These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

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

2

Long-term eruptive activity at a submarine arc volcano  

USGS Publications Warehouse

Three-quarters of the Earth's volcanic activity is submarine, located mostly along the mid-ocean ridges, with the remainder along intraoceanic arcs and hotspots at depths varying from greater than 4,000 m to near the sea surface. Most observations and sampling of submarine eruptions have been indirect, made from surface vessels or made after the fact. We describe here direct observations and sampling of an eruption at a submarine arc volcano named NW Rota-1, located 60 km northwest of the island of Rota (Commonwealth of the Northern Mariana Islands). We observed a pulsating plume permeated with droplets of molten sulphur disgorging volcanic ash and lapilli from a 15-m diameter pit in March 2004 and again in October 2005 near the summit of the volcano at a water depth of 555 m (depth in 2004). A turbid layer found on the flanks of the volcano (in 2004) at depths from 700 m to more than 1,400 m was probably formed by mass-wasting events related to the eruption. Long-term eruptive activity has produced an unusual chemical environment and a very unstable benthic habitat exploited by only a few mobile decapod species. Such conditions are perhaps distinctive of active arc and hotspot volcanoes. ?? 2006 Nature Publishing Group.

Embley, R. W.; Chadwick, Jr. , W. W.; Baker, E. T.; Butterfield, D. A.; Resing, J. A.; De Ronde, C. E. J.; Tunnicliffe, V.; Lupton, J. E.; Juniper, S. K.; Rubin, K. H.; Stern, R. J.; Lebon, G. T.; Nakamura, K. -I.; Merle, S. G.; Hein, J. R.; Wiens, D. A.; Tamura, Y.

2006-01-01

3

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

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

4

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

5

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

6

Potential cauchy-poisson waves generated by submarine eruptions of kick 'em Jenny volcano  

Microsoft Academic Search

Kick 'em Jenny is the only known currently active submarine volcano in the Lesser Antilles. The volcano has erupted at least 10 times since first being discovered in 1939 and the summit has shoaled from a depth of ~232 m in 1962 to its present-day depth of ~150 m. Kick 'em Jenny is located in a province of explosive volcanism,

M. S. Smith; J. B. Shepherd

1995-01-01

7

Physical volcanology of the submarine Mariana and Volcano Arcs  

NASA Astrophysics Data System (ADS)

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 the Mariana Arc tend to be simple cones. Sets of individual cones and volcanic ridges are elongate parallel to the trend of the arc or at 110° counterclockwise from that trend, suggesting a strong fault control on the distribution of arc magmas. Volcanos in the Mariana Arc are generally developed west of the frontal arc ridge, on rifted frontal arc crust or new back-arc basin crust. Volcanos in the central Mariana Arc are usually subaerial, large (> 500 km3), and spaced about 50 70 km apart. Those in the northern and southern Marianas are largely submarine, closer together, and generally less than 500 km3 in volume. There is a shoaling of the arc basement around Iwo Jima, accompanied by the appearance of incompatible-element enriched lavas with alkalic affinities. The larger volcanic edifices must reflect either a higher magma supply rate or a greater age for the larger volcanos. If the magma supply (estimated at 10 20 km3/km of arc per million years at 18° N) has been relatively constant along the Mariana Arc, we can infer a possible evolutionary sequence for arc volcanos from small, irregularly spaced edifices to large (over 1000 km3) edifices spaced at 50 70 km. The volcano distribution and basal depths are consistent with the hypothesis of back-arc propagation into the Volcano Arc.

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

1989-05-01

8

Potential-field modeling of collapse-prone submarine volcanoes in the southern Tyrrhenian Sea (Italy)  

NASA Astrophysics Data System (ADS)

Hydrothermal alteration may weaken volcanic rocks, causing the gravitational instability of portions of active volcanoes with potentially hazardous collapses. Here we show high-resolution multibeam, magnetic and gravity surveys of the Marsili seamount, the largest active volcano of Europe located in the southern Tyrrhenian back-arc basin. These surveys reveal zones with exceptionally low densities and with vanishing magnetizations, due probably to the comminution of basalts during hyaloclastic submarine eruptions and to their post-eruptive hydrothermal alteration. The location of these regions correlates with morphological data showing the occurrence of past collapses. Similar evidence has been obtained from pre-existing data at Vavilov Seamount, another older volcanic system in the Tyrrhenian back-arc basin. Here a large volume of at least 50 km3 may have collapsed in a single event from its 40 km long western flank. Given the similarities between these volcanoes, a large collapse event may also be expected at Marsili.

Caratori Tontini, F.; Cocchi, L.; Muccini, F.; Carmisciano, C.; Marani, M.; Bonatti, E.; Ligi, M.; Boschi, E.

2010-02-01

9

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

E-print Network

that 67% of the volcano's submarine flanks are covered with volcaniclastic debris and 26% is lava flows volcanoes may be characterized by sediment flows of unconsolidated volcaniclastic debris instead of mass and the spring of 2004. This was part of the Submarine Ring of Fire project, which is a multi-year study

Chadwick, Bill

10

Near-specular acoustic scattering from a buried submarine mud volcano.  

PubMed

Submarine mud volcanoes are objects that form on the seafloor due to the emission of gas and fluidized sediment from the Earth's interior. They vary widely in size, can be exposed or buried, and are of interest to the underwater acoustics community as potential sources of active sonar clutter. Coincident seismic reflection data and low frequency bistatic scattering data were gathered from one such buried mud volcano located in the Straits of Sicily. The bistatic data were generated using a pulsed piston source and a 64-element horizontal array, both towed over the top of the volcano. The purpose of this work was to appropriately model low frequency scattering from the volcano using the bistatic returns, seismic bathymetry, and knowledge of the general geoacoustic properties of the area's seabed to guide understanding and model development. Ray theory, with some approximations, was used to model acoustic propagation through overlying layers. Due to the volcano's size, scattering was modeled using geometric acoustics and a simple representation of volcano shape. Modeled bistatic data compared relatively well with experimental data, although some features remain unexplained. Results of an inversion for the volcano's reflection coefficient indicate that it may be acoustically softer than expected. PMID:18247739

Gerig, Anthony L; Holland, Charles W

2007-12-01

11

Remote Analysis of Grain Size Characteristic in Submarine Pyroclastic Deposits from Kolumbo Volcano, Greece  

NASA Astrophysics Data System (ADS)

Grain size characteristics of pyroclastic deposits provide valuable information about source eruption energetics and depositional processes. Maximum size and sorting are often used to discriminate between fallout and sediment gravity flow processes during explosive eruptions. In the submarine environment the collection of such data in thick pyroclastic sequences is extremely challenging and potentially time consuming. A method has been developed to extract grain size information from stereo images collected by a remotely operated vehicle (ROV). In the summer of 2010 the ROV Hercules collected a suite of stereo images from a thick pumice sequence in the caldera walls of Kolumbo submarine volcano located about seven kilometers off the coast of Santorini, Greece. The highly stratified, pumice-rich deposit was likely created by the last explosive eruption of the volcano that took place in 1650 AD. Each image was taken from a distance of only a few meters from the outcrop in order to capture the outlines of individual clasts with relatively high resolution. Mosaics of individual images taken as the ROV transected approximately 150 meters of vertical outcrop were used to create large-scale vertical stratigraphic columns that proved useful for overall documentation of the eruption sequence and intracaldera correlations of distinct tephra units. Initial image processing techniques, including morphological operations, edge detection, shape and size estimation were implemented in MatLab and applied to a subset of individual images of the mosiacs. A large variety of algorithms were tested in order to best discriminate the outlines of individual pumices. This proved to be challenging owing to the close packing and overlapping of individual pumices. Preliminary success was achieved in discriminating the outlines of the large particles and measurements were carried out on the largest clasts present at different stratigraphic levels. In addition, semi-quantitative analysis of the size distribution could also be determined for individual images. Although a complete size distribution is not possible with this technique, information about the relative distribution of large and medium size clasts is likely to provide a reasonable proxy for the overall sorting of submarine deposits. Our preliminary work represents the first attempt to carry out an in situ granulometric analysis of a thick submarine pyroclastic sequence. This general technique is likely to be valuable in future studies of submarine explosive volcanism given the recent discoveries of extensive pumiceous deposits in many submarine calderas associated with subduction zone environments.

Smart, C.; Whitesell, D. P.; Roman, C.; Carey, S.

2011-12-01

12

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

13

Distribution of tephra from the 1650 AD submarine eruption of Kolumbo volcano, Greece  

NASA Astrophysics Data System (ADS)

Kolumbo submarine volcano, located 7 km northeast of Santorini in the Aegean Sea, last erupted in 1650 AD resulting in about 70 fatalities on Thera from gas discharge and significant coastal destruction from tsunamis. Extensive pumice rafts were reported over a large area surrounding Santorini, extending as far south as Crete. Tephra from the 1650 AD submarine eruption has been correlated in sediment box cores using a combination of mineralogy and major element composition of glass shards. The biotite-bearing rhyolite of Kolumbo can be readily discriminated from other silicic pyroclastics derived from the main Santorini complex. In general the tephra deposits are very fine grained (silt to fine sand-size), medium gray in color, and covered by about 10 cms of brown hemipelagic sediment. This corresponds to an average background sedimentation rate of 29 cm/kyr. The distribution of the 1650 AD Kolumbo tephra extends over an area larger than previously inferred from seismic profiles on the volcano's slopes and in adjacent basins. The cores indicate tephra deposits at least 19 km from the caldera, more than double the approximate 9 km inferred from seismic data. The preferential occurrence of the tephra within basins and sedimentological features such as cross bedding and laminations suggests that emplacement was dominated by sediment gravity flows generated from submarine and subaerial eruption plumes. We suggest that generation of the sediment gravity flows took place by collapse of submarine eruption columns and by Rayleigh-Taylor instabilities that formed on the sea surface as subaerial fallout accumulated from parts of the columns that breached the surface. Additionally, SEM imaging reveals particle morphologies that can be attributed to fragmentation by both primary volatile degassing (bubble wall shards) and phreatomagmatic activity (blocky equant grains). It is likely that phreatomagmatic activity became more important in the latter stages of the eruptive sequence when eruptions columns broke the surface and a small ephemeral island was formed. The fine grain marine tephra deposits surrounding Kolumbo represent the compliment to the very fines-poor proximal pumice sequence exposed in the crater walls and demonstrates the very effective fractionation of fine tephra that can take place during explosive submarine eruptions.

Fuller, S. A.; Carey, S.; Nomikou, P.

2013-12-01

14

Submarine Strombolian Eruptions Observed at NW Rota1 Volcano, Mariana Arc  

Microsoft Academic Search

Extraordinary video and hydrophone observations of a submarine explosive eruption were made with a remotely operated vehicle in April 2006 at a depth of 550-560 m on NW Rota-1, a conical, basaltic-andesite submarine volcano in the Mariana arc. The observed eruption evolved from effusive to explosive, while the eruption rate increased from near zero to 10-100 m3\\/hr. During the peak

W. W. Chadwick; K. V. Cashman; R. W. Embley; R. P. Dziak; C. de Ronde; H. Matsumoto; N. Deardorff; S. G. Merle

2007-01-01

15

Bubble Plumes above erupting NW Rota-1 submarine volcano, Mariana Arc  

NASA Astrophysics Data System (ADS)

NW Rota-1 is a submarine volcano in the Mariana volcanic arc with a summit depth of 517 m, located ~100 km north of Guam. Underwater explosive eruptions driven by magmatic gases were first witnessed here in 2004 and the volcano has remained persistently active ever since. During a March 2010 expedition to NW Rota-1 with the remotely operated vehicle Jason, we observed intermittent explosive activity at five distinct eruptive vents along a line 100-m long near the summit of the volcano (550-590 m depth). The continuous but variable eruptive activity produced CO2 bubble plumes that rose in the water column over the volcano and could be readily imaged by sonar because they provide excellent acoustic reflectors. This study compares the manifestations of NW Rota's eruptive activity as measured by several independent methods, including: (1) an EM122 multibeam sonar system (12 kHz) on the R/V Kilo Moana that imaged bubble plumes in the water column over the volcano, (2) hydrophone data that recorded the sounds of the variable eruptive activity, and (3) visual observations of the activity at the eruptive vents on the seafloor from Jason. Throughout the 2010 expedition numerous passes were made over the volcano's summit to image the bubble plumes with the EM122 multibeam sonar, in order to capture the variability of the plumes over time and to relate them to the eruptive output of the volcano. The mid-water sonar dataset totals >95 hours of observations over a 12-day period. Analysis of the EM122 dataset shows: (1) bubble plumes were visible in the water column on every pass over the summit, (2) separate plumes were resolvable from up to 4 of the 5 eruptive vents at times, (3) plume heights and intensities were variable with time, (4) the highest observed bubble plume rise height was 415 meters above the seafloor to within 175 m of the ocean surface, while lower amplitude wisps rose to heights <100 m from the surface, (5) most of the bubble plumes were deflected to the WSW in the prevailing current. We will compare these bubble plume results to the time-series of eruptive intensity as measured by the hydrophone recordings, with ground-truth provided by the Jason visual observations at the eruptive vents. This will show to what extent the variability of eruptive output observed on the seafloor is reflected in the plume dynamics. We will also compare ocean current data from the ship's acoustic doppler current profiling (ADCP) sonar to the distance and direction of deflection of the bubble plumes. These data will be used to test whether multibeam-sonar water-column data can be used as a proxy to determine the level of eruptive activity above submarine volcanoes that have robust CO2 output. We also plan to compare these results with independent quantitative CO2 flux estimates made from the hydrophone data.

Chadwick, B.; Merle, S. G.; Embley, R. W.; Buck, N.; Resing, J. A.; Leifer, I.

2013-12-01

16

Gas flux measurements from a year-long hydroacoustic record at an erupting submarine volcano  

NASA Astrophysics Data System (ADS)

The output of gas and tephra from volcanoes is an inherently disorganized process that makes reliable flux estimates challenging to obtain. Continuous monitoring of CO2 flux has been achieved in only a few instances at subaerial volcanoes, but never for submarine volcanoes. Here we use the first sustained (year-long) hydroacoustic monitoring of an erupting submarine volcano (NW Rota-1, Mariana island-arc) to make the first calculations of total gas flux from a volcano into the ocean. Bursts of Strombolian explosive degassing at the volcano summit (520 m deep) occurred at 1-2 minute intervals during the entire 12-month hydrophone record and commonly exhibited cyclic step-function changes between high and low intensity. The explosion bursts are comprised of hundreds of individual (100-200 ms duration) explosion pulses totaling ~12.7M discrete pulses recorded during the year. The acoustic explosion packets are broadband: 1-80 Hz with a peak at 30 Hz. The loudest explosions occurred during February-August 2008 with a typical sound level of 192 dBrms re ?Pa2/Hz @ 1m, equal to ~100 W of acoustic power. Total gas flux calculated from the hydroacoustic record, 5.4 ± 0.6 Tg a-1, combined with melt inclusion information, yields an annual CO2 eruption flux of 0.4 ± 0.1 Tg a-1. This result is consistent with measured CO2 fluxes at continuously erupting subaerial volcanoes (~0.5 Tg a-1), and represents ~0.2-0.6% of the annual estimated output of CO2 from all subaerial arc volcanoes. The multi-year eruptive history of NW Rota-1 demonstrates that submarine volcanoes can be significant and sustained sources of CO2 to the shallow ocean.

Dziak, R. P.; Baker, E. T.; Shaw, A. M.; Bohnenstiehl, D. R.; Chadwick, B.; Haxel, J. H.; Matsumoto, H.; Walker, S. L.

2011-12-01

17

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

18

Shoshonitic magmas in nascent arcs: New evidence from submarine volcanoes in the northern Marianas  

Microsoft Academic Search

Volcanoes in the northern Mariana arc between Uracas (lat 20°N) and Minami Iwo Jima (24°N) are very active yet entirely submarine. In contrast to the predominantly low-K basaltic magmas of the central Mariana arc, the northern Mariana arc is dominated by more siliceous melts in the south and by shoshonites in the north. The northern arc melts have enrichments in

Robert J. Stern; Sherman H. Bloomer; Ping-Nan Lin; Emi Ito; Julie Morris

1988-01-01

19

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

20

Rapid mass wasting following nearshore submarine volcanism on Kilauea volcano, Hawaii  

Microsoft Academic Search

The rapid mass wasting of shallow submarine basalts was documented during SCUBA dives along the flanks of Kilauea volcano, Hawaii during the Kii lava entry of the current eruption (19°20.5?N, 154°59.8?W). Lava entered the ocean at this site from mid-February to late March 1990, with several pauses. Dives on 19–20 March 1990 confirmed the widespread formation of lava pillows at

Francis J. Sansone; John R. Smith

2006-01-01

21

The submarine eruption of the Bombarda volcano, Milos Island, Cyclades, Greece  

Microsoft Academic Search

The Milos volcanic field includes a well-exposed volcaniclastic succession which records a long history of submarine explosive\\u000a volcanism. The Bombarda volcano, a rhyolitic monogenetic center, erupted ?1.7 Ma at a depth <200 m below sea level. The aphyric\\u000a products are represented by a volcaniclastic apron (up to 50 m thick) and a lava dome. The apron is composed of pale

M. Rinaldi; M. Campos Venuti

2003-01-01

22

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

23

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

24

Sector collapse at Kick 'em Jenny submarine volcano (Lesser Antilles): numerical simulation and landslide behaviour  

NASA Astrophysics Data System (ADS)

Kick 'em Jenny volcano is the only known active submarine volcano in the Lesser Antilles. It lies within a horseshoe-shaped structure open to the west northwest, toward the deep Grenada Basin. A detailed bathymetric survey of the basin slope at Kick 'em Jenny and resulting high-resolution digital elevation model allowed the identification of a major submarine landslide deposit. This deposit is thought to result from a single sector collapse event at Kick 'em Jenny and to be linked to the formation of the horseshoe-shaped structure. We estimated the volume and the leading-edge runout of the landslide to be ca. 4.4 km3 and 14 km, respectively. We modelled a sector collapse event of a proto Kick 'em Jenny volcano using VolcFlow, a finite difference code based on depth-integrated mass and momentum equations. Our models show that the landslide can be simulated by either a Coulomb-type rheology with low basal friction angles (5.5°-6.5°) and a significant internal friction angle (above 17.5°) or, with better results, by a Bingham rheology with low Bingham kinematic viscosity (0 < ? B < 30 m2/s) and high shear strength (130 < ? ? 180 m2/s2). The models and the short runout distance suggest that the landslide travelled as a stiff cohesive flow affected by minimal granular disaggregation and slumping on a non-lubricated surface. The main submarine landslide deposit can therefore be considered as a submarine mass slide deposit that behaved like a slump.

Dondin, Frédéric; Lebrun, Jean-Frédéric; Kelfoun, Karim; Fournier, Nicolas; Randrianasolo, Auran

2012-03-01

25

Research Article Evolution of West Rota Volcano, an extinct submarine volcano in the  

E-print Network

.33­0.55 my ago, whereas eruption of the upper rhyolites and basalts occurred 37­51 thousand years ago. Four sequences of rhyolite pyroclastics each are 20­75 m thick, unwelded and show reverse grading, indicating submarine eruption. The youngest unit consists of 1­2 m diam- eter spheroids of rhyolite pumice, interpreted

Stern, Robert J.

26

Submarine geology of Hana Ridge and Haleakala Volcano's northeast flank, Maui  

NASA Astrophysics Data System (ADS)

We present a morphostructural analysis of the submarine portions of Haleakala Volcano and environs, based upon a 4-year program of geophysical surveys and submersible explorations of the underwater flanks of Hawaiian volcanoes that was conducted by numerous academic and governmental research organizations in Japan and the U.S. and funded primarily by the Japan Agency for Marine-Earth Science and Technology. A resulting reconnaissance geologic map features the 135-km-long Hana Ridge, the 3000 km 2 Hana slump on the volcano's northeast flank, and island-surrounding terraces that are the submerged parts of volcanic shields. Hana Ridge below 2000 m water depth exhibits the lobate morphology typical of the subaqueously erupted parts of Hawaiian rift zones, with some important distinctions: namely, subparallel crestlines, which we propose result from the down-rift migration of offsets in the dike intrusion zone, and an amphitheater at its distal toe, where a submarine landslide has embayed the ridge tip. Deformation of Haleakala's northeast flank is limited to that part identified as the Hana slump, which lies downslope from the volcano's submerged shield, indicating that flank mobility is also limited in plan, inconsistent with hypothesized volcanic spreading driven by rift-zone dilation. The leading edge of the slump has transverse basins and ridges that resemble the thrust ramps of accretionary prisms, and we present a model to describe the slump's development that emphasizes the role of coastally generated fragmental basalt on gravitational instability of Haleakala's northeast flank and that may be broadly applicable to other ocean-island slumps.

Eakins, Barry W.; Robinson, Joel E.

2006-03-01

27

Geochemistry of Post-shield Lavas and Submarine Tholeiites from the Kea and Loa Trends of Hawaiian Volcanoes  

Microsoft Academic Search

We present high-precision isotopic ratios (MC-ICP-MS) and trace element concentrations (HR-ICP-MS) of post-shield lavas and submarine tholeiites from two paired sequences of Hawaiian volcanoes: Mauna Kea and Kohala on the Kea trend, and Hualalai and Mahukona on the Loa trend. Post-shield lavas from Hualalai have some of the least radiogenic Pb isotopic compositions of recent Hawaiian volcanoes (206Pb\\/204Pb = 17.888-18.011)

D. Hanano; D. Weis; S. Aciego; J. S. Scoates; D. J. Depaolo

2006-01-01

28

New insights into hydrothermal vent processes in the unique shallow-submarine arc-volcano, Kolumbo (Santorini), Greece.  

PubMed

We report on integrated geomorphological, mineralogical, geochemical and biological investigations of the hydrothermal vent field located on the floor of the density-stratified acidic (pH ~ 5) crater of the Kolumbo shallow-submarine arc-volcano, near Santorini. Kolumbo features rare geodynamic setting at convergent boundaries, where arc-volcanism and seafloor hydrothermal activity are occurring in thinned continental crust. Special focus is given to unique enrichments of polymetallic spires in Sb and Tl (±Hg, As, Au, Ag, Zn) indicating a new hybrid seafloor analogue of epithermal-to-volcanic-hosted-massive-sulphide deposits. Iron microbial-mat analyses reveal dominating ferrihydrite-type phases, and high-proportion of microbial sequences akin to "Nitrosopumilus maritimus", a mesophilic Thaumarchaeota strain capable of chemoautotrophic growth on hydrothermal ammonia and CO2. Our findings highlight that acidic shallow-submarine hydrothermal vents nourish marine ecosystems in which nitrifying Archaea are important and suggest ferrihydrite-type Fe(3+)-(hydrated)-oxyhydroxides in associated low-temperature iron mats are formed by anaerobic Fe(2+)-oxidation, dependent on microbially produced nitrate. PMID:23939372

Kilias, Stephanos P; Nomikou, Paraskevi; Papanikolaou, Dimitrios; Polymenakou, Paraskevi N; Godelitsas, Athanasios; Argyraki, Ariadne; Carey, Steven; Gamaletsos, Platon; Mertzimekis, Theo J; Stathopoulou, Eleni; Goettlicher, Joerg; Steininger, Ralph; Betzelou, Konstantina; Livanos, Isidoros; Christakis, Christos; Bell, Katherine Croff; Scoullos, Michael

2013-01-01

29

Shoshonitic magmas in nascent arcs: New evidence from submarine volcanoes in the northern Marianas  

NASA Astrophysics Data System (ADS)

Volcanoes in the northern Mariana arc between Uracas (lat 20°N) and Minami Iwo Jima (24°N) are very active yet entirely submarine. In contrast to the predominantly low-K basaltic magmas of the central Mariana arc, the northern Mariana arc is dominated by more siliceous melts in the south and by shoshonites in the north. The northern arc melts have enrichments in Ba (<800 ppm), Rb (<70 ppm), Sr (<1000 ppm), Ce (<50 ppm), and (Ce/Yb)n (<24) which increase to the north as far as Iwo Jima. Lavas from volcanoes north of Iwo Jima lack these enrichments and are indistinguishable from those of the central Maranas. The shoshonites are unusual in occurring along the magmatic front of a primitive, intra-oceanic arc. We hypothesize that they represent the reconstruction of a magmatic arc following melting of enriched mantle due to the propagation of the Mariana Trough spreading center northward through the Volcano arc. Shoshonites thus may characterize the initial stages of arc construction after an episode of back-arc rifting and need not be restricted to the mature stages of arc evolution. This situation contrasts with subduction-zone initiation, where first melts may be boninites or low-K tholeiites. These differing initial melts converge toward tholeiitic and calc-alkaline compositions as arcs evolve.

Stern, Robert J.; Bloomer, Sherman H.; Lin, Ping-Nan; Ito, Emi; Morris, Julie

1988-05-01

30

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

31

North Kona slump: Submarine flank failure during the early(?) tholeiitic shield stage of Hualalai Volcano  

USGS Publications Warehouse

The North Kona slump is an elliptical region, about 20 by 60 km (1000-km2 area), of multiple, geometrically intricate benches and scarps, mostly at water depths of 2000-4500 m, on the west flank of Hualalai Volcano. Two dives up steep scarps in the slump area were made in September 2001, using the ROV Kaiko of the Japan Marine Science and Technology Center (JAMSTEC), as part of a collaborative Japan-USA project to improve understanding of the submarine flanks of Hawaiian volcanoes. Both dives, at water depths of 2700-4000 m, encountered pillow lavas draping the scarp-and-bench slopes. Intact to only slightly broken pillow lobes and cylinders that are downward elongate dominate on the steepest mid-sections of scarps, while more equant and spherical pillow shapes are common near the tops and bases of scarps and locally protrude through cover of muddy sediment on bench flats. Notably absent are subaerially erupted Hualalai lava flows, interbedded hyaloclastite pillow breccia, and/or coastal sandy sediment that might have accumulated downslope from an active coastline. The general structure of the North Kona flank is interpreted as an intricate assemblage of downdropped lenticular blocks, bounded by steeply dipping normal faults. The undisturbed pillow-lava drape indicates that slumping occurred during shield-stage tholeiitic volcanism. All analyzed samples of the pillow-lava drape are tholeiite, similar to published analyses from the submarine northwest rift zone of Hualalai. Relatively low sulfur (330-600 ppm) and water (0.18-0.47 wt.%) contents of glass rinds suggest that the eruptive sources were in shallow water, perhaps 500-1000-m depth. In contrast, saturation pressures calculated from carbon dioxide concentrations (100-190 ppm) indicate deeper equilibration, at or near sample sites at water depths of -3900 to -2800 m. Either vents close to the sample sites erupted mixtures of undegassed and degassed magmas, or volatiles were resorbed from vesicles during flowage downslope after eruption in shallow water. The glass volatile compositions suggest that the tholeiitic lavas that drape the slump blocks were erupted either (1) early during shield-stage tholeiitic volcanism prior to emergence of a large subaerial edifice, or alternatively (2) from submarine radial vents during subaerial shield-building. Because no radial vents have been documented on land or underwater for the unbuttressed flanks of any Hawaii volcano, alternative (1) is favored. In comparison to other well-documented Hawaiian slumps and landslides, North Kona structures suggest a more incipient slump event, with smaller down-slope motions and lateral displacements.

Lipman, P.W.; Coombs, M.L.

2006-01-01

32

Direct Observations of Explosive Eruptive Activity at a Submarine Volcano, NW Rota-1, Mariana Arc  

NASA Astrophysics Data System (ADS)

In April 2006, a series of extraordinary observations of a deep-sea volcanic eruption were made at NW Rota-1, located at 14^{circ}36'N in the Mariana arc, western Pacific. This is a conical, basaltic-andesite submarine volcano with a summit depth of 517 m. Explosive eruptive activity at NW Rota-1 was discovered in 2004 and was witnessed again in 2005, but the activity in 2006 was especially vigorous and well documented. During six dives with the remotely operated vehicle Jason II over a period of 7 days, video observations made at close range documented a diverse and increasingly energetic range of volcanic activity that culminated in explosive bursts with flashes of glowing red lava propelled by violently expanding gases. Other notable activity included discreet degassing events, extrusion of sluggish lava flows, explosions that formed dilute density currents and/or expelled rocks and ash tens of meters from the vent, and rapid pressure oscillations apparently caused by the repeated formation and condensation of steam. During the last dive when the highest extrusion rates were observed, quasi-periodic bursts from the vent, each lasting 1-10 minutes, were separated by pauses lasting 10 seconds to a few minutes. Each burst started as a plug of crusted-over lava rose in the vent and was blown apart by expanding gases, producing large lava bombs with distinctly flat, disc-like shapes. A remarkable aspect of these observations was how close Jason II could be to the vent during the eruptions. This was because the pressure of the overlying seawater dampened the energy of the explosions and slowed the velocity of volcanic ejecta. Also, lava degassing could be visualized with great clarity underwater as either clear bubbles (CO2) or opaque yellow clouds (dominated by SO2 and H2S). A portable hydrophone with a 30-hour recording capacity was deployed twice by Jason II at the summit of NW Rota-1 during the 2006 dive series. The hydrophone data extends the visual observations made at the vent and quantifies the temporal pattern and intensity of the eruptive activity. The expedition to NW Rota-1 in 2006 was supported by the NOAA Ocean Exploration Program.

Chadwick, W. W.; Embley, R. W.; de Ronde, C. E.; Deardorff, N.; Matsumoto, H.; Cashman, K. V.; Dziak, R. P.; Merle, S. G.

2006-12-01

33

Hydrodynamic modeling of magmatic-hydrothermal activity at submarine arc volcanoes, with implications for ore formation  

NASA Astrophysics Data System (ADS)

Subduction-related magmas have higher volatile contents than mid-ocean ridge basalts, which affects the dynamics of associated submarine hydrothermal systems. Interaction of saline magmatic fluids with convecting seawater may enhance ore metal deposition near the seafloor, making active submarine arcs a preferred modern analogue for understanding ancient massive sulfide deposits. We have constructed a quantitative hydrological model for sub-seafloor fluid flow based on observations at Brothers volcano, southern Kermadec arc, New Zealand. Numerical simulations of multi-phase hydrosaline fluid flow were performed on a two-dimensional cross-section cutting through the NW Caldera and the Upper Cone sites, two regions of active venting at the Brothers volcanic edifice, with the former hosting sulfide mineralization. Our aim is to explore the flow paths of saline magmatic fluids released from a crystallizing magma body at depth and their interaction with seawater circulating through the crust. The model includes a 3×2 km sized magma chamber emplaced at ?2.5 km beneath the seafloor connected to the permeable cone via a ?200 m wide feeder dike. During the simulation, a magmatic fluid was temporarily injected from the top of the cooling magma chamber into the overlying convection system, assuming hydrostatic conditions and a static permeability distribution. The simulations predict a succession of hydrologic regimes in the subsurface of Brothers volcano, which can explain some of the present-day hydrothermal observations. We find that sub-seafloor phase separation, inferred from observed vent fluid salinities, and the temperatures of venting at Brothers volcano can only be achieved by input of a saline magmatic fluid at depth, consistent with chemical and isotopic data. In general, our simulations show that the transport of heat, water, and salt from magmatic and seawater sources is partly decoupled. Expulsion of magmatic heat and volatiles occurs within the first few hundred years of magma emplacement in the form of rapidly rising low-salinity vapor-rich fluids. About 95% of the magmatically derived salt is temporarily trapped in the crust, either as dense brine or as precipitated halite. This retained salt can only be expelled by later convection of seawater during the waning period of the hydrothermal system (i.e., “brine mining”). While the abundant mineralization of the NW Caldera vent field at Brothers could not be classified as an economic ore deposit, our model has important implications for submarine metal enrichment and the origin of distinct ore types known from exposed systems on land. Sulfide-complexed metals (notably Au) will preferentially ascend during early vapor-dominated fluid expulsion, potentially forming gold ± copper rich vein and replacement deposits in near-seafloor zones of submarine volcanoes. Dense magmatic brine will initially accumulate chloride-complexed base metals (such as Cu, Fe, Pb and Zn) at depth before they are mobilized by seawater convection. The resulting mixed brines can become negatively buoyant when they reach the seafloor and may flow laterally towards depressions, potentially forming layers of base metal sulphides with distinct zonation of metals.

Gruen, Gillian; Weis, Philipp; Driesner, Thomas; Heinrich, Christoph A.; de Ronde, Cornel E. J.

2014-10-01

34

Characteristics of Offshore Hawai';i Island Seismicity and Velocity Structure, including Lo';ihi Submarine Volcano  

NASA Astrophysics Data System (ADS)

The Island of Hawai';i is home to the most active volcanoes in the Hawaiian Islands. The island's isolated nature, combined with the lack of permanent offshore seismometers, creates difficulties in recording small magnitude earthquakes with accuracy. This background offshore seismicity is crucial in understanding the structure of the lithosphere around the island chain, the stresses on the lithosphere generated by the weight of the islands, and how the volcanoes interact with each other offshore. This study uses the data collected from a 9-month deployment of a temporary ocean bottom seismometer (OBS) network fully surrounding Lo';ihi volcano. This allowed us to widen the aperture of earthquake detection around the Big Island, lower the magnitude detection threshold, and better constrain the hypocentral depths of offshore seismicity that occurs between the OBS network and the Hawaii Volcano Observatory's land based network. Although this study occurred during a time of volcanic quiescence for Lo';ihi, it establishes a basis for background seismicity of the volcano. More than 480 earthquakes were located using the OBS network, incorporating data from the HVO network where possible. Here we present relocated hypocenters using the double-difference earthquake location algorithm HypoDD (Waldhauser & Ellsworth, 2000), as well as tomographic images for a 30 km square area around the summit of Lo';ihi. Illuminated by using the double-difference earthquake location algorithm HypoDD (Waldhauser & Ellsworth, 2000), offshore seismicity during this study is punctuated by events locating in the mantle fault zone 30-50km deep. These events reflect rupture on preexisting faults in the lower lithosphere caused by stresses induced by volcano loading and flexure of the Pacific Plate (Wolfe et al., 2004; Pritchard et al., 2007). Tomography was performed using the double-difference seismic tomography method TomoDD (Zhang & Thurber, 2003) and showed overall velocities to be slower than the regional velocity model (HG50; Klein, 1989) in the shallow lithosphere above 16 km depth. This is likely a result of thick deposits of volcaniclastic sediments and fractured pillow basalts that blanket the southern submarine flank of Mauna Loa, upon which Lo';ihi is currently superimposing (Morgan et al., 2003). A broad, low-velocity anomaly was observed from 20-40 km deep beneath the area of Pahala, and is indicative of the central plume conduit that supplies magma to the active volcanoes. A localized high-velocity body is observed 4-6 km deep beneath Lo';ihi's summit, extending 10 km to the North and South. Oriented approximately parallel to Lo';ihi's active rift zones, this high-velocity body is suggestive of intrusion in the upper crust, similar to Kilauea's high-velocity rift zones.

Merz, D. K.; Caplan-Auerbach, J.; Thurber, C. H.

2013-12-01

35

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

36

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

37

High-Temperature Hydrothermal Vent Field of Kolumbo Submarine Volcano, Aegean Sea: Site of Active Kuroko-Type Mineralization  

NASA Astrophysics Data System (ADS)

Kolumbo submarine volcano is located 7 km north-east of the island of Santorini in the Hellenic arc (Greece), and comprises one of about twenty submarine cones in a NE-trending rift zone. Kolumbo erupted explosively in 1649-50AD, causing 70 fatalities on Santorini. Kolumbo's crater is 1700 m in diameter, with a crater rim at 10 m below sea level and crater floor at depth of 505 m. Recent marine geological investigations, using ROVs, reveal a very active high-temperature hydrothermal vent field in the northeastern part of the Kolumbo crater floor, about 25,000 m2. Vent chimneys up to 4 m high are vigorously emitting colorless gas plumes up to 10 m high in the water column. Temperatures up to 220oC are recorded in vent fluids. Some vents are in crater- like depressions, containing debris from collapsed extinct chimneys. The entire crater floor of Kolumbo is mantled by a reddish-orange bacterial mat, and bacterial filaments of a variety of colors cling to chimneys in dense clusters. Glassy tunicates and anemones are common in lower-temperature environments on the crater floor. Most chimneys show a high porosity, with a central conduit surrounded by an open and very permeable framework of sulfides and sulfates, aiding fluid flow through the chimney walls. In the sulfate-rich samples, blades of euhedral barite and anhydrite crystals coat the outside of the chimney wall, and layers of barite alternate with sulfide in the interior. The dominant sulfides are pyrite, sphalerite, wurtzite, marcasite and galena. Crusts on extinct and lower-temperature chimneys are composed of amorphous silica, goethite and halite. Sulfur isotope composition of sulfates is virtually at sea water values, whereas the sulfides are more depleted. Elevated levels of copper, gold and silver are observed in bulk composition of chimney samples. Both the structural setting, character of the vent field and sulfide/sulfate mineralogy and geochemistry indicate on-going Kuroko-type mineralization in the Kolumbo submarine crater today.

Sigurdsson, H.; Carey, S.; Alexandri, M.; Vougioukalakis, G.; Croff, K.; Roman, C.; Sakellariou, D.; Anagnostou, C.; Rousakis, G.; Ioakim, C.; Gogou, A.; Ballas, D.; Misaridis, T.; Nomikou, P.

2006-12-01

38

Discovery of an active shallow submarine silicic volcano in the northern Izu-Bonin Arc: volcanic structure and potential hazards of Oomurodashi Volcano (Invited)  

NASA Astrophysics Data System (ADS)

Oomurodashi is a bathymetric high located ~20 km south of Izu-Oshima, an active volcanic island of the northern Izu-Bonin Arc. Using the 200 m bathymetric contour to define its summit dimensions, the diameter of Oomurodashi is ~20 km. Oomurodashi has been regarded as inactive, largely because it has a vast flat-topped summit at 100 - 150 meters below sea level (mbsl). During cruise NT07-15 of R/V Natsushima in 2007, we conducted a dive survey in a small crater, Oomuro Hole, located in the center of the flat-topped summit, using the remotely-operated vehicle (ROV) Hyper-Dolphin. The only heat flow measurement conducted on the floor of Oomuro Hole during the dive recorded an extremely high value of 4,200 mW/m2. Furthermore, ROV observations revealed that the southwestern wall of Oomuro Hole consists of fresh rhyolitic lavas. These findings suggest that Oomurodashi is in fact an active silicic submarine volcano. To confirm this hypothesis, we conducted detailed geological and geophysical ROV Hyper-Dolphin (cruise NT12-19). In addition to further ROV surveys, we carried out single-channel seismic (SCS) surveys across Oomurodashi in order to examine the shallow structures beneath the current edifice. The ROV surveys revealed numerous active hydrothermal vents on the floor of Oomuro Hole, at ~200 mbsl, with maximum water temperature measured at the hydrothermal vents reaching 194°C. We also conducted a much more detailed set of heat flow measurements across the floor of Oomuro Hole, detecting very high heat flows of up to 29,000 mW/m2. ROV observations revealed that the area surrounding Oomuro Hole on the flat-topped summit of Oomurodashi is covered by extensive fresh rhyolitic lava and pumice clasts with minimum biogenetic or manganese cover, suggesting recent eruption(s). These findings strongly indicate that Oomurodashi is an active silicic submarine volcano, with recent eruption(s) occurring from Oomuro Hole. Since the summit of Oomurodashi is in shallow water, it is possible that eruption columns are likely to breach the sea surface and generate subaerial plumes. A ~10 ka pumiceous tephra layer with a similar composition to the rocks recovered during the dives has been discovered in the subaerial outcrops of Izu-Oshima, suggesting that this tephra may have originated from Oomurodashi. The deeper slopes of Oomurodashi are composed of effusive and intrusive rocks that are bimodal in composition, with basaltic dikes and lavas on the northern flank and dacite volcaniclastics on the eastern flank. This suggests that Oomurodashi is a complex of smaller edifices of various magma types, similar to what has been observed at silicic submarine calderas in the southern part of the Izu-Bonin Arc (e.g. Sumisu Caldera; Tani et al., 2008, Bull. Vol.). Furthermore, the SCS surveys revealed the presence of a buried caldera structure, ~8 km in diameter, beneath the flat-topped summit of Oomurodashi, indicating that voluminous and explosive eruptions may have occurred in the past.

Tani, K.; Ishizuka, O.; Nichols, A. R.; Hirahara, Y.; Carey, R.; McIntosh, I. M.; Masaki, Y.; Kondo, R.; Miyairi, Y.

2013-12-01

39

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

NASA Astrophysics Data System (ADS)

On October 10 2011 an underwater eruption gave rise to a novel shallow submarine volcano south of the island of El Hierro, Canary Islands, Spain. During the eruption large quantities of mantle-derived gases, solutes and heat were released into the surrounding waters. In order to monitor the impact of the eruption on the marine ecosystem, periodic multidisciplinary cruises were carried out. Here, we present an initial report of the extreme physical-chemical perturbations caused by this event, comprising thermal changes, water acidification, deoxygenation and metal-enrichment, which resulted in significant alterations to the activity and composition of local plankton communities. Our findings highlight the potential role of this eruptive process as a natural ecosystem-scale experiment for the study of extreme effects of global change stressors on marine environments. (A) Natural color composite from the MEdium Resolution Imaging Spectrometer (MERIS) instrument aboard ENVISAT Satellite (European Space Agency), (November 9, 2011 at 14:45 UTC). Remote sensing data have been used to monitor the evolution of the volcanic emissions, playing a fundamental role during field cruises in guiding the Spanish government oceanographic vessel to the appropriate sampling areas. The inset map shows the position of Canary Islands west of Africa and the study area (solid white box). (B) Location of the stations carried out from November 2011 to February 2012 at El Hierro. Black lines denote transects A-B and C-D.

Fraile-Nuez, E.; Santana-Casiano, J.; Gonzalez-Davila, M.

2013-12-01

40

Dive and Explore: An Interactive Web Visualization that Simulates Making an ROV Dive to an Active Submarine Volcano  

NASA Astrophysics Data System (ADS)

Several years ago we created an exciting and engaging multimedia exhibit for the Hatfield Marine Science Center that lets visitors simulate making a dive to the seafloor with the remotely operated vehicle (ROV) named ROPOS. The exhibit immerses the user in an interactive experience that is naturally fun but also educational. The public display is located at the Hatfield Marine Science Visitor Center in Newport, Oregon. We are now completing a revision to the project that will make this engaging virtual exploration accessible to a much larger audience. With minor modifications we will be able to put the exhibit onto the world wide web so that any person with internet access can view and learn about exciting volcanic and hydrothermal activity at Axial Seamount on the Juan de Fuca Ridge. The modifications address some cosmetic and logistic ISSUES confronted in the museum environment, but will mainly involve compressing video clips so they can be delivered more efficiently over the internet. The web version, like the museum version, will allow users to choose from 1 of 3 different dives sites in the caldera of Axial Volcano. The dives are based on real seafloor settings at Axial seamount, an active submarine volcano on the Juan de Fuca Ridge (NE Pacific) that is also the location of a seafloor observatory called NeMO. Once a dive is chosen, then the user watches ROPOS being deployed and then arrives into a 3-D computer-generated seafloor environment that is based on the real world but is easier to visualize and navigate. Once on the bottom, the user is placed within a 360 degree panorama and can look in all directions by manipulating the computer mouse. By clicking on markers embedded in the scene, the user can then either move to other panorama locations via movies that travel through the 3-D virtual environment, or they can play video clips from actual ROPOS dives specifically related to that scene. Audio accompanying the video clips informs the user where they are going or what they are looking at. After the user is finished exploring the dive site they end the dive by leaving the bottom and watching the ROV being recovered onto the ship at the surface. Within the three simulated dives there are a total of 6 arrival and departure movies, 7 seafloor panoramas, 12 travel movies, and 23 ROPOS video clips. This virtual exploration is part of the NeMO web site and will be at this URL http://www.pmel.noaa.gov/vents/dive.html

Weiland, C.; Chadwick, W. W.

2004-12-01

41

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.

42

Submarine pyroclastic deposits formed at the Soufrière Hills volcano, Montserrat (1995 2003): What happens when pyroclastic flows enter the ocean?  

NASA Astrophysics Data System (ADS)

The Soufrière Hills volcano, Montserrat, West Indies, has undergone a series of dome growth and collapse events since the eruption began in 1995. Over 90% of the pyroclastic material produced has been deposited into the ocean. Sampling of these submarine deposits reveals that the pyroclastic flows mix rapidly and violently with the water as they enter the sea. The coarse components (pebbles to boulders) are deposited proximally from dense basal slurries to form steep-sided, near-linear ridges that intercalate to form a submarine fan. The finer ash-grade components are mixed into the overlying water column to form turbidity currents that flow over distances >30 km from the source. The total volume of pyroclastic material off the east coast of Montserrat exceeds 280 × 106 m3, with 65% deposited in proximal lobes and 35% deposited as distal turbidites.

Trofimovs, J.; Amy, L.; Boudon, G.; Deplus, C.; Doyle, E.; Fournier, N.; Hart, M. B.; Komorowski, J. C.; Le Friant, A.; Lock, E. J.; Pudsey, C.; Ryan, G.; Sparks, R. S. J.; Talling, P. J.

2006-07-01

43

Long-distance magma transport from arc volcanoes inferred from the submarine eruptive fissures offshore Izu-Oshima volcano, Izu-Bonin arc  

NASA Astrophysics Data System (ADS)

Long-distance lateral magma transport away from volcanic centers in island arcs is emerging as a common phenomenon where the regional stress regime is favorable. It should also be recognized as an important factor in the construction and growth of island arcs, and a potential trigger for devastating eruptions. In this contribution, we report on recent investigations into the magma dynamics of Izu-Oshima volcano, an active basaltic volcano with an extensive fissure system. Izu-Oshima is flanked by numerous, subparallel NW-SE trending submarine ridges extending up to 22 km to the NW and the SE from the central vent. During a recent submersible survey we have identified that these ridges are fissures which erupted basaltic spatter and lava flows. Furthermore, lavas are petrographically similar along each ridge, while there are noticeable differences between ridges. The subparallel ridges are observed to transect a series of seamounts - the Izu-Tobu monogenetic volcanoes - which are dispersed across this area of the rear-arc. However, there are consistent petrographic and chemical differences between these seamounts and the ridges, indicating that they have different magma sources, yet, they are essentially bounding each other in dive tracks. The most appropriate scenario for their development is one where the Izu-Tobu Volcanoes are fed by an “in-situ” underlying source, while the NW-SE ridges are fed by lateral magma transport from Izu-Oshima. Magma erupted from each ridge is of a consistent geochemistry along its length, but has experienced crystal fractionation and some plagioclase accumulation. Compositions of the ridges are also very similar to lavas from the subaerial cones that can be traced down the flanks of Izu-Oshima. This implies that pairs of subaerial cones and submarine ridges represent the locus of magma transport events away from the storage system beneath Izu-Oshima. Hence, magma from this crustal reservoir moved upward to feed the on-edifice cones, as well as laterally to supply submarine fissures and dykes to a distance of 22 km.

Ishizuka, Osamu; Geshi, Nobuo; Kawanabe, Yoshihisa; Ogitsu, Itaru; Taylor, Rex N.; Tuzino, Taqumi; Sakamoto, Izumi; Arai, Kohsaku; Nakano, Shun

2014-09-01

44

Repeater Fault Location for a Submarine Optical Fiber Cable Transmission System  

Microsoft Academic Search

This paper introduces a repeater fault location system for a repeated submarine optical fiber transmission system of 400 Mbits\\/ s at 1.3?m. The repeater fault location system is used in an out-of-service test. The fault locator transmits a test signal via a main optical fiber line, in order to make a loop-back path in one of the repeaters for returning

Y. Kobayashi; Y. Ichihashi

1984-01-01

45

Seismic tomography reveals magma chamber location beneath Uturuncu volcano (Bolivia)  

NASA Astrophysics Data System (ADS)

Uturuncu volcano belongs to the Altiplano-Puna Volcanic Complex in the central Andes, the product of an ignimbrite ''flare-up''. The region has been the site of large-scale silicic magmatism since 10 Ma, producing 10 major eruptive calderas and edifices, some of which are multiple-eruption resurgent complexes as large as the Yellowstone or Long Valley caldera. Satellite measurements show that the hill has been rising more than half an inch a year for almost 20 years, suggesting that the Uturuncu volcano, which has erupted last time more than 300,000 years ago, is steadily inflating, which makes it fertile ground for study. In 2009 an international multidisciplinary team formed a project called PLUTONS to study Uturuncu. Under this project a 100 km wide seismic network was set around the volcano by seismologists from University of Alaska Fairbanks. Local seismicity is well distributed and provides constraints on the shallow crust. Ray paths from earthquakes in the subducting slab complement this with steep ray paths that sample the deeper crust. Together the shallow and deep earthquakes provide strong 3D coverage of Uturuncu and the surrounding region. To study the deformation source beneath the volcano we performed simultaneous tomographic inversion for the Vp and Vs anomalies and source locations, using the non-linear passive source tomographic code, LOTOS. We estimated both P and S wave velocity structures beneath the entire Uturuncu volcano by using arrival times of P and S waves from more than 600 events registered by 33 stations. To show the reliability of the results, we performed a number of different tests, including checkerboard synthetic tests and tests with odd/even data. Obtained Vp/Vs ratio distribution shows increased values beneath the south Uturuncu, at a depth of about 15 km. We suggest the high ratio anomaly is caused by partial melt, presented in expanding magma chamber, responsible for the volcano inflation. The resulting Vp, Vs and the ratio reveal the paths of the ascending fluids and melts, feeding the magma chamber. This work was partly supported by Project #7.3 of BES RAS and Project #14-05-31176 mola of RFBR.

Kukarina, Ekaterina; West, Michael; Koulakov, Ivan

2014-05-01

46

Submarine Pyroclastic Flow Deposits; July 2003 Dome Collapse Event of the Soufrière Hills Volcano, Montserrat, West Indies  

NASA Astrophysics Data System (ADS)

What happens when pyroclastic flows enter the ocean? To date, the subject of submarine pyroclastic flow behaviour has been controversial. Ambiguity arises from inconclusive evidence of a subaqueous depositional environment in ancient successions, to difficulty in sampling the in situ products of modern eruptions. A research voyage of the RRS James Clark Ross (9-18 May 2005) sampled 52 sites offshore from the volcanic island of Montserrat. The Soufrière Hills volcano, Montserrat, has been active since 1995 with eruptive behaviour dominated by andesite lava dome growth and collapse. Over 90% of the pyroclastic material produced has been deposited into the ocean. In July 2003 the Soufrière Hills volcano produced the largest historically documented dome collapse event. 210 x 106 m3 of pyroclastic material avalanched down the Tar River Valley, southeast Montserrat, to be deposited into the ocean. Bathymetric imaging and coring of offshore pyroclastic deposits, with a specific focus on the July 2003 units, reveals that the pyroclastic flows mix rapidly and violently with the water as they enter the ocean. Mixing takes place between the shore and 500 m depth where the deposition of basal coarse-grained parts of the flow initiates on slopes of 15° or less. The coarse components (pebbles to boulders) are deposited proximally from dense basal slurries to form steep sided, near linear ridges that amalgamate to form a kilometer-scale submarine fan. These proximal deposits contain <1% of ash-grade material. The finer components (dominantly ash-grade) are mixed into the overlying water column to form turbidity currents that flow distances >40 km from source. The total volume of pyroclastic material deposited within the submarine environment during this event exceeds 170 x 106 m3, with 65% deposited in proximal lobes and 35% deposited as distal turbidites. This broadly correlates with the block and ash components respectively, of the source subaerial pyroclastic flow. However, the efficient sorting and physical differentiation of the submarine flows, in comparison to the original mixture of their subaerial counterparts, suggests that the pyroclastic flows mix thoroughly with seawater and generate sediment gravity currents which are stratified in grain size and concentration.

Trofimovs, J.; Sparks, S.; Talling, P.

2006-12-01

47

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

PubMed

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

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

2012-01-01

48

Magnetic mapping of submarine hydrothermal systems at Marsili and Palinuro volcanoes from deep-towed magnetometer data  

NASA Astrophysics Data System (ADS)

We collected near-bottom magnetic data at Marsili and Palinuro volcanoes in the Southern Tyrrhenian Sea, by adding a magnetometer to a deep-towed sidescan sonar. Equivalent magnetization maps obtained by inversion of the recorded magnetic anomalies are analyzed to map alteration zones related to hydrothermal processes and are correlated with water-column and seafloor observations of hydrothermal activity. At Marsili volcano, we found a large elliptical area of low magnetization, confirming the existence of a large hydrothermal system located in proximity of the top cone, above the magma chamber. Palinuro volcano is characterized by hydrothermal venting located along the caldera walls, where the corresponding ring faults may provide preferred pathways for the upflow of the hydrothermal fluids.

Caratori Tontini, F.; Bortoluzzi, G.; Carmisciano, C.; Cocchi, L.; de Ronde, C. E.; Ligi, M.; Muccini, F.

2013-12-01

49

Hydroacoustic investigation of submarine landslides at West Mata volcano, Lau Basin  

NASA Astrophysics Data System (ADS)

landslides are an important process in volcano growth yet are rarely observed and poorly understood. We show that landslides occur frequently in association with the eruption of West Mata volcano in the NE Lau Basin. These events are identifiable in hydroacoustic data recorded between ~5 and 20 km from the volcano and may be recognized in spectrograms by the weak and strong powers at specific frequencies generated by multipathing of sound waves. The summation of direct and surface-reflected arrivals causes interference patterns in the spectrum that change with time as the landslide propagates. Observed frequencies are consistent with propagation down the volcano's north flank in an area known to have experienced mass wasting in the past. These data allow us to estimate the distance traveled by West Mata landslides and show that they travel at average speeds of ~10-25 m/s.

Caplan-Auerbach, J.; Dziak, R. P.; Bohnenstiehl, D. R.; Chadwick, W. W.; Lau, T.-K.

2014-08-01

50

Cold seeps associated with a submarine debris avalanche deposit at Kick'em Jenny volcano, Grenada (Lesser Antilles)  

NASA Astrophysics Data System (ADS)

Remotely operated vehicle (ROV) exploration at the distal margins of a debris avalanche deposit from Kick'em Jenny submarine volcano in Grenada has revealed areas of cold seeps with chemosynthetic-based ecosystems. The seeps occur on steep slopes of deformed, unconsolidated hemipelagic sediments in water depths between 1952 and 2042 m. Two main areas consist of anastomosing systems of fluid flow that have incised local sediments by several tens of centimeters. No temperature anomalies were observed in the vent areas and no active flow was visually observed, suggesting that the venting may be waning. An Eh sensor deployed on a miniature autonomous plume recorder (MAPR) recorded a positive signal and the presence of live organisms indicates at least some venting is still occurring. The chemosynthetic-based ecosystem included giant mussels (Bathymodiolus sp.) with commensal polychaetes (Branchipolynoe sp.) and cocculinid epibionts, other bivalves, Siboglinida (vestimentiferan) tubeworms, other polychaetes, and shrimp, as well as associated heterotrophs, including gastropods, anemones, crabs, fish, octopods, brittle stars, and holothurians. The origin of the seeps may be related to fluid overpressure generated during the collapse of an ancestral Kick'em Jenny volcano. We suggest that deformation and burial of hemipelagic sediment at the front and base of the advancing debris avalanche led to fluid venting at the distal margin. Such deformation may be a common feature of marine avalanches in a variety of geological environments especially along continental margins, raising the possibility of creating large numbers of ephemeral seep-based ecosystems.

Carey, Steven; Ballard, Robert; Bell, Katherine L. C.; Bell, Richard J.; Connally, Patrick; Dondin, Frederic; Fuller, Sarah; Gobin, Judith; Miloslavich, Patricia; Phillips, Brennan; Roman, Chris; Seibel, Brad; Siu, Nam; Smart, Clara

2014-11-01

51

Examples of Models Fit to Magnetic Anomalies Observed Over Subaerial, Submarine, and Subglacial Volcanoes in the West Antarctic Rift System  

NASA Astrophysics Data System (ADS)

Aeromagnetic and marine magnetic surveys over the volcanically active West Antarctic rift system, constrained by seismic reflection profiles over the Ross Sea continual shelf, and radar ice sounding surveys over the West Antarctic Ice Sheet (WAIS) allowed calculation of models fit to very high-amplitude anomalies. We present several examples: exposed 2700-m high, subaerial erupted volcano Mt Melbourne; the 750-m high source of anomaly D (Hamilton submarine volcano) in the Ross sea; and the 600-m high edifice of Mt. CASERTZ beneath the WAIS. The character of these anomalies and their sources varies greatly, and is inferred to be the result of subaerial, submarine and subglacial emplacement respectively. Mt. Melbourne erupted through the WAIS at a time when it was grounded over the Ross Sea continental shelf. Highly magnetic volcanic flows inferred to have high remanent (normal) magnetization in the present field direction produce the 600-nT positive anomaly. The flows protected the edifice above the ice from erosion. Negligible amounts of probably subglacially erupted, apparently non-magnetic hyaloclastite exist in association with Mt. Melbourne. Mt. CASERTZ is nonmagnetic and the edifice is interpreted as consisting of a transient mound of unconsolidated hyaloclastite injected into the WAIS. However Mt. CASERTZ, about 8-km diameter, overlies a 200-m high, 40-km wide highly magnetic residual edifice modeled as the top of the source (an active subglacial volcano) of a 400-nT high positive anomaly. Any former edifices comprising hyaloclastite, pillow breccia or other volcanic debris injected into the moving WAIS apparently have been removed. About 400 other high- amplitude anomalies associated with low relief (80 percent less than 200 m) edifices at the base of the ice (the tops of the sources of these steep gradient anomalies) beneath the WAIS defined by radar ice sounding have been interpreted as having former hyaloclastite edifices, which were removed by the moving ice. The source of the -1300-nT negative anomaly D projecting 600 m above the Ross Sea continental shelf is enigmatic. We interpret models as either the result of reversed magnetization (less than 780 Ka) at a time of deglaciation of the continental shelf, or a hydrothermally altered central core surrounded by highly magnetic flows erupted beneath the Ross sea since deglaciation in Holocene time.

Behrendt, J. C.; Finn, C. A.; Blankenship, D. D.

2006-12-01

52

Morphometric analysis of the submarine arc volcano Monowai (Tofua-Kermadec Arc) to decipher tectono-magmatic interactions  

NASA Astrophysics Data System (ADS)

Morphometric analysis of multibeam bathymetry and backscatter data is applied to Monowai, a submarine volcano of the active Tofua-Kermadec Arc to map and document the structure and evolution of the volcanic centre. Low rates of erosion and sedimentation, and pervasive tectonic and magmatic processes, allow quantification through detailed structural analysis and measurement of deformation. The Slope, Aspect, Curvature, Rugosity, and Hydrology (flow) tools of ArcGIS provide a robust structural interpretation and the development of a model of Monowai evolution. A nested caldera structure with a volume of ~ 31 km3 and a stratovolcano of ~ 18 km3 dominate the magmatic constructs. The outer caldera is elongate along 125°, and the inner caldera along 135°. Numerous parasitic cones and fissure ridges are also observed, oriented at 039° and 041°, respectively. Northeast trending faults (with a regional average strike of 031°) are widespread within this part of the backarc, forming a nascent rift graben to the west of the Monowai caldera complex. The distribution of throw varies spatially, reaching a maximum total along-rift of 320 m and across rift of 120 m, with greater throw values measured in the west. Elongation directions of the two nested calderas are near-perpendicular to the trends of faults and fissure ridges. The inner caldera is more orthogonal to the magmatic constructs (fissure ridges and aligned vent cones) and the outer caldera is approximately orthogonal to the regional fault fabric, suggesting a strong interaction between magmatic and tectonic processes, and the directions of the horizontal principal stress. We present a detailed morphometric analysis of these relationships and the data are used to interpret the spatial and temporal evolution of the tectono-magmatic system at Monowai, and classify the type of rifting as transtensional. Similar analysis is possible elsewhere in the Kermadec backarc and within other regions of submarine volcanism.

Wormald, Sarah C.; Wright, Ian C.; Bull, Jonathan M.; Lamarche, Geoffroy; Sanderson, David J.

2012-09-01

53

Molecular Comparison of Bacterial Communities within Iron-Containing Flocculent Mats Associated with Submarine Volcanoes along the Kermadec Arc?  

PubMed Central

Iron oxide sheaths and filaments are commonly found in hydrothermal environments and have been shown to have a biogenic origin. These structures were seen in the flocculent material associated with two submarine volcanoes along the Kermadec Arc north of New Zealand. Molecular characterization of the bacterial communities associated with the flocculent samples indicated that no known Fe-oxidizing bacteria dominated the recovered clone libraries. However, clones related to the recently described Fe-oxidizing bacterium Mariprofundus ferrooxydans were obtained from both the iron-containing flocculent (Fe-floc) and sediment samples, and peaks corresponding to Mariprofundus ferrooxydans, as well as the related clones, were observed in several of our terminal restriction fragment length polymorphism profiles. A large group of epsilonproteobacterial sequences, for which there is no cultured representative, dominated clones from the Fe-floc libraries and were less prevalent in the sediment sample. Phylogenetic analyses indicated that several operational taxonomic units appeared to be site specific, and statistical analyses of the clone libraries found that all samples were significantly different from each other. Thus, the bacterial communities in the Fe-floc samples were not more closely related to each other than to the sediment communities. PMID:19114513

Hodges, Tyler W.; Olson, Julie B.

2009-01-01

54

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

55

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

NASA Astrophysics Data System (ADS)

Stromboli is the easternmost island of the Aeolian Archipelago (Tyrrhenian Sea) and one of the most active Mediterranean volcanoes. The volcanic edifice rises over 3000 m above the surrounding seafloor, from a depth of about 2000 m b.s.l. to 924 m a.s.l. The north-western flank of volcano is deeply scarred by a destructive collapse event occurred ca. 5000 years ago, and forming a big horseshoe-shaped depression, known as "Sciara del Fuoco" (SdF). This depression, 3 Km long and 2 Km wide, is supposed to extend into the sea down to 700 m b.s.l., while further basinward it turns into a fan-shaped mounted deposit down to about 2600 m b.s.l., where it merges the so-called "Stromboli Canyon". Since its formation, emerged and submerged portions of the SdF have been progressively filled by the volcanic products of the persistent activity of the Stromboli Volcano. In the last 10 years, two paroxysmal eruptions occurred in the Stromboli Volcano, during 2002-2003 and February-April 2007. During both events, the SdF has been partially covered by lava flows and affected by slope failures, also causing (for the 2002-2003 event) a local tsunami. Since the 1990's, and especially after the last two paroxysms, the submerged extension of the SdF has been intensively investigated by using swath bathymetry data. We focused principally on the magnetic anomaly pattern of the submerged SdF since the chaotic depositional system virtually cancels magnetic remanence (which at Stromboli can reach 5-10 A/m values), thus lowering magnetic residual intensity. On July 2012 we acquired new detailed sea-surface magnetic data of the SdF from the shoreline to about 7 km offshore, where the depth is more than 1800 m b.s.l. We collected data thanks to the Italian Navy ship "Nave Aretusa" and by using the Marine Magnetics SeaSPY magnetometer. At the same time, new bathymetric data were acquired in the same area by using a Kongsberg Marine multibeam systems. Although the morphologic features of the submarine prosecution of the SdF system were already studied and unveiled, the complete description of the in-depth extension of the system and the overall volume estimation is still poorly known. This has important implications for the hazard assessment of the landslide structure and most generally of the entire volcanic edifice. The application of a classical geomagnetic prospection to describe a landslide feature is an uncommon procedure yet it can be considered as innovative approach, having the advantages of effectiveness, low cost and expedition typical of the geomagnetic survey. Here we present the interpretation of the newly acquired high-resolution magnetic dataset, thanks to susceptibility and magnetic remanence values gathered from on-land rock samples at Stromboli. A 3D inverse model is here proposed, allowing a full definition of the submerged SdF structure geometry.

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

2012-12-01

56

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

57

Magma Ascent to Submarine Volcanoes: Real-Time Monitoring by Means of Teleseismic Observations of Earthquake Swarms  

NASA Astrophysics Data System (ADS)

Earthquake swarm occurrence belongs to reliable indicators of magmatic activity in the Earth crust. Their occurrence beneath submarine portions of volcanic arcs brings valuable information on plumbing systems of this unsufficiently understood environment and reveals recently active submarine volcanoes. Utilisation of teleseismically recorded data (NEIC, GCMT Project) enables to observe magmatic activity in almost real time. We analysed seismicity pattern in two areas - the Andaman-Nicobar region in April 2012 and the southern Ryukyu in April 2013. In both regions, the swarms are situated 80-100 km above the Wadati-Benioff zone of the subducting slab. Foci of the swarm earthquakes delimit a seismogenic layer at depths between 9 - 35 km that should be formed by brittle and fractured rock environment. Repeated occurrence of earthquakes clustered in swarms excludes large accumulations of melted rocks in this layer. Magma reservoirs should be situated at depths greater than 35 km. Upward magma migration from deeper magma reservoirs to shallow magma chambers or to the seafloor induce earthquake swarms by increasing tectonic stress and/or decreasing friction at faults. Frequency of earthquake swarm occurrence in the investigated areas has made a volcanic eruption at the seafloor probable. Moreover, epicentral zones of the swarms often coincide with distinct elevations at the seafloor - seamounts and seamount ranges. High accuracy of global seismological data enabled also to observe migration of earthquakes during individual swarms (Fig. 1), probably reflecting dike and/or sill propagation. Triggering of earthquake swarms by distant strong earthquakes was repeatedly observed in the Andaman-Nicobar region. The presented study documents high accuracy of hypocentral determinations published by the above mentioned data centers and usefulness of the EHB relocation procedure. Epicentral map of the October 2002 earthquake swarm in southern Ryukyu showing E-W migration of events during the swarm. The swarm occurred during 29 hours on October 23 - 25 in the magnitude range 4.0 - 5.2. Open circles - epicenters of all 54 events of the swarm; red circles - epicenters of events that occurred in a particular time interval of the swarm development: (a) - starting 3 hours; (b) - following 4 hours; (c) - final 22 hours.

Spicak, A.; Vanek, J.; Kuna, V. M.

2013-12-01

58

Vailulu'u Seamount, Samoa: Life and Death at the Edge of An Active Submarine Volcano  

NASA Astrophysics Data System (ADS)

Exploration of Vailulu'u seamount (14°13'S; 169°04'W) by manned submersible, ROV, and surface ship revealed a new, 300m tall volcano that has grown in the summit crater in less than four years. This shows that Vailulu'u's eruption behavior is at this stage not predictable and continued growth could allow Vailulu'u to breach sea level within decades Several types of hydrothermal vents fill Vailulu'u crater with particulates that reduce visibility to less than a few meters in some regions. Hydrothermal solutions mix with seawater that enters the crater from its breaches to produce distinct biological habitats. Low temperature hydrothermal vents can produce Fe-oxide chimneys or up to one meter-thick microbial mats. Higher temperature vents (85°C) produce low salinity acidic fluids containing buoyant droplets of immiscible CO2. Low temperature hydrothermal vents at Nafanua summit (708m depth) support a thriving population of eels (Dysommia rusosa). The areas around the high temperature vents and the moat and remaining crater around the new volcano is almost devoid of any macroscopic life and is littered with fish, and mollusk carcasses that apparently died from exposure to hydrothermal fluid components in deeper crater waters. Acid- tolerant polychaetes adapt to this environment and feed near and on these carcasses. Vailulu'u presents a natural laboratory for the study of how seamounts and their volcanic systems interact with the hydrosphere to produce distinct biological habitats, and how marine life can adapt to these conditions or be trapped in a toxic volcanic system that leads to mass mortality. The Vailulu'u research team: Hubert Staudigel, Samantha Allen, Brad Bailey, Ed Baker, Sandra Brooke, Ryan Delaney, Blake English, Lisa Haucke, Stan Hart, John Helly, Ian Hudson, Matt Jackson, Daniel Jones, Alison Koleszar, Anthony Koppers, Jasper Konter, Laurent Montesi, Adele Pile, Ray Lee, Scott Mcbride, Julie Rumrill, Daniel Staudigel, Brad Tebo, Alexis Templeton, Rhea Workman, Craig Young, Robert Zierenberg.

Vailulu'U Research Group, T.

2005-12-01

59

The volcanic debris avalanche on the SE submarine slope of Nisyros volcano, Greece: geophysical exploration and implications for subaerial eruption history  

NASA Astrophysics Data System (ADS)

A spectacular hummocky topography was discovered offshore of the south-eastern slope of the Nisyros island volcano in the eastern sector of the Aegean volcanic arc in 2000-2001, using multibeam bathymetric mapping and seismic profiling, and interpreted as part of a volcanic debris avalanche originating onland. During E/V Nautilus cruise NA011 in 2010, a detailed side-scan sonar and ROV exploration aimed at evaluating the surface morphology of this avalanche field. Combining the new data with selected older datasets reveals that the debris avalanche is characterized by numerous (at least 78) variously sized and shaped hummocks. Some of these are distinctly round, either scattered or aligned in groups, whereas others are elongated in the form of ridges. This is consistent with existing models accounting for variations in the longitudinal and lateral velocity ratio of landslides. Maximum dimensions reach 60 m in height above the sea bottom, 220 m in length and 230 m in width. The structures outline a large tongue-shaped, submarine hummock field of about 22.2 km2, approx. 4.8 km wide and 4.6 km long and with an estimated volume of 0.277 km3. Due to its characteristic shape, the collapsed volcanic flank is interpreted to represent a singular failing event, involving a rapid and virtually instantaneous downslope movement of the slide mass into the sea. Indeed, the H/L (height of 280 m vs. run-out of 7 km) ratio for the Nisyros slide is 0.04; plotted against volume, this falls within the theoretical bounds as well as measured values typical of submarine landslides. The timing of the event is probably related to the extrusion of Nikia lavas and their subsequent failure and formation of a main scarp observed at about 120 m depth on an 8-km-long seismic profile and a map of slope angle distribution, at the depth where the palaeo-coastline was located 40 ka ago. An inferred age of ca. 40 ka for the avalanche awaits confirmation based on dating of core material.

Livanos, Isidoros; Nomikou, Paraskevi; Papanikolaou, Dimitris; Rousakis, Grigoris

2013-12-01

60

Survival of mussels in extremely acidic waters on a submarine volcano  

NASA Astrophysics Data System (ADS)

Increasing atmospheric carbon dioxide levels are causing ocean acidification, compromising the ability of some marine organisms to build and maintain support structures as the equilibrium state of inorganic carbon moves away from calcium carbonate. Few marine organisms tolerate conditions where ocean pH falls significantly below today's value of about 8.1 and aragonite and calcite saturation values below 1 (refs 5, 6). Here we report dense clusters of the vent mussel Bathymodiolus brevior in natural conditions of pH values between 5.36 and 7.29 on northwest Eifuku volcano, Mariana arc, where liquid carbon dioxide and hydrogen sulphide emerge in a hydrothermal setting. We find that both shell thickness and daily growth increments in shells from northwest Eifuku are only about half those recorded from mussels living in water with pH>7.8. Low pH may therefore also be implicated in metabolic impairment. We identify four-decade-old mussels, but suggest that the mussels can survive for so long only if their protective shell covering remains intact: crabs that could expose the underlying calcium carbonate to dissolution are absent from this setting. The mussels' ability to precipitate shells in such low-pH conditions is remarkable. Nevertheless, the vulnerability of molluscs to predators is likely to increase in a future ocean with low pH.

Tunnicliffe, Verena; Davies, Kimberley T. A.; Butterfield, David A.; Embley, Robert W.; Rose, Jonathan M.; Chadwick, William W., Jr.

2009-05-01

61

Simulation of Submarine Hydrothermal Systems: IV. Fluid Flow in Active Arc-Related Volcanoes  

NASA Astrophysics Data System (ADS)

Fluid flow through submarine hydrothermal systems transports a major part of the Earth's heat to its surface and greatly impacts the chemistry of crust and overlying ocean. Seafloor high-temperature vent sites are manifestations of active ore-forming systems and can be regarded as modern analogues of massive sulfide deposits whose ancient equivalents have been exploited as world-class mines on land. Recent research cruises dedicated to seafloor hydrothermal activity along convergent plate boundaries, e.g. along the intra-oceanic Kermadec arc, have systematically surveyed and sampled numerous hydrothermal plumes. Follow-up submersible dives show venting that ranges from relatively high temperature (~300° C), metal-rich fluids to lower temperature, gas-rich and metal-poor fluids. Some of these vent sites show evidence for significant contributions from magmatic sources. The physics of such systems is complex because the seawater-derived hydrothermal fluid can mix with ambient seawater and phase-separate, either via boiling or condensation, into a low-salinity vapor and a high-salinity brine. In order to model the sub-seafloor hydrology with numerical transport simulation techniques, a newly developed pressure-enthalpy-salinity scheme has been used, which includes the full phase relations of the NaCl-H2O system up to 1000° C and accurately captures boiling, condensation, and salt precipitation. We have designed a new numerical model, based on observations in currently active arc-related systems, to assess the influence of first-order physical parameters (such as seafloor topography and the contribution of magmatic fluids) to fluid flow patterns, thermal structure, and phase-separation. Preliminary results of these simulations will be presented and compared with data recently obtained from simulations at mid-ocean ridge systems. In our ongoing project, we aim to predict the optimal conditions for which metal-rich magmatic vapor may cool and contract to an aqueous liquid, which in turn is likely to generate particularly Cu- and Au-rich mineralization on the seafloor.

Gruen, G.; Coumou, D.; Weis, P.; Driesner, T.; de Ronde, C.; Heinrich, C. A.

2008-12-01

62

Submarine evidence of a debris avalanche deposit on the eastern slope of Santorini volcano, Greece  

NASA Astrophysics Data System (ADS)

Hummocky seafloor features were discovered on the eastern flank of Santorini volcano, Greece. Multibeam bathymetric mapping, airgun seismic profiling, side scan sonar survey, and remotely operated vehicle (ROV) dives have been carried out to characterize the nature of the hummocks. These hummocks appear to be composed of several tens of blocks that are up to several hundred meters in diameter, and are the surface expression of a much larger deposit than is observed in the bathymetry. The sidescan and airgun data show that the deposit covers an area of approximately 6 km wide by 20 km long, and is up to 75 m thick. We estimate the total volume of the deposit to be approximately 4.4 × 109 m3. Sampling of these blocks show they are composed of pyroclastic flow deposits produced during the Minoan eruption of Santorini (ca. 3600 BP). We propose that the deposit is the result of a multi-stage landslide event that was caused by one of the several large earthquakes or volcanic eruptions that have occurred in the vicinity of Santorini since the Minoan eruption. One or more of these events likely triggered the destabilization of a part of the eastern flank of Santorini, which led to a debris avalanche, depositing blocks and forming a hummocky terrain at the base of the island's slope. The mass movement later evolved into a turbulent suspension flow that traveled 20 km or more from the presumed initial failure. Given the size of the landslide deposit, it might have a tsunami potentially affecting the islands across the southern Aegean Sea. The understanding of earthquake-landslide dynamics has important implications for hazard assessment in this seismically active, historical, and highly populated region of the world.

Bell, Katherine Lynn Croff; Carey, Steven N.; Nomikou, Paraskevi; Sigurdsson, Haraldur; Sakellariou, Dimitris

2013-06-01

63

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

64

Eruptive fracture location forecasts from high-frequency events on Piton de la Fournaise Volcano  

NASA Astrophysics Data System (ADS)

Piton de la Fournaise (La Réunion island) is a very active basaltic volcano, with five eruptions between Nov 2009 and Dec 2010. Pre-eruptive seismic crises usually last for a few hours and mainly consist of a volcano-tectonic swarm. During the quiescent period between the volcano-tectonic swarm and the eruptive tremor, we identify another swarm of events with a very high frequency content. These events are shallow and are located close to the future eruption site. They seem associated with the opening of the path for the magma propagating laterally at shallow depth. As these events start to occur while the magma is still in a vertical propagation phase, this seismicity seems to be related with the generic response of the volcano to the stress perturbation and not directly induced by the magma pressure. This new observation brings new insights to short-term forecasting of the eruption location.

De Barros, Louis; Bean, Christopher J.; Zecevic, Megan; Brenguier, Florent; Peltier, Aline

2013-09-01

65

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.

66

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

67

The design and testing of a procedure to locate fresh submarine groundwater discharge in Cyprus  

E-print Network

The aim of this collaborative project between Massachusetts Institute of Technology (MIT) and Cyprus Institute was to develop an experimental procedure for identifying fresh submarine groundwater discharge (SGD) in Cyprus. ...

Olesnavage, Kathryn M

2012-01-01

68

Submarine hydrothermal activity and gold-rich mineralization at Brothers Volcano, Kermadec Arc, New Zealand  

NASA Astrophysics Data System (ADS)

Brothers volcano, of the Kermadec intraoceanic arc, is host to a hydrothermal system unique among seafloor hydrothermal systems known anywhere in the world. It has two distinct vent fields, known as the NW Caldera and Cone sites, whose geology, permeability, vent fluid compositions, mineralogy, and ore-forming conditions are in stark contrast to each other. The NW Caldera site strikes for ˜600 m in a SW-NE direction with chimneys occurring over a ˜145-m depth interval, between ˜1,690 and 1,545 m. At least 100 dead and active sulfide chimney spires occur in this field and are typically 2-3 m in height, with some reaching 6-7 m. Their ages (at time of sampling) fall broadly into three groups: <4, 23, and 35 years old. The chimneys typically occur near the base of individual fault-controlled benches on the caldera wall, striking in lines orthogonal to the slopes. Rarer are massive sulfide crusts 2-3 m thick. Two main types of chimney predominate: Cu-rich (up to 28.5 wt.% Cu) and, more commonly, Zn-rich (up to 43.8 wt.% Zn). Geochemical results show that Mo, Bi, Co, Se, Sn, and Au (up to 91 ppm) are correlated with the Cu mineralization, whereas Cd, Hg, Sb, Ag, and As are associated with the dominant Zn-rich mineralization. The Cone site comprises the Upper Cone site atop the summit of the recent (main) dacite cone and the Lower Cone site that straddles the summit of an older, smaller, more degraded dacite cone on the NE flank of the main cone. Huge volumes of diffuse venting are seen at the Lower Cone site, in contrast to venting at both the Upper Cone and NW Caldera sites. Individual vents are marked by low-relief (?0.5 m) mounds comprising predominately native sulfur with bacterial mats. Vent fluids of the NW Caldera field are focused, hot (?300°C), acidic (pH ? 2.8), metal-rich, and gas-poor. Calculated end-member fluids from NW Caldera vents indicate that phase separation has occurred, with Cl values ranging from 93% to 137% of seawater values. By contrast, vent fluids at the Cone site are diffuse, noticeably cooler (?122°C), more acidic (pH 1.9), metal-poor, and gas-rich. Higher-than-seawater values of SO4 and Mg in the Cone vent fluids show that these ions are being added to the hydrothermal fluid and are not being depleted via normal water/rock interactions. Iron oxide crusts 3 years in age cover the main cone summit and appear to have formed from Fe-rich brines. Evidence for magmatic contributions to the hydrothermal system at Brothers includes: high concentrations of dissolved CO2 (e.g., 206 mM/kg at the Cone site); high CO2/3He; negative ?D and ?18OH2O for vent fluids; negative ?34S for sulfides (to -4.6‰), sulfur (to -10.2‰), and ?15N2 (to -3.5‰); vent fluid pH values to 1.9; and mineral assemblages common to high-sulfidation systems. Changing physicochemical conditions at the Brothers hydrothermal system, and especially the Cone site, occur over periods of months to hundreds of years, as shown by interlayered Cu + Au- and Zn-rich zones in chimneys, variable fluid and isotopic compositions, similar shifts in 3He/4He values for both Cone and NW Caldera sites, and overprinting of "magmatic" mineral assemblages by water/rock-dominated assemblages. Metals, especially Cu and possibly Au, may be entering the hydrothermal system via the dissolution of metal-rich glasses. They are then transported rapidly up into the system via magmatic volatiles utilizing vertical (˜2.5 km long), narrow (˜300-m diameter) "pipes," consistent with evidence of vent fluids forming at relatively shallow depths. The NW Caldera and Cone sites are considered to represent stages along a continuum between water/rock- and magmatic/hydrothermal-dominated end-members.

de Ronde, Cornel E. J.; Massoth, Gary J.; Butterfield, David A.; Christenson, Bruce W.; Ishibashi, Junichiro; Ditchburn, Robert G.; Hannington, Mark D.; Brathwaite, Robert L.; Lupton, John E.; Kamenetsky, Vadim S.; Graham, Ian J.; Zellmer, Georg F.; Dziak, Robert P.; Embley, Robert W.; Dekov, Vesselin M.; Munnik, Frank; Lahr, Janine; Evans, Leigh J.; Takai, Ken

2011-07-01

69

Geochemistry of Fresh Submarine HSDP-2 Glasses from Mauna Kea Volcano: Unexpected Mobility of 'Immobile' Trace Elements  

NASA Astrophysics Data System (ADS)

The Hawaii Scientific Drilling Project-2 provides the opportunity to investigate the geochemical evolution of the submarine section of Mauna Kea. Our previous analyses of bulk-rock trace element concentrations had revealed relatively high degrees of scatter of trace element ratios such as Th/U, Ta/U and even Nb/Ta, and we suspected that many of the samples had been affected by seawater alteration. Fortunately, fresh glasses are found throughout the drill core in many glass-rich hyaloclastic and pillow basalts with glass proportions up to 10%. We therefore determined incompatible trace elements such as Th, U, Nb, Ta, Zr, Ba, Pb, Rb in carefully handpicked, fresh glasses in 16 samples derived from depths between 1310 m and 3050 m. The samples were crushed to less than 0.425 mm grain size in order to obtain very fresh glass fragments free of contamination by alteration products, olivines or other minerals. The glass fractions and their corresponding bulk samples were analyzed for major and trace elements by EMP, MIC-SSMS and HR-ICPMS. The differences between glass and bulk are particularly obvious in Pb, Rb, Cs and U. As expected, Pb, Rb and Cs were found to be mobile, with concentrations in the bulk samples varying by up to a factor of 5 relative to the glass samples. Similarly, U concentrations in glass are up to a factor of 2 higher than in bulk samples. More surprising is the observation that Th and Ta are quite probably mobile, because these elements are normally believed to be immobile. However, these results are consistent with those of Bienvenue et al. (1990), who found that Th appears to be sensitive to seawater alteration. Our glass data indicate that Ta/U (3.7+/-0.2) is uniform along the sequence, in contrast to the bulk data which show a large scatter (3.7-6.5). Th/U ratios in the glasses show a maximum (~3.5) at a depth of ~2100 m, whereas low ratios of about 3 were found in depths of 1300-1400 m and 2800-3000 m. The high Th/U ratios in the 2100 m region are associated with low SiO2 contents, high 208Pb*/206Pb*(Eisele et al., 2002; Blichert-Toft et al., 2002) and high 3He/4He ratios (Kurz, personal comm., Althaus et al., 2002). Thus, it appears that the high Th/U values are not caused by melting effects but are features of an anomalous source chemistry sampled by the volcano at this stratigraphic level.

Amini, M. A.; Jochum, K. P.; Stoll, B.; Willbold, M.; Sobolev, A. V.; Hofmann, A. W.

2002-12-01

70

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.

71

Validation of Innovative Exploration Technologies for Newberry Volcano: Drill Site Location Map 2010  

SciTech Connect

Newberry seeks to explore "blind" (no surface evidence) convective hydrothermal systems associated with a young silicic pluton on the flanks of Newberry Volcano. This project will employ a combination of innovative and conventional techniques to identify the location of subsurface geothermal fluids associated with the hot pluton. Newberry project drill site location map 2010. Once the exploration mythology is validated, it can be applied throughout the Cascade Range and elsewhere to locate and develop “blind” geothermal resources.

Todd Jaffe

2012-01-01

72

Preliminary results from Submarine Ring of Fire 2012 - NE Lau: First explorations of hydrothermally active volcanoes across the supra-subduction zone and a return to the West Mata eruption site  

NASA Astrophysics Data System (ADS)

Several expeditions in the past few years have shown that the NE Lau basin has one of the densest concentrations of volcanically and hydrothermally active volcanoes on the planet. In 2008 two active submarine volcanic eruptions were discovered during a one week period and subsequent dives with the Jason remotely operated vehicle at one of the sites (West Mata) revealed an active boninite eruption taking place at 1200 m depth. Two dives at the other revealed evidence for recent eruption along the NE Lau Spreading Center. Several more expeditions in 2010-11 discovered additional evidence about the extent and types of hydrothermal activity in this area. Data from CTDO (conductivity, temperature, depth, optical) vertical casts, tow-yos, and towed camera deployments revealed more than 15 hydrothermal sites at water depths from ~800 to 2700 m that include sites from the magmatic arc, the "rear arc," and the back arc spreading centers. These sites range from high temperature black smoker sulfide-producing systems to those dominated by magmatic degassing. Dives by remotely operated vehicle (Quest 4000) in September 2012 will explore these sites and return samples for chemical, biological and geologic studies. One of the dives will be a return visit to West Mata volcano, the site of the deepest submarine eruption yet observed (in 2009). Recent multibeam data reveal large changes in West Mata's summit, suggesting that the nature of the eruption and the location of the erupting vents may have changed. In addition to the preliminary results from the science team, we will also discuss our use and experience with continuous live video transmission (through the High Definition video camera on the Quest 4000) back to shore via satellite and through the internet. Submarine Ring of Fire 2012 Science Team: Bradley Tebo, Bill Chadwick, Ed Baker, Ken Rubin, Susan Merle, Timothy Shank, Sharon Walker, Andra Bobbitt, Nathan Buck, David Butterfield, Eric Olson, John Lupton, Richard Arculus, Fabio Caratori-Tontini, Rick Davis, Kevin Roe, Edward Mitchell, Paula Keener-Chavis Carolyn Sheehan, Peter Crowhurst, Simon Richards,and Volker Ratmeyer along with the Quest-4000 team. .

Resing, J.; Embley, R. W.

2012-12-01

73

How Slab Dip Affects the Location of Volcanoes  

NSDL National Science Digital Library

Students will plot the locations of earthquakes on the top of subducting slabs to determine slab dip and will then develop hypotheses regarding the relationship between slab dip, the depth of the slab, and volcanic activity on the surface.

Beutel, Erin

74

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

75

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 ...

76

Comparison of the submarine landslide by the sector collapse of Oshima-Oshima island in the northern part of Japan with the debris avalanche of off Kaimon volcano in the southern part of Japan and several landslide.  

NASA Astrophysics Data System (ADS)

Oshima-Oshima island is an active volcano located in the eastern margin of the Japan Sea off Hokkaido. Oshima-Oshima consists of Higashi-yama somma, Nishi-yama somma, and the central cone. The latest eruption occurred at the 18th century. In a huge eruption on August 1741 , Nishiyama of western part of Oshima- Oshima collapsed toward the northern submarine slope , and the horseshoe shape caldera was formed. It is proposed by Katsui et al.(1977) , Satake and Kato(2001) that Japan Sea tsunami in 1741 was generated by this collapse. Detailed swath bathymetry surveys have been conducted around Oshima-Oshima by Hydrographic and Oceanographic Department of Japan in 1993. As a result, a large area of debris avalanche deposits has been discovered on the northern submarine flanks of Oshima-Oshima island. In addition, sidescan sonar surveys was also conducted by Hydrographic and Oceanographic Department of Japan and University of Tokyo in 1995. In 1997, the lower part of the debris avalanche deposit was investigated using submersible 'Shinkai 2000' by JAMSTEC(Japan Agency for Marine-Earth Science and Technology). It was confirmed that those deposits were Oshima origins (Kato,1997). We compiled and analyzed using these detailed bathymetry data and sidescan data. As a result , we clarified a detailed geographical features of debris avalanche and the limit of their distribution. Scarp of caldera rim continues to approximately 1100m under the sea. Oshima-Oshima has diameter of approximately 16km. Oshima-Oshima has also an estimated total edifice volume (subaerial and submarine) of 127km3 and rises about 2200m from its base in 1500m depth of water. Northern part of Oshima-Oshima, the scarp of caldera rim on the subaerial area consecutively continues up to about 1100m of depth. The scarp has 100m-300m high, and width of landslide valley is about 2km. Hammocky surface starts from 1100m depth of water. Sea mount of like spur is composed of the collapse deposits has almost extended to the whole area in the trough deeper than 1100m. Debris avalanche deposits have been identified up to 2200m depth and 24km from Oshima-Oshima island, H/L is approximately 0.12. Maximum sizes of debris avalanche block is up to 1-2km width and 100m high. We divided the debris avalanche deposits into three areas (Type A-C) by the topography. Type-A is the main sedimentary area in front of the collapse area and the form is like a spur with 100 to 130m height. Type-B has a form like a knoll or block. Type-C shows gradual slope containing a small rise. We compared these feature with debris avalanche of off Kaimon volcano in the southern part of Japan and the other debris avalanche (landslide, submarine landslide).

Kaji, T.; Yamazaki, H.; Kato, Y.

2007-12-01

77

Submarine sliver in North Kona: A window into the early magmatic and growth history of Hualalai Volcano, Hawaii  

E-print Network

Volcano, Hawaii Julia E. Hammer a,*, Michelle L. Coombs b , Patrick J. Shamberger a , Jun-Ichi Kimura c at dive site S690 (water depth 3412­2104 m) is draped by elongated and truncated pillow lavas-mail address: jhammer@hawaii.edu (J.E. Hammer). Journal of Volcanology and Geothermal Research 151 (2006) 157

Hammer, Julia Eve

78

Submarine landslides in French Polynesia SUBMARINE LANDSLIDES IN SOCIETY AND AUSTRAL ISLANDS,  

E-print Network

Submarine landslides in French Polynesia 1 SUBMARINE LANDSLIDES IN SOCIETY AND AUSTRAL ISLANDS with the age of oceanic islands. Submarine active volcanoes are subject to superficial landslides of fragmental material whereas young islands exhibit marks of mass wasting corresponding to giant lateral collapses due

Clouard, Valerie

79

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

NASA Astrophysics Data System (ADS)

This paper presents the results of submersible dives off Hawaii Islands during four research cruises (R/V Kairei-ROV Kaiko 1998 and 2001, R/V Yokosuka-DSV Shinkai 1999 and 2002) by the Japan Marine Science and Technology Center. Morphologies and structures of submarine volcanic edifices were observed during dives on the Hana Ridge, submarine extension of Haleakala rift zone of East Maui and the south rift zone of Loihi Seamount. Three types of volcanic edifices are recognized: 1) Conical seamount with a small summit and steep slopes [Clague et al., 2000]; 2) Flat-topped cone [Clague et al., 2000] or terrace [Smith et al., 2002] with a wide, flat summit compared to the relative height; 3) Lobate terrace with a hemi-circular lobate outline with a smaller areal ratio of the summit to the base than flat-topped cones. These volcanic edifices are morphologically classified into two groups: Group A (flat-topped cones and lobate terraces) shows a positive correlation of an areal ratio of summit/base with slope. Group B (conical seamounts) has a low areal ratio of summit/base and a positive correlation between a volume and slope. ROV Kaiko and DSV Shinkai dives were carried out on 6 conical seamounts, 5 flat-topped cones and 3 lobate terraces. Conical seamounts with moderate slopes have aprons of elongate pillows and a summit crater filled by lobate sheet flows, which gradually change into elongate pahoehoe flows downslope. Steep cones are surrounded by talus slopes of pillow rubble with elongate pillows sporadically exposed between pillow clasts. Embedded pillow lobes are all elongate downslope, indicating that fragmentation took place while pillows were flowing. Under a very low extrusion rate, flowing lava congealed on the steep slope in a short distance from the source and collapsed into rubble that formed the lower part of the cone. Flat-topped cones have elongate pillows on moderate slopes, and pahoehoe and lobate sheet flows interbedded with pillows on gentle slopes. Flat summits are overlain by lobate sheets but do not have any collapse pits. Successive change in flow morphology from lobate sheets on the summit through pahoehoe sheets into elongate pillows downslope indicates that lava quietly spilt over the crater rim flowed as elongate pillows on steep slopes. Because lobate sheets are present interbedded with pillows in the lower slope, several eruptive episodes with higher extrusion rates of lava were repeated to form the flat-topped cones. Lobate terraces have similar constituents as flat-topped cones but collapse pits on the summit. Lava channels are present both on the bottom of the pits and on the aprons of the terraces, through which lava was rapidly expelled. Lobate terraces are more like a single large inflated sheet flow grown on a gentle ridge that broke out channeled lava at the final stage of growth.

Umino, S.

2003-12-01

80

Active Submarine Volcanoes and Electro-Optical Sensor Networks: The Potential of Capturing and Quantifying an Entire Eruptive Sequence at Axial Seamount, Juan de Fuca Ridge  

NASA Astrophysics Data System (ADS)

The NE Pacific Regional Scale Nodes (RSN) component of the NSF Ocean Observatories Initiative is designed to provide unprecedented electrical power and bandwidth to the base and summit of Axial Seamount. The scientific community is engaged in identifying a host of existing and innovative observation and measurement techniques that utilize the high-power and bandwidth infrastructure and its real-time transmission capabilities. The cable, mooring, and sensor arrays will enable the first quantitative documentation of myriad processes leading up to, during, and following a submarine volcanic event. Currently planned RSN instrument arrays will provide important and concurrent spatial and temporal constraints on earthquake activity, melt migration, hydrothermal venting behavior and chemistry, ambient currents, microbial community structure, high-definition (HD) still images and HD video streaming from the vents, and water-column chemistry in the overlying ocean. Anticipated, but not yet funded, additions will include AUVs and gliders that continually document the spatial-temporal variations in the water column above the volcano and the distal zones. When an eruption appears imminent the frequency of sampling will be increased remotely, and the potential of repurposing the tracking capabilities of the mobile sensing platforms will be adapted to the spatial indicators of likely eruption activity. As the eruption begins mobile platforms will fully define the geometry, temperature, and chemical-microbial character of the volcanic plume as it rises into the thoroughly documented control volume above the volcano. Via the Internet the scientific community will be able to witness and direct adaptive sampling in response to changing conditions of plume formation. A major goal will be to document the eruptive volume and link the eruption duration to the volume of erupted magma. For the first time, it will be possible to begin to quantify the time-integrated output of an underwater volcanic eruption linked to the heat, chemical, and biological fluxes. In the late stages of the event, the dissipation of the "event plume" into the surrounding water column and the plume's migration patterns in the ambient regional flow will be tracked using specifically designed mobile sensor-platforms. The presence of these assets opens the potential for more immediate, coordinated, and thorough event responses than the community has previously been able to mount. Given the relative abundance of information on many variables in a verifiable and archived spatial and temporal context, and the rapidly evolving ability to conduct real-time genomic analyses, our community may be able to secure entirely novel organisms that are released into the overlying ocean only under well-characterized eruptive conditions.

Delaney, J. R.; Kelley, D. S.; Proskurowski, G.; Fundis, A. T.; Kawka, O.

2011-12-01

81

Bayesian statistics applied to the location of the source of explosions at Stromboli Volcano, Italy  

USGS Publications Warehouse

We present a method for determining the location and spatial extent of the source of explosions at Stromboli Volcano, Italy, based on a Bayesian inversion of the slowness vector derived from frequency-slowness analyses of array data. The method searches for source locations that minimize the error between the expected and observed slowness vectors. For a given set of model parameters, the conditional probability density function of slowness vectors is approximated by a Gaussian distribution of expected errors. The method is tested with synthetics using a five-layer velocity model derived for the north flank of Stromboli and a smoothed velocity model derived from a power-law approximation of the layered structure. Application to data from Stromboli allows for a detailed examination of uncertainties in source location due to experimental errors and incomplete knowledge of the Earth model. Although the solutions are not constrained in the radial direction, excellent resolution is achieved in both transverse and depth directions. Under the assumption that the horizontal extent of the source does not exceed the crater dimension, the 90% confidence region in the estimate of the explosive source location corresponds to a small volume extending from a depth of about 100 m to a maximum depth of about 300 m beneath the active vents, with a maximum likelihood source region located in the 120- to 180-m-depth interval.

Saccorotti, G.; Chouet, B.; Martini, M.; Scarpa, R.

1998-01-01

82

Near-real time 3D probabilistic earthquakes locations at Mt. Etna volcano  

NASA Astrophysics Data System (ADS)

Automatic procedure for locating earthquake in quasi-real time must provide a good estimation of earthquakes location within a few seconds after the event is first detected and is strongly needed for seismic warning system. The reliability of an automatic location algorithm is in?uenced by several factors such as errors in picking seismic phases, network geometry, and velocity model uncertainties. On Mt. Etna, the seismic network is managed by INGV and the quasi-real time earthquakes locations are performed by using an automatic-picking algorithm based on short-term-average to long-term-average ratios (STA/LTA) calculated from an approximate squared envelope function of the seismogram, which furnish a list of P-wave arrival times, and the location algorithm Hypoellipse, with a 1D velocity model. The main purpose of this work is to investigate the performances of a different automatic procedure to improve the quasi-real time earthquakes locations. In fact, as the automatic data processing may be affected by outliers (wrong picks), the use of a traditional earthquake location techniques based on a least-square misfit function (L2-norm) often yield unstable and unreliable solutions. Moreover, on Mt. Etna, the 1D model is often unable to represent the complex structure of the volcano (in particular the strong lateral heterogeneities), whereas the increasing accuracy in the 3D velocity models at Mt. Etna during recent years allows their use today in routine earthquake locations. Therefore, we selected, as reference locations, all the events occurred on Mt. Etna in the last year (2011) which was automatically detected and located by means of the Hypoellipse code. By using this dataset (more than 300 events), we applied a nonlinear probabilistic earthquake location algorithm using the Equal Differential Time (EDT) likelihood function, (Font et al., 2004; Lomax, 2005) which is much more robust in the presence of outliers in the data. Successively, by using a probabilistic non linear method (NonLinLoc, Lomax, 2001) and the 3D velocity model, derived from the one developed by Patanè et al. (2006) integrated with that obtained by Chiarabba et al. (2004), we obtained the best possible constraint on the location of the focii expressed as a probability density function (PDF) for the hypocenter location in 3D space. As expected, the obtained results, compared with the reference ones, show that the NonLinLoc software (applied to a 3D velocity model) is more reliable than the Hypoellipse code (applied to layered 1D velocity models), leading to more reliable automatic locations also when outliers are present.

Barberi, G.; D'Agostino, M.; Mostaccio, A.; Patane', D.; Tuve', T.

2012-04-01

83

Buried ostracods collected at the location of a nuclear submarine accident in the Chazhma Cove (Peter the Great Bay, Sea of Japan)  

Microsoft Academic Search

In a sample of benthos collected at the location of a nuclear submarine accident in Chazhma Cove (Peter the Great Bay, Sea\\u000a of Japan), we found remains (valves and shells) of 37 ostracod species, along with living pollution-tolerant organisms. The\\u000a death of ostracods may be due to the consequences of the nuclear accident, but most likely was caused by domestic

E. I. Schornikov; M. A. Zenina

2007-01-01

84

Regional setting of Håkon Mosby Mud Volcano, SW Barents Sea margin  

Microsoft Academic Search

The Håkon Mosby Mud Volcano (HMMV) is a seafloor mud volcano, having a 1-km-diameter circular shape and a relief of 8–10?m.\\u000a HMMV is located within a slide scar on the Bjørnøya glacial submarine fan on the SW Barents Sea slope, and is underlain by\\u000a a >6-km-thick Cenozoic sequence. Multichannel seismic data reveal a 1- to 2-km-wide disturbed zone, which extends

B. O. Hjelstuen; O. Eldholm; J. I. Faleide; P. R. Vogt

1999-01-01

85

Numerical modelling of mud volcanoes and their flows using constraints from the Gulf of Cadiz  

Microsoft Academic Search

It is estimated that the total number of submarine mud volcanoes is between 1000 and 100?000. Because many are associated with greenhouse gases, such as methane, it is argued that the global flux of these gases to the atmosphere from the world’s terrestrial and submarine mud volcanoes is highly significant. Clues to the processes forming submarine mud volcanoes can be

Bramley J. Murton; Juliet Biggs

2003-01-01

86

Locating sources of explosion quakes and long-period events at Yasur volcano, Vanuatu  

NASA Astrophysics Data System (ADS)

Yasur is a small scoria cone located on Tanna Island (South Vanuatu). The cone is composed of 3 vents: two vents (A and B) in the southern crater and one vent (C) in the northern crater. The volcano is going through a permanent strombolian activity, characterized by explosions of gas bubbles and small ash plumes. The activity generates thousands of seismic signals per day, mostly explosion quakes (EQs) and long-period events (LP). From January 2008 to February 2009, seismic activity has been recorded by 12 seismic antennas, each composed of 7 short-period sensors: a 3 components seismometer surrounded by six vertical sensors. Distances between the central seismometer and the others sensors was 20m or 40m. In May 2008, 10 broadband stations have been installed to complete the seismic network. In this work, we present source locations obtained for EQs and LP recorded during the experiment. Each signal, classified in different families of similar events, is located using a seismic triangulation method. This method is based on the calculation of the time delays between each pair of seismometers, allowing to estimate the slowness vector (which contains back-azimuth and apparent velocity) for each antenna. Using a probabilistic approach, the probability density functions of back-azimuth are computed providing the directions of propagation of the wave field. The position of the source is determined by intersecting these directions. To estimate the source depth, we used a method based 1) on the differences of propagation time between the P and the acoustic waves, and 2) on the differences of apparent velocity associated to each family of events. The combination of these two methods allowed to show that the majority of the EQs recorded during the 2008 year came from the south crater and have been located between 250 meters and 700 meters below the surface. Nevertheless, during a few periods lasting for a few days the EQs activity has been located on the north crater roughly at a hundred meters below the surface. In contrast to the EQs whose sources were relatively stable, the long-period activity showed different behaviors according to the periods of time. These behaviors, stability or progressive variation of back-azimuth and apparent velocity, have highlighted source displacements of several hundred meters towards North-East and surface, then towards South only. The comparison of the EQ activity with the LP activity showed few similarity. In general, changes in source location of EQs were not correlated with changes in source location of LP events and conversely. Comparing all these results with previous studies realized at Yasur and Stromboli volcanoes, several assumptions on the volcanic dynamics (depth and mechanisms governing the gas coalescence zone) will be presented.

Perrier, L.; Metaxian, J.; Battaglia, J.; Garaebiti, E.

2010-12-01

87

Stress fields associated with the growth of a large shield volcano (La Palma, Canary Islands)  

Microsoft Academic Search

Measurements of dyke orientations and fault slip data have been taken in 39 stations located in the northern part of the island of La Palma (Canary Archipelago). These structures affect the materials belonging to the submarine growth stage and to the lower units of the subaerial shield volcano stage. Four sets of dykes have been distinguished (Groups I, II, III-1,

Carlos Fernández; Julio de la Nuez; Ramón Casillas; Encarnación García Navarro

2002-01-01

88

Source amplitudes of volcano-seismic signals determined by the amplitude source location method as a quantitative measure of event size  

NASA Astrophysics Data System (ADS)

The amplitude source location (ASL) method, which uses high-frequency amplitudes under the assumption of isotropic S-wave radiation, has been shown to be useful for locating the sources of various types of volcano-seismic signals. We tested the ASL method by using synthetic seismograms and examined the source amplitudes determined by this method for various types of volcano-seismic signals observed at different volcanoes. Our synthetic tests indicated that, although ASL results are not strongly influenced by velocity structure and noise, they do depend on site amplification factors at individual stations. We first applied the ASL method to volcano-tectonic (VT) earthquakes at Taal volcano, Philippines. Our ASL results for the largest VT earthquake showed that a frequency range of 7-12 Hz and a Q value of 50 were appropriate for the source location determination. Using these values, we systematically estimated source locations and amplitudes of VT earthquakes at Taal. We next applied the ASL method to long-period events at Cotopaxi volcano and to explosions at Tungurahua volcano in Ecuador. We proposed a practical approach to minimize the effects of site amplifications among different volcano seismic networks, and compared the source amplitudes of these various volcano-seismic events with their seismic magnitudes. We found a proportional relation between seismic magnitude and the logarithm of the source amplitude. The ASL method can be used to determine source locations of small events for which onset measurements are difficult, and thus can estimate the sizes of events over a wider range of sizes compared with conventional hypocenter determination approaches. Previously, there has been no parameter widely used to quantify the sources of volcano-seismic signals. This study showed that the source amplitude determined by the ASL method may be a useful quantitative measure of volcano-seismic event size.

Kumagai, Hiroyuki; Lacson, Rudy; Maeda, Yuta; Figueroa, Melquiades S.; Yamashina, Tadashi; Ruiz, Mario; Palacios, Pablo; Ortiz, Hugo; Yepes, Hugo

2013-05-01

89

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.

90

Seismic swarm associated with the 2008 eruption of Kasatochi Volcano, Alaska: Earthquake locations and source parameters  

Microsoft Academic Search

An energetic seismic swarm accompanied an eruption of Kasatochi Volcano in the central Aleutian volcanic arc in August of 2008. In retrospect, the first earthquakes in the swarm were detected about 1 month prior to the eruption onset. Activity in the swarm quickly intensified less than 48 h prior to the first large explosion and subsequently subsided with decline of

Natalia A. Ruppert; Stephanie Prejean; Roger A. Hansen

2011-01-01

91

Identifying elements of the plumbing system beneath Kilauea Volcano, Hawaii, from the source locations of very-long-period signals  

USGS Publications Warehouse

We analyzed 16 seismic events recorded by the Hawaiian broad-band seismic network at Kilauca Volcano during the period September 9-26, 1999. Two distinct types of event are identified based on their spectral content, very-long-period (VLP) waveform, amplitude decay pattern and particle motion. We locate the VLP signals with a method based on analyses of semblance and particle motion. Different source regions are identified for the two event types. One source region is located at depths of ~1 km beneath the northeast edge of the Halemaumau pit crater. A second region is located at depths of ~8 km below the northwest quadrant of Kilauea caldera. Our study represents the first time that such deep sources have been identified in VLP data at Kilauea. This discovery opens the possibility of obtaining a detailed image of the location and geometry of the magma plumbing system beneath this volcano based on source locations and moment tensor inversions of VLP signals recorded by a permanent, large-aperture broad-band network.

Almendros, J.; Chouet, B.; Dawson, P.; Bond, T.

2002-01-01

92

A Newly Recognized Shield Volcano Southwest of Oahu Island, Hawaii  

Microsoft Academic Search

During the 2001 Hawaiian cruise of the JAMSTEC research ship Kairei (with ROV-Kaiko; P.I.: E. Takahashi, Co P.I.: T. Kanamatsu), Seabeam mapping revealed a previously unidentified volcanic edifice (submarine shield) located about 100 km southwest of Oahu. The volcano (centered at 21\\\\deg35'N, 158\\\\deg45'W) is approximately 100 km in diameter and 0.5 km high with its summit at 4200 m depth.

E. Takahashi; J. G. Moore; H. Yokose; D. A. Clague; M. Nakagawa; T. Kani; M. Coombs; G. Moore; Y. Harada; T. Kunikiyo; J. Robinson

2001-01-01

93

Flank Instability Phenomena of the Sciara del Fuoco at Stromboli Volcano, Italy: Recent Evidence From a Multidisciplinary Study  

Microsoft Academic Search

The Sciara del Fuoco (SDF) at Stromboli volcano, located in the western side of the homonymous island, is a deep scar prone to phenomena of flank instability, such as rockfalls and flowing debris. By 30 December, 2002, landslides associated with tsunami waves affected both the sub aerial and submarine part of SDF two days after the onset of a new

S. Falsaperla; M. Neri; E. Pecora; S. Spampinato; H. Langer

2005-01-01

94

Microbial Communities in Sunken Wood Are Structured by Wood-Boring Bivalves and Location in a Submarine Canyon  

PubMed Central

The cornerstones of sunken wood ecosystems are microorganisms involved in cellulose degradation. These can either be free-living microorganisms in the wood matrix or symbiotic bacteria associated with wood-boring bivalves such as emblematic species of Xylophaga, the most common deep-sea woodborer. Here we use experimentally submerged pine wood, placed in and outside the Mediterranean submarine Blanes Canyon, to compare the microbial communities on the wood, in fecal pellets of Xylophaga spp. and associated with the gills of these animals. Analyses based on tag pyrosequencing of the 16S rRNA bacterial gene showed that sunken wood contained three distinct microbial communities. Wood and pellet communities were different from each other suggesting that Xylophaga spp. create new microbial niches by excreting fecal pellets into their burrows. In turn, gills of Xylophaga spp. contain potential bacterial symbionts, as illustrated by the presence of sequences closely related to symbiotic bacteria found in other wood eating marine invertebrates. Finally, we found that sunken wood communities inside the canyon were different and more diverse than the ones outside the canyon. This finding extends to the microbial world the view that submarine canyons are sites of diverse marine life. PMID:24805961

Fagervold, Sonja K.; Romano, Chiara; Kalenitchenko, Dimitri; Borowski, Christian; Nunes-Jorge, Amandine; Martin, Daniel; Galand, Pierre E.

2014-01-01

95

Application of near real-time radial semblance to locate the shallow magmatic conduit at Kilauea Volcano, Hawaii  

USGS Publications Warehouse

Radial Semblance is applied to broadband seismic network data to provide source locations of Very-Long-Period (VLP) seismic energy in near real time. With an efficient algorithm and adequate network coverage, accurate source locations of VLP energy are derived to quickly locate the shallow magmatic conduit system at Kilauea Volcano, Hawaii. During a restart in magma flow following a brief pause in the current eruption, the shallow magmatic conduit is pressurized, resulting in elastic radiation from various parts of the conduit system. A steeply dipping distribution of VLP hypocenters outlines a region extending from sea level to about 550 m elevation below and just east of the Halemaumau Pit Crater. The distinct hypocenters suggest the shallow plumbing system beneath Halemaumau consists of a complex plexus of sills and dikes. An unconstrained location for a section of the conduit is also observed beneath the region between Kilauea Caldera and Kilauea Iki Crater.

Dawson, P.; Whilldin, D.; Chouet, B.

2004-01-01

96

The red triangles are volcano locations. Dark-orange areas have a higher volcanic hazard; light-orange areas have a lower volcanic hazard. Dark-gray areas have a higher ash fall hazard;  

E-print Network

The red triangles are volcano locations. Dark-orange areas have a higher volcanic hazard; light from volcanoes are escalating as more and more people live, work, play, and travel in volcanic regions. Since 1980, 45 eruptions and 15 cases of notable volcanic unrest have occurred at 33 U.S. volcanoes

Torgersen, Christian

97

Submarine Atmospheres  

Microsoft Academic Search

Atmosphere control in submarines has developed to meet the operational requirements. Until\\u000a the end of WWII submarines were primarily semi-submersibles spending most of their time on the surface\\u000a and submerged for periods of 12 h or less. However, rudimentary control of oxygen and carbon\\u000a dioxide was available in some WWI boats. In the latter years of WWII, the requirement for longer

Waldemar Mazurek

98

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

99

Submarine Volcanic Cones in the São Miguel Region/Azores  

NASA Astrophysics Data System (ADS)

São Miguel, the main island of the Azores Archipelago, is located in an area ~1500 km west of Portugal where the American, African and Eurasian plates converge. Just as well as the other eight Azorian islands, it is of volcanic origin and therefore volcanic processes also play an important role for the evolution of its submarine domain. Around 300 submarine volcanic cones have been mapped in the vicinity of São Miguel Island with multi-beam data during RV Meteor cruise M79/2 . They are distributed in depth down to 3000 m. They exhibit an average diameter of 600 m, an average slope of 22° and heights mainly between 50 and 200 m, slightly decreasing with increasing water depth. Even if their morphological appearances show no segregation, the volcanic setting can be classified in three different categories. A numerous amount of cones are located on the submarine flank of Sete Cidades Volcano in the west of São Miguel considered as parasitic structures, whereas in the very east they build up an own superstructure possibly reflecting an early submarine stadium of a posterior subaerial stratovolcano like Sete Cidades. The third class is controlled by and orientated along faults, most of them in a graben system southwest of the Island. High-resolution multichannel seismic data depicts that the graben cones extinguished synchronously in the past most likely accompanying with the end of graben formation. Backscatter data reveal a rough surface possibly caused by currents removing the fine grain-size fraction over time. However, a young cone investigated in detail is characterized by a smooth surface, a distal increasing stratification and concave shaped flanks. Other few exhibit craters, all together indicating rather a phreatomagmatic than an effusive evolution of these structures. Very similar in size and shape to cinder cones on-shore São Miguel Island, they appear to be their submarine equivalent.

Weiß, Benedikt; Hübscher, Christian; Wolf, Daniela

2014-05-01

100

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.

101

Determining the seismic source mechanism and location for an explosive eruption with limited observational data: Augustine Volcano, Alaska  

NASA Astrophysics Data System (ADS)

Waveform inversions of the very-long-period components of the seismic wavefield produced by an explosive eruption that occurred on 11 January, 2006 at Augustine Volcano, Alaska constrain the seismic source location to near sea level beneath the summit of the volcano. The calculated moment tensors indicate the presence of a volumetric source mechanism. Systematic reconstruction of the source mechanism shows the source consists of a sill intersected by either a sub-vertical east-west trending dike or a sub-vertical pipe and a weak single force. The trend of the dike may be controlled by the east-west trending Augustine-Seldovia arch. The data from the network of broadband sensors is limited to fourteen seismic traces, and synthetic modeling confirms the ability of the network to recover the source mechanism. The synthetic modeling also provides a guide to the expected capability of a broadband network to resolve very-long-period source mechanisms, particularly when confronted with limited observational data.

Dawson, Phillip B.; Chouet, Bernard A.; Power, John

2011-02-01

102

Epsilon-Proteobacterial Dominance in Microbial Mats Located at the Champagne Hydrothermal Vent Site on NW Eifuku Volcano, Mariana Arc  

NASA Astrophysics Data System (ADS)

By far the most extensive hydrothermal vent related microbial mats discovered during the 2004 Ring of Fire cruise were those found at NW Eifuku Volcano located along the Mariana Island Arc. The Champagne Hydrothermal Vent Site located near the summit of NW Eifuku Volcano (1,650 meters below sea level) consists of multiple white smoker chimneys venting highly gaseous fluids (Max temp ˜103° C). Large amounts of liquid carbon dioxide bubbles and clathrates were observed exuding from the seafloor contributing to an extremely low Eh (i.e., highly reducing conditions) and giving the location its name. Luxuriant white flocculent mats were discovered and collected in and around the Champagne Vent Site in April, 2004. Molecular analyses of small subunit ribosomal DNA (SSU rDNA) from these mats using both T-RFLP community fingerprinting and PCR-generated clone library analyses showed that the bacterial community is dominated by ? -Proteobacteria represented by the thiovulum-group along with lesser levels of Thermotogales represented by the thermotoga-group (as determined using the Ribosomal Database Project). Initial estimates of the relative abundance of phylotypes place the thiovulum-group at 50% and 67%, and the thermotoga-group at 18% and 9%, for T-RFLP and clone library methods, respectively. Phylogenetic analysis of SSU rDNA sequence data also suggests that these most dominant phylotypes are most likely chemoautotrophic and involved in sulfur-cycling. Due to the extreme nature of their habitat, many of these bacteria often grow where no macrofauna are present. However, on the edges of these areas, once sufficient mixing has taken place, abundant macrofauna can be seen vigorously feeding upon these microbial mats. This further demonstrates the transfer of chemosynthetically-derived energy up the food chain supporting large communities of macrofauna. Similar types of microbial mats have been observed at Axial Volcano on the Juan de Fuca Ridge, where they were dominated by a diverse community of ? -Proteobacteria known to both oxidize and reduce multiple sulfur compounds.

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

2004-12-01

103

The Fukuyama volcanic rocks: Submarine composite volcano in the Late Miocene to Early Pliocene Akita-Yamagata back-arc basin, northeast Honshu, Japan  

NASA Astrophysics Data System (ADS)

The Fukuyama Volcanic Rocks are composed of pyroxene andesite (FKV-1), hornblende-pyroxene andesite (FKV-2), biotite-hornblende dacite (FKV-3) and volcaniclastic debris-flow deposits and/or turbidites. FKV-1, FKV-2 and FKV-3 are medium-K calc-alkaline rocks depleted in Nd, similar to other back-arc volcanic rocks of the northeast Japan arc and constitute a dome cluster at Fukuyama. Volcaniclastic beds surround the dome cluster and thin and fine upwards. The predominant clast type in the volcaniclastic beds changes upwards from pyroxene andesite, through hornblende-pyroxene andesite, to biotite-hornblende dacite, consistent with the stratigraphic relationships of FKV-1, FKV-2 and FKV-3 lavas. All the siltstones inter-bedded with the volcaniclastic beds and overlying the whole succession contain diatom fossils indicative of the lower part of the Thalassionema schraderi zone (7.8 Ma to 8.5 Ma), compatible with the isotopic ages of FKV-1, FKV-2 and FKV-3. The Fukuyama volcano has a total eruption volume of 60-100 km 3, with a lifetime of the order of 10 5 years, as typically observed for volcanoes in the present back-arc region of northeast Honshu. FKV-1 erupted in deep water and partly disintegrated into hyaloclastite breccias due to direct contact with water. FKV-2 lava repeatedly effused over the FKV-1 lava and produced a volcanic apron of breccias that eventually grew above wave base and was eroded by wave action. The magma of FKV-3 was probably hydrous as it contains biotite and hornblende. The FKV-3 magma could have explosively erupted from a shallow-water dome or vent emergent above the wave base, followed by growth of a degassing lava dome. Repose between eruptions allowed accumulation of silt, and after the Fukuyama eruptions ceased silt entirely mantled the volcano. A small magma supply rate perhaps allowed a relatively long period of quiescence between eruptions of FKV-1, FKV-2 and FKV-3 magmas, resulting in abrasion and reworking of volcanic fragments and accumulation of non-volcanic sediments that constitute part of the volcaniclastic apron. Oil generated in the contemporaneous or underlying sediments, migrated to the upper levels of the volcaniclastic apron and accumulated there under the thick cover of fine-grained sediments that mantle the volcano.

Yagi, Masahiko; Ohguch, Takeshi; Akiba, Fumio; Yoshida, Takeyoshi; Tiba, Tokiko

2009-10-01

104

Cutting Costs by Locating High Production Wells: A Test of the Volcano seismic Approach to Finding ''Blind'' Resources  

SciTech Connect

In the summer of 2000, Duke University and the Kenyan power generation company, KenGen, conducted a microearthquake monitoring experiment at Longonot volcano in Kenya. Longonot is one of several major late Quaternary trachyte volcanoes in the Kenya Rift. They study was aimed at developing seismic methods for locating buried hydrothermal areas in the Rift on the basis of their microearthquake activity and wave propagation effects. A comparison of microearthquake records from 4.5 Hz, 2 Hz, and broadband seismometers revealed strong high-frequency site and wave-propagation effects. The lower frequency seismometers were needed to detect and record individual phases. Two-dozen 3-component 2- Hz L22 seismographs and PASSCAL loggers were then distributed around Longonot. Recordings from this network located one seismically active area on Longonot's southwest flank. The events from this area were emergent, shallow (<3 km), small (M<1), and spatially restricted. Evidently, the hydrothermal system in this area is not currently very extensive or active. To establish the nature of the site effects, the data were analyzed using three spectral techniques that reduce source effects. The data were also compared to a simple forward model. The results show that, in certain frequency ranges, the technique of dividing the horizontal motion by the vertical motion (H/V) to remove the source fails because of non-uniform vertical amplification. Outside these frequencies, the three methods resolve the same, dominant, harmonic frequencies at a given site. In a few cases, the spectra can be fit with forward models containing low velocity surface layers. The analysis suggests that the emergent, low frequency character of the microearthquake signals is due to attenuation and scattering in the near surface ash deposits.

Eylon Shalev; Peter E. Malin; Wendy McCausland

2002-06-06

105

High-precision earthquake location and three-dimensional P wave velocity determination at Redoubt Volcano, Alaska  

Microsoft Academic Search

Redoubt Volcano, Alaska poses significant volcanic hazard to the Cook Inlet region and overlying flight paths. During and following the most recent eruption in 1989–1990 the Alaska Volcano Observatory deployed up to 10 seismometers to improve real-time monitoring capabilities at Redoubt and continues to produce an annual earthquake catalog with associated arrival times for this volcano. We compute a three-dimensional

Heather R. DeShon; Clifford H. Thurber; Charlotte Rowe

2007-01-01

106

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

107

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

108

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

109

Moment tensor inversion for the source location and mechanism of long period (LP) seismic events from 2009 at Turrialba volcano, Costa Rica  

NASA Astrophysics Data System (ADS)

Long-period (LP) seismic events were recorded during the temporary installation of a broadband seismic network of 13 stations from March to September 2009 on Turrialba volcano, Costa Rica. Over 6000 LPs were extracted using a modified STA/LTA method and a family consisting of 435 similar LP events has been identified. For the first time at Turrialba volcano, full-waveform moment tensor inversion is performed to jointly determine the location and source mechanism of the events. The LPs in the family are likely to be caused by crack mechanisms dipping towards the southwest at angles of approximately 10 to 20°, located at shallow depths (< 800 m) below the active Southwest and Central craters. As the locations are so shallow, the most probable causes of crack mechanisms are hydrothermal fluids resonating within or "pulsing" through a crack. The waveforms observed at the summit stations suggest a "pulsing" mechanism, but source resonance with a high degree of damping is also possible.

Eyre, Thomas S.; Bean, Christopher J.; De Barros, Louis; O'Brien, Gareth S.; Martini, Francesca; Lokmer, Ivan; Mora, Mauricio M.; Pacheco, Javier F.; Soto, Gerardo J.

2013-05-01

110

THE SUBMARINE REVIEW FIXED SONAR SYSTEMS  

E-print Network

in the early 1950's. It was designed using breakthrough discoveries of the propagation paths of sound through to locate submarines that were able to stay below the surface of the ocean for longer periods of time deployed along the ocean floor in strategic areas, designed to detect an enemy submarine as she either left

111

How Submarines Work  

NSDL National Science Digital Library

In this article, presented by HowStuffWorks.com, shows how a submarine dives and surfaces in the water. It also shows how life support is maintained, how the submarine gets its power, how a submarine finds its way in the deep ocean and how submarines might be rescued. The article addresses many points effectively and is a good survey of the topic.

Brain, Marshall; Freudenrich, Craig

2008-10-09

112

Deep Research Submarine  

E-print Network

The Deep Sea Research Submarine (Figure 1) is a modified VIRGINIA Class Submarine that incorporates a permanently installed Deep Sea Operations Compartment (Figure 2). Table 1 summarizes the characteristics of the Deep ...

Woertz, Jeff

2002-02-01

113

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

114

SUBMARINE AUTOMATION: DEMONSTRATION #5  

Microsoft Academic Search

This paper describes the results obtained in the final performing period of the ARPA sponsored submarine automation project1. Efforts on the mapping between the submarine operational environment and the RCS software architecture lead to the result of three watch station graphic user interface panels. The submarine automation model has been expanded to include some engineering systems control capability. On the

Hui-Min Huang; Richard Quintero

115

Argon geochronology of Kilauea's early submarine history  

USGS Publications Warehouse

Submarine alkalic and transitional basalts collected by submersible along Kilauea volcano's south flank represent early eruptive products from Earth's most active volcano. Strongly alkalic basalt fragments sampled from volcaniclastic deposits below the mid-slope Hilina Bench yield 40Ar/39Ar ages from 212 ?? 38 to 280 ?? 20 ka. These ages are similar to high-precision 234 ?? 9 and 239 ?? 10 ka phlogopite ages from nephelinite clasts in the same deposits. Above the mid-slope bench, two intact alkalic to transitional pillow lava sequences protrude through the younger sediment apron. Samples collected from a weakly alkalic basalt section yield 138 ?? 30 to 166 ?? 26 ka ages and others from a transitional basalt section yield 138 ?? 115 and 228 ?? 114 ka ages. The ages are incompatible with previous unspiked K-Ar studies from samples in deep drill holes along the east rift of Kilauea. The submarine birth of Kilauea volcano is estimated at <300 ka. If the weakly alkalic sequence we dated is representative of the volcano as a whole, the transition from alkalic to tholeiitic basalt compositions is dated at ??? 150 ka. ?? 2005 Elsevier B.V. All rights reserved.

Calvert, A.T.; Lanphere, M.A.

2006-01-01

116

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

117

Submarine Fernandina: Magmatism at the leading edge of the Galápagos hot spot  

Microsoft Academic Search

New multibeam and side-scan sonar surveys of Fernandina volcano and the geochemistry of lavas provide clues to the structural and magmatic development of Galápagos volcanoes. Submarine Fernandina has three well-developed rift zones, whereas the subaerial edifice has circumferential fissures associated with a large summit caldera and diffuse radial fissures on the lower slopes. Rift zone development is controlled by changes

Dennis J. Geist; Daniel J. Fornari; Mark D. Kurz; Karen S. Harpp; S. Adam Soule; Michael R. Perfit; Alison M. Koleszar

2006-01-01

118

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

119

Research on the Web: Deep Sea Volcanoes and Vents  

NSDL National Science Digital Library

This Web research project gives students a close-up look at the dynamic forces at work in the deep seas. They'll work as scientists, making observations and recording their findings. Students begin by gathering background information on submarine volcanoes and mid-ocean ridges. They then compare volcanic activity on land with submarine volcanoes, noting the effects of near-freezing temperatures and incredibly intense pressure on volcanoes on the ocean floor. They end by viewing real-time videos of deep sea vents in motion.

120

Using Ambient Noise Fields for Submarine Team #525 for the Mathematical Contest in Modeling  

E-print Network

that the measurements of sound are to be made by an array of transducers (piezo-electric crystal microphones) suspen with transducers, submarine, and planar noise waves transducer array Page 3 of 30 #12;#525 Submarine LocationUsing Ambient Noise Fields for Submarine Location Team #525 for the Mathematical Contest

Mitchener, W. Garrett

121

Microbiological Conditions on Oberon Submarines.  

National Technical Information Service (NTIS)

Microbiological conditions on Oberon submarines were examined to gain an insight into the potential effects on submariners' health. Samples from submarine atmospheres showed that satisfactory standards could be attained. However, samples taken from surfac...

J. F. Upsher, L. E. Fletcher, C. M. Upsher

1994-01-01

122

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.

123

Mud Volcanoes - Analogs to Martian Cones and Domes (by the Thousands!)  

NASA Technical Reports Server (NTRS)

Mud volcanoes are mounds formed by low temperature slurries of gas, liquid, sediments and rock that erupt to the surface from depths of meters to kilometers. They are common on Earth, with estimates of thousands onshore and tens of thousands offshore. Mud volcanoes occur in basins with rapidly-deposited accumulations of fine-grained sediments. Such settings are ideal for concentration and preservation of organic materials, and mud volcanoes typically occur in sedimentary basins that are rich in organic biosignatures. Domes and cones, cited as possible mud volcanoes by previous authors, are common on the northern plains of Mars. Our analysis of selected regions in southern Acidalia Planitia has revealed over 18,000 such features, and we estimate that more than 40,000 occur across the area. These domes and cones strongly resemble terrestrial mud volcanoes in size, shape, morphology, associated flow structures and geologic setting. Geologic and mineralogic arguments rule out alternative formation mechanisms involving lava, ice and impacts. We are studying terrestrial mud volcanoes from onshore and submarine locations. The largest concentration of onshore features is in Azerbaijan, near the western edge of the Caspian Sea. These features are typically hundreds of meters to several kilometers in diameter, and tens to hundreds of meters in height. Satellite images show spatial densities of 20 to 40 eruptive centers per 1000 square km. Many of the features remain active, and fresh mud flows as long as several kilometers are common. A large field of submarine mud volcanoes is located in the Gulf of Cadiz, off the Atlantic coasts of Morocco and Spain. High-resolution sonar bathymetry reveals numerous km-scale mud volcanoes, hundreds of meters in height. Seismic profiles demonstrate that the mud erupts from depths of several hundred meters. These submarine mud volcanoes are the closest morphologic analogs yet found to the features in Acidalia Planitia. We are also conducting laboratory analyses of surface samples collected from mud volcanoes in Azerbaijan, Taiwan and Japan. X-ray diffraction, visible / near infrared reflectance spectroscopy and Raman spectroscopy show that the samples are dominated by mixed-layer smectite clays, along with quartz, calcite and pyrite. Thin section analysis by optical and scanning electron microscopy confirms the mineral identifications. These samples also contain chemical and morphological biosignatures, including common microfossils, with evidence of partial replacement by pyrite. The bulk samples contain approximately 1 wt% total organic carbon and 0.4 mg / gm volatile hydrocarbons. The thousands of features in Acidalia Planitia cited as analogous to terrestrial mud volcanoes clearly represent an important element in the sedimentary record of Mars. Their location, in the distal depocenter for massive Hesperian-age floods, suggests that they contain fine-grained sediments from a large catchment area in the martian highlands. We have proposed these features as a new class of exploration target that can provide access to minimally-altered material from significant depth. By analogy to terrestrial mud volcanoes, these features may also be excellent sites for the sampling martian organics and subsurface microbial life, if such exist or ever existed.

Allen, Carlton C.; Oehler, Dorothy

2010-01-01

124

Mud Volcanoes - Analogs to Martian Cones and Domes (by the thousands !)  

NASA Astrophysics Data System (ADS)

Mud volcanoes are mounds formed by low temperature slurries of gas, liquid, sediments and rock that erupt to the surface from depths of meters to kilometers. They are common on Earth, with estimates of thousands onshore and tens of thousands offshore. Mud volcanoes occur in basins with rapidly-deposited accumulations of fine-grained sediments. Such settings are ideal for concentration and preservation of organic materials, and mud volcanoes typically occur in sedimentary basins that are rich in organic biosignatures. Domes and cones, cited as possible mud volcanoes by previous authors, are common on the northern plains of Mars. Our analysis of selected regions in southern Acidalia Planitia has revealed over 18,000 such features, and we estimate that more than 40,000 occur across the area. These domes and cones strongly resemble terrestrial mud volcanoes in size, shape, morphology, associated flow structures and geologic setting. Geologic and mineralogic arguments rule out alternative formation mechanisms involving lava, ice and impacts. We are studying terrestrial mud volcanoes from onshore and submarine locations. The largest concentration of onshore features is in Azerbaijan, near the western edge of the Caspian Sea. These features are typically hundreds of meters to several kilometers in diameter, and tens to hundreds of meters in height. Satellite images show spatial densities of 20 to 40 eruptive centers per 1000 km2. Many of the features remain active, and fresh mud flows as long as several kilometers are common. A large field of submarine mud volcanoes is located in the Gulf of Cadiz, off the Atlantic coasts of Morocco and Spain. High-resolution sonar bathymetry reveals numerous km-scale mud volcanoes, hundreds of meters in height. Seismic profiles demonstrate that the mud erupts from depths of several hundred meters. These submarine mud volcanoes are the closest morphologic analogs yet found to the features in Acidalia Planitia. We are also conducting laboratory analyses of surface samples collected from mud volcanoes in Azerbaijan, Taiwan and Japan. X-ray diffraction, visible / near infrared reflectance spectroscopy and Raman spectroscopy show that the samples are dominated by mixed-layer smectite clays, along with quartz, calcite and pyrite. Thin section analysis by optical and scanning electron microscopy confirms the mineral identifications. These samples also contain chemical and morphological biosignatures, including common microfossils, with evidence of partial replacement by pyrite. The bulk samples contain approximately 1 wt% total organic carbon and 0.4 mg / gm volatile hydrocarbons. The thousands of features in Acidalia Planitia cited as analogous to terrestrial mud volcanoes clearly represent an important element in the sedimentary record of Mars. Their location, in the distal depocenter for massive Hesperian-age floods, suggests that they contain fine-grained sediments from a large catchment area in the martian highlands. We have proposed these features as a new class of exploration target that can provide access to minimally-altered material from significant depth. By analogy to terrestrial mud volcanoes, these features may also be excellent sites for the sampling martian organics and subsurface microbial life, if such exist or ever existed.

Allen, C.; Oehler, D.

2010-12-01

125

Geochronology, geochemistry and geophysics of Mahukona Volcano, Hawai`i  

NASA Astrophysics Data System (ADS)

Mahukona is an extinct submarine volcano that fills a gap in the Loa-trend of paired Hawaiian volcanoes between Hualalai and Kaho`olawe. A new marine survey of the seamount was undertaken in an attempt to resolve the location of the volcano’s summit. The multibeam bathymetry showed no clear summit. The gravity data reveals a central oval-shaped residual gravity anomaly with a maximum density 85 kg/m3 greater than the surrounding edifice, which could be the frozen magmatic center of Mahukona. Eighteen weakly to strongly olivine-phyric samples were collected by submersible from the shallower parts (>2 km) of the volcano to supplement previous dredged samples. These fresh, mostly glassy samples vary from low-silica tholeiites to weakly alkali basalts. Ar-Ar weighted plateau ages range from 653 ka for a tholeiite to 479 and 351 ka for transitional basalts. These ages straddle the predicted age for the end of shield building (435 ka) and are older than previous ages for transitional basalts (310-298 ka; Clague and Calvert, 2008). Trace elements show a moderate range of variability (33% for Ba and Nb) and parallel primitive mantle normalized patterns suggesting variable degrees of melting of a similar source. Zr/Nb ratios for this Loa chain volcano (11-14) span the Loa-Kea boundary. Pb, Sr, Nd and Hf isotope ratios for 12 samples are distinct from adjacent Kohala volcano with Loihi-like values, although they are slightly higher in Hf and Nd at a given Pb isotope value. Most samples have Loa-like Pb isotope ratios, although two tholeiites have Kea-like ratios but high, Loa-like Zr/Nb. Sr isotopes are well correlated with the other isotopic systems indicating no ancient carbonate-rich sediment source component is needed. Mahukona He isotope ratios overlap with those found at Lo`ihi Seamount. Higher values are found in transitional basalts and lower in the tholeiites (16-21 vs. 12-14 Ra), which is opposite to other Hawaiian volcanoes. With high-precision data sets for more volcanoes along the Hawaiian chain in multiple stages of growth, we will be able to resolve the fine structure and evolution of the Hawaiian plume. Clague, D. and Calvert, A. 2008. Bull. Volcanol.

Hanano, D.; Garcia, M. O.; Weis, D. A.; Flinders, A. F.; Ito, G.; Kurz, M. D.

2009-12-01

126

Earthquake classification, location, and error analysis in a volcanic environment: implications for the magmatic system of the 1989-1990 eruptions at redoubt volcano, Alaska  

USGS Publications Warehouse

Determination of the precise locations of seismic events associated with the 1989-1990 eruptions of Redoubt Volcano posed a number of problems, including poorly known crustal velocities, a sparse station distribution, and an abundance of events with emergent phase onsets. In addition, the high relief of the volcano could not be incorporated into the hypoellipse earthquake location algorithm. This algorithm was modified to allow hypocenters to be located above the elevation of the seismic stations. The velocity model was calibrated on the basis of a posteruptive seismic survey, in which four chemical explosions were recorded by eight stations of the permanent network supplemented with 20 temporary seismographs deployed on and around the volcanic edifice. The model consists of a stack of homogeneous horizontal layers; setting the top of the model at the summit allows events to be located anywhere within the volcanic edifice. Detailed analysis of hypocentral errors shows that the long-period (LP) events constituting the vigorous 23-hour swarm that preceded the initial eruption on December 14 could have originated from a point 1.4 km below the crater floor. A similar analysis of LP events in the swarm preceding the major eruption on January 2 shows they also could have originated from a point, the location of which is shifted 0.8 km northwest and 0.7 km deeper than the source of the initial swarm. We suggest this shift in LP activity reflects a northward jump in the pathway for magmatic gases caused by the sealing of the initial pathway by magma extrusion during the last half of December. Volcano-tectonic (VT) earthquakes did not occur until after the initial 23-hour-long swarm. They began slowly just below the LP source and their rate of occurrence increased after the eruption of 01:52 AST on December 15, when they shifted to depths of 6 to 10 km. After January 2 the VT activity migrated gradually northward; this migration suggests northward propagating withdrawal of magma from a plexus of dikes and/or sills located in the 6 to 10 km depth range. Precise relocations of selected events prior to January 2 clearly resolve a narrow, steeply dipping, pencil-shaped concentration of activity in the depth range of 1-7 km, which illuminates the conduit along which magma was transported to the surface. A third event type, named hybrid, which blends the characteristics of both VT and LP events, originates just below the LP source, and may reflect brittle failure along a zone intersecting a fluid-filled crack. The distribution of hybrid events is elongated 0.2-0.4 km in an east-west direction. This distribution may offer constraints on the orientation and size of the fluid-filled crack inferred to be the source of the LP events. ?? 1994.

Lahr, J. C.; Chouet, B. A.; Stephens, C. D.; Power, J. A.; Page, R. A.

1994-01-01

127

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

128

Introduction Submarine debris-flow deposits are often accompanied  

E-print Network

Introduction Submarine debris-flow deposits are often accompanied by isolated blocks located some landslides. A more general review on the mobility of submarine debris flows is given in this spe- cial issue by De Blasio et al. (2006a). Recently, we have investigated a simple hydrodynamic model of a rigid block

129

Tectonic and magmatic controls on the location of post-subduction monogenetic volcanoes in Baja California, Mexico, revealed through spatial analysis of eruptive vents  

NASA Astrophysics Data System (ADS)

Post-subduction (12.5 Ma to less than 1 Ma) monogenetic volcanism on the Baja California peninsula, Mexico, formed one of the densest intra-continental areas of eruptive vents on Earth. It includes about 900 vents within an area ˜700 km long (N-S) and 70 to 150 km wide (W-E). This study shows that post-subduction volcanic activity was distributed along this arc and that modes exist in the volcano distribution, indicating that productivity of the magma source region was not uniform along the length of the arc. Vent clustering, vent alignments, and cone elongations were measured within eight monogenetic volcanic fields located along the peninsula. Results indicate that on a regional scale, vent clustering varies from north to south with denser spatial clustering in the north on the order of 1.9 × 10-1 vents/km2 to less dense clustering in the south on the order of 7.8 × 10-2 vents/km2. San Quintin, San Carlos, Jaraguay, and Santa Clara are spatially distinct volcanic fields with higher eruptive vent densities suggesting the existence of individual melt columns that may have persisted over time. In contrast, the San Borja, Vizcaino, San Ignacio, and La Purisima vent fields show lower degrees of vent clustering and no obvious spatial gaps between fields, thus indicating an area of more distributed volcanism. Insight into the lithospheric stress field can be gained from vent alignments and vent elongation measurements. Within the fields located along the extinct, subduction-related volcanic arc, elongation patterns of cinder cones and fissure-fed spatter cones, vent clusters, and vent alignments trend NW-SE and N-S. Within the Santa Clara field, located more to the west within the forearc, elongation patterns of the same volcanic features trend NE-SW. These patterns suggest that magmatism was more focused in the forearc and in the northern part of Baja California than in its southern region. Within the extinct arc, magma ascent created volcano alignments and elongate cones parallel to NW-SE to N-S oriented tectonic structures. In the forearc, the existence of N-S and NE-SW oriented volcanic features indicates a rotation in the stress field orientation compared to the arc.

Germa, Aurélie; Connor, Laura J.; Cañon-Tapia, Edgardo; Le Corvec, Nicolas

2013-12-01

130

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.

131

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

132

Submarine neutrino communication  

E-print Network

We discuss the possibility to use a high energy neutrino beam from a muon storage ring to provide one way communication with a submerged submarine. Neutrino interactions produce muons which can be detected either, directly when they pass through the submarine or by their emission of Cerenkov light in sea water, which, in turn, can be exploited with sensitive photo detectors. Due to the very high neutrino flux from a muon storage ring, it is sufficient to mount either detection system directly onto the hull of the submersible. The achievable data transfer rates compare favorable with existing technologies and do allow for a communication at the usual speed and depth of submarines.

Patrick Huber

2009-09-25

133

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.

134

Submarine: Lift Bag Lander  

NSDL National Science Digital Library

In this activity (on page 4), learners create a submarine using a plastic sandwich bag. This is a fun way to learn about buoyancy and how captured gas can cause objects to float. Note: You will also need access to a tank or swimming pool to watch your submarine dive. Safety note: Learners will need an adult's help to drill holes in the film canister.

Cameron, James; Hardy, Kevin

2013-01-01

135

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

136

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.

137

Physical and chemical properties of submarine basaltic rocks from the submarine flanks of the Hawaiian Islands  

USGS Publications Warehouse

To evaluate physical and chemical diversity in submarine basaltic rocks, approximately 280 deep submarine samples recovered by submersibles from the underwater flanks of the Hawaiian Islands were analyzed and compared. Based on observations from the submersibles and hand specimens, these samples were classified into three main occurrence types (lavas, coarse-grained volcaniclastic rocks, and fine-grained sediments), each with several subtypes. The whole-rock sulfur content and porosity in submarine basaltic rocks, recovered from depths greater than 2000 m, range from < 10 ppm and 2 vol.% to 2200 ppm and 47 vol.%, respectively. These wide variations cannot be due just to different ambient pressures at the collection depths, as inferred previously for submarine erupted lavas. The physical and chemical properties of the recovered samples, especially a combination of three whole-rock parameters (Fe-oxidation state, Sulfur content, and Porosity), are closely related to the occurrence type. The FSP triangular diagram is a valuable indicator of the source location of basaltic fragments deposited in deep submarine areas. This diagram can be applied to basaltic rocks such as clasts in debris-flow deposits, submarine-emplaced lava flows that may have crossed the shoreline, and slightly altered geological samples. ?? 2005 Elsevier B.V. All rights reserved.

Yokose, H.; Lipman, P. W.; Kanamatsu, T.

2005-01-01

138

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.

139

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

140

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

141

The emergence of a Galápagos shield volcano, Roca Redonda  

Microsoft Academic Search

Roca Redonda volcano is a mostly submarine shield volcano that rises nearly 3 km from the adjacent seafloor. Over twenty\\u000a lava flows and palagonite tuff are exposed in a 60 meter high oblong outcrop above sea level, and several other flows are\\u000a exposed in the shallow water surrounding the islet. Thick, slightly alkaline picritic flows form the base of the

Jeff Standish; Dennis Geist; Karen Harpp; Mark D. Kurz

1998-01-01

142

Submarine Coaxial Cable Pressure Characteristics  

Microsoft Academic Search

In equalization design of submarine coaxial cable system, the cable attenuation deviation due to pressure in deep sea bottom has significant weight. This paper treats the submarine coaxial cable characteristics pressure dependency. By using an artificial ocean test facility, 1.7 inch submarine coaxial cable attenuation, phase, capacitance and insulator core diameter were studied and their pressure coefficients under a pressure

K. Aida; M. Aiki

1978-01-01

143

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

144

Investigations of Anomalous Earthquakes at Active Volcanoes  

NASA Astrophysics Data System (ADS)

This dissertation investigates the link between volcanic unrest and the occurrence of moderate-to-large earthquakes with a specific type of focal mechanism. Vertical compensated-linear-vector-dipole (vertical-CLVD) earthquakes have vertical pressure or tension axes and seismic radiation patterns that are inconsistent with the double-couple model of slip on a planar fault. Prior to this work, moderate-to-large vertical-CLVD earthquakes were known to be geographically associated with volcanic centers, and vertical-CLVD earthquakes were linked to a tsunami in the Izu-Bonin volcanic arc and a subglacial fissure eruption in Iceland. Vertical-CLVD earthquakes are some of the largest and most anomalous earthquakes to occur in volcanic systems, yet their physical mechanisms remain controversial largely due to the small number of observations. Five vertical-CLVD earthquakes with vertical pressure axes are identified near Nyiragongo volcano in the Democratic Republic of the Congo. Three earthquakes occur within days of a fissure eruption at Nyiragongo, and two occur several years later in association with the refilling of the lava lake in the summit crater of the volcano. Detailed study of these events shows that the earthquakes have slower source processes than tectonic earthquakes with similar magnitudes and locations. All five earthquakes are interpreted as resulting from slip on inward-dipping ring-fault structures located above deflating shallow magma chambers. The Nyiragongo study supports the interpretation that vertical-CLVD earthquakes may be causally related to dynamic physical processes occurring inside the edifices or magmatic plumbing systems of active volcanoes. Two seismicity catalogs from the Global Centroid Moment Tensor (CMT) Project are used to search for further examples of shallow earthquakes with robust vertical-CLVD focal mechanisms. CMT solutions for approximately 400 target earthquakes are calculated and 86 vertical-CLVD earthquakes are identified near active volcanoes. Together with the Nyiragongo study, this work increases the number of well-studied vertical-CLVD earthquakes from 14 to 101. Vertical-CLVD earthquakes have focal depths in the upper ˜10 km of the Earth's crust, and ˜80% have centroid locations within 30 km of an active volcanic center. Vertical-CLVD earthquakes are observed near several different types of volcanoes in a variety of geographic and tectonic settings, but most vertical-CLVD earthquakes are observed near basaltic-to-andesitic stratovolcanoes and submarine volcanoes in subduction zones. Vertical-CLVD earthquakes are linked to tsunamis, volcanic earthquake swarms, effusive and explosive eruptions, and caldera collapse, and approximately 70% are associated with documented volcanic eruptions or episodes of volcanic unrest. Those events with vertical pressure axes typically occur after volcanic eruptions initiate, whereas events with vertical tension axes commonly occur before the start of volcanic unrest. Both types of vertical-CLVD earthquakes have longer source durations than tectonic earthquakes of the same magnitude. The isotropic and pure vertical-CLVD components of the moment tensor cannot be independently resolved using our long-period seismic dataset. As a result, several physical mechanisms can explain the retrieved deviatoric vertical-CLVD moment tensors, including dip-slip motion on ring faults, volume exchange between two reservoirs, the opening and closing of tensile cracks, and volumetric sources. An evaluation of these mechanisms is performed using constraints obtained from detailed studies of individual vertical-CLVD earthquakes. Although no single physical mechanism can explain all of the characteristics of vertical-CLVD earthquakes, a ring-faulting model consisting of slip on inward- or outward-dipping ring faults triggered by the inflation or deflation of a shallow magma chamber can account for their seismic radiation patterns and source durations, as well as their temporal relationships with volcanic unrest. The observation that most vertical-CLVD earthquakes a

Shuler, Ashley Elizabeth

145

Paint-Stirrer Submarine  

NSDL National Science Digital Library

In today's fast-paced, technological world, it is a constant struggle for teachers to find new and exciting ways to challenge and engage our students. The Paint-Stirrer Submarine is a unique and challenging laboratory exercise that keeps the students enthralled. They won't even realize they are learning because they will be having too much fun. This inquiry-based, hands-on experience in building a submarine allows the students to learn about buoyancy, buoyant force, Archimedes' principle, and motion in an engaging manner. It will be an experience neither you nor your students will ever forget.

Young, Jocelyn; Hardy, Kevin

2007-02-01

146

Researchers Find Japanese Submarine at Pearl Harbor  

NSDL National Science Digital Library

Earlier this week, researchers from the University of Hawaii and the Hawaii Underwater Research Lab located the remains of a Japanese midget submarine. Found in 1200 feet of water, the submarine was sunk by the USS Ward just an hour before the aerial attack on Pearl Harbor on December 7, 1941. Most important, the discovery of the midget submarine offers concrete physical evidence that the United States did fire the first shot against the Japanese. Previous expeditions to locate the sub, including an effort made in 2000 by the National Geographic Society, had been unsuccessful, largely due to the fact that the area is a military "junkyard" with tons of debris on the ocean floor.For more in-depth information on this story, readers may find the first four news links particularly helpful. The fifth link leads to the Hawaii Underwater Research Lab's Web site that features photographs of the midget sub from the expedition earlier this week. The sixth link is to a Web site dealing with the history and missions of the USS Ward. The final link contains detailed information about the 2000 expedition led by Robert Ballard, with support from the National Geographic Society, to find the midget submarine.

Green, Marcia.

2002-01-01

147

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.

148

Isotopic and trace element geochemistry of lavas from the northern Mariana and southern volcano arcs  

Microsoft Academic Search

Samples from submarine volcanoes and islands were analyzed for concentrations of K, Rb, Sr, Ba, REE, ⁸⁷Sr\\/⁸⁶Sr and some selected samples for ¹⁴³Nd\\/¹⁴⁴Nd. These data show strong variations along the arc, being relatively depleted in the tholeiitic and low-K calc-alkaline volcanoes of the Volcano Arc (VA) and the Mariana Central Island Province (CIP). All of the Mariana Northern Seamount Province

Lin Pingnan

1989-01-01

149

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

150

Extensive and Diverse Submarine Volcanism and Hydrothermal Activity in the NE Lau Basin  

NASA Astrophysics Data System (ADS)

The northeast Lau basin, the NE “corner” of the Tonga subduction zone, has an unusual concentration of young submarine volcanism and hydrothermal activity. The area is bounded on the west by overlapping spreading centers opening at rates up to 120 mm/yr, on the north by the E-W trending Tonga trench and on the east by the Tofua arc front. From the south, the Fonualei rift spreading center (FRSC) overlaps with the southern rift of The Mangatolo triple junction spreading center (MTJSC). The northern arm of the MTJSC overlaps with the northeast Lau spreading center (NELSC). Surveys of the area with an EM300 sonar system in November 2008 show high backscatter over the 10-20 km wide neovolcanic zones of the FRSC, MTJSC and NELSC. High backscatter is also associated with: (1) a 10-km diameter, hydrothermally active, volcanic caldera/cone (Volcano “O”) lying between the NELSC and the northern Tofua arc front; (2) a rift zone extending north from volcano “O” and intersecting the NELSC near the Tonga trench; and (3) a series of volcanoes constructed along SW-NE trending crustal tears in the northernmost backarc near the east-west portion of the Tonga Trench. Two eruptions were detected in November 2008 during hydrothermal plume surveys of the area. Subsequent dives with the remotely operated vehicle Jason 2 in May 2009 revealed that the southern NELSC eruption was a short-lived, primarily effusive eruption. The second eruption was detected on the summit of the largest SW-NE trending volcano (West Mata) and was ongoing when Jason 2 arrived on site more than 6 months later. It was producing both pillow lavas and abundant volcaniclastic debris streams that have a characteristic appearance on the sonar backscatter map. There is also an unusual series of lava flows emanating from ridges and scarps between Volcano “O” and West Mata. These flows contain drained-out lava ponds up to 2 km in diameter. The apparent high level of volcanic activity in the NE Lau basin is likely attributable to its unusual tectonic setting at the northern edge of Earth’s most dynamic subduction zone. Earthquake tomography shows that the northern edge corresponds to an E-W tear fault in the subducting Pacific plate along latitude 15 degrees S. West Mata and its hydrothermally active “twin”, East Mata volcano, are located directly above the tear fault. Seismological evidence further indicates that the tear fault is currently “active,” providing a strong explanation for the unusually high level of volcanic activity in this area.

Embley, R. W.; Merle, S. G.; Lupton, J. E.; Resing, J.; Baker, E. T.; Lilley, M. D.; Arculus, R. J.; Crowhurst, P. V.

2009-12-01

151

Multi-Fluid Hydrodynamic Calculations Of Turbidite Deposits From Submarine-Landslide Tsunamis  

Microsoft Academic Search

Calculations with the LANL multiphysics hydrocode SAGE of tsunamis produced by submarine landslides illustrate the relation between fluid rheology and the resultant morphology of the turbidite deposits seen afterwards on the seafloor. Tsunamigenic underwater landslides can have a variety of triggers: a seismic event that pushes a stable slope of granular material past its angle of repose, an underwater volcano

G. R. Gisler; R. P. Weaver; M. L. Gittings

2006-01-01

152

The 1989 submarine eruption off eastern Izu Peninsula, Japan: ejecta and eruption mechanisms  

Microsoft Academic Search

The submarine eruption of a new small knoll, which was named “Teishi knoll”, off eastern Izu Peninsula behind the Izu-Mariana arc occurred in the evening of 13 July 1989. This is the first historic eruption of the Higashi-Izu monogenetic volcano group. The eruption of 13 July followed an earthquake swarm near Ito city starting on 30 June. There were subsequent

Takahiro Yamamoto; Tatsunori Soya; Shigeru Suto; Kozo Uto; Akira Takada; Keiichi Sakaguchi; Koji Ono

1991-01-01

153

Worldwide Submarine Challenges.  

National Technical Information Service (NTIS)

The Worldwide Submarine Challenges that the United States and its allies face today are more diverse and more complex than at any time during the Cold War. These Challenges now encompass both the open ocean and the littoral. They run the gamut from the hi...

1997-01-01

154

Fiber Optic Submarine Cables  

NASA Astrophysics Data System (ADS)

Submarine communication cables have one of the longest history in the field of technics. During the last 20 years their importance showed a drastic decay in favour of satellites. Presently their future looks bright again as they contain now optical fibers instead of coaxial pairs.

Oestreich, Ulrich H. P.

1990-01-01

155

The Stability of Submarines  

Microsoft Academic Search

SIR WILLIAM WHITE, in his paper in the Roy. Soc. Proceedings (vol. lxxvii. A., p. 528), discusses the hydrostatic forces tending to stability or instability of a submarine at the surface of the water. When the vessel is in motion, hydrodynamical forces come into play from the stream-line action of the water, and these also will affect the stability of

J. H. Jeans

1906-01-01

156

Submarine Dynamic Modeling  

Microsoft Academic Search

This paper discusses the development of a dynamic model for a torpedo shaped sub- marine. Expressions for hydrostatic, added mass, hydrodynamic, control surface and pro- peller forces and moments are derived from first principles. Experimental data obtained from flume tests of the submarine are inserted into the model in order to provide computer simulations of the open loop behavior of

Peter Ridley; Julien Fontan; Peter Corke

157

International Submarine Races  

NSDL National Science Digital Library

Engineering design competition in which teams design & build one or two-man submarines. Participants compete for best overall performance, innovation, speed, best use of composite materials, and spirit of the race. Participants include universities, corporations, government agencies, individuals and research labs.

158

Acoustic stratigraphy and hydrothermal activity within Epi Submarine Caldera, Vanuatu, New Hebrides Arc  

USGS Publications Warehouse

Geological and geophysical surveys of active submarine volcanoes offshore and southeast of Epi Island, Vanuatu, New Hebrides Arc, have delineated details of the structure and acoustic stratigraphy of three volcanic cones. These submarine cones, named Epia, Epib, and Epic, are aligned east-west and spaced 3.5 km apart on the rim of a submerged caldera. At least three acoustic sequences, of presumed Quaternary age, can be identified on single-channel seismic-reflection profiles. Rocks dredged from these cones include basalt, dacite, and cognate gabbroic inclusions with magmatic affinities similar to those of the Karua (an active submarine volcano off the southeastern tip of Epi) lavas. ?? 1988 Springer-Verlag New York Inc.

Greene, H. Gary; Exon, N.F.

1988-01-01

159

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.

160

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 ...

161

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

162

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

163

Using Ambient Noise Fields for Submarine Team #525 for the Mathematical Contest in Modeling  

E-print Network

that the measurements of sound are to be made by an array of transducers (piezo­electric crystal microphones) suspen waves transducer array Page 3 of 30 #12; #525 Submarine Location ¯ Section 2.2 1. Thermal noise causedUsing Ambient Noise Fields for Submarine Location Team #525 for the Mathematical Contest

Mitchener, W. Garrett

164

SCOOP--An Improved Submarine Cable Recovery System  

Microsoft Academic Search

For more than twenty years, acoustically controlled, buoyant subsurface arrays have been utilized by research institutions and industry for mooring, location, and retrieval of oceanographic instruments. Submarine telecommunications cable laying and repair operations typically involve location and retrieval of free cable ends left on the seafloor. In deep water areas, conventional methods for cable-end location and recovery included the use

G. Rich; J. Ewald; C. Jeffcoat; R. Weller

1984-01-01

165

Stratigraphy of the Hawai`i Scientific Drilling Project core (HSDP2): Anatomy of a Hawaiian shield volcano  

NASA Astrophysics Data System (ADS)

The Hawai`i Scientific Drilling Project (HSDP2) successfully drilled ˜3.1 km into the island of Hawai`i. Drilling started on Mauna Loa volcano, drilling 247 m of subaerial lavas before encountering 832 m of subaerial Mauna Kea lavas, followed by 2019 m of submarine Mauna Kea volcanic and sedimentary units. The 2.85 km stratigraphic record of Mauna Kea volcano spans back to ˜650 ka. Mauna Kea subaerial lavas have high average olivine contents (13 vol.%) and low average vesicle abundances (10 vol.%). Most subaerial Mauna Kea flows are `a`? (˜63%), whereas the Mauna Loa section contains nearly equal amounts of p?hoehoe and `a`? (like its current surface). The submarine Mauna Kea section contains an upper, ˜900 m thick, hyaloclastite-rich section and a lower, ˜1100 m thick, pillow-lava-dominated section. These results support a model that Hawaiian volcanoes are built on a pedestal of pillow lavas capped by rapidly quenched, fragmented lava debris. The HSDP2 section is compared here to a 1.7 km deep hole (SOH1) on Kilauea's lower east rift zone. Differences in the sections reflect the proximity to source vents and the lower magma supply to Kilauea's rift zone. Both drill core sections are cut by intrusions, but the higher abundance of intrusions in SOH1 reflects its location within a rift zone, causing more extensive alteration in the SOH1 core. The HSDP2 site recovered a relatively unaltered core well suited for geochemical analyses of the single deepest and most complete borehole ever drilled through a Hawaiian or any other oceanic island volcano.

Garcia, Michael O.; Haskins, Eric H.; Stolper, Edward M.; Baker, Michael

2007-02-01

166

Earth Currents in Short Submarine Cables  

Microsoft Academic Search

PRIOR to 1940, faults on submarine telephone cables between Great Britain and the Continent were normally located by direct-current methods employing a good wire in another cable. Confirmatory tests were usually made by the impedance-frequency method1. When the time came in 1944 to restore telephone communications, no good wires were available. The impedance-frequency method was employed for fault localization with

D. W. Cherry; A. T. Stovold

1946-01-01

167

Unmanned submarine vehicle  

SciTech Connect

An unmanned self-propelled submarine vehicle is provided with a material exchanger-container having a vertical axis of symmetry aligned with both the vehicle's center of gravity and its center of volume. The exchanger-container has a moveable diaphragm which divides the interior into two compartments, a lower ballast compartment equipped with an unloading apparatus and an upper compartment adapted to receive collected material. Ballast is unloaded during material loading to maintain the weight of the vehicle constant during loading.

Hervieu

1984-05-15

168

Degassing of metals and metalloids from erupting seamount and mid-ocean ridge volcanoes: Observations and predictions  

Microsoft Academic Search

Recently, it has been reported that the element polonium degasses from mid-ocean ridge and seamount volcanoes during eruptions. Published and new observations on other volatile metal and metalloid elements can also be interpreted as indicating significant degassing of magmatic vapors during submarine eruptions. This process potentially plays an important role in the net transfer of chemical elements from erupting volcanoes

Ken Rubin

1997-01-01

169

Up-Close Fluid Sampling at a Deep Submarine Lava Eruption  

NASA Astrophysics Data System (ADS)

On three separate expeditions from April 2004 to April 2006 to the Mariana volcanic arc, we found eruptive activity at NW Rota 1 submarine volcano. ROVs ROPOS, Hyper Dolphin, and Jason-2 were used to survey and collect samples. The summit of the volcano is at 520 meters depth and there are numerous sites of hydrothermal activity around the east-west trending summit ridge and down the south flank. The chemical composition of vent fluids on NW Rota and the microbiological communities entrained by the fluids varies significantly according to location. There is an eruptive pit crater on the south flank about 30 meters below the summit where seawater interacts directly with erupting lava, volcanic gases and molten sulfur. On every visit, the pit has exhibited extreme variability in output, ranging from a very quiet stream of particulate sulfur smoke to violent bursts of smoke, gas bubbles, molten sulfur, highly vesicular volcaniclastic lapilli and small lava bombs. We were able to sample many hydrothermal vents around the volcano and many phases of the output at the eruptive pit. In 2004, we sampled by lowering ROPOS directly into the pit during a quiet period, and subsequently used a long sampling tube to access the pit. In 2006, the wall of the pit was absent and the volcanic vent was directly visible. During this period we were able to sample directly over the surface of slowly erupting lava. The fluid and particle samples obtained were unlike anything ever sampled in the deep sea and appear to be the result of rapid reaction of seawater with volcanic products.

Butterfield, D. A.; Embley, R. W.; Chadwick, W. W.; Lupton, J. E.; Nakamura, K.; Takano, B.; de Ronde, C.; Resing, J.; Bolton, S.; Baross, J.

2006-12-01

170

Active hydrothermal discharge on the submarine Aeolian Arc  

NASA Astrophysics Data System (ADS)

In November 2007 we conducted a water column and seafloor mapping study of the submarine volcanoes of the Aeolian Arc in the southern Tyrrhenian Sea aboard the R/V Urania. On 26 conductivity-temperature-depth casts and tows we measured temperature, conductivity, pressure, and light scattering and also collected discrete samples for helium isotopes, methane, and pH. The 3He/4He isotope ratio, an unambiguous indicator of hydrothermal input, showed a clear excess above background at 6 of the 10 submarine volcanoes surveyed. Marsili seamount had the highest anomaly, where the 3He/4He ratio reached a ?3He value of 23% at 610 m depth compared with background values of ˜5%. Smaller but distinct ?3He anomalies occurred over Palinuro, Enarete, Eolo, Sisifo, and Secca del Capo. Although hydrothermal emissions are known to occur offshore of some Aeolian subaerial volcanoes, and hydrothermal deposits have been sampled throughout the arc, our results are the first to confirm active discharge on Marsili, Enarete, Eolo, Sisifo, and Secca del Capo. Samples collected over Lametini, Filicudi North, Alicudi North, and Alcione had ?3He near the regional background values, suggesting either absence of, or very weak, hydrothermal activity on these seamounts. Hydrocasts between the volcanoes revealed a consistent ?3He maximum between 11% and 13% at 2000 m depth throughout the SE Tyrrhenian Sea. The volcanoes of the Aeolian arc and the Marsili back arc, all <1000 m deep, cannot contribute directly to this maximum. This deep 3He excess may be a remnant of tritium decay or may have been produced by an unknown deep hydrothermal source.

Lupton, John; de Ronde, Cornel; Sprovieri, Mario; Baker, Edward T.; Bruno, Pier Paolo; Italiano, Franco; Walker, Sharon; Faure, Kevin; Leybourne, Matthew; Britten, Karen; Greene, Ronald

2011-02-01

171

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

172

DEFUELING OF RETIRED NUCLEAR SUBMARINES  

Microsoft Academic Search

The Russian Federation (RF) Decree #518 of May 28, 1998 “On Measures on Supporting Complex Decommissioning of Nuclear Submarines, Withdrawn from Service in the Russian Navy, and Ships of RF Ministry of Transport” entrusted RF Ministry for Atomic Energy (Minatom, presently Rosatom) with the task of drastic increase in the paces of Nuclear Submarine (NS) complex decommissioning, the heaviest burden

A. V. TIMOFEEV; V. I. KOSTIN; N. G. SANDLER; V. N. VAVILKIN; V. V. MOSCALENKO; A. I. KALINKIN

173

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

174

Subaerial, submarine and extraterrestrial volcanic morphologies: Comparisons and contrasts  

NASA Astrophysics Data System (ADS)

Interpretation of volcanic deposits on Mars is frustrated by lack of ground truth. Although orbiting instruments are collecting compositional data (as spectra), and rovers are providing detailed analyses of a few select areas on the surface, volcanic morphologies remain the primary means for our understanding of Martian volcanic behavior. Geologic mapping, combined with critical study of terrestrial analogs, provides a sound means for constraining the precise origin of volcanic deposits on Mars, Earth's sea floor, and the surfaces of the other terrestrial planets. Layered deposits within Hesperia Planum, Mars, and composing Tyrrhenus Mons (a low-relief central-vent volcano located within Hesperia Planum) have variously been interpreted to be: flood lavas, pyroclastic deposits (probably pyroclastic flows), or sedimentary deposits. Compositional data are not helpful here: the area is covered with sufficient dust to prevent orbiting instruments from measuring the bedrock composition. An additional complication is that these deposits were emplaced in the Noachian to Early Hesperian and have been subsequently modified by fluvial, mass wasting, and groundwater sapping processes. Comparing Martian deposits with terrestrial subaerial and submarine analogs provides necessary insight for interpreting the Martian deposits as effusive, explosive, or sedimentary. The planform margins of eroded subaerial ignimbrite deposits on Earth, for example, are locally dominated by aeolian exploitation of contraction cooling joints and have a crenulated margin. In contrast, the planform shape of seamounts reflects competing forces of accumulation of lava with simultaneous mass-wasting of oversteepened slopes, resulting in an almost stellate outline. Sedimentary deposits are unlikely to display thermal jointing, but may have jointing caused by local tectonics. Thus, determining the nature of these (and other) layered deposits requires the compilation of a 'preponderance of evidence,' including geologic setting, deposit morphology, and erosional history.

Gregg, T. K.

2013-12-01

175

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.

176

Learning to Characterize Submarine Lava Flow Morphology at Seamounts and Spreading Centers using High Definition Video and Photomosaics  

Microsoft Academic Search

In August, 2010 the UW ENLIGHTEN '10 expedition provided ~140 hours of seafloor HD video footage at Axial Seamount, the most magmatically robust submarine volcano on the Juan de Fuca Ridge. During this expedition, direct imagery from an Insite Pacific HD camera mounted on the ROV Jason 2 was used to classify broad expanses of seafloor where high power (8

A. T. Fundis; L. R. Sautter; D. S. Kelley; J. R. Delaney; M. Kerr-Riess; A. R. Denny; M. Elend

2010-01-01

177

Soil Volatile Hg, As, B and NH3 Distribution Prior the 2001 Eruption at Usu Volcano, Japan  

Microsoft Academic Search

Usu volcano is one of the most active volcanoes in Japan, and eight major eruptions have been recorded at this volcano since 1963. It is located in the southwestern part of Hokkaido. The volcano is a post-caldera cone of Toya caldera, and composed of a somma volcano with a parasitic scoria cone and a number of lava domes and cryptodomes.

R. Quintana; P. Salazar; A. Mena; P. A. Hernandez; J. M. Salazar; N. M. Perez; T. Mori; K. Notsu; H. Okada

2002-01-01

178

Near-bottom water column anomalies associated with active hydrothermal venting at Aeolian arc volcanoes, Tyrrhenian Sea, Italy  

NASA Astrophysics Data System (ADS)

Hydrothermal deposits such as metalliferous sediments, Fe-Mn crusts, and massive sulfides are common on the submarine volcanoes of the Aeolian arc (Tyrrhenian Sea, Italy), but the extent and style of active hydrothermal venting is less well known. A systematic water column survey in 2007 found helium isotope ratios indicative of active venting at 6 of the 9 submarine volcanoes surveyed plus the Marsili back-arc spreading center (Lupton et al., 2011). Other plume indicators, such as turbidity and temperature anomalies were weak or not detected. In September 2011, we conducted five ROV Hercules dives at Eolo, Enarete, and Palinuro volcanoes during an E/V Nautilus expedition. Additionally, two dives explored the Casoni seamount on the southern flank of Stromboli where a dredge returned apparently warm lava in 2002 (Gamberi, 2006). Four PMEL MAPRs, with temperature, optical backscatter (particles), and oxidation-reduction potential (ORP) sensors, were arrayed along the lowermost 50 m of the Hercules/Argus cable during the dives to assess the relationship between seafloor observations and water column anomalies. Active venting was observed at each of the volcanoes visited. Particle anomalies were weak or absent, consistent with the 2007 CTD surveys, but ORP anomalies were common. Venting at Eolo volcano was characterized by small, localized patches of yellow-orange bacteria; living tubeworms were observed at one location. ORP anomalies (-1 to -22 mv) were measured at several locations, primarily along the walls of the crescent-shaped collapse area (or possible caldera) east of the Eolo summit. At Enarete volcano, we found venting fluids with temperatures up to 5°C above ambient as well as small, fragile iron-oxide chimneys. The most intense ORP anomaly (-140 mv) occurred at a depth of about 495 m on the southeast side of the volcano, with smaller anomalies (-10 to -20 mv) more common as the ROV moved upslope to the summit. At Palinuro volcano, multiple dives located several active sites along the 50-km-long summit. The distribution of ORP anomalies seen during these dives correlates quite well with the locations of anomalous helium samples from 2007. An ORP anomaly of -160 mv was located at the west end of Palinuro where vent fluids up to 54°C were found. Living tubeworms, bacterial mats of various colors and textures, and small chimneys and globular spires coated with iron oxide having bright-green interiors indicative of the iron-rich hydrothermal clay nontronite were found at actively venting areas on Palinuro. ORP anomalies were generally only detected in the near-bottom MAPR mounted on Hercules. In a few locations the MAPRs on Argus (10-30 meters above bottom) and 25 meters above Argus registered anomalies not seen by the MAPR on Hercules indicating active venting nearby, but not observed along the trackline of the ROV. Only the higher-temperature vent site at the west end of Palinuro generated a plume that had an appreciable particle anomaly and rise height (seen by the Argus+25m MAPR). No anomalies were measured by the MAPR located 50 meters above Argus.

Walker, S. L.; Carey, S.; Bell, K. L.; Baker, E. T.; Faure, K.; Rosi, M.; Marani, M.; Nomikou, P.

2012-12-01

179

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

180

Variations of the state of stress and dike propagation at Fernandina volcano, Galápagos.  

NASA Astrophysics Data System (ADS)

Fernandina volcano forms the youngest and westernmost island of the Galapagos Archipelago, a group of volcanic islands located near the equator and 1000 km west of Ecuador. Twenty-five eruptions in the last two hundred years make Fernandina the most active volcano in the archipelago and one of the most active volcanoes in the world. Most eruptions occur along fissures fed by dikes that propagate from the central magmatic system and from reservoirs centered under the summit caldera. Eruptive fissures in the subaerial portion of the volcano form two distinct sets: (1) arcuate or circumferential fissures characterize the upper portion of the volcano around the caldera while (2) radial fissures are present on the lower flanks. The subaerial portion of the volcano lacks of well-developed rift zones, while the submarine part of Fernandina shows three rifting zones that extend from the western side of the island. Using Interferometric Synthetic Aperture Radar (InSAR) measurements of the surface displacement at Fernandina acquired from 1992 to 2010, and in particular the ones spanning the last three eruptions (1995 - radial, 2005 - circumferential and 2009 - radial) we infer the geometry of the shallow magmatic system and of the dikes that fed these eruptions. A shallow dipping radial dike on the southwestern flank has been inferred by Jónnson et al. (1999) for the 1995 eruption. This event shows a pattern of deformation strikingly similar to the one associated with the April 2009 eruption for which we infer a similar geometry. Co-eruptive deformation for the 2005 event has been modeled by Chadwick et al. (2010) using three planar dikes, connected along hinge lines, in the attempt to simulate a curve-concave shell, steeply dipping toward the caldera at the surface and more gently dipping at depth. Dike propagation in a volcano is not a random process but it is controlled by the orientation of the principal stresses, with the dike orthogonal to the least compressive stress. We calculate stress changes within the volcanic edifice generated by the active geophysical processes (e.g., pressure changes in reservoir, dike emplacement, …) and we investigate what phenomena can produce a stress field compatible with the inferred dike geometries and the observed pattern of eruptive fissures. Stress models are generated in a three-dimensional linear elastic medium, using a 3D boundary element code based on the analytical solutions for triangular dislocations in isotropic elastic half and full space.

Bagnardi, M.; Amelung, F.

2012-04-01

181

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 ...

182

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

183

Submarine fresh water outflow detection with a dual-frequency microwave and an infrared radiometer system  

NASA Technical Reports Server (NTRS)

Since infrared measurements are only very slightly affected by whitecap and banking angle influences, the combined multifrequency radiometric signatures of the L-band, the S-band, and an infrared radiometer are used in identifying freshwater outflows (submerged and superficial). To separate the river and lagoon outflows from the submarine outflows, geographical maps with a scale of 1:100,000 are used. In all, 44 submarine freshwater springs are identified. This is seen as indicating that the submarine freshwater outflow locations are more numerous around the island than had earlier been estimated. Most of the submarine springs are located at the northwest and southeast portion of the Puerto Rican coastline; the success in detecting the submarine springs during both missions at the northwest portion of the island is 39%. Salinity and temperature distribution plots along the flight path in longitude and latitude coordinates reveal that runoff direction can be determined.

Blume, H.-J. C.; Kendall, B. M.; Fedors, J. C.

1981-01-01

184

Carbohydrate Metabolism in Submariner Personnel.  

National Technical Information Service (NTIS)

Submariners have been shown to have an increased rate of glucose utilization 2 hours after an oral loading test. Relative hypoglycemia due to excess insulin production has been considered a first indication of developing diabetes. However, diabetes can no...

E. Heyder, L. W. Mooney, D. V. Tappan

1983-01-01

185

Volcanic Explosions, Seismicity, and Debris from the West and North Mata Volcano Complex, NE Lau Basin  

Microsoft Academic Search

The discovery of the explosively erupting deep-ocean West Mata volcano in the northeast Lau Basin offers an unprecedented opportunity for in situ and near-field studies of the hydroacoustic wavefield produced by a submarine arc volcano, as well as the relationship between gas-driven explosions and the formation of volcanic-hydrothermal plumes. From December 2009 to April 2010, we re-initiated acoustic monitoring of

R. P. Dziak; D. R. Bohnenstiehl; E. T. Baker; H. Matsumoto; J. Haxel; S. Walker; M. Fowler

2010-01-01

186

Character of seismic motion at a location of a gas hydrate-bearing mud volcano on the SW Barents Sea margin  

NASA Astrophysics Data System (ADS)

Håkon Mosby mud volcano (HMMV) at 1270 m water depth on the SW Barents Sea slope has been intensively studied since its discovery in 1989. A variety of sensors monitored morphological, hydrological, geochemical, and biological parameters in the HMMV area. An ocean bottom seismometer deployment allowed us to register seismic motion for 2 years, from October 2008 to October 2010. The analysis of seismic records documents two types of seismic signals. The first type are harmonic tremors with frequency peaks around 4-5 and 8-10 Hz that occur in swarms. Their origin could be from fluid flow circulation or resonant vibrations of gas bubbles or from delayed movement of fluid-rich sediments in the conduit or in a deeper pseudo-mud chamber of the HMMV. Because swarms occur with a periodicity of ~ 6 h, tide-related effects are suspected to influence the mechanism originating the tremors. The second type of signals are regional earthquakes that were in 15 cases recognized in seismic records. The activity of harmonic tremors was not significantly affected by earthquakes.

Franek, Peter; Mienert, Jürgen; Buenz, Stefan; Géli, Louis

2014-08-01

187

Glacier monitoring at Popocatépetl volcano, Mexico: glacier shrinkage and possible causes  

Microsoft Academic Search

Glacier monitoring at Popocatépetl volcano, Mexico: glacier shrinkage and possible causes Glaciers in combination with volcanoes may represent an important hazard for human settlements. As Popocatépetl volcano is located in the vicinity of highly populated areas monitoring its glaciers is a vital part of the surveillance system of the volcano. Popocatépetl hosts two small glaciers that are monitored mainly by

Christian Huggel; Hugo Delgado

188

A Volcano Population Index for Estimating Relative Risk With Example Data From Central America  

Microsoft Academic Search

We have developed a Volcano Population Index (VPI) to make objective comparisons among individual volcanoes of populations that may be subject to volcanic hazards. We used volcano location data from the Smithsonian's Global Volcanism Program (GVP) with the LandScan 2001 gridded global population data base from the Oak Ridge National Laboratory to evaluate population distribution near potentially active volcanoes in

J. W. Ewert; C. J. Harpel

2003-01-01

189

New discoveries of mud volcanoes on the Moroccan Atlantic continental margin (Gulf of Cádiz): morpho-structural characterization  

NASA Astrophysics Data System (ADS)

During the MVSEIS-08 cruise of 2008, ten new mud volcanoes (MVs) were discovered on the offshore Moroccan continental margin (Gulf of Cádiz) at water depths between 750 and 1,600 m, using multibeam bathymetry, backscatter imagery, high-resolution seismic and gravity core data. Mud breccias were recovered in all cases, attesting to the nature of extrusion of these cones. The mud volcanoes are located in two fields: the MVSEIS, Moundforce, Pixie, Las Negras, Madrid, Guadix, Almanzor and El Cid MVs in the western Moroccan field, where mud volcanoes have long been suspected but to date not identified, and the Boabdil and Al Gacel MVs in the middle Moroccan field. Three main morphologies were observed: asymmetric, sub-circular and flat-topped cone-shaped types, this being the first report of asymmetric morphologies in the Gulf of Cádiz. Based on morpho-structural analysis, the features are interpreted to result from (1) repeated constructive (expulsion of fluid mud mixtures) and destructive (gravity-induced collapse and submarine landsliding) episodes and (2) interaction with bottom currents.

León, Ricardo; Somoza, Luis; Medialdea, Teresa; Vázquez, Juan Tomás; González, Francisco Javier; López-González, Nieves; Casas, David; del Pilar Mata, María; del Fernández-Puga, María Carmen; Giménez-Moreno, Carmen Julia; Díaz-del-Río, Víctor

2012-12-01

190

Hawaiian submarine manganese-iron oxide crusts - A dating tool?  

USGS Publications Warehouse

Black manganese-iron oxide crusts form on most exposed rock on the ocean floor. Such crusts are well developed on the steep lava slopes of the Hawaiian Ridge and have been sampled during dredging and submersible dives. The crusts also occur on fragments detached from bedrock by mass wasting, on submerged coral reefs, and on poorly lithified sedimentary rocks. The thickness of the crusts was measured on samples collected since 1965 on the Hawaiian Ridge from 140 dive or dredge localities. Fifty-nine (42%) of the sites were collected in 2001 by remotely operated vehicles (ROVs). The thinner crusts on many samples apparently result from post-depositional breakage, landsliding, and intermittent burial of outcrops by sediment. The maximum crust thickness was selected from each dredge or dive site to best represent crusts on the original rock surface at that site. The measurements show an irregular progressive thickening of the crusts toward the northwest-i.e., progressive thickening toward the older volcanic features with increasing distance from the Hawaiian hotspot. Comparison of the maximum crust thickness with radiometric ages of related subaerial features supports previous studies that indicate a crust-growth rate of about 2.5 mm/m.y. The thickness information not only allows a comparison of the relative exposure ages of two or more features offshore from different volcanoes, but also provides specific age estimates of volcanic and landslide deposits. The data indicate that some of the landslide blocks within the south Kona landslide are the oldest exposed rock on Mauna Loa, Kilauea, or Loihi volcanoes. Crusts on the floors of submarine canyons off Kohala and East Molokai volcanoes indicate that these canyons are no longer serving as channelways for downslope, sediment-laden currents. Mahukona volcano was approximately synchronous with Hilo Ridge, both being younger than Hana Ridge. The Nuuanu landslide is considerably older than the Wailau landslide. The Waianae landslide southwest of Oahu has yielded samples with the greatest manganese-iron oxide crusts (9.5 mm thick) and therefore apparently represents the oldest submarine material yet found in the study area. The submarine volcanic field 100 km southwest of Oahu is apparently younger than the Waianae landslide. ?? 2004 Geological Society of America.

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

2004-01-01

191

Multifrequency radiometer detection of submarine freshwater sources along the Puerto Rican coastline  

NASA Technical Reports Server (NTRS)

The surface area above submarine springs of fresh water exhibit temperatures and salinities lower than the surrounding sea waters. A multifrequency radiometer system which earlier demonstrated an accuracy of 1 degree C and 1 part per thousand in remotely detecting the surface temperature and salinities, respectively, was used to detect submarine freshwater springs. The first mission on February 4, 1978, consisted of overflight measurements over three fourths of the coastal areas around the Island of Puerto Rico. During the second mission on February 6, 1978, special attention was directed to the northwest portion of Puerto Rico where several submarine springs had been reported. The previously reported spring locations correlated well with the locations detected by the radiometers. After separating the surface runoffs such as rivers, lagoons, marshes, and bays, 44 submarine freshwater springs were identified which indicates that the submarine freshwater outflow locations are more numerous around the island than had earlier been estimated. The majority of the submarine springs are located at the northwest and southeast portion of the Puerto Rican coastline. The success of detecting the same submarine springs during both missions at the northwest portion of the island was 39%.

Blume, H.-J. C.; Kendall, B. M.; Fedors, J. C.

1981-01-01

192

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

193

Rapid Mass Wasting Following Nearshore Underwater Volcanism on Kilauea Volcano  

Microsoft Academic Search

The rapid mass wasting of shallow submarine basalts was documented during SCUBA dives (with extensive underwater video and photography) along the flanks of Kilauea volcano, Hawaii during the Ki'i lava entry of the current eruption (19° 20.4'N, 155° 00.0'W). Lava entered the ocean at this site from mid-February to late March 1990, with several pauses. Dives on 19-20 March 1990

F. J. Sansone; J. R. Smith; J. B. Culp

2003-01-01

194

Underwater observations of active lava flows from Kilauea volcano, Hawaii  

Microsoft Academic Search

Underwater observation of active submarine lava flows from Kilauea volcano, Hawaii, in March-June 1989 revealed both pillow lava and highly channelized lava streams flowing down a steep and unconsolidated lava delta. The channelized streams were 0.7-1.5 m across and moved at rates of 1-3 m\\/s. The estimated flux of a stream was 0.7 m3\\/s. Jets of hydrothermal water and gas

Gordon W. Tribble

1991-01-01

195

Surface and bottom boundary layer dynamics on a shallow submarine bank : southern flank of Georges Bank  

E-print Network

The thesis investigates the circulation at a 76-m deep study site on the southern flank of Georges Bank, a shallow submarine bank located between the deeper Gulf of Maine and the continental slope. Emphasis is placed on ...

Werner, Sandra R. (Sandra Regina)

1999-01-01

196

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.

197

Transport of Fine Ash Through the Water Column at Erupting Volcanoes - Monowai Cone, Kermadec-Tonga Arc  

NASA Astrophysics Data System (ADS)

Monowai cone is a large, active, basaltic stratovolcano, part of the submarine Monowai volcanic center (MVC) located at ~26°S on the Kermadec-Tonga arc. At other actively erupting submarine volcanoes, magma extrusions and hydrothermal vents have been located only near the summit of the edifice, generating plumes enriched with hydrothermal components and magmatic gasses that disperse into the ocean environment at, or shallower than, the summit depth. Plumes found deeper than summit depths are dominated by fresh volcaniclastic ash particles, devoid of hydrothermal tracers, emplaced episodically by down-slope gravity flows, and transport fine ash to 10’s of km from the active eruptions. A water column survey of the MVC in 2004 mapped intensely hydrothermal-magmatic plumes over the shallow (~130 m) summit of Monowai cone and widespread plumes around its flanks. Due to the more complex multiple parasitic cone and caldera structure of MVC, we analyzed the dissolved and particulate components of the flank plumes for evidence of additional sources. Although hydrothermal plumes exist within the adjacent caldera, none of the parasitic cones on Monowai cone or elsewhere within the MVC were hydrothermally or volcanically active. The combination of an intensely enriched summit plume, sulfur particles and bubbles at the sea surface, and ash-dominated flank plumes indicate Monowai cone was actively erupting at the time of the 2004 survey. Monowai cone is thus the fourth erupting submarine volcano we have encountered, and all have had deep ash plumes distributed around their flanks [the others are: Kavachi (Solomon Island arc), NW Rota-1 (Mariana arc) and W Mata (NE Lau basin)]. These deep ash plumes are a syneruptive phenomenon, but it is unknown how they are related to eruptive style and output, or to the cycles of construction and collapse that occur on the slopes of submarine volcanoes. Repeat multibeam bathymetric surveys have documented two large-scale sector collapse events at Monowai and one at NW Rota-1, as well as constructional deposits extending down the flanks of these volcanoes. Acoustic records at Monowai and NW Rota-1 suggest sector collapse events are infrequent while eruptions, and the resulting supply of depositional material, have been nearly continuous. The sector collapse events occurred at times remote from our plume surveys, so, large landslide events are not a prerequisite for the presence of deep ash plumes. Despite a wide range of summit depths (<10 m at Kavachi to 1500 m at W Mata), lava types (basaltic-andesite, boninite, and basalt), and eruptive styles (Surtseyan, Strombolian, and effusive flows with active pillow formation), the deep particle plumes at each of these volcanoes are remarkably similar in their widespread distribution (to 10’s of km from the summit and at multiple depths down the flanks) and composition (dominantly fresh volcanic ash). Moderate eruption rates, lava-seawater interaction and steep slopes below an eruptive vent may be sufficient to initiate the transport of fine ash into the ocean environment and distal sediments via these types of plumes.

Walker, S. L.; Baker, E. T.; Leybourne, M. I.; de Ronde, C. E.; Greene, R.; Faure, K.; Chadwick, W.; Dziak, R. P.; Lupton, J. E.; Lebon, G.

2010-12-01

198

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.

199

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

200

Medical Implications of Women On Submarines.  

National Technical Information Service (NTIS)

The review highlights traditionally important medical conditions for submariners along with the unique consequence of women's health care on the submarine. The information covered includes a review of the history of women in the military followed by a dis...

J. L. Kane, W. G. Horn

2001-01-01

201

Calculated volumes of individual shield volcanoes at the young end of the Hawaiian Ridge  

Microsoft Academic Search

High-resolution multibeam bathymetry and a digital elevation model of the Hawaiian Islands are used to calculate the volumes of individual shield volcanoes and island complexes (Niihau, Kauai, Oahu, the Maui Nui complex, and Hawaii), taking into account subsidence of the Pacific plate under the load of the Hawaiian Ridge. Our calculated volume for the Island of Hawaii and its submarine

Joel E. Robinson; Barry W. Eakins

2006-01-01

202

Exploration of the 1891 Foerstner submarine vent site (Pantelleria, Italy): insights into the formation of basaltic balloons  

NASA Astrophysics Data System (ADS)

On October 17, 1891, a submarine eruption started at Foerstner volcano located within the Pantelleria Rift of the Strait of Sicily (Italy). Activity occurred for a period of 1 week from an eruptive vent located 4 km northwest of the island of Pantelleria at a water depth of 250 m. The eruption produced lava balloons that discharged gas at the surface and eventually sank to the seafloor. Remotely operated vehicle (ROV) video footage and high-resolution multi-beam mapping of the Foerstner vent site were used to create a geologic map of the AD 1891 deposits and conduct the first detailed study of the source area associated with this unusual type of submarine volcanism. The main Foerstner vent consists of two overlapping circular mounds with a total volume of 6.3 × 105 m3 and relief of 60 m. It is dominantly constructed of clastic scoriaceous deposits with some interbedded pillow lavas. Petrographic and geochemical analyses of Foerstner samples by X-ray fluorescence and inductively coupled plasma mass spectrometry reveal that the majority of the deposits are vesicular, hypocrystalline basanite scoria that display porphyritic, hyaloophitic, and vitrophyric textures. An intact lava balloon recovered from the seafloor consists of a large interior gas cavity surrounded by a thin lava shell comprising two distinct layers: a thin, oxidized, quenched crust surrounding the exterior of the balloon and a dark gray, tachylite layer lying beneath it. Ostwald ripening is proposed to be the dominant bubble growth mechanism of four representative Foerstner scoria samples as inferred by vesicle size distributions. Characterization of the diversity of deposit facies observed at Foerstner in conjunction with quantitative rock texture analysis indicates that submarine Strombolian-like activity is the most likely mechanism for the formation of lava balloons. The deposit facies observed at the main Foerstner vent are very similar to those produced by other known submarine Strombolian eruptions (short pillow flow lobes, large scoriaceous clasts, spatter-like vent facies). Balloons were likely formed from the rapid cooling of extremely vesicular magma fragments as a result of a gas-rich frothy magma source. The exterior of these fragments hyperquenched forming a vesicular glassy shell that acted as an insulating layer preventing magmatic gas in its interior from escaping and thus allowing flotation as densities reached less than 1,000 kg/m3. We believe that lava balloons are a common eruptive product, as the conditions required to generate these products are likely to be present in a variety of submarine volcanic environments. Additionally, the facies relationships observed at Foerstner may be used as a paleoenvironmental indicator for modern and ancient basaltic shallow submarine eruptions because of the relatively narrow depth range over which they likely occur (200-400 m).

Kelly, Joshua T.; Carey, Steven; Pistolesi, Marco; Rosi, Mauro; Croff-Bell, Katherine Lynn; Roman, Chris; Marani, Michael

2014-07-01

203

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.

204

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

205

A comparison of eruption mechanisms in subaerial and submarine arc environments (Invited)  

NASA Astrophysics Data System (ADS)

The past few decades of research on submarine arc volcanism have produced exciting new observations that allow us to address long-standing questions about the role of seawater on submarine eruption dynamics. Although conduit processes in submarine arc volcanoes are probably similar to those in their subaerial counterparts, as illustrated by similarities in bubble and crystal textures in erupted pyroclasts, the effect of the overlying water column on syn- and post-eruptive processes can be dramatic. Perhaps most important is a blurring of the distinction between primary and secondary emplacement of pyroclastic material as a consequence of rapid remobilization of primary deposits down submarine slopes. As a result, it may prove difficult to distinguish between submarine pyroclastic (primary) and volcaniclastic (secondary) deposits in the geologic record. Other subaerial eruptive categories are also less distinct in the submarine environment. Plume rise is suppressed by the efficiency of steam condensation, from loss of buoyancy due to mixing with seawater, and by the rapid deceleration of solid pyroclasts in the overlying water column. Together these processes contribute to efficient segregation of fine and coarse pyroclasts very close to the vent. As magmatic steam contained within pyroclasts also condenses and drives rapid ingestion of seawater, most pyroclasts will sink, which promotes cone growth over development of widespread pyroclastic deposits. An exception is material that is sufficiently fine-grained to be carried by water currents. Efficient winnowing of fines from both fall and flow deposits renders the grain-size distinction between these deposit types less distinctive than in subaerial deposits. Finally, seawater-induced spalling of fragments from effusive extrusions accompanied by vigorous degassing can produce a local fall deposit, thus blurring the distinction between explosive and effusive eruptive mechanisms. Together these observations suggest caution in direct transferal of terminology and interpretations developed for subaerial eruptions to the submarine environment.

Cashman, K. V.; Chadwick, W.; Fiske, R. S.; Deardorff, N.

2009-12-01

206

Absolute and relative locations of earthquakes at Mount St. Helens, Washington, using continuous data: implications for magmatic processes: Chapter 4 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006  

USGS Publications Warehouse

This study uses a combination of absolute and relative locations from earthquake multiplets to investigate the seismicity associated with the eruptive sequence at Mount St. Helens between September 23, 2004, and November 20, 2004. Multiplets, a prominent feature of seismicity during this time period, occurred as volcano-tectonic, hybrid, and low-frequency earthquakes spanning a large range of magnitudes and lifespans. Absolute locations were improved through the use of a new one-dimensional velocity model with excellent shallow constraints on P-wave velocities. We used jackknife tests to minimize possible biases in absolute and relative locations resulting from station outages and changing station configurations. In this paper, we show that earthquake hypocenters shallowed before the October 1 explosion along a north-dipping structure under the 1980-86 dome. Relative relocations of multiplets during the initial seismic unrest and ensuing eruption showed rather small source volumes before the October 1 explosion and larger tabular source volumes after October 5. All multiplets possess absolute locations very close to each other. However, the highly dissimilar waveforms displayed by each of the multiplets analyzed suggest that different sources and mechanisms were present within a very small source volume. We suggest that multiplets were related to pressurization of the conduit system that produced a stationary source that was highly stable over long time periods. On the basis of their response to explosions occurring in October 2004, earthquakes not associated with multiplets also appeared to be pressure dependent. The pressure source for these earthquakes appeared, however, to be different from the pressure source of the multiplets.

Thelen, Weston A.; Crosson, Robert S.; Creager, Kenneth C.

2008-01-01

207

Evaluation of Ancient and Future Submarine Landslides Along the Central California Coast and Their Potential to Generate Tsunamis  

Microsoft Academic Search

Submarine landslides have been located along the central California continental margin with the use of multibeam bathymetric and sub-bottom profiling data. These features are primarily concentrated on the lower continental slope and in submarine canyons. Recent evaluation of these landslides indicates that they are of various ages and types and formed in different ways. For example, the extensive slope failure

H. G. Greene; C. K. Paull; S. Ward; W. Ussler; N. M. Maher

2001-01-01

208

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.

209

Detailed gravity study of the offshore structure of Piton de la Fournaise volcano, Reunion Island  

NASA Astrophysics Data System (ADS)

We present an interpretation of gravity data acquired in 1984 by the French R/V Jean Charcot on the submarine part of the eastern flank of Piton de la Fournaise volcano. We comment on the Bouguer anomaly map and give a quantitative interpretation of three gravity profiles. The main results are that a gravity high over Grand Brûlé, the lower subaerial part of the eastern flank, does not extend far offshore and that an anomalous topographic feature, discovered in 1982 on the submarine eastern flank, is characterized by a large negative anomaly. We propose three hypotheses to explain the origin of this anomaly, i. e., it marks the site of a new volcano, or it is a consequence of lateral volcanism from a volcano older than Piton de la Fournaise, or more probably, it represents a great landslide deposit.

Rousset, Dominique; Bonneville, Alain; Lenat, Jean-François

1987-12-01

210

Flow dynamics around downwelling submarine canyons  

NASA Astrophysics Data System (ADS)

Flow dynamics around a downwelling submarine canyon were analysed with the Massachusetts Institute of Technology general circulation model. Blanes Canyon (northwestern Mediterranean) was used for topographic and initial forcing conditions. Fourteen scenarios were modelled with varying forcing conditions. Rossby and Burger numbers were used to determine the significance of Coriolis acceleration and stratification (respectively) and their impacts on flow dynamics. A new non-dimensional parameter (?) was introduced to determine the significance of vertical variations in stratification. Some simulations do see brief periods of upwards displacement of water during the 10-day model period; however, the presence of the submarine canyon is found to enhance downwards advection of density in all model scenarios. High Burger numbers lead to negative vorticity and a trapped anticyclonic eddy within the canyon, as well as an increased density anomaly. Low Burger numbers lead to positive vorticity, cyclonic circulation, and weaker density anomalies. Vertical variations in stratification affect zonal jet placement. Under the same forcing conditions, the zonal jet is pushed offshore in more uniformly stratified domains. The offshore jet location generates upwards density advection away from the canyon, while onshore jets generate downwards density advection everywhere within the model domain. Increasing Rossby values across the canyon axis, as well as decreasing Burger values, increase negative vertical flux at shelf break depth (150 m). Increasing Rossby numbers lead to stronger downwards advection of a passive tracer (nitrate), as well as stronger vorticity within the canyon. Results from previous studies are explained within this new dynamic framework.

Spurgin, J. M.; Allen, S. E.

2014-10-01

211

Bathymetry of the southwest flank of Mauna Loa Volcano, Hawaii  

USGS Publications Warehouse

Much of the seafloor topography in the map area is on the southwest submarine flank of the currently active Mauna Loa Volcano. The benches and blocky hills shown on the map were shaped by giant landslides that resulted from instability of the rapidly growing volcano. These landslides were imagined during a 1986 to 1991 swath sonar program of the United States Hawaiian Exclusive Economic Zone, a cooperative venture by the U.S. Geological Survey and the British Institute of Oceanographic Sciences (Lipman and others, 1988; Moore and others, 1989). Dana Seamount (and probably also the neighboring Day Seamount) are apparently Cretaceous in age, based on paleomagnetic studies, and predate the growth of the Hawaiian Ridge volcanoes (Sager and Pringle, 1990).

Chadwick, William W.; Moore, James G.; Fox, Christopher G.

1994-01-01

212

Postshield stage transitional volcanism on Mahukona Volcano, Hawaii  

USGS Publications Warehouse

Age spectra from 40Ar/39Ar incremental heating experiments yield ages of 298??25 ka and 310??31 ka for transitional composition lavas from two cones on submarine Mahukona Volcano, Hawaii. These ages are younger than the inferred end of the tholeiitic shield stage and indicate that the volcano had entered the postshield alkalic stage before going extinct. Previously reported elevated helium isotopic ratios of lavas from one of these cones were incorrectly interpreted to indicate eruption during a preshield alkalic stage. Consequently, high helium isotopic ratios are a poor indicator of eruptive stage, as they occur in preshield, shield, and postshield stage lavas. Loihi Seamount and Kilauea are the only known Hawaiian volcanoes where the volume of preshield alkalic stage lavas can be estimated. ?? Springer-Verlag 2008.

Clague, D.A.; Calvert, A.T.

2009-01-01

213

Digital Transmission over Submarine Cables  

Microsoft Academic Search

The problems of transoceanic transmission of large volumes of information have been raised increasingly over the past few years. Lately, the need for transoceanic digital communications has been of interest. This paper discusses the significance of these trends and examines the technical prospects for handling large volumes of digital traffic using submarine cables. Concentrating on transatlantic traffic, an argument is

W. Litchman

1965-01-01

214

Initial waves from submarine landslides  

Microsoft Academic Search

Modeling tsunamis generated by submarine mass failure is not as well understood as waves generated by seismic displacements. Co-seismic deformation occurs very rapidly even in comparison with the shallow-water wave speed, allowing for a specification of the displacement of the sea surface to be set as identical to the deformation of the ocean floor, as initial conditions for computer modeling.

R. Weiss; C. Synolakis

2009-01-01

215

Initial waves from submarine landslides  

Microsoft Academic Search

Modeling tsunamis generated by submarine mass failure is not as well understood as waves generated by seismic displacements. Co-seismic deformation occurs very rapidly even in comparison with the shallow-water wave speed, allowing for a specification of the displacement of the sea surface to be set as identical to the deformation of the ocean floor, as initial conditions for computer modeling.

R. Weiss; C. E. Synolakis; J. A. O'Shay

2010-01-01

216

Currents in Monterey Submarine Canyon  

Microsoft Academic Search

Flow fields of mean, subtidal, and tidal frequencies between 250 and 3300 m water depths in Monterey Submarine Canyon are examined using current measurements obtained in three yearlong field experiments. Spatial variations in flow fields are mainly controlled by the topography (shape and width) of the canyon. The mean currents flow upcanyon in the offshore reaches (>1000 m) and downcanyon

J. P. Xu; Marlene A. Noble

2009-01-01

217

Diversity and Abundance of Aerobic and Anaerobic Methane Oxidizers at the Haakon Mosby Mud Volcano, Barents Sea  

Microsoft Academic Search

Submarine mud volcanoes are formed by expulsions of mud, fluids, and gases from deeply buried subsurface sources. They are highly reduced benthic habitats and often associated with intensive methane seepage. In this study, the microbial diversity and community structure in methane-rich sediments of the Haakon Mosby Mud Volcano (HMMV) were investigated by comparative sequence analysis of 16S rRNA genes and

Tina Losekann; Katrin Knittel; Thierry Nadalig; Bernhard Fuchs; Helge Niemann; Antje Boetius; Rudolf Amann

2007-01-01

218

Stratigraphy of the Hawai`i Scientific Drilling Project core (HSDP2): Anatomy of a Hawaiian shield volcano  

Microsoft Academic Search

The Hawai`i Scientific Drilling Project (HSDP2) successfully drilled ~3.1 km into the island of Hawai`i. Drilling started on Mauna Loa volcano, drilling 247 m of subaerial lavas before encountering 832 m of subaerial Mauna Kea lavas, followed by 2019 m of submarine Mauna Kea volcanic and sedimentary units. The 2.85 km stratigraphic record of Mauna Kea volcano spans back to

Michael O. Garcia; Eric H. Haskins; Edward M. Stolper; Michael Baker

2007-01-01

219

Titan2D Based Pyroclastic Flows Hazard Maps for Santa Ana Volcano, El Salvador  

Microsoft Academic Search

Santa Ana Volcano is located in the Apaneca Volcanic Field located to the west of El Salvador, Central America. It is one the six active volcanoes monitor by the Servicios Nacionales de Estudios Territoriales (SNET) in El Salvador, out of twenty that are considered active in this small country by Smithsonian definition. The Santa Ana Volcano is surrounded by rural

J. V. Bajo; B. Martinez-Hackert; C. D. Escobar; R. E. Gutierrez

2009-01-01

220

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

221

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

222

The 1998 eruption of Axial Seamount: New insights on submarine lava flow emplacement from high-resolution mapping  

NASA Astrophysics Data System (ADS)

Axial Seamount, an active submarine volcano on the Juan de Fuca Ridge at 46°N, 130°W, erupted in January 1998 along 11 km of its upper south rift zone. We use ship-based multibeam sonar, high-resolution (1 m) bathymetry, sidescan sonar imagery, and submersible dive observations to map four separate 1998 lava flows that were fed from 11 eruptive fissures. These new mapping results give an eruption volume of 31 × 106 m3, 70% of which was in the northern-most flow, 23% in the southern-most flow, and 7% in two smaller flows in between. We introduce the concept of map-scale submarine lava flow morphology (observed at a scale of hundreds of meters, as revealed by the high-resolution bathymetry), and an interpretive model in which two map-scale morphologies are produced by high effusion-rate eruptions: "inflated lobate flows" are formed near eruptive vents, and where they drain downslope more than 0.5-1.0 km, they transition to "inflated pillow flows." These two morphologies are observed on the 1998 lava flows at Axial. A third map-scale flow morphology that was not produced during this eruption, "pillow mounds," is formed by low effusion-rate eruptions in which pillow lava piles up directly over the eruptive vents. Axial Seamount erupted again in April 2011 and there are remarkable similarities between the 1998 and 2011 eruptions, particularly the locations of eruptive vents and lava flow morphologies. Because the 2011 eruption reused most of the same eruptive fissures, 58% of the area of the 1998 lava flows is now covered by 2011 lava.

Chadwick, W. W.; Clague, D. A.; Embley, R. W.; Perfit, M. R.; Butterfield, D. A.; Caress, D. W.; Paduan, J. B.; Martin, J. F.; Sasnett, P.; Merle, S. G.; Bobbitt, A. M.

2013-10-01

223

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

224

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

225

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

226

An ongoing large submarine landslide at the Japan trench  

NASA Astrophysics Data System (ADS)

This paper deals with an active submarine landslide on a landward trench slope in the Japan trench. Studied area is located on the upper terrace ranging from 400 to 1200 m in water depth, off Sendai, northeast Japan. We have surveyed in detail the seabed topography using a multi narrow beam (hereafter MBES) and a subbottom profiler (hereafter SBP) during the cruise MR12-E02 of R/V Mirai. The survey lines were 12 lines in N-S, and 3 lines in E-W, and situated in the region from 141°45'E, 37°40'N to 142°33'E, 38°32'N. Moreover, we used multi-channel seismic profile by the cruise KR04-10 of R/V Kairei in the interpretation of the SBP results. In general, horseshoe-shaped depressions of about 100 km wide along the trench slope are arrayed along the Japan trench. It has thought that they were formed by large submarine landslides, but we could not understand critically the relationship between the depressions and the submarine landslides. Based on the survey results, we found signals of an active submarine landslide in the depression as follows. 1) We observed arcuate-shaped lineaments, which are sub-parallel to a horseshoe-shaped depression. The lineaments concentrate in the south region from 38°N at about 20 km wide. These lineaments are formed by deformation structures as anticlines, synclines and normal fault sense displacements. 2) Most of the synclines and anticlines are not buried to form the lineaments. 3) Normal faults cutting about 1 km deep are observed in a multi-channel seismic profile. The normal faults are located just below the arcuate-shaped lineaments, and are tilted eastward being the downslope direction. It indicates a large submarine landslide. We concluded that the arcuate-shaped lineaments were generated by surface sediment movement with the submarine landsliding. We think that the submarine landslide of about 20 km wide and about 1 km thick move continuously down the landward trench slope. This would be the formation process of the horseshoe-shaped depression along the Japan trench.

Nitta, S.; Kasaya, T.; Miura, S.; Kawamura, K.

2013-12-01

227

30. VIEW OF PHOTO CAPTIONED 'SUBMARINE BASE, NEW LONDON, CONNECTICUT. ...  

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

30. VIEW OF PHOTO CAPTIONED 'SUBMARINE BASE, NEW LONDON, CONNECTICUT. 2 JUNE 1930. SUBMARINE TRAINING TANK - STEELWORK 98% COMPLETE; BRICKWORK 95% COMPLETE, PIPING 10% IN PLACE. LOOKING NORTH. CONTRACT NO. Y-1539-ELEVATOR, SUBMARINE ESCAPE TANK.' - U.S. Naval Submarine Base, New London Submarine Escape Training Tank, Albacore & Darter Roads, Groton, New London County, CT

228

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

229

Clay alteration of volcaniclastic material in a submarine geothermal system, Bay of Plenty, New Zealand  

NASA Astrophysics Data System (ADS)

The Calypso Hydrothermal Vent Field (CHVF) is located along an offshore extension of the Taupo Volcanic Zone (TVZ), an area of abundant volcanism and geothermal activity on the North Island of New Zealand. The field occurs within a northeast-trending submarine depression on the continental shelf approximately 10-15 km southwest of the White Island volcano in the Bay of Plenty. The graben has been partially filled by tephra from regional subaerial volcanic eruptions, and active hydrothermal venting occurs at several locations along its length. The vents occur at water depths of 160 to 190 m and have temperatures up to 201 °C. Recovered samples from the vent field include variably cemented and veined volcaniclastic sediments containing an assemblage of clay minerals, amorphous silica, barite, As-Sb-Hg sulfides, and abundant native sulfur. The volcanic glass has been altered primarily to montmorillonite and mixed-layer illite-montmorillonite; illite, and possibly minor talc and mixed-layer chlorite-smectite or chlorite-vermiculite are also present. A hydrothermal versus diagenetic origin for the smectite is indicated by the presence of both illite and mixed-layer clays and by the correlation between the abundance of clay minerals and the abundance of native sulfur in the samples. The mineralization and alteration of the volcanic host rocks are similar to that observed in near-neutral pH geothermal systems on land in the TVZ (e.g., Broadlands-Ohaaki). However, the clay minerals in the CHVF have a higher concentration of Mg in the dioctahedral layer and a higher interlayer Na content than clay minerals from Broadlands-Ohaaki, reflecting the higher concentrations of Mg and Na in seawater compared to meteoric water. Minerals formed at very low pH (e.g., kaolinite and alunite), typical of steam-heated acid-sulfate type alteration in the TVZ geothermal environment, were not found. Mixing with seawater likely prevented the formation of such low-pH mineral assemblages. The occurrence of illite and mixed-layer illite-smectite close to the seafloor in the CHVF, rather than at depth as in the Broadlands system, is interpreted to reflect the higher pressures associated with submarine venting. This allows hotter fluids to be discharged before they boil, and thus minerals that are encountered mainly at depth in subaerial geothermal systems can form close to the seafloor.

Hocking, Michael W. A.; Hannington, Mark D.; Percival, Jeanne B.; Stoffers, Peter; Schwarz-Schampera, Ulrich; de Ronde, C. E. J.

2010-04-01

230

Directional VLF antenna for communicating with submarines  

NASA Astrophysics Data System (ADS)

High-power, very low frequency transmitters for communicating with submarines use electrically short, top-loaded, vertical monopoles. These are efficient radiators of the lateral surface wave, but since they are omnidirectional, they expose residents of neighboring urban areas to possibly harmful effects. A possible alternative, the horizontal traveling-wave antenna of the Beverage type, is analyzed, and the design for the frequency range from 10 to 30 kHz is described. The antenna is highly directive in the horizontal plane. Although the field of the unit horizontal dipole over the earth is much smaller than that of the unit vertical dipole, the large effective length of the traveling-wave antenna makes its field comparable to that of the electrically short vertical monopole. Furthermore, since the radiated field in all directions except within a 30° to 60° angle out to sea is small, there is no exposure risk when the electrically long horizontal antenna is located near inhabited areas.

King, Ronold W. P.

1997-01-01

231

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

232

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

233

A giant three-stage submarine slide off Norway  

Microsoft Academic Search

One of the largest submarine slides known, The Storegga Slide, is located on the Norwegian continental margin. The slide is up to 450 m thick and has a total volume of about 5,600 km3. The headwall of the slide scar is 290 km long and the total run-out distance is about 800 km. The slide involved sediments of Quaternary to

Tom Bugge; Stein Befring; Robert H. Belderson; Tor Eidvin; Eystein Jansen; Neil H. Kenyon; Hans Holtedahl; Hans Petter Sejrup

1987-01-01

234

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

235

Initial waves from submarine landslides  

NASA Astrophysics Data System (ADS)

Modeling tsunamis generated by submarine mass failure is not as well understood as waves generated by seismic displacements. Co-seismic deformation occurs very rapidly even in comparison with the shallow-water wave speed, allowing for a specification of the displacement of the sea surface to be set as identical to the deformation of the ocean floor, as initial conditions for computer modeling. Submarine mass failure exhibits slower speeds and water gravitationally adjusts to a new potential field while the submarine mass is failing. Empirical formulae and computer models exist to calculate the one or two-dimensional surface waveform generated by underwater mass movements. For different empirical formulae, estimates vary over orders of magnitude for the same slide. We present the scatter from ten different empirical formulations for the leading wave amplitude for 19 different underwater landslides. Some of these formulations are based on modeling, some on analytical solutions, and some are based on experimental data. The scatter highlights that it is important to use higher order approximations of the Navier-Stokes equations to reliably and robustly compute the interaction between water surface and the deforming mass. We carry out modeling with iSALE, a hydrocode that numerically solves the compressible Navier-Stokes equations in a multi-material and multi-rheology framework, and present preliminary results for the leading wave height with varying rheologies to account for different slide materials. It appears that multi-material modeling is important in for understanding the hydrodynamics of tsunamis generated by submarine mass failures under geophysically realistic conditions.

Weiss, R.; Synolakis, C.

2009-12-01

236

Initial waves from submarine landslides  

NASA Astrophysics Data System (ADS)

Modeling tsunamis generated by submarine mass failure is not as well understood as waves generated by seismic displacements. Co-seismic deformation occurs very rapidly even in comparison with the shallow-water wave speed, allowing for a specification of the displacement of the sea surface to be set as identical to the deformation of the ocean floor, as initial conditions for computer modeling. Submarine mass failure exhibits slower speeds and water gravitationally adjusts to a new potential field while the submarine mass is failing. Empirical formulae and computer models exist to calculate the one or two-dimensional surface waveform generated by underwater mass movements. For different empirical formulae, estimates vary over orders of magnitude for the same slide. We present the scatter from ten different empirical formulations for the leading wave amplitude for 19 different underwater landslides. Some of these formulations are based on modeling, some on analytical solutions, and some are based on experimental data. The scatter highlights that it is important to use higher order approximations of the Navier-Stokes equations to reliably and robustly compute the interaction between water surface and the deforming mass. We carry out modeling with iSALE, a hydrocode that numerically solves the compressible Navier-Stokes equations in a multi-material and multi-rheology framework, and present preliminary results for the leading wave height with varying rheologies to account for different slide materials. It appears that multi-material modeling is important in for understanding the hydrodynamics of tsunamis generated by submarine mass failures under geophysically realistic conditions.

Weiss, R.; Synolakis, C. E.; O'Shay, J. A.

2010-12-01

237

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

238

34. VIEW OF SUBMARINE ESCAPE TRAINING TANK PRIOR TO ADDITION ...  

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

34. VIEW OF SUBMARINE ESCAPE TRAINING TANK PRIOR TO ADDITION OF BLISTERS IN 1959, LOOKING SOUTHEAST - U.S. Naval Submarine Base, New London Submarine Escape Training Tank, Albacore & Darter Roads, Groton, New London County, CT

239

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

240

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

241

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

242

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

243

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

244

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

245

Geomorphic evolution of the Piton des Neiges volcano (Réunion Island, Indian Ocean): Competition between volcanic construction and erosion since 1.4 Ma  

NASA Astrophysics Data System (ADS)

Réunion Island (Indian Ocean) is a volcanic complex whose eruptive history was dominated by the activity of two main edifices: Piton des Neiges (PN) and Piton de la Fournaise (PF) volcanoes. The tropical climate induces erosion processes that permanently compete with volcanic constructional processes. Exposed to the trade winds and associated heavy rainfalls, the northeastern part of the island exhibits the most complex morphological evolution. Geomorphological analysis, performed on a 50 m DEM and associated to new K-Ar ages has clarified the overall history of PN volcano. Each massif is assigned to one of the main building stages of the edifice. In addition, the arrangement of these different massifs reveals that the eruptive phases have led to successive relief inversions and successive excavations of large central depressions in the proximal area. As a result, the younger massifs are always located in more proximal parts of the volcano, the youngest being close to the edifice center. In distal areas, early lava flows were channeled into valleys incised along the massif boundaries, leading to a more complex geochronological organization. Quantitative study of the dissection of PN volcano allows us to propose a minimum eroded volume of 101 ± 44 and 105 ± 41 km 3 for the Mafate and Cilaos "Cirques" (depressions), respectively, during the last 180 kyr and a minimum average long-term erosion rate of 1.2 ± 0.4 km 3/ka. This leads us to estimate the removed volume during the whole history of PN volcano (> 1000 km 3) as equivalent to the volume of the deposits identified on the submarine flanks of Piton des Neiges volcano. Therefore, as regressive erosion appears to be the prevailing geomorphic process during the whole PN history, it questions the presence of major flank collapses younger than 1.4 Ma on this volcano. Erosion processes have largely been neglected in recent models, but our study emphasizes them as a key component of landscape development and a major process in the morphological evolution of Réunion Island that has to be fully integrated in future studies.

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

2012-01-01

246

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

247

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

248

Sapas Mons, Venus: evolution of a large shield volcano  

Microsoft Academic Search

Magellan radar image data of Sapas Mons, a 600 km diameter volcano located on the flanks of the Arla Rise, permit the distinction of widespread volcanic units on the basis of radar properties, morphology, and spatial and inferred temporal relations, each representing a stage or phase in the evolution of the volcano. Six flow units were identified and are arranged

Susan T. Keddie; James W. Head

1994-01-01

249

Geochemical stratigraphy and magmatic evolution at Arenal Volcano, Costa Rica  

E-print Network

Geochemical stratigraphy and magmatic evolution at Arenal Volcano, Costa Rica Louise L. Bolge a Miravalles (OSIVAM), Instituto Costarricense de, Electricidad (ICE), Apdo. 10032-1000, Costa Rica Received 13; tephrostratigraphy; Central American arc 1. Introduction Arenal is a small strato volcano located in Costa Rica (10

250

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

251

An assessment of shuttle radar topography mission digital elevation data for studies of volcano morphology  

E-print Network

An assessment of shuttle radar topography mission digital elevation data for studies of volcano's volcanoes. Although these data were acquired with a nominal spatial resolution of 30 m, such data are only available for volcanoes located within the U.S.A. and its Territories. For the overwhelming majority

Wright, Robert

252

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

253

Decreasing Magmatic Footprints of Individual Volcanos in a Waning Basaltic Field  

SciTech Connect

The distribution and characteristics of individual basaltic volcanoes in the waning Southwestern Nevada Volcanic Field provide insight into the changing physical nature of magmatism and the controls on volcano location. During Pliocene-Pleistocene times the volumes of individual volcanoes have decreased by more than one order of magnitude, as have fissure lengths and inferred lava effusion rates. Eruptions evolved from Hawaiian-style eruptions with extensive lavas to eruptions characterized by small pulses of lava and Strombolian to violent Strombolian mechanisms. These trends indicate progressively decreasing partial melting and length scales, or magmatic footprints, of mantle source zones for individual volcanoes. The location of each volcano is determined by the location of its magmatic footprint at depth, and only by shallow structural and topographic features that are within that footprint. The locations of future volcanoes in a waning system are less likely to be determined by large-scale topography or structures than were older, larger volume volcanoes.

G.A> Valentine; F.V. Perry

2006-06-06

254

Correlation of submarine deposits and witness accounts of the 1952 Myojinsho submarine eruption, Izu-Bonin arc, by bathymetric survey  

NASA Astrophysics Data System (ADS)

The relationship between eruptive phenomena during the 1952 phreatomagmatic eruption and consequent deposits under seawater is discussed, on the basis of bathymetric survey of Myojinsho volcano, Izu-Bonin island arc (32°55’N, 140°00’E). We carried out some research cruises by the ship Natsushima (JAMSTEC) in 2006-2008. We used unmanned bathymetric vehicle, Hyperdolphin, for observation and sampling of the submarine deposit. Myojinsho volcano is an active post-caldera volcano that grew on the northeastern rim of Myojinsho caldera (8 x 6 km in diameter). There have been many reports of colored seawater, and we also recognized a bubbly column above the summit of Myojinsho (Myojin reef; ca. 50 m below sea level) during acoustic survey. The 1952 eruption was the latest eruption that formed and destroyed new island above sea level, and would have been the first submarine eruption to be recorded by good scientific standard. This eruption was firstly recognized at the middle of September, 1952, and explosions and dome growth have been documented for about 1 year till the middle of September, 1953. There are many time series color photographs of explosions so that we can evaluate these explosions quantitatively (Ossaka, 1991). These records indicate that most of the cock’s tail jets are limited within the proximal area (ca. 500m) from the center of explosions, whereas the base surges and lateral steam clouds reach farther than ca. 500 m. During the bathymetric survey, we found several small lobes of pumice-rich deposits (< 1 m thick, several meter wide, several tens of meter long) on the sandy flat slope father than ca. 500 m from the summit of Myojinsho (deeper than ca. 300 m below sea level). Large pumices are concentrated at the front of each lobe, and the lobes become thinner toward the summit. On the other hand, the proximal deposit (<500 m from the summit) is characterized by scattered large angular blocky rocks or pumices. The largest blocks are as large as several meters in diameter. The compositional variations and textural features of these pumices and blocks are similar to those reported for samples obtained during the eruption. The correspondence of the lateral changes in witnessed phenomena (cock’s tail jets to base surges) and in depositional features (scattered blocks to pumice lobes) would indicate that (1) the lobes of pumices are derived either by base surges or by lateral steam clouds, and that (2) large angular blocks are derived by cock’s tail jets during explosions or dome collapse occurred at the end of the eruption.

Shimano, T.; Tani, K.; Maeno, F.; Fiske, R. S.; Shukuno, H.; Ito, K.; Shimoda, G.; Suzuki, Y. J.; Yoshida, T.; Taniguchi, H.

2009-12-01

255

Submarine Maneuvers Prediction using Recursive Neural Networks  

Microsoft Academic Search

Recursive neural networks (RNNs) are a technique for developing time-dependent, nonlinear equation systems. In this paper, we applied RNN to simulate the maneuvers of submarine. The forces and moments acting on the body of submarine are functions of the motion state variables. Component force modules is developed to calculate five component forces as inputs to the recursive neural networks. These

Hassan Fahmy Hashem; Alexandria HighInstitute

2006-01-01

256

Research on Submarine Maneuverability of Flooded Compartment  

Microsoft Academic Search

The paper establishes the emergency recovery maneuver motion model. According to the characteristic of hydrodynamics coefficients on flooded submarine, attaining hydrodynamics coefficients of different angle of attack by limited ship model hydrodynamics experiment of large angle of attack. A sensitivity index is introduced to evaluate submarine's controllability. The experiment results are regressed to two kinds of hydrodynamic coefficients for big

Liu Hui; Pu Jinyun; Jin Tao

2009-01-01

257

Aquifers and groundwater within active shield volcanoes. Evolution of conceptual models in the Piton de la Fournaise volcano  

Microsoft Academic Search

The uncertainty regarding hydrogeological models that have been proposed for describing active volcanoes results from the difficulty of prospecting deep groundwater bodies. In the case of the Piton de la Fournaise volcano located in Reunion Island, recent geophysical exploration using deep electromagnetic (EM) prospecting tools has provided new geostructural and hydrogeological information. This paper introduces yet a new hydrogeological model,

Jean-Lambert Join; Jean-Luc Folio; Bernard Robineau

2005-01-01

258

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

259

Investigating the active hydrothermal field of Kolumbo Volcano using CTD profiling  

NASA Astrophysics Data System (ADS)

The submarine Kolumbo volcano NE of Santorini Island and the unique active hydrothermal vent field on its crater field (depth ~ 500 m) have been recently explored in multiple cruises aboard E/V Nautilus. ROV explorations showed the existence of extensive vent activity and almost completely absence of vent-specific macrofauna. Gas discharges have been found to be 99%-rich in CO2, which is sequestered at the bottom of the crater due to a special combination of physicochemical and geomorphological factors. The dynamic conditions existing along the water column in the crater have been studied in detail by means of temperature, salinity and conductivity depth profiles for the first time. CTD sensors aboard the ROV Hercules were employed to record anomalies in those parameters in an attempt to investigate several active and inactive vent locations. Temporal CTD monitoring inside and outside of the crater was carried out over a period of two years. Direct comparison between the vent field and locations outside the main cone, where no hydrothermal activity is known to exist, showed completely different characteristics. CTD profiles above the active vent field (NNE side) are correlated to Kolumbo's cone morphology. The profiles suggest the existence of four distinct zones of physicochemical properties in the water column. The layer directly above the chimneys exhibit gas discharges highly enriched in CO2. Continuous gas motoring is essential to identify the onset of geological hazards in the region.

Eleni Christopoulou, Maria; Mertzimekis, Theo; Nomikou, Paraskevi; Papanikolaou, Dimitrios; Carey, Steve

2014-05-01

260

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

Microsoft Academic Search

Nd- and Sr-isotopic data are reported for lavas from 23 submarine and 3 subaerial volcanoes in the northern Mariana and southern Volcano arcs. Values of eNd range from +2.4 to +9.5 whereas 87Sr\\/86Sr ranges from 0.70319 to 0.70392; these vary systematically between and sometimes within arc segments. The Nd-and Sr-isotopic compositions fall in the field of ocean island basalt (OIB)

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

1990-01-01

261

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

Microsoft Academic Search

Nd- and Sr-isotopic data are reported for lavas from 23 submarine and 3 subaerial volcanoes in the northern Mariana and southern Volcano arcs. Values of ?Nd range from +2.4 to +9.5 whereas 87Sr\\/86Sr ranges from 0.70319 to 0.70392; these vary systematically between and sometimes within arc segments. The Nd-and Sr-isotopic compositions fall in the field of ocean island basalt (OIB)

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

1990-01-01

262

Novel microbial communities of the Haakon Mosby mud volcano and their role as a methane sink.  

PubMed

Mud volcanism is an important natural source of the greenhouse gas methane to the hydrosphere and atmosphere. Recent investigations show that the number of active submarine mud volcanoes might be much higher than anticipated (for example, see refs 3-5), and that gas emitted from deep-sea seeps might reach the upper mixed ocean. Unfortunately, global methane emission from active submarine mud volcanoes cannot be quantified because their number and gas release are unknown. It is also unclear how efficiently methane-oxidizing microorganisms remove methane. Here we investigate the methane-emitting Haakon Mosby Mud Volcano (HMMV, Barents Sea, 72 degrees N, 14 degrees 44' E; 1,250 m water depth) to provide quantitative estimates of the in situ composition, distribution and activity of methanotrophs in relation to gas emission. The HMMV hosts three key communities: aerobic methanotrophic bacteria (Methylococcales), anaerobic methanotrophic archaea (ANME-2) thriving below siboglinid tubeworms, and a previously undescribed clade of archaea (ANME-3) associated with bacterial mats. We found that the upward flow of sulphate- and oxygen-free mud volcano fluids restricts the availability of these electron acceptors for methane oxidation, and hence the habitat range of methanotrophs. This mechanism limits the capacity of the microbial methane filter at active marine mud volcanoes to <40% of the total flux. PMID:17051217

Niemann, Helge; Lösekann, Tina; de Beer, Dirk; Elvert, Marcus; Nadalig, Thierry; Knittel, Katrin; Amann, Rudolf; Sauter, Eberhard J; Schlüter, Michael; Klages, Michael; Foucher, Jean Paul; Boetius, Antje

2006-10-19

263

29. VIEW OF SUBMARINE ESCAPE TRAINING TANK DURING CONSTRUCTION AT ...  

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

29. VIEW OF SUBMARINE ESCAPE TRAINING TANK DURING CONSTRUCTION AT POINT JUST ABOVE THE SUBMARINE SECTION AT THE 110-FOOT LEVEL 1929-1930 - U.S. Naval Submarine Base, New London Submarine Escape Training Tank, Albacore & Darter Roads, Groton, New London County, CT

264

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

265

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.

266

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.

267

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

268

Fuel-cell-propelled submarine-tanker-system study  

SciTech Connect

This report provides a systems analysis of a commercial Arctic Ocean submarine tanker system to carry fossil energy to markets. The submarine is to be propelled by a modular Phosphoric Acid Fuel Cell system. The power level is 20 Megawatts. The DOE developed electric utility type fuel cell will be fueled with methanol. Oxidant will be provided from a liquid oxygen tank carried onboard. The twin screw submarine tanker design is sized at 165,000 deadweight tons and the study includes costs and an economic analysis of the transport system of 6 ships. The route will be under the polar icecap from a loading terminal located off Prudhoe Bay, Alaska to a transshipment facility postulated to be in a Norwegian fjord. The system throughput of the gas-fed methanol cargo will be 450,000 barrels per day. The total delivered cost of the methanol including well head purchase price of natural gas, methanol production, and shipping would be $25/bbl from Alaska to the US East Coast. Of this, the shipping cost is $6.80/bbl. All costs in 1981 dollars.

Court, K E; Kumm, W H; O'Callaghan, J E

1982-06-01

269

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.

270

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

271

Co-existing wet and dry basaltic magmas at Torishima volcano, 100 km south of Sumisu caldera, Izu-Bonin arc; implications for arc magma genesis and crustal evolution  

NASA Astrophysics Data System (ADS)

Basalts erupted from Sumisu caldera, Izu-Bonin arc, include both highly depleted, wet basalts and moderately depleted, dry basalts, which were defined as low-Zr basalt and high-Zr basalt, respectively (Tamura et al., 2005). Higher degrees of partial melting of the mantle source are closely related to higher water contents of the basalts. Tamura et al. (2005) suggested that within a single volcanic complex, the water content in the mantle wedge is heterogeneous, resulting in different degrees of partial melting of this source. This was the first documented example of co-existing wet and dry basalts in a single volcano from the Izu-Bonin arc, and it remains unclear if this feature is unique to, or even common within, the Izu-Bonin arc. Here, we propose that Torishima Island is a further example of both wet and dry basalts occurring in a single arc volcano, and suggest that this may be a common feature of the Izu-Bonin arc. Torishima (translated into English as bird-island) is only a small island (3 km in diameter), however it is the subaerial exposure of a large submarine volcano (the 466 km3 Torishima volcano), built from depths of > 1000 m below sea level. The 1902 eruption of Torishima killed all 125 inhabitants, and the island has been uninhabited since 1965, when the weather station was evacuated due to an earthquake swarm in 1965 and 1966. Torishima volcano is situated approximately 100 km south of Sumisu caldera, with no arc volcanoes between the two. Furthermore, ODP Site 788, located on the volcanic front between the two volcanoes, found no proximal lithologies such as lava flows or agglutinates that indicate any submarine volcanic centres at least back to Pliocene times. Thus, a comparative study of Sumisu and Torishima volcanoes is important to determine the temporal dimension of along-strike variations in mantle composition and crust production rates, and to clarify the role that hot fingers (Tamura et al., 2002) might play in the production of arc magmas and crustal evolution. Torishima Island is comprised of three groups of basaltic lavas, distinguished by small, but clear gaps in SiO2 content (< 50 wt. %, ~51-53 wt. %, and ~54.5 wt. % SiO2). Using FeO*/MgO as proxy for differentiation, the basalts form two trends distinguished by their different K2O and Zr contents and Sr/Zr ratios at the same FeO*/MgO. Torishima Island basalts with SiO2 content < 50 wt %, and basaltic rocks with > 50 wt % SiO2 are comparable to the low-Zr and high-Zr basalts of Sumisu caldera (Tamura et al., 2005), respectively. All Torishima volcano basalts are strongly depleted in light rare earth elements (LREE), compared with middle and heavy REE. Importantly, low-Zr basalts at Torishima Island are more LREE depleted than high-Zr basalts, a feature also observed at Sumisu caldera. Our results for Torishima Island basalts suggest that wet and dry basalts co-existing within a single volcanic complex could be a common feature of Izu-Bonin arc volcanoes . A mantle diapir model (Tamura et al., 2005) could explain the petrogenesis of both high-Zr and low-Zr basalts at both Torishima Island and Sumisu Caldera.

Tamura, Y.; Tani, K.; Chang, Q.; Shukuno, H.; Kawabata, H.

2005-12-01

272

Timing of occurrence of large submarine landslides on the Atlantic Ocean margin  

USGS Publications Warehouse

Submarine landslides are distributed unevenly both in space and time. Spatially, they occur most commonly in fjords, active river deltas, submarine canyon-fan systems, the open continental slope and on the flanks of oceanic volcanic islands. Temporally, they are influenced by the size, location, and sedimentology of migrating depocenters, changes in seafloor pressures and temperatures, variations in seismicity and volcanic activity, and changes in groundwater flow conditions. The dominant factor influencing the timing of submarine landslide occurrence is glaciation. A review of known ages of submarine landslides along the margins of the Atlantic Ocean, augmented by a few ages from other submarine locations shows a relatively even distribution of large landslides with time from the last glacial maximum until about five thousand years after the end of glaciation. During the past 5000??yr, the frequency of occurrence is less by a factor of 1.7 to 3.5 than during or shortly after the last glacial/deglaciation period. Such an association likely exists because of the formation of thick deposits of sediment on the upper continental slope during glacial periods and increased seismicity caused by isostatic readjustment during and following deglaciation. Hydrate dissociation may play a role, as suggested previously in the literature, but the connection is unclear.

Lee, H.J.

2009-01-01

273

Assessment of tsunami hazard to the U.S. East Coast using relationships between submarine landslides and earthquakes  

Microsoft Academic Search

Submarine landslides along the continental slope of the U.S. Atlantic margin are potential sources for tsunamis along the U.S. East coast. The magnitude of potential tsunamis depends on the volume and location of the landslides, and tsunami frequency depends on their recurrence interval. However, the size and recurrence interval of submarine landslides along the U.S. Atlantic margin is poorly known.

Uri S. ten Brink; Homa J. Lee; Eric L. Geist; David Twichell

2009-01-01

274

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

275

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

276

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

277

An Overview of Geodetic Volcano Research in the Canary Islands  

NASA Astrophysics Data System (ADS)

The Canary Islands are mostly characterized by diffuse and scattered volcanism affecting a large area, with only one active stratovolcano, the Teide-Pico Viejo complex (Tenerife). More than 2 million people live and work in the 7,447 km2 of the archipelago, resulting in an average population density three times greater than the rest of Spain. This fact, together with the growth of exposure during the past 40 years, increases volcanic risk with respect previous eruptions, as witnessed during the recent 2011-2012 El Hierro submarine eruption. Therefore, in addition to purely scientific reasons there are economic and population-security reasons for developing and maintaining an efficient volcano monitoring system. In this scenario geodetic monitoring represents an important part of the monitoring system. We describe volcano geodetic monitoring research carried out in the Canary Islands and the results obtained. We consider for each epoch the two main existing constraints: the level of volcanic activity in the archipelago, and the limitations of the techniques available at the time. Theoretical and observational aspects are considered, as well as the implications for operational volcano surveillance. Current challenges of and future perspectives in geodetic volcano monitoring in the Canaries are also presented.

Fernández, José; González, Pablo J.; Camacho, Antonio G.; Prieto, Juan F.; Brú, Guadalupe

2014-08-01

278

Complete data listings for CSEM soundings on Kilauea Volcano, Hawaii  

SciTech Connect

This document contains complete data from a controlled-source electromagnetic (CSEM) sounding/mapping project at Kilauea volcano, Hawaii. The data were obtained at 46 locations about a fixed-location, horizontal, polygonal loop source in the summit area of the volcano. The data consist of magnetic field amplitudes and phases at excitation frequencies between 0.04 and 8 Hz. The vector components were measured in a cylindrical coordinate system centered on the loop source. 5 references.

Kauahikaua, J.; Jackson, D.B.; Zablocki, C.J.

1983-01-01

279

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.

280

Capacity upgrade in WDM submarine cable system  

Microsoft Academic Search

The capacity upgrade from 20 Gbit\\/s to 160 Gbit\\/s in a WDM submarine cable system has been designed based on the experimental study of the dependency of the repeater output power and the number of wavelength

Eiichi Shibano; Hidenori Taga; Toshio Kawazawa; Koji Goto

1999-01-01

281

Comparative naval architecture analysis of diesel submarines  

E-print Network

Many comparative naval architecture analyses of surface ships have been performed, but few published comparative analyses of submarines exist. Of the several design concept papers, reports and studies that have been written ...

Torkelson, Kai Oscar

2005-01-01

282

Studies on formation mechanism and source depth of mud volcanoes by using of drilling cores in the Kumano forearc basin, SW Japan  

Microsoft Academic Search

Submarine mud volcanoes are formed as conical mounds composed of erupted unconsolidated or partially consolidated sediments from mud diapirs which are induced by high pore-fluid pressure and buoyancy developed in the deep underground. Most of them were discovered around subduction zones. Mud diapir that brings deep underground materials to seafloor has an important role for material circulations in subduction zones.

S. Muraoka; J. Ashi; T. Kanamatsu; A. Sakaguchi; F. Inagaki

2010-01-01

283

Microbiological and Geochemical Characterization of the Deep Subsurface Environment: Kumano Mud Volcano, Nankai Trough, Japan  

NASA Astrophysics Data System (ADS)

Submarine mud volcanoes play an important environmental role by delivering deep-sourced fluids, elements, and hydrocarbons to the seafloor. These fluxes in turn support chemosynthetic benthic communities. However, due to difficulty in accessing the deep biosphere most mud volcano samples only represent the top one to several meters below seafloor (mbsf) obtainable by remotely operated vehicle (ROV) or gravity cores. Thus, the geochemical and microbiological conditions, as well as vertical homogeneity, deep within mud volcanoes remains poorly constrained. In 2012, using the deep-sea drilling vessel Chikyu, we drilled one of the most active submarine mud volcanoes in the Kumano forearc basin of the Nankai Trough, off the Kii Peninsula of Japan (33°67.581'N, 136°56.8085'E: 1,986.7 m in water depth). Cores were obtained down to 200 mbsf. Cell counts indicate the presence of microorganisms at relatively low abundance (less than 105 cells/cm3) throughout the cored depth. Molecular analyses reveal vertical heterogeneity in the microbial community composition, including specific depth horizons harboring putative methanogenic and methanotrophic phylotypes at >100 mbsf. Geochemical profiles indicate the potential for microbial activity and rate measurements with radiotracers revealed active homoacetogenesis rates that were 2-3 orders of magnitude higher than rates of homo- and acetoclastic methanogenesis. To assess active autotrophic, methanotrophic and heterotrophic populations, 13C- and 15N-amendment experiments with sediment samples collected from 15 and 115 mbsf were established and single cell stable isotope analyses with nanoSIMS are in progress. Our samples and analyses represent a unique observation of a subseafloor setting different from previously explored stratified sediments on continental margins and will allow further understanding of how submarine mud volcanoes contribute to geochemical and microbiological fluxes into the surface biosphere.

Case, D. H.; Ijiri, A.; Morono, Y.; Orphan, V. J.; Inagaki, F.

2013-12-01

284

Addressing submarine geohazards through scientific drilling  

Microsoft Academic Search

Natural submarine geohazards (earthquakes, volcanic eruptions, landslides, volcanic island flank collapses) are geological phenomena originating at or below the seafloor leading to a situation of risk for off-shore and on-shore structures and the coastal population. Addressing submarine geohazards means understanding their spatial and temporal variability, the pre-conditioning factors, their triggers, and the physical processes that control their evolution. Such scientific

A. Camerlenghi

2009-01-01

285

Personality characteristics of successful Navy submarine personnel.  

PubMed

This study evaluated the personality characteristics of senior enlisted and occupationally successful Navy submarine personnel. One hundred subjects completed the Schedule for Nonadaptive and Adaptive Personality (SNAP). Results indicated that the traits of detachment, propriety, and workaholism were most descriptive of the sample. Thirty-seven percent met SNAP criteria for a personality disorder, typically antisocial, obsessive-compulsive, or avoidant. The results are discussed in terms of adaptation to environmental demands aboard submarines. Suggestions for further research are offered. PMID:8935516

Moes, G S; Lall, R; Johnson, W B

1996-04-01

286

Explosion craters associated with shallow submarine gas venting off Panarea island, Italy  

NASA Astrophysics Data System (ADS)

Explosions of hot water, steam, and gas are common periodic events of subaerial geothermal systems. These highly destructive events may cause loss of life and substantial damage to infrastructure, especially in densely populated areas and where geothermal systems are actively exploited for energy. We report on the occurrence of a large number of explosion craters associated with the offshore venting of gas and thermal waters at the volcanic island of Panarea, Italy, demonstrating that violent explosions similar to those observed on land also are common in the shallow submarine environment. With diameters ranging from 5 to over 100 m, the observed circular seafloor depressions record a history of major gas explosions caused by frequent perturbation of the submarine geothermal system over the past 10,000 years. Estimates of the total gas flux indicate that the Panarea geothermal system released over 70 Mt of CO2 over this period of time, suggesting that CO2 venting at submerged arc volcanoes contributes significantly to the global atmospheric budget of this greenhouse gas. The findings at Panarea highlight that shallow submarine gas explosions represent a previously unrecognized volcanic hazard around populated volcanic islands that needs to be taken into account in the development of risk management strategies.

Monecke, Thomas; Petersen, Sven; Hannington, Mark D.; Anzidei, Marco; Esposito, Alessandra; Giordano, Guido; Garbe-Schönberg, Dieter; Augustin, Nico; Melchert, Bernd; Hocking, Mike

2012-11-01

287

Submarine cable OBS using a retired submarine telecommunication cable: GeO-TOC program  

NASA Astrophysics Data System (ADS)

In order to study the Earth's structure and subduction zone tectonics, seismic data from the oceanic region are extremely important. The present seismograph distribution in the oceanic region, however, provides a very poor coverage. To improve this poor seismic coverage, a cable OBS system using a retired submarine telecommunication cable is proposed. The GeO-TOC cable runs from Ninomiya, Japan, to Guam through the Izu-Bonin forearc and the Marina Trough. The total length of the cable is 2659 km. An OBS, IZU, using the GeO-TOC cable, was successfully installed at the landward slope of the Izu-Bonin Trench in January 1997. The IZU OBS is located approximately 400 km south of Tokyo. The installation method is similar to repair work on submarine cables. The IZU OBS is equipped with three accelerometers, a hydrophone, a quartz pressure gauge, and a quartz precision thermometer with a few temperature sensors to monitor overheating of the internal electronics. After installation, the voltage increase is 90 V when the current is maintained at a constant 370 mA. Data from accelerometers are digitized by 24-bit A/D converters and sent to Ninomiya at 9600 bps for each component. Hydrophone data are sent to Ninomiya as analog signals using the AM (Amplitude Modulation) method for safety reasons. Hydrophone data are digitized at the shore station. Other slow-rate data are multiplexed and sent to the shore at 9600 bps. The instrument can be controlled by a shore computer. All data will be transmitted from Ninomiya to Tokyo and combined with other existing seismic data.

Kasahara, Junzo; Utada, Hisashi; Sato, Toshinori; Kinoshita, Hajimu

1998-06-01

288

Three-dimensional flow dynamics of an active submarine channel  

NASA Astrophysics Data System (ADS)

Field scale submarine channel gravity currents are notoriously difficult to measure and thus directly investigate due to their inaccessible location and infrequent nature, which is compounded by present sea-level high-stand. An exception to this is the almost continuous density-driven current that results from the inflow of saline Mediterranean water, via the Bosporus strait, into the Black Sea. This flow has carved a sinuous channel system in water depths of 70 to 120 m. The relatively shallow depths of the channel and the continuous nature of this current provide a rare opportunity to study three-dimensional flow dynamics and the interaction of the flow with a seafloor channel network. Thus, it provides a rare analogue for channelized dilute sediment-laden turbidity currents. Sediment erosion, transport and deposition within submarine channel bends is primarily controlled by the magnitude and direction of near bed flow. Flow around channel bends is characterized by a helical or spiralling structure. In rivers this helical flow is characterized by near-surface fluid moving toward the outer bank and near-bed fluid moving toward the inner bank. Following fierce debate over the last decade, it is now accepted that helical flow in submarine channel bends can display a variety of complex structures. Most importantly for understanding sediment transport, near bed flow can be directed towards the outer bank, which is in the opposite sense to in a river. The next challenge is to understand what the exact controls on the orientation of helical flow cells within submarine flows are, and their spatial evolution around bends. We present data from the Black Sea showing how the three-dimensional velocity and density of a submarine gravity current evolves at multiple cross sections as the flow travels around a bend. We use this data to calculate the magnitude, relative importance and interaction of centrifugal, coriolis and pressure gradients in controlling the structure of helical cells within the flow. We demonstrate the first order importance of radial pressure gradients, resulting from flow stratification, in controlling the structure of the flow as it travels around the bend.

Sumner, E. J.; Dorrell, R. M.; Peakall, J.; Darby, S. E.; Parsons, D. R.; Wynn, R.

2012-12-01

289

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

290

Growth history of Kilauea inferred from volatile concentrations in submarine-collected basalts  

USGS Publications Warehouse

Major-element and volatile (H2O, CO2, S) compositions of glasses from the submarine flanks of Kilauea Volcano record its growth from pre-shield into tholeiite shield-stage. Pillow lavas of mildly alkalic basalt at 2600-1900 mbsl on the upper slope of the south flank are an intermediate link between deeper alkalic volcaniclastics and the modern tholeiite shield. Lava clast glasses from the west flank of Papau Seamount are subaerial Mauna Loa-like tholeiite and mark the contact between the two volcanoes. H2O and CO2 in sandstone and breccia glasses from the Hilina bench, and in alkalic to tholeiitic pillow glasses above and to the east, were measured by FTIR. Volatile saturation pressures equal sampling depths (10 MPa = 1000 m water) for south flank and Puna Ridge pillow lavas, suggesting recovery near eruption depths and/or vapor re-equilibration during down-slope flow. South flank glasses are divisible into low-pressure (CO20.5 wt.%, S 1000-1700 ppm), and high-pressure groups (CO2 >40 ppm, S >???1000 ppm), corresponding to eruption ???sea level, at moderate water depths (300-1000 m) or shallower but in disequilibrium, and in deep water (> 1000 m). Saturation pressures range widely in early alkalic to strongly alkalic breccia clast and sandstone glasses, establishing that early Kilauea's vents spanned much of Mauna Loa's submarine flank, with some vents exceeding sea level. Later south flank alkalic pillow lavas expose a sizeable submarine edifice that grew concurrent with nearby subaerial alkalic eruptions. The onset of the tholeiitic shield stage is marked by extension of eruptions eastward and into deeper water (to 5500 m) during growth of the Puna Ridge. Subaerial and shallow water eruptions from earliest Kilauea show that it is underlain shallowly by Mauna Loa, implying that Mauna Loa is larger, and Kilauea smaller, than previously recognized.

Coombs, M.L.; Sisson, T.W.; Lipman, P.W.

2006-01-01

291

Topographic analysis of submarine cable failures offshore southwestern taiwan  

NASA Astrophysics Data System (ADS)

In 2006, there was large scale of the submarine cable failures offshore southern Taiwan right after the Pingtung Earthquake. Apparently the December 26 Pingtung Earthquake triggered submarine mass movements which generated turbidity currents in the submarine canyons and damaged cables lying across the canyons. In addition, the Typhoon Morakot on August 8-9, 2009 and the Jiashian Earthquake on March 4, 2010 also caused many submarine cable failures offshore southwestern Taiwan. The most of broken cable sites are along the axis of the Gaoping Submarine Canyon (GPSC) and Fangliao Submarine Canyon (FLSC), topography should be an important factor controlling transport processes of submarine mass movement. The cable broken sites indicate that there were submarine mass movement pass through. Therefore, the topographic factor of the cable broken sites can be the threshold to index submarine mass movement. And as, submarine cables are distributed widely offshore southwestern Taiwan, why only a total of 35 sites of submarine cable failures occurred in 2006, 2009 and 2010? We use bathymetry data, CHIRP (compressed high-intensity radar pulse) sonar profile data and the time series of the cable breakage to investigate the characteristics of submarine mass movement and to develop a model for the series of submarine cable failure. Using the Geographic Information System (GIS) software, we analyze the bathymetric data collected before the 35 sites of submarine cable failures offshore southwestern Taiwan. Applying the hydrology in GIS software, the flow movement could be derived from the factors of slope and aspect. We quantify the transport process of submarine mass movement and combine with the time series of the cable breakage to discuss the effect between submarine cable failures. Based on the CHIRP sonar data, we identified the distinct CHIRP echo character patterns after the submarine cable failures and classify the distinct CHIRP echo characters. Using the threshold of topographic factor to expect where will be potential area of submarine mass movement and evidence the result by CHIRP sonar profile data.

Hsia, Pei Cheng; Shine Liu, Char; Hsu, Ho Han

2013-04-01

292

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.

293

Haines - Scagway Submarine Cable Intertie Project, Haines to Scagway, Alaska; Final Technical and Construction Report  

Microsoft Academic Search

The Haines to Skagway submarine cable project is located n Taiya Inlet, at the north end of Lynn Canal, in Southeast Alaska. The cable is approximately 15 miles long, with three landings and splice vaults. The cable is 35 kV, 3-Phase, and armored. The cable interconnects the Goat Lake Hydro Project near Skagway with the community of Haines. Both communities

Alan See; Bennie N. Rinehart; Glen Marin

1998-01-01

294

From suspended particles to strata: The fate of terrestrial substances in the Gaoping (Kaoping) submarine canyon  

Microsoft Academic Search

The river–sea system consisting of the Gaoping (new spelling according to the latest government's directive, formerly spelled Kaoping) River (KPR), shelf, and Submarine Canyon (KPRSC) located off southern Taiwan is an ideal natural laboratory to study the source, pathway, transport, and fate of terrestrial substances. In 2004 during the flood season of the KPR, a system-wide comprehensive field experiment was

James T. Liu; Jia-Jang Hung; Hui-Ling Lin; Chih-An Huh; Chon-Lin Lee; Ray T. Hsu; Ya-Wen Huang; Joel C. Chu

2009-01-01

295

Recent Results From Seafloor Instruments at the NeMO Observatory, Axial Volcano, Juan de Fuca Ridge  

NASA Astrophysics Data System (ADS)

NeMO is a seafloor observatory at Axial Seamount, an active submarine volcano located on the Juan de Fuca Ridge (JdFR) in the NE Pacific. Axial Volcano was chosen for NeMO because it has the largest magma supply on the JdFR, and is therefore the best place to study volcanic events and the perturbations they cause to pre-existing hydrothermal systems. In fact, Axial volcano erupted in January 1998 and initially our field efforts were focused on mapping the new lava flows and documenting the impact of the eruption on the hydrothermal vents and biological communities. Since then, our emphasis has gradually shifted to long-term geophysical and geochemical monitoring of the volcano in anticipation of its next eruption. Recent results from seafloor monitoring instruments and recent geologic mapping will be presented, including the following: (1) NeMO Net, a state-of-the-art, two-way communication system currently deployed at Axial, which uses a moored surface buoy to link three instruments on the seafloor in near real-time to the internet. The buoy communicates with the seafloor instruments via acoustic modems and relays data to and from shore via the Orbcomm and Iridium satellite systems. The seafloor instruments include two Remote Access Samplers (RAS) located at two hydrothermal vents in the ASHES vent field, and a Bottom Pressure Recorder (BPR) located near the center of the caldera. The RAS samplers monitor temperature and chemistry at the vents and can take 48 fluid and particle samples over a year, but can also be commanded from shore to take a sample at any time in response to detected seismic or volcanic events. The BPR is monitoring vertical motion of the seafloor, looking for sudden inflation or deflation events that may signal the onset of an eruption or intrusion. Data from the three instruments is displayed on the web at http://www.pmel.noaa.gov/vents/nemo/realtime/. (2) Data from a RAS sampler that was deployed at Cloud vent in Axial caldera between 2001-2002. The RAS collected a time-series of temperature readings as well as hydrothermal fluid and particle samples from the vent over a year. (3) Data from a BPR that was deployed at the center of the caldera between 2000-2002, to monitor for sudden inflation or deflation events. (4) Data from annually repeated precise pressure measurements made from an ROV at a network of five seafloor benchmarks located inside and outside the caldera. These measurements look for any gradual volcanic inflation that would not be detectable with BPR instruments due to their long-term drift. (5) Previously recorded BPR data collected during the 1998 eruption by an instrument that became caught in the 1998 lava flow will also be examined for its implications for models of submarine lava flow emplacement and lava pillar formation.

Chadwick, W. W.; Butterfield, D. A.; Embley, R. W.; Meinig, C.; Stalin, S. E.; Nooner, S. L.; Zumberge, M. A.; Fox, C. G.

2002-12-01

296

Catalog of earthquake hypocenters at Alaskan volcanoes: January 1, 2000 through December 31, 2001  

USGS Publications Warehouse

The Alaska Volcano Observatory (AVO), a cooperative program of the U.S. Geological Survey, the Geophysical Institute of the University of Alaska Fairbanks, and the Alaska Division of Geological and Geophysical Surveys, has maintained seismic monitoring networks at potentially active volcanoes in Alaska since 1988 (Power and others, 1993; Jolly and others, 1996; Jolly and others, 2001). The primary objectives of this program are the seismic surveillance of active, potentially hazardous, Alaskan volcanoes and the investigation of seismic processes associated with active volcanism. This catalog reflects the status and evolution of the seismic monitoring program, and presents the basic seismic data for the time period January 1, 2000, through December 31, 2001. For an interpretation of these data and previously recorded data, the reader should refer to several recent articles on volcano related seismicity on Alaskan volcanoes in Appendix G. The AVO seismic network was used to monitor twenty-three volcanoes in real time in 2000-2001. These include Mount Wrangell, Mount Spurr, Redoubt Volcano, Iliamna Volcano, Augustine Volcano, Katmai Volcanic Group (Snowy Mountain, Mount Griggs, Mount Katmai, Novarupta, Trident Volcano, Mount Mageik, Mount Martin), Aniakchak Crater, Pavlof Volcano, Mount Dutton, Isanotski Peaks, Shishaldin Volcano, Fisher Caldera, Westdahl Peak, Akutan Peak, Makushin Volcano, Great Sitkin Volcano, and Kanaga Volcano (Figure 1). AVO located 1551 and 1428 earthquakes in 2000 and 2001, respectively, on and around these volcanoes. Highlights of the catalog period (Table 1) include: volcanogenic seismic swarms at Shishaldin Volcano between January and February 2000 and between May and June 2000; an eruption at Mount Cleveland between February and May 2001; episodes of possible tremor at Makushin Volcano starting March 2001 and continuing through 2001, and two earthquake swarms at Great Sitkin Volcano in 2001. This catalog includes: (1) earthquake origin times, hypocenters, and magnitudes with summary statistics describing the earthquake location quality; (2) a description of instruments deployed in the field and their locations; (3) a description of earthquake detection, recording, analysis, and data archival systems; (4) station parameters and velocity models used for earthquake locations; (5) a summary of daily station usage throughout the catalog period; and (6) all HYPOELLIPSE files used to determine the earthquake locations presented in this report.

Dixon, James P.; Stihler, Scott D.; Power, John A.; Tytgat, Guy; Estes, Steve; Moran, Seth C.; Paskievitch, John; McNutt, Stephen R.

2002-01-01

297

Boron-rich mud volcanoes of the Black Sea region: modern analogues to ancient sea-floor tourmalinites associated with Sullivan-type Pb-Zn deposits?  

USGS Publications Warehouse

Large submarine mud volcanoes in the abyssal part of the Black Sea south of the Crimean Peninsula are similar in many respects to synsedimentary mud volcanoes in the Mesoproterozoic Belt-Purcell basin. One of the Belt-Purcell mud volcanoes directly underlies the giant Sullivan Pb-Zn-Ag deposit in southeastern British Columbia. Footwall rocks to the Sullivan deposit comprise variably tourmalinized siltstone, conglomerate, and related fragmental rock; local thin pyrrhotite-rich and spessartine-quartz beds are interpreted as Fe and Fe-Mn exhalites, respectively. Analogous Fe- and Mn-rich sediments occur near the abyssal Black Sea mud volcanoes. Massive pyrite crusts and associated carbonate chimneys discovered in relatively shallow waters (~200 m depth) west of the Crimean Peninsula indicate an active sea-floor-hydrothermal system. Subaerial mud volcanoes on the Kerch and Taman Peninsulas (~100 km north of the abyssal mud volcanoes) contain saline thermal waters that locally have very high B contents (to 915 mg/L). These data suggest that tourmalinites might be forming in or near submarine Black Sea mud volcanoes, where potential may also exist for Sullivan-type Pb-Zn mineralization.

Slack, J. F.; Turner, R. J. W.; Ware, P. L. G.

1998-01-01

298

Volcanic Explosions, Seismicity, and Debris from the West and North Mata Volcano Complex, NE Lau Basin  

NASA Astrophysics Data System (ADS)

The discovery of the explosively erupting deep-ocean West Mata volcano in the northeast Lau Basin offers an unprecedented opportunity for in situ and near-field studies of the hydroacoustic wavefield produced by a submarine arc volcano, as well as the relationship between gas-driven explosions and the formation of volcanic-hydrothermal plumes. From December 2009 to April 2010, we re-initiated acoustic monitoring of the West Mata system by deploying four hydrophone moorings in a diamond-shaped geometry encompassing the summit and a set of nearby volcanic edifices known as the North Matas. Recent water column surveys over the North Matas found intense volcanic plumes suggesting that one or more of these volcanoes may be in an active eruption phase similar to West Mata. Each mooring contained a single sound-channel moored hydrophone (~1000 m depth) with a sample-rate of 1 kHz. The southern mooring in the array also included two optical backscatter and temperature sensors (MAPRs) attached to the mooring line (at 1800 m (data lost due to a battery failure) and 2250 m (~300 mab) depth) to detect plumes of volcanic debris that detach from the flank of West Mata. The acoustic record shows that West Mata volcano was continually erupting during the 5-month period of the experiment, producing broadband explosions every few seconds and long episodes of both mono- and poly-chromatic volcanic tremor. The MAPR record shows at least four major and several minor events, lasting from days to >week, that may correspond to debris flows. In most cases these episodes begin with a turbidity spike that slowly decreases while also fluctuating between elevated and ambient levels with the semidiurnal tides, as indicated by the temperature record. This linked temperature-turbidity fluctuation requires the events to be thin (<~100 m?) lenses that vertically oscillate around the MAPR depth while dissipating. High turbidity values (0.15-5 NTU) in some events imply these debris flows regularly move substantial quantities of material downslope. Source locations derived from the first 700 explosions recorded (~12 hrs) are near the northwest summit of West Mata, consistent with the locations of previously mapped eruption vents. Earthquake (T-phase) locations derived to date show dozens of events focused at the northernmost North Mata volcano as well as hundreds of earthquakes from throughout the region. A contemporaneous Lau Basin hydrophone experiment showed that West Mata explosions and tremor can be detected ~600 km to the south, illustrating that West Mata is a significant, continuous source of seismo-acoustic energy in the region and offers a rare chance to ground-truth the sounds of deep-ocean eruptions since they were originally recognized on far-field military hydrophones during the 1950s.

Dziak, R. P.; Bohnenstiehl, D. R.; Baker, E. T.; Matsumoto, H.; Haxel, J.; Walker, S.; Fowler, M.

2010-12-01

299

Infrasound produced by degassing of shield-volcanoes: Hawaii and Galapagos, and its potential for atmospheric monitoring  

E-print Network

Infrasound produced by degassing of shield-volcanoes: Hawaii and Galapagos, and its potential. Volcanoes located on hotspots (e.g.: Hawaii, Galapagos) usually erupt ef- fusively releasing significant (2010). "Infrasonic harmonic tremor and degassing bursts from Halema'uma'u Crater, Kilauea Volcano

Geist, Dennis

300

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

301

Catalog of earthquake hypocenters at Alaskan volcanoes: January 1 through December 31, 2002  

USGS Publications Warehouse

The Alaska Volcano Observatory (AVO), a cooperative program of the U.S. Geological Survey, the Geophysical Institute of the University of Alaska Fairbanks, and the Alaska Division of Geological and Geophysical Surveys, has maintained seismic monitoring networks at historically active volcanoes in Alaska since 1988 (Power and others, 1993; Jolly and others, 1996; Jolly and others, 2001; Dixon and others, 2002). The primary objectives of this program are the seismic monitoring of active, potentially hazardous, Alaskan volcanoes and the investigation of seismic processes associated with active volcanism. This catalog presents the basic seismic data and changes in the seismic monitoring program for the period January 1, 2002 through December 31, 2002. Appendix G contains a list of publications pertaining to seismicity of Alaskan volcanoes based on these and previously recorded data. The AVO seismic network was used to monitor twenty-four volcanoes in real time in 2002. These include Mount Wrangell, Mount Spurr, Redoubt Volcano, Iliamna Volcano, Augustine Volcano, Katmai Volcanic Group (Snowy Mountain, Mount Griggs, Mount Katmai, Novarupta, Trident Volcano, Mount Mageik, Mount Martin), Aniakchak Crater, Mount Veniaminof, Pavlof Volcano, Mount Dutton, Isanotski Peaks, Shishaldin Volcano, Fisher Caldera, Westdahl Peak, Akutan Peak, Makushin Volcano, Great Sitkin Volcano, and Kanaga Volcano (Figure 1). Monitoring highlights in 2002 include an earthquake swarm at Great Sitkin Volcano in May-June; an earthquake swarm near Snowy Mountain in July-September; low frequency (1-3 Hz) tremor and long-period events at Mount Veniaminof in September-October and in December; and continuing volcanogenic seismic swarms at Shishaldin Volcano throughout the year. Instrumentation and data acquisition highlights in 2002 were the installation of a subnetwork on Okmok Volcano, the establishment of telemetry for the Mount Veniaminof subnetwork, and the change in the data acquisition system to an EARTHWORM detection system. AVO located 7430 earthquakes during 2002 in the vicinity of the monitored volcanoes. This catalog includes: (1) a description of instruments deployed in the field and their locations; (2) a description of earthquake detection, recording, analysis, and data archival systems; (3) a description of velocity models used for earthquake locations; (4) a summary of earthquakes located in 2002; and (5) an accompanying UNIX tar-file with a summary of earthquake origin times, hypocenters, magnitudes, and location quality statistics; daily station usage statistics; and all HYPOELLIPSE files used to determine the earthquake locations in 2002.

Dixon, James P.; Stihler, Scott D.; Power, John A.; Tytgat, Guy; Moran, Seth C.; Sánchez, John; Estes, Steve; McNutt, Stephen R.; Paskievitch, John

2003-01-01

302

Mauna Loa's submarine western flank: Landsliding, deep volcanic spreading, and hydrothermal alteration  

NASA Astrophysics Data System (ADS)

Four new remotely operated vehicle dives carried out by Monterey Bay Aquarium Research Institute (MBARI) reveal a heterogeneous distribution of lithologies and compositions along a transect across the submarine west flank of Mauna Loa, from the outer scarp of the frontal bench to the upper flank. The frontal bench is composed predominantly of volcaniclastic sediments, ranging from very fine-grained monomictic hyaloclastites to coarse-grained, compositionally mixed volcaniclastic breccias. The predominance of subaerially derived clasts suggests accumulations of landslide deposits, probably emplaced along a regional shear plane preserved in cataclastic breccias with local foliations and grain trails. Repeated packages of inversely graded strata are interpreted to reflect thrust imbrication of the resulting volcaniclastic apron during volcanic spreading of Mauna Loa's western flank, similar to that now documented along K?lauea's south flank. Many of the rocks from the bench show evidence for alteration, ranging from low-grade burial diagenesis to higher-grade hydrothermal alteration, including phases never before observed in submarine Hawaiian rocks, including epidote, talc, sphene, and corrensite. Alteration is concentrated in deformed zones, denoting pathways for fluid flow into or out of the volcanic edifice. Formed at depth, the altered rocks were subsequently transported along low-angle thrust faults into the bench and exposed along high-angle fractures and faults. The upper submarine flanks are draped by subaerially erupted, submarine emplaced pillow lavas and interbedded hyaloclastites, generated by shoreline-crossing lava flows. Basalt glasses indicate Mauna Loa origin but imply earlier compositions than present-day lavas, consistent with Ar-Ar ages suggesting eruption 0.28 ± 0.10 Ma. Late stage detachment of a nearshore slump produced the '?lika 2 debris avalanche that broke through the frontal bench, perhaps portending the evolution of the active Hilina slump now present on K?lauea volcano's south flank.

Morgan, Julia K.; Clague, David A.; Borchers, Deanna C.; Davis, Alicé S.; Milliken, Kitty L.

2007-05-01

303

Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2007  

USGS Publications Warehouse

Between January 1 and December 31, 2007, AVO located 6,664 earthquakes of which 5,660 occurred within 20 kilometers of the 33 volcanoes monitored by the Alaska Volcano Observatory. Monitoring highlights in 2007 include: the eruption of Pavlof Volcano, volcanic-tectonic earthquake swarms at the Augustine, Illiamna, and Little Sitkin volcanic centers, and the cessation of episodes of unrest at Fourpeaked Mountain, Mount Veniaminof and the northern Atka Island volcanoes (Mount Kliuchef and Korovin Volcano). This catalog includes descriptions of : (1) locations of seismic instrumentation deployed during 2007; (2) earthquake detection, recording, analysis, and data archival systems; (3) seismic velocity models used for earthquake locations; (4) a summary of earthquakes located in 2007; and (5) an accompanying UNIX tar-file with a summary of earthquake origin times, hypocenters, magnitudes, phase arrival times, location quality statistics, daily station usage statistics, and all files used to determine the earthquake locations in 2007.

Dixon, James P.; Stihler, Scott D.; Power, John A.

2008-01-01

304

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

305

Eruption of a deep-sea mud volcano triggers rapid sediment movement.  

PubMed

Submarine mud volcanoes are important sources of methane to the water column. However, the temporal variability of their mud and methane emissions is unknown. Methane emissions were previously proposed to result from a dynamic equilibrium between upward migration and consumption at the seabed by methane-consuming microbes. Here we show non-steady-state situations of vigorous mud movement that are revealed through variations in fluid flow, seabed temperature and seafloor bathymetry. Time series data for pressure, temperature, pH and seafloor photography were collected over 431 days using a benthic observatory at the active Håkon Mosby Mud Volcano. We documented 25 pulses of hot subsurface fluids, accompanied by eruptions that changed the landscape of the mud volcano. Four major events triggered rapid sediment uplift of more than a metre in height, substantial lateral flow of muds at average velocities of 0.4?m per day, and significant emissions of methane and CO2 from the seafloor. PMID:25384354

Feseker, Tomas; Boetius, Antje; Wenzhöfer, Frank; Blandin, Jerome; Olu, Karine; Yoerger, Dana R; Camilli, Richard; German, Christopher R; de Beer, Dirk

2014-01-01

306

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

307

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

308

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.

309

Open architecture framework for improved early stage submarine design  

E-print Network

Could transparency between current disparate methods improve efficiency in early stage submarine design? Does the lack of transparency between current design methods hinder the effectiveness of early stage submarine design? ...

Sewell, Eli A. (Eli Anthony)

2010-01-01

310

Submarine intraplate volcanism in the South Pacific: Geological setting and petrology of the society and the austral regions  

NASA Astrophysics Data System (ADS)

The southeastern prolongations of the Society and Austral islands volcanic chains are terminated by several recent submarine volcanoes (300-3800 m in height) built on irregularly shaped crustal swells or bulges (3600-3950 m in depth). The crustal swells (about 100 km in width) is bounded by deeper abyssal hill regions (>4000 m in depth) where old volcanoes with thick Fe-Mn coatings are encountered. The rocks sampled on this ancient oceanic crust are depleted mid-ocean ridge basalts (MORBs) similar to modem volcanics encountered on the East Pacific Rise. The volcanics of the Society hot spot consist of ankaramites, picrites, alkali-basalts, basanites, tephrites, and trachytes. Highly vesiculated pillow lavas show a wide compositional range in their large ion lithophile elements (LILE) (K2O=1-4%, Nb=25-80 ppm, Zr=200-400 ppm, Ba=300-840 ppm) and compatible element variations (Mg #=40-70, Ni=80-500 ppm), and low Zr/Nb ratios (5-8). Low-K tholeiites (K2O<0.15%, Nb=3-6 ppm, Zr=56-74 ppm, Zr/Nb=10-25), also found associated with alkali-basalts and basanites from recent volcanoes, are believed to have been exposed during rejuvenation of ancient edifices. The Macdonald volcano (Austral island chain), with a base diameter of 45 km at a depth of 3850 m, was sampled from its summital area (<100 m in depth) down to 2000 m in depth. Highly vesiculated pillow lavas, volcanic ejecta, and accidental rock debris recovered differ from those of the Society hot spot volcanoes by their lower Zr/Nb (3-5), Rb/Sr (<0.045), and (Ce/Yb)N (5-10) ratios and their lower Ba (350-400 ppm) and light rare eath elements (LREE) content. The accidental rock debris (metabasalt, metadolerite, isotropic gabbros, and metagabbros) were scattered during phreatic explosive events on the flanks of the Macdonald volcano. Volcanic ejecta of basanite lapilli partially covering the accidental rock debris were formed during more recent phreatomagmatic explosions. The most undersaturated glassy pillow lava encountered in the Austral hot spot is a normative nepheline-rich rock with incipient amphibole recovered from an ancient seamount (Ra seamount) located at about 100 km northwest of the Macdonald volcano. Based on their high LREE content and low Zr/Nb (3-8) and on their high (Ce/Yb)N (5-20) (5-20), (La/Sm)N (1-5), and (La/Lu)N (7-40) ratios with respect to the MORBs, it is speculated that the intraplate volcanics (Austral and Society volcanoes) have originated from the partial melting of mixed mantle sources made up of lherzolite (MORB mantle source) and another complementary source enriched in LREEs and Nb. A recycling of continental crust or pelagic sediments in subduction zones represents a possible supply of LREEs but not of Nb. Continental metasomatized peridotites and oceanic amphibole-peridotites such as Zabargad and St. Paul's Rocks samples were proposed as potential mantle sources for intraplate magmas. Using modal and chemical (Zr, Nb, Ce, and Yb) data available in the literature, a model of partial melting of a composite mantle, obtained by mixing homblendite (Queensland's xenoliths) and spinel-lherzolites, was tested as being a possible origin for the studied rocks. This model provides adequate Zr/Nb ratios and suggests that the Society mantle source contained smaller amount of homblendite (<5 wt %) and underwent lower degree of partial melting (about 5 %) than that of the Austral hot spot (10 wt % and 10-20% respectively). However, the complementary mantle source in the Society hot spot requires larger amount of LREEs than it is necessary for the Austral volcanoes. While the Zabargad amphibole-peridotites are reasonable candidates, the metasomatized peridotite xenoliths from continental alkali-basalts and the amphibole-peridotite mylonites from St. Paul's Rocks are more suitable as a potential source for the Society parental melts enriched in Ce and La. Hence the intraplate lava compositions could be the result of recycling and remelting of an ancient oceanic upper mantle which is partially metasomatized during its lateral transfer off

Hekinian, Roger; Bideau, Daniel; Stoffers, Peter; Cheminee, Jean Louis; Muhe, Richard; Puteanus, Doris; Binard, Nicolas

1991-02-01

311

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

312

Newly recognized submarine slide complexes in the southern California Bight  

NASA Astrophysics Data System (ADS)

New high-resolution bathymetric and seismic-reflection surveys have imaged large (<0.5 km3) submarine landslides offshore southern California that have not been previously recognized in the Borderland. The new data show several large slides or slide complexes that include: 1) a slide complex consisting of numerous (>7) individual overlapping slides along the western margin of Santa Cruz Basin (SCB slide); 2) a series of slumps and slide scars on the slope south of San Pedro shelf (SPS slide); and 3) a slope failure along the shelf edge in northern San Diego County, termed the Del Mar slide. The SCB slide complex extends for 30 km along the western slope of Santa Cruz Basin, with debris lobes extending 5-8 km into the basin. Head scarps of some of these slides are 50-75 m high. The SPS slide complex also appears to consist of multiple slides, which roughly parallel the Palos Verdes Fault and the San Gabriel Canyon submarine channel on the shelf edge and slope south of San Pedro shelf. Slide deposits associated with this complex are only partially mapped due to limited high-resolution bathymetric coverage, but extend to the south in the area SW of Lasuen Knoll. Seismic-reflection profiles show that some of these deposits are up to 20 m thick. The Del Mar slide is located about 10 km north of La Jolla Canyon and extends about 6 km along the shelf edge. The head scarp lies along the trend of a branch of the Rose Canyon Fault Zone. Radiocarbon ages of sediment overlying this slide indicate the Del Mar slide is approximately 12-16 ka. These large slide complexes have several characteristics in common. Nearly all occur in areas of tectonic uplift. All of the complexes show evidence of recurrent slide activity, exhibiting multiple headwall scarps and debris lobes, and where available, high-resolution seismic-reflection profiles of these slide areas provide evidence of older, buried mass transport deposits. Assuming typical sedimentation rates, the recurrence interval of major slide events appears to be on the order of tens of thousands of years. Most of the slide complexes do not appear to be located in areas of high sediment input. The SCB and Del Mar slides are in areas receiving relatively small terrestrial sediment input from fluvial sources, as are most other previously recognized submarine slides in the Borderland. Only the SPS slide, which lies adjacent to the San Gabriel Canyon submarine channel, is associated with a significant fluvial sediment source.

Conrad, J. E.; Lee, H. J.; Edwards, B. D.; McGann, M.; Sliter, R. W.

2012-12-01

313

Geochemical constraints on the evolution of mafic and felsic rocks in the Bathani volcanic and volcano-sedimentary sequence of Chotanagpur Granite Gneiss Complex  

NASA Astrophysics Data System (ADS)

The Bathani volcanic and volcano-sedimentary (BVS) sequence is a volcanic and volcano-sedimentary sequence, best exposed near Bathani village in Gaya district of Bihar. It is located in the northern fringe of the Chotanagpur Granite Gneiss Complex (CGGC). The volcano-sedimentary unit comprises of garnet-mica schist, rhyolite, tuff, banded iron formation (BIF) and chert bands with carbonate rocks as enclaves within the rhyolite and the differentiated volcanic sequence comprises of rhyolite, andesite, pillow basalt, massive basalt, tuff and mafic pyroclasts. Emplacement of diverse felsic and mafic rocks together testifies for a multi-stage and multi-source magmatism for the area. The presence of pillow basalt marks the eruption of these rocks in a subaqueous environment. Intermittent eruption of mafic and felsic magmas resulted in the formation of rhyolite, mafic pyroclasts, and tuff. Mixing and mingling of the felsic and mafic magmas resulted in the hybrid rock andesite. Granites are emplaced later, cross-cutting the volcanic sequence and are probably products of fractional crystallization of basaltic magma. The present work characterizes the geochemical characteristics of the magmatic rocks comprising of basalt, andesite, rhyolite, tuff, and granite of the area. Tholeiitic trend for basalt and calc-alkaline affinities of andesite, rhyolite and granite is consistent with their generation in an island arc, subduction related setting. The rocks of the BVS sequence probably mark the collision of the northern and southern Indian blocks during Proterozoic period. The explosive submarine volcanism may be related to culmination of the collision of the aforementioned blocks during the Neoproterozoic (1.0 Ga) as the Grenvillian metamorphism is well established in various parts of CGGC.

Saikia, Ashima; Gogoi, Bibhuti; Ahmad, Mansoor; Ahmad, Talat

2014-06-01

314

Investigating the Source Mechanism of Long Period Volcano-Seismic Events Recorded in 2009 at Turrialba Volcano, Costa Rica  

NASA Astrophysics Data System (ADS)

Long-period (LP) seismic events (with energy concentrated between frequencies of 0.5 to 5Hz) were recorded on Turrialba volcano, Costa Rica during a field experiment from March to September 2009. This type of event has been recorded at many volcanoes across the world and in some instances swarms of LP events have signalled the onset of a volcanic eruption. The most widely accepted models for the source mechanism of these events attribute them to resonance within a fluid-filled cavity within the volcano, due to the similarity between waveforms of different LP events suggesting a non-destructive, repeatable source. Therefore inverting recorded LP events for the source mechanism can provide valuable information about the internal structure and dynamics of the volcano. Turrialba volcano is an ideal volcano on which to carry out this experiment because of the relatively easy and safe access to the volcano summit. This is important because it has been shown in previous studies that seismometers should be located in a dense network across the summit of a volcano (above the source), in order to gain as accurate a source inversion as possible. Activity at Turrialba volcano has increased dramatically in recent years with high levels of seismic and fumerolic activity. In this study 16 broadband seismometers were deployed on the summit and flanks of the volcano, including a 5 station array that was in operation for ~2 weeks. The data from the field experiment has been analysed and the LP events found. These were sorted into five families based on their correlations. The source locations have been calculated using a variety of methods including first picks, array analysis and a gridsearch implemented while carrying out moment tensor inversion. The LP events are located below the summit craters at shallow depth. These locations were then used to carry out full waveform moment tensor inversion to constrain the source mechanism, using a full waveform method to calculate the Green's functions. From unconstrained inversion, the optimum source for LP events is a crack mechanism. Constrained inversion will be carried out to better constrain the orientation of the crack. This will lead to a much greater understanding of the magmatic and hydrothermal systems within Turrialba volcano and better constraints on LP event source mechanism within volcanoes in general.

Eyre, T. S.; Bean, C. J.; O'Brien, G. S.; Martini, F.; Mora, M. M.; Pacheco, J. F.; Soto, G. J.

2011-12-01

315

Introduction Fresh or brackish ground water in submarine environ-  

E-print Network

hydrodynamic phenomena (i.e., submarine ground water discharge) along the U.S. Atlantic margin are attractingIntroduction Fresh or brackish ground water in submarine environ- ments has been shown to exist the presence of submarine fresh water as far as 100 km from shore (Manheim 1967). Subsequently, most

Krantz, David

316

Theory of NURBS and its application in submarine hull modeling  

Microsoft Academic Search

Submarine hull consists of complicated spatial freeform surface. During the development of submarine design, the design of its body is the important factor which will decide whether this design is successful or not. But the design of complex curve and curve surface is the core in the CAD of submarine body. It is the key skill to speed up the

Zhang Jing; He Qiwei; Feng Shaowei

2010-01-01

317

36. VIEW OF CUPOLA, SUBMARINE ESCAPE TRAINING TANK, SHOWING ROVING ...  

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

36. VIEW OF CUPOLA, SUBMARINE ESCAPE TRAINING TANK, SHOWING ROVING RESCUE BELL SUSPENDED ABOVE TANK, WITH TWO-LOCK RECOMPRESSION CHAMBER AT REAR, LOOKING WEST. Photo taken after installation of recompression chamber in 1956. - U.S. Naval Submarine Base, New London Submarine Escape Training Tank, Albacore & Darter Roads, Groton, New London County, CT

318

35. INTERIOR VIEW OF EQUIPMENT HOUSE, SUBMARINE ESCAPE TRAINING TANK, ...  

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

35. INTERIOR VIEW OF EQUIPMENT HOUSE, SUBMARINE ESCAPE TRAINING TANK, PRIOR TO ENLARGEMENT OF ROOM AND INSTALLATION OF TRIPLE-LOCK RECOMPRESSION CHAMBER IN 1957 - U.S. Naval Submarine Base, New London Submarine Escape Training Tank, Albacore & Darter Roads, Groton, New London County, CT

319

31. VIEW OF SUBMARINE ESCAPE TRAINING TANK DURING CONSTRUCTION OF ...  

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

31. VIEW OF SUBMARINE ESCAPE TRAINING TANK DURING CONSTRUCTION OF THE ELEVATOR AND PASSAGEWAYS TO THE 18- AND 50-FOOT LOCKS AND CUPOLA 1932 - U.S. Naval Submarine Base, New London Submarine Escape Training Tank, Albacore & Darter Roads, Groton, New London County, CT

320

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

NSDL National Science Digital Library

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

Fries-Gaither, Jessica

321

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

322

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

323

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

324

Geomorphic process fingerprints in submarine canyons  

USGS Publications Warehouse

Submarine canyons are common features of continental margins worldwide. They are conduits that funnel vast quantities of sediment from the continents to the deep sea. Though it is known that submarine canyons form primarily from erosion induced by submarine sediment flows, we currently lack quantitative, empirically based expressions that describe the morphology of submarine canyon networks. Multibeam bathymetry data along the entire passive US Atlantic margin (USAM) and along the active central California margin near Monterey Bay provide an opportunity to examine the fine-scale morphology of 171 slope-sourced canyons. Log–log regression analyses of canyon thalweg gradient (S) versus up-canyon catchment area (A) are used to examine linkages between morphological domains and the generation and evolution of submarine sediment flows. For example, canyon reaches of the upper continental slope are characterized by steep, linear and/or convex longitudinal profiles, whereas reaches farther down canyon have distinctly concave longitudinal profiles. The transition between these geomorphic domains is inferred to represent the downslope transformation of debris flows into erosive, canyon-flushing turbidity flows. Over geologic timescales this process appears to leave behind a predictable geomorphic fingerprint that is dependent on the catchment area of the canyon head. Catchment area, in turn, may be a proxy for the volume of sediment released during geomorphically significant failures along the upper continental slope. Focused studies of slope-sourced submarine canyons may provide new insights into the relationships between fine-scale canyon morphology and down-canyon changes in sediment flow dynamics.

Brothers, Daniel S.; ten Brink, Uri S.; Andrews, Brian D.; Chaytor, Jason D.; Twichell, David C.

2013-01-01

325

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

326

A model for the submarine depthkeeping team  

NASA Technical Reports Server (NTRS)

The most difficult task the depthkeeping team must face occurs during periscope-depth operations during which they may be required to maintain a submarine several hundred feet long within a foot of ordered depth and within one-half degree of ordered pitch. The difficulty is compounded by the facts that wave generated forces are extremely high, depth and pitch signals are very noisy and submarine speed is such that overall dynamics are slow. A mathematical simulation of the depthkeeping team based on the optimal control models is described. A solution of the optimal team control problem with an output control restriction (limited display to each controller) is presented.

Ware, J. R.; Best, J. F.; Bozzi, P. J.; Kleinman, D. W.

1981-01-01

327

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.

328

A preliminary seismic study of Taal Volcano, Luzon Island Philippines  

NASA Astrophysics Data System (ADS)

The very active Taal Volcano lies in the southern part of Luzon Island only 60 km from Manila, the capital of the Philippines. In March 2008 we deployed a temporary seismic network around Taal that consisted of 8 three-component short period seismometers. This network recorded during the period from March to November 2008 about 1050 local events. In the early data processing stages, unexpected linear drifting of clock time was clearly identified for a number of stations. The drifting rates of each problematic station were determined and the errors were corrected before further processing. Initial location of each event was derived by manually picked P-/S-phases arrival times using HYPO71 and a general velocity model based on AK135. Since the velocity structure beneath Taal is essentially unknown, we used travel times of 338 well-located events in order to derive a minimum 1D velocity model using VELEST. The resulting locations show that most events occurred at the shallow depth beneath the Taal Volcano, and two major earthquake groups were noticed, with one lying underneath the western shore of Taal lake and the other one spread around the eastern flank of the Taal Volcano. Since there is no reported volcano activities during the operation period of our seismic array, we are still not confident to interpret these findings in terms of other natures of volcano at the current stage. However, our work represents an important pioneer step towards other more advanced seismic studies in Taal Volcano.

You, S.-H.; Gung, Y.; Lin, C.-H.; Konstantinou, K. I.; Chang, T.-M.; Chang, E. T. Y.; Solidum, R.

2013-03-01

329

Estimation of submarine mass failure probability from a sequence of deposits with age dates  

USGS Publications Warehouse

The empirical probability of submarine mass failure is quantified from a sequence of dated mass-transport deposits. Several different techniques are described to estimate the parameters for a suite of candidate probability models. The techniques, previously developed for analyzing paleoseismic data, include maximum likelihood and Type II (Bayesian) maximum likelihood methods derived from renewal process theory and Monte Carlo methods. The estimated mean return time from these methods, unlike estimates from a simple arithmetic mean of the center age dates and standard likelihood methods, includes the effects of age-dating uncertainty and of open time intervals before the first and after the last event. The likelihood techniques are evaluated using Akaike’s Information Criterion (AIC) and Akaike’s Bayesian Information Criterion (ABIC) to select the optimal model. The techniques are applied to mass transport deposits recorded in two Integrated Ocean Drilling Program (IODP) drill sites located in the Ursa Basin, northern Gulf of Mexico. Dates of the deposits were constrained by regional bio- and magnetostratigraphy from a previous study. Results of the analysis indicate that submarine mass failures in this location occur primarily according to a Poisson process in which failures are independent and return times follow an exponential distribution. However, some of the model results suggest that submarine mass failures may occur quasiperiodically at one of the sites (U1324). The suite of techniques described in this study provides quantitative probability estimates of submarine mass failure occurrence, for any number of deposits and age uncertainty distributions.

Geist, Eric L.; Chaytor, Jason D.; Parsons, Thomas E.; ten Brink, Uri S.

2013-01-01

330

Identification of topographic fingerprints of eruption environments: Geomorphometric evidence from volcanoes of the Reykjanes Peninsula, Iceland  

NASA Astrophysics Data System (ADS)

The geomorphometry of volcanoes provides important information on the geologic evolution of planets. Therefore, constraining the topographic characteristics of terrestrial volcanoes is an important step for comparative planetology. Here we resolve geomorphometric fingerprints of volcanic edifices formed in subaerial, submarine and subglacial environments by focusing on volcanoes of the Reykjanes Peninsula, Iceland. The Reykjanes Volcanic Belt connects the Reykjanes midoceanic spreading ridge with the Western volcanic zone. It consists of four volcanic systems that display a variety of pristine Quaternary submarine, subglacial and subaerial volcanic edifices. 35 edifices were chosen for quantitative characterization using the IS 50V digital elevation model (20m/pixel). The edifice boundaries were delimited by concave breaks in slope around their bases and edifices were grouped according to slope, size and shape. A division based on slope values proves successful in discriminating subaerial edifices from subglacial and submarine edifices. Subaerial shields have average slopes between 2.8°-6.5°, which is at least 6° less than the average slopes of submarine and subglacial edifices. Moreover, the shields can be sub-divided into tholeite (2.8°-4.6°) and picrite (5.3°-6.5°) shields based on average slope. Submarine and subglacial edifices cannot be distinguished from each other by average slopes, and were grouped together in a submarine and subglacial class. This class was sub-divided into 3 groups based on their volume and suggests an evolutionary growth trend starting with small elliptical, linear ridges (~2*10-3-7*10-3 km3) to flat topped, table-shaped mountains (~100*10-3 -640*10-3 km3), with an intermediate growth stage (~10*10-3 - 80*10-3 km3) of very variable and irregular complex edifices. Further analysis of topographic profiles, slope frequency and elevational slope development, show that it is possible to resolve individual land elements based on break in slope, such as lava cap, hyaloclastite apron, hyaloclastite slope and hyaloclastite summit. The boundary between hyaloclastite breccia and lava cap represents a passage zone that marks late-stage subaerial lava-fed deltas and is clearly defined by convex breaks in slope. Large elevation changes in the passage zone is diagnostic of lava deltas emplaced in a glacial environment, and thus mapping of elevation changes of convex breaks in slope is a potential tool for distinguishing big table-shaped volcanic edifices emplaced in a submarine or subglacial environment. This study shows that volcano morphometry can be used to obtain information on processes operating during volcano construction, its eruption environment and the resulting evolutionary growth trends. A significant advantage of this method is its application for remote and inaccessible areas such as submarine or subglacial environments as well as extraterrestrial planets. Moreover, the break in slope delimitation of edifice bases and the possibility of resolving individual landform elements makes this geomorphometric analysis directly applicable for advanced mapping techniques such as object-based image analysis.

Pedersen, G. B.; Grosse, P.

2012-12-01

331

Addressing submarine geohazards through scientific drilling  

NASA Astrophysics Data System (ADS)

Natural submarine geohazards (earthquakes, volcanic eruptions, landslides, volcanic island flank collapses) are geological phenomena originating at or below the seafloor leading to a situation of risk for off-shore and on-shore structures and the coastal population. Addressing submarine geohazards means understanding their spatial and temporal variability, the pre-conditioning factors, their triggers, and the physical processes that control their evolution. Such scientific endeavour is nowadays considered by a large sector of the international scientific community as an obligation in order to contribute to the mitigation of the potentially destructive societal effects of submarine geohazards. The study of submarine geohazards requires a multi-disciplinary scientific approach: geohazards must be studied through their geological record; active processes must be monitored; geohazard evolution must be modelled. Ultimately, the information must be used for the assessment of vulnerability, risk analysis, and development of mitigation strategies. In contrast with the terrestrial environment, the oceanic environment is rather hostile to widespread and fast application of high-resolution remote sensing techniques, accessibility for visual inspection, sampling and installation of monitoring stations. Scientific Drilling through the IODP (including the related pre site-survey investigations, sampling, logging and in situ measurements capability, and as a platform for deployment of long term observatories at the surface and down-hole) can be viewed as the centre of gravity of an international, coordinated, multi-disciplinary scientific approach to address submarine geohazards. The IODP Initial Science Plan expiring in 2013 does not address openly geohazards among the program scientific objectives. Hazards are referred to mainly in relation to earthquakes and initiatives towards the understanding of seismogenesis. Notably, the only drilling initiative presently under way is the multi-platform drilling of the Nankai seismogenic zone. Scientific initiatives are flourishing to drive IODP towards the study of submarine geohazards. In the last three years international workshops, were held to address the topic: ESF-ECORD sponsored a Magellan Workshop focussed on submarine landslides (Barcelona, Spain, 2006); IODP sponsored a world-wide Geohazard Workshop (Portland, Oregon, 2007); ESF-ECORD sponsored another Magellan Workshop focussed on Mediterranean submarine geohazards (Luleå, Sweden, 2008). In addition, following the ECORD-Net Conference on the Deep Sea Frontier (Naples, Italy, 2006), the history, monitoring and prediction of geohazards was identified as one of the 6 major areas for a European science plan to integrate Ocean Drilling, Ocean Margin, and Seabed research. More than 200 scientists and private companies representatives have been mobilized world-wide to attend these meetings, from where it emerged that Ocean Drilling will play a key role in the future to answer the following basic open questions on submarine geohazards: - What is the frequency, magnitude, and distribution of geohazard events? - Do precursory phenomena exist and can they be recognized? - What are the physical and mechanical properties of materials prone to failure? - What are the roles of preconditioning vs. triggering in rapid seafloor deformation? - Can the tsunamigenic potential of past and future events be assessed? Within the global-ocean geohazards, worth of note is the attention given in this preparatory phase to submarine geohazards in the Mediterranean basin, a miniature ocean often called a "natural laboratory" because of the diversity of geological environments it contains. The coastline is very densely-populated, totalling 160 million inhabitants sharing 46,000 km of coastline. The Mediterranean is the World's leading holiday destination, receiving an average of 135 million visitors annually. Submarine landslides, volcanic flank collapses, volcanic island eruptions, earthquakes and the associated tsunamis can lead to destruction of seaf

Camerlenghi, A.

2009-04-01

332

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

333

Effects of Sulfur Emissions from Popocatepetl Volcano on the Central U.S. in June 1997  

E-print Network

Effects of Sulfur Emissions from Popocatepetl Volcano on the Central U.S. in June 1997 Carmen M the degassing of SO2 from volcanos can represent a major fraction of sulfate in impacted areas and can is a continually degassing volcano located in Central Mexico (98.62°W, 19.02°N); on June 16, 1997 it had a major

334

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

335

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.

336

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

337

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.

338

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

339

Catalog of earthquake hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011  

USGS Publications Warehouse

Between January 1 and December 31, 2011, the Alaska Volcano Observatory (AVO) located 4,364 earthquakes, of which 3,651 occurred within 20 kilometers of the 33 volcanoes with seismograph subnetworks. There was no significant seismic activity above background levels in 2011 at these instrumented volcanic centers. This catalog includes locations, magnitudes, and statistics of the earthquakes located in 2011 with the station parameters, velocity models, and other files used to locate these earthquakes.

Dixon, James P.; Stihler, Scott D.; Power, John A.; Searcy, Cheryl K.

2012-01-01

340

Submarine transmission line: lifeline for Vieques  

Microsoft Academic Search

Lack of an adequate water supply is now a thing of the past for the island of Vieques. On Feb. 10, 1978, a submarine water transmission main from mainland Puerto Rico to Vieques was inaugurated. This facility has dramatically increased the potable water supply for the island, eliminating the need for the operation of twelve low production wells whose waters

Juan J. Mayol; José R. Goitia

1980-01-01

341

Gold plating in submarine telephone cable repeaters  

Microsoft Academic Search

Thousands of miles of submarine telephone cables form an important and growing part of the world pattern of communications.\\u000a Repeaters every few miles along these cables maintain signal strengths, and many of the components in these repeaters are\\u000a gold plated to ensure freedom from deterioration or failure in service.

D. S. Girling

1973-01-01

342

Sliding of outrunner blocks from submarine landslides  

Microsoft Academic Search

Outrunner blocks are nearly intact pieces of debris that detach from a slowing-down submarine landslide and flow ahead of the front. Data gathered from different sliding areas highlight some properties of outrunner blocks and in particular their inordinate mobility reflected in runouts of up to 25 kilometres, even on very gentle slopes. Blocks may produce an erosion glide track on

Fabio Vittorio De Blasio; Lars Enok Engvik; Anders Elverhøi

2006-01-01

343

Submarine Thermal Springs on the Galapagos Rift  

Microsoft Academic Search

The submarine hydrothermal activity on and near the Galapagos Rift has been explored with the aid of the deep submersible Alvin. Analyses of water samples from hydrothermal vents reveal that hydrothermal activity provides significant or dominant sources and sinks for several components of seawater; studies of conductive and convective heat transfer suggest that two-thirds of the heat lost from new

John B. Corliss; Jack Dymond; Louis I. Gordon; John M. Edmond; Richard P. von Herzen; Robert D. Ballard; Kenneth Green; David Williams; Arnold Bainbridge; Kathy Crane; Tjeerd H. van Andel

1979-01-01

344

Chemical environments of submarine hydrothermal systems  

NASA Technical Reports Server (NTRS)

Perhaps because black-smoker chimneys make tremendous subjects for magazine covers, the proposal that submarine hydrothermal systems were involved in the origin of life has caused many investigators to focus on the eye-catching hydrothermal vents. In much the same way that tourists rush to watch the spectacular eruptions of Old Faithful geyser with little regard for the hydrology of the Yellowstone basin, attention is focused on the spectacular, high-temperature hydrothermal vents to the near exclusion of the enormous underlying hydrothermal systems. Nevertheless, the magnitude and complexity of geologic structures, heat flow, and hydrologic parameters which characterize the geyser basins at Yellowstone also characterize submarine hydrothermal systems. However, in the submarine systems the scale can be considerably more vast. Like Old Faithful, submarine hydrothermal vents have a spectacular quality, but they are only one fascinating aspect of enormous geologic systems operating at seafloor spreading centers throughout all of the ocean basins. A critical study of the possible role of hydrothermal processes in the origin of life should include the full spectrum of probable environments. The goals of this chapter are to synthesize diverse information about the inorganic geochemistry of submarine hydrothermal systems, assemble a description of the fundamental physical and chemical attributes of these systems, and consider the implications of high-temperature, fluid-driven processes for organic synthesis. Information about submarine hydrothermal systems comes from many directions. Measurements made directly on venting fluids provide useful, but remarkably limited, clues about processes operating at depth. The oceanic crust has been drilled to approximately 2.0 km depth providing many other pieces of information, but drilling technology has not allowed the bore holes and core samples to reach the maximum depths to which aqueous fluids circulate in oceanic crust. Such determinations rely on studies of pieces of deep oceanic crust uplifted by tectonic forces such as along the Southwest Indian Ridge, or more complete sections of oceanic crust called ophiolite sequences which are presently exposed on continents owing to tectonic emplacement. Much of what is thought to happen in submarine hydrothermal systems is inferred from studies of ophiolite sequences, and especially from the better-exposed ophiolites in Oman, Cyprus and North America. The focus of much that follows is on a few general features: pressure, temperature, oxidation states, fluid composition and mineral alteration, because these features will control whether organic synthesis can occur in hydrothermal systems.

Shock, Everett L.

1992-01-01

345

One hundred years of volcano monitoring in Hawaii  

USGS Publications Warehouse

In 2012 the Hawaiian Volcano Observatory (HVO), the oldest of five volcano observatories in the United States, is commemorating the 100th anniversary of its founding. HVO's location, on the rim of Klauea volcano (Figure 1)one of the most active volcanoes on Earthhas provided an unprecedented opportunity over the past century to study processes associated with active volcanism and develop methods for hazards assessment and mitigation. The scientifically and societally important results that have come from 100 years of HVO's existence are the realization of one man's vision of the best way to protect humanity from natural disasters. That vision was a response to an unusually destructive decade that began the twentieth century, a decade that saw almost 200,000 people killed by the effects of earthquakes and volcanic eruptions.

Kauahikaua, J.; Poland, M.

2012-01-01

346

One hundred years of volcano monitoring in Hawaii  

USGS Publications Warehouse

In 2012 the Hawaiian Volcano Observatory (HVO), the oldest of five volcano observatories in the United States, is commemorating the 100th anniversary of its founding. HVO's location, on the rim of Kilauea volcano (Figure 1)—one of the most active volcanoes on Earth—has provided an unprecedented opportunity over the past century to study processes associated with active volcanism and develop methods for hazards assessment and mitigation. The scientifically and societally important results that have come from 100 years of HVO's existence are the realization of one man's vision of the best way to protect humanity from natural disasters. That vision was a response to an unusually destructive decade that began the twentieth century, a decade that saw almost 200,000 people killed by the effects of earthquakes and volcanic eruptions.

Kauahikaua, Jim; Poland, Mike

2012-01-01

347

Catalog of earthquake hypocenters at Alaskan Volcanoes: January 1 through December 31, 2010  

USGS Publications Warehouse

Between January 1 and December 31, 2010, the Alaska Volcano Observatory (AVO) located 3,405 earthquakes, of which 2,846 occurred within 20 kilometers of the 33 volcanoes with seismograph subnetworks. There was no significant seismic activity in 2010 at these monitored volcanic centers. Seismograph subnetworks with severe outages in 2009 were repaired in 2010 resulting in three volcanic centers (Aniakchak, Korovin, and Veniaminof) being relisted in the formal list of monitored volcanoes. This catalog includes locations and statistics of the earthquakes located in 2010 with the station parameters, velocity models, and other files used to locate these earthquakes.

Dixon, James P.; Stihler, Scott D.; Power, John A.; Searcy, Cheryl K.

2011-01-01

348

Lab7: Volcanoes I. --Their Geographic Distribution Introduction  

E-print Network

(Tambora, 1815) and the fourth largest (Krakatau, 1883) have occurred in this volcanic region. More than of their remote location, the volcanoes are only poorly known. Aleutian Arc. Curved chain of recent volcanic exclusively of basalt. #12; 2 Aeolian Arc. This volcanic chain is located in the Mediterranean north

Chen, Po

349

Catalog of earthquake hypocenters at Alaskan volcanoes: January 1, 1994 through December 31, 1999  

USGS Publications Warehouse

The Alaska Volcano Observatory (AVO), a cooperative program of the U.S. Geological Survey, the Geophysical Institute of the University of Alaska - Fairbanks, and the Alaska Division of Geological and Geophysical Surveys, has maintained a seismic monitoring program at potentially active volcanoes in Alaska since 1988 (Power and others, 1993; Jolly and others, 1996). The primary objectives of this program are the seismic surveillance of active, potentially hazardous, Alaskan volcanoes and the investigation of seismic processes associated with active volcanism. Between 1994 and 1999, the AVO seismic monitoring program underwent significant changes with networks added at new volcanoes during each summer from 1995 through 1999. The existing network at Katmai –Valley of Ten Thousand Smokes (VTTS) was repaired in 1995, and new networks were installed at Makushin (1996), Akutan (1996), Pavlof (1996), Katmai - south (1996), Aniakchak (1997), Shishaldin (1997), Katmai - north (1998), Westdahl, (1998), Great Sitkin (1999) and Kanaga (1999). These networks added to AVO's existing seismograph networks in the Cook Inlet area and increased the number of AVO seismograph stations from 46 sites and 57 components in 1994 to 121 sites and 155 components in 1999. The 1995–1999 seismic network expansion increased the number of volcanoes monitored in real-time from 4 to 22, including Mount Spurr, Redoubt Volcano, Iliamna Volcano, Augustine Volcano, Mount Snowy, Mount Griggs, Mount Katmai, Novarupta, Trident Volcano, Mount Mageik, Mount Martin, Aniakchak Crater, Pavlof Volcano, Mount Dutton, Isanotski volcano, Shisaldin Volcano, Fisher Caldera, Westdahl volcano, Akutan volcano, Makushin Volcano, Great Sitkin volcano, and Kanaga Volcano (see Figures 1-15). The network expansion also increased the number of earthquakes located from about 600 per year in1994 and 1995 to about 3000 per year between 1997 and 1999. Highlights of the catalog period include: 1) a large volcanogenic seismic swarm at Akutan volcano in March and April 1996 (Lu and others, 2000); 2) an eruption at Pavlof Volcano in fall 1996 (Garces and others, 2000; McNutt and others, 2000); 3) an earthquake swarm at Iliamna volcano between September and December 1996; 4) an earthquake swarm at Mount Mageik in October 1996 (Jolly and McNutt, 1999); 5) an earthquake swarm located at shallow depth near Strandline Lake; 6) a strong swarm of earthquakes near Becharof Lake; 7) precursory seismicity and an eruption at Shishaldin Volcano in April 1999 that included a 5.2 ML earthquake and aftershock sequence (Moran and others, in press; Thompson and others, in press). The 1996 calendar year is also notable as the seismicity rate was very high, especially in the fall when 3 separate areas (Strandline Lake, Iliamna Volcano, and several of the Katmai volcanoes) experienced high rates of located earthquakes. This catalog covers the period from January 1, 1994, through December 31,1999, and includes: 1) earthquake origin times, hypocenters, and magnitudes with summary statistics describing the earthquake location quality; 2) a description of instruments deployed in the field and their locations and magnifications; 3) a description of earthquake detection, recording, analysis, and data archival; 4) velocity models used for earthquake locations; 5) phase arrival times recorded at individual stations; and 6) a summary of daily station usage from throughout the report period. We have made calculated hypocenters, station locations, system magnifications, velocity models, and phase arrival information available for download via computer network as a compressed Unix tar file.

Jolly, Arthur D.; Stihler, Scott D.; Power, John A.; Lahr, John C.; Paskievitch, John; Tytgat, Guy; Estes, Steve; Lockhart, Andrew B.; Moran, Seth C.; McNutt, Stephen R.; Hammond, William R.

2001-01-01

350

First Use of an Autonomous Glider for Exploring Submarine Volcanism in the SW Pacific  

NASA Astrophysics Data System (ADS)

A 1000-m Slocum glider® (Teledyne Webb Research Corporation) with CTD, turbidity, and hydrophone sensors was operated for two days in the Northeast Lau Basin. The survey was conducted near West Mata Volcano, where in November of 2008 the NOAA PMEL Vents program observed an active eruption at its 1207 m summit—the deepest submarine activity ever before witnessed. Our goal was to use the glider as a forensic tool to search for other nearby eruption sites with onboard sensors that detect the chemical and hydroacoustic signatures associated with the volcanic and hydrothermal plumes. The glider was launched approximately 40 km to the west of West Mata. It flew toward West Mata and was recovered near the summit of the volcano after repeating 13 yos during a 41-hour mission. Although the recordings were affected by mechanical noise from the glider’s rudder, the data demonstrate that the system can detect the wide-band noises (>1 kHz) associated with submarine volcanic and intense hydrothermal activity. The glider recorded complex acoustic amplitudes due to the multiple raypaths from West Mata as well as temporal variations in the volcano’s rate of activity, and demonstrated that these geologic processes contribute to the region’s high ambient noise levels. With the exception of the deployment and recovery, the mission was managed entirely by the shore teams in PMEL (Seattle, WA) and OSU labs (Newport, OR), ~5000 miles away without an engineer onboard. The dive cycle of the 950-m dives was ~3.5 hours and the average speed was ~0.27 cm/s. The CTD data were downloaded at every surface cycle and appeared to be of high quality. However we found that the sensitivity of the Wetlabs ECO flntu turbidity sensor was not adequate for the detection of volcanic plumes. The mission demonstrated PMEL’s ability to use autonomous gliders to monitor a variety of environmental parameters including ambient sound levels, temperature, salinity and turbidity for the purpose of finding subsea volcanism. Our plan is to add a more sensitive turbidity sensor and design a near realtime interface between the NOAA’s acoustic system and glider.

Matsumoto, H.; Embley, R. W.; Haxel, J. H.; Dziak, R. P.; Bohnenstiehl, D. R.; Stalin, S.; Meinig, C.

2010-12-01

351

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

352

Estimates of elastic plate thicknesses beneath large volcanos on Venus  

NASA Technical Reports Server (NTRS)

Megellan radar imaging and topography data are now available for a number of volcanos on Venus greater than 100 km in radius. These data can be examined to reveal evidence of the flexural response of the lithosphere to the volcanic load. On Earth, flexure beneath large hotspot volcanos results in an annual topographic moat that is partially to completely filled in by sedimentation and mass wasting from the volcano's flanks. On Venus, erosion and sediment deposition are considered to be negligible at the resolution of Magellan images. Thus, it may be possible to observe evidence of flexure by the ponding of recent volcanic flows in the moat. We also might expect to find topographic signals from unfilled moats surrounding large volcanos on Venus, although these signals may be partially obscured by regional topography. Also, in the absence of sedimentation, tectonic evidence of deformation around large volcanos should be evident except where buried by very young flows. We use analytic solutions in axisymmetric geometry for deflections and stresses resulting from loading of a plate overlying an inviscid fluid. Solutions for a set of disk loads are superimposed to obtain a solution for a conical volcano. The deflection of the lithosphere produces an annular depression or moat, the extent of which can be estimated by measuring the distance from the volcano's edge to the first zero crossing or to the peak of the flexural arch. Magellan altimetry data records (ARCDRs) from data cycle 1 are processed using the GMT mapping and graphics software to produce topographic contour maps of the volcanos. We then take topographic profiles that cut across the annular and ponded flows seen on the radar images. By comparing the locations of these flows to the predicted moat locations from a range of models, we estimate the elastic plate thickness that best fits the observations, together with the uncertainty in that estimate.

Mcgovern, Patrick J.; Solomon, Sean C.

1992-01-01

353

The natural ocean acidification and fertilization event caused by the submarine eruption of El Hierro  

PubMed Central

The shallow submarine eruption which took place in October 10th 2011, 1.8?km south of the island of El Hierro (Canary Islands) allowed the study of the abrupt changes in the physical-chemical properties of seawater caused by volcanic discharges. In order to monitor the evolution of these changes, seven oceanographic surveys were carried out over six months (November 2011-April 2012) from the beginning of the eruptive stage to the post-eruptive phase. Here, we present dramatic changes in the water column chemistry including large decreases in pH, striking effects on the carbonate system, decreases in the oxygen concentrations and enrichment of Fe(II) and nutrients. Our findings highlight that the same volcano which was responsible for the creation of a highly corrosive environment, affecting marine biota, has also provided the nutrients required for the rapid recuperation of the marine ecosystem. PMID:23355953

Santana-Casiano, J. M.; Gonzalez-Davila, M.; Fraile-Nuez, E.; de Armas, D.; Gonzalez, A. G.; Dominguez-Yanes, J. F.; Escanez, J.

2013-01-01

354

The natural ocean acidification and fertilization event caused by the submarine eruption of El Hierro.  

PubMed

The shallow submarine eruption which took place in October 10(th) 2011, 1.8 km south of the island of El Hierro (Canary Islands) allowed the study of the abrupt changes in the physical-chemical properties of seawater caused by volcanic discharges. In order to monitor the evolution of these changes, seven oceanographic surveys were carried out over six months (November 2011-April 2012) from the beginning of the eruptive stage to the post-eruptive phase. Here, we present dramatic changes in the water column chemistry including large decreases in pH, striking effects on the carbonate system, decreases in the oxygen concentrations and enrichment of Fe(II) and nutrients. Our findings highlight that the same volcano which was responsible for the creation of a highly corrosive environment, affecting marine biota, has also provided the nutrients required for the rapid recuperation of the marine ecosystem. PMID:23355953

Santana-Casiano, J M; González-Dávila, M; Fraile-Nuez, E; de Armas, D; González, A G; Domínguez-Yanes, J F; Escánez, J

2013-01-01

355

On the fate of pumice rafts formed during the 2012 Havre submarine eruption  

PubMed Central

Pumice rafts are floating mobile accumulations of low-density pumice clasts generated by silicic volcanic eruptions. Pumice in rafts can drift for years, become waterlogged and sink, or become stranded on shorelines. Here we show that the pumice raft formed by the impressive, deep submarine eruption of the Havre caldera volcano (Southwest Pacific) in July 2012 can be mapped by satellite imagery augmented by sailing crew observations. Far from coastal interference, the eruption produced a single >400?km2 raft in 1 day, thus initiating a gigantic, high-precision, natural experiment relevant to both modern and prehistoric oceanic surface dispersal dynamics. Observed raft dispersal can be accurately reproduced by simulating drift and dispersal patterns using currents from an eddy-resolving ocean model hindcast. For future eruptions that produce potentially hazardous pumice rafts, our technique allows real-time forecasts of dispersal routes, in addition to inference of ash/pumice deposit distribution in the deep ocean. PMID:24755668

Jutzeler, Martin; Marsh, Robert; Carey, Rebecca J.; White, James D. L.; Talling, Peter J.; Karlstrom, Leif

2014-01-01

356

Liquid Carbon Dioxide Venting at the Champagne Hydrothermal Site, NW Eifuku Volcano, Mariana Arc  

NASA Astrophysics Data System (ADS)

In March/April 2004, submersible dives with the remotely-operated vehicle ROPOS discovered an unusual CO2-rich hydrothermal system near the summit of NW Eifuku, a submarine volcano located at 21.49° N, 144.04° E in the northern Mariana Arc. Although several sites of hydrothermal discharge were located on NW Eifuku, the most intense venting was found at 1600-m depth at the Champagne site, slightly west of the volcano summit. The Champagne site was found to be discharging two distinct fluids into the ocean: a) several small white chimneys were emitting milky 103° C gas-rich hydrothermal fluid with at least millimolar levels of H2S and b) cold (< 4° C) droplets coated with a milky skin were rising slowly from the sediment. These droplets were later determined to consist mainly of liquid CO2, with H2S as a probable secondary component. The droplets were sticky, and did not tend to coalesce into larger droplets, even though they adhered to the ROV like clumps of grapes. The film coating the droplets was assumed to be CO2 hydrate (or clathrate) which is known to form whenever liquid CO2 contacts water under these P,T conditions. Samples of the 103° C hydrothermal fluids were collected in special gas-tight titanium sampling bottles that were able to withstand the high internal pressures created by the dissolved gases. The Champagne hydrothermal fluids contained a surprising 2.3 moles/kg of CO2, an order of magnitude higher than any CO2 values previously reported for submarine hydrothermal fluids. The overall gas composition was 87% CO2, < 0.1% CH4, < 2 ppm H2, 0.012 mM/kg 4He, with the remaining 13% (322 mM/kg) assumed to be sulfur gases (H2S, SO2, etc.). (Additional analyses planned will confirm the speciation of this sulfur gas component). The helium had R/RA = 7.3, typical of subduction zone systems (R = 3He/4He and RA = Rair). Isotopic analysis of the CO2 yielded ? 13C = -1.75 ‰ , much heavier than the -6.0 ‰ typical for carbon in MOR vent fluids. The C/3He ratio was ~2.2 x 1010, an order of magnitude higher than the average value of 2 x 109 found in MOR vent fluids. The ? 13C and C/3He values suggest a substantial contribution to the carbon from subducted carbonates rather than mantle carbon. The Champagne site is only the second locality where liquid CO2 has been observed venting into the deep sea (the other reported location is in the Okinawa Trough, see Sakai et al., 1990). Because of the presence of liquid CO2 in proximity to hydrothermal organisms, the Champagne site may prove to be a valuable natural laboratory for studying the effects of high CO2 concentrations on marine ecosystems.

Lupton, J.; Lilley, M.; Butterfield, D.; Evans, L.; Embley, R.; Olson, E.; Proskurowski, G.; Resing, J.; Roe, K.; Greene, R.; Lebon, G.

2004-12-01

357

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

358

Crustal deformation and volcanic earthquakes associated with the recent volcanic activity of Iwojima Volcano, Japan  

NASA Astrophysics Data System (ADS)

Iwojima is an active volcanic island located within a 10 km wide submarine caldera about 1250 km to the south of Tokyo, Japan. The seismometer and GPS network of National Research Institute for Earth Science and Disaster Prevention (NIED) in Iwojima has observed a repeating island wide uplift more than 1 m associated with large number of volcanic earthquakes every several years. During 2006-2012, we observed more than 20000 volcanic earthquakes and an uplift of about 3 m, and precursory volcanic earthquakes and rapid crustal deformation just before the small submarine eruption near the northern coast of Iwojima in April 2012. In a restless volcano such as Iwojima, it is important issue to distinguish whether rapid crustal deformation and intense earthquake activity lead to an eruption or not. According to a long period geodetic observation by Ukawa et al. (2006), the crustal deformation of Iwojima can be classify into 2 phases. The first is an island wide large uplift centering on Motoyama area (the eastern part of the island, the center of the caldera), and the second is contraction and subsidence at local area centering on Motoyama and uplift around that area. They are interpreted by superposition of crustal deformations by a shallow contraction source and a deep seated inflation source beneath Motoyama. The earthquake activity of Iwojima highly correlates with the island wide large uplift, suggesting the earthquakes are almost controlled by a magma accumulation into a deep seated magma chamber. In contrast to the activity, the precursory activity of the eruption in 2012 is deviated from the correlation. The rapid crustal deformation just before and after the eruption in 2012 can be interpreted by rapid inflation and deflation of a shallow sill source about 1km deep, respectively, suggesting that it was caused by a shallow hydrothermal activity. The result shows that we can probably distinguish an abnormal activity related with a volcanic eruption when we observe a volcanic activity deviated from the correlation. Since the beginning of Japanese settlement into Iwojima in 1898, more than 20 phreatic eruptions have been reported, whereas no historical magmatic eruptions have been reported. The eruptive activity probably limited in near ground surface at present in spite of the successive magma injection into the deep magma chamber.

Ueda, H.; Fujita, E.; Tanada, T.

2013-12-01

359

Fluid Flow Simulations of an Active Arc-Related Submarine Hydrothermal System  

NASA Astrophysics Data System (ADS)

Active high-temperature vents at the seafloor greatly contribute to the heat transport system at the Earth's surface and significantly influence the chemistry of crust and overlying ocean. While mid-ocean ridge systems have been intensely studied in the last decades, hydrothermal activity along convergent plate boundaries has received deeper attention only in the last few years. Brothers volcano is the most hydrothermally active volcano situated along the intra-oceanic Kermadec arc, northeast of North Island, New Zealand. Recent detailed surveys of hydrothermal plumes at Brothers volcano picture several distinct vent sites at different localities within the volcanic edifice. Venting ranges from lower temperature, gas-rich and metal-poor fluids to relatively high temperature (~300 °C), metal-rich fluids. However, the sub-surface structure of these systems and the contribution of magmatic sources are not well understood yet. In order to model the sub-seafloor hydrodynamics of Brothers volcano, a numerical transport scheme has been applied, using a combined finite element - finite volume method which computes multi-phase fluid flow and describes heat transport on basis of enthalpy, pressure, and salinity. Our process code covers the full phase relations of the binary NaCl-H2O system up to 1000 °C and accurately captures boiling, condensation, and salt precipitation. Numerical simulations for varying first-order physical parameters such as water depth and seafloor topography, rock permeability, and a heat source with or without a deep magmatic fluid source have been conducted. Our results show that seafloor topography controls the spatial distribution of venting sites and the input of a magmatic fluid source affects the style of hydrothermal venting. In this ongoing project, by combining simulation results with real observations in Brothers volcano and other currently active arc-related submarine volcanoes, we aim to present a new understanding of the sub-surface hydrology, the interaction of seawater with magmatic fluids, and subsequently the conditions to generate particularly Cu- and Au-rich mineralization within such magmatic-hydrothermal systems.

Gruen, G.; de Ronde, C. E.; Driesner, T.; Heinrich, C. A.

2009-12-01

360

Generation scenarios for Atlantic-region tsunamis: landslides and volcanos  

NASA Astrophysics Data System (ADS)

Significant historical and prehistoric tsunami activity in the Atlantic and in the peripheral Caribbean and Mediterranean Basins has often been associated with volcanic activity. Landslides from continental shelf margins and from undersea trenches have also contributed. These none-earthquake sources probably contribute more tsunamis to the Atlantic basin than earthquakes do, in contrast to the more earthquake- prone Pacific and Indian Oceans. (Of course one must always remember the devastating Lisbon earthquake tsunami of 1755). For the Atlantic region it is therefore important to better understand the ways in which volcanos and landslides produce tsunamis, and to that end I present simulations of tsunami generation mechanisms in the context of subaerial landslides (as in the Canary and Cape Verde Islands), submarine landslides (as in Caribbean trenches and continental shelf margins), and by hydromagmatic activity (as in the Caribbean and Iceland). I will also briefly discuss the unlikely danger posed by asteroid-impact tsunamis.

Gisler, G. R.

2008-12-01

361

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

362

Zircon UPb Dating Analyses of Lava Domes in the Sutter Buttes Volcano, California  

Microsoft Academic Search

The Sutter Buttes are a Pleistocene volcano located in the Sacramento Valley 80 km north of Sacramento. The volcano is circular, 15 km in diameter, and composed of a central core of volcanic domes surrounded by a large fragmental apron of pyroclastic deposits. Most of the dome complex is andesite-dacite while rhyolite domes form a discontinuous peripheral ring around the

A. M. Hansen; B. Hausback; A. K. Schmitt

2010-01-01

363

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

364

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

NSDL National Science Digital Library

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

Fries-Gaither, Jessica

365

Models of Ground Deformation and Eruption Magnitude from a Deep Source at Popocatepetl Volcano, Central Mexico  

Microsoft Academic Search

Popocatepetl volcano in Central Mexico entered its latest stage of activity in late 1994. Due to the nature of its eruptive history and its location in a heavily populated area, it constitutes the highest risk in the cuntry. For this reason the volcano is currently under continuous surveillance; yet the interpretation of the information is carried out mostly on empirical

Juan Manuel Espíndola; Maria De Lourdes Godinez; Victor Hugo Espindola

2004-01-01

366

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

367

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

Microsoft Academic Search

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

S. Ettinger; S. Kruse

2007-01-01

368

Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2008  

USGS Publications Warehouse

Between January 1 and December 31, 2008, the Alaska Volcano Observatory (AVO) located 7,097 earthquakes of which 5,318 occurred within 20 kilometers of the 33 volcanoes monitored by the AVO. Monitoring highlights in 2008 include the eruptions of Okmok Caldera, and Kasatochi Volcano, as well as increased unrest at Mount Veniaminof and Redoubt Volcano. This catalog includes descriptions of: (1) locations of seismic instrumentation deployed during 2008; (2) earthquake detection, recording, analysis, and data archival systems; (3) seismic velocity models used for earthquake locations; (4) a summary of earthquakes located in 2008; and (5) an accompanying UNIX tar-file with a summary of earthquake origin times, hypocenters, magnitudes, phase arrival times, location quality statistics, daily station usage statistics, and all files used to determine the earthquake locations in 2008.

Dixon, James P.; Stihler, Scott D.

2009-01-01

369

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

370

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

371

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.

372

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.

373

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

374

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

375

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

376

Total Magnetic Field Signatures over Submarine HVDC Power Cables  

NASA Astrophysics Data System (ADS)

Mikhail Tchernychev, Geometrics, Inc. Ross Johnson, Geometrics, Inc. Jeff Johnston, Geometrics, Inc. High Voltage Direct Current (HVDC) technology is widely used to transmit electrical power over considerable distances using submarine cables. The most commonly known examples are the HVDC cable between Italy and Greece (160 km), Victoria-Tasmania (300 km), New Jersey - Long Island (82 km) and the Transbay cable (Pittsburg, California - San-Francisco). These cables are inspected periodically and their location and burial depth verified. This inspection applies to live and idle cables; in particular a survey company could be required to locate pieces of a dead cable for subsequent removal from the sea floor. Most HVDC cables produce a constant magnetic field; therefore one of the possible survey tools would be Marine Total Field Magnetometer. We present mathematical expressions of the expected magnetic fields and compare them with fields observed during actual surveys. We also compare these anomalies fields with magnetic fields produced by other long objects, such as submarine pipelines The data processing techniques are discussed. There include the use of Analytic Signal and direct modeling of Total Magnetic Field. The Analytic Signal analysis can be adapted using ground truth where available, but the total field allows better discrimination of the cable parameters, in particular to distinguish between live and idle cable. Use of a Transverse Gradiometer (TVG) allows for easy discrimination between cable and pipe line objects. Considerable magnetic gradient is present in the case of a pipeline whereas there is less gradient for the DC power cable. Thus the TVG is used to validate assumptions made during the data interpretation process. Data obtained during the TVG surveys suggest that the magnetic field of a live HVDC cable is described by an expression for two infinite long wires carrying current in opposite directions.

Johnson, R. M.; Tchernychev, M.; Johnston, J. M.; Tryggestad, J.

2013-12-01

377

Frequency based satellite monitoring of small scale explosive activity at remote North Pacific volcanoes  

NASA Astrophysics Data System (ADS)

Monitoring of volcanoes in the North Pacific can be an expensive and sometimes dangerous task, specifically for those located in Alaska (USA) and Kamchatka (Russia). An active frequency detection method previously used at Stromboli, Italy, uses the thermal- and mid-infrared wavelength bands from the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data to detect anomalies at a volcano. This method focuses on small scale explosive activity, often referred to as Strombolian activity which can produce small spatter fields near a volcano's active vent. In the North Pacific, there are a number of volcanoes which exhibit small scale explosive activity and three are the focus of this study: Chuginadak (Mt. Cleveland) and Shishaldin in Alaska, and Karymsky Volcano in Kamchatka. Satellite images from the Advanced Very High Resolution Radiometer (AVHRR) were used to monitor the frequency of thermal features as well as the occurrence of ash plumes at each volcano. This data was then used to produce a time series spanning 2005-2010 for all three volcanoes. During this time period, each volcano underwent a series of eruptive cycles including background levels of activity, heightened frequency of small explosions (identified as precursory activity), and heightened activity typified by ash plume-producing eruptions. Each location has a unique precursory signal, both in timing and magnitude. The use of a previously developed method on a new sample set of volcanoes has proved the validity of this method as a monitoring tool for volcanoes with small scale explosive activity. This method should be applied to a larger set of volcanoes to continue the development and database production for its use as a volcano monitoring tool.

Worden, Anna; Dehn, Jonathan; Webley, Peter

2014-10-01

378

Magmatically Greedy Reararc Volcanoes of the N. Tofua Segment of the Tonga Arc  

NASA Astrophysics Data System (ADS)

Volcanism along the northernmost Tofua Arc is enigmatic because edifices of the arc's volcanic front are mostly, magmatically relatively anemic, despite the very high convergence rate of the Pacific Plate with this section of Tonga Arc. However, just westward of the arc front, in terrain generally thought of as part of the adjacent NE Lau Backarc Basin, lie a series of very active volcanoes and volcanic features, including the large submarine caldera Niuatahi (aka volcano 'O'), a large composite dacite lava flow terrain not obviously associated with any particular volcanic edifice, and the Mata volcano group, a series of 9 small elongate volcanoes in an extensional basin at the extreme NE corner of the Lau Basin. These three volcanic terrains do not sit on arc-perpendicular cross chains. Collectively, these volcanic features appear to be receiving a large proportion of the magma flux from the sub-Tonga/Lau mantle wedge, in effect 'stealing' this magma flux from the arc front. A second occurrence of such magma 'capture' from the arc front occurs in an area just to the south, on southernmost portion of the Fonualei Spreading Center. Erupted compositions at these 'magmatically greedy' volcanoes are consistent with high slab-derived fluid input into the wedge (particularly trace element abundances and volatile contents, e.g., see Lupton abstract this session). It is unclear how long-lived a feature this is, but the very presence of such hyperactive and areally-dispersed volcanism behind the arc front implies these volcanoes are not in fact part of any focused spreading/rifting in the Lau Backarc Basin, and should be thought of as 'reararc volcanoes'. Possible tectonic factors contributing to this unusually productive reararc environment are the high rate of convergence, the cold slab, the highly disorganized extension in the adjacent backarc, and the tear in the subducting plate just north of the Tofua Arc.

Rubin, K. H.; Embley, R. W.; Arculus, R. J.; Lupton, J. E.

2013-12-01

379

Hypercortisolism as a potential concern for submariners.  

PubMed

Cortisol is a stress-response hormone that is important for survivability in fight or flight situations. Hypercortisolism is a state of chronically elevated cortisol levels due to a failure to return to, or maintain baseline levels. It is a condition that is often undiagnosed and can aid in the development of many physiological and psychological health problems. Some of the health ailments associated with hypercortisolism include metabolic syndrome, decreases in bone mineral density, and depression. Chronic stress and sleep deprivation are two common causes of hypercortisolism, both areas of concern within the submarine community. This review discusses the etiology of hypercortisolism and the likelihood of submariner vulnerability to the condition along with health problems associated with it. Lastly, strategies to prevent chronic elevation of cortisol and mitigate the potential health risks associated with the condition are covered. PMID:21197856

Reini, Seth A

2010-12-01

380

Detailed Analysis of a Submarine Landslide (SAR27) in the Deep Basin Offshore Algiers (Western Mediterranean)  

Microsoft Academic Search

\\u000a On May 21, 2003 an earthquake with a magnitude of 6.8 (Mw) struck the city of Boumerdes, located on the coast near Algiers,\\u000a and generated significant gravity flows recognized by numerous submarine cable breaks. In order to investigate a possible\\u000a offshore imprint of past earthquakes in terms of sediment instabilities, we analyzed one of the numerous escarpments of tectonic\\u000a origin

A. Nouguès; N. Sultan; A. Cattaneo; G. Dan; K. Yelles

381

Whale Entanglements With Submarine Telecommunication Cables  

Microsoft Academic Search

Before 1955-1966, 16 instances of whale entanglement with submarine telegraphic cables were reported in the scientific literature. Here we present new information, derived from global cable fault databases, that reveals an absence of whale entanglements since 1959. This cessation coincided with the transition from telegraphic to coaxial telecommunication cables followed by the change to fiber-optic systems in the 1980s. We

Matthew Peter Wood; Lionel Carter

2008-01-01

382

Submarine Mass Movements and Their Consequences  

Microsoft Academic Search

\\u000a In 1929, an earthquake off the Grand Banks of Newfoundland initiated a submarine mass movement that sheared undersea communication\\u000a cables and generated a tsunami that resulted in deaths of 27 people along the south coast of Newfoundland. This event initiated\\u000a the modern realization that the seafloor is a dynamic environment with potential to do harm. More recent catastrophic examples\\u000a include

D. C. Mosher; L. Moscardelli; R. C. Shipp; J. D. Chaytor; C. D. P. Baxter; H. J. Lee; R. Urgeles

383

Transport of typhoon-induced submarine sediment-laden flows off southwestern Taiwan  

NASA Astrophysics Data System (ADS)

Since 2006, southern Taiwan experienced destructive typhoons and earthquakes which triggered large scale submarine landslides and turbidity currents and devastated many submarine cables off southwestern Taiwan. Most of cable breakages were located in the Gaoping (GPSC) and Fangliao (FLSC) submarine canyons which indicate submarine canyon is an important pathway for underwater gravity flows that induced by natural hazards. A series of investigations were conducted before and after Morakot typhoon, the sub-bottom profiler and core analysis results revealed the GPSC and FLSC may play different roles in transport sediment from coastal seas to the abyssal ocean during the typhoon invaded period. Off southwestern Taiwan, the GPSC and FLSC are incising from continental shelf to deep sea floor and both of them transport considerable amounts of sediment to the South China Sea. GPSC is directly connected to the Gaoping River on land. The hyperpycnal flows, formed during Typhoon Morakot, delivered coarse sands, gravels and branches of trees into GPSC and deposited at the upper reach. On the contrary, the FLSC, which is smaller, younger and confined to the slope, does not associate with any river on land. A series of turbidites and debrites, which composed by coarse slates, fractal shells, wood fragments and fresh leaves, were observed in cores collected from the head of FLSC through Gaoping slope to the lower reach of GPSC. It implies the torrential rains induced landslides at the southernmost Central Mountain Range may directly delivered large amount of slate fragments through narrow Gaoping shelf into the deep sea. Furthermore, according to Water Resources Agency's groundwater level monitoring data, during Typhoon Morakot, the groundwater level raised significantly at the coastal area of Pingtung Plain. The increased groundwater pressure may lead to high flux of submarine groundwater discharge and induced liquefaction on seafloor. From sub-bottom profiles, the liquefaction structures and chaotic deposits were found widely spread off southwestern Taiwan and we suggest it may highly related to the anomalous submarine groundwater discharge incident. Our results reveal the extreme weather induced catastrophic events (e.g. torrential rains, floods, stormy waves… etc.) can generate devastating sediment-laden flows both in the Gaoping and Fangliao Submarine Canyons and provide an efficient way for delivering organic carbon into the deep sea.

Su, C.; Cheng, Y.

2012-12-01

384

General patterns of circulation, sediment fluxes and ecology of the Palamós (La Fonera) submarine canyon, northwestern Mediterranean  

Microsoft Academic Search

Currents, particle fluxes and ecology were studied in the Palamós submarine canyon (also known as the Fonera canyon), located in the northwestern Mediterranean. Seven mooring arrays equipped with current meters and sediment traps were deployed along the main canyon axis, on the canyon walls and on the adjacent slope. Additionally, local and regional hydrographic cruises were carried out. Current data

Albert Palanques; Emilio García-Ladona; Damià Gomis; Jacobo Martín; Marta Marcos; Ananda Pascual; Pere Puig; Josep-Maria Gili; Mikhail Emelianov; Sebastià Monserrat; Jorge Guillén; Joaquín Tintoré; Mariona Segura; Antoni Jordi; Simón Ruiz; Gotzon Basterretxea; Dolors Blasco; Francesc Pagès

2005-01-01

385

Analysis of the operational impacts of alternative propulsion configurations on submarine maneuverability  

E-print Network

In an effort to develop submarine designs that deliver reduced size submarines with equivalent capabilities of the current USS VIRGINIA (SSN-774 Class) submarine, a joint Navy/Defense Advanced Research Projects Agency ...

Heberley, Brian Douglas.

2011-01-01

386

16. INTERIOR VIEW OF SUBMARINE SECTION AT 110FOOT LEVEL, ESCAPE ...  

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

16. INTERIOR VIEW OF SUBMARINE SECTION AT 110-FOOT LEVEL, ESCAPE TRAINING TANK, SHOWING LADDER TO ESCAPE TANK, LOOKING SOUTH - U.S. Naval Submarine Base, New London Submarine Escape Training Tank, Albacore & Darter Roads, Groton, New London County, CT

387

The submarine service of the future?  

PubMed

Space missions, although now routine, are unique in terms of their environment and logistical requirements. The number of missions (man-hours) remains relatively small and planning still relies on comparisons with analogous missions, including submarine operations. Antarctic missions, which tend not to be classified, have provided more information about isolated communities because of the number of personnel per base. Space medicine has traditionally been an extension of aviation medicine with high g-forces involved in the transition from Earth to orbit and astronauts such as Neil Armstrong recruited from the test pilot fraternity. As the length of a mission increases and the space habitation relies more on regenerative systems, the environment becomes more analogous with today's nuclear submarines. As well as the air purification implications, radiation still is a significant hazard with even greater impact on future Mars missions requiring the provision of health physics monitoring, advice and countermeasures well established in the submarine flotilla. Nevertheless, the specialty space medicine will progress as a specialty in its own right, pooling expertise from other specialties such as aviation, radiation, emergency and occupational medicine taking human exploration beyond the confines of land and sea. PMID:11346925

Bland, S A

2000-01-01

388

Seismic anisotropy and its time variation on active volcanoes  

NASA Astrophysics Data System (ADS)

Seismic anisotropy, the directional dependence of wave speeds, is caused by stress-oriented cracks and can be used to monitor stresses from magmatic movement. Shear wave splitting fast polarisations (?) align with cracks and hence with the compressive stress field. Delay times (dt) measure the density of cracks. Time variations in both ? and dt on volcanoes have been reported by ourselves and other workers. Here we report results from a new objective automatic technique, developed on Ruapehu, New Zealand and Asama, Japan. We also applied it to Okmok; Soufrière Hills; Aso; Unzen and Sakurajima. Thousands of measurements made on each volcano allow us to determine correlations with other volcano monitoring techniques. We examine volcano-tectonic earthquakes local to each volcano and more distant regional earthquakes. Seismic waves from local earthquakes travel solely through the volcano, so that anisotropy in the mantle or lower crustal mineral alignment will not affect the measurements, but care must be taken because earthquake locations and hence ray paths may change due to magma movement. Spatial changes are thus difficult to disentangle from temporal changes. We analyse families of earthquakes with near-identical waveforms to try to overcome this limitation. Deep regional earthquakes occur mostly in subducted plates and their paths are affected by mantle and lower crustal mineral anisotropy as well as by crustal stress. They are also affected by laterally varying properties, but earthquakes far removed from the volcano should not have systematic variations in location that are correlated with magma movement. Therefore, changes in measurements from regional events that correlate with magma movement can be interpreted as temporal rather than spatial variations. Common features at all volcanoes are that stations closest to the craters yield the fewest good measurements, and even those tend to give varying results at closely spaced stations. Scattering from the volcanic edifice may be making the S waves difficult to pick, and the local stresses may be varied. Stations on the volcanic flanks give many good measurements. Some stations yield variations in ? and dt that depend upon the earthquake location. But at most volcanoes, some stations show changes that are better explained by variations in time than in space. Where GPS measurements are available, the variations sometimes but not always correlate with previously-modeled inflation or deflation events and ? usually matches well with the stress field modelled from GPS-derived locations of magmatic sources. At Soufrière Hills variations in focal mechanisms correlate with variations in ?. The temporal variations in ? are large, ranging from 30? at some stations to 90? at other stations.

Savage, M. K.; Ohkura, T.; Umakoshi, K.; Shimizu, H.; Iguchi, M.; Johnson, J. H.; Ohminato, T.; Roman, D. C.

2009-12-01

389

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

390

Microbial Communities in Erupting Fluids from West Mata Volcano, Tonga Arc  

NASA Astrophysics Data System (ADS)

Eruptions provide unique opportunities for sampling the subseafloor microbial habitat due to the release of crustal fluids and microbes into the overlying water column via plumes and new diffuse vents. Work at mid-ocean ridges show that as post-eruption fluids evolve chemically, the subseafloor microbial communities also experience shifts in population structure and diversity. Timely sampling of plume and venting fluids is critical to understanding the microbial response to active volcanic eruptions, as well as resolving the relationship between stability and diversity. In response to eruption indicators observed in the water column during a November 2008 NOAA PMEL cruise, a multidisciplinary expedition funded by NSF and NOAA was mounted in May 2009 with the ROV Jason 2 to survey and observe eruption-related processes at West Mata volcano and the Northeast Lau Spreading Center (NELSC). While eruptive activity was not found at NELSC, explosive and effusive activity was found at W. Mata, located about 200 km southwest of Samoa at a depth of 1200 m. Diffuse venting and eruptive plumes were observed around the summit, and fluids were collected for cell counts, culturing, and DNA- and RNA-based analyses. Despite many vents having a pH of less than 3, all diffuse fluids contained cell concentrations elevated above background seawater, with large clumps of cells and filaments often present. Positive enrichments of anaerobic microbes, including thermophiles and hyperthermophiles, were obtained from a variety of vent and plume samples at 37, 55, 70, and 85 degrees Celsius. DNA- and RNA-based 16S rRNA clone libraries were built from all vent and plume samples. Results indicate that all sites are dominated by bacteria, but at relatively low diversity compared to other diffuse vent sites studied to date, suggesting that the microbial community may be at the early stages of development. Similar to other diffuse vents, most fluids hosted members of the mesophilic sulfur-oxidizing epsilon- and gamma- proteobacteria, although some putatively thermophilic bacteria were also recovered. The dominant genera found, Sulfurimonas spp., is also found at recently erupted fluids at NW Rota-1, a volcano of the Mariana Arc. A comparison of active (RNA-based) bacteria versus total bacteria (DNA-based) is on-going and indicates that many members of the bacterial community are active in the sampled fluids. All microbial data will be presented along with geochemical data to provide further insight into submarine volcanic-hosted ecosystems.

Huber, J. A.; Cantin, H.; Resing, J.; Butterfield, D. A.

2009-12-01

391

1994 Volcanic activity in Alaska: summary of events and response of the Alaska Volcano Observatory  

USGS Publications Warehouse

During 1994, the Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, or false alarms at nine volcanic centers-- Mount Sanford, Iliamna, the Katmai group, Kupreanof, Mount Veniaminof, Shishaldin, Makushin, Mount Cleveland and Kanaga (table 1). Of these volcanoes, AVO has a real time, continuously recording seismic network only at Iliamna, which is located in the Cook Inlet area of south-central Alaska (fig. 1). AVO has dial-up access to seismic data from a 5-station network in the general region of the Katmai group of volcanoes. The remaining unmonitored volcanoes are located in sparsely populated areas of the Wrangell Mountains, the Alaska Peninsula, and the Aleutian Islands (fig. 1). For these volcanoes, the AVO monitoring program relies chiefly on receipt of pilot reports, observations of local residents and analysis of satellite imagery.

Neal, Christina A.; Doukas, Michael P.; McGimsey, Robert G.

1995-01-01

392

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

393

Jurassic submarine arc-apron deposits and associated magma/wet-sediment interaction, northern Sierra Nevada, California  

NASA Astrophysics Data System (ADS)

Jurassic metavolcanic rocks of the Northern Sierra terrane in northern California are part of an extensive Triassic-Jurassic arc constructed along the western margin of North America. In the English Mountain area, Nevada and Sierra Counties, a well-exposed volcaniclastic sequence 3.6 km thick records Jurassic island-arc activity in a submarine environment. In the lower part of the sequence, thinly bedded andesitic volcanic sandstone turbidites and mudstones of the Lower to Middle Jurassic Sailor Canyon Formation were deposited below storm wave base in a long-lived marine basin. This unit is overlain conformably by the Middle Jurassic Tuttle Lake Formation, which records rapid accumulation of coarse-grained, calc-alkaline volcanic debris in the proximal parts of a submarine apron around a major volcano that developed within the earlier Sailor Canyon basin. The formation consists primarily of massively bedded, matrix-supported, polymict, basaltic to andesitic volcanic breccias deposited from submarine debris flows. Intercalated pillow-hyaloclastite breccias formed during local extrusion of lavas on the seafloor. Numerous intrusions cut the sequence and are petrographically and chemically identical to clasts in the debris-flow deposits. Peperite occurs along intrusion margins and as abundant isolated pockets, indicating intrusion of magma into wet, unconsolidated sediments. Elongate intrusive pods to 13.6 m in length are associated with smaller intrusive pillows and are inferred to represent a network of feeder tubes that extended from larger, coherent intrusions and supplied magma to complex zones of magma/wet-sediment interaction at shallow levels beneath the seafloor. Syndepositional intrusive activity of this type, including formation of abundant peperite, probably is a characteristic feature of submarine volcaniclastic sequences developed in proximal island-arc settings.

Templeton, Jeffrey H.; Hanson, Richard E.

2003-12-01

394

Turbidity currents and submarine morphodynamics River, Coastal and Estuarine Morphodynamics: RCEM 2005 Parker & Garca (eds)  

E-print Network

Turbidity currents and submarine morphodynamics #12;#12;River, Coastal and Estuarine Morphodynamics Submarine channels systems are the conduits that allow turbidity currents to transport and deposit mate

Lajeunesse, Eric

395

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

396

Distribution and characters of the mud diapirs and mud volcanoes off southwest Taiwan  

NASA Astrophysics Data System (ADS)

In order to identify the mud diapirs and mud volcanoes off SW Taiwan, we have examined ?1500 km long MCS profiles and related marine geophysical data. Our results show ten quasi-linear mud diapirs, oriented NNE-SSW to N-S directions. Thirteen mud volcanoes are identified from the multibeam bathymetric data. These mud volcanoes generally occur on tops of the diapiric structures. Moreover, the active mud flow tracks out of mud volcanoes MV1, MV3 and MV6 are observed through the high backscatter intensity stripes on the sidescan sonar images. The heights of the cone-shaped mud volcanoes range from 65 m to 345 m, and the diameters at base from 680 m to 4100 m. These mud volcanoes have abrupt slopes between 5.3° and 13.6°, implying the mudflow is active and highly viscous. In contrast, the flat crests of mud volcanoes are due to relative lower-viscosity flows. The larger cone-shaped mud volcanoes located at deeper water depths could be related to a longer eruption history. The formation of mud diapirs and volcanoes in the study area are ascribed to the overpressure in sedimentary layers, compressional tectonic forces and gas-bearing fluids. Especially, the gas-bearing fluid plays an important role in enhancing the intrusion after the diapirism as a large amount of gas expulsions is observed. The morphology of the upper Kaoping Slope is mainly controlled by mud diapiric intrusions.

Chen, Song-Chuen; Hsu, Shu-Kun; Wang, Yunshuen; Chung, San-Hsiung; Chen, Po-Chun; Tsai, Ching-Hui; Liu, Char-Shine; Lin, Hsiao-Shan; Lee, Yuan-Wei

2014-10-01

397

AI Planning for Robotic Submarine Exploration  

E-print Network

Overview 1. Oceanography Black smokers Vent prospecting 2. PhD Research Problem definition Mapping Vents Sea-floor "volcanoes" Mineral-rich superheated water (350°C) Photos © WHOI and Dana Yoerger 3 1. Oceanography Black smokers Vent prospecting 2. PhD Research Problem definition Mapping

Yao, Xin

398

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

399

Haines - Scagway Submarine Cable Intertie Project, Haines to Scagway, Alaska Final Technical and Construction Report  

SciTech Connect

The Haines to Skagway submarine cable project is located n Taiya Inlet, at the north end of Lynn Canal, in Southeast Alaska. The cable is approximately 15 miles long, with three landings and splice vaults. The cable is 35 kV, 3-Phase, and armored. The cable interconnects the Goat Lake Hydro Project near Skagway with the community of Haines. Both communities are now on 100% hydroelectric power. The Haines to Skagway submarine cable is the result of AP&T's goal of an alternative, economic, and environmentally friendly energy source for the communities served and to eliminate the use of diesel fuel as the primary source of energy. Diesel units will continue to be used as a backup system.

Alan See; Bennie N. Rinehart; Glen Marin

1998-11-01

400

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