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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

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

E-print Network

The 12 September 1999 Upper East Rift Zone dike intrusion at Kilauea Volcano, Hawaii P. Cervelli,1 seaward sliding of Kilauea's south flank. INDEX TERMS: 7280 Seismology: Volcano seismology (8419); 8035 and associated volcanic tremor began at Kilauea Volcano. The swarm was concentrated along the east rift zone near

Segall, Paul

3

Geohydrology and Numerical Simulation of the Ground-Water Flow System of Molokai, Hawaii  

USGS Publications Warehouse

A two-dimensional, steady-state, areal ground-water flow model was developed for the island of Molokai, Hawaii, to enhance the understanding of (1) the conceptual framework of the ground-water flow system, (2) the distribution of aquifer hydraulic properties, and (3) the regional effects of ground-water withdrawals on water levels and coastal discharge. The model uses the finite-element code AQUIFEM-SALT, which simulates flow of fresh ground water in systems that may have a freshwater lens floating on denser underlying saltwater. Model results are in agreement with the general conceptual model of the flow system on Molokai, where ground water flows from the interior, high-recharge areas to the coast. The model-calculated ground-water divide separating flow to the northern and southern coasts lies to either the north or the south of the topographic divide but is generally not coincident with the topographic divide. On the basis of model results, the following horizontal hydraulic conductivities were estimated: (1) 1,000 feet per day for the dike-free volcanic rocks of East and West Molokai, (2) 100 feet per day for the marginal dike zone of the East Molokai Volcano, (3) 2 feet per day for the West Molokai dike complex, (4) 0.02 feet per day for the East Molokai dike complex, and (5) 500 feet per day for the Kalaupapa Volcanics. Three simulations to determine the effects of proposed ground-water withdrawals on water levels and coastal discharge, relative to model-calculated water levels and coastal discharge for 1992-96 withdrawal rates, show that the effects are widespread. For a withdrawal rate of 0.337 million gallons per day from a proposed well about 4 miles southeast of Kualapuu and 3 miles north of Kamiloloa, the model-calculated drawdown of 0.01 foot or more extends 4 miles southeast and 6 miles northwest from the well. For a withdrawal rate of 1.326 million gallons per day from the same well, the model-calculated drawdown of 0.01 foot or more extends 6 miles southeast and 9 miles northwest from the well. In a third scenario, the withdrawal rate from an existing well near Kualapuu was increased by 0.826 million gallons per day. The model-calculated drawdown of 0.01 foot or more extends 6 miles southeast and 8 miles northwest from the well. In all scenarios, coastal discharge is reduced by an amount equal to the additional withdrawal. Additional data needed to improve the understanding of the ground-water flow system on Molokai include: (1) a wider spatial distribution and longer temporal distribution of water-levels, (2) independent estimates of hydraulic conductivity, (3) improved recharge estimates, (4) information about the vertical distribution of salinity in ground water, (5) streamflow data at additional sites, and (6) improved information about the subsurface geology.

Oki, Delwyn S.

1997-01-01

4

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

5

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

Microsoft Academic Search

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

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

2009-01-01

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

Volcanoes!  

NSDL National Science Digital Library

This webquest provides a information and links explaining the different types of volcanoes, lava flow, volcano locations, and volcano damage. There are links for students to research their own questions and a vocabulary list. A teacher page contains associated lesson plan criteria. There are links to building volcano models, virtual volcano field trips, and a volcano quiz.

1998-09-01

8

Volcanoes!!  

NSDL National Science Digital Library

5th grade students will be able to explain what makes a volcano erupt. 5th grade students will be able to list the effects that volcanoes have on the environment and people. Read through the page to gather more knowledge about volcanoes. After reading this, you should be able to explain what makes a volcano erupt Volcano Facts View a model of a volcano erupting Visual Model of a volcano erupting Use the web tool to make your own volcano erupt. Adjust the gas level and size to make ...

Fucaloro, Kailey

2009-09-15

9

Alaska - Russian Far East connection in volcano research and monitoring  

NASA Astrophysics Data System (ADS)

The Kurile-Kamchatka-Alaska portion of the Pacific Rim of Fire spans for nearly 5400 km. It includes more than 80 active volcanoes and averages 4-6 eruptions per year. Resulting ash clouds travel for hundreds to thousands of kilometers defying political borders. To mitigate volcano hazard to aviation and local communities, the Alaska Volcano Observatory (AVO) and the Institute of Volcanology and Seismology (IVS), in partnership with the Kamchatkan Branch of the Geophysical Survey of the Russian Academy of Sciences (KBGS), have established a collaborative program with three integrated components: (1) volcano monitoring with rapid information exchange, (2) cooperation in research projects at active volcanoes, and (3) volcanological field schools for students and young scientists. Cooperation in volcano monitoring includes dissemination of daily information on the state of volcanic activity in neighboring regions, satellite and visual data exchange, as well as sharing expertise and technologies between AVO and the Kamchatkan Volcanic Eruption Response Team (KVERT) and Sakhalin Volcanic Eruption Response Team (SVERT). Collaboration in scientific research is best illustrated by involvement of AVO, IVS, and KBGS faculty and graduate students in mutual international studies. One of the most recent examples is the NSF-funded Partnerships for International Research and Education (PIRE)-Kamchatka project focusing on multi-disciplinary study of Bezymianny volcano in Kamchatka. This international project is one of many that have been initiated as a direct result of a bi-annual series of meetings known as Japan-Kamchatka-Alaska Subduction Processes (JKASP) workshops that we organize together with colleagues from Hokkaido University, Japan. The most recent JKASP meeting was held in August 2011 in Petropavlovsk-Kamchatsky and brought together more than 130 scientists and students from Russia, Japan, and the United States. The key educational component of our collaborative program is the continuous series of international volcanological field schools organized in partnership with the Kamchatka State University. Each year more than 40 students and young scientists participate in our annual field trips to Katmai, Alaska and Mutnovsky, Kamchatka.

Izbekov, P. E.; Eichelberger, J. C.; Gordeev, E.; Neal, C. A.; Chebrov, V. N.; Girina, O. A.; Demyanchuk, Y. V.; Rybin, A. V.

2012-12-01

10

Volcanic geology and eruption frequency, lower east rift zone of Kilauea volcano, Hawaii  

Microsoft Academic Search

Detailed geologic mapping and radiocarbon dating of tholeiitic basalts covering about 275 km2 on the lower east rift zone (LERZ) and adjoining flanks of Kilauea volcano, Hawaii, show that at least 112 separate eruptions have occurred during the past 2360 years. Eruptive products include spatter ramparts and cones, a shield, two extensive lithic-rich tuff deposits, aa and pahoehoe flows, and

Richard B Moore

1992-01-01

11

A geomorphological reconnaissance of the submarine part of the East Rift Zone of Kilauea Volcano, Hawaii  

Microsoft Academic Search

More than half of the intensely active East Rift Zone of Kilauea Volcano crops out underwater along the crest of the submarine Puna Ridge. I present multibeam bathmetry of the entire ridge, near-bottom photographic and sonar observations of the plunging crest of its deeper distal half, and seismic profiles across the ridge tip and the adjacent structural moat. Analysis of

Peter Lonsdale

1989-01-01

12

Volcanoes  

NSDL National Science Digital Library

Create a poster about volcanoes Directions: Make a poster about volcanoes. (20 points) Include at least (1) large picture (15 points) on your poster complete with labels of every part (10 points). (15 points) Include at least three (3) facts about volcanoes. (5 points each) (15 points) Write at least a three sentence summary of your poster and volcanoes. (5 points) Use at ...

Walls, Mrs.

2011-01-30

13

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

14

Volcanoes  

SciTech Connect

This book describes volcanoes although the authors say they are more to be experienced than described. This book poses more question than answers. The public has developed interest and awareness in volcanism since the first edition eight years ago, maybe because since the time 120 volcanoes have erupted. Of those, the more lethal eruptions were from volcanoes not included in the first edition's World's 101 Most Notorious Volcanoes.

Decker, R.W.; Decker, B.

1989-01-01

15

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.

16

Volcanoes  

NSDL National Science Digital Library

In this lesson, students investigate the processes that build volcanoes, the types of rocks they create, the factors that influence different eruption types, and the threats volcanoes pose to their surrounding environments. They will also create a notebook of volcano characteristics and use what they have learned to identify physical features and eruption types in some real-life documented volcanic episodes.

2005-01-01

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

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.

19

Volcanoes!  

NSDL National Science Digital Library

This site presents a summary of current volcanic eruptions and images and videos of volcanoes on Earth. Discussions of the characteristics of volcanism on other worlds in our solar system are also presented and are accompanied by maps and imagery. Links to volcano observatories, parks, and monuments around the world are also included.

20

NAME: Molokai Fish Pond & Fringing Reef Restoration LOCATION: Kaunakakai, Island of Molokai (Maui County), Hawai'i  

E-print Network

NAME: Molokai Fish Pond & Fringing Reef Restoration LOCATION: Kaunakakai, Island of Molokai (Maui fish ponds on the fringing reef of the Hawaiian island of Molokai. Mangroves were planted in 1902 conditions and threaten to take over the reef flats and fish ponds. EXPECTED BENEFITS: Fine sediment flushed

US Army Corps of Engineers

21

Rifts of deeply eroded Hawaiian basaltic shields: A structural analog for large Martian volcanoes  

NASA Technical Reports Server (NTRS)

Recently derived morphologic evidence suggests that intrusive events have not only influenced the growth of young shield volcanoes on Mars but also the distribution of volatiles surrounding these volcanoes: in addition to rift zones and flank eruptions on Arsia Mons and Pavonis Mons, melt water channels were identified to the northwest of Hecates Tholus, to the south of Hadriaca Patera, and to the SE of Olympus Mons. Melt water release could be the surface expression of tectonic deformation of the region or, potentially, intrusive events associated with dike emplacement from each of these volcanoes. In this study the structural properties of Hawaiian shield volcanoes were studied where subaerial erosion has removed a sufficient amount of the surface to enable a direct investigation of the internal structure of the volcanoes. The field investigation of dike morphology and magma flow characteristics for several volcanoes in Hawaii is reported. A comprehensive investigation was made of the Koolau dike complex that passes through the summit caldera. A study of two other dissected Hawaiian volcanoes, namely Waianae and East Molokai, was commenced. The goal is not only to understand the emplacement process and magma flow within these terrestrial dikes, but also to explore the possible role that intrusive events may have played in volcano growth and the distribution of melt water release on Mars.

Knight, Michael D.; Walker, G. P. L.; Mouginis-Mark, P. J.; Rowland, Scott K.

1988-01-01

22

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

23

Volcanoes  

NSDL National Science Digital Library

This resource provides general information about volcanoes. It illustrates the growth of a volcano, using Paricutin and Mt. St. Helens as examples of an active volcano and a lava dome. The terms extinct and dormant are also discussed. This site provides an explanation of why and how volcanoes form, zones of subduction, mid-ocean ridges, and hot spots. Deadly dangers associated with eruptions are discussed as is the use of a tiltmeter for prediction. The content center lesson describes a possible connection between the lost continent of Atlantis and the island of Santorini. Dissolved gasses in magma and the creation of a lava dome are both demonstrated in the hands-on section.

Johnson, Scott

24

Volcanoes  

MedlinePLUS

... They have been known to knock down entire forests. Volcanic eruptions can be accompanied by other natural hazards, including earthquakes , mudflows and flash floods , rock falls and landslides , acid rain, fire , and (under special conditions) tsunamis . Active volcanoes in ...

25

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

26

Evolution and dynamics of magmatic processes below Gede volcano, East-Java, Indonesia  

NASA Astrophysics Data System (ADS)

Subduction-zone volcanism produces a large variety of compositions and eruption styles, but silica-rich explosive eruptions from arc volcanoes are those that pose the most direct threat for those living on and around the volcanoes. The little known Gede volcano (East-Java, Indonesia) is a composite arc-volcano showing evidences of recurrent silicic explosive eruptions and it is a hazard to its 1 million residences settled on its flank also to the two most populated neighboring metropolises: Jakarta and Bandung. Here we present the results of a detailed petrological and geochemical study of Gede's deposits to untangle its magmatic evolution, the key magma reservoir processes, and try to use this information to better anticipate possible future eruptions at Gede. After field-work and dating of the main deposits we identified 5 pyroclastic units ranging from basaltic andesite to dacite, and of eruption ages from about 1 ky to > 45 ky. Bulk-rock major and trace element compositions can be explained as a combination of fractional crystallization and magma mixing/mingling. Crystallization trends evolve with time from wet (amphibole present and plagioclase delayed) to 'dry' (olivine and two pyroxenes, and plagioclase). Petrological and geochemical evidence for within-trend mixing/mingling are common and involve high-Si basalt and dacite end-members. Core to rim electron microprobe and LA-ICP-MS trace element analysis of main phenocrysts (amphibole, plagioclase, ortho- and clinopyroxene) record the details of repetitive magma mixing and mingling events. Cores of amphibole, ortho- and clinopyroxene in the Holocene units have low Mg/Fe, high REEs and Eu-anomaly, and are rimmed Mg/Fe, low REEs and no Eu-anomaly zones. These minerals are thus recording the intrusions of mafic, water-richer and crystal-poor magma into an evolved and partly crystallized magma reservoir. Modeling the diffusive re-equilibration between the crystal cores and rims provides the time elapsed since the intrusion of the primitive magmas, interaction between end-member magmas, and eruption, and this is less than a few years. Our study shows that Gede volcano has evolved in the last 50 ky from a water-rich to a water-poor fractionation series. Many eruptions of both series are probably triggered by injection of mafic magma in evolved magma reservoirs. This suggest that if new unrest occurs below Gede the eruptions are likely to be explosive but the time between new intrusion and eruption would be long enough for proper response for mitigating its potential hazards.

Krimer, Daniel; Costa, Fidel

2014-05-01

27

Paleomagnetic correlation of Late Quaternary lava flows in the lower east rift zone of Kilauea Volcano, Hawaii  

Microsoft Academic Search

Paleomagnetic data reflecting paleosecular variation (PSV) of the geomagnetic field are used to correlate individual lava flows in the lower east rift zone of Kilauea Volcano. This area has been recently mapped based on petrography, stratigraphy, soil development, and degree of weathering of the flows; eight C-14 dates also provide a framework for the relative age assignments. Site-mean directions of

Jonathan T. Hagstrum; Duane E. Champion

1994-01-01

28

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

NASA Astrophysics Data System (ADS)

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) the drilling of the nearby Banjar Panji-1 gas exploration well (150 m away), and (c) a combination of the earthquake and drilling operations. We compare the distance and magnitude of the earthquake with the relationship between the distance and magnitude of historical earthquakes that have caused sediment liquefaction, or triggered the eruption of mud volcanoes or caused other hydrological responses. Based on this comparison, an earthquake trigger is not expected. The static stress changes caused by the rupture of the fault that created the Yogyakarta earthquake are a few tens of Pascals, much smaller than changes in stress caused by tides or variations in barometric pressure. At least 22 earthquakes (and possibly hundreds) likely caused stronger ground shaking at the site of Lusi in the past 30 years without causing an eruption. The period immediately preceding the eruption was seismically quieter than average and thus there is no evidence that Lusi was "primed" by previous earthquakes. We thus rule out an earthquake-only trigger. The day before the eruption started (May 28th 2006), as a result of pulling the drill bit and drill pipe out of the hole, there was a significant influx of formation fluid and gas. The monitored pressure after the influx, in the drill pipe and annulus showed variations typical of the leakage of drilling fluid into the surrounding sedimentary rock strata. Furthermore we calculate that the pressure at a depth of 1091 m (the shallowest depth without any protective steel casing) exceeded a critical level after the influx occurred. Fractures formed due to the excess pressure, allowing a fluid-gas-mud mix to flow to the surface. With detailed data from the exploration well, we can now identify the specific drilling induced phenomena that caused this man-made disaster.

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

2008-08-01

29

Beach and reef-flat sediments along the south shore of Molokai, Hawaii  

USGS Publications Warehouse

As part of the U.S. Geological Survey's multi-disciplinary Coral Reef Project addressing the health and geological variability of coral reef systems, sediment components and their distribution along the fringing reef on the south shore of the Hawaiian island of Molokai are being examined. Particular interest is being paid to the types and origin of sediment found on the reef. The south shore of Molokai is sheltered by one of the largest fringing reefs in the US. At approximately 50 km in length, up to 1.5 km in width, and covered by 90% live coral in many locations, the reef seemingly should be able to provide ample sediment for large carbonate beaches. However, siliciclastic grains supplied by erosion of the basaltic uplands of Molokai are often the most conspicuous individual nearshore sediment type. Coralline algae and coral are the most common carbonate components of the beaches. On the nearshore reef-flat, chemically-altered carbonate grains, particularly coralline algae, are the most abundant component. Molluscs and Halimeda may be common in specific locations, but are usually minor components. Sediment calcium carbonate levels increase to the west from a minimum at Kamalo, and are high along the east shore of Molokai. However, these general island-scale trends may be overridden by local influences, such as protected stream mouths or high carbonate growth rates. Additionally, trends seen on the beach and nearshore environments may not reflect trends a few hundred meters offshore since shore normal trends are more pronounced than shore parallel ones.

Calhoun, R.S.; Field, M.E.

2000-01-01

30

Numerical Simulation of the Hydrologic Effects of Redistributed and Additional Ground-Water Withdrawal, Island of Molokai, Hawaii  

USGS Publications Warehouse

Because of increased demand for water associated with a growing population, projected increases in demand over the next few decades, and rising salinity of the water pumped from some existing wells, the County of Maui Department of Water Supply (DWS) is currently (2006) considering drilling additional wells to replace or supplement existing wells on the Island of Molokai, Hawaii. Redistributed and additional ground-water withdrawals will affect ground-water levels, discharge of ground water to the nearshore environment, and, possibly, salinity of the water pumped from existing wells. For this study, an existing numerical ground-water-flow model was used to estimate water-level and coastal-discharge changes, relative to 2005 base-case conditions, caused by withdrawals in the area between Kualapuu and Ualapue on Molokai. For most of the scenarios tested, total withdrawals were either equal to or 0.28 million gallons per day greater than those in the 2005 base case. Model results indicate that a redistribution of withdrawals causes a corresponding redistribution of water levels and coastal discharge. Water levels rise and coastal discharge increases near sites of reduced withdrawal, whereas water levels decline and coastal discharge decreases near sites of increased withdrawal. The magnitude and areal extent of hydrologic changes caused by a redistribution of withdrawals increase with larger changes in withdrawal rates. Simulated water-level changes are greatest at withdrawal sites and decrease outward with distance elsewhere. Simulated water-level declines at proposed withdrawal sites generally were less than 0.5 feet. The low-permeability dike complex of East Molokai Volcano impedes the spread of water-level changes to perennial streams in the northeastern part of the island, and discharge to these streams in the dike complex therefore is unaffected by the proposed withdrawals. Simulated coastal-discharge changes generally are greatest immediately downgradient from sites of withdrawal change. Simulated coastal-discharge reductions generally are less than 30,000 gallons per day (and everywhere less than 75,000 gallons per day) within model elements for scenarios that exclude the Hawaii Department of Hawaiian Home Lands reservation (2.905 million gallons per day). (Model elements cover discrete 1,640-feet by 1,640-feet square areas.) Simulated coastal-discharge reductions generally represent less than 5 percent change relative to 2005 base-case conditions. Simulated discharge to some fishponds and springs increased in response to decreased withdrawal at upgradient sites, and simulated discharge to other fishponds and springs decreased in response to increased withdrawal. Simulated water-level declines associated with the Hawaii Department of Hawaiian Home Lands reservation were as much as 4 feet at three arbitrarily selected withdrawal sites, and simulated reductions in coastal discharge between Umipaa and Kamiloloa along the south coast exceeded 200,000 gallons per day from several model elements.

Oki, Delwyn S.

2006-01-01

31

Volcanic geology and eruption frequency, lower east rift zone of Kilauea volcano, Hawaii  

USGS Publications Warehouse

Detailed geologic mapping and radiocarbon dating of tholeiitic basalts covering about 275 km2 on the lower east rift zone (LERZ) and adjoining flanks of Kilauea volcano, Hawaii, show that at least 112 separate eruptions have occurred during the past 2360 years. Eruptive products include spatter ramparts and cones, a shield, two extensive lithic-rich tuff deposits, aa and pahoehoe flows, and three littoral cones. Areal coverage, number of eruptions and average dormant interval estimates in years for the five age groups assigned are: (I) historic, i.e. A D 1790 and younger: 25%, 5, 42.75; (II) 200-400 years old: 50%, 15, 14.3: (III) 400-750 years old: 20%, 54, 6.6; (IV) 750-1500 years old: 5%, 37, 20.8; (V) 1500-3000 years old: <1%, 1, unknown. At least 4.5-6 km3 of tholeiitic basalt have been erupted from the LERZ during the past 1500 years. Estimated volumes of the exposed products of individual eruptions range from a few tens of cubic meters for older units in small kipukas to as much as 0.4 km3 for the heiheiahulu shield. The average dormant interval has been about 13.6 years during the past 1500 years. The most recent eruption occurred in 1961, and the area may be overdue for its next eruption. However, eruptive activity will not resume on the LERZ until either the dike feeding the current eruption on the middle east rift zone extends farther down rift, or a new dike, unrelated to the current eruption, extends into the LERZ. ?? 1992 Springer-Verlag.

Moore, R. B.

1992-01-01

32

Extreme peralkalinity in delhayelite- and andremeyerite-bearing nephelinite from Nyiragongo volcano, East African Rift  

NASA Astrophysics Data System (ADS)

Highly peralkaline leucite nephelinite from the active volcano Nyiragongo in the Virunga province of the East African Rift contains globules of iron- and volatile-rich, highly peralkaline silicate glass with (Na + K)/Al up to 18 which has formed as a late differentiate of less peralkaline precursors, probably by fractional crystallization at a shallow level in the volcanic system. A number of uncommon minerals coexist with this glass (kalsilite, kirschsteinite, chlorbartonite, götzenite, delhayelite, umbrianite, zirconian cuspidine, andremeyerite (BaFe2Si2O7), other Ba-Fe-Ti silicate minerals, and unnamed alkali-barium phosphate and Zr-Nb-Ti silicate minerals). These minerals are members of late magmatic assemblages that have survived sub-solidus recrystallization. Combeite occurs as a near-solidus mineral. Low-variance mineral assemblages in Nyiragongo nephelinite define a cooling trend from eruptive temperatures ? 980 °C to the solidus of extremely peralkaline residual liquids at ca. 600 °C, followed by sub-solidus recrystallization and metasomatism down to ca. 500 °C. Oxygen fugacity well below the QFM buffer (QFM-2 to -3) persisted throughout the magmatic crystallization stage, but increased to above QFM during the final stage of postmagmatic recrystallization. Highly alkaline, volatile-rich minerals such as delhayelite, götzenite and cuspidine were stabilized by a combination of high peralkalinity and elevated activity of chlorine and fluorine; these conditions persisted to sub-solidus temperatures.

Andersen, Tom; Elburg, Marlina A.; Erambert, Muriel

2014-10-01

33

Seismic Characterization of the June 17, 2007 East Rift Intrusion at Kilauea Volcano  

NASA Astrophysics Data System (ADS)

An early morning earthquake swarm on Sunday, June 17, 2007 signaled the beginning of a sequence of seismic and deformational activity consistent with an intrusion of magma in the upper East Rift of Kilauea volcano, Hawaii. This culminated in an outbreak of lava from a discontinuous 160 meter long fissure, approximately 6 km west of Pu`u `O`o and 13 km southeast of Kilauea's summit. Here we detail the seismic characteristics and observed deformation accompanying this magmatic intrusion and eruption. Seismic activity began at 0216 Hawaiian Standard Time (HST - UTC minus 10 hours) with 38 events greater than magnitude 2 and over 80 located earthquakes in the first two hours. These earthquakes were centered 1.5-2 km southwest of Mauna Ulu (9 km southeast of Kilauea summit) between 1.5 and 3 km deep. At the same time, tiltmeters at Kilauea's summit began indicating rapid deflation of the summit area. Starting at 0730 HST there was a pronounced eastward shift (by about 4 km) of the center of seismicity to a location just west of Makaopuhi crater. At this time GPS stations began to show extension across the rift in that area. Over the next 7-8 hours, the locus of seismicity continued to migrate eastward with over 70 events located at Makaopuhi crater. Over the next day more than 40 earthquakes occurred with locations ranging from the uppermost east rift to Makaopuhi crater. The next afternoon (June 18) there was another pronounced eastward shift in seismicity with 23 earthquakes, occurring between 1459-1600 HST, centered between Makaopuhi crater and Napau crater. Kilauea summit area tremor levels rose throughout the day on June 17, reaching a peak of 24 times background levels mid-day on the June 18, before beginning a slow decline. Tremor levels along the East Rift showed brief periods of strong activity (4-6 times background levels), and lava was discovered at the surface shortly after one such tremor episode at 0625 HST on June 19. Shortly before noon on the same day, Kilauea tiltmeters indicated an end to summit deflation, and GPS stations indicated a slowing of rift extension which had reached nearly 1 meter of across rift extension. This series of punctuated eastward migrations of seismicity (along with the observed deformational signals) provide a detailed record of the space-time evolution of the June 17 magmatic intrusion and eruption.

Wilson, D. C.; Uribe, J.; Kamibayashi, S.; Nakata, J.; Okubo, P.

2007-12-01

34

The mythos of dwelling : a settlement at Kalaupapa, Molokai  

E-print Network

This thesis is the exploration of the physical and metaphorical potential of one of the most beautiful and poignant places in the world. It is Kalaupapa, a peninsula on the North Shore of Molokai, Hawaii, and the site of ...

Ries, Paul R

1989-01-01

35

Selected time-lapse movies of the east rift zone eruption of K?lauea Volcano, 2004–2008  

USGS Publications Warehouse

Since 2004, the U.S. Geological Survey's Hawaiian Volcano Observatory has used mass-market digital time-lapse cameras and network-enabled Webcams for visual monitoring and research. The 26 time-lapse movies in this report were selected from the vast collection of images acquired by these camera systems during 2004–2008. Chosen for their content and broad aesthetic appeal, these image sequences document a variety of flow-field and vent processes from K?lauea's east rift zone eruption, which began in 1983 and is still (as of 2011) ongoing.

Orr, Tim R.

2011-01-01

36

Shear destruction of the East Asian margin and its role in the formation of volcano-plutonic belts, epicontinental sedimentary basins, and marginal seas  

Microsoft Academic Search

The spatial?temporal and genetic relations between the formation of volcano-plutonic belts and the development of the East Asian global shear zone in the Cretaceous?Cenozoic was first demonstrated in [5, 7?9]. Subsequently, many researchers paid attention to strike-slip faults as a factor of tectonic evolution of the Asian margin. In the context of plate tectonics, the East Asian global shear zone

V. P. Utkin

2009-01-01

37

Reconnaissance gas measurements on the East Rift Zone of Kilauea Volcano, Hawai'i by Fourier transform infrared spectroscopy  

USGS Publications Warehouse

We report the results of a set of measurements of volcanic gases on two small ground level plumes in the vicinity of Pu`u `O`o cone on the middle East Rift Zone (ERZ) of Kilauea volcano, Hawai`i on 15 June 2001 using open-path Fourier transform infrared (FTIR) spectroscopy. The work was carried out as a reconnaissance survey to assess the monitoring and research value of FTIR measurements at this volcano. Despite representing emissions of residual volatiles from lava that has undergone prior degassing, the plumes contained detectable amounts of CO2, CO, SO2, HCl, HF and SiF4. Various processes, including subsurface cooling, condensation of water in the atmospheric plume, oxidation, dissolution in water, and reactions with wall rocks at plume vents affect the abundance of these gases. Low concentrations of volcanic CO2 measured against a high ambient background are not well constrained by FTIR spectroscopy. Although there appear to be some differences between these gases and Pu`u `O`o source gases, ratios of HCl/SO2, HF/SO2 and CO/SO2 determined by FTIR measurements of these two small plumes compare reasonably well with earlier published analyses of ERZ vent samples. The measurements yielded emission rate estimates of 4, 11 and 4 t d-1

McGee, Kenneth A.; Elias, Tamar; Sutton, A. Jefferson; Doukas, Michael P.; Zemek, Peter G.; Gerlach, Terrence M.

2005-01-01

38

Molokai Community Needs Assessment for Agriculture Education and Training.  

ERIC Educational Resources Information Center

In order to assess the needs of agriculture (AG) education and ascertain the potential employment demand for pre-service and in-service training in agriculture over the next 5 years, Maui Community College (MCC) sent questionnaires to Molokai community businesses, inquiring about their agricultural labor demand. In December 1997, 68 questionnaires…

Pezzoli, Jean A.

39

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

NASA Astrophysics Data System (ADS)

Volcanoes in humid tropical environments are frequently cloud covered, typically densely vegetated and rapidly eroded. These factors complicate field and laboratory studies and even the basic identification of potentially active volcanoes. Numerous previous studies have highlighted the potential value of radar remote sensing for volcanology in equatorial regions. Here, cloud- and vegetation-penetrating LHH-band (? 24cm) synthetic aperture radar (SAR) data from the Japanese Earth Resources Satellite (JERS-1) are used to investigate persistently active volcanoes and prehistoric calderas in East Java, Indonesia. The LHH-band JERS-1 SAR produces high-spatial-resolution (18m) imagery with relatively high incidence angle that highlights structures and topographic variations at or greater than the wavelength scale while minimising geometrical distortions such as layover and foreshortening. These images, along with Internet browse data derived from the Canadian RADARSAT mission, provide new evidence relating regional tectonics to volcanism throughout East Java. Volcanic events, such as caldera collapse at the Tengger caldera, appear to have been partly controlled by northwest-aligned faults related to intra-arc sedimentary basins. Similar regional controls appear important at historically active Lamongan volcano, which is encircled by numerous flank maars and cinder cones. A previously undocumented pyroclastic sheet and debris avalanche deposit from the Jambangan caldera complex is also manifested in the synoptic radar images. At the currently active Semeru volcano these data permit identification of recent pyroclastic flow and lahar deposits. Radar data therefore offer a valuable tool for mapping and hazard assessment at late Quaternary volcanoes. The criteria developed in the analysis here could be applied to other regions in the humid tropics.

Carn, Simon A.

40

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

41

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

42

Preliminary Analytical Results for a Mud Sample Collected from the LUSI Mud Volcano, Sidoarjo, East Java, Indonesia  

USGS Publications Warehouse

On May 29, 2006, mud and gases began erupting unexpectedly from a vent 150 meters away from a hydrocarbon exploration well near Sidoarjo, East Java, Indonesia. The eruption, called the LUSI (Lumpur 'mud'-Sidoarjo) mud volcano, has continued since then at rates as high as 160,000 m3 per day. At the request of the United States Department of State, the U.S. Geological Survey (USGS) has been providing technical assistance to the Indonesian Government on the geological and geochemical aspects of the mud eruption. This report presents initial characterization results of a sample of the mud collected on September 22, 2007, as well as inerpretive findings based on the analytical results. The focus is on characteristics of the mud sample (including the solid and water components of the mud) that may be of potential environmental or human health concern. Characteristics that provide insights into the possible origins of the mud and its contained solids and waters have also been evaluated.

Plumlee, Geoffrey S.; Casadevall, Thomas J.; Wibowo, Handoko T.; Rosenbauer, Robert J.; Johnson, Craig A.; Breit, George N.; Lowers, Heather A.; Wolf, Ruth E.; Hageman, Philip L.; Goldstein, Harland; Anthony, Michael W.; Berry, Cyrus J.; Fey, David L.; Meeker, Gregory P.; Morman, Suzette A.

2008-01-01

43

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

44

Full Vector Studies of the Last 10 Thousand Years Derived From The East Maui Volcano Hawaii  

NASA Astrophysics Data System (ADS)

We have determined the paleointensity of nine lavas flows that recorded the last 10 kyrs of geomagnetic field behavior from the youngest and largest of the two edifices of the island of Maui (i.e. Hana Volcanics, East Maui) with the multispecimen parallel differential pTRM method [Dekkers and Böhnel, EPSL, 248, 508-517, 2006]. The flows are characterized by irreversible Curie curves indicating two kinds of magnetic carriers: one almost pure magnetite and the second one Ti-rich magnetite with possible traces of titanomaghemite. The coercivity of remanence (Hcr) suggests that low-coercivity grains carry the NRM. Magnetic minerals from all of these flows are scattered within the PSD range with the exception of site HKAM (age 4.07±+0.09 ka) that lies in the SD range. The multispecimen method involves giving a laboratory pTRM to pristine specimens in different field strengths parallel to the original TRM; note that all pTRMs are given within the same range. From an existing sample collection for paleosecular variation studies [Herrero-Bervera and Valet, PEPI, 161, 267-280, 2007] we processed samples from 9 flows for paleointensity determinations ranging in age from 0.830.06 ka to 8.19±0.06 ka. pTRMs were given by in-field heating and cooling from 175 and to 260°C to avoid alteration. Low-field susceptibility variation appeared to be less than 10%, and sample sets from a few flows were heated to two different temperatures to check for consistency of results. All flows yielded good quality data. The paleointensity values increase to ~46 microTesla at ~ 2.2 ka and drop to ~22 microTesla at ~3.5 ka. At ~8.2 ka, ~39 microTesla is obtained, i.e. slightly higher than the present-day value (36 microTesla). Our paleointensity results (at least 7 flows) correlate well with the absolute paleointensity global determinations. The influence of a recently proposed domain-state correction [Fabian and Leonhardt, 2010, EPSL] on the paleointensity values will be investigated and shown.

Herrero-Bervera, E.; Dekkers, M. J.; Bohnel, H.; Hagstrum, J. T.; Champion, D. E.

2010-12-01

45

A new high resolution total magnetic intensity data set of the Laacher See Volcano in the East-Eifel volcanic field, Germany  

NASA Astrophysics Data System (ADS)

The Laacher See Volcano (LSV) is part of the Quaternary East-Eifel volcanic field (EVF) located in the western part of Germany, where at least 103 eruptive centers have been identified. The Laacher See volcano explosively erupted about 6.3 km3 of phonolitic magma during a dominantly phreato-plinian eruption at about 12,900 BP. Despite numerous previous studies the eruptive history of LSV is not fully unveiled. For a better understanding of the eruptive history of LSV several geophysical methods, including magnetic, gravimetric and bathymetric surveys have been applied on and around Laacher See Volcano. Here we focus on the magnetic and bathymetric data. The presented high resolution magnetic data covering an area of about 25 km2 (20,000 sample points) and were collected using ground based proton magnetometers (GEM Systems GSM-19TGW, Geometrics G856) during several field campaigns. In addition, a magnetic survey on the lake was done using a non-magnetic boat as platform. The bathymetric survey was conducted on profiles (total length of 235 km) using an echo sounder GARMIN GPSMap 421. Depth data were computed to a bathymetric model on a 10 m spaced regular grid. A joint interpretation of magnetic, morphologic and bathymetric data allows us to search for common patterns which can be associated with typical volcanic features. From our data at least one new eruptive center and lava flow could be identified. Furthermore, the new data suggest that previously identified lava flows have not been accurately located.

Goepel, A.; Queitsch, M.; Lonschinski, M.; Eitner, A.; Meisel, M.; Reißig, S.; Engelhardt, J.; Büchel, G.; Kukowski, N.

2012-04-01

46

Physical and acoustic properties of sediments off the coasts of Molokai and Lanai Islands, Hawaii  

E-print Network

Examination of physical and acoustic properties of carbonate-rich sediments was conducted on a suite of cores off of the coasts of Molokai and Lanai Islands, Hawaii. Carbonate mineralogy, grain size, grain density, porosity, bulk density...

Bayer, Mary Rose

2012-06-07

47

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

48

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

49

Temporal monitoring of radiative heat flux from the craters of Tendürek volcano (East Anatolia, Turkey) using ASTER satellite imagery  

NASA Astrophysics Data System (ADS)

Tendürek volcano is situated in the Eastern Anatolia near Turkish-Iranian border. It is one of the youngest volcanoes of Eastern Anatolia and it is a polygenetic, basaltic shield volcano formed by successive basalt flows. Tendürek is characterized by alkaline volcanism. Holocene and historical activity has been reported. Hydrothermal activity have been observed on the twin summit craters. Fumaroles, steam vents, steam/gas emission and zones of hot grounds have been reported. In order to quantify and to determine a base value for the current thermal state of the volcano, we used ASTER Thermal Infrared spectra. Four ASTER daytime and nighttime images have been used to calculate radiative heat flux from the craters. Heat flux calculations have been made using three nighttime images and a daytime image acquired in 2002, 2004, 2008 and 2012. Images have been atmospherically corrected, temperature and emissivity have been separated and Land Surface Temperature (LST) has been calculated from 5 thermal bands. LST images have been topographically corrected. Heat flux have been calculated using corrected surface temperature data, emissivity, vapor pressure and height-dependent air temperature values. Maximum temperature anomalies observed were 9.0 °C and 15.9 °C for the western and eastern craters respectively. Heat flux is estimated between 14.4 and 25.2 W/m² at the western crater and between 16.5 and 49.4 W/m² at the eastern crater. These values are well correlated with other known low-level activity volcanoes such as Yellowstone, Stromboli and Nisyros, whereas they are lower than that of observed at Vulcano.

Ulusoy, ?nan

2014-05-01

50

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

USGS Publications Warehouse

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. ?? 1989 Springer-Verlag.

Andres, R.J.; Kyle, P.R.; Stokes, J.B.; Rose, W.I.

1989-01-01

51

22. VIEW EAST TOWARDS WAIKOLU VALLEY OF PIPELINE ALONG PALI. ...  

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

22. VIEW EAST TOWARDS WAIKOLU VALLEY OF PIPELINE ALONG PALI. EYE BOLTS IN ROCK FACE AT RIGHT WERE USED BRIEFLY IN PLACE OF PIERS TO SUSPEND PIPE BY CHAIN BECAUSE THE CONCRETE PIERS WERE SUSCEPTIBLE TO HEAVY WAVE ACTION IN THIS AREA. - Kalaupapa Water Supply System, Waikolu Valley to Kalaupapa Settlement, Island of Molokai, Kalaupapa, Kalawao County, HI

52

Thermal and rheological controls on magma migration in dikes: Examples from the east rift zone of Kilauea volcano, Hawaii  

NASA Technical Reports Server (NTRS)

Long-lived eruptions from basaltic volcanoes involving episodic or steady activity indicate that a delicate balance has been struck between the rate of magma cooling in the dike system feeding the vent and the rate of magma supply to the dike system from a reservoir. We describe some key factors, involving the relationships between magma temperature, magma rheology, and dike geometry that control the nature of such eruptions.

Parfitt, E. A.; Wilson, L.; Pinkerton, H.

1993-01-01

53

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

54

Holocene reef accretion: southwest Molokai, Hawaii, U.S.A.  

USGS Publications Warehouse

Two reef systems off south Molokai, Hale O Lono and Hikauhi (separated by only 10 km), show strong and fundamental differences in modern ecosystem structure and Holocene accretion history that reflect the influence of wave-induced near-bed shear stresses on reef development in Hawaii. Both sites are exposed to similar impacts from south, Kona, and trade-wind swell. However, the Hale O Lono site is exposed to north swell and the Hikuahi site is not. As a result, the reef at Hale O Lono records no late Holocene net accretion while the reef at Hikauhi records consistent and robust accretion over late Holocene time. Analysis and dating of 24 cores from Hale O Lono and Hikauhi reveal the presence of five major lithofacies that reflect paleo-environmental conditions. In order of decreasing depositional energy they are: (1) coral-algal bindstone; (2) mixed skeletal rudstone; (3) massive coral framestone; (4) unconsolidated floatstone; and (5) branching coral framestone-bafflestone. At Hale O Lono, 10 cores document a backstepping reef ranging from ? 8,100 cal yr BP (offshore) to ? 4,800 cal yr BP (nearshore). A depauperate community of modern coral diminishes shoreward and seaward of ? 15 m depth due to wave energy, disrupted recruitment activities, and physical abrasion. Evidence suggests a change from conditions conducive to accretion during the early Holocene to conditions detrimental to accretion in the late Holocene. Reef structure at Hikauhi, reconstructed from 14 cores, reveals a thick, rapidly accreting and young reef (maximum age ? 900 cal yr BP). Living coral cover on this reef increases seaward with distance from the reef crest but terminates at a depth of ? 20 m where the reef ends in a large sand field. The primary limitation on vertical reef growth is accommodation space under wave base, not recruitment activities or energy conditions. Interpretations of cored lithofacies suggest that modern reef growth on the southwest corner of Molokai, and by extension across Hawaii in general, is controlled by wave-induced near-bed shear stress related to refracted North Pacific swell. Holocene accretion patterns here also reflect the long-term influence of wave-induced near-bed shear stress from north swell during late Holocene time. This finding is consistent with other studies (e.g., Grigg 1998; Cabioch et al. 1999) that reflect the dominance of swell energy and sea level in controlling modern and late Holocene accretion elsewhere in Hawaii and across the Pacific and Indian oceans. Notably, however, this result is refined and clarified for Hawaii in the hypothesis of Rooney et al. (2003) stating that enhancement of the El Niño Southern Oscillation beginning approximately 5000 years ago led to increased north swell energy and signaled the end to net accretion along exposed coastlines in Hawaii. The exposure of Hale O Lono to north swell and the age of sea floor there (ca. 4,800 cal yr BP), coupled with the lack of north swell incidence at Hikauhi and the continuous accretion that has occurred there over the last millennium, strongly supports the ENSO reef hypothesis as outlined by Rooney et al. (2003). Other factors controlling Holocene reef accretion at the study site are relative sea-level position and rate of rise, and wave sheltering by Laau Point. Habitat suitable for reef accretion on the southwest shore of Molokai has shrunk throughout the Holocene.

Engels, Mary S.; Fletcher, Charles H. III; Field, Michael E.; Storlazzi, Curt D.; Grossman, Eric E.; Rooney, John J. B.; Conger, Christopher L.; Glenn, Craig

2004-01-01

55

A Full-Vector Geomagnetic PSV Curve Derived from East Maui Volcano Lava Flows for the Last ~15,000 years  

NASA Astrophysics Data System (ADS)

We have studied the paleomagnetism and rock magnetism of oriented samples from 105 lava flows erupted by the East Maui Volcano, Hawai`i, (i.e. Hana Volcanics) in order to construct a directional and absolute paleointensity (full-vector) paleosecular variation (PSV) curve for the last ~15,000 years. The directional geomagnetic behavior for East Maui has already been published by Sherrod et al. [JGR, 111, 10,1029/2005JB003876, 2006], and Herrero-Bervera and Valet [PEPI, 161-267-280, 2007]. All lava flows were previously dated using radiocarbon methods and span the last ~15,000 years of geomagnetic behavior. In addition to demagnetization experiments (i.e. alternating field and thermal) we have determined Curie temperatures and hysteresis parameters to characterize composition and grain size of the magnetic grains contained by the sampled flows. Accordingly, most lava flow samples have two types of magnetic minerals in different proportions; low-Ti titanomagnetite with high Curie temperature and high-Ti titanomagnetite with low Curie temperature. During sample heating and cooling the temperature curves are often irreversible. Magnetic grains have sizes that are within the pseudo single domain range and include both single and multi domain particles. Absolute paleointensities (PI) of 37 flows were obtained using the multi-specimen parallel differential pTRM method [Dekkers and Böhnel, EPSL, 248, 508-517, 2006], mostly at temperatures between 170° and 250°C when high-Ti titanomagnetite was dominant. In a few samples with magnetic grains having near-magnetite compositions, higher temperatures could be used. For some of the samples the recently proposed domain-state correction [Fabian and Leonhardt, EPSL, 297, 84-94, 2010] was applied as well. In addition, we have been able to successfully obtain PIs by means of the Thellier-Coe protocol for 17 lava flows. Our paleointensity results correlate well with global absolute paleointensity determinations.

Herrero-Bervera, E.; Hagstrum, J. T.; Champion, D. E.; Dekkers, M. J.; Bohnel, H.

2012-12-01

56

Volcano Live  

NSDL National Science Digital Library

The volocanologist John Seach provides the latest volcano news and information on volcanoes all across the world. The website provides fun hands-on activities, tutorials in volcano safety and volcanology, and a glossary. Students can discover the geography of many areas of the world and how it impacts the likelihood of volcanic eruptions. Users can find links to numerous volcano cameras and maps. The amazing images of volcanoes from Seach's expeditions are a great addition to this informative site.

57

A Practical Framework for Evaluating a Culturally Tailored Adolescent Substance Abuse Treatment Programme in Molokai, Hawaii  

Microsoft Academic Search

Objective. Successful substance abuse treatment requires many changes in behavior, attitude and skills. Culturally tailored approaches to substance abuse treatment have shown initial success, but are not yet accepted as best practice models. In order to document programme effectiveness of a new culturally tailored substance abuse treatment programme on the rural island of Molokai, Hawaii, the authors worked to develop

Kelley M. Withy; Wayde Lee; Ralph F. Renger

2007-01-01

58

Diurnal variability in turbidity and coral fluorescence on a fringing reef flat: Southern Molokai, Hawaii  

Microsoft Academic Search

Terrigenous sediment in the nearshore environment can pose both acute and chronic stresses to coral reefs. The reef flat off southern Molokai, Hawaii, typically experiences daily turbidity events, in which trade winds and tides combine to resuspend terrigenous sediment and transport it alongshore. These chronic turbidity events could play a role in restricting coral distribution on the reef flat by

Gregory A. Piniak; Curt D. Storlazzi

2008-01-01

59

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.

60

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

61

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

62

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.

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 factors complicate field and laboratory studies and even the basic identification of potentially active volcanoes. Numerous previous studies have highlighted the potential value of radar remote sensing for volcanology in equatorial regions. Here, cloud- and vegetation-penetrating LHH-band (lambda 24cm) synthetic aperture radar (SAR) data

Simon A. Carn

1999-01-01

64

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

65

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

66

Volcano Vents  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Released 5 May 2003

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

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

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

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

2003-01-01

67

The pre-eruptive magma plumbing system of the 2007-2008 dome-forming eruption of Kelut volcano, East Java, Indonesia  

NASA Astrophysics Data System (ADS)

Kelut volcano, East Java, is an active volcanic complex hosting a summit crater lake that has been the source of some of Indonesia's most destructive lahars. In November 2007, an effusive eruption lasting approximately 7 months led to the formation of a 260-m-high and 400-m-wide lava dome that displaced most of the crater lake. The 2007-2008 Kelut dome comprises crystal-rich basaltic andesite with a texturally complex crystal cargo of strongly zoned and in part resorbed plagioclase (An47-94), orthopyroxene (En64-72, Fs24-32, Wo2-4), clinopyroxene (En40-48, Fs14-19, Wo34-46), Ti-magnetite (Usp16-34) and trace amounts of apatite, as well as ubiquitous glomerocrysts of varying magmatic mineral assemblages. In addition, the notable occurrence of magmatic and crustal xenoliths (meta-basalts, amphibole-bearing cumulates, and skarn-type calc-silicates and meta-volcaniclastic rocks) is a distinct feature of the dome. New petrographical, whole rock major and trace element data, mineral chemistry as well as oxygen isotope data for both whole rocks and minerals indicate a complex regime of magma-mixing, decompression-driven resorption, degassing and crystallisation and crustal assimilation within the Kelut plumbing system prior to extrusion of the dome. Detailed investigation of plagioclase textures alongside crystal size distribution analyses provide evidence for magma mixing as a major pre-eruptive process that blends multiple crystal cargoes together. Distinct magma storage zones are postulated, with a deeper zone at lower crustal levels or near the crust-mantle boundary (>15 km depth), a second zone at mid-crustal levels (~10 km depth) and several magma storage zones distributed throughout the uppermost crust (<10 km depth). Plagioclase-melt and amphibole hygrometry indicate magmatic H2O contents ranging from ~8.1 to 8.6 wt.% in the lower crustal system to ~1.5 to 3.3 wt.% in the mid to upper crust. Pyroxene and plagioclase ?18O values range from 5.4 to 6.7 ‰, and 6.5 to 7.6 ‰, respectively. A single whole rock analysis of the 2007-2008 dome lava gave a ?18O value of 7.6 ‰, whereas meta-basaltic and calc-silicate xenoliths are characterised by ?18O values of 6.2 and 10.3 ‰, respectively. Magmatic ?18O values calculated from individual pyroxene and plagioclase analyses range from 5.7 to 7.0 ‰, and 6.2 to 7.4 ‰, respectively. This range in O-isotopic compositions is explained by crystallisation of pyroxenes in the lower to mid-crust, where crustal contamination is either absent or masked by assimilation of material having similar ?18O values to the ascending melts. This population is mixed with isotopically distinct plagioclase and pyroxenes that crystallised from a more contaminated magma in the upper crustal system. Binary bulk mixing models suggest that shallow-level, recycled volcaniclastic sedimentary rocks together with calc-silicates and/or limestones are the most likely contaminants of the 2007-2008 Kelut magma, with the volcaniclastic sediments being dominant.

Jeffery, A. J.; Gertisser, R.; Troll, V. R.; Jolis, E. M.; Dahren, B.; Harris, C.; Tindle, A. G.; Preece, K.; O'Driscoll, B.; Humaida, H.; Chadwick, J. P.

2013-07-01

68

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

69

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

70

Volcano Preparedness  

MedlinePLUS

... your local emergency officials. Mudflows Mudflows are powerful “rivers” of mud that can move 20 to 40 ... cannot see the volcano during an eruption. Avoid river valleys and low lying areas. Trying to watch ...

71

Dante's Volcano  

NASA Technical Reports Server (NTRS)

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

1994-01-01

72

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

73

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

74

Ke 'Ano Ola: Moloka'i's Community-Based Healthy Lifestyle Modification Program  

PubMed Central

We evaluated a community-based 12-week healthy lifestyle program in Moloka‘i, HI, called Ke ‘Ano Ola, which was developed to decrease chronic disease risk through health education emphasizing weight loss, exercise, and risk factor reduction. Program leaders' strong commitment and positive role modeling, along with social and group support and community involvement, were key elements. A pre–post evaluation of weight, blood pressure, total cholesterol, and blood sugar showed significant improvements for weight (mean change [?] = ?7.4 lbs; P < .001), systolic blood pressure (? = –3.8 mm Hg; P = .027), diastolic blood pressure (? = –4.6 mm Hg; P < .001), and total cholesterol (? = –9.7 mg/dL; P < .001). Attrition was low, with 89% of participants attending all 12 sessions. Our findings show that lifestyle improvements in a predominantly Native Hawaiian community are achievable in a support group setting. PMID:20299650

Aubert, Ronald E.; Mikami, Judith S.

2010-01-01

75

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

USGS Publications Warehouse

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 hydrologie 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. Copyright 2009 by the American Geophysical Union.

Prouty, N. G.; Jupiter, S. D.; Field, M. E.; McCulloch, M. T.

2009-01-01

76

Cascades Volcano Observatory  

NSDL National Science Digital Library

The Cascades Volcano Observatory of the U.S. Geological Survey has announced a WWW server offering information on volcanically-induced geologic and hydrologic hazards as well as images of volcanoes and volcanic phenomena. Includes links to ther components of the USGS Volcano Hazards Program such as the Alaska and Hawaii Volcano Observatory and the international Volcano Disaster Assistance Program.

77

Internet Geography: Volcanoes  

NSDL National Science Digital Library

This site is part of GeoNet Internet Geography, a resource for pre-collegiate British geography students and their instructors. This page focuses on various aspects of volcanoes, including the main features of a volcano, types of volcanoes, the Ring of Fire, locations of volcanoes, volcanic flows, and case studies about specific volcanoes.

78

What Are Volcano Hazards?  

MedlinePLUS

... Hawaii, California, Oregon, and Washington. Volcanoes produce a wide variety of hazards that can kill people and ... a volcano is not erupting. Volcanoes produce a wide variety of natural hazards that can kill people ...

79

Volcanic gas impacts on vegetation at Turrialba Volcano, Costa Rica  

Microsoft Academic Search

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

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

2010-01-01

80

20 months of sustained changes at Turrialba volcano. Visual changes  

Microsoft Academic Search

Turrialba Volcano (3340 m) is located at the southern end of the Mesoamerican Volcanic Arc. The summit area has three craters aligned NE-SW: East, Central and West craters. The last active period of Turrialba Volcano occurred between 1864-1866. During this period, the West crater of Turrialba was formed and ash falls were reported in the Central Valley of Costa Rica.

E. Duarte; E. Fernandez; W. Saenz; M. Martinez; V. Barboza

2007-01-01

81

Geochemistry of ash leachates during the 1994–1996 activity of Popocatépetl volcano  

Microsoft Academic Search

Increasing fumarolic activity at Popocatépetl volcano has been observed since 1992. On 21 December 1994, a series of eruptions at Popocatépetl volcano produced ash emissions that reached the city of Puebla located to the east of the volcano. Eruptive activity declined sharply from June 1995 until 5 March 1996 when ash emissions and fumarole flux increased to levels similar to

Ma Aurora Armienta; A. L. Martin-Del-Pozzo; R. Espinasa; O. Cruz; N. Ceniceros; A. Aguayo; M. A. Butron

1998-01-01

82

Structural setting of gold deposits in the Oudalan-Gorouol volcano-sedimentary belt east of the Markoye Shear Zone, West African Craton  

NASA Astrophysics Data System (ADS)

The Oudalan-Gorouol volcano-sedimentary belt (OGB) of Burkina Faso and Niger hosts meta-volcanic and metasedimentary sequences of the Birimian Supergroup that were folded and deformed during emplacement of the Dori Batholith (D1-x), the Tangaean Event (D1) and the Eburnean Orogeny (D2). The emplacement of the Dori Batholith accompanied aureole deformation (D1-x) and the development of proto-mylonite, migmatite, gneiss and schist on the northern margin of the batholith. Contact metamorphic grade reached granulite facies with partial melting of the supracrustal sequences. Emplacement of the Dori Batholith was succeeded by emplacement of monzonite dykes and sills through the OGB. The Tangaean Event (D1) accompanied formation of (a) the Saoga Branch of the Markoye Shear Zone (MSZ), (b) the Mukosi and Billiata mylonite zones that are hosted in the MSZ, (c) the Afu Branch of the Kargouna Shear Zone Complex (KSZC), and (d) northwest-trending thrust-folds (F1) that crosscut the OGB and coalesce with the MSZ. Metamorphic grade attained amphibolite facies in mylonite or proto-mylonite zones in the Saoga and Afu branches. D1 was succeeded by emplacement of alkali-granite plutons of the Dolbel Batholith. The Eburnean Orogeny, D2, accompanied formation of (a) the Korizéna Branch of the MSZ, (b) the Waho Branch of the KSZC, and (c) northeast-trending shear-faults that crosscut the OGB. D2 is manifested by refolding of F1 by northeast-trending F2, and development of a pervasive northeast-trending S2 to S2-C. Metamorphic grade attained greenschist facies during D2 with development of the mineral assemblage quartz-chlorite-muscovite ± actinolite. D2 was succeeded by emplacement of northwest-trending gabbro and dolerite dykes. The OGB hosts structurally-controlled gold deposits that are sited along five metallogenic corridors and include the Essakane, Tin-Fal, Bom Kodjelé, Kossa and Tassiri Trends. Gold mineralisation is preferentially located where northeast-trending faults and shears crosscut northwest-trending thrust-folds, or where northwest-trending thrust-folds coalesce with north-northeast trending shears. An intimate relationship thus exists between D1 and D2 structures and gold mineralisation in the OGB. Gold in sheeted-stockwork veins is hosted in competent rocks units including conglomerate beds, greywacke, quartzite, monzonite dykes, pyroxenite-gabbro sills and D1 buck quartz veins. Gold in fine veinlets may also be hosted in massive shale units.

Tshibubudze, Asinne; Hein, Kim A. A.

2013-04-01

83

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

84

Kilauea volcano eruption seen from orbit  

NASA Technical Reports Server (NTRS)

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

1993-01-01

85

Hawaiian Volcano Observatory  

NSDL National Science Digital Library

As part of the US Geological Survey, the Hawaiian Volcano Observatory (HVO) is charged with monitoring and researching volcanoes in Hawaii. The site provides current activity reports, hazard information, and a history of the two main volcanoes, Kilauea and Mauna Loa. In addition, the site provides information on three other volcanoes that are either active or potentially active. Visitors can also learn about earthquakes in Hawaii and the particular hazards posed by volcanos. Captivating photos help bring the volcanoes to life. Visitors can patronize the Photo Gallery for additional volcano photos. Cross links to additional information and sites are provided on every page.

86

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.

87

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

88

Diurnal variability in turbidity and coral fluorescence on a fringing reef flat: Southern Molokai, Hawaii  

USGS Publications Warehouse

Terrigenous sediment in the nearshore environment can pose both acute and chronic stresses to coral reefs. The reef flat off southern Molokai, Hawaii, typically experiences daily turbidity events, in which trade winds and tides combine to resuspend terrigenous sediment and transport it alongshore. These chronic turbidity events could play a role in restricting coral distribution on the reef flat by reducing the light available for photosynthesis. This study describes the effects of these turbidity events on the Hawaiian reef coral Montipora capitata using in situ diurnal measurements of turbidity, light levels, and chlorophyll fluorescence yield via pulse-amplitude-modulated (PAM) fluorometry. Average surface irradiance was similar in the morning and the afternoon, while increased afternoon turbidity resulted in lower subsurface irradiance, higher fluorescence yield (??F/Fm???), and lower relative electron transport rates (rETR). Model calculations based on observed light extinction coeffecients suggest that in the absence of turbidity events, afternoon subsurface irradiances would be 1.43 times higher than observed, resulting in rETR for M. capitata that are 1.40 times higher.

Piniak, G.A.; Storlazzi, C.D.

2008-01-01

89

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.

90

Preliminary volcano-hazard assessment for Mount Spurr Volcano, Alaska  

USGS Publications Warehouse

Mount Spurr volcano is an ice- and snow-covered stratovolcano complex located in the north-central Cook Inlet region about 100 kilometers west of Anchorage, Alaska. Mount Spurr volcano consists of a breached stratovolcano, a lava dome at the summit of Mount Spurr, and Crater Peak vent, a small stratocone on the south flank of Mount Spurr volcano. Historical eruptions of Crater Peak occurred in 1953 and 1992. These eruptions were relatively small but explosive, and they dispersed volcanic ash over areas of interior, south-central, and southeastern Alaska. Individual ash clouds produced by the 1992 eruption drifted east, north, and south. Within a few days of the eruption, the south-moving ash cloud was detected over the North Atlantic. Pyroclastic flows that descended the south flank of Crater Peak during both historical eruptions initiated volcanic-debris flows or lahars that formed temporary debris dams across the Chakachatna River, the principal drainage south of Crater Peak. Prehistoric eruptions of Crater Peak and Mount Spurr generated clouds of volcanic ash, pyroclastic flows, and lahars that extended to the volcano flanks and beyond. A flank collapse on the southeast side of Mount Spurr generated a large debris avalanche that flowed about 20 kilometers beyond the volcano into the Chakachatna River valley. The debris-avalanche deposit probably formed a large, temporary debris dam across the Chakachatna River. The distribution and thickness of volcanic-ash deposits from Mount Spurr volcano in the Cook Inlet region indicate that volcanic-ash clouds from most prehistoric eruptions were as voluminous as those produced by the 1953 and 1992 eruptions. Clouds of volcanic ash emitted from the active vent, Crater Peak, would be a major hazard to all aircraft using Ted Stevens Anchorage International Airport and other local airports and, depending on wind direction, could drift a considerable distance beyond the volcano. Ash fall from future eruptions could disrupt many types of economic and social activities, including oil and gas operations and shipping activities in the Cook Inlet area. Eruptions of Crater Peak could involve significant amounts of ice and snow that would lead to the formation of large lahars, formation of volcanic debris dams, and downstream flooding. The greatest hazards in order of importance are described below and shown on plate 1.

Waythomas, Christopher F.; Nye, Christopher J.

2001-01-01

91

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

92

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.

93

Molokai Farm Project. An Agricultural Training Program of the Maui Community College, University of Hawaii. Report for Fiscal Year 1982-83.  

ERIC Educational Resources Information Center

The Molokai Farm Project at Maui Community College grew out of a grant for a Youth Agricultural Entrepreneurship Demonstration Program. The program, which can lead either to an associate degree or to a certification of completion for any number of smaller units of course work, is designed to develop students' managerial proficiency and the…

Hawaii State Dept. of Agriculture, Honolulu.

94

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

95

Iceland: Eyjafjallajökull Volcano  

article title:  Ash from Eyjafjallajökull Volcano, Iceland Stretches over the North Atlantic   ... that occurred in late March 2010, the Eyjafjallajökull Volcano in Iceland began erupting again on April 14, 2010. The resulting ash ...

2013-04-17

96

Database for the Geologic Map of Newberry Volcano, Deschutes, Klamath, and Lake Counties, Oregon  

USGS Publications Warehouse

Newberry Volcano, one of the largest Quaternary volcanoes in the conterminous United States, is a broad shield-shaped volcano measuring 60 km north-south by 30 km east-west with a maximum elevation of more than 2 km. Newberry Volcano is the product of deposits from thousands of eruptions, including at least 25 in the past approximately 12,000 years (Holocene Epoch). Newberry Volcano has erupted as recently as 1,300 years ago, but isotopic ages indicate that the volcano began its growth as early as 0.6 million years ago. Such a long eruptive history and recent activity suggest that Newberry Volcano is likely to erupt in the future. This geologic map database of Newberry Volcano distinguishes rocks and deposits based on their composition, age, and lithology.

Bard, Joseph A.; Ramsey, David W.; MacLeod, Norman S.; Sherrod, David R.; Chitwood, Lawrence A.; Jensen, Robert A.

2013-01-01

97

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

98

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

99

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

100

Monitoring Active Volcanoes  

NSDL National Science Digital Library

This United States Geological Survey (USGS) publication discusses the historic and current monitoring of active volcanoes around the globe. Techniques to measure deviations in pressure and stress induced by subterranean magma movement, as well as other technologies, explain the ways in which researchers monitor and predict volcanoes. Case studies of volcanoes such as Mt. St. Helens, El Chichon, Mauna Loa, and others are discussed.

Tilling, Robert

101

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

102

The hydrogeology of Kilauea volcano  

SciTech Connect

The hydrogeology of Kilauea volcano and adjacent areas has been studied since the turn of this century. However, most studies to date have focused on the relatively shallow, low-salinity parts of the ground-water system, and the deeper hydrothermal system remains poorly understood. The rift zones of adjacent Mauna Loa volcano bound the regional ground-water flow system that includes Kilauea, and the area bounded by the rift zones of Kilauea and the ocean may comprise a partly isolated subsystem. Rates of ground-water recharge vary greatly over the area, and discharge is difficult to measure, because streams are ephemeral and most ground-water discharges diffusely at or below sea level. Hydrothermal systems exist at depth in Kilauea's east and southwest rift zone, as evidenced by thermal springs at the coast and wells in the lower east-rift zone. Available data suggest that dike-impounded, heated ground water occurs at relatively high elevations in the upper east- and southwest-rift zones of Kilauea, and that permeability at depth in the rift zones. Available data suggest that dike-impounded, heated ground water occurs at relatively high elevations in the upper east- and southwest-rift zones of Kilauea, and that permeability at depth in the rift zones (probably [le]10[sup [minus]15] m[sup 2]) is much lower than that of unaltered basalt flows closer to the surface ([ge]10[sup [minus]10] m[sup 2]). Substantial variations in permeability and the presence of magmatic heat sources influence that structure of the fresh water-salt water interface, so the Ghyben-Herzberg model will often fail to predict its position. Numerical modeling studies have considered only subsets of the hydrothermal system, because no existing computer code solves the coupled fluid-flow, heat- and solute-transport problem over the temperature and salinity range encountered at Kilauea. 73 refs., 7 figs., 2 tabs.

Ingebritsen, S.E.; Scholl, M.A. (Geological Survey, Menlo Park, CA (United States))

1993-08-01

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

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

105

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

USGS Publications Warehouse

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 trapped sediment, floods recharged the reef flat with land-derived sediment, but had a low potential for burying coral on the fore reef when accompanied by high waves. The trapped sediments have low concentrations of anthropogenic metals. The magnetic properties of trapped sediment may provide information about the sources of land-derived sediment reaching the fore reef. The high trapping rate and low sediment cover indicate that coral surfaces on the fore reef are exposed to transient resuspended sediment, and that the traps do not measure net sediment accumulation on the reef surface.

Bothner, M.H.; Reynolds, R.L.; Casso, M.A.; Storlazzi, C.D.; Field, M.E.

2006-01-01

106

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

PubMed

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 trapped sediment, floods recharged the reef flat with land-derived sediment, but had a low potential for burying coral on the fore reef when accompanied by high waves. The trapped sediments have low concentrations of anthropogenic metals. The magnetic properties of trapped sediment may provide information about the sources of land-derived sediment reaching the fore reef. The high trapping rate and low sediment cover indicate that coral surfaces on the fore reef are exposed to transient resuspended sediment, and that the traps do not measure net sediment accumulation on the reef surface. PMID:16545399

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

2006-09-01

107

Demise of reef-flat carbonate accumulation with late Holocene sea-level fall: Evidence from Molokai, Hawaii  

USGS Publications Warehouse

Twelve cores from the protected reef-flat of Molokai revealed that carbonate sediment accumulation, ranging from 3 mm year-1 to less than 1 mm year-1, ended on average 2,500 years ago. Modern sediment is present as a mobile surface veneer but is not trapped within the reef framework. This finding is consistent with the arrest of deposition at the end of the mid-Holocene highstand, known locally as the "Kapapa Stand of the Sea," ???2 m above the present datum ca. 3,500 years ago in the main Hawaiian Islands. Subsequent erosion, non-deposition, and/or a lack of rigid binding were probable factors leading to the lack of reef-flat accumulation during the late Holocene sea-level fall. Given anticipated climate changes, increased sedimentation of reef-flat environments is to be expected as a consequence of higher sea level. ?? 2008 Springer-Verlag.

Engels, M. S.; Fletcher, C. H.; Field, M.; Conger, C. L.; Bochicchio, C.

2008-01-01

108

Lahar Hazards at Casita and San Cristóbal Volcanoes, Nicaragua  

USGS Publications Warehouse

Casita and San Cristóbal volcanoes are part of a volcano complex situated at the eastern end of the Cordillera de los Maribios. Other centers of volcanism in the complex include El Chonco, Cerro Moyotepe, and La Pelona. At 1745 m, San Cristóbal is the highest and only historically active volcano of the complex. The volcano’s crater is 500 to 600 m across and elongate east to west; its western rim is more than 100 m higher than its eastern rim. The conical volcano is both steep and symmetrical. El Chonco, which lies west of San Cristóbal, is crudely conical but has been deeply dissected by streams. Cerro Moyotepe to the northeast of San Cristóbal is even more deeply incised by erosion than El Chonco, and its crater is breached by erosion. Casita volcano, about 5 km east of San Cristóbal volcano, comprises a broad ridge like form, elongate along an eastwest axis, that is deeply dissected. Nested along the ridge are two craters. The younger one, La Ollada crater, truncates an older smaller crater to the east near Casita’s summit (1430 m). La Ollada crater is about 1 km across and 100 m deep. Numerous small fumarole fields occur near the summit of Casita and on nearby slopes outside of the craters. Casita volcano overlaps the 3-km-wide crater of La Pelona to the east. Stream erosion has deeply incised the slopes of La Pelona, and it is likely the oldest center of the Casita-San Cristóbal volcano complex. In late October and early November 1998, torrential rains of Hurricane Mitch caused numerous slope failures in Central America. The most catastrophic occurred at Casita volcano, on October 30, 1998. At Casita, five days of heavy rain triggered a 1.6-million-cubic-meter rock and debris avalanche that generated an 2- to 4- million-cubic-meter debris flow that swept down the steep slopes of the volcano. The debris flow spread out across the volcano’s apron, destroyed two towns, and killed more than 2500 people. In prehistoric time, Casita erupted explosively to form ash-fall deposits (tephra), debris avalanches, lava flows, and hot flowing mixtures of ash and rock (called pyroclastic flows). The chronology of activity at Casita is rather poorly known. Its last documented eruption occurred 8300 years ago, and included a pyroclastic flow. Tephra deposits exposed in the east crater suggest the possibility of subsequent eruptions. Work prior to Hurricane Mitch suggested that a part of the volcano’s apron that included the area inundated during the 1998 event south of Casita was a lahar pathway. Erosion during Hurricane Mitch revealed that at least three large lahars descended this pathway to distances of up to 10 km. This report describes the hazards of landslides and lahars in general, and discusses potential hazards from future landslides and lahars at San Cristóbal and Casita volcanoes in particular. The report also shows, in the accompanying lahar hazard-zonation maps, which areas are likely to be at risk from future landslides and lahars at Casita and San Cristóbal.

Vallance, J.W.; Schilling, S.P.; Devoli, G.; Reid, M.E.; Howell, M.M.; Brien, D.L.

2004-01-01

109

Volcanoes, Observations and Impact  

NASA Astrophysics Data System (ADS)

Volcanoes are critical geologic hazards that challenge our ability to make long-term forecasts of their eruptive behaviors. They also have direct and indirect impacts on human lives and society. As is the case with many geologic phenomena, the time scales over which volcanoes evolve greatly exceed that of a human lifetime. On the other hand, the time scale over which a volcano can move from inactivity to eruption can be rather short: months, weeks, days, and even hours. Thus, scientific study and monitoring of volcanoes is essential to mitigate risk. There are thousands of volcanoes on Earth, and it is impractical to study and implement ground-based monitoring at them all. Fortunately, there are other effective means for volcano monitoring, including increasing capabilities for satellite-based technologies.

Thurber, Clifford; Prejean, Stephanie

110

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

111

Degassing from a Mafic Alkaline Shield Volcano: Nyamulagira, D.R. Congo  

Microsoft Academic Search

Nyamulagira (D.R. Congo) is a highly effusive, alkaline mafic shield volcano located in the western branch of the East African Rift. Due to political instability that limits access to the volcano, satellite remote sensing is invaluable for monitoring its activity, which threatens the local population and infrastructure. Cumulative sulfur dioxide (SO2) emissions during 15 eruptions of Nyamulagira between 1980 and

E. M. Head; S. A. Carn; K. W. Sims; A. M. Shaw; P. J. Wallace; A. Maclean

2009-01-01

112

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

113

Volcanoes generate devastating waves  

Microsoft Academic Search

Although volcanic eruptions can cause many frightening phenomena, it is often the power of the sea that causes many volcano-related deaths. This destruction comes from tsunamis (huge volcano-generated waves). Roughly one-fourth of the deaths occurring during volcanic eruptions have been the result of tsunamis. Moreover, a tsunami can transmit the volcano's energy to areas well outside the reach of the

Lockridge

1988-01-01

114

Alaska Volcano Observatory Monitoring Station  

USGS Multimedia Gallery

An Alaska Volcano Observatory Monitoring station with Peulik Volcano behind. This is the main repeater for the Peulik monitoring network located on Whale Mountain, Beecharaof National Wildlife Refuge....

2009-12-08

115

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

Microsoft Academic Search

Boron samples from 40 fumarolic condensates from volcanoes in the Ryukyu arc (Satsuma Iwo-jima and Shiratori Iwo-yama) and the North-east Japan arc (Usu-shinzan, Showa-shinzan, Esan and Issaikyo-yama) all have 11 B \\/ 10 B ratios close to 4.07. Higher values, from 4.09 to 4.13, were only observed in condensates from volcanoes in the southernmost end of the North-east Japan arc

Masao Nomura; Tadeo Kanzaki; Takejiro Ozawa; Makoto Okamoto; Hidetake Kakihana

1982-01-01

116

Iceland: Eyjafjallajökull Volcano  

... to capture a series of images of the Eyjafjallajökull volcano and its erupting ash plume. Figure 1 is a view from MISR's nadir ... The companion image, Figure 2, is a stereo anaglyph (see  Volcano Plume Heights Anaglyph ) generated from the nadir and 46-degree ...

2013-04-17

117

Iceland: Eyjafjallajökull Volcano  

... height map   Ash from Iceland's Eyjafjallajökull volcano, viewed here in imagery from the Multi-angle Imaging SpectroRadiometer ... natural-color, nadir (vertical) view of the scene, with the volcano itself located outside the upper left corner of the image. The ash ...

2013-04-17

118

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.

119

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.

120

Anatomy of a Volcano  

NSDL National Science Digital Library

This interactive lesson 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.

2010-12-14

121

Thermal and mechanical development of the East African Rift System  

E-print Network

The deep basins, uplifted flanks, and volcanoes of the Western and Kenya rift systems have developed along the western and eastern margins of the 1300 km-wide East African plateau. Structural patterns deduced from field, ...

Ebinger, Cynthia Joan

1988-01-01

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

Mechanism of explosive eruptions of Kilauea Volcano, Hawaii  

Microsoft Academic Search

A small explosive eruption of Kilauea Volcano, Hawaii, occurred in May 1924. The eruption was preceded by rapid draining of a lava lake and transfer of a large volume of magma from the summit reservoir to the east rift zone. This lowered the magma column, which reduced hydrostatic pressure beneath Halemaumau and allowed groundwater to flow rapidly into areas of

John J. Dvorak

1992-01-01

124

Reunion Island Volcano Erupts  

NASA Technical Reports Server (NTRS)

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

2002-01-01

125

CO32- concentration and pCO2 thresholds for calcification and dissolution on the Molokai reef flat, Hawaii  

USGS Publications Warehouse

The severity of the impact of elevated atmospheric pCO2 to coral reef ecosystems depends, in part, on how sea-water pCO2 affects the balance between calcification and dissolution of carbonate sediments. Presently, there are insufficient published data that relate concentrations of pCO 2 and CO32- to in situ rates of reef calcification in natural settings to accurately predict the impact of elevated atmospheric pCO2 on calcification and dissolution processes. Rates of net calcification and dissolution, CO32- concentrations, and pCO2 were measured, in situ, on patch reefs, bare sand, and coral rubble on the Molokai reef flat in Hawaii. Rates of calcification ranged from 0.03 to 2.30 mmol CaCO3 m-2 h-1 and dissolution ranged from -0.05 to -3.3 mmol CaCO3 m-2 h-1. Calcification and dissolution varied diurnally with net calcification primarily occurring during the day and net dissolution occurring at night. These data were used to calculate threshold values for pCO2 and CO32- at which rates of calcification and dissolution are equivalent. Results indicate that calcification and dissolution are linearly correlated with both CO32- and pCO2. Threshold pCO2 and CO32- values for individual substrate types showed considerable variation. The average pCO2 threshold value for all substrate types was 654??195 ??atm and ranged from 467 to 1003 ??atm. The average CO32- threshold value was 152??24 ??mol kg-1, ranging from 113 to 184 ??mol kg-1. Ambient seawater measurements of pCO2 and CO32- indicate that CO32- and pCO2 threshold values for all substrate types were both exceeded, simultaneously, 13% of the time at present day atmospheric pCO2 concentrations. It is predicted that atmospheric pCO2 will exceed the average pCO2 threshold value for calcification and dissolution on the Molokai reef flat by the year 2100.

Yates, K.K.; Halley, R.B.

2006-01-01

126

Volcanoes. A planetary perspective.  

NASA Astrophysics Data System (ADS)

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

Francis, P.

127

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.

128

Vent of Sand Volcano  

USGS Multimedia Gallery

Vent of sand volcano produced by liquefaction is about 4 ft across in strawberry field near Watsonville. Strip spanning vent is conduit for drip irrigation system. Furrow spacing is about 1.2 m (4 ft) on center....

2009-01-26

129

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.

130

Preliminary Geologic Map of Newberry Volcano, Oregon  

NASA Astrophysics Data System (ADS)

The late Pleistocene and Holocene rear-arc Newberry Volcano is located in central Oregon east of the Cascades arc axis. Total area covered by the broad, shield-shaped edifice and its accompanying lava field is about 3,200 square kilometers, encompassing all or part of 38 U.S.G.S. 1:24,000-scale quadrangles. Distance from the northernmost extent of lava flows to the southernmost is about 115 km; east-west maximum width is less than 50 km. A printed version of the preliminary map at its intended publication scale of 1:50,000 is 8 ft high by 4 ft wide. More than 200 units have been identified so far, each typically consisting of the lava flow(s) and accompanying vent(s) that represent single eruptive episodes, some of which extend 10’s of kilometers across the edifice. Vents are commonly aligned north-northwest to north-northeast, reflecting a strong regional tectonic influence. The largest individual units on the map are basaltic, some extending nearly 50 km to the north through the cities of Bend and Redmond from vents low on the northern flank of the volcano. The oldest and most distal of the basalts is dated at about 350 ka. Silicic lava flows and domes are confined to the main edifice of the volcano; the youngest rhyolite flows are found within Newberry Caldera, including the rhyolitic Big Obsidian Flow, the youngest flow at Newberry Volcano (~1,300 yr B.P.). The oldest known rhyolite dome is dated at about 400 ka. Andesite units (those with silica contents between 57% and 63%) are the least common, with only 13 recognized to date. The present 6.5 by 8 km caldera formed about 75 ka with the eruption of compositionally-zoned rhyolite to basaltic andesite ash-flow tuff. Older widespread silicic ash-flow tuffs imply previous caldera collapses. Approximately 20 eruptions have occurred at Newberry since ice melted off the volcano in latest Pleistocene time. The mapping is being digitally compiled as a spatial geodatabase in ArcGIS. Within the geodatabase, feature classes have been created representing geologic lines (contacts, faults, lava tubes, etc.), geologic unit polygons, and volcanic vent location points. The geodatabase can be queried to determine the spatial distributions of different rock types, geologic units, and other geologic and geomorphic features. Map colors are being used to indicate compositions. Some map patterns have been added to distinguish the youngest lavas and the ash-flow tuffs. Geodatabase information can be used to better understand the evolution, growth, and potential hazards of the volcano.

Donnelly-Nolan, J. M.; Ramsey, D. W.; Jensen, R. A.; Champion, D. E.; Calvert, A. T.

2010-12-01

131

Exceptional sulphur degassing from Nyamuragira volcano, 1979-2005 G.J.S. BLUTH and S.A. CARN  

E-print Network

shield volcano within the western branch of the East African Rift Valley in DR Congo, 14 km NW above sea level, with a 2 x 2.3 km caldera. Historical lava flows extend down the volcano's flanks more century a lava lake. Associated seismic activity includes swarms of long- period events, signalling

Bluth, Gregg

132

What is a volcano?  

NASA Astrophysics Data System (ADS)

In a volcano, magma, generated at a source in a planetary interior, flows upward with varying amounts of physicochemical evolution, intruding the encasing rocks. Once near the top of the lithosphere, that is at a major rigid-fluid, high-low-density interface, the magma erupts, piercing this interface. While gas, vapors and thinnest particles mix up with the atmosphere and stratosphere, larger drops and particles will eventually accumulate on top of the interface to form volcanic deposits, giving rise in the area around the crater to a volcanic edifice. In turn, these deposits may be intruded or modified by magma, eruptions, geothermal fluids, tectonics, erosion, landsliding and all other kinds of geologic processes. In this view, volcanism is a self-similar process that ranges many orders of magnitude in space and time scales from small cinder cones to large ocean ridges. For instance, at Amiata Volcano, Italy, many of the above mentioned processes have interacted. The volcano is deeply dissected by volcanic spreading, to the point of loosing its original cone-like shape; large diapirs and thrust-related structure have formed in the clay- and gypsum-rich substratum all around the volcano generating dismembered lava flows. In addition, the spreading have created the conditions for the existence of mercury mineralization and geothermal reservoirs. All this complexity that, in our opinion must be considered volcanic is not easy described by commonly used definitions of volcanoes. In fact, former definitions of "volcano", for instance that from the Glossary of Geology (1997) "a vent in the surface of the Earth through which magma and associated gases and ash erupt" or "the form or structure, usually conical, that is produced by the ejected material" are clearly insufficient and cannot capture the geologic complexity of a real volcanic environment. All definitions, that we encountered, tend to consider volcanoes from the point of view of a single discipline, each of them neglecting relevant aspects belonging to other disciplines. For the two cases mentioned above a volcano is seen only from the point of view of eruptive activity or of morphology. We attempt to look at "volcano" holistically to provide a more comprehensive definition. We define a volcano as a geologic environment that, at any scale, is characterized by three elements: magma, eruption and edifice. It is sufficient that only one of these elements is proven, as long as the others can be inferred to exist, to have existed, or that will exist.

Borgia, A.; Merle, O.; van Wyk de Vries, B.; Aubert, M.

2007-05-01

133

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

134

Optimizing remote sensing and GIS tools for mapping and managing the distribution of an invasive mangrove (Rhizophora mangle) on South Molokai, Hawaii  

USGS Publications Warehouse

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 accuracy for various sensor-technique combinations. ANOVA of accuracy assessments demonstrated significant differences among techniques, but no significant differences among the three sensors. We summarize advantages and disadvantages of each sensor and technique for mapping mangrove distributions in tropical coastal environments.

D'Iorio, M.; Jupiter, S. D.; Cochran, S. A.; Potts, D. C.

2007-01-01

135

Flood-Frequency Estimates for Streams on Kaua`i, O`ahu, Moloka`i, Maui, and Hawai`i, State of Hawai`i  

USGS Publications Warehouse

This study provides an updated analysis of the magnitude and frequency of peak stream discharges in Hawai`i. Annual peak-discharge data collected by the U.S. Geological Survey during and before water year 2008 (ending September 30, 2008) at stream-gaging stations were analyzed. The existing generalized-skew value for the State of Hawai`i was retained, although three methods were used to evaluate whether an update was needed. Regional regression equations were developed for peak discharges with 2-, 5-, 10-, 25-, 50-, 100-, and 500-year recurrence intervals for unregulated streams (those for which peak discharges are not affected to a large extent by upstream reservoirs, dams, diversions, or other structures) in areas with less than 20 percent combined medium- and high-intensity development on Kaua`i, O`ahu, Moloka`i, Maui, and Hawai`i. The generalized-least-squares (GLS) regression equations relate peak stream discharge to quantified basin characteristics (for example, drainage-basin area and mean annual rainfall) that were determined using geographic information system (GIS) methods. Each of the islands of Kaua`i,O`ahu, Moloka`i, Maui, and Hawai`i was divided into two regions, generally corresponding to a wet region and a dry region. Unique peak-discharge regression equations were developed for each region. The regression equations developed for this study have standard errors of prediction ranging from 16 to 620 percent. Standard errors of prediction are greatest for regression equations developed for leeward Moloka`i and southern Hawai`i. In general, estimated 100-year peak discharges from this study are lower than those from previous studies, which may reflect the longer periods of record used in this study. Each regression equation is valid within the range of values of the explanatory variables used to develop the equation. The regression equations were developed using peak-discharge data from streams that are mainly unregulated, and they should not be used to estimate peak discharges in regulated streams. Use of a regression equation beyond its limits will produce peak-discharge estimates with unknown error and should therefore be avoided. Improved estimates of the magnitude and frequency of peak discharges in Hawai`i will require continued operation of existing stream-gaging stations and operation of additional gaging stations for areas such as Moloka`i and Hawai`i, where limited stream-gaging data are available.

Oki, Delwyn S.; Rosa, Sarah N.; Yeung, Chiu W.

2010-01-01

136

Living With Volcanoes: The USGS Volcano Hazards Program  

NSDL National Science Digital Library

This report summarizes the Volcano Hazards Program of the United States Geological Survey (USGS). Topics include its goals and activities, some key accomplishments, and a plan for future operations. There are also discussions of active and potentially active volcanoes in the U.S., the role of the USGS volcano observatories, prediction of eruptions, and potential danger to aircraft from volcanic plumes.

2010-11-11

137

Living With Volcanoes: The USGS Volcano Hazards Program  

NSDL National Science Digital Library

This report summarizes the Volcano Hazards Program of the United States Geological Survey (USGS). Topics include its goals and activities, some key accomplishments, and a plan for future operations. There are also discussions of active and potentially active volcanoes in the U.S., the role of the USGS volcano observatories, prediction of eruptions, and potential danger to aircraft from volcanic plumes.

138

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

139

Earthquakes and Volcanoes  

NSDL National Science Digital Library

This activity has students compare maps of plate tectonics with population density maps and to analyze what these maps imply about the relationship between population and seismic hazards. Students will read about and discuss the theory of plate tectonics, map the regions of the United States that are most susceptible to earthquakes and those that have volcanoes, and list the states that lie on plate boundaries. In addition, they will look at a population density map to determine if people avoid living in areas at high risk for earthquakes and volcanoes. Students will also research specific volcanoes or earthquake zones and write pretend letters to residents of these areas describing the risks. This site also contains suggestions for assessment and ideas for extending the lesson.

2001-01-01

140

Erupting Volcano Mount Etna  

NASA Technical Reports Server (NTRS)

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

2002-01-01

141

Vegetation map of the watersheds between Kawela and Kamal? Gulches, Island of Moloka?i, Hawai?i  

USGS Publications Warehouse

In this document we describe the methods and results of a project to produce a large-scale map of the dominant plant communities for an area of 5,118.5 hectares encompassing the Kawela and Kamal? watersheds on the island of Moloka?i, Hawai?i, using digital image analysis of multi-spectral satellite imagery. Besides providing a base map of the area for land managers to use, this vegetation map serves as spatial background for the U.S. Geological Survey’s (USGS) Moloka?i Ridge-to-Reef project, which is an interdisciplinary study of erosion and sediment transport within these watersheds. A total of 14 mapping units were identified for the Kawela-Kamal? project area. The most widespread units were the ??hi?a montane wet or mesic forest and No vegetation or very sparse grasses/shrubs communities, each present in more than 800 hectares, or 16 percent of the mapping area. Next largest were the Kiawe woodland with alien grass understory and ?A?ali?i dry shrubland units, each of which covered more than 500 hectares, or more than 12 percent of the area; followed by the Mixed native mesic shrubland, ?Ilima and mixed grass dry shrubland, Mixed alien grass with ?ilima shrubs, and the Mixed alien forest with alien shrub/grass understory communities, which ranged in size from approximately 391 to 491 hectares, or 7.6 to 9.6 percent of the project site. The other six mapped units covered less than 170 hectares of the landscape. Six of the map units were dominated by native vegetation, covering a total of 2,535.2 hectares combined, or approximately 50 percent of the project area. The remaining map units were dominated by nonnative species and represent vegetation types that have resulted from invasion and establishment of plant species that had been either purposely or accidently introduced into Hawai?i since humans arrived in these islands more than 1,500 years ago. The preponderance of mapping units that are dominated by alien species of plants is a strong indication of how much anthropogenic disturbance has occurred in this area. The native-dominated ??hi?a forest and uluhe fern communities are probably most similar to the vegetation that was originally found in the upper part of the project area this area. Portions of the mixed mesic native shrub community still persist in the lowland mesic zone, but below that area, the vegetation is either dominated by alien species, or artificially opened by animal grazing and erosion, even in the few units that are still dominated by native species. The map produced for the Kawela to Kamal? watersheds can be used as a baseline for assessing the distribution and abundance of the various plant communities found across this landscape at the time of the imagery (2004). It can also be used to help understand the dynamics of the vegetation and other attributes of this watershed—such as erosion and surface transport of sediment, relative to current and future habitat conditions.

Jacobi, James D.; Ambagis, Stephen

2013-01-01

142

The Worlds Deadliest Volcanoes  

NSDL National Science Digital Library

At this interactive site the student attempts to rate the eruption of a volcano according to the Volcanic Explosive Index (VEI). After seeing the step by step eruption of an actual volcano, the student is introduced to VEI scale, which includes a description of the eruption, volume of ejected material, plume height, eruption type, duration, total known eruptions with that VEI, and an example. Each factor is linked to a section where it is explained in detail. After evaluating all of the factors and rating them, the student selects a VEI number and clicks for feedback. The correct answer is given with an explanation.

143

The nature of «Umsini Volcano», Irian Jaya, Indonesia  

NASA Astrophysics Data System (ADS)

Mount Umsini («Oemsini») is internationally listed as an active volcano in the Bird’s head of Irian Jaya (New Guinea). The mountain occurs at the north end of the Arfak Range that consists of tilted and presumably folded early turbidite sequences and volcano-clastic rocks that were intruded by Early Oligocene gabbroic rocks. The morphology is characterized by NNW-striking, long mountain ranges with parallel drainage and on the east side of the range by dendritic patterns. We conclude from the absence of any volcanic activity, crater relicts and general morphology, and lithology, that Mount Umsini is not a volcano and that the actual name of the mountain is Umcen (pronounced «oumchen»).

Tjia, H. D.; Hadian, R.; Sumailani, A. R.; Martono, A.

1980-09-01

144

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

145

The Three Little Volcanoes  

NSDL National Science Digital Library

In this worksheet students identify and label the characteristic features of shield, cinder cone and composite volcanoes. The resource is part of the teacher's guide accompanying the video, NASA Why Files: The Case of the Mysterious Red Light. Lesson objectives supported by the video, additional resources, teaching tips and an answer sheet are included in the teacher's guide.

146

Santa Maria Volcano, Guatemala  

NASA Technical Reports Server (NTRS)

The eruption of Santa Maria volcano in 1902 was one of the largest eruptions of the 20th century, forming a large crater on the mountain's southwest flank. Since 1922, a lava-dome complex, Santiaguito, has been forming in the 1902 crater. Growth of the dome has produced pyroclastic flows as recently as the 2001-they can be identified in this image. The city of Quezaltenango (approximately 90,000 people in 1989) sits below the 3772 m summit. The volcano is considered dangerous because of the possibility of a dome collapse such as one that occurred in 1929, which killed about 5000 people. A second hazard results from the flow of volcanic debris into rivers south of Santiaguito, which can lead to catastrophic flooding and mud flows. More information on this volcano can be found at web sites maintained by the Smithsonian Institution, Volcano World, and Michigan Tech University. ISS004-ESC-7999 was taken 17 February 2002 from the International Space Station using a digital camera. The image is provided by the Earth Sciences and Image Analysis Laboratory at Johnson Space Center. Searching and viewing of additional images taken by astronauts and cosmonauts is available at the NASA-JSC Gateway to

2002-01-01

147

The Super Volcano Game  

NSDL National Science Digital Library

How would you handle a volcano diasater? In this game, you've just been appointed chief of the Emergency Management Agency for Bluebear County. Everyone is counting on you to handle the eruption of Mount Spur. Download this game to find out. Before you play, make sure Flash is installed on your computer.

Corporation, British B.

148

The Volcano Adventure Guide  

NASA Astrophysics Data System (ADS)

This guide contains vital information for anyone wishing to visit, explore, and photograph active volcanoes safely and enjoyably. Following an introduction that discusses eruption styles of different types of volcanoes and how to prepare for an exploratory trip that avoids volcanic dangers, the book presents guidelines to visiting 42 different volcanoes around the world. It is filled with practical information that includes tour itineraries, maps, transportation details, and warnings of possible non-volcanic dangers. Three appendices direct the reader to a wealth of further volcano resources in a volume that will fascinate amateur enthusiasts and professional volcanologists alike. Rosaly Lopes is a planetary geology and volcanology specialist at the NASA Jet Propulsion Laboratory in California. In addition to her curatorial and research work, she has lectured extensively in England and Brazil and written numerous popular science articles. She received a Latinas in Science Award from the Comision Feminil Mexicana Nacional in 1991 and since 1992, has been a co-organizer of the United Nations/European Space Agency/The Planetary Society yearly conferences on Basic Science for the Benefit of Developing Countries.

Lopes, Rosaly

2005-02-01

149

Digital Geologic Map Database of Medicine Lake Volcano, Northern California  

NASA Astrophysics Data System (ADS)

Medicine Lake volcano, located in the southern Cascades ~55 km east-northeast of Mount Shasta, is a large rear-arc, shield-shaped volcano with an eruptive history spanning nearly 500 k.y. Geologic mapping of Medicine Lake volcano has been digitally compiled as a spatial database in ArcGIS. Within the database, coverage feature classes have been created representing geologic lines (contacts, faults, lava tubes, etc.), geologic unit polygons, and volcanic vent location points. The database can be queried to determine the spatial distributions of different rock types, geologic units, and other geologic and geomorphic features. These data, in turn, can be used to better understand the evolution, growth, and potential hazards of this large, rear-arc Cascades volcano. Queries of the database reveal that the total area covered by lavas of Medicine Lake volcano, which range in composition from basalt through rhyolite, is about 2,200 km2, encompassing all or parts of 27 U.S. Geological Survey 1:24,000-scale topographic quadrangles. The maximum extent of these lavas is about 80 km north-south by 45 km east-west. Occupying the center of Medicine Lake volcano is a 7 km by 12 km summit caldera in which nestles its namesake, Medicine Lake. The flanks of the volcano, which are dotted with cinder cones, slope gently upward to the caldera rim, which reaches an elevation of nearly 2,440 m. Approximately 250 geologic units have been mapped, only half a dozen of which are thin surficial units such as alluvium. These volcanic units mostly represent eruptive events, each commonly including a vent (dome, cinder cone, spatter cone, etc.) and its associated lava flow. Some cinder cones have not been matched to lava flows, as the corresponding flows are probably buried, and some flows cannot be correlated with vents. The largest individual units on the map are all basaltic in composition, including the late Pleistocene basalt of Yellowjacket Butte (296 km2 exposed), the largest unit on the map, whose area is partly covered by a late Holocene andesite flow. Silicic lava flows are mostly confined to the main edifice of the volcano, with the youngest rhyolite flows found in and near the summit caldera, including the rhyolitic Little Glass Mountain (~1,000 yr B.P.) and Glass Mountain (~950 yr B.P.) flows, which are the youngest eruptions at Medicine Lake volcano. In postglacial time, 17 eruptions have added approximately 7.5 km3 to the volcano’s total estimated volume of 600 km3, which may be the largest by volume among Cascade Range volcanoes. The volcano has erupted nine times in the past 5,200 years, a rate more frequent than has been documented at all other Cascade volcanoes except Mount St. Helens.

Ramsey, D. W.; Donnelly-Nolan, J. M.; Felger, T. J.

2010-12-01

150

Volcano Inflation prior to Gas Explosions at Semeru Volcano, Indonesia  

NASA Astrophysics Data System (ADS)

Semeru volcano in east Java, Indonesia, is well known to exhibit small vulcanian eruptions at the summit crater. Such eruptive activity stopped on April 2009, but volcanic earthquakes started to occur in August and a lava dome was found in the summit crater on November. Since then, lava sometimes flows downward on the slope and small explosions emitting steams from active crater frequently occur every a few to a few tens of minutes. Since the explosions repeatedly occur with short intervals and the active crater is located close to the summit with an altitude of 3676m, the explosions are considered to originate from the gas (steams) from magma itself in the conduit and not to be caused by interactions of magma with the underground water. We installed a tiltmeter at the summit on March 2010 to study the volcanic eruption mechanisms. The tiltmeter (Pinnacle hybrid type, accuracy of measurement is 1 nrad ) was set at a depth of about 1 m around the summit about 500 m north from the active crater. The data stored every 1 s in the internal memory was uploaded every 6 hours by a small data logger with GPS time correction function. More than one thousand gas explosion events were observed for about 2 weeks. We analyze the tilt records as well as seismic signals recorded at stations of CVGHM, Indonesia. The tilt records clearly show uplift of the summit about 20 to 30 seconds before each explosion. Uplifts before large explosions reach to about 20 - 30 n rad, which is almost equivalent to the volume increase of about 100 m^3 beneath the crater. To examine the eruption magnitude dependence on the uplift, we classify the eruptions into five groups based on the amplitudes of seismograms associated with explosions. We stack the tilt records for these groups to reduce noises in the signals and to get general characteristics of the volcano inflations. The results show that the amplitudes of uplifts are almost proportional to the amplitudes of explosion earthquakes while the preceding time of uplift is almost constant (20 s - 30 s). This implies that the inflation rate controls the magnitude of gas explosions. The observed preceding time of inflation prior to gas explosions are much shorter than those for the inflations before magmatic explosions (Nishi et al., 2007; Iguchi et al., 2008), which suggests that the pressurization processes in shallow conduit for gas explosions are different from that for explosions emitting ashes.

Nishimura, T.; Iguchi, M.; Kawaguchi, R.; Surono, S.; Hendrasto, M.; Rosadi, U.

2010-12-01

151

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

152

Multiparameter Volcano Surveillance of Villarrica Volcano (South-Central Chile)  

NASA Astrophysics Data System (ADS)

Villarrica is one of the most active volcanoes in Chile and one of the few in the world known to have an active lava lake within its crater. This snow-covered volcano generates frequent strombolian eruptions and lava flows and, at times, the melting of snow can cause massive lahars. Besides this, continuous degassing and high-level seismicity are the most common types of activity recorded at the volcano. In order to investigate the mechanisms driving the persistent degassing and seismic activity at the volcano, we use a multiparameter approach based on the combined study of high time-resolved gas and seismic data. These data are respectively acquired by means of 3 stationary NOVAC-type scanning Mini-DOAS and 7 additional seismometers (short period and broad bands), installed at the volcano since March 2009, that complement the existing OVDAS (Observatorio Volcanológico de los Andes del Sur) volcano monitoring network. On the basis of the combination of gas and seismological measurements we aim at gaining insight into volcano-magmatic processes, and factors playing a role on onset of volcanic unrest and eruptive activity. Since the gas monitoring network has been installed at the volcano a correlation between SO2 emissions and seismic activity (LP events) has been recognized. A possible role played by regional tectonics on detected changes in volcano degassing and seismicity, and consequently on the volcanic activity, is also investigated.

Garofalo, Kristin; Peña, Paola; Dzierma, Yvonne; Hansteen, Thor; Rabbel, Wolfgang; Gil, Fernando

2010-05-01

153

Earthquakes and Volcanoes  

NSDL National Science Digital Library

This unit provides an introduction for younger students on earthquakes, volcanoes, and how they are related. Topics include evidence of continental drift, types of plate boundaries, types of seismic waves, and how to calculate the distance to the epicenter of an earthquake. There is also information on how earthquake magnitude and intensity are measured, and how seismic waves can reveal the Earth's internal structure. A vocabulary list and downloadable, printable student worksheets are provided.

Medina, Philip

2011-06-27

154

Yellowstone Volcano Observatory  

NSDL National Science Digital Library

This is the homepage of the United States Geological Survey's (USGS) Yellowstone Volcano Observatory. It features news articles, monitoring information, status reports and information releases, and information on the volcanic history of the Yellowstone Plateau Volcanic Field. Users can access monthly updates with alert levels and aviation warning codes and real-time data on ground deformation, earthquakes, and hydrology. There is also a list of online products and publications, and an image gallery.

2012-08-23

155

Volcanoes and Climate Change  

NSDL National Science Digital Library

Major volcanic eruptions alter the Earth's radiative balance, as volcanic ash and gas clouds absorb terrestrial radiation and scatter a significant amount of the incoming solar radiation, an effect known as "radiative forcing" that can last from two to three years following a volcanic eruption. This results in reduced temperatures in the troposphere, and changes in atmospheric circulation patterns. This site uses text, photographs, and links to related sites to describe volcano-induced climate change.

156

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.

157

Volcanoes generate devastating waves  

SciTech Connect

Although volcanic eruptions can cause many frightening phenomena, it is often the power of the sea that causes many volcano-related deaths. This destruction comes from tsunamis (huge volcano-generated waves). Roughly one-fourth of the deaths occurring during volcanic eruptions have been the result of tsunamis. Moreover, a tsunami can transmit the volcano's energy to areas well outside the reach of the eruption itself. Some historic records are reviewed. Refined historical data are increasingly useful in predicting future events. The U.S. National Geophysical Data Center/World Data Center A for Solid Earth Geophysics has developed data bases to further tsunami research. These sets of data include marigrams (tide gage records), a wave-damage slide set, digital source data, descriptive material, and a tsunami wall map. A digital file contains information on methods of tsunami generation, location, and magnitude of generating earthquakes, tsunami size, event validity, and references. The data can be used to describe areas mot likely to generate tsunamis and the locations along shores that experience amplified effects from tsunamis.

Lockridge, P. (National Geophysical Data Center, Boulder, CO (USA))

1988-01-01

158

Pairing the Volcano  

E-print Network

Isogeny volcanoes are graphs whose vertices are elliptic curves and whose edges are $\\ell$-isogenies. Algorithms allowing to travel on these graphs were developed by Kohel in his thesis (1996) and later on, by Fouquet and Morain (2001). However, up to now, no method was known, to predict, before taking a step on the volcano, the direction of this step. Hence, in Kohel's and Fouquet-Morain algorithms, many steps are taken before choosing the right direction. In particular, ascending or horizontal isogenies are usually found using a trial-and-error approach. In this paper, we propose an alternative method that efficiently finds all points $P$ of order $\\ell$ such that the subgroup generated by $P$ is the kernel of an horizontal or an ascending isogeny. In many cases, our method is faster than previous methods. This is an extended version of a paper published in the proceedings of ANTS 2010. In addition, we treat the case of 2-isogeny volcanoes and we derive from the group structure of the curve and the pairing ...

Ionica, Sorina

2011-01-01

159

Sulfur volcanoes on Io?  

NASA Technical Reports Server (NTRS)

The unusual rheological properties of sulfur are discussed in order to determine the distinctive volcanic flow morphologies which indicate the presence of sulfur volcanoes on the Saturnian satellite Io. An analysis of high resolution Voyager imagery reveals three features which are considered to be possible sulfur volcanoes: Atar Patera, Daedalus Patera, and Kibero Patera. All three features are distinguished by circular-to-oval central masses surrounded by irregular widespread flows. The central zones of the features are interpreted to be domes formed of high temperature sulfur. To confirm the interpretations of the satellite data, molten sulfur was extruded in the laboratory at a temperature of 210 C on a flat surface sloping 0.5 deg to the left. At this temperature, the sulfur formed a viscous domelike mass over the event. As parts of the mass cooled to 170 C the viscosity decreased to a runny stage, forming breakout flows. It is concluded that a case can be made for sulfur volcanoes on Io sufficient to warrant further study, and it is recommended that the upcoming Galileo mission examine these phenomena.

Greeley, R.; Fink, J. H.

1984-01-01

160

Cascades Volcano Observatory: Educational Outreach  

NSDL National Science Digital Library

Located in Vancouver, Washington, the Cascades Volcano Observatory monitors and reports on volcanic activity in the area and around the country. The related Educational Outreach Web site is provided by the US Geological Survey. Visitors will find information on current volcanic activity and news, what to do if a volcano erupts, volcano terminology, America's volcanic history, how the Cascade range got their names, volcano questions and answers, and much more. Other features of the site include activities and fun "stuff," posters and videos, and many outside links.

161

Database for the Geologic Map of the Summit Region of Kilauea Volcano, Hawaii  

USGS Publications Warehouse

INTRODUCTION The area covered by this map includes parts of four U.S. Geological Survey (USGS) 7.5' topographic quadrangles (Kilauea Crater, Volcano, Ka`u Desert, and Makaopuhi). It encompasses the summit, upper rift zones, and Koa`e Fault System of Kilauea Volcano and a part of the adjacent, southeast flank of Mauna Loa Volcano. The map is dominated by products of eruptions from Kilauea Volcano, the southernmost of the five volcanoes on the Island of Hawai`i and one of the world's most active volcanoes. At its summit (1,243 m) is Kilauea Crater, a 3 km-by-5 km collapse caldera that formed, possibly over several centuries, between about 200 and 500 years ago. Radiating away from the summit caldera are two linear zones of intrusion and eruption, the east and the southwest rift zones. Repeated subaerial eruptions from the summit and rift zones have built a gently sloping, elongate shield volcano covering approximately 1,500 km2. Much of the volcano lies under water: the east rift zone extends 110 km from the summit to a depth of more than 5,000 m below sea level; whereas, the southwest rift zone has a more limited submarine continuation. South of the summit caldera, mostly north-facing normal faults and open fractures of the Koa`e Fault System extend between the two rift zones. The Koa`e Fault System is interpreted as a tear-away structure that accommodates southward movement of Kilauea's flank in response to distension of the volcano perpendicular to the rift zones. This digital release contains all the information used to produce the geologic map published as USGS Geologic Investigations Series I-2759 (Neal and Lockwood, 2003). The main component of this digital release is a geologic map database prepared using ArcInfo GIS. This release also contains printable files for the geologic map and accompanying descriptive pamphlet from I-2759.

Dutton, Dillon R.; Ramsey, David W.; Bruggman, Peggy E.; Felger, Tracey J.; Lougee, Ellen; Margriter, Sandy; Showalter, Patrick; Neal, Christina A.; Lockwood, John P.

2007-01-01

162

Drilling, Construction, Water-Level, and Water-Quality Information for the Kualapuu Deep Monitor Well, 4-0800-01, Molokai, Hawaii  

USGS Publications Warehouse

A monitor well was completed in January 2001 by the U.S. Geological Survey in the Kualapuu area of central Molokai, Hawaii that allows for monitoring the thicknesses of the freshwater body and the upper part of the underlying freshwater-saltwater transition zone. The well was drilled in cooperation with the State Department of Hawaiian Home Lands and the Maui County Department of Water Supply, and is located near the area that supplies much of the drinking water on Molokai. The well is at a ground-surface elevation of about 982 feet and penetrated a 1,585-foot section of soil and volcanic rock to a depth of 603 feet below sea level. Prior to casing, a cave-in caused the bottom 55 feet of the well to be filled with rocks originating from a zone above. Thus, the final well depth reported by the driller was 1,530 feet. Measured water levels in the well during the period from February 1 to July 13, 2001 range from 8.68 to 9.05 feet above sea level. The most recent available water-conductivity profile from July 13, 2001 indicates that the lowest salinity water in the well is in the upper zone from the water table to a depth of about 220 feet below sea level. Below this upper zone, water salinity increases with depth. The water-temperature profile from July 13, 2001 indicates that the lowest temperature water (20.2 degrees Celsius) in the well is located in the upper zone from the water table to a depth of about 200 feet below sea level. Water temperature increases to 24.5 degrees Celsius near the bottom of the measured profile, 507 feet below sea level.

Oki, Delwyn S.; Bauer, Glenn R.

2001-01-01

163

The composition and sources of magmas of Changbaishan Tianchi volcano (China-North Korea)  

NASA Astrophysics Data System (ADS)

The Changbaishan Tianchi volcano is the greatest stratovolcano within the bounds of the Late Cenozoic intraplate volcanic province of East Asia. Changbaishan Tianchi volcanic cone consists mostly of trachytes and pantellerites. It was found that the lavas composing the shield platform of Changbaishan Tianchi volcano are weakly differentiated basic rocks whose geochemical characteristics are generally similar. All the alkaline salic rocks composing the cone of the volcano are characterized by conformable normalized trace element patterns. The concentrations of rare-earth elements in these rocks are high and amount up to 1000 ppm. The character of the distribution of trace elements in the basic rocks of Changbaishan Tianchi volcano is close to that in the OIB-type basalts. Within the series from basalts to pantellerites, the rocks are enriched in REE and zirconium, but depleted in barium, strontium, and europium. According to the obtained geochemical data, it was shown that the rock series of Changbaishan Tianchi volcano, varying from basalts to trachytes and pantellerites comprises compositions geochemically interrelated by the processes of crystal fractionation. The parental magma for the rocks of the volcano was derived from plume sources of the same type as those of OIB and sources of the Late Cenozoic intraplate province of East Asia.

Andreeva, O. A.; Yarmolyuk, V. V.; Andreeva, I. A.; Ji, J. Q.; Li, W. R.

2014-05-01

164

Remote sensing of Italian volcanos  

NASA Technical Reports Server (NTRS)

The results of a July 1986 remote sensing campaign of Italian volcanoes are reviewed. The equipment and techniques used to acquire the data are described and the results obtained for Campi Flegrei and Mount Etna are reviewed and evaluated for their usefulness for the study of active and recently active volcanoes.

Bianchi, R.; Casacchia, R.; Coradini, A.; Duncan, A. M.; Guest, J. E.; Kahle, A.; Lanciano, P.; Pieri, D. C.; Poscolieri, M.

1990-01-01

165

Regional controls on volcano seismicity along the Aleutian arc  

NASA Astrophysics Data System (ADS)

identify patterns in volcano seismicity along the Aleutian arc using nearly 10 years of seismic data recorded at 46 volcanoes. The volcanoes in the central portion of the arc—those located from Aniakchak to Okmok—are associated with significantly more seismicity at depths below 15 km. We also examine the median weight percent SiO2 compositions of the seismically monitored volcanoes by compiling published geochemical data. We find that the transition between felsic volcanism in the east to more mafic volcanism in the west occurs in the same region where the depth distribution of volcanic earthquakes changes. Since deep volcanic earthquakes are often thought to be generated by the ascent of magma through the deep crust (i.e., depths > 15 km), our results suggest that magma ascent is more prolific in the central part of the arc compared to the western and eastern regions. This observation is in agreement with the location of the largest and most historically active volcanoes in the Aleutian arc, which are found in same region that generates abundant deep volcano seismicity. We propose two models to explain these apparent variations in magmatic flux: (1) a stress-based model, in which subduction obliquity and the collision of the Yakutat block affect the stress regime in the upper plate, inhibiting the rise of magma in eastern and western regions of the arc and (2) a melt-based model, where more magma is generated in the central region of the arc through increased H2O in the downgoing slab via water-laden sediments and subducting fracture zones.

Buurman, Helena; Nye, Christopher J.; West, Michael E.; Cameron, Cheryl

2014-04-01

166

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

167

Migration of a Caldera Eruptive Center, Newberry Volcano, Oregon  

NASA Astrophysics Data System (ADS)

Newberry Volcano is located in Deschutes County, Oregon about 35 km south of the city of Bend. It is a bi-modal Quaternary volcano and is one of the largest volcanos in the Cascade Range. The volcano is positioned near the junction of three geologic provinces: the Cascade Range to the west, the High Lava Plains portion of the Basin and Range to the south and east, and the Blue Mountains to the northeast. Newberry Volcano has been active for the past 600,000 years and has had at least two caldera-forming eruptions. The most recent major caldera-related eruptions, resulting in significant silicic ash and pyroclastic deposits, occurred approximately 300,000 and 80,000 years ago. A large-volume basaltic eruption that occurred about 72,000 years ago is represented by the widespread Bend Lavas which extend approximately 70 km to the north of the central caldera. About 6,000 years ago numerous basaltic eruptions occurred along a northwest fracture zone. The most recent eruption, a silicic obsidian flow and associated pumice fall that vented from within the caldera, has been dated at 1,300 ybp. Newberry has been the site of multiple rounds of geothermal exploration over the past 30 years. Geophysical data including gravity, resistivity, and seismic studies collected in the 1980s in early exploration of the volcano have identified anomalous features beneath the west flank of the volcano. Four deep (<2.8km) wells have been drilled on the northern half of the west flank; all of the wells have encountered temperatures in excess of 300°C, however, three of the wells have low permeability and unconnected fractures. The fourth well showed evidence of a hydrothermal system, but the well caved before a flow test could be completed. Recent geophysical analysis coupled with well geochemistry has identified evidence for older nested caldera related eruptive events buried under younger west flank lavas. A strong gravity gradient, a sharp MT boundary, and arcuate surface features from LIDAR coupled with 300-1200m offsets in units between wells is evidence that the caldera has migrated to the east over time. Buried silicic lavas are observed on the west flank; these lavas include McKay Butte, West Flank Dome, and Southwest Flank Dome. If this conclusion is correct, buried volcanic features similar to those observed in the present caldera could be expected under portions of the west flank, now buried by subsequent volcanic units. Hydrothermal systems, as exposed by erosion in older caldera mineral deposits, may be found associated with these features at Newberry.

Frone, Z.; Waibel, A.; Blackwell, D. D.

2012-12-01

168

Anfrageoptimierung in Volcano und Bjorn Scheuermann  

E-print Network

Anfrageoptimierung in Volcano und Cascades Bj¨orn Scheuermann Vortrag im Rahmen des Seminars Datenbanken, WS 03/04 Anfrageoptimierung in Volcano und Cascades ­ p.1/23 #12;Zielsetzung Entwicklung von ¨angig von konkretem Datenmodell Anfrageoptimierung in Volcano und Cascades ­ p.2/23 #12;Volcano

Mannheim, Universität

169

Explosive Eruptions of Kamchatkan Volcanoes in 2012 and Danger to Aviation  

NASA Astrophysics Data System (ADS)

Strong explosive eruption of volcanoes is the most dangerous for aircraft because in a few hours or days in the atmosphere and the stratosphere can produce about several cubic kilometers of volcanic ash and aerosols. Ash plumes and the clouds, depending on the power of the eruption, the strength and wind speed, can travel thousands of kilometers from the volcano for several days, remaining hazardous to aircraft, as the melting temperature of small particles of ash below the operating temperature of jet engines. There are 30 active volcanoes in the Kamchatka and 6 active volcanoes in the Northern Kuriles, and 4 of them continuously active. In 2012 seven strong explosive eruptions of the Kamchatkan and the Northern Kuriles volcanoes Sheveluch, Bezymianny, Kizimen, Tolbachik, Klyuchevskoy, and Karymsky took place. In addition, higher fumarolic activity of Gorely volcano was observed. The eruptive activity of Sheveluch Volcano began since 1980 (growth of the lava dome) and is continuing at present. Strong explosive events of the volcano occurred in 2012: on January 22-23; on March 16-17; March 25-30 - June 03; and on September 18: ash plumes rose up to 10 km a.s.l. and extended about 200-2000 km to the different directions of the volcano. The eruptive activity of Bezymianny volcano began since 1955, and is continuing at present as growth of the lava dome. Two paroxysmal explosive phases of the eruption occurred on March 08 and September 01: ash plumes rose up to 8-12 km a.s.l. and extended about 1500 km to the east-north-east of the volcano. Eruption of Kizimen volcano began on December 09, 2010, and continues. Strong explosive eruption began in mid-December, 2010, - ash plumes rose up to 10 km a.s.l. and extended > 800 km from the volcano. There are several stages of the eruption: explosive (from 09 December 2010 to mid-January 2011); explosive-effusive (mid-January to mid-June 2011); effusive (mid-January 2011 to September 2012). Extrusive-effusive phase of eruption of the volcano continues at present. Strombolian explosive eruption of Klyuchevskoy volcano began on October 14, 2012, and continues at present. Tolbachik. Explosive-effusive fissure eruption at Tolbachinsky Dol began on November 27, 2012, and continues. Four cinder cones grew at the fissure; lava flows extended about 20 km of vents. Karymsky volcano has been in a state of explosive eruption since 1996. The moderate explosive eruption continued during all 2012. The eruptive activity of Alaid volcano began on October 06 and probably finished in mid- December, 2012. Gas-steam plumes containing small amount of ash rose up to 3 km a.s.l., a small cinder cone grew into summit volcanic crater. Satellite data showed a weak thermal anomaly over the volcano on October-November. Strong fumarolic activity of Gorely volcano began to noting from June 2010 and continues at present. A new vent on the wall of the volcanic active crater was discovered on June 17, 2010. The crater lake disappeared to Summer 2012.

Girina, Olga; Manevich, Alexander; Melnikov, Dmitry; Nuzhdaev, Anton; Demyanchuk, Yury; Petrova, Elena

2013-04-01

170

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

171

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

172

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

173

Sulfur Volcanoes on Io?  

NASA Technical Reports Server (NTRS)

The unusual rheological properties of molten sulfur, in which viscosity decreases approximately four orders of magnitude as it cools from 170 to 120 C, may result in distinctive volcanic flow morphologies that allow sulfur flows and volcanoes to be identified on Io. Search of high resolution Voyager images reveals three features--Atar Patera, Daedalus Patera, and Kibero Patera--considered to be possible sulfur volcanoes based on their morphology. All three average 250 km in diameter and are distinguished by circular-to-oval central masses surrounded by irregular, widespread flows. Geometric relations indicate that the flows were emplaced after the central zone and appear to have emanated from their margins. The central zones are interpreted to be domes representing the high temperature stage of sulfur formed initially upon eruption. Rapid quenching formed a crust which preserved this phase of the emplacement. Upon cooling to 170 C, the sulfur reached a low viscosity runny stage and was released as the thin, widespread flows.

Greeley, R.; Fink, J.

1985-01-01

174

A Preliminary Study of Hazus-MH Volcano for Korea  

NASA Astrophysics Data System (ADS)

This presentation will introduce our design to develop a volcano risk modeling capacity within the Hazus-MH loss estimation framework. In particular, we will present how to build fragility curves within the Hazus-MH framework for loss estimation from volcanoes. This capability is designed to analyze the risk from volcanic hazards in Korea. The Korean peninsula has Mt. Baekdu in North Korea, which will soon enter an active phase, according to some volcanologists. The anticipated eruption will be explosive given the viscous and grassy silica-rich magma, and is expected to be one of the largest in recent millennia. We aim to assess the impacts of this eruption, in particular to South Korea. There are several types of hazards related to volcanic eruption, including ash, pyroclastic flows, volcanic floods and earthquakes. However, our initial efforts focus on modeling losses from volcanic ash. The proposed volcanic ash model is anticipated to be used to estimate losses caused by yellow dust in East Asia as well. Also, many countries, which are exposed to potentially dangerous volcanoes, can benefit from the proposed Hazus-MH Volcano risk model. Acknowledgement: this research was supported by a grant [NEMA-BAEKDUSAN-2012-1-3] from the Volcanic Disaster Preparedness Research Center sponsored by National Emergency Management Agency of Korea. We would like to thank Federal Emergency Management Agency which develops Hazus-MH and allows the international use of Hazus-MH.

Yu, S.; An, H.; Oh, J.

2013-12-01

175

Volcano Hazards at Fuego and Acatenango, GuatemalaVolcano Hazards at Fuego and Acatenango, GuatemalaVolcano Hazards at Fuego and Acatenango, GuatemalaVolcano Hazards at Fuego and Acatenango, GuatemalaVolcano Hazards at Fuego and Acatenango, Guatemala 1111  

E-print Network

Volcano Hazards at Fuego and Acatenango, GuatemalaVolcano Hazards at Fuego and Acatenango, GuatemalaVolcano Hazards at Fuego and Acatenango, GuatemalaVolcano Hazards at Fuego and Acatenango, GuatemalaVolcano Hazards at Fuego and Acatenango, Guatemala 11111 Open-File Report 01­431Open-File Report 01

Rose, William I.

176

Volcanic Structure of the Basaltic Shield Volcano of Socorro Island, Mathematician Ridge, Pacific Plate  

Microsoft Academic Search

Socorro Island is a pantellerite and perialkaline shield volcano built at the northern segment of the Mathematician ridge in the Pacific plate. Active spreading along the ridge terminated following major plate boundary re-organization and ridge jumping eastwards to the East Pacific Rise. Cessation of spreading and ridge jumping are recorded in the marine magnetic anomaly pattern that preserve a record

M. Escorza-Reyes; J. A. Pavon-Moreno; L. Perez-Cruz; J. U. Fucugauchi

2009-01-01

177

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

178

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

179

Volcano-tectonic activity along structures of the unstable NE flank of Mt. Etna (Italy) and their possible origin  

Microsoft Academic Search

We describe the prehistoric–historic activity of the main and minor volcano-tectonic structures of the northeastern flank of Mt. Etna, giving new data which provide a clearer view of how destabilized volcanoes react to magma pressure and gravity forces. Data are mostly based on new lithostratigraphic surveys and on offset measurements of late Pleistocene–Holocene deposits and historic man-made features. The North-East

Alessandro Tibaldi; Gianluca Groppelli

2002-01-01

180

Mount Rainier active cascade volcano  

NASA Technical Reports Server (NTRS)

Mount Rainier is one of about two dozen active or recently active volcanoes in the Cascade Range, an arc of volcanoes in the northwestern United States and Canada. The volcano is located about 35 kilometers southeast of the Seattle-Tacoma metropolitan area, which has a population of more than 2.5 million. This metropolitan area is the high technology industrial center of the Pacific Northwest and one of the commercial aircraft manufacturing centers of the United States. The rivers draining the volcano empty into Puget Sound, which has two major shipping ports, and into the Columbia River, a major shipping lane and home to approximately a million people in southwestern Washington and northwestern Oregon. Mount Rainier is an active volcano. It last erupted approximately 150 years ago, and numerous large floods and debris flows have been generated on its slopes during this century. More than 100,000 people live on the extensive mudflow deposits that have filled the rivers and valleys draining the volcano during the past 10,000 years. A major volcanic eruption or debris flow could kill thousands of residents and cripple the economy of the Pacific Northwest. Despite the potential for such danger, Mount Rainier has received little study. Most of the geologic work on Mount Rainier was done more than two decades ago. Fundamental topics such as the development, history, and stability of the volcano are poorly understood.

1994-01-01

181

Moloka'i: Fishponds.  

ERIC Educational Resources Information Center

Designed to help teachers implement marine education in their classrooms, this module provides information regarding a vanishing Hawaiian resource, fishponds. Due to the impact of present day human activities on shoreline areas, the size and number of fishponds have been greatly reduced; therefore, this module focuses on fishponds as a resource…

Hawaii State Dept. of Education, Honolulu. Office of Instructional Services.

182

Development of volcano monitoring technique using repeating earthquakes observed by the Volcano Observation Network of NIED  

NASA Astrophysics Data System (ADS)

After the Grate East Japan Earthquake (M9.0) on March 11, 2011, the M6.4 earthquake occurred beneath Mt. Fuji on March 15, 2011. Although the hypocenter seemed to be very close to an assumed magma chamber of Fuji volcano, no anomalies in volcanic activity have been observed until August 2012. As an example, after the M6.1 earthquake occurred in 1998 at southwest of Iwate volcano, a change of seismic velocity structure (e.g. Nishimura et al., 2000) was observed as well as active seismicity and crustal deformation. It had affected waveforms of repeating earthquakes occurring at a plate subduction zone, that is, the waveform similarities were reduced just after the earthquake due to upwelling of magma. In this study, first we analyzed for Mt. Fuji where such changes are expected by the occurrence of the earthquake to try to develop a tool for monitoring active volcanoes using the Volcano Observation network (V-net) data. We used seismic waveform data of repeating earthquakes observed by short period seismometers of V-net and the High Sensitivity Seismograph Network Japan (Hi-net) stations near Fuji volcano after 2007. The seismic data were recorded with a sampling rate of 100 Hz, and we applied 4-8 Hz band pass filter to reduce noise. The repeating earthquakes occurred at the plate subduction zone and their catalog is compiled by Hi-net data (Kimura et al., 2006). We extracted repeating earthquake groups that include earthquakes before and after the M6.4 earthquake on March 15, 2011. A waveform of the first event of the group and waveforms of the other events are compared and calculated cross-correlation coefficients. We adjusted P wave arrivals of each event and calculate the coefficients and lag times of the latter part of the seismic waves with the time window of 1.25 s. We searched the best fit maximizing the cross-correlation coefficients with 0.1 s shift time at each time window. As a result we found three remarkable points at this time. [1] Comparing lag times of (a) a pair that both earthquakes are before March 15, 2011, and (b) a pair that before and after March 15, 2011, (b) has bigger time delay at several stations than (a). [2] The delays for several pairs of earthquakes are obtained at NIED V-net stations established just around Mt. Fuji. On the other hand Hi-net stations which are far from the edifice have the smaller delays. [3] Some stations, FJNV, FJHV, FJYV, located on the west part of the edifice have bigger delays than the others. An obvious delay comes out at the S wave coda part, and does not in the P wave coda part or S wave. As one of the possibilities to create the delays, it is considered that, for example, seismic velocity structure beneath Mt. Fuji had changed since the M6.4 earthquake. In the case of the unrest of Iwate volcano in 1998, waves passing through the magma chamber had got delayed (e.g. Yamawaki et al., 2004). It is important to install borehole type seismometers just around a volcano, like V-net stations, to get high quality seismograms for precise study like this analysis and to get some changes of volcano activities.

Kohno, Y.; Ueda, H.; Kimura, H.; Nagai, M.; Miyagi, Y.; Fujita, E.; Kozono, T.; Tanada, T.

2012-12-01

183

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

USGS Publications Warehouse

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 target volume to a dense array of 140 seismographs provides 1- to 2-km resolution in the upper 5 to 7 km of the crust beneath the volcano. The experiment tests the hypothesis that Cascade Range volcanoes of this type are underlain only by small silicic magma chambers. We image a low-velocity low-Q region not larger than a few tens of cubic kilometers in volume beneath the summit caldera, supporting the hypothesis. A shallower high-velocity high-density feature, previously known to be present, is imaged for the first time in full plan view; it is east-west elongate, paralleling a topographic lineament between Medicine Lake volcano and Mount Shasta. Differences between this high-velocity feature and the equivalent feature at Newberry volcano, a volcano in central regon resembling Medicine Lake volcano, may partly explain the scarcity of surface hydrothermal features at Medicine Lake volcano. A major low-velocity low-Q feature beneath the southeast flank of the volcano, in an area with no Holocene vents, is interpreted as tephra, flows, and sediments from the volcano deeply ponded on the downthrown side of the Gillem fault. A high-Q normal-velocity feature beneath the north rim of the summit caldera may be a small, possibly hot, subsolidus intrusion. A high-velocity low-Q region beneath the eastern caldera may be an area of boiling water between the magma chamber and the ponded east flank material. -from Authors

Evans, J. R.; Zucca, J. J.

1988-01-01

184

Counterfactual Volcano Hazard Analysis  

NASA Astrophysics Data System (ADS)

The historical database of past disasters is a cornerstone of catastrophe risk assessment. Whereas disasters are fortunately comparatively rare, near-misses are quite common for both natural and man-made hazards. The word disaster originally means 'an unfavourable aspect of a star'. Except for astrologists, disasters are no longer perceived fatalistically as pre-determined. Nevertheless, to this day, historical disasters are treated statistically as fixed events, although in reality there is a large luck element involved in converting a near-miss crisis situation into a disaster statistic. It is possible to conceive a stochastic simulation of the past to explore the implications of this chance factor. Counterfactual history is the exercise of hypothesizing alternative paths of history from what actually happened. Exploring history from a counterfactual perspective is instructive for a variety of reasons. First, it is easy to be fooled by randomness and see regularity in event patterns which are illusory. The past is just one realization of a variety of possible evolutions of history, which may be analyzed through a stochastic simulation of an array of counterfactual scenarios. In any hazard context, there is a random component equivalent to dice being rolled to decide whether a near-miss becomes an actual disaster. The fact that there may be no observed disaster over a period of time may belie the occurrence of numerous near-misses. This may be illustrated using the simple dice paradigm. Suppose a dice is rolled every month for a year, and an event is recorded if a six is thrown. There is still an 11% chance of no events occurring during the year. A variety of perils may be used to illustrate the use of near-miss information within a counterfactual disaster analysis. In the domain of natural hazards, near-misses are a notable feature of the threat landscape. Storm surges are an obvious example. Sea defences may protect against most meteorological scenarios. However, if a major storm surge happens to arrive at a high astronomical tide, sea walls may be overtopped and flooding may ensue. In the domain of geological hazards, periods of volcanic unrest may generate precursory signals suggestive of imminent volcanic danger, but without leading to an actual eruption. Near-miss unrest periods provide vital evidence for assessing the dynamics of volcanoes close to eruption. Where the volcano catalogue has been diligently revised to include the maximum amount of information on the phenomenology of unrest periods, dynamic modelling and hazard assessment may be significantly refined. This is illustrated with some topical volcano hazard examples, including Montserrat and Santorini.

Woo, Gordon

2013-04-01

185

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

186

Mt. Erebus Volcano Observatory  

NSDL National Science Digital Library

The Mt. Erebus Volcano Observatory website offers a plethora of information about the geology, geochemistry, and geophysics research at Mt. Erebus in Antarctica. The site addresses the evolution of Erebus, lava and gas chemistry, seismology, and much more. Students can discover how Mount Erebus's environment changes by examining two day, 30 day, and 365 day records. The Photo Gallery is packed with incredible images of the landscape, geologic features, and the scientific monitoring. Users can view live footage as well as movies of volcanic eruptions and the inner and outer crater. Because the materials are not particularly technical, users can easily learn about volcanology and, more specifically, about scientists' efforts to better understand Mt. Erebus.

187

Monitoring change in volcanoes  

NASA Astrophysics Data System (ADS)

Because of their heterogeneous structure, volcanoes strongly scatter elastic waves. We show examples of repeated earthquakes at Mount St. Helens. The repeatability of recorded waveforms is spectacular, but as time progresses the waveforms do change. We have analyzed the nature of the changes in the observed waveforms. For example, the change in the waveforms does not increase with propagation time, which argues against a change in seismic velocity. We conclude that observed changes are likely to be due to a migration of the seismic source with time.Theory exists that quantifies changes in multiply scattered waves to changes in the location of the seismic source. The inferred movement of the seismic zone is of the order of about 100 meters per day. This is much more than one would expect for the movement of a plug in the magma chamber, and a adjustment of the stress field is the most likely cause of the inferred migration of the seismic region.

Snieder, R.; Prejean, S.; Johnson, J.

2008-12-01

188

Eye in the Sky: Volcanoes  

NSDL National Science Digital Library

This resource presents a brief overview of volcanoes, including the science, phenomena, and effects of volcanic eruptions. Included are video clips and an animation of the Mount Saint Helens eruption.

189

The Ice Piston, Redoubt Volcano  

USGS Multimedia Gallery

The Ice Piston with Ash, Redoubt Volcano, Alaska. This photo was taken on March 21, 2009, the day before Redoubt first erupted. The glacier that filled the crater was collapsing because of the increase in ground temperature underneath....

2009-12-08

190

Alaska Volcanoes Guidebook for Teachers.  

National Technical Information Service (NTIS)

Alaska's volcanoes, like its abundant glaciers, charismatic wildlife, and wild expanses inspire and ignite scientific curiosity and generate an ever-growing source of questions for students in Alaska and throughout the world. Alaska is home to more than 1...

J. N. Adleman

2010-01-01

191

Lung problems and volcano smog  

MedlinePLUS

Volcanic smog (vog) is created when sulfur dioxide and other gases released from a volcano react with oxygen, moisture, dust, and sunlight in the atmosphere. Volcanic smog can irritate the lungs and worsen existing lung ...

192

Paleomagnetism of Paisano Volcano, Texas  

E-print Network

PALEOMAGNETISM OF PAISANO VOLCANO, TEXAS A Thesis by DAVID RYAN Submitted to the Office of Graduate Studies of Texas ARM University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE December 1988 Major Subject...: Geophysics PALEOMAGNETISM OF PAISANO VOLCANO, TEXAS A Thesis by DAVID RYAN Approved as to style and content by: William W. Sager (Chairman of Committee) Tibor G. Rozgon i (Member) Earl R. Hoskins (Member) Robert J. McCabe (Member) Joe S. Watkins...

Ryan, David

2012-06-07

193

Sensitivity of the East African rift lakes to climate variability  

Microsoft Academic Search

Lakes in the East African Rift have provided excellent proxies to reconstruct past climate changes in the low latitudes. The lakes occupy volcano-tectonic depressions with highly variable climate and hydrological setting, that present a good opportunity to study the climatic and hydrogeological influences on the lake water budget. Previous studies have used lake floor sediments to establish the sensitivity of

L. Olaka; M. H. Trauth

2009-01-01

194

Mount St. Helens and Kilauea volcanoes  

SciTech Connect

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

Barrat, J. (Smithsonian Institution, Washington, DC (USA))

1989-01-01

195

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.

2010-02-19

196

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.

197

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

198

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

199

20 months of sustained changes at Turrialba volcano. Visual changes.  

NASA Astrophysics Data System (ADS)

Turrialba Volcano (3340 m) is located at the southern end of the Mesoamerican Volcanic Arc. The summit area has three craters aligned NE-SW: East, Central and West craters. The last active period of Turrialba Volcano occurred between 1864-1866. During this period, the West crater of Turrialba was formed and ash falls were reported in the Central Valley of Costa Rica. Mild to moderate fumarolic activity has been present at Turrialba volcano, Central and West craters, since 1866. This volcano has shown a variety of activity peaks during the last 10 years, mainly seismic swarms and vigorous gas activity. Furthermore, at the middle of 2005 one of the greater degassing events took place provoking serious effects on vegetation and expanding fumaroles towards the W and NW edges of the caldera. Cracks around these sectors are releasing unestimated amounts of gas and vapor. Rapid sedimentation in the bottom of W crater has been also reported. Enrichment of routinely sampled fumaroles make gas sampling process more difficult. Expansion of heated ground around the W crater is accompanied by deposition of sulphur salts and other sulphur-relative deposits. Rapid erosion of the W crater accompanied of yet more vigorous degassing has sustained all through 2006. On august a report was given to the national and international community due to the rapid burning and death of major tree species. Most of dwarf vegetation and small vegetation coverage is rapidly disappearing thus affecting directly the fragile balance between flora and fauna. Disorders in the feeding and behavior of a community of coyotes has been observed, always related to acute impact of volcanic activity. More changes in other species that inhabit the summit areas are expected. Moreover, pressure and impact on settlers, living in the low lands around the volcano, is also expected. A poster will illustrate areas of gas expansion, physical instability and sedimentation. It will also show areas where major impact on vegetation and fauna is taking place.

Duarte, E.; Fernandez, E.; Saenz, W.; Martinez, M.; Barboza, V.

2007-05-01

200

Anomalous earthquakes associated with Nyiragongo Volcano: Observations and potential mechanisms  

NASA Astrophysics Data System (ADS)

A series of five unusual earthquakes (4.6 ? M ? 5.3) has been recently located near Nyiragongo volcano (D. R. Congo) in the Western Rift Valley of the East African Rift. Despite their moderate size, these earthquakes do not appear in global seismicity catalogs, but were located using long-period surface waves primarily recorded on the Global Seismographic Network. Three of the events occurred in the week following the January 2002 eruption of Nyiragongo, while the final two occurred in 2003 and 2005 respectively, and are not linked to a major eruption at Nyiragongo or its neighboring volcano, Nyamuragira. Several common techniques were used to investigate the characteristics of these seismic sources in the context of the volcanic activity of the region. The frequency content of the five anomalous earthquakes was compared to that from local events found in global catalogs, and the newly detected earthquakes were shown to be slow events, being greatly depleted in frequencies above 0.1 Hz. Each of the newly detected earthquakes was modeled by a series of forces and by a centroid-moment tensor. A deviatoric moment tensor was shown to provide a better fit to the data. The newly detected earthquakes are highly non-double-couple in nature, each having a large compensated-linear-vector-dipole component of the moment tensor. Drawing on models based on similar observations from other active volcanoes, we propose that the earthquakes are caused by slip on non-planar faults beneath the volcano. We suggest a mechanism in which these newly detected earthquakes are generated by the collapse of the roof of a shallow magma chamber along an inward-dipping cone-shaped ring fault. Diking events, which result in magma evacuation from shallow magma chambers, could trigger such earthquakes. Our results provide new constraints on the dynamics of the poorly understood magma system beneath Nyiragongo, an active volcano that is a significant threat to life and property.

Shuler, Ashley; Ekström, Göran

2009-04-01

201

Resistivity Changes of Sakurajima Volcano by Magnetotelluric Continuous Observations  

NASA Astrophysics Data System (ADS)

In order to predict volcano eruptions and to contribute to hazard mitigation, monitoring of subsurface magma movement is the most essential approach. Recent study of time change of seismic structure (4D tomography) in Etna volcano clearly imaged time change of Vp/Vs structure, [Patanè et al., 2006]. They showed that structure changes not only on the location of magma intrusion but widely around the intrusion. They attributed Vp/Vs change to subsurface magma movement and fluids migration from the intrusion zone. Another method using seismic noise records are proposed to monitor the subsurface seismic structure [Brenguier et al., 2008]. These seismic methods have a great potential to reliable prediction of volcano eruption, though the method need densely deployed seismometer network. Monitoring electric resistivity structure is also the promising tools for imaging the subsurface magma movement, because magma and degassed volatile is highly conductive. Indeed, by repeated DC electric measurement using active source field, significant resistivity change is detected before and after the 1986 eruption of Izu-Oshima volcano, and the subsurface magma movement is deduced [Yukutake et al., 1990; Utada, 2003]. In this study, we show the first results of the long term continuous magnetotellurics (MT) observation to monitor the resistivity structure. Because MT impedance is stable and high time resolution [Eisel and Egbert, 2001; Hanekop and Simpson, 2006], the continuous MT observation is suitable to detect subsurface resistivity changes. We conducted long-term MT continuous measurements since May, 2008 to July, 2009 at Sakurajima, which is the most active volcano in Japan. Two observation sites were set up at 3.3km east, and 3km WNW of the summit crater. The obtained MT impedance shows significant apparent resistivity changes, which continues 20~50 days, in the frequency range between 300-1 Hz at the both observation sites. This frequency range corresponds to the depth around sea level, where groundwater is likely to exist. The start of the resistivity changes roughly coincide with the start of the uplift of the summit detected by the underground tunnel tiltmeter, which is one of the most reliable indicators of the subsurface magma intrusion of Sakurajima volcano. A possible cause of the apparent resistivity change is the volatile degassed from rising magma. In this study, we will carefully investigate the cause of the resistivity change of showing various data of volcano activities.

Aizawa, K.; Kanda, W.; Ogawa, Y.; Iguchi, M.; Yokoo, A.

2009-12-01

202

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

203

Ash and Steam, Soufriere Hills Volcano, Monserrat  

NASA Technical Reports Server (NTRS)

International Space Station crew members are regularly alerted to dynamic events on the Earth's surface. On request from scientists on the ground, the ISS crew observed and recorded activity from the summit of Soufriere Hills on March 20, 2002. These two images provide a context view of the island (bottom) and a detailed view of the summit plume (top). When the images were taken, the eastern side of the summit region experienced continued lava growth, and reports posted on the Smithsonian Institution's Weekly Volcanic Activity Report indicate that 'large (50-70 m high), fast-growing, spines developed on the dome's summit. These spines periodically collapsed, producing pyroclastic flows down the volcano's east flank that sometimes reached the Tar River fan. Small ash clouds produced from these events reached roughly 1 km above the volcano and drifted westward over Plymouth and Richmond Hill. Ash predominately fell into the sea. Sulfur dioxide emission rates remained high. Theodolite measurements of the dome taken on March 20 yielded a dome height of 1,039 m.' Other photographs by astronauts of Montserrat have been posted on the Earth Observatory: digital photograph number ISS002-E-9309, taken on July 9, 2001; and a recolored and reprojected version of the same image. Digital photograph numbers ISS004-E-8972 and 8973 were taken 20 March, 2002 from Space Station Alpha and were provided by the Earth Sciences and Image Analysis Laboratory at Johnson Space Center. Additional images taken by astronauts and cosmonauts can be viewed at the NASA-JSC Gateway to Astronaut Photography of Earth.

2002-01-01

204

Coral Ba/Ca records of sediment input to the fringing reef of the southshore of Moloka'i, Hawai'i over the last several decades  

USGS Publications Warehouse

The fringing reef of southern Moloka’i is perceived to be in decline because of land-based pollution. In the absence of historical records of sediment pollution, ratios of coral Ba/Ca were used to test the hypothesis that sedimentation has increased over time. Baseline Ba/Ca ratios co-vary with the abundance of red, terrigenous sediment visible in recent imagery. The highest values at One Ali’i are near one of the muddiest parts of the reef. This co-varies with the lowest growth rate of all the sites, perhaps because the upstream Kawela watershed was historically leveed all the way to the nearshore, providing a fast-path for sediment delivery. Sites adjacent to small, steep watersheds have ?decadal periodicities whereas sites adjacent to mangrove forests have shorter-period fluctuations that correspond to the periodicity of sediment transport in the nearshore, rather than the watershed. All four sites show a statistically significant upward trend in Ba/Ca.

Prouty, N. G.; Field, M. E.; Stock, J. D.; Jupiter, S. D.; McCulloch, M.

2010-01-01

205

Understanding Volcano Hazards and Preventing Volcanic Disasters A Science Strategy for the Volcano Hazards Program,  

E-print Network

Understanding Volcano Hazards and Preventing Volcanic Disasters A Science Strategy for the Volcano active volcanoes, the United States is among the most volcanically active countries in the world. During and property through exposure to volcano hazards continue to increase. Moreover, rapid globalization makes U

Torgersen, Christian

206

REDUCING THE RISK FROM VOLCANO HAZARDS BenefitsofVolcanoMonitoringFarOutweigh  

E-print Network

REDUCING THE RISK FROM VOLCANO HAZARDS BenefitsofVolcanoMonitoringFarOutweigh Costs--TheCaseofMountPinatubo T Villagers fleeing the vicinity of Mount Pinatubo, Philippines, during heavy ash fall from the volcano and the U.S. Geological Survey forecast this eruption, enabling people living near the volcano to evacuate

Torgersen, Christian

207

Seismicity characteristics of a potentially active Quaternary volcano: The Tatun Volcano Group, northern Taiwan  

E-print Network

Seismicity characteristics of a potentially active Quaternary volcano: The Tatun Volcano Group Volcano Group (TVG) is located at the northern tip of Taiwan, near the capital Taipei and close to two as an extinct volcano, even though more recent studies suggest that TVG might have been active during the last

Lin, Andrew Tien-Shun

208

The changing shapes of active volcanoes: History, evolution, and future challenges for volcano geodesy  

E-print Network

The changing shapes of active volcanoes: History, evolution, and future challenges for volcano Volcano Observatory, Crater Rim Drive, Hawaii National Park, HI 96718-0051, United States b Department of Earth's active volcanoes. By their very nature, however, the magmatic reservoirs and conduits

209

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

E-print Network

When mud volcanoes sleep: Insight from seep geochemistry at the Dashgil mud volcano, Azerbaijan A Available online 18 November 2008 Keywords: Dashgil mud volcano Azerbaijan Dormant Methane Water geochemistry a b s t r a c t The worlds >1500 mud volcanoes are normally in a dormant stage due to the short

Mazzini, Adriano

210

Volcano-earthquake interaction at Mauna Loa volcano, Hawaii Thomas R. Walter1,2  

E-print Network

Volcano-earthquake interaction at Mauna Loa volcano, Hawaii Thomas R. Walter1,2 and Falk Amelung1] The activity at Mauna Loa volcano, Hawaii, is characterized by eruptive fissures that propagate transfer can explain the observed volcano-earthquake interaction. We examine stress changes due to typical

Amelung, Falk

211

A Benthic Invertebrate Survey of Jun Jaegyu Volcano: An active undersea volcano in Antarctic Sound, Antarctica  

Microsoft Academic Search

Jun Jaegyu volcano, an Antarctic submarine volcano, was dredged in May 2004 during cruise 04-04 of the RV Laurence M. Gould to determine rock, sediment composition and marine macroinvertebrate diversity. The objectives of this study are to examine the benthic assemblages and biodiversity present on a young volcano. The volcano is located on the continental shelf of the northeastern Antarctic

G. Quinones; S. Brachfeld; M. Gorring; R. S. Prezant; E. Domack

2005-01-01

212

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

213

Costa Rica's Chain of laterally collapsed volcanoes  

Microsoft Academic Search

From the NW extreme to the SW end of Costa Rica's volcanic backbone, a number of laterally collapsed volcanoes can be observed. Due to several factors, attention has been given to active volcanoes disregarding the importance of collapsed features in terms of assessing volcanic hazards for future generations around inhabited volcanoes. In several cases the typical horseshoe shape amphitheater-like depression

E. Duarte; E. Fernandez

2007-01-01

214

EarthScope: Activity at Augustine Volcano  

NSDL National Science Digital Library

This bulletin provides information on the recent eruptive activity of Augustine Volcano in Alaska. Topics include some history of the volcano, its geologic setting as part of the Aleutian island arc, and earthquake locations as indicators of magma movement. The bulletin is also accompanied by a 360-degree rotation around the volcano and background information on the EarthScope Project.

2011-06-03

215

Capulin Volcano National Monument September 7, 2000  

E-print Network

Capulin Volcano National Monument September 7, 2000 Landsat Enhanced Thematic Mapper + (RGB = 4,3,2) Noxious Weeds Inventory and Mapping at Capulin Volcano National Monument, Fort Union National Monument and delineate areas of noxious weeds within Capulin Volcano National Monument and Fort Union National Monument

Nebraska-Lincoln, University of

216

Global Volcano Mortality Risk Distribution Projection: Robinson  

E-print Network

Global Volcano Mortality Risk Distribution Projection: Robinson Mortality risk is found by weighting the value of population exposure to volcanoes for each grid cell by a vulnerability coefficient and Development/The World Bank and Columbia University. Volcano Mortality Risk Deciles 1 st ­4 th 5 th ­7 th 8 th

Columbia University

217

The Volcano Optimizer Jan. 29 2003  

E-print Network

The Volcano Optimizer Generator Jan. 29 2003 Presented by Peng Wang in CIS650 Cite: Zhang Da Generator System General "toolkits" for creating customized DBs Exodus (Graefe&DeWitt,87) Volcano (Graefe;4 The Motivation of Volcano High Performance Optimization time Memory consumption for search More Extensibility

Ives, Zachary G.

218

Hydrogen emissions from Erebus volcano, Antarctica  

E-print Network

Hydrogen emissions from Erebus volcano, Antarctica Yves Moussallam1 , Clive Oppenheimer1, 2, 3 of molecular hydrogen (H2) emissions from passively degassing volcanoes has recently been made possible using with SO2, H2O and CO2, in the gas and aerosol plume emitted from the phonolite lava lake at Erebus volcano

Paris-Sud XI, Université de

219

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

220

Man Against Volcano: The Eruption on Heimaey,  

E-print Network

Man Against Volcano: The Eruption on Heimaey, Vestmannaeyjar, Iceland This booklet was originally published in 1976 under the title "Man Against Volcano:The Eruption on Heimaey, Vestmann Islands, Iceland:Town of Vestmannaeyjar with Helgafell in the right back- ground (photo courtesy of Sólarfilma). #12;Man Against Volcano

Ingólfsson, �lafur

221

Remote Sensing of Active Volcanoes  

NASA Astrophysics Data System (ADS)

The synoptic coverage offered by satellites provides unparalleled opportunities for monitoring active volcanoes, and opens new avenues of scientific inquiry. Thermal infrared radiation can be used to monitor levels of activity, which is useful for automated eruption detection and for studying the emplacement of lava flows. Satellite radars can observe volcanoes through clouds or at night, and provide high-resolution topographic data. In favorable conditions, radar inteferometery can be used to measure ground deformation associated with eruptive activity on a centimetric scale. Clouds from explosive eruptions present a pressing hazard to aviation; therefore, techniques are being developed to assess eruption cloud height and to discriminate between ash and meterological clouds. The multitude of sensors to be launched on future generations of space platforms promises to greatly enhance volcanological studies, but a satellite dedicated to volcanology is needed to meet requirements of aviation safety and volcano monitoring.

Francis, Peter; Rothery, David

222

Global Volcano Model  

NASA Astrophysics Data System (ADS)

Over 600 million people live close enough to active volcanoes to be affected when they erupt. Volcanic eruptions cause loss of life, significant economic losses and severe disruption to people's lives, as highlighted by the recent eruption of Mount Merapi in Indonesia. The eruption of Eyjafjallajökull, Iceland in 2010 illustrated the potential of even small eruptions to have major impact on the modern world through disruption of complex critical infrastructure and business. The effects in the developing world on economic growth and development can be severe. There is evidence that large eruptions can cause a change in the earth's climate for several years afterwards. Aside from meteor impact and possibly an extreme solar event, very large magnitude explosive volcanic eruptions may be the only natural hazard that could cause a global catastrophe. GVM is a growing international collaboration that aims to create a sustainable, accessible information platform on volcanic hazard and risk. We are designing and developing an integrated database system of volcanic hazards, vulnerability and exposure with internationally agreed metadata standards. GVM will establish methodologies for analysis of the data (eg vulnerability indices) to inform risk assessment, develop complementary hazards models and create relevant hazards and risk assessment tools. GVM will develop the capability to anticipate future volcanism and its consequences. NERC is funding the start-up of this initiative for three years from November 2011. GVM builds directly on the VOGRIPA project started as part of the GRIP (Global Risk Identification Programme) in 2004 under the auspices of the World Bank and UN. Major international initiatives and partners such as the Smithsonian Institution - Global Volcanism Program, State University of New York at Buffalo - VHub, Earth Observatory of Singapore - WOVOdat and many others underpin GVM.

Sparks, R. S. J.; Loughlin, S. C.; Cottrell, E.; Valentine, G.; Newhall, C.; Jolly, G.; Papale, P.; Takarada, S.; Crosweller, S.; Nayembil, M.; Arora, B.; Lowndes, J.; Connor, C.; Eichelberger, J.; Nadim, F.; Smolka, A.; Michel, G.; Muir-Wood, R.; Horwell, C.

2012-04-01

223

Alaska volcanoes guidebook for teachers  

USGS Publications Warehouse

Alaska’s volcanoes, like its abundant glaciers, charismatic wildlife, and wild expanses inspire and ignite scientific curiosity and generate an ever-growing source of questions for students in Alaska and throughout the world. Alaska is home to more than 140 volcanoes, which have been active over the last 2 million years. About 90 of these volcanoes have been active within the last 10,000 years and more than 50 of these have been active since about 1700. The volcanoes in Alaska make up well over three-quarters of volcanoes in the United States that have erupted in the last 200 years. In fact, Alaska’s volcanoes erupt so frequently that it is almost guaranteed that an Alaskan will experience a volcanic eruption in his or her lifetime, and it is likely they will experience more than one. It is hard to imagine a better place for students to explore active volcanism and to understand volcanic hazards, phenomena, and global impacts. Previously developed teachers’ guidebooks with an emphasis on the volcanoes in Hawaii Volcanoes National Park (Mattox, 1994) and Mount Rainier National Park in the Cascade Range (Driedger and others, 2005) provide place-based resources and activities for use in other volcanic regions in the United States. Along the lines of this tradition, this guidebook serves to provide locally relevant and useful resources and activities for the exploration of numerous and truly unique volcanic landscapes in Alaska. This guidebook provides supplemental teaching materials to be used by Alaskan students who will be inspired to become educated and prepared for inevitable future volcanic activity in Alaska. The lessons and activities in this guidebook are meant to supplement and enhance existing science content already being taught in grade levels 6–12. Correlations with Alaska State Science Standards and Grade Level Expectations adopted by the Alaska State Department of Education and Early Development (2006) for grades six through eleven are listed at the beginning of each activity. A complete explanation, including the format of the Alaska State Science Standards and Grade Level Expectations, is available at the beginning of each grade link at http://www.eed.state.ak.us/tls/assessment/GLEHome.html.

Adleman, Jennifer N.

2011-01-01

224

Using multiplets to track volcanic processes at Kilauea Volcano, Hawaii  

NASA Astrophysics Data System (ADS)

Multiplets, or repeating earthquakes, are commonly observed at volcanoes, particularly those exhibiting unrest. At Kilauea, multiplets have been observed as part of long period (LP) earthquake swarms [Battaglia et al., 2003] and as volcano-tectonic (VT) earthquakes associated with dike intrusion [Rubin et al., 1998]. The focus of most previous studies has been on the precise location of the multiplets based on reviewed absolute locations, a process that can require extensive human intervention and post-processing. Conversely, the detection of multiplets and measurement of multiplet parameters can be done in real-time without human interaction with locations approximated by the stations that best record the multiplet. The Hawaiian Volcano Observatory (HVO) is in the process of implementing and testing an algorithm to detect multiplets in near-real time and to analyze certain metrics to provide enhanced interpretive insights into ongoing volcanic processes. Metrics such as multiplet percent of total seismicity, multiplet event recurrence interval, multiplet lifespan, average event amplitude, and multiplet event amplitude variability have been shown to be valuable in understanding volcanic processes at Bezymianny Volcano, Russia and Mount St. Helens, Washington and thus are tracked as part of the algorithm. The near real-time implementation of the algorithm can be triggered from an earthworm subnet trigger or other triggering algorithm and employs a MySQL database to store results, similar to an algorithm implemented by Got et al. [2002]. Initial results using this algorithm to analyze VT earthquakes along Kilauea's Upper East Rift Zone between September 2010 and August 2011 show that periods of summit pressurization coincide with ample multiplet development. Summit pressurization is loosely defined by high rates of seismicity within the summit and Upper East Rift areas, coincident with lava high stands in the Halema`uma`u lava lake. High percentages, up to 100%, of earthquakes occurring during summit pressurization were part of a multiplet. Percentages were particularly high immediately prior to the March 5 Kamoamoa eruption. Interestingly, many multiplets that were present prior to the Kamoamoa eruption were reactivated during summit pressurization occurring in late July 2011. At a correlation coefficient of 0.7, 90% of the multiplets during the study period had populations of 10 or fewer earthquakes. Between periods of summit pressurization, earthquakes that belong to multiplets rarely occur, even though magma is flowing through the Upper East Rift Zone. Battaglia, J., Got, J. L. and Okubo, P., 2003. Location of long-period events below Kilauea Volcano using seismic amplitudes and accurate relative relocation. Journal of Geophysical Research-Solid Earth, v.108 (B12) 2553. Got, J. L., P. Okubo, R. Machenbaum, and W. Tanigawa (2002), A real-time procedure for progressive multiplet relative relocation at the Hawaiian Volcano Observatory, Bulletin of the Seismological Society of America, 92(5), 2019. Rubin, A. M., D. Gillard, and J. L. Got (1998), A reinterpretation of seismicity associated with the January 1983 dike intrusion at Kilauea Volcano, Hawaii, Journal of Geophysical Research-Solid Earth, 103(B5), 10003.

Thelen, W. A.

2011-12-01

225

Savage Earth: Out of the Inferno - Volcanoes  

NSDL National Science Digital Library

This article, entitled Mountains of Fire, describes the relationship between the types of volcanic activity and plate movement and the connection between types of volcanoes and how they erupt. The article is supported by a video of an erupting volcano, a photograph of an eruption and an animation depicting pyroclastic flow and the formation of a composite volcano. It is also supported by three sidebars, called Volcanoes of North America, Montserrat: An Island Under Siege, and Volcanoes on other Planets. These sidebars also have videos or photographs to enhance their message.

226

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.

227

Field-mapping and petrographic analysis of volcanoes surrounding the Lake Natron Homo sapiens footprint site, northern Tanzania  

Microsoft Academic Search

The Lake Natron Homo sapiens footprint site is located in northern Tanzania along the East African Rift escarpment. The site is positioned south of Lake Natron within an ephemeral channel of the Engare Sero River. The hominid footprints are preserved in a tuff, which originated from one of the volcanic centers surrounding the site. Two large volcanoes in the surrounding

S. M. Hewitt; B. Zimmer; C. Liutkus; S. K. Carmichael; K. McGinnis

2010-01-01

228

Constructing the upper crust of the Mid-Atlantic Ridge: A reinterpretation based on the Puna Ridge, Kilauea Volcano  

Microsoft Academic Search

The volcanic morphology of a number of segments of the slow spreading Mid-Atlantic Ridge (MAR) have been reinterpreted based on our understanding of dike emplacement, dike propagation, and eruption at the East Rift Zone of Kilauea Volcano, Hawaii and its submarine extension, the Puna Ridge. The styles of volcanic eruption at the submarine Puna Ridge are remarkably similar to those

Deborah K. Smith; Johnson R. Cann

1999-01-01

229

Space Radar Image of Taal Volcano, Philippines  

NASA Technical Reports Server (NTRS)

This is an image of Taal volcano, near Manila on the island of Luzon in the Philippines. The black area in the center is Taal Lake, which nearly fills the 30-kilometer-diameter (18-mile) caldera. The caldera rim consists of deeply eroded hills and cliffs. The large island in Taal Lake, which itself contains a crater lake, is known as Volcano Island. The bright yellow patch on the southwest side of the island marks the site of an explosion crater that formed during a deadly eruption of Taal in 1965. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on its 78th orbit on October 5, 1994. The image shows an area approximately 56 kilometers by 112 kilometers (34 miles by 68 miles) that is centered at 14.0 degrees north latitude and 121.0 degrees east longitude. North is toward the upper right of the image. The colors in this image were obtained using the following radar channels: red represents the L-band (horizontally transmitted and received); green represents the L-band (horizontally transmitted and vertically received); blue represents the C-band (horizontally transmitted and vertically received). Since 1572, Taal has erupted at least 34 times. Since early 1991, the volcano has been restless, with swarms of earthquakes, new steaming areas, ground fracturing, and increases in water temperature of the lake. Volcanologists and other local authorities are carefully monitoring Taal to understand if the current activity may foretell an eruption. Taal is one of 15 'Decade Volcanoes' that have been identified by the volcanology community as presenting large potential hazards to population centers. The bright area in the upper right of the image is the densely populated city of Manila, only 50 kilometers (30 miles) north of the central crater. Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves, allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those changes which are induced by human activity. SIR-C was developed by NASA's Jet Propulsion Laboratory. X-SAR was developed by the Dornier and Alenia Spazio companies for the German space agency, Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA), and the Italian space agency, Agenzia Spaziale Italiana (ASI), with the Deutsche Forschungsanstalt fuer Luft und Raumfahrt e.v.(DLR), the major partner in science, operations and data processing of X-SAR.

1994-01-01

230

Papers about Volcanoes and Tsunamis  

NSDL National Science Digital Library

Steven N Ward, a Earth Sciences professor at UC-Santa Cruz, provides downloadable PDF versions of his numerous publications about volcanoes and tsunamis as a part of his homepage. Topics include tsunamis caused by earthquakes, underwater landslides, volcanic eruptions, and asteroid impacts, as well as risk assessment and modeling.

Ward, Steven N.

231

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

232

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.

233

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.

234

East Africa  

NASA Technical Reports Server (NTRS)

This image shows the East African nations of Ethiopia, Eritrea, and Somalia, as well as portions of Kenya, Sudan, Yemen, and Saudi Arabia. Dominating the scene are the green Ethiopian Highlands. With altitudes as high as 4,620 meters (15,157 feet), the highlands pull moisture from the arid air, resulting in relatively lush vegetation. In fact, coffee-one of the world's most prized crops-originated here. To the north (above) the highlands is Eritrea, which became independent in 1993. East (right) of Ethiopia is Somalia, jutting out into the Indian Ocean. The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) captured this true-color image on November 29, 2000. Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

2002-01-01

235

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

236

Predictions of turbidity due to enhanced sediment resuspension resulting from sea-level rise on a fringing Coral Reef: Evidence from Molokai, Hawaii  

USGS Publications Warehouse

Accelerating sea-level rise associated with global climate change will affect sedimentary processes on coral reefs and other shoreline environments by increasing energy and sediment resuspension. On reefs, sedimentation is known to increase coral stress and bleaching as particles that settle on coral surfaces interfere with photosynthesis and feeding, and turbidity induced by suspended sediment reduces incident light levels. Using relationships developed from observations of wave orbital velocity, water-surface elevation, and suspended-sediment concentration on a fringing reef flat of Molokai, Hawaii, predictions of the average daily maximum in suspended-sediment concentration increase from ~11 mg/l to ~20 mg/l with 20 cm sea-level rise. The duration of time concentrations exceeds 10 mg/l increases from 9 to 37. An evaluation of the reduction of wave energy flux through breaking and frictional dissipation across the reef flat shows an increase of ~80 relative to the present will potentially reach the shoreline as sea level increases by 20 cm. Where the shoreline exists on low, flat terrain, the increased energy could cause significant erosion of the shoreline. Considering the sediment budget, the sediment flux is predicted to increase and removal of fine-grained sediment may be expedited on some fringing reefs, and sediment in storage on the inner reef could ultimately be reduced. However, increased shoreline erosion may add sediment and offset removal from the reef flat. The shifts in sediment availability and transport that will occur as result of a modest increase in sea level have wide application to fringing coral reefs elsewhere, as well as other shoreline environments. ?? 2010 the Coastal Education & Research Foundation (CERF).

Ogston, A.S.; Field, M.E.

2010-01-01

237

Iridium emissions from Hawaiian volcanoes  

NASA Technical Reports Server (NTRS)

Particle and gas samples were collected at Mauna Loa volcano during and after its eruption in March and April, 1984 and at Kilauea volcano in 1983, 1984, and 1985 during various phases of its ongoing activity. In the last two Kilauea sampling missions, samples were collected during eruptive activity. The samples were collected using a filterpack system consisting of a Teflon particle filter followed by a series of 4 base-treated Whatman filters. The samples were analyzed by INAA for over 40 elements. As previously reported in the literature, Ir was first detected on particle filters at the Mauna Loa Observatory and later from non-erupting high temperature vents at Kilauea. Since that time Ir was found in samples collected at Kilauea and Mauna Loa during fountaining activity as well as after eruptive activity. Enrichment factors for Ir in the volcanic fumes range from 10,000 to 100,000 relative to BHVO. Charcoal impregnated filters following a particle filter were collected to see if a significant amount of the Ir was in the gas phase during sample collection. Iridium was found on charcoal filters collected close to the vent, no Ir was found on the charcoal filters. This indicates that all of the Ir is in particulate form very soon after its release. Ratios of Ir to F and Cl were calculated for the samples from Mauna Loa and Kilauea collected during fountaining activity. The implications for the KT Ir anomaly are still unclear though as Ir was not found at volcanoes other than those at Hawaii. Further investigations are needed at other volcanoes to ascertain if basaltic volcanoes other than hot spots have Ir enrichments in their fumes.

Finnegan, D. L.; Zoller, W. H.; Miller, T. M.

1988-01-01

238

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

NASA Astrophysics Data System (ADS)

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

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

1982-11-01

239

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

240

Temperature of an active lava channel from spectral measurements, Kilauea Volcano, Hawaii  

Microsoft Academic Search

A narrow band spectroradiometer was used to determine the characteristic temperatures of a very active channeled lava flow for the phase 50 eruption of Pu'u 'O'o on the East Rift Zone of Kilauea Volcano, Hawaii. During the twilight of 19 February 1992, 14 spectra of this activity were acquired over a 51 minute interval [18.29 to 19.20 Hawaiian Standard Time

Luke P. Flynn; Peter J. Mouginis-Mark

1994-01-01

241

The Late Holocene Compositionally Zoned Glass Mountain Eruption at Medicine Lake Volcano, California  

Microsoft Academic Search

The spectacular Glass Mountain rhyolite-dacite flow erupted high on the east side of Medicine Lake volcano 950 yrs ago, producing one cubic kilometer of pumice and lava from more than a dozen vents along a 5-km- long fissure. Detailed mapping and chemical\\/petrographic analysis of 107 lava and tephra samples, 40 quenched andesitic blobs, 18 co-magmatic cumulates, and 6 granitoid fragments

J. M. Donnelly-Nolan; T. L. Grove

2008-01-01

242

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

Microsoft Academic Search

The island of Kauai has always been interpreted as a single shield volcano, but lavas of previously correlated reversed-to-normal magnetic-polarity transitions on opposite sides of the island differ significantly in isotopic composition. Samples from west Kauai have 87Sr\\/86Sr < 0.7037, ?Nd >= 6.14, and 206Pb\\/204Pb > 18.25; samples from east Kauai have 87Sr\\/86Sr > 0.7037, ?Nd <= 6.14, and 206Pb\\/204Pb

Robin T. Holcomb; Peter W. Reiners; Bruce K. Nelson; Nuni-Lyn E. Sawyer

1997-01-01

243

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

NSF Publications Database

... an active underwater volcano near the Samoan Island chain. During a research cruise to study the ... indication that this volcano existed. When sound beams were directed into the crater, they measured ...

244

Review of the United States Geological Survey Volcano Hazards Program  

E-print Network

Review of the United States Geological Survey Volcano Hazards Program Authors and Review Panel.................................................................................................................. 6 1.1 The Volcano Hazards Program Mission and Significance......................................................................................................... 12 3.1 Volcano Hazard Assessments

Torgersen, Christian

245

The USGS Hawaiian Volcano Observatory Monitors Klauea's Summit Eruption  

USGS Multimedia Gallery

The USGS Hawaiian Volcano Observatory (foreground) is located on the caldera rim of Kilauea Volcano, Hawai'i?the most active volcano in the world.  The observatory's location provides an excellent view of summit eruptive activity, which began in 2008....

2010-08-18

246

Shallow plumbing systems for small-volume basaltic volcanoes  

NASA Astrophysics Data System (ADS)

Eruptive dynamics in basaltic volcanoes are controlled, in part, by the conduit geometry. However, uncertainties in conduit shape and dike-to-conduit transition geometry have limited our predictive capability for hazards assessments. We characterize 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 by erosion and exhibiting feeder dikes, conduits, and vent areas ?250 m depth. Study areas include East Grants Ridge (New Mexico, USA), Basalt Ridge, East Basalt Ridge, Paiute Ridge, and Southeast Crater Flat (Nevada, USA). Basaltic feeder dikes 250 to 100 m deep have typical widths of 4-12 m, with smooth host-rock contacts (rhyolite tuff). At depths less than 100 m, heterogeneities in the host rock form preferential pathways for small dike splays and sills, resulting in a 30-m effective width at 50 m depth. The development of a complex conduit at depths less than 70 m is reflected in bifurcating dikes and brecciation and incorporation of the country rock. The overall zone of effect at depths less than 50 m is ?110 m wide (220 m elongated along the feeder dike). Based on comparisons with theoretical conduit flow models, the width of the feeder dike at depths from 250 to 500 m is expected to range from 1 to 10 m and is expected to decrease to about 1-2 m at depths greater than 500 m. The flaring shape of the observed feeder systems is similar to results of theoretical modeling using lithostatic pressure-balanced flow conditions. Sizes of observed conduits differ from modeled dimensions by up to a factor of 10 in the shallow subsurface (<50 m depth), but at depths greater than 100 m the difference is a factor of 2 to 4. This difference is primarily due to the fact that observed eroded conduits record the superimposed effects of multiple eruptive events, while theoretical model results define dimensions necessary for a single, steady eruption phase. The complex details of magma-host rock interactions observed at the study areas (contact welding, brecciation, bifurcating dikes and sills, and stoping) represent the mechanisms by which the lithostatic pressure-balanced geometry is attained. The similarity in the normalized shapes of theoretical and observed conduits demonstrates the appropriateness of the pressure-balanced modeling approach, consistent with the conclusions of Wilson and Head (J Geophys Res 86:2971-3001, 1981) for this type of volcano.

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

2008-03-01

247

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

248

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.

249

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

250

New studies of Martian volcanoes  

NASA Technical Reports Server (NTRS)

To investigate the morphology, topography, and evolution of volcanic constructs on Mars, researchers have been studying the volcanoes Olympus Mons, Tyrrhena Patera, and Apollinaris Patera. These studies relied upon the analysis of digital Viking orbiter images to measure the depth and slopes of the summit area of Olympus Mons, upon new Earth-based radar measurements for the analysis of the slopes of Tyrrhena Patera, and upon the color characteristics of the flanks of Apollinaris Patera for information regarding surface properties.

Mouginis-Mark, P. J.; Robinson, M. S.; Zisk, S. H.

1991-01-01

251

Morphometric properties of Martian volcanoes  

Microsoft Academic Search

Mars Orbiter Laser Altimeter (MOLA) data have been used to construct Digital Elevation Models (DEM) of the Martian volcanoes in order to determine height, flank slope, caldera depth, and volumes. Summit elevations range from 21.1 km to ?0.5 km, and relief varies from 1.0 km to almost 22 km. Average flank slopes are in the range of <1° to ?10°,

J. B. Plescia

2004-01-01

252

Volcano monitoring using GPS: Developing data analysis strategies based on the June 2007 Klauea Volcano intrusion  

E-print Network

Click Here for Full Article Volcano monitoring using GPS: Developing data analysis strategies based on the June 2007 Klauea Volcano intrusion and eruption Kristine M. Larson,1 Michael Poland,2 and Asta Miklius2, used to monitor volcano deformation. In addition to slow (several centimeters per year) displacement

Larson, Kristine

253

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.

254

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.

255

Topography of Martian central volcanoes  

NASA Technical Reports Server (NTRS)

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. B.; Cutts, J. A.

1981-01-01

256

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

257

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.

258

Thematic mapper studies of Andean volcanoes  

NASA Technical Reports Server (NTRS)

The primary objective was to identify all the active volcanoes in the Andean region of Bolivia. Morphological features of the Tata Sabaya volcano, Bolivia, were studied with the thematic mapper. Details include marginal levees on lava and pyroclastic flows, and summit crater structure. Valley glacier moraine deposits, not easily identified on the multispectral band scanner, were also unambiguous, and provide useful marker horizons on large volcanic edifices which were built up in preglacial times but which were active subsequently. With such high resolution imagery, it is not only possible to identify potentially active volcanoes, but also to use standard photogeological interpretation to outline the history of individual volcanoes.

Francis, P. W.

1986-01-01

259

From: Volcano Watch, September 26, 1997 Volcano Watch, a weekly feature written by scientists at the USGS Hawaiian Volcano Observatory, is  

E-print Network

From: Volcano Watch, September 26, 1997 Volcano Watch, a weekly feature written by scientists at the USGS Hawaiian Volcano Observatory, is posted on the HVO Web site (http zone of Mauna Loa Volcano in historic time. The 1919 Alika eruption was the most voluminous historical

260

Rockfalls at Augustine Volcano, Alaska: 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. Typical events lasted about 30 sec, had frequencies >6 Hz, and were strongest 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 peaked in May and June, then continued through the fall and early winter. Overall there were more than 340 rockfalls in 2005, with both small and large events occurring. The 2005 rockfall activity increased at nearly the same time as earthquake activity and heating of the ground, suggesting that higher temperatures and steaming contributed to mechanical instabilities of the surface dome rocks. We examined relative amplitudes at station pairs and frequency contents to determine relative locations of the rockfalls by assuming that 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 there was a clear correlation between rockfalls, debris flows, and pyroclasic flows to the east (towards the camera) and high amplitudes and frequencies at east station AUE. Other events had high amplitudes and higher frequencies at west station AUW and no material was seen moving to the east. Still other events moved to the north and amplitudes were nearly the same at AUE and AUW. The systematic patterns in amplitude and frequency, verified by data from the low-light camera, make it possible to estimate mass flow in various directions using seismic data. Energy estimates of the rockfalls made from video images can be compared with energy estimates from magnitude-energy equations. The observer stations AUE and AUW show shifts in the frequency depending on whether the rockfalls are moving toward or away from them. Estimates of the seismic wave speeds from the rockfalls can be estimated using the Doppler equation, since the rockfalls are a moving frequency source. Also in progress is a program to estimate mass flow around the flanks of the volcano, using the amplitude ratios from stations around the volcano. The results from this work can be compared with geologic maps of deposits from the 2006 eruptions. The high rate of rockfalls in 2005 was also 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.

2007-12-01

261

Alaska Volcano Observatory at 20  

NASA Astrophysics Data System (ADS)

The Alaska Volcano Observatory (AVO) was established in 1988 in the wake of the 1986 Augustine eruption through a congressional earmark. Even within the volcanological community, there was skepticism about AVO. Populations directly at risk in Alaska were small compared to Cascadia, and the logistical costs of installing and maintaining monitoring equipment were much higher. Questions were raised concerning the technical feasibility of keeping seismic stations operating through the long, dark, stormy Alaska winters. Some argued that AVO should simply cover Augustine with instruments and wait for the next eruption there, expected in the mid 90s (but delayed until 2006), rather than stretching to instrument as many volcanoes as possible. No sooner was AVO in place than Redoubt erupted and a fully loaded passenger 747 strayed into the eruption cloud between Anchorage and Fairbanks, causing a powerless glide to within a minute of impact before the pilot could restart two engines and limp into Anchorage. This event forcefully made the case that volcano hazard mitigation is not just about people and infrastructure on the ground, and is particularly important in the heavily traveled North Pacific where options for flight diversion are few. In 1996, new funding became available through an FAA earmark to aggressively extend volcano monitoring far into the Aleutian Islands with both ground-based networks and round-the-clock satellite monitoring. Beyond the Aleutians, AVO developed a monitoring partnership with Russians volcanologists at the Institute of Volcanology and Seismology in Petropavlovsk-Kamchatsky. The need to work together internationally on subduction phenomena that span borders led to formation of the Japan-Kamchatka-Alaska Subduction Processes (JKASP) consortium. JKASP meets approximately biennially in Sapporo, Petropavlovsk, and Fairbanks. In turn, these meetings and support from NSF and the Russian Academy of Sciences led to new international education and research opportunities for Russian and American students. AVO was a three-way partnership of the federal and state geological surveys and the state university from the start. This was not a flowering of ecumenism but was rather at the insistence of the Alaska congressional delegation. Such shared enterprises are not managerially convenient, but they do bring a diversity of roles, thinking, and expertise that would not otherwise be possible. Through AVO, the USGS performs its federally mandated role in natural hazard mitigation and draws on expertise available from its network of volcano observatories. The Alaska Division of Geological and Geophysical Surveys performs a similar role at the state level and, in the tradition of state surveys, provides important public communications, state data base, and mapping functions. The University of Alaska Fairbanks brought seismological, remote sensing, geodetic, petrological, and physical volcanological expertise, and uniquely within US academia was able to engage students directly in volcano observatory activities. Although this "model" cannot be adopted in total elsewhere, it has served to point the USGS Volcano Hazards Program in a direction of greater openness and inclusiveness.

Eichelberger, J. C.

2008-12-01

262

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

263

Double Glacier Volcano, a `new' Quaternary volcano in the eastern Aleutian volcanic arc  

NASA Astrophysics Data System (ADS)

The Double Glacier Volcano (DGV) is a small dome complex of porphyritic hornblende andesite and dacite that is part of the Cook Inlet segment of Quaternary volcanoes of the eastern Aleutian arc. Its discovery reduces the previously described large volcano gap in Cook Inlet segment to a distance similar to that between other volcanoes in the area. DGV lavas are medium-K, calcalkaline andesites and dacites with concentrations of major and minor elements similar to the other Quaternary volcanoes of the Cook Inlet segment. Available K-Ar ages indicate that DGV was active 600 900 ka.

Reed, Bruce L.; Lanphere, Marvin A.; Miller, Thomas P.

1992-10-01

264

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

265

Combining relative and absolute gravity measurements to enhance volcano monitoring  

NASA Astrophysics Data System (ADS)

To achieve a balance between uncertainty and efficiency in gravity measurements, we have investigated the applicability of combined measurements of absolute and relative gravity as a hybrid method for volcano monitoring. Between 2007 and 2009, three hybrid gravity surveys were conducted at Mt Etna volcano, in June 2007, July 2008, and July 2009. Absolute gravity data were collected with two absolute gravimeters, which represent the state of the art in recent advances in ballistic gravimeter technology: (1) the commercial instrument FG5#238 and (2) the prototype instrument IMGC-02. We carried out several field surveys and confirmed that both the absolute gravimeters can still achieve a 10 ?Gal or better uncertainty even when they are operated in severe environmental conditions. The use of absolute gravimeters in a field survey of the summit area of Mt Etna is unprecedented. The annual changes of the gravity measured over 2007-2008 and 2008-2009 provide unequivocal evidence that during the 2007-2009 period, two main phenomena of subsurface mass redistribution occurred in distinct sectors of the volcano, accompanying different eruptive episodes. From 2007 to 2008, a gravity change of -60 ?Gal was concentrated around the North-East Rift. This coincided with a zone affected by strong extensional tectonics, and hence might have been related to the opening of new voids. Between 2008 and 2009, a North-South elongate feature with a maximum gravity change of +80 ?Gal was identified in the summit craters area. This is interpreted to indicate recharge of a deep-intermediate magma storage zone, which could have occurred when the 2008-2009 eruption was still ongoing.

Greco, F.; Currenti, G.; D'Agostino, G.; Germak, A.; Napoli, R.; Pistorio, A.; Del Negro, C.

2012-09-01

266

Venus - Volcanic Domes East of Beta Regio  

NASA Technical Reports Server (NTRS)

Two unusual volcanic domes are shown in this Magellan full-resolution mosaic. The image covers an area 180 by 240 kilometers (120 by 160 miles) centered at 18 degrees north latitude, 303.5 degrees east longitude, just east of Beta Regio. The dome in the south center of the image is about 45 kilometers (30 miles) across, with a 20 kilometer (13 mile) caldera, or volcanic collapse crater, in the center. The dome in the northwest corner of the image is about 30 kilometers (20 miles) across with a small (5 kilometer or 3 mile) summit crater. The very bright radar return from the western flank of this dome indicates that it has steep slopes. The flanks of the volcanoes display prominent gullies which may have been formed by slumping of surface material or thermal erosion by lava flows. Variations in the brightness with the surrounding plains show the extent of lava flows which originated at these volcanoes. Curved or bowed fractures surrounding the southern structure indicate that there has been subsidence, or sinking, of the dome following eruptive activity.

1991-01-01

267

Topics in Hydrogeology: Mud volcanoes and geysers  

E-print Network

et al. (2006) NASA, Voyager Enceladus Mars? Triton #12;What's Special About Lusi? · Observing;#12;#12;#12;#12;Field project · Multiparameter characterization of a geyser eruption (maybe a mud volcano?): T, IR, SP: Triggered earthquakes (Amanda, Chi) Week 13: Mud volcanoes on Mars (Edwin) Week 14: Field project Outline

Manga, Michael

268

Magnetotelluric Investigations of the Kilauea Volcano, Hawaii  

Microsoft Academic Search

A collaborative effort between Lawrence Berkeley National Laboratory, Sandia National Laboratories, Electromagnetic Instruments and the USGS Hawaiian Volcano Observatory has undertaken a three-dimensional (3D) magnetotelluric (MT) study of the Kilauea volcano in Hawaii. The survey objectives are 1): to produce a high quality 3D MT data set over the central caldera and the eastern and southwestern rift zones, 2) to

G. Hoversten; G. A. Newman; E. Gasperikova; J. P. Kauahikaua

2002-01-01

269

Geoflicks Reviewed--Films about Hawaiian Volcanoes.  

ERIC Educational Resources Information Center

Reviews 11 films on volcanic eruptions in the United States. Films are given a one- to five-star rating and the film's year, length, source and price are listed. Top films include "Inside Hawaiian Volcanoes" and "Kilauea: Close up of an Active Volcano." (AIM)

Bykerk-Kauffman, Ann

1994-01-01

270

Decision Analysis Tools for Volcano Observatories  

Microsoft Academic Search

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

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

2005-01-01

271

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

272

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

273

Thermal surveillance of active volcanoes. [infrared scanner recordings of thermal anomalies of Mt. Baker volcano  

NASA Technical Reports Server (NTRS)

The author has identified the following significant results. By the end of 1973, aerial infrared scanner traverses for thermal anomaly recordings of all Cascade Range volcanoes were essentially completed. Amplitude level slices of the Mount Baker anomalies were completed and compiled at a scale of 1:24,000, thus producing, for the first time, an accurate map of the distribution and intensity of thermal activity on Mount Baker. The major thermal activity is concentrated within the crater south of the main summit and although it is characterized by intensive solfataric activity and warm ground, it is largely subglacial, causing the development of sizable glacier perforation features. The outgoing radiative flux from the east breach anomalies is sufficient to account for the volume of ice melted to form the glacier perforations. DCP station 6251 has been monitoring a thermally anomalous area on the north slope of Mount Baker. The present thermal activity of Mount Baker accounts for continuing hydrothermal alteration in the crater south of the main summit and recurrent debris avalanches from Sherman Peak on its south rim. The infrared anomalies mapped as part of the experiment SR 251 are considered the basic evidence of the subglacial heating which was the probable triggering mechanism of an avalanche down Boulder Glacier on August 20-21, 1973.

Friedman, J. D. (principal investigator)

1974-01-01

274

ASTER Images Mt. Usu Volcano  

NASA Technical Reports Server (NTRS)

On April 3, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra Satellite captured this image of the erupting Mt. Usu volcano in Hokkaido, Japan. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image the Earth for the next 6 years to map and monitor the changing surface of our planet.

This false color infrared image of Mt Usu volcano is dominated by Lake Toya, an ancient volcanic caldera. On the south shore is the active Usu volcano. On Friday, March 31, more than 11,000 people were evacuated by helicopter, truck and boat from the foot of Usu, that began erupting from the northwest flank, shooting debris and plumes of smoke streaked with blue lightning thousands of feet in the air. Although no lava gushed from the mountain, rocks and ash continued to fall after the eruption. The region was shaken by thousands of tremors before the eruption. People said they could taste grit from the ash that was spewed as high as 2,700 meters (8,850 ft) into the sky and fell to coat surrounding towns with ash. 'Mount Usu has had seven significant eruptions that we know of, and at no time has it ended quickly with only a small scale eruption,' said Yoshio Katsui, a professor at Hokkaido University. This was the seventh major eruption of Mount Usu in the past 300 years. Fifty people died when the volcano erupted in 1822, its worst known eruption.

In the image, most of the land is covered by snow. Vegetation, appearing red in the false color composite, can be seen in the agricultural fields, and forests in the mountains. Mt. Usu is crossed by three dark streaks. These are the paths of ash deposits that rained out from eruption plumes two days earlier. The prevailing wind was from the northwest, carrying the ash away from the main city of Date. Ash deposited can be traced on the image as far away as 10 kilometers (16 miles) from the volcano.

Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. Science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface.

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

2000-01-01

275

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

276

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

277

The chronology of the martian volcanoes  

NASA Technical Reports Server (NTRS)

The volcanoes of Mars have been divided into three groups based on morphology: basaltic shields, domes and composite cones, and highland patera. A fourth group can be added to include the volcano-tectonic depressions. Using crater counts and the absolute chronology of Soderblom, an attempt is made to estimate the history of the volcanoes. Early in the martian history, about 2.5 b.y. ago, all three styles of volcanoes were active at various locations on the surface. At approximately 1.7-1.8 b.y. ago a transition occurred in the style and loci of volcanic construction. Volcanoes of younger age appear to be only of the basaltic shield group and are restricted to the Tharsis region. This same transition was noted by a change in the style of the basaltic shield group. Older shields were small low features, while the younger shields are significantly broader and taller.

Plescia, J. B.; Saunders, R. S.

1979-01-01

278

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

279

The "Plus Side" of Volcanoes  

NSDL National Science Digital Library

This web page provides a brief guide to the benefits of living with volcanoes. The topics considered are: Fertile Soils; Geothermal Energy with examples from Newberry Caldera in Oregon and in California, The Geysers, Casa Diablo in Long Valley Caldera, and the Salton Sea geothermal field; Mineral Resources including metallic minerals; Industrial Products including construction materials, cleaning agents, and raw materials for many chemical and industrial uses; Business Opportunities; Spas and Resorts; and Recreation and Tourism in America's national parks and monuments. Included among the parks are Yellowstone National Park, Mount Rainier National Park, and Mount St. Helens National Volcanic Monument.

280

Costa Rica's Chain of laterally collapsed volcanoes.  

NASA Astrophysics Data System (ADS)

From the NW extreme to the SW end of Costa Rica's volcanic backbone, a number of laterally collapsed volcanoes can be observed. Due to several factors, attention has been given to active volcanoes disregarding the importance of collapsed features in terms of assessing volcanic hazards for future generations around inhabited volcanoes. In several cases the typical horseshoe shape amphitheater-like depression can be easily observed. In other cases due to erosion, vegetation, topography, seismic activity or drastic weather such characteristics are not easily recognized. In the order mentioned above appear: Orosi-Cacao, Miravalles, Platanar, Congo, Von Frantzius, Cacho Negro and Turrialba volcanoes. Due to limited studies on these structures it is unknown if sector collapse occurred in one or several phases. Furthermore, in the few studied cases no evidence has been found to relate collapses to actual eruptive episodes. Detailed studies on the deposits and materials composing dome-like shapes will shed light on unsolved questions about petrological and chemical composition. Volume, form and distance traveled by deposits are part of the questions surrounding most of these collapsed volcanoes. Although most of these mentioned structures are extinct, at least Irazú volcano (active volcano) has faced partial lateral collapses recently. It did presented strombolian activity in the early 60s. Collapse scars show on the NW flank show important mass removal in historic and prehistoric times. Moreover, in 1994 a minor hydrothermal explosion provoked the weakening of a deeply altered wall that holds a crater lake (150m diameter, 2.6x106 ). A poster will depict images of the collapsed volcanoes named above with mayor descriptive characteristics. It will also focus on the importance of deeper studies to assess the collapse potential of Irazú volcano with related consequences. Finally, this initiative will invite researchers interested in such topic to join future studies in these Costarrican volcanoes.

Duarte, E.; Fernandez, E.

2007-05-01

281

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

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

1989-01-01

282

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

283

Three active volcanoes in China and their hazards  

Microsoft Academic Search

The active volcanoes in China are located in the Changbaishan area, Jingbo Lake, Wudalianchi, Tengchong and Yutian. Several of these volcanoes have historical records of eruption and geochronological evidence of Holocene activity. Tianchi Volcano is a well-preserved Cenozoic polygenetic central volcano, and, due to its recent history of powerful explosive eruptions of felsic magmas, with over 100,000 people living on

H. Wei; R. S. J. Sparks; R. Liu; Q. Fan; Y. Wang; H. Hong; H. Zhang; H. Chen; C. Jiang; J. Dong; Y. Zheng; Y. Pan

2003-01-01

284

The deep structure of Axial Volcano Michael West  

E-print Network

available on Web #12;The deep structure of Axial Volcano IV. Magma Reservoir beneath Axial Volcano AxialThe deep structure of Axial Volcano Michael West Thesis defense, June 4, 2001 #12;Motivation What at Axial may be interpreted (NeMO, Neptune) #12;The deep structure of Axial Volcano IV. Magma Reservoir

West, Michael

285

Mayon volcano, southeast Luzon, Philippines  

NASA Technical Reports Server (NTRS)

Mayon volcano is the most active volcano in the Philippines, located just north of the coastal town of Legaspi in southern Luzon about 325 km southeast of Manila. Mayon is a near-perfect cone; its steep, forested slopes look rather like a bull's eye when viewed from above. For scale, Mayon's circular footprint is about 16 km in diameter. This photograph was taken from the Space Shuttle on April 8, 1997. At the time the photo was taken, Mayon sported a steam plume from the summit. The lighter (non-forested) regions that radiate from the summit to the southern slopes are flows from eruptions that have occurred over the past twenty-five years. The current eruption, which started June 24, 2001, is sending flows down the southeast slope in the general direction of Legaspi. Image STS083-747-88 was provided by the by the Earth Sciences and Image Analysis Laboratory, Johnson Space Center. Additional images taken by astronauts and cosmonauts can be viewed at the NASA-JSC Gateway to Astronaut Photography of Earth.

2002-01-01

286

Seismic structure and origin of active intraplate volcanoes in Northeast Asia  

NASA Astrophysics Data System (ADS)

Three-dimensional P-wave velocity structure beneath the Changbai and other intraplate volcanic areas in Northeast Asia is determined by inverting 1378 high-quality P-wave arrival times from 186 teleseismic events recorded by 61 broadband seismic stations. Low-velocity (low-V) anomalies are revealed beneath the Changbai, Longgan, Xianjindao volcanoes. High-velocity (high-V) anomalies are found in the mantle transition zone, where deep-focus earthquakes under Hunchun occur at depths of 500-600 km. The high-V anomaly reflects the deep subduction of the Pacific slab under NE Asia which may have contributed to the formation of the Changbai, Longgang, Xianjindao and Jingpohu intraplate volcanoes. A low-V anomaly is also revealed in the mantle transition zone, which may have a close relationship with the occurrence of deep earthquakes under the Hunchun area. Our results support the Big Mantle Wedge (BMW) model by Zhao et al. [Zhao, D., Lei, J., Tang, Y., 2004. Origin of the Changbai volcano in northeast China: evidence from seismic tomography, Chin. Sci. Bull. 49, 1401-1408; Zhao, D., Maruyama, S., Omori, S., 2007. Mantle dynamics of western Pacific and East Asia: insight from seismic tomography and mineral physics. Gondwana Res. 11, 120-131.] who proposed that the intraplate volcanoes in NE Asia are caused by the back-arc magmatism associated with the deep dehydration process of the subducting slab and convective circulation process in the BMW above the stagnant Pacific slab.

Duan, Yonghong; Zhao, Dapeng; Zhang, Xiankang; Xia, Shaohong; Liu, Zhi; Wang, Fuyun; Li, Li

2009-05-01

287

Hydrogeological insights at Stromboli volcano (Italy) from geoelectrical, temperature, and CO2 soil degassing investigations  

NASA Astrophysics Data System (ADS)

Finding the geometry of aquifers in an active volcano is important for evaluating the hazards associated with phreato-magmatic phenomena and incidentally to address the problem of water supply. A combination of electrical resistivity tomography (ERT), self-potential, CO2, and temperature measurements provides insights about the location and pattern of ground water flow at Stromboli volcano. The measurements were conducted along a NE-SW profile across the island from Scari to Ginostra, crossing the summit (Pizzo) area. ERT data (electrode spacing 20 m, depth of penetration of ~200 m) shows the shallow architecture through the distribution of the resistivities. The hydrothermal system is characterized by low values of the resistivity (<50 ? m) while the surrounding rocks are resistive (>2000 ? m) except on the North-East flank of the volcano where a cold aquifer is detected at a depth of ~80 m (resistivity in the range 70-300 ? m). CO2 and temperature measurements corroborate the delineation of the hydrothermal body in the summit part of the volcano while a negative self-potential anomaly underlines the position of the cold aquifer.

Finizola, A.; Revil, A.; Rizzo, E.; Piscitelli, S.; Ricci, T.; Morin, J.; Angeletti, B.; Mocochain, L.; Sortino, F.

2006-09-01

288

Analysis of Vulnerability Around The Colima Volcano, MEXICO  

NASA Astrophysics Data System (ADS)

The Colima volcano located in the western of the Trasmexican Volcanic Belt, in the central portion of the Colima Rift Zone, between the Mexican States of Jalisco and Colima. The volcano since January of 1998 presents a new activity, which has been characterized by two stages: the first one was an effusive phase that begin on 20 November 1998 and finish by the middle of January 1999. On February 10of 1999 a great explosion in the summit marked the beginning of an explosive phase, these facts implies that the eruptive process changes from an effusive model to an explosive one. Suárez-Plascencia et al, 2000, present hazard maps to ballistic projectiles, ashfalls and lahars for this scenario. This work presents the evaluation of the vulnerability in the areas identified as hazardous in the maps for ballistic, ashfalls and lahars, based on the economic elements located in the middle and lower sections of the volcano building, like agriculture, forestry, agroindustries and communication lines (highways, power, telephonic, railroad, etc). The method is based in Geographic Information Systems, using digital cartography scale 1:50,000, digital orthophotos from the Instituto Nacional de Estadística, Geografía e Informática, SPOT and Landsat satellite images from 1997 and 2000 in the bands 1, 2 and 3. The land use maps obtained for 1997 and 2000, were compared with the land use map reported by Suárez in 1992, from these maps an increase of the 5 porcent of the sugar cane area and corn cultivations were observed compared of those of 1990 (1225.7 km2) and a decrease of the forest surface, moving the agricultural limits uphill, and showing also some agave cultivation in the northwest and north hillslopes of the Nevado de Colima. This increment of the agricultural surface results in bigger economic activity in the area, which makes that the vulnerability also be increased to different volcanic products emitted during this phase of activity. The degradation of the soil by the agriculture and forestry, mainly in the east hillslope of the volcano is another factor that generate remoulded material that in the event of an extraordinary rainsfall during an explosive events, could increase the size of the lahar or generate flows of mud that may affect the towns, villages (like Atenquique, which has been affected in 1957 by a large lahar), and could generate strong damages to the communication lines affecting distant places as Guadalajara city and the Port of Manzanillo.

Carlos, S. P.

2001-12-01

289

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

USGS Publications Warehouse

As magma moves toward the surface, it interacts with anything in its path: hydrothermal systems, cooling magma bodies from previous eruptions, and (or) the surrounding 'country rock'. Magma also undergoes significant changes in its physical properties as pressure and temperature conditions change along its path. These interactions and changes lead to a range of geophysical and geochemical phenomena. The goal of volcano monitoring is to detect and correctly interpret such phenomena in order to provide early and accurate warnings of impending eruptions. Given the well-documented hazards posed by volcanoes to both ground-based populations (for example, Blong, 1984; Scott, 1989) and aviation (for example, Neal and others, 1997; Miller and Casadevall, 2000), volcano monitoring is critical for public safety and hazard mitigation. Only with adequate monitoring systems in place can volcano observatories provide accurate and timely forecasts and alerts of possible eruptive activity. At most U.S. volcanoes, observatories traditionally have employed a two-component approach to volcano monitoring: (1) install instrumentation sufficient to detect unrest at volcanic systems likely to erupt in the not-too-distant future; and (2) once unrest is detected, install any instrumentation needed for eruption prediction and monitoring. This reactive approach is problematic, however, for two reasons. 1. At many volcanoes, rapid installation of new ground-1. based instruments is difficult or impossible. Factors that complicate rapid response include (a) eruptions that are preceded by short (hours to days) precursory sequences of geophysical and (or) geochemical activity, as occurred at Mount Redoubt (Alaska) in 1989 (24 hours), Anatahan (Mariana Islands) in 2003 (6 hours), and Mount St. Helens (Washington) in 1980 and 2004 (7 and 8 days, respectively); (b) inclement weather conditions, which may prohibit installation of new equipment for days, weeks, or even months, particularly at midlatitude or high-latitude volcanoes; (c) safety factors during unrest, which can limit where new instrumentation can safely be installed (particularly at near-vent sites that can be critical for precursor detection and eruption forecasting); and (d) the remoteness of many U.S. volcanoes (particularly those in the Aleutians and the Marianas Islands), where access is difficult or impossible most of the year. Given these difficulties, it is reasonable to anticipate that ground-based monitoring of eruptions at U.S. volcanoes will likely be performed primarily with instruments installed before unrest begins. 2. Given a growing awareness of previously undetected 2. phenomena that may occur before an eruption begins, at present the types and (or) density of instruments in use at most U.S. volcanoes is insufficient to provide reliable early warning of volcanic eruptions. As shown by the gap analysis of Ewert and others (2005), a number of U.S. volcanoes lack even rudimentary monitoring. At those volcanic systems with monitoring instrumentation in place, only a few types of phenomena can be tracked in near-real time, principally changes in seismicity, deformation, and large-scale changes in thermal flux (through satellite-based remote sensing). Furthermore, researchers employing technologically advanced instrumentation at volcanoes around the world starting in the 1990s have shown that subtle and previously undetectable phenomena can precede or accompany eruptions. Detection of such phenomena would greatly improve the ability of U.S. volcano observatories to provide accurate early warnings of impending eruptions, and is a critical capability particularly at the very high-threat volcanoes identified by Ewert and others (2005). For these two reasons, change from a reactive to a proactive volcano-monitoring strategy is clearly needed at U.S. volcanoes. Monitoring capabilities need to be expanded at virtually every volcanic center, regardless of its current state of

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

2008-01-01

290

Volcano-tectonic modelling of magma chambers, ring-faults, unrest, and eruptions in the Tianchi Volcano, China  

E-print Network

Volcano-tectonic modelling of magma chambers, ring-faults, unrest, and eruptions in the Tianchi Volcano, China Supervisor: Agust Gudmundsson Project Description: The Tianchi (Changbaishan) Volcano, located at the boundary between China and North Korea, is widely regarded as the most dangerous volcano

Sheldon, Nathan D.

291

Shallow Plumbing Systems for Small-Volume Basaltic Volcanoes  

NASA Astrophysics Data System (ADS)

We characterize 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 5 basaltic volcanoes with varying degrees of erosion exposing feeder dikes, conduits, and vent areas <250 m depth. Study areas include East Grants Ridge (New Mexico), Basalt Ridge, East Basalt Ridge, Paiute Ridge, and Southeast Crater Flat (Nevada). Basaltic feeder dikes ~250 to 100 m deep have typical widths of 4 - 12 m, with smooth host-rock contacts (rhyolite tuff). At depths <100 m, heterogeneities in the host rock form preferential pathways for small dike splays and sills, resulting in a 30-m effective width at 50 m depth. The development of a complex conduit above ~50-70 m depth is reflected in bifurcating dikes and brecciation and stoping of the country rock. The overall zone of effect <50 m depth is <110 m wide (220 m elongated along the feeder dike). Based on comparisons with theoretical conduit flow models, the width of the feeder dike from 250 to 500 m depth is expected to range from 1 to 10 m and is expected to decrease to about 1-2 meters below ~500 m. The flaring shape of the observed feeder systems is similar to results of theoretical modeling using lithostatic pressure- balanced flow conditions. Sizes of observed conduits differ from modeled dimensions by up to a factor of 10 in the shallow (<50 m) subsurface, but >100 m depth the difference is a factor of two to five. This difference is primarily due to the fact that observed eroded conduits record the superimposed effects of multiple eruptive events while theoretical model results define dimensions necessary for a single, steady eruption phase. The complex details of magma-host rock interactions observed at the study areas (contact welding, brecciation, bifurcating dikes and sills, and stoping) represent the mechanisms by which the lithostatic pressure-balanced geometry is attained. The similarity in the normalized shapes of theoretical and observed conduits demonstrates the appropriateness of the pressure-balanced modeling approach, validating the conclusions of Wilson and Head (1981) for this type of volcano.

Keating, G. N.; Valentine, G. A.; Krier, D. J.; Perry, F. V.

2006-12-01

292

Unzipping of the volcano arc, Japan  

NASA Astrophysics Data System (ADS)

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) structural elements of the Mariana Trough extend north to the southern Volcano Arc. (2) both the Mariana Trough and frontal arc shoal rapidly northwards as the Volcano Arc is approached. (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.

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

1984-02-01

293

Lahar Hazards at Concepción volcano, Nicaragua  

USGS Publications Warehouse

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

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

2001-01-01

294

Eruption of Shiveluch Volcano, Kamchatka Peninsula  

NASA Technical Reports Server (NTRS)

On March 29, 2007, the Shiveluch Volcano on the Russian Federation's Kamchatka Peninsula erupted. According to the Alaska Volcano Observatory the volcano underwent an explosive eruption between 01:50 and 2:30 UTC, sending an ash cloud skyward roughly 9,750 meters (32,000 feet), based on visual estimates. The Moderate Resolution Imaging Spectroradiometer (MODIS) flying onboard NASA's Aqua satellite took this picture at 02:00 UTC on March 29. The top image shows the volcano and its surroundings. The bottom image shows a close-up view of the volcano at 250 meters per pixel. Satellites often capture images of volcanic ash plumes, but usually as the plumes are blowing away. Plumes have been observed blowing away from Shiveluch before. This image, however, is different. At the time the Aqua satellite passed overhead, the eruption was recent enough (and the air was apparently still enough) that the ash cloud still hovered above the summit. In this image, the bulbous cloud casts its shadow northward over the icy landscape. Volcanic ash eruptions inject particles into Earth's atmosphere. Substantial eruptions of light-reflecting particles can reduce temperatures and even affect atmospheric circulation. Large eruptions impact climate patterns for years. A massive eruption of the Tambora Volcano in Indonesia in 1815, for instance, earned 1816 the nickname 'the year without a summer.' Shiveluch is a stratovolcano--a steep-sloped volcano composed of alternating layers of solidified ash, hardened lava, and volcanic rocks. One of Kamchatka's largest volcanoes, it sports a summit reaching 3,283 meters (10,771 feet). Shiveluch is also one of the peninsula's most active volcanoes, with an estimated 60 substantial eruptions in the past 10,000 years.

2007-01-01

295

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_.

296

Lava Sampling on Kilauea Volcano, Hawaii  

NSDL National Science Digital Library

This video segment shows how scientists collaborate to collect and chemically analyze samples of molten lava as part of their quest to learn more about how volcanoes work. Working at Kilauea volcano, scientists collect samples of lava before it has a chance to cool so they can study the chemical properties it had when it was deep within Earth's interior. The samples are sent to a laboratory where other scientists determine their chemical compositions. Questions such as whether two volcanoes share a common magma source can be answered through such analyses. The segment is five minutes forty-seven seconds in length. A background essay and list of discussion questions are also provided.

2011-02-24

297

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

USGS Publications Warehouse

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

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

2008-01-01

298

Volcanoes  

MedlinePLUS

... is a vent in the Earth's crust. Hot rock, steam, poisonous gases, and ash reach the Earth's ... can also cause earthquakes, mudflows and flash floods, rock falls and landslides, acid rain, fires, and even ...

299

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

300

How Volcanoes Work: Historical Eruptions  

NSDL National Science Digital Library

This information about major volcanic eruptions in history covers events from the civilization-destroying explosion at Santorini in about 1630 BC, to the killing cloud of carbon dioxide at Lake Nyos Cameroon in 1986. The site documents the seven deadliest eruptions in history. Other eruptions include Mount Pelee on the island of Martinique in 1902, Mount Saint Helens in Washington State in 1980, Nevado Del Ruiz Columbia in 1985, the Mexican eruption of Paricutin in 1943, and the 1883 explosion that nearly obliterated the island of Krakatau in what is now Indonesia. For each eruption the site offers information about the type of volcano, the type of eruption, the products of the eruption, and the relation to plate tectonics. In addition, historical background is provided when appropriate.

Camp, Victor

301

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

302

Wide Angle View of Arsia Mons Volcano  

NASA Technical Reports Server (NTRS)

Arsia Mons (above) is one of the largest volcanoes known. This shield volcano is part of an aligned trio known as the Tharsis Montes--the others are Pavonis Mons and Ascraeus Mons. Arsia Mons is rivaled only by Olympus Mons in terms of its volume. The summit of Arsia Mons is more than 9 kilometers (5.6 miles) higher than the surrounding plains. The crater--or caldera--at the volcano summit is approximately 110 km (68 mi) across. This view of Arsia Mons was taken by the red and blue wide angle cameras of the Mars Global Surveyor Mars Orbiter Camera (MOC) system. Bright water ice clouds (the whitish/bluish wisps) hang above the volcano--a common sight every martian afternoon in this region. Arsia Mons is located at 120o west longitude and 9o south latitude. Illumination is from the left.

1999-01-01

303

Lahar hazards at Mombacho Volcano, Nicaragua  

USGS Publications Warehouse

Mombacho volcano, at 1,350 meters, is situated on the shores of Lake Nicaragua and about 12 kilometers south of Granada, a city of about 90,000 inhabitants. Many more people live a few kilometers southeast of Granada in 'las Isletas de Granada and the nearby 'Peninsula de Aseses. These areas are formed of deposits of a large debris avalanche (a fast moving avalanche of rock and debris) from Mombacho. Several smaller towns with population, in the range of 5,000 to 12,000 inhabitants are to the northwest and the southwest of Mombacho volcano. Though the volcano has apparently not been active in historical time, or about the last 500 years, it has the potential to produce landslides and 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. -- Vallance, et.al., 2001

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

2001-01-01

304

Natural Resources Canada: Volcanoes of Canada  

NSDL National Science Digital Library

Natural Resources Canada has launched yet another impressive and educational Web site. At this site you can learn all you wanted to know about Canadian volcanoes and volcanology. The site offers an introduction to volcanoes, in-depth sections on types, eruptions, hazards, and risks. You can also discover interesting facts, such as how eruptions in Alaska and the Western coast of the US impact agriculture and air travel in Canada. In addition to text, the site offers a wonderful interactive Map of Canadian Volcanoes. The Catalogue of Canadian Volcanoes is also an excellent reference tool. Available in English and French, this site is easy to understand and ideal for science students as well as anyone interested in volcanology. This site is also reviewed in the August 22, 2003 NSDL Physical Sciences Report.

305

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

306

Petrology of lavas from the Puu Oo eruption of Kilauea Volcano: III. The Kupaianaha episode (1986–1992)  

Microsoft Academic Search

The Puu Oo eruption has been remarkable in the historical record of Kilauea Volcano for its duration (over 13 years), volume\\u000a (>1?km3) and compositional variation (5.7–10?wt.% MgO). During the summer of 1986, the main vent for lava production moved 3?km down\\u000a the east rift zone and the eruption style changed from episodic geyser-like fountaining at Puu Oo to virtually continuous,

Michael O. Garcia; J. M. Rhodes; Frank A. Trusdell; Aaron J. Pietruszka

1996-01-01

307

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

308

Evolution of large shield volcanoes on Venus  

NASA Technical Reports Server (NTRS)

We studied the geologic history, topographic expression, and gravity signature of 29 large Venusian shield volcanoes with similar morphologies in Magellan synthetic aperture radar imagery. While they appear similar in imagery, 16 have a domical topographic expression and 13 have a central depression. Typical dimensions for the central depression are 150 km wide and 500 m deep. The central depressions are probably not calderas resulting from collapse of a shallow magma chamber but instead are the result of a corona-like sagging of a previously domical volcano. The depressions all have some later volcanic filling. All but one of the central depression volcanoes have been post-dated by geologic features unrelated to the volcano, while most of the domical volcanoes are at the top of the stratigraphic column. Analysis of the gravity signatures in the spatial and spectral domains shows a strong correlation between the absence of post-dating features and the presence of dynamic support by an underlying plume. We infer that the formation of the central depressions occurred as a result of cessation of dynamic support. However, there are some domical volcanoes whose geologic histories and gravity signatures also indicate that they are extinct, so sagging of the central region apparently does not always occur when dynamic support is removed. We suggest that the thickness of the elastic lithosphere may be a factor in determining whether a central depression forms when dynamic support is removed, but the gravity data are of insufficient resolution to test this hypothesis with admittance methods.

Herrick, Robert R.; Dufek, Josef; McGovern, Patrick J.

2005-01-01

309

Ambient Noise Tomography at Bezymianny Volcano, Kamchatka  

NASA Astrophysics Data System (ADS)

Bezymianny Volcano is an active stratovolcano located in the Kluychevskoy volcanic group on the Kamchatka Peninsula in eastern Russia. Since its dramatic sector collapse eruption in 1956, the volcano's activity has been characterized by nearly twice annual plinian eruptions accompanying ongoing lava-dome growth. Its frequent eruptions and similarity to Mt. St. Helens have made it the target of a multifaceted geologic and geophysical project supported by the NSF Partners in Research and Education (PIRE) program. Since mid- 2006, the volcano has been monitored by a broadband seismic array that is currently composed of 8 stations within 10 kilometers of the active dome. In this project, we use continuous data from these stations to investigate the static and dynamic structure of the volcano. Using methods similar to those used by Brenguier et al. (2007, 2008), we estimate the Green's function for each pair of stations by cross-correlating day-long time series of ambient noise. Paths with high signal-to-noise ratios can be used to estimate group velocity dispersion curves. From these measurements, we work towards constructing the first velocity model of this volcano. Furthermore, we begin to test whether measurements of ambient noise can be used to monitor changes inside the volcano prior to eruptive activity. These problems will continue to be addressed as more data becomes available in future field seasons.

Shuler, A. E.; Ekström, G.; West, M.; Senyukov, S.

2008-12-01

310

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

311

Interagency collaboration on an active volcano: a case study at Hawai‘i Volcanoes National Park  

USGS Publications Warehouse

Hawai‘i Volcanoes National Park (HAVO) includes two active Hawai‘i shield volcanoes – Mauna Loa, the largest active volcano on earth that most recently erupted for three weeks in 1984, and K?lauea, which has been erupting continuously for more than 31 years. Unlike the steep-sided volcanoes around the rim of the Pacific Ocean, all Hawaiian volcanoes have gentle-sloped flanks that result from copious eruptions of fluid lavas with infrequent interludes of explosive activity. Each of the Hawaiian volcanoes erupts from its summit area – K?lauea and Mauna Loa both have summit calderas (large subsided craters)—and from one or more rift zones (a sequence of vents aligned radially away from the summit). Because Kilauea and Mauna Loa are included within the National Park, there is a natural intersection of missions for the National Park Service (NPS) and the U.S. Geological Survey (USGS). HAVO staff and the USGS Hawaiian Volcano Observatory scientists have worked closely together to monitor and forecast multiple eruptions from each of these volcanoes since HAVO’s founding in 1916.

Kauahikaua, James P.; Orlando, Cindy

2014-01-01

312

An Admittance Survey of Large Volcanoes on Venus: Implications for Volcano Growth  

NASA Technical Reports Server (NTRS)

Estimates of the thickness of the venusian crust and elastic lithosphere are important in determining the rheological and thermal properties of Venus. These estimates offer insights into what conditions are needed for certain features, such as large volcanoes and coronae, to form. Lithospheric properties for much of the large volcano population on Venus are not well known. Previous studies of elastic thickness (Te) have concentrated on individual or small groups of edifices, or have used volcano models and fixed values of Te to match with observations of volcano morphologies. In addition, previous studies use different methods to estimate lithospheric parameters meaning it is difficult to compare their results. Following recent global studies of the admittance signatures exhibited by the venusian corona population, we performed a similar survey into large volcanoes in an effort to determine the range of lithospheric parameters shown by these features. This survey of the entire large volcano population used the same method throughout so that all estimates could be directly compared. By analysing a large number of edifices and comparing our results to observations of their morphology and models of volcano formation, we can help determine the controlling parameters that govern volcano growth on Venus.

Brian, A. W.; Smrekar, S. E.; Stofan, E. R.

2004-01-01

313

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

E-print Network

Available online xxx Keywords: Dashgil mud volcano Azerbaijan Dormant Methane Water geochemistry a b s t r continuously leaking deep- seated reservoirs underneath the mud volcano, with minimal oxidation during suggesting a deep-seated water source. These results demonstrate that the plumbing system of dormant mud

Svensen, Henrik

314

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

315

Update of map the volcanic hazard in the Ceboruco volcano, Nayarit, Mexico  

NASA Astrophysics Data System (ADS)

The Ceboruco Volcano (21° 7.688 N, 104° 30.773 W) is located in the northwestern part of the Tepic-Zacoalco graben. Its volcanic activity can be divided in four eruptive cycles differentiated by their VEI and chemical variations as well. As a result of andesitic effusive activity, the "paleo-Ceboruco" edifice was constructed during the first cycle. The end of this cycle is defined by a plinian eruption (VEI between 3 and 4) which occurred some 1020 years ago and formed the external caldera. During the second cycle an andesitic dome built up in the interior of the caldera. The dome collapsed and formed the internal caldera. The third cycle is represented by andesitic lava flows which partially cover the northern and south-southwestern part of the edifice. The last cycle is represented by the andesitic lava flows of the nineteenth century located in the southwestern flank of the volcano. Actually, moderate fumarolic activity occurs in the upper part of the volcano showing temperatures ranging between 20° and 120°C. Some volcanic high frequency tremors have also been registered near the edifice. Shows the updating of the volcanic hazard maps published in 1998, where we identify with 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 sides of the Ceboruco volcano. The population inhabiting the area is 70,224 people in 2010, concentrated in 107 localities and growing at an annual rate of 0.37%, also the region that has shown an increased in the vulnerability for the development of economic activities, supported by highway, high road, railroad, and the construction of new highway to Puerto Vallarta, which is built in the southeast sector of the volcano and electrical infrastructure that connect the Cajon and Yesca Dams to Guadalajara city. The most important economic activity in the area is agriculture, with crops of sugar cane (Saccharum officinarum), corn, and jamaica (Hibiscus sabdariffa). Recently it has established tomato and green pepper crops in greenhouses. The regional commercial activities are concentrated in the localities of Ixtlán, Jala and Ahuacatlán. The updated hazard maps are: a) Hazard map of 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 Ceboruco Volcano by the State Civil & Fire Protection Unit of Nayarit, 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.; Camarena-Garcia, M. A.; Nunez-Cornu, F. J.

2012-12-01

316

Modeling eruptions of Karymsky volcano  

E-print Network

A model is proposed to explain temporal patterns of activity in a class of periodically exploding Strombolian-type volcanos. These patterns include major events (explosions) which follow each other every 10-30 minutes and subsequent tremor with a typical period of 1 second. This two-periodic activity is thought to be caused by two distinct mechanisms of accumulation of the elastic energy in the moving magma column: compressibility of the magma in the lower conduit and viscoelastic response of the almost solid magma plug on the top. A release of the elastic energy happens when a stick-slip dynamic phase transition in a boundary layer along the walls of the conduit occurs; this phase transition is driven by the shear stress accumulated in the boundary layer. The first-order character and intrinsic hysteresis of this phase transition explains the long periods of inactivity in the explosion cycle. Temporal characteristics of the model are found to be qualitatively similar to the acoustic and seismic signals recor...

Ozerov, A; Lees, J

2001-01-01

317

Quantifying the Role of Cloud Water in the Hydrology of Two Montane Forest Sites on East Maui, Hawaii  

Microsoft Academic Search

East Maui (Haleakala volcano) rises 3054 m above the ocean, and clouds intercepting the mountain slopes are an integral part of the climate. To what extent do the trees and shrubs on the mountainsides extract cloud water that contributes to soil moisture, groundwater recharge, and stream flow in the watersheds? Two sites, on the windward and leeward sides of the

M. A. Scholl; S. B. Gingerich; T. W. Giambelluca; M. A. Nullet; L. L. Loope

2003-01-01

318

EGGERTJOHANNESSON/AP Iceland's Brarbunga volcano erupted on  

E-print Network

EGGERTJOHANNESSON/AP Iceland's B�r�arbunga volcano erupted on 29 August, spurting lava out of a 1 been emitted. But halfway around the world, the Rabaul volcano in Papua New Guinea spewed ash on 29

Napp, Nils

319

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

320

The youngest eruptions and edifice collapse of Iriga volcano, Philippines  

E-print Network

The youngest eruptions and edifice collapse of Iriga volcano, Philippines Alexander Belousov 1 of Volcanology and Seismology, Petropavlovsk, Russia, 3 ­ University of Philippines Iriga volcano has a prominent

Belousov, Alexander

321

Space Radar Image of Rabaul Volcano, New Guinea  

NASA Technical Reports Server (NTRS)

This is a radar image of the Rabaul volcano on the island of New Britain, Papua, New Guinea taken almost a month after its September 19, 1994, eruption that killed five people and covered the town of Rabaul and nearby villages with up to 75 centimeters (30 inches) of ash. More than 53,000 people have been displaced by the eruption. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on its 173rd orbit on October 11, 1994. This image is centered at 4.2 degrees south latitude and 152.2 degrees east longitude in the southwest Pacific Ocean. The area shown is approximately 21 kilometers by 25 kilometers (13 miles by 15.5 miles). North is toward the upper right. The colors in this image were obtained using the following radar channels: red represents the L-band (horizontally transmitted and received); green represents the L-band (horizontally transmitted and vertically received); blue represents the C-band (horizontally transmitted and vertically received). Most of the Rabaul volcano is underwater and the caldera (crater) creates Blanche Bay, the semi-circular body of water that occupies most of the center of the image. Volcanic vents within the caldera are visible in the image and include Vulcan, on a peninsula on the west side of the bay, and Rabalanakaia and Tavurvur (the circular purple feature near the mouth of the bay) on the east side. Both Vulcan and Tavurvur were active during the 1994 eruption. Ash deposits appear red-orange on the image, and are most prominent on the south flanks of Vulcan and north and northwest of Tavurvur. A faint blue patch in the water in the center of the image is a large raft of floating pumice fragments that were ejected from Vulcan during the eruption and clog the inner bay. Visible on the east side of the bay are the grid-like patterns of the streets of Rabaul and an airstrip, which appears as a dark northwest-trending band at the right-center of the image. Ashfall and subsequent rains caused the collapse of most buildings in the town of Rabaul. Mudflows and flooding continue to pose serious threats to the town and surrounding villages. Volcanologists and local authorities expect to use data such as this radar image to assist them in identifying the mechanisms of the eruption and future hazardous conditions that may be associated with the vigorously active volcano. Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves, allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those changes which are induced by human activity. SIR-C was developed by NASA's Jet Propulsion Laboratory. X-SAR was developed by the Dornier and Alenia Spazio companies for the German space agency, Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA), and the Italian space agency, Agenzia Spaziale Italiana (ASI), with the Deutsche Forschungsanstalt fuer Luft und Raumfahrt e.v.(DLR), the major partner in science, operations and data processing of X-SAR.

1994-01-01

322

The First Historical Eruption of Anatahan Volcano, Mariana Islands  

NASA Astrophysics Data System (ADS)

The first historical eruption of Anatahan volcano occurred on May 10, 2003. The MARGINS office responded by authorizing helicopter surveillance and ship deployment to visit the volcano. The helicopter flight on May 19 allowed visual observations and identification of the east crater as the source of the eruption. The top of the plume was estimated to be at 10,000 ft - significantly less than the 30,000 ft of the initial blast. No bombs were ejected out of the east crater at this time but were falling back into the crater. The bombs looked irregular in shape, massive and were estimated to be a few m in diameter. Bombs and tephra samples were collected from the eastern side of the island when blasts were occurring at a rate of approx. 1 per 5min. The ship visit followed on May 21 to the western side of the island for collection of samples and SO2 flux measurements, along with maintenance of a previously deployed seismometer. Volcanic samples collected on Anatahan consisted of bombs, ash and scoria from the present eruption and old lavas (age unknown). The ash section on the western shore was 25 cm thick and consisted of the following sequence (bottom to top): 0-5 inversely? graded dark ash with scoria and pumice clasts (1-2 cm), 20-25 cm: well sorted clast-supported scoria (max 2 cm) with some fine ash. The maximum total thickness measured at a site 6 km from the east crater was approximately 45 cm. The sequence is interpreted as 1) initial blast 2) interaction of magma with water (from pre-existing hydrothermal system) as evidenced by accretionary lapilli 3) magmatic phase of the eruption producing juvenile material. Electron microprobe analyses of the pumice and scoria show uniform compositions of ~ 60wt% SiO2 in the glass; zoned plagioclase with average composition of 61% An, 37.7% Ab, 1.2% Or; pyroxenes (19.4% Wo, 53.4% En, 26.7% Fs) and Fe-Ti oxides. Sulfur and Cl contents are approx. 100 and 1500 ppm, respectively. Water content of the glass may be several wt% based on analytical totals. Volatile emissions from the volcano were measured by traversing under the plume with a ship-based COSPEC. Using wind speed data from NOAA (10-15 knots on May 21), we estimate the daily SO2 flux to be 3000 - 4500 tons. Our observations are consistent with the idea that the initial phreatic eruption evolved rapidly into a magmatic phase producing juvenile (and vesicular) material accompanied by a high SO2 flux. Details on the eruption products, chemical analyses, seismic measurements, and current monitoring efforts can be found in accompanying posters.

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

2003-12-01

323

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

324

Predicting The Timing And Location of the Next Hawaiian Volcano  

NSDL National Science Digital Library

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 included in which students use their own calculations to predict when the next volcano on the Kea trend should appear.

Russo, Joseph; Mattox, Stephen; Kidau, Nicole

2010-01-01

325

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

326

The absence of diffuse degassing at Popocatépetl volcano, Mexico  

Microsoft Academic Search

Soil gas or flux measurements have shown that many active volcanoes release significant volumes of magmatic gas through their flanks. This type of measurement represents a useful and safer method (compared with direct fumarole measurements) for monitoring an active volcano. However, this study shows that not all volcanoes will have a significant diffuse component, even if substantial quantities of gas

N. R Varley; M. A Armienta

2001-01-01

327

PUBLICATIONS OF THE VOLCANO HAZARDS PROGRAM 1999-2003  

E-print Network

PUBLICATIONS OF THE VOLCANO HAZARDS PROGRAM 1999-2003 2003 UNITED STATES DEPARTMENT OF THE INTERIOR UNITED STATES GEOLOGICAL SURVEY #12;2 The Volcano Hazards Program of the U.S. Geological Survey (USGS;3 Volcano Hazards Bibliography 1999-2003 Adleman, Jennifer, 2002, The great eruption of 1912: Alaska Park

Torgersen, Christian

328

REDUCING THE RISK FROM VOLCANO HAZARDS UNITED STATES GEOLOGICAL SURVEY  

E-print Network

REDUCING THE RISK FROM VOLCANO HAZARDS UNITED STATES GEOLOGICAL SURVEY VolcanicAsh--Danger toAircraft intheNorthPacific The world's busy air traffic corridors pass over hundreds of volcanoes ca- pable and millions of dollars of cargo over volcanoes each day. Volcanic ash can be a serious hazard to aviation even

Torgersen, Christian

329

Global Volcano Total Economic Loss Risk Distribution Projection: Robinson  

E-print Network

Global Volcano Total Economic Loss Risk Distribution Projection: Robinson Total Economic Loss is found by weighting the value of GDP exposure to volcanoes for each grid cell by a vulnerability International Bank for Reconstruction and Development/The World Bank and Columbia University. Volcano Total

Columbia University

330

Global Volcano Proportional Economic Loss Risk Distribution Projection: Robinson  

E-print Network

Global Volcano Proportional Economic Loss Risk Distribution Projection: Robinson Like Total to volcanoes for each grid cell by a vulnerability coefficient to obtain an estimate of risk. The vulnerability Analysis. Washington, D.C.: World Bank. Source: Volcano Proportional Economic Loss Risk Deciles 1 st ­4 th

Columbia University

331

Historical 3D Topographic Reconstruction of the Iwaki Volcano  

E-print Network

Historical 3D Topographic Reconstruction of the Iwaki Volcano using Structure from Motion from of topographiy that may change drastically in a short-time such as volcanoes. Precise topographic data is testing the technique at the Iwaki volcano in Northern Honshu in Japan, using a series of historical

Paris-Sud XI, Université de

332

ARTICLE IN PRESS Volcano geodesy and magma dynamics in Iceland  

E-print Network

ARTICLE IN PRESS Volcano geodesy and magma dynamics in Iceland Erik Sturkell a,*, Pa´ll Einarsson b 7, 101 Reykjavi´k, Iceland d Volcano Dynamics Group, Department of Earth Sciences, The Open; received in revised form 19 December 2004 Abstract Here we review the achievements of volcano geodesy

Pedersen, Rikke

333

A Global Volcano Product for Thermal Emission and Effusion Rate  

E-print Network

A Global Volcano Product for Thermal Emission and Effusion Rate: Hyperion;Overview · EO-1 Volcano Sensorweb ­ Uses in-situ, other satellite, and hybrid sources to task EO-1 to acquire imagery of acGve volcanoes ­ Automated processing workflows

Schaffer, Steven

334

Monitoring Volcanic Activity at Reventador Volcano, Ecuador with a  

E-print Network

Monitoring Volcanic Activity at Reventador Volcano, Ecuador with a Wireless Sensor Network Geoff of the erupting volcano Automatic triggering to download data following seismic events Tested sophisticated data.g., tomography -- image interior of volcano using wave arrivals at many locations #12;© 2005 Matt Welsh ­ Harvard

Chen, Yiling

335

Margins Volcanoes Field Trip July 2001 Nicaragua Michael J. Carr  

E-print Network

-Masaya is a highly explosive shield volcano/caldera complex with the world's highest 10 Be/9 Be. Its volume of about of the caldera. The Apoyo caldera may have been preceded by a low shield volcano (Sussman (1982). GeographicallyMargins Volcanoes Field Trip July 2001 Nicaragua Michael J. Carr Image taken from INETER web site

336

What's this volcano trying to tell us? by Daniel Pendick  

E-print Network

. There's danger in the air too: the volcano's dark cone looms over nearby towns and villages, and has in the boiling hearts of volcanoes that show, for example, whether a river of fresh magma charged with explosive debris into the air. But infrasound also comes from the very heart of a volcano, produced

Buckingham, Michael

337

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

338

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

339

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

340

Turrialba volcano: awaking indications of possible unrest  

NASA Astrophysics Data System (ADS)

Based on historical descriptions and reports, Turrialba volcano has presented events like incandescence, SO2 combustion, phreatic eruptions, that preceded the only historical magmatic eruption (1864-1866), this VEI value 2 eruption covered a surface area of 3400 km2, successively the volcano enter in a period of calm. During most of the 80's and 90's the volcano was under low seismic activity and low temperature fumaroles (<100°C). At the end of the 90's and the firsts years of 00's there was a small changes on fumarole fields sizes and small increase on temperature and microquakes, but it was after 2005 that the volcano increased the seismicity from 10 to 100 diary microquakes, accompained by a higher degassing, acid rain and fumaroles over ?250°C. On January 5th, 2010 the volcano had a serial of phreatic eruptions, which formed an elongated intracrateric vent named "Boquete 2010", at the NW crater, which reached maximum temperatures of 560°C, also incandescence at night with sporadically emission of non-juvenile ashes. Later on June 2011, "Boquete 2010" temperature decreased to ?300°C, but some new fumaroles appeared in the NW intracrater with a maximum temperature of 531°C, also with incandescence and SO2 blue combustion gases. Finally on January 11, 2012 during a fieldwork caused by thermal images showing the increase on temperature of fumaroles (?250°C to ?450°C), a couple of active sulphur flows of at least 100m long appeared, that flows behaved like a newtonian liquid with similar setting of a pahoehoe lava. Next day on January 12, the volcano had a serial of phreatic eruptions with emission of non-juvenile ashes and formed a new vent ("Boquete 2012") in outer eastern wall of the NW crater, that reach temperatures of 780°C also with incandescence and SO2 combustion gases.

González, G.; Ramirez, C. J.; Mora-Amador, R.; Rouwet, D.; Mora, R.; Alpizar, Y.; Picado, C.

2012-12-01

341

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

342

The origin of the Hawaiian Volcano Observatory  

SciTech Connect

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

Dvorak, John [University of Hawaii's Institute for Astronomy (United States)

2011-05-15

343

Mantle fault zone beneath Kilauea Volcano, Hawaii.  

PubMed

Relocations and focal mechanism analyses of deep earthquakes (>/=13 kilometers) at Kilauea volcano demonstrate that seismicity is focused on an active fault zone at 30-kilometer depth, with seaward slip on a low-angle plane, and other smaller, distinct fault zones. The earthquakes we have analyzed predominantly reflect tectonic faulting in the brittle lithosphere rather than magma movement associated with volcanic activity. The tectonic earthquakes may be induced on preexisting faults by stresses of magmatic origin, although background stresses from volcano loading and lithospheric flexure may also contribute. PMID:12702874

Wolfe, Cecily J; Okubo, Paul G; Shearer, Peter M

2003-04-18

344

Density imaging of volcanos with atmospheric muons  

NASA Astrophysics Data System (ADS)

Their long range in matter renders high-energy atmospheric muons a unique probe for geophysical explorations, permitting the cartography of density distributions which can reveal spatial and possibly also temporal variations in extended geological structures. A Collaboration between volcanologists and (astro-)particle physicists, TOMUVOL, was formed in 2009 to study tomographic muon imaging of volcanos with high-resolution tracking detectors. Here we discuss preparatory work towards muon tomography as well as the first flux measurements taken at the Puy de Dôme, an inactive lava dome volcano in the Massif Central.

Fehr, Felix; Tomuvol Collaboration

2012-07-01

345

Venus small volcano classification and description  

NASA Technical Reports Server (NTRS)

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 by this author during data collection for the Magellan Volcanic and Magmatic Feature Catalog. This global study of approximately 10 exp 4 volcanoes provides new information for refining small volcano classification based on individual characteristics. Total number of these volcanoes was estimated to be 10 exp 5 to 10 exp 6 planetwide based on pre-Magellan analysis of Venera 15/16, and during preparation of the global catalog, small volcanoes were identified individually or in clusters in every C1-MIDR mosaic of the Magellan data set. Basal diameter (based on 1000 measured edifices) generally ranges from 2 to 12 km with a mode of 34 km, and follows an exponential distribution similar to the size frequency distribution of seamounts as measured from GLORIA sonar images. This is a typical distribution for most size-limited natural phenomena unlike impact craters which follow a power law distribution and continue to infinitely increase in number with decreasing size. Using an exponential distribution calculated from measured small volcanoes selected globally at random, we can calculate total number possible given a minimum size. The paucity of edifice diameters less than 2 km may be due to inability to identify very small volcanic edifices in this data set; however, summit pits are recognizable at smaller diameters, and 2 km may represent a significant minimum diameter related to style of volcanic eruption. Guest, et al, discussed four general types of small volcanic edifices on Venus: (1) small lava shields; (2) small volcanic cones; (3) small volcanic domes; and (4) scalloped margin domes ('ticks'). Steep-sided domes or 'pancake domes', larger than 20 km in diameter, were included with the small volcanic domes. For the purposes of this study, only volcanic edifices less than 20 km in diameter are discussed. This forms a convenient cutoff since most of the steep-sided domes ('pancake domes') and scalloped margin domes ('ticks') are 20 to 100 km in diameter, are much less numerous globally than are the smaller diameter volcanic edifices (2 to 3 orders of magnitude lower in total global number), and do not commonly occur in large clusters or fields of large numbers of edifices.

Aubele, J. C.

1993-01-01

346

U.S. GEOLOGICAL SURVEY --REDUCING RISK FROM VOLCANO HAZARDS Glacier Peak --History and Hazards of a Cascade Volcano  

E-print Network

U.S. GEOLOGICAL SURVEY -- REDUCING RISK FROM VOLCANO HAZARDS Glacier Peak -- History and Hazards of a Cascade Volcano Glacier Peak lies in Washington State's North Cascade Mountains, in the heart-capped volcanoes of Washington State have long been recognized by Native Americans in their language and legends

Torgersen, Christian

347

A Foamy Lava Lake at Kilauea Volcano, Hawai`i  

NASA Astrophysics Data System (ADS)

Kilauea Volcano, in Hawai`i, is currently erupting from two locations simultaneously: along the east rift zone and at the summit. The east rift zone eruption began in 1983 and is characterized by lava effusion from the Pu`u `O`o and nearby vents, while the summit eruptive vent, which opened in 2008, persistently emits gas and small amounts of ash while hosting a lava lake. On March 5, 2011, a dike initiated from the east rift zone magma conduit and reached the surface, resulting in the 4.5-day-long Kamoamoa fissure eruption just uprift of Pu`u `O`o. The eruption was accompanied by summit deflation as magma withdrew from subsurface reservoirs to feed the fissure eruption. The level of the summit lava lake dropped as the summit deflated. A continuously recording gravimeter located at Kilauea's summit (about 150 m east of the center of the summit eruptive vent, 80 m above the vent rim, and about 140 m above the highest level reached by the lava lake) measured a gravity decrease of about 150 ?Gal during the lava level drop, after taking into account corrections for the solid Earth tide. The gravity signal is caused by a combination of three processes. First, subsidence of 15 cm due to summit deflation moved the gravimeter closer to the center of the Earth, resulting in a gravity increase. Second, mass removal from the subsurface magma reservoir at a depth of 1.4 km (based on a model from GPS and InSAR data) caused a gravity decrease. Third, the drop in the level of the lava lake, which reached a maximum of about 150 m, led to a gravity decrease. Assuming a simple point source of pressure change and a typical density for basaltic magma (2.3-2.7 g/cm3), the first two processes can only explain a small percent of the observed gravity decrease, which must therefore be mainly due to the drop in the level of the lava lake. We developed a numerical model of the summit eruptive vent that takes into account its complex geometry (as deduced from geological observations). Using the change in lava level over time (data courtesy of Matt Patrick), we estimated that a lava density of about 0.8 g/cm3 is required to fit the gravity time series. Gravity results, therefore, argue that the upper part of the vent is occupied by a low-density lava foam (in agreement with models of Kilauea's summit eruption from seismic, gas, and geologic data by Tim Orr and Matt Patrick) and provide the only means of quantifying the lava lake density.

Poland, M. P.; Carbone, D.

2012-12-01

348

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

349

Mobile Response Team Saves Lives in Volcano Crises  

USGS Publications Warehouse

The world's only volcano crisis response team, organized and operated by the USGS, can be quickly mobilized to assess and monitor hazards at volcanoes threatening to erupt. Since 1986, the team has responded to more than a dozen volcano crises as part of the Volcano Disaster Assistance Program (VDAP), a cooperative effort with the Office of Foreign Disaster Assistance of the U.S. Agency for International Development. The work of USGS scientists with VDAP has helped save countless lives, and the valuable lessons learned are being used to reduce risks from volcano hazards in the United States.

Ewert, John W.; Miller, C. Dan; Hendley, James W.; Stauffer, Peter H.

1997-01-01

350

Volcano monitoring using GPS: Developing data analysis strategies based on the June 2007 Klauea Volcano intrusion  

E-print Network

] The global positioning system (GPS) is one of the most common techniques, and the current state of the art, global positioning system (GPS) volcano monitoring systems must be installed on the ground and thus

351

Characteristics and management of the 2006-2008 volcanic crisis at the Ubinas volcano (Peru)  

NASA Astrophysics Data System (ADS)

Ubinas volcano is located 75 km East of Arequipa and ca. 5000 people are living within 12 km from the summit. This composite cone is considered the most active volcano in southern Peru owing to its 24 low to moderate magnitude (VEI 1-3) eruptions in the past 500 years. The onset of the most recent eruptive episode occurred on 27 March 2006, following 8 months of heightened fumarolic activity. Vulcanian explosions occurred between 14 April 2006 and September 2007, at a time ejecting blocks up to 40 cm in diameter to distances of 2 km. Ash columns commonly rose to 3.5 km above the caldera rim and dispersed fine ash and aerosols to distances of 80 km between April 2006 and April 2007. Until April 2007, the total volume of ash was estimated at 0.004 km 3, suggesting that the volume of fresh magma was small. Ash fallout has affected residents, livestock, water supplies, and crop cultivation within an area of ca. 100 km 2 around the volcano. Continuous degassing and intermittent mild vulcanian explosions lasted until the end of 2008. Shortly after the initial explosions on mid April 2006 that spread ash fallout within 7 km of the volcano, an integrated Scientific Committee including three Peruvian institutes affiliated to the Regional Committee of Civil Defense for Moquegua, aided by members of the international cooperation, worked together to: i) elaborate and publish volcanic hazard maps; ii) inform and educate the population; and iii) advise regional authorities in regard to the management of the volcanic crisis and the preparation of contingency plans. Although the 2006-2008 volcanic crisis has been moderate, its management has been a difficult task even though less than 5000 people now live around the Ubinas volcano. However, the successful management has provided experience and skills to the scientific community. This volcanic crisis was not the first one that Peru has experienced but the 2006-2008 experience is the first long-lasting crisis that the Peruvian civil authorities have had to cope with, including attempts to utilize a new alert-level scheme and communications system, and the successful evacuation of 1150 people. Lessons learned can be applied to future volcanic crises in southern Peru, particularly in the case of reawakening of El Misti volcano nearby Arequipa.

Rivera, Marco; Thouret, Jean-Claude; Mariño, Jersy; Berolatti, Rossemary; Fuentes, José

2010-12-01

352

Using Ground Penetrating Radar to Help Delineate Lahar Hazard Zones at Cotopaxi Volcano, Ecuador  

NASA Astrophysics Data System (ADS)

Cotopaxi (5897 m) is located in the Eastern Cordillera of the Ecuadorian Andes about 80 km south of Quito and is one of the most active Ecuadorian volcanoes. Over the last 2000 years, Cotopaxi has had at least one eruption of Volcano Explosivity Index (VEI) 3 or larger per century. Many of these past eruptions melted parts of the glaciers on Cotopaxi, generating large volume debris flows. These flows rapidly descended along the three main drainage systems of the volcano towards the North, East and Southwest resulting in considerable destruction. The focus of this work is the study of a debris flow fan covering an area of 2.8 km2. The fan is situated within the confluence area of three quebradas; the San Lorenzo, the San Diego and the Burrohuaycu, that form part of the southwest drainage system 13 km downslope from the volcano summit. In order to estimate extent and thickness of recent lahar deposits, we used a Ground Penetrating Radar (GPR) survey that covers the fan surface in a grid pattern. Transects are perpendicular and parallel to the flow direction of the quebradas. The total length of all transects is 10 km. Regular common mid-point surveys (CMP) at different sites along the lines ensure wave velocity control on wet and dry ground. Global Positioning System Rover measurements along the transects yield X, Y and Z topographic control with an accuracy of decimeters that are used to correct the vertical exaggeration of the GPR profiles. We chose 200 MHz antennas having an average penetration depth of 6 m assuming a velocity of 0.09 m/ns, helping us detect even relatively small changes in outcrop morphology and stratigraphy over short distances. Subsurface control of the surficial geology comes from outcrop sections, quarry faces and excavated trenches that are distributed across the fan area. The identification of a paleo-lahar topography and the integration of GPR data are primary components of this ongoing lahar flow modeling study.

Ettinger, S.; Kruse, S.

2007-12-01

353

Stress field change around the Mount Fuji volcano magma system caused by the Tohoku megathrust earthquake, Japan  

NASA Astrophysics Data System (ADS)

Crustal deformation by the M w 9.0 megathrust Tohoku earthquake causes the extension over a wide region of the Japanese mainland. In addition, a triggered M w 5.9 East Shizuoka earthquake on March 15 occurred beneath the south flank, just above the magma system of Mount Fuji. To access whether these earthquakes might trigger the eruption, we calculated the stress and pressure changes below Mount Fuji. Among the three plausible mechanisms of earthquake-volcano interactions, we calculate the static stress change around volcano using finite element method, based on the seismic fault models of Tohoku and East Shizuoka earthquakes. Both Japanese mainland and Mount Fuji region are modeled by seismic tomography result, and the topographic effect is also included. The differential stress given to Mount Fuji magma reservoir, which is assumed to be located to be in the hypocentral area of deep long period earthquakes at the depth of 15 km, is estimated to be the order of about 0.001-0.01 and 0.1-1 MPa at the boundary region between magma reservoir and surrounding medium. This pressure change is about 0.2 % of the lithostatic pressure (367.5 MPa at 15 km depth), but is enough to trigger an eruptions in case the magma is ready to erupt. For Mount Fuji, there is no evidence so far that these earthquakes and crustal deformations did reactivate the volcano, considering the seismicity of deep long period earthquakes.

Fujita, Eisuke; Kozono, Tomofumi; Ueda, Hideki; Kohno, Yuhki; Yoshioka, Shoichi; Toda, Norio; Kikuchi, Aiko; Ida, Yoshiaki

2013-01-01

354

Dynamics and deposits of multiple pyroclastic density currents associated with the May 2008 eruption of Chaitén volcano (Chile)  

NASA Astrophysics Data System (ADS)

Explosive activity at Chaitén volcano in southern Chile, a 3-km-diameter caldera with a 0.5 km3 pre-eruption rhyolite lava dome, triggered multiple moderate- to low-temperature, dilute, pyroclastic density currents (PDCs) from 2-7 May 2008. Flows were focused predominantly in discrete sectors north and east of the volcano. A blast-like PDC leveled a 2-km-long, 4-km2 swath of trees north of the volcano, removing trees near the volcano's rim but causing only minor abrasion and leaf kill at its distal limit. Felled trees pointing in the down-current direction dominate the disturbance zone. The PDC left a decimeters-thick friable deposit grading upward from poorly sorted, fines depleted, pumiceous coarse ash and fine lapilli to pumiceous and lithic coarse ash. Fragments of charred and uncharred wood are concentrated in the basal half of the deposit, but vegetation protruding above the deposit is largely uncharred. Thin overlying layers of tephra fall suggest the PDC deposit was emplaced during the initial explosive phase on 2 May. Deposit characteristics and forest impacts suggest that the current was of moderate temperature (< 300°C), dilute, highly mobile and energetic, having a dynamic pressure of 2-4 kPa and a minimum, near-ground velocity of 30-40 ms-1. A similar and probably contemporaneous PDC felled approximately 2 km2 of forest on the northeast flank of the volcano. Deposits and impacts of PDCs east of the volcano contrast with that to the north. To the east, PDC(s) defoliated large trees on the outer flank, but tree boles, some with intact limbs, remained standing and unabraded; bark and epiphytes were largely intact and uncharred. However, small understory trees were broken with their tops pointed downhill, and ash clung to vertical tree boles to a height of several meters above ground surface. One or more PDCs left meter-scale dunes on the caldera floor, composed of stratified beds of friable pumice lapilli, pumiceous and lithic coarse ash, and faintly stratified ash and polymictic lapilli. Similarly stratified beds preserved at the low point on the east caldera rim show that the PDC(s) swept over the rim at this point. The deposit on the outer eastern flank is 2-3 m thick and composed of curviplanar, discontinuous beds of fine to coarse ash supporting scattered pumice lapilli. At Chaitén volcano, there is no evidence that sector collapse or significant dome collapse rapidly decompressed a magma body or controlled the azimuth of directed PDCs. We therefore hypothesize that northward- and northeastward-directed, blast-like PDCs were caused by rapid decompression associated with vent opening along the most propitious, subvertical fissures that existed in the old lava dome, possibly aided by vent asymmetry. A similar mechanism has been inferred for the blast event during the 1902 eruption of Mount Pelée, Martinique. We infer that PDC(s) affecting the east flank of Chaitén formed by column collapse and partial spillover at the low point on the east rim. Such limited and low-temperature PDCs are noteworthy for a major explosive rhyolite eruption.

Major, J. J.; Hoblitt, R. P.; Pierson, T. C.; Moreno, H.

2012-12-01

355

Sangay volcano, Ecuador: structural development, present activity and petrology  

NASA Astrophysics Data System (ADS)

Sangay (5230 m), the southernmost active volcano of the Andean Northern Volcanic Zone (NVZ), sits ˜130 km above a >32-Ma-old slab, close to a major tear that separates two distinct subducting oceanic crusts. Southwards, Quaternary volcanism is absent along a 1600-km-long segment of the Andes. Three successive edifices of decreasing volume have formed the Sangay volcanic complex during the last 500 ka. Two former cones (Sangay I and II) have been largely destroyed by sector collapses that resulted in large debris avalanches that flowed out upon the Amazon plain. Sangay III, being constructed within the last avalanche amphitheater, has been active at least since 14 ka BP. Only the largest eruptions with unusually high Plinian columns are likely to represent a major hazard for the inhabited areas located 30 to 100 km west of the volcano. However, given the volcano's relief and unbuttressed eastern side, a future collapse must be considered, that would seriously affect an area of present-day colonization in the Amazon plain, ˜30 km east of the summit. Andesites greatly predominate at Sangay, there being few dacites and basalts. In order to explain the unusual characteristics of the Sangay suite—highest content of incompatible elements (except Y and HREE) of any NVZ suite, low Y and HREE values in the andesites and dacites, and high Nb/La of the only basalt found—a preliminary five-step model is proposed: (1) an enriched mantle (in comparison with an MORB source), or maybe a variably enriched mantle, at the site of the Sangay, prior to Quaternary volcanism; (2) metasomatism of this mantle by important volumes of slab-derived fluids enriched in soluble incompatible elements, due to the subduction of major oceanic fracture zones; (3) partial melting of this metasomatized mantle and generation of primitive basaltic melts with Nb/La values typical of the NVZ, which are parental to the entire Sangay suite but apparently never reach the surface and subordinate production of high Nb/La basaltic melts, maybe by lower degrees of melting at the periphery of the main site of magma formation, that only infrequently reach the surface; (4) AFC processes at the base of a 50-km-thick crust, where parental melts pond and fractionate while assimilating remelts of similar basaltic material previously underplated, producing andesites with low Y and HREE contents, due to garnet stability at this depth; (5) low-pressure fractionation and mixing processes higher in the crust. Both an enriched mantle under Sangay prior to volcanism and an important slab-derived input of fluids enriched in soluble incompatible elements, two parameters certainly related to the unique setting of the volcano at the southern termination of the NVZ, apparently account for the exceptionally high contents of incompatible elements of the Sangay suite. In addition, the low Cr/Ni values of the entire suite—another unique characteristic of the NVZ—also requires unusual fractionation processes involving Cr-spinel and/or clinopyroxene, either in the upper mantle or at the base of the crust.

Monzier, Michel; Robin, Claude; Samaniego, Pablo; Hall, Minard L.; Cotten, Jo; Mothes, Patricia; Arnaud, Nicolas

1999-05-01

356

Long Period Earthquakes Beneath California's Young and Restless Volcanoes  

NASA Astrophysics Data System (ADS)

The newly established USGS California Volcano Observatory has the broad responsibility of monitoring and assessing hazards at California's potentially threatening volcanoes, most notably Mount Shasta, Medicine Lake, Clear Lake Volcanic Field, and Lassen Volcanic Center in northern California; and Long Valley Caldera, Mammoth Mountain, and Mono-Inyo Craters in east-central California. Volcanic eruptions occur in California about as frequently as the largest San Andreas Fault Zone earthquakes-more than ten eruptions have occurred in the last 1,000 years, most recently at Lassen Peak (1666 C.E. and 1914-1917 C.E.) and Mono-Inyo Craters (c. 1700 C.E.). The Long Valley region (Long Valley caldera and Mammoth Mountain) underwent several episodes of heightened unrest over the last three decades, including intense swarms of volcano-tectonic (VT) earthquakes, rapid caldera uplift, and hazardous CO2 emissions. Both Medicine Lake and Lassen are subsiding at appreciable rates, and along with Clear Lake, Long Valley Caldera, and Mammoth Mountain, sporadically experience long period (LP) earthquakes related to migration of magmatic or hydrothermal fluids. Worldwide, the last two decades have shown the importance of tracking LP earthquakes beneath young volcanic systems, as they often provide indication of impending unrest or eruption. Herein we document the occurrence of LP earthquakes at several of California's young volcanoes, updating a previous study published in Pitt et al., 2002, SRL. All events were detected and located using data from stations within the Northern California Seismic Network (NCSN). Event detection was spatially and temporally uneven across the NCSN in the 1980s and 1990s, but additional stations, adoption of the Earthworm processing system, and heightened vigilance by seismologists have improved the catalog over the last decade. LP earthquakes are now relatively well-recorded under Lassen (~150 events since 2000), Clear Lake (~60 events), Mammoth Mountain (~320 events), and Long Valley Caldera (~40 events). LP earthquakes are notably absent under Mount Shasta. With the exception of Long Valley Caldera where LP earthquakes occur at depths of ?5 km, hypocenters are generally between 15-25 km. The rates of LP occurrence over the last decade have been relatively steady within the study areas, except at Mammoth Mountain, where years of gradually declining LP activity abruptly increased after a swarm of unusually deep (20 km) VT earthquakes in October 2012. Epicenter locations relative to the sites of most recent volcanism vary across volcanic centers, but most LP earthquakes fall within 10 km of young vents. Source models for LP earthquakes often involve the resonance of fluid-filled cracks or nonlinear flow of fluids along irregular cracks (reviewed in Chouet and Matoza, 2013, JVGR). At mid-crustal depths the relevant fluids are likely to be low-viscosity basaltic melt and/or exsolved CO2-rich volatiles (Lassen, Clear Lake, Mammoth Mountain). In the shallow crust, however, hydrothermal waters/gases are likely involved in the generation of LP seismicity (Long Valley Caldera).

Pitt, A. M.; Dawson, P. B.; Shelly, D. R.; Hill, D. P.; Mangan, M.

2013-12-01

357

Bathymetry of southern Mauna Loa Volcano, Hawaii  

USGS Publications Warehouse

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

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

1993-01-01

358

Hydrogeochemical indicators of the Popocatépetl volcano activity  

Microsoft Academic Search

The main ions, silica, boron and sulfide were analyzed by standard methods in samples from waters of several springs and a shallow well located around Popocatépetl volcano. Analyses of several chemical components allowed a geochemical monitoring of Popocatépetl activity from 1995 to 2004. Most samples were dilute and immature cold waters and only silica minerals were oversaturated in the springs

M. A. Armienta; S. De la Cruz-Reyna; A. Gómez; E. Ramos; N. Ceniceros; O. Cruz; A. Aguayo; A. Martínez

2008-01-01

359

Exact bound states in volcano potentials  

E-print Network

Quantum mechanics in a one--parameter family of volcano potentials is investigated. After a discussion on their construction and classical mechanics, we obtain exact, normalisable bound states for specific values of the energy. The nature of the wave functions and probability densities, as well as some curious features of the solutions are highlighted.

Ratna Koley; Sayan Kar

2006-11-07

360

Exact bound states in volcano potentials  

E-print Network

Quantum mechanics in a one--parameter family of volcano potentials is investigated. After a discussion on their construction and classical mechanics, we obtain exact, normalisable bound states for specific values of the energy. The nature of the wave functions and probability densities, as well as some curious features of the solutions are highlighted.

Koley, R; Kar, Sayan; Koley, Ratna

2006-01-01

361

Monitoring ground deformations at active Neapolitan volcanoes  

Microsoft Academic Search

The Neapolitan volcanic area, located in the south sector of the Campanian plain, includes three active volcanoes: Somma-Vesuvio, Campi Flegrei Caldera, and Ischia Islands. Somma-Vesuvio (last eruption occurred in 1944) is characterized by a low level seismic and ground deformation activity; Campi Flegrei Caldera (last eruption occurred in 1538) is characterized by slow deformation and several bradyiseismic events. During the

F. Pingue; C. del Gaudio; G. de Natale; F. Obrizzo; V. Sepe; G. Cecere; P. de Martino; V. Siniscalchi; U. Tammaro

2003-01-01

362

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.

363

Publications of the Volcano Hazards Program 2005  

E-print Network

seismicity at Long Valley Caldera: Journal of Geophysical Research, v. 110, B04302, doi:10.1029/2004JB003211 caldera-forming eruption of Okmok volcano, Alaska: Bulletin of Volcanology, v. 67, p. 497-525. Calvert, A, determined from waveform inversions of very long period signals: Journal of Geophysical Researc

Torgersen, Christian

364

Evolution of large shield volcanoes on Venus  

Microsoft Academic Search

We studied the geologic history, topographic expression, and gravity signature of 29 large Venusian shield volcanoes with similar morphologies in Magellan synthetic aperture radar imagery. While they appear similar in imagery, 16 have a domical topographic expression and 13 have a central depression. Typical dimensions for the central depression are 150 km wide and 500 m deep. The central depressions

Robert R. Herrick; Josef Dufek; Patrick J. McGovern

2005-01-01

365

New volcanoes discovered in southeast Australia  

NASA Astrophysics Data System (ADS)

Scientists have discovered three new active volcanoes in the Newer Volcanics Province (NVP) in southeast Australia. Researchers from Monash University in Melbourne describe in the Australian Journal of Earth Sciences how they used a combination of satellite photographs, detailed topography models from NASA, the distribution of magnetic minerals in the rocks, and site visits to analyze the region.

Wendel, JoAnna

2014-07-01

366

Santa María, Guatemala: A decade volcano  

Microsoft Academic Search

Located in southwestern Guatemala, near the triple junction of the North American, Cocos, and Caribbean plates (Figure 1), Santa María is the most notorious volcano in Central America. In October 1902, Santa María was the site of one of the Earth's ten largest historic eruptions. This eruption resulted in thousands of deaths and had global atmospheric impact. Since 1922, the

Eddy Hardie Sanchez Bennett; William I. Rose; F. Michael Conway

1992-01-01

367

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

368

Publications of the Volcano Hazards Program 2004  

E-print Network

of Mount Pinatubo (Philippines): Journal of Geophysical Research, v. 109, B07302, doi:10.1029/2003JB002959, Geochemical constraints on possible subduction components in lavas of Mayon and Taal volcanoes, southern Luzon, Philippines: Journal of Petrology, v. 45, p. 1089-1108. Coombs, M. L., Clague, D. A., Moore, G. F

Torgersen, Christian

369

The Middle East.  

ERIC Educational Resources Information Center

This sixth grade resource unit focuses on Middle East culture as seen through five areas of the social sciences: anthropology-sociology, geography, history, economics, and political science. Among objectives that the student is expected to achieve are the following: 1) given general information on the Middle East through the use of film, visuals,…

Blouin, Virginia; And Others

370

Mechanism of explosive eruptions of Kilauea Volcano, Hawaii  

USGS Publications Warehouse

A small explosive eruption of Kilauea Volcano, Hawaii, occurred in May 1924. The eruption was preceded by rapid draining of a lava lake and transfer of a large volume of magma from the summit reservoir to the east rift zone. This lowered the magma column, which reduced hydrostatic pressure beneath Halemaumau and allowed groundwater to flow rapidly into areas of hot rock, producing a phreatic eruption. A comparison with other events at Kilauea shows that the transfer of a large volume of magma out of the summit reservoir is not sufficient to produce a phreatic eruption. For example, the volume transferred at the beginning of explosive activity in May 1924 was less than the volumes transferred in March 1955 and January-February 1960, when no explosive activity occurred. Likewise, draining of a lava lake and deepening of the floor of Halemaumau, which occurred in May 1922 and August 1923, were not sufficient to produce explosive activity. A phreatic eruption of Kilauea requires both the transfer of a large volume of magma from the summit reservoir and the rapid removal of magma from near the surface, where the surrounding rocks have been heated to a sufficient temperature to produce steam explosions when suddenly contacted by groundwater. ?? 1992 Springer-Verlag.

Dvorak, J.J.

1992-01-01

371

Natural Pollution Caused by the Extremely Acid Crater Lake Kawah Ijen, East Java, Indonesia (7 pp)  

Microsoft Academic Search

Background, Aims and Scope. Lakes developing in volcano craters can become highly acidic through the influx of volcanic gases, yielding one of the chemically most extreme natural environments on earth. The Kawah Ijen crater lake in East Java (Indonesia) has a pH < 0.3. It is the source of the extremely acidic and metal-polluted river Banyupahit (45 km). The lake

Ansje J. Löhr; Thom A. Bogaard; Alex Heikens; Martin R. Hendriks; Sri Sumarti; Manfred J. Van Bergen; Kees C. A. M. van Gestel; Nico van Straalen; Pieter Vroon; Budi Widianarko

2005-01-01

372

Measurement and interpretation of diffuse gas emission in tectonic structures associated to volcanoes: the case of Volcán de Fuego de Colima  

NASA Astrophysics Data System (ADS)

Diffuse gas emission is used to understand the behavior of volcanoes during eruptive activity or during passive-degassing periods (i.e. diffuse gas emissions of Stromboli volcano have been observed for 10 years; Inguaggiato 2011). Also, diffuse gas emission is used to study the activity of tectonic structures such as faults in some areas as precursors of seismic events. Volcanoes are always associated to tectonic structures. However, few has been done to understand the volcano-tectonic relationships using diffuse emissions as a tool. For instance, Volcán de Fuego de Colima (VFC) is located in a highly active tectonic area such as the Colima graben where the existence of southward-trending faults have been previously documented as well as east-west trending faults (Macías 2005; Norini et al 2010; Cortés et al 2010). VFC is a historically active volcano with major explosive eruptions (most recent in 1913), refilling of the crater, overtopping with growing lava domes and pyroclastic flow events. However, what is the relationship between the tectonic features across the volcano? Are these structures affecting the activity of the volcano? If so, how are they affecting the eruptive activity? Can the tectonic activity be used to understand the evolution of the volcanic activity? In this work we use the diffuse gas emission to answer these questions. For this end, we measured soil CO2 flux and soil H2S flux along the Tamazula fault at more than 300 stations. Also, samples were collected from springs at VFC. Our preliminary results found no indication of significant tectonic activity around the faults to which VFC is associated. This is the first measurement of this kind at VFC and established a baseline we may compare with in the future.

Jácome Paz, M. P.; Delgado Granados, H.; Inguaggiato, S.

2011-12-01

373

Petrogenesis of a voluminous Quaternary adakitic volcano: the case of Baru volcano  

NASA Astrophysics Data System (ADS)

The origin of adakite magmas remains controversial because initially the term adakite had petrogenetic significance implying an origin by direct melting of the eclogitized subducting oceanic crust. Many models have been produced for their origin, and until now there has not been a straightforward method to discriminate between these models in a given adakite suite. Here, we use detailed chronological and geochemical studies of selected adakitic edifices that allows for the determination of the magmatic output rate parameter (Qe), which has been correlated with the rates of magma generation deep within subduction zones. By providing temporal and eruption rate estimates, we provide constraints on the possible petrogenetic processes involved in the generation of adakite-like signatures. Adakite magmas derived from the melting of the subducting slab should be volumetrically insignificant when compared to the adakite-like magmas produced by typical arc magma generation processes. In this study, we use this observation and the extraordinary stratigraphic exposure from Miocene to present in an adakitic volcano in Panama and to study the temporal and chemical variation in erupted magmas to estimate rates of magma generation. Detailed chemical and geochronological analyses of Baru volcano indicate that the volcanic edifice was constructed in its entirety during the Quaternary and magmas display adakite-like features such as steep rare earth elements patterns, pronounced depletions in the heavy rare earth elements, low Y, high Sr, and high Sr/Y. The magmatic output rates (Qe) that we have calculated show that compared to other typical adakitic volcanoes, most of the volcanic edifice of Baru volcano was constructed extremely rapidly (<~213 k.a.) and in time frames that are similar to typical arc volcanoes. The observed chemical and mineralogical variation, coupled with the high magma production rates, indicate that Baru volcano is more representative of a typical arc volcano than a small-volume melt of the subducting oceanic crust. The technique we outline may have broader application in determining the petrogenetic conditions of other adakite suites.

Hidalgo, Paulo J.; Rooney, Tyrone O.

2014-09-01

374

Space Radar Image of Colombian Volcano  

NASA Technical Reports Server (NTRS)

This is a radar image of a little known volcano in northern Colombia. The image was acquired on orbit 80 of space shuttle Endeavour on April 14, 1994, by the Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR). The volcano near the center of the image is located at 5.6 degrees north latitude, 75.0 degrees west longitude, about 100 kilometers (65 miles) southeast of Medellin, Colombia. The conspicuous dark spot is a lake at the bottom of an approximately 3-kilometer-wide (1.9-mile) volcanic collapse depression or caldera. A cone-shaped peak on the bottom left (northeast rim) of the caldera appears to have been the source for a flow of material into the caldera. This is the northern-most known volcano in South America and because of its youthful appearance, should be considered dormant rather than extinct. The volcano's existence confirms a fracture zone proposed in 1985 as the northern boundary of volcanism in the Andes. The SIR-C/X-SAR image reveals another, older caldera further south in Colombia, along another proposed fracture zone. Although relatively conspicuous, these volcanoes have escaped widespread recognition because of frequent cloud cover that hinders remote sensing imaging in visible wavelengths. Four separate volcanoes in the Northern Andes nations ofColombia and Ecuador have been active during the last 10 years, killing more than 25,000 people, including scientists who were monitoring the volcanic activity. Detection and monitoring of volcanoes from space provides a safe way to investigate volcanism. The recognition of previously unknown volcanoes is important for hazard evaluations because a number of major eruptions this century have occurred at mountains that were not previously recognized as volcanoes. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those changes which are induced by human activity. SIR-C was developed by NASA's Jet Propulsion Laboratory. X-SAR was developed by the Dornier and Alenia Spazio companiesfor the German space agency, Deutsche Agentur fuer Raumfahrtange-legenheiten (DARA), and the Italian space agency,Agenzia SpazialeItaliana (ASI), with the Deutsche Forschungsanstalt fuer Luft undRaumfahrt e.v.(DLR), the major partner in science,operations, and data processing of X-SAR.

1999-01-01

375

Volcano deformation and subdaily GPS products  

NASA Astrophysics Data System (ADS)

Volcanic unrest is often accompanied by hours to months of deformation of the ground that is measurable with high-precision GPS. Although GPS receivers are capable of near continuous operation, positions are generally estimated for daily intervals, which I use to infer characteristics of a volcano’s plumbing system. However, GPS based volcano geodesy will not be useful in early warning scenarios unless positions are estimated at high rates and in real time. Visualization and analysis of dynamic and static deformation during the 2011 Tohokuoki earthquake in Japan motivates the application of high-rate GPS from a GPS seismology perspective. I give examples of dynamic seismic signals and their evolution to the final static offset in 30 s and 1 s intervals, which demonstrates the enhancement of subtle rupture dynamics through increased temporal resolution. This stresses the importance of processing data at recording intervals to minimize signal loss. Deformation during the 2009 eruption of Redoubt Volcano, Alaska, suggested net deflation by 0.05 km³ in three distinct phases. Mid-crustal aseismic precursory inflation began in May 2008 and was detected by a single continuous GPS station about 28 km NE of Redoubt. Deflation during the explosive and effusive phases was sourced from a vertical ellipsoidal reservoir at about 7-11.5 km. From this I infer a model for the temporal evolution of a complex plumbing system of at least 2 sources during the eruption. Using subdaily GPS positioning solutions I demonstrate that plumes can be detected and localized by utilizing information on phase residuals. The GPS network at Bezymianny Volcano, Kamchatka, records network wide subsidence at rapid rates between 8 and 12 mm/yr from 2005-2010. I hypothesize this to be caused by continuous deflation of a ˜30 km deep sill under Kluchevskoy Volcano. Interestingly, 1-2 explosive events per year cause little to no deformation at any site other than the summit site closest to the vent. I derive evidence for a very shallow source, likely within the edifice. This work shows that network design and individual plumbing system characteristics affect the ability to detect motion on subdaily and even weekly time scales, which stresses the importance of network scale considerations.

Grapenthin, Ronni

376

Lahar Hazard Modeling at Tungurahua Volcano, Ecuador  

NASA Astrophysics Data System (ADS)

Tungurahua Volcano (Lat. 01^o28'S; Long. 78^o27'W), located in the central Ecuadorian Andes, is an active edifice that rises more than 3 km above surrounding topography. Since European settlement in 1532, Tungurahua has experienced four major eruptive episodes: 1641-1646, 1773-1781, 1886-1888 and 1916-1918 (Hall et al, JVGR V91; p1-21, 1999). In September 1999, Tungurahua began a new period of activity that continues to the present. During this time, the volcano has erupted daily, depositing ash and blocks on its steep flanks. A pattern of continuing eruptions, coupled with rainfall up to 28 mm in a 6 hour period (rain data collected in Baños at 6-hr intervals, 3000 meters below Tungurahua’s summit), has produced an environment conducive to lahar mobilization. Tungurahua volcano presents an immediate hazard to the town of Baños, an important tourist destination and cultural center with a population of about 25,000 residents located 8 km from the crater. During the current eruptive episode, lahars have occurred as often as 3 times per week on the northern and western slopes of the volcano. Consequently, the only north-south trending highway on the west side of Tungurahua has been completely severed at the intersection of at least ten drainages, where erosion has exceeded 10 m since 1999. The La Pampa quebrada, located 1 km west of Baños, is the most active of Tungurahua's drainages. At this location, where the slope is moderate, lahars continue to inundate the only highway linking Baños to the Pan American Highway. Because of steep topography, the conventional approach of measuring planimetric inundation areas to determine the scale of lahars could not be employed. Instead, cross sections were measured in the channels using volume/cross-sectional inundation relationships determined by (Iverson et al, GSABull V110; no. 8, p972-984, 1998). After field observations of the lahars, LAHARZ, a program used in a geographic information system (GIS) to objectively map lahar-hazard-zones using a digital elevation model (DEM), was used to construct a hazard map for the volcano. The 10 meter resolution DEM was constructed for Tungurahua Volcano using scanned topographic lines obtained from the GIS Department at the Escuela Politécnica Nacional, Quito, Ecuador. The steep topographic gradients and rapid downcutting of most rivers draining the edifice prevents the deposition of lahars on the lower flanks of Tungurahua. Modeling confirms the high degree of flow channelization in the deep Tungurahua canyons. Inundation zones observed and shown by LAHARZ at Baños yield identification of safe zones within the city which would provide safety from even the largest magnitude lahar expected.

Sorensen, O. E.; Rose, W. I.; Jaya, D.

2003-04-01

377

Spatiotemporal probability of vent opening at Mt Etna volcano (Sicily, Italy)  

NASA Astrophysics Data System (ADS)

We produced a spatiotemporal probability map of vent opening at Mt Etna, using a statistical analysis of structural features of the flank eruptions of the last 2000 years. The methodology is based on the hypothesis that the location and frequency of future events will have the same causal factors as the eruptions occurring in the past. The study is supported by 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. The geological and structural data are converted in distinct and weighted probability density functions (PDFs), exploiting both spatial and temporal recurrence rates. The spatiotemporal probability map is obtained through a non-homogeneous Poisson process, where the expected recurrence rate per unit area is calculated as the weighted sum of the PDFs, with the weights derived from a backward/forward analysis to highlight the presence of temporal trends in the history of the volcano. The highest probability of new eruptive vents opening at Mt Etna falls within a N-S aligned area passing through the Summit Craters down to about 2000 m a.s.l. on the southern flank. Four other zones of high probability follow respectively the North-East, East-North-East, West and South Rifts, the latter reaching low altitudes (~400 m). Less susceptible areas prone to the opening of new vents were found around the faults cutting the upper portions of Mt Etna, including the western portion of the Pernicana fault system and the northern extent of the Ragalna fault system. The spatiotemporal probability map of vent opening provides detailed recurrence rates (events expected per unit area per unit time) and will hence be an important resource to predict the future timing and location of Etna eruptions. This structural-based map is the first and perhaps most important step in assessing lava flow hazards at Mt Etna, and thus represents a support tool for decision makers.

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

2012-04-01

378

SAR4Volcanoes: an international ASI funded research project on volcano deformation through new generation SAR sensors  

NASA Astrophysics Data System (ADS)

Volcano deformation monitoring is crucial to understand how magma emplaces, propagates and erupts. Therefore, volcano deformation research projects are particularly important opportunities to improve our understanding of volcano dynamics. SAR4Volcanoes is a 2-year research project funded by the Italian Space Agency (ASI) within the framework of a cooperation agreement with the Japan Aerospace Exploration Agency (JAXA). It focuses on volcano deformation analysis through Differential SAR Interferometry (DInSAR) techniques by means of COSMO-SkyMed and ALOS data, through the joint use of L-band and X-band SAR data. It also aims to the identification of methods and techniques to support decision making in emergency cases. Main target volcanoes in the projects are Etna, Vesuvio, Campi Flegrei and Stromboli (Italy) and Sakurajima and Kirishima (Japan). Secondary target volcanoes include recently or currently erupting volcanoes, as El Hierro (Spain), Nabro (Ethiopia) and Galapagos volcanoes (Ecuador). Since the project kickoff (July 2011) a large number of COSMO-SkyMed data has been acquired at these volcanoes; in some cases, the acquisitions are available almost at every satellite orbit, with an average interval down to 4 days. On these premises, the project represents an important opportunity to: (1) collect a significant amount of X-band data on active and erupting volcanoes and (2) study surface deformation to understand magma dynamics in different volcanic settings. We will present preliminary results on the ground deformation analysis of the main and secondary target volcanoes. In particular, target volcanoes without a pre-project archive are analyzed using single deformation maps, while those with archives are analysed through a time series approach, based on the SBAS technique.

Sansosti, E.; Pepe, S.; Solaro, G.; Casu, F.; Tizzani, P.; Acocella, V.; Ruch, J.; Nobile, A.; Puglisi, G.; Guglielmino, F.; Zoffoli, S.

2012-04-01

379

Darwin's triggering mechanism of volcano eruptions  

NASA Astrophysics Data System (ADS)

Charles Darwin wrote that ‘… the elevation of many hundred square miles of territory near Concepcion is part of the same phenomenon, with that splashing up, if I may so call it, of volcanic matter through the orifices in the Cordillera at the moment of the shock;…' and ‘…a power, I may remark, which acts in paroxysmal upheavals like that of Concepcion, and in great volcanic eruptions,…'. Darwin reports that ‘…several of the great chimneys in the Cordillera of central Chile commenced a fresh period of activity ….' In particular, Darwin reported on four-simultaneous large eruptions from the following volcanoes: Robinson Crusoe, Minchinmavida, Cerro Yanteles and Peteroa (we cite the Darwin's sentences following his The Voyage of the Beagle and researchspace. auckland. ac. nz/handle/2292/4474). Let us consider these eruptions taking into account the volcano shape and the conduit. Three of the volcanoes (Minchinmavida (2404 m), Cerro Yanteles (2050 m), and Peteroa (3603 m)) are stratovolcanos and are formed of symmetrical cones with steep sides. Robinson Crusoe (922 m) is a shield volcano and is formed of a cone with gently sloping sides. They are not very active. We may surmise, that their vents had a sealing plug (vent fill) in 1835. All these volcanoes are conical. These common features are important for Darwin's triggering model, which is discussed below. The vent fill material, usually, has high level of porosity and a very low tensile strength and can easily be fragmented by tension waves. The action of a severe earthquake on the volcano base may be compared with a nuclear blast explosion of the base. It is known, that after a underground nuclear explosion the vertical motion and the surface fractures in a tope of mountains were observed. The same is related to the propagation of waves in conical elements. After the explosive load of the base. the tip may break and fly off at high velocity. Analogous phenomenon may be generated as a result of a severe earthquake. The volcano base obtains the great earthquake-induced vertical acceleration, and the compression wave begins to propagate through the volcano body. Since we are considering conic volcano, the interaction of this wave with the free surface of the volcano may be easily analysed. It is found that the reflection of the upward-going wave from the volcano slope produces tensile stresses within the volcano and bubbles in conduit magma. The conduit magma is held at high pressure by the weight and the strength of the vent fill. This fill may be collapsed and fly off , when the upward wave is reflected from the volcano crater as a decompression wave. After this collapse the pressure on the magma surface drops to atmospheric, and the decompression front begins to move downward in the conduit. In particular, large gas bubbles can begin to form in the magma within the conduit. The resulting bubble growth provides the driving force at the beginning of the eruption. Thus, the earthquake-induced nonlinear wave phenomena can qualitatively explain the spectacular simultaneity of large eruptions after large earthquakes. The pressure difference between a region of low pressure (atmosphere) and the magma chamber can cause the large-scale eruption. The beginning and the process of the eruption depend on many circumstances: conduit system and its dimension, chamber size and pressure, magma viscosity and gas concentration in it may be the main variables . The resonant free oscillations in the conduit may continue for a long time, since they are fed by the magma chamber pressure (Galiev, Sh. U., 2003. The theory of nonlinear trans-resonant wave phenomena and an examination of Charles Darwin's earthquake reports. Geophys. J. Inter., 154, 300-354.). The behaviour of the system strongly depends on the magma viscosity. The gas can escape from the bubbles more easily in the case of low viscous magma. However, if the magma is very viscous, so the gas cannot escape so easily, then the bubbles grow very quickly near the vent only. Effects of this growth can resemble an explos

Galiev, Shamil

2010-05-01

380

Volcano eruption monitoring by thermal image correlation: pixel offsets show episodic dome growth at Colima volcano  

NASA Astrophysics Data System (ADS)

To quantify the magnitude of eruptions or explosions is one of the main problems in volcano monitoring programs. Whilst modern monitoring data such as derived from seismicity allow depicting the location, type and occurrence of volcanic activity, the scale of eruptions commonly remained to be estimated visually or in the aftermath based on eruptive products. Quantifying deformation and eruption occurrence is of high value not only for early warning, but also for physical understanding of explosive volcanoes as this study demonstrates for one of the most active volcanoes of Mexico. Volcán de Colima is currently experiencing a phase of viscous dome growth, associated with daily episodic Vulcanian eruptions and rock falls. Little is known about the dynamics of dome growth accompanied by explosion scales. We present results from a nighttime time-lapse infrared camera shooting, compared to local seismic amplitude recordings. As detected by tracking features in correlated images before and after the explosions, the location of the high-temperature field is subject to significant and systematic lateral pixel offsets during eruptions. Dome growth is shown to occur intermittently, with lateral displacements exceeding 1 m within less than 120 seconds. Only the thermally elevated regions of the dome are displaced and are often, but not always, associated to seismic amplitude peaks. Therefore our analysis of infrared image correlation suggests the occurrence of silent or aseismic dome growth episodes, challenging current understanding of volcano physics as well as applied methods in volcano surveillance.

Walter, T. R.; Legrand, D.; Granados, G. D.; Reyes, G.; Arámbula, R.

2012-04-01

381

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

382

Volcano Deformation and Gravity Workshop Synopsis and Outcomes  

NASA Astrophysics Data System (ADS)

The 2008 Volcano Deformation and Temporal Gravity Change Workshop; Vancouver, Washington, 13-15 May 2008; A volcano workshop was held in Washington State, near the U.S. Geological Survey (USGS) Cascades Volcano Observatory. The workshop, hosted by the USGS Volcano Hazards Program (VHP), included more than 40 participants from the United States, the European Union, and Canada. Goals were to promote (1) collaboration among scientists working on active volcanoes and (2) development of new tools for studying volcano deformation. The workshop focused on conventional and emerging techniques, including the Global Positioning System (GPS), borehole strain, interferometric synthetic aperture radar (InSAR), gravity, and electromagnetic imaging, and on the roles of aqueous and magmatic fluids.

Dzurisin, Daniel; Lu, Zhong

2009-01-01

383

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

384

Author's personal copy Adsorbate interactions on surface lead to a flattened Sabatier volcano plot  

E-print Network

Author's personal copy Adsorbate interactions on surface lead to a flattened Sabatier volcano plot: Surface Catalysis Sabatier principle Volcano Plot Oxygen Reduction Adsorbate interactions Microkinetic vs. adsorption strength volcano plot and reduce sensitivity to material elementary energetics

Chen, Sow-Hsin

385

Gravity, magnetic, and radiometric data for Newberry Volcano, Oregon, and vicinity  

USGS Publications Warehouse

Newberry Volcano in central Oregon is a 3,100-square-kilometer (1,200-square-mile) shield-shaped composite volcano, occupying a location east of the main north-south trend of the High Cascades volcanoes and forming a transition between the High Lava Plains subprovince of the Basin and Range Province to the east and the Cascade Range to the west. Magnetic, gravity, and radiometric data have been gathered and assessed for the region around the volcano. These data have widely varying quality and resolution, even within a given dataset, and these limitations are evaluated and described in this release. Publicly available gravity data in general are too sparse to permit detailed modeling except along a few roads with high-density coverage. Likewise, magnetic data are also unsuitable for all but very local modeling, primarily because available data consist of a patchwork of datasets with widely varying line-spacing. Gravity data show only the broadest correlation with mapped geology, whereas magnetic data show moderate correlation with features only in the vicinity of Newberry Caldera. At large scales, magnetic data correlate poorly with both geologic mapping and gravity data. These poor correlations are largely due to the different sensing depths of the two potential fields methods, which respond to physical properties deeper than the surficial geology. Magnetic data derive from rocks no deeper than the Curie-point isotherm depth (10 to 15 kilometers, km, maximum), whereas gravity data reflect density-contrasts to 100 to 150 km depths. Radiometric data from the National Uranium Resource Evaluation (NURE) surveys of the 1980s have perhaps the coarsest line-spacing of all (as much as 10 km between lines) and are extremely “noisy” for several reasons inherent to this kind of data. Despite its shallow-sensing character, only a few larger anomalies in the NURE data correlate well with geologic mapping. The purpose of this data series release is to collect and place the available geophysical data in the hands of other investigators in a readily comprehensible form. All data-compilation, splicing, filtering, and overlay-map displays were accomplished with the commercial Geosoft™ system, Advanced Option. Images are provided in both JPG and PDF formats.

Wynn, Jeff

2014-01-01

386

Seismic tomography at Popocatépetl volcano, Mexico  

NASA Astrophysics Data System (ADS)

We performed the first 3D seismic tomography of the Popocatépetl volcano, Mexico, from the inversion of the P-wave arrival times of nearly 1500 earthquakes recorded by up to 11 seismic stations of the permanent CENAPRED-SSN network. We used the Bayesian tomographic algorithm developed by Monteiller et al. (2005) to perform this P-wave travel-time tomography and carefully choose optimal regularization hyper-parameters. Sensitivity tests show that the inversion is correctly constrained under the volcano from - 1 to 4 km depth b.s.l.. At these depths, the optimal tomographic model mainly shows low-velocity volumes surrounded by higher-velocity volumes. Lateral heterogeneity is strong: the variation of the P-wave velocity may reach up to ± 20% of the average value at a given depth. Low-velocity volumes correlate well with results from former geological and geophysical studies.

Berger, Pia; Got, Jean-Luc; González, Carlos Valdés; Monteiller, Vadim

2011-03-01

387

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

388

Volcanism in Iceland in historical time: Volcano types, eruption styles and eruptive history  

NASA Astrophysics Data System (ADS)

The large-scale volcanic lineaments in Iceland are an axial zone, which is delineated by the Reykjanes, West and North Volcanic Zones (RVZ, WVZ, NVZ) and the East Volcanic Zone (EVZ), which is growing in length by propagation to the southwest through pre-existing crust. These zones are connected across central Iceland by the Mid-Iceland Belt (MIB). Other volcanically active areas are the two intraplate belts of Öræfajökull (ÖVB) and Snæfellsnes (SVB). The principal structure of the volcanic zones are the 30 volcanic systems, where 12 are comprised of a fissure swarm and a central volcano, 7 of a central volcano, 9 of a fissure swarm and a central domain, and 2 are typified by a central domain alone. Volcanism in Iceland is unusually diverse for an oceanic island because of special geological and climatological circumstances. It features nearly all volcano types and eruption styles known on Earth. The first order grouping of volcanoes is in accordance with recurrence of eruptions on the same vent system and is divided into central volcanoes (polygenetic) and basalt volcanoes (monogenetic). The basalt volcanoes are categorized further in accordance with vent geometry (circular or linear), type of vent accumulation, characteristic style of eruption and volcanic environment (i.e. subaerial, subglacial, submarine). Eruptions are broadly grouped into effusive eruptions where >95% of the erupted magma is lava, explosive eruptions if >95% of the erupted magma is tephra (volume calculated as dense rock equivalent, DRE), and mixed eruptions if the ratio of lava to tephra occupy the range in between these two end-members. Although basaltic volcanism dominates, the activity in historical time (i.e. last 11 centuries) features expulsion of basalt, andesite, dacite and rhyolite magmas that have produced effusive eruptions of Hawaiian and flood lava magnitudes, mixed eruptions featuring phases of Strombolian to Plinian intensities, and explosive phreatomagmatic and magmatic eruptions spanning almost the entire intensity scale; from Surtseyan to Phreatoplinian in case of "wet" eruptions and Strombolian to Plinian in terms of "dry" eruptions. In historical time the magma volume extruded by individual eruptions ranges from ˜1 m 3 to ˜20 km 3 DRE, reflecting variable magma compositions, effusion rates and eruption durations. All together 205 eruptive events have been identified in historical time by detailed mapping and dating of events along with extensive research on documentation of eruptions in historical chronicles. Of these 205 events, 192 represent individual eruptions and 13 are classified as "Fires", which include two or more eruptions defining an episode of volcanic activity that lasts for months to years. Of the 159 eruptions verified by identification of their products 124 are explosive, effusive eruptions are 14 and mixed eruptions are 21. Eruptions listed as reported-only are 33. Eight of the Fires are predominantly effusive and the remaining five include explosive activity that produced extensive tephra layers. The record indicates an average of 20-25 eruptions per century in Iceland, but eruption frequency has varied on time scale of decades. An apparent stepwise increase in eruption frequency is observed over the last 1100 years that reflects improved documentation of eruptive events with time. About 80% of the verified eruptions took place on the EVZ where the four most active volcanic systems (Grímsvötn, Bárdarbunga-Veidivötn, Hekla and Katla) are located and 9%, 5%, 1% and 0.5% on the RVZ-WVZ, NVZ, ÖVB, and SVB, respectively. Source volcano for ˜4.5% of the eruptions is not known. Magma productivity over 1100 years equals about 87 km 3 DRE with basaltic magma accounting for about 79% and intermediate and acid magma accounting for 16% and 5%, respectively. Productivity is by far highest on the EVZ where 71 km 3 (˜82%) were erupted, with three flood lava eruptions accounting for more than one half of that volume. RVZ-WVZ accounts for 13% of the magma and the NWZ and the

Thordarson, T.; Larsen, G.

2007-01-01

389

Adakitic volcanism in the eastern Aleutian arc: Petrology and geochemistry of Hayes volcano, Cook Inlet, Alaska  

NASA Astrophysics Data System (ADS)

Located in south-central Alaska, 135 km northwest of Anchorage, Hayes volcano is responsible for the most widespread tephra fall deposit in the regional Holocene record (~3,500 BP). Hayes is bounded to the west by the Cook Inlet volcanoes (CIV; Mt. Spurr, Redoubt, Iliamna, and Augustine) and separated from the nearest volcanism to the east, Mount Drum of the Wrangell Volcanic Field (WVF), by a 400 km-wide volcanic gap. We report initial results of the first systematic geochemical and petrologic study of Hayes volcano. Hayes eruptive products are calc-alkaline dacites and rhyolites that have anomalous characteristics within the region. Major and trace element analyses reveal that the Hayes rhyolites are more silicic (~74 wt. % SiO2) than compositions observed in other CIV, and its dacitic products possess the distinctive geochemical signatures of adakitic magmas. Key aspects of the Hayes dacite geochemistry include: 16.03 - 17.54 wt. % Al2O3, 0.97 - 2.25 wt. % MgO, Sr/Y = 60 - 78, Yb = 0.9 - 1.2 ppm, Ba/La = 31 - 79. Such signatures are consistent with melting of a metamorphosed basaltic source that leaves behind a residue of garnet ± amphibole ± pyroxene via processes such as melting of a subducting oceanic slab or underplated mafic lower crust, rather than flux melting of the mantle wedge by dehydration of the down-going slab. Additionally, Hayes tephras display a distinctive mineralogy of biotite with amphibole in greater abundance than pyroxene, a characteristic not observed at other CIV. Furthermore, Hayes rhyolites and dacites exhibit little isotopic heterogeneity (87Sr/86Sr = 0.70384 - 0.70395, 206Pb/204Pb = 18.866 - 18.889) suggesting these lavas originate from the same source. Hayes volcano is approximately situated above the western margin of the subducting Yakutat terrane and where the dip of the Pacific slab beneath Cook Inlet shallows northward. Due to its position along the margin of the subducting Yakutat terrane, it is plausible that Hayes magmas are the result of partial melting of this slab where thermal erosion and weakening of the crust occurs along the Pacific plate-Yakutat terrane transition. Additionally, flat slab subduction may be responsible for producing adakitic magmas by equilibration of the hydrous slab with ambient mantle temperatures. In contrast, it is possible that the adakitic signature at Hayes is from underplated mafic lower crust that melted as the result of pooling mantle melt at depth. Two volcanoes within the WVF, Mt. Drum and Mt. Churchill, are adakitic with an abundance of biotite and amphibole similar to Hayes volcano and have been suggested to have slab melt origins. Mt. Drum lavas have less radiogenic 87Sr/86Sr but overlapping 206Pb/204Pb signatures while Mt. Churchill, which approximately overlies the eastern edge of the Yakutat terrane, has similar 87Sr/86Sr compositions, but more radiogenic 206Pb/204Pb than Hayes. Mt. Spurr, the nearest CIV to Hayes volcano (90 km south), does not share its adakitic signature but exhibits overlapping, more heterogeneous isotopic compositions. Thus, understanding the petrogenetic history of Hayes volcano is essential not only to explain the development of an adakitic volcanic system but how this relates to regional, arc-wide volcanism.

McHugh, K.; Hart, W. K.; Coombs, M. L.

2012-12-01

390

Steady state volcanism - Evidence from eruption histories of polygenetic volcanoes  

Microsoft Academic Search

Cumulative volcano volume curves are presented as evidence for steady-state behavior at certain volcanoes and to develop a model of steady-state volcanism. A minimum criteria of five eruptions over a year was chosen to characterize a steady-state volcano. The subsequent model features a constant head of magmatic pressure from a reservoir supplied from depth, a sawtooth curve produced by the

G. Wadge

1982-01-01

391

Mapping the magma conduit for the Shinmoe-dake volcano  

NASA Astrophysics Data System (ADS)

Near the southern end of Kyushu, the most southerly of Japan's major islands, a complex of more than 20 small volcanoes together form the Kirishima volcanoes. In January 2011, approximately 20 million cubic meters of material spewed from one of the volcanoes, Shinmoe-dake. Before this most recent activity, Shinmoe-dake had previously erupted in 2010, 1991, 1962, and 1959, with the 2011 eruption being the biggest.

Schultz, Colin

2014-05-01

392

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

393

Seismic tomography at Popocatépetl volcano, Mexico  

Microsoft Academic Search

We performed the first 3D seismic tomography of the Popocatépetl volcano, Mexico, from the inversion of the P-wave arrival times of nearly 1500 earthquakes recorded by up to 11 seismic stations of the permanent CENAPRED-SSN network. We used the Bayesian tomographic algorithm developed by Monteiller et al. (2005) to perform this P-wave travel-time tomography and carefully choose optimal regularization hyper-parameters.

Pia Berger; Jean-Luc Got; Carlos Valdés González; Vadim Monteiller

2011-01-01

394

Volcaniclastic sedimentation on the submarine slopes of a basaltic hotspot volcano: Piton de la Fournaise volcano (La Runion Island, Indian Ocean)  

E-print Network

1 Volcaniclastic sedimentation on the submarine slopes of a basaltic hotspot volcano: Piton de la Fournaise volcano (La Réunion Island, Indian Ocean) Francky Saint-Ange a,b,d,*, Patrick Bachèlery c hotspot volcanoes as exemplified by the Piton de la Fournaise volcano (La Réunion Island). The facies

Paris-Sud XI, Université de

395

Long-term multi-hazard assessment for El Misti volcano (Peru)  

NASA Astrophysics Data System (ADS)

We propose a long-term probabilistic multi-hazard assessment for El Misti Volcano, a composite cone located <20 km from Arequipa. The second largest Peruvian city is a rapidly expanding economic centre and is classified by UNESCO as World Heritage. We apply the Bayesian Event Tree code for Volcanic Hazard (BET_VH) to produce probabilistic hazard maps for the predominant volcanic phenomena that may affect c.900,000 people living around the volcano. The methodology accounts for the natural variability displayed by volcanoes in their eruptive behaviour, such as different types/sizes of eruptions and possible vent locations. For this purpose, we treat probabilistically several model runs for some of the main hazardous phenomena (lahars, pyroclastic density currents (PDCs), tephra fall and ballistic ejecta) and data from past eruptions at El Misti (tephra fall, PDCs and lahars) and at other volcanoes (PDCs). The hazard maps, although neglecting possible interactions among phenomena or cascade effects, have been produced with a homogeneous method and refer to a common time window of 1 year. The probability maps reveal that only the north and east suburbs of Arequipa are exposed to all volcanic threats except for ballistic ejecta, which are limited to the uninhabited but touristic summit cone. The probability for pyroclastic density currents reaching recently expanding urban areas and the city along ravines is around 0.05 %/year, similar to the probability obtained for roof-critical tephra loading during the rainy season. Lahars represent by far the most probable threat (around 10 %/year) because at least four radial drainage channels can convey them approximately 20 km away from the volcano across the entire city area in heavy rain episodes, even without eruption. The Río Chili Valley represents the major concern to city safety owing to the probable cascading effect of combined threats: PDCs and rockslides, dammed lake break-outs and subsequent lahars or floods. Although this study does not intend to replace the current El Misti hazard map, the quantitative results of this probabilistic multi-hazard assessment can be incorporated into a multi-risk analysis, to support decision makers in any future improvement of the current hazard evaluation, such as further land-use planning and possible emergency management.

Sandri, Laura; Thouret, Jean-Claude; Constantinescu, Robert; Biass, Sébastien; Tonini, Roberto

2014-02-01

396

Preliminary Stratigraphy and Eruptive History of Salak Volcano, West Java, Indonesia  

NASA Astrophysics Data System (ADS)

Volcaniclastic deposits around Salak volcano, West Java, suggest a history of explosive eruptions and debris flows. Salak has historical unrest, fumaroles, and a large population in close proximity, yet the record of pre-historic eruptions of the volcano has previously remained relatively unknown. Lahar and pyroclastic-flow deposits with felsic pumice suggest that Salak erupted explosively at about 37.5 ka and 25 ka. The 37.5 ka deposits are present on all sides of the volcano, indicating a large eruption. Undated lahar and pyroclastic-flow deposits imply other eruptions have occurred. An undated tephra-fall deposit, delineated by weathered clasts with black cores and white rims, is present within several meters of the modern surface on all sides of the volcano, suggesting a relatively young explosive eruption. The tephra-fall deposit was probably originally felsic, but is now weathered to clay and no pumice remains. Debris-flow and hyperconcentrated-flow deposits lacking pumice or scoria are interspersed between the pumice-rich pyroclastic-flow and lahar deposits. Wood from one debris-flow deposit on the east flank of the volcano yielded an age of about 2 ka. The Cipinanggading and Ciapus rivers border a heavily populated fan at the north foot of Salak. The fan consists mainly of debris-flow deposits with interspersed hyperconcentrated-flow and stream-channel deposits. Wood from debris-flow deposits in the fan yielded ages as old as 4.5 ka, but the relatively smooth, boulder-covered fan surface suggests younger debris-flow deposits as well. Historical reports describe voluminous, earthquake-triggered landslides and debris-rich floods that descended Salak and inundated three drainages, including the Cipinanggading and Ciapus, in 1699 AD. Wood and bamboo from debris-flow deposits in the Ciapus and three other drainages yielded ages consistent with 1699 AD, suggesting that the flooding was even more wide spread than previously reported. The lack of pumice or scoria in the 1699 AD debris-flow deposits implies that accounts of a concurrent eruption are probably false, but ongoing work will confirm or refute this possible eruption. If the 1699 AD and earlier debris flows are not associated with eruptions, it suggests that voluminous debris flows are a threat during periods of quiescence as well as during unrest and eruptions.

Harpel, C.; Hendratno, K.

2011-12-01

397

Quantifying shapes of volcanoes on Venus  

NASA Technical Reports Server (NTRS)

A large population of discrete volcanic edifices on Venus has been identified and cataloged by means of Magellan SAR images, and an extensive database describing thousands of such features is in final preparation. Those volcanoes categorized as Intermediate to Large in scale, while relatively small in number (approx. 400), nonetheless constitute a significant volumetric component (approx. 13 x 10(exp 6) cu km) of the total apparent crustal volume of Venus. For this reason, we have focused attention on the morphometry of a representative suite of the larger edifices on Venus and, in particular, on ways of constraining the eruptive histories of these possibly geologically youthful landforms. Our approach has been to determine a series of reproducible morphometric parameters for as many of the discrete volcanoes on Venus that have an obvious expression within the global altimetry data acquired by Magellan. In addition, we have attempted to objectively and systematically define the mathematical essence of the shapes of these larger volcanoes using a polynomial cross-section approximation involving only parameters easily measured from digital topography, as well as with simple surface cylindrical harmonic expansions. The goal is to reduce the topological complexities of the larger edifices to a few simple parameters which can then be related to similar expressions for well-studied terrestrial and martian features.

Garvin, J. B.

1994-01-01

398

A Teachers Guide to the Geology of Hawaii Volcanoes National Park  

NSDL National Science Digital Library

This guide is designed for teachers, other educators, and anyone interested in volcanoes. Topics covered by this guide include plate tectonics, hot spots and mantle plumes, the evolution of Hawaiian volcanoes, volcanic landforms, landforms of Hawaii Volcanoes National Park, lava, tephra, calderas, pit craters, minerals, magma, volcanic rocks, monitoring volcanoes, eruption types and details about Kilauea. Although the guide focuses on Hawaiian volcanoes, similar processes and features are observed at volcanoes around the world.

Mattox, Stephen

399

Erosion and aggradation on persistently active volcanoes—a case study from Semeru Volcano, Indonesia  

NASA Astrophysics Data System (ADS)

Erosion processes on active volcanoes in humid climates result in some of the highest sediment yields on Earth. Episodic sediment yields after large eruptions have been evaluated, but not the long-term and continuous patterns on persistently active volcanoes. We have used high-spatial resolution satellite imagery and DEMs/DSMs along with field-based geologic mapping to assess accurately sediment budgets for the active Semeru Volcano in Java, Indonesia. Patterns of aggradation and degradation on Semeru differ from that of other active volcanoes because (1) both episodic pyroclastic density currents (PDC) and continuous supplies of tephra generate pulses of sediment, (2) sediment is transferred via cycles of aggradation and degradation that continue for >15 years in river channels after each PDC-producing eruption, and (3) rain-triggered lahars remove much greater material than fluvial transport during long, intense rainfall events. The geomorphic response of two of Semeru's rivers to volcanic sediment migration indicates that (1) each river experiences alternating aggradation and degradation cycles following PDC-producing eruptions and (2) spatial patterns of sediment transfer are governed by geomorphic characteristics of the river reaches. Usually high degradation in the steep source reach is followed by a long bypassing middle reach. Aggradation predominates in the depositional reaches further down valley on the ring plain. Average sediment yields (103-105 t/km2/year) at persistently active volcanoes are two to three orders of magnitude lower than sediment yields after large and infrequent eruptions, but the continuous and steady sediment transfer in rivers removes more sediment on a mid-term (10 years) to long-term (30 years) basis. In contrast to the trend observed on composite cones after large and infrequent eruptions, decay of sediment yields is not exponential and river channels do not fully recover at steadily active volcanoes as episodic inputs from BAF eruptions, superimposed on the background remobilization of daily tephra, have a greater cumulative effect.

Thouret, Jean-Claude; Oehler, Jean-François; Gupta, Avijit; Solikhin, Akhmad; Procter, Jonathan N.

2014-10-01

400

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

401

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

402

Geochemistry of the volcano-hydrothermal system of El Chichón Volcano, Chiapas, Mexico  

Microsoft Academic Search

The 1982 eruption of El Chichón volcano ejected more than 1?km3 of anhydrite-bearing trachyandesite pyroclastic material to form a new 1-km-wide and 300-m-deep crater and uncovered the\\u000a upper 500?m of an active volcano-hydrothermal system. Instead of the weak boiling-point temperature fumaroles of the former\\u000a lava dome, a vigorously boiling crater spring now discharges ?\\/?20?kg\\/s of Cl-rich (?15?000?mg\\/kg) and sulphur-poor (?\\/?200?mg\\/kg

Yuri Taran; Tobias P. Fischer; Boris Pokrovsky; Yuji Sano; Maria Aurora Armienta; Jose Luis Macias

1998-01-01

403

Seismic Monitoring studies at Popocatepetl volcano, México  

NASA Astrophysics Data System (ADS)

We present the analysis of seven months of continuous record (March-September, 2012) of the seismic monitoring of Popocatépetl volcano in four broad band stations (the maximum aperture is 12 km). The aim is to explore whether the seismic interferometry method provides complimentary information about the tectonic stress before eruptive stages. In that period of time several eruptive events have occurred. One of them was a subduction-related earthquake (March, 20, 2012, M=7.4) that produced an increase in the volcanic activity. On March 30 the volcano registered a train of 10 hours of exhalations and from March 11 to 29 a swarm of 15 volcanotectonic events. Another important event lasted from April 13 to June 3, in which around 276 hours of harmonic and spasmodic tremor were recorded. One of the biggest events was on May 11, a volcano emissions of around 4 km above the crater with incandescent fragments falling on the volcano slope. From March to September 90 volcanotectonic events were registered the biggest occurred on April 14 and July 23 with Mc=3.2 and 2.9 respectively. Also we analyze the volcano activity with the SSEM analysis, which can be related with regional tectonic earthquakes. We take advantage of seismic noise to get daily correlograms for each motion component (Z, R, T) by stacking 40s time windows. We observe that there are consecutive days for which it is not possible to obtain correlations between pairs of stations, probably caused by instrumental problems or variations in absolute time. Between the nearest stations, 4 km on average, we get consistent correlations, but not in the days of major volcanic activity. The similarity between the Z and R correlograms indicate an appropriate extraction of Rayleigh waves, while in the T component we have the Love wave. Over longer distances it is not possible to extract the dispersion properties; however, the loss of correlation prevails for those days of increased activity. It is important to mention that some locations of volcanotectonic events match the areas where the correlation was lost.

Reyes Pimentel, T. A.; Cárdenas-Soto, M.

2013-05-01

404

Alaska Volcano Observatory Seismic Network Data Availability  

NASA Astrophysics Data System (ADS)

The Alaska Volcano Observatory (AVO) established in 1988 as a cooperative program of the U.S. Geological Survey, the Geophysical Institute at the University of Alaska Fairbanks, and the Alaska Division of Geological and Geophysical Surveys, monitors active volcanoes in Alaska. Thirty-three volcanoes are currently monitored by a seismograph network consisting of 193 stations, of which 40 are three-component stations. The current state of AVO’s seismic network, and data processing and availability are summarized in the annual AVO seismological bulletin, Catalog of Earthquake Hypocenters at Alaska Volcanoes, published as a USGS Data Series (most recent at http://pubs.usgs.gov/ds/467). Despite a rich seismic data set for 12 VEI 2 or greater eruptions, and over 80,000 located earthquakes in the last 21 years, the volcanic seismicity in the Aleutian Arc remains understudied. Initially, AVO seismic data were only provided via a data supplement as part of the annual bulletin, or upon request. Over the last few years, AVO has made seismic data more available with the objective of increasing volcano seismic research on the Aleutian Arc. The complete AVO earthquake catalog data are now available through the annual AVO bulletin and have been submitted monthly to the on-line Advanced National Seismic System (ANSS) composite catalog since 2008. Segmented waveform data for all catalog earthquakes are available upon request and efforts are underway to make this archive web accessible as well. Continuous data were first archived using a tape backup, but the availability of low cost digital storage media made a waveform backup of continuous data a reality. Currently the continuous AVO waveform data can be found in several forms. Since late 2002, AVO has burned all continuous waveform data to DVDs, as well as storing these data in Antelope databases at the Geophysical Institute. Beginning in 2005, data have been available through a Winston Wave Server housed at the USGS in Anchorage. AVO waveform data were added to the Incorporated Research Institutions for Seismology Data Management Center (IRIS-DMC) beginning in 2008 and now includes continuous waveform data from all available AVO seismograph stations in real time. Data coverage is available through the DMC’s Metadata Aggregator.

Dixon, J. P.; Haney, M. M.; McNutt, S. R.; Power, J. A.; Prejean, S. G.; Searcy, C. K.; Stihler, S. D.; West, M. E.

2009-12-01

405

Asymmetric deformation structure of lava spine in Unzen Volcano, Japan  

NASA Astrophysics Data System (ADS)

Lava spine is commonly generated by effusive eruption of crystal-rich, dacitic-andesitic magmas. Especially, deformation rock on surface of lava spine has been related with processes of magma ascent, outgassing, and generation of volcanic earthquake (e.g., Cashman et al. 2008). To reveal the relationships and generation process of the spine, it is needed to understand a spatial distribution of the deformation rock. Here we show the spatial distribution of the deformation rock of lava spine in the Unzen volcano, Japan, to discuss the generation process of the spine. The lava spine in Unzen volcano is elongated in the E-W direction, showing a crest like shape with 150 long, 40 m wide and 50 m high. The lava spine is divided into following four parts: 1) Massive dacite part: Dense dacite with 30 m of maximum thickness, showing slickenside on the southern face; 2) Sheared dacite part: Flow band developed dacite with 1.0 m of maximum thickness; 3) Tuffisite part: Network of red colored vein develops in dacite with 0.5 m of maximum thickness; 4) Breccia part: Dacitic breccia with 10 m of maximum thickness. The Breccia part dominates in the northern part of the spine, and flops over Massive dacite part accross the Sheared dacite and Tuffisite parts. The slickenside on southern face of massive dacite demonstrates contact of solids. The slickenside breaks both of phenocryst and groundmass, demonstrating that the slickenside is formed after significant crystallization at the shallow conduit or on the ground surface. The lineation of the slickenside shows E-W direction with almost horizontal rake angle, which is consistent with the movement of the spine to an east before emplacement. Development of sub-vertical striation due to extrusion was observed on northern face of the spine (Hayashi, 1994). Therefore, we suggest that the spine just at extrusion consisted of Massive dacite, Sheared dacite, Tuffisite, Breccia, and Striation parts in the northern half of the spine. Such a variation of rock type is analogous to tectonic fault zone, suggesting that brittle failure of rigid magma due to contact with the conduit wall. Also similar variation is observed in the spine of Mt. St. Helens (Kendrick et al., 2012), which implies the existence of fault zone and brittle failure of magma are common features in the lava spine. The lava spine in Unzen volcano exhibits asymmetric deformation structure about direction of north and south. There is positive correlation between width and length in tectonic fault (Wells and Coppersmith, 1994). Therefore, development of fault zone (Sheared dacite, Tuffisite, and Breccia parts) in northern half may indicate that brittle failure starts at the deeper conduit for the northern half than the southern half of the spine. The asymmetry of magma ascent process is possible to result in asymmetries of outgassing path and location of volcanic earthquake in the conduit.

Miwa, T.; Okumura, S.; Matsushima, T.; Shimizu, H.

2013-12-01

406

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

407

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

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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 descript