous GPS receivers and by borehole tiltmeters. Analyses of campaign GPS, leveling data, and interferometric synthetic aperture radar (InSAR) data from the ERS-2 satellite also reveal significant deformation from the swarm. We interpret the swarm as resulting from

P. Cervelli; P. Segall; F. Amelung; H. Garbeil; C. Meertens; S. Owen; A. Miklius; M. Lisowski

2002-01-01

9

Modeling study of growth and potential geohazard for LUSI mud volcano: East Java, Indonesia  

Microsoft Academic Search

The mud volcano known as LUSI first erupted in May 2006 in East Java, Indonesia. The eruption has continued for over two years, and potentially will continue for many years to come, impacting an ever larger area. An obvious and significant question is how extensive the impacted area will become in the coming years. The answer is important for planning

Bambang P. Istadi; Gatot H. Pramono; Prihadi Sumintadireja; Syamsu Alam

2009-01-01

10

Organic chemical composition of mud from the LUSI mud volcano, Sidoarjo, East Java, Indonesia  

Microsoft Academic Search

Sidoarjo, East Java, Indonesia is the site of LUSI, a terrestrial mud volcano that has been erupting since May 29, 2006. In response to a U.S. Department of State request, the U.S. Geological Survey has been assisting the Indonesian Government to describe the geological and geochemical aspects and potential health risk of the mud eruption. We report here on the

R. J. Rosenbauer; P. Campbell; A. Lam

2009-01-01

11

Volcanoes  

ERIC Educational Resources Information Center

|Describes the forces responsible for the eruptions of volcanoes and gives the physical and chemical parameters governing the type of eruption. Explains the structure of the earth in relation to volcanoes and explains the location of volcanic regions. (GS)|

Kunar, L. N. S.

1975-01-01

12

Volcanoes.  

ERIC Educational Resources Information Center

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

Tilling, Robert I.

13

Volcanoes.  

ERIC Educational Resources Information Center

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

Tilling, Robert I.

14

Volcanoes  

NSDL National Science Digital Library

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

15

The 1962 Flank Eruption of Kilauea Volcano and Structure of the East Rift Zone  

Microsoft Academic Search

On December 7-9, 1962, a small flank eruption occurred on the upper part of the east rift zone of Kilauea volcano. The six eruptive fissures, which show a right-offset en echelon pattern, extend more than 2 miles from Aloi crater eastward to the west slope of Kane Nut o Hamo. The total volume of erupted lava was small (426,000 cubic

James G. Moore; Harold L. Krivoy

1964-01-01

16

Volcanoes  

NSDL National Science Digital Library

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

Foundation, Wgbh E.

2005-12-17

17

Crustal structure of east central Oregon: relation between Newberry Volcano and regional crustal structure  

SciTech Connect

A 180-km-long seismic refraction transect from the eastern High Cascades, across Newberry Volcano, to the eastern High Lava Plains is used to investigate the subvolcanic crustal and upper mantle velocity structure there. Near-surface volcanic flows and sedimentary debris (1.6--4.7 km/s), ranging from 3 to 5 km in thickness, overlie subvolcanic Basin and Range structures. East and west of Newberry Volcano, the subvolcanic basement (5.6 km/s) has been downwarped, producing 5-km-deep basins. The midcrust (8- to 28-km depth) is characterized by velocities ranging from 6.1 to 6.5 km/s and varies laterally in thicknesses. The lowercrust is characterized by an unusually high velocity (about 7.4 km/s), and its geometry mirrors the subvolcanic basement geometry. The Moho is located at a depth of 37 km and represents a transition to an upper mantle velocity of 8.1 km/s. The shallow subsurface (1.2 km) beneath Newberry Volcano is characterized by high-velocity (5.6 km/s, versus 4.1 km/s for the surrounding area) intrusions and appears to be located on a basement high. Beneath the seismic fraction array at Newberry Volcano, an absence of low-velocity anomalies suggests that large silicic magma chambers do not exist in the upper crust, but apparent high attenuation of the seismic wave field may be consistent with either partial melts in small volumes, elevated crustal temperatures, and/or poor geophone-recording site coupling. The east central Oregon velocity structure is nearly identical to that of the northwestern Nevada Basin and Range and the Modoc Plateau of northeastern California, and variations in the deep crustal structure about Newberry Volcano are consistent with tectonism involving crustal underplating, melting, and extension.

Catchings, R.D.; Mooney, W.D.

1988-09-10

18

The 2007 eruption of Kelut volcano (East Java, Indonesia): Phenomenology, crisis management and social response  

NASA Astrophysics Data System (ADS)

We focus in this paper on the processes and consequences of an unusual volcanic eruption at Kelut volcano, East Java. In November 2007, after two months of worrying precursor signs, Kelut volcano erupted. But neither explosions nor the usual hazards observed during the historic eruptions happened (e.g. ash falls, volcanic bombs and pyroclastic flows). Instead of an explosive eruption, the 2007 eruption was extrusive. Given than such an eruption could not be predicted, the authorities had to manage a new situation. We conducted interviews with nine stakeholders of the crisis management team, and undertook a questionnaire-based survey in the settlement nearest to the crater, in order to understand how the authorities managed the crisis, and how people reacted. Inquiries and questionnaires were carried out shortly after the end of the evacuation process, when the volcano was still under surveillance for fear of an explosive phase. The results display a real gap in what it takes to manage a crisis or live through a crisis. This suggests that the "unusual" eruption pattern of Kelut volcano was not the only factor of the misunderstanding between the authorities and the population. These problems stem from more structural causes such as the lack of communication and information when there is a need to adapt to a new scenario. In such a situation, the inability of the crisis management system to take decisions underscored the intrinsic vulnerability of the population despite a hierarchical and strategic top-down crisis management approach.

de Bélizal, Édouard; Lavigne, Franck; Gaillard, J. C.; Grancher, Delphine; Pratomo, Indyo; Komorowski, Jean-Christophe

2012-01-01

19

Volcanoes and ENSO in millennium simulations: global impacts and regional reconstructions in East Asia  

NASA Astrophysics Data System (ADS)

The impacts and cooperative effects of volcanic eruptions and ENSO (El Niño/Southern Oscillation) are analyzed in a millennium simulation for 800-2005 AD using the earth system model (ESM) ECHAM5/MPIOM/JSBACH subject to anthropogenic and natural forcings. The simulation comprises two ensembles, a first with weak (E1, five members) and a second with strong (E2, three members) variability total solar irradiance. In the analysis, the 21 most intense eruptions are selected in each ensemble member. Volcanoes with neutral ENSO states during two preceding winters cause a global cooling in the year after eruptions up to -2.5°C. The nonsignificant positive values in the tropical Pacific Ocean indicate an El Niño-like warming. In the winter after an eruption, warming is mainly found in the Arctic Ocean and the Bering Sea in E2 warming extends to Siberia and central Asia. The recovery times for the volcano-induced cooling (average for 31 eruptions) vary globally between 1 and 12 years. There is no significant increase of El Niño events after volcanic eruptions in both ensembles. The simulated temperature and the drought indices are compared with corresponding reconstructions in East Asia. Volcanoes cause a dramatic cooling in west China (-2°C) and a drought in East China during the year after the eruption. The reconstructions show similar cooling patterns with smaller magnitudes and confirm the dryness in East China. Without volcanoes, El Niño events reduce summer precipitation in the North, while South China becomes wetter; La Niña events cause opposite effects. El Niño events in the winters after eruptions compensate the cooling caused by volcanoes in most regions of China (consistent with reconstructions), while La Niña events intensify the cooling (up to -2.5°C). The simulated and reconstructed drought indices show tripole patterns which are altered by El Niño events. The simulated impact of the Tambora eruption in 1815, which caused the "year without summer" of 1816 in Europe and North America and led to coldness and famines in the Chinese province Yunnan, depends crucially on the ENSO state of the coupled model. A comparison with reconstructed El Niño events shows a moderate cool climate with wet (in the south) and extreme dry anomalies (in the north) persisting for several years.

Zhang, Dan; Blender, Richard; Fraedrich, Klaus

2013-02-01

20

Crustal structure of east central Oregon: relation between Newberry Volcano and regional crustal structure  

USGS Publications Warehouse

A 180-km-long seismic refraction transect from the eastern High Cascades, across Newberry Volcano, to the eastern High Lava Plains is used to investigate the subvolcanic crustal and upper mantle velocity structure there. Near-surface volcanic flows and sedimentary debris (1.6-4.7 km/s), ranging from 3 to 5 km in thickness, overlie subvolcanic Basin and Range structures. East and west of Newberry Volcano, the subvolcanic basement (5.6 km/s) has been downwarped, producing 5-km-deep basins. The midcrust (8- to 28-km depth) is characterized by velocities ranging from 6.1 to 6.5 km/s and varies laterally in thicknesses. The lower crust is characterized by an unusually high velocity (about 7.4 km/s), and its geometry mirrors the subvolcanic basement geometry. The Moho is located at a depth of 37 km and represents a transition to an upper mantle velocity of 8.1 km/s. The shallow subsurface (1.2 km) beneath Newberry Volcano is characterized by high-velocity 5.6 km/s, versus 4.1 km/s for the surrounding area) intrusions and appears to be located on a basement high. Beneath the seismic refraction array at Newberry Volcano, an absence of low-velocity anomalies suggests that large silicic magma chambers do not exist in the upper crust, but apparent high attenuation of the seismic wave field may be consistent with either partial melts in small volumes, elevated crustal temperatures, and/or poor geophone-recording site coupling. -Authors

Catchings, R. D.; Mooney, W. D.

1988-01-01

21

Volcano  

NSDL National Science Digital Library

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

Weisel, Frank

22

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

Microsoft Academic Search

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

Christopher F. Waythomas

1999-01-01

23

Geochemistry and age of the Essimingor volcano, northern Tanzania (East Africa)  

NASA Astrophysics Data System (ADS)

Essimingor is the oldest of a line of north-south trending pre-rift volcanoes in northern Tanzania associated with the opening of the southern sector of the Gregory Rift, part of the East African Rift system (EAR). Essimingor is centrally located within the present day rift, on the East-West alignment between the large volcanoes of Kilimanjaro and Ngorongoro. Based on K-Ar data of Bagdasaryan et al. (1973), Essimingor is commonly reported to be about 8 Ma, although Evans et al. (1971) reports it to be between 5 to 3 Ma. Geochemically, Essimingor is characterized by alkaline magmatism and it is compositionally similar to adjacent albeit younger volcanoes (e.g. Burko, Tarosero and Monduli). Although the regional trend in magmatic evolution is from basalt to alkaline basalt, and then to more evolved rock types enriched in alkalis (Dawson, 2008), Essimingor appears to be an exception given its age. In fact, this volcano precedes or is, perhaps, contemporaneous with the dominantly basaltic regional magmatism. Essimingor’s age and geochemistry are crucial to providing the earliest record for the tectonomagmatic reconstruction of the EAR in northern Tanzania. To better characterize this pivotal pre-rift volcano we present new 40Ar/39Ar laser-incremental heating and geochemical analyses (major, minor and trace element compositions, and Sr-Nd-Pb isotope data) on twelve carefully chosen lava samples. Laser-incremental heating of whole rock matrix, bulk whole rock and nepheline, yield 40Ar/39Ar ages ranging from 5.81±0.01 Ma to 6.20±0.03 Ma. These ages restrict the duration of volcanism of Essimingor to approximately 370 kyr, and its maximum age to about 6.2 Ma, approximately 2 myr earlier than previously considered. Preliminary geochemical data suggest the presence of large variations in radiogenic isotopes: 87Sr/86Sr ranges from 0.7036 to 0.7056, 143Nd/144Nd from 0.5124 to 0.5126 and 206Pb/204Pb are about 20-21. The isotopic and incompatible trace element variations indicate open system processes and multiple sources, in which one end member is most probably HIMU. The Ce/Pb ratio can be used as a rough evaluation of the crust-magma mixing suggesting the presence of crustal contamination. This contamination is not attributed to simple wall rock assimilation around the magma chamber as there is no correlation between Sr isotopes and Sr concentration. In contrast, major elements are well-behaved with linear compositional variations that reveal magmatic evolution from picrite, to basanite, to nephelinite to tephri-phonolite. The MgO content decreases from 9.40 to 1.12 wt.%, CaO correlates positively with MgO while Al2O3, Na2O and K2O correlate negatively. At about 6 wt.% of MgO, P2O5 and TiO2 no longer behave as incompatible elements but behave as compatible elements. These geochemical trends can be modeled by crystal fractionation during the process of magma evolution in a sub-volcanic chamber. Initially, olivine and pyroxene crystallization drive magmatic evolution, but at MgO values close to 6-5 wt.% a change in slope occurs in several oxide-oxide plots corresponding with the co-precipitation of several other mineral phases (e.g. apatite, Fe-Ti oxides, nepheline).

Mana, S.; Mollel, G. F.; Feigenson, M.; Carr, M. J.; Turrin, B. D.; Furman, T.; Swisher, C. C.

2009-12-01

24

Molokai II: Addendum to the Recovery Plan for the Molokai Plant Cluster.  

National Technical Information Service (NTIS)

This document is meant to supplement the original Recovery Plan for the Molokai Plant Cluster (Recovery Plan) (USEWS 1996a), which dealt with 16 plant taxa. Because the three additional listed taxa covered in this Addendum occur in similar habitats as the...

1998-01-01

25

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

Microsoft Academic Search

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

Christopher F. Waythomas

1999-01-01

26

Organic chemical composition of mud from the LUSI mud volcano, Sidoarjo, East Java, Indonesia  

NASA Astrophysics Data System (ADS)

Sidoarjo, East Java, Indonesia is the site of LUSI, a terrestrial mud volcano that has been erupting since May 29, 2006. In response to a U.S. Department of State request, the U.S. Geological Survey has been assisting the Indonesian Government to describe the geological and geochemical aspects and potential health risk of the mud eruption. We report here on the organic chemical composition of the mud. Organic chemical analyses were carried out by gas chromatography/mass spectroscopy following organic extraction by microwave-assisted solvent extraction and compound fractionation by adsorption chromatography. There is a petroliferous component in the mud that is fresh, immature, and nonbiodegraded. There is a complete suite of n-alkanes with a bell-shaped pattern typical of fresh petroleum with a Cmax around C20. The alkane content ranges from 0.12 to 1.01 mg/kg dry mud. The presence of certain hopanes (i.e. 17 ?,21?(H)-30-norhopane and 17?,21?(H)-hopane) is also indicative of the presence of oil. The proportions of other biomarker compounds (pristane/phytane = 2.4) and the dominance of the C27 sterane (5?(H),14?(H),17?(H)-chlolestane) suggest that oil formed under oxic conditions and has a likely coastal marine or terrigenous source. The presence of oleanane indicates a Cretaceous or younger age for the petrogenic material. These geochemical parameters are consistent with Indonesian oil derived from Tertiary marlstone source rocks that contained kerogen deposited under oxic conditions, probably the upper Miocene Klasafet Formation. Polycyclic aromatic hydrocarbons (PAHs) are present and range in content from 0.1 to 2.2 mg/kg dry mud. The low molecular weight (LMW) PAHs, in particular, naphthalene and methyl-naphthalene are dominant except for perylene which is ubiquitous in the environment. The presence of both parent and higher homologue PAHs indicate a petrogenic rather than combustion source. PAHs are known carcinogens but toxicity data in sediments are sparse and often qualitative, depending on the PAH matrix and thus bioavailability. The distribution and content of PAHs measured in the LUSI mud do exceed USEPA recommended interim sediment quality criteria. In addition, judging sediment toxicity on the basis of single PAH compounds risks underestimating effects because mixtures of PAHs tend to aggregate toxicity. Further studies are needed to determine whether or not PAHs are present in levels that exceed soil remediation or aquatic guidelines. The mud contains low levels (tens of ppb) of the higher plant sterols including stigmasterol and ?-sitosterol. Also, 22-dehydrocholesterol (generally ascribed to algal material) is present at 39 ppb. These compounds are derived from natural sources, are non-hazardous, and were likely entrained in the mud during ascent to the surface or mixed with the mud post-eruption. The organic compounds identified to date will exhibit a variety of environmental behaviors and effects. Some compounds will volatilize and photo-oxidize or biodegrade relatively quickly (i.e. n-alkanes), and are relatively nontoxic. LMW PAHs are sparingly soluble in water but heavier PAHs will likely persist in the environment and represent potential toxicity to biota because PAHs are bio-accumulative. But the overall toxicity of the mud appears low.

Rosenbauer, R. J.; Campbell, P.; Lam, A.

2009-12-01

27

Nd and Sr isotope systematics of Shombole volcano, East Africa, and the links between nephelinites, phonolites, and carbonatites  

SciTech Connect

Nd and Sr isotope compositions of nephelinites, carbonatites, and phonolites from Shombole, a Pliocene volcano in East Africa, show that the phonolites cannot be derived by simple fractional crystallization of nephelinite magma. For a given initial {sup 87}Sr/{sup 86}Sr ratio, {sup 143}Nd/{sup 144}Nd is lower in most phonolites than in the nephelinites and carbonatites. Interaction between nephelinitic magma and lower-crustal granulites can account for these differences. The similar ranges in isotopic composition of the carbonatites and nephelinites are consistent with repeated melting events involving heterogeneous mantle. The carbonatites could have formed by immiscibility with nephelinite magma or by direct partial melting of the same mantle source(s) as the nephelinites.

Bell, K. (Carleton Univ., Ottawa, Ontario (Canada)); Peterson, T. (Geological Survey of Canada, Ottawa, Ontario (Canada))

1991-06-01

28

November 16th 2006 Lateral Collapse of South-East Crater on Mount Etna Volcano and Hazard Implication  

NASA Astrophysics Data System (ADS)

On November 16th 2006 a sector collapse affected the unstable eastern flank of the South-East Crater (SEC) on Mount Etna Volcano. The SEC is located on the Etna volcano summit and is an active steep cone formed by alternated scoria deposits and lava flows traversed by numerous fractures. The collapse occurred during an eruptive event and was probably triggered by effusive and explosive activity on the SEC. The resulting debris avalanche involved both altered and fresh materials, including an active lava flow. The collapse produced a debris avalanche deposit emplaced on the eastern flank of the volcano, extending up to 1.1 km from the source. The deposit is formed by superimposed flow units, suggesting that it is the result of at least two discrete events, the total volume is estimated in the order of 300,000-500,000 m3. A block-facies and a matrix-facies were recognized in the field. The former is composed by blocks up to 1 meters in dimension and has maximum thickness of 4-5 meters. The matrix-facies is mainly composed by a convection-driven flow deposit consisted of fine ash produced by elutriation during emplacement of the block-facies, maximum observed thickness is 30 cm. The reconstruction of the event has been supported by numerical simulations that were executed using TITAN2D, a modeling software for granular avalanches and landslides developed by GMFG at Buffalo. This approach is also useful to estimate the area that would be affected by an eventual similar event that could interest the SEC. The area affected by the lateral collapse of the SEC is a small portion of the summit area of Mount Etna, but the fact that no one was killed or injured should be considered fortuitous. This because the summit and adjacent areas of the volcano are usually visited by several people, especially tourists, not prepared to face this type of events, which was never observed and described during the recent activity of Mount Etna. The collapse of November 16th 2006 underscores the need to prepare for similar events through scientific investigation (analysis of instability, numerical modelling of flows) and development of specific civil protection plans.

Norini, G.; Andronico, D.; de Beni, E.; Polacci, M.; Grieco, F.

2007-05-01

29

Relation of summit deformation to east rift zone eruptions on Kilauea Volcano, Hawaii  

SciTech Connect

An inverse relationship exists between the summit deflation of Kilauea, as recorded by summit tilt, and the elevation of associated eruptive vents on the East Rift Zone. This relationship implies that East Rift eruptions drain the summit magma reservior to pressure levels that are dependent on the elevation of the eruptive vents.

Epp, D.; Decker, R.W.; Okamura, A.T.

1983-07-01

30

Age and petrology of the Kalaupapa Basalt, Molokai, Hawaii ( geochemistry, Sr isotopes).  

USGS Publications Warehouse

The post-erosional Kalaupapa Basalt on East Molokai, Hawaii, erupted between 0.34 and 0.57 million years ago to form the Kalaupapa Peninsula. The Kalaupapa Basalt ranges in composition from basanite to lava transitional between alkalic and tholeiitic basalt. Rare-earth and other trace-element abundances suggest that the Kalaupapa Basalt could be generated by 11-17% partial melting of a light-REE-enriched source like that from which the post-erosional lavas of the Honolulu Group on Oahu were generated by 2-11% melting. The 87Sr/86Sr ratios of the lavas range from 0.70320 to 0.70332, suggesting that the variation in composition mainly reflects variation in the melting process rather than heterogeneity of sources. The length of the period of volcanic quiescence that preceded eruption of post-erosional lavas in the Hawaiian Islands decreased as volcanism progressed from Kauai toward Kilauea. - Authors

Clague, D. A.

1982-01-01

31

Multibeam Bathymetry of Haleakala Volcano, Maui  

NASA Astrophysics Data System (ADS)

The submarine northeast flank of Haleakala Volcano, Maui was mapped in detail during the summers of 2001 and 2002 by a joint team from the Japan Marine Science and Technology Center (JAMSTEC), Tokyo Institute of Technology, University of Hawaii, and the U.S. Geological Survey. JAMSTEC instruments used included SeaBeam 2112 hull-mounted multibeam sonar (bathymetry and sidescan imagery), manned submersible Shinkai 6500 and ROV Kaiko (bottom video, photographs and sampling of Hana Ridge), gravimeter, magnetometer, and single-channel seismic system. Hana Ridge, Haleakala's submarine east rift zone, is capped by coral-reef terraces for much of its length, which are flexurally tilted towards the axis of the Hawaiian Ridge and delineate former shorelines. Its deeper, more distal portion exhibits a pair of parallel, linear crests, studded with volcanic cones, that suggest lateral migration of the rift zone during its growth. The northern face of the arcuate ridge terminus is a landslide scar in one of these crests, while its southwestern prong is a small, constructional ridge. The Hana slump, a series of basins and ridges analogous to the Laupahoehoe slump off Kohala Volcano, Hawaii, lies north of Hana Ridge and extends down to the Hawaiian moat. Northwest of this slump region a small, dual-crested ridge strikes toward the Hawaiian moat and is inferred to represent a fossil rift zone, perhaps of East Molokai Volcano. A sediment chute along its southern flank has built a large submarine fan with a staircase of contour-parallel folds on its surface that are probably derived from slow creep of sediments down into the moat. Sediments infill the basins of the Hana slump [Moore et al., 1989], whose lowermost layers have been variously back-tilted by block rotation during slumping and flexural loading of the Hawaiian Ridge; the ridges define the outer edges of those down-dropped blocks, which may have subsided several kilometers. An apron of volcaniclastic debris shed from subaerial Haleakala smoothes the upper slopes of the slump complex. The slump and apron do not extend beyond the formerly-subaerial portion of Hana Ridge, implying that supply of subaerially-erupted volcaniclastic sediments may be a necessary precondition to massive slope failure.

Eakins, B. W.; Robinson, J.

2002-12-01

32

Fluid transport properties and estimation of overpressure at the Lusi mud volcano, East Java Basin  

Microsoft Academic Search

Generation and maintenance of overpressure can prevent sediments from compaction and weaken sedimentary rocks in deep basins. Excess fluid pressure is one of the key factors to explain the disastrous mud eruption that took place in Sidoarjo, East Java, on 29 May 2006, though the mechanism by which it developed is not well known. We measured permeability and specific storage

W. Tanikawa; M. Sakaguchi; H. T. Wibowo; T. Shimamoto; O. Tadai

2009-01-01

33

Fluid transport properties and estimation of overpressure at the Lusi mud volcano, East Java Basin  

Microsoft Academic Search

Generation and maintenance of overpressure can prevent sediments from compaction and weaken sedimentary rocks in deep basins. Excess fluid pressure is one of the key factors to explain the disastrous mud eruption that took place in Sidoarjo, East Java, on 29 May 2006, though the mechanism by which it developed is not well known. We measured permeability and specific storage

Wataru Tanikawa; Masumi Sakaguchi; Handoko Teguh Wibowo; Toshihiko Shimamoto; Osamu Tadai

2010-01-01

34

Evolution of the Quaternary melitite-nephelinite Herchenberg volcano (East Eifel)  

Microsoft Academic Search

The Quaternary Herchenberg composite tephra cone (East Eifel, FR Germany) with an original bulk volume of 1.17·107 m3 (DRE of 8.2·106 m3) and dimensions of ca. 900·600·90 m (length·width·height) erupted in three main stages: (a) Initial eruptions along a NW-trending, 500-m-long fissure were dominantly Vulcanian in the northwest and Strombolian in the southeast. Removal of the unstable, underlying 20-m-thick Tertiary

Ulrich Bednarz; Hans-Ulrich Schmincke

1990-01-01

35

Multispectral thermal infrared mapping of sulfur dioxide plumes: A case study from the East Rift Zone of Kilauea Volcano, Hawaii  

USGS Publications Warehouse

The synoptic perspective and rapid mode of data acquisition provided by remote sensing are well suited for the study of volcanic SO2 plumes. In this paper we describe a plume-mapping procedure that is based on image data acquired with NASA's airborne thermal infrared multispectral scanner (TIMS) and apply the procedure to TIMS data collected over the East Rift Zone of Kilauea Volcano, Hawaii, on September 30, 1988. These image data covered the Pu'u 'O'o and Kupaianaha vents and a skylight in the lava tube that was draining the Kupaianaha lava pond. Our estimate of the SO2 emission rate from Pu'u 'O'o (17 - 20 kg s-1) is roughly twice the average of estimates derived from correlation spectrometer (COSPEC) measurements collected 10 days prior to the TIMS overflight (10 kg s-1). The agreement between the TIMS and COSPEC results improves when we compare SO2 burden estimates, which are relatively independent of wind speed. We demonstrate the feasibility of mapping Pu'u 'O'o - scale SO2 plumes from space in anticipation of the 1998 launch of the advanced spaceborne thermal emission and reflectance radiometer (ASTER). Copyright 1997 by the American Geophysical Union.

Realmuto, V. J.; Sutton, A. J.; Elias, T.

1997-01-01

36

Interpretation of time-domain electromagnetic soundings in the East Rift geothermal area of Kilauea Volcano, Hawaii  

SciTech Connect

A controlled-source time-domain electromagnetic (TDEM) sounding survey was completed on the lower portion of the East Rift of Kilauea Volcano, Hawaii (locally known as the Puna area) during the summer of 1974 as part of the geophysical task of the Hawaii Geothermal Project. Interpretations as obtained by a layered-earth TDEM inversion computer program are presented. Interpretations in terms of layered half-space models can be used to localize low-resistivity zones vertically as well as horizontally. The results show that much of the area is underlain by an anomalously conductive zone at depths of 250 to 1300 below sea level. Twenty-four TDEM soundings were attempted in the area using four different grounded wire current sources and a 42-conductor, horizontal loop sensor. The TDEM sounding data were in the form of voltages (proportional to the time derivative of the induced magnetic field) measured at discrete times after a break in the source current. Seventeen of the soundings are interpreted here.

Kauahikaua, J.

1981-01-01

37

Volcano Live  

NSDL National Science Digital Library

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

Seach, John

38

Puhimau thermal area: A window into the upper east rift zone of Ki??lauea Volcano, Hawaii?  

USGS Publications Warehouse

We report the results of two soil CO2 efflux surveys by the closed chamber circulation method at the Puhimau thermal area in the upper East Rift Zone (ERZ) of Ki??lauea volcano, Hawaii. The surveys were undertaken in 1996 and 1998 to constrain how much CO2 might be reaching the ERZ after degassing beneath the summit caldera and whether the Puhimau thermal area might be a significant contributor to the overall CO2 budget of Ki??lauea. The area was revisited in 2001 to determine the effects of surface disturbance on efflux values by the collar emplacement technique utilized in the earlier surveys. Utilizing a cutoff value of 50 g m-2 d-1 for the surrounding forest background efflux, the CO2 emission rates for the anomaly at Puhimau thermal area were 27 t d-1 in 1996 and 17 t d-1 in 1998. Water vapor was removed before analysis in all cases in order to obtain CO2 values on a dry air basis and mitigate the effect of water vapor dilution on the measurements. It is clear that Puhimau thermal area is not a significant contributor to Ki??lauea's CO2 output and that most of Ki??lauea's CO2 (8500 t d-1) is degassed at the summit, leaving only magma with its remaining stored volatiles, such as SO2, for injection down the ERZ. Because of the low CO2 emission rate and the presence of a shallow water table in the upper ERZ that effectively scrubs SO2 and other acid gases, Puhimau thermal area currently does not appear to be generally well suited for observing temporal changes in degassing at Ki??lauea. ?? Birkha??user Verlag, Basel, 2006.

McGee, K. A.; Sutton, A. J.; Elias, T.; Doukas, M. P.; Gerlach, T. M.

2006-01-01

39

Deformation signals from InSAR time series analysis related to the 2007 and 2011 east rift zone intrusions at Kilauea Volcano, Hawaii  

NASA Astrophysics Data System (ADS)

Located on the Big Island of Hawaii, Kilauea volcano is one of the most active volcanoes on Earth with continuous eruptive activity since 1983. The eruptive activity is predominately from the Pu'u O'o vent within the east rift zone, but periodic intrusions occur in the upper east rift zone between the summit and Pu'u O'o. These intrusions occur as dikes typically accompanied by fissure openings and eruptions of small volumes of lava. Interferometric synthetic aperture radar (InSAR) provides surface displacement measurements showing how the ground moves before, during, and after these intrusions. Given the recent increase in the number of active or planned SAR satellites and the more frequent repeat-pass times, InSAR is proving to be a valuable monitoring tool for volcanic hazards. Using data from Radarsat-1, Envisat, ALOS, and TerraSAR-X satellites, we generate line-of-sight InSAR time series using the small baseline subset (SBAS) which provides dense spatial and temporal coverage at Kilauea covering the 17 June 2007 and 5 March 2011 intrusions. For these two events, the summit caldera area switches from deflation to inflation months to years before both intrusions, and just prior to the intrusions we observe increased rates of inflation accompanied by elevated seismic activity in the upper east rift zone. Observations of the intrusion relate surface displacement and the response of the summit caldera area provide insight into the shallow magmatic system and the connectivity of the system. By combining InSAR time series with other geophysical data sets (such as seismic or GPS), we obtain more details about the associated hazard and a better understanding of the time-dependent relationship between what we are measuring and the controlling processes at the volcano.

Baker, S.; Amelung, F.

2011-12-01

40

Magma Reservoir Processes Revealed by Geochemistry of the Ongoing East Rift Zone Eruption, Kilauea Volcano, Hawaii  

NASA Astrophysics Data System (ADS)

Geochemical data were examined for a suite of 1,000 near-vent lava samples from the Pu`u `O`o-Kupaianaha eruption of Kilauea, collected from January 1983 through October 2001. Bulk lava and glass compositions reveal short- and long-term changes in pre-eruptive magma conditions that can be correlated with changes in edifice deformation, shallow magma transfer and eruptive behavior. Two decades of eruption on Kilauea's east rift zone has yielded ~2 km3 of lava, 97% of which is sparsely olivine-phyric with an MgO range of 6.8 to 9.6 wt%. During separate brief intervals of low-volume, fissure eruption (episodes 1 to 3 and 54), isolated rift-zone reservoirs with lower-MgO and olv-cpx-plg-phryic magma were incorporated by more mafic magma immediately prior to eruption. During prolonged, near-continuous eruption(e.g.,episodes 48-53 and most of 55), steady-state effusion is marked by cyclic variations in olivine-saturated magma chemistry. Bulk lava MgO and eruption temperature vary in cycles of monthly to bi-annual frequency, while olivine-incompatible elements vary inversely to these cycles. However, MgO-normalized values and ratios of highly to moderately incompatible elements (HINCE/MINCE), which nullify olivine fractionation effects, reveal cycles in magma chemistry that occur prior to olivine crystallization over the magmatic temperature range that is tapped by this eruption (1205-1155°C). These short-term cycles are superimposed on a long-term decrease of HINCE/MINCE, which is widely thought to reflect a 20-year change in mantle-source conditions. While HINCE/MINCE variation in primitive recharge magma cannot be ruled out, the short-term fluctuations of this signature may require unreasonably complex mantle variations. Alternatively, the correspondence of HINCE/MINCE cycles with edifice deformation and eruptive behavior suggests that the long-term evolving magmatic condition is a result of prolonged succession of short-term shallow magmatic events. The consistent limits of repeated MgO and temperature variation imply end-member magma conditions that are regulated by open-system recharge of the shallow magmatic plumbing system. The low-end of MgO variation (7 wt%) approaches the low-pressure multiphase cotectic, which is maintained by open-system replenishment of a persistent magma reservoir. The high-temperature end-member (10 wt% MgO) is probably regulated by olivine fractionation in a zone of turbulent mixing between primitive recharge magma (15 wt% MgO) and resident cotectic magma. The highest temperature magmas are associated with eruption pulses that occur in response to intrusive events at the summit and initiate short-term increases of HINCE/MINCE. Subsequent changes toward lower magmatic temperatures are associated with periods of overall summit deflation, relatively low-level effusion, and frequent eruptive pauses. The long-term trends can be explained by episodic mixing of chemically uniform recharge melt with diminishing proportions of pre-1983 summit magma (maintained at cotectic conditions). Decreasing HINCE/MINCE may signify that a greater proportion of recharge magma is being diverted directly to Pu`u `O`o with minimal summit interaction or that the mass ratio of those mixing end-members has changed due to a depleted summit chamber (or both). The coincidence of long-term summit deflation since the 1982 summit eruption suggests that shallow processes related to summit reservoir depletion may be responsible for decreasing HINCE/MINCE and Pb isotopes in post-1982 steady-state eruption products. Magma derived from a uniform mantle-source, after having flushed out older resident magma, may now completely occupy the shallow magmatic plumbing system.

Thornber, C. R.

2002-12-01

41

Historic Structure Report, St. Philomena Catholic Church (Father Damien's Church), Kalaupapa National Historical Park, Molokai, Hawaii.  

National Technical Information Service (NTIS)

The Historic Structure Report was undertaken to develop preservation treatment recommendations for St. Philomena Catholic Church at Kalaupapa National Historical Park, Molokai, Hawaii. The structure represents the early history of the settlement. The stru...

C. H. Blee H. T. McGrath L. W. Greene P. C. Cloyd R. L. Carper

1985-01-01

42

77 FR 2019 - Security Zone; Passenger Vessel SAFARI EXPLORER Arrival/Departure, Kaunakakai Harbor, Molokai, HI  

Federal Register 2010, 2011, 2012, 2013

...USCG-2011-1159] RIN 1625-AA87 Security Zone; Passenger Vessel SAFARI EXPLORER Arrival/ Departure, Kaunakakai Harbor, Molokai, HI AGENCY: Coast Guard, DHS. ACTION: Temporary interim rule with request for...

2012-01-13

43

77 FR 24381 - Security Zone; Passenger Vessel SAFARI EXPLORER Arrival/Departure, Kaunakakai Harbor, Molokai, HI  

Federal Register 2010, 2011, 2012, 2013

...USCG-2011-1159] RIN 1625-AA87 Security Zone; Passenger Vessel SAFARI EXPLORER Arrival/ Departure, Kaunakakai Harbor, Molokai, HI AGENCY: Coast Guard, DHS. ACTION: Temporary interim rule; reopening of comment...

2012-04-24

44

Magmatic history of the East Rift Zone of Kilauea Volcano, Hawaii based on drill core from SOH 1  

Microsoft Academic Search

Deep drilling has allowed for the first time an examination of most of the shield stage of a Hawaiian volcano when it is centered over the hotspot and most of its volume is produced. We determined the lithologies, ages, geochemical characteristics and accumulation rates of rocks from the continuously cored, ?1.7km deep Scientific Observation Hole (SOH) 1, which was drilled

S. L. Quane; M. O. Garcia; H. Guillou; T. P. Hulsebosch

2000-01-01

45

Crystal and magma residence at Kilauea Volcano, Hawaii: 230Th– 226Ra dating of the 1955 east rift eruption  

Microsoft Academic Search

Previous estimates of crustal storage time of magmas at Kilauea Volcano, Hawaii, range from a few years to a few thousand years, leading to considerable uncertainty in the time scales of processes of magmatic storage and differentiation. We present a new approach for determining minimum magma residence times which involves dating phenocrysts in a magma using 226Ra–230Th disequilibria, and apply

Kari M Cooper; Mary R Reid; Michael T Murrell; David A Clague

2001-01-01

46

‘New’ Antarctic volcanos  

NASA Astrophysics Data System (ADS)

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

47

SO2 from episode 48A eruption, Hawaii: Sulfur dioxide emissions from the episode 48A East Rift Zone eruption of Kilauea volcano, Hawaii  

NASA Astrophysics Data System (ADS)

An SO2 flux of 1170±400 (1?) tonnes per day was measured with a correlation spectrometer (COSPEC) in October and November 1986 from the continuous, nonfountaining, basaltic East Rift Zone eruption (episode 48A) of Kilauea volcano. This flux is 5 27 times less than those of highfountaining episodes, 3 5 times greater than those of contemporaneous summit emissions or interphase Pu'u O'o emissions, and 1.3 2 times the emissions from Pu'u O'o alone during 48A. Calculations based on the SO2 emission rate resulted in a magma supply rate of 0.44 million m3 per day and a 0.042 wt% sulfur loss from the magma upon eruption. Both of these calculated parameters agree with determinations made previously by other methods.

Andres, Rj; Kyle, Pr; Stokes, Jb; Rose, Wi

1989-12-01

48

Volcanoes Galore!  

NSDL National Science Digital Library

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

Syracuse, Mr.

2008-06-11

49

Earth's Active Volcanoes by Geographic Region  

NSDL National Science Digital Library

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

50

Multispectral thermal infrared mapping of sulfur dioxide plumes: A case study from the East Rift Zone of Kilauea Volcano, Hawaii  

Microsoft Academic Search

The synoptic perspective and rapid mode of data acquisition provided by remote sensing are well suited for the study of volcanic SO2 plumes. In this paper we describe a plume-mapping procedure that is based on image data acquired with NASA's airborne ther- mal infrared multispectral scanner (TIMS) and apply the procedure to TIMS data collected over the East Rift Zone

V. J. Realmuto; A. J. Sutton; T. Elias

1997-01-01

51

Ash from Popocatepetl Volcano  

NASA Video Gallery

The GOES-13 satellite captured this animation of an ash cloud streaming from Mexico's Popocatepetl Volcano and blowing over the town of Puebla, located to the east. This four second black and white movie was captured over several hours during the morning of April 18, 2012. > Related story > Download video

Robert Garner

2012-04-20

52

Wave and tidally-driven flowand sediment flux across a fringing coral reef: Southern Molokai, Hawaii  

Microsoft Academic Search

The fringing coral reef off the south coast of Molokai, Hawaii is currently being studied as part of a US Geological Survey (USGS) multi-disciplinary project that focuses on geologic and oceanographic processes that affect coral reef systems. For this investigation, four instrument packages were deployed across the fringing coral reef during the summer of 2001 to understand the processes governing

C. D. Storlazzi; A. S. Ogston; M. H. Bothner

53

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

NSDL National Science Digital Library

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

54

Collapsing volcanoes  

Microsoft Academic Search

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

Peter Francis; Stephen Self

1987-01-01

55

Crystallization, Fluid Exsolution, and Eruption of Extremely Volatile-rich Silicate Magma at Oldoinyo Lengai Volcano, East African Rift  

NASA Astrophysics Data System (ADS)

Oldoinyo Lengai volcano (OL) is famous for producing natrocarbonatite (NC) lava flows, yet its magmatic products are volumetrically dominated by silicate pyroclastic deposits [1]. After ~25 years of NC effusion, OL erupted explosively in 2007-2008 to produce nephelinite ash. NC effusion resumed in 2009, completing the typical historical eruptive cycle observed at OL [2]. Here we investigate the processes of magma differentiation and volatile exsolution resulting in this behavior through the study of major, trace, and volatile element compositions of nepheline-hosted melt inclusions (MI) and matrix glass (MG) in nephelinite scoria erupted in 2007-2008. The nephelinite scoria are extremely crystal rich, with nepheline and clinopyroxene dominating the phenocryst assemblage. Other phenocryst and accessory minerals include garnet, wollastonite, combeite, melilite, and sulfides. The glasses span a wide range in composition and define a cohesive evolutionary trend of decreasing SiO2 from ~46 wt% in the MI to ~38 wt% in the MG. The decrease in SiO2 is accompanied by strong enrichment in alkalis and depletion in Al2O3, resulting in extremely peralkaline MG. Rare earth elements and other incompatible elements are also strongly enriched in the MG relative to the MI. For example, the least evolved MI contain ~55 ppm Ce whereas the MG attains concentrations of >1000 ppm. Fractional crystallization modeling indicates that the evolutionary trends observed in the major element data are consistent with ~90% crystallization of the melt between the time of MI entrapment and eruption. The MI are exceptionally rich in volatiles and contain the highest CO2 concentrations (up to 2.5 wt%) ever measured in natural silicate glass, high H2O (up to 6 wt%), and high S (0.3-1.3 wt%). Immiscible NC coexists with nephelinite glass in many MI, providing clear evidence that the NC lavas and nephelinitic pyroclastics at OL are derived from a common magma [3]. The silicate MI are extremely CO2-rich, however CO2/Nb ratios are much lower than depleted upper mantle values indicating that the magma experienced prior exsolution of C-rich fluid. The MI display a trend of decreasing H2O and increasing CO2 with evolution of the melt. This trend is interpreted to reflect crystallization-driven melt evolution in a stream of C-rich fluid percolating from deeper in the magma system. Melt evolution to higher alkali and lower SiO2 contents resulted in less polymerized melt compositions and increasing CO2 solubility, whereas H2O was partitioned into the fluid phase. Crystallization and degassing of H2O led to increasing magma viscosity, which ultimately inhibited gas-magma separation and triggered the explosive eruption. Once the viscous apex of the magma chamber was expelled then quiescent degassing and NC effusion were able to resume. [1] Klaudius, J., and Keller, J. (2006) Lithos, 91: 173-190. [2] Dawson, J.B., et al. (1995) IAVCEI Proc. in Volc., 4: 70-86. [3] Mitchell, R.H. (2009) Contrib. Min. Pet.,158: 589-598.

de Moor, J.; Fischer, T. P.; King, P. L.; Hervig, R. L.; Hilton, D. R.

2011-12-01

56

Lava fountains during the episodic eruption of South-East Crater (Mt. Etna), 2000: insights into magma-gas dynamics within the shallow volcano plumbing system  

NASA Astrophysics Data System (ADS)

Mt. Etna, in Sicily (Italy) is well known for frequent effusive and explosive eruptions from both its summit and flanks. South-East Crater (SE Crater), one of the four summit craters, has been the most active in the last 20 years and often produces episodic lava fountains over periods lasting from a few weeks to months. The most striking of such eruptive phases was in 2000. Sixty four lava fountains, separated by quiescent intervals and sometimes associated with lava overflows, occurred that year between January and June, a time period during which we consider the volcano to have been in episodic eruption. This paper presents mainly results of petrochemical investigations carried out on both tephra and lavas collected during a number of the lava fountain episodes in 2000. The new data have been integrated with volcanological and seismic information in order to correlate the features of the eruptive activity with magma-gas dynamics in the plumbing system of SE Crater. The main findings allow us to characterise the 2000 episodic eruption in the framework of the recent SE Crater activity. In particular, we infer that the onset of the 2000 eruption was triggered by the ascent of new, more primitive and volatile-rich magma that progressively intruded into the SE Crater reservoir, where it mixed with the resident, more evolved magma. Furthermore, we argue that the 2000 SE Crater lava fountains largely resulted from the instability of a foam layer accumulated at the top of the underlying reservoir and rebuilt prior to each episode, in agreement with the collapsing foam model for lava fountains.

Andronico, D.; Corsaro, R. A.

2011-11-01

57

Non-hotspot volcano chains produced by migration of shear-driven upwelling toward the East Pacific Rise  

NASA Astrophysics Data System (ADS)

While most oceanic volcanism is associated with the passive rise of hot mantle beneath the spreading axes of mid-ocean ridges (MOR), volcanism occurring off-axis reflects intraplate upper-mantle dynamics and composition, yet is poorly understood. Close to the East Pacific Rise (EPR), active magmatism propagated towards the spreading center to create a series of parallel volcanic ridges on the Pacific Plate (of length ~3500 km for the Pukapuka, and ~500 km for the Sojourn, and Hotu-Matua ridges). Propagation of this volcanism by ~20 cm/a, as well as asymmetry in a variety of geophysical observables across the EPR, indicates strong lateral eastward pressure-driven flow in the asthenosphere that is driven by upwelling beneath the South Pacific Superswell [1]. Although this pattern of large-scale mantle flow can account for the propagation of intraplate melting towards the EPR, it does not explain decompression melting itself. We hypothesize that shear-driven upwelling sustains off-axis volcanism. Shear-driven upwelling is a mechanism for mantle decompression that does not require lateral density heterogeneity to drive upwelling. For example, vertical flow emerges at the edges of viscosity anomalies, if the asthenosphere is sheared horizontally [2]. These two ingredients are present in the SE Pacific, where (1) shear across the asthenosphere is inferred to be greatest worldwide [2], and (2) lateral variability in mantle viscosity is indicated by geoid lineations and anomalies in seismic tomography [3]. Eastward pressure-driven flow from the South Pacific Superswell has been suggested to break up into fingers thus providing this variability in viscosity [3]. Our three-dimensional numerical models [4] show that asthenospheric shear can excite upwelling and decompression melting at the tip of low-viscosity fingers that are propelled by vigorous sublithospheric flow. This shear-driven upwelling is able to sustain intraplate volcanism that progresses towards the MOR, spreads laterally close to the axis, and weakly continues on the opposite plate. These predictions can explain the anomalously-fast eastward progression of volcanism, and its spatial distribution near the EPR. Moreover, for a heterogeneous mantle source involving a fertile component in addition to peridotite, the predicted systematics of volcanism can account for the geochemical trend observed along the Pukapuka ridge, and the enriched anomaly of EPR MOR-basalt at 16°S-20.5°S. Our study highlights the role of horizontal asthenospheric flow and mantle heterogeneity in producing linear chains of intraplate volcanism independent of a (deep-rooted) buoyancy source. [1] Conder, J. A., D. W. Forsyth, E. M. Parmentier (2002): J. Geophys. Res., 107(B12), 2344. [2] Conrad, C. P., T. A. Bianco, E. I. Smith, P. Wessel (2011): Nature Geoscience, 4, 317-321. [3] Harmon, N., D. W. Forsyth, D. S. Weeraratne, Y. Yang, S. C. Webb (2011): Earth Planet. Sci. Lett., 311, 306-315. [4] Ballmer, M. D., C. P. Conrad, E. I. Smith, N. Harmon (2013): Geology, in press.

Ballmer, Maxim D.; Conrad, Clinton P.; Harmon, Nicholas; Smith, Eugene I.

2013-04-01

58

Anomalously high b-values in the South Flank of Kilauea volcano, Hawaii: Evidence for the distribution of magma below Kilauea's East rift zone  

USGS Publications Warehouse

The pattern of b-value of the frequency-magnitude relation, or mean magnitude, varies little in the Kaoiki-Hilea area of Hawaii, and the b-values are normal, with b = 0.8 in the top 10 km and somewhat lower values below that depth. We interpret the Kaoiki-Hilea area as relatively stable, normal Hawaiian crust. In contrast, the b-values beneath Kilauea's South Flank are anomalously high (b = 1.3-1.7) at depths between 4 and 8 km, with the highest values near the East Rift zone, but extending 5-8 km away from the rift. Also, the anomalously high b-values vary along strike, parallel to the rift zone. The highest b-values are observed near Hiiaka and Pauahi craters at the bend in the rift, the next highest are near Makaopuhi and also near Puu Kaliu. The mildest anomalies occur adjacent to the central section of the rift. The locations of the three major and two minor b-value anomalies correspond to places where shallow magma reservoirs have been proposed based on analyses of seismicity, geodetic data and differentiated lava chemistry. The existence of the magma reservoirs is also supported by magnetic anomalies, which may be areas of dike concentration, and self-potential anomalies, which are areas of thermal upwelling above a hot source. The simplest explanation of these anomalously high b-values is that they are due to the presence of active magma bodies beneath the East Rift zone at depths down to 8 km. In other volcanoes, anomalously high b-values correlate with volumes adjacent to active magma chambers. This supports a model of a magma body beneath the East Rift zone, which may widen and thin along strike, and which may reach 8 km depth and extend from Kilauea's summit to a distance of at least 40 km down rift. The anomalously high b-values at the center of the South Flank, several kilometers away from the rift, may be explained by unusually high pore pressure throughout the South Flank, or by anomalously strong heterogeneity due to extensive cracking, or by both phenomena. The major b-value anomalies are located SSE of their parent reservoirs, in the direction of motion of the flank, suggesting that magma reservoirs leave an imprint in the mobile flank. We hypothesize that the extensive cracking may have been acquired when the anomalous parts of the South Flank, now several kilometers distant from the rift zone, were generated at the rift zone near persistent reservoirs. Since their generation, these volumes may have moved seaward, away from the rift, but earthquakes occurring in them still use the preexisting complex crack distribution. Along the decollement plane at 10 km depth, the b-values are exceptionally low (b = 0.5), suggesting faulting in a more homogeneous medium. ?? 2001 Elsevier Science B.V. All rights reserved.

Wyss, M.; Klein, F.; Nagamine, K.; Wiemer, S.

2001-01-01

59

Erupting Volcanoes!  

NSDL National Science Digital Library

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

60

Computationally Modelling the Lava Dome at Soufriere Hills Volcano, Montserrat  

Microsoft Academic Search

Since November 1995 the eruption of Soufrière Hills volcano, Montserrat, has produced a Peléean dome. Originally confined within the walls of an earlier crater open to the east, the dome has overtopped the walls and since 1996 collapse events have occurred in most directions around the volcano. Many of these collapse events feed pyroclastic flows and surges down the volcano

A. J. Hale; G. Wadge

2003-01-01

61

Petrology of deep drill hole, Kilauea Volcano  

Microsoft Academic Search

The first deep drill hole (1262 m TD) at the summit of an active volcano (1102 m elev) was drilled in 1973 at Kilauea volcano, Hawaii with support from NSF and USGS. The hole is located within southern margin of Kilauea caldera in northern part of a 15 km² triangular block bounded by east rift zone, Koae fault zone, and

L. T. Grose; G. V. Keller

1976-01-01

62

Volcano Types  

NSDL National Science Digital Library

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

Camp, Victor

63

Application of synthetic aperture radar (SAR) imagery to volcano mapping in the humid tropics: a case study in East Java, Indonesia  

Microsoft Academic Search

Volcanoes in humid tropical environments are frequently cloud covered, typically densely vegetated and rapidly eroded. These\\u000a factors complicate field and laboratory studies and even the basic identification of potentially active volcanoes. Numerous\\u000a previous studies have highlighted the potential value of radar remote sensing for volcanology in equatorial regions. Here,\\u000a cloud- and vegetation-penetrating LHH-band (??24?cm) synthetic aperture radar (SAR) data from

Simon A. Carn

1999-01-01

64

Sequential change in intensity and magma supply of the Hoei eruption, Fuji Volcano, Japan (AD 1707)  

Microsoft Academic Search

Fuji volcano, which is the most famous mountain in Japan, is also one of the most dangerous volcanoes in the country. The AD 1707 eruption of the volcano, known as Hoei eruption, caused severe damage in the downwind area, including Tokyo and Yokohama approximately 100 km east of the volcano. We reconstructed the sequence and change in mass discharge rate

K. Mannen; M. Naomichi

2010-01-01

65

Decade Volcanoes  

NSDL National Science Digital Library

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

2007-11-02

66

Volcano spacing and plate rigidity  

SciTech Connect

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

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

1991-04-01

67

Geology of Kilauea volcano  

SciTech Connect

This paper summarizes studies of the structure, stratigraphy, petrology, drill holes, eruption frequency, and volcanic and seismic hazards of Kilauea volcano. All the volcano is discussed, but the focus is on its lower east rift zone (LERZ) because active exploration for geothermal energy is concentrated in that area. Kilauea probably has several separate hydrothermal-convection systems that develop in response to the dynamic behavior of the volcano and the influx of abundant meteoric water. Important features of some of these hydrothermal-convection systems are known through studies of surface geology and drill holes. Observations of eruptions during the past two centuries, detailed geologic mapping, radiocarbon dating, and paleomagnetic secular-variation studies indicate that Kilauea has erupted frequently from its summit and two radial rift zones during Quaternary time. Petrologic studies have established that Kilauea erupts only tholeiitic basalt. Extensive ash deposits at Kilauea's summit and on its LERZ record locally violent, but temporary, disruptions of local hydrothermal-convection systems during the interaction of water or steam with magma. Recent drill holes on the LERZ provide data on the temperatures of the hydrothermal-convection systems, intensity of dike intrusion, porosity and permeability, and an increasing amount of hydrothermal alteration with depth. The prehistoric and historic record of volcanic and seismic activity indicates that magma will continue to be supplied to deep and shallow reservoirs beneath Kilauea's summit and rift zones and that the volcano will be affected by eruptions and earthquakes for many thousands of years. 71 refs., 2 figs.

Moore, R.B. (Geological Survey, Denver, CO (United States). Federal Center); Trusdell, F.A. (Geological Survey, Hawaii National Park, HI (United States). Hawaiian Volcano Observatory)

1993-08-01

68

Collapsing volcanoes  

NASA Astrophysics Data System (ADS)

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

Francis, Peter; Self, Stephen

1987-06-01

69

Model Volcanoes  

NSDL National Science Digital Library

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

70

Cascade Volcanoes  

USGS Multimedia Gallery

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

2009-12-08

71

Determination of Diphacinone in Sea Water, Vertebrates, Invertebrates, and Bait Pellet Formulations Following Aerial Broadcast on Mokapu Island, Molokai, Hawaii.  

National Technical Information Service (NTIS)

This report presents the results of a study to determine diphacinone concentrations in samples of sea water and in fillet samples of fish and in limpets from the ocean adjacent to Mokapu Island and from reference samples from Molokai, Hawaii; concentratio...

C. E. Orazio M. Tanner R. W. Gale

2008-01-01

72

Spreading volcanoes  

USGS Publications Warehouse

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

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

2000-01-01

73

Volcano Baseball  

NSDL National Science Digital Library

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

Science, American A.

2009-01-01

74

Volcano survey  

Microsoft Academic Search

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

H. Tazieff

1966-01-01

75

Scoping Meeting Summary, Kaunakakai, Moloka'i, March 12, 1992, 2 PM Session  

SciTech Connect

The meeting began with presentations by the facilitator, Mr. Spiegel, and Dr. Lewis, the program manager from DOE. The facilitator introduced those on the podium. He then described the general structure of the meeting and its purpose: to hear the issues and concerns of those present regarding the proposed Hawaiian Geothermal Project. He described his role as assuring the impartiality and fairness of the meeting. Dr. Lewis of DOE further defined the scope of the project, introduced members of the EIS team, and briefly described.the EIS process. The overwhelming concerns of the meeting were Native Hawaiian issues. The presenters [more than 70%, most of whom addressed no other issue] want the EIS to respect Native Hawaiian religion, race, rights, language, and culture, noting that they believe that geothermal development is a desecration of Pele [{approx}60% of all presenters]. They expressed concern that their ancestors and burials should not be desecrated. The EIS should address Native Hawaiian concerns that the HGP would negatively impact Native Hawaiian fisheries, subsistence lifestyles, and religious practices. Virtually all the speakers expressed frustration with government. Most (> 70%) of the speakers voiced concern and frustration regarding lack of consideration for Native Hawaiians by government and lack of trust in government. One commenter requested that the EIS should consider the international implications of the U.S allowing their rainforests to be cleared, when the U.S. government asks other nations to preserve theirs. Nearly 30% of the commenters want the EIS to address the concern that people on Moloka'i will bear major environmental consequences of the HGP, but not gain from it. The commenters question whether it is right for Moloka'i to pay for benefits to Oahu, particularly using an unproven technology. After questioning the reliability and feasibility of the marine cable:, nearly 30% of the presenters were concerned about the impacts of the submarine cable. In specific, they suggested that the EIS investigate the impacts the cable would have on fisheries and marine life due to electromagnetic fields, dredging, and oil-release. The EIS should study the impacts of the HGP on the humpback whale and other marine species, particularly their birthing grounds, noting whales' hypersensitivity to emf and sound. One commenter suggested that the EIS examine the economics of the cable, including the need to build specialized ships to lay it, harbour(s), and the cable itself. One commenter was concerned about the future uses of the cable suggesting that the EIS should address the impacts that would result if the cable connecting Moloka'i to Oahu is used to transmit power from large coal or other types of power generation facilities constructed on Moloka'i. Commenters questioned the reliability of geothermal development in a region that is both seismically and volcanically active. One suggested that the EIS examine the merits of projects that conserve energy. With respect to land use, commenters asked that the EIS examine the propriety of using Native Hawaiian homelands and ceded lands for the HGP, questioning specifically the land exchange in Puna [Campbell Estate for Wao Kele o Puna]. The commenters want the EIS to address the issue of air, water and sail quality preservation. More than 20% of the commenters asked that the EIS examine concerns about the environmental consequences of the HGP to the rainforest, including possible species extinction. In particular, the EIS should address the impacts of roads associated with the HGP in the rainforest, including the resulting importation of exotic species (for example banana poko), which successfully compete against native species; and the effects of noise and fumes which negatively impact plants, birds, animals, and insects.

Quinby-Hunt, Mary S.

1992-06-01

76

Coral proxy record of decadal-scale reduction in base flow from Moloka'i, Hawaii  

NASA Astrophysics Data System (ADS)

Groundwater is a major resource in Hawaii and is the principal source of water for municipal, agricultural, and industrial use. With a growing population, a long-term downward trend in rainfall, and the need for proper groundwater management, a better understanding of the hydroclimatological system is essential. Proxy records from corals can supplement long-term observational networks, offering an accessible source of hydrologic and climate information. To develop a qualitative proxy for historic groundwater discharge to coastal waters, a suite of rare earth elements and yttrium (REYs) were analyzed from coral cores collected along the south shore of Moloka'i, Hawaii. The coral REY to calcium (Ca) ratios were evaluated against hydrological parameters, yielding the strongest relationship to base flow. Dissolution of REYs from labradorite and olivine in the basaltic rock aquifers is likely the primary source of coastal ocean REYs. There was a statistically significant downward trend (-40%) in subannually resolved REY/Ca ratios over the last century. This is consistent with long-term records of stream discharge from Moloka'i, which imply a downward trend in base flow since 1913. A decrease in base flow is observed statewide, consistent with the long-term downward trend in annual rainfall over much of the state. With greater demands on freshwater resources, it is appropriate for withdrawal scenarios to consider long-term trends and short-term climate variability. It is possible that coral paleohydrological records can be used to conduct model-data comparisons in groundwater flow models used to simulate changes in groundwater level and coastal discharge.

Prouty, Nancy G.; Jupiter, Stacy D.; Field, Michael E.; McCulloch, Malcolm T.

2009-12-01

77

Volcanic hazards at Atitlan volcano, Guatemala  

USGS Publications Warehouse

Atitlan Volcano is in the Guatemalan Highlands, along a west-northwest trending chain of volcanoes parallel to the mid-American trench. The volcano perches on the southern rim of the Atitlan caldera, which contains Lake Atitlan. Since the major caldera-forming eruption 85 thousand years ago (ka), three stratovolcanoes--San Pedro, Toliman, and Atitlan--have formed in and around the caldera. Atitlan is the youngest and most active of the three volcanoes. Atitlan Volcano is a composite volcano, with a steep-sided, symmetrical cone comprising alternating layers of lava flows, volcanic ash, cinders, blocks, and bombs. Eruptions of Atitlan began more than 10 ka [1] and, since the arrival of the Spanish in the mid-1400's, eruptions have occurred in six eruptive clusters (1469, 1505, 1579, 1663, 1717, 1826-1856). Owing to its distance from population centers and the limited written record from 200 to 500 years ago, only an incomplete sample of the volcano's behavior is documented prior to the 1800's. The geologic record provides a more complete sample of the volcano's behavior since the 19th century. Geologic and historical data suggest that the intensity and pattern of activity at Atitlan Volcano is similar to that of Fuego Volcano, 44 km to the east, where active eruptions have been observed throughout the historical period. Because of Atitlan's moderately explosive nature and frequency of eruptions, there is a need for local and regional hazard planning and mitigation efforts. Tourism has flourished in the area; economic pressure has pushed agricultural activity higher up the slopes of Atitlan and closer to the source of possible future volcanic activity. This report summarizes the hazards posed by Atitlan Volcano in the event of renewed activity but does not imply that an eruption is imminent. However, the recognition of potential activity will facilitate hazard and emergency preparedness.

Haapala, J. M.; Escobar Wolf, R.; Vallance, James W.; Rose, W. I.; Griswold, J. P.; Schilling, S. P.; Ewert, J. W.; Mota, M.

2006-01-01

78

The LUSI mud volcano triggering controversy: Was it caused by drilling?  

Microsoft Academic Search

Following the Yogyakarta earthquake on May 27th, 2006, the subsequent eruption of a mud volcano has been closely observed and analyzed by the geological community. The mud volcano, known as LUSI, began erupting near the Banjarpanji-1 exploration well in Sidoarjo, East Java, Indonesia. LUSI offers a unique opportunity to study the genesis and development of a mud volcano.For the first

Nurrochmat Sawolo; Edi Sutriono; Bambang P. Istadi; Agung B. Darmoyo

2009-01-01

79

Quantity, composition, and source of sediment collected in sediment traps along the fringing coral reef off Molokai, Hawaii  

Microsoft Academic Search

Sediment traps were used to evaluate the frequency, cause, and relative intensity of sediment mobility\\/resuspension along the fringing coral reef off southern Molokai (February 2000–May 2002). Two storms with high rainfall, floods, and exceptionally high waves resulted in sediment collection rates>1000 times higher than during non-storm periods, primarily because of sediment resuspension by waves. Based on quantity and composition of

Michael H. Bothner; Richard L. Reynolds; Michael A. Casso; Curt D. Storlazzi; Michael E. Field

2006-01-01

80

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

USGS Publications Warehouse

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

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

2003-01-01

81

High Resolution Seismic Attenuation Tomography at Medicine Lake Volcano, California.  

National Technical Information Service (NTIS)

Medicine Lake Volcano, a broad shield volcano about 50km east of Mount Shasta in northern California, produced rhylotic eruptions as recently as 400 years ago. Because of this recent activity it is of considerable interest to producers of geothermal energ...

J. J. Zucca P. W. Kasameyer

1987-01-01

82

Debris Avalanche Formation at Kick'em Jenny Submarine Volcano  

Microsoft Academic Search

Kick'em Jenny submarine volcano near Grenada is the most active volcanic center in the Lesser Antilles arc. Multibeam surveys of the volcano by NOAA in 2002 revealed an arcuate fault scarp east of the active cone, suggesting flank collapse. More extensive NOAA surveys in 2003 demonstrated the presence of an associated debris avalanche deposit, judging from their surface morphologic expression

H. Sigurdsson; S. N. Carey; D. Wilson

2005-01-01

83

Volcano Explorer: Build A Virtual Volcano  

NSDL National Science Digital Library

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

84

Volcano Lovers  

NSDL National Science Digital Library

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

Tenenbaum, David

1997-01-02

85

The Electronic Volcano  

NSDL National Science Digital Library

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

86

Earth Layers and Volcanoes  

NSDL National Science Digital Library

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

Brookeshallow

2011-04-13

87

Landslides on the windward flanks of Oahu and Molokai, Hawaii: Shinkai 6500 submersible investigations  

NASA Astrophysics Data System (ADS)

The submarine geology of the Nuuanu (perhaps the largest landslide in the world) and Wailau landslides was investigated during 1999, using the SHINKAI 6500 manned submersible and its mother ship, R.V. YOKOSUKA. Observations were made at eight dive sites, and about 100 in-situ rock samples were collected from the landslide deposits at depths of 2500 to 4500 m. Based on video images and rock samples, the outcrops are subdivided into three basic types, each with several facies: (1) products of volcanic eruptions, (2) coarse volcaniclastic deposits, and (3) unconsolidated and reworked epiclastic sediments. The coarse volcaniclastic deposits are thought to have originated from debris flows in alluvial-fan systems. Unconsolidated muddy gravel is abundant in submarine channels and piedmont slopes; this facies is considered to be the product of reworked sediment in submarine channel systems and small-scale slope failures. These facies comprise most of the megablocks and the apron of Oahu. The steep cliffs of many megablocks can be reasonably fitted together like a jigsaw puzzle. The megablocks can be graphically re-joined to form a huge slab that can be extrapolated back to the submarine eastern flanks of Oahu, at ocean depths of 1000 to 3000 m. Growth of the pre-failure volcaniclastic apron has been enhanced by debris supplied by subaerial erosion from the windward, rainy sides of Oahu and Molokai. Thus, the exceptional size of the landslides described here may have been influenced by heavy trade-wind rainfall.

Yokose, Hisayoshi

88

Super Volcano  

NSDL National Science Digital Library

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

89

Types of Volcanoes  

NSDL National Science Digital Library

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

90

Gravity model studies of Newberry Volcano, Oregon  

SciTech Connect

Newberry, Volcano, a large Quaternary volcano located about 60 km east of the axis of the High Cascades volcanoes in central Oregon, has a coincident positive residual gravity anomaly of about 12 mGals. Model calculations of the gravity anomaly field suggest that the volcano is underlain by an intrusive complex of mafic composition of about 20-km diameter and 2-km thickness, at depths above 4 km below sea level. However, uplifted basement in a northwest trending ridge may form part of the underlying excess mass, thus reducing the volume of the subvolcanic intrusive. A ring dike of mafic composition is inferred to intrude to near-surface levels along the caldera ring fractures, and low-density fill of the caldera floor probably has a thickness of 0.7--0.9 km. The gravity anomaly attributable to the volcano is reduced to the east across a north-northwest trending gravity anomaly gradient through Newberry caldera and suggests that normal, perhaps extensional, faulting has occurred subsequent to caldera formation and may have controlled the location of some late-stage basaltic and rhyolitic eruptions. Significant amounts of felsic intrusive material may exist above the mafic intrusive zone but cannot be resolved by the gravity data.

Gettings, M.E.; Griscom, A.

1988-09-10

91

Gravity model studies of Newberry Volcano, Oregon  

USGS Publications Warehouse

Newberry Volcano, a large Quaternary volcano located about 60 km east of the axis of the High Cascades volcanoes in central Oregon, has a coincident positive residual gravity anomaly of about 12 mGals. Model calculations of the gravity anomaly field suggest that the volcano is underlain by an intrusive complex of mafic composition of about 20-km diameter and 2-km thickness, at depths above 4 km below sea level. However, uplifted basement in a northwest trending ridge may form part of the underlying excess mass, thus reducing the volume of the subvolcanic intrusive. A ring dike of mafic composition is inferred to intrude to near-surface levels along the caldera ring fractures, and low-density fill of the caldera floor probably has a thickness of 0.7-0.9 km. The gravity anomaly attributable to the volcano is reduced to the east across a north-northwest trending gravity anomaly gradient through Newberry caldera and suggests that normal, perhaps extensional, faulting has occurred subsequent to caldera formation and may have controlled the location of some late-stage basaltic and rhyolitic eruptions. Significant amounts of felsic intrusive material may exist above the mafic intrusive zone but cannot be resolved by the gravity data. -Authors

Gettings, M. E.; Griscom, A.

1988-01-01

92

Volcano-Tectonic Deformation at Taal Volcano, Philippines  

NASA Astrophysics Data System (ADS)

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

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

2004-12-01

93

Volcanoes: Annenberg Media Project  

NSDL National Science Digital Library

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

1997-01-01

94

Optimizing Remote Sensing and GIS Tools for Mapping and Managing the Distribution of an Invasive Mangrove (Rhizophora mangle) on South Molokai, Hawaii  

Microsoft Academic Search

In 1902, the Florida red mangrove, Rhizophora mangle L., was introduced to the island of Molokai, Hawaii, and has since colonized nearly 25% of the south coast shoreline. By classifying three kinds of remote sensing imagery, we compared abilities to detect invasive mangrove distributions and to discriminate mangroves from surrounding terrestrial vegetation. Using three analytical techniques, we compared mangrove mapping

Mimi Diorio; Stacy D. Jupiter; Susan A. Cochran; Donald C. Potts

2007-01-01

95

Aircraft Accident Report - Aloha Islandair, Inc., Flight 1712 De Havilland Twin Otter, DHC-6-300, N707PV Halawa Point, Molokai, Hawaii October 28, 1989.  

National Technical Information Service (NTIS)

The report explains the crash of Aloha Island Air flight 1712, a de Havilland Twin Otter DHC-6-300 near Halawa Bay, Molokai, Hawaii, on October 28, 1989. The safety issues discussed in the report are surveillance of 14 CFR Part 135 operators by the Federa...

1990-01-01

96

Aerosol Lesson: Volcano Types  

NSDL National Science Digital Library

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

97

Where are the Volcanoes?  

NSDL National Science Digital Library

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

Fries-Gaither, Jessica

98

The Volcano Adventure Guide  

Microsoft Academic Search

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

Fraser Goff

2005-01-01

99

A Scientific Excursion: Volcanoes.  

ERIC Educational Resources Information Center

|Reviews an educationally valuable and reasonably well-designed simulation of volcanic activity in an imaginary land. VOLCANOES creates an excellent context for learning information about volcanoes and for developing skills and practicing methods needed to study behavior of volcanoes. (Author/JN)|

Olds, Henry, Jr.

1983-01-01

100

How Volcanoes Work  

NSDL National Science Digital Library

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

2011-04-18

101

Focus: alien volcanos  

NASA Astrophysics Data System (ADS)

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

Carroll, Michael; Lopes, Rosaly

2007-03-01

102

Cascades Volcano Observatory  

NSDL National Science Digital Library

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

2010-09-15

103

Glaciation of Haleakala volcano, Hawaii  

SciTech Connect

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

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

1993-04-01

104

Mafic Plinian volcanism and ignimbrite emplacement at Tofua volcano, Tonga  

Microsoft Academic Search

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

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

105

Geologic Mapping, Volcanic Stages and Magmatic Processes in Hawaiian Volcanoes  

NASA Astrophysics Data System (ADS)

The concept of volcanic stages arose from geologic mapping of Hawaiian volcanoes. Subaerial Hawaiian lava successions can be divided generally into three constructional phases: an early (shield) stage dominated by thin-bedded basaltic lava flows commonly associated with a caldera; a later (postshield) stage with much thicker bedded, generally lighter colored lava flows commonly containing clinopyroxene; calderas are absent in this later stage. Following periods of quiescence of a half million years or more, some Hawaiian volcanoes have experienced renewed (rejuvenated) volcanism. Geological and petrographic relations irrespective of chemical composition led to the identification of mappable units on Niihau, Kauai, Oahu, Molokai, Maui and Hawaii, which form the basis for this 3-fold division of volcanic activity. Chemical data have complicated the picture. There is a growing tendency to assign volcanic stage based on lava chemistry, principally alkalicity, into tholeiitic shield, alkalic postshield, and silica undersaturated rejuvenation, despite the evidence for interbedded tholeiitic and alkalic basalts in many shield formations, and the presence of mildly tholeiitic lavas in some postshield and rejuvenation formations. A consistent characteristic of lava compositions from most postshield formations is evidence for post-melting evolution at moderately high pressures (3-7 kb). Thus, the mapped shield to postshield transitions primarily reflect the disappearance of shallow magma chambers (and associated calderas) in Hawaiian volcanoes, not the earlier (~100 ka earlier in Waianae Volcano) decline in partial melting that leads to the formation of alkalic parental magmas. Petrological signatures of high-pressure evolution are high-temperature crystallization of clinopyroxene and delayed crystallization of plagioclase, commonly to <3 % MgO. Petrologic modeling using pMELTS and MELTS algorithms allows for quantification of the melting and fractionation conditions giving rise to various Hawaiian lithologies. This analysis indicates that the important magmatic process that links geologic mapping to volcanic stage is thermal state of the volcano, as manifest by depth of magma evolution. The only criterion for rejuvenation volcanism is the presence of a significant time break (more than several hundred thousand years) preceding eruption.

Sinton, J. M.

2005-12-01

106

Volcano Seismology  

NASA Astrophysics Data System (ADS)

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

Chouet, B.

107

Volcanoes: Nature's Caldrons Challenge Geochemists.  

ERIC Educational Resources Information Center

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

Zurer, Pamela S.

1984-01-01

108

Volcanoes: Nature's Caldrons Challenge Geochemists.  

ERIC Educational Resources Information Center

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

Zurer, Pamela S.

1984-01-01

109

Volcanoes of North America  

NASA Astrophysics Data System (ADS)

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

Wood, Charles Arthur; Kienle, Jürgen

1992-11-01

110

Galactic Super Volcano Similar to Iceland Volcano  

NASA Video Gallery

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

Jim Wilson

2010-08-27

111

Active high-resolution seismic tomography of compressional wave velocity and attenuation structure at Medicine Lake volcano, northern California Cascade Range  

Microsoft Academic Search

We determine compressional wave velocity and attenuation structures for the upper crust beneath Medicine Lake volcano in northeast California using a high-resolution active source seismic tomography method. Medicine Lake volcano is a basalt through rhyolite shield volcano of the Cascade Range, lying east of the range axis. The Pg wave from eight explosive sources which has traveled upward through the

John R. Evans; John J. Zucca

1988-01-01

112

Fractal properties of tremor and gas piston events observed at Kilauea Volcano, Hawaii  

Microsoft Academic Search

We study the fractal properties of shallow volcanic tremor and gas piston events associated with magma degassing at Kilauea Volcano, Hawaii, using data from two dense short-baseline arrays of seismographs deployed near the active crater of Puu Oo on the east rift of the volcano. We found an upper bound on the fractal dimension of a strange attractor common to

Bernard Chouet; Herbert R. Shaw

1991-01-01

113

Submersible study of mud volcanoes seaward of the Barbados accretionary wedge: sedimentology, structure and rheology  

Microsoft Academic Search

In 1992, the Nautile went to a mud volcano field located east of the Barbados accretionary wedge near 13 ° 50N. Using nannofossil analysis on cores, we determined the sedimentation rate, and provided a new estimation of the age of the mud volcanoes (750,000 years for the oldest one). Six structures have been explored with the submersible Nautile, and manifestations

Sophie Lance; Pierre Henry; Xavier Le Pichon; Siegfried Lallemant; Hervé Chamley; Frauke Rostek; Jean-Claude Faugères; Eliane Gonthier; Karine Olu

1998-01-01

114

Sizes of Conical Volcanoes  

Microsoft Academic Search

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

P. W. Francis; B. M. Abbott

1973-01-01

115

Mud volcanoes on Mars?  

NASA Astrophysics Data System (ADS)

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

Komar, Paul D.

1991-06-01

116

Submarine picritic basalts from Ko'olau Volcano, Hawai'i: Implications for parental magma compositions and mantle source  

NASA Astrophysics Data System (ADS)

Previous studies of Ko'olau Volcano subaerial basalts have invoked melting of recycled oceanic crust (garnet pyroxenite) as a mantle source to explain the unusually high SiO2 (53-55 wt.%), moderate MgO (6-8 wt.%) and low olivine contents (<5 vol.%) of these lavas. To evaluate whether such usual lavas form the bulk of Ko'olau Volcano, we sampled for the first time the dissected flanks of this volcano and the landslide blocks derived from Ko'olau and the volcanoes on the neighboring island of Molokai using the SHINKAI 6500 submersible, the remotely operated vehicle (ROV) KAIKO and dredging. Olivine-rich basalts (>10 vol.%) with high MgO contents (14 to 31.5 wt.%) are abundant among submarine Ko'olau lavas. Many of these picritic lavas have accumulated olivine, including xenocrysts with one or more subgrain boundaries. However, euhedral, undeformed olivine with forsterite contents of 88-90% and normal zoning is the dominant crystal type in these Ko'olau submarine basalts. Olivine CaO contents are moderate (0.16-0.27 wt%) and NiO contents are generally high (up to 0.60 wt%) compared to olivines from other Hawaiian volcanoes. These results indicate that subaerial Ko'olau exposures give a biased sampling of the volcano and that the olivines in these submarine lavas grew at crustal depths in parental magmas with MgO contents of at least 14-15 wt.%. Thus, they were primarily derived from melting peridotite, like other Hawaiian tholeiitic magmas. The wide range in olivine CaO contents indicates that there is a much greater range in Ko'olau parental magma compositions than observed for subaerial lavas.

Garcia, Michael O.

117

Mangroves and shoreline change on Molokai, Hawaii: Assessing the role of introduced Rhizophora mangle in sediment dynamics and coastal change using remote sensing and GIS  

Microsoft Academic Search

The Florida red mangrove, Rhizophora mangle, was introduced to the high volcanic island of Molokai, Hawaii in 1902 to trap sediment and stabilize eroding coastal mudflats along the island's reef-fringed south coast. This prolific invasive species now occupies 2.4 km2 of inter-tidal land and borders approximately 20% of the south coast shoreline. Integrating the fundamentals of remote sensing and Geographical

Margaret Mary D'Iorio

2003-01-01

118

Anatomy of a Volcano  

NSDL National Science Digital Library

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

119

Chaiten Volcano Still Active  

NSDL National Science Digital Library

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

120

Mud Volcanoes on Mars.  

National Technical Information Service (NTIS)

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

P. D. Komar

1991-01-01

121

Groundwater at Mayon, Volcano  

Microsoft Academic Search

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

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

2001-01-01

122

Alaska Volcano Observatory  

NSDL National Science Digital Library

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

123

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

NASA Astrophysics Data System (ADS)

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

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

2003-04-01

124

Active Lava Flow near Hawai'i Volcanoes National Park  

USGS Multimedia Gallery

Areas of flowing lava show up as bright spots in this image of the active lava flow that extends south from the east rift to the ocean, near the eastern boundary of Hawai'i Volcanoes National Park. The image is a composite of a regular photo and a new ARRA-funded thermal infrared camera that will be...

2010-05-20

125

AVO: Alaska Volcano Observatory  

NSDL National Science Digital Library

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

126

Pavlof Volcano From Station  

NASA Website

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

127

Volcanoes in the Infrared  

NSDL National Science Digital Library

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

Foundation, Wgbh E.

2009-02-27

128

Volcano Watch Satellite Images  

NSDL National Science Digital Library

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

129

Volcano Monitoring Techniques  

NSDL National Science Digital Library

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

130

Earthquakes - Volcanoes (Causes - Forecast - Counteraction)  

NASA Astrophysics Data System (ADS)

Earthquakes and volcanoes are caused by: 1)Various liquid elements (e.g. H20, H2S, S02) which emerge from the pyrosphere and are trapped in the space between the solid crust and the pyrosphere (Moho discontinuity). 2)Protrusions of the solid crust at the Moho discontinuity (mountain range roots, sinking of the lithosphere's plates). 3)The differential movement of crust and pyrosphere. The crust misses one full rotation for approximately every 100 pyrosphere rotations, mostly because of the lunar pull. The above mentioned elements can be found in small quantities all over the Moho discontinuity, and they are constantly causing minor earthquakes and small volcanic eruptions. When large quantities of these elements (H20, H2S, SO2, etc) concentrate, they are carried away by the pyrosphere, moving from west to east under the crust. When this movement takes place under flat surfaces of the solid crust, it does not cause earthquakes. But when these elements come along a protrusion (a mountain root) they concentrate on its western side, displacing the pyrosphere until they fill the space created. Due to the differential movement of pyrosphere and solid crust, a vacuum is created on the eastern side of these protrusions and when the aforementioned liquids overfill this space, they explode, escaping to the east. At the point of their escape, these liquids are vaporized and compressed, their flow accelerates, their temperature rises due to fluid friction and they are ionized. On the Earth's surface, a powerful rumbling sound and electrical discharges in the atmosphere, caused by the movement of the gasses, are noticeable. When these elements escape, the space on the west side of the protrusion is violently taken up by the pyrosphere, which collides with the protrusion, causing a major earthquake, attenuation of the protrusions, cracks on the solid crust and damages to structures on the Earth's surface. It is easy to foresee when an earthquake will occur and how big it is going to be, when we know the record of specific earthquakes and the routes they have followed towards the East. For example, to foresee an earthquake in the Mediterranean region, we take starting point earthquakes to Latin America (0°-40°).The aforementioned elements will reach Italy in an average time period of 49 days and Greece in 53 days. The most reliable preceding phenomenon to determine the epicenter of an earthquake is the rise of the crust's temperature at the area where a large quantity of elements is concentrated, among other phenomena that can be detected either by instruments or by our senses. When there is an active volcano along the route between the area where the "starting-point" earthquake occurred and the area where we expect the same elements to cause a new earthquake, it is possible these elements will escape through the volcano's crater, carrying lava with them. We could contribute to that end, nullifying earthquakes that might be triggered by these elements further to the east, by using manmade resources, like adequate quantities of explosives at the right moment.

Tsiapas, Elias

2013-04-01

131

Hazard maps of Colima volcano, Mexico  

NASA Astrophysics Data System (ADS)

Colima volcano, also known as Volcan de Fuego (19° 30.696 N, 103° 37.026 W), is located on the border between the states of Jalisco and Colima and is the most active volcano in Mexico. Began its current eruptive process in February 1991, in February 10, 1999 the biggest explosion since 1913 occurred at the summit dome. The activity during the 2001-2005 period was the most intense, but did not exceed VEI 3. The activity resulted in the formation of domes and their destruction after explosive events. The explosions originated eruptive columns, reaching attitudes between 4,500 and 9,000 m.a.s.l., further pyroclastic flows reaching distances up to 3.5 km from the crater. During the explosive events ash emissions were generated in all directions reaching distances up to 100 km, slightly affected nearby villages as Tuxpan, Tonila, Zapotlán, Cuauhtemoc, Comala, Zapotitlan de Vadillo and Toliman. During the 2005 this volcano has had an intense effusive-explosive activity, similar to the one that took place during the period of 1890 through 1900. Intense pre-plinian eruption in January 20, 1913, generated little economic losses in the lower parts of the volcano due to low population density and low socio-economic activities at the time. Shows the updating of the volcanic hazard maps published in 2001, where we identify whit SPOT satellite imagery and Google Earth, change in the land use on the slope of volcano, the expansion of the agricultural frontier on the east and southeast sides of the Colima volcano, the population inhabiting the area is approximately 517,000 people, and growing at an annual rate of 4.77%, also the region that has shown an increased in the vulnerability for the development of economic activities, supported by the construction of highways, natural gas pipelines and electrical infrastructure that connect to the Port of Manzanillo to Guadalajara city. The update the hazard maps are: a) Exclusion areas and moderate hazard for explosive events (rockfall) and pyroclastic flows, b) Hazard map of lahars and debris flow, and c) Hazard map of ash-fall. The cartographic and database information obtained will be the basis for updating the Operational Plan of the Colima Volcano by the State Civil & Fire Protection Unit of Jalisco, Mexico, and the urban development plans of surrounding municipalities, in order to reduce their vulnerability to the hazards of the volcanic activity.

Suarez-Plascencia, C.; Nunez-Cornu, F. J.; Escudero Ayala, C. R.

2011-12-01

132

Volcanoes: Coming Up from Under.  

ERIC Educational Resources Information Center

|Provides specific information about the eruption of Mt. St. Helens in March 1980. Also discusses how volcanoes are formed and how they are monitored. Words associated with volcanoes are listed and defined. (CS)|

Science and Children, 1980

1980-01-01

133

Wave- and tidally-driven flow and sediment flux across a fringing coral reef: Southern Molokai, Hawaii  

USGS Publications Warehouse

The fringing coral reef off the south coast of Molokai, Hawaii is currently being studied as part of a US Geological Survey (USGS) multi-disciplinary project that focuses on geologic and oceanographic processes that affect coral reef systems. For this investigation, four instrument packages were deployed across the fringing coral reef during the summer of 2001 to understand the processes governing fine-grained terrestrial sediment suspension on the shallow reef flat (h=1m) and its advection across the reef crest and onto the deeper fore reef. The time-series measurements suggest the following conceptual model of water and fine-grained sediment transport across the reef: Relatively cool, clear water flows up onto the reef flat during flooding tides. At high tide, more deep-water wave energy is able to propagate onto the reef flat and larger Trade wind-driven waves can develop on the reef flat, thereby increasing sediment suspension. Trade wind-driven surface currents and wave breaking at the reef crest cause setup of water on the reef flat, further increasing the water depth and enhancing the development of depth-limited waves and sediment suspension. As the tide ebbs, the water and associated suspended sediment on the reef flat drains off the reef flat and is advected offshore and to the west by Trade wind- and tidally- driven currents. Observations on the fore reef show relatively high turbidity throughout the water column during the ebb tide. It therefore appears that high suspended sediment concentrations on the deeper fore reef, where active coral growth is at a maximum, are dynamically linked to processes on the muddy, shallow reef flat.

Storlazzi, C. D.; Ogston, A. S.; Bothner, M. H.; Field, M. E.; Presto, M. K.

2004-01-01

134

Seismic imaging of the deep structure under the Chinese volcanoes: An overview  

NASA Astrophysics Data System (ADS)

The rapid development of provincial seismic networks and portable seismic arrays has provided a good opportunity to image the detailed 3-D seismic structure of the upper mantle under the active volcanoes in the Chinese continent. Under the Changbaishan (Tianchi) volcano prominent low-velocity (low-V) anomalies are imaged above 400 km depth, and high-velocity (high-V) anomalies are detected within the mantle transition zone, suggesting that the Changbaishan volcano is a back-arc volcano related to the dehydration of the subducted Pacific slab that is stagnant in the mantle transition zone. Seismic structures under the Tengchong volcano are similar to those under the Changbaishan volcano, whereas the subducted slab under the Tengchong volcano is the continental Indian slab. Regional and global tomographic models illustrate that obvious low-V anomalies are visible under the Hainan volcano from the crust down to the lower mantle, suggesting that the Hainan volcano is a hotspot. A recent local tomographic model shows that the Hainan plume is imaged as a southeast tilted low-V anomaly with depth in the upper mantle. A high-resolution upper-mantle tomographic model under the North China Craton shows a significantly Y-shaped low-V anomaly under the Datong volcano and Bohai Sea extending down to the lower mantle, which, for the first time, is inferred using precise teleseismic arrival times hand-picked from high-quality seismograms recorded at densely spaced stations from the Chinese provincial networks. The results indicate the possibility of a mantle plume beneath the region. These models suggest that the Changbaishan and Tengchong volcanoes share the history of deep mantle origin, whereas the Datong and Hainan volcanoes are comparable. All these results provide a better understanding of the dynamics of East Asia, and also call for future volcanic hazard mitigation.

Lei, Jianshe; Xie, Furen; Fan, Qicheng; Santosh, M.

2013-11-01

135

Magmatic processes at Popocatepetl volcano, Mexico: petrology, geochemistry and Sr-Nd-Pb isotopes  

Microsoft Academic Search

Popocatepetl volcano is one of the most famous and most active stratovolcanoes of the Trans-Mexican Volcanic Belt (TMVB). It is located 60 km south-east of Mexico-City and 40 km west of the city of Puebla, both cities have more than 30 million inhabitants. In this contribution we present a study of Late Pleistocene to Recent products of Popocatépetl (Popo) volcano

P. Schaaf; J. Stimac; C. Siebe

2003-01-01

136

The enormous Chillos Valley Lahar: an ash-flow-generated debris flow from Cotopaxi Volcano, Ecuador  

Microsoft Academic Search

The Chillos Valley Lahar (CVL), the largest Holocene debris flow in area and volume as yet recognized in the northern Andes,\\u000a formed on Cotopaxi volcano's north and northeast slopes and descended river systems that took it 326?km north–northwest to\\u000a the Pacific Ocean and 130+?km east into the Amazon basin. In the Chillos Valley, 40?km downstream from the volcano, depths\\u000a of

Patricia A. Mothes; Minard L. Hall; Richard J. Janda

1998-01-01

137

Tech trek: Viewing volcanoes  

NSDL National Science Digital Library

Help students make real-world connections to Earth science concepts such as volcanoes with the help of modern technology. This article enumerates several websites where students can explore these forces of nature in a variety of ways - all from a safe distance!

Christmann, Edwin P.; Wighting, Mervyn J.; Lucking, Robert A.

2005-03-01

138

Chilean Volcano Eruption  

NASA Video Gallery

This animation includes visible and infrared imagery from GOES-13 that runs from June 4, 2011, at 1:45 p.m. EDT to June 6, 2011, at 10:45 a.m. EDT and shows the ash plume from the Puyehue-Cordón Caulle volcano in Chile (lower left) follow the wind shift from southeast to north. (no audio)

Robert Garner

2011-06-09

139

The Alaska Volcano Observatory - Expanded Monitoring of Volcanoes Yields Results  

USGS Publications Warehouse

Recent explosive eruptions at some of Alaska's 52 historically active volcanoes have significantly affected air traffic over the North Pacific, as well as Alaska's oil, power, and fishing industries and local communities. Since its founding in the late 1980s, the Alaska Volcano Observatory (AVO) has installed new monitoring networks and used satellite data to track activity at Alaska's volcanoes, providing timely warnings and monitoring of frequent eruptions to the aviation industry and the general public. To minimize impacts from future eruptions, scientists at AVO continue to assess volcano hazards and to expand monitoring networks.

Brantley, Steven R.; McGimsey, Robert G.; Neal, Christina A.

2004-01-01

140

Tectonic Plates, Earthquakes, and Volcanoes  

NSDL National Science Digital Library

According to theory of plate tectonics, Earth is an active planet -- its surface is composed of many individual plates that move and interact, constantly changing and reshaping Earth's outer layer. Volcanoes and earthquakes both result from the movement of tectonic plates. This interactive feature shows the relationship between earthquakes and volcanoes and the boundaries of tectonic plates. By clicking on a map, viewers can superimpose the locations of plate boundaries, volcanoes and earthquakes.

2011-05-12

141

Volcanoes, Third Edition  

NASA Astrophysics Data System (ADS)

It takes confidence to title a smallish book merely “Volcanoes” because of the impliction that the myriad facets of volcanism—chemistry, physics, geology, meteorology, hazard mitigation, and more—have been identified and addressed to some nontrivial level of detail. Robert and Barbara Decker have visited these different facets seamlessly in Volcanoes, Third Edition. The seamlessness comes from a broad overarching, interdisciplinary, professional understanding of volcanism combined with an exceptionally smooth translation of scientific jargon into plain language.The result is a book which will be informative to a very broad audience, from reasonably educated nongeologists (my mother loves it) to geology undergraduates through professional volcanologists. I bet that even the most senior professional volcanologists will learn at least a few things from this book and will find at least a few provocative discussions of subjects they know.

Nye, Christopher J.

142

Gelatin Volcanoes: Student Page  

NSDL National Science Digital Library

This is the Student Page of an activity that teaches students how and why magma moves inside volcanoes by injecting colored water into a clear gelatin cast. The Student Page contains the activity preparation instructions and materials list, key words, and a photograph of the experimental setup. There is also an extension activity question that has students predict what will happen when the experiment is run using an elongated model. This activity is part of Exploring Planets in the Classroom's Volcanology section.

143

Geologists on Volcano  

USGS Multimedia Gallery

Two HVO geologists are standing on the east rim of Pu`u `? `? cone, triangulating the depth of several degassing vents inside the crater. An infrared camera is being used to see the vents through the fume. The plume in the background is coming from the east wall vent....

2010-06-18

144

Multiple explosive rhyolite/trachyte eruptions of alkaline-peralkaline Nemrut and dacite/rhyolite eruptions of neighboring subduction zone-related Süphan volcano over 600 000 years: the East Anatolian tephra province  

NASA Astrophysics Data System (ADS)

The active Nemrut stratovolcano (2918 m asl) (Eastern Anatolia) is topped by a spectacular caldera and dominates the area west of huge Lake Van that covers its lower flanks. The stratovolcano has been active explosively for at least ca. 600 ka based on drilling evidence (ICDP Paleovan project). We have identified, correlated and compositionally characterized some 40 fallout sheets on land - none previously known - the largest ones probably with magma volumes exceeding 30 km3(DRE). The alkaline to peralkaline tephras are dominated by anorthoclase, Fe-rich clinopyroxene and fayalite with quartz and aenigmatite in some. Large-volume comenditic to pantelleritic rhyolite eruptions occurred in intervals of 20 000 - 40 000 years with smaller volume trachytic tephra deposits in between reflecting overall fairly constant magma transfer rates periodically fractionating to highly evolved rhyolite in larger magma reservoirs. Many of the ca. 10 widespread ignimbrite sheets, nearly all newly recognized, commonly followed on the heels of rhyolitic fallout sheets. They are more mafic than the underlying fallout deposits, magma mixing being common. Widespread spectacular agglutinates represent a late phase of the youngest large-volume fallout/ignimbrite eruption at ca. 30 ka. Active Süphan stratovolcano (4158 m asl), some 50 km NE of Nemrut and bordering Lake Van to the north, is dominated in contrast by subduction-related chemistry and mineralogy, smaller-volume eruptions and more advanced crystallization of magmas prior to eruption. Chief phenocrysts comprise complex disequilibrium assemblages of clinopyroxene, hypersthene, olivine, strongly zoned plagioclase, biotite and/or amphibole and common clots of fractionating phases. Many of the highly viscous and crystal-laden Süphan magmas were emplaced as domes and debris avalanches next to fallout sheets and ignimbrites. The dominant NE direction of fan axes of partial isopach maps of ca. 15 major fallout deposits reflecting prevailing wind directions for more than half a million years suggest that well-dated tephra markers of alkaline/peralkaline Nemrut, and sofar less well-dated "calcalkaline" Süphan and Ararat volcanoes represent a major tephrostratigraphic framework that should provide for excellent tephra markers in neighboring countries (e.g. Iran, Armenia, Aserbeidschan) and the Caspian Sea.

Schmincke, H.-U.; Sumita, M.; Paleovan scientific Team

2012-04-01

145

Fine-Scale Volcano-Tectonic Patterns Along the Hotspot and Non-Hotspot Influenced Fastest Spreading Parts of the East Pacific Rise, and Their Relation to Hydrothermal Activity  

NASA Astrophysics Data System (ADS)

A broad Easter mantle plume appears to be having a major long-term effect on the evolution of the giant duelling propagator system between the Easter and Juan Fernandez microplates. It is driving long-term propagation of the West ridge of this system toward the south, although there are occasional episodes of duelling propagation of the East ridge towards the north. The West ridge segment nearest the hotspot is the most highly inflated segment and contains several intense hydrothermal vent areas, although the East ridge segment farthest from the hotspot has a higher percentage of axis with active hydrothermal activity. DSL-120 sidescan sonar and bathymetry data collected along the EPR segment axes between the Easter and Juan Fernandez microplates have been compiled into a Quicktime movie. This presentation method provides a fast overview of an immense amount of data, and facilitates comparisons between the hotspot influenced and non-hotspot influenced segments, as well as correlations between the structural data and hydrothermal patterns, with implications for hydrothermal prospecting along mid-ocean ridges. For example, in addition to strong correlations with axial inflation and spreading rate, hydrothermal activity frequently correlates with areas of recent voluminous low-backscatter flows pouring out of axial fissures. Hydrothermal activity shows good correlation with presence of axial summit collapse structures, but not with the presence of an axial summit graben (sensu strictu). Although on a million year timescale the hotspot influence on the West ridge has a dominant effect on the tectonic evolution of this area, on the shorter timescales governing hydrothermal activity the hotspot influence is much less important than individual magmatic inflation events along individual ridge segments.

Hey, R.; Baker, E.; Lupton, J.; Kleinrock, M.; Martinez, F.; Naar, D.; Bohnenstiehl, D.; Pardee, D.; Massoth, G.; Rodrigo, C.; Gegg, S.; Reed, T.; Andersson, A.

2001-12-01

146

Anatomy of a basaltic volcano  

Microsoft Academic Search

Kilauea volcano, in Hawaii, may be the best understood basaltic volcano in the world. Magma rises from a depth of 80 km or more and resides temporarily in near-surface reservoirs: eruption begins when the crust above one of these reservoirs splits open in response to a pressure increase. Repeated rift-zone eruptions compress Kilauea's flanks; after decades of accumulation, the stress

Robert I. Tilling; John J. Dvorak

1993-01-01

147

Earthquakes, Volcanoes, and Plate Tectonics  

NSDL National Science Digital Library

This page consists of two maps of the world, showing how earthquakes define the boundaries of tectonic plates. Volcanoes are also distributed at plate boundaries (the "Ring of Fire" in the Pacific) and at oceanic ridges. It is part of the U.S. Geological Survey's Cascades Volcano Observatory website, which features written material, images, maps, and links to related topics.

148

Volcano Homework Assignment  

NSDL National Science Digital Library

In this and similar assignments students have to download quantitative natural hazard data from the Internet, load it into a spreadsheet, rank order the data, calculate recurrence times and plot the result on a log-log graph. They then interpret this graph in terms of the recurrence time of hazard events of different sizes. In many cases this includes comparing results from two different features (volcanoes, faults, rivers, etc.) Uses online and/or real-time data Addresses student fear of quantitative aspect and/or inadequate quantitative skills Uses geophysics to solve problems in other fields Addresses student misconceptions

Jaume, Steven

149

Ruiz Volcano: Preliminary report  

NASA Astrophysics Data System (ADS)

Ruiz Volcano, Colombia (4.88°N, 75.32°W). All times are local (= GMT -5 hours).An explosive eruption on November 13, 1985, melted ice and snow in the summit area, generating lahars that flowed tens of kilometers down flank river valleys, killing more than 20,000 people. This is history's fourth largest single-eruption death toll, behind only Tambora in 1815 (92,000), Krakatau in 1883 (36,000), and Mount Pelée in May 1902 (28,000). The following briefly summarizes the very preliminary and inevitably conflicting information that had been received by press time.

150

Gelatin Volcanoes: Teacher Page  

NSDL National Science Digital Library

This is the Teacher Page of an activity that teaches students how and why magma moves inside volcanoes by injecting colored water into a clear gelatin cast. Activity preparation instructions are on the Student Page, while the Teacher Page has background, preparation, and in-class information. An extension activity has the students repeat the experiment using a square bread pan to simulate the original research that was done using elongate models with triangular cross-sections. This activity is part of Exploring Planets in the Classroom's Volcanology section.

151

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

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

152

High-resolution seismic tomography of compressional wave velocity structure at Newberry Volcano, Oregon Cascade Range  

SciTech Connect

Compressional wave velocity structure is determined for the upper crust beneath Newberry Volcano, central Oregon, using a high-resolution active-source seismic-tomography method. Newberry Volcano is a bimodal shield volcano east of the axis of the Cascade Range. It is associated both with the Cascade Range and with northwest migrating silicic volcanism in southeast Oregon. High-frequency (approx.7 Hz) crustal phases, nominally Pg and a midcrustal reflected phase, travel upward through a target volume beneath Newberry Volcano to a dense array of 120 seismographs. This arrangement is limited by station spacing to 1- to 2-km resolution in the upper 5 to 6 km of the crust beneath the volcano's summit caldera. The experiment tests the hypothesis that Cascade Range volcanoes are underlain only by small magma chambers. A small low-velocity anomaly delineated abosut 3 km below the summit caldera supports this hypothesis for Newberry Volcano and is interpreted as a possible magma chamber of a few to a few tens of km/sup 3/ in volume. A ring-shaped high-velocity anomaly nearer the surface coincides with the inner mapped ring fractures of the caldera. It also coincides with a circular gravity high, and we interpret it as largely subsolidus silicic cone sheets. The presence of this anomaly and of silicic vents along the ring fractures suggests that the fractures are a likely eruption path between the small magma chamber and the surface.

Achauer, U.; Evans, J.R.; Stauber, D.A.

1988-09-10

153

Volcan Baru: Eruptive History and Volcano-Hazards Assessment  

USGS Publications Warehouse

Volcan Baru is a potentially active volcano in western Panama, about 35 km east of the Costa Rican border. The volcano has had four eruptive episodes during the past 1,600 years, including its most recent eruption about 400?500 years ago. Several other eruptions occurred in the prior 10,000 years. Several seismic swarms in the 20th century and a recent swarm in 2006 serve as reminders of a restless tectonic terrane. Given this history, Volcan Baru likely will erupt again in the near or distant future, following some premonitory period of seismic activity and subtle ground deformation that may last for days or months. Future eruptions will likely be similar to past eruptions?explosive and dangerous to those living on the volcano?s flanks. Outlying towns and cities could endure several years of disruption in the wake of renewed volcanic activity. Described in this open-file report are reconnaissance mapping and stratigraphic studies, radiocarbon dating, lahar-inundation modeling, and hazard-analysis maps. Existing data have been compiled and included to make this report as comprehensive as possible. The report is prepared in coooperation with National Secretariat for Science, Technology and Innovation (SENACYT) of the Republic of Panama and the U.S. Agency for International Development (USAID).

Sherrod, David R.; Vallance, James W.; Tapia Espinosa, Arkin; McGeehin, John P.

2008-01-01

154

Types and Effects of Volcano Hazards  

NSDL National Science Digital Library

This United States Geological Survey (USGS) website discusses volcano hazards by type (gas, lahars, landslides, lava flows, pyroclastic flows, and tephra) and by the effect volcanoes have on people and land. This site gives an overview of volcano hazards and links to selected case studies listed by country, volcano, year, and type of hazard. Links to more USGS information about volcanoes, such as a photo glossary, a site index, observatories, and an educator's page are also provided.

155

The chemistry of sublimates collected directly from lava fountains at Kilauea Volcano, Hawaii  

Microsoft Academic Search

During 1970, it was occasionally feasible to collect sublimate from directly above the lava fountain in the crater of Mauna Ulu on the east rift zone of Kilauea Volcano, when the level of the lava pool had dropped within the crater. Collecting equipment was suspended down the steep wall to a position above the fountain. Collections were made on quartz

John J. Naughton; Virginia A. Lewis; Dale Hammond; Daniel Nishimoto

1974-01-01

156

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

Microsoft Academic Search

The first historical eruption on Anatahan Island occurred on 10 May 2003 from the east crater of the volcano. The eruption was preceded by several hours of seismicity. Two and a half hours before the outbreak, the number of earthquakes surged to more than 100 events per hour. At 0730 UTC, the Washington Volcanic Ash Advisory Center issued an ash

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

2005-01-01

157

Geochemical Constraints on Possible Subduction Components in Lavas of Mayon and Taal Volcanoes, Southern Luzon, Philippines  

Microsoft Academic Search

Mayon is the most active volcano along the east margin of southern Luzon, Philippines. Petrographic and major element data indicate that Mayon has produced a basaltic to andesitic lava series by fractional crystallization and magma mixing. Trace element data indicate that the parental basalts came from a heterogeneous mantle source. The unmodified composition of the mantle wedge is similar to

P. R. CASTILLO; C. G. NEWHALL

2004-01-01

158

Rheology of the 1983 Royal Gardens basalt flows, Kilauea Volcano, Hawaii  

Microsoft Academic Search

Ten carefully surveyed topographic profiles across a 1983 Royal Gardens basalt flow from the East Rift of the Kilauea Volcano were matched to digitally derived preflow profiles to construct accurate flow cross sections. Geometric parameters measured on these sections were then used to compute yield strengths and viscosities by means of several rheologic models. Calculated yield strengths (1.5–50 × 103

Jonathan H. Fink; James R. Zimbelman

1986-01-01

159

A reinterpretation of seismicity associated with the January 1983 dike intrusion at Kilauea Volcano, Hawaii  

Microsoft Academic Search

In January 1983, a dike intrusion\\/fissure eruption generated a swarm of 375 magnitude 1 to 3 earthquakes along a 16-km segment of Kilauea's Middle East Rift Zone. We searched the Hawaiian Volcano Observatory catalog for multiples of similar events from this region from 1980 through 1985 and obtained precise relative locations by waveform cross correlation. Over 150 of the intrusion

Allan M. Rubin; Dominique Gillard; Jean-Luc Got

1998-01-01

160

Groundwater at Mayon, Volcano  

NASA Astrophysics Data System (ADS)

Around Mayon Volcano, Philippines, anecdotal evidence and rainfall normalized spring discharge data suggest that the water table 8 km from the summit of the volcano drops prior to eruptions. Residents report that they had to deepen their shallow wells in 1993 (some before and others following the eruption). In some cases they had to dig as far as 5 meters deeper to reach the water table. Significant decreases in spring discharge were recorded prior to the 1999 phreatic explosions and explosive eruption in 2000. A lesser decrease in spring discharge was recorded prior to the 2001 explosive eruptions. The cause of the observed correlation is not yet understood. Mechanisms consider include decrease in rainfall and boiling away of groundwater due to magmatic intrusion. Dilatation of the volcano may cause an increase in pore pressure, opening of cracks, and inflation of the ground surface that would all result in lower water table levels and decreases in spring discharges. Lack of significant hydraulic precursors prior to the 2001 eruptions may be due to a sustained state of inflation following the eruption of 2000. To better understand the relationship between changes in the volcanic system and changes in the groundwater system surrounding Mayon, instruments were installed about eight kilometers from the summit immediately following the explosive eruption of 26 July 2001. Parameters monitored include rainfall data, water levels in four shallow wells, discharge in the main river basin, and spring discharge. The aquifers at eight kilometers are predominantly poorly sorted lahar flow deposits. Characterization of these highly permeable aquifers has been conducted. Preliminary data include porosity ranges, hydraulic conductivity estimates, and response to rainfall. Water samples have been collected that are intended for geo-chemical analysis to determine if the water is predominantly meteoric or magmatic in origin. Numerical modeling of the system using the above mentioned parameters is planned. We expect to determine what the magnitude of strain produced by the intruding magma would have to be for the lowering of the water table that was observed in 1993, 1999, and 2000. This strain will then be compared with the expected strain from volcanic intrusion to determine if strain alone could be responsible for the changes to the groundwater system.

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

2001-12-01

161

VolcanoWorld Online Lessons  

NSDL National Science Digital Library

These five activities are sequential and are designed to cover introductory volcano topics. Included are objectives, materials lists, procedures, and a selection of related sites for students to access.

162

USGS Cascades Volcano Observatory: Maps and Graphics  

NSDL National Science Digital Library

The United States Geological Survey's website for the Cascades Volcano Observatory (CVO) has a host of graphics and maps for the professional volcano researcher or the amateur volcanologist. The maps and graphics are divided into four broad categories, and within each of those categories are dozens and dozens of maps and graphics. The categories include "Hazards, Features, Topics, and Types: Maps and Graphics", "Monitoring: Maps and Graphics", and "Volcano or Region: Maps and Graphics". Visitors should check out "Bachelor", which is in the "Volcano or Region" category, as there is an "Interactive Imagemap" of the Cascade Range Volcanoes. Clicking on any of the images of the volcanoes will reveal a beautiful, aerial photo of the volcano, along with a brief description of the history of the volcano. Additionally, there is a "Planning Your Visit" section that gives online and offline resources to look at before going to the actual volcano.

163

U. S. Geological Survey Volcano Hazards Program  

NSDL National Science Digital Library

A comprehensive overview of the U.S. Geological Survey's Volcano Hazards Program and current volcanic activity in the United States. The Volcano Hazards Program monitors volcanoes and collects the best possible scientific information on volcanoes in the United States and elsewhere to reduce the risk from volcanic activity. Site includes links to the Program's four volcano observatories in Alaska, the Cascades (Washington State) , Hawaii, and Long Valley (California). Other links include information on volcano hazards: types, effects, locations and historical eruptions, information on reducing volcanic risks, volcano monitoring, emergency planning, and warning schemes. Other resources available are a photoglossary, volcano fact sheets and videos, an educator's page, and updates and weekly reports on worldwide, U.S., and Russian volcano activity.

164

Mud volcanoes in deepwater Nigeria  

Microsoft Academic Search

Detailed study of 3D seismic data from deepwater Nigeria has revealed the presence of features interpreted to be mud volcanoes. They occur in an upper slope environment seen as 1–2km circular features at the seabed. Seabed cores from the mud volcanoes contain oil, gas and sand\\/shale–clast content richer than the seabed background. Pliocene fossils have been identified in the cores,

K Graue

2000-01-01

165

Evaluation of volcanic risk management in Merapi and Bromo Volcanoes  

NASA Astrophysics Data System (ADS)

Merapi (Central Java Province) and Bromo (East Java Province) volcanoes have human-environmental systems with unique characteristics, thus causing specific consequences on their risk management. Various efforts have been carried out by many parties (institutional government, scientists, and non-governmental organizations) to reduce the risk in these areas. However, it is likely that most of the actions have been done for temporary and partial purposes, leading to overlapping work and finally to a non-integrated scheme of volcanic risk management. This study, therefore, aims to identify and evaluate actions of risk and disaster reduction in Merapi and Bromo Volcanoes. To achieve this aims, a thorough literature review was carried out to identify earlier studies in both areas. Afterward, the basic concept of risk management cycle, consisting of risk assessment, risk reduction, event management and regeneration, is used to map those earlier studies and already implemented risk management actions in Merapi and Bromo. The results show that risk studies in Merapi have been developed predominantly on physical aspects of volcanic eruptions, i.e. models of lahar flows, hazard maps as well as other geophysical modeling. Furthermore, after the 2006 eruption of Merapi, research such on risk communication, social vulnerability, cultural vulnerability have appeared on the social side of risk management research. Apart from that, disaster risk management activities in the Bromo area were emphasizing on physical process and historical religious aspects. This overview of both study areas provides information on how risk studies have been used for managing the volcano disaster. This result confirms that most of earlier studies emphasize on the risk assessment and only few of them consider the risk reduction phase. Further investigation in this field work in the near future will accomplish the findings and contribute to formulate integrated volcanic risk management cycles for both Merapi and Bromo. Keywords: Risk management, volcanoes hazard, Merapi and Bromo Volcano Indonesia

Bachri, S.; Stöetter, J.; Sartohadi, J.; Setiawan, M. A.

2012-04-01

166

Mahukona: The missing Hawaiian volcano  

SciTech Connect

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

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

1990-11-01

167

Deep structure and origin of active volcanoes in China  

NASA Astrophysics Data System (ADS)

Recent geophysical studies have provided important constraints on the deep structure and origin of the active intraplate volcanoes in Mainland China. Magmatism in the western Pacific arc and back-arc areas is caused by the corner flow in the mantle wedge and dehydration of the subducting slab (e.g., Zhao et al., 2009a), while the intraplate magmatism in China has different origins. The active volcanoes in Northeast China (such as the Changbai and Wudalianchi) are caused by hot upwelling in the big mantle wedge (BMW) above the stagnant slab in the mantle transition zone and deep slab dehydration as well (Zhao et al., 2009b). The Tengchong volcano in Southwest China is caused by a similar process in the BMW above the subducting Burma microplate (or Indian plate) (Lei et al., 2009a). The Hainan volcano in southernmost China is a hotspot fed by a lower-mantle plume which may be associated with the Pacific and Philippine Sea slabs' deep subduction in the east and Indian slab's deep subduction in the west down to the lower mantle (Lei et al., 2009b; Zhao, 2009). The stagnant slab finally collapses down to the bottom of the mantle, which can trigger the upwelling of hot mantle materials from the lower mantle to the shallow mantle beneath the subducting slabs and may cause the slab-plume interactions (Zhao, 2009). References Lei, J., D. Zhao, Y. Su, 2009a. Insight into the origin of the Tengchong intraplate volcano and seismotectonics in southwest China from local and teleseismic data. J. Geophys. Res. 114, B05302. Lei, J., D. Zhao, B. Steinberger et al., 2009b. New seismic constraints on the upper mantle structure of the Hainan plume. Phys. Earth Planet. Inter. 173, 33-50. Zhao, D., 2009. Multiscale seismic tomography and mantle dynamics. Gondwana Res. 15, 297-323. Zhao, D., Z. Wang, N. Umino, A. Hasegawa, 2009a. Mapping the mantle wedge and interplate thrust zone of the northeast Japan arc. Tectonophysics 467, 89-106. Zhao, D., Y. Tian, J. Lei, L. Liu, 2009b. Seismic image and origin of the Changbai intraplate volcano in East Asia: Role of big mantle wedge above the stagnant Pacific slab. Phys. Earth Planet. Inter. 173, 197-206.

Zhao, D.

2010-12-01

168

EARTHQUAKES - VOLCANOES(Causes - Forecast - Counteraction)  

NASA Astrophysics Data System (ADS)

Earthquakes and volcanoes are caused by: ?) Various liquid elements (e.g. H20, H2S, S02) which emerge from the pyrosphere and are trapped in the space between the solid crust and the pyrosphere (Moho discontinuity). ?) Protrusions of the solid crust at the Moho discontinuity (mountain range roots, sinking of the lithosphere's plates). C) The differential movement of crust and pyrosphere. The crust misses one full rotation for approximately every 100 pyrosphere rotations, mostly because of the lunar pull. The above mentioned elements can be found in small quantities all over the Moho discontinuity, and they are constantly causing minor earthquakes and small volcanic eruptions. When large quantities of these elements (H20, H2S, SO2, etc) concentrate, they are carried away by the pyrosphere, moving from west to east under the crust. When this movement takes place under flat surfaces of the solid crust, it does not cause earthquakes. But when these elements come along a protrusion (a mountain root) they concentrate on its western side, displacing the pyrosphere until they fill the space created. Due to the differential movement of pyrosphere and solid crust, a vacuum is created on the eastern side of these protrusions and when the aforementioned liquids overfill this space, they explode, escaping to the east. At the point of their escape, these liquids are vaporized and compressed, their flow accelerates, their temperature rises due to fluid friction and they are ionized. On the Earth's surface, a powerful rumbling sound and electrical discharges in the atmosphere, caused by the movement of the gasses, are noticeable. When these elements escape, the space on the west side of the protrusion is violently taken up by the pyrosphere, which collides with the protrusion, causing a major earthquake, attenuation of the protrusions, cracks on the solid crust and damages to structures on the Earth's surface. It is easy to foresee when an earthquake will occur and how big it is going to be, when we know the record of specific earthquakes and the routes they have followed towards the East. For example, to foresee an earthquake in the Mediterranean region, we take starting point earthquakes to Latin America (0°-40°).The aforementioned elements will reach Italy in an average time period of 49 days and Greece in 53 days. The most reliable preceding phenomenon to determine the epicenter of an earthquake is the rise of the crust's temperature at the area where a large quantity of elements is concentrated, among other phenomena that can be detected either by instruments or by our senses. When there is an active volcano along the route between the area where the "starting-point" earthquake occurred and the area where we expect the same elements to cause a new earthquake, it is possible these elements will escape through the volcano's crater, carrying lava with them. We could contribute to that end, nullifying earthquakes that might be triggered by these elements further to the east, by using manmade resources, like adequate quantities of explosives at the right moment.

Tsiapas, E.; Soumelidou, D.; Tsiapas, C.

2012-04-01

169

East African Rift Valley Links for Learning  

NSDL National Science Digital Library

This web page contains links to a collection of resources devoted to the East African Valley Rift, with emphasis on environmental issues and concerns. It lists web addresses by subtopics, in outline form, with a short description to assist the viewer in searching for information. Topics include The Rift Valley, Stromboli online, African volcanoes, the Alid page, paleontology, and many more. The creator of this collection has checked uRLs provided for content and guarantees them to be quality web pages.

Moyra/mysticpc; Geolor.com

170

Neotectonics of East Anatolian Plateau (Turkey) and Lesser Caucasus: implication for transition from thrusting to strike-slip faulting  

Microsoft Academic Search

The east Anatolian plateau and the Lesser Caucasus are characterised and shaped by three major structures: (1) NW- and NE-trending dextral to sinistral active strike-slip faults, (2) N-S to NNW-trending fissures and \\/or Plio-Quaternary volcanoes, and (3) a 5-km thick, undeformed Plio-Quaternary continental volcano-sedimentary sequence accumulated in various strike-slip basins. In contrast to the situation in the east Anatolian plateau

Ali Koçyi?it; Ali Y?lmaz; Shota Adamia; Simon Kuloshvili

2001-01-01

171

Are Monogenetic Basaltic Explosive Volcanoes Good Analogues for Explosive Kimberlite Volcanoes?  

Microsoft Academic Search

There is uncertainty as to the nature of kimberlite volcanoes because the edifices of ancient kimberlite volcanoes have been largely eroded. Monogenetic basaltic explosive volcanoes, such as scoria or cinder cones and maars, are often proposed as good analogues for kimberlite volcanoes. Basaltic scoria or cinder cones form from explosive eruptions driven by exsolving magmatic gases. The sparsity of country

R. A. Cas

2009-01-01

172

Modeling Secular Deformation of Kilauea Volcano, Hawaii  

NASA Astrophysics Data System (ADS)

Kilauea volcano, Hawaii, is a dynamic volcanic and tectonic system that hosts rift intrusions and eruptions, summit inflation/deflation and eruptions, flank earthquakes and slow slip events, as well as quasi-steady flank motion. We seek to identify and characterize the actively deforming structures on Kilauea and study their interactions using a combination of GPS, InSAR, and seismic data. In addition we examine whether the change from summit subsidence to inflation in 2003, led to changes elsewhere in the volcano. We begin by modeling velocities of 16 continuous GPS and 28 campaign GPS sites and mean velocities from three ENVISAT tracks (T93 ascending: 10 acquisitions from 20030120 to 20041115; T200 descending: 13 acquisitions from 20030127 to 20041122, T429 descending: 10 acquisitions from 20030212 to 20041103) between 2003 and 2004, a period lacking major episodic events. We use triangular dislocations to mesh the curving rift zones and décollement. The southwest and east rift zones are continuous through the summit caldera area, where we also include a point center of dilatation beneath the southwest caldera. A décollement beginning about 12 km offshore at seven km depth dips approximately eight degrees northwest to achieving a depth of nine kilometers beneath the summit/rift zone. The décollement mesh continues at a shallower dip beneath the north flank of Kilauea reaching a final depth of 9.5 km beneath the north flank of Kilauea/south flank of Mauna Loa. Kinematic constraints enforce that opening at the base of the rift equal the differential décollement slip across the rift. Future modeling will include tests of Koae and Hilina fault geometries as well as time-dependent modeling of the deformation field.

Sinnett, D. K.; Montgomery-Brown, E. D.; Casu, F.; Segall, P.; Fukushima, Y.; Miklius, A.; Poland, M. P.

2010-12-01

173

East Timor  

NSDL National Science Digital Library

This Week's In the News examines the escalation of violence and the proposal for autonomy in the Indonesian province of East Timor. Last weekend, anti-independence militiamen killed dozens of separatist activists in Dili, the East Timorese capital, intensifying the fierce bloodshed and political tumult in the province. The recent massacre is just one of several brutal episodes that have plagued East Timor in the past quarter-century. The people of the embattled island have suffered numerous human rights violations, have endured economic collapse, and have been decimated by guerrilla warfare, famine, and disease. Over 200,000 East Timorese -- or nearly one-fourth of the population -- have died in the troubles, which began in 1975 when Portugal abruptly abandoned East Timor after 400 years of colonial rule. Unstable and vulnerable, the newly independent East Timor was quickly invaded, occupied, and annexed in 1976 by Indonesia, a stronger nation that quashed all subsequent separatist movements. Last January, after years of political oppression, Indonesia's parliament finally succumbed to international pressure and announced that it would grant East Timor either full independence or autonomy within the Indonesian state. The United Nations, although it has never officially recognized Indonesia's sovereignty over East Timor, plans to supervise a vote, tentatively scheduled for July, wherein the East Timorese will determine whether they want full independence or provincial autonomy. Later this week, Foreign Ministers Ali Alatas of Indonesia and Jaime Gama of Portugal are meeting in New York with UN Secretary-General Kofi Annan to discuss the East Timorese autonomy option and plan for the pending UN-monitored poll. However, the recent resurgence of violence between anti- and pro-independence factions in and around Dili threatens the viability of the proposed poll and endangers the stability of East Timor's self-determination. The nine resources discussed offer background information, the latest news, political analysis, and social commentary.

Osmond, Andrew.

1999-01-01

174

Mud Volcanoes Formation And Occurrence  

NASA Astrophysics Data System (ADS)

Mud volcanoes are natural phenomena, which occur throughout the globe. They are found at a greater or lesser scale in Azerbaijan, Turkmenistan, Georgia, on the Kerch and Taman peninsulas, on Sakhalin Island, in West Kuban, Italy, Romania, Iran, Pakistan, India, Burma, China, Japan, Indonesia, Malaysia, New Zealand, Mexico, Colombia, Trinidad and Tobago, Venezuela and Ecuador. Mud volcanoes are most well-developed in Eastern Azerbaijan, where more than 30% of all the volcanoes in the world are concentrated. More than 300 mud volcanoes have already been recognized here onshore or offshore, 220 of which lie within an area of 16,000 km2. Many of these mud volcanoes are particularly large (up to 400 m high). The volcanoes of the South Caspian form permanent or temporary islands, and numerous submarine banks. Many hypotheses have been developed regarding the origin of mud volcanoes. Some of those hypotheses will be examined in the present paper. Model of spontaneous excitation-decompaction (proposed by Ivanov and Guliev, 1988, 2002). It is supposed that one of major factors of the movement of sedimentary masses and formation of hydrocarbon deposits are phase transitions in sedimentary basin. At phase transitions there are abnormal changes of physical and chemical parameters of rocks. Abnormal (high and negative) pressure takes place. This process is called as excitation of the underground environment with periodicity from several tens to several hundreds, or thousand years. The relationship between mud volcanism and the generation of hydrocarbons, particularly methane, is considered to be a critical factor in mud volcano formation. At high flow rates the gas and sediment develops into a pseudo-liquid state and as flow increases the mass reaches the "so-called hover velocity" where mass transport begins. The mass of fluid moves as a quasi-uniform viscous mass through the sediment pile in a piston like manner until expelled from the surface as a "catastrophic eruption". Model of buoyancy drive (by Brown, 1990). Brown's basic hypothesis is similar to Ivanov and Guliev and may be summarized briefly as follows: -in situations where rapid sedimentation is occurring mud may be driven to the surface by buoyancy forces due to bulk density contrasts between mud and overlying sediment cover. Such density contrasts may be simply the result of compaction -disequilibrium, but more importantly may be related to gas expansion when fluids are transported to shallower depths with lower pressure and temperature conditions. Synthetic model had been proposed by I.Lerche, E.Bagirov, I.Guliyev (1997). The model includes the following studies: The starting point of the mud volcanoes begins with the formation of a zone of decompaction as a consequence of a high rate of gas generation. The mud body starts to rise under buoyancy. The excess pressure inside the mud intrusion is less than in surrounding formation. As a result, fluid flow toward the body of mud volcanoes. The body of the mud volcanoes then grows, increasing the buoyancy forces, with further drive the mud. If the rate of gas generation more thôn gas flow, causing exsolving of gas to free-phase gas. If there are open faults and fractures which cross the body of mud volcanoes, then gas and mud can penetrate through the faults, and so from gryphons and salses on the surface. A mud volcanoes can be consider as a huge accumulation of gas, where as the oil is concentrated on the flanks of the mud body.

Guliyev, I. S.

2007-12-01

175

Iridium emissions from Kilauea Volcano  

NASA Astrophysics Data System (ADS)

During May 1983, gas and particulate samples were collected at the cooling vents of Kilauea volcano in Hawaii. Three vents on the southeast rift zone were sampled using base-treated filter packs to absorb acidic gases and Teflon filters for particles. The samples were analyzed for 40 elements by nondestructive neutron activation analysis. As with other volcanoes, the chalcophilic and volatile elements were enriched by up to seven orders of magnitude relative to the erupted basalt. Unlike the case of other volcanoes, iridium was observed to be highly enriched (105 fold) at the two higher temperature vents, and the degree of enrichment appears to be related to both high temperatures and high fluorine content of the gases. Estimates of the emission rates of Ir during eruptions of Kilauea based on the measurements reported here and those of the Hawaiian Volcano Observatory yield an emission rate of about 3 g Ir per 106 m3 of magma. This rate amounts to only about 0.3% of the Ir present in the magma that is being released by the volcano. This previously unidentified Ir source to the atmosphere and ocean may have a significant influence on the geochemical cycle of Ir on the earth. The uniqueness of Kilauea in its emissions of Ir is probably related to the deep source of magma, which contains significant levels of Ir (0.32 ppb) and high levels of the halogens F and Cl.

Olmez, I.; Finnegan, D. L.; Zoller, W. H.

1986-01-01

176

Exploratour - Volcanoes of the Solar System  

NSDL National Science Digital Library

Visit this Windows to the Universe site for a tour of volcanoes in the solar system. Each page includes a picture with a brief description of the volcano and a link to more information. The tour includes volcanoes from Earth, Mars, the moon, Venus, Io, and Mercury.

2009-07-13

177

Venus small volcano classification and description  

Microsoft Academic Search

The high resolution and global coverage of the Magellan radar image data set allows detailed study of the smallest volcanoes on the planet. A modified classification scheme for volcanoes less than 20 km in diameter is shown and described. It is based on observations of all members of the 556 significant clusters or fields of small volcanoes located and described

J. C. Aubele

1993-01-01

178

Volcanoes of the Earth. [Book with glossary  

Microsoft Academic Search

Current knowledge of volcanoes and their effect on the environment and the people of the earth is presented. The book is based on actual field studies around the world. Discussion is presented in three sections entitled: facts and fiction about volcanoes; types of volcanic eruptions; and theory, cycles, utilization, and environmental effects of volcanoes. A chapter in the third section

Bullard

1976-01-01

179

Geophysical Study of the Kamchatka Volcanoes  

Microsoft Academic Search

The following conclusions were reached from a study of volcanoes in the eastern volcanic belt of the Kamchatka region: (1) Magnetic anomalies are due to the topographic effect of volcanoes. (2) Rocks in the vicinity of the active volcanoes, being above the Curie temperature, are nonmagnetic. (3) The fractures through which magma enters the crust of the earth do not

G. S. Steinberg; L. A. Rivosh

1965-01-01

180

Volcanism at Hualca Hualca Volcano, Southern Peru  

Microsoft Academic Search

Nevado Hualca Hualca (6025m), in southern Peru, is the northernmost edifice in a north-south trending chain of 3 volcanoes that includes Ampato and the active Sabancaya stratovolcano. The oldest in the chain and considered extinct, virtually no research exists about the history of this large volcano. The summit of the volcano shows deep incision by glaciation, which from aerial photographs

B. Burkett

2005-01-01

181

High resolution seismic attenuation tomography at Medicine Lake Volcano, California  

SciTech Connect

Medicine Lake Volcano, a broad shield volcano about 50km east of Mount Shasta in northern California, produced rhylotic eruptions as recently as 400 years ago. Because of this recent activity it is of considerable interest to producers of geothermal energy. In a joint project sponsored by the Geothermal Research Program of the USGS and the Division of Geothermal and Hydropower Division of the US-DOE, the USGS and LLNL conducted an active seismic experiment designed to explore the area beneath and around the caldera. The experiment of eight explosions detonated in a 50 km radius circle around the volcano recorded on a 11 x 15 km grid of 140 seismographs. The travel time data from the experiment have been inverted for structure and are presented elsewhere in this volume. In this paper we present the results of an inversion for 1/Q structure using t* data in a modified Aki inversion scheme. Although the data are noisy, we find that in general attenuative zones correlate with low velocity zones. In particular, we observe a high 1/Q zone roughly in the center of the caldera at 4 km depth in between two large recent dacite flows. This zone could represent the still molten or partially molten source of the flows.

Zucca, J.J.; Kasameyer, P.W.

1987-07-10

182

Surfing for Earthquakes and Volcanoes  

NSDL National Science Digital Library

This resource is part of the Science Education Gateway (SEGway) project, funded by NASA, which is a national consortium of scientists, museums, and educators working together to bring the latest science to students, teachers, and the general public. In this lesson, students use the Internet to research data on earthquakes and volcanoes and plot locations to determine plate boundaries. Extensions include interpretation of interaction between plate boundaries, causes of earthquakes and volcanoes, and the comparison of the formation of Olympus Mons on Mars and the Hawaiian volcanic chain. There are worksheets, references, assessment ideas, and vocabulary available for educators.

Coe, Patty; Merrick, Michael

183

Sunset Crater Volcano National Monument  

NSDL National Science Digital Library

This website of the United States Geological Survey (USGS) and the National Park Service (NPS) is a source of geologic information about Sunset Crater Volcano National Monument. It offers a virtual field trip through the area to learn more about cinder cone volcanics and the history of this region. General volcanic information includes an image gallery of the monument, a brief history of the eruptions in the area, volcano facts, and area earthquake and seismic information. There are links to a large glossary and more geologic details about this area.

184

Mount St. Helens VolcanoCam  

NSDL National Science Digital Library

This webcam shows a static image of Mount St. Helens taken from the Johnston Ridge Observatory. The Observatory and VolcanoCam are located at an elevation of approximately 4,500 feet, about five miles from the volcano. The observer is looking approximately south-southeast across the North Fork Toutle River Valley. The VolcanoCam image automatically updates approximately every five minutes. Other features include current conditions reports, weather updates, an image achive, and eruption movies. In addition, there are frequently asked questions, and information about using the VolcanoCam image and funding for the VolcanoCam.

185

Broadband seismic observation at Kusatsu-Shirane volcano, Japan  

NASA Astrophysics Data System (ADS)

Kusatsu-Shirane volcano, central part of Japan, has repeated phreatic explosions with an interval of several decades. More than 25 years have passed since the last eruption in 1983. Currently persistent seismic and fumarolic activities are observed. Recently, a long tremor was observed in May 2011, for the first time in the last 3 years. The high-frequency tremor lasted for about 7 minutes and were observed by borehole seismometers. It was accompanied by a notable crustal deformation which lasted for about 4 minutes and observed by borehole tiltmeters. The source of the crustal deformation was estimated about 0.5 km to the southeast of Yugama, the main crater lake of the volcano. The location is at the margin of the observation network, which makes it difficult to locate the source precisely. The seismic network of the volcano has consisted of short-period seismometers. Thus very low frequency seismic events, which have often been observed at volcanoes with broadband seismometers, have not been investigated. In order to constrain such pressure sources, to understand better the relationships between high frequency tremor and low frequency deformation, and to investigate very low frequency events, we deployed 3-component seimometers at 3 points, surrounding the deformation source area. Two broadband seismometers, CMG-40T (f0=0.033 Hz) by Güralp Systems were installed to the north and east of the deformation source. And a short-period seismometer, L-4C (f0=1 Hz) by Mark Products, was installed to the south. The seismic data are continuously recorded. One and a half month passed at the time of abstract submission. Neither tremor nor very low frequency event have occurred to date.

Yamawaki, T.; Aoyama, H.; Terada, A.; Nogami, K.

2011-12-01

186

Deformation associated with the January 17, 2002, eruption of Nyiragongo volcano, Democratic Republic of the Congo, from radar interferometry  

Microsoft Academic Search

Nyiragongo volcano, in the western branch of the East African Rift in the Democratic Republic of Congo, erupted on January 17, 2002, after several years of repose. The activity lasted for approximately one day and sent lava flows into the city of Goma (18 km south of the summit), destroying approximately 13% (4.5 km2) of the city and causing several

M. Poland; Z. Lu

2004-01-01

187

A Model of Outflow Generation by Hydrothermal Underpressure Drainage in Volcano–Tectonic Environment, Shalbatana Vallis (Mars)  

Microsoft Academic Search

The survey of the Shalbatana Vallis course and the analysis of the distribution of the concentric peripheral and radial systems of faults east of Tharsis allow us to propose a model that demonstrates the effect of volcano–tectonic strains generating crossing fault systems where heat points allowed hydrothermal drainage of confined aquifers and generated headwater systems. This model is qualitatively consistent

Nathalie A. Cabrol; Edmond A. Grin; Gilles Dawidowicz

1997-01-01

188

A Model of Outflow Generation by Hydrothermal Underpressure Drainage in Volcano-Tectonic Environment, Shalbatana Vallis (Mars)  

Microsoft Academic Search

The survey of the Shalbatana Vallis course and the analysis of the distribution of the concentric peripheral and radial systems of faults east of Tharsis allow us to propose a model that demonstrates the effect of volcano-tectonic strains generating crossing fault systems where heat points allowed hydrothermal drainage of confined aquifers and generated headwater systems. This model is qualitatively consistent

Nathalie A. Cabrol; Edmond A. Grin; Gilles Dawidowicz

1997-01-01

189

Photo glossary of volcano terms  

NSDL National Science Digital Library

The glossary has about 60 terms that are primarily types of volcanoes or vents, eruption types, and eruptive products. Clicking on a term displays a captioned photograph illustrating the concept and a glossary definition. Below the photgraph are related glossary terms and sometimes other information or photograph links.

190

Mount Rainier, a decade volcano  

SciTech Connect

Mount Rainier, recently designated as a decade volcano, is a 14,410 foot landmark which towers over the heavily populated southern Puget Sound Lowland of Washington State. It last erupted in the mid-1800's and is an obvious threat to this area, yet Rainier has received little detailed study. Previous work has divided Rainier into two distinct pre-glacial eruptive episodes and one post-glacial eruptive episode. In a pilot project, the authors analyzed 253 well-located samples from the volcano for 27 major and trace elements. Their objective is to test the value of chemical compositions as a tool in mapping the stratigraphy and understanding the eruptive history of the volcano which they regard as prerequisite to determining the petrogenesis and potential hazard of the volcano. The preliminary data demonstrates that variation between flows is significantly greater than intra-flow variation -- a necessary condition for stratigraphic use. Numerous flows or groups of flows can be distinguished chemically. It is also apparent from the small variation in Zr abundances and considerable variation in such ratios as Ba/Nb that fractional crystallization plays a subordinate role to some form of mixing process in the origin of the Mount Rainier lavas.

Kuehn, S.C.; Hooper, P.R. (Washington State Univ., Pullman, WA (United States). Dept. of Geology); Eggers, A.E. (Univ. of Puget Sound, Tacoma, WA (United States). Dept. of Geology)

1993-04-01

191

Kanaga Volcano, Aleutian Islands, Alaska  

NSDL National Science Digital Library

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

192

What Happened to Our Volcano?  

ERIC Educational Resources Information Center

|In this article, the author presents an investigative approach to "understanding Earth changes." The author states that students were familiar with earthquakes and volcanoes in other regions of the world but never considered how the land beneath their feet had experienced changes over time. Here, their geology unit helped them understand and…

Mangiante, Elaine Silva

2006-01-01

193

VOLCANO INSTABILITY AND LATERAL COLLAPSE  

Microsoft Academic Search

Active volcanoes are dynamically evolving structures, the life-cycles of which are punctuated by episodes of flank instability and lateral failure. Such behaviour is now recognised as ubiquitous and lateral collapses are estimated to have occurred at least four times a century over the past 500 years. In the Andes, three quarters of the large volcanic edifices have experienced collapse, while

W. J. McGuire

2003-01-01

194

What Happened to Our Volcano?  

ERIC Educational Resources Information Center

In this article, the author presents an investigative approach to "understanding Earth changes." The author states that students were familiar with earthquakes and volcanoes in other regions of the world but never considered how the land beneath their feet had experienced changes over time. Here, their geology unit helped them understand and…

Mangiante, Elaine Silva

2006-01-01

195

The Volcanoes of Central France  

Microsoft Academic Search

AN unlucky error, perhaps mine, in the letter on the ``Volcanoes of Central France,'' p. 80, will quite prevent any reader finding the paper I mentioned of May 1865, which, instead of being in the Gentleman's Magazine, was in the Englishman's Magazine, a short-lived periodical, begun and ended, I think, with that year. As your two correspondents, Prof. Corfield and

E. L. Garbett

1872-01-01

196

Large landslides from oceanic volcanoes  

Microsoft Academic Search

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

Robin T. Holcomb; Roger C. Searle

1991-01-01

197

Morne aux Diables. a potentially active volcano in northern Dominica, Lesser Antilles  

NASA Astrophysics Data System (ADS)

The island of Dominica, which is located near the center of the Lesser Antilles island arc, comprises at least 8 potentially active volcanoes. One of these is Morne aux Diables, an isolated composite cone situated at the extreme northern end of the island. Age dating suggests that the main cone building activity occurred between 1.5 and 1.0 million years ago. Exposed on the volcano's flanks however are a number of unconsolidated valley-fill block and ash flow deposits suggesting more recent activity. One of these deposits, on the north-east flank of the volcano, has been recently dated at > 46,000 years B.P. Other evidence of potential activity from this center includes the presence of warm (27°C), acidic (pH 1.6), sulfate-rich springs on the summit of the volcano, hot springs on the coast, and the occurrence in 2002 and 2003 of shallow earthquake swarms partially located beneath the volcano. Morne aux Diables is dominantly composed of deposits of block and ash flows and associated domes from Pelean-style activity, however, semi-vesicular andesite block and ash flows and surges (Asama-style activity) and pumiceous lapilli falls (Plinian-style activity) are locally abundant. The Pelean domes are located both in the summit region and along the southern flanks of the volcano. Petrologically, the volcano is composed of a monotonous series of porphyritic andesites and dacites containing phenocrysts of plagioclase+augite-hypersthene with very sparse crystals of hornblende and quartz. Petrological models suggest the Morne aux Diables andesites and dacites can be produced by fractional crystallization of basaltic magma (such as those erupted from centers such as Morne Anglais and Morne Plat Pays in the south). Minor variations within this suite of andesites and dacites can be related to upper crustal fractionation of phenocryst phases.

Rheubottom, A. N.; Smith, A. L.; Roobol, M. J.

2005-12-01

198

Long-Period seismic events at Ubinas Volcano (Peru): their implications and potentiality as monitoring tool  

NASA Astrophysics Data System (ADS)

Ubinas volcano (Southern Peru) is an active andesitic stratovolcano, located 75 km East of Arequipa City, with an average occurrence of 6-7 eruptions per century and persistent fumarolic and phreatic activity. The most recent eruption, accompanied by explosions and by the extrusion of a lava dome, started on March 2006 with an increase of seismicity and observed fumarole occurrence followed in April by more intense explosions, recorded until May 2009. To monitor the volcanic activity, the Geophysical Institute of Peru and the Institut de Recherche pour le Développment (France), built up a seismic network around the volcano, installing 4 permanent stations and deploying 8 supplementary temporary broadband seismometers. In addition, in the period May to July 2009, a seismic experiment was carried out on the volcano flanks with 2 cross-shaped dense antennas with broadband seismometers. As the seismic activity was characterized by recurring low-frequency waveforms, we identify their pattern of occurrence through waveform cross-correlation technique, with respect to major eruptive phases and other observations (as volcano ground deformation from tiltmeters, volcanic product composition, etc). Once established their likely association with the eruptive sequence, we utilize both local network and dense-array data and analyze their location, changes in location, spectral content variations and possible physical explanation. The final aim is to introduce this kind of analysis as quantitative tool to understand ongoing eruptive phases at andesitic volcanoes and possibly to forecast magma/fluid significant movements.

Zandomeneghi, D.; Inza, A.; Metaxian, J.-P.; Macedo, O.

2012-04-01

199

Damavand volcano spreading detected by advanced InSAR time series  

NASA Astrophysics Data System (ADS)

Unlike the ordinary mountains, volcanoes are mostly formed rapidly. As a result many of them are subject to gradual spreading and sometimes massive flank failures. This spreading specially in case of being directional can be assessed as a precursor for the future flank collapse. Herein using an advanced InSAR time series approach and consuming a data set of ENVISAT radar images spanning period of 2003 till 2009 we obtain spatiotemporal deformation field over Damavand volcano, in north Iran. This volcano that is located in the north-east of the capital city Tehran with over 13 million inhabitants, exhibit continuously fumarolic activity and considered as potentially active volcano. The obtained deformation time series shows sort of gradual spreading in the direction of the regional stressing access which emphasizes that spreading and probable failure can happen even without any associated magmatic activity. In this work using InSAR time series, geological and metrological data we investigate the presence of spreading partitioning regarding the geological units and also we assess the influence of the rain fall on the occasional changes in the rate of spreading. Finally we underline the importance of continuous monitoring (such as the approach we employed here for InSAR time series generation) for timely forecasting future flank failure associated to Damavand volcano, which might be another significant hazard for Tehran city, regardless of magmatic activity.

Shirzaei, Manoochehr; Walter, Thomas

2010-05-01

200

A Summary of the History and Achievements of the Alaska Volcano Observatory.  

NASA Astrophysics Data System (ADS)

Volcanoes of the Aleutian Islands, Kamchatka and the Kurile Islands present a serious threat to aviation on routes from North America to the Far East. On March 27, 1986, an eruption of Augustine Volcano deposited ash over Anchorage and disrupted air traffic in south-central Alaska. The consequences of the colocation of an active volcano and the largest city in Alaska were clearly evident. That event led to a three-way partnership between the US Geological Survey, the University of Alaska Geophysical Institute and the Alaska State Division of Geological and Geophysical Surveys that now maintains a continuous watch through ground instrumentation and satellite imagery providing data from which warnings of eruptions can be issued to airline operators and pilots. The eruption of Redoubt Volcano in December 1989 was AVO's first big test. It spewed volcanic ash to a height of 14,000 m (45,000 feet) and managed to catch KLM 867, a Boeing 747 aircraft in its plume under dark conditions while approaching Anchorage Airport. Further details of the early days of the Alaska Volcano Observatory will be described, along with its recent successes and challenges.

Smith, R. W.

2008-12-01

201

Far East  

SciTech Connect

Petroleum activity throughout the Far East region was on the upswing during 1980. In spite of increased interest in many parts of the Far East, no major new discoveries were reported. From India to Indonesia, old fields are being rehabilitated and previously uneconomic areas are being looked at again. Indonesia set a new record in 1980 for the number of exploratory wells drilled. Peninsular Malaysia set a record for oil production. Overall, however, 1980 was a banner year for petroleum exploration in the Far East. Sri Lanka saw its first foreign contractor interest in several years. India made major moves toward increasing exploration by offering offshore and onshore blocks to foreign contractors . Bangladesh and even Burma signed exploitation contracts with Japanese investors in order to increase production. Malaysia offered new acreage blocks for the first time in several years. Indonesia and the Philippines also actively encouraged exploration by offering new contract areas. One country in the Far East that did not participate in the 1980 oil boom was China. Taiwan also carried on, as in previous years with the Chinese Petroleum Corporation as the only operator. Japanese and South Korean activities were at approximately the same level as in previous years, although drilling did start in the joint development zone. Total production of the Far East reporting region declined slightly. One significant aspect of 1980 petroleum activities throughout the Far East region is the growing acceptance by various Far East countries of Asian investment for developing and exploring for hydrocarbons. Japan is the major investor, but South Korean interests and the Chinese Petroleum Corporation also began to invest in petroleum rights in other Asian countries. The main area for investment continued to be Indonesia. 39 figures, 9 tables.

Fletcher, G.L.

1981-10-01

202

Researchers Discover Underwater Volcano-within-a-Volcano (PR 05-089)  

NSF Publications Database

... a submarine volcano growing within the summit crater of another larger underwater volcano called ... they profiled the seafloor of the Vailulu'u crater using multi-beam mapping. Existing maps of the ...

203

Volcano and Earthquake Monitoring Plan for the Yellowstone Volcano Observatory, 2006-2015.  

National Technical Information Service (NTIS)

To provide Yellowstone National Park (YNP) and its surrounding communities with a modern, comprehensive system for volcano and earthquake monitoring, the Yellowstone Volcano Observatory (YVO) has developed a monitoring plan for the period 20062015. Such a...

2006-01-01

204

Volcanology, history and myths of the Lake Albano maar (Colli Albani volcano, Italy)  

Microsoft Academic Search

The polygenetic Albano maar is the most recent centre of the Colli Albani volcano, located just few kilometres to the south-east of Roma. Presently the maar hosts a 167.5 m deep crater lake, the deepest in Europe. The maar is to be considered quiescent, as phreatic activity is documented throughout the Holocene. This paper illustrates the close relationships between the activity

A. A. De Benedetti; R. Funiciello; G. Giordano; G. Diano; E. Caprilli; M. Paterne

2008-01-01

205

Co-eruptive deformation of Nyiragongo and Nyamulagira volcanoes, Africa, from radar interferometry  

Microsoft Academic Search

Nyiragongo and Nyamulagira volcanoes are located in the western branch of the East African Rift in the Democratic Republic of Congo. On January 17, 2002, an eruption at Nyiragongo stratovolcano sent lava flows into the city of Goma (population ~500,000), 18 km south of the summit. About 13% (4.5 km2) of the city was destroyed and several dozen people were

M. P. Poland; Z. Lu

2003-01-01

206

January 30, 1997 eruptive event on Kilauea Volcano, Hawaii, as monitored by continuous GPS  

Microsoft Academic Search

A continuous Global Positioning System (GPS) network on Kilauea Volcano captured the most recent fissure eruption in Kilauea's East Rift Zone (ERZ) in unprecedented spatial and temporal detail. The short eruption drained the lava pond at Pu'u O'o, leading to a two month long pause in its on-going eruption. Models of the GPS data indicate that the intrusion's bottom edge

Susan Owen; Paul Segall; Michael Lisowski; Asta Miklius; Mark Murray; Michael Bevis; James Foster

2000-01-01

207

Seismic activity and ground deformation associated with 1995 phreatic eruption of Kuju Volcano, Kyushu, Japan  

Microsoft Academic Search

Kuju Volcano lies near Aso Caldera in central Kyushu. After a few hundred years of dormancy, a phreatic eruption began with the ejection of about 20,000 m3 ash on 11 October 1995. A number of new vents have opened on a series of lines striking east–west on the eastern slope of Mt. Hossho, one of the domes of the Kuju

Yasuaki Sudo; Hiroyasu Ono; Anthony W. Hurst; Tomoki Tsutsui; Takehiko Mori; Makoto Nakaboh; Yoshihiro Matsumoto; Mikio Sako; Shin Yoshikawa; Maki Tanaka; Yoshimasa Kobayashi; Takeshi Hashimoto; Teruaki Hoka; Toshihiro Yamada; Hideharu Masuda; Shigetomo Kikuchi

1998-01-01

208

Density Muon Radiography of Soufrière of Guadeloupe Volcano: Comparison with Geological, Electrical Resistivity and Seismic data.  

NASA Astrophysics Data System (ADS)

We present density radiographies obtained for the Soufrière of Guadeloupe lava dome, both in the North-South and East-West planes. These radiographies reveal the highly heterogeneous density structure of the volcano, with low-density regions corresponding to recognized hydrothermally altered areas. The main structures observed in the density radiographies correlate with anomalies in electrical resistivity cross-sections and seismic velocity model.

Gibert, D.; Lesparre, N.; Marteau, J.; Komorowski, J.-C.; Nicollin, F.; Coutant, O.; Carbone, D.; Kergosien, B.; Rolland, P.

2012-04-01

209

‘Column on column’ structures as indicators of lava\\/ice interaction, Ruapehu andesite volcano, New Zealand  

Microsoft Academic Search

Lava flows of the Mangawhero Formation (ca. 15–60 ka) on Ruapehu volcano erupted during the last glaciation. In a distal flow lobe at Tukino, on the east side of the mountain, small secondary columns (10–20 cm thick) have formed on the sides of large, rectangular, primary (0.5–3 m thick) cooling columns. Thick (10 m+) zones of such small columns form a lateral and basal

K. B. Spörli; J. V. Rowland

2006-01-01

210

Composite Volcanoes, Stratovolcanoes, and Subduction-Zone Volcanoes (title provided or enhanced by cataloger)  

NSDL National Science Digital Library

This resource defines and describes composite volcanoes, stratovolcanoes, subduction-zone volcanoes and composite cones. The information is from different sources and therefore the site gives a broad picture of these forms. The shape of the volcano is described as a function of the type and frequency of eruption and its proximity to plate boundaries.

211

USGS Photo glossary of volcano terms  

NSDL National Science Digital Library

This website, part of the USGS Volcano Hazards Program, can help users distinguish among various types of volcanoes, vents, eruption types, and ejected material. The site features an extensive list of volcanic vocabulary, along with photographs and text for each entry. Users can also check out the latest U.S. volcanic activity reported by the USGS volcano observatories, which are linked to the page.

Usgs

212

Volcanoes: Local Hazard, Global Issue  

NSDL National Science Digital Library

In this module, students can explore two ways that volcanoes affect Earth: by directly threatening people and the environments adjacent to them, and by ejecting aerosols into the atmosphere. The module consists of three investigations in which they will study the local effects of volcanism using images of Mount St. Helens, examine how the effects of volcanic activity can be remotely sensed and monitored from space using NASA data for Mount Spurr in Alaska, and see how geography and spatial perspective are useful in addressing global issues in the tracking and mapping of aerosol hazards such as the ash cloud emitted by the 1989 eruption on Redoubt Volcano. Each investigation is complete with overview, a list of materials and supplies, content preview, classroom procedures, worksheets, background, and evaluation.

213

Laboratory simulation of volcano seismicity.  

PubMed

The physical processes generating seismicity within volcanic edifices are highly complex and not fully understood. We report results from a laboratory experiment in which basalt from Mount Etna volcano (Italy) was deformed and fractured. The experiment was monitored with an array of transducers around the sample to permit full-waveform capture, location, and analysis of microseismic events. Rapid post-failure decompression of the water-filled pore volume and damage zone triggered many low-frequency events, analogous to volcanic long-period seismicity. The low frequencies were associated with pore fluid decompression and were located in the damage zone in the fractured sample; these events exhibited a weak component of shear (double-couple) slip, consistent with fluid-driven events occurring beneath active volcanoes. PMID:18845753

Benson, Philip M; Vinciguerra, Sergio; Meredith, Philip G; Young, R Paul

2008-10-10

214

Update of the volcanic risk map of Colima volcano, Mexico  

NASA Astrophysics Data System (ADS)

The Colima volcano, located in western Mexico (19° 30.696 N, 103° 37.026 W) began its current eruptive process in February 10, 1999. This event was the basis for the development of two volcanic hazard maps: one for ballistics (rock fall) lahars, and another one for ash fall. During the period of 2003 to 2008 this volcano has had an intense effusive-explosive activity, similar to the one that took place during the period of 1890 through 1900. Intense pre-Plinian eruption in January 20, 1913, generated little economic losses in the lower parts of the volcano thanks to the low population density and low socio-economic activities at the time The current volcanic activity has triggered ballistic projections, pyroclastic and ash flows, and lahars, all have exceeded the maps limits established in 1999. Vulnerable elements within these areas have gradually changed due to the expansion of the agricultural frontier on the east and southeast sides of the Colima volcano. On the slopes of the northwest side, new blue agave Tequilana weber and avocado orchard crops have emerged along with important production of greenhouse tomato, alfalfa and fruit (citrus) crops that will eventually be processed and dried for exportation to the United States and Europe. Also, in addition to the above, large expanses of corn and sugar cane have been planted on the slopes of the volcano since the nineteenth century. The increased agricultural activity has had a direct impact in the reduction of the available forest land area. Coinciding with this increased activity, the 0.8% growth population during the period of 2000 - 2005, - due to the construction of the Guadalajara-Colima highway-, also increased this impact. The growth in vulnerability changed the level of risk with respect to the one identified in the year 1999 (Suarez, 2000), thus motivating us to perform an update to the risk map at 1:25,000 using vector models of the INEGI, SPOT images of different dates, and fieldwork done in order to obtain new agricultural development and socioeconomic status data.

Suarez-Plascencia, C.; Nuñez Cornu, F. J.; Marquez-Azua, B.

2010-12-01

215

Cascade Range Volcanoes: North to South  

NSDL National Science Digital Library

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

216

Modeling an Active (!!) Explosive Volcano  

NSDL National Science Digital Library

This activity is an active simulation of an explosive volcanic eruption. The model volcano is a plastic 35 mm film cannister that erupts (the lid blows off) when gas pressure generated by dissolving alka seltzer is sufficiently high. It is realistic in that the timing of the eruption is difficult to predict precisely and in that the eruption occurs when the pressure of the gas exceeds the confining pressure of the lid. The experiment can be modified to show that an eruption will not occur if there is not enough gas pressure generated or if gas is allowed to escape gradually. Students will explain how the build-up of gas from dissolving alka seltzer causes the lid of a film cannister to blow off, explain that build-up of gas pressure causes eruption of explosive volcanoes, and that the pressure comes from heating of dissolved gases in the magma, and they will delineate the similarities and differences between the model and an actual volcano.

217

Seismic structure of Taal volcano  

NASA Astrophysics Data System (ADS)

In order to investigate seismicity and tectonic structure under Taal volcano, Philippines, a temporary seismic array consisting of 8 stations was deployed in this area since March 2008. As a pioneer seismic study in this area, our first goal is to build a robust 1-D velocity model using local earthquakes. In the mean time, we also apply ambient noise cross-correlation technique to the continuous records, aiming to search for the potential volcanic structure perturbations. While we were trying to retrieve Empirical Green's functions from cross-correlation functions (CCF) of ambient noise, unexpected linear drifting of clock time are clearly identified by the gradual shifting of symmetric center of daily CCFs. The clock errors have been further confirmed by comparing earthquake signals from teleseismic events. The errors are corrected before further data processing. Over 1100 local events are recorded in the duration from March 2008 to November 2008. Phase pickings from about 450 events are used to invert for event locations and 1-D velocity model by using the standard packages HYPO71 and VELEST. The obtained 1-D velocity model of Taal volcano is lower than the global average (AK135) at the depths less than 10 km, and most events (~90%) are also located at this shallow depth range. Two groups of seismicity are noticed, with the major one clustered under the western shore of Taal lake ranging, and the other spread from Main Crater Lake to the eastern of Taal volcano complex.

You, Shuei-Huei; Gung, Yuancheng; Konstantinou, Konstantinos I.; Lin, Cheng-Horng; Chang, Emmy T. Y.

2010-05-01

218

Flank tectonics of Martian volcanoes  

SciTech Connect

On the flanks of Olympus Mons is a series of terraces, concentrically distributed around the caldera. Their morphology and location suggest that they could be thrust faults caused by compressional failure of the cone. In an attempt to understand the mechanism of faulting and the possible influences of the interior structure of Olympus Mons, the authors have constructed a numerical model for elastic stresses within a Martian volcano. In the absence of internal pressurization, the middle slopes of the cone are subjected to compressional stress, appropriate to the formation of thrust faults. These stresses for Olympus Mons are {approximately}250 MPa. If a vacant magma chamber is contained within the cone, the region of maximum compressional stress is extended toward the base of the cone. If the magma chamber is pressurized, extensional stresses occur at the summit and on the upper slopes of the cone. For a filled but unpressurized magma chamber, the observed positions of the faults agree well with the calculated region of high compressional stress. Three other volcanoes on Mars, Ascraeus Mons, Arsia Mons, and Pavonis Mons, possess similar terraces. Extending the analysis to other Martian volcanoes, they find that only these three and Olympus Mons have flank stresses that exceed the compressional failure strength of basalt, lending support to the view that the terraces on all four are thrust faults.

Thomas, P.J. (Univ. of Wisconsin, Eau Claire (USA)); Squyres, S.W. (Cornell Univ., Ithaca, NY (USA)); Carr, M.H. (Geological Survey, Menlo Park, CA (USA))

1990-08-30

219

Topography of Martian central volcanoes  

NASA Astrophysics Data System (ADS)

Results are presented of the topographic mapping of six large central volcanoes on Mars. Stereo images of the volcanoes Olympus Mons, Elysium Mons, Albor Tholus, Ceraunius Tholus, Uranius Tholus and Uranius Patera were acquired by Viking Orbiter 1, and pairs of images were compiled into topographic maps through the use of digital image measurement techniques. Olympus Mons is found to have the general form of a terrestrial basaltic shield constructed almost entirely from lava flows, however with an altitude of 20-23 km and flank slopes averaging about 4 deg; a high nominal density indicates that anomalously dense lithosphere underlies the shield. Uranius Patera is observed to be a similar feature of present relief about 2 km, with its lower flanks buried by later lava flood deposits. Elysium Mons has about 13 km of local relief with average slopes of 4.4 deg, although its upper flank slopes are significantly steeper than those of Olympus Mons, suggesting a shield volcano modified by a terminal phase of mixed volcanic activity. Albor Tholus is found to be a partially buried 3-km shield-like construct, while Ceranius and Uranius Tholus are steeper cone-like features with reliefs of about 6 and 2 km, respectively, which may be lava shield constructs modified by a terminal stage of explosive activity.

Blasius, K. R.; Cutts, J. A.

1981-01-01

220

Huge landslide blocks in the growth of piton de la fournaise, La re??union, and Kilauea volcano, Hawaii  

USGS Publications Warehouse

Piton de la Fournaise, on the island of La Re??union, and Kilauea volcano, on the island of Hawaii, are active, basaltic shield volcanoes growing on the flanks of much larger shield volcanoes in intraplate tectonic environments. Past studies have shown that the average rate of magma production and the chemistry of lavas are quite similar for both volcanoes. We propose a structural similarity - specifically, that periodic displacement of parts of the shields as huge landslide blocks is a common mode of growth. In each instance, the unstable blocks are within a rift-zone-bounded, unbuttressed flank of the shield. At Kilauea, well-documented landslide blocks form relatively surficial parts of a much larger rift-zone-bounded block; scarps of the Hilina fault system mark the headwalls of the active blocks. At Fournaise, Hilina-like slump blocks are also present along the unbuttressed east coast of the volcano. In addition, however, the existence of a set of faults nested around the present caldera and northeast and southeast rift zones suggests that past chapters in the history of Fournaise included the slumping of entire rift-zone-bounded blocks themselves. These nested faults become younger to the east southeast and apparently record one of the effects of a migration of the focus of volcanism in that direction. Repeated dilation along the present set of northeast and southeast rift zones, most recently exemplified by an eruption in 1977, suggests that the past history of rift-zone-bounded slumping will eventually be repeated. The record provided by the succession of slump blocks on Fournaise is apparently at a relatively detailed part of a migration of magmatic focus that has advanced at least 30 km to the east-southeast from neighboring Piton des Neiges, an extinct Pliocene to Pleistocene volcano. ?? 1982.

Duffield, W. A.; Stieltjes, L.; Varet, J.

1982-01-01

221

Anomalous Soil Temperature and CO2 Emissions at Cerro Pacho (Coatepeque Caldera) and Santa Ana Volcano before the October 1, 2005 Eruption of Santa Ana Volcano  

NASA Astrophysics Data System (ADS)

Coatepeque Caldera and Santa Ana Volcano belong to the Santa Ana-Izalco-Coatepeque volcanic complex in western El Salvador. The last eruption of Santa Ana Volcano on October 1, 2005 killed two people and damaged 65% of the cultivated land around the volcano due to ash emissions and gases. Prior and after the eruption, we carry out several CO2 soil efflux and soil temperature surveys of Cerro Pacho fumarolic field and Santa Ana Volcano crater. For the diffuse CO2 emission, at Cerro Pacho the total CO2 efflux emited to the atmosphere from an area of 2600 m2 on April 1, September 7, and October 26, 2005, was 77, 99 and 64 kg/day respectively. In comparison, at the south-east perimeter of Santa Ana Crater, CO2 emissions on September 2 and September 21, 2005, were 112 and 442 g/m2 day, respectively (Barahona et al.,2007,this meeting). These values are one order of magnitude higher than the 15 g/m2 day measured in the same region by Salazar et al. (2004). For the soil temperatures at Cerro Pacho and at the south of Santa Ana crater, three areas of temperatures higher than 60°C were identified. According to Allis (1979), for soil temperatures lower than 60°C the dominant heat transport mechanism is conductive, there is a transition zone between 60-70°C, and the convective zone occurs at temperatures higher than 70°C up to the boiling point. At Santa Ana crater and at Cerro Pacho, the temperature anomalies were oriented in the NW-SE and E-W direction. In Santa Ana crater, the conductive zone was more important with a 49.1% of the surveyed area on May 8, and a 57% on April 7, 2005. This increase in convective heat flow suggest an increase in thermal heat from the volcano. At Cerro Pacho we have only a slight difference of 90 to 92% in the conductive area during April 3 and October 26, 2005, respectively. The increase in diffuse soil CO2 and the variations in the thermal field at the Santa Ana Crater and the Cerro Pacho fumarolic field can be interpreted as premonitory signals of the Santa Ana Volcano eruption. At other active volcanoes, monitoring of the soil temperature and diffuse emissions of gases could be important methods to follow the state of activity of a volcano.

Olmos, R.; Barahona, F.; Benítez, J.; Henríquez, B.; Hernández, A.; Funes, R.; López, D.; Hernández, P.; Pérez, N.

2007-05-01

222

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

NASA Astrophysics Data System (ADS)

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

Michon, Laurent; Saint-Ange, Francky

2008-03-01

223

Geophysical characteristics of the hydrothermal systems of Kilauea volcano, Hawaii  

SciTech Connect

Clues to the structure of Kilauea volcano can be obtained from spatial studies of gravity, magnetic, and seismic velocity variations. The rift zones and summit are underlain by dense, magnetic, and seismic velocity variations. The rift zones and summit are underlain by dense, magnetic, high P-wave-velocity rocks at depths of about 2 km less. The gravity and seismic velocity studies indicate that the rift structures are broad, extending farther to the north than to the south of the surface features. The magnetic data allow separation into a narrow, highly-magnetized, shallow zone and broad, flanking, magnetic lows. The patterns of gravity, magnetic variations, and seismicity document the southward migration of the upper east rift zone. Regional, hydrologic features of Kilauea can be determined from resistivity and self-potential studies. High-level groundwater exists beneath Kilauea summit to elevations of +800 m within a triangular area bounded by the west edge of the upper southwest rift zone, the east edge of the upper east rift zone, and the Koa'e fault system. High-level groundwater is present within the east rift zone beyond the triangular summit area. Self-potential mapping shows that areas of local heat produce local fluid circulation in the unconfined aquifer (water table). Shallow seismicity and surface deformation indicate that magma is intruding and that fractures are forming beneath the rift zones and summit area. Heat flows of 370--820 mW/m[sup 2] are calculated from deep wells within the lower east rift zone. The estimated heat input rate for Kilauea of 9 gigawatts (GW) is at least 25 times higher than the conductive heat loss as estimated from the heat flow in wells extrapolated over the area of the summit caldera and rift zones. 115 refs., 13 figs., 1 tab.

Kauahikaua, J. (Hawaiian Volcano Observatory, Hawaii National Park, HI (United States))

1993-08-01

224

Spatial vent opening probability map of Etna volcano (Sicily, Italy)  

NASA Astrophysics Data System (ADS)

We produce a spatial probability map of vent opening (susceptibility map) at Etna, using a statistical analysis of structural features of flank eruptions of the last 2 ky. We exploit a detailed knowledge of the volcano structures, including the modalities of shallow magma transfer deriving from dike and dike-fed fissure eruptions analysis on historical eruptions. Assuming the location of future vents will have the same causal factors as the past eruptions, we converted the geological and structural data in distinct and weighted probability density functions, which were included in a non-homogeneous Poisson process to obtain the susceptibility map. The highest probability of new eruptive vents opening falls within a N-S aligned area passing through the Summit Craters down to about 2,000 m a.s.l. on the southern flank. Other zones of high probability follow the North-East, East-North-East, West, and South Rifts, the latter reaching low altitudes (˜400 m). Less susceptible areas are found around the faults cutting the upper portions of Etna, including the western portion of the Pernicana fault and the northern extent of the Ragalna fault. This structural-based susceptibility map is a crucial step in forecasting lava flow hazards at Etna, providing a support tool for decision makers.

Cappello, A.; Neri, M.; Acocella, V.; Gallo, G.; Vicari, A.; Del Negro, C.

2012-11-01

225

Dike injection and magma mixing in Kenya rift volcanoes  

NASA Astrophysics Data System (ADS)

A nexus of volcanoes in the rift graben at approximately the latitude of Nairobi consist of central vent trachyte, phonolite, and peralkaline rhyolite and cinder cone and fissure-fed flows of basalt to benmoreite. The volcanoes are referred to as the Central Kenya Peralkaline Province (CKPP, Macdonald and Scaillet, 2006, Lithos 91, 59-73) and formed by a combination of processes including fractional crystallization, magma mixing, and volatile transport (Ren et al., 2006, Lithos 91, 109-124; Macdonald et al., 2008, JPet 49, 1515-1547). This presentation focuses on magma mixing for trachytes and phonolites for Suswa rocks, which are the southernmost part of the CKPP. We also explore the contribution of magma process studies to the interpretation of recent geodetic data, which indicate inflation/deflation of up to 21 cm for Kenyan volcanoes from 1997 to present (Biggs et al., 2009, Geology, in press). Incontrovertible evidence for magma mixing is found in field evidence, where a basaltic trachyandesite ash horizon is found interbedded with syncaldera trachyte (Skilling, 1993, J. Geol. Society London 150, 885-896), hand-specimen and thin-section petrography, and disequilibrium mineral chemistry. Precaldera lavas contain a homogeneous group of anorthoclase crystals with An content 6% or less. Syncaldera samples contain this same group and two other populations: polysynthetic twinned labradorite and andesine and anorthoclase with An content of 17%. Textures for all three groups indicate disequilibrium. Postcaldera flows contain the high and low An anorthoclase populations but lack the polysynthetic twinned labradorite and andesine. These observations suggest a model of injection of mafic magmas via diking into shallow trachtytic magma systems. Recent geodetic studies of dike injection and subsequent seismic/volcanic activity in both Ethiopia and Lengai point to the ongoing importance of these processes to rift evolution in East Africa.

Anthony, E. Y.; Espejel, V.; Biggs, J.

2009-12-01

226

Direct magmatic gas sampling at Gorely volcano (Kamchatka) in 2011  

NASA Astrophysics Data System (ADS)

Gorely volcano is located in Southern Kamchatka 75 km south-west of Petropavlovsk-Kamchatsky and 15 km north-west of Mutnovsky volcano. Gorely consists of 3 merged cones and is a ridge-like sublatitudinal structure (1830 masl) of basaltic-andesite-basaltic composition inside a 9x13 km caldera (of upper pleistocene age) situated in the East Volcanic Belt of Kamchatka. During the last 600-650 years eruptions of Gorely were explosive, mainly Vulcanian and phreatic. Since the 18th century a new eruptive cycle set with eruptions every 4-60 years. All eruptions in the 20th century (1929-31, 1961, 1980-81, 1984-86) occurred in the active crater of the central cone (Kirsanov and Melekestsev, 1991). Acid crater lakes appeared in the crater during non-eruptive periods in 1960, 1978-79, 1984, since 1992 (Egorov et al., 1998). After the last eruption vigorously degassing ~20 m red-glowing bocca in the active crater was first observed on June 16, 2010 5-7 m above the crater lake (Ovsyannikov and Chirkov, 2010). First direct sampling of magmatic gas and condensate on Gorely volcano was performed on September 20, 2011 during short fieldwork after 11th CCVG IAVCEI Workshop on Volcanic Gases. Samples were collected from the high-temperature (~900°C) vent near the bocca in the active crater. Chemical composition of gases, metallic trace element composition of ammonia solution from Giggenbach bottle and acid condensate (ICP-MS) as well as isotopic composition of H and O in condensate were determined. The results obtained will be presented and discussed. The study is supported by RFBR, grant 10-05-00649.

Chaplygin, I. V.; Shapar, V. N.; Timofeeva, I. F.; Dubinina, E. O.

2012-04-01

227

Steady subsidence of Medicine Lake volcano, northern California, revealed by repeated leveling surveys  

NASA Astrophysics Data System (ADS)

Leveling surveys of a 193-km circuit across Medicine Lake volcano (MLV) in 1954 and 1989 show that the summit area subsided by as much as 302 ± 30 mm (-8.6 ± 0.9 mm/yr) with respect to a datum point near Bartle, California, 40 km to the southwest. This result corrects an error in the earlier analysis of the same data by [1991], who reported the subsidence rate as -11.1 ± 1.2 mm/yr. The subsidence pattern extends across the entire volcano, with a surface area of nearly 2000 km2. Two areas of localized subsidence by as much as 20 cm can be attributed to shallow normal faulting near the volcano's periphery. Surveys of an east-west traverse across Lava Beds National Monument on the north flank of the volcano in 1990 and of a 23-km traverse across the summit area in 1999 show that subsidence continued at essentially the same rate during 1989-1999 as 1954-1989. Volcano-wide subsidence can be explained by either a point source of volume loss (Mogi) or a contracting horizontal rectangular dislocation (sill) at a depth of 10-11 km. Volume loss rate estimates range from 0.0013 to 0.0032 km3/yr, depending mostly on the source depth estimate and source type. Based on first-order quantitative considerations, we can rule out that the observed subsidence is due to volume loss from magma withdrawal, thermal contraction, or crystallizing magma at depth. Instead, we attribute the subsidence and faulting to: (1) gravitational loading of thermally weakened crust by the mass of the volcano and associated intrusive rocks, and (2) thinning of locally weakened crust by Basin and Range deformation. The measured subsidence rate exceeds long-term estimates from drill hole data, suggesting that over long timescales, steady subsidence and episodic uplift caused by magmatic intrusions counteract each other to produce the lower net subsidence rate.

Dzurisin, Daniel; Poland, Michael P.; Bürgmann, Roland

2002-12-01

228

Volcano deformation on a regional scale: insights from systematic InSAR surveys  

NASA Astrophysics Data System (ADS)

Space-based geodesy has allowed the measurement of volcano deformation on a regional scale through different stages of eruption cycles. This has included the detection of deformation at volcanoes too isolated or dangerous for ground based measurements, and at systems not previously thought to be active. The majority of InSAR volcano deformation events measured so far did not occur during eruptions. There are also a growing number of reports of a lack of deformation during volcanic eruption. A fair analysis of the relationship between deformation and volcanic unrest on a regional to global scale therefore requires a catalogue of when and where deformation does not occur as well as when it does. Reports of a lack of deformation during any stage of an eruption cycle are underrepresented in the published literature. As the distribution of global measurements is uneven, it is crucial to consider the method limitations in InSAR measurements of volcano deformation. For example, InSAR measurement is limited by dense vegetation, frequent explosive activity, steep topography and periodic snow cover. It is easier to make InSAR deformation measurements at shield volcanoes than at young stratovolcanoes, especially in equatorial regions where water vapour concentrations are high and vegetation may be dense. Any comparison between the incidence of deformation measured with InSAR in different regions therefore requires quantification of method limitations. We draw on systematic surveys of the Central American Volcanic Arc and the East African Rift as well as other published measurements to investigate commonalities and variations in volcano deformation and unrest.

Ebmeier, Susanna; Biggs, Juliet; Mather, Tamsin

2013-04-01

229

ODP DISCOVERS MUD VOLCANOES FROM THE MANTLE  

Microsoft Academic Search

Undersea volcanoes, oozing green, asbestos-rich mud, were discovered just west of the Mariana Trench in the western Pacific. Seafloor volcanoes are normally composed of molten lava, but the unusually large (more than 25,000 m in diameter and 2,000 m high) \\

Patricia Fryer

230

Endogenous growth of persistently active volcanoes  

Microsoft Academic Search

LAVA lakes and active strombolian vents have persisted at some volcanoes for periods exceeding the historic record. They liberate prodigious amounts of volatiles and thermal energy but erupt little lava, a paradox that raises questions about how volcanoes grow. Although long-lasting surface manifestations can be sustained by convective exchange of magma with deeper reservoirs, residence times of magmas beneath several

Peter Francis; Clive Oppenheimer; David Stevenson

1993-01-01

231

Characteristics of avalanche motion from Montserrat volcano  

Microsoft Academic Search

Solid block model is applied to describe avalanche motion under the action of gravity and Coulomb friction. Special attention is paid to characteristics of avalanche flow generated by Soufriere Hills Volcano (Montserrat) in likely directions. Duration of fall and velocity of avalanche are computed in order to estimate potential avalanche and tsunami hazard associated with eruption of Montserrat Volcano.

Irina Nikolkina; Narcisse Zahibo; Tatiana Talipova; Efim Pelinovsky

2010-01-01

232

Mechanisms of Groundwater Level Changes at Volcanoes  

Microsoft Academic Search

Groundwater level changes associated with eruptions have been observed at Mayon Volcano, Philippines and Usu and Miyake-jima Volcanoes, Japan. Possible mechanisms include strain, uplift or subsidence of the ground surface, boiling away of recharge and changes in the permeability of the aquifer. These mechanisms may work alone or in combination. In order to use such information for eruption forecasting, the

S. E. Albano; N. Matsumoto; C. G. Newhall; N. Koizumi; T. Sato

2002-01-01

233

Volcanoes and Volcanic Provinces: Martian Western Hemisphere  

Microsoft Academic Search

The recognition of some Martian landforms as volcanoes is based on their morphology and geologic setting. Other structures, however, may exhibit classic identifying features to a varying or a less degree; these may be only considered provisionally as having a volcanic origin. Regional geologic mapping of the western hemisphere of Mars from Viking images has revealed many more probable volcanoes

David H. Scott

1982-01-01

234

Infrared radiation thermometry of guatemalan volcanoes  

Microsoft Academic Search

A Barnes PRT-5 radiation thermometer was used to obtain apparent surface temperatures of two Guatemalan volcanoes from land-based stations from 500 to 4000 meters distant. Isotherms of apparent surface temperatures, drawn on photographs of the volcanic terrain under study, delineate areas of fumarolic activity and active domal upgrowth. The excess radiant heat emitted from Pacaya Volcano is calculated from apparent

R. W. Birnie

1973-01-01

235

Parallelizing the Volcano database query processor  

Microsoft Academic Search

Volcano is a new data flow query processing system developed for database systems research and education. All operators are designed and coded as if they were meant for a single-process system only. The design implementation of Volcano's exchange operator that parallelizes all other operators is described. It allows intraoperator parallelism on partitioned data assets and both vertical and horizontal interoperator

Goetz Graefe

1990-01-01

236

Middle East  

SciTech Connect

Petroleum production in Middle East countries during 1980 totaled 6,747,719,000 bbl or an average rate of 18,436,390,000 bbl/d, down 13.9% from 1979. Increases were in Saudi Arabia and Syria. Significant decreases occurred in Iraq, Iran, Kuwait, and Turkey. New discoveries were made in Abu Dhabi, Iran, Saudi Arabia, Sharjah, and Oman. New areas were explored in Bahrain, Oman, Syria, and Yemen. 9 figures, 16 tables.

Hemer, D.O. (Mobil Oil Corp., New York, NY); Mason, J.F.; Hatch, G.C.

1981-10-01

237

USGS: Cascades Volcano Observatory Educational Outreach  

NSDL National Science Digital Library

Reaching out to a volcano can be a precarious enterprise. Reaching out to teach young people about volcanoes and related geological matters is less precarious, particularly after discovering this site. Created by staff members at the United States Geological Survey's Cascades Volcano Observatory, this site brings together educational materials such as short videos, printable posters, and fact sheets. Teachers may wish to start at the "Learn About Volcanoes" area. Here they will find resources that will help them teach students about volcano terminology, eruption histories, and the answer to the question "Can Lava Be Diverted?" Moving along, the "Special Features and Useful Pages" includes interactive photo tours of Mount Rainier and an excellent timetable of the Cascade Range.

2007-11-28

238

Isotopic composition of gases from mud volcanoes  

SciTech Connect

A study has been made of the isotopic composition of the carbon in methane and carbon dioxide, as well as hydrogen in the methane, in the gases of mud volcanoes, for all main mud volcano areas in the USSR. The isotopic composition of carbon and hydrogen in methane shows that the gases resemble those of oil and gas deposits, while carbon dioxide of these volcanoes has a heavier isotopic composition with a greater presence of ''ultraheavy'' carbon dioxide. By the chemical and isotopic composition of gases, Azerbaidzhan and South Sakhalin types of mud volcano gases have been identified, as well as Bulganak subtypes and Akhtala and Kobystan varieties. Correlations are seen between the isotopic composition of gases and the geological build of mud volcano areas.

Valysaev, B.M.; Erokhin, V.E.; Grinchenko, Y.I.; Prokhorov, V.S.; Titkov, G.A.

1985-09-01

239

Introduction to Special Section on How Volcanoes Work: Part 2  

NASA Astrophysics Data System (ADS)

The special section on "How Volcanoes Work" is a collection of some of the nearly 300 papers presented at the Hawaii Symposium on How Volcanoes Work, held in Hilo in January 1987 [Tilling, 1987a]. The response of the symposium participants to the invitation to submit their papers for consideration in the special section exceeded expectations. In all, more than 70 manuscripts were received, reviewed, and handled following regular JGR editorial procedures. Part 1 of the special section, composed of the papers that were processed and accepted in time to meet the production schedule, was published in the December 1987 issue of the Journal of Geophysical Research-Solid Earth and Planets [Tilling, 1987a]. Even though part 1 contained only eight papers, it nonetheless provided a representative sampling of the multidisciplinary nature of the investigations undertaken to improve our understanding of volcanic systems. The papers published in part 1 included ground deformation studies on caldera systems [Dzurisin and Yamashita, 1987; Mortensen and Hopkins, 1987], geochemical and observational studies of the lava fountains and of volcanic fume during the 1983-1984 activity of Pu'u 'O'o in Kilauea's east rift zone [Crowe et al., 1987; Head and Wilson, 1987], magmatic crystal stratigraphy and theoretical petrology [Pearce et al., 1987; Russell, 1987], dynamics of active lava lakes [Tilling, 1987b], and seismic evidence for a subcrustal intrusive complex beneath the Island of Oahu, Hawaii [ten Brink and Brocher, 1987].

Tilling, Robert I.

1988-05-01

240

Volcanic gas impacts on vegetation at Turrialba Volcano, Costa Rica  

NASA Astrophysics Data System (ADS)

Turrialba volcano is an active composite stratovolcano that is located approximately 40 km east of San Jose, Costa Rica. Seismic activity and degassing have increased since 2005, and gas compositions reflect further increased activity since 2007 peaking in January 2010 with a phreatic eruption. Gas fumes dispersed by trade winds toward the west, northwest, and southwest flanks of Turrialba volcano have caused significant vegetation kill zones, in areas important to local agriculture, including dairy pastures and potato fields, wildlife and human populations. In addition to extensive vegetative degradation is the potential for soil and water contamination and soil erosion. Summit fumarole temperatures have been measured over 200 degrees C and gas emissions are dominated by SO2; gas and vapor plumes reach up to 2 km (fumaroles and gases are measured regularly by OVSICORI-UNA). A recent network of passive air sampling, monitoring of water temperatures of hydrothermal systems, and soil pH measurements coupled with measurement of the physiological status of surrounding plants using gas exchange and fluorescence measurements to: (1) identify physiological correlations between leaf-level gas exchange and chlorophyll fluorescence measurements of plants under long term stress induced by the volcanic gas emissions, and (2) use measurements in tandem with remotely sensed reflectance-derived fluorescence ratio indices to track natural photo inhibition caused by volcanic gas emissions, for use in monitoring plant stress and photosynthetic function. Results may prove helpful in developing potential land management strategies to maintain the biological health of the area.

Teasdale, R.; Jenkins, M.; Pushnik, J.; Houpis, J. L.; Brown, D. L.

2010-12-01

241

Exploring Geology on the World-Wide Web--Volcanoes and Volcanism.  

ERIC Educational Resources Information Center

|Focuses on sites on the World Wide Web that offer information about volcanoes. Web sites are classified into areas of Global Volcano Information, Volcanoes in Hawaii, Volcanoes in Alaska, Volcanoes in the Cascades, European and Icelandic Volcanoes, Extraterrestrial Volcanism, Volcanic Ash and Weather, and Volcano Resource Directories. Suggestions…

Schimmrich, Steven Henry; Gore, Pamela J. W.

1996-01-01

242

Volcano Flank Terraces on Mars  

NASA Astrophysics Data System (ADS)

Flank terraces are bulge-like structures that occur on the slopes of at least nine large shield volcanoes on Mars, and three on Earth. Terraces have a convex-upward, convex-outward morphology, with an imbricate "fish scale" stacking pattern in plan. They occur at all elevations, are scale-invariant structures, and have similar proportions to thrust faults on Earth. Suggested mechanisms of formation include elastic self-loading, lithospheric flexure, magma chamber tumescence, flank relaxation, and shallow gravitational slumping. Terrace geometries predicted by most of these mechanisms do not agree with our observations, however. Only lithospheric flexure can fully account for terrace geometry on Mars and Earth, and so is the most likely candidate mechanism for flank terrace formation. To verify this hypothesis, we conducted scaled analogue modelling experiments, and investigated the structures formed during flexure. Cones of a sand-gypsum mix were placed upon a deep layer of silicone gel, to simulate volcanic loads upon viscoelastic Martian crust. Key parameters were varied across our experimental program. In all cases convex topographic structures developed on the cones' flanks, arranged in an imbricate, overlapping plan-view pattern. These structures closely resemble flank terraces observed on Mars, and our results provide for a basic kinematic model of terrace formation. Analogue volcanoes experienced a decrease in upper surface area whilst volume was conserved; the contractional surface strain was accommodated by outward verging, circumferentially striking thrusts. The morphology of experimental structures suggests an orientation of the principal stress axes of ?1 = radial, ?2 = concentric, and ?3 = vertical. Elsewhere (J. B. Murray et al., this volume) we detail the relationship between flank terraces and other structures such as pit craters and gräben, using Ascraeus Mons as a case study. We suggest that terraces may influence the distribution and location of these other structures, and thus play a fundamental role in the tectonic development of large shield volcanoes on Mars.

Byrne, P. K.; van Wyk de Vries, B.; Murray, J. B.; Troll, V. R.

2008-12-01

243

Physical volcanology of the submarine Mariana and Volcano Arcs  

Microsoft Academic Search

Narrow-beam maps, selected dredge samplings, and surveys of the Mariana and Volcano Arcs identify 42 submarine volcanos. Observed activity and sample characteristics indicate 22 of these to be active or dormant. Edifices in the Volcano Arc are larger than most of the Mariana Arc edifices, more irregularly shaped with numerous subsidiary cones, and regularly spaced at 50–70 km. Volcanos in

Sherman H. Bloomer; Robert J. Stern; N. Christian Smoot

1989-01-01

244

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

NASA Astrophysics Data System (ADS)

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

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

2003-12-01

245

Geodetic evidence for en echelon dike emplacement and concurrent slow slip during the June 2007 intrusion and eruption at K?lauea volcano, Hawaii  

Microsoft Academic Search

A series of complex events at K?lauea Volcano, Hawaii, 17 June to 19 June 2007, began with an intrusion in the upper east rift zone (ERZ) and culminated with a small eruption (1500 m3). Surface deformation due to the intrusion was recorded in unprecedented detail by Global Positioning System (GPS) and tilt networks as well as interferometric synthetic aperture radar

E. K. Montgomery-Brown; D. K. Sinnett; M. Poland; P. Segall; T. Orr; H. Zebker; A. Miklius

2010-01-01

246

Geodetic evidence for en echelon dike emplacement and concurrent slow slip during the June 2007 intrusion and eruption at Kilauea volcano, Hawaii  

Microsoft Academic Search

A series of complex events at Kilauea Volcano, Hawaii, 17 June to 19 June 2007, began with an intrusion in the upper east rift zone (ERZ) and culminated with a small eruption (1500 m3). Surface deformation due to the intrusion was recorded in unprecedented detail by Global Positioning System (GPS) and tilt networks as well as interferometric synthetic aperture radar

E. K. Montgomery-Brown; D. K. Sinnett; M. Poland; P. Segall; T. Orr; H. Zebker; A. Miklius

2010-01-01

247

Unzipping of the volcano arc, Japan  

USGS Publications Warehouse

A working hypothesis for the recent evolution of the southern Volcano Arc, Japan, is presented which calls upon a northward-progressing sundering of the arc in response to a northward-propagating back-arc basin extensional regime. This model appears to explain several localized and recent changes in the tectonic and magrnatic evolution of the Volcano Arc. Most important among these changes is the unusual composition of Iwo Jima volcanic rocks. This contrasts with normal arc tholeiites typical of the rest of the Izu-Volcano-Mariana and other primitive arcs in having alkaline tendencies, high concentrations of light REE and other incompatible elements, and relatively high silica contents. In spite of such fractionated characteristics, these lavas appear to be very early manifestations of a new volcanic and tectonic cycle in the southern Volcano Arc. These alkaline characteristics and indications of strong regional uplift are consistent with the recent development of an early stage of inter-arc basin rifting in the southern Volcano Arc. New bathymetric data are presented in support of this model which indicate: 1. (1) structural elements of the Mariana Trough extend north to the southern Volcano Arc. 2. (2) both the Mariana Trough and frontal arc shoal rapidly northwards as the Volcano Arc is approached. 3. (3) rugged bathymetry associated with the rifted Mariana Trough is replaced just south of Iwo Jima by the development of a huge dome (50-75 km diameter) centered around Iwo Jima. Such uplifted domes are the immediate precursors of rifts in other environments, and it appears that a similar situation may now exist in the southern Volcano Arc. The present distribution of unrifted Volcano Arc to the north and rifted Mariana Arc to the south is interpreted not as a stable tectonic configuration but as representing a tectonic "snapshot" of an arc in the process of being rifted to form a back-arc basin. ?? 1984.

Stern, R. J.; Smoot, N. C.; Rubin, M.

1984-01-01

248

Growth and collapse of the Reunion Island volcanoes  

NASA Astrophysics Data System (ADS)

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

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

2008-04-01

249

University of Tokyo: Volcano Research Center (VRC)  

NSDL National Science Digital Library

This website discusses the Volcano Research Center's (VRC) work to improve predictions of volcanic eruptions by conducting research on volcanic processes. Users can find out about Asama, Kirishima, Izu-Oshima, and other VRC volcano observatories. The website features information on many continuing and recent eruptions in Japan. Visitors can view many images of volcanic eruptions and disaster relief missions. Researchers can learn about the international cooperative drilling operation at the Unzen Volcano to understand the eruption mechanisms and magnetic activity. This site is also reviewed in the February 20, 2004 _NSDL Physical Sciences Report_.

250

Pavlof Volcano darkens the Alaskan sky  

NASA Astrophysics Data System (ADS)

Pavlof Volcano, historically the most active volcano in the Aleutian volcanic arc and a serious potential threat to aviation safety, began a vigorous strombolian eruption in mid-September. Located 965 km southwest of Anchorage, Pavlof lies beneath the heavily traveled North Pacific jet air routes through which 10,000 passengers fly each day. During its most recent eruption in 1986-1988, an 8-hour explosive event at Pavlof sent ash more than 15 km above sea level and dropped 3 mm of ash on Cold Bay, 60 km southwest of the volcano. A similar, unanticipated explosive eruption today would pose a significant hazard to air traffic in the region.

Neal, Tina

251

Subsidence associated with the LUSI mud eruption, East Java, investigated by SAR interferometry  

Microsoft Academic Search

A mud volcano LUSI initiated its eruption on 29 May 2006, adjacent to a hydrocarbon exploration well in East Java. Ground subsidence in the vicinity of the LUSI eruptive vent was well recorded by a Synthetic Aperture Radar (SAR) PALSAR onboard the Japanese ALOS satellite. We apply an Interferometric SAR (InSAR) technique on ten PALSAR data scenes, acquired between 19

Yo Fukushima; Jim Mori; Manabu Hashimoto; Yasuyuki Kano

2009-01-01

252

Intraplate volcanism and mantle dynamics in East Asia: Big mantle wedge (BMW) model (Invited)  

NASA Astrophysics Data System (ADS)

In the East Asia continent there are many Cenozoic volcanoes, but only a few are still active now, such as the Changbai, Wudalianchi, and Tengchong volcanoes which have erupted several times in the past 1000 years. Although many studies have been made by using various approaches, the origin of the intraplate volcanoes in East Asia is still not very clear. Recently we used regional and global seismic tomography to determine high-resolution 3-D mantle structure under Western Pacific to East Asia (Zhao, 2004; Huang and Zhao, 2006; Zhao et al., 2009). Our results show prominent low-velocity anomalies from the surface down to 410 km depth beneath the intraplate volcanoes and a broad high-velocity anomaly in the mantle transition zone under East Asia. Focal-mechanism solutions of deep earthquakes indicate that the subducting Pacific slab under the Japan Sea and the East Asia margin is subject to compressive stress regime. These results suggest that the Pacific slab meets strong resistance at the 660-km discontinuity and so it becomes stagnant in the mantle transition zone under East Asia. The Philippine Sea slab has also subducted down to the mantle transition zone under western Japan and the Ryukyu back-arc region. The western edge of the stagnant slab is generally parallel with the Japan trench and the Ryukyu trench and roughly coincides with a prominent surface topography and gravity boundary in East China, which is located approximately 1800 km west of the trenches. The upper mantle under East Asia has formed a big mantle wedge (BMW) above the stagnant slab. The BMW exhibits low seismic-velocity and high electrical-conductivity, which is hot and wet because of the deep dehydration reactions of the stagnant slab and the convective circulation process in the BMW. These processes lead to the upwelling of hot and wet asthenospheric materials and thinning and fracturing of the continental lithosphere, leading to the formation of the active intraplate volcanoes in East Asia. Our results also show that the active Tengchong volcano in SW China is related to the deep subduction of the Burma microplate down to the mantle transition zone and a BMW above the Burma slab. References: D. Zhao (2004) Phys. Earth Planet. Inter. 146, 3-34. J. Huang, D. Zhao (2006) J. Geophys. Res. 111, B09305. D. Zhao et al. (2009) Phys. Earth Planet. Inter. 173, 197-206.

Zhao, D.

2009-12-01

253

Relationship between Kamen Volcano and the Klyuchevskaya group of volcanoes (Kamchatka)  

NASA Astrophysics Data System (ADS)

Data on the geology, petrography, mineralogy, and geochemistry of rocks from Kamen Volcano (Central Kamchatka Depression) are presented and compared with rocks from the neighbouring active volcanoes. The rocks from Kamen and Ploskie Sopky volcanoes differ systematically in major elemental and mineral compositions and could not have been produced from the same primary melts. The compositional trends of Kamen stratovolcano lavas and dikes are clearly distinct from those of Klyuchevskoy lavas in all major and trace element diagrams as well as in mineral composition. However, lavas of the monogenetic cones on the southwestern slope of Kamen Volcano are similar to the moderately high-Mg basalts from Klyuchevskoy and may have been derived from the same primary melts. This means that the monogenetic cones of Kamen Volcano represent the feeding magma for Klyuchevskoy Volcano. Rocks from Kamen stratovolcano and Bezymianny form a common trend on all major element diagrams, indicating their genetic proximity. This suggests that Bezymianny Volcano inherited the feeding magma system of extinct Kamen Volcano. The observed geochemical diversity of rocks from the Klyuchevskaya group of volcanoes can be explained as the result of both gradual depletion over time of the mantle N-MORB-type source due to the intense previous magmatic events in this area, and the addition of distinct fluids to this mantle source.

Churikova, Tatiana G.; Gordeychik, Boris N.; Ivanov, Boris V.; Wörner, Gerhard

2013-08-01

254

Dynamics of degassing at Kilauea Volcano, Hawaii  

NASA Astrophysics Data System (ADS)

At Kilauea volcano, Hawaii, the recent long-lived eruptions of Mauna Ulu and Pu'u O'o have occurred in two major stages, defining a characteristic eruptive pattern. The first stage consists of cyclic changes of activity between episodes of "fire fountaining" and periods of quiescence or effusion of vesicular lava. The second stage consists only of continuous effusion of lava. We suggest that these features reflect the dynamics of magma degassing in a chamber which empties into a narrow conduit. In the volcano chamber, gas bubbles rise through magma and accumulate at the roof in a foam layer. The foam flows toward the conduit, and its shape is determined by a dynamic balance between the input of bubbles from below and the output into the conduit. The foam thickness is proportional to (?lQ/?2 ?l g)1/4, where ? l and ?l are the viscosity and density of magma, ? is the gas volume fraction in the foam, g is the acceleration of gravity, and Q is the gas flux. The bubbles in the foam deform under the action of buoyancy, and the maximum permissible foam thickness is hc = 2?/??lgR, where ? is the coefficient of surface tension and R is the original bubble radius. If this critical thickness is reached, the foam collapses into a large gas pocket which erupts into the conduit. Foam accumulation then resumes, and a new cycle begins. The attainment of the foam collapse threshold requires a gas flux in excess of a critical value which depends on viscosity, surface tension, and bubble size. Hence two different eruption regimes are predicted: (1) alternating regimes of foam buildup and collapse leading to the periodic eruption of large gas volumes and (2) steady foam flow at the roof leading to continuous bubbly flow in the conduit. The essential result is that the continuous process of degassing can lead to discontinuous eruptive behavior. Data on eruption rates and repose times between fountaining phases from the 1969 Mauna UIu and the 1983-1986 Pu'u O'o eruptions yield constraints on three key variables. The area of the chamber roof must be a few tens of square kilometers, with a minimum value of about 8 km2. Magma reservoirs of similar dimensions are imaged by seismic attenuation tomography below the east rift zone. Close to the roof, the gas volume fraction is a few percent, and the gas bubbles have diameters lying between 0.1 and 0.6 mm. These estimates are close to the predictions of models for bubble nucleation and growth in basaltic melts, as well as to the observations on deep submarine basalts. The transition between cyclic and continuous activity occurs when the mass flux of gas becomes lower than a critical value of the order of 103 kg/s. In this model, changes of eruptive regime reflect changes in the amount and size of bubbles which reach the chamber roof.

Vergniolle, Sylvie; Jaupart, Claude

1990-03-01

255

Volcanoes can muddle the greenhouse  

SciTech Connect

As scientists and politicians anxiously eye signs of global greenhouse warming, climatologists are finding the best evidence yet that a massive volcanic eruption can temporarily bring the temperature down a notch or two. Such a cooling could be enough to set the current global warming back more than a decade, confusing any efforts to link it to the greenhouse effect. By effectively eliminating some nonvolcanic climate changes from the record of the past 100 years, researchers have detected drops in global temperature of several tenths of a degree within 1 to 2 years of volcanic eruptions. Apparently, the debris spewed into the stratosphere blocked sunlight and caused the temperature drops. For all their potential social significance, the climate effects of volcanoes have been hard to detect. The problem has been in identifying a volcanic cooling among the nearly continuous climate warmings and coolings of a similar size that fill the record. The paper reviews how this was done.

Kerr, R.A.

1990-01-01

256

Volcanoes and Global Climate Change  

NSDL National Science Digital Library

This lesson is designed to help students use appropriate tools and techniques to gather, analyze, and interpret data; develop descriptions, explanations, predictions and models using evidence; develop an understanding of the Earth as a system by understanding that global patterns of atmospheric movement influence climate, including local weather; and understand that internal and external processes of the Earth system cause natural hazards (volcanoes) that can change or destroy human and wildlife habitats, damage property and harm or kill humans. Students will demonstrate numerous cooperative learning strategies in response to a presentation of basic concepts. They will also collect, analyze, and interpret data, and make predictions based on its synthesis. The lesson provides detailed instructions as well as worksheets, charts, internet access, and publications.

257

Hawaii Volcanoes National Park: Collection Management Plan.  

National Technical Information Service (NTIS)

The collections of Hawaii Volcanoes National Park are comprised of historical, ethnographic, archeological, and fine arts objects as well as an extensive and active natural history collection. In a recent appraisal the cultural objects were valued at more...

D. R. Pardue D. Nicholson D. Cumberland M. Tanaka-Sanders

1989-01-01

258

Volcanology: A volcano's sharp intake of breath  

NASA Astrophysics Data System (ADS)

Shallow magma bodies that feed regularly erupting volcanoes are usually considered enduring features that grow steadily between eruptions. Measurements of deformation at Santorini, however, reveal sudden rapid magma accumulation after half a century of rest.

Hooper, Andrew

2012-10-01

259

Lahar hazards at Agua Volcano, Guatemala  

USGS Publications Warehouse

At 3,760 meters, Agua volcano towers more than 3,500 meters above the Pacific coastal plain to the south and 2,000 meters above the Guatemalan highlands to the north. The volcano is within 5 to 10 kilometers of Antigua, Guatemala and several other large towns situated on its northern apron. These towns have a combined population of nearly 100,000. It is within about 20 kilometers of Escuintla (population, ca .100,000) to the south. Though the volcano has not been active in historical time, or about the last 500 years, it has the potential to produce debris flows (watery flows of mud, rock, and debris -- also known as lahars when they occur on a volcano) that could inundate these nearby populated areas. -- Schilling, et.al., 2001

Schilling, S. P.; Vallance, J. W.; Matias, O.; Howell, M. M.

2001-01-01

260

Halogen Oxide Measurements at Masaya Volcano, Nicaragua  

NASA Astrophysics Data System (ADS)

Sulphur dioxide (SO2) and halogen oxide emissions were measured at Masaya Volcano in Nicaragua in April 2007 using differential optical absorption spectroscopy (DOAS). Next to passive DOAS measurements using scattered sunlight, an active long-path DOAS system was operated for several days with the light beam crossing the crater of the volcano. These measurements for the first time give an insight into the night-time halogen chemistry occurring at volcanoes. While the passive DOAS instruments measured sulphur dioxide (SO2) and bromine monoxide (BrO) in various viewing geometries and distances from the crater during daytime, the active instrument additionally allowed a quantification of chlorine monoxide (ClO) and chlorine dioxide (OClO), as well as being able to measure round-the-clock. The results of the field measurements will be presented and their implications for halogen chemistry at volcanoes will be discussed.

Kern, C.; Vogel, L.; Sihler, H.; Rivera, C.; Strauch, W.; Galle, B.; Platt, U.

2007-12-01

261

Eruption of Alaska volcano breaks historic pattern  

USGS Publications Warehouse

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

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

2009-01-01

262

Newberry Volcano—Central Oregon's Sleeping Giant  

USGS Publications Warehouse

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

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

2011-01-01

263

Mineralized microbes from Giggenbach submarine volcano  

Microsoft Academic Search

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

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

2008-01-01

264

Infrared radiation thermometry of guatemalan volcanoes  

Microsoft Academic Search

A Barnes PRT-5 radiation thermometer was used to obtain apparent surface temperatures of two Guatemalan volcanoes from land-based\\u000a stations from 500 to 4000 meters distant. Isotherms of apparent surface temperatures, drawn on photographs of the volcanic\\u000a terrain under study, delineate areas of fumarolic activity and active domal upgrowth.\\u000a \\u000a The excess radiant heat emitted from Pacaya Volcano is calculated from apparent

R. W. Birnie

1973-01-01

265

Airborne ice nuclei near an active volcano  

Microsoft Academic Search

ACTIVE volcanoes have been suggested as being sources of atmospheric ice nuclei1,2, the rare yet crucial particles that initiate much of the Earth's precipitation. Other studies indicate that some volcanoes are not adding ice nuclei to the atmosphere or may be deactivating natural ice nuclei3-5. We report here measurements of atmospheric ice nucleus concentrations upwind and within the effluent plume

Russell C. Schnell

1976-01-01

266

Trace element geochemistry of volcanic gases and particles from 1983-1984 eruptive episodes of Kilauea volcano  

Microsoft Academic Search

Compositional data have been obtained for volcanic gases and particles collected from fume emitted at the Pu'u O'o vent on the east rift zone of Kilauea volcano. The samples were collected by pumping fume through a filter pack system consisting of a front stage particulate filter followed by four base-treated filters (7LiOH). Particles and condensed phases are trapped on the

Bruce M. Crowe; David L. Finnegan; William H. Zoller; William V. Boynton

1987-01-01

267

Lava bubble-wall fragments formed by submarine hydrovolcanic explosions on L?'ihi Seamount and K?lauea Volcano  

Microsoft Academic Search

Glassy bubble-wall fragments, morphologically similar to littoral limu o Pele, have been found in volcanic sands erupted\\u000a on L?'ihi Seamount and along the submarine east rift zone of K?lauea Volcano. The limu o Pele fragments are undegassed with\\u000a respect to H2O and S and formed by mild steam explosions. Angular glass sand fragments apparently form at similar, and greater, depths

David A. Clague; Alice S. Davis; James L. Bischoff; Jacqueline E. Dixon; Renee Geyer

2000-01-01

268

Stress changes during the rapid deformation of Miyakejima volcano on 26-27 June 2000  

NASA Astrophysics Data System (ADS)

Deformation often signals the occurrence of magmatic processes within volcanoes, such as the intrusion of new magma bodies and inflation or deflation, of existing bodies. Stress change induced by magmatic activity can drive propagation of dike and earthquake activity. Conversely, by relieving stresses from previous intrusive processes, can establish stress states favorable to new or continued intrusion. In this research we have modeled stress transfer effects during the dikes intrusion sequence in Miyakejima volcano on 26-27 June 2000. On 26-27 June 2003, a kinematic GPS analysis of data from the the Miyakejima volcano captured a fast developing event in unprecedented spatial and temporal detail. Initial ground deformation toward east and upward was observed in the southeastern part of the volcano at 18:00 on 26 June 2000, almost simultaneous with earthquake swarms. Some time after 21:30 on 26 June the displacements at these sites turned from eastward to westward. Three hours later the displacement rates increased gradually at GPS sites in the western part of Miyakejima as the seismicity migrated and approached the west coast, and reached a climax with the submarine eruption at 09:00 on 27 June 2000. The non linear inversion of GPS data leads to an interpretation that the 18:00, 26 June earthquake swarm was caused by a dike intrusion near the Oyama crater. Starting from 21:30 this dike deflated and a new dike intruded near the west coast. Following the propagation of this dike to the offshore, a spherical source began deflating in the southwest of Oyama crater. This research attempts to identify and delineate stress interactions and to develop a consistent model of magmatic processes in Miyakejima volcano.

Irwan, M.; Kimata, F.; Fujii, N.

2003-12-01

269

Evolution of the Hawaiian Plume: Evidence from Submarine Haleakala Volcano (Hana Ridge), Hawaii  

NASA Astrophysics Data System (ADS)

Hana Ridge is the submarine portion of the east rift zone of Haleakala Volcano, Hawaii. At 140 km long, Hana Ridge is the longest submarine rift zone in the Hawaiian Island chain and has developed a complex morphology compared to other Hawaiian rift zones, such as Puna Ridge. The main ridge comprises two or three subparallel or subjacent ridges with distinct morphological expressions related to sequential accretionary stages of the shield-building phase of Haleakala volcano. In order to investigate the geochemical evolution of Haleakala shield-building, we sampled several sections of Hana Ridge on six dives with ROV Kaiko and Shinkai 6500 submersible, both operated by JAMSTEC, in 2001 and 2002. We report new geochemical data for basalt samples from these six dives on Hana Ridge. All the recovered rocks are primitive tholeiites and picrites and more than half of them, those obtained in the deeper portions of the ridge, are picrites. Major and trace elements of the submarine Hana ridge rocks are similar to modern Kilauea and unlike Honomanu series lavas. Our results indicate that the mantle plume source for the Haleakala shield has changed over time from Kilauea-like compositions (high La/Sm, low Zr/Nb) in the submarine lavas to Mauna Loa-like compositions (lower La/Sm, higher Zr/Nb) in the subaerial Honomanu shield lavas. Moreover, the submarine stages show a gradual, but irregular, trend from higher to lower La/Sm with decreasing water depth (inferred to be decreasing age). We infer that Haleakala volcano originally had typical Hawaiian tholeiite magma compositions whose source material was similar to present-day Kilauea volcano and that the magma source became more Mauna Loa-like during growth of Haleakala volcano.

Johnson, K. T.; Ren, Z.; Takahashi, E.; Orihashi, Y.

2002-12-01

270

Hydrogeochemical exploration of the Tecuamburro Volcano region, Guatemala  

SciTech Connect

Approximately 100 thermal and nonthermal water samples and 20 gas samples from springs and fumaroles have been chemically and isotopically analyzed to help evaluate the geothermal potential of the Tecuamburro Volcano region, Guatemala. Thermal waters of the acid- sulfate, steam condensate, and neutral-chloride types generally occur in restricted hydrogeologic areas: Tecuamburro-Laguna Ixpaco (acid- sulfate); andesite highland north of Tecuamburro (steam-condensate); Rio Los Esclavos (neutral-chloride). One small area of neutral-chloride springs east of the village of Los Esclavos has no relation to the Tecuamburro geothermal system. Neutral-chloride springs on the Rio Los Esclavos east and southeast of Tecuamburro show mixing with various types of groundwaters and display a maximum oxygen-18 enrichment compared to the world meteoric line of only about 1.5 parts per thousand. Maximum estimated subsurface temperatures are {le}200{degree}C. In contrast, maximum estimated subsurface temperatures based on gas compositions in the Laguna Ixpaco area are about 300{degree}C. The relation of neutral-chloride waters to the overall Tecuamburro geothermal system is not entirely resolved but we have suggested two system models. Regardless of model, we believe that a first exploration drill hole should be sited within 0.5 km of Laguna Ixpaco to tap the main geothermal reservoir or its adjacent, main upflow zone. 9 refs., 4 figs., 3 tabs.

Goff, F.; Truesdell, A.H.; Janik, C.J.; Adams, A.; Roldan-M, A.; Meeker, K. (Los Alamos National Lab., NM (USA); Geological Survey, Menlo Park, CA (USA); Los Alamos National Lab., NM (USA); Instituto Nacional de Electrificacion, Guatemala City (Guatemala). Unidad de Desarollo Geotermico; Los Alamos National Lab., NM (USA))

1989-01-01

271

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

Microsoft Academic Search

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

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

1999-01-01

272

When mud volcanoes sleep: Insight from seep geochemistry at the Dashgil mud volcano, Azerbaijan  

Microsoft Academic Search

The worlds >1500 mud volcanoes are normally in a dormant stage due to the short duration of eruptions. Their dormant stage activity is often characterized by vigorous seepage of water, gas, and petroleum. However, the source of the fluids and the fluid–rock interactions within the mud volcano conduit remain poorly understood. In order to investigate this type of activity, we

A. Mazzini; H. Svensen; S. Planke; I. Guliyev; G. G. Akhmanov; T. Fallik; D. Banks

2009-01-01

273

Classification of Martian Volcanoes on Basis of Volcano Ground Ice Interaction  

Microsoft Academic Search

Most Martian volcanoes have common morphological features indicating mass wasting and erosion compatible with large scale break down of ground ice. While some features suggest the ground ice melted rapidly resulting in catastrophic erosive events, other features indicate a slow melting process (e.g sublimation) resulting in collapse structures. To determine relative volcano age and activity on Mars it is suggested

J. Helgason

2000-01-01

274

Buried Rift Zones and Seamounts in Hawaii: Implications for Volcano Tectonics  

NASA Astrophysics Data System (ADS)

As volcanoes grow, they deform due to their own weight and ongoing magmatic intrusions. For example, Kilauea's south flank is moving seaward ~10 cm/yr, apparently pushed by dike injection along rift zones and/or gravitational spreading. Offshore, Kilauea's south flank has developed a broad bench, attributed to overthrusting at the toe of the mobile flank. Mauna Loa's southeastern flank is much less mobile today, and exhibits no offshore bench. The great variability in present-day surface motions and deformation of these two volcanoes is not well explained by the distribution of surface structures, which might influence the driving and resisting forces acting on the flanks. Using first-arrival seismic tomography of a unique onshore-offshore airgun dataset, we have developed a 3-D P-wave velocity model of the southeastern part of the Island of Hawaii. This model provides an unprecedented view into both the submarine and subaerial portions of Kilauea, Mauna Loa, and Loihi volcanoes, helping to resolve some outstanding puzzles. The preferred velocity model shows that the known summits and rift zones of Kilauea, Mauna Loa and Loihi volcanoes are underlain by high velocity anomalies (6.5-7.0 km/s), indicating the presence of intrusive magma cumulates and dike complexes. In addition, we observe an anomalously high velocity feature (7.0-7.5 km/s) within the southeastern flank of Mauna Loa that extends ~40 km south of the volcano's summit. Our model also shows anomalously high velocity materials (6.3-6.8 km/s) in the oceanic crust beneath Kilauea's outer bench. Based on the geometry of their high velocities, we propose that these features represent previously unrecognized intrusive complexes that have influenced the evolution of the two volcanoes. The high velocity feature within Mauna Loa's southeastern flank appears to represent a buried rift zone, either of ancient Mauna Loa, or an older volcano perhaps related to the Ninole Hills. Curiously, at shallow depths (5-9 km below sea level), the high velocities are sharply truncated to the south. However, at greater depths, the anomalously high velocities extend another 20 km into the submarine flank, distinguishing this feature as a once extensive rift zone. The presence of dense, coherent intrusive rock may have anchored Mauna Loa's southeastern flank, such that much of the volcano's recent deformation has occurred along the west flank of Mauna Loa. This massive rift zone may also impede the propagation of Kilauea's southwest rift zone, accounting for its lesser development relative to Kilauea's east rift zone. The velocity highs beneath Kilauea's submarine flank likely represent buried seamounts that might obstruct the seaward migration of volcano's south flank, causing the bench uplift at the toe of flank. These new observations lead us to propose that previously unrecognized intrusive complexes within Mauna Loa and Kilauea have significantly affected the past evolution of these volcanoes in the Island of Hawaii, and are likely responsible for the present patterns of deformation on these active volcanoes.

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

2005-12-01

275

The Massive Compound Cofre de Perote Shield Volcano: a Volcanological Oddity in the Eastern Mexican Volcanic Belt  

NASA Astrophysics Data System (ADS)

Cofre de Perote volcano anchors the northern end of the easternmost of several volcanic chains orthogonal to the E-W trend of the Mexican Volcanic Belt (MVB). Its structure, geochemistry, and volcanic history diverge significantly from that of the large dominantly andesitic stratovolcanoes that have been the major focus of research efforts in the MVB. Andesitic-trachyandesitic to dacitic-trachydacitic effusive activity has predominated at Cofre de Perote, forming a massive low-angle compound shield volcano that dwarfs the more typical smaller shield volcanoes of the central and western MVB. The 4282-m-high volcano overlooking Xalapa, the capital city of the State of Veracruz, has a diameter of about 30 km and rises more than 3000 m above the coastal plain to the east. Repeated edifice collapse has left massive horseshoe-shaped scarps that truncate the eastern side of the edifice. Five major evolutionary stages characterize the growth of this compound volcano: 1) emplacement of a multiple-vent dome complex forming the basal structure of Cofre de Perote around 1.9-1.3 Ma; 2) construction of the basal part of the compound shield volcano from at least two main upper-edifice vents at about 400 ka; 3) effusion of the summit dome-like lavas through multiple vents at ca. 240 ka; 4) eruption of a large number of geochemically diverse, alkaline and calc-alkaline Pleistocene-to-Holocene monogenetic cones (likely related to regional volcanism) through the flanks of the Cofre de Perote edifice; 5) late-stage, large-volume edifice collapse on at least two occasions (ca. 40 ka and ca. 10 ka), producing long-runout debris avalanches that traveled to the east. An undated tephra layer from Cofre de Perote overlies deposits likely of the youngest collapse. Cofre de Perote is one of several volcanoes in the roughly N-S-trending chain that has undergone major edifice collapse. As with Citlaltepetl (Pico de Orizaba) and Las Cumbres volcanoes, Cofre de Perote was constructed at the eastern margin of the Altiplano, with pronounced differential relief and sloping substrate promoting failures toward the Gulf of Mexico coastal plain.

Siebert, L.; Carrasco-Nunez, G.; Diaz-Castellon, R.; Rodriguez, J. L.

2007-12-01

276

A 3D visualization of spatial relationship between geological structure and groundwater chemical profile around Iwate volcano, Japan: based on the ARCGIS 3D Analyst  

NASA Astrophysics Data System (ADS)

We established 3D geological and hydrological model around Iwate volcano to visualize 3D relationships between subsurface structure and groundwater profile. Iwate volcano is a typical polygenetic volcano located in NE Japan, and its body is composed of two stratovolcanoes which have experienced sector collapses several times. Because of this complex structure, groundwater flow around Iwate volcano is strongly restricted by subsurface construction. For example, Kazahaya and Yasuhara (1999) clarified that shallow groundwater in north and east flanks of Iwate volcano are recharged at the mountaintop, and these flow systems are restricted in north and east area because of the structure of younger volcanic body collapse. In addition, Ohwada et al. (2006) found that these shallow groundwater in north and east flanks have relatively high concentration of major chemical components and high 3He/4He ratios. In this study, we succeeded to visualize the spatial relationship between subsurface structure and chemical profile of shallow and deep groundwater system using 3D model on the GIS. In the study region, a number of geological and hydrological datasets, such as boring log data and groundwater chemical profile, were reported. All these paper data are digitized and converted to meshed data on the GIS, and plotted in the three dimensional space to visualize spatial distribution. We also inputted digital elevation model (DEM) around Iwate volcano issued by the Geographical Survey Institute of Japan, and digital geological maps issued by Geological Survey of Japan, AIST. All 3D models are converted into VRML format, and can be used as a versatile dataset on personal computer.

Shibahara, A.; Ohwada, M.; Itoh, J.; Kazahaya, K.; Tsukamoto, H.; Takahashi, M.; Morikawa, N.; Takahashi, H.; Yasuhara, M.; Inamura, A.; Oyama, Y.

2009-12-01

277

Linear volcanic segments in the central Sunda Arc, Indonesia, identified using Hough Transform analysis: Implications for arc lithosphere control upon volcano distribution  

NASA Astrophysics Data System (ADS)

Hough Transform analysis is used as an objective means to constrain volcano distribution in the central Sunda Arc, Indonesia. Most volcanoes in the arc define four en echelon, linear segments, each of 500-700 km length. Javan volcanoes that do not lie on these segments either (i) formed at an early stage in the history of the arc and erupted products that are petrologically and geochemically distinct from typical arc magma, or (ii) lie along other mapped structures. The en echelon distribution of volcanoes in the central Sunda Arc is best explained as originating from two possible sources. First, interaction with the subducting Indo-Australian Plate may induce stress in the arc lithosphere generating pathways for magma to exploit. Second, downward flexure of the arc lithosphere, as a result of mantle flow or loading by the arc, would also establish arc-normal tension towards the base of the lithosphere, where magma is supplied to volcanic systems. To the west and east of the central Sunda Arc deviations from the distribution of long, en echelon, linear segments can be understood as responses to specific stress fields in the arc lithosphere of Sumatra and eastern Nusa Tenggara, respectively. Control of volcano distribution by arc lithosphere explains why there are large variations in the depth from volcanoes to the zone of slab seismicity in the central Sunda Arc, where there is little variation in slab geometry or the rate of plate convergence.

Pacey, Adam; Macpherson, Colin G.; McCaffrey, Ken J. W.

2013-05-01

278

Changbai intraplate volcanism and deep earthquakes in East Asia: a possible link?  

NASA Astrophysics Data System (ADS)

The origin of intraplate volcanoes in Northeast Asia is considered to be associated with upwelling of hot and wet asthenospheric materials in the big mantle wedge above the stagnant Pacific slab in the mantle transition zone. Among these intraplate volcanoes, Changbai is the largest and most active one, and very deep earthquakes (500-650 km depths) in the Pacific slab under East Asia occur ˜300 km to the east of the Changbai volcano. Integrating the findings of geophysical, geochemical and petrologic studies so far, we suggest a link between Changbai volcanism and the deep earthquakes in the Pacific slab. Many large shallow earthquakes occurred in the Pacific Plate in the outer-rise areas close to the oceanic trench, and sea water may enter down to a deep portion of the oceanic lithosphere through the active normal faults which generated the large outer-rise earthquakes. Sea water or fluids may be preserved in the active faults even after the Pacific Plate subducts into the mantle. Many large deep earthquakes are observed that took place in the subducting Pacific slab under the Japan Sea and the East Asian margin. At least some of the large deep earthquakes are caused by the reactivation of faults preserved in the subducting slab, and the fluids preserved in the faults within the slab may cause the observed non-double-couple components of the deep earthquake faulting. Fluids preserved in the slab may be released to the overlying mantle wedge through large deep earthquakes. Because large deep earthquakes occur frequently in the vicinity of the Changbai volcano, many more fluids could be supplied to this volcano than in other areas in Northeast Asia, making Changbai the largest and most active intraplate volcano in the region.

Zhao, Dapeng; Tian, You

2013-11-01

279

Online Courses: Mississippi State University: Earthquakes and Volcanoes  

NSDL National Science Digital Library

Earthquakes and Volcanoes is intended as an investigation into the main processes and products of earthquakes and volcanoes within the framework of plate tectonics. The goals of the course include (1) the application of scientific principles to the study

1900-01-01

280

Volcanoes in the Classroom--an Explosive Learning Experience.  

ERIC Educational Resources Information Center

|Presents a unit on volcanoes for third- and fourth-grade students. Includes demonstrations; video presentations; building a volcano model; and inviting a scientist, preferably a vulcanologist, to share his or her expertise with students. (JRH)|

Thompson, Susan A.; Thompson, Keith S.

1996-01-01

281

Velocity Structure and 2008 Eruptive Seismicity at Okmok Volcano, Alaska  

NASA Astrophysics Data System (ADS)

Okmok Volcano is an active volcanic caldera located on the northeastern portion of Umnak Island in the Aleutian arc, and most recently erupted in 2008. We present updated results from Okmok seismicity between January 2003 and May 2009. The volcanic caldera has been well instrumented with a network of as many as nine short-period and four broadband seismometers, providing good azimuthal coverage. Since the 2008 eruption, the volcano underwent a period of increased seismicity (addition of over 700 earthquakes) making earthquake tomography more feasible. Using a combination of waveform cross-correlation and double-difference seismic tomography, we derive refined Vp and Vs models, relocate hypocenters in them, and carry out resolution tests on the models. We image two low Vp and Vs anomalies: one directly beneath the caldera extending to 4-5 km below sea level and another to the southwest below a well known geothermal area. In addition, we re-calculate focal mechanisms in the updated model for relocated events prior to and during the 2008 eruption. We observe high focal mechanism diversity, including many reverse-faulting events. Finally, we present the 2008 relocation results in the context of satellite ash observations and seismic tremor for a detailed assessment of Okmok's seismic activity during vent formation and stabilization. The earthquakes accompanying the onset of the eruption occurred in a vertical lineation at about 4 km below sea level to the northwest of Cone D, directly below the site of the new vent, and spread slightly towards the east and west over the next few hours. Four hours after the first earthquakes, a sequence of events began near sea level. As the eruption progressed, events expanded both to greater depths and outward throughout the caldera volume, mainly westward in the direction of Cone A. The shallower and deeper groups of events seen in the early eruption remained separated by a nearly aseismic region.

Ohlendorf, S. J.; Thurber, C. H.; Prejean, S. G.

2010-12-01

282

A new volcano-structural map of the Virunga Volcanic Province, D.R.Congo and Rwanda  

NASA Astrophysics Data System (ADS)

The Virunga Volcanic Province (VVP) is situated within the Western branch of the East African Rift system at the boundary of D.R.Congo, Rwanda and Uganda. The Western VVP comprises two active volcanoes, Nyamulagira and Nyiragongo. Six supposedly historically inactive volcanoes are present in the Central and Eastern VVP. Nyamulagira is recently the most active volcano on the African continent, with 30 eruptions since 1900, while Nyiragongo hosts a semi-permanent lava lake in its crater and fed a catastrophic lava flow in 2002. Additionally, numerous volcanic vents, fissures and cones are scattered on and around the main edifices. Except for geological maps from the colonial times and limited studies of historical eruptions, little is known about the volcano-tectonic structure and long term volcanic history of the VVP. A new Digital Elevation Model (TanDEM-X) with a resolution of 5 m, combined with SPOT and SAR images served as a base for the development of a new volcano-structural map for the entire VVP. A GIS data base was developed including the location of eruptive cones and fissures and the distribution of lava flows. The boundaries of historic and pre-historic lava flows and pyroclastic cones were traced from from interpretation of topographic and multispectral remote sensing data and re-analysis of ancient geological maps.Larger-scale lineaments interpreted as potential volcano-tectonic structures were also systematically mapped. All previously geochemically analyzed samples were localized. This GIS-based volcano-structural map will serve as a base for the quantitative characterization of recent and historic volcanic eruption products, such as pyroclastic cones and lava flows, of Nyamulagira and Nyiragongo, as well as for the assessment of potential Holocene activity in the Central and Eastern VVP. The orientation of feeder dykes inferred from cone alignments and morphology is used to identify the main volcanic structures and infer the locally dominant stress field. Geochemistry and eruption characteristics of the 1957 Mugogo eruption to the North of Visoke Volcano, Central Virunga, is used to illustrate the importance of the analysis of historic volcanic activity in the Central and Eastern region of the VVP. The ultimate aim served by the resulting volcano-structural map and data-base is the evaluation of potential future eruption scenarios and the derivation of the spatial distribution of eruption probability.

Poppe, Sam; Smets, Benoît; Albino, Fabien; Kervyn, François; Kervyn, Matthieu

2013-04-01

283

Kizimen volcano basaltic andesites: petrography and magmatic inclusions  

NASA Astrophysics Data System (ADS)

Kizimen volcano has unique geological position because it is located just between global active volcanic structures as East Volcanic Front (EVF) and Central Kamchatka Depression (CKD), but it still remains one of the pure studied volcanoes of Kamchatka. Several samples of basaltic andesites (53-54 wt.{%} SiO2) was studied. Microprobe analyses of olivine phenocryst cores show composition from Fo79 to Fo72. Olivine rims are strongly zoned and have Fe-rich composition (from Fo72 to Fo62). Phenocrysts of clinopyroxene are slightly zoned (En44 - 38 Fs15 - 10 Wo47 - 39). Orthopyroxene phenocrysts have nearly constant composition (En64 - 63 Fs35 - 34 Wo2 - 1). Apatite inclusions and silica-rich melt inclusions in orthopyroxene argues for their late crystallization. Plagioclase represented by two generations: An96 - 93 to An93 - 87 and An65 - 62 to An70 - 67. At the same time clinopyroxene+magnetite aggregates that have early amphibole morphology was founded. These aggregates have been produced by amphibole breakdown during magma ascending. Ferrous oxide phases have narrow range of compositions corresponding to Ti-magnetite. Solid inclusions of plagioclase in olivine show clear correlation between their compositions. High-Ca plagioclase (An97 - 92) coexists with relatively high-Mg olivine (Fo79 - 75). Such assemblage is very similar to allivalites (Ol-Pl cumulates of the eucritic composition). This assemblage has the most magnesian olivine for Kizimen volcano and probably is the earliest assemblage, known for these rocks. Initial magma composition of studied eruption was calculated using melt inclusion compositions from olivine of earliest Ol-Pl assemblage. Partially crystallized melt inclusions were heated experimentally, quenched, exposed to the grain surface and their compositions were measured. Reconstructed melts are corresponding to basalt composition (46-47 wt.{%} SiO2) and falls into the field of middle-K series. Temperatures of olivine crystallization are near 1110± 10r{} T. According to Frolova et al. (2001) allivalite assemblages were known only for low-K island arc tholeitic series and discovering of the earliest Ol-Pl assemblage can be applied for expanding of boundaries of allivalite-bearing rock compositions from low-K series to middle-K one.

Trusov, S.; Pletchov, P.; Ivanov, B.

2003-04-01

284

Syn and posteruptive hazards of maar–diatreme volcanoes  

Microsoft Academic Search

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

Volker Lorenz

2007-01-01

285

Versatile Time-Lapse Camera System Developed by the Hawaiian Volcano Observatory for Use at Kilauea Volcano, Hawaii.  

National Technical Information Service (NTIS)

Volcanoes can be difficult to study up close. Because it may be days, weeks, or even years between important events, direct observation is often impractical. In addition, volcanoes are often inaccessible due to their remote location and (or) harsh environ...

R. P. Hoblitt T. R. Orr

2008-01-01

286

Mount St. Helens volcano: Recent and future behavior  

USGS Publications Warehouse

Mount St. Helens volcano in southern Washington has erupted many times during the last 4000 years, usually after brief dormant periods. This behavior pattern suggests that the volcano, last active in 1857, will erupt again - perhaps within the next few decades. Potential volcanic hazards of several kinds should be considered in planning for land use near the volcano.

Crandell, D. R.; Mullineaux, D. R.; Rubin, M.

1975-01-01

287

Encapsulation of Parallelism in the Volcano Query Processing System  

Microsoft Academic Search

Volcano 1s a new dataflow query processmg system we have developed for database systems research and educauon The umform Interface between operators makes Volcano extenstble by new operators All operators are designed and coded as d they were meant for a smgle-process system only When attemptmg to parallelue Volcano, we had to choose between two models of parallchzatlon, called here

Goetz Graefe

1990-01-01

288

Overview of the 1990–1995 eruption at Unzen Volcano  

Microsoft Academic Search

Following 198 years of dormancy, a small phreatic eruption started at the summit of Unzen Volcano (Mt. Fugen) in November 1990. A swarm of volcano-tectonic (VT) earthquakes had begun below the western flank of the volcano a year before this eruption, and isolated tremor occurred below the summit shortly before it. The focus of VT events had migrated eastward to

Setsuya Nakada; Hiroshi Shimizu; Kazuya Ohta

1999-01-01

289

Satellite monitoring of remote volcanoes improves study efforts in Alaska  

Microsoft Academic Search

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

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

1998-01-01

290

Managing volcanic unrest: The mobile volcano fast response system  

Microsoft Academic Search

A mobile volcano fast response system (VFRS) that can be deployed on a volcano in case of volcanic unrest is currently under development in Germany. The main goal of the project called Exupery, which is funded by the BMBF (German ministry for the education and research) project Geotech-nologien, is to develop the core of a mobile volcano fast response system,

Matthias Hort; K. Zaksek

2008-01-01

291

Predicting the Timing and Location of the next Hawaiian Volcano  

ERIC Educational Resources Information Center

The wealth of geologic data on Hawaiian volcanoes makes them ideal for study by middle school students. In this paper the authors use existing data on the age and location of Hawaiian volcanoes to predict the location of the next Hawaiian volcano and when it will begin to grow on the floor of the Pacific Ocean. An inquiry-based lesson is also…

Russo, Joseph; Mattox, Stephen; Kildau, Nicole

2010-01-01

292

Predicting the Timing and Location of the next Hawaiian Volcano  

ERIC Educational Resources Information Center

|The wealth of geologic data on Hawaiian volcanoes makes them ideal for study by middle school students. In this paper the authors use existing data on the age and location of Hawaiian volcanoes to predict the location of the next Hawaiian volcano and when it will begin to grow on the floor of the Pacific Ocean. An inquiry-based lesson is also…

Russo, Joseph; Mattox, Stephen; Kildau, Nicole

2010-01-01

293

Living with Volcanoes: Year Eleven Teaching Resource Unit.  

ERIC Educational Resources Information Center

|Presents a unit on volcanoes and experiences with volcanoes that helps students develop geography skills. Focuses on four volcanoes: (1) Rangitoto Island; (2) Lake Pupuke; (3) Mount Smart; and (4) One Tree Hill. Includes an answer sheet and resources to use with the unit. (CMK)|

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

2000-01-01

294

Lab using Volcano Scenarios: Hazard Maps and Communicating Risk  

NSDL National Science Digital Library

This is a lab activity in which small groups of students work with maps, rocks, photographs of volcanic deposits, and textual data to construct a hazard map and a risk communication plan for a specific volcano. Each group is assigned a "volcano scenario," which is based on real volcanoes.

Srogi, Leeann

295

Active Volcano Monitoring using a Space-based Hyperspectral Imager  

Microsoft Academic Search

Active volcanoes occur on every continent, often in close proximity to heavily populated areas. While ground-based studies are essential for scientific research and disaster mitigation, remote sensing from space can provide rapid and continuous monitoring of active and potentially active volcanoes [Ramsey and Flynn, 2004]. In this paper, we report on hyperspectral measurements of Kilauea volcano, Hawaii. Hyperspectral images obtained

J. J. Cipar; R. Dunn; T. Cooley

2010-01-01

296

How Do Volcanoes Affect Human Life? Integrated Unit.  

ERIC Educational Resources Information Center

|This packet contains a unit on teaching about volcanoes. The following question is addressed: How do volcanoes affect human life? The unit covers approximately three weeks of instruction and strives to present volcanoes in an holistic form. The five subject areas of art, language arts, mathematics, science, and social studies are integrated into…

Dayton, Rebecca; Edwards, Carrie; Sisler, Michelle

297

Effects of volcano topography on seismic broad-band waveforms  

Microsoft Academic Search

Volcano seismology often deals with rather shallow seismic sources and seismic stations deployed in their near field. The complex stratigraphy on volcanoes and near-field source effects have a strong impact on the seismic wavefield, complicating the interpretation techniques that are usually employed in earthquake seismology. In addition, as most volcanoes have a pronounced topography, the interference of the seismic wavefield

Jürgen Neuberg; Tim Pointer

2000-01-01

298

Distribution of Io's volcanoes: Possible influence on spin axis  

Microsoft Academic Search

We examine the potential effect of volcano distribution on the orientation of Io's spin axis. Volcanoes dominate Io's surface and the massive outpourings documented in short intervals could cause instability in Io's rotation and a corresponding reorientation of its spin axis. Currently, the volcanoes and mountains exhibit a complementary distribution, with the maximum principal axis for the set of 351

Paul R. Stoddard; Donna M. Jurdy

2002-01-01

299

Tsunamis Generated by Eruptions from Mount St. Augustine Volcano, Alaska  

Microsoft Academic Search

During an eruption of the Alaskan volcano Mount St. Augustine in the spring of 1986, there was concern about the possibility that a tsunami might be generated by the collapse of a portion of the volcano into the shallow water of Cook Inlet. A similar edifice collapse of the volcano and ensuing sea wave occurred during an eruption in 1883.

Jurgen Kienle; Zygmunt Kowalik; T. S. Murty

1987-01-01

300

Ongoing inflation and magma accumulation of Grimsvotn subglacial volcano, Iceland  

Microsoft Academic Search

The sub-glacial Grimsvotn volcano, one of Iceland's most active volcanoes, erupted in 1983, 1998 and 2004. Since 1998, annual GPS measurements have been conducted at the only available nunatak at the volcano, located on the rim of its caldera. A clear pattern of deformation is observed that can be attributed to magma inflow and outflow, uplift due to glacial thinning,

E. C. Sturkell; F. Sigmundsson; P. Einarsson; F. Jouanne; H. Geirsson; B. G. Ofeigsson; T. Villemin; F. Palsson

2008-01-01

301

Glacial fragmentation induced by eruptive activity: Popocatépetl Volcano (México)  

Microsoft Academic Search

Ice-volcano interactions at volcanoes depend on eruptive behavior, glacier characteristics and time scales. High- intensity eruptions occurred in a short span of time can provoke dramatic glacial changes whilst intermittent eruptive behavior of variable intensity over years can generate gradual glacial changes. Popocatépetl volcano hosted a small glacial area when it started to erupt in December 1994. Over 12 years

P. Julio-Miranda; H. Delgado-Granados

2007-01-01

302

A late pleistocene to recent rhyodacite-trachybasalt-basaltic latite volcanic association in north-east Papua  

Microsoft Academic Search

The Managalase Plateau in north-east Papua is a faultbounded block of fractured basement metabasalt and basic plutonic rock\\u000a overlain in the east by some thirty small volcanic centres of late Pleistocene to Recent age which include rhyodacite ash\\u000a cones and trachybasalt and basaltic latite lava. To the north andesitic strato-volcanoes of Pleistocene and Recent age occur\\u000a along the margin of

B. P. Ruxton

1966-01-01

303

Swift snowmelt and floods (lahars) caused by great pyroclastic surge at Mount St Helens volcano, Washington, 18 May 1980  

NASA Astrophysics Data System (ADS)

The initial explosions at Mount St. Helens, Washington, on the moring of 18 May 1980 developed into a huge pyroclastic surge that generated catastrophic floods off the east and west flanks of the volcano. Near-source surge deposits on the east and west were lithic, sorted, lacking in accretionary lapilli and vesiculated ash, not plastered against upright obstacles, and hot enough to char wood — all attributes of dry pyroclastic surge. Material deposited at the surge base on steep slopes near the volcano transformed into high-concentration lithic pyroclastic flows whose deposits contain charred wood and other features indicating that these flows were hot and dry. Stratigraphy shows that even the tail of the surge had passed the east and west volcano flanks before the geomorphically distinct floods (lahars) arrived. This field evidence undermines hypotheses that the turbulent surge was itself wet and that its heavy components segregated out to transform directly into lahars. Nor is there evidence that meters-thick snow-slab avalanches intimately mixed with the surge to form the floods. The floods must have instead originated by swift snowmelt at the base of a hot and relatively dry turbulent surge. Impacting hot pyroclasts probably transferred downslope momentum to the snow surface and churned snow grains into the surge base. Melting snow and accumulating hot surge debris may have moved initially as thousands of small thin slushflows. As these flows removed the surface snow and pyroclasts, newly uncovered snow was partly melted by the turbulent surge base; this and accumulating hot surge debris in turn began flowing, a self-sustaining process feeding the initial flows. The flows thus grew swiftly over tens of seconds and united downslope into great slushy ejecta-laden sheetfloods. Gravity accelerated the floods to more than 100 km/h as they swept down and off the volcano flanks while the snow component melted to form great debris-rich floods (lahars) channeled into valleys.

Waitt, Richard B.

1989-12-01

304

Swift snowmelt and floods (lahars) caused by great pyroclastic surge at Mount St Helens volcano, Washington, 18 May 1980  

USGS Publications Warehouse

The initial explosions at Mount St. Helens, Washington, on the moring of 18 May 1980 developed into a huge pyroclastic surge that generated catastrophic floods off the east and west flanks of the volcano. Near-source surge deposits on the east and west were lithic, sorted, lacking in accretionary lapilli and vesiculated ash, not plastered against upright obstacles, and hot enough to char wood - all attributes of dry pyroclastic surge. Material deposited at the surge base on steep slopes near the volcano transformed into high-concentration lithic pyroclastic flows whose deposits contain charred wood and other features indicating that these flows were hot and dry. Stratigraphy shows that even the tail of the surge had passed the east and west volcano flanks before the geomorphically distinct floods (lahars) arrived. This field evidence undermines hypotheses that the turbulent surge was itself wet and that its heavy components segregated out to transform directly into lahars. Nor is there evidence that meters-thick snow-slab avalanches intimately mixed with the surge to form the floods. The floods must have instead originated by swift snowmelt at the base of a hot and relatively dry turbulent surge. Impacting hot pyroclasts probably transferred downslope momentum to the snow surface and churned snow grains into the surge base. Melting snow and accumulating hot surge debris may have moved initially as thousands of small thin slushflows. As these flows removed the surface snow and pyroclasts, newly uncovered snow was partly melted by the turbulent surge base; this and accumulating hot surge debris in turn began flowing, a self-sustaining process feeding the initial flows. The flows thus grew swiftly over tens of seconds and united downslope into great slushy ejecta-laden sheetfloods. Gravity accelerated the floods to more than 100 km/h as they swept down and off the volcano flanks while the snow component melted to form great debris-rich floods (lahars) channeled into valleys. ?? 1989 Springer-Verlag.

Waitt, R. B.

1989-01-01

305

Volcanoes: Can We Predict Volcanic Eruptions?  

NSDL National Science Digital Library

This volcanoes site provides information about volcanoes as well as a classroom activity. There are video clips which show some of the features discussed, such as types of lava and eruptive styles. Topics covered by the text include how rocks melt, where and why volcanoes occur (plate tectonics), hot spots, volcanic hazards, forecasting eruptions and coping with risk. The classroom exercise involves deciding whether or not to build developments near volcanic features. Students are provided with maps, geologic data and helpful hints. Once the decision is made, students must defend their decisions at a press conference, complete with reporter's questions and a printout of the resulting news stories. This exercise illustrates the connection between science and public policy.

2002-06-10

306

The Unexpected Awakening of Chaitén Volcano, Chile  

NASA Astrophysics Data System (ADS)

On 2 May 2008, a large eruption began unexpectedly at the inconspicuous Chaitén volcano in Chile's southern volcanic zone. Ash columns abruptly jetted from the volcano into the stratosphere, followed by lava dome effusion and continuous low-altitude ash plumes [Lara, 2009]. Apocalyptic photographs of eruption plumes suffused with lightning were circulated globally. Effects of the eruption were extensive. Floods and lahars inundated the town of Chaitén, and its 4625 residents were evacuated. Widespread ashfall and drifting ash clouds closed regional airports and cancelled hundreds of domestic flights in Argentina and Chile and numerous international flights [Guffanti et al., 2008]. Ash heavily affected the aquaculture industry in the nearby Gulf of Corcovado, curtailed ecotourism, and closed regional nature preserves. To better prepare for future eruptions, the Chilean government has boosted support for monitoring and hazard mitigation at Chaitén and at 42 other highly hazardous, active volcanoes in Chile.

Carn, Simon A.; Pallister, John S.; Lara, Luis; Ewert, John W.; Watt, Sebastian; Prata, Alfred J.; Thomas, Ronald J.; Villarosa, Gustavo

2009-06-01

307

Submarine Volcanoes in Arctic Ocean Surprise Scientists  

NSDL National Science Digital Library

Until now, geoscientists believed that spreading ridges under the Arctic Ocean were too slow-spreading and cool to vent molten rock. An article published this month in Nature details sonar data revealing two young volcanoes under Arctic waters. Dr. Marago H. Edwards of the University of Hawaii led the exploration team in which civilian scientists worked in cooperation with the Navy, using a nuclear submarine to take sonar readings of the ocean floor. A submarine was employed because the ice cover makes the Arctic seafloor unviewable by satellites and difficult for ships bearing seismic instruments to navigate. The two volcanoes were found at the Gakkel Ridge, the Earth's slowest spreading mid-ocean ridge. During August and September of 2001, Russian icebreakers and Mir submersibles will be employed to investigate the volcanoes, taking rock samples and looking for organisms living at the volcanic vents. This week's In the News takes a closer look at this discovery.

Sanders, Hilary C.

2001-01-01

308

Mafic Plinian volcanism and ignimbrite emplacement at Tofua volcano, Tonga  

NASA Astrophysics Data System (ADS)

Tofua Island is the largest emergent mafic volcano within the Tofua arc, Tonga, southwest Pacific. The volcano is dominated by a distinctive caldera averaging 4 km in diameter, containing a freshwater lake in the south and east. The latest paroxysmal (VEI 5-6) explosive volcanism includes two phases of activity, each emplacing a high-grade ignimbrite. The products are basaltic andesites with between 52 wt.% and 57 wt.% SiO2. The first and largest eruption caused the inward collapse of a stratovolcano and produced the `Tofua' ignimbrite and a sub-circular caldera located slightly northwest of the island's centre. This ignimbrite was deposited in a radial fashion over the entire island, with associated Plinian fall deposits up to 0.5 m thick on islands >40 km away. Common sub-rounded and frequently cauliform scoria bombs throughout the ignimbrite attest to a small degree of marginal magma-water interaction. The common intense welding of the coarse-grained eruptive products, however, suggests that the majority of the erupted magma was hot, water-undersaturated and supplied at high rates with moderately low fragmentation efficiency and low levels of interaction with external water. We propose that the development of a water-saturated dacite body at shallow (<6 km) depth resulted in failure of the chamber roof to cause sudden evacuation of material, producing a Plinian eruption column. Following a brief period of quiescence, large-scale faulting in the southeast of the island produced a second explosive phase believed to result from recharge of a chemically distinct magma depleted in incompatible elements. This similar, but smaller eruption, emplaced the `Hokula' Ignimbrite sheet in the northeast of the island. A maximum total volume of 8 km3 of juvenile material was erupted by these events. The main eruption column is estimated to have reached a height of ˜12 km, and to have produced a major atmospheric injection of gas, and tephra recorded in the widespread series of fall deposits found on coral islands 40-80 km to the east (in the direction of regional upper-tropospheric winds). Radiocarbon dating of charcoal below the Tofua ignimbrite and organic material below the related fall units imply this eruption sequence occurred post 1,000 years BP. We estimate an eruption magnitude of 2.24 × 1013 kg, sulphur release of 12 Tg and tentatively assign this eruption to the AD 1030 volcanic sulphate spike recorded in Antarctic ice sheet records.

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

2011-11-01

309

Airborne laser swath mapping of the summit of Erebus volcano, Antarctica: Applications to geological mapping of a volcano  

Microsoft Academic Search

The lidar observations reported here have provided the first high precision topographic data on the active craters of Erebus volcano, Antarctica. Digital elevation data are invaluable for geomorphic analysis of volcanoes especially when combined with methods to automatically extract landscape features. The data are indispensable for studying eruptive events and volcano-tectonic processes. Airborne laser scanning or lidar is a rapidly

Bea Csatho; Toni Schenk; Philip Kyle; Terry Wilson; William B. Krabill

2008-01-01

310

Locating volcano-seismic signals in the presence of rough topography: wave simulations on Arenal volcano, Costa Rica  

Microsoft Academic Search

Quantifying the scattering effects of pronounced volcano topography on the seismic wavefield is an important component in locating and interpreting volcano seismic sources. In this study, we perform seismic wave simulations to quantify the scattering generated by a 3-D digital elevation map and 1-D velocity model of Arenal volcano, Costa Rica. Full waveform synthetic seismograms were generated using a 3-D

J. P. Métaxian; G. S. O'Brien; C. J. Bean; B. Valette; M. Mora

2009-01-01

311

The New USGS Volcano Hazards Program Web Site  

NASA Astrophysics Data System (ADS)

The U.S. Geological Survey's (USGS) Volcano Hazard Program (VHP) has launched a revised web site that uses a map-based interface to display hazards information for U.S. volcanoes. The web site is focused on better communication of hazards and background volcano information to our varied user groups by reorganizing content based on user needs and improving data display. The Home Page provides a synoptic view of the activity level of all volcanoes for which updates are written using a custom Google® Map. Updates are accessible by clicking on one of the map icons or clicking on the volcano of interest in the adjacent color-coded list of updates. The new navigation provides rapid access to volcanic activity information, background volcano information, images and publications, volcanic hazards, information about VHP, and the USGS volcano observatories. The Volcanic Activity section was tailored for emergency managers but provides information for all our user groups. It includes a Google® Map of the volcanoes we monitor, an Elevated Activity Page, a general status page, information about our Volcano Alert Levels and Aviation Color Codes, monitoring information, and links to monitoring data from VHP's volcano observatories: Alaska Volcano Observatory (AVO), Cascades Volcano Observatory (CVO), Long Valley Observatory (LVO), Hawaiian Volcano Observatory (HVO), and Yellowstone Volcano Observatory (YVO). The YVO web site was the first to move to the new navigation system and we are working on integrating the Long Valley Observatory web site next. We are excited to continue to implement new geospatial technologies to better display our hazards and supporting volcano information.

Venezky, D. Y.; Graham, S. E.; Parker, T. J.; Snedigar, S. F.

2008-12-01

312

(Nearly) Silent Earthquakes on Volcanoes  

NASA Astrophysics Data System (ADS)

Slow, or silent, earthquakes are not restricted to plate boundary zones. Cervellli et al. (Nature, 2002) discovered a slow slip event on Kilauea Volcano, Hawaii that occurred in November 2000. This event, with a moment magnitude of ~ 5.7, had a duration of roughly 36 hours, and slipped a subhorizontal thrust fault at a depth of ~ 5 km. Since that publication, four additional slow earthquakes have been discovered using the Kilauea continuous GPS network. These events are nearly identical to the 2000 event, in pattern of deformation, amplitude, and duration. Inversions for source geometry using simulated annealing place the causative fault in precisely the same location as the 2000 event. In comparison to slow slip events in subduction zones in Cascadia, Japan, Mexico, and elsewhere, the volcanic slow slip events are smaller Mw 5.7 compared to Mw 7 for the larger subduction events, shorter in duration, 1-2 days compared to several years for the Tokai slow slip event, shallower, 5 km as opposed to 30-50 km for most subduction events, and have faster slip rates, ~ 20 m/yr compared to ~ 1 m/yr in Cascadia. The lateral position of the imaged slow event dislocations is directly seaward (updip?) of a prominent, and persistent band of microseismicity on Kilauea. Remarkably, there is a clear increase in seismicity within this region accompanying the slow slip events, although the events (M<3) are far too small to account for the GPS displacements. The temporal and spatial association suggests that the earthquakes are triggered by the otherwise silent slip. We are currently investigating whether non-volcanic tremor also accompanies these slip events.

Segall, P.; Desmarais, E.; Miklus, A.; Okubo, P.

2005-12-01

313

A dynamic balance between magma supply and eruption rate at Kilauea volcano, Hawaii  

USGS Publications Warehouse

The dynamic balance between magma supply and vent output at Kilauea volcano is used to estimate both the volume of magma stored within Kilauea volcano and its magma supply rate. Throughout most of 1991 a linear decline in volume flux from the Kupaianaha vent on Kilauea's east rift zone was associated with a parabolic variation in the elevation of Kilauea's summit as vent output initially exceeded then lagged behind the magma supply to the volcano. The correspondence between summit elevation and tilt established with over 30 years of data provided daily estimates of summit elevation in terms of summit tilt. The minimum in the parabolic variation in summit tilt and elevation (or zero elevation change) occurs when the magma supply to the reservoir from below the volcano equals the magma output from the reservoir to the surface, so that the magma supply rate is given by vent flux on that day. The measurements of vent flux and tilt establish that the magma supply rate to Kilauea volcano on June 19, 1991, was 217,000 ?? 10,000 m3/d (or 0.079 ?? 0.004 km3/yr). This is close to the average eruptive rate of 0.08 km3/yr between 1958 and 1984. In addition, the predictable response of summit elevation and tilt to each east rift zone eruption near Puu Oo since 1983 shows that summit deformation is also a measure of magma reservoir pressure. Given this, the correlation between the elevation of the Puu Oo lava lake (4 km uprift of Kupaianaha and 18 km from the summit) and summit tilt provides an estimate for magma pressure changes corresponding to summit tilt changes. The ratio of the change in volume to the change in reservoir pressure (dV/dP) during vent activity may be determined by dividing the ratio of volume erupted to change in summit tilt (dV/dtilt) by the ratio of pressure change to change in summit tilt (dP/dtilt). This measure of dV/dP, when combined with laboratory measurements of the bulk modulus of tholeitic melt, provides an estimate of 240 ?? 50 km3 for the volume of Kilauea's magma reservoir. This estimate is much larger than traditional estimates but consistent with seismic tomographic imaging and geophysical modeling of Kilauea's magma system. Copyright 1997 by the American Geophysical Union.

Denlinger, R. P.

1997-01-01

314

In Brief: Russian volcano warnings reinstated  

NASA Astrophysics Data System (ADS)

The Kamchatka Volcanic Eruption Response Team (KVERT) is again issuing warnings for aviation during periods of activity by Kamchatkan volcanoes. KVERT had stopped issuing warnings on 1 March due to a loss of funding by the Federal Unitary Enterprise State Air Traffic Management Corporation of Russia (see Eos 88(12), 2007). The funding for this work has now resumed. KVERT is a collaborative project of scientists from the Russian Institute of Volcanology and Seismology, the Kamchatka Experimental and Methodical Seismological Department, and the Alaska Volcano Observatory.

Zielinski, Sarah

2007-04-01

315

Tracking Pyroclastic Flows at Soufrière Hills Volcano  

NASA Astrophysics Data System (ADS)

Explosive volcanic eruptions typically show a huge column of ash and debris ejected into the stratosphere, crackling with lightning. Yet equally hazardous are the fast moving avalanches of hot gas and rock that can rush down the volcano's flanks at speeds approaching 280 kilometers per hour. Called pyroclastic flows, these surges can reach temperatures of 400°C. Fast currents and hot temperatures can quickly overwhelm communities living in the shadow of volcanoes, such as what happened to Pompeii and Herculaneum after the 79 C.E. eruption of Italy's Mount Vesuvius or to Saint-Pierre after Martinique's Mount Pelée erupted in 1902.

Ripepe, Maurizio; De Angelis, Silvio; Lacanna, Giorgio; Poggi, Pasquale; Williams, Carlisle; Marchetti, Emanuele; Delle Donne, Dario; Ulivieri, Giacomo

2009-07-01

316

Gas analyses from the Pu'u O'o eruption in 1985, Kilauea volcano, Hawaii  

USGS Publications Warehouse

Volcanic gas samples were collected from July to November 1985 from a lava pond in the main eruptive conduit of Pu'u O'o from a 2-week-long fissure eruption and from a minor flank eruption of Pu'u O'o. The molecular composition of these gases is consistent with thermodynamic equilibrium at a temperature slightly less than measured lava temperatures. Comparison of these samples with previous gas samples shows that the composition of volatiles in the magma has remained constant over the 3-year course of this episodic east rift eruption of Kilauea volcano. The uniformly carbon depleted nature of these gases is consistent with previous suggestions that all east rift eruptive magmas degas during prior storage in the shallow summit reservoir of Kilauea. Minor compositional variations within these gas collections are attributed to the kinetics of the magma degassing process. ?? 1986 Springer-Verlag.

Greenland, L. P.

1986-01-01

317

Hawaii Volcanoes and Volcanics - Maps and Graphics, etc.  

NSDL National Science Digital Library

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

318

Mount Dutton volcano, Alaska: Aleutian arc analog to Unzen volcano, Japan  

Microsoft Academic Search

Holocene eruptions from Mount Dutton, a small Late Quaternary volcano near the tip of the Alaska Peninsula, bear strong physical and petrologic similarities to the 1990–1995 Unzen Fugendake eruption in Japan. The volcano had a protracted phase of effusive calcalkaline andesitic (54–59 wt.% SiO2) cone-building in the late Pleistocene followed by an abrupt switch to more silicic (?65 wt.% SiO2)

T. P Miller; D. G Chertkoff; J. C Eichelberger; M. L Coombs

1999-01-01

319

Digital data set of volcano hazards for active Cascade Volcanos, Washington  

USGS Publications Warehouse

Scientists at the Cascade Volcano Observatory have completed hazard assessments for the five active volcanos in Washington. The five studies included Mount Adams (Scott and others, 1995), Mount Baker (Gardner and others, 1995), Glacier Peak (Waitt and others, 1995), Mount Rainier (Hoblitt and others, 1995) and Mount St. Helens (Wolfe and Pierson, 1995). Twenty Geographic Information System (GIS) data sets have been created that represent the hazard information from the assessments. The twenty data sets have individual Open File part numbers and titles

Schilling, Steve P.

1996-01-01

320

GlobVolcano pre-operational services for global monitoring active volcanoes  

Microsoft Academic Search

The GlobVolcano project (2007-2010) is part of the Data User Element programme of the European Space Agency (ESA). The project aims at demonstrating Earth Observation (EO) based integrated services to support the Volcano Observatories and other mandate users (e.g. Civil Protection) in their monitoring activities. The information services are assessed in close cooperation with the user organizations for different types

Lucia Tampellini; Raffaella Ratti; Sven Borgström; Frank Martin Seifert; Aline Peltier; Edouard Kaminski; Marco Bianchi; Wendy Branson; Fabrizio Ferrucci; Barbara Hirn; Paul van der Voet; J. van Geffen

2010-01-01

321

Continuous deflation of the askja volcano, iceland  

NASA Astrophysics Data System (ADS)

The Askja volcano, located on the spreading plate boundary in north Iceland, consists of nested calderas, the latest formed in an eruption in 1875. Several small eruptions have occurred since 1875, with the most recent in 1961. To measure the crustal deformation in Askja, GPS, InSAR and levelling techniques are used. These methods are independent from each other and all give a consistent picture of subsidence in the centre of the main caldera in recent years. Levelling has been conducted annually from 1983, and also in the 1966-1972 period. The first major GPS campaign at Askja, was conducted in 1993 and repeated in 1998. The GPS results show subsidence. The deformation signal obtained from the GPS and the levelling (tilt) measurements broadly fits a "Mogi" model source of pressure decrease near the centre of the caldera at a depth of 3.5 km. However, a wider deformation field reaching about 10 km out from the centre of the main caldera is suggested. The wider deformation field overlaps with the plate-spreading deformation. The plate boundary which is roughly north-south trending affects the areas to the east and west mostly, but the deformation field is not influenced significantly in north and south directions. This wider field indicates a possible deeper source. An InSAR image spanning from 1992 to 1998 shows a concentric deformation pattern, associated with subsidence in the centre of the main caldera, mostly consistent with GPS and tilt results. The two GPS-points closest to the subsidence centre have been measured annually in recent years, and the measurements indicate a slight decrease in the subsidence rate from 1993 to 2002. This rate of decrease is more obvious in the levelling data, as these data span the period 1983 to 2002. Using the "Mogi" point source location obtained from GPS and InSAR, and assuming it has been at the same place since the mid seventies, it is possible to calculate the total amount of subsidence by comparing the levelling result from 1972 and 2002. The vertical displacement is -1.9 meters in the centre for the time period 1972 to 2002. Likely processes responsible for a subsurface volume reduction in volcanic area include volume contraction and /or mass transport. Processes such as eruptions, lateral dyke injections, crystallisation and draining of a deeper-seated magma reservoir into the rift zone will result in a volume reduction. Neither eruptions nor shallow dyke injections are known during this period, and earthquake activity has been low. We suggest that magma solidification is an important process to explain some of the long-term subsidence in Askja, but regional deformation and drainage of magma into the rift zone contribute as well.

Sturkell, E.; Pagli, C.; Sigmundsson, F.

2003-04-01

322

Englacial tephrostratigraphy of Erebus volcano, Antarctica  

Microsoft Academic Search

A tephrostratigraphy for Erebus volcano is presented, including tephra composition, stratigraphy, and eruption mechanism. Tephra from Erebus were collected from glacial ice and firn. Scanning electron microscope images of the ash morphologies help determine their eruption mechanisms The tephra resulted mainly from phreatomagmatic eruptions with fewer from Strombolian eruptions. Tephra having mixed phreatomagmatic–Strombolian origins are common. Two tephra deposited on

C. J. Harpel; P. R. Kyle; N. W. Dunbar

2008-01-01

323

Lava Layering: Making and Mapping a Volcano  

NSDL National Science Digital Library

In this activity, learners discover how geologists use stratigraphy, the study of layered rock, to understand the sequence of geological events. Learners use baking soda, vinegar, and different colored play dough to model how "lava" flows. This lesson plan includes background information, play dough recipes, student worksheets, and an optional volcano mapping extension activity.

Nasa

2012-06-26

324

Monogenetic volcanoes of the terrestrial planets  

Microsoft Academic Search

Monogenetic volcanic activity has produced cinder cones and small shield volcanoes on the earth, moon, and Mars. Extraterrestrial cinder cones have median volumes only 25% as large as average terrestrial cinder cones, implying that their magma chambers are smaller and shallower (1 km depth vs 3 km). Ejection velocities for lunar and Martian cinder cones range from 20 to 70

C. A. Wood

1979-01-01

325

Maar-diatreme volcanoes: A review  

Microsoft Academic Search

Maar-diatreme volcanoes are produced by explosive eruptions that cut deeply into the country rock. A maar is the crater cut into the ground and surrounded by an ejecta ring, while the diatreme structure continues downward and encloses diatreme and root zone deposits. Here we attempt an evenhanded review of maar-diatreme volcanology that extends from mafic to kimberlitic varieties, and from

J. D. L. White; P.-S. Ross

2011-01-01

326

Volcano Hazards Fact Sheet: Volcanic Gas  

NSDL National Science Digital Library

This fact sheet provides an overview of the gases emitted by volcanoes, which consist mostly of water vapor, carbon dioxide, and sulfur dioxide. Topics include reasons for studying them, potential hazards, methods for studying them, and some facts about the gases emitted by the eruption of Mount St. Helens. A downloadable, printable version is available.

327

Acoustic Noise from Volcanoes: Theory and Experiment  

Microsoft Academic Search

The paper discusses some theoretical aspects of acoustic investigation of volcanoes and describes a field experiment involving the recording, analysis, and interpretation of acoustic radiation from energetic fumaroles at Volcan Acatenango, Guatemala, during mid-January 1973. Particular attention is given to deriving information about the flow velocity of the erupting medium from acoustics as a means to study eruption dynamics. Theoretical

Gordon Woulff; Thomas R. McGetchin

1976-01-01

328

Volcano instability and collapse from basement faulting  

Microsoft Academic Search

The potential of volcanic edifices to suffer sudden and catastrophic lateral collapse, generating debris avalanches with long run-out distances, represents a major geological hazard. There are many possible triggers of such collapses, but the size and direction of collapse may be heavily influenced by tectonic faulting. Where faults occur in proximity to a volcano, modification to the position and form

L. Wooller; H. Rymer; B. van Wyk de Vries

2003-01-01

329

Continental basaltic volcanoes — Processes and problems  

Microsoft Academic Search

Monogenetic basaltic volcanoes are the most common volcanic landforms on the continents. They encompass a range of morphologies from small pyroclastic constructs to larger shields and reflect a wide range of eruptive processes. This paper reviews physical volcanological aspects of continental basaltic eruptions that are driven primarily by magmatic volatiles. Explosive eruption styles include Hawaiian and Strombolian (sensu stricto) and

G. A. Valentine; T. K. P. Gregg

2008-01-01

330

Volcano geodesy and magma dynamics in Iceland  

Microsoft Academic Search

Here we review the achievements of volcano geodesy in Iceland during the last 15 years. Extensive measurements of crustal deformation have been conducted using a variety of geodetic techniques, including leveling, electronic distance measurements, campaign and continuous Global Positioning System (GPS) geodesy, and interferometric analysis of synthetic aperture radar images (InSAR). Results from these measurements provide a comprehensive view of

Erik Sturkell; Páll Einarsson; Freysteinn Sigmundsson; Halldór Geirsson; Halldór Ólafsson; Rikke Pedersen; Elske de Zeeuw-van Dalfsen; Alan T. Linde; Selwyn I. Sacks; Ragnar Stefánsson

2006-01-01

331

Taking the Pulse of Yellowstone's "Breathing" Volcano  

NSDL National Science Digital Library

In this activity, students learn about volcanism in Yellowstone National Park, focusing on its history of eruption, recent seismicity, hydrothermal events, and ground deformation. They learn how scientists monitor volcanoes (using Mount St. Helens as an example) and then apply that as an open-ended problem to Yellowstone; their problem is to identify a site for a research station.

Pratt-Sitaula, Beth

332

Measuring earthquake and volcano activity from space  

NSDL National Science Digital Library

The student will be introduced to InSAR observations in the beginning of the class via a PPT presentation that explains basic concepts. The activity will expose the student to simple examples of earthquake and volcano activity and better understanding of the colorful phase presentation of interferograms.

Wdowinski, Shimon

333

Volcano hazards at Fuego and Acatenango, Guatemala  

USGS Publications Warehouse

The Fuego-Acatenango massif comprises a string of five or more volcanic vents along a north-south trend that is perpendicular to that of the Central American arc in Guatemala. From north to south known centers of volcanism are Ancient Acatenango, Yepocapa, Pico Mayor de Acatenango, Meseta, and Fuego. Volcanism along the trend stretches back more than 200,000 years. Although many of the centers have been active contemporaneously, there is a general sequence of younger volcanism, from north to south along the trend. This massive volcano complex towers more than 3,500 meters above the Pacific coastal plain to the south and 2,000 meters above the Guatemalan Highlands to the north. The volcano complex comprises remnants of multiple eruptive centers, which periodically have collapsed to form huge debris avalanches. The largest of these avalanches extended more than 50 kilometers from its source and covered more than 300 square kilometers. The volcano has potential to produce huge debris avalanches that could inundate large areas of the Pacific coastal plain. In areas around the volcanoes and downslope toward the coastal plain, more than 100,000 people are potentially at risk from these and other flowage phenomena. -- Vallance, et.al., 2001

Vallance, J. W.; Schilling, S. P.; Matias, O.; Rose, W. I.; Howell, M. M.

2001-01-01

334

The Reawakening of Alaska's Augustine Volcano  

Microsoft Academic Search

Augustine volcano, in south central Alaska, ended a 20-year period of repose on 11 January 2006 with 13 explosive eruptions in 20 days. Explosive activity shifted to a quieter effusion of lava in early February, forming a new summit lava dome and two short, blocky lava flows by late March (Figure 1). The eruption was heralded by eight months of

John A. Power; Christopher J. Nye; Michelle L. Coombs; Rick L. Wessels; Peter F. Cervelli; John Dehn; Kristi L. Wallace; Jeffery T. Freymueller; Michael P. Doukas

2006-01-01

335

The Anatahan volcano-monitoring system  

NASA Astrophysics Data System (ADS)

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

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

2003-12-01

336

Volcano load control on dyke propagation and vent distribution: Insights from analogue modeling  

Microsoft Academic Search

The spatial distribution of eruptive vents around volcanoes can be complex and evolve as a volcano grows. Observations of vent distribution at contrasting volcanoes, from scoria cones to large shields, show that peripheral eruptive vents concentrate close to the volcano base. We use analogue experiments to explore the control of volcano load on magma ascent and on vent location. Results

M. Kervyn; G. G. J. Ernst; B. van Wyk de Vries; L. Mathieu; P. Jacobs

2009-01-01

337

Common characteristics of paired volcanoes in northern Central America  

NASA Astrophysics Data System (ADS)

Four pairs of active volcanoes along the northern Central American volcanic front have erupted basalt-andesite magmas that show consistent intrapair behavioral and compositional differences. These differences are found in records of volcanic activity and complete major and minor element data on over 200 samples. From northwest to southeast along the volcanic front the four volcano pairs are Cerro Quemado-Santa María, Tolimán-Atitlán, Acatenango-Fuego, and Santa Ana-Izalco. The volcano pair relations help explain compositional differences, apart from those reflecting variation in crustal thickness of about 15 km along the volcanic front, providing insight into across-arc variations and closely spaced subvolcanic plumbing systems. Intravolcano pair spacing is less than 5 km compared with an average intervolcano spacing of 25 km along the entire volcanic front. Within each volcano pair, the seaward volcano has had more frequent historic activity, erupting magmas that are generally more mafic, lower in large ion lithophile elements and higher in Na2O/K2O than magmas erupted from its landward counterpart. Each paired volcano site lies in close proximity to a rhyolitic caldera, situated north or northeast of the volcano pair. However, rare earth element data at the Tolimán-Atitlán volcano pair imply that mixing between caldera rhyolite and the mafic magma of the paired volcanoes does not occur. Petrographie, isotopic, and other geochemical data from the Tolimán-Atitlán volcano pair suggest that separate but contemporaneous magma bodies beneath each volcano evolve and pass through the crust at different rates. Atitlán magmas are processed through the crust more efficiently and with greater frequency than Tollman magmas, which undergo longer periods of stagnation interrupted by mafic injection and rapid eruption. This relation appears to hold at the other paired volcano sites and is further evidence that closely spaced volcanoes, with similar subcrustal magma sources, evolve over separate magmatic plumbing systems that traverse the crust. The pairing pattern probably reflects the regional southward migration of the volcanic front.

Halsor, Sid P.; Rose, William I.

1988-05-01

338

Geochemistry Study of Cenozoic Wangtian'e Volcano in Northeast China  

NASA Astrophysics Data System (ADS)

Wangtian'e Volcano (41° 43.6'N, 127° 54.3'E), which is ca. 35 km south of the famous central-type Tianchi Volcano, locates on north part of Changbai County, on the border of Changbai County and Fusong County, Jilin Province, Northeast China. It is another large central eruption volcano on the south slape of Changbaishan. The highest peak of Wangtian'e Volcano locating on the southeast rim of the caldera is 2438 m high, which is the second highest peak in Northeast China. The main part surrounding Wangtian'e Volcano is a large area of basaltic lava as a shield platform. The lava flow reaches the bank of the Yalu River in the south and stretches across the Yalu River over to the North Korean side to the east, advances into Fusong County in the north, reaching the east of Linjiang to the west, which covers an area of nearly 4000 km2. Development of radial drainage formed gullies around Wangtian'e cone. In the part of Changbai County, the gullies are named No. 8 to No. 23 gully. Due to the late drainage, from No. 13 to No. 19 gullies, trachybasalt with well-developed columnar jointing occurs, leading to the formation of isolated tower forest spreading along both sides of the drainage. On top of the Wangtian'e cone there exists alkalic rhyolite. Volcanic rocks were collected from the bottom to the top of Wangtian'e Volcano in 2006. Basaltic rocks consist of plagioclase rich phenocrysts, alkalic rhyolite has the presence of sanidine phenocrysts. The dominant Cenozoic (7.04-1.86Ma) volcanic samples from Wangtian'e Volcano are basaltic trachyandesite and alkalic rhyolite. The basaltic trachyandesites have low SiO2 (49.38%-53.31%), K2O+Na2O (4.27%-7.72%) and ? REE (163.69ppm-258.55ppm). ?Eu range between 0.72 and 1.17. The alkalic rhyolites have high SiO2(70.39%-71.49%), K2O+Na2O (9.28%-9.49%) and ? REE (309.30ppm-465.03ppm). The value of ?Eu is 0.72 to 1.17. 87Sr/86Sr and 144Nd/143Nd vary within 0.705156-0.709029 and 0.512602-0.512295 respectively. Radiogenic Pb is relatively low (206Pb/204Pb=17.254-18.090; 207Pb/204Pb=15.460-15.507; 208Pb/204Pb=37.278-38.048). All the above characters show that there are two magma sources that generate basaltic trachyandesite and alkalic rhyolite.

Chen, X.; Liu, L.

2012-04-01

339

Continuous monitoring of volcanoes with borehole strainmeters  

NASA Astrophysics Data System (ADS)

Monitoring of volcanoes using various physical techniques has the potential to provide important information about the shape, size and location of the underlying magma bodies. Volcanoes erupt when the pressure in a magma chamber some kilometers below the surface overcomes the strength of the intervening rock, resulting in detectable deformations of the surrounding crust. Seismic activity may accompany and precede eruptions and, from the patterns of earthquake locations, inferences may be made about the location of magma and its movement. Ground deformation near volcanoes provides more direct evidence on these, but continuous monitoring of such deformation is necessary for all the important aspects of an eruption to be recorded. Sacks-Evertson borehole strainmeters have recorded strain changes associated with eruptions of Hekla, Iceland and Izu-Oshima, Japan. Those data have made possible well-constrained models of the geometry of the magma reservoirs and of the changes in their geometry during the eruption. The Hekla eruption produced clear changes in strain at the nearest instrument (15 km from the volcano) starting about 30 minutes before the surface breakout. The borehole instrument on Oshima showed an unequivocal increase in the amplitude of the solid earth tides beginning some years before the eruption. Deformational changes, detected by a borehole strainmeter and a very long baseline tiltmeter, and corresponding to the remote triggered seismicity at Long Valley, California in the several days immediately following the Landers earthquake are indicative of pressure changes in the magma body under Long Valley, raising the question of whether such transients are of more general importance in the eruption process. We extrapolate the experience with borehole strainmeters to estimate what could be learned from an installation of a small network of such instruments on Mauna Loa. Since the process of conduit formation from the magma sources in Mauna Loa and other volcanic regions should be observable, continuous high sensitivity strain monitoring of volcanoes provides the potential to give short time warnings of impending eruptions. Current technology allows transmission and processing of rapidly sampled borehole strain data in real-time. Such monitoring of potentially dangerous volcanoes on a global scale would provide not only a wealth of scientific information but also significant social benefit, including the capability of diverting nearby in-flight aircraft.

Linde, Alan T.; Sacks, Selwyn

340

East Asia mantle tomography: New insight into plate subduction and intraplate volcanism  

NASA Astrophysics Data System (ADS)

We present a new P-wave tomographic model beneath East Asia by inverting 1,401,797 arrival-time data recorded by the regional seismic networks in East Asia and temporary seismic arrays deployed on the Tibetan Plateau. Our high-resolution tomography shows that the subducted Pacific slab is revealed clearly as a high-velocity (high-V) zone and it becomes stagnant in the mantle transition zone beneath eastern China. Prominent high-V anomalies atop the 410 km discontinuity are detected beneath the eastern North China Craton and Northeast China, suggesting that lithospheric delamination may have occurred and greatly affected the thermal state, intraplate magmatism and surface topography of this region. The Indian lithosphere is characterized by a high-V anomaly and it is subducting nearly horizontally beneath the entire or most parts of western Tibet and with a small dipping angle to the southernmost part of eastern Tibet. The intraplate magmatism in different parts of East Asia has different origins. The active Tengchong volcano is underlain by a prominent low-velocity (low-V) anomaly in the shallow mantle, which may be caused by the subduction and dehydration of the Burma microplate plate (or Indian plate). The Hainan volcano is underlain by a plume-like low-V anomaly that extends down to at least 1000 km depth and seems to be related to the deep subductions of the Burma microplate (or Indian plate) in the west and the Philippine Sea plate in the east. Prominent low-V anomalies are detected beneath the Changbai, Longgang and Xianjindao volcanoes in Northeast Asia, which may be related to the rollback of the subducting Pacific slab as well as the convective circulation process in the big mantle wedge above the stagnant slab. The origin of the Wudalianchi volcano in Northeast China seems associated with the upwelling of asthenospheric materials caused by the subduction-induced lithospheric delamination.

Wei, Wei; Xu, Jiandong; Zhao, Dapeng; Shi, Yaolin

2012-10-01

341

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

Microsoft Academic Search

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

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

1999-01-01

342

Deformation and Eruption Forecasting at Volcanoes under Retreating Ice Caps: Discriminating Signs of Magma Inflow and Ice Unloading at Grimsvotn and Katla volcanoes, Iceland  

Microsoft Academic Search

Warmer climate is causing retreat of many of the world's ice caps that cover volcanoes. Such ice unloading may influence magma systems and lead to elastic\\/inelastic earth response such as glacio-isostatic uplift. In Iceland, a number of the most active volcanoes are under retreating ice caps, including the Grimsvotn and Katla volcanoes. Both volcanoes have calderas and shallow magma chambers,

F. Sigmundsson; E. Sturkell; V. Pinel; P. Einarsson; R. Pedersen; H. Geirsson; M. T. Gudmundsson; H. Bjornsson; C. Pagli

2004-01-01

343

GPS Monitoring Bezimyany Volcano 2006-2010 (kamchatka)  

Microsoft Academic Search

The PIRE project (U.S.-Russia Partnership for Volcanological Research and Education) started in 2005, focused on Bezymianny volcano in Kamchatka, Russia. One part of the research is the GPS monitoring of deformation at Bezymianny volcano and surrounding area. In 2005-2006, we established a GPS network of 14 points around Bezymianny volcano, 10 observation points built for continuous GPS stations and 4

S. Serovetnikov; J. T. Freymueller; N. Titkov; V. Bahtiarov; S. Senyukov

2010-01-01

344

Shallow plumbing systems for small-volume basaltic volcanoes  

Microsoft Academic Search

Eruptive dynamics in basaltic volcanoes are controlled, in part, by the conduit geometry. However, uncertainties in conduit\\u000a shape and dike-to-conduit transition geometry have limited our predictive capability for hazards assessments. We characterize\\u000a the subvolcanic geometry of small-volume basaltic volcanoes (magmatic volatile-driven eruptions, 0.1 to 0.5 km3) based on a synthesis of field studies of five basaltic volcanoes exposed to varying degrees

Gordon N. Keating; Greg A. Valentine; Donathon J. Krier; Frank V. Perry

2008-01-01

345

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

NSDL National Science Digital Library

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

Fries-Gaither, Jessica

346

Active volcanoes of Kamchatka and northern Kurils in 2005  

Microsoft Academic Search

In 2005, six major eruptions of four Kamchatka volcanoes (Bezymyannyi, Klyuchevskoy, Shiveluch, and Karymskii) occurred and\\u000a the Avachinskii, Mutnovskii, and Gorelyi Kamchatka volcanoes and the Ebeko and Chikurachki volcanoes in northern Kurils were\\u000a in a state of increased activity. Owing to a close collaboration between the KVERT project, Elizovo airport meteorological\\u000a center, and volcanic ash advisory centers in Tokyo, Anchorage,

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

2007-01-01

347

Origin of maar volcanoes: external water, internal volatiles, or both?  

NASA Astrophysics Data System (ADS)

The origin of maar volcanoes has been interpreted as due to explosive magma-water interaction for more than 40 years (Fisher and Waters 1970; Lorenz 1973 and Fisher and Schmincke 1984). Earlier suspicions that CO2-degassing plays a role in maar formation (Schmincke 1977) are now followed up by re-examining maar deposits of four different compositions in the maar-type locality (Eifel, Germany). These four compositions comprise: (1) melilite-nephelinites (West Eifel), (2) leucitites/nephelinites (West Eifel), (3) Na-rich basanites (West Eifel), and (4) K-rich basanites (East Eifel). At present, we focus on high-resolution stratigraphy, sedimentology, grain-size distribution, component analysis (accidental vs. juvenile clasts), and morphological and textural particle studies, accompanied by standard glass and bulk chemical and mineralogical analyses. Interestingly, maar deposits of highly silica-undersaturated and - by inference - CO2-rich composition (melilite-nephelinites and leucitites/nephelinites) show features contrasting with the classical catalogue of criteria for hydroclastic fragmentation (Fisher and Schmincke 1984). Their deposits are medium- to coarse-grained (MdØ mainly: 2 - 8 mm), mostly moderate- to well-sorted (?Ø mainly: 1 - 2.5) and in some cases juvenile-rich (up to 50-70 wt. %). Transport and depositional mechanisms comprise a mixture of surge and fallout differing from the general assumption that maar deposits are dominated by surges. Additionally, features of juvenile clasts of highly silica-undersaturated composition largely differ from the features of "classic" hydroclastic particles (e.g.: dense, blocky, glassy shards). Juvenile clasts of highly silica-undersaturated composition show: (a) round- to semiround morphologies, (b) slight- to moderate vesicularities, (c) near absence of glassy material, (d) abundance of deep-seated xenoliths (mantle and lower crust), (e) agglutinated lava rinds enveloping the mantle- and crust-xenoliths, and (f) carbonate fragments, most probably of magmatic origin, within the groundmass. In contrast, basanitic maar deposits - by inference with low CO2 concentrations - and particularly their juvenile clasts show more conventional features of hydroclastic fragmentation processes. They are finer-grained, moderate- to poorly-sorted, extremely lithoclast-rich, and the juvenile clasts are generally angular, slightly- to non-vesicular and glassy. Moreover, deep-seated xenoliths and carbonate fragments are lacking. At this stage in our study we postulate that the high CO2 concentrations of highly silica-undersaturated maar volcanoes in the West Eifel could have played a significant role in maar-forming processes. These magmas may have undergone magmatic fragmentation due to rapid CO2-exsolution prior to shallow magma-water interaction resulting in explosive eruptions governed by both, magmatic and phreatomagmatic fragmentation and eruptive processes.

Rausch, J.; Schmincke, H.-U.

2012-04-01

348

Preliminary radon measurements at Villarrica volcano, Chile  

NASA Astrophysics Data System (ADS)

We report data from a radon survey conducted at Villarrica volcano. Measurements have been obtained at selected sites by E-PERM® electrets and two automatic stations utilizing DOSEman detectors (SARAD Gmbh). Mean values for Villarrica are 1600 (±1150) Bq/m3 are similar to values recorded at Cerro Negro and Arenal in Central America. Moderately higher emissions, at measurement sites, were recorded on the NNW sector of the volcano and the summit, ranging from 1800 to 2400 Bq/m3. These measurements indicate that this area could potentially be a zone of flank weakness. In addition, the highest radon activities, up to 4600 Bq/m3, were measured at a station located near the intersection of the Liquiñe-Ofqui Fault Zone with the Gastre Fault Zone.

Cigolini, C.; Laiolo, M.; Coppola, D.; Ulivieri, G.

2013-10-01

349

How Volcanoes Work: Dynamics of Eruptions  

NSDL National Science Digital Library

This site examines the variability of volcanic environments and the physical and chemical controls on eruption dynamics. Environments of volcanism are discussed in terms of plate tectonic theory and include spreading center, subduction zone, and interplate volcanism along with a detailed discussion of the Earth's structure and internal heat. Physical and chemical controls of eruption dynamics include composition of the magma and also its viscosity, temperature, and the amount of dissolved gases in the magma. The section on eruption variability includes a discussion about the frequency and size of the eruptions as well as a detailed explanation of Volcano Explosivity Index, (VEI) and also includes a chart that compares the VEI of well-known volcanoes. This site also has an eruption model that explains the dynamics of the eruption with diagrams. An interactive quiz is included that gives immediate feed-back.

Camp, Victor

350

Decision Analysis Tools for Volcano Observatories  

NASA Astrophysics Data System (ADS)

Staff at volcano observatories are predominantly engaged in scientific activities related to volcano monitoring and instrumentation, data acquisition and analysis. Accordingly, the academic education and professional training of observatory staff tend to focus on these scientific functions. From time to time, however, staff may be called upon to provide decision support to government officials responsible for civil protection. Recognizing that Earth scientists may have limited technical familiarity with formal decision analysis methods, specialist software tools that assist decision support in a crisis should be welcome. A review is given of two software tools that have been under development recently. The first is for probabilistic risk assessment of human and economic loss from volcanic eruptions, and is of practical use in short and medium-term risk-informed planning of exclusion zones, post-disaster response, etc. A multiple branch event-tree architecture for the software, together with a formalism for ascribing probabilities to branches, have been developed within the context of the European Community EXPLORIS project. The second software tool utilizes the principles of the Bayesian Belief Network (BBN) for evidence-based assessment of volcanic state and probabilistic threat evaluation. This is of practical application in short-term volcano hazard forecasting and real-time crisis management, including the difficult challenge of deciding when an eruption is over. An open-source BBN library is the software foundation for this tool, which is capable of combining synoptically different strands of observational data from diverse monitoring sources. A conceptual vision is presented of the practical deployment of these decision analysis tools in a future volcano observatory environment. Summary retrospective analyses are given of previous volcanic crises to illustrate the hazard and risk insights gained from use of these tools.

Hincks, T. H.; Aspinall, W.; Woo, G.

2005-12-01

351

The 1931 Eruption of Aniakchak Volcano, Alaska  

Microsoft Academic Search

One of the largest Aleutian Arc eruptions of the 20th century was the 1931 intracaldera eruption of Aniakchak Volcano, with an erupted volume of 0.3 to 0.5 km3. The eruption, which varied in intensity, style, and composition, persisted for approximately 6 weeks, dispersing ash as far as 600 km to the north. The eruption was first noticed when a large

R. S. Nicholson; C. A. Neal; J. E. Gardner

2002-01-01

352

The Soufriere Hills Volcano, Montserrat, is  

Microsoft Academic Search

The Soufriere Hills Volcano, Montserrat, experienced a remarkable episode of activity in September-October, 1997. During this period, 75 vulcanian explosions generated plumes that commonly rose between 5 to 15 km a.s.l. accompanied by pyroclastic flows. Repose intervals between vulcanian explosions varied from 2.77 to 33.7 hrs, with a median repose interval of 9.0 hr and mean of 9.6 hr. During

C. Connor; S. Sparks; R. Mason; C. Bonadonna; S. Young; A. Lejeune

2002-01-01

353

Radar Images of the Earth: Volcanoes  

NSDL National Science Digital Library

This site features links to thirty-five NASA radar images of the world's volcanoes, including brief descriptions of the respective processes and settings involved. The images were created with the Spaceborne Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) as part of NASA's Mission to Planet Earth. The radar illuminates Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions.

354

Airborne gravity reveals interior of Antarctic volcano  

NASA Astrophysics Data System (ADS)

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

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

2009-07-01

355

Carbon Dioxide Budget of Kilauea Volcano  

Microsoft Academic Search

We report a new CO2 budget for Kilauea volcano based on experiments carried out in 9\\/95, 10\\/98, and 5\\/99. The summit CO2 emission rate was constrained by the SO2 emission rate (by COSPEC) and the average volcanic CO2\\/SO2 (by NDIR CO2 analyzer and CP-FTIR) at ground level along the 5.4-km summit COSPEC traverse. The summit CO2 emission rate is nearly

T. M. Gerlach; K. A. McGee; T. Elias; A. J. Sutton; M. P. Doukas

2002-01-01

356

Degassing and differentiation in subglacial volcanoes, Iceland  

USGS Publications Warehouse

Within the neovolcanic zones of Iceland many volcanoes grew upward through icecaps that have subsequently melted. These steep-walled and flat-topped basaltic subglacial volcanoes, called tuyas, are composed of a lower sequence of subaqueously erupted, pillowed lavas overlain by breccias and hyaloclastites produced by phreatomagmatic explosions in shallow water, capped by a subaerially erupted lava plateau. Glass and whole-rock analyses of samples collected from six tuyas indicate systematic variations in major elements showing that the individual volcanoes are monogenetic, and that commonly the tholeiitic magmas differentiated and became more evolved through the course of the eruption that built the tuya. At Herdubreid, the most extensively studies tuya, the upward change in composition indicates that more than 50 wt.% of the first erupted lavas need crystallize over a range of 60??C to produce the last erupted lavas. The S content of glass commonly decreases upward in the tuyas from an average of about 0.08 wt.% at the base to < 0.02 wt.% in the subaerially erupted lava at the top, and is a measure of the depth of water (or ice) above the eruptive vent. The extensive subsurface crystallization that generates the more evolved, lower-temperature melts during the growth of the tuyas, apparently results from cooling and degassing of magma contained in shallow magma chambers and feeders beneath the volcanoes. Cooling may result from percolation of meltwater down cracks, vaporization, and cycling in a hydrothermal circulation. Degassing occurs when progressively lower pressure eruption (as the volcanic vent grows above the ice/water surface) lowers the volatile vapour pressure of subsurface melt, thus elevating the temperature of the liquidus and hastening liquid-crystal differentiation. ?? 1991.

Moore, J. G.; Calk, L. C.

1991-01-01

357

Buried caldera of mauna kea volcano, hawaii.  

PubMed

An elliptical caldera (2.1 by 2.8 kilometers) at the summit of Mauna Kea volcano is inferred to lie buried beneath hawaiite lava flows and pyroclastic cones at an altitude of approximately 3850 meters. Stratigraphic relationships indicate that hawaiite eruptions began before a pre-Wisconsin period of ice-cap glaciation and that the crest of the mountain attained its present altitude and gross form during a glaciation of probable Early Wisconsin age. PMID:17842285

Porter, S C

1972-03-31

358

New insights on Panarea volcano from terrestrial, marine and airborne data  

NASA Astrophysics Data System (ADS)

The Panarea volcano belongs to the Aeolian arc system and its activity, which recently produced impacts on the environment as well as on human settlements, is known since historical times. This volcano, which includes Panarea island and its archipelago, is the emergent portion of submarine stratovolcano more than 2000 m high and 20 Km across. In November 2002 a submarine gas eruption started offshore 3 Km east of Panarea on top of a shallow rise of 2.3 km2 surrounded by the islets of Lisca Bianca, Bottaro and Lisca Nera. This event has posed new concern on a volcano generally considered extinct. Soon after the submarine eruption, this area has been surveyed under multidisciplinary programs funded by the Italian Department of the Civil Protection and INGV. Monitoring programs included subaerial and sea bottom DEM of Panarea volcano by merging aerial digital photogrammetry, aerial laser scanning and multibeam bathymetry. A GPS ground deformation network (PANANET) was designed, set up and measured during time span December 2002 - October 2007. GPS data show rates of motion and strain values typical of volcanic areas which are in agreement with the NE-SW and NW-SE tectonic systems. The latter coincide with the main pathways for the upwelling of hydrothermal fluids. GPS data inferred a pre-event uplift followed by a general subsidence and shortening across the area that could be interpreted as the response to the surface of the inflation and deflation of the hydrothermal system reservoir which is progressively reducing its pressure after the 2002 gas eruption. Magnetic and gravimetric data depict the deep and shallow structure of the volcano. From geochemical surveys were calculated energetic conditions at craters. Data were coupled with the computed physic-chemical state of the fluids at the level of the deep reservoir and provided the boundary conditions of the occurred event, and suggesting that a low-energy explosion was responsible for producing the craters at the sea bottom. Finally, we provide a model constrained by GPS data and Okada formulation, which suggests that the degassing intensity and distribution are strongly influenced by geophysical-geochemical changes within the hydrothermal/geothermal system. These variations may be triggered by changes in the regional stress field as suggested by the geophysical and volcanological events which occurred in 2002 in the Southern Tyrrhenian area.

Anzidei, Marco

2010-05-01

359

Fumarole/plume and diffuse CO2 emission from Sierra Negra volcano, Galapagos archipelago  

NASA Astrophysics Data System (ADS)

The active shield-volcano Sierra Negra is part of the Galapagos hotspot. Sierra Negra is the largest shield volcano of Isabela Island, hosting a 10 km diameter caldera. Ten historic eruptions have occurred and some involved a frequently visited east caldera rim fissure zone called Volcan Chico. The last volcanic event occurred in October 2005 and lasted for about a week, covering approximately twenty percent of the eastern caldera floor. Sierra Negra volcano has experienced some significant changes in the chemical composition of its volcanic gas discharges after the 2005 eruption. This volcanic event produced an important SO2 degassing that depleted the magmatic content of this gas. Not significant changes in the MORB and plume-type helium contribution were observed after the 2005 eruption, with a 65.5 % of MORB and 35.5 % of plume contribution. In 2006 a visible and diffuse gas emission study was performed at the summit of Sierra Negra volcano, Galapagos, to evaluate degassing rate from this volcanic system. Diffuse degassing at Sierra Negra was mainly confined in three different DDS: Volcan Chico, the southern inner margin of the caldera, and Mina Azufral. These areas showed also visible degassing, which indicates highly fractured areas where volcano-hydrothermal fluids migrate towards surface. A total fumarole/plume SO2 emission of 11 ± 2 td-1 was calculated by mini-DOAS ground-based measurements at Mina Azufral fumarolic area. Molar ratios of major volcanic gas components were also measured in-situ at Mina Azufral with a portable multisensor. The results showed H2S/SO2, CO2/SO2 and H2O/SO2 molar ratios of 0.41, 52.2 and 867.9, respectively. Multiplying the observed SO2 emission rate times the observed (gas)i/SO2 mass ratio we have estimated other volatiles emission rates. The results showed that H2O, CO2 and H2S emission rates from Sierra Negra are 562, 394, and 2.4 t d-1, respectively. The estimated total output of diffuse CO2 emission from the summit of Sierra Negra was 989 ± 85 t d-1. Estimated diffuse/plume CO2 emission ratio was 2.5.

Padron, E.; Hernandez Perez, P. A.; Perez, N.; Theofilos, T.; Melian, G.; Barrancos, J.; Virgil, G.; Sumino, H.; Notsu, K.

2009-12-01

360

Masaya Volcano, Nicaragua: A Terrestrial Analog for the Evolution of Martian Calderas  

NASA Astrophysics Data System (ADS)

Like their terrestrial counterparts, Martian calderas are believed to be the surface products of the partial evacuation of a magma chamber at a few kilometers depth. Mars Orbiter Laser Altimeter (MOLA) data show that sagging of the caldera center may exceed 1.6 km at Biblis Patera, 1.3 km at Olympus Mons, and 300 m at Alba Patera, suggesting post-eruption deflation of the magma chamber. In order to understand the physical structure of Martian volcanoes, we are conducting a detailed morphologic and topographic comparison of Olympus Mons caldera, Mars, and the Nindiri pit crater of Masaya volcano, Nicaragua. Masaya volcano, Nicaragua, is a persistently active basaltic volcano that comprises four main pit craters, which are named (from east to west) Masaya, Santiago, Nindiri, and San Pedro. Nindiri crater is partially filled by frozen lava lakes that formed between 1570 and 1670. The lava surface in the crater subsequently sagged downward plastically before failure in a brittle fashion along circular bounding faults, producing fractures that are morphologically similar to the circumferential fractures seen around the perimeter of the floor of Olympus Mons caldera. The walls of San Pedro and Santiago pit craters that formed following lava lake emplacement now cut these Nindiri features. Exposure of the lava lake pile in the pit crater wall allows a vertical section in excess of 300 m to be studied. Lava flows preserved in the eastern wall of Nindiri have sagged about 50 meters. A more recent lava lake was also erupted onto the sagged crater floor in 1852 where it ponded within the sag-structure. Our on-going study of Nindiri as a terrestrial analog to Martian calderas is focused on analysis of the structural features and on the timing of the eruptions and deformation events. Numerous features are common to both calderas, including extensional fractures around the perimeter of their floors, compressional ridges near the center of collapse, and ponded lava flows that have now been dissected by more recent collapse events. If we can show that one collapse event deformed plastically (as at Nindiri), then this suggests that the subsidence took place within a few years of lava lake emplacement so that the lava was still at a high enough temperature to allow plastic deformation. Brittle deformation is more likely to imply a longer time period between lava lake emplacement and collapse. In either case, extrapolation of these ideas to Mars has significance for inferring magma supply rates at the summit of Olympus Mons and other Martian volcanoes.

Mouginis-Mark, P. J.; Harris, A. J.

2002-12-01

361

Unusual ice diamicts emplaced during the December 15, 1989 eruption of redoubt volcano, Alaska  

USGS Publications Warehouse

Ice diamict comprising clasts of glacier ice and subordinate rock debris in a matrix of ice (snow) grains, coarse ash, and frozen pore water was deposited during the eruption of Redoubt Volcano on December 15, 1989. Rounded clasts of glacier ice and snowpack are as large as 2.5 m, clasts of Redoubt andesite and basement crystalline rocks reach 1 m, and tabular clasts of entrained snowpack are as long as 10 m. Ice diamict was deposited on both the north and south volcano flanks. On Redoubt's north flank along the east side of Drift piedmont glacier and outwash valley, ice diamict accumulated as at least 3 units, each 1-5 m thick. Two ice-diamict layers underlie a pumice-lithic fall tephra that accumulated on December 15 from 10:15 to 11:45 AST. A third ice diamict overlies the pumiceous tephra. Some of the ice diamicts have a basal 'ice-sandstone' layer. The north side icy flows reached as far as 14 km laterally over an altitude drop of 2.3 km and covered an area of about 5.7 km2. On Crescent Glacier on the south volcano flank, a composite ice diamict is locally as thick as 20 m. It travelled 4.3 km over an altitude drop of 1.7 km, covering about 1 km2. The much higher mobility of the northside flows was influenced by their much higher water contents than the southside flow(s). Erupting hot juvenile andesite triggered and turbulently mixed with snow avalanches at snow-covered glacier heads. These flows rapidly entrained more snow, firn, and ice blocks from the crevassed glacier. On the north flank, a trailing watery phase of each ice-diamict flow swept over and terraced the new icy deposits. The last (and perhaps each) flood reworked valley-floor snowpack and swept 35 km downvalley to the sea. Ice diamict did not form during eruptions after December 15 despite intervening snowfalls. These later pyroclastic flows swept mainly over glacier ice rather than snowpack and generated laharic floods rather than snowflows. Similar flows of mixed ice grains and pyroclastic debris resulted from the November 13, 1985 eruption of Nevado del Ruiz volcano and from eruptions of snowclad Mount St. Helens in 1982-1984. Such deposits at snowclad volcanoes are initially broad and geomorphically distinct, but they soon become extensively reworked and hard to recognize in the geologic record. ?? 1994.

Waitt, R. B.; Gardner, C. A.; Pierson, T. C.; Major, J. J.; Neal, C. A.

1994-01-01

362

Volcano Expedition: From the Field in Costa Rica  

NSDL National Science Digital Library

This resource offers, among other things, a collection of journal entries from scientists reporting on their personal experiences of the volcanoes of Costa Rica. Reference sections include an introduction to volcanoes and Central America, the anatomy of subduction zones, the source of volatiles, sampling volatiles, recycling elements, and isotope geochemistry (geochemical tracers). There is a short description of several Costa Rican volcanoes, including: Turrialba, Arenal, Irazu, Poas, Rincon de la Vieja, Miravalles, and Laguna Poco Sol. Also included are a question and answer section on volcanoes, details about the expedition, and safety and danger issues.

363

Large shield volcanoes on the Moon  

NASA Astrophysics Data System (ADS)

volcanic style of the Moon has long been understood to consist almost exclusively of flood basalts erupted from fissures along with minor pyroclastic activity; large central vent shield volcanoes that characterize basaltic volcanism on the other terrestrial planets appeared to be absent. Small (few kilometers diameter) central vent constructs have long been recognized in the lunar maria and often are found clustered in fields throughout the lunar maria. New global topographic data from the LOLA and LROC instruments on LRO reveal that almost all of these volcanic complexes on the Moon occur on large, regional topographic rises in the lunar maria, tens to hundreds of kilometers in extent and between several hundred to several thousand meters high. We propose that these topographic swells are shield volcanoes and are the lunar equivalents of the large basaltic shields found on the Earth, Venus, and Mars. The newly recognized lunar shields are found peripheral to the large, deeply flooded impact basins Imbrium and Serenitatis, suggesting a genetic relation to those features. Loading of the lithosphere by these basalt-filled basins may be responsible for inducing a combination of flexural and membrane stress, inducing a pressure distribution on vertically oriented dikes favorable to magma ascent. This condition would occur in a zone annular to the large circular loads produced by the basins, where the shield volcanoes occur.

Spudis, Paul D.; McGovern, Patrick J.; Kiefer, Walter S.

2013-05-01

364

JPRS Report, East Europe.  

National Technical Information Service (NTIS)

Partial Contents: East Europe, Party Activities, Socialist Party, Freedom Fighters, Education, Youth Training, Historian, Death Penalty, Peace Making Duties, Socialism, Communism, Economics, Restructuring, Catastrophic Condition, Computer Production, edit...

1988-01-01

365

An Experimental Contribution to the Dynamics of Explosive Volcanism. A Case Study of Unzen Volcano and Soufrière Hills Volcano, Montserrat  

Microsoft Academic Search

Knowledge of the dynamics of magma fragmentation is necessary for a better understanding of the explosive behavior of silicic volcanoes. Here we have measured the fragmentation speed and the fragmentation threshold of five dacitic field samples (6.7 vol.% to 53.5 vol.% open porosity) from Unzen volcano, Kyushu, Japan and four andesitic-dacitic field samples of Soufrière Hills Volcano, Montserrat, West Indies

B. Scheu; O. Spieler; D. B. Dingwell

2003-01-01

366

Fluid-volcano interaction in an active stratovolcano: the crater lake system of Poás volcano, Costa Rica  

Microsoft Academic Search

Rowe, G.L. Jr., Brantley, S.L., Fernandez, M., Fernandez, J.F., Borgia, A. and Barquero, J., 1992. Fluid-volcano interac- tion in an active stratovolcano: the crater lake system of Po~is volcano, Costa Rica. J. Volcanol. Geotherm. Res., 49: 23- 51. Seismic and geochemical data collected at Po~is volcano, Costa Rica, since 1978 suggest that temperature and chemical variations recorded in subaerial fumaroles

G ROWEJR; Susan L. Brantley; Mario Fernandez; Jose F. Fernandez; Andrea Borgia; Jorge Barquero

1992-01-01

367

Mud volcanoes and gas hydrates in the Black Sea: new data from Dvurechenskii and Odessa mud volcanoes  

Microsoft Academic Search

Meteor cruise M52\\/1 documented the presence of gas hydrates in sediments from mud volcanoes in the Sorokin Trough of the Black Sea. In a mud flow on the Odessa mud volcano, a carbonate crust currently forms in association with anaerobic methane oxidation. Dvurechenskii mud volcano (DMV), a flat-topped “mud pie”-type structure, appeared to be very active. Pore water in sediments

G. Bohrmann; M. Ivanov; J.-P. Foucher; V. Spiess; J. Bialas; J. Greinert; W. Weinrebe; F. Abegg; G. Aloisi; Y. Artemov; V. Blinova; M. Drews; F. Heidersdorf; A. Krabbenhöft; I. Klaucke; S. Krastel; T. Leder; I. Polikarpov; M. Saburova; O. Schmale; R. Seifert; A. Volkonskaya; M. Zillmer

2003-01-01

368

Electrical structure of Newberry Volcano, Oregon  

NASA Astrophysics Data System (ADS)

From the interpretation of magnetotelluric, transient electromagnetic, and Schlumberger resistivity soundings, the electrical structure of Newberry Volcano in central Oregon is found to consist of four units. From the surface downward, the geoelectrical units are (1) very resistive, young, unaltered volcanic rock, (2) a conductive layer of older volcanic material composed of altered tuffs, (3) a thick resistive layer thought to be in part intrusive rocks, and (4) a lower-crustal conductor. This model is similar to the regional geoelectrical structure found throughout the Cascade Range. Inside the caldera, the conductive second layer corresponds to the steep temperature gradient and alteration minerals observed in the USGS Newberry 2 test hole. Drill hole information on the south and north flanks of the volcano (test holes GEO N-1 and GEO N-3, respectively) indicates that outside the caldera the conductor is due to alteration minerals (primarily smectite) and not high-temperature pore fluids. On the flanks of Newberry the conductor is generally deeper than inside the caldera, and it deepens with distance from the summit. A notable exception to this pattern is seen just west of the caldera rim, where the conductive zone is shallower than at other flank locations. The volcano sits atop a rise in the resistive layer, interpreted to be due to intrusive rocks. The intrusive material has served as a heat source to produce enhanced hydrothermal alteration and, perhaps in the case of the west-flank anomaly, elevated fluid temperatures. While no public drill hole information is available to confirm this hypothesis, the west-flank anomaly appears to be a good geothermal target. In addition to the possibility that a region on the west side of the volcano could be favorable for prospecting, part of the resistive structure under the center of the volcano could be due to a vapor-dominated environment with temperatures above 300°C. In other parts of the Cascades, pervasive alteration has produced mixed layer clays and zeolites, resulting in low-resistivity anomalies. Low resistivities cannot be assumed to indicate high-temperature pore fluids. The use of electrical methods that measure resistivity as a function of excitation frequency, such as spectral induced polarization, may provide a way of obtaining information about the type and extent of alteration.

Fitterman, D. V.; Stanley, W. D.; Bisdorf, R. J.

1988-09-01

369

Constraining volcano eruption dynamics with infrasound  

NASA Astrophysics Data System (ADS)

Infrasonic airwaves produced by exploding volcanoes provide an indispensable tool for understanding dynamics of diverse eruptions. Unlike the seismicity generated during eruption, which is a complex superposition of internal and surface source and wave propagation processes, the infrasonic pressure field can be unequivocally associated with the flux rate of gas released at the volcanic vent. Because the atmosphere does not support shear waves, and internal scattering, topographic echoes, site, and weather effects are substantially predictable, it is possible to objectively compare the infrasound, and assess degassing from diverse volcanic systems. With its utility for continuously tracking eruptive activity, even when line-of-sight view to the vent is obscured, infrasound greatly enhances the efficacy of volcano monitoring and interpretation of conduit processes / eruption dynamics. We showcase new results from Erebus, Fuego, Villarrica, and Santiaguito volcanoes to demonstrate the utility of infrasound for recovering quantitative parameters, such as eruption duration, source dimensions and mechanism, and explosive gas release. At Erebus, infrasound can constrain the physical dimension of enormous bubbles, with diameters up to 10 m and containing more than 1000 kg gas, that burst individually and infrequently from the lava lake surface. At Villarrica, longer-duration infrasonic transients reveal the eruptive mechanism to be a succession of gas slugs bursting from the free surface, occurring at 60-90 s intervals and representing a stable long-term mode of degassing. At Fuego, the infrasound associated with vigorous explosions is inferred to result from the fragmentation of a bubble foam layer, which continues for tens of seconds until the gas foam is depleted. And at Santiaguito, large eruptions, which generate low intensity infrasound, suggest a diffuse source region with dimensions comparable to the radiated infrasonic wavelength (vent radii > 100 m). The recorded infrasound from these 4 volcanoes complements our infrasound archives for an additional 6 volcanoes, which encompasses a wide range of eruptive behaviors. Infrasound recorded within a few km of a volcanic vent thus provides an ideal tool for objective comparison of associated degassing.

Johnson, J. B.; Aster, R. C.

2003-12-01

370

Climate model calculations of the effects of volcanoes on global climate. Status report, 1 December 1991-30 November 1992  

SciTech Connect

An examination of the Northern Hemisphere winter surface temperature patterns after the 12 largest volcanic eruptions from 1883-1992 shows warming over Eurasia and North America and cooling over the Middle East which are significant at the 95 percent level. This pattern is found in the first winter after tropical eruptions, in the first or second winter after midlatitude eruptions, and in the second winter after high latitude eruptions. The effects are independent of the hemisphere of the volcanoes. An enhanced zonal wind driven by heating of the tropical stratosphere by the volcanic aerosols is responsible for the regions of warming, while the cooling is caused by blocking of incoming sunlight.

Robock, A.

1992-01-01

371

Density muon radiography of La Soufrière of Guadeloupe volcano: comparison with geological, electrical resistivity and gravity data  

NASA Astrophysics Data System (ADS)

Density muon radiography is a new method to determine the average density of geological bodies by measuring the attenuation produced by rocks on the flux of cosmic muons. We present such density radiographies obtained for the Soufrière of Guadeloupe lava dome, both in the north-south and east-west planes. These radiographies reveal the highly heterogeneous density structure of the volcano, with low-density regions corresponding to recognized hydrothermally altered areas. The main structures observed in the density radiographies correlate with anomalies in electrical resistivity cross-sections and a density model obtained from gravity data.

Lesparre, Nolwenn; Gibert, Dominique; Marteau, Jacques; Komorowski, Jean-Christophe; Nicollin, Florence; Coutant, Olivier

2012-08-01

372

Characterization of acid river dilution and associated trace element behavior through hydrogeochemical modeling: A case study of the Banyu Pahit River in East Java, Indonesia  

Microsoft Academic Search

Kawah Ijen volcano in East Java, Indonesia emits hyperacid (pH?0) brines rich in toxic elements including F, Al, Cd and Tl, which are transported downstream by the Banyu Pahit River, which is eventually used to irrigate farmland on the Asambagus Plain. The fate and behavior of major and trace elements are investigated, in the region of greatest change to the

Stephanie C. J. Palmer; Vincent J. van Hinsberg; Jeffrey M. McKenzie; Sophia Yee

2011-01-01

373

An overview of the 2009 eruption of Redoubt Volcano, Alaska  

NASA Astrophysics Data System (ADS)

In March 2009, Redoubt Volcano, Alaska erupted for the first time since 1990. Explosions ejected plumes that disrupted international and domestic airspace, sent lahars more than 35 km down the Drift River to the coast, and resulted in tephra fall on communities over 100 km away. Geodetic data suggest that magma began to ascend slowly from deep in the crust and reached mid- to shallow-crustal levels as early as May, 2008. Heat flux at the volcano during the precursory phase melted ~ 4% of the Drift glacier atop Redoubt's summit. Petrologic data indicate the deeply sourced magma, low-silica andesite, temporarily arrested at 9-11 km and/or at 4-6 km depth, where it encountered and mixed with segregated stored high-silica andesite bodies. The two magma compositions mixed to form intermediate-silica andesite, and all three magma types erupted during the earliest 2009 events. Only intermediate- and high-silica andesites were produced throughout the explosive and effusive phases of the eruption. The explosive phase began with a phreatic explosion followed by a seismic swarm, which signaled the start of lava effusion on March 22, shortly prior to the first magmatic explosion early on March 23, 2009 (UTC). More than 19 explosions (or "Events") were produced over 13 days from a single vent immediately south of the 1989-90 lava domes. During that period multiple small pyroclastic density currents flowed primarily to the north and into glacial ravines, three major lahars flooded the Drift River Terminal over 35 km down-river on the coast, tephra fall deposited on all aspects of the edifice and on several communities north and east of the volcano, and at least two, and possibly three lava domes were emplaced. Lightning accompanied almost all the explosions.A shift in the eruptive character took place following Event 9 on March 27 in terms of infrasound signal onsets, the character of repeating earthquakes, and the nature of tephra ejecta. More than nine additional explosions occurred in the next two days, followed by a hiatus in explosive activity between March 29 and April 4. During this hiatus effusion of a lava dome occurred, whose growth slowed on or around April 2. The final explosion pulverized the very poorly vesicular dome on April 4, and was immediately followed by the extrusion of the final dome that ceased growing by July 1, 2009, and reached 72 M m3 in bulk volume. The dome remains as of this writing. Effusion of the final dome in the first month produced blocky intermediate- to high-silica andesite lava, which then expanded by means of lava injection beneath a fracturing and annealing, cooling surface crust. In the first week of May, a seismic swarm accompanied extrusion of an intermediate- to high-silica andesite from the apex of the dome that was highly vesicular and characterized by lower P2O5 content. The dome remained stable throughout its growth period likely due to combined factors that include an emptied conduit system, steady degassing through coalesced vesicles in the effusing lava, and a large crater-pit created by the previous explosions. We estimate the total volume of erupted material from the 2009 eruption to be between ~ 80 M and 120 M m3 dense-rock equivalent (DRE).The aim of this report is to synthesize the results from various datasets gathered both during the eruption and retrospectively, and which are represented by the papers in this publication. We therefore provide an overall view of the 2009 eruption and an introduction to this special issue publication.

Bull, Katharine F.; Buurman, Helena

2013-06-01

374

8. EAST PORTAL AND DECK VIEW, FROM EAST, SHOWING PORTAL ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. EAST PORTAL AND DECK VIEW, FROM EAST, SHOWING PORTAL CONFIGURATION AND LATERAL BRACING, STEEL MESH FLOOR, METAL RAILINGS, AND PORTION OF EAST APPROACH - Glendale Road Bridge, Spanning Deep Creek Lake on Glendale Road, McHenry, Garrett County, MD

375

55. LOOKING EAST FROM HEAD OF PLANE 2 EAST. POWER ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

55. LOOKING EAST FROM HEAD OF PLANE 2 EAST. POWER HOUSE AND FLUME VISIBLE TO RIGHT, TAILRACE RUNNING THROUGH CENTER OF PHOTOGRAPH. CRADLE TO INCLINED PLANE 3 EAST IS VISIBLE IN BACKGROUND TO LEFT. - Morris Canal, Phillipsburg, Warren County, NJ

376

Two Millennia of Edifice Instability at Augustine Volcano, Alaska and Implications for Future Collapse  

NASA Astrophysics Data System (ADS)

Augustine volcano, a ca. 1250-m-high lava-dome complex in the southern Cook Inlet, Alaska, has collapsed repeatedly during the late Holocene, producing debris-avalanche deposits that ring the island and extend offshore. About a dozen collapses have occurred in the past 2.2 ka, producing the highest-known collapse frequency (ca. 150-200 yr) at any volcano. Most debris avalanches at Augustine had volumes between 0.1 and 1 cu. km and reached about 7-10 km from the summit; typically about half that distance involved submarine travel into Cook Inlet. The most recent collapse took place in October 1883, forming the Burr Point debris- avalanche deposit on the north side of the volcano. Emplacement of the avalanche extended the shoreline about 2 km and produced a tsunami that impacted English Bay on the Kenai Peninsula. The collapse was accompanied by pumiceous pyroclastic flows that reached the sea and a subplinian explosive eruption that deposited ash across Cook Inlet. An earlier NW-flank collapse about 300 years ago was preceded by one of the largest known Augustine debris avalanches about 1540 +/- 110 AD. This collapse formed a new 2 x 3.5 km wide island (West Island) off the WNW coast of Augustine Island and was accompanied by a lateral blast that overrode the avalanche deposit and extended out to sea. The margins of West Island display extensive tsunami modification. Debris avalanches older than 1 ka were concentrated on the southern and eastern flanks of the volcano. Documented magmatic eruptions have accompanied several edifice-collapse events at Augustine, although syn-eruptive collapse has not been confirmed in all cases. The small size of the volcano and high magma production rates (0.0025 cu. km/yr) result in rapid reconstruction of the volcano after each collapse. The repeated cycles of collapse and regrowth have produced a subaerial and submarine apron of debris-avalanche, pyroclastic-flow, and other volcaniclastic deposits several times the volume of the edifice itself. The orientation of previous collapses shows a crude pattern of clockwise migration beginning on the east side. This may in part reflect the influence of the prior failure plane on collapse direction. Although future collapse is possible in any direction, the pattern of past collapses suggests that an elevated risk may exist for a future edifice failure to the northeast. The highest tsunami hazard exists from debris avalanches directed to the northeast, east, and south, where the shoreline lies only about 3.5-4.5 km from the summit. Risk to populated areas is contingent on factors including debris avalanche dynamics, thickness, volume, and emplacement direction, as well as timing with respect to Cook Inlet tides.

Siebert, L.; Beget, J.

2006-12-01

377

Multiple collapses at Mt Meru volcano, Tanzania: remote sensing and field evidences from debris avalanche deposits.  

NASA Astrophysics Data System (ADS)

Mt Meru volcano is located in the Northern Tanzanian Divergence Zone where the East African rift splits into several branches. This 4565 m-high stratovolcano overlooks the highly populated city of Arusha and is breached on the east side by a 4x5 km horse-shoe shaped valley that was attributed to landslides associated with lahars deposits (Wilkinson et al., 1986; Dawson, 2008) and a major collapse (Wilkinson et al., 1986; Roberts, 2002; Dawson, 2008). An ash cone is growing up within the collapse scar, with its last eruption occurring in 1910. Remote sensing, detailed field mapping and facies/lithology description allowed the recognition of more than two collapse events originated from the main eastern scar, as well as at least one collapse from an almost buried scar on the North East flank. No evidence of syn-collapse eruption has been observed. The high distance and large area covered by the bigger deposit up to the foot of Kilimanjaro is partly due to local interaction with water, where debris avalanche behaves like a lahar. Mt Meru has been undergoing several phases of destabilisation events during its history and can be considered as still potentially hazardous, especially with the ongoing Ash Cone growth within the scar.

Delcamp, Audray; Kwelwa, Shimba; Macheyeki, Athanas; Kervyn De Meerendre, Matthieu

2013-04-01

378

Insights into the dynamics of Mt Etna volcano from gravity and DInSar observations  

NASA Astrophysics Data System (ADS)

18-years (September 1994 - October 2011) gravity and ground deformation sequences, recorded at Etna volcano along an East-West trending profile of 19 stations on the southern flank at a quasi-monthly sampling rate, are presented. Over the last two decades, frequent fountaining events and several flank eruptions occurred at Mt Etna. We use the SBAS DInSAR technique to analyze the temporal evolution of surface displacements by inverting a sequence of interferograms to form a deformation time series. Height changes, evaluated by DInSAR data during the entire period, show modest vertical variations unable to produce significant gravity changes. However, the gravity data set was corrected for the small height variations using the experimental free-air gravity gradients measured at two stations of the profile. The residual space-time gravity image displayed some gravity increase/decrease cycles, mostly affecting the central and eastern stations of the East-West profile. We attributed these gravity cycles to mass redistribution processes mainly located at a depth of 2-4 km bsl in a region recognized to be a preferential pathway of magma rising and an intermediate zone of magma storage/withdrawal. In the latter period 2008-2011, when several paroxysmal events occurred from the South East crater, the gravity and height deformation patterns show many similarities with the previous period 1995-2000 encompassing a long series of paroxysmal episodes that preceded the violent and dramatic explosive/effusive eruptions of 2001 and 2002-2003.

Del Negro, C.; Sansosti, E.; Greco, F.; Pepe, A.; Currenti, G.; Solaro, G.; Napoli, R.; Pepe, S.; Pistorio, A.

2012-04-01

379

Volcano geodesy: The search for magma reservoirs and the formation of eruptive vents  

USGS Publications Warehouse

Routine geodetic measurements are made at only a few dozen of the world's 600 or so active volcanoes, even though these measurements have proven to be a reliable precursor of eruptions. The pattern and rate of surface displacement reveal the depth and rate of pressure increase within shallow magma reservoirs. This process has been demonstrated clearly at Kilauea and Mauna Loa, Hawaii; Long Valley caldera, California; Campi Flegrei caldera, Italy; Rabaul caldera, Papua New Guinea; and Aira caldera and nearby Sakurajima, Japan. Slower and lesser amounts of surface displacement at Yellowstone caldera, Wyoming, are attributed to changes in a hydrothermal system that overlies a crustal magma body. The vertical and horizontal dimensions of eruptive fissures, as well as the amount of widening, have been determined at Kilauea, Hawaii; Etna, Italy; Tolbachik, Kamchatka; Krafla, Iceland; and Asal-Ghoubbet, Djibouti, the last a segment of the East Africa Rift Zone. Continuously recording instruments, such as tiltmeters, extensometers, and dilatometers, have recorded horizontal and upward growth of eruptive fissures, which grew at rates of hundreds of meters per hour, at Kilauea; Izu-Oshima, Japan; Teishi Knoll seamount, Japan; and Piton de la Fournaise, Re??union Island. In addition, such instruments have recorded the hour or less of slight ground movement that preceded small explosive eruptions at Sakurajima and presumed sudden gas emissions at Galeras, Colombia. The use of satellite geodesy, in particular the Global Positioning System, offers the possibility of revealing changes in surface strain both local to a volcano and over a broad region that includes the volcano.

Dvorak, J. J.; Dzurisin, D.

1997-01-01

380

A total volatile inventory for Masaya Volcano, Nicaragua  

Microsoft Academic Search

We present results from a campaign in March 2009 to assess the current state of emissions from Masaya Volcano, Nicaragua. These results constitute one of the most comprehensive inventories to date of emissions from an active volcano and update the exceptional record of emissions from Masaya. Results from open-path Fourier transform infrared spectroscopy and filter packs demonstrate that, in terms

R. S. Martin; G. M. Sawyer; L. Spampinato; G. G. Salerno; C. Ramirez; E. Ilyinskaya; M. L. I. Witt; T. A. Mather; I. M. Watson; J. C. Phillips; C. Oppenheimer

2010-01-01

381

Photometric Observations of Aerosol Plumes From Lascar Volcano, Chile  

Microsoft Academic Search

Lascar volcano, Chile, is the most active volcano in the Central Andes region. We conducted field campaigns at Lascar during October-November 2002 and December 2004, using a visible to near infrared Microtops II sun- photometer to measure spectral optical depths in order to infer particle size distributions of volcanic aerosols in the volcanic plume. Through this method we hope to

L. A. Rodriguez; I. Watson; J. G. Viramonte; M. Poodts; A. Cabrera; A. Amigo; W. I. Rose; C. M. Oppenheimer; G. J. Bluth

2007-01-01

382

36 CFR 7.25 - Hawaii Volcanoes National Park.  

Code of Federal Regulations, 2010 CFR

...Property 1 2010-07-01 2010-07-01 false Hawaii Volcanoes National Park. 7.25 Section 7.25 Parks, Forests...REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.25 Hawaii Volcanoes National Park. (a) Fishing â(1) Commercial...

2010-07-01

383

36 CFR 7.25 - Hawaii Volcanoes National Park.  

Code of Federal Regulations, 2010 CFR

...Property 1 2009-07-01 2009-07-01 false Hawaii Volcanoes National Park. 7.25 Section 7.25 Parks, Forests...REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.25 Hawaii Volcanoes National Park. (a) Fishing â(1) Commercial...

2009-07-01

384

The hydrothermal system of Nevado del Ruiz volcano, Colombia  

Microsoft Academic Search

Hot springs and steam vents on the slopes of Nevado del Ruiz volcano provide evidence regarding the nature of hydrothermal activity within the summit and flanks of the volcano. At elevations below 3000 m, alkali-chloride water is discharged from two groups of boiling springs and several isolated warm springs on the western slope of Nevado del Ruiz. Chemical and isotopic

Neil C. Sturchio; Stanley N. Williams; Nestor P. Garcia; Adela C. Londono

1988-01-01

385

The Earthscope Plate Boundary Observatory Akutan Alaskan Volcano Network Installation  

Microsoft Academic Search

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

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

2005-01-01

386

Robust Satellite Techniques (RST) for active volcanoes monitoring  

Microsoft Academic Search

The RST (Robust Satellite Techniques) approach is a multi-temporal scheme of data analysis recently implemented in an automatic processing chain developed at IMAA-DIFA laboratories in order to monitor Italian volcanoes in near real time. In this paper some recent results of satellite monitoring of Etna and Stromboli volcanoes are presented. Preliminary results of RST implementation on SEVIRI (Spinning Enhanced Visible

Francesco Marchese; Carolina Filizzola; Giuseppe Mazzeo; Rossana Paciello; Nicola Pergola; Valerio Tramutoli

2010-01-01

387

Structural map of the summit area of Kilauea Volcano, Hawaii  

SciTech Connect

The map shows the faults, sets of fissures, eruptive vent lines and collapse features in the summit area of the volcano. It covers most of the USGS Kilauea Crater 7-1/2 minute quadrangle, together with parts of Volcano, Makaopuhi Crater, and Kau Desert 7-1/2 minute quadrangles. (ACR)

Not Available

1982-01-01

388

Volcano - An Extensible and Parallel Query Evaluation System  

Microsoft Academic Search

To investigate the interactions of extensibility and parallelism in database query processing, we have developed a new dataflow query execution system called Volcano. The Vol- cano effort provides a rich environment for research and edu- cation in database systems design, heuristics for query opti- mization, parallel query execution, and resource allocation. Volcano uses a standard interface between algebra opera- tors,

Goetz Graefe

1994-01-01

389

Highlights from a seismic broadband array on Stromboli volcano  

Microsoft Academic Search

An array of nine three-component broadband seismometers was deployed in two different configurations on Stromboli volcano. The analysis of the seismic wavefield related to volcanic explosions revealed some observations which offer a completely new insight into the internal dynamics of a volcano. These new observations are restricted to the low-frequency range below 1 Hz and underline, therefore, the superiority of

Juegen Neuberg; Richard Luckett; Maurizio Ripepe; Thomas Braun

1994-01-01

390

Sulfur Dioxide Contributions to the Atmosphere by Volcanoes  

Microsoft Academic Search

The first extensive measurements by remote-sensing correlation spectrometry of the sulfur dioxide emitted by volcanic plumes indicate that on the order of 10 3 metric tons of sulfur dioxide gas enter the atmosphere daily from Central American volcanoes. Extrapolation gives a minimum estimate of the annual amount of sulfur dioxide emitted from the world's volcanoes of about 107 metric tons.

Richard E. Stoiber; Anders Jepsen

1973-01-01

391

Stratospheric sulfate from El Chichon and the Mystery Volcano  

SciTech Connect

Stratospheric sulfate was collected by high-altitude aircraft and balloons to assess the impacts of El Chichon and an unidentified volcano on the stratosphere. The Mystery Volcano placed about 0.85 Tg of sulfate in the northern hemisphere stratosphere. El Chicon injected about 7.6 Tg sulfate into the global stratosphere.

Mroz, E.J.; Mason, A.S.; Sedlacek, W.A.

1983-09-01

392

Triggering and dynamic evolution of the LUSI mud volcano, Indonesia  

Microsoft Academic Search

Mud volcanoes are geologically important manifestations of vertical fluid flow and mud eruption in sedimentary basins worldwide. Their formation is predominantly ascribed to release of overpressure from clay- and organic-rich sediments, leading to impressive build-up of mud mountains in submarine and subaerial settings. Here we report on a newly born mud volcano appearing close to an active magmatic complex in

A. Mazzini; H. Svensen; G. G. Akhmanov; G. Aloisi; S. Planke; A. Malthe-Sørenssen; B. Istadi

2007-01-01

393

Rapid Deformation of the South Flank of Kilauea Volcano, Hawaii  

Microsoft Academic Search

The south flank of Kilauea volcano has experienced two large [magnitude (M) 7.2 and M 6.1] earthquakes in the past two decades. Global Positioning System measurements conducted between 1990 and 1993 reveal seaward displacements of Kilauea's central south flank at rates of up to about 10 centimeters per year. In contrast, the northern side of the volcano and the distal

Susan Owen; Paul Segall; Jeff Freymueller; Asta Miklius; Roger Denlinger; Thora Arnadottir; Maurice Sako; Roland Burgmann

1995-01-01

394

Tsunami wave generation by the eruption of underwater volcano  

Microsoft Academic Search

Eruption of volcanoes represents one of important origins of tsunami waves and is responsible for most catastrophic tsunami (Krakatau, 1883; Thira, BC). The products of volcano eruption include solids, liquids (lava) and gases. The present article presents hydrodynamic model of relatively slow process of eruption, with domination of liquids. The process of underwater eruption of lava causes the disturbance of

Y. Egorov

2007-01-01

395

Using Google Earth to Study the Basic Characteristics of Volcanoes  

ERIC Educational Resources Information Center

|Landforms, natural hazards, and the change in the Earth over time are common material in state and national standards. Volcanoes exemplify these standards and readily capture the interest and imagination of students. With a minimum of training, students can recognize erupted materials and types of volcanoes; in turn, students can relate these…

Schipper, Stacia; Mattox, Stephen

2010-01-01

396

Sulphur dioxide fluxes from Papua New Guinea's volcanoes  

Microsoft Academic Search

Papua New Guinea (PNG) hosts some of the most prolific degassing volcanoes in the world. Collectively, they are thought to be responsible for a significant contribution of sulfur dioxide to the regional and global atmosphere. Despite their importance, very few measurements of SO2 fluxes from PNG volcanoes have been made in the past, leading to uncertainty in estimates of total

A. J. S. McGonigle; C. Oppenheimer; V. I. Tsanev; S. Saunders; K. Mulina; S. Tohui; J. Bosco; J. Nahou; J. Kuduon; F. Taranu

2004-01-01

397

Flank spreading and collapse of weak-cored volcanoes  

Microsoft Academic Search

Volcanoes subjected to hydrothermal activity develop weak cores as a result of alteration and due to elevated pore pressures. Edifices constructed at the angle of repose of volcanoclastics, or at even more gentle slopes, respond to internal weakening by initially deforming slowly, but may then collapse catastrophically. Such a process has so far been described for only a few volcanoes,

Emmanuelle Cecchi; Benjamin van Wyk de Vries; Jean-Marc Lavest

2004-01-01

398

Ocean currents at Axial Volcano, a northeastern Pacific seamount  

Microsoft Academic Search

Axial Volcano is a magmatically active seamount that straddles the Juan de Fuca Ridge (JdFR). With a summit depth of ~1400 m, the volcano intercepts deep ocean flows at a height well above that of the linear ridge adjoining it to the north and south. Multiyear, yearlong observations of currents at Axial show that mean flow circles the seamount in

J. W. Lavelle; E. T. Baker; G. A. Cannon

2003-01-01

399

Mercury and halogen emissions from Masaya and Telica volcanoes, Nicaragua  

Microsoft Academic Search

We report measurements of Hg, SO2, and halogens (HCl, HBr, HI) in volcanic gases from Masaya volcano, Nicaragua, and gaseous SO2 and halogens from Telica volcano, Nicaragua. Mercury measurements were made with a Lumex 915+ portable mercury vapor analyzer and gold traps, while halogens, CO2 and S species were monitored with a portable multi gas sensor and filter packs. Lumex

M. L. I. Witt; T. A. Mather; D. M. Pyle; A. Aiuppa; E. Bagnato; V. I. Tsanev

2008-01-01

400

Common characteristics of paired volcanoes in northern Central America  

Microsoft Academic Search

Four pairs of active volcanoes along the northern Central American volcanic front have erupted basalt-andesite magmas that show consistent intrapair behavioral and compositional differences. These differences are found in records of volcanic activity and complete major and minor element data on over 200 samples. From northwest to southeast along the volcanic front the four volcano pairs are Cerro Quemado-Santa Maria.

Sid P. Halsor; William I. Rose

1988-01-01

401

Sunset Crater Volcano National Monument - Nature and Science  

NSDL National Science Digital Library

This National Park Service (NPS) website highlights the natural resources of Sunset Crater Volcano National Monument. Topics covered include the geologic history of the area, threatened and endangered species, geologic activity, geologic formations, soils, seeps and springs, and volcanoes and lava flows. There are links for more information on the Colorado Plateau and other lava fields.

402

36 CFR 7.25 - Hawaii Volcanoes National Park.  

Code of Federal Regulations, 2013 CFR

...Public Property 1 2013-07-01 2013-07-01 false Hawaii Volcanoes National Park. 7.25 Section 7.25 Parks...REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.25 Hawaii Volcanoes National Park. (a) Fishing â(1)...

2013-07-01

403

Exploring Means of Determining Surface Deformation at Augustine Volcano  

Microsoft Academic Search

The recent January 2006 eruption of Augustine Volcano followed a nearly a year of increased seismic activity, that has been actively monitored by the Alaska Volcano Observatory (AVO). The eruption has generated a topographical signal that GPS ground stations were able to monitor. This work addresses the question as to which other techniques are able to see this deformation. While

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

2006-01-01

404

Observations of a nuée ardente from the St. Augustine volcano  

Microsoft Academic Search

A series of aerial photographs were obtained for a nuée ardente produced by the February 8, 1976 eruption of the St. Augustine volcano, Alaska. The nuée ardente reached a maximum velocity of 50 m s-1 while descending the steeper (~1:3) slope of the volcano. It later slowed to a velocity of 6 m s-1 as it traversed the gentler slope

Jeffrey L. Stith; Peter V. Hobbs; Lawrence F. Radke

1977-01-01

405

Cyclic formation of debris avalanches at Mount St Augustine volcano  

Microsoft Academic Search

VOLCANIC debris avalanches have been seen at many volcanoes since the 1980 eruption of Mount St Helens, but typically only one or two avalanche deposits are identified at each eruptive centre, suggesting that catastrophic slope failures are rare or even unique events in the lifetime of a volcano1-4 Here we present a series of radiocarbon dates from volcanic deposits showing

James E. Begét; Juergen Kienle

1992-01-01

406

Search for shallow magma accumulations at Augustine Volcano  

Microsoft Academic Search

A search was made for shallow magma accumulations beneath Augustine Volcano using primarily three geophysical techniques: (1) temperature and heat flow measurements, (2) active and passive seismic refraction, and (3) three-dimensional modeling of aeromagnetic data. With these studies it was hoped to gain insight into the interval structure of Augustine Volcano, to delineate, if possible, the size and shape of

J. Kienle; D. J. Lalla; C. F. Pearson; S. A. Barrett

1979-01-01

407

Monitoring Popocatepetl volcano's glaciers (Mexico): case study of glacier extinction  

Microsoft Academic Search

Popocatépetl volcano is located 60 km southeast of Mexico City and is one of the three ice-clad volcanoes in Mexico. The two glaciers of Popocatépetl became extinct after a strong retreat due to the combination of at least three causes: global change, change in regional meteorological conditions (induced by the vicinity to highly polluted areas) and local enforcement (namely volcanic

H. Delgado; P. Julio; C. Huggel; M. Brugman

2003-01-01

408

January 2002 volcano-tectonic eruption of Nyiragongo volcano, Democratic Republic of Congo  

Microsoft Academic Search

In January 2002, Nyiragongo volcano erupted 14-34 × 106 m3 of lava from fractures on its southern flanks. The nearby city of Goma was inundated by two lava flows, which caused substantial socioeconomic disruption and forced the mass exodus of the population, leaving nearly 120,000 people homeless. Field observations showed marked differences between the lava erupted from the northern portion

D. Tedesco; O. Vaselli; P. Papale; S. A. Carn; M. Voltaggio; G. M. Sawyer; J. Durieux; M. Kasereka; F. Tassi

2007-01-01

409

January 2002 volcano-tectonic eruption of Nyiragongo volcano, Democratic Republic of Congo  

Microsoft Academic Search

In January 2002, Nyiragongo volcano erupted 14–34 × 106 m3 of lava from fractures on its southern flanks. The nearby city of Goma was inundated by two lava flows, which caused substantial socioeconomic disruption and forced the mass exodus of the population, leaving nearly 120,000 people homeless. Field observations showed marked differences between the lava erupted from the northern portion

D. Tedesco; O. Vaselli; P. Papale; S. A. Carn; M. Voltaggio; G. M. Sawyer; J. Durieux; M. Kasereka; F. Tassi

2007-01-01

410

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

Microsoft Academic Search

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

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

2006-01-01

411

A Principal Component Analysis of Hawaiian Volcanoes Deformation  

NASA Astrophysics Data System (ADS)

We use Principal Component Analysis (PCA) with mode rotation (Kawamura and Yamaoka, 2006) to analyze ground deformation at Kilauea and Mauna Loa volcanoes, Hawaii. A changing pattern of deformation at the summit and flanks of Mauna Loa, revealed by 13 years (1996-2008) of campaign GPS measurements, was analyzed. Two modes of deformation can explain ~98% of the data at Mauna Loa. The first mode records summit inflation which can be modeled by an inflating dike and a Mogi source ~6 km beneath the summit caldera. Summit deformation as revealed by the temporal mode does not begin until 2002, and has recently slowed. The second mode records flank deformation which can be modeled by slip on the basal décollement between Mauna Loa and Kilauea. Flank deformation occurs between 1996 and 2002 after which deformation of the flank ceases. The lack of flank deformation after 2002 suggests volcanic spreading at Mauna Loa is not steady and may be decoupled from summit activity. Eleven years (1998-2009) of continuous GPS data at Kilauea were analyzed. We find modes of deformation at Kilauea which represent episodic east rift zone intrusions, movement of magma beneath the summit and rift zones, and motion of the south flank associated with slow-slip events. The spatial density of stations is insufficient to distinguish individual events (such as the 1999 and 2007 intrusions) spatially, but these events are recorded in the temporal modes. Principal component analysis with mode rotation is a useful tool which can illuminate deformation due to multiple sources and improve detection of subtle transient events.

Sinnett, D. K.; Segall, P.

2009-12-01

412

Earthquake-volcano interaction imaged by coda wave interferometry  

NASA Astrophysics Data System (ADS)

Large earthquakes are often assumed to influence the eruptive activity of volcanoes. A major challenge to better understand the causal relationship between these phenomena is to detect and image, in detail, all induced changes, including subtle, non-eruptive responses. We show that coda wave interferometry can be used to image such earthquake-induced responses, as recorded at Yasur volcano (Vanuatu) following a magnitude 7.3 earthquake which occurred 80 km from its summit. We use repeating Long-Period events to show that the earthquake caused a sudden seismic velocity drop, followed by a slow partial recovery process. The spatial distribution of the response amplitude indicates an effect centered on the volcano. Our result demonstrates that, even if no major change in eruptive activity is observed, volcanoes will be affected by the propagation of large amplitude seismic waves through their structure, suggesting that Earthquake-volcano interaction is likely a more common phenomenon than previously believed.

Battaglia, Jean; Métaxian, Jean-Philippe; Garaebiti, Esline

2012-06-01

413

A Submarine Perspective on Hawaiian Volcanoes  

NASA Astrophysics Data System (ADS)

Postwar improvements in navigation, sonar-based mapping, and submarine photography enabled the development of bathymetric maps, which revealed submarine morphologic features that could be dredged or explored and sampled with a new generation of manned and unmanned submersibles. The maps revealed debris fields from giant landslides, the great extent of rift zones radiating from volcanic centers, and two previously unknown submarine volcanoes named Mahukona and Loihi, the youngest Hawaiian volcano. About 70 major landslides cover half the flanks of the Hawaiian Ridge out to Midway Island. Some of the landslides attain lengths of 200 km and have volumes exceeding 5,000 km3. More recent higher resolution bathymetry and sidescan data reveal that many submarine eruptions construct circular, flat-topped, monogenetic cones; that large fields of young strongly alkalic lava flows, such as the North Arch and South Arch lava fields, erupt on the seafloor within several hundred km of the islands; and that alkalic lavas erupt during the shield stage on Kilauea and Mauna Loa. The North Arch flow field covers about 24,000 km2, has an estimated volume between about 1000 and 1250 km3, has flows as long as 108 km, and erupted from over 100 vents. The source and melting mechanisms for their production is still debated. The maps also displayed stair-step terraces, mostly constructed of drowned coral reefs, which form during early rapid subsidence of the volcanoes during periods of oscillating sea level. The combination of scuba and underwater photography facilitated the first motion pictures of the mechanism of formation of pillow lava in shallow water offshore Kilauea. The age progression known from the main islands was extended westward along the Hawaiian Ridge past Midway Island, around a bend in the chain and northward along the Emperor Seamounts. Radiometric dating of dredged samples from these submarine volcanoes show that the magma source that built the chain has been active for over 80 Ma and established the remarkable linearity of the age-progression along the chain. Glass rinds on submarine lava quenched at depth contain initial magmatic volatiles and yield data on the juvenile water, sulfur, CO2, and rare gas contents of basaltic magmas, and continue to reveal nuances of the volatile contents of lava. Rock sampling at Loihi Seamount led to the discovery of the pre-shield alkalic phase of Hawaiian volcanism, which mirrors the well-known post-shield alkalic phase. Lava compositions from the Hawaiian Ridge and Emperor Seamounts have clear affinities to present-day Hawaiian lavas, but subtle source differences as well. The progression from small to large and back to small degrees of melting at individual volcanoes and the compositional changes along the chain constrain the melting processes and source compositions of Hawaiian volcanism. Coupling the age of lavas with that of submerged coral reefs has provided data on the growth and subsidence of volcanic centers. This information has meshed nicely with the age, composition, and morphology of lavas from the 3.2-km-deep Hawaiian Scientific Drill Hole. Submarine studies have taught us much about the workings of Hawaiian Volcanoes, and in the process have stimulated new work and concepts on marine volcanism worldwide.

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

2011-12-01

414

Diversity and spatial distribution of prokaryotic communities along a sediment vertical profile of a deep-sea mud volcano.  

PubMed

We investigated the top 30-cm sediment prokaryotic community structure in 5-cm spatial resolution, at an active site of the Amsterdam mud volcano, East Mediterranean Sea, based on the 16S rRNA gene diversity. A total of 339 and 526 sequences were retrieved, corresponding to 25 and 213 unique (?98% similarity) phylotypes of Archaea and Bacteria, respectively, in all depths. The Shannon-Wiener diversity index H was higher for Bacteria (1.92-4.03) than for Archaea (0.99-1.91) and varied differently between the two groups. Archaea were dominated by anaerobic methanotrophs ANME-1, -2 and -3 groups and were related to phylotypes involved in anaerobic oxidation of methane from similar habitats. The much more complex Bacteria community consisted of 20 phylogenetic groups at the phylum/candidate division level. Proteobacteria, in particular ?-Proteobacteria, was the dominant group. In most sediment layers, the dominant phylotypes of both the Archaea and Bacteria communities were found in neighbouring layers, suggesting some overlap in species richness. The similarity of certain prokaryotic communities was also depicted by using four different similarity indices. The direct comparison of the retrieved phylotypes with those from the Kazan mud volcano of the same field revealed that 40.0% of the Archaea and 16.9% of the Bacteria phylotypes are common between the two systems. The majority of these phylotypes are closely related to phylotypes originating from other mud volcanoes, implying a degree of endemicity in these systems. PMID:21538105

Pachiadaki, Maria G; Kallionaki, Argyri; Dählmann, Anke; De Lange, Gert J; Kormas, Konstantinos Ar

2011-05-03

415

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

NASA Astrophysics Data System (ADS)

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

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

2004-12-01

416

Rockfalls, Avalanches and Landslides at Augustine Volcano, 2003-2006  

NASA Astrophysics Data System (ADS)

Rockfalls, avalanches, and landslides have been frequently recorded in seismic data at Augustine Volcano for many years. Typical years, such as 2003 or 2004, had several dozen such events that were strong enough to trigger the automatic event detection system. Seventeen rockfalls occurred in 2003, mostly in late summer when air temperatures were highest. In 2004, 28 events occurred -- also in late summer. Typical events lasted about 30 sec, had frequencies greater than 6 Hz, and were well recorded on summit stations, suggesting that they were rockfalls from the steep summit dome into the adjacent moat area. In 2005, both the rate and the occurrence pattern changed. Rockfall activity began in April 2006 and continued through fall and early winter, after peaking in May and June. Overall there were more than 340 rockfalls in 2005, including both small and large events. The 2005 rockfall activity increased at nearly the same time as both earthquake activity and ground heating, suggesting that higher temperatures and steaming contributed to mechanical instabilities of the surface dome rocks. We examined relative amplitudes and frequency contents at station pairs to determine relative locations of the rockfalls by assuming both higher amplitudes and higher frequencies are associated with events closer to a given station. When a low-light camera was installed at Augustine in January 2006, we were able to confirm these relations because of the clear correlation between rockfalls, debris flows, and pyroclastic flows to the east (towards the camera) and higher amplitudes and frequencies at east station AUE. Other events had higher amplitudes and frequencies at west station AUW with no material seen moving eastward. Still other events moved towards the north, with amplitudes being nearly equivalent at both AUE and AUW. Compound events also occurred, with mass flow in several directions simultaneously. As the new steep-sided and unstable dome grew in spring 2006, rockfalls and related signals dominated the seismograms. The systematic patterns in amplitude and frequency, verified by data form the low-light camera, make it possible to estimate mass flow in various directions using seismic data. This work is in progress and will be compared with geologic maps of deposits from the 2006 eruptions. The increased rockfall rate of 2005 is a new class of precursory signal that may be incorporated into long-term monitoring strategies at Augustine and elsewhere.

Deroin, N.; McNutt, S. R.; Reyes, C.; Sentman, D. D.

2006-12-01

417

Environmental assessment of 1991 Hudson volcano eruption ashfall effects on southern Patagonia region, Argentina  

NASA Astrophysics Data System (ADS)

The August 1991 eruption of the Hudson volcano in the southern Andean volcanic zone affected an area of 1000 km in radius to the east in the Argentine Patagonic meseta. The thickness of ash ranged from 20 cm in the Andean area to less than 1 mm in the Atlantic coast zone. Wind storms reactivated the ash deposits, together with terrigenous material, more than one year after the eruption. In order to assess the potential risk of the ash, analyses of concentration, size, mineralogical composition, toxic elements, and irritating effects of gases were performed. In all samples, the percentage of particles of the 2-to 5-?m range is below the toxic threshold level. Trace elements are below the toxic threshold concentration for humans and animals. The major impact of the ashfall was on sheep herds; about one third of them were lost in the areas close to the volcano. Soil incorporated the ash layers, and a fast recovery of orchards was reported two years later. Rivers were loaded with sediment in the immediate aftermath, but one year later returned to previous conditions. Along the shores of the Buenos Aires Lake, a fresh tephra layer can be distinguished.

Inbar, M.; Ostera, H. A.; Parica, C. A.; Remesal, M. B.; Salani, F. M.

1995-03-01

418

Geometry and kinematics of the fault systems controlling the unstable flank of Etna volcano (Sicily)  

NASA Astrophysics Data System (ADS)

An updated tectonic framework of Etna's unstable flank has been defined as a result of multidisciplinary analyses carried out by integrating geological and geophysical data. The different typologies of datasets have been analyzed and correlated in order to constrain the geometry and kinematics of the fault systems controlling the unstable flank of Etna volcano and to better understand their complex relationship with the offshore morphostructures of the continental margin. In particular, we have considered as the main structural elements the following four fault systems: Pernicana, Ragalna, Tremestieri-Trecastagni and Timpe. Slip-rates and kinematics have been estimated in both long- and short-terms, respectively, from geological and seismotectonic/geodetic data. Data integration has allowed defining five kinematic domains in the sliding flank of Etna: (1) the NE block, bordered by the Pernicana fault and characterised by the highest deformation velocities; ground velocity progressively diminishes toward South, with a clockwise rotation of the vectors defining (2) the block embracing the central part of the Timpe system; (3) the Giarre wedge; (4) the Medium-East block, bounded by the S. Tecla and Trecastagni faults; and (5) the SE block bordered, by the hidden Belpasso-Ognina tectonic lineament. The dynamics of these blocks takes place through discontinuous movements: sudden short-term accelerations related to the magma intrusion are superimposed to a fairly constant mid-term ESE sliding. The proposed comprehensive model of the unstable flank provides the basic input parameters for applying analytical models to flank dynamics of Etna volcano.

Azzaro, R.; Bonforte, A.; Branca, S.; Guglielmino, F.

2013-02-01

419

VALVE: Volcano Analysis and Visualization Environment  

NASA Astrophysics Data System (ADS)

Modern volcano observatories collect data using a wide variety of instruments. Visualizing these disparate data on a common time base is critical to interpreting and reacting to geophysical changes. With this in mind, the Hawaiian Volcano Observatory (HVO) created Valve, the Volcano Analysis and Visualization Environment. Valve integrates a wide range of both continuous and discontinuous data sources into a common, internet web-browser based interface that allows scientists to interactively select and visualize these data on a common time base and, if appropriate, in three dimensions. Advances in modern internet browser technology allow for a truly interactive user-interface experience that could previously only be found in stand-alone applications--all while maintaining client platform independence and network portability. This system aids more traditional in-depth analysis by providing a common front-end to retrieving raw data. In most cases, the raw data are being served from an SQL database, a system that lends itself to quickly retrieving, logically arranging, and safely storing data. Beyond Valve's visualization capabilities, the system also provides a variety of tools for time series analysis and source modeling. For example, a user could load several tilt and GPS time series, estimate co-seismic or co-intrusive deformation, and then model the event with an elastic point source or dislocation. From the source model, Coulomb stress changes could be calculated and compared to pre- and post-event hypocenter distribution. Employing a heavily object-oriented design, Valve is easily extensible, modular, portable, and remarkably cost efficient. Quickly visualizing arbitrary data is a trivial matter, while implementing methods for permanent, continuous data streams requires only minimal programming. Portability is ensured by using software that is readily available on a wide variety of operating systems; cost efficiency is achieved by using software that is open-source and/or available free of charge.

Cervelli, D. P.; Cervelli, P.; Miklius, A.; Krug, R.; Lisowski, M.

2002-12-01

420

A GIS-based Spatial Analysis of Volcanoes in the Central Andes: Insights Into Factors Controlling Volcano Spacing  

Microsoft Academic Search

Volcano spacing has received little attention since the mid-70's when studies undertaken by Vogt (1974; EPSL) and then Marsh (1979; J Geol) suggested a regular spacing of volcanoes in arcs that ranged from 50 to 75 km for different arcs. The spacing was thought to be influenced by the thickness of the lithosphere or gravitational (Rayleigh-Taylor) instabilities related to source

S. S. Savant; S. L. de Silva

2005-01-01

421

Relating volcano morphometry to the developmental progression of Hawaiian shield volcanoes through slope and hypsometric analyses of SRTM data  

Microsoft Academic Search

We calculated average and median slope values and produced hypsometric curves for the subaerial Hawaiian shield volcanoes using Shuttle Radar Topography Mission (SRTM) digital elevation models. The SRTM-derived average and median slope values display similar trends to published results based on other topographic data products, showing an increase in slope relative to volcano age. Shadows in the radar data over

Jacob E. Bleacher; Ronald Greeley

2008-01-01

422

Volcano-seismic Signal Detection and Classification Processing using Hidden Markov Models. Application to San Cristóbal Volcano, Nicaragua  

Microsoft Academic Search

We present a method for automatic seismic event detection and classification, focusing on volcanic-seismic signals by means of the validity of the hidden Markov modeling (HMM) method in active volcanoes. Recordings of different seismic event types are studied at one active volcano; San Cristobal in Nicaragua. We use data from one field surveys carried out in February to March 2006.

Ligdamis A. Gutiérrez; Jesús Ibañéz; Guillermo Cortés; Javier Ramírez; M. Carmen Benítez; Virginia Tenorio; Isaac Álvarez

2009-01-01

423

The Effects of Persistently Degassing Volcanoes on the Natural Environment as Exemplified by Kilauea, Masaya and Poás Volcanoes  

Microsoft Academic Search

While the effects on the global environment of large volcanic eruptions have been frequently studied, there has been little work on the impact of lower tropospheric emissions from persistently degassing volcanoes. In contrast to large volcanic eruptions which may have a short term but hemispheric\\/global effect (through injection of gas and ash into the stratosphere), persistently degassing volcanoes can have

G. Williams-Jones; L. Flynn; A. J. Harris; B. Gibson; P. J. Mouginis-Mark

2002-01-01

424

Galactic Super-volcano in Action  

NASA Astrophysics Data System (ADS)

A galactic "super-volcano" in the massive galaxy M87 is erupting and blasting gas outwards, as witnessed by NASA's Chandra X-ray Observatory and NSF's Very Large Array. The cosmic volcano is being driven by a giant black hole in the galaxy's center and preventing hundreds of millions of new stars from forming. Astronomers studying this black hole and its effects have been struck by the remarkable similarities between it and a volcano in Iceland that made headlines earlier this year. At a distance of about 50 million light years, M87 is relatively close to Earth and lies at the center of the Virgo cluster, which contains thousands of galaxies. M87's location, coupled with long observations over Chandra's lifetime, has made it an excellent subject for investigations of how a massive black hole impacts its environment. "Our results show in great detail that supermassive black holes have a surprisingly good control over the evolution of the galaxies in which they live," said Norbert Werner of the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University and the SLAC National Accelerator Laboratory, who led one of two papers describing the study. "And it doesn't stop there. The black hole's reach extends ever farther into the entire cluster, similar to how one small volcano can affect practically an entire hemisphere on Earth." The cluster surrounding M87 is filled with hot gas glowing in X-ray light, which is detected by Chandra. As this gas cools, it can fall toward the galaxy's center where it should continue to cool even faster and form new stars. However, radio observations with the Very Large Array suggest that in M87 jets of very energetic particles produced by the black hole interrupt this process. These jets lift up the relatively cool gas near the center of the galaxy and produce shock waves in the galaxy's atmosphere because of their supersonic speed. The scientists involved in this research have found the interaction of this cosmic "eruption" with the galaxy's environment to be very similar to that of the Eyjafjallajokull volcano, which forced much of Europe to close its airports earlier this year. With Eyjafjallajokull, pockets of hot gas blasted through the surface of the lava, generating shock waves that can be seen passing through the grey smoke of the volcano. The hot gas then rises up in the atmosphere, dragging the dark ash with it. This process can be seen in a movie of the Eyjafjallajokull volcano where the shock waves propagating in the smoke are followed by the rise of dark ash clouds into the atmosphere. In the analogy with Eyjafjallajokull, the energetic particles produced in the vicinity of the black hole rise through the X-ray emitting atmosphere of the cluster, lifting up the coolest gas near the center of M87 in their wake, much like the hot volcanic gases drag up the clouds of dark ash. And just like the volcano here on Earth, shockwaves can be seen when the black hole pumps energetic particles into the cluster gas. "This analogy shows that even though astronomical phenomena can occur in exotic settings and over vast scales, the physics can be very similar to events on Earth," said co-author Aurora Simionescu also of the Kavli Institute. In M87, the plumes of cooler gas being lifted upwards contain as much mass as all of the gas contained within 12,000 light years of the center of the galaxy cluster. This shows the black hole-powered volcano is very efficient at blasting the galaxy free of the gas that would otherwise cool and form stars. "This gas could have formed hundreds of millions of stars if the black hole had not removed it from the center of the galaxy. That seems like a much worse disruption than what the airline companies on Earth had to put up with earlier this year," said Evan Million, a graduate student at Stanford University and lead-author of the other paper to be published about this deep study of M87. The eruption in M87 that lifted up the cooler gas must have occurred about 150 million years earlie

2010-08-01

425

Publications of the Volcano Hazards Program 2011  

USGS Publications Warehouse

The Volcano Hazards Program of the U.S. Geological Survey (USGS) is part of the Geologic Hazards Assessments subactivity, as funded by Congressional appropriation. Investigations are carried out by the USGS and with cooperators at the Alaska Division of Geological and Geophysical Surveys, University of Alaska Fairbanks Geophysical Institute, University of Hawaii Manoa and Hilo, University of Utah, and University of Washington Geophysics Program. This report lists publications from all these institutions. Only published papers and maps are included here; abstracts presented at scientific meetings are omitted. Publication dates are based on year of issue, with no attempt to assign them to fiscal year.

Nathenson, Manuel

2013-01-01

426

The Reawakening of Alaska's Augustine Volcano  

NASA Astrophysics Data System (ADS)

Augustine volcano, in south central Alaska, ended a 20-year period of repose on 11 January 2006 with 13 explosive eruptions in 20 days. Explosive activity shifted to a quieter effusion of lava in early February, forming a new summit lava dome and two short, blocky lava flows by late March (Figure 1). The eruption was heralded by eight months of increasing seismicity, deformation, gas emission, and small phreatic eruptions, the latter consisting of explosions of steam and debris caused by heating and expansion of groundwater due to an underlying heat source.

Power, John A.; Nye, Christopher J.; Coombs, Michelle L.; Wessels, Rick L.; Cervelli, Peter F.; Dehn, John; Wallace, Kristi L.; Freymueller, Jeffery T.; Doukas, Michael P.

2006-09-01

427

Volcano and Hydrologic Hazards, Features, and Terminology  

NSDL National Science Digital Library

This web site is a good place to start for anyone seeking information on the geology and management of natural hazards phenomena related to volcanoes and hydrologic and geothermal processes. Some information is included on landslides, earthquakes, faults, and tsunamis. In addition to a brief definition of the terms, the site provides background information on related terms; maps, graphics and images; items of interest - reports and case studies; and additional U. S. Geological Survey publications, abstracts, and fact sheets. Web sites of other agencies and other regional or global organizations responsible for monitoring and managing natural hazards are linked.

428

Tectonic Setting of Active Costa Rican Volcanoes  

NSDL National Science Digital Library

This 3D visualization provides the tectonic context for volcanic activity in Costa Rica. Active volcanoes are confined to northern Costa Rica because the subducted Cocos plate is relatively deep there. In contrast, almost no volcanic activity happens in the south because of processes directly or indirectly related to the subduction of the Cocos Ridge. Funding for this visualization was provided by the NASA Earth Observing System Higher Education Alliance. For more information, see http://gsdidocs.org/gsdiconf/GSDI-9/papers/TS57.3paper.pdf

Abolins, Mark

429

Shallow magma accumulation at K??lauea Volcano, Hawai'i, revealed by microgravity surveys  

USGS Publications Warehouse

Using microgravity data collected at K??lauea Volcano, Hawai'i (United States), between November 1975 and January 2008, we document significant mass increase beneath the east margin of Halema'uma'u Crater, within K??lauea's summit caldera. Surprisingly, there was no sustained uplift accompanying the mass accumulation. We propose that the positive gravity residual in the absence of significant uplift is indicative of magma accumulation in void space (probably a network of interconnected cracks), which may have been created when magma withdrew from the summit in response to the 29 November 1975 M = 7.2 south flank earthquake. Subsequent refilling documented by gravity represents a gradual recovery from that earthquake. A new eruptive vent opened at the summit of K??lauea in 2008 within a few hundred meters of the positive gravity residual maximum, probably tapping the reservoir that had been accumulating magma since the 1975 earthquake. ?? 2010 Geological Society of America.

Johnson, D. J.; Eggers, A. A.; Bagnardi, M.; Battaglia, M.; Poland, M. P.; Miklius, A.

2010-01-01

430

Shallow magma accumulation at Kilauea Volcano, Hawai'i, revealed by microgravity surveys  

USGS Publications Warehouse

Using microgravity data collected at Kilauea Volcano, Hawai'i (United States), between November 1975 and January 2008, we document significant mass increase beneath the east margin of Halema'uma'u Crater, within Kilauea's summit caldera. Surprisingly, there was no sustained uplift accompanying the mass accumulation. We propose that the positive gravity residual in the absence of significant uplift is indicative of magma accumulation in void space (probably a network of interconnected cracks), which may have been created when magma withdrew from the summit in response to the 29 November 1975 M = 7.2 south flank earthquake. Subsequent refilling documented by gravity represents a gradual recovery from that earthquake. A new eruptive vent opened at the summit of Kilauea in 2008 within a few hundred meters of the positive gravity residual maximum, probably tapping the reservoir that had been accumulating magma since the 1975 earthquake.

Johnson, David J.; Eggers, Albert A.; Bagnardi, Marco; Battaglia, Maurizio; Poland, Michael P.; Miklius, Asta

2010-01-01

431

OPERATIONAL USE OF INSAR FOR VOLCANO OBSERVATORIES: EXPERIENCE IN LOCAL RECEPTION AT MONTSERRAT  

Microsoft Academic Search

A volcano observatory that is monitoring an erupting volcano(es) needs as much relevant data as it can get in a timely manner. InSAR has, potentially, a major role to play in delivering information on ground deformation and topographic change that can feed into the crisis management process. The Montserrat Volcano Observatory (MVO) has been observing the ongoing eruption of the

G. Wadge; L. Cabey; S. Lomas-Clarke; M. D. Palmer; A. Smith

432

Volcanic hazard map for Telica, Cerro Negro and El Hoyo volcanoes, Nicaragua  

Microsoft Academic Search

A volcano hazard study was conducted for Telica, Cerro Negro and El Hoyo volcanoes, Nicaragua, based on geological and volcanological field investigations, air photo analyses, and numerical eruption simulation. These volcanoes are among the most active volcanoes of the country. This study was realized 2004-2006 through technical cooperation of Japan International Cooperation Agency (JICA) with INETER, upon the request of

T. Asahina; M. Navarro; W. Strauch

2007-01-01

433

A Volcano Population Index for Estimating Relative Risk With Example Data From Central America  

Microsoft Academic Search

We have developed a Volcano Population Index (VPI) to make objective comparisons among individual volcanoes of populations that may be subject to volcanic hazards. We used volcano location data from the Smithsonian's Global Volcanism Program (GVP) with the LandScan 2001 gridded global population data base from the Oak Ridge National Laboratory to evaluate population distribution near potentially active volcanoes in

J. W. Ewert; C. J. Harpel

2003-01-01

434

Aeromagnetic and Resistive Evidence for a Concealed Depression Associated with a Past Flank Collapse of Fuji Volcano, Central Japan  

NASA Astrophysics Data System (ADS)

Two helicopter-borne aeromagnetic surveys were conducted over Fuji Volcano, central Japan in 2003 and 2007 to better understand the subsurface structure of the volcano. The surveys were flown at an altitude of 150 m above terrain along north-south survey lines and east-west tie lines, spaced 200 - 250 m and 1,000 m respectively. The compiled high-resolution aeromagnetic anomaly map of the volcano clearly showed the heterogeneity of the subsurface structure of the volcano. The most significant characteristic is a pair of magnetic high and low elongated in the east-west direction, which ranges from the east-southeast of the summit crater to the eastern flank with an altitude of approximately 2,000 m above sea level or higher. Although there is no evidence on the surface to explain the anomaly, the aeromagnetic anomaly map implies the existence of subsurface structures such as a depression which contains thick lava accumulation overlain by pyroclastic rocks. This depression might be caused by a past flank collapse which triggered a debris avalanche such as the Gotemba Debris Avalanche of 2,900 yBP. Magnetic modeling for the anomaly was conducted to constrain the subsurface structure of the area. First, the horizontal dimension of the magnetic structure was assumed from the results of apparent magnetization intensity mapping. Then, the thickness of the structure was determined by a comparison between observed and synthetic magnetic anomalies by trial and error. The optimum model has a thickness of 400 m on the basis of the rock magnetic properties of volcanic rocks sampled from the volcano. Audio-frequency Magnetotelluric (AMT) surveys were conducted in 2008 and 2009 to confirm the buried structure suggested by the magnetic modeling. Measurements were performed at 9 sites each along two north-south profiles traversing the magnetic anomaly at altitudes of 2,100 m and 2,700 m, respectively. Induction vectors at all the sites point to the west, implying the existence of a conductor in the direction of the summit of the volcano. Preliminary 2-D inversion was done using the TM mode apparent resistivities, TM mode phases and TE mode phases. A resistivity model obtained shows subsurface specific resistive and conductive features down to the sea level. The two resistivity cross-sections indicate a shallow resistive layer of approximately 1,000 m in thickness underlain by a deep conductive layer. The shallow resistive layer and deep conductive layer are implied to correspond to products of Shin-Fuji (Younger Fuji) and Ko-Fuji (Older Fuji) Volcanoes, respectively. A U-shaped depression of the lower conductive layer was found in the upper cross-section at an altitude of 2,700 m, supporting the volcanic depression suggested by the magnetic modeling.

Okuma, S.; Nakatsuka, T.; Takakura, S.; Matsushima, N.; Nakano, S.

2010-12-01

435

3D Velocity and Hypocentre Distribution About a Cone-Volcano: Mt Taranaki, New Zealand  

NASA Astrophysics Data System (ADS)

Mt Taranaki is a 2518 m andesite cone-volcano (last eruption AD1755) within an oil-bearing sedimentary basin approximately 50 km west of the deepest part of the Benioff zone beneath the North Island of New Zealand. It is the most recent of a series of volcanoes that have erupted in the Taranaki region in the last 1.7 million years. Although a permanent six-station seismic network monitors Mt Taranaki for signs of unrest, little is known of the structure at the depths earthquakes occur and magma maybe stored. This information is vital for interpreting precursors to any future eruption. For nine months in 2001-2002, a temporary network of 75 three-component, broadband (0.03 - 50 Hz) seismographs (area c. 100 km by 100 km) was used to collect data to image crustal structure and accurately locate earthquakes in the Taranaki region. Three hundred and eighty-nine earthquakes were located using more than 15,000 phase picks (55% P and 45% S). A joint inversion for 1D Vp, Vs and hypocentres was undertaken using Velest followed by a 3D inversion for Vp, Vp/Vs ratio and hypocentres using Simul2000. The base of the seismogenic zone increases gradually from a depth of 20 km immediately west of Mt Taranaki to 35 km deep 100 km to the east, corresponding to a previously observed increase in crustal thickness. The area close to Mt Taranaki is anomalous in that there are few earthquakes and all are shallower than 10 km. Within the upper 5-10 km of the crust Vp is closely related to surface geology, being high beneath Mt Taranaki, low beneath the surrounding sedimentary basin, and very high to the east of the basin. We present the Vp and Vp/Vs structure and hypocentre distribution of the Taranaki region and discuss features that can be attributed to volcanism at Mt Taranaki and older volcanic centres.

Sherburn, S.; White, R.

2003-12-01

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1. 728732 East Madison, southeast view of 700 block East ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. 728-732 East Madison, southeast view of 700 block East Madison Street, 728 East Madison Street is first building on the right Hugh Foshee, Photographer, March 1980 - Phoenix Hill Historic District, 728 East Madison Street (House), Louisville, Jefferson County, KY

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19. VIEW OF CRUDE ORE BINS FROM EAST. EAST CRUDE ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

19. VIEW OF CRUDE ORE BINS FROM EAST. EAST CRUDE ORE BIN IN FOREGROUND WITH DISCHARGE TO GRIZZLY AT BOTTOM OF VIEW. CONCRETE RETAINING WALL TO LEFT (SOUTH) AND BOTTOM (EAST EDGE OF EAST BIN). - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD