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1

Submarine volcanoes along the Aegean volcanic arc  

NASA Astrophysics Data System (ADS)

The Aegean volcanic arc has been investigated along its offshore areas and several submarine volcanic outcrops have been discovered in the last 25 years of research. The basic data including swath bathymetric maps, air-gun profiles, underwater photos and samples analysis have been presented along the four main volcanic groups of the arc. The description concerns: (i) Paphsanias submarine volcano in the Methana group, (ii) three volcanic domes to the east of Antimilos Volcano and hydrothermal activity in southeast Milos in the Milos group, (iii) three volcanic domes east of Christiana and a chain of about twenty volcanic domes and craters in the Kolumbo zone northeast of Santorini in the Santorini group and (iv) several volcanic domes and a volcanic caldera together with very deep slopes of several volcanic islands in the Nisyros group. The tectonic structure of the volcanic centers is described and related to the geometry of the arc and the neotectonic graben structures that usually host them. The NE-SW direction is dominant in the Santorini and Nisyros volcanic groups, located at the eastern part of the arc, where strike-slip is also present, whereas NW-SE direction dominates in Milos and Methana at the western part, where co-existence of E-W disrupting normal faults is observed. The volcanic relief reaches 1100-1200 m in most cases. This is produced from the outcrops of the volcanic centers emerging usually at 400-600 m depth and ending either below sea level or at high altitudes of 600-700 m on the islands. Hydrothermal activity at relatively high temperatures observed in Kolumbo is remarkable whereas low temperature phenomena have been detected in the Santorini caldera around Kameni islands and in the area southeast of Milos. In Methana and Nisyros, hydrothermal activity seems to be limited in the coastal areas without other offshore manifestations.

Nomikou, Paraskevi; Papanikolaou, Dimitrios; Alexandri, Matina; Sakellariou, Dimitris; Rousakis, Grigoris

2013-06-01

2

Submarine growth and internal structure of ocean island volcanoes based on submarine observations of Mauna Loa volcano, Hawaii  

NASA Astrophysics Data System (ADS)

A recent model for the submarine growth of Hawaiian volcanoes indicates that these volcanoes are composed mainly of fragmental lava debris formed as lavas enter the ocean. This model has major implications for locating earthquake hypocenters and for the landslide hazard potential of these and other ocean island volcanoes. Observations from submersible dives and analyses of volcanic glasses collected from the western submarine flank of Mauna Loa indicate that subaerially erupted pillow lavas are abundant at depths of 950 to 1900 m below sea level. Fragmental lava is an important component of ocean island volcanoes, as witnessed during the most recent eruption of Kilauea volcano, but probably is the dominant lithology only in the upper 1 km of the submarine section. A submarine dike complex was discovered 17 km west of the assumed axis of Mauna Loa's southwest rift, which indicates that its intrusive complex is much broader than previously suspected (˜20 km vs. ˜8 km). The great width of this dike complex may be a consequence of crustal unloading following the South Kona landslide or a normal feature of Hawaiian rift zones that was previously unrecognized.

Garcia, Michael O.; Davis, Michael G.

2001-02-01

3

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

4

Worldwide distribution of submarine mud volcanoes and associated gas hydrates  

Microsoft Academic Search

The list of known and inferred submarine mud volcanoes is presented in this paper. They occur worldwide on shelves, continental and insular slopes and in the abyssal parts of inland seas. Submarine mud volcanoes are distributed on the Earth more extensively than their subaerial analogs. The estimated total number of known and inferred deep-water mud volcanoes is 103–105. There are

A. V Milkov

2000-01-01

5

Voluminous submarine lava flows from Hawaiian volcanoes  

SciTech Connect

The GLORIA long-range sonar imaging system has revealed fields of large lava flows in the Hawaiian Trough east and south of Hawaii in water as deep as 5.5 km. Flows in the most extensive field (110 km long) have erupted from the deep submarine segment of Kilauea's east rift zone. Other flows have been erupted from Loihi and Mauna Loa. This discovery confirms a suspicion, long held from subaerial studies, that voluminous submarine flows are erupted from Hawaiian volcanoes, and it supports an inference that summit calderas repeatedly collapse and fill at intervals of centuries to millenia owing to voluminous eruptions. These extensive flows differ greatly in form from pillow lavas found previously along shallower segments of the rift zones; therefore, revision of concepts of volcano stratigraphy and structure may be required.

Holcomb, R.T.; Moore, J.G.; Lipman, P.W.; Belderson, R.H.

1988-05-01

6

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

7

A Submarine Perspective on Hawaiian Volcanoes  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

8

Earthquakes of Loihi submarine volcano and the Hawaiian hot spot.  

USGS Publications Warehouse

Loihi is an active submarine volcano located 35km S of the island of Hawaii and may eventually grow to be the next and S most island in the Hawaiian chain. The Hawaiian Volcano Observatory recorded two major earthquake swarms located there in 1971-1972 and 1975 which were probably associated with submarine eruptions or intrusions. The swarms were located very close to Loihi's bathymetric summit, except for earthquakes during the second stage of the 1971-1972 swarm, which occurred well onto Loihi's SW flank. The flank earthquakes appear to have been triggered by the preceding activity and possible rifting along Loihi's long axis, similar to the rift-flank relationship at Kilauea volcano. Other changes accompanied the shift in locations from Loihi's summit to its flank, including a shift from burst to continuous seismicity, a rise in maximum magnitude, a change from small earthquake clusters to a larger elongated zone, a drop in b value, and a presumed shift from concentrated volcanic stresses to a more diffuse tectonic stress on Loihi's flank. - Author

Klein, F.W.

1982-01-01

9

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

E-print Network

submarine eruption. The youngest unit consists of 1­2 m diam- eter spheroids of rhyolite pumice, interpreted mineralization, Mariana Arc, pumice, Quaternary volcano, submarine caldera. INTRODUCTION The 3000-km long Izu

Stern, Robert J.

10

Mapping the sound field of an erupting submarine volcano using an acoustic glider  

E-print Network

Mapping the sound field of an erupting submarine volcano using an acoustic glider Haru Matsumoto a recently discovered erupting submarine volcano in the north- ern Lau basin. With the volcano providing recordings of an actively erupting submarine volcano were obtained at NW Rota-1 in the Mariana Arc. Chadwick

Bohnenstiehl, Delwayne

11

Fluid Flow Patterns in a Submarine Volcano: Simulating the Hydrothermal Evolution of Brothers Volcano  

NASA Astrophysics Data System (ADS)

Brothers volcano is part of the southern Kermadec intra-oceanic arc located northeast of New Zealand, and is one of the world’s best-studied active submarine volcanoes. It provides insight into the complex subseafloor hydrology of a submarine arc volcano with evidence for different stages in its magmatic-hydrothermal evolution [1]. The volcanic edifice comprises an elongated caldera surrounding an asymmetrically centered post-collapse cone. While hydrothermal venting at the NW caldera wall is focused and dates back to at least 1,200 years, hydrothermal discharge at the cone summit is diffuse and considered to be significantly younger. Recent studies of regional seismicity and local harmonic tremor at Brothers volcano imply the existence of a hydrothermal fluid reservoir underneath the area of the present cone [2]. Using a combined finite element - finite volume method, we have computed multi-phase mass and heat transport with a process simulation scheme based on realistic fluid properties. We have used correlations that describe phase stability relations in the binary NaCl-H2O system up to 1000°C [3]. Our earlier results of generic fluid flow simulations showed that water depth and seafloor topography, together with crustal permeability and the relative contributions of seawater and magmatic fluids, are first-order physical parameters controlling the fluid flow patterns and the style of hydrothermal venting. In our more recent simulations, we use available data from Brothers volcano, including detailed bathymetry, physical and chemical measurements from different vent sites and information on the size and location of the subseafloor magma chamber(s). The implementation of two distinct magmatic stages (i.e., pre-cone vs. post-cone) shows that the topography of the volcanic edifice, in combination with the location and size of an underlying magma chamber, play an important role in the style and evolution of the hydrothermal system. [1] de Ronde, C. E. J., et al. (2005) Evolution of a submarine magmatic-hydrothermal system: Brothers volcano, southern Kermadec arc, New Zealand. Economic Geology 100, p. 1097-1133. [2] Dziak, R. P., et al. (2008) Observations of regional seismicity and local harmonic tremor at Brothers volcano, south Kermadec arc, using an ocean bottom hydrophone array. Journal of Geophysical Research-Solid Earth 113, B08S04. [3] Driesner, T., and Heinrich, C. A. (2007) The system H2O-NaCl. Part I: Correlation formulae for phase relations in temperature-pressure-composition space from 0 to 1000 °C, 0 to 5000 bar, and 0 to 1 XNaCl. Geochimica Et Cosmochimica Acta 71, p. 4880-4901.

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

2010-12-01

12

Integrated volcanologic and petrologic analysis of the 1650 AD eruption of Kolumbo submarine volcano, Greece  

NASA Astrophysics Data System (ADS)

Kolumbo submarine volcano, located 7 km northeast of Santorini, Greece in the Aegean Sea, last erupted in 1650 AD. Submarine and subaerial explosive activity lasted for a period of about four months and led to the formation of thick (~ 250 m) highly stratified pumice deposits on the upper crater walls as well as extensive pumice rafts that were dispersed throughout the southern Aegean Sea. Subaerial tephra fallout from eruption columns that breached the surface occurred as far east as Turkey.

Cantner, Kathleen; Carey, Steven; Nomikou, Paraskevi

2014-01-01

13

A submarine canyon as the cause of a mud volcano Liuchieuyu Island in Taiwan  

E-print Network

A submarine canyon as the cause of a mud volcano Ð Liuchieuyu Island in Taiwan J. Chowa,*, J, we also discuss the relationship between a nearby submarine canyon (Kaoping Submarine Canyon¯ection; Submarine canyon; Mud volcano 1. Introduction In the early Pliocene, the paleoenvironment of the offshore

Lin, Andrew Tien-Shun

14

Seafloor seismic monitoring of an active submarine volcano: Local seismicity at Vailulu'u Seamount, Samoa  

E-print Network

Seafloor seismic monitoring of an active submarine volcano: Local seismicity at Vailulu'u Seamount'u; volcano; seismic monitoring; volcanic activity; submarine. Index Terms: 3025 Marine Geology and Geophysics of an active submarine volcano: Local seismicity at Vailulu'u Seamount, Samoa, Geochem. Geophys. Geosyst., 5, Q

Shearer, Peter

15

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

E-print Network

The submarine flanks of Anatahan Volcano, commonwealth of the Northern Mariana Islands William W flanks of Anatahan volcano were surveyed comprehensively for the first time in 2003 and 2004 that 67% of the volcano's submarine flanks are covered with volcaniclastic debris and 26% is lava flows

Chadwick, Bill

16

Dynamic Submarine Flanks of Hualalai Volcano, Hawaii  

NASA Astrophysics Data System (ADS)

Four remote and manned submersible dives examined the Hualalai midslope bench scarps, NW rift zone, and an elongate ridge cresting at 3900 mbsl during 2001 and 2002 JAMSTEC cruises. Here we report the results of stratigraphic, petrographic, and geochemical studies of the latter feature (dive S692). The ridge is 2x8 km, 300-700 m above datum, oriented parallel to the midslope bench, and 1 km east of the Mauna Loa Alika 2 landslide chute and levee deposit. Although the vast majority of the ridge is sediment covered, dive videos and sampling of the steep seaward side of the ridge revealed the following in-place lithologies, from base to crest: (1) bedded, landward dipping glass sandstones consisting of arcuate, angular to subangular glasses, moderately vesicular, tholeiitic and fairly uniform in composition, dominantly low in S, and intensely chemically altered toward the base, (2) olivine basalt breccia with fresh tholeiite glassy matrix, including S-rich grains, (3) dense olivine basalt lava blocks, (4) coarsely crystalline, vesicular, and oxidized lava, and (5) a capping unit of layered, volcaniclastic siltstone beds rich in radiolarians. Finally, an apron of talus and a superficial coating of muddy clastic materials drape the base of the ridge. Samples of this material are compositionally distinct from the in-place samples: they include transitional basalt and S-rich hawaiite. Key inferences about the ridge deposits are: (1) glass sands were produced as shield stage Hualalai lava erupted subaerially or in shallow water, (2) sands were cemented and overlain by breccia and lava blocks following minimal transport as grain flows to a depth that allowed incorporation of high-S grains; the entire sequence was transported to its current deep water location as a coherent package, (3) the zone of intense hydrothermal alteration and mineralization at the base is consistent with fluid flow in a region of distributed strain, possibly associated with gravitational spreading of Hualalai volcano, (4) the alkalic and transitional materials may represent pre-shield Hualalai volcanism. Alternatively, they could represent pre-shield Mauna Loa lavas excavated and transported to their present location by the Alika 2 landslide, which truncated the package, exposed the observed outcrop, and capped the sequence with fossiliferous glassy silt.

Hammer, J. E.; Shamberger, P. J.

2003-12-01

17

Submarine sand volcanos: experiments and numerical modelling  

NASA Astrophysics Data System (ADS)

Fluid overpressure at the bottom of a soil layer may generate fracturation in preferential paths for a cohesive material. But the case of sandy soils is rather different: a significant internal flow is allowed within the material and can potentially induce hydro-mechanical instabilities whose most common example is fluidization. Many works have been devoted to fluidization but very few have the issue of initiation and development of a fluidized zone inside a granular bed, prior entire fluidization of the medium. In this contribution, we report experimental results and numerical simulations on a model system of immersed sand volcanos generated by a localized upward spring of liquid, injected at constant flow-rate at the bottom of a granular layer. Such a localized state of fluidization is relevant for some industrial processes (spouted bed, maintenance of navigable waterways,…) and for several geological issues (kimberlite volcano conduits, fluid venting, oil recovery in sandy soil, More precisely, what is presented here is a comparison between experiments, carried out by direct visualization throughout the medium, and numerical simulations, based on DEM modelling of the grains coupled to resolution of NS equations in the liquid phase (LBM). There is a very good agreement between the experimental phenomenology and the simulation results. When the flow-rate is increased, three regimes are successively observed: static bed, fluidized cavity that does not extend to the top of the layer, and finally fluidization over the entire height of layer that creates a fluidized chimney. A very strong hysteretic effect is present here with an extended range of stability for fluidized cavities when flow-rate is decreased back. This can be interpreted in terms force chains and arches. The influences of grain diameter, layer height and injection width are studied and interpreted using a model previously developed by Zoueshtiagh [1]. Finally, growing rate of the fluidized zone and possible coupling between two distinct injection orifices are also discussed.

Philippe, P.; Ngoma, J.; Delenne, J.

2012-12-01

18

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

19

Environmental monitoring of El Hierro Island submarine volcano, by combining low and high resolution satellite imagery  

NASA Astrophysics Data System (ADS)

El Hierro Island, located at the Canary Islands Archipelago in the Atlantic coast of North Africa, has been rocked by thousands of tremors and earthquakes since July 2011. Finally, an underwater volcanic eruption started 300 m below sea level on October 10, 2011. Since then, regular multidisciplinary monitoring has been carried out in order to quantify the environmental impacts caused by the submarine eruption. Thanks to this natural tracer release, multisensorial satellite imagery obtained from MODIS and MERIS sensors have been processed to monitor the volcano activity and to provide information on the concentration of biological, chemical and physical marine parameters. Specifically, low resolution satellite estimations of optimal diffuse attenuation coefficient (Kd) and chlorophyll-a (Chl-a) concentration under these abnormal conditions have been assessed. These remote sensing data have played a fundamental role during field campaigns guiding the oceanographic vessel to the appropriate sampling areas. In addition, to analyze El Hierro submarine volcano area, WorldView-2 high resolution satellite spectral bands were atmospherically and deglinted processed prior to obtain a high-resolution optimal diffuse attenuation coefficient model. This novel algorithm was developed using a matchup data set with MERIS and MODIS data, in situ transmittances measurements and a seawater radiative transfer model. Multisensor and multitemporal imagery processed from satellite remote sensing sensors have demonstrated to be a powerful tool for monitoring the submarine volcanic activities, such as discolored seawater, floating material and volcanic plume, having shown the capabilities to improve the understanding of submarine volcanic processes.

Eugenio, F.; Martin, J.; Marcello, J.; Fraile-Nuez, E.

2014-06-01

20

Submarine venting of liquid carbon dioxide on a Mariana Arc volcano  

E-print Network

Submarine venting of liquid carbon dioxide on a Mariana Arc volcano John Lupton NOAA/Pacific Marine hydrothermal fluids, it is rarely found in the form of CO2 liquid. Here we report the discovery of an unusual CO2-rich hydrothermal system at 1600-m depth near the summit of NW Eifuku, a small submarine volcano

Chadwick, Bill

21

South Hachijyo Volcano -Initial Stage of Submarine Saldera Sctivity-  

NASA Astrophysics Data System (ADS)

South Hachijyo Volcano (SHV), a part of Northern Izu-Bonin Arc, is located between Hachijyojima Is. and Aogashima Is. SHV is composed of four blocks (somma) surrounding a bathymetric low. Each block is flat-topped and has a scarp with a gentle slope. The bathymetric low, encircled by the -400m contour line, extends vertically 160m to the top of the SHV. At the bottom of the bathymetric low lies a small depressional structure (caldera floor), which is approximately 2 km in diameter. At the middle of this structure lies a N-S trending central cone that is 1.3*0.9km in diameter and 100m high. We collected many dredge samples of pumice, basaltic fragments, and Q-diorite. Based on observations from a submersible, the sediments on the caldera floor consist of sorted pumice, unsorted pumice and coarse sand. Huge pumice blocks were observed near the slope of the central cone. Angular M-type pumice block and rhyolitic breccias were observed on the top of the central cone. Several rhyolitic volcanic cones (knolls) were observed around the central cone in the caldera floor. Therefore these rhyolitic fragments are associated with dome activities. The result of total geomagnetic analysis indicates that non-magnetic layer (about 600-900m thick) exists at the Hachijyo insular shelf (HIS). Non-magnetic layer in SHV covers magnetic basement, and the south part of it is shallower than the north part. Single-channel seismic records indicate that well-stratified layers (with a total thickness of 700m) exist at the HIS. These layers are corresponds to non-magnetic layer, and the thickness of these layers (interpreted as volcanic products from Hachijyojima Is.) decreases from Hachijyojima toward SHV. Therefore, the production of volcanic material from SHV has been small. Some crypt dome structures are observed under each block (somma). The seismic profiles show knolls atop the stratified somma and the caldera floor. From the geological and geophysical data, we interpret the following regarding the evolution of the SHV. Despite the fact that this volcanic structure is young, we observe morphology that suggests the existence of a caldera that is characterized by gentle slopes that are not well stratified. We interpret the relief between the caldera floor and the somma tops as having been caused by crypt dome intrusion that elevates the somma, rather than by depression of caldera floor after huge eruption. This interpretation is supported by the lack of voluminous volcanic product around the somma. In conclusion, we consider SHV to be in an initial stage of submarine caldera volcanism that is characterized by dike (knoll) complex activity without large volcanic eruptions.

Sakamoto, I.; Ishida, M.

2003-12-01

22

A Miocene submarine volcano at Low Layton, Jamaica  

NASA Astrophysics Data System (ADS)

A submarine fissure eruption of Upper Miocene age produced a modest volume of alkaline basalt at Low Layton, on the north coast of Jamaica. The eruption occurred in no more than a few hundred meters of water and produced a series of hyaloclastites, pillow breccias and pillow lavas, massive lavas, and dikes with an ENE en echelon structure. The volcano lies on the trend of one of the island's major E-W strike-slip fault zones; the Dunavale Fault Zone. The K-Ar age of the eruption of 9.5 plus or minus 0.5 Ma. B.P. corresponds to an extension of the Mid-Cayman Rise spreading center inferred from magnetic anomalies and bathymetry of the Cayman Trough to the north and west of Jamaica. The Low Layton eruption was part of the response of the strike-slip fault systems adjacent to this spreading center during this brief episode of tectonic readjustment.

Wadge, G.

23

A Miocene submarine volcano at Low Layton, Jamaica  

NASA Technical Reports Server (NTRS)

A submarine fissure eruption of Upper Miocene age produced a modest volume of alkaline basalt at Low Layton, on the north coast of Jamaica. The eruption occurred in no more than a few hundred meters of water and produced a series of hyaloclastites, pillow breccias and pillow lavas, massive lavas, and dikes with an ENE en echelon structure. The volcano lies on the trend of one of the island's major E-W strike-slip fault zones; the Dunavale Fault Zone. The K-Ar age of the eruption of 9.5 plus or minus 0.5 Ma. B.P. corresponds to an extension of the Mid-Cayman Rise spreading center inferred from magnetic anomalies and bathymetry of the Cayman Trough to the north and west of Jamaica. The Low Layton eruption was part of the response of the strike-slip fault systems adjacent to this spreading center during this brief episode of tectonic readjustment.

Wadge, G.

1982-01-01

24

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

25

Daily Variations of Methane Flux from Submarine Mud Volcanoes in Southwest Taiwan  

NASA Astrophysics Data System (ADS)

Submarine mud volcanoes are features that episodically emit gases, fluids, and mud onto the seafloor. Methane is the representative gas transport by mud volcanoes efficiently from deep buried sediment to the water column, and potentially to the atmosphere as a greenhouse gas. An active mud volcano, site-G96, located at the upper slope of southwest Taiwan, has plume from the top of mud volcano (360 m) direct to the sea surface. We can observe the bubbles at the sea surface. This study was conducted during cruise OR3-1693 in June 2013. To understand the activity of gas emissions of mud volcano, we utilized the 38kz echo sounder to scan back and forth over the site-G96 and obtained 53 acoustic images of plumes. Five water column samples were collected above the venting of G96 at the tidal maximum and minimum. Three gravity cores were taken at the mudflow site of G96. The results show high concentration of methane (38,522ul/l) and shallow depth of sulfate methane transition zone (~70cm) in the cored sediment profiles. The C1/(C2+C3) ratios from cored sediments are in the range of 29-392, indicating that the methane gas is mostly thermogenic in origin. Calculated areas of the plumes from echo sounder images show good correlation with the tide variations during the survey on 1st -2nd June 2013. Flux of methane from the water column to atmosphere can be estimated by diffusive exchange equation, showing that gas emission from an active mud volcano could be largely various (0.065, 3.426, 3.414, 0, 41.739umol m-2 d-1) from time to time, at least, in this study.

Yang, Tsung-Han; Yang, Tsanyao; Chen, Naichen; Lin, Saulwood; Wang, Pei-Ling

2014-05-01

26

Are midwater shrimp trapped in the craters of submarine volcanoes by hydrothermal venting?  

NASA Astrophysics Data System (ADS)

The biology of Kick'em Jenny (KEJ) submarine volcano, part of the Lesser Antilles volcanic arc and located off the coast of Grenada in the Caribbean Sea, was studied during a cruise in 2003. Hydrothermal venting and an associated biological assemblage were discovered in the volcanic crater (˜250 m depth). Warm water with bubbling gas emanated through rock fissures and sediments. Shrimp (some of them swimming) were clustered at vents, while other individuals lay immobile on sediments. The shrimp fauna consisted of 3 mesopelagic species that had no prior record of benthic or vent association. We suggest that these midwater shrimp, from deeper water populations offshore, were trapped within the crater during their downward diel vertical migration. It is unknown whether they then succumbed to the hostile vent environment (immobile individuals) or whether they are potentially opportunistic vent residents (active individuals). Given the abundance of submarine arc volcanoes worldwide, this phenomenon suggests that volcanic arcs could be important interaction sites between oceanic midwater and vent communities.

Wishner, Karen F.; Graff, Jason R.; Martin, Joel W.; Carey, S.; Sigurdsson, H.; Seibel, B. A.

2005-08-01

27

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

28

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

29

Hf, Pb, Sr, and Nd Isotope Geochemistry of Submarine Lavas from Hualalai Volcano, Hawaii  

NASA Astrophysics Data System (ADS)

The volcanoes of the Hawaiian islands are distributed in two parallel trends ('Loa' and 'Kea'), whose rocks are characterized by general geochemical differences. It is broadly accepted that Hawaiian plume is composed of several components, but the chemical structure of Hawaiian plume remains a matter of considerable debate. Hualalai volcano, the third youngest on the island of Hawaii and located on Loa trend, has been in the post shield alkalic stage for >100 ky. The study of the deep submarine ridges of this volcano has not been previously conducted. Many of submarine ridge lavas are older than any exposed on land, and extend our view of Hualalai magmatism back in time. To identify source materials involved in Hualalai ridge volcanism can provide constraints on the chemical structure of the Hawaiian plume. We analyzed Hf, Pb, Sr, Nd isotopic compositions and trace element contents of 16 lava samples from the submarine ridges of Hualalai. The samples were collected from North Kona region at 2700 - 3500 m water depth by 2001 Kaiko dive (K219) and at 2100 - 4500 m depth by 2002 Shinkai 6500 dives (S690, S692). It is considered that these samples are older than 105 ka, and are erupted at the pre-shield or shield stage of this volcano based on the stratigraphy and lithology. Isotopic compositions of the lavas have 87 Sr/86Sr ratios ranging from 0.703638 to 0.703813, 143Nd/144Nd from 0.512932 to 0.512946, 176Hf/177Hf from 0.2830988 to 0.2831234, 206Pb/204Pb from 18.1554 to 18.2663, 207Pb/204Pb from 15.4488 to 15.5518, and 208Pb/204Pb from 37.8661 to 38.2583. Hf, Nd, Sr isotopic compositions of the basalt samples are similar to, and overlap with the data previously reported for shield stage tholeiite from Hualalai and older tholeiite (>100ka) from Mauna Loa. Some of new Pb isotopic data have higher 207Pb/204Pb and 208Pb/204Pb, for a given 206Pb/204Pb, than published data from Mauna Loa and Hualalai. The results indicate that the Loa Pb isotope signature of the Hualalai source was present before 105 ka.

Yamasaki, S.; Kani, T.; Hanan, B. B.; Nohda, S.

2005-12-01

30

Imaging of CO2 bubble plumes above an erupting submarine volcano, NW Rota-1, Mariana Arc  

NASA Astrophysics Data System (ADS)

Rota-1 is a submarine volcano in the Mariana volcanic arc located ˜100 km north of Guam. Underwater explosive eruptions driven by magmatic gases were first witnessed there in 2004 and continued until at least 2010. During a March 2010 expedition, visual observations documented continuous but variable eruptive activity at multiple vents at ˜560 m depth. Some vents released CO2 bubbles passively and continuously, while others released CO2 during stronger but intermittent explosive bursts. Plumes of CO2 bubbles in the water column over the volcano were imaged by an EM122 (12 kHz) multibeam sonar system. Throughout the 2010 expedition numerous passes were made over the eruptive vents with the ship to document the temporal variability of the bubble plumes and relate them to the eruptive activity on the seafloor, as recorded by an in situ hydrophone and visual observations. Analysis of the EM122 midwater data set shows: (1) bubble plumes were present on every pass over the summit and they rose 200-400 m above the vents but dissolved before they reached the ocean surface, (2) bubble plume deflection direction and distance correlate well with ocean current direction and velocity determined from the ship's acoustic doppler current profiler, (3) bubble plume heights and volumes were variable over time and correlate with eruptive intensity as measured by the in situ hydrophone. This study shows that midwater multibeam sonar data can be used to characterize the level of eruptive activity and its temporal variability at a shallow submarine volcano with robust CO2 output.

Chadwick, William W.; Merle, Susan G.; Buck, Nathaniel J.; Lavelle, J. William; Resing, Joseph A.; Ferrini, Vicki

2014-11-01

31

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

E-print Network

Submarine sliver in North Kona: A window into the early magmatic and growth history of Hualalai rights reserved. Keywords: ocean islands; basalt; hawaiite; sulfur; submarine landslide; geochemistry 1. Introduction Interest in the processes affecting submarine flanks of Hawaiian volcanoes has grown in recent

Hammer, Julia Eve

32

Hydrothermal Helium Plumes over Submarine Volcanoes of the Marianas Arc  

Microsoft Academic Search

During February-March, 2003, as part of the Submarine Ring of Fire project funded by NOAA's Ocean Exploration Program, the R\\/V T.G. Thompson conducted a comprehensive survey of hydrothermal activity along 1200 km of the Mariana Arc from 13.5° N to 22.5° N [see Embley et al., EOS Trans. AGU, 2003]. Plume surveys were conducted in the water-column above ~50 submarine

J. E. Lupton; E. T. Baker; R. W. Embley; J. E. Resing; G. J. Massoth; K. Nakamura; R. Greene; S. Walker; G. Lebon

2003-01-01

33

Argon-40: Excess in submarine pillow basalts from Kilauea Volcano, Hawaii  

USGS Publications Warehouse

Submarine pillow basalts from Kilauea Volcano contain excess radiogenic argon-40 and give anomalously high potassium-argon ages. Glassy rims of pillows show a systematic increase in radiogenic argon-40 with depth, and a pillow from a depth of 2590 meters shows a decrease in radiogenic argon-40 inward from the pillow rim. The data indicate that the amount of excess radiogenic argon-40 is a direct function of both hydrostatic pressure and rate of cooling, and that many submarine basalts are not suitable for potassium-argon dating.

Brent, Dalrymple G.; Moore, J.G.

1968-01-01

34

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

NASA Astrophysics Data System (ADS)

Submarine 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

35

Acoustic response of submarine volcanoes in the Tofua Arc and northern Lau Basin to two great earthquakes  

NASA Astrophysics Data System (ADS)

Using a short-baseline hydrophone array, persistent volcanoacoustic sources are identified within the ambient noise field of the Lau Basin during the period between 2009 January and 2010 April. The submarine volcano West Mata and adjacent volcanic terrains, including the northern Matas and Volcano O, are the most active acoustic sources during the 15-month period of observation. Other areas of long-term activity include the Niua hydrothermal field, the volcanic islands of Hunga Ha'apai, Founalei, Niuatoputapu and Niuafo'ou, two seamounts located along the southern Tofua Arc and at least three unknown sites within the northern Lau Basin. Following the great Samoan earthquake on 2009 September 29, seven of the volcanoacoustic sources identified exhibit increases in the rate of acoustic detection. These changes persist over timescales of days-to-months and are observed up to 900 km from the earthquake hypocentre. At least one of the volcanoacoustic sources that did not respond to the 2009 Samoan earthquake exhibits an increase in detection rate following the great Mw 8.8 Chile earthquake that occurred at a distance of ˜9500 km on 2010 February 27. These observations suggest that great earthquakes may have undocumented impacts on Earth's vast submarine volcanic systems, potentially increasing the short-term flux of magma and volcanic gas into the overlying ocean.

Bohnenstiehl, DelWayne R.; Dziak, Robert P.; Matsumoto, Haru; Conder, James A.

2014-03-01

36

Predicting the Timing and Location of the next Hawaiian Volcano  

ERIC Educational Resources Information Center

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

Russo, Joseph; Mattox, Stephen; Kildau, Nicole

2010-01-01

37

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.

Joseph Russo

2010-01-01

38

Isotope Compositions of Submarine North Kona Tholeiitic Lavas, Hualalai Volcano, Hawaii  

NASA Astrophysics Data System (ADS)

Four remote and manned submersible dives examined the deep submarine portion of the North Kona region, offshore Hualalai during 2001 and 2002 JAMSTEC cruises. The dives encountered compositionally homogeneous tholeiitic pillow lavas that are interpreted to have erupted from Hualalai during its shield stage. Hualalai volcano, the westernmost volcano on the Island of Hawaii is presently in the post-shield alkalic stage and most of its subaerial surface is covered by alkalic basalt. Difficulty accessing buried tholeiite is one reason that compositional data from the volumetrically dominant stage in the volcano's edifice are scarce. To identify source materials involved in shield stage of Hualalai can provide important information about the isotopic variation and evolution during Hawaiian volcano growth. We report the results of Hf, Pb, Sr, Nd isotopic compositions of 34 tholeiitic lava samples collected from submarine North Kona region. Hf, Nd, Sr isotopic compositions of the submarine North Kona lavas are similar to Mauna Loa tholeiites, and define a clear mixing line showing that the mantle source consists of at least two components. Some of new Pb isotopic data have higher 207Pb/204Pb and ^{208}Pb/204Pb, for a given 206Pb/204Pb, than published data from Mauna Loa and Hualalai. The trend emerges towards to 'Kea'-like component. Although in general Hawaiian basalts require more than two components to account for their geochemical variations, the isotopic variations in Hualalai shield lavas appear dominated by a mixture of two components: 'Koolau'-like enriched component and a 'Kea'-like depleted component, and contributed to relatively higher proportion of the 'Kea'-like component than the Mauna Loa.

Yamasaki, S.; Tagami, T.; Kani, T.; Hanan, B. B.

2006-12-01

39

The acoustic response of submarine volcanoes in the Tofua Arc and northern Lau Basin following two great earthquakes in Samoa and Chile  

NASA Astrophysics Data System (ADS)

Using a correlation-based detector operating on data from a short-baseline hydrophone array, persistent volcano-acoustic sources are identified within the ambient noise field of the Lau Basin during the period between January 2009 and April 2010. The submarine volcano West Mata and adjacent volcanic terrains, including the northern Matas and Volcano O, are the most active acoustic sources during the 15-month period of observation. Other areas of long-term activity include the Niua hydrothermal field, the volcanic islands of Hunga-Ha'apai, Founalei, Niuatoputapu and Niuafo'ou, two unnamed seamounts located along the southern Tofua Arc, and at least three unknown sites within the northern Lau Basin. Following the great Samoan earthquake on 29 September of 2009, seven of the volcano-acoustic sources identified exhibit increases in the rate of acoustic detection. These changes persist over time scales of days-to-months and are observed up to 900 km from the earthquake hypocenter. At least one of the volcano-acoustic sources that did not respond to the 2009 Samoan earthquake exhibits an increase in detection rate following the great Mw 8.8 Chile earthquake that occurred at a distance of ~9,500 km on 27 February 2010. These observations suggest that great earthquakes may have undocumented impacts on Earth's vast submarine volcanic systems, potentially increasing the short-term flux of magma and volcanic gas into the overlying ocean.

Bohnenstiehl, D. R.; Dziak, R. P.; Matsumoto, H.; Conder, J. A.

2013-12-01

40

A large submarine sand-rubble flow on kilauea volcano, hawaii  

USGS Publications Warehouse

Papa'u seamount on the south submarine slope of Kilauea volcano is a large landslide about 19 km long, 6 km wide, and up to 1 km thick with a volume of about 39 km3. Dredge hauls, remote camera photographs, and submersible observations indicate that it is composed primarily of unconsolidated angular glassy basalt sand with scattered basalt blocks up to 1 m in size; no lava flows were seen. Sulfur contents of basalt glass from several places on the sand-rubble flow and nearby areas are low (< 240 ppm), indicating that the clastic basaltic material was all erupted on land. The Papa'u sandrubble flow was emplaced during a single flow event fed from a large near-shore bank of clastic basaltic material which in turn was formed as lava flows from the summit area of Kilauea volcano disintegrated when they entered the sea. The current eruptive output of the volcano suggests that the material in the submarine sand-rubble flow represents about 6000 years of accumulation, and that the flow event occurred several thousand years ago. ?? 1979.

Fornari, D.J.; Moore, J.G.; Calk, L.

1979-01-01

41

Submarine mass movements on continental margins HOMA J. LEE*, JACQUES LOCAT, PRISCILLA DESGAGNS, JEFFREY D. PARSONS,  

E-print Network

Submarine mass movements on continental margins HOMA J. LEE*, JACQUES LOCAT, PRISCILLA DESGAGNÉS **Institut de Ciències del Mar, Barcelona 08003, Spain ABSTRACT Submarine landslides can be important currents. Recent submarine land- slide research has: shown that landslides and sediment waves may generate

Lin, Andrew Tien-Shun

42

Submarine Location Estimation via a Network of Detection-Only Sensors  

E-print Network

Submarine Location Estimation via a Network of Detection-Only Sensors Shengli Zhou and Peter by the source/target receive-geometry and the target aspect can detect the return signal. Thus, submarines can. Traditional Approach and Low-Visibility Targets Submarine detection and localization is one major applica

Zhou, Shengli

43

Helium Isotopes of Fluids from Submarine Volcanoes in the South-Okinawa Trough  

NASA Astrophysics Data System (ADS)

Many active submarine volcanoes have been found in southern Okinawa Trough. Water column samples from the hydrothermal plumes above venting volcanoes were collected during the OR2-1897 and -1984 cruises. Meanwhile, diving at shallower depths were conducted several times to collect the water samples near the venting sites. In total, 122 water samples from various depths in the offshore area of NE Taiwan were collected for dissolved gases and helium isotopes measurement. The dissolved gases of water column samples show that the CO2 concentration and the alkalinity increase with depth and become higher at the bottom, while the result of O2 concentration shows a reverse pattern. The 3He/4He ratios near the vicinity of active Kueishantao volcano show highest value, up to 5.5 RA, where RA is the atmospheric ratios of 1.39 x 10-6. The plot of 3He/4He and 3He/20Ne ratios suggests that there may be different sources in this region. Furthermore, we will estimate the helium flux from the venting volcanoes in this area.

Hsin Kao, Li; Yang, Tsanyao Frank; Wen, Hsin-Yi; Chen, Ai-Ti; Lee, Hsiao-Fen

2014-05-01

44

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

45

Eruption-fed particle plumes and volcaniclastic deposits at a submarine volcano: NW Rota1, Mariana Arc  

Microsoft Academic Search

NW Rota-1 is an active submarine volcano in the Mariana Arc with a summit depth of 517 m and an explosively erupting volcanic vent southwest of the summit at a depth of 530–560 m. During a period of ongoing explosive eruptions, particle plumes surrounded the volcano and at least 3.3 × 107 m3 of volcaniclastic material was deposited on the

Sharon L. Walker; Edward T. Baker; Joseph A. Resing; William W. Chadwick; Geoffrey T. Lebon; John E. Lupton; Susan G. Merle

2008-01-01

46

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

47

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

PubMed Central

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 Fe3+-(hydrated)-oxyhydroxides in associated low-temperature iron mats are formed by anaerobic Fe2+-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

48

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

49

Submarine volcanoes of the Kolumbo volcanic zone NE of Santorini Caldera, Greece  

NASA Astrophysics Data System (ADS)

The seafloor northeast of Santorini volcano in Greece consists of a small, elongated rifted basin that has been the site of recent submarine volcanism. This area lies within the Cyclades back-arc region of the present Hellenic subduction zone where the seafloor of the eastern Mediterranean Sea is descending beneath the Aegean microplate. The Cycladic region and the Aegean Sea as a whole are known to be regions of north-south back-arc extension and thinning of continental crust. Nineteen submarine volcanic cones occur within this small rift zone, the largest of these being Kolumbo which last erupted explosively in 1650 AD, causing significant damage and fatalities on the nearby island of Santorini. Previous SEABEAM mapping and seismic studies from HCMR indicate that many of the smaller v'olcanic cones have been built above the present seafloor, while others are partly buried, indicating a range of ages for the activity along this volcanic line. None of the cones to the northeast of Kolumbo had been explored in detail prior to a cruise of the E/V Nautilus (NA007) in August 2010. The ROV Hercules was used to explore the slopes, summits and craters of 17 of the 19 centers identified on multibeam maps of the area. Water depths of the submarine volcano's summits ranged from 18 to 450 m. In general, the domes/craters northeast of Kolumbo were sediment covered and showed little evidence of recent volcanic activity. Outcrops of volcanic rock were found in the crater walls and slopes of some of the cones but they typically consisted of volcanic fragments of pumice and lava that have been cemented together by biological activity, indicative of the lack of recent eruptions. Geochemical analysis of samples collected on the northeast cones showed evidence of low temperature hydrothermal circulation on the summit and upper flanks in the form of stream-like manganese precipitates emanating from pits and fractures.

Nomikou, P.; Carey, S.; Papanikolaou, D.; Croff Bell, K.; Sakellariou, D.; Alexandri, M.; Bejelou, K.

2012-06-01

50

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

NASA Astrophysics Data System (ADS)

The North Kona slump is an elliptical region, about 20 by 60 km (1000-km 2 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 Hual?lai. 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.

2006-03-01

51

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

52

Submarine Volcaniclastic Deposits Associated with the Minoan Eruption of Santorini volcano, Greece  

NASA Astrophysics Data System (ADS)

The distribution of submarine volcaniclastic deposits has been studied in the Santorini volcanic field by a combination of seismic surveys using a ten cubic inch air-gun, sediment coring and ROV operations. A distinctive sediment sequence has been identified in the uppermost section of the seafloor surrounding Santorini. It is generally massive or chaotic with some irregular internal reflectors. The sequence extends more than 25 km to the west in the Christiana Basin, 22 km to the east in the Anafi Basin, and 28 km to the NE in the Anydros Basin. A mean thickness of about 29 meters is inferred from the seismic records, but is as high as 80 meters locally in areas near the coast of Santorini, where the Minoan pyroclastic flow deposit is up to 40 m thick on land. The sequence has been traced over an area of at least 1378 square kilometers on the sea floor. On the steep submarine slopes of the volcano the sequence often exhibits a terraced or step-like morphology that may reflect downslope creep or slumping during or just after deposition. The massive facies of the sequence was observed to transform abruptly into a laminated or well-bedded, and much thinner facies with distance from source, and with greater overall extent. In many cases this distal facies, which may consist of turbidites, extends beyond the area of the seismic survey lines, or more than 30 km from Santorini. ROV dives on the sediment sequence to the east of Santorini show that it consists of massive pyroclastic flow deposit. By analogy with the seismic character of submarine pyroclastic flows from the 1883 eruption of Krakatau we propose that the widespread sequence is related to the entrance of pyroclastic flows into the sea during the Minoan explosive eruption of Santorini (~3600 yrs. B.P.). A previous estimate of the volume of submarine pyroclastic flow deposits from the Minoan eruption was 20 cubic kilometers (dense rock equivalent, DRE) based on the fractionation of co-ignimbrite ash fall from the source flows. The volume of the newly mapped sequence around Santorini is estimated at 55 cubic kilometers. Conversion of that volume to DRE is sensitive to the assumption of sediment bulk density. New measurements of pumice-rich and lithic-rich submarine pyroclastic flow densities range from 1.5 to 1.85 g/cm3. This translates to a potential range of 20 to 34 km3 dense rock equivalent, if the whole sequence consists of juvenile pyroclastic flow material from the Minoan eruption.

Carey, S.; Sigurdsson, H.; 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

53

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

54

Origins of lithium in submarine mud volcano fluid in the Nankai accretionary wedge  

NASA Astrophysics Data System (ADS)

To investigate fluid regimes in the Nankai accretionary wedge, we estimated the temperatures of lithium (Li) reservoirs from the Li isotope ratio (7Li/6Li) in fluids recovered from Kumano mud volcano No. 5 (KMV#5) in the Nankai forearc basin. The 7Li/6Li ratios in the KMV#5 fluids are among the lightest reported from submarine mud volcanoes. The estimated Li reservoir temperatures (310 °C at maximum) were significantly higher than the smectite-to-illite conversion temperature (60-150 °C), whereas the temperature of fluid from the deeper Nankai décollement was estimated to be 150 °C at maximum. Data obtained from previous conductivity surveys across the trench suggest that there are two fluid reservoirs associated with distinct dehydration processes in the Nankai subduction zone. From these results, we inferred that the discontinuous mud diapirism in the Kumano forearc basin results from the periodic injection of deep-seated fluid accumulated in the corner of the serpentinized forearc mantle wedge that travels upward via a thrust fault. The intermittent upwelling of deep-seated fluid from the Nankai accretionary wedge due to periodic breaches of a low-permeability barrier above the fluid reservoir may be associated with seismogenic fault activity.

Nishio, Yoshiro; Ijiri, Akira; Toki, Tomohiro; Morono, Yuki; Tanimizu, Masaharu; Nagaishi, Kazuya; Inagaki, Fumio

2015-03-01

55

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

56

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

57

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

58

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

59

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

60

Slope failure and volcanic spreading along the submarine south flank of Kilauea volcano, Hawaii  

NASA Astrophysics Data System (ADS)

New multichannel reflection data and high-resolution bathymetry over the submarine slopes of Kilauea volcano provide evidence for current and prior landsliding, suggesting a dynamic interplay among slope failure, regrowth, and volcanic spreading. Disrupted strata along the upper reaches of Kilauea's flank denote a coherent slump, correlated with the active Hilina slump. The slump comprises mostly slope sediments, underlain by a detachment 3-5 km deep. Extension and subsidence along the upper flank is compensated by uplift and folding of the slump toe, which surfaces about midway down the submarine flank. Uplift of strata forming Papa`u seamount and offset of surface features along the western boundary of Kilauea indicate that the slump has been displaced ˜3 km in a south-southeast direction. This trajectory matches coseismic and continuous ground displacements for the Hilina slump block on land, and contrasts with the southeast vergence of the rest of the creeping south flank. To the northeast, slope sediments are thinned and disrupted within a recessed region of the central flank, demonstrating catastrophic slope failure in the recent past. Debris from the collapsed flank was shed into the moat in front of Kilauea, building an extensive apron. Seaward sliding of Kilauea's flank offscraped these deposits to build an extensive frontal bench. A broad basin formed behind the bench and above the embayed flank. Uplift and back tilting of young basin fill indicate recent, and possibly ongoing, bench growth. The Hilina slump now impinges upon the frontal bench; this buttress may tend to reduce the likelihood of future catastrophic detachment.

Morgan, Julia K.; Moore, Gregory F.; Clague, David A.

2003-09-01

61

Historical bathymetric charts and the evolution of Santorini submarine volcano, Greece  

NASA Astrophysics Data System (ADS)

Historical bathymetric charts are a potential resource for better understanding the dynamics of the seafloor and the role of active processes such as those associated with submarine faulting, landsliding, and magmatism. The UK Hydrographic Office, for example, has been involved in lead line measurements of seafloor depth since the early 1790s in a range of geological settings including ocean islands. Here, we report on an analysis of historical bathymetric charts in the region of Santorini volcano, Greece. Repeat lead line surveys in 1848, 1866 and 1928 and multibeam swath bathymetric surveys in 2001 and 2006 have been used to document changes in the depth of the seafloor in Santorini caldera. The data reveal that the flanks of the Kameni islands, a volcanic dome and dacitic lava complex in the caldera centre, have shallowed by up to 215 m and deepened by up to 60 m since 1848. The largest shallowing occurred between the 1866 and 1928 surveys and was accompanied by a significant increase in the surface area of the island of Nea Kameni, especially its southeast flank. Field observations by the French Geologist, F. A. Fouqué, during 1866-1870 suggest the shallowing is associated with the formation of the Giorgos and Aphroessa domes and their associated lava flows. Other shallowing probably occurred during 1925-1928 when lava flows filled the narrow strait between Nea Kameni and Mikra Kameni. The largest deepenings occurred between the 1928 and 2001 and 2006 surveys, on the shelf and slope of Nea Kameni. One possibility is that the deepening is caused by mass wasting due to large-scale slope failure and debris flow. Another is that it reflects a stress-induced viscoelastic relaxation of the crust following dome loading. Irrespective, the rates implied from the volumes and duration of the 19th century submarine magmatic activity are up to 0.11 km3/yr, which is significantly larger than rates inferred from mapping of surface lava flows.

Watts, A. B.; Nomikou, P.; Parks, M.; Smith, J.

2013-12-01

62

40Ar/39Ar geochronology of submarine Mauna Loa volcano, Hawaii  

NASA Astrophysics Data System (ADS)

A major impediment to our understanding of the nature and structure of the Hawaiian plume, and evaluating the competing plume models has been a lack of thick stratigraphic sections from which to obtain long temporal records of magmatic history. The Hawaii Scientific Drilling Project (HSDP) made a significant advance towards solving this problem by documenting the long-term magmatic evolution of Mauna Kea volcano on the Kea side of the plume. To evaluate comparable long-term magmatic history on the Loa side of the plume we collected a stratigraphically controlled sample suite using Jason and Pisces dives from three vertical transects of the 1.6 km high Kae Lae landslide scarp cut into Mauna Loa’s submarine southwest rift zone (SWR). We have undertaken an 40Ar/39Ar investigation of Mauna Loa’s growth history to integrate new geochronologic constraints with geochemical, and isotopic data, illuminating temporal trends within the Hawaiian plume. Obtaining precise 40Ar/39Ar ages from tholeiitic lavas younger than 500 ka containing only 0.2-0.6 wt.% K2O is challenging due to the extremely low radiogenic 40Ar contents. Furnace incremental heating experiments of groundmass separated from 15 submarine lavas have yielded four new age determinations (a 27% success rate). These four lavas give concordant age spectra with plateau and isochron ages that agree with stratigraphy. We also analyzed two previously-dated subaerial Mauna Kea tholeiites from the HSDP-2 drill core, to assess inter-laboratory reproducibility and calibrate our results to those obtained for the core. Two experiments on sample SR413-4.0 and one experiment from SR781-21.2 gave weighted mean plateau ages of 364 ± 95 ka and 473 ± 109, respectively, which are indistinguishable from the published 40Ar/39Ar ages of 390 ± 70 ka and 482 ± 67. Although Sharp and Renne (2005) preferred isochron ages for the submarine Mauna Kea tholeiites recovered from HSDP, we find that submarine Mauna Loa lavas contain trapped argon with a 40Ar/36Ar ratio that is indistinguishable from the atmospheric value of 295.5. Therefore, we consider the plateau ages to provide the most precise estimate of time elapsed since eruption. Lavas from 857, 1753, and 2112 mbsl give indistinguishable plateau ages of 473 ± 29, 463 ± 33, and 472 ± 107, respectively, implying an extraordinary period of lava accumulation. If correct, this implies that ~1300 m of lava was emplaced on the SWR at a rate far exceeding that proposed in previous accumulation models for Mauna Loa or Mauna Kea, possibly correlating with the peak of the shield-building stage. Three experiments from a more K-rich lava (0.67 wt. % K2O) near the top of the landslide scarp gave a weighted mean plateau age of 193 ± 16 ka, indicating a marked decline in eruption rates on this part of the SWR.

Jicha, B.; Rhodes, J. M.; Singer, B. S.; Vollinger, M. J.; Garcia, M. O.

2009-12-01

63

3104 IEEE TRANSACTIONS ON SIGNAL PROCESSING, VOL. 55, NO. 6, JUNE 2007 Submarine Location Estimation Via a  

E-print Network

3104 IEEE TRANSACTIONS ON SIGNAL PROCESSING, VOL. 55, NO. 6, JUNE 2007 Submarine Location by the source/target receive geometry, and the target aspect can detect the return signal. Thus, submarines can and missed detections. Index Terms--Active sonar, cross section, multistatic, sensor net- work, submarine

Zhou, Shengli

64

V. Lykousis, D. Sakellariou and J. Locat (eds.). Submarine Mass Movements and Their Consequences, 395-403. 2007 Springer.  

E-print Network

V. Lykousis, D. Sakellariou and J. Locat (eds.). Submarine Mass Movements and Their Consequences, 395- 403. © 2007 Springer. REVISITING SUBMARINE MASS MOVEMENTS ALONG THE U.S. ATLANTIC CONTINENTAL in the generation of tsunamis by submarine mass movements has warranted a reassessment of their distribution

ten Brink, Uri S.

65

40Ar/39Ar geochronology of submarine Mauna Loa volcano, Hawaii  

NASA Astrophysics Data System (ADS)

New geochronologic constraints refine the growth history of Mauna Loa volcano and enhance interpretations of the petrologic, geochemical, and isotopic evolution of Hawaiian magmatism. We report results of 40Ar/39Ar incremental heating experiments on low-K, tholeiitic lavas from the 1.6 km high Kahuku landslide scarp cutting Mauna Loa's submarine southwest rift zone, and from lavas in a deeper section of the rift. Obtaining precise40Ar/39Ar ages from young, tholeiitic lavas containing only 0.2-0.3 wt.% K2O is challenging due to their extremely low radiogenic 40Ar contents. Analyses of groundmass from 45 lavas yield 14 new age determinations (31% success rate) with plateau and isochron ages that agree with stratigraphic constraints. Lavas collected from a 1250 m thick section in the landslide scarp headwall were all erupted around 470 ± 10 ka, implying an extraordinary period of accumulation of ˜25 mm/yr, possibly correlating with the peak of the shield-building stage. This rate is three times higher than the estimated vertical lava accumulation rate for shield-building at Mauna Kea (8.6 ± 3.1 mm/yr) based on results from the Hawaii Scientific Drilling Project. Between ˜470 and 273 ka, the lava accumulation rate along the southwest rift zone decreased dramatically to ˜1 mm/yr. We propose that the marked reduction in lava accumulation rate does not mark the onset of post-shield volcanism as previously suggested, but rather indicates the upward migration of the magma system as Mauna Loa evolved from a submarine stage of growth to one that is predominantly subaerial, thereby cutting off supply to the distal rift zone. Prior to ˜250 ka, lavas with Loihi-like isotopic signatures were erupted along with lavas having typical Mauna Loa values, implying greater heterogeneity in the plume source earlier in Mauna Loa's growth. In addition to refining accumulation rates and the isotopic evolution of the lavas erupted along the southwest rift zone, our new40Ar/39Ar results constrain the eruption of the Ninole Basalts from 227 to 108 ka and provide maximum estimates on the timing of the Ka Lae and South Kona landslides.

Jicha, Brian R.; Rhodes, J. Michael; Singer, Brad S.; Garcia, Michael O.

2012-09-01

66

Timing and emplacement dynamics of newly recognised mass flow deposits at ~ 8-12 ka offshore Soufrière Hills volcano, Montserrat: How submarine stratigraphy can complement subaerial eruption histories  

NASA Astrophysics Data System (ADS)

This contribution describes two mass movement deposits (total volume ~ 0.5 km3) identified in seven marine cores located 8 to 15 km offshore southern Montserrat, West Indies. The deposits were emplaced in the last 35 ka and have not previously been recognised in either the subaerial or distal submarine records. Age constraints, provided by radiocarbon dating, show that an explosive volcanic eruption occurred at ca 8-12 ka, emplacing a primary eruption-related deposit that overlies a large (~ 0.3 km3) reworked bioclastic and volcaniclastic flow deposit, formed from a shelf collapse between 8 and 35 ka. The origin of these deposits has been deduced through the correlation of marine sediment cores, component analysis and geochemical analysis. The 8-12 ka primary volcanic deposit was likely derived from a highly-erosive pyroclastic flow from the Soufrière Hills volcano that entered the ocean and mixed with the water column forming a water-supported density current. Previous investigations of the eruption record suggested that there was a hiatus in activity at the Soufrière Hills volcano between 16 and 6 ka. The ca 8-12 ka eruptive episode identified here shows that this hiatus was shorter than previously hypothesised, and thus highlights the importance of obtaining an accurate and complete marine record of events offshore from volcanic islands and incorporating such data into eruption history reconstructions. Comparisons with the submarine deposit characteristics of the 2003 dome collapse also suggests that the ~ 8-12 ka eruptive episode was more explosive than eruptions from the current eruptive episode.

Cassidy, M.; Trofimovs, J.; Palmer, M. R.; Talling, P. J.; Watt, S. F. L.; Moreton, S. G.; Taylor, R. N.

2013-03-01

67

A decade of exploring a submarine intraplate volcano: Hydrothermal manganese and iron at L?'ihi volcano, Hawai'i  

Microsoft Academic Search

Decadal time series observations of hydrothermal fluid emissions from L?'ihi volcano were initiated in 1992 using a combination of submersible and shipboard sampling strategies. Magmatic-tectonic processes associated with a spectacular seismic event in July–August 1996 led to the collapse of Pele's Vents (31°C) near the volcano summit into a new pit crater (Pele's Pit) inundated by high-temperature (Tmax = 198°C)

Alexander Malahoff; Irina Ya. Kolotyrkina; Brian P. Midson; Gary J. Massoth

2006-01-01

68

Acoustic and tephra records of explosive eruptions at West Mata submarine volcano, NE Lau Basin  

NASA Astrophysics Data System (ADS)

West Mata is a 1200 m deep submarine volcano where explosive boninite eruptions were directly observed in May 2009. Here we present long-term acoustic and tephra records of West Mata explosion activity from three deployments of hydrophone and particle sensor moorings beginning on 8 January 2009. These records provide insights into the character of explosive magma degassing occurring at the volcano's summit vent until the decline and eventual cessation of the eruption during late 2010 and early 2011. The detailed acoustic records show three types of volcanic signals, 1) discrete explosions, 2) diffuse explosions, and 3) volcanic tremor. Discrete explosions are short duration, high amplitude broad-band signals caused by rapid gas bubble release. Diffuse signals are likely a result of 'trap-door' explosions where a quench cap of cooled lava forms over the magmatic vent but gas pressure builds underneath the cap. This pressure eventually causes the cap to breach and gas is explosively released until pressure reduces and the cap once again forms. Volcanic tremor is typified by narrow-band, long-duration signals with overtones, as well as narrow-band tones that vary frequency over time between 60-100 Hz. The harmonic tremor is thought to be caused by modulation of rapid, short duration gas explosion pulses and not a magma resonance phenomenon. The variable frequency tones may be caused by focused degassing or hydrothermal fluid flow from a narrow volcanic vent or conduit. High frequency (>30 Hz) tremor-like bands of energy are a result of interference caused by multipath wide-band signals, including sea-surface reflected acoustic phases, that arrive at the hydrophone with small time delays. Acoustic data suggest that eruption velocities for a single explosion range from 4-50 m s-1, although synchronous arrival of explosion signals has complicated our efforts to estimate long-term gas flux. Single explosions exhibit ~4-40 m3 s-1 of total volume flux (gas and rock) but with durations of only 20-30 ms. Interestingly, explosion activity increased at West Mata for several months, observed at more distant hydrophone stations, following the September 2009 8.1 Mw Samoan earthquake. The tephra and hydrophone data were only synchronously recorded from January to May 2010, but these data indicate a repeated record of summit explosions followed by down flank debris flows, an important process in the construction of the volcanic edifice. Bathymetric differencing between 2010 and 2011 shows two large negative anomalies at the summit and a broad positive anomaly on the east flank, interpreted as a major slump that removed part of the summit during the final magma withdrawal related to formation of the summit pit crater.

Dziak, R. P.; Bohnenstiehl, D. R.; Baker, E. T.; Matsumoto, H.; Caplan-Auerbach, J.; Mack, C. J.; Embley, R. W.; Merle, S. G.; Walker, S. L.; Lau, T. A.

2013-12-01

69

The Hilina Slump: Consequences of Slope Failure and Volcanic Spreading Along the Submarine South Flank of Kilauea Volcano, HI  

NASA Astrophysics Data System (ADS)

Kilauea volcano is the type locale to study the dynamic interplay between slope failure and volcanic spreading; this was recognized very early by Jim Moore and colleagues. New geophysical data and seafloor mapping in the area now better resolve the dramatic history of Kilauea volcano. In this seismically active setting, the interface between the oceanic crust and volcanic edifice accommodates seaward sliding of the south flank of Kilauea, probably rooted along Kilauea's East Rift Zone. Present day displacement of the south flank is punctuated by intermittent movement of the Hilina slump, defined by a set of arcuate normal faults that break the flank just downslope of Kilauea's summit. Analysis of recent multichannel seismic (MCS) data and high-resolution bathymetry over the submarine slopes of Kilauea volcano reveals that the active slump has a relatively shallow detachment, 3-5 km deep, comprises largely slope sediments, and is restricted to the upper northwestern portion of the mobile south flank. Offset morphologic features along the marginal ridge known as Papa'u seamount, constrain measurable downslope displacement of the slump to ~3 km, directed oblique to its western boundary. The MCS data also reveal the buried scar of a large-scale slope failure to the northeast of the submarine Hilina slump, which is the probable source of thick deposits of volcaniclastic breccias presently contained within the frontal midslope bench. The midslope bench developed as the mobile south flank of Kilauea plowed seaward into and offscraped the landslide debris, trapping a broad basin above the landslide scar. Uplift and back-tilting of young basin fill indicate recent, and possibly ongoing, bench growth. The Hilina slump now impinges upon this frontal bench, a buttress that may tend to reduce the likelihood of future catastrophic detachment of the landslide.

Morgan, J. K.; Moore, G. F.; Clague, D. A.

2003-12-01

70

High-Resolution Distribution of Temperature, Particle and Oxidation/Reduction Potential Anomalies From a Submarine Hydrothermal System: Brothers Volcano, Kermadec Arc  

NASA Astrophysics Data System (ADS)

The complex relationships between geological setting and hydrothermal venting have, to date, largely been explored with ship-based surveys that effectively examine regional relationships, or with remotely operated vehicles (ROV) and manned submersibles which allow close examination of individual vent fields. Higher- resolution surveys than are possible with ship-based techniques and broader surveys than are practical with ROVs and manned submersibles are necessary for more thoroughly understanding hydrothermal systems and their impact on ocean ecosystems. Autonomous vehicles (AUVs), such as the WHOI Autonomous Benthic Explorer (ABE) can be programmed to conduct high-resolution surveys that systematically cover a broad area of seafloor. Brothers volcano, a hydrothermally active submarine caldera volcano located on the Kermadec arc northwest of New Zealand, was surveyed in July-August 2007 using ABE. Brothers caldera is ~3 km in diameter with a floor depth of 1850 m and walls that rise 290-530 m above the caldera floor. A dacite cone with a summit depth of ~1200 m sits within the caldera, partially merging with the southern caldera wall. Prior to the survey, active hydrothermal vents were known to be perched along the NW caldera wall and located at three sites on the cone. The enclosed caldera, presence of known vent fields with differing geochemical characteristics, and existence of at least one currently inactive site made Brothers volcano an ideal site for a high-resolution survey to explore in greater detail the mass, thermal and geochemical exchanges of hydrothermal systems. During our expedition, the caldera walls and dacite cone (~7 km2) were completely surveyed by ABE with 50-60 m trackline spacing at an altitude of 50 m above the seafloor. Hydrothermal plumes were mapped with ABE's integrated CTD (conductivity- temperature-depth) and sensors measuring optical backscatter (particle concentrations) and oxidation- reduction potential (ORP; indicating the presence of reduced chemical species). This survey resulted in the first high-resolution map of temperature, particle and ORP anomalies within a hydrothermally active submarine caldera. New details about the extent and structure of the known active vent fields were revealed, and a new area of active venting was discovered along the west caldera wall. Additionally, relationships between source vents, buoyant plumes, and neutrally buoyant regional plumes mapped using standard surface ship methods can be compared. Simultaneously acquired bathymetry and magnetic anomaly data show correlations between the geomorphology of the caldera, magnetic alterations and patterns of past and present hydrothermal venting.

Walker, S. L.; Baker, E. T.; de Ronde, C. E.; Yoerger, D.; Embley, R. W.; Davy, B.; Merle, S. G.; Resing, J. A.; Nakamura, K.

2008-12-01

71

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

72

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

73

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

PubMed Central

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

74

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.

Fraile-Nuez, Eugenio; Magdalena Santana-Casiano, J.; González-Dávila, Melchor

2014-05-01

75

Viral infections stimulate the metabolism and shape prokaryotic assemblages in submarine mud volcanoes.  

PubMed

Mud volcanoes are geological structures in the oceans that have key roles in the functioning of the global ecosystem. Information on the dynamics of benthic viruses and their interactions with prokaryotes in mud volcano ecosystems is still completely lacking. We investigated the impact of viral infection on the mortality and assemblage structure of benthic prokaryotes of five mud volcanoes in the Mediterranean Sea. Mud volcano sediments promote high rates of viral production (1.65-7.89 × 10(9) viruses g(-1) d(-1)), viral-induced prokaryotic mortality (VIPM) (33% cells killed per day) and heterotrophic prokaryotic production (3.0-8.3 ?gC g(-1) d(-1)) when compared with sediments outside the mud volcano area. The viral shunt (that is, the microbial biomass converted into dissolved organic matter as a result of viral infection, and thus diverted away from higher trophic levels) provides 49 mgC m(-2) d(-1), thus fuelling the metabolism of uninfected prokaryotes and contributing to the total C budget. Bacteria are the dominant components of prokaryotic assemblages in surface sediments of mud volcanoes, whereas archaea dominate the subsurface sediment layers. Multivariate multiple regression analyses show that prokaryotic assemblage composition is not only dependant on the geochemical features and processes of mud volcano ecosystems but also on synergistic interactions between bottom-up (that is, trophic resources) and top-down (that is, VIPM) controlling factors. Overall, these findings highlight the significant role of the viral shunt in sustaining the metabolism of prokaryotes and shaping their assemblage structure in mud volcano sediments, and they provide new clues for our understanding of the functioning of cold-seep ecosystems. PMID:22170423

Corinaldesi, Cinzia; Dell'Anno, Antonio; Danovaro, Roberto

2012-06-01

76

1891 Submarine eruption of Foerstner volcano (Pantelleria, Sicily) : insights into the vent structure of basaltic balloon eruptions  

NASA Astrophysics Data System (ADS)

Numerous shallow water basaltic eruptions have produced abundant floating scoria up to several meters in diameter, yet little is known about the conditions that give rise to this unusual style of volcanism. On October 17, 1891, a submarine eruption began 4 kilometers northwest of the island of Pantelleria, Sicily. The eruptive vent was located at a depth of 250 meters along the NW-SE trending Sicily Channel Rift Zone. Evidence for the eruption was provided by the occurrence of hot, scoriaceous lava "balloons" floating on the sea surface along a narrow line about 850-1000 meters long trending along the rift. These extremely vesicular fragments were spherical to ellipsoidal in shape and ranged from <50 to 250 cm in diameter. Remotely Operated Vehicles (ROVs) and existing bathymetric maps have been used to conduct the first detailed investigation of a vent site associated with this unique style of volcanism. In 2011 the ROV Hercules, deployed from the E/V Nautilus, explored the 1891 Foerstner vent using high definition video cameras and produced a high resolution bathymetric map of the area using a BlueView multibeam imaging sonar. Light backscattering and oxidation-reduction potential sensors (MAPRs) were added to Hercules to detect discharge from active venting. ROV video footage has been used in conjunction with the high resolution bathymetric data to construct a geologic map of the vent area based on a variety of facies descriptors, such as abundance of scoria bombs, occurrence of pillow or scoria flow lobes, extent of sediment cover, and presence of spatter-like deposits. Initial results of the mapping have shown that there are two main vents that erupted within the observed area of floating scoria and most likely erupted at the same time as evidenced by similar bulk chemical compositions of recovered samples. Scoria bomb beds and some scoria flow lobes largely cover the suspected main vent, located at a depth of 250 meters. Distinct pillow flow lobes cover the second, previously unknown vent located north of Foerstner volcano at a depth of around 350 meters. Given the close proximity of these two vents, the differences in deposit types may be due to changing eruption style as a function of water depth. The abundant pillow flow lobes observed at the northern vent are most likely the result of more effusive eruptions occurring in deeper water (350 m) whereas the dominantly fragmental nature of material in the main southern vent indicates more vigorous explosive activity at shallower levels (250 m). Based on the nature of deposits found at the vent areas, the basaltic balloons of the 1891 Foerstner eruption are suspected to be a result of both coarse, localized fire fountaining activity and detachment from gas-charged flow lobes. The larger and shallower southern vent area is likely to have been the main source of the basaltic balloons observed on the surface during the 1891 eruption. A review of other historic eruptions that have produced basaltic balloons suggests that this style of activity is likely to be restricted to a rather narrow range of water depths and thus recognition of the distinct deposits produced by this type of activity in ancient deposits could help place important paleodepth constraints on volcaniclastic sequences.

Kelly, J. T.; Carey, S.; Bell, K. L.; Rosi, M.; Marani, M.; Roman, C.; Pistolesi, M.; Baker, E. T.

2012-12-01

77

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

78

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 ...

Kailey Fucaloro

2009-09-15

79

SeaMARC 2 side-scan images of submarine volcanoes: Potential analogues for Venus  

NASA Technical Reports Server (NTRS)

The Earth's surface beneath the oceans may be very similar, in terms of ambient pressures, to the surface of Venus. For that reason it is particularly important for geologists studying the surface of Venus to understand the processes which form features on the floors of the oceans. With the SeaMARC 2 seafloor mapping system, it is possible to view a swath of seafloor that is 10 km wide (about 6.2 mi). Side scan images of the Mariana region show that volcanoes of the island arc are more complicated than previously realized and that features of the fore-arc region, which resemble volcanoes morphologically, may result from processes other than volcanism. By comparing data obtained from the ocean floor with radar images of Venus, the geological evolution of that planet may be more fully understood.

Fryer, P.; Hussong, D.; Mouginis-Mark, P. J.

1984-01-01

80

Two-dimensional simulations of explosive eruptions of Kick-em Jenny and other submarine volcanos  

Microsoft Academic Search

Kick-em Jenny, in the Eastern Caribbean, is a submerged volcanic cone that has erupted a dozen or more times since its discovery in 1939. The most likely hazard posed by this volcano is to shipping in the immediate vicinity (through volcanic missiles or loss-of-buoyancy), but it is of interest to estimate upper limits on tsunamis that might be produced by

Galen R. Gisler; R. P. Weaver; Charles L. Mader; M. L. Gittings

2004-01-01

81

Complex magma storage and ascent at embryonic submarine volcanoes from the Madeira Archipelago  

NASA Astrophysics Data System (ADS)

The formation of magma chambers is a significant phase in the evolution of large oceanic intraplate volcanoes and has strong control on melt composition. There is, however, little information about the earliest magma chambers because the pre-shield stage of a volcano is difficult to access. Here we present thermobarometric data from embryonic seamounts near Madeira that provide us with the rare opportunity to sample the earliest stage of an oceanic island volcano. The erupted magmas indicate crystal fractionation in reservoirs ca. 500 1000 MPa (the upper 15 20 km of the mantle) and polybaric magma ascent including mixing events. Depths and degree of crystal fractionation during the pre-shield stage basically resemble the subaerial shield stage of Madeira. This contrasts with Pacific hotspot-islands such as Hawaii or Tahiti, where magma chambers of the pre-shield and shield stages are more distinct. We propose that the different manifestations of early hotspot volcanism are related to plate velocities controlling thermal gradients in the lithosphere. Because of slower plate velocity, the lithosphere is compositionally and thermally more uniform beneath Madeira than beneath Hawaii. This results in only minor rearrangements of the magma plumbing systems during evolution from the pre-shield to the shield stage.

Klügel, Andreas; Klein, Frieder

2006-05-01

82

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 ...

Mrs. Walls

2011-01-30

83

The Kolumbo submarine volcano of Santorini island is a large pool of bacterial strains with antimicrobial activity.  

PubMed

Microbes in hydrothermal vents with their unique secondary metabolism may represent an untapped potential source of new natural products. In this study, samples were collected from the hydrothermal field of Kolumbo submarine volcano in the Aegean Sea, in order to isolate bacteria with antimicrobial activity. Eight hundred and thirty-two aerobic heterotrophic bacteria were isolated and then differentiated through BOX-PCR analysis at the strain level into 230 genomic fingerprints, which were screened against 13 different type strains (pathogenic and nonpathogenic) of Gram-positive, Gram-negative bacteria and fungi. Forty-two out of 176 bioactive-producing genotypes (76 %) exhibited antimicrobial activity against at least four different type strains and were selected for 16S rDNA sequencing and screening for nonribosomal peptide (NRPS) and polyketide (PKS) synthases genes. The isolates were assigned to genus Bacillus and Proteobacteria, and 20 strains harbored either NRPS, PKS type I or both genes. This is the first report on the diversity of culturable mesophilic bacteria associated with antimicrobial activity from Kolumbo area; the extremely high proportion of antimicrobial-producing strains suggested that this unique environment may represent a potential reservoir of novel bioactive compounds. PMID:25627249

Bourbouli, Maria; Katsifas, Efstathios A; Papathanassiou, Evangelos; Karagouni, Amalia D

2015-05-01

84

Dive and Explore: An Interactive Exhibit That Simulates Making an ROV Dive to a Submarine Volcano, Hatfield Marine Science Visitor Center, Newport, Oregon  

NASA Astrophysics Data System (ADS)

We have created a new interactive exhibit in which the user can sit down and simulate that they are 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. This new public display is located at the Hatfield Marine Science Visitor Center in Newport, Oregon. The exhibit is designed to look like the real ROPOS control console and includes three video monitors, a PC, a DVD player, an overhead speaker, graphic panels, buttons, lights, dials, and a seat in front of a joystick. 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. The user can choose between 1 of 3 different dives sites in the caldera of Axial Volcano. 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 joystick. 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. The user can then choose a different dive or make the same dive again. 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. The exhibit software was created with Macromedia Director using Apple Quicktime and Quicktime VR. The exhibit is based on the NeMO Explorer web site (http://www.pmel.noaa.gov/vents/nemo/explorer.html).

Weiland, C.; Chadwick, W. W.; Hanshumaker, W.; Osis, V.; Hamilton, C.

2002-12-01

85

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

86

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

87

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

88

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

89

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

90

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.

91

The Submarine Volcano Eruption off El Hierro Island: Effects on the Scattering Migrant Biota and the Evolution of the Pelagic Communities  

PubMed Central

The submarine volcano eruption off El Hierro Island (Canary Islands) on 10 October 2011 promoted dramatic perturbation of the water column leading to changes in the distribution of pelagic fauna. To study the response of the scattering biota, we combined acoustic data with hydrographic profiles and concurrent sea surface turbidity indexes from satellite imagery. We also monitored changes in the plankton and nekton communities through the eruptive and post-eruptive phases. Decrease of oxygen, acidification, rising temperature and deposition of chemicals in shallow waters resulted in a reduction of epipelagic stocks and a disruption of diel vertical migration (nocturnal ascent) of mesopelagic organisms. Furthermore, decreased light levels at depth caused by extinction in the volcanic plume resulted in a significant shallowing of the deep acoustic scattering layer. Once the eruption ceased, the distribution and abundances of the pelagic biota returned to baseline levels. There was no evidence of a volcano-induced bloom in the plankton community. PMID:25047077

Ariza, Alejandro; Kaartvedt, Stein; Røstad, Anders; Garijo, Juan Carlos; Arístegui, Javier; Fraile-Nuez, Eugenio; Hernández-León, Santiago

2014-01-01

92

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

93

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

94

Volcanoes  

NSDL National Science Digital Library

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

2005-12-17

95

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.

96

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

97

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.

Scott Johnson

98

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.

Jaffe, Todd

2012-01-01

99

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 of numerous submarine landslides in French Polynesia. This inventory shows an evolution of the landslide type with the age of oceanic islands. Submarine active volcanoes are subject to superficial landslides of fragmental

Clouard, Valerie

100

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

101

Distribution of trace elements including tellurium, gallium, indium, and select REE in sulfide chimneys from Brothers submarine volcano, Kermadec arc  

NASA Astrophysics Data System (ADS)

Brothers volcano is a dacitic volcano located along the Kermadec arc, New Zealand, and hosts the NW Caldera hydrothermal vent field perched on part of the steep caldera walls. The field strikes for ~600 m between depths of 1550 and 1700 m and includes numerous, active, high-temperature (max 302°C) chimneys and even more dead, sulfide-rich spires. Chimney samples collected from Brothers show distinct mineralogical zonation reflecting gradients in oxidation state, temperature, and pH from the inner walls in contact with hydrothermal fluids through to the outer walls in contact with seawater. Minerals deposited from hotter fluids (e.g., chalcopyrite) are located in the interior of the chimneys and are surrounded by an external zone of minerals deposited by cooler fluids (e.g., sulfates, sphalerite). Four chimneys types are identified at Brothers volcano based on the relative proportions of chalcopyrite and sulfate layers, and the presence or absence of anhydrite. Two are Cu-rich, i.e., chalcopyrite-rich and chalcopyrite-bornite-rich chimneys, and two are Zn-rich, i.e., sphalerite-rich and sphalerite-chalcopyrite-rich. Barite and anhydrite are common to both Cu-rich chimney types whereas Zn-rich chimneys contain barite only. The main mineral phases in all the chimneys are anhydrite, barite, chalcopyrite, pyrite/marcasite, and sphalerite. Trace minerals include galena, covellite, tennantite, realgar, chalcocite, bornite, hematite, goethite, Pb-As sulfosalts, and Bi- or Au-tellurides. The vast majority of tellurides are <5 ?m in size, although columnar crystals up to 80 ?m long have been observed. The tellurides commonly form in bands, cluster in patches, or occur along internal grain boundaries within chalcopyrite. They also are found at the contact between chalcopyrite and pyrite grains. In sulfate layers adjacent to the chalcopyrite zones tellurides can occur as inclusions in anhydrite, barite or pyrite and/or occupy void space within the chimney. One Cu-rich chimney also contained native Te in a similar distribution as the tellurides. Whole rock geochemical analysis has determined the maximum concentration of trace elements and REE such as In (53.1 ppm), Ga (1870), Y (26), La (21.2), Ce (21), Sm (2.8), Gd (4), and Yb (3) in Brothers chimneys. To better understand the mineral associations and zonation of these and other trace elements within the chimney walls, we have undertaken element mapping on the four different chimneys types with both X-Ray fluorescence microscopy using synchrotron radiation and with Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS). For example, in a chalcopyrite-rich chimney visibly laminated chalcopyrite in the interior contains bands of Co, Mo, Ag, Te, Au, and Bi, whereas In, La, Ce, Ga, and Y are concentrated in other mineral phases towards the exterior. Element mapping allows us to better understand the physico-chemical gradients within chimney walls, as well as metal sources and transportation, and depositional processes.

Berkenbosch, H. A.; de Ronde, C. E.; McNeill, A.; Goemann, K.; Gemmell, J. B.

2011-12-01

102

Location and mechanism of very long period tremor during the 2008 eruption of Okmok Volcano  

E-print Network

Location and mechanism of very long period tremor during the 2008 eruption of Okmok Volcano from; published 6 October 2010. [1] We describe continuous, very long period (VLP) tremor that occurred during, the wave field of the VLP tremor is relatively free of path effects. From continuous recordings of the VLP

Barrash, Warren

103

An experiment to detect and locate lightning associated with eruptions of Redoubt Volcano  

USGS Publications Warehouse

A commercially-available lightning-detection system was temporarily deployed near Cook Inlet, Alaska in an attempt to remotely monitor volcanogenic lightning associated with eruptions of Redoubt Volcano. The system became operational on February 14, 1990; lightning was detected in 11 and located in 9 of the 13 subsequent eruptions. The lightning was generated by ash clouds rising from pyroclastic density currents produced by collapse of a lava dome emplaced near Redoubt's summit. Lightning discharge (flash) location was controlled by topography, which channeled the density currents, and by wind direction. In individual eruptions, early flashes tended to have a negative polarity (negative charge is lowered to ground) while late flashes tended to have a positive polarity (positive charge is lowered to ground), perhaps because the charge-separation process caused coarse, rapid-settling particles to be negatively charged and fine, slow-settling particles to be positively charged. Results indicate that lightning detection and location is a useful adjunct to seismic volcano monitoring, particularly when poor weather or darkness prevents visual observation. The simultaneity of seismicity and lightning near a volcano provides the virtual certainty that an ash cloud is present. This information is crucial for aircraft safety and to warn threatened communities of impending tephra falls. The Alaska Volcano Observatory has now deployed a permanent lightning-detection network around Cook Inlet. ?? 1994.

Hoblitt, R.P.

1994-01-01

104

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.

Erin Beutel

105

Volcanoes  

MedlinePLUS

... by authorities and evacuate immediately from the volcano area to avoid flying debris, hot gases, lateral blast and lava flow. Be aware of mudflows . The danger from a mudflow increases near stream channels and with ... and low-lying areas. Remember to help your neighbors who may require ...

106

The 2011 Eruption of Nabro Volcano (Eritrea): Earthquake Locations from a Temporary Broadband Network  

NASA Astrophysics Data System (ADS)

Nabro volcano dominates the central part of the Nabro Volcanic Range (NVR), which trends SSW-NNE covering a stretch of 110 km from the SEE margin of the Afar depression to the Red Sea. Regionally, the NVR sits within the Afar triangle, the triple junction of the Somalian, Arabian and African plates. On 12th June 2011 Nabro volcano suddenly erupted after being inactive for 10, 000 years. In response, a network of 8 seismometers, were located around the active vent. The seismic signals detected by this array and those arriving at a regional seismic station (located to the north-west) were processed to provide accurate earthquake locations for the period August-October. Transects of the volcano were used to create cross sections to aid the interpretation. Typically, the majority of the seismic events are located at the active vent and on the flanks of Nabro, with fewer events dispersed around the surrounding area. However, there appears to be a smaller hub of events to the south-west of Nabro beneath the neighbouring Mallahle volcanic caldera (located on the Ethiopian side of the international border). This may imply some form of co-dependent relationship within the plumbing of the magma system beneath both calderas.

Hamlyn, J.; Keir, D.; Hammond, J.; Wright, T.; Neuberg, J.; Kibreab, A.; Ogubazghi, G.; Goitom, B.

2012-04-01

107

Volcanoes: On-Line Edition  

NSDL National Science Digital Library

This is the on-line version of a general interest publication prepared by the United States Geological Survey (USGS). It provides a general introduction to volcanoes and volcanology. Topics include types of volcanoes; types of eruptions; submarine volcanoes; and features associated with volcanic terrains (geysers, hot springs, etc.). There is also discussion of volcanoes and their association to plate tectonics, extraterrestrial volcanoes, monitoring and research efforts, and the impacts of volcanoes on human populations. A text-only version is also available.

108

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

E-print Network

Numerical modelling of mud volcanoes and their £ows using constraints from the Gulf of Cadiz of submarine mud volcanoes is between 1000 and 100 000. Because many are associated with greenhouse gases and submarine mud volcanoes is highly significant. Clues to the processes forming submarine mud volcanoes can

Biggs, Juliet

109

Volcanic evolution of the submarine super volcano, Tamu Massif of Shatsky Rise: New insights from Formation MicroScanner logging imagery  

NASA Astrophysics Data System (ADS)

Massif, the southernmost plateau of Shatsky Rise, is recently reported as the largest single volcano known on Earth. This work seeks to understand the type of volcanism necessary to form such an anomalously large single volcano by integrating core and high-resolution wireline logging data. In particular, resistivity imagery obtained by the Formation MicroScanner, in Integrated Ocean Drilling Program Hole U1347A, located on the eastern flank of Tamu Massif, was used to construct a logging-based volcanostratigraphy. This model revealed two different volcanic stages formed Tamu Massif: (i) the core part of the massif's basaltic basement was formed by a "construction phase" of volcanism with cyclic eruption events from a steady state magma supply and (ii) the very topmost basaltic section was formed by a "depositional phase" of volcanism during which long-traveling lava flows were deposited from a distant eruption center.

Tominaga, Masako; Iturrino, Gerardo; Evans, Helen F.

2015-01-01

110

Optimizing submarine berthing with a persistence incentive  

Microsoft Academic Search

Submarine berthing plans reserve mooring locations for inbound U.S. Navy nuclear submarines prior to their port entrance. Once in port, submarines may be shifted to different berthing locations to allow them to better receive services they require or to make way for other shifted vessels. However, submarine berth shifting is expensive, labor inten- sive, and potentially hazardous. This article presents

Gerald G. Brown; Kelly J. Cormican; Siriphong Lawphongpanich; Daniel B. Widdis

1997-01-01

111

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

112

NOAA Explorations: Submarine Ring of Fire 2004  

NSDL National Science Digital Library

NOAA's 2004 Submarine Ring of Fire expedition's goals are to examine over a 1,000 km stretch of submarine volcanoes and sea-floor hot springs in the Mariana Island Arc. At this website, users can find general information about the Mariana Arc, the research, and the scientists involved. Educators can find intriguing lesson plans about volcanoes and the chemistry of hydrothermal vents for grades fifth through twelfth. The site presents fascinating materials about seafloor mapping, volcanism, and vent chemistry. Visitors can view amazing satellite images of the overall Mariana Arc Volcanic Chain, its sea floor, and the NW Uracas and Ahyi submarine volcanoes.

113

Volcanic Risk Perception in Five Communities Located near the Chichón Volcano, Northern Chiapas, Mexico  

NASA Astrophysics Data System (ADS)

The Chichón volcano (17° 19’ N and 93° 15’ W) is located in the state of Chiapas, Mexico. This volcano is classified by UNESCO as one of the ten most dangerous volcanos in the world. The eruptions of March and April in 1982 affected at least 51 communities located in the surroundings of the volcano and caused the death of about 2000 people. In this work we evaluate the risk perception in five communities highly populated: Juárez, Ostuacán, Pichucalco, Reforma and Sunuapa. We selected these communities because they have a high possibility to be affected by a volcanic eruption in the future. Our survey was carried out during February and March 2006. A total of 222 families were interviewed using a questionnaire to measure risk perception. These questionnaires retrieved general information as how long people had been living there and their reasons to do so; their experiences during the 1982 events, their opinion about the authorities participation and their perception of volcanic risk; the plans of the community for disaster prevention and mitigation. Some of the most important results are: (1). People perceive a very low volcanic risk and the 70% of interviewees believe that a new eruption in the future is almost improbable because it happened in 1982. This result is particularly interesting because, according to the state government, more than 100,000 inhabitants will be directly affected in case of a new similar eruption; (2). About 95% of the population do not know the current activity of the volcano and consider that the authorities do not inform properly to their communities; (3). The response of the authorities during the events of 1982 was ranked as deficient mainly because they were unable provide shelters, storage facilities, food as well as medicine and health care access; (4). Approximately 60% of the community will accept to be re-located again in case of a new eruption; (5). About 70% of the population will not accept to be re-located because they do not know any plan, strategy, emergency schemes or shelters locations no even evacuation routes. In conclusion, during the 1982 eruption the risk perception of the population played an important role in the social impact on the region. We believe that if the population had had a proper perception of their volcanic risk, the number of casualties would have been lower. Thus, the present low volcanic risk perception of the five studied communities can be considered as an important element of vulnerability. Frances Rodríguez-VanGort1 and David A. Novelo-Casanova2 (1) Posgrado Instituto de Geofísica, Universidad Nacional Autónoma de México, Ciudad Universitaria, México Distrito Federal (2) Departamento de Sismología Instituto de Geofísica, Universidad Nacional Autónoma de México, Ciudad Universitaria, México Distrito Federal

Rodriguez, F.; Novelo-Casanova, D. A.

2010-12-01

114

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

115

Kinematic variables and water transport control the formation and location of arc volcanoes.  

PubMed

The processes that give rise to arc magmas at convergent plate margins have long been a subject of scientific research and debate. A consensus has developed that the mantle wedge overlying the subducting slab and fluids and/or melts from the subducting slab itself are involved in the melting process. However, the role of kinematic variables such as slab dip and convergence rate in the formation of arc magmas is still unclear. The depth to the top of the subducting slab beneath volcanic arcs, usually approximately 110 +/- 20 km, was previously thought to be constant among arcs. Recent studies revealed that the depth of intermediate-depth earthquakes underneath volcanic arcs, presumably marking the slab-wedge interface, varies systematically between approximately 60 and 173 km and correlates with slab dip and convergence rate. Water-rich magmas (over 4-6 wt% H(2)O) are found in subduction zones with very different subduction parameters, including those with a shallow-dipping slab (north Japan), or steeply dipping slab (Marianas). Here we propose a simple model to address how kinematic parameters of plate subduction relate to the location of mantle melting at subduction zones. We demonstrate that the location of arc volcanoes is controlled by a combination of conditions: melting in the wedge is induced at the overlap of regions in the wedge that are hotter than the melting curve (solidus) of vapour-saturated peridotite and regions where hydrous minerals both in the wedge and in the subducting slab break down. These two limits for melt generation, when combined with the kinematic parameters of slab dip and convergence rate, provide independent constraints on the thermal structure of the wedge and accurately predict the location of mantle wedge melting and the position of arc volcanoes. PMID:19494913

Grove, T L; Till, C B; Lev, E; Chatterjee, N; Médard, E

2009-06-01

116

Automated identification, location, and volume estimation of rockfalls at Piton de la Fournaise volcano  

NASA Astrophysics Data System (ADS)

Since the collapse of the Dolomieu crater floor at Piton de la Fournaise Volcano (la Réunion) in 2007, hundreds of seismic signals generated by rockfalls have been recorded daily at the Observatoire Volcanologique du Piton de la Fournaise (OVPF). To study rockfall activity over a long period of time, automated methods are required to process the available continuous seismic records. We present a set of automated methods designed to identify, locate, and estimate the volume of rockfalls from their seismic signals. The method used to automatically discriminate seismic signals generated by rockfalls from other common events recorded at OVPF is based on fuzzy sets and has a success rate of 92%. A kurtosis-based automated picking method makes it possible to precisely pick the onset time and the final time of the rockfall-generated seismic signals. We present methods to determine rockfall locations based on these accurate pickings and a surface-wave propagation model computed for each station using a Fast Marching Method. These methods have successfully located directly observed rockfalls with an accuracy of about 100 m. They also make it possible to compute the seismic energy generated by rockfalls, which is then used to retrieve their volume. The methods developed were applied to a data set of 12,422 rockfalls that occurred over a period extending from the collapse of the Dolomieu crater floor in April 2007 to the end of the UnderVolc project in May 2011 to identify the most hazardous areas of the Piton de la Fournaise volcano summit.

Hibert, C.; Mangeney, A.; Grandjean, G.; Baillard, C.; Rivet, D.; Shapiro, N. M.; Satriano, C.; Maggi, A.; Boissier, P.; Ferrazzini, V.; Crawford, W.

2014-05-01

117

Satellite observations of environmental changes from the Tonga volcano eruption in the southern tropical Pacific  

Microsoft Academic Search

Satellite measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS) on Aqua were used to study changes of the ocean and atmosphere following the eruption of a submarine volcano in March 2009 in the southern tropical Pacific. Significant increase of water turbidity was observed in an area of ?368 km near the location of the eruption due to the deposition of

Wei Shi; Menghua Wang

2011-01-01

118

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

NASA Astrophysics Data System (ADS)

Two manned submersible dives examined the Hualalai Northwest rift zone and an elongate ridge cresting at 3900 mbsl during a 2002 JAMSTEC cruise. The rift zone flank at dive site S690 (water depth 3412-2104 m) is draped by elongated and truncated pillow lavas. These olivine-rich tholeiitic lavas are compositionally indistinguishable from those examined further south along the bench, except that they span a wider range in dissolved sulfur content (200-1400 ppm). The elongate ridge investigated in dive S692, located at the base of the bench, is a package of distinct lithologic units containing volcaniclastic materials, glassy pillow breccias, and lava blocks; these units contain a range of compositions including tholeiitic basalt, transitional basalt, and hawaiite. The textures, compositions, and stratigraphic relationships of materials within the elongate ridge require that a variety of transport mechanisms juxtaposed materials from multiple eruptions into individual beds, compacted them into a coherent package of units, and brought the package to its present depth 10 km from the edge of the North Kona slump bench. Sulfur-rich hawaiite glasses at the base of the elongate ridge may represent the first extant representatives of juvenile alkalic volcanism at Hualalai. They are geochemically distinct from shield tholeiite and post-shield alkalic magmas, but may be related to transitional basalt by high-pressure crystal fractionation of clinopyroxene. Tholeiitic glasses that compose the majority of the exposed outcrop are similar to Mauna Kea tholeiites and other Hualalai tholeiites, but they differ from younger basalts in having greater incompatible element enrichments and higher CaO for a given MgO. These differences could arise from small extents of partial melting during the transition from alkalic to shield stage magmatism. Low sulfur contents of most of the volcaniclastic tholeiites point to early emergence of Hualalai above sea level relative to the development of the midslope slump bench.

Hammer, Julia E.; Coombs, Michelle L.; Shamberger, Patrick J.; Kimura, Jun-Ichi

2006-03-01

119

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

USGS Publications Warehouse

Two manned submersible dives examined the Hualalai Northwest rift zone and an elongate ridge cresting at 3900 mbsl during a 2002 JAMSTEC cruise. The rift zone flank at dive site S690 (water depth 3412-2104 m) is draped by elongated and truncated pillow lavas. These olivine-rich tholeiitic lavas are compositionally indistinguishable from those examined further south along the bench, except that they span a wider range in dissolved sulfur content (200-1400 ppm). The elongate ridge investigated in dive S692, located at the base of the bench, is a package of distinct lithologic units containing volcaniclastic materials, glassy pillow breccias, and lava blocks; these units contain a range of compositions including tholeiitic basalt, transitional basalt, and hawaiite. The textures, compositions, and stratigraphic relationships of materials within the elongate ridge require that a variety of transport mechanisms juxtaposed materials from multiple eruptions into individual beds, compacted them into a coherent package of units, and brought the package to its present depth 10 km from the edge of the North Kona slump bench. Sulfur-rich hawaiite glasses at the base of the elongate ridge may represent the first extant representatives of juvenile alkalic volcanism at Hualalai. They are geochemically distinct from shield tholeiite and post-shield alkalic magmas, but may be related to transitional basalt by high-pressure crystal fractionation of clinopyroxene. Tholeiitic glasses that compose the majority of the exposed outcrop are similar to Mauna Kea tholeiites and other Hualalai tholeiites, but they differ from younger basalts in having greater incompatible element enrichments and higher CaO for a given MgO. These differences could arise from small extents of partial melting during the transition from alkalic to shield stage magmatism. Low sulfur contents of most of the volcaniclastic tholeiites point to early emergence of Hualalai above sea level relative to the development of the midslope slump bench. ?? 2005 Elsevier B.V. All rights reserved.

Hammer, J.E.; Coombs, M.L.; Shamberger, P.J.; Kimura, J.-I.

2006-01-01

120

Deadly Volcanos  

NSDL National Science Digital Library

This interactive slide show provides accounts of eight of history's most deadly volcanic eruptions. These eruptions are from both ancient and modern times, and include such volcanos as Mount Vesuvius, Tambora, Krakatau, Nevado del Ruiz, and Mount Pinatubo. Each slide features an illustration from the event, a written description with the name of the volcano, date, number of casualties, an account of the eruption, and a map showing the location of the volcano.

121

Hawaiian Volcano Observatory  

USGS Publications Warehouse

Lava from Kilauea volcano flowing through a forest in the Royal Gardens subdivision, Hawai'i, in February 2008. The Hawaiian Volcano Observatory (HVO) monitors the volcanoes of Hawai'i and is located within Hawaiian Volcanoes National Park. HVO is one of five USGS Volcano Hazards Program observatories that monitor U.S. volcanoes for science and public safety. Learn more about Kilauea and HVO at http://hvo.wr.usgs.gov.

Venezky, Dina Y.; Orr, Tim R.

2008-01-01

122

Trace element distribution, with a focus on gold, in copper-rich and zinc-rich sulfide chimneys from Brothers submarine volcano, Kermadec arc  

NASA Astrophysics Data System (ADS)

Brothers volcano is a dacitic volcano located along the Kermadec arc, New Zealand, and hosts the NW Caldera hydrothermal vent field perched on part of the steep caldera walls. The field strikes for ~600 m between depths of 1550 and 1700 m and includes numerous, active, high-temperature (max 302°C) chimneys and even more dead, sulfide-rich spires. Chimney samples collected from Brothers show distinct mineralogical zonation reflecting gradients in oxidation state, temperature, and pH from the inner walls in contact with hydrothermal fluids through to the outer walls in contact with seawater. Minerals deposited from hotter fluids (e.g., chalcopyrite) are located in the interior of the chimneys and are surrounded by an external zone of minerals deposited by cooler fluids (e.g., sulfates, sphalerite). Four chimneys types are identified at Brothers volcano based on the relative proportions of chalcopyrite and sulfate layers, and the presence or absence of anhydrite. Two are Cu-rich, i.e., chalcopyrite-rich and chalcopyrite-bornite-rich chimneys, and two are Zn-rich, i.e., sphalerite-rich and sphalerite-chalcopyrite-rich. Barite and anhydrite are common to both Cu-rich chimney types whereas Zn-rich chimneys contain barite only. The main mineral phases in all the chimneys are anhydrite, barite, chalcopyrite, pyrite/marcasite, and sphalerite. Trace minerals include galena, covellite, tennantite, realgar, chalcocite, bornite, hematite, goethite, Pb-As sulfosalts, and Bi- or Au-tellurides. The vast majority of tellurides are <5 ?m in size and they commonly form in bands, cluster in patches, or occur along internal grain boundaries within chalcopyrite. In sulfate layers adjacent to the chalcopyrite zones tellurides can occur as inclusions in anhydrite, barite or pyrite and/or occupy void space within the chimney. The occurrence of specular hematite and Bi- or Au-tellurides associated with chalcopyrite are consistent with magmatic contributions to the NW Caldera vent site. These tellurides are the first gold-bearing phase to be identified in these chimneys, and the Bi-Au association suggests that gold-enrichment up to 91 ppm is due to scavenging by liquid bismuth. To better understand the mineral associations and zonation of these and other trace elements within the chimney walls, we have undertaken element mapping on the four different chimneys types with both X-Ray fluorescence microscopy using synchrotron radiation and with Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS). For example, in a chalcopyrite-rich chimney, visibly laminated chalcopyrite in the interior contains bands with a magmatic suite of elements including Co, Mo, Ag, Te, Au, and Bi. In comparison in a sphalerite-chalcopyrite-rich chimney, Au is again associated with minor Cu, although not with Bi and Te indicating alternative methods of gold transport and deposition are dominant. Element mapping allows us to better understand the physico-chemical gradients within chimney walls, as well as metal sources and transportation, and depositional processes.

Berkenbosch, H. A.; de Ronde, C. E.; McNeill, A.; Goemann, K.; Gemmell, J. B.

2012-12-01

123

Intermediate products of sulfur disproportional reaction and their physical role in effusive to explosive submarine volcanic activity  

Microsoft Academic Search

Recent direct observations of submarine volcanic activity in the Mariana Arc are giving us a chance to examine the role of volcanic gas in submarine volcanic conduits. Unlike subaerial volcanoes, where hydrogeologic conditions have different character from place to place, the overlying water mass above submarine volcanoes gives a uniform hydrographic setting. Currently, the places where we can directly observe

K. Nakamura; B. Takano; D. A. Butterfield; J. Resing; W. W. Chadwick; R. W. Embley

2009-01-01

124

Repetitive Long-Period Seismicity: Source Location and Mechanism Characteristics, Villarrica Volcano, Chile  

NASA Astrophysics Data System (ADS)

Villarrica Volcano, Chile has an exposed magma free-surface, characterized by vigorous degassing ranging from small bubble bursts to Strombolian style slug bursting. Slug bursting events are characterized by both repetitive seismic and acoustic signals within the long-period (LP) band. We use the very repetitive nature of the low amplitude seismic LP signals to identify them with a matched filter on several persistent seismic stations, functional over the three year experiment duration. We stack the seismic and acoustic signals accompanying degassing to increase the signal to noise ratio, and tie signals measured 2010-2012 to produce a synthetic seismic network that recorded LP signals at a wide range of azimuths and distances from the source. Particle motions for most of the 21 stations were dominantly tangential, indicating the presence of a complex source geometry that deviated greatly from the logical axisymmetric geometry visible at the lave lake surface. We use the synthetic network to solve for the moment-tensor and location of the LP source, searching for the best source-time function using combinations of moment components, single force components, and both, for six different homogeneous half-space velocity models. Using the best source configuration and velocity model as a guide, we present forward models of reasonable geometries with geologic significance, including dikes, sills, pipes, and combination mechanisms to validate and test the sensitivity of the results of the free-inversion. Our results indicate that the current repetitive LP seismicity dominated by tangential particle motions is probably associated with relic fissure geometry from the last eruptive phase, and is caused by a conduit constriction through which large gas slugs pass (seismic emission) and subsequently burst at the surface (acoustic emission).

Richardson, J.; Waite, G. P.

2012-12-01

125

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....

126

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

127

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

128

Microbial communities in sunken wood are structured by wood-boring bivalves and location in a submarine canyon.  

PubMed

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

129

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

130

Iceland: Grímsvötn Volcano  

Atmospheric Science Data Center

article title:  Grímsvötn Volcano Injects Ash into the Stratosphere     ... p.m. local time (1730 UTC) on Saturday, May 21, 2011. The volcano, located approximately 140 miles (220 kilometers) east of the capital ...

2013-04-17

131

2006 Nature Publishing Group Long-term eruptive activity at a submarine arc  

E-print Network

© 2006 Nature Publishing Group Long-term eruptive activity at a submarine arc volcano Robert W , Douglas A. Wiens12 & Yoshihiko Tamura13 Three-quarters of the Earth's volcanic activity is submarine of submarine eruptions have been indirect, made from surface vessels or made after the fact1­6 . We describe

Chadwick, Bill

132

33 CFR 209.310 - Representation of submarine cables and pipelines on nautical charts.  

Code of Federal Regulations, 2012 CFR

...Representation of submarine cables and pipelines on nautical charts. 209.310 Section...Representation of submarine cables and pipelines on nautical charts. (a) The policy...the locations of submarine cables and pipelines on nautical charts published by the...

2012-07-01

133

33 CFR 209.310 - Representation of submarine cables and pipelines on nautical charts.  

Code of Federal Regulations, 2010 CFR

...Representation of submarine cables and pipelines on nautical charts. 209.310 Section...Representation of submarine cables and pipelines on nautical charts. (a) The policy...the locations of submarine cables and pipelines on nautical charts published by the...

2010-07-01

134

33 CFR 209.310 - Representation of submarine cables and pipelines on nautical charts.  

Code of Federal Regulations, 2013 CFR

...Representation of submarine cables and pipelines on nautical charts. 209.310 Section...Representation of submarine cables and pipelines on nautical charts. (a) The policy...the locations of submarine cables and pipelines on nautical charts published by the...

2013-07-01

135

33 CFR 209.310 - Representation of submarine cables and pipelines on nautical charts.  

Code of Federal Regulations, 2011 CFR

...Representation of submarine cables and pipelines on nautical charts. 209.310 Section...Representation of submarine cables and pipelines on nautical charts. (a) The policy...the locations of submarine cables and pipelines on nautical charts published by the...

2011-07-01

136

33 CFR 209.310 - Representation of submarine cables and pipelines on nautical charts.  

Code of Federal Regulations, 2014 CFR

...Representation of submarine cables and pipelines on nautical charts. 209.310 Section...Representation of submarine cables and pipelines on nautical charts. (a) The policy...the locations of submarine cables and pipelines on nautical charts published by the...

2014-07-01

137

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

USGS Publications Warehouse

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. Copyright 2011 by the American Geophysical Union.

Dawson, P.B.; Chouet, B.A.; Power, J.

2011-01-01

138

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

139

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.

John Seach

140

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.

Jessica Fries-Gaither

141

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

DOE Data Explorer

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.

Jaffe, Todd

142

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

143

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.

144

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

145

Precise Hypocenter Location of High-Frequency-Onset Earthquakes, Tomography, and Changing Stress Conditions Beneath Soufriere Hills Volcano, Montserrat  

NASA Astrophysics Data System (ADS)

The andesite stratovolcano of Soufriere Hills (SHV), Montserrat, has been intermittently erupting now for 9 years. Previous work (Aspinall et al., 1998) has examined hypocenter locations for events 1995 - 1997 to map possible magma migration pathways and domains sensitive to stress redistributions caused by magmatic processes. This indicated a NE-SW alignment of epicenters under the NE flank, and nests occurring under the volcano, and 3 km W of SHV. Recent instrumentation at SHV with hardware by the CALIPSO Project (Voight et al., 2003; Mattioli et al., 2003) have made it desirable to re-examine the seismic database to more precisely constrain the magma storage and transport system, and stress changes which have occurred during eruption activity. Recent developments have allowed more precise hypocenter relocations using relative positioning techniques. Studies using such methods (e.g., Prejean et al., 2002) have demonstrated improvements in location precision, with distinct lineaments emerging where previous techniques had merely identified earthquake clusters. Therefore we have examined seismic data at SHV utilizing the Waldhauser and Ellsworth (2000) precise relocation technique. The aim of the study is to provide clarification of distinct structures that may have influenced magmatic processes, and which might influence the modeling of crustal strains as deduced by CALIPSO data. Velocity structure is examined, and fault plane solutions are also explored to detect any stress changes that have occurred in concert with pulsatory magmatic pressure episodes. Examination of the data for both spatial and temporal patterns provides constraints on magma storage and transport dynamics at SHV.

Miller, V.; Thompson, G.; Voight, B.; Ammon, C.

2004-12-01

146

Quantitative constraints on the growth of submarine lava pillars from a monitoring instrument that was caught in a lava flow  

E-print Network

Quantitative constraints on the growth of submarine lava pillars from a monitoring instrument that are common features within the collapsed interiors of submarine sheet flows on intermediate and fast beneath each crust. During the submarine eruption of Axial Volcano in 1998 on the Juan de Fuca Ridge

Chadwick, Bill

147

Shallow-water longshore drift-fed submarine fan deposition (Moisie River Delta, Eastern Canada)  

E-print Network

ORIGINAL Shallow-water longshore drift-fed submarine fan deposition (Moisie River Delta, Eastern Submarine canyons and associated submarine fans are in some cases located at the end of a littoral cell to the discovery of an unusu- ally shallow submarine fan (60 m) located at the end of a littoral cell. Sediment

St-Ong, Guillaume

148

Simple Submarine  

NSDL National Science Digital Library

Using simple, inexpensive items, students build and test submarine models in a single class period. They gain insight into the engineering that's required to make these machines ascend, descend, and hover safely in extreme environments. The printable eight-page handout includes a series of inquiry-based questions that get students thinking about the complex engineering required for submersibles, illustrated experiment directions, and a worksheet that includes thought-provoking questions along with areas for recording experiment data.

149

Large landslides from oceanic volcanoes  

Microsoft Academic Search

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

Robin T. Holcomb; Roger C. Searle

1991-01-01

150

The implementation of a volcano seismic monitoring network in Sete Cidades Volcano, São Miguel, Açores  

Microsoft Academic Search

Sete Cidades is one of the three active central volcanoes of S. Miguel Island, in the Azores archipelago. With a 5 kilometres wide caldera, it has the highest eruptive record in the last 5000 years with 17 intracaldera explosive events (Queiroz, 1997). Only submarine volcanic eruptions occurred in Sete Cidades volcano-tectonic system since the settlement of the island, in the

N. Wallenstein; A. Montalvo; U. Barata; R. Ortiz

2003-01-01

151

An efficient algorithm for double-difference tomography and location in heterogeneous media, with an application to the Kilauea volcano  

USGS Publications Warehouse

Improving our understanding of crustal processes requires a better knowledge of the geometry and the position of geological bodies. In this study we have designed a method based upon double-difference relocation and tomography to image, as accurately as possible, a heterogeneous medium containing seismogenic objects. Our approach consisted not only of incorporating double difference in tomography but also partly in revisiting tomographic schemes for choosing accurate and stable numerical strategies, adapted to the use of cross-spectral time delays. We used a finite difference solution to the eikonal equation for travel time computation and a Tarantola-Valette approach for both the classical and double-difference three-dimensional tomographic inversion to find accurate earthquake locations and seismic velocity estimates. We estimated efficiently the square root of the inverse model's covariance matrix in the case of a Gaussian correlation function. It allows the use of correlation length and a priori model variance criteria to determine the optimal solution. Double-difference relocation of similar earthquakes is performed in the optimal velocity model, making absolute and relative locations less biased by the velocity model. Double-difference tomography is achieved by using high-accuracy time delay measurements. These algorithms have been applied to earthquake data recorded in the vicinity of Kilauea and Mauna Loa volcanoes for imaging the volcanic structures. Stable and detailed velocity models are obtained: the regional tomography unambiguously highlights the structure of the island of Hawaii and the double-difference tomography shows a detailed image of the southern Kilauea caldera-upper east rift zone magmatic complex. Copyright 2005 by the American Geophysical Union.

Monteiller, V.; Got, J.-L.; Virieux, J.; Okubo, P.

2005-01-01

152

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

153

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

NASA Astrophysics Data System (ADS)

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 Peninsula, where recent changes in surface temperature and ice shelf stability have been observed. This volcano was originally swath-mapped during cruise 01-07 of the Research Vessel-Ice Breaker Nathaniel B. Palmer. During LMG04-04 we also studied the volcano using a SCUD video camera, and performed temperature surveys along the flanks and crest. Both the video and the dredge indicate a seafloor surface heavily colonized by benthic organisms. Indications of fairly recent lava flows are given by the absence of marine life on regions of the volcano. The recovered dredge material was sieved, and a total of thirty-three invertebrates were extracted. The compilation of invertebrate community data can subsequently be compared to other benthic invertebrate studies conducted along the peninsula, which can determine the regional similarity of communities over time, their relationship to environmental change and health, if any, and their relationship to geologic processes in Antarctic Sound. Twenty-two rock samples, all slightly weathered and half bearing encrusted organisms, were also analyzed using inductively coupled plasma-optical emission spectrometry (ICP-OES). Except for one conglomerate sample, all are alkali basalts and share similar elemental compositions with fresh, unweathered samples from the volcano. Two of the encrusted basalt samples have significantly different compositions than the rest. We speculate this difference could be due to water loss during sample preparation, loss of organic carbon trapped within the vesicles of the samples and/or elemental uptake by the organism. These results can establish a qualitative baseline survey for other young volcanoes, and be used to monitor changes in the benthic assemblages and biodiversity as a function of environmental change and environmental health.

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

2005-12-01

154

The USGS Hawaiian Volcano Observatory Monitors Kilauea'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....

155

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....

156

Submarine Volcanic Morphology of Santorini Caldera, Greece  

NASA Astrophysics Data System (ADS)

Santorini volcanic group form the central part of the modern Aegean volcanic arc, developed within the Hellenic arc and trench system, because of the ongoing subduction of the African plate beneath the European margin throughout Cenozoic. It comprises three distinct volcanic structures occurring along a NE-SW direction: Christianna form the southwestern part of the group, Santorini occupies the middle part and Koloumbo volcanic rift zone extends towards the northeastern part. The geology of the Santorini volcano has been described by a large number of researchers with petrological as well as geochronological data. The offshore area of the Santorini volcanic field has only recently been investigated with emphasis mainly inside the Santorini caldera and the submarine volcano of Kolumbo. In September 2011, cruise NA-014 on the E/V Nautilus carried out new surveys on the submarine volcanism of the study area, investigating the seafloor morphology with high-definition video imaging. Submarine hydrothermal vents were found on the seafloor of the northern basin of the Santorini caldera with no evidence of high temperature fluid discharges or massive sulphide formations, but only low temperature seeps characterized by meter-high mounds of bacteria-rich sediment. This vent field is located in line with the normal fault system of the Kolumbo rift, and also near the margin of a shallow intrusion that occurs within the sediments of the North Basin. Push cores have been collected and they will provide insights for their geochemical characteristics and their relationship to the active vents of the Kolumbo underwater volcano. Similar vent mounds occur in the South Basin, at shallow depths around the islets of Nea and Palaia Kameni. ROV exploration at the northern slopes of Nea Kameni revealed a fascinating underwater landscape of lava flows, lava spines and fractured lava blocks that have been formed as a result of 1707-1711 and 1925-1928 AD eruptions. A hummocky topography at the area that lies between the town of Fira on the main island of Santorini and Nea Kammeni has been revealed. The lower slopes were covered with landslide debris which consisted of lava blocks mostly mantled with soft sediment. At the upper slopes an abrupt cliff face was exposed that was highly indurated by biologic material. At the top of a volcanic dome, a crater with its deepest part at 43m, its rim at about 34m with an approximately 8m diameter was also found. Shimmery water with temperatures as much as 25°C above ambient was observed there but the source of venting has not yet been found. The combination of ROV video footage and multibeam data provide new information about the main morphological characteristics of Santorini Caldera which demonstrates the intense geodynamic processes occurring at the central part of the active Hellenic volcanic arc. These results will be useful for the interpretation of understanding the offshore volcanic area and its linkage with the onshore structures.

Nomikou, P.; Croff Bell, K.; Carey, S.; Bejelou, K.; Parks, M.; Antoniou, V.

2012-04-01

157

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? ...

Mr. Syracuse

2008-06-11

158

Iceland: Eyjafjallajökull Volcano  

Atmospheric Science Data Center

... 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

159

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

NASA Astrophysics Data System (ADS)

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

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

2004-12-01

160

Source location variability and volcanic vent mapping with a small-aperture infrasound array at Stromboli Volcano, Italy  

Microsoft Academic Search

Stromboli Volcano in Italy is a persistently active, complex volcanic system. In May 2002 activity was confined to 3 major summit craters within which several active vents hosted multiple explosions each hour. During a 5-day field campaign an array of 3 low-frequency microphones was installed to investigate the coherent infrasound produced by degassing from these vents. Consistent phase lags across

Jeffrey B. Johnson

2004-01-01

161

Nicaraguan Volcanoes  

Atmospheric Science Data Center

article title:  Nicaraguan Volcanoes     View Larger Image Nicaraguan volcanoes, February 26, 2000 . The true-color image at left is a ... February 26, 2000 - Plumes from the San Cristobal and Masaya volcanoes. project:  MISR category:  gallery ...

2013-04-18

162

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

163

Anatomy of a Volcano  

NSDL National Science Digital Library

In this interactive activity from NOVA Online, explore the main features of the Nyiragongo volcano, located in the Democratic Republic of Congo, and learn what risks it poses to the 500,000 people who live in its shadow.

2005-12-17

164

Design a Submarine  

NSDL National Science Digital Library

Learners act as engineers and design mini submarines that move in the water like real submarines. The submarines must be able to float, sink, and hover steadily without touching the top of the water or resting on the bottom. Use this activity to introduce learners to density and buoyancy.

2012-03-20

165

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.

166

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

167

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

168

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.

169

The Kaena Ridge Submarine Rift Zone off Oahu, Hawaii  

NASA Astrophysics Data System (ADS)

Deep-water multibeam data was collected in the Kauai Channel between the islands of Kauai and Oahu during the years 2000 to 2002 using the R/V Roger Revelle in support of the NSF funded Hawaii Ocean Mixing Experiment (HOME) with M. Gregg and A. Chave as principal investigators. The bathymetric surveys covered the Kaena Ridge, possibly a large submarine rift zone extension of the Waianae Volcano that makes up the western half of the island of Oahu. The Kaena ridge is bordered by the Kauai Channel and debris avalanche deposit material to the west, the Waianae slump to the south, and the Kaena slump to the north. The 35-55 km wide crest of the Kaena ridge extends 75-100 km northwest from Kaena Point, the westernmost tip of Oahu. The length and morphology resemble that of the Hana Ridge, the submarine extension of the Haleakala east rift zone. The broad central portion of Kaena ridge is comprised of two apparent lava shields 15 km and 10 km in diameter, both rising 200 m above the ridge (approximately 2500 m above the basal seafloor) to within 880 m and 660 m of sea level, respectively. The large size and distant location of the westernmost cone in the middle of the Kauai Channel suggests that it might predate Waianae Volcano and represent a precursor to the island of Oahu in the Hawaiian Chain, aborted before it ever reached sea level. Several 1500 m high steep concave landslide scars facing the giant Waianae slump mark the southern side of the ridge. To the north, a series of four 15 to 30 km wide benches step down to the basal seafloor, forming the Kaena slump, which may represent a less developed version of the Waianae slump. A 42 km long and 22 km wide (at its center) narrow rift zone ridge, in the classic Hawaiian submarine rift zone style (e.g., Puna ridge), bifurcates from the main broad ridge near the distal end. The smaller ridge trends north-northwest and is covered with approximately a dozen volcanic cones along its axis. Its rough morphology is characteristic of pillow and lobate lava flows effusing from a central dike injected rift zone.

Smith, J. R.

2002-12-01

170

The diversity of mud volcanoes in the landscape of Azerbaijan  

NASA Astrophysics Data System (ADS)

As the natural phenomenon the mud volcanism (mud volcanoes) of Azerbaijan are known from the ancient times. The historical records describing them are since V century. More detail study of this natural phenomenon had started in the second half of XIX century. The term "mud volcano" (or "mud hill") had been given by academician H.W. Abich (1863), more exactly defining this natural phenomenon. All the previous definitions did not give such clear and capacious explanation of it. In comparison with magmatic volcanoes, globally the mud ones are restricted in distribution; they mainly locate within the Alpine-Himalayan, Pacific and Central Asian mobile belts, in more than 30 countries (Columbia, Trinidad Island, Italy, Romania, Ukraine, Georgia, Azerbaijan, Turkmenistan, Iran, Pakistan, Indonesia, Burma, Malaysia, etc.). Besides it, the zones of mud volcanoes development are corresponded to zones of marine accretionary prisms' development. For example, the South-Caspian depression, Barbados Island, Cascadia (N.America), Costa-Rica, Panama, Japan trench. Onshore it is Indonesia, Japan, and Trinidad, Taiwan. The mud volcanism with non-accretionary conditions includes the areas of Black Sea, Alboran Sea, the Gulf of Mexico (Louisiana coast), Salton Sea. But new investigations reveal more new mud volcanoes and in places which were not considered earlier as the traditional places of mud volcanoes development (e.g. West Nile Rive delta). Azerbaijan is the classic region of mud volcanoes development. From over 800 world mud volcanoes there are about 400 onshore and within the South-Caspian basin, which includes the territory of East Azerbaijan (the regions of Shemakha-Gobustan and Low-Kura River, Absheron peninsula), adjacent water area of South Caspian (Baku and Absheron archipelagoes) and SW Turkmenistan and represents an area of great downwarping with thick (over 25 km) sedimentary series. Generally, in the modern relief the mud volcanoes represent more or less large uplifts on surface, often of plane-conical shape, rising for 5 to 400 m and more over the country (for example, mud volcano Toragay, 400 m height). The base diameter is from 100 m to 3-4 km and more. Like the magmatic ones, the mud volcanoes are crowned with crater of convex-plane or deeply-seated shape. In Azerbaijan there are all types of mud volcanoes: active, extinct, buried, submarine, island, abundantly oil seeping. According to their morphology they are defined into cone-shaped, dome-shaped, ridge-shaped, plateau-shaped. The crater shapes are also various: conical, convex-plane, shield-shaped, deeply-seated, caldera-like. The most complete morphological classification was given in "Atlas of mud volcanoes of Azerbaijan" (Yakubov et al., 1971). Recently (Aliyev Ad. et al., 2003) it was proposed a quite new morphological classification of mud volcanoes of Azerbaijan. For the first time the mud volcanic manifestations had been defined. Volcanoes are ranged according to morphological signs, crater shape and type of activity.

Rashidov, Tofig

2014-05-01

171

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

172

Summit crater lake observations, and the location, chemistry, and pH of water samples near Mount Chiginagak volcano, Alaska: 2004-2012  

USGS Publications Warehouse

Mount Chiginagak is a hydrothermally active volcano on the Alaska Peninsula, approximately 170 km south–southwest of King Salmon, Alaska (fig. 1). This small stratovolcano, approximately 8 km in diameter, has erupted through Tertiary to Permian sedimentary and igneous rocks (Detterman and others, 1987). The highest peak is at an elevation of 2,135 m, and the upper ~1,000 m of the volcano are covered with snow and ice. Holocene activity consists of debris avalanches, lahars, and lava flows. Pleistocene pyroclastic flows and block-and-ash flows, interlayered with andesitic lava flows, dominate the edifice rocks on the northern and western flanks. Historical reports of activity are limited and generally describe “steaming” and “smoking” (Coats, 1950; Powers, 1958). Proximal tephra collected during recent fieldwork suggests there may have been limited Holocene explosive activity that resulted in localized ash fall. A cluster of fumaroles on the north flank, at an elevation of ~1,750 m, commonly referred to as the “north flank fumarole” have been emitting gas throughout historical time (location shown in fig. 2). The only other thermal feature at the volcano is the Mother Goose hot springs located at the base of the edifice on the northwestern flank in upper Volcano Creek, at an elevation of ~160 m (fig. 2, near sites H1, H3, and H4). Sometime between November 2004 and May 2005, a ~400-m-wide, 100-m-deep lake developed in the snow- and ice-filled summit crater of the volcano (Schaefer and others, 2008). In early May 2005, an estimated 3 million cubic meters (3×106 m3) of sulfurous, clay-rich debris and acidic water exited the crater through tunnels at the base of a glacier that breaches the south crater rim. More than 27 km downstream, these acidic flood waters reached approximately 1.3 m above normal water levels and inundated a fertile, salmon-spawning drainage, acidifying the entire water column of Mother Goose Lake from its surface waters to its maximum depth of 45 m (resulting pH ~2.9), and preventing the annual salmon run in the King Salmon River. A simultaneous release of gas and acidic aerosols from the crater caused widespread vegetation damage along the flow path. Since 2005, we have been monitoring the crater lake water that continues to flow into Mother Goose Lake by collecting surface water samples for major cation and anion analysis, measuring surface-water pH of affected drainages, and photo-documenting the condition of the summit crater lake. This report describes water sampling locations, provides a table of chemistry and pH measurements, and documents the condition of the summit crater between 2004 and 2011. In September 2013, the report was updated with results of water-chemistry samples collected in 2011 and 2012, which were added as an addendum.

Schaefer, Janet R.; Scott, William E.; Evans, William C.; Wang, Bronwen; McGimsey, Robert G.

2013-01-01

173

Iceland Volcano  

Atmospheric Science Data Center

article title:  Eyjafjallajökull, Iceland, Volcano Ash Cloud     View larger ... Europe and captured this image of the Eyjafjallajökull Volcano ash cloud as it continued to drift over the continent. Unlike other ...

2013-04-23

174

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.

175

Detail of conning tower atop the submarine. Note the wire ...  

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

Detail of conning tower atop the submarine. Note the wire rope wrapped around the base of the tower, which may have been used in an attempt to pull the submarine offshore. - Sub Marine Explorer, Located along the beach of Isla San Telmo, Pearl Islands, Isla San Telmo, Former Panama Canal Zone, CZ

176

Tectonic Plates, Earthquakes, and Volcanoes  

NSDL National Science Digital Library

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

177

Morphotectonics and incision of the Kaoping submarine canyon, SW Taiwan orogenic wedge  

E-print Network

Morphotectonics and incision of the Kaoping submarine canyon, SW Taiwan orogenic wedge Cheng February 2006 Available online 24 March 2006 Abstract The Kaoping submarine canyon developed on the frontal; Incision; Submarine canyon; Taiwan 1. Introduction 1.1. Geological settings The island of Taiwan is located

Lin, Andrew Tien-Shun

178

33 CFR 165.1302 - Bangor Naval Submarine Base, Bangor, WA.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Bangor Naval Submarine Base, Bangor, WA. 165.1302 Section...District § 165.1302 Bangor Naval Submarine Base, Bangor, WA. (a) Location...Vessels that are performing work at Naval Submarine Base Bangor pursuant to a...

2014-07-01

179

SUBMARINE MASS MOVEMENTS IN THE BETSIAMITES AREA, GENEVIEVE CAUCHON-VOYER1  

E-print Network

SUBMARINE MASS MOVEMENTS IN THE BETSIAMITES AREA, GENEVIEVE CAUCHON-VOYER1 , JACQUES LOCAT1 A complex submarine geomorphology was revealed from multibeam bathymetry and seismic reflection surveys. Introduction Investigating submarine mass movements in order to evaluate slope stability for a region

St-Ong, Guillaume

180

33 CFR 165.1302 - Bangor Naval Submarine Base, Bangor, WA.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Bangor Naval Submarine Base, Bangor, WA. 165.1302 Section...District § 165.1302 Bangor Naval Submarine Base, Bangor, WA. (a) Location...Vessels that are performing work at Naval Submarine Base Bangor pursuant to a...

2013-07-01

181

33 CFR 165.1302 - Bangor Naval Submarine Base, Bangor, WA.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Bangor Naval Submarine Base, Bangor, WA. 165.1302 Section...District § 165.1302 Bangor Naval Submarine Base, Bangor, WA. (a) Location...Vessels that are performing work at Naval Submarine Base Bangor pursuant to a...

2011-07-01

182

33 CFR 165.1302 - Bangor Naval Submarine Base, Bangor, WA.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Bangor Naval Submarine Base, Bangor, WA. 165.1302 Section...District § 165.1302 Bangor Naval Submarine Base, Bangor, WA. (a) Location...Vessels that are performing work at Naval Submarine Base Bangor pursuant to a...

2010-07-01

183

33 CFR 165.1302 - Bangor Naval Submarine Base, Bangor, WA.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Bangor Naval Submarine Base, Bangor, WA. 165.1302 Section...District § 165.1302 Bangor Naval Submarine Base, Bangor, WA. (a) Location...Vessels that are performing work at Naval Submarine Base Bangor pursuant to a...

2012-07-01

184

Submarine pingoes: Indicators of shallow gas hydrates in a pockmark at Nyegga, Norwegian Sea  

E-print Network

Submarine pingoes: Indicators of shallow gas hydrates in a pockmark at Nyegga, Norwegian Sea Martin the features as true submarine pingoes, formed by the local accumulation of hydrate (ice) below the sediment the pockmark. We suggest that these submarine hydrate-pingoes manifest the exact locations where fluid flow

Svensen, Henrik

185

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.

186

The implementation of a volcano seismic monitoring network in Sete Cidades Volcano, São Miguel, Açores  

NASA Astrophysics Data System (ADS)

Sete Cidades is one of the three active central volcanoes of S. Miguel Island, in the Azores archipelago. With a 5 kilometres wide caldera, it has the highest eruptive record in the last 5000 years with 17 intracaldera explosive events (Queiroz, 1997). Only submarine volcanic eruptions occurred in Sete Cidades volcano-tectonic system since the settlement of the island, in the 15th century. Small seismic swarms, some of which were interpreted as being related with magmatic and/or deep hydrothermal origin, characterize the most recent seismo-volcanic activity of Sete Cidades volcano. To complement the regional seismic network, operating since the early 80's, a new local seismic network was designed and installed at Sete Cidades Volcano. It includes 5 digital stations being one 5-seconds three-component station located inside the caldera and four 10-seconds one-component stations placed on the caldera rim. The solution found for the digital telemetry is based on UHF 19,2 Kbps radio modems linking four of the seismic stations to a central point, where the fifth station is installed. At this site, signals are synchronised with a GPS receiver, stored in a PC and re-transmitted to the Azores University Volcanological Observatory by an 115,2 Kbps Spread Spectrum 2.4 Ghz Radio Modem Network. Seismic signal tests carried out in all the area showed that cultural and sea noise, as well as some scattering effects due to the geological nature of the terrain (composed by thick pumice and ash deposits) and the topographic effects are factors that can not be avoidable and will be present in future records. This low cost network with locally developed and assembled components, based on short-period sensors without signal filtering in the field and digital telemetry, will improve the detection and location of low magnitude events in the Sete Cidades volcano area. Future developments of this program will include the installation of a seismic array inside the caldera to identify and characterize LP events and volcanic tremor signals.

Wallenstein, N.; Montalvo, A.; Barata, U.; Ortiz, R.

2003-04-01

187

Submarine cable route survey  

SciTech Connect

The growth of telecommunication market is very significant. From the beginning of the nineties, more and more the use of optical fiber submarine cables is privileged to that of satellites. These submarine telecommunication highways require accurate surveys in order to select the optimum route and determine the cable characteristics. Advanced technology tools used for these surveys are presented along with their implementation.

Herrouin, G.; Scuiller, T.

1995-12-31

188

Paint-Stirrer Submarine  

ERIC Educational Resources Information Center

In this article, the authors discuss a unique and challenging laboratory exercise called, the paint-stir-stick submarine, that keeps the students enthralled. The paint-stir-stick submarine fits beautifully with the National Science Education Standards Physical Science Content Standard B, and with the California state science standards for physical…

Young, Jocelyn; Hardy, Kevin

2007-01-01

189

Intra-caldera Events: A Look at the Hydrovolcanic Deposit Stratigraphically Located Between two Caldera-Forming Eruptions of Okmok Volcano, Umnak Island, Alaska  

NASA Astrophysics Data System (ADS)

Within the 10 km diameter caldera that characterizes Okmok Volcano, a field of post-caldera cones and deposits demonstrate many features associated with water-magma interactions. A unit deposited prior to the formation of the present caldera provides evidence for large explosive hydrovolcanic eruptions in the past as well. This unit is referred to as the Middle Scoria Unit as it is stratigraphically located between the ~9000 BP Okmok I and 2050 BP Okmok II caldera-forming events. Here, we present data on the stratigraphy, geochemistry, and eruptive mechanisms of the Middle Scoria Unit, which averages a thickness of 2.5 meters. The basal layer of the Middle Scoria consists of moderately well sorted, highly inflated juvenile clasts of basaltic composition (53.88 wt.% SiO2) that average 3 to 5 cm in size. Capping the base is a sequence of layers alternating between oxidized reddish lithic fragments and poorly vesicular scoria averaging 1 mm to 3 cm in size. The contacts between the scoria and lithic layers are less discrete in the top section, with a higher proportion of mixing averaging up to 75% for a clast-rich layer. The upper layers of the unit also show reverse grading and contain dense, poorly vesicular scoria fragments and lithic fragments of 2 mm to 1.5 cm in size. The Middle Scoria unit has been found on the neighboring Unalaska Island, approximately 30 km to the East, revealing a wide dispersal. Our results indicate that this eruption began as a highly explosive, purely magmatic and rare basaltic Plinian eruption. With time, the eruptive series evolved to incorporate external water, as demonstrated by the successions of oxidized lithic lapilli and poorly vesicular scoria layers. Our preliminary interpretations of the Middle Scoria indicate that Okmok Volcano may be capable of highly explosive basaltic Plinian and hydrovolcanic eruptions.

Wong, L. J.

2002-12-01

190

US Geological Survey Volcano Hazards Program  

NSDL National Science Digital Library

The US Geological Survey Volcano Hazards Program website presents its objectives "to advance the scientific understanding of volcanic processes and to lessen the harmful impacts of volcanic activity." The public can explore information on volcano monitoring, warning schemes, and emergency planning. Students and educators can find out about the types, effects, location, and history of volcano hazards. The website offers recent online volcano reports and maps, volcano factsheets, videos, and a photo glossary. Teachers can find online versions of many educational volcano-related books and videos. The website features the volcanic observatories in Alaska, the Cascades, Hawaii, Long Valley, and Yellowstone.

191

Precise Hypocenter Location of High-Frequency-Onset Earthquakes, During the Initial Stages of Activity at Soufriere Hills Volcano, Montserrat  

NASA Astrophysics Data System (ADS)

Volcano-tectonic (VT) earthquakes are interpreted as resulting from slip on fractures or faults induced by magma pressurisation. Examination of VT earthquakes can provide information on areas of magma storage and any induced stress state due to such pressurisation. The andesite stratovolcano of Soufriere Hills, Montserrat began showing an increase in seismicity in 1992, with this rapidly increasing towards the end of 1994. The eruption commenced in July 1995 with phreatic activity and during the subsequent and ongoing eruption there have been several phases, with VT seismicity varying throughout this period. Here we use data from the initial stages (July 1995 - October 1996) of activity on Montserrat to better characterise the magma storage and transport system, and stress changes which have occurred during this eruption. Recent developments have allowed more precise hypocenter relocations using relative positioning techniques. Therefore we have examined seismic data recorded at SHV, utilising the Waldhauser and Ellsworth (2000) precise relocation technique. Previous work by Aspinall et al. (1998) highlighted three main clusters, one stretching out from the summit to the NE (the Arm) showing a SW progression through time, another mass of hypocentres under St. Georges Hill and a NW-SE trending summit cluster which extended from the surface down to ~5km. Our results are comparable, but the decreased relative position errors in this study enable further analysis. We show that not only did hypocenters migrate to the SW through time in the Arm cluster, but also with decreasing depth. The St. Georges Hill cluster is also elongated and shows a temporal movement of hypocenters deepening to the NW with time. A second phase of seismicity clustered beneath the summit mainly between 1.3 and 2.3 km depth below sea level during early 1996. These hybrid events accompanied a significant increase in extrusion rate. This summit cluster persisted with a NW-SE trend in map view.

Miller, V. L.; Ammon, C. J.; Voight, B.; Thompson, G.

2006-12-01

192

Plunge Pools in Submarine Canyons  

NASA Astrophysics Data System (ADS)

Many submarine canyon systems include well-defined intra-canyon depressions. Often, these depressions are found at the base of scarps along the canyon thalweg, with morphologic characteristics similar to subarial plunge pools formed at waterfalls. One plausible mechanism for the origin of these features is scouring during submarine debris flows. Other processes which can plausibly contribute to the formation of re-entrants and depressions in submarine canyons include erosion by spring sapping, slumping, collapse following gas expulsion or subsurface dissolution, and channel damming by mass wasting of canyon walls. We have examined multibeam bathymetry surveys of a number of submarine canyons, and identified more than fifteen apparent plunge pools within submarine canyon systems offshore of Australia, Hawaii, and North America. These features range in scale from 2 km long, 6 km across, and 300 m deep (the largest plunge pool in Perth Canyon, offshore Australia) down to as small as 10 m deep and 150 m across (the smallest plunge pool identified offshore Kohala, Hawaii). Although these features vary considerably in scale, they share common characteristics. Each basin is located at the base of a headwall scarp within the canyon, and is bounded on the down-canyon side by a sill. Measurements of the characteristic dimensions of the plunge pools show that the basin depth (defined relative to the down-canyon sill) increases with the headwall scarp height,. However, the across and down canyon basin widths do not strongly correlate with the scarp height, and seem to be more closely related to the width of the overall canyon channel. The Monterey Bay Aquarium Research Institute investigated three apparent plunge pools using ROV Tiburon during a spring 2001 expedition to the Hawaiian Islands. These basins are located in submarine canyons on the north side of Molokai and the Kohala coast of Hawaii. Our ROV observations support the hypothesis that these intra-canyon depressions are formed through scouring during submarine debris flows. In all cases the down-canyon depression sills are dams composed of debris piles, with angular rubble exposed on the depression side and sand covering the down-canyon side. The Molokai plunge pool is draped with mud and silt, suggesting no recent activity. However, the Kohala plunge pools show clear signs of recent scour and no sediment cover. The headwalls above the plunge pools expose layered volcanoclastic and lava flow units, with more resistant layers frequently forming vertical or overhanging walls. We interpret these canyons as being largely formed through retrogressive (headward) erosion and slope failure. Periodic rockfalls and debris flows following undercutting of the headwalls scours the depressions, builds the pool dams, and both lengthens and deepens the canyons. Modern bathymetric surveys indicate that plunge pools occur in many, but not most submarine canyons. Our ROV observations suggest that stratigraphic variability is a key prerequisite for plunge pool formation. Headwall scarps can persist within active canyons when the existence of more and less resistive layers allows for differential erosion. In turn, plunge pools form when headwall scarps are persistent features.

Caress, D. W.; Greene, H. G.; Paull, C. K.

2002-12-01

193

THE SUBMARINE REVIEW SUMMER 2012  

E-print Network

THE SUBMARINE REVIEW 1 SUMMER 2012 SPURRING INNOVATION AT THE DECKPLATE LEVEL IN THE SUBMARINE FORCE LT Ryan P. Hilger, USN Submarine Student at the Naval Postgraduate School he phenomenal success to alter how we design and operate our submarines. Vice Admiral Richardson happily announced after

194

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

195

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.

196

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

197

Thomas A. Jaggar, Hawaiian Volcano Observatory  

USGS Multimedia Gallery

Thomas A. Jaggar founded the Hawaiian Volcano Observatory in 1912 and served as its Director until 1940.  Shown here in 1925, Jaggar is at work in HVO's first building, which, at the time, was located on the northeast rim of K?lauea Volcano’s summit caldera, near the present-day Volc...

198

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.

199

Volcano: Tectonic Environments  

NSDL National Science Digital Library

This site describes where volcanoes are found in terms of plate tectonics and explains why they occur at those locations. S map shows that volcanoes are located mainly at plate boundaries. Then there are explanations for plate motion, mantle convection, and magma generation. The three types of plate boundaries are listed as divergent, convergent, and transform. There is also information about the relationship between types of boundaries and types of volcanism and the fact that intraplate volcanism describes volcanic eruptions within tectonic plates. The site features a diagram that depicts each type, with a link for more information about the Earth's internal heat energy and interior structure.

Victor Camp

200

Erupting Volcanoes!  

NSDL National Science Digital Library

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

201

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

2010-08-20

202

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.

Huber, Patrick

2009-01-01

203

Potential for SGD induced submarine geohazard off southwestern Taiwan  

NASA Astrophysics Data System (ADS)

The submarine groundwater discharge (SGD) is not only play important roles on material exchange between land and sea, it may also trigger liquefaction process and induce further submarine geohazards in coastal zone. Since 2006, Southern Taiwan was experienced a series of natural hazards including earthquakes and typhoon that induced severe landslides and flooding and caused huge human lives and economics losses. These natural hazards also touched off submarine cable-break incidents off southwestern Taiwan from Gaoping Slope to the northern terminus of the Manila Trench. After the 2006 Pingtung Earthquake, the local fishermen reported disturbed waters at the Fangliao submarine canyon head. Although many researches conjectured the disturbed waters may caused by the eruption of submarine volcanoes which has been widely discovered off the southwestern Taiwan. The subbottom profiles reveal a series of faults and liquefaction strata exist near the head of Fanliao submarine canyon and acoustically transparent sediments with doming structures also observed at the adjacent area. Moreover, we also found pockmarks with acoustic blanking under it on the Gaoping Shelf and a series of gaseous pluming gushed from the seafloor was also observed in the shallow waters. Integrate all these data, we may reasonably infer the disturbed waters which reported by the fishermen may caused by the liquefaction process on the seafloor. In addition to geophysical observations, natural geochemical tracers (radon and radium) in conjunction with side-scan sonar were used to evaluate the distribution of SGD system in the study area. All the evidences indicate that the large earthquake in conjunction with high pore fluid pressures in the surface sediment might have easily triggered liquefaction process and generated large debris flow and swept the submarine cables away from the Fangliao submarine canyon head to the abyss.

Su, C.; Lin, C.; Cheng, Y.; Chiu, H.

2013-12-01

204

Discovery of the Largest Historic Silicic Submarine Eruption  

NASA Astrophysics Data System (ADS)

It was likely twice the size of the renowned Mount St. Helens eruption of 1980 and perhaps more than 10 times bigger than the more recent 2010 Eyjafjallajökull eruption in Iceland. However, unlike those two events, which dominated world news headlines, in 2012 the daylong submarine silicic eruption at Havre volcano in the Kermadec Arc, New Zealand (Figure 1a; ~800 kilometers north of Auckland, New Zealand), passed without fanfare. In fact, for a while no one even knew it had occurred.

Carey, Rebecca J.; Wysoczanski, Richard; Wunderman, Richard; Jutzeler, Martin

2014-05-01

205

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.

206

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.

James Cameron

2013-01-01

207

Dynamic Controls of Fluid and Gas Flow at North Alex Mud Volcano, West Nile Delta  

NASA Astrophysics Data System (ADS)

The North Alex Mud Volcano (NAMV) is located at a water depth of 500m above a large deep-seated gas reservoir on the upper slope of the western Nile deep-sea fan. It has been the object of an integrated study of fluid and gas flow using existing and newly developed observatory technologies to better constrain and quantify devolatilisation and defluidisation patterns and their long-term variability in relation to underlying hydrocarbon reservoirs. As it is known that the activity of mud volcanoes varies significantly over periods of months and weeks, the assessment of the activity of NAMV focuses on proxies of fluid and gas emanations. Submarine mud volcanoes are usually characterized by fluid formation and fluidization processes occuring at depths of several kilometers below the seafloor, driving a complex system of interacting geochemical, geological and microbial processes. Mud volcanoes are natural leakages of oil and gas reservoirs. Near-surface observations made at such sites can therefore be used to monitor phenomena that occur at greater depth. Since the initiation of the project in 2007, NAMV has arguably become one of the best-instrumented mud volcanoes worldwide with a network of observatories collecting long-term records of chemical fluxes, seismicity, temperature, ground deformation, and methane concentration. In addition five research cruises collected complementary geophysical and geological data and samples. In the summer of 2010 a large number of monitoring systems has been recovered which provide us with a synoptic view of the internal dynamics of an active mud volcano. We will present an integrated analysis based on ship-based and sea-floor observations.

Brueckmann, W.; Bialas, J.; Jegen, M. D.; Lefeldt, M. R.; Hoelz, S.; Feseker, T.

2010-12-01

208

Postshield stage transitional volcanism on Mahukona Volcano, Hawaii  

Microsoft Academic Search

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\\u000a on submarine Mahukona Volcano, Hawaii. These ages are younger than the inferred end of the tholeiitic shield stage and indicate\\u000a that the volcano had entered the postshield alkalic stage before going extinct. Previously reported elevated helium isotopic\\u000a ratios of lavas

David A. Clague; Andrew T. Calvert

2009-01-01

209

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

210

A submarine canyon conduit under typhoon conditions off Southern Taiwan  

Microsoft Academic Search

The function of a submarine conduit under typhoon conditions is examined. The study site is the Kao-ping river, shelf, and submarine canyon (KPRSC) system located off southern Taiwan on a wave-dominated microtidal coast. The head of the canyon is located approximately 1km off the river mouth. Two comprehensive 1-month field experiments were carried out in 2000 and 2002 during the

James T. Liu; Hui-Ling Lin; Jia-Jang Hung

2006-01-01

211

In search of ancestral Kilauea volcano  

USGS Publications Warehouse

Submersible observations and samples show that the lower south flank of Hawaii, offshore from Kilauea volcano and the active Hilina slump system, consists entirely of compositionally diverse volcaniclastic rocks; pillow lavas are confined to shallow slopes. Submarine-erupted basalt clasts have strongly variable alkalic and transitional basalt compositions (to 41% SiO2, 10.8% alkalies), contrasting with present-day Kilauea tholeiites. The volcaniclastic rocks provide a unique record of ancestral alkalic growth of an archetypal hotspot volcano, including transition to its tholeiitic shield stage, and associated slope-failure events.

Lipman, P.W.; Sisson, T.W.; Ui, T.; Naka, J.

2000-01-01

212

Volcano Landslides  

NSDL National Science Digital Library

Information given in this United States Geological Survey (USGS) publication includes a description of volcano landslides, how they are generated, and their effects on surrounding areas. Case studies of specific volcano landslides are linked from this page, including Mt. St. Helens, Otake in Japan, Huila in Columbia, Mt. Rainier, and Casita in Nicaragua.

213

Chikurachki Volcano  

Atmospheric Science Data Center

... plume from the April 22, 2003, eruption of the Chikurachki volcano is portrayed in these views from the Multi-angle Imaging ... the volcanically active Kuril Island group, the Chikurachki volcano is an active stratovolcano on Russia's Paramushir Island (just south of ...

2013-04-16

214

Redoubt Volcano  

USGS Multimedia Gallery

Ascending eruption cloud from Redoubt Volcano as viewed to the west from the Kenai Peninsula. The mushroom-shaped plume rose from avalanches of hot debris (pyroclastic flows) that cascaded down the north flank of the volcano. A smaller, white steam plume rises from the summit crater. ...

215

Spectral Analysis of Surface Features of Subaquaeous Pyroclastic Flow Deposits Around Santorini Volcano, Greece  

NASA Astrophysics Data System (ADS)

Multibeam bathymetry mapping and seismic airgun surveys of the submarine region around the Santorini volcanic field in the Hellenic Arc (Greece) have revealed regions of terraced or step-like topography. These features may be related to the transport and deposition of submarine pyroclastic flows from the last major eruption of this volcano (~3600yrs. B.P.). The uppermost sediment sequence identified in seismic records has an average thickness of approximately 29 meters and may represent the pyroclastic flow deposits from this eruption. These terraced or step-like features are mainly located in areas that are approximately five kilometers offshore and at depths in the range of 200 to 800 meters. The seafloor in these areas has slope ratios on the order of 1:20. Profiles of the seafloor topography were sampled from seismic profiles that radiate from the Sanotrini caldera in five regions of interest. Spectral analysis of seafloor topography has been carried out to determine spectral characteristics of these features, including power spectrum, periodicity and amplitude of the waveforms, variance, and roughness of topography. The results are compared to surface features of the subaqueous pyroclastic deposits from the 1883 explosive eruption of Krakatau (Indonesia) and other areas with similar environments, to determine the parameters that are characteristic of this new feature of submarine volcaniclastic deposits.

Croff, K. L.; Sigurdsson, H.; Carey, S.; Alexandri, M.; Sakellariou, D.; Nomikou, P.

2006-12-01

216

Volcano Hazards Assessment for Medicine Lake Volcano, Northern California  

USGS Publications Warehouse

Medicine Lake volcano (MLV) is a very large shield-shaped volcano located in northern California where it forms part of the southern Cascade Range of volcanoes. It has erupted hundreds of times during its half-million-year history, including nine times during the past 5,200 years, most recently 950 years ago. This record represents one of the highest eruptive frequencies among Cascade volcanoes and includes a wide variety of different types of lava flows and at least two explosive eruptions that produced widespread fallout. Compared to those of a typical Cascade stratovolcano, eruptive vents at MLV are widely distributed, extending 55 km north-south and 40 km east-west. The total area covered by MLV lavas is >2,000 km2, about 10 times the area of Mount St. Helens, Washington. Judging from its long eruptive history and its frequent eruptions in recent geologic time, MLV will erupt again. Although the probability of an eruption is very small in the next year (one chance in 3,600), the consequences of some types of possible eruptions could be severe. Furthermore, the documented episodic behavior of the volcano indicates that once it becomes active, the volcano could continue to erupt for decades, or even erupt intermittently for centuries, and very likely from multiple vents scattered across the edifice. Owing to its frequent eruptions, explosive nature, and proximity to regional infrastructure, MLV has been designated a 'high threat volcano' by the U.S. Geological Survey (USGS) National Volcano Early Warning System assessment. Volcanic eruptions are typically preceded by seismic activity, but with only two seismometers located high on the volcano and no other USGS monitoring equipment in place, MLV is at present among the most poorly monitored Cascade volcanoes.

Donnelly-Nolan, Julie M.; Nathenson, Manuel; Champion, Duane E.; Ramsey, David W.; Lowenstern, Jacob B.; Ewert, John W.

2007-01-01

217

The eect of a submarine canyon on the river sediment dispersal and inner shelf sediment movements in  

E-print Network

The e¡ect of a submarine canyon on the river sediment dispersal and inner shelf sediment movements 2001 Abstract This study examines the influence of a submarine canyon on the dispersal of sediments the head region of the Kao-ping Submarine Canyon whose landward terminus is located approximately 1 km

Lin, Andrew Tien-Shun

218

Model Volcanoes  

NSDL National Science Digital Library

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

219

Sedimentary facies in submarine canyons  

NASA Astrophysics Data System (ADS)

Submarine canyons are the major conduits by which sediment, pollutants and nutrients are transported from the continental shelf out into the deep sea. The sedimentary facies within these canyons are remarkably poorly understood because it has proven difficult to accurately sample these heterogeneous and bathymetrically complex environments using traditional ship-based coring techniques. This study exploits a suite of over 100 precisely located vibracores collected using remotely operated vehicles in ten canyons along the northern Californian margin, enabling better understanding of the facies that exist within submarine canyons, their distribution, and the processes responsible for their formation. The dataset reveals three major facies types within the submarine canyons: extremely poorly sorted, coarse-grained sands and gravels with complex and indistinct internal grading patterns and abundant floating clasts; classical normally graded thin bedded turbidites; and a variety of fine-grained muddy deposits. Not all facies are observed within individual canyons, in particular coarse-grained deposits occur exclusively in canyons where the canyon head cuts up to the modern day beach, whereas finer grained deposits have a more complex distribution that relates to processes of sediment redistribution on the shelf. Pairs of cores collected within 30 meters elevation of one another reveal that the coarse-grained chaotic deposits are restricted to the basal canyon floor, with finer-grained deposits at higher elevations on the canyon walls. The remarkable heterogeneity of the facies within these sediment cores illustrate that distinctive processes operate locally within the canyon. In the authors' experience the canyon floor facies represent an unusual facies rarely observed in ancient outcrops, which potentially results from the poor preservation of ancient coarse-grained canyon deposits in the geological record.

Sumner, E.; Paull, C. K.; Gwiazda, R.; Anderson, K.; Lundsten, E. M.; McGann, M.

2013-12-01

220

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

221

Tlie Submarine Caves of Bermuda  

E-print Network

Tlie Submarine Caves of Bermuda ThomasM. Iliffe Bermuda Biological Station, Ferry Reach 1-15 #12;The SubmarineCavesofBermuda ThomasM.Iliffe BermudaBiological Station,Ferry Reach 1-15 Abstract Bermuda the volcanic pedistal. Three types of submarine limestone cave morphology have so far been identified

Iliffe, Thomas M.

222

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....

223

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 ...

224

Plume and Pyroclast Dynamics Observed During a Submarine Explosive Eruption at NW Rota1, Mariana arc  

Microsoft Academic Search

Strombolian submarine eruptions at 550-560 m water depth were observed in April, 2006 at NW Rota-1 volcano, Mariana arc. During six dives with the Jason II remotely operated vehicle observations made at close range documented a diverse and increasingly energetic range of activity. The initial dives observed lava extrusion followed by small, explosive bursts. Activity steadily increased to produce gas

N. Deardorff; K. V. Cashman; W. W. Chadwick; R. W. Embley

2007-01-01

225

Volcano Hazards Program Webcams  

MedlinePLUS

Volcano Hazards Program Webcams Below is a list of webcams of U.S. volcanoes. All webcams are operated ... the webcam. Pu`u `O`o vent, Kilauea Volcano (HVO) Halema`uma`u from HVO, Kilauea Volcano ( ...

226

Submarine: Soda Cup Lander  

NSDL National Science Digital Library

In this activity (on page 2), learners create a submarine using a plastic cup. This is a fun way to learn about buoyancy and density. Extensions for this activity, such as adding a propeller or manometer, are also included.
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. Learners will also need an adult's help if they use a glue gun to attach the film canister to the plastic cup.

James Cameron

2013-01-01

227

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.

Jocelyn Young

2007-02-01

228

Automating the hunt for volcanoes on Venus  

Microsoft Academic Search

Our long-term goal is to develop a trainable tool for locating patterns of interest in large image databases. Toward this goal we have developed a prototype system, based on classical filtering and statistical pattern recognition techniques, for automatically locating volcanoes in the Magellan SAR database of Venus. Training for the specific volcano-detection task is obtained by synthesizing feature templates (via

M. C. Burl; U. M. Fayyad; P. Perona; P. Smyth; M. P. Burl

1994-01-01

229

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

230

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

231

Nyamuragira Volcano Erupts  

NASA Technical Reports Server (NTRS)

Nyamuragira volcano erupted on July 26, 2002, spewing lava high into the air along with a large plume of steam, ash, and sulfur dioxide. The 3,053-meter (10,013-foot) volcano is located in eastern Congo, very near that country's border with Rwanda. Nyamuragira is the smaller, more violent sibling of Nyiragongo volcano, which devastated the town of Goma with its massive eruption in January 2002. Nyamuragira is situated just 40 km (24 miles) northeast of Goma. This pair of images was acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra satellite, on July 26. The image on the left shows the scene in true color. The small purple box in the upper righthand corner marks the location of Nyamuragira's hot summit. The false-color image on the right shows the plume from the volcano streaming southwestward. This image was made using MODIS' channels sensitive at wavelengths from 8.5 to 11 microns. Red pixels indicate high concentrations of sulphur dioxide. Image courtesy Liam Gumley, Space Science and Engineering Center, University of Wisconsin-Madison

2002-01-01

232

Submarine Volcanic Cones in the Central Aleutian Arc: Relationship to Arc Rifting and Oblique Plate Convergence  

NASA Astrophysics Data System (ADS)

Plate convergence along the 2200km Aleutian Arc varies from orthogonal at the Alaskan Peninsula to fully strike-slip on the west end of the arc. Deformation response of the upper plate to oblique convergence appears to accelerate markedly between Adak (177W) and Amchitka Pass (180W). On a regional scale, this deformation appears to be concentrated at the boundaries of crustal blocks, with clockwise rotation and westward translation [Geist et al., Tectonics 7, 327-341, 1988]. In the block rotation model, extensional rift structures develop between the blocks in arc-normal orientation. Summit basins develop at the northern, trailing edge of the blocks in arc-parallel orientation. These summit basins are located near or within the volcanic front. Thus structures in the upper plate driven by oblique convergence are predicted to interact with arc volcanism. We report on multibeam mapping in 2003-2004 and ROV Jason II dives in 2004. The data reveal locations and patterns of fault structures, volcanic cones, and lithologies in several locations critical to understanding the arc's response to oblique convergence. A large submarine volcano, named Amchixtam Chaxsxii in the Unangan language, was mapped next to Semisopochnoi Island. Additional small cones are identified on the flank of Tanaga Volcano, and near Bobrof Volcano on possible fault structures. The largest extensional `block boundary' is located at Amchitka Pass; in this area the seafloor is offset by a network of faults. Small volcanic cones are clustered at these faults. Some show signs of erosion and mass wasting; others, especially deeper ones, are intact. Surfaces are dominated by `a`a flows and spatter, and have light sediment cover and moderately fresh lavas. Our mapping focused on specific sites that were chosen to be representative, and suggests that (1) small, probably monogenetic cones are common; (2) the cones occur preferentially in areas of extensional faulting in the volcanic front; (3) these cones are present largely because of oblique convergence and arc deformation. Geochemical analyses will test their relationship to nearby subaerial arc volcanoes.

Reynolds, J. R.; Greene, G.; Krutikov, L.; Vallier, T. L.

2004-12-01

233

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.

234

Making a Submarine.  

ERIC Educational Resources Information Center

Describes Archimedes principle and why a ship sinks when it gets a hole in it. Suggests an activity for teaching the concept of density and water displacement through the construction of a simple submarine. Includes materials and procedures for this activity. (KHR)

Cornacchia, Deborah J.

2002-01-01

235

Intermediate products of sulfur disproportional reaction and their physical role in effusive to explosive submarine volcanic activity  

NASA Astrophysics Data System (ADS)

Recent direct observations of submarine volcanic activity in the Mariana Arc are giving us a chance to examine the role of volcanic gas in submarine volcanic conduits. Unlike subaerial volcanoes, where hydrogeologic conditions have different character from place to place, the overlying water mass above submarine volcanoes gives a uniform hydrographic setting. Currently, the places where we can directly observe submarine volcanic activity are located deeper than 400 m, which raises the boiling point of seawater to over 240 deg C. This situation allows us to examine the interaction of volcanic gases with ambient seawater at a shorter distance from the magma source than at subaerial volcanic settings. Arc volcano settings give us longer and more frequent opportunities to make observations and provide a more diverse range of submarine volcanism than ridge settings. Among the three major components of volcanic gases (i.e., H2O, CO2 and SO2), water follows a two phase boundary below the critical temperature after volatile components leave from the magmatic source. Milky sulfur sol bearing hydrothermal fluid is commonly observed throughout Mariana active sites. Most of the sulfur sol (colloidal elemental sulfur and polysulfides) might be formed by disproportional reaction of sulfur dioxide with seawater when water vapor shrinks to liquid water. The reaction creates not only sulfur sol but also various types of sulfite, which affects the pH of seawater. We detected short-lived sulfite species in the water column above several active Mariana volcanoes such as NW Rota-1, Daikoku and Nikko by on-board HPLC. Because most observations are made on the liquid phase side of H2O boundary, it is very hard to get data to investigate the physical and chemical sulfur sol forming process occurring on the vapor phase side or at the critical state (i.e., near the magma source process). Carbon dioxide behaves as a gas at a wide range of pressures and temperatures and carries heat and sulfur dioxide effectively and quickly to the seafloor. At Nikko Seamount carbon dioxide bubbles penetrated the intentionally excavated liquid sulfur pond beneath a hydrothermal vent. The bubbles have misty surfaces, which indicated progressive disproportional reaction of carried sulfur dioxide with ambient seawater. Although the temperature along most of the conduit up to the seafloor is above the freezing point of elemental sulfur, coalescence of sulfur sol, which creates masses of liquid sulfur, mostly occur when the mixture of hydrothermal fluid and volcanic gas leaves the two phase boundary of water near the seafloor. The polymerization state of liquid sulfur governs the resistance against volcanic gas flow near the surface of volcanic conduits. Several types of liquid sulfur spherules were sampled at NW Rota-1 eruption site.

Nakamura, K.; Takano, B.; Butterfield, D. A.; Resing, J.; Chadwick, W. W.; Embley, R. W.

2009-12-01

236

Volcano Baseball  

NSDL National Science Digital Library

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

American Association for the Advancement of Science

2009-01-01

237

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

238

Volcano Hazards Program  

USGS Publications Warehouse

Diagram of common volcano hazards. The U.S. Geological Survey Volcano Hazards Program (VHP) monitors unrest and eruptions at U.S. volcanoes, assesses potential hazards, responds to volcanic crises, and conducts research on how volcanoes work. When conditions change at a monitored volcano, the VHP issues public advisories and warnings to alert emergency-management authorities and the public. See http://volcanoes.usgs.gov/ to learn more about volcanoes and find out what's happening now.

Venezky, Dina Y.; Myers, Bobbie; Driedger, Carolyn

2008-01-01

239

Submarine Paleoseismology Based on Turbidite Records  

E-print Network

Submarine Paleoseismology Based on Turbidite Records Chris Goldfinger College of Oceanic trigger processes such as turbidity currents, submarine landslides, tsunami (which may be recorded both counterparts. This article reviews the use of submarine turbidite deposits for paleoseismology, focuses

Goldfinger, Chris

240

Arctic Submarine Slope Stability  

NASA Astrophysics Data System (ADS)

Submarine landsliding represents aside submarine earthquakes major natural hazard to coastal and sea-floor infrastructure as well as to coastal communities due to their ability to generate large-scale tsunamis with their socio-economic consequences. The investigation of submarine landslides, their conditions and trigger mechanisms, recurrence rates and potential impact remains an important task for the evaluation of risks in coastal management and offshore industrial activities. In the light of a changing globe with warming oceans and rising sea-level accompanied by increasing human population along coasts and enhanced near- and offshore activities, slope stability issues gain more importance than ever before. The Arctic exhibits the most rapid and drastic changes and is predicted to change even faster. Aside rising air temperatures, enhanced inflow of less cooled Atlantic water into the Arctic Ocean reduces sea-ice cover and warms the surroundings. Slope stability is challenged considering large areas of permafrost and hydrates. The Hinlopen/Yermak Megaslide (HYM) north of Svalbard is the first and so far only reported large-scale submarine landslide in the Arctic Ocean. The HYM exhibits the highest headwalls that have been found on siliciclastic margins. With more than 10.000 square kilometer areal extent and app. 2.400 cubic kilometer of involved sedimentary material, it is one of the largest exposed submarine slides worldwide. Geometry and age put this slide in a special position in discussing submarine slope stability on glaciated continental margins. The HYM occurred 30 ka ago, when the global sea-level dropped by app. 50 m within less than one millennium due to rapid onset of global glaciation. It probably caused a tsunami with circum-Arctic impact and wave heights exceeding 130 meters. The HYM affected the slope stability field in its neighbourhood by removal of support. Post-megaslide slope instability as expressed in creeping and smaller-scaled slides are the consequence. Its geometrical configuration and timing is different from submarine slides on other glaciated continental margins. Thus, it raises the question whether slope stability within the Arctic Ocean is governed by processes specific to this environment. The extraordinary thick slabs (up to 1600 m) that were moved translationally during sliding rise the question on the nature of the weak layers associated with this process. Especially theories involving higher pore pressure are being challenged by this observation, because either extreme pore pressures or alternative explanations (e.g. mineralogical and/or textural) can be considered. To assess the actual submarine slope stability and failure potential in the Arctic Ocean, we propose to drill and recover weak layer material of the HYM from the adjacent intact strata by deep drilling under the framework of Integrated Ocean Drilling Program. This is the only method to recover weak layer material from the HYM, because the strata are too thick. We further propose to drill into the adjacent deforming slope to identify material properties of the layers acting as detachment and monitor the deformation.

Winkelmann, D.; Geissler, W.

2010-12-01

241

Volcano Seismology  

Microsoft Academic Search

-- A fundamental goal of volcano seismology is to understand active magmatic systems, to characterize the configuration of such systems, and to determine the extent and evolution of source regions of magmatic energy. Such understanding is critical to our assessment of eruptive behavior and its hazardous impacts. With the emergence of portable broadband seismic instrumentation, availability of digital networks with

BERNARD CHOUET

2003-01-01

242

Klyuchevskaya Volcano  

NASA Technical Reports Server (NTRS)

The Klyuchevskaya Volcano on Russia's Kamchatka Peninsula continued its ongoing activity by releasing another plume on May 24, 2007. The same day, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured this image, at 01:00 UTC. In this image, a hotspot marks the volcano's summit. Outlined in red, the hotspot indicates where MODIS detected unusually warm surface temperatures. Blowing southward from the summit is the plume, which casts its shadow on the clouds below. Near the summit, the plume appears gray, and it lightens toward the south. With an altitude of 4,835 meters (15,863 feet), Klyuchevskaya (sometimes spelled Klyuchevskoy or Kliuchevskoi) is both the highest and most active volcano on the Kamchatka Peninsula. As part of the Pacific 'Ring of Fire,' the peninsula experiences regular seismic activity as the Pacific Plate slides below other tectonic plates in the Earth's crust. Klyuchevskaya is estimated to have experienced more than 100 flank eruptions in the past 3,000 years. Since its formation 6,000 years ago, the volcano has seen few periods of inactivity. NASA image courtesy the MODIS Rapid Response Team at NASA GSFC. The Rapid Response Team provides daily images of this region.

2007-01-01

243

Flushing submarine canyons  

Microsoft Academic Search

The continental slope is a steep, narrow fringe separating the coastal zone from the deep ocean. During low sea-level stands, slides and dense, sediment-laden flows erode the outer continental shelf and the continental slope, leading to the formation of submarine canyons that funnel large volumes of sediment and organic matter from shallow regions to the deep ocean1. During high sea-level

Miquel Canals; Pere Puig; Xavier Durrieu de Madron; Serge Heussner; Albert Palanques; Joan Fabres

2006-01-01

244

A new species of Copepoda Harpacticoida, Xylora calyptogenae spec. n., with a carnivorous life-style from a hydrothermally active submarine volcano in the New Ireland Fore-Arc system (Papua New Guinea) with notes on the systematics of the Donsiellinae Lang, 1948  

NASA Astrophysics Data System (ADS)

A new species of harpacticoid copepods, Xylora calyptogenae spec. n., from Edison Seamount, a hydrothermally active submarine volcano in the New Ireland Fore-Arc system (Papua New Guinea) is described. The new species belongs to the Donsiellinae Lang, 1944, a highly specialised taxon, the members of which have previously been encountered only in association with decaying wood and/or wood-boring isopods. A closer relationship of the Donsiellinae with the Pseudotachidiidae Lang, 1936, can be stated on the basis of characteristics concerning the setation and/or segmentation of A1, A2, Mxl, Mxp, the shape of the female P5, anal somite, sexual dimorphisms on P2 and P3 and missing caudal seta I. Within the Pseudotachidiidae, the Donsiellinae again can be well characterized, e.g. by the setation and segmentation of A2, Mxl, swimming-legs, the shape of P1, female P5, male P2, sexual dimorphism and male P5. The Donsiellinae share some apomorphies with the pseudotachidiid subtaxon Paranannopinae Por, 1986: setation/segmentation of Mx, P1, A1. X. calyptogenae spec. n. is more closely related to Xylora bathyalis Hicks 1988 living in the deep sea wood substrata in New Zealand waters. Some traits of the evolutionary history of the Donsiellinae become evident, probably starting from the more primitive deep sea taxa X .calyptogenae spec. n., which lives in the hydrothermal seafloor in the absence of decaying wood, and X. bathyalis, which is found in decaying wood but not necessarily associated with the wood-boring isopod Limnoria Leach, 1814, towards the more advanced genera such as Donsiella Stephensen, 1936, which invades shallow waters and, further, clings to Limnoria, forming a close and, for the copepod, probably obligatory association. The specialised mouthparts of X. calyptogenae spec. n. seem to facilitate the grabbing and fixing of larger and/or active food items. This is confirmed by the presence of a large prey organism, presumably a copepod, consumed either alive or dead, in the gut of one of the available specimens. This morphology of the mouthparts is also shared by the closely related X. bathyalis.

Willen, Elke

2006-12-01

245

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

246

Hydroacoustic Records of the First Historical Eruption of Anatahan Volcano, Mariana Islands  

NASA Astrophysics Data System (ADS)

For the past decade, NOAA/Pacific Marine Environmental Laboratory has monitored volcano-seismic activity from western Pacific island-arc volcanoes using an array of U.S. Navy hydrophones (called SOSUS) deployed at fixed locations throughout the North Pacific Ocean. SOSUS hydrophones are mounted within the SOFAR channel and record the hydroacoustic tertiary phase or T-wave of oceanic earthquakes from throughout the Pacific basin. Since acoustic T-waves obey cylindrical energy attenuation as opposed to the spherical attenuation of solid-earth seismic phases, sound channel hydrophones can detect often smaller and therefore more numerous earthquakes than land-based seismic networks. This property allowed for the detection of harmonic tremor from a submarine volcano in the Volcano Islands on hydrophones >14,000 km away in the eastern Pacific. The first historical eruption of Anatahan Volcano appears to have started (from satellite imagery) at 1730Z on 10 May, with an ash plume visible by 2232Z (BGVN, 5 May 2003). Records from a broadband seismometer deployed on nearby ( ˜6.5 km) Sarigan Island indicate earthquake activity increased at about 1300Z on 10 May (D. Weins, pers com). SOSUS hydrophones in the western Pacific ( ˜4000 km distant) also recorded increased earthquake activity at 1300Z on 10 May as well as continuous, low-frequency (<10 Hz) energy (possible volcanic tremor) that began about a day before the seismicity. The earthquakes and tremor were detected on only two SOSUS hydrophones and therefore it was not possible to estimate their source location. The arrival azimuth of the signals were, however, consistent with a source in the Mariana Islands. To complement the SOSUS hydrophone array coverage in the western Pacific Ocean, an array of five autonomous hydrophones were deployed in February 2003 (sponsored by NOAA's Ocean Exploration Program) within the SOFAR channel along the active island- and back-arc of the Mariana Islands. All five hydrophones (1-110 Hz bandpass) were deployed between 13° N and 22° N, with one hydrophone located within 50 km of Anatahan Island. These five hydrophone will be recovered in September 2003, and it is anticipated their data will provide insights into Anatahan, as well as Mariana Island wide, volcano-seismic activity.

Dziak, R.; Park, M.; Matsumoto, H.; Fox, C.; Byun, S.; Fowler, M.; Haxel, J.; Embley, R.

2003-12-01

247

Michigan Tech Volcanoes  

NSDL National Science Digital Library

The Michigan Tech Volcanoes Page encourages collaborative, interdisciplinary work on active volcanos, and links to resources for the Santa Maria Decade Volcano in Guatemala and for Central America's most frequently active volcano, Fuego. Also includes images of Pinatubo Volcano [one nice one taken from the Space Shuttle Endeavor] and some movies of laharic activity.

248

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.

249

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

250

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

251

Earthquake occurrence reveals magma ascent beneath volcanoes and seamounts in the Banda region  

NASA Astrophysics Data System (ADS)

Characteristic seismicity patterns beneath the volcanic arcs of the Banda region, SE Asia, suggest that magmatic processes have recently occurred beneath submarine portions of the arcs, forming yet-unrecognised submarine volcanoes. We have found that almost 50 % of earthquakes spatially associated with the Banda and Ambon volcanic arcs occurred in sequences with epicenters often concentrated in a small area and foci distributed in vertically elongated domains. The most pronounced occurrence of such earthquake series and swarms was observed in the area of the Manipa submarine basin (latitude 3.75°S, longitude 127.5°E, ESE of Buru Island), the remarkable morphology of which resembles a huge caldera (60 km in diameter) with a distinct cone seamount in its center, reaching almost 3000 m above seafloor. Another candidate for an unrecognised submarine volcano is an area between volcanoes Banda Api and Manuk, with a huge 1973/74 earthquake swarm. We assume that such a specific occurrence of earthquakes is induced by magma ascent and migration along faults above the subducting slab, with magma possibly occasionally reaching the sea floor. Utilization of teleseismic data can thus reveal activation of plumbing systems of submarine volcanoes, and highlight areas with the potential of near-future volcanic events.

Špi?ák, Aleš; Kuna, Václav; Van?k, Ji?í

2013-12-01

252

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

253

33 CFR 165.1328 - Regulated Navigation Area; U.S. Navy submarines, Hood Canal, WA.  

Code of Federal Regulations, 2012 CFR

...Navigation Area; U.S. Navy submarines, Hood Canal, WA. 165.1328 Section 165.1328...Navigation Area; U.S. Navy submarines, Hood Canal, WA. (a) Location. The following...navigation area (RNA): All waters of the Hood Canal in the State of Washington whenever...

2012-07-01

254

33 CFR 165.1328 - Regulated Navigation Area; U.S. Navy submarines, Hood Canal, WA.  

Code of Federal Regulations, 2013 CFR

...Navigation Area; U.S. Navy submarines, Hood Canal, WA. 165.1328 Section 165.1328...Navigation Area; U.S. Navy submarines, Hood Canal, WA. (a) Location. The following...navigation area (RNA): All waters of the Hood Canal in the State of Washington whenever...

2013-07-01

255

33 CFR 165.1328 - Regulated Navigation Area; U.S. Navy submarines, Hood Canal, WA.  

Code of Federal Regulations, 2011 CFR

...Navigation Area; U.S. Navy submarines, Hood Canal, WA. 165.1328 Section 165.1328...Navigation Area; U.S. Navy submarines, Hood Canal, WA. (a) Location. The following...navigation area (RNA): All waters of the Hood Canal in the State of Washington whenever...

2011-07-01

256

33 CFR 165.1328 - Regulated Navigation Area; U.S. Navy submarines, Hood Canal, WA.  

Code of Federal Regulations, 2014 CFR

...Navigation Area; U.S. Navy submarines, Hood Canal, WA. 165.1328 Section 165.1328...Navigation Area; U.S. Navy submarines, Hood Canal, WA. (a) Location. The following...navigation area (RNA): All waters of the Hood Canal in the State of Washington whenever...

2014-07-01

257

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

258

Submarine landslides: advances and challenges  

Microsoft Academic Search

Due to the recent development of well-integrat ed surveying techniques of the sea-floor, significant improvements were achieved in mapping and describing the morphology of submarine mass movements. Except for the occurrence of turbidity currents, the aquatic environment (marine and fresh water) experiences the same type of mass failure as found on land. Submarine mass movements however, can have run out

Jacques Locat; Homa J. Lee

2002-01-01

259

Santorini Volcano  

USGS Publications Warehouse

Santorini is one of the most spectacular caldera volcanoes in the world. It has been the focus of significant scientific and scholastic interest because of the great Bronze Age explosive eruption that buried the Minoan town of Akrotiri. Santorini is still active. It has been dormant since 1950, but there have been several substantial historic eruptions. Because of this potential risk to life, both for the indigenous population and for the large number of tourists who visit it, Santorini has been designated one of five European Laboratory Volcanoes by the European Commission. Santorini has long fascinated geologists, with some important early work on volcanoes being conducted there. Since 1980, research groups at Cambridge University, and later at the University of Bristol and Blaise Pascal University in Clermont-Ferrand, have collected a large amount of data on the stratigraphy, geochemistry, geochronology and petrology of the volcanics. The volcanic field has been remapped at a scale of 1:10 000. A remarkable picture of cyclic volcanic activity and magmatic evolution has emerged from this work. Much of this work has remained unpublished until now. This Memoir synthesizes for the first time all the data from the Cambridge/Bristol/Clermont groups, and integrates published data from other research groups. It provides the latest interpretation of the tectonic and magmatic evolution of Santorini. It is accompanied by the new 1:10 000 full-colour geological map of the island.

Druitt, T.H.; Edwards, L.; Mellors, R.M.; Pyle, D.M.; Sparks, R.S.J.; Lanphere, M.; Davies, M.; Barreirio, B.

1999-01-01

260

Current submarine atmosphere control technology.  

PubMed

Air purification in submarines was introduced towards the end of World War II and was limited to the use of soda lime for the removal of carbon dioxide and oxygen candles for the regeneration of oxygen. The next major advances came with the advent of nuclear-powered submarines. These included the development of regenerative and, sometimes, energy-intensive processes for comprehensive atmosphere revitalization. With the present development of conventional submarines using air-independent propulsion there is a requirement for air purification similar to that of the nuclear-powered submarines but it is constrained by limited power and space. Some progress has been made in the development of new technology and the adoption of air purification equipment used in the nuclear-powered submarines for this application. PMID:11876194

Mazurek, W

1998-01-01

261

Shrimp Populations on Northwest Rota, an Active Volcano of the Mariana Volcanic Arc  

NASA Astrophysics Data System (ADS)

NW Rota-1 is a submarine volcano that manifested active volcanic and hydrothermal activity during submersible surveys in March 2004 (see Embley et al.). Substratum on the volcano summit (520 m depth) was entirely basalt outcrop or variously-sized ejecta lying near the angle of repose. While no fauna inhabited the rim of the volcanic pit, patches of shrimp were located within 25 m and on the nearby summit. Two species are present. Opaepele cf. loihi shows few morphological differences from either a nearby population on Eifuku Volcano (see Chadwick et al.) at 1700 m depth or from the type locality in Hawaii. A molecular comparison of COI sequences of 13 specimens found little difference from two Hawaiian sequences. Video observations detail frequent feeding activity using spatulate chelipeds to trim microbial filaments as the cephalothorax sways across the substratum. The second species is an undescribed Alvinocaris. Juveniles of this species appear to form clusters distinct from Opaepele where they also graze on filaments. Sparse adults of Alvinocaris range up to 5.5 cm long and display aggressive behaviour moving through patches of smaller shrimp. Densities of Opaepele were highest on sloping rock walls (over 500 per sq.m.) whereas adult Alvinocaris were more abundant on rubble. This division may reflect food preference: microbial filaments versus polychaetes and meiofauna. Characterization of particulates from these substrata was conducted using visual sorting and stable isotope composition. As Alvinocaris matures, the chelipeds enlarge, enabling a greater predatory capacity. Measurements of Opaepele from digital in situ images reveal a population structure suggesting a recent recruitment. Average size is significantly smaller than the Eifuku population and no egg-bearing females were collected. The disjunct range of this species where it occurs on active volcanoes 6000 km apart is puzzling. Further work on intermediate sites and into the reproductive strategy of the species is required.

Tunnicliffe, V.; Juniper, S. K.; Limén, H.; Jones, W. J.; Vrijenhoek, R.; Webber, R.; Eerkes-Medrano, D.

2004-12-01

262

Iceland: Eyjafjallajökull Volcano  

Atmospheric Science Data Center

article title:  Eyjafjallajökull Volcano Ash Plume Particle Properties     ... satellite flew over Iceland's erupting Eyjafjallajökull volcano on April 19, 2010, its Multi-angle Imaging SpectroRadiometer (MISR) ...

2013-04-17

263

Observations on the Origin of Submarine Volcanic Cone Morphologies in Hawaii  

NASA Astrophysics Data System (ADS)

Our recent models for the formation of flat-topped and pointed volcanic cones on the submarine flanks of the Hawaiian islands were based on 30 kHz multibeam bathymetry and backscatter data and the few existing samples [Clague et al., Bull. Volcanol. 62, 214-233, 2000]. During MBARI's Hawaii expedition in April-May 2001, we used the ROV TIBURON to further investigate the origins of volcanic cones. Pointed cones have steep, symmetrical, smooth slopes with no discernible summit platform. We proposed that these were monogenetic cones constructed of a uniform type of fragmental volcanic products in the manner of cinder cones on land; major differences are that submarine pointed cones are taller and do not have summit craters. Observations from dives on three such cones on the NW flank of Ni`ihau showed that the smooth acoustic character of the slopes cannot be attributed either to sediment cover or to the specific nature of volcanic products on the cones' surfaces (e.g., volcaniclastics vs. talus vs. pillow lava), but instead to a uniform distribution of these products. One of the cones is partly dissected and eroded, exposing bedded volcaniclastics in both interior and exterior, but near the summit its surface is mantled by pillow lava. The other two are located 600m apart and are composed of geochemically similar hawaiites, suggesting that they represent two vents from the same eruption. These observations are consistent with our proposal that these pointed cones were constructed by vigorous eruption of fragmental ejecta, and this gives them their steep, pointed shape. The pillow lava is a thin veneer extruded at lower effusion rate during the waning stage of eruptions. New samples from these three pointed cones are vesicular hawaiite similar to Ni'ihau's subaerial postshield alkalic lavas, and confirm that pointed cones form by eruptions of gas-rich alkalic lavas. Flat-topped volcanic cones are found on the tholeiitic submarine rift zones of all mature Hawaiian volcanoes, and are also abundant on the submarine flank of Ni`ihau. They have the form of truncated cones. We modeled them as monogenetic constructions formed by an inflating and overflowing lava pond during protracted, steady eruption of gas-poor, low-viscosity lava. Previous dive observations on flat-topped cones at Mahukona and Kohala showed that the outer slopes are covered by pillow lava flows (and talus), consistent with overflows from a lava pond, but observations on the flat tops were thwarted by heavy sediment cover. The recent TIBURON dives investigated five flat-topped cones on Ni`ihau. As before, elongated pillow lavas were observed on the outer slopes. On the flat tops, the lava flow forms protruding through the sediment were primarily hackly sheet flows, folded sheets, tumuli (which form on inflated sheet flows), and lobate lavas. Submarine hackly sheet flows indicate unusually fast-moving, well-insulated lava. Existence of these flow forms on a low-grade slope is consistent with crust forming on an actively circulating lava pond, and suggests that the crust forms over large areas of the pond at once, rather than gradually accumulating at the edges as the cone grows. The lobate flows may represent lava extruded through cracks in the crust. The flat-topped cones on Ni`ihau are confirmed to be submarine equivalents of the rejuvenated stage Kiekie Volcanics on the island. The new samples have low vesicularity, supporting the model of flat-topped cones as sustained eruptions of gas-poor, low-viscosity lava.

Reynolds, J. R.; Clague, D. A.; Hon, K.; Dixon, J. E.; Cousens, B. L.

2001-12-01

264

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

265

Smithsonian Volcano Data on Google Earth  

NASA Astrophysics Data System (ADS)

Interactive global satellite imagery datasets such as hosted by Google Earth provide a dynamic platform for educational outreach in the Earth Sciences. Users with widely varied backgrounds can easily view geologic features on a global-to-local scale, giving access to educational background on individual geologic features or events such as volcanoes and earthquakes. The Smithsonian Institution's Global Volcanism Program (GVP) volcano data became available as a Google Earth layer on 11 June 2006. Locations for about 1550 volcanoes with known or possible Holocene activity are shown as red triangles with associated volcano names that appear when zooming in to a regional-scale view. Clicking on a triangle opens an informational balloon that displays a photo, geographic data, and a brief paragraph summarizing the volcano's geologic history. The balloon contains links to a larger version of the photo with credits and a caption and to more detailed information on the volcano, including eruption chronologies, from the GVP website. Links to USGS and international volcano observatories or other websites focusing on regional volcanoes are also provided, giving the user ready access to a broad spectrum of volcano data. Updates to the GVP volcano layer will be provided to Google Earth. A downloadable file with the volcanoes organized regionally is also available directly from the GVP website (www.volcano.si.edu) and provides the most current volcano data set. Limitations of the implied accuracy of spacially plotted data at high zoom levels are also apparent using platforms such as Google Earth. Real and apparent mismatches between plotted locations and the summits of some volcanoes seen in Google Earth satellite imagery occur for reasons including data precision (deg/min vs. deg/min/sec) and the GVP convention of plotting the center-point of large volcanic fields, which often do not correspond to specific volcanic vents. A more fundamental problem originates from the fact that regional topographic mapping does not utilize a standardized global datum, so that locations from topographic maps often diverge from those of the World Geodetic System datum used in geo-registered satellite imagery. These limitations notwithstanding, virtual globe platforms such as Google Earth provide an easily accessible pathway to volcano data for a broad spectrum of users ranging from the home/classroom to Earth scientists.

Venzke, E.; Siebert, L.; Luhr, J. F.

2006-12-01

266

4D volcano gravimetry  

USGS Publications Warehouse

Time-dependent gravimetric measurements can detect subsurface processes long before magma flow leads to earthquakes or other eruption precursors. The ability of gravity measurements to detect subsurface mass flow is greatly enhanced if gravity measurements are analyzed and modeled with ground-deformation data. Obtaining the maximum information from microgravity studies requires careful evaluation of the layout of network benchmarks, the gravity environmental signal, and the coupling between gravity changes and crustal deformation. When changes in the system under study are fast (hours to weeks), as in hydrothermal systems and restless volcanoes, continuous gravity observations at selected sites can help to capture many details of the dynamics of the intrusive sources. Despite the instrumental effects, mainly caused by atmospheric temperature, results from monitoring at Mt. Etna volcano show that continuous measurements are a powerful tool for monitoring and studying volcanoes.Several analytical and numerical mathematical models can beused to fit gravity and deformation data. Analytical models offer a closed-form description of the volcanic source. In principle, this allows one to readily infer the relative importance of the source parameters. In active volcanic sites such as Long Valley caldera (California, U.S.A.) and Campi Flegrei (Italy), careful use of analytical models and high-quality data sets has produced good results. However, the simplifications that make analytical models tractable might result in misleading volcanological inter-pretations, particularly when the real crust surrounding the source is far from the homogeneous/ isotropic assumption. Using numerical models allows consideration of more realistic descriptions of the sources and of the crust where they are located (e.g., vertical and lateral mechanical discontinuities, complex source geometries, and topography). Applications at Teide volcano (Tenerife) and Campi Flegrei demonstrate the importance of this more realistic description in gravity calculations. ?? 2008 Society of Exploration Geophysicists. All rights reserved.

Battaglia, Maurizio; Gottsmann, J.; Carbone, D.; Fernandez, J.

2008-01-01

267

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.

David Tenenbaum

1997-01-02

268

Orographic Flow over an Active Volcano  

NASA Astrophysics Data System (ADS)

Orographic flows over and around an isolated volcano are studied through a series of numerical model experiments. The volcano top has a heated surface, so can be thought of as "active" but not erupting. A series of simulations with different atmospheric conditions and using both idealised and realistic configurations of the Weather Research and Forecast (WRF) model have been carried out. The study is based on the Soufriere Hills volcano, located on the island of Montserrat in the Caribbean. This is a dome-building volcano, leading to a sharp increase in the surface skin temperature at the top of the volcano - up to tens of degrees higher than ambient values. The majority of the simulations use an idealised topography, in order for the results to have general applicability to similar-sized volcanoes located in the tropics. The model is initialised with idealised atmospheric soundings, representative of qualitatively different atmospheric conditions from the rainy season in the tropics. The simulations reveal significant changes to the orographic flow response, depending upon the size of the temperature anomaly and the atmospheric conditions. The flow regime and characteristic features such as gravity waves, orographic clouds and orographic rainfall patterns can all be qualitatively changed by the surface heating anomaly. Orographic rainfall over the volcano can be significantly enhanced with increased temperature anomaly. The implications for the eruptive behaviour of the volcano and resulting secondary volcanic hazards will also be discussed.

Poulidis, Alexandros-Panagiotis; Renfrew, Ian; Matthews, Adrian

2014-05-01

269

Geomechanical Characterization of Submarine Volcano-Flank Sediments, Martinique, Lesser  

E-print Network

. Lafuerza et al. Keywords Undrained shear strength · Consolidation properties · Overpressure · Sediment have catastrophic effects on-land and on nearby islands by generating tsunami waves (Harbitz et al occurred on Montserrat in 1997 (Voight et al. 2002). Marine geophysical and on-land studies in Martinique

Manga, Michael

270

Methane seeps and mud volcanoes in the Western Black Sea: First results of RV Meteor cruise M72-4  

NASA Astrophysics Data System (ADS)

Cold seeps are a widespread phenomenon in the Black Sea ranging from seeps in water depths located above the gas hydrate stability zone to mud volcanoes and seeps associated with gas hydrates in deeper water. In May 2007, RV Meteor cruise M72-4 investigated the distribution of cold seeps as well as the pathways of the fluids in the subsurface by a combination of seismic and geo-acoustic methods (sidescan sonar, Chirp subbottom profiling, reflection seismic and refraction experiments). Two areas have been targeted in particular: the Sorokin Trough southeast of the Crimean peninsula and the continental slope of the Dnepr submarine fan further to the West. The Dnepr slope area is characterized by numerous gas emissions situated in water depths of less than 725 metres, while beyond this depth they are almost absent. Raw sidescan images show many individual flares that do not leave a mark on seafloor backscatter intensity, while others coincide with irregular patches of high backscatter intensity. These latter locations are associated with higher gas fluxes, but whether high backscatter is related solely to high gas content is yet unclear. The Sorokin Trough, on the other hand, shows the presence of several mud volcanoes that show a wide range of morphologies ranging from flat mud pies to large cones with or without calderas. Some of the mud volcanoes are aligned, which points to a strong underlying structural control. The source level for all mud volcanoes in the Black Sea is located in the Late Miocene Maikop formation, which is located at a depth of several kilometres in the Sorokin Trough. The dynamics of fluid reservoirs at depth in order to produce mud flow activity with very different rheology at lateral distances of a few kilometres is still under investigation. Several of these mud volcanoes show recent activity through either mud flows or gas flares. The gas flares are surprising as the mud volcanoes lie in water depths of around 2000 metres, i.e. well within the depth of gas hydrate stability. However, this flare activity is intermittent. geomar.de/index.php?id=seepmod

Klaucke, I.; Bialas, J.; Petersen, C. J.; Netzeband, G. L.; Wagner, G.; Fink, M.

2007-12-01

271

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.

272

Nyiragonga Volcano  

NASA Technical Reports Server (NTRS)

This image of the Nyiragonga volcano eruption in the Congo was acquired on January 28, 2002 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters about 50 to 300 feet ), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet.

Image: A river of molten rock poured from the Nyiragongo volcano in the Congo on January 18, 2002, a day after it erupted, killing dozens, swallowing buildings and forcing hundreds of thousands to flee the town of Goma. The flow continued into Lake Kivu. The lave flows are depicted in red on the image indicating they are still hot. Two of them flowed south form the volcano's summit and went through the town of Goma. Another flow can be seen at the top of the image, flowing towards the northwest. One of Africa's most notable volcanoes, Nyiragongo contained an active lava lake in its deep summit crater that drained catastrophically through its outer flanks in 1977. Extremely fluid, fast-moving lava flows draining from the summit lava lake in 1977 killed 50 to 100 people, and several villages were destroyed. The image covers an area of 21 x 24 km and combines a thermal band in red, and two infrared bands in green and blue.

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

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

2001-01-01

273

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

274

Silicic Submarine Eruptions: what can erupted pyroclasts tell us?  

NASA Astrophysics Data System (ADS)

Our understanding of submarine volcanism is in its infancy with respect to subaerial eruption processes. Two fundamental differences between eruptions in seawater compared to those on land are that (1) eruptions occur at higher confining pressures, and (2) in a seawater medium, which has a higher heat capacity, density and viscosity than air. Together with JAMSTEC collaborators we have a sample suite of submarine pumice deposits from modern volcanoes of known eruption depths. This sample suite spans a spectrum of eruption intensities, from 1) powerful explosive caldera-forming (Myojin Knoll caldera); to 2) weakly explosive cone building (pre-caldera Myojin Knoll pumice and Kurose-Nishi pumice); to 3) volatile-driven effusive dome spalling (Sumisu knoll A); to 4) passive dome effusion (Sumisu knoll B and C). This sample suite has exceptional potential, not simply because the samples have been taken from well-constrained, sources but because they have similar high silica contents, are unaltered and their phenocrysts contain melt inclusions. Microtextural quantitative analysis has revealed that (i) clast vesicularities remain high (69-90 vol.%) regardless of confining pressure, mass eruption rate or eruption style , (ii) vesicle number densities scale with inferred eruption rate, and (iii) darcian and inertial permeabilities of submarine effusive and explosive pyroclasts overlap with explosively-erupted subaerial pyroclasts.

Carey, R.; Allen, S.; McPhie, J.; Fiske, R. S.; Tani, K.

2013-12-01

275

Sediment Flux in Hueneme and Mugu Submarine Canyons  

Microsoft Academic Search

Subsurface moorings were deployed at ~190 m water depth for 6 months (9\\/07 - 3\\/08) inside Hueneme and Mugu submarine canyons in southern California. Data collected from the sediment traps, located at 30 and 60 meters above canyon floor, showed marked temporal and spatial variations of sediment flux. Not surprisingly, high sediment flux correlated well with high river discharge, which

J. Xu; P. Swarzenski; M. Noble; A. Li

2008-01-01

276

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.

277

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

278

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

279

Obstacle avoidance sonar for submarines  

Microsoft Academic Search

The Advanced Mine Detection Sonar (AMDS) system was designed to operate in poor environments with high biological and\\/or shallow-water boundary conditions. It provides increased capability for active detection of volume, close-tethered, and bottom mines, as well as submarine and surface target active\\/passive detection for ASW and collision avoidance. It also provides bottom topography mapping capability for precise submarine navigation in

Albert C. Dugas; Kenneth M. Webman

2002-01-01

280

Computer simulation of submarine motion  

E-print Network

COMPUTER SIMULATION OF SUBMARINE MOTION A Thesis by JEFFERY ALAN ZURFLUEH Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE May 1991 Major... Subject: Mechanical Engineering COMPUTER SIMULATION OF SUBMARINE MOTION A Thesis by JEFFERY ALAN ZURFLUEH Approved as to style and content by: Make McDermott, Jr. ( Chair of Committee ) Glen Williams ( Member ) Lo 4verett ( Member ) gu r Walter...

Zurflueh, Jeffery Alan

1991-01-01

281

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.

282

Santorini Volcano  

NASA Astrophysics Data System (ADS)

What is it about Santorini (Thera) that attracts volcanologists? This small archipelago in the Aegean has captivated volcanic pilgrims since Fouque published his geologic study of the volcanic field in 1879 [Fouqué, 1879].It must be the combination of its spectacular setting, rising out of the blue waters of the Aegean, the remarkable exposures that lay open its violent past for everyone to see, or possibly the slower pace of life and remarkable Greek hospitality Perhaps it is the Lower Bronze Age town of Akrotiri, destroyed yet preserved by a large explosive eruption 3600 years ago. There are thousands of volcanoes yet to be studied on our planet, but for 140 years, groups of volcanologists have regularly visited this flooded caldera complex to add yet another bit of information to the foundation laid by Fouqué.

Heiken, Grant

283

Penguin Bank: A Loa-Trend Hawaiian Volcano  

NASA Astrophysics Data System (ADS)

Hawaiian volcanoes along the Hawaiian Ridge from Molokai Island in the northwest to the Big Island in the southeast, define two parallel trends of volcanoes known as the Loa and Kea spatial trends. In general, lavas erupted along these two trends have distinctive geochemical characteristics that have been used to define the spatial distribution of geochemical heterogeneities in the Hawaiian plume (e.g., Abouchami et al., 2005). These geochemical differences are well established for the volcanoes forming the Big Island. The longevity of the Loa- Kea geochemical differences can be assessed by studying East and West Molokai volcanoes and Penguin Bank which form a volcanic ridge perpendicular to the Loa and Kea spatial trends. Previously we showed that East Molokai volcano (~1.5 Ma) is exclusively Kea-like and that West Molokai volcano (~1.8 Ma) includes lavas that are both Loa- and Kea-like (Xu et al., 2005 and 2007).The submarine Penguin Bank (~2.2 Ma), probably an independent volcano constructed west of West Molokai volcano, should be dominantly Loa-like if the systematic Loa and Kea geochemical differences were present at ~2.2 Ma. We have studied 20 samples from Penguin Bank including both submarine and subaerially-erupted lavas recovered by dive and dredging. All lavas are tholeiitic basalt representing shield-stage lavas. Trace element ratios, such as Sr/Nb and Zr/Nb, and isotopic ratios of Sr and Nd clearly are Loa-like. On an ?Nd-?Hf plot, Penguin Bank lavas fall within the field defined by Mauna Loa lavas. Pb isotopic data lie near the Loa-Kea boundary line defined by Abouchami et al. (2005). In conclusion, we find that from NE to SW, i.e., perpendicular to the Loa and Kea spatial trend, there is a shift from Kea-like East Molokai lavas to Loa-like Penguin Bank lavas with the intermediate West Molokai volcano having lavas with both Loa- and Kea-like geochemical features. Therefore, the Loa and Kea geochemical dichotomy exhibited by Big Island volcanoes existed at ~2.2 Ma when the Molokai Island volcanoes formed and has persisted until the present. References: Abouchami et al., 2005 Nature, 434:851-856 Xu et al., 2005 G3, doi: 10.1029/2004GC000830 Xu et al., 2007 G3, doi: 10.1029/2006GC001554

Xu, G.; Blichert-Toft, J.; Clague, D. A.; Cousens, B.; Frey, F. A.; Moore, J. G.

2007-12-01

284

Global Observation of Vertical-CLVD Earthquakes Associated with Active Volcanoes  

NASA Astrophysics Data System (ADS)

Recent work suggests that vertical-CLVD earthquakes associated with active volcanoes can be generated by slip on pre-existing ring fault structures. These earthquakes can occur in connection with ongoing volcanic eruptions. These events can also occur due to the transport of magma from deeper to more shallow magma chambers, and so their detection may be useful for determining the likelihood of future eruptions. In this study, we perform a systematic global search for non-double-couple earthquakes with either vertical P or T axes located within 100 kilometers of a volcano that has erupted since 1900. Our survey utilizes the Global CMT Catalog as well as a catalog of newly detected earthquakes that were located using intermediate-period surface waves (Ekström, 2006). Using updated methods that include both body and surface wave data, deviatoric centroid-moment-tensor solutions were (re)calculated for 135 vertical-CLVD earthquakes recorded in the Global CMT catalog from 1976-2009 and 175 earthquakes recorded in the surface wave catalog from 1991-2008. In total, 33 earthquakes from the Global CMT catalog and 49 earthquakes from the surface wave catalog were found to have robust vertical-CLVD sources, excluding earthquakes previously studied at Bárdarbunga and Nyiragongo volcanoes. Though many of the vertical-CLVD earthquakes are not temporally associated with eruptions at nearby volcanoes, roughly one third occur during periods of observed volcanic unrest. For example, vertical-CLVD events are associated with a paroxysmal explosion at Stromboli in 2003, with a submarine eruption at Vailulu’u in 1995, and with large-scale eruptions at Sierra Negra in 2005 and Tungurahua in 2006. Dozens of vertical-CLVD earthquakes are also associated with the incremental caldera collapse of Miyakejima in 2000. We explore a range of potential physical mechanisms for vertical-CLVD earthquakes by integrating our seismic observations with auxiliary data from the best-studied volcanoes. Full moment tensor solutions are also calculated, and the trade-offs between isotropic and vertical-CLVD components are considered in our models.

Shuler, A. E.; Ekstrom, G.; Nettles, M.

2010-12-01

285

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)

The 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

286

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

287

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

288

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.

289

Leakage of magmatic-hydrothermal volatiles from a crater bottom formed by a submarine eruption in 1989 at Teishi Knoll, Japan  

NASA Astrophysics Data System (ADS)

A submarine eruption occurred off the Izu Peninsula of Japan on 13 July 1989, forming Teishi Knoll, which has a diameter of 450 m and a height of ca. 10 m above the surrounding 90-100 m deep seafloor. Immediately after the eruption, intense gas release was observed from two vents in the crater. The gas bubbling gradually decreased and apparently ceased in 1990. Given that no survey has been undertaken to examine volatile release from the crater of Teishi Knoll, we collected seawater samples at three different sites from just above the crater bottom on 17 July 2012, in order to detect signs of magmatic volatile release. Seawater samples from the crater bottom have dissolved CH4 contents and ?13C values higher than those of shallower (50-100 m deep) seawater samples. Total inorganic carbon contents from the bottom seawater samples are also higher, and ?13C and ?14C values lower than those of shallower seawater samples. These data indicate the addition of minor CH4 and CO2 of hydrothermal or magmatic origin to the bottom seawater from the crater. 3He/4He ratios and total organic carbon data are also consistent with the leakage of magmatic fluids. The most prominent CH4 and CO2 anomalies were observed at the site located closest to one of the bubbling gas sites of the 1989 eruption. As such, volcanic gas emissions still continue today at extremely low levels, 23 years after eruption of this monogenetic volcano. The monitoring of ultra-trace amounts of chemical components in seawater is a prospective method to monitor temporal changes in magmatic activity at such submarine volcanoes.

Notsu, Kenji; Sohrin, Rumi; Wada, Hideki; Tsuboi, Tatsuya; Sumino, Hirochika; Mori, Toshiya; Tsunogai, Urumu; Hernández, Pedro A.; Suzuki, Yusuke; Ikuta, Ryoya; Oorui, Kohei; Koyama, Masato; Masuda, Toshiaki; Fujii, Naoyuki

2014-01-01

290

Submarine hydrothermal fossils confirmed  

NASA Astrophysics Data System (ADS)

Researchers from Princeton University (D. Crerrar et al, Econ. Geol., May 1982) have documented, in considerable detail, evidence for the formation of some of the 800 or more manganiferous chert deposits occurring in the central belt of the Fransiscan formation in northwestern California. They confirm the surprisingly old conclusion o f Tiaferro and Hudson (Cal. Div. Mines Bull., 125, 217-276, 1943) that the Fransiscan chert deposits probably represent the fossil remains of submarine hydrothermal vents.The deposits resemble recently discovered hydrothermal mounds near the Galapagos rift, the Gulf of Aden, and the Mid-Atlantic Ridge. As the Princeton investigators point out, there are important implications of the existence of deep hydrothermal circulation systems at oceanic spreading centers throughout geologic time. They note that the calculated annual flow of hydrothermal fluids in such processes is about 1017 g, which implies that the entire volume of the oceans could circulate completely every 10 million years. With such circulation, the hydrothermal processes along midocean ridges could control the composition of seawater and strongly influence the geochemical flux of elements in the marine environment.

Bell, Peter M.

291

135Y. Yamada et al. (eds.), Submarine Mass Movements and Their Consequences, Advances in Natural and Technological Hazards Research 31,  

E-print Network

The Munson-Nygren-Retriever (MNR) landslide complex is a series of distinct submarine landslides located, USA e-mail: jchaytor@usgs.gov Chapter 12 A Reevaluation of the Munson-Nygren- Retriever Submarine distribution of Fig. 12.1 Shaded-relief bathymetry of the MNR complex area with the Munson-Nygren (red

ten Brink, Uri S.

292

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

293

Ol Doinyo Lengai Volcano  

USGS Multimedia Gallery

Scientists from the Volcano Disaster Assistance Program team and the Geological Survey of Tanzania take a sample of the most recent ashfall from Ol Doinyo Lengai as the volcano looms in the background....

294

Iceland: Eyjafjallajökull Volcano  

Atmospheric Science Data Center

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

295

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

296

Submarine Warfare in the A Bibliography  

E-print Network

Submarine Warfare in the 20th & 21st Centuries: A Bibliography Compiled by Michaele Lee Huygen 3D, 1966. p. 205. This bibliography is a revised edition of the bibliography Submarine Warfare in the 20th & 21st Centuries, 2003, which is in turn a revised and expanded version of Submarine Warfare in the 20

297

Spreading Flanks of Ocean-Island Volcanoes: Similarities and Differences at Mauna Loa and Kilauea, Hawaii  

NASA Astrophysics Data System (ADS)

Submarine-flank deposits of Hawaiian volcanoes are widely recognized to have formed largely by gravitationally driven volcano spreading and associated landsliding. Observations from JAMSTEC submersibles (Japan Marine Science and Technology Center) show that prominent benches at mid-depths on flanks of both Mauna Loa and Kilauea consist of volcaniclastic debris derived by landsliding from nearby shallow submarine and subaerial flanks of the same edifice. Both volcanoes have mid-slope benches that record the same general processes of slope failure on varying scales, followed by modest compression during continued volcano spreading, even though they record development during different stages of edifice growth. Massive slide breccias from the mature subaerial tholeiitic shield of Mauna Loa underlie the frontal scarp of its South Kona bench. Outboard of the South Kona bench are large slide blocks, containing mixed subaerial and submarine Mauna Loa rocks, that appear to constitute a distal facies of the same large landslide event(s). The dive results also suggest that volcaniclastic rocks at the north end of the Kona bench, interpreted by others as distal sediments from older volcanoes that were offscraped, uplifted, and accreted to the island by far-traveled thrusts, alternatively are a largely coherent stratigraphic assemblage deposited in a basin behind the South Kona bench. In contrast, the Hilina bench developed as Kilauea volcano has spread seaward, in part riding piggyback on the still active south flank of Mauna Loa. The Hilina bench is underlain by coarse volcaniclastic sediments derived largely from submarine-erupted pre-shield alkalic and transitional basalts of ancestral Kilauea. The south flank of Kilauea is thus far not associated with any massive slide deposits comparable to the distal blocks of the South Kona slide complex.

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

2003-12-01

298

The Volcano Adventure Guide  

Microsoft Academic Search

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

Rosaly Lopes

2005-01-01

299

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.

Victor Camp

2001-10-01

300

USGS Hawaiian Volcano Observatory  

USGS Multimedia Gallery

The USGS Hawaiian Volcano Observatory is perched on the rim of Kilauea Volcano's summit caldera (next to the Thomas A. Jaggar Museum in Hawai'i Volcanoes National Park), providing a spectacular view of the active vent in Halema‘uma‘u Crater....

301

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

302

Aerosol Lesson: Volcano Types  

NSDL National Science Digital Library

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

303

Focus: alien volcanos  

Microsoft Academic Search

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

Michael Carroll; Rosaly Lopes

2007-01-01

304

Focus: alien volcanos  

NASA Astrophysics Data System (ADS)

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

Carroll, Michael; Lopes, Rosaly

2007-03-01

305

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

NSDL National Science Digital Library

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

Jessica Fries-Gaither

306

American Field Guide: Volcanoes, How Safe Are They?  

NSDL National Science Digital Library

This website integrates video footage and information with lesson plans and activities to teach students about volcanoes. Students learn about some of the most dangerous volcanoes, plot locations, research hazards, and assess risks presented by volcanoes. There are lesson plans for each activity with objectives, videos, pre-activities, materials, and discussion questions. There are worksheets, lists, and assessment pages available to download and links for further information.

307

Infrared science of Hawaiian volcanoes  

USGS Publications Warehouse

Aerial infrared-sensor surveys of Kilauea volcano have depicted the areal extent and the relative intensity of abnormal thermal features in the caldera area of the volcano and along its associated rift zones. Many of these anomalies show correlation with visible steaming and reflect convective transfer of heat to the surface from subterranean sources. Structural details of the volcano, some not evident from surface observation, are also delineated by their thermal abnormalities. Several changes were observed in the patterns of infrared emission during the period of study; two such changes show correlation in location with subsequent eruptions, but the cause-and-effect relationship is uncertain. Thermal anomalies were also observed on the southwest flank of Mauna Loa; images of other volcanoes on the island of Hawaii, and of Haleakala on the island of Maui, revealed no thermal abnormalities. Approximately 25 large springs is- suing into the ocean around the periphery of Hawaii have been detected. Infrared emission varies widely with surface texture and composition, suggesting that similar observations may have value for estimating surface conditions on the moon or planets.

Fischer, William A.; Moxham, R.M.; Polcyn, R.C.; Landis, G.H.

1964-01-01

308

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

309

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

310

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 (Northwest Mediterranean) was used for topographic and initial forcing conditions. Fourteen scenarios were modelled with varying forcing conditions. Rossby number and Burger number 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. 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 were explained within this new dynamic framework.

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

2014-05-01

311

Cascades Volcano Observatory  

USGS Publications Warehouse

Washington's Mount St. Helens volcano reawakens explosively on October 1, 2004, after 18 years of quiescence. Scientists at the U.S. Geological Survey's Cascades Volcano Observatory (CVO) study and observe Mount St. Helens and other volcanoes of the Cascade Range in Washington, Oregon, and northern California that hold potential for future eruptions. CVO is one of five USGS Volcano Hazards Program observatories that monitor U.S. volcanoes for science and public safety. Learn more about Mount St. Helens and CVO at http://vulcan.wr.usgs.gov/.

Venezky, Dina Y.; Driedger, Carolyn; Pallister, John

2008-01-01

312

Alaska Volcano Observatory  

USGS Publications Warehouse

Steam plume from the 2006 eruption of Augustine volcano in Cook Inlet, Alaska. Explosive ash-producing eruptions from Alaska's 40+ historically active volcanoes pose hazards to aviation, including commercial aircraft flying the busy North Pacific routes between North America and Asia. The Alaska Volcano Observatory (AVO) monitors these volcanoes to provide forecasts of eruptive activity. AVO is a joint program of the U.S. 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). AVO is one of five USGS Volcano Hazards Program observatories that monitor U.S. volcanoes for science and public safety. Learn more about Augustine volcano and AVO at http://www.avo.alaska.edu.

Venezky, Dina Y.; Murray, Tom; Read, Cyrus

2008-01-01

313

Volcano seismology  

USGS Publications Warehouse

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

Chouet, B.

2003-01-01

314

What controls earthquakes at Aleutian arc volcanoes?  

NASA Astrophysics Data System (ADS)

Alaska has around 100 Holocene active volcanoes spread over 3000 km of the Aleutian arc, from Mount Wrangell in southcentral Alaska to Buldir Island in the western Aleutian islands. The range in volcanic styles across the arc is as great as the distance that it spans, and so too is the accompanying volcano seismicity. This study examines whether there are systematic influences on volcano seismicity across the Aleutian arc that can account for distinctive patterns in earthquake behaviour, such as the paucity of deep (>20 km depth) volcanic earthquakes in the Cook Inlet region compared to volcanic earthquakes at the westernmost portion of the Alaska Peninsula. We investigate whether physical factors such as volcano size, geographic location relative to the subduction zone, the regional setting - including the type of crust and the distance between the vent and the ocean - and the local angle and rate of subduction affect volcano seismicity. We use continuous seismic data recorded over a 10-year period at 47 volcanoes to characterise patterns in seismicity. Our analyses consider the number and locations of hypocenters, waveform characteristics such as frequency content and magnitude, and the frequency and style of volcanic unrest during the study period.

Buurman, H.; West, M. E.; Cameron, C.

2012-12-01

315

Evolution of the Hawaiian Mantle Plume: Shield and Rejuvenescent Magmatism at Middle Bank, the Youngest Sunken Hawaiian Volcano  

NASA Astrophysics Data System (ADS)

Post-shield volcanism provides unique insight into the structure of mantle plumes and the magmatic processes responsible for the evolution of ocean islands. Middle Bank is the closest seamount to the main Hawaiian archipelago, thus providing a perspective into the processes related to the dying phase of a Hawaiian volcano. We conducted a detailed survey of the volcano in 2007 using multibeam sonar coupled with Jason2 ROV imaging and sampling. According to plate tectonic models, Middle Bank volcano should be about 9.6 Ma, if it formed near the present location of Kilauea. Middle Bank is 100 km in diameter and rises nearly 5000 m from base level. Its morphology is dominated by three major rift zones that emanate to the east, west, and south from the beveled summit platform. The rifts are separated by talus fans, and the volcano is surrounded by dozens of satellite cones. Many of the satellite cones are covered by remarkably unsedimented lavas that were erupted in the submarine environment, which we interpret as a rejuvenated stage of volcanism. Most of the sampled rocks are strongly alkaline and range from basanite to hawaiite and trachyte. Samples from two sites are tholeiitic, which is consistent with them forming during the shield stage of volcanism. If so, then most of the late history of volcanism, from shield building to rejuvenated volcanism is preserved at Middle Bank. The alkaline basalts and basanites have La/Sm and La/Yb ratios that are higher than the tholeiites, and all of the rocks are strongly LREE enriched. Major and trace element compositions of hawaiites and trachytes are consistent with large amounts of crystal fractionation, which especially affected magmas erupted on the outer flanks of the volcano. The tholeiites have Sr/Nb and Zr/Nb that suggest that the Middle Bank shield is akin to the modern-day "Kea" trend geochemically. Thus, Middle Bank has preserved the archetypical tholeiitic-shield to alkaline-rejuvenated evolutionary stages that characterize the subaerial Hawaiian volcanoes.

Geist, D.; Garcia, M.; Ito, G.; Harpp, K.; Weis, D.

2008-12-01

316

A field guide to Newberry Volcano, Oregon  

USGS Publications Warehouse

Newberry Volcano is located in central Oregon at the intersection of the Cascade Range and the High Lava Plains. Its lavas range in age from ca. 0.5 Ma to late Holocene. Erupted products range in composition from basalt through rhyolite and cover ~3000 km2. The most recent caldera-forming eruption occurred ~80,000 years ago. This trip will highlight a revised understanding of the volcano's history based on new detailed geologic work. Stops will also focus on evidence for ice and flooding on the volcano, as well as new studies of Holocene mafic eruptions. Newberry is one of the most accessible U.S. volcanoes, and this trip will visit a range of lava types and compositions including tholeiitic and calc-alkaline basalt flows, cinder cones, and rhyolitic domes and tuffs. Stops will include early distal basalts as well as the youngest intracaldera obsidian flow.

Jenson, Robert A.; Donnelly-Nolan, Julie M.; McKay, Danielle

2009-01-01

317

Obstacle avoidance sonar for submarines  

NASA Astrophysics Data System (ADS)

The Advanced Mine Detection Sonar (AMDS) system was designed to operate in poor environments with high biological and/or shallow-water boundary conditions. It provides increased capability for active detection of volume, close-tethered, and bottom mines, as well as submarine and surface target active/passive detection for ASW and collision avoidance. It also provides bottom topography mapping capability for precise submarine navigation in uncharted littoral waters. It accomplishes this by using advanced processing techniques with extremely narrow beamwidths. The receive array consists of 36 modules arranged in a 15-ft-diameter semicircle at the bottom of the submarine sonar dome to form a chin-mounted array. Each module consists of 40 piezoelectric rubber elements. The modules provide the necessary signal conditioning to the element data prior to signal transmission (uplink) through the hull. The elements are amplified, filtered, converted to digital signals by an A/D converter, and multiplexed prior to uplink to the inboard receiver. Each module also has a downlink over which it receives synchronization and mode/gain control. Uplink and downlink transmission is done using fiberoptic telemetry. AMDS was installed on the USS Asheville. The high-frequency chin array for Virginia class submarines is based on the Asheville design.

Dugas, Albert C.; Webman, Kenneth M.

2002-05-01

318

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

319

Cold-water coral banks and submarine landslides: a review  

NASA Astrophysics Data System (ADS)

This paper aims to review the relation between cold-water coral bank development and submarine landslides. Both are common features on continental margins, but so far it has not been reviewed which effect—if at all—they may have upon each other. Indirect and direct relations between coral banks and landslides are evaluated here, based on four case studies: the Magellan Mound Province in the Porcupine Seabight, where fossil coral banks appear partly on top of a buried slide deposit; the Sula Ridge Reef Complex and the Storegga landslide both off mid-Norway; and the Mauritania coral bank province, associated with the Mauritanian Slide Complex. For each of these locations, positive and negative relationships between both features are discussed, based on available datasets. Locally submarine landslides might directly favour coral bank development by creating substratum where corals can settle on, enhancing turbulence due to abrupt seabed morphological variations and, in some cases, causing fluid seepage. In turn, some of these processes may contribute to increased food availability and lower sedimentation rates. Landslides can also affect coral bank development by direct erosion of the coral banks, and by the instantaneous increase of turbidity, which may smother the corals. On the other hand, coral banks might have a stabilising function and delay or stop the headwall retrogradation of submarine landslides. Although local relationships can be deduced from these case studies, no general and direct relationship exists between submarine landslides and cold-water coral banks.

de Mol, Ben; Huvenne, Veerle; Canals, Miquel

2009-06-01

320

How volcano monitoring in New Zealand can contribute to a global volcano dataset: The GeoNet Project  

NASA Astrophysics Data System (ADS)

Volcanism plays an important role in New Zealand. Much of the landscape of the central North Island owes its shape to volcanism, with the soils supporting forestry and farming economies, geothermal systems providing renewable electricity production and the spectacular landscape supporting tourism and adventure. However volcanism also has it disadvantages: eruptive activity brings physical damage and economic losses and, sometimes, tragically the loss of life. Historically, in New Zealand, volcanoes represent the largest single source of fatalities from natural disasters. To better mitigate the hazard from New Zealand’s volcanoes, a multidisciplinary approach is applied. In 2001 the NZ Earthquake Commission (EQC) commenced funding the GeoNet project, providing the first totally national modern geological hazard monitoring system in New Zealand. The GeoNet project is responsibly for monitoring and assessing all of the active volcanoes (and other geological hazards) in New Zealand. The volcano monitoring programme is integrated into the national seismograph and geodetic networks. The volcano monitoring covers active volcanic cones, resting calderas, volcanic fields, and submarine volcanoes. Monitoring techniques include volcano seismology, geodesy, gas and water chemistry, remote sensing and other geophysical techniques, producing a wide variety of data sets, with both temporal and spatial distribution. These data sets form the basis for detailed research to achieve in depth understanding of these volcanoes and will contribute to the global knowledge of volcanic processes. However to achieve this the data sets need to be accessible by a range of end users, so that they can be used to underpin fundamental research and applied hazard assessments. This presentation will outline the NZ data sets and the problems of presenting and sharing them globally.

Jolly, G. E.; Scott, B.

2009-12-01

321

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

322

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

323

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

324

Geophys. J. Int. (2003) 000, 000000 Seismo-Volcano Source Localization with  

E-print Network

Geophys. J. Int. (2003) 000, 000­000 Seismo-Volcano Source Localization with Triaxial September 5 SUMMARY Seismo-volcano source localization is essential to improve our understanding of eruptive common in volcano studies. In order to determine the source location parameters (back-azimuth and depth

Paris-Sud XI, Université de

325

Automating the Hunt for Volcanoes on Venus , U.M. Fayyad  

E-print Network

Automating the Hunt for Volcanoes on Venus M.C. Burl ¢¡ , U.M. Fayyad ¡ , P. Perona , P. Smyth on classical filtering and statistical pattern recog- nition techniques, for automatically locating volcanoes in the Magellan SAR database of Venus. Training for the specific volcano-detection task is obtained

Smyth, Padhraic

326

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

327

Decreasing magmatic footprints of individual volcanoes in a waning basaltic field  

Microsoft Academic Search

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

G. A. Valentine; F. V. Perry

2006-01-01

328

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

329

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

330

Submarine silicic volcanism of the Healy caldera, southern Kermadec arc (SW Pacific): I - volcanology and eruption mechanisms  

Microsoft Academic Search

The submarine Healy volcano (southern Kermadec arc), with a 2-2.5 km wide caldera, is pervasively mantled with highly vesicular silicic pumice within a water depth of 1,150-1,800 m. Pumices comprise type 1 white-light grey pumice with ⢾ mm vesicles and weak-moderate foliation, type 2 grey pumice with millimetre-scale laminae, flow banded foliation, including stretched vesicles ⣗ mm in length, and

Ian C. Wright; John A. Gamble; Phil A. R. Shane

2003-01-01

331

Noble gases in submarine pillow basalt glasses from Loihi and Kilauea, Hawaii - A solar component in the Earth  

Microsoft Academic Search

Noble gas elemental and isotopic abundances have been analyzed in 22 samples of basaltic glass dredged from the submarine flanks of two currently active Hawaiian volcanoes, Loihi Seamount and Kilauea. Neon isotopic ratios are enriched in Ne-20 and Ne-21 by as much as 16 percent with respect to atmospheric ratios. All the Hawaiian basalt glass samples show relatively high He-3\\/He-4

Masahiko Honda; Ian McDougall; Desmond B. Patterson; Anthony Doulgeris; David A. Clague

1993-01-01

332

Spatial and temporal variations of the state of stress at Fernandina volcano, Galápagos, revealed by InSAR measurements  

NASA Astrophysics Data System (ADS)

Fernandina volcano forms the youngest and westernmost island of the Galápagos 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 sub-aerial 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 sub-aerial 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. 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. Chadwick and Dietriech [1995] attributed the pattern of fissures at Fernandina to stresses induced by the sub-caldera magma body. Changes in pressure in a flat-topped magma reservoir produce circumferential tensional stress at the summit that becomes radial outward on the flanks. They also suggested that a feedback relationship exists between circumferential and radial intrusions where the intrusion in one orientation tends to favor a future intrusion in the other orientation. Using Interferometric Synthetic Aperture Radar (InSAR) measurements of the surface deformation at Fernandina spanning the last three eruptions (1995 - radial, 2005 - circumferential and 2009 - radial) we can infer the geometry of the feeding dikes and calculate stress changes in the volcanic edifice in space and time. Large spatial coverage and frequent SAR acquisitions during the 2009 eruption allow us to study its onset and effects in terms of surface displacement. A SAR image acquired only two hours before the opening of the first eruptive vent shows distinct uplift of a circular area centered below the southwestern caldera rim. This pattern of deformation is generated by the propagation of a sheet-like body gently dipping toward the central magmatic system and parallel to the caldera's major axis (WNW-ESE). SAR interferograms generated using images acquired before and after the eruption show the subsequent opening of radial fissures on the southwestern flank. As for the 1995 event, the dike feeding the 2009 eruptive fissures generates uplift of a semi-circular area on the eastern side of the fractures. Both eruptions are consistent with a model of eastward-shallow-dipping (~30°-35°) dike. The varying orientation of the dike during its propagation and the non-verticality when it intercept the surface imply that the least principal stress direction is not horizontal as usually assumed, but varies in space from the caldera down to the submarine rifts.

Bagnardi, M.; Amelung, F.

2011-12-01

333

The Underwater Cuban Missile Crisis: Soviet Submarines and the Risk of Nuclear War  

NSDL National Science Digital Library

The folks at The National Security Archive are always up to something interesting, like this recently released electronic briefing book. The site provides users with access to numerous documents related to the activities of Soviet submarines during the Cuban Missile Crisis. Visitors can look over the original Soviet Navy map of the Caribbean, which shows the locations of the four Foxtrot diesel submarines that had deployed from the Kola peninsula northwest of Murmansk on October 1962, bound for Mariel port in Cuba. That's just the tip of the proverbial iceberg: the book also contains images of the diary of submariner Anatoly Petrovich Andreyev and video of Captain John Peterson (United States Navy, retired) talking at a conference in 2002 about the hunt for the submarines. It's an absolutely engrossing collection and one that will merit several return visits.

2011-01-01

334

The 2005 eruption of Kliuchevskoi volcano: Chronology and processes derived from ASTER spaceborne and field-based data  

Microsoft Academic Search

Kliuchevskoi volcano, located on the Kamchatka peninsula of eastern Russia, is one of the largest and most active volcanoes in the world. Its location and diversity of eruption styles make satellite-based monitoring and characterization of its eruptive activity essential. In 2005, the Kamchatka Volcano Emergency Response Team (KVERT) first reported that seismic activity of Kliuchevskoi increased above background levels on

Shellie Rose; Michael Ramsey

2009-01-01

335

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

336

Yellowstone Volcano Observatory  

USGS Publications Warehouse

Eruption of Yellowstone's Old Faithful Geyser. Yellowstone hosts the world's largest and most diverse collection of natural thermal features, which are the surface expression of magmatic heat at shallow depths in the crust. The Yellowstone system is monitored by the Yellowstone Volcano Observatory (YVO), a partnership among the U.S. Geological Survey (USGS), Yellowstone National Park, and the University of Utah. YVO is one of five USGS Volcano Hazards Program observatories that monitor U.S. volcanoes for science and public safety. Learn more about Yellowstone and YVO at http://volcanoes.usgs.gov/yvo.

Venezky, Dina Y.; Lowenstern, Jacob

2008-01-01

337

Iceland's Grímsvötn volcano erupts  

NASA Astrophysics Data System (ADS)

About 13 months after Iceland's Eyjafjallajökull volcano began erupting on 14 April 2010, which led to extensive air traffic closures over Europe, Grímsvötn volcano in southeastern took its turn. Iceland's most active volcano, which last erupted in 2004 and lies largely beneath the Vatnajökull ice cap, began its eruption activity on 21 May, with the ash plume initially reaching about 20 kilometers in altitude, according to the Icelandic Meteorological Office. Volcanic ash from Grímsvötn has cancelled hundreds of airplane flights and prompted U.S. president Barack Obama to cut short his visit to Ireland. As Eos went to press, activity at the volcano was beginning to subside.

Showstack, Randy

2011-05-01

338

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

339

32 CFR 707.7 - Submarine identification light.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Submarine identification light. 707.7 Section 707.7 National Defense...WITH RESPECT TO ADDITIONAL STATION AND SIGNAL LIGHTS § 707.7 Submarine identification light. Submarines may display, as a...

2010-07-01

340

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

341

32 CFR 707.7 - Submarine identification light.  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 2013-07-01 false Submarine identification light. 707.7 Section...ADDITIONAL STATION AND SIGNAL LIGHTS § 707.7 Submarine identification light. Submarines may display, as a distinctive...

2013-07-01

342

32 CFR 707.7 - Submarine identification light.  

Code of Federal Regulations, 2014 CFR

... 2014-07-01 2014-07-01 false Submarine identification light. 707.7 Section...ADDITIONAL STATION AND SIGNAL LIGHTS § 707.7 Submarine identification light. Submarines may display, as a distinctive...

2014-07-01

343

32 CFR 707.7 - Submarine identification light.  

Code of Federal Regulations, 2012 CFR

... 2012-07-01 2012-07-01 false Submarine identification light. 707.7 Section...ADDITIONAL STATION AND SIGNAL LIGHTS § 707.7 Submarine identification light. Submarines may display, as a distinctive...

2012-07-01

344

Submarines, spacecraft and exhaled breath.  

PubMed

Foreword The International Association of Breath Research (IABR) meetings are an eclectic gathering of researchers in the medical, environmental and instrumentation fields; our focus is on human health as assessed by the measurement and interpretation of trace chemicals in human exhaled breath. What may have escaped our notice is a complementary field of research that explores the creation and maintenance of artificial atmospheres practised by the submarine air monitoring and air purification (SAMAP) community. SAMAP is comprised of manufacturers, researchers and medical professionals dealing with the engineering and instrumentation to support human life in submarines and spacecraft (including shuttlecraft and manned rockets, high-altitude aircraft, and the International Space Station (ISS)). Here, the immediate concerns are short-term survival and long-term health in fairly confined environments where one cannot simply 'open the window' for fresh air. As such, one of the main concerns is air monitoring and the main sources of contamination are CO(2) and other constituents of human exhaled breath. Since the inaugural meeting in 1994 in Adelaide, Australia, SAMAP meetings have been held every two or three years alternating between the North American and European continents. The meetings are organized by Dr Wally Mazurek (a member of IABR) of the Defense Systems Technology Organization (DSTO) of Australia, and individual meetings are co-hosted by the navies of the countries in which they are held. An overriding focus at SAMAP is life support (oxygen availability and carbon dioxide removal). Certainly, other air constituents are also important; for example, the closed environment of a submarine or the ISS can build up contaminants from consumer products, cooking, refrigeration, accidental fires, propulsion and atmosphere maintenance. However, the most immediate concern is sustaining human metabolism: removing exhaled CO(2) and replacing metabolized O(2). Another important concern is a suite of products from chemical reactions among oxidizing compounds with biological chemicals such as amines, thiols and carbonyls. SAMAP Meeting We (Armin and Joachim) attended the 2011 SAMAP conference in Taranto, Italy (10-14 October), which occurred just a few weeks after the IABR meeting in Parma, Italy (11-15 September 2011). It was held at the Officers' Club of the Taranto Naval Base under the patronage of the Italian navy; the local host was Lucio Ricciardi of the University of Insubria, Varese, Italy. At the 2011 SAMAP meeting, the theme was air-independent propulsion (AIP), meaning the capability of recharging the main batteries of the submarine without the need to surface. Only a few navies (e.g. US, UK, France, Russia, China) have historically had this capability using nuclear-powered submarines that can function underwater for extended periods of time (months). Most navies operate submarines with conventional diesel-electric propulsion, wherein diesel-powered generators charge battery banks which then drive an electric motor connected to the propeller. The batteries are charged while the boat is on the surface or during snorkelling, when the boat is submerged a few meters below the surface and a snorkel tube is extended to the surface. The period between battery charges can vary from several hours to one or two days depending on the power requirements and the nature of the mission. The process is necessary for breathing air revitalization (flushing out accumulated contaminants) and for the operation of the diesel engines. However, during this period the submarine is vulnerable to detection. Since the 1940s there have been various attempts to develop a power generation system that is independent of external air (AIP). To this end hydrogen peroxide was initially used and later liquid oxygen (LOX). Currently, most AIP submarines use fuel cell technology (LOX and hydrogen) to supplement the conventional diesel-electric system in order to extend the underwater endurance to 2-3 weeks. These propulsion engineering changes also reduce per

Pleil, Joachim D; Hansel, Armin

2012-03-01

345

Russian nuclear-powered submarine decommissioning  

SciTech Connect

Russia is facing technical, economic and organizational difficulties in dismantling its oversized and unsafe fleet of nuclear powered submarines. The inability of Russia to deal effectively with the submarine decommissioning crisis increases the risk of environmental disaster and may hamper the implementation of the START I and START II treaties. This paper discusses the nuclear fleet support infrastructure, the problems of submarine decommissioning, and recommends international cooperation in addressing these problems.

Bukharin, O. [Princeton Univ., NJ (United States); Handler, J. [Greenpeace International`s Disarmament Campaign, Washington, DC (United States)

1995-11-01

346

Saga is largest commercial submarine ever  

SciTech Connect

The long-range autonomous submarine, Saga, went nuclear last year with an agreement between the French and two Canadian companies. The agreement to convert the prototype from Swedish Stirling closed-cycle combustion engines to a nuclear power supply will make Saga the first non-defense nuclear submarine. With an external hull displacement of 500 tons, Saga will be the largest commercial submarine ever built.

Not Available

1985-05-01

347

Tsunami Modeling from Submarine Landslides  

NSDL National Science Digital Library

This paper describes a kinematic model that computes tsunamis generated from submarine landslides. The model is based on bathymetric (ocean floor modeling) data and historical tsunami data. The papers' main focus is the application of the model to the 1741 Oshima-Oshima Tsunami in Japan and landslide events around the Hawaiian Islands. This paper was presented at the U.S. National Tsunami Hazard Mitigation Program Review and International Tsunami Symposium in Seattle, Washington on August 10, 2001.

Kenji Satake

348

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

349

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

350

Pb, Hf, Nd, and Sr Isotopic Variations of Hualalai Shield Stage Tholeiites from the Submarine North Kona Region  

NASA Astrophysics Data System (ADS)

We present the isotope and trace element compositions of tholeiitic lavas collected from deep submarine portions of North Kona region, the west flank of Hualalai volcano. The samples were collected from the lower section of the North Kona bench (dives K218 and K219), a submarine section at Hualalai volcano's northwest rift zone (dive S690), and an elongate ridge below the central section of the bench (dive S692) during 2001 and 2002 JAMSTEC Hawaii cruises. Hualalai volcano is presently in the post-shield alkalic stage and most of its subaerial surface is covered by alkalic basalt. All analyzed samples of the pillow lavas are tholeiites that erupted during Hualalai shield stage. It is important to identify source materials involved in the volumetrically dominant stage of Hualalai volcano in order to provide constraints for the size and distribution of compositional heterogeneities of Hawaiian plume. The isotopic compositions of the submarine North Kona tholeiites are similar to the data previously reported for Mauna Loa tholeiites. The data trends define clear mixing relationships that require at least three mantle source components. The mixing is dominated by a Koolau-like enriched component and a Kea-like depleted component. The K219 data trend toward higher epsilon Hf and 87Sr/86Sr relative to the K218, S690, and S692 arrays, requiring another component similar to that observed in post-shield lavas of Hualalai volcano. Pb isotopic compositions for samples from dive K218 and K219 form distinct non-overlapping Pb-Pb arrays suggesting further source heterogeneity. Samples from dive S690 and S692 plot on both of these trends. These findings suggest small-scale compositional heterogeneity in the source regions that can be attributed to anomalous irregular 'blobs' involved in late shield stage magmatism of Mauna Loa reported in previous works.

Yamasaki, S.; Kani, T.; Hanan, B. B.; Tagami, T.

2007-12-01

351

Chaiten Volcano, Chile  

NASA Technical Reports Server (NTRS)

On May 2, 2008 Chile's Chaiten Volcano erupted after 9,000 years of inactivity. Now, 4 weeks later, the eruption continues, with ash-, water-, and sulfur-laden plumes blowing hundreds of kilometers to the east and north over Chile and Argentina. On May 24, ASTER captured a day-night pair of thermal infrared images of the eruption, displayed here in enhanced, false colors. At the time of the daytime acquisition (left image) most of the plume appears dark blue because it is too thick for upwelling ground radiation to penetrate. At the edges it appears orange, indicating the presence of ash and sulfur dioxide. In the nighttime image (right), the plume is orange and red near the source, and becomes more yellow-orange further away from the vent. The possible cause is that ash is settling out of the plume further downwind, revealing the dominant presence of sulfur dioxide.

The images were acquired May 24, 2008, cover an area of 37 x 26.5 km, and are located near 42.7 degrees south latitude, 72.7 degrees west longitude.

The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

2008-01-01

352

Large-scale volcanic cone collapse: The 1888 slope failure of Ritter volcano, and other examples from Papua New Guinea  

NASA Astrophysics Data System (ADS)

A largely submarine avalanche amphitheatre that formed catastrophically in 1888 on Ritter volcano has been identified from a bathymetric survey. Collapse of the volcano in 1888 therefore is considered to have been caused by rapid, large-scale slope failure, rather than by cauldron subsidence, as previously supposed. Escarpments of pre-historic slope failures are common on other Papua New Guinea volcanoes. Directions of avalanching on some volcanoes in the Bismarck volcanic arc appear to be controlled by a regional stress pattern, and those for some volcanoes in the Fly-Highlands province on mainland Papua New Guinea point away from the regional centre of Pliocene uplift. Large amphitheatres such as at Doma Peaks in the Fly-High-lands province probably originated by multiple collapses.

Johnson, R. W.

1987-10-01

353

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

354

Flank tectonics of Martian volcanoes  

SciTech Connect

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

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

1990-08-30

355

Mud volcanoes of the Orinoco Delta, Eastern Venezuela  

USGS Publications Warehouse

Mud volcanoes along the northwest margin of the Orinoco Delta are part of a regional belt of soft sediment deformation and diapirism that formed in response to rapid foredeep sedimentation and subsequent tectonic compression along the Caribbean-South American plate boundary. Field studies of five mud volcanoes show that such structures consist of a central mound covered by active and inactive vents. Inactive vents and mud flows are densely vegetated, whereas active vents are sparsely vegetated. Four out of the five mud volcanoes studied are currently active. Orinoco mud flows consist of mud and clayey silt matrix surrounding lithic clasts of varying composition. Preliminary analysis suggests that the mud volcano sediment is derived from underlying Miocene and Pliocene strata. Hydrocarbon seeps are associated with several of the active mud volcanoes. Orinoco mud volcanoes overlie the crest of a mud-diapir-cored anticline located along the axis of the Eastern Venezuelan Basin. Faulting along the flank of the Pedernales mud volcano suggests that fluidized sediment and hydrocarbons migrate to the surface along faults produced by tensional stresses along the crest of the anticline. Orinoco mud volcanoes highlight the proximity of this major delta to an active plate margin and the importance of tectonic influences on its development. Evaluation of the Orinoco Delta mud volcanoes and those elsewhere indicates that these features are important indicators of compressional tectonism along deformation fronts of plate margins. ?? 2001 Elsevier Science B.V. All rights reserved.

Aslan, A.; Warne, A.G.; White, W.A.; Guevara, E.H.; Smyth, R.C.; Raney, J.A.; Gibeaut, J.C.

2001-01-01

356

Volcano Resources for Educators  

NSDL National Science Digital Library

This site provides an up-to-date list of textual and video educational materials pertaining to volcanoes. The online pamphlets and books, hardcopy books, rental films and videos cover all levels of interest regarding volcanoes. The site furnishes the information or links to information needed to obtain these materials.

357

Iceland: Eyjafjallajökull Volcano  

Atmospheric Science Data Center

... 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

358

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.

359

Volcanoes, Third Edition  

Microsoft Academic Search

It takes confidence to title a smallish book merely ``Volcanoes'' because of the impliction that the myriad facets of volcanism---chemistry, physics, geology, meteorology, hazard mitigation, and more---have been identified and addressed to some nontrivial level of detail. Robert and Barbara Decker have visited these different facets seamlessly in Volcanoes, Third Edition. The seamlessness comes from a broad overarching, interdisciplinary, professional

Christopher J. Nye

1998-01-01

360

Iceland: Eyjafjallajökull Volcano  

Atmospheric Science Data Center

article title:  Eyjafjallajökull Volcano Plume Heights     View ... volcano produced its second major ash plume of 2010 beginning on May 7. Unlike the response to the earlier eruption, which began on April 14, 2010, the reaction to the new plume was better informed. Aircraft were diverted ...

2013-04-17

361

Northern Arizona Volcanoes  

NASA Technical Reports Server (NTRS)

Northern Arizona is best known for the Grand Canyon. Less widely known are the hundreds of geologically young volcanoes, at least one of which buried the homes of local residents. San Francisco Mtn., a truncated stratovolcano at 3887 meters, was once a much taller structure (about 4900 meters) before it exploded some 400,000 years ago a la Mt. St. Helens. The young cinder cone field to its east includes Sunset Crater, that erupted in 1064 and buried Native American homes. This ASTER perspective was created by draping ASTER image data over topographic data from the U.S. Geological Survey National Elevation Data.

With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet.

ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

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

The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

Size: 20.4 by 24.6 kilometers (12.6 by 15.2 miles) Location: 35.3 degrees North latitude, 111.5 degrees West longitude Orientation: North at top Image Data: ASTER Bands 3, 2, and 1 Original Data Resolution: Landsat 30 meters (24.6 feet); ASTER 15 meters (49.2 feet) Dates Acquired: October 21, 2003

2006-01-01

362

Segmentation and Tracking of Anticyclonic Eddies during a Submarine Volcanic Eruption Using Ocean Colour Imagery.  

PubMed

The eruptive phase of a submarine volcano located 2 km away from the southern coast of El Hierro Island started on October 2011. This extraordinary event provoked a dramatic perturbation of the water column. In order to understand and quantify the environmental impacts caused, a regular multidisciplinary monitoring was carried out using remote sensing sensors. In this context, we performed the systematic processing of every MODIS and MERIS and selected high resolution Worldview-2 imagery to provide information on the concentration of a number of biological, physical and chemical parameters. On the other hand, the eruption provided an exceptional source of tracer that allowed the study a variety of oceanographic structures. Specifically, the Canary Islands belong to a very active zone of long-lived eddies. Such structures are usually monitored using sea level anomaly fields. However these products have coarse spatial resolution and they are not suitable to perform submesoscale studies. Thanks to the volcanic tracer, detailed studies were undertaken with ocean colour imagery allowing, using the diffuse attenuation coefficient, to monitor the process of filamentation and axisymmetrization predicted by theoretical studies and numerical modelling. In our work, a novel 2-step segmentation methodology has been developed. The approach incorporates different segmentation algorithms and region growing techniques. In particular, the first step obtains an initial eddy segmentation using thresholding or clustering methods and, next, the fine detail is achieved by the iterative identification of the points to grow and the subsequent application of watershed or thresholding strategies. The methodology has demonstrated an excellent performance and robustness and it has proven to properly capture the eddy and its filaments. PMID:25875193

Marcello, Javier; Eugenio, Francisco; Estrada-Allis, Sheila; Sangrà, Pablo

2015-01-01

363

Volcano's Deadly Warning  

NSDL National Science Digital Library

This site highlights the Nova television program Volcano's Deadly Warning broadcast in November of 2002. In addition to a description of the program, which included information on the eruptions of Galeras and Nevado del Ruiz in Columbia and Popocatepetl in Mexico, the site has four other sections. There is an interactive slide show that includes information about ash, lava flow, lava domes, lava, vents, tephra, calderas, lahars, fissures, dikes, and magmas; a section where one can discover the hidden signatures that volcanologists seek in the noise emanating from a restless volcano; a section where Bernard Chouet of the United States Geological Surveys Volcano Hazard Team describes the mysterious seismic signal he discovered that hints when a volcano might blow; and an interview with Dan Miller of the Volcano Disaster Assistance Program discussing their work with other countries, including the success at Mt. Pinatubo in the Philippines in 1991.

364

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.

365

Historically Active Volcanoes in Alaska - A Quick Reference  

NSDL National Science Digital Library

This United States Geological Survey (USGS) fact sheet summarizes historical data (from 1760 to 1999) on 41 Alaskan volcanoes, using information drawn from the more thorough and comprehensive USGS Open-File Report 98-582. Summaries include the volcano type, location (latitude and longitude), location on USGS quadrangle map, and any information available about the dates of eruptions and type of volcanic activity that occurred. Some volcanoes covered include Trident, Redoubt, Wrangell, Katmai, Cleveland, Kiska and more. A downloadable, printable version is available.

366

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

367

Shiveluch Volcano, Kamchatka Peninsula, Russia  

NASA Technical Reports Server (NTRS)

On the night of June 4, 2001, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) captured this thermal image of the erupting Shiveluch volcano. Located on Russia's Kamchatka Peninsula, Shiveluch rises to an altitude of 2,447 meters (8,028 feet). The active lava dome complex is seen as a bright (hot) area on the summit of the volcano. To the southwest, a second hot area is either a debris avalanche or hot ash deposit. Trailing to the west is a 25-kilometer (15-mile) ash plume, seen as a cold 'cloud' streaming from the summit. At least 60 large eruptions have occurred here during the last 10,000 years; the largest historical eruptions were in 1854 and 1964.

Because Kamchatka is located along the major aircraft routes between North America/Europe and Asia, this area is constantly monitored for potential ash hazards to aircraft. The area is part of the 'Ring of Fire,' a string of volcanoes that encircles the Pacific Ocean.

The lower image is the same as the upper, except it has been color-coded: red is hot, light greens to dark green are progressively colder, and gray/black are the coldest areas.

The image is located at 56.7 degrees north latitude, 161.3 degrees east longitude.

ASTER is one of five Earth-observing instruments launched Dec. 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface.

2001-01-01

368

Topographic characteristics of the submarine Taiwan orogen  

NASA Astrophysics Data System (ADS)

A complete digital elevation and bathymetry model of Taiwan provides the opportunity to characterize the topography of an emerging mountain belt. The orogen appears to form a continuous wedge of constant slope extending from the subaerial peaks to the submarine basin. We compare submarine channel systems from the east coast of Taiwan with their subaerial counterparts and document a number of fundamental similarities between the two environments. The submarine channel systems form a dendritic network with distinct hillslopes and channels. There is minimal sediment input from the subaerial landscape and sea level changes are insignificant, suggesting that the submarine topography is sculpted by offshore processes alone. We implement a range of geomorphic criteria, widely applied to subaerial digital elevation models, and explore the erosional processes responsible for sculpting the submarine and subaerial environments. The headwaters of the submarine channels have steep, straight slopes and a low slope-area scaling exponent, reminiscent of subaerial headwaters that are dominated by bedrock landslides. The main trunk streams offshore have concave-up longitudinal profiles, extensive knickpoints, and a slope-area scaling exponent similar in form to the onshore fluvial domain. We compare the driving mechanisms of the likely offshore erosional processes, primarily debris flows and turbidity currents, with subaerial fluvial incision. The results have important implications for reading the geomorphic signals of the submarine and subaerial landscapes, for understanding the links between the onshore and offshore environments, and, more widely, for focusing the future research of the submarine slope.

Ramsey, L. A.; Hovius, N.; Lague, D.; Liu, C.-S.

2006-06-01

369

Direct measures of Submarine Groundwater Discharge (SGD)  

E-print Network

Page: 1 Direct measures of Submarine Groundwater Discharge (SGD) over a fractured rock aquifer of submarine groundwater discharge (SGD) have been made, but measurements along the South American coast and over fractured rock aquifers are especially rare. The rate and distribution of SGD was measured using

370

Submarine landslide geomorphology, US continental slope  

Microsoft Academic Search

The morphometric analysis of submarine landslides in four distinctly different tectonic environments on the continental slopes of Oregon, central California, Texas, and New Jersey provides useful insight into submarine process, including sediment transport mechanisms and slope stability. Using Geographic Information System (GIS) software, we identify landslides from multibeam bathymetric and GLORIA sidescan surveys based solely on surficial morphology and reflectivity.

B. g. Mcadoo; L. f. Pratson; D. l. Orange

2000-01-01

371

Location, Location, Location!  

ERIC Educational Resources Information Center

Of prime importance in real estate, location is also a key element in the appeal of romances. Popular geographic settings and historical periods sell, unpopular ones do not--not always with a logical explanation, as the author discovered when she conducted a survey on this topic last year. (Why, for example, are the French Revolution and the…

Ramsdell, Kristin

2004-01-01

372

Short and Long Term Volcano Instability Studies at Concepcion Volcano, Nicaragua  

NASA Astrophysics Data System (ADS)

Concepcion is the most active composite volcano in Nicaragua, and is located on Ometepe Island, within Lake Nicaragua. Moderate to small volcanic explosions with a volcanic explosivity index (VEI) of 1-2 have been characteristic of this volcano during the last four decades. Although its current activity is not violent, its volcanic deposits reveal stages of violent activity involving Plinian and sub-Plinian eruptions that deposited vast amounts of volcanic tephra in the Atlantic Ocean. These observations, together with the 31,000 people living on the island, make Concepcion volcano an important target for volcanological research. My research focuses on the investigation of the stability of the volcano edifice of Concepcion, using geophysical data such as gravity, geodetic global positioning system (GPS), sulphur dioxide (SO2) flux, real-time seismic amplitude (RSAM), and satellite remotely-sensed data. The integration of these data sets provides information about the short-term behavior of Concepcion, and some insights into the volcano's long-term behavior. This study has provided, for the first time, information about the shallow dynamics of Concepcion on time scales of days to weeks. I furnish evidence that this volcano is not gravitationally spreading in a continuous fashion as previously thought, that its bulk average density is comparable to that of a pile of gravel, that the volcano edifice is composed of two major distinctive lithologies, that the deformation field around the volcano is recoverable in a matter of days, and that the deformation source is located in the shallow crust. This source is also degassing through the relatively open magmatic conduit. There are, however, several remaining questions. Although the volcano is not spreading continuously there is the possibility that gravitational spreading may be taking place in a stick-slip fashion. This has important implications for slope stability of the volcano, and the associated hazards. The factors influencing the long term slope stability of the volcano are still not fully resolved, but internal volcanic processes and anthropogenic disturbances appear to be the major factors.

Saballos, Jose A.

373

The seismicity of Marapi volcano, West Sumatra.  

NASA Astrophysics Data System (ADS)

Marapi is one of the active volcanoes in West Sumatra. It is a stratovolcano with an edifice that is elongated in the ENE-WSW direction. Its elevation is about 2,900 m a.s.l. The summit area is characterized by a caldera that contains some active craters aligned along the ENE-WSW direction. The Marapi volcano is an attractive region for tourists and hosts many small communities its surrounding areas. The recent history of Mt. Marapi is characterized by explosive activity at the summit craters. No lava flows have passed the rim of the summit caldera in recent times. The last eruption occurred on August 5, 2004, and consisted of moderate explosive activity from the central crater. In 1975 an eruption with magmatic and phreatic explosive phases and mudflows and lahars occurred that caused fatalities in the surrounding areas. Since 1980 other eruptions have occurred at Marapi volcano. Even if the explosive intensities of those eruptions have been small to moderate, in some cases, there were fatalities. A cooperation project started between Italy and Indonesia (COVIN) for the monitoring of volcanoes in West Sumatra. In the context of this project a monitoring centre has been set up at the Bukittinggi Observatory and a seismological monitoring system for Marapi volcano has been realized. This system is based on a broadband seismic network including 4 three-component stations. The data acquired by the broadband network of Marapi volcano are continuous recordings of the seismic signals starting from 19/10/2006. Volcano-Tectonic and Long Period events of Marapi volcano together with regional and teleseismic earthquakes are recorded. Several events of high magnitude located at short distances from the network were also recorded such as on March 6, 2007, when two events of Magnitudes Mw 6.4 and 6.3 were recorded with the epicentres near the Marapi volcano. During the following days, there was a sequence of hundreds of aftershocks. The preliminary analysis of the seismicity of the Marapi Volcano indicates that the broadband network installed under the joint Italy-Indonesia project provides great help for its study and for the monitoring of this active volcanic and seismogenic area.

D'Auria, L.

2009-04-01

374

Monitoring Anak Krakatau Volcano in Indonesia  

NASA Astrophysics Data System (ADS)

Krakatau volcano, in Indonesia, showed its destructive vigor when it exploded in 1883 [Self and Rampino, 1981]. The eruption and subsequent tsunami caused more than 35,000 casualties along the coasts of the Sunda Strait. In 1928, the `child' of Krakatau, Anak Krakatau, emerged from the sea at the same location as its predecessor and has since grown to a height of 315 meters. The volcano exhibits frequent activity-on average one large eruption every four years-yet again posing risk for the coastal population of Java and Sumatra and for the economically important shipping routes through the Sunda Strait.

Hoffmann-Rothe, Arne; Ibs-von Seht, Malte; Knie?, Rudolf; Faber, Eckhard; Klinge, Klaus; Reichert, Christian; Atje Purbawinata, Mas; Patria, Cahya

2006-12-01

375

Primary Initiation of Submarine Canyons  

E-print Network

The discovery of close-to-star gas-giant exo-planets lends support to the idea of Earth's origin as a Jupiter-like gas-giant and to the consequences of its compression, including whole-Earth decompression dynamics that gives rise, without requiring mantle convection, to the myriad measurements and observations whose descriptions are attributed to plate tectonics. I propose here another, unanticipated consequence of whole-Earth decompression dynamics: namely, a specific, dominant, non-erosion, underlying initiation-mechanism precursor for submarine canyons that follows as a direct consequence of Earth's early origin as a Jupiter-like gas-giant.

Herndon, J Marvin

2011-01-01

376

Primary Initiation of Submarine Canyons  

E-print Network

The discovery of close-to-star gas-giant exo-planets lends support to the idea of Earth's origin as a Jupiter-like gas-giant and to the consequences of its compression, including whole-Earth decompression dynamics that gives rise, without requiring mantle convection, to the myriad measurements and observations whose descriptions are attributed to plate tectonics. I propose here another, unanticipated consequence of whole-Earth decompression dynamics: namely, a specific, dominant, non-erosion, underlying initiation-mechanism precursor for submarine canyons that follows as a direct consequence of Earth's early origin as a Jupiter-like gas-giant.

J. Marvin Herndon

2011-02-02

377

Currents in monterey submarine canyon  

USGS Publications Warehouse

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 in the shallow reaches (100-m amplitude isotherm oscillations and associated high-speed rectilinear currents. The 15-day spring-neap cycle and a ???3-day??? band are the two prominent frequencies in subtidal flow field. Neither of them seems directly correlated with the spring-neap cycle of the sea level.

Xu, J.P.; Noble, M.A.

2009-01-01

378

New Insights on Submarine Volcanism in the Western Galapagos Archipelago from High Resolution Sonar and Magnetic Surveys  

NASA Astrophysics Data System (ADS)

We combine high-resolution MR-1 sidescan sonar and EM-300 bathymetric data collected on four cruises (AHA-Nemo2 in 2000 (R/V Melville), DRIFT4 in 2001 (R/V Revelle), TN188 and TN189 in January 2006 (R/V Thompson) to study volcanic platform-building processes on the submarine flanks of Fernandina, Isabela, Roca Redonda and Santiago volcanoes, in the western Galapagos. Three primary volcanic provinces were identified including: rift zones (16, ranging from 5 to 20 km in length), small submarine volcanic cones (<3 km in diameter and several 100 m high) and deep (>3000 m), long (>10 km), large-area submarine lava flows. Lengths of the Galapagos rift zones are comparable to western Canary Island rift zones, but significantly shorter than Hawaiian submarine rift zones, possibly reflecting lower magma supply. A surface-towed magnetic survey was conducted over the NW Fernandina rift on TN189 and Fourier inversions were performed to correct for topographic effects. Calculated magnetization was highest (up to +32 A/m) over the shallow southwest flank of the rift, coinciding with cone fields and suggesting most recent volcanism has focused at this portion of the rift. Small submarine volcanic cones with various morphologies (e.g., pointed, cratered and occasionally breached) are common in the submarine western Galapagos both on rift zones and on the island flanks where no rifts are present, such as the northern flank of Santiago Island. Preliminary study of these cones suggests that their morphologies and depth of occurrence may reflect a combination of petrogenetic and eruption processes. Deep, long large-area lava flow fields in regions of low bathymetric relief have been previously identified as a common seafloor feature in the western Galapagos by Geist et al. [in press], and new EM300 data show that a number of the deep lava flows originate from small cones along the mid-lower portion of the NW submarine rift of Fernandina. Our high-resolution sonar data suggest that submarine volcanism in the western Galapagos occurs both on and off rift zones. Volcanic cones are prevalent on the Galapagos volcanic platform and long lava flows dominate in the deep regions west and north of the platform, possibly representing the foundation upon which the next Galapagos volcanoes will be constructed.

Glass, J. B.; Fornari, D. J.; Tivey, M. A.; Hall, H. F.; Cougan, A. A.; Berkenbosch, H. A.; Holmes, M. L.; White, S. M.; de La Torre, G.

2006-12-01

379

The volcanoes of Auckland city  

Microsoft Academic Search

This article considers that portion of the Auckland volcanic field included in the isthmus west of Tamaki Inlet. The volcanoes (late Pleistocene-Recent) are described in four groups: the dominantly tuff-producing volcanoes of the c.entral city area; the mainly effusive volcanoes of Wraitemata lava field; the volcanoes of Manukau lava field and the associated Epsom tuff deposit: and the volcanoes of

E. J. Searle

1962-01-01

380

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

381

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.

382

Geology of Medicine Lake Volcano, Northern California Cascade Range  

USGS Publications Warehouse

Medicine Lake volcano (MLV) is located in an E-W extensional environment on the Modoc Plateau just east of the main arc of the Cascades. It consists mainly of mafic lavas, although drillhole data indicate that a larger volume of rhyolite is present than is indicated by surface mapping. The most recent eruption was rhyolitic and occurred about 900 years ago. At least seventeen eruptions have occurred since 12,000 years ago, or between 1 and 2 eruptions per century on average, although activity appears to be strongly episodic. The calculated eruptive rate is about 0.6 km3 per thousand years during the entire history of the volcano. Drillhole data indicate that the plateau surface underlying the volcano has been downwarped by 0.5 km under the center of MLV. The volcano may be even larger than the estimated 600 km3, already the largest volcano by volume in the Cascades.

Donnelly-Nolan, Julie

1990-01-01

383

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

384

32. VIEW OF PHOTO CAPTIONED 'SUBMARINE BASE, NEW LONDON, CONN. ...  

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

32. VIEW OF PHOTO CAPTIONED 'SUBMARINE BASE, NEW LONDON, CONN. OCTOBER 3, 1932. COMPLETION OF ERECTION OF STEELWORK FOR ELEVATOR. 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

385

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

386

Volcano-Monitoring Instrumentation in the United States, 2008  

USGS Publications Warehouse

The United States is one of the most volcanically active countries in the world. According to the global volcanism database of the Smithsonian Institution, the United States (including its Commonwealth of the Northern Mariana Islands) is home to about 170 volcanoes that are in an eruptive phase, have erupted in historical time, or have not erupted recently but are young enough (eruptions within the past 10,000 years) to be capable of reawakening. From 1980 through 2008, 30 of these volcanoes erupted, several repeatedly. Volcano monitoring in the United States is carried out by the U.S. Geological Survey (USGS) Volcano Hazards Program, which operates a system of five volcano observatories-Alaska Volcano Observatory (AVO), Cascades Volcano Observatory (CVO), Hawaiian Volcano Observatory (HVO), Long Valley Observatory (LVO), and Yellowstone Volcano Observatory (YVO). The observatories issue public alerts about conditions and hazards at U.S. volcanoes in support of the USGS mandate under P.L. 93-288 (Stafford Act) to provide timely warnings of potential volcanic disasters to the affected populace and civil authorities. To make efficient use of the Nation's scientific resources, the volcano observatories operate in partnership with universities and other governmental agencies through various formal agreements. The Consortium of U.S. Volcano Observatories (CUSVO) was established in 2001 to promote scientific cooperation among the Federal, academic, and State agencies involved in observatory operations. Other groups also contribute to volcano monitoring by sponsoring long-term installation of geophysical instruments at some volcanoes for specific research projects. This report describes a database of information about permanently installed ground-based instruments used by the U.S. volcano observatories to monitor volcanic activity (unrest and eruptions). The purposes of this Volcano-Monitoring Instrumentation Database (VMID) are to (1) document the Nation's existing, ground-based, volcano-monitoring capabilities, (2) answer queries within a geospatial framework about the nature of the instrumentation, and (3) provide a benchmark for planning future monitoring improvements. The VMID is not an archive of the data collected by monitoring instruments, nor is it intended to keep track of whether a station is temporarily unavailable due to telemetry or equipment problems. Instead, it is a compilation of basic information about each instrument such as location, type, and sponsoring agency. Typically, instruments installed expressly for volcano monitoring are emplaced within about 20 kilometers (km) of a volcanic center; however, some more distant instruments (as far away as 100 km) can be used under certain circumstances and therefore are included in the database. Not included is information about satellite-based and airborne sensors and temporarily deployed instrument arrays, which also are used for volcano monitoring but do not lend themselves to inclusion in a geospatially organized compilation of sensor networks. This Open-File Report is provided in two parts: (1) an Excel spreadsheet (http://pubs.usgs.gov/of/2009/1165/) containing the version of the Volcano-Monitoring Instrumentation Database current through 31 December 2008 and (2) this text (in Adobe PDF format), which serves as metadata for the VMID. The disclaimer for the VMID is in appendix 1 of the text. Updated versions of the VMID will be posted on the Web sites of the Consortium of U.S. Volcano Observatories (http://www.cusvo.org/) and the USGS Volcano Hazards Program http://volcanoes.usgs.gov/activity/data/index.php.

Guffanti, Marianne; Diefenbach, Angela K.; Ewert, John W.; Ramsey, David W.; Cervelli, Peter F.; Schilling, Steven P.

2010-01-01

387

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

388

Gravity measurement from moving platform by Kalman Filter and position and velocity corrections for earth layer monitoring to earthquake and volcano activity survey  

Microsoft Academic Search

Gravity measurement responds to changes in subsurface density and characteristics and is a non-invasive and cost effective way to identify and characterize subsurface. Gravity measurement is an effective tool for earth layer monitoring to earthquake and volcano activity survey. It is particularly important for gravity observation from moving platforms, especially for remote and offshore areas by aircraft, boat, ship, submarine,

Amin Almasi

2008-01-01

389

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

390

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

391

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

NASA Astrophysics Data System (ADS)

Submarine-flank deposits of Hawaiian volcanoes are widely recognized to have formed largely by gravitationally driven volcano spreading and associated landsliding. Observations from submersibles show that prominent benches at middepths on flanks of Mauna Loa and K?lauea consist of volcaniclastic debris derived by landsliding from nearby shallow submarine and subaerial flanks of the same edifice. Massive slide breccias from the mature subaerial tholeiitic shield of Mauna Loa underlie the frontal scarp of its South Kona bench. In contrast, coarse volcaniclastic sediments derived largely from submarine-erupted preshield alkalic and transitional basalts of ancestral K?lauea underlie its Hilina bench. Both midslope benches record the same general processes of slope failure, followed by modest compression during continued volcano spreading, even though they record development during different stages of edifice growth. The dive results suggest that volcaniclastic rocks at the north end of the Kona bench, interpreted by others as distal sediments from older volcanoes that were offscraped, uplifted, and accreted to the island by far-traveled thrusts, alternatively are a largely coherent stratigraphic assemblage deposited in a basin behind the South Kona bench.

Lipman, Peter W.; Eakins, Barry W.; Yokose, Hisayoshi

2003-10-01

392

Volcanoes in the Infrared  

NSDL National Science Digital Library

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

2008-11-04

393

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

394

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.

395

A newly recognized 7.5 ka dome-forming eruption of Towada volcano, Northeast Japan Arc  

Microsoft Academic Search

The Towada volcano is an active caldera volcano located in the northern part of the Northeast Japan Arc. The Towada volcano has erupted repeatedly with a magnitude of VEI=4-5 at intervals of several hundreds to thousands years during the last 10,000 years. Therefore, long-term prediction of the eruptive activity of the Towada volcano is needed to avoid volcanic hazards. The

T. Kudo

2010-01-01

396

Comparison of the Submarine 1888 Ritter and the Subaerial 1980 Mount St Helens Debris Avalanche Deposits  

NASA Astrophysics Data System (ADS)

The lateral collapse of Ritter Island volcano, Papua New Guinea, on March 13th 1888 was nearly twice the volume of the lateral collapse of Mount St Helens on May 18th 1980 (4 to 5 km3 compared to 2.8 km3) and the resulting landslide traveled about twice the distance (~75 km for Ritter and ~30 km for MSH). Both landslides descended valleys producing topographically - controlled deposit distributions. Sonar mapping and deep tow camera imaging indicate that the Ritter Island deposit is exceptionally well exposed for a submarine debris avalanche deposit, most likely due to its very young age. Comparing the Ritter and MSH deposits in terms of their geometry, areas of associated substrate erosion, and the development of different morphological facies, provides insights into the kinematic and mechanical similarities and differences between subaerial and submarine debris avalanches resulting from volcano lateral collapses. Although both deposits have block - rich and matrix - rich facies, extensive substrate erosion in the distal part of the Ritter Island landslide resulted in the incorporation of water - rich sediment and transformation of the debris avalanche into a debris flow rich in sediment intraclasts.

Day, S.; Silver, E.; Ward, S.; Gary, H.; Amelia, L.; Llanes-Estrada, P.

2005-12-01

397

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

398

Exterior view of submarine with survey crew posed in front. ...  

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

Exterior view of submarine with survey crew posed in front. From left to right: Todd Croteau - U.S. National Park Service, Joshua Price - U.S. Navy, Bert Ho - National Oceanic and Atmospheric Administration, Michael McCarthy - Western Australia Maritime Museum, Larry Murphy - U.S. National Park Service, Don Johnson- University of Nebraska Engineering School, James Delgado- Institute for Nautical Archeology, Jacinto Ahmendra - Government of Panama. - Sub Marine Explorer, Located along the beach of Isla San Telmo, Pearl Islands, Isla San Telmo, Former Panama Canal Zone, CZ

399

Submarine permafrost in the nearshore zone of the southwestern Kara Sea  

Microsoft Academic Search

The results of seismic studies in the shallow waters of the southwestern Kara Sea show the presence of a seismic unit that can be interpreted as relict submarine permafrost. The permafrost table has a strongly dissected upper surface and is located at a water depth of 5–10 m. A 3D modeling of the permafrost table suggests the presence of relict buried

P. Rekant; G. Cherkashev; B. Vanstein; P. Krinitsky

2005-01-01

400

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

E-print Network

that most of the sound comes from the surface requires some justi cation. There are several main sources, similar to the Beaufort wind force scale. A sea state of 0 indicates a perfectly calm ocean, and 9 indicates a hurricane. Page 2 of 30 #12;#525 Submarine Location Section 2.1 Figure 1: Picture of a boat

Mitchener, W. Garrett

401

Evidence of a turbidity current in Monterey Submarine Canyon associated with the 1989 Loma Prieta earthquake  

Microsoft Academic Search

Evidence of a turbidity current sweeping through the Monterey Submarine Canyon following the October 1989 Loma Prieta earthquake was documented by the movement of bottom-deployed acoustic transponders used to navigate free-falling oceanographic instrumentation. Measuring sites located along the Canyon at distances of 55, 130 and 190 km from the Canyon head off Moss Landing, CA, all showed evidence of tectonically

Newell Garfield; Thomas A. Rago; Kurt J. Schnebele; Curtis A. Collins

1994-01-01

402

Direct measurements of submarine groundwater discharge (SGD) over a fractured rock aquifer in Flamengo Bay Brazil  

Microsoft Academic Search

Measurements of submarine groundwater discharge (SGD) along the South American coast and over fractured rock aquifers are rare. The rate and distribution of SGD was measured using three types of vented benthic chambers on the floor of Flamengo Bay located at the southeast coast of Brazil. Discharge rates were found up to almost 400cmday?1, although typically less than 100cmd?1. Large

Henry Bokuniewicz; Makoto Taniguchi; Tomotoshi Ishitoibi; Matthew Charette; Matthew Allen; Evgeny A. Kontar

2008-01-01

403

Measurement of submarine groundwater discharge in Kahana Bay, O'ahu, Hawai'i  

Microsoft Academic Search

Submarine groundwater discharge (SGD) is neither well understood nor commonly investigated in Hawai'i, but it is recognized as a potential pollution source to coastal environments. Between 1998 and 2000, this study located and quantified both total SGD and the terrestrial SGD fraction (ftgw) in Kahana Bay, O'ahu. CTD casts were used to profile the water structure and identify potential areas

G. H. Garrison; C. R. Glenn; G. M. McMurtry

2003-01-01

404

Hydraulic and Morphodynamic Characteristics of Submarine Channel Confluences  

NASA Astrophysics Data System (ADS)

Submarine channel systems are receiving increased attention recently for their potential in transporting and depositing hydrocarbons via turbidity currents into the deep ocean. In order to better predict the locations of hydrocarbon reserves, a more complete understanding of the hydraulic behavior of flows within the channels is necessary. Past field observations have shown that submarine channels have straight and meandering reaches, along with junctions in channel systems; flows in the submarine environment (i.e. density currents) may propagate as a single pulse or as a sustained flow over a prolonged period. This work aims to further the understanding of submarine channel systems by focusing on the hydraulic behavior of submarine channel confluences due to both sudden release (i.e. pulse events) and sustained flows. The associated morphodynamic consequences at and near the confluence are also assessed as they relate to the observed hydraulic conditions. Observational goals include comparisons to heavily studied characteristics of subaerial river channel confluences. These include flow separation zones, helical flow cells, existence of vertical shear layers, avalanche faces upstream of the junction, and deep central scours in the junction. For this investigation, a physical model was built to simulate a 45 degree submarine channel junction with an erodible bed in which two fully conservative density currents are released in each upstream reach and allowed to collide before creating a single combined current in the downstream reach. The pulse events focused on the head of the density currents and were simulated using a lock-exchange mechanism in which a fixed volume of salt water was locked in each upstream reach of the flume before being suddenly released into the ambient water downstream. HD images were used to obtain 1D velocity both up- and down-stream of the junction, and bathymetry measurements were obtained using an ultrasonic probe after each experiment. The sustained (i.e. steady) events focus on the body of the current and were simulated by continuously releasing salt water into the flume initially filled with ambient water. In this case, 2D velocity measurements were obtained around the junction at five elevations, and bed evolution is tracked qualitatively after each test. It has been observed that: 1) a clear shear layer forms between contributing flows; 2) there is evidence of flow separation near the bed downstream of the junction; 3) the current accelerates as it reforms after the collision in the junction; 4) the location and orientation of the central scour differs from river junctions in the sustained case; 5) the sudden release case shows very little scour in the junction zone. This data is used to develop and validate a numerical simulation of both types of density current releases in which further variations on initial conditions can be assessed for their impact on the velocity field and sediment transport in submarine channel junctions.

Ismail, H.; Viparelli, E.; Ezz, H.; Imran, J.

2013-12-01

405

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

406

Using Submarine Landslides to Predict Slope Stability  

NSDL National Science Digital Library

Students use detailed bathymetric maps to find submarine landslides and compare the slope of these slides to the slope of hills near school and home. By comparing the slopes they can consider slope failure, especially during earthquakes.

Shawn Doan

407

Volcano-earthquake interaction at Mauna Loa volcano, Hawaii  

NASA Astrophysics Data System (ADS)

The activity at Mauna Loa volcano, Hawaii, is characterized by eruptive fissures that propagate into the Southwest Rift Zone (SWRZ) or into the Northeast Rift Zone (NERZ) and by large earthquakes at the basal decollement fault. In this paper we examine the historic eruption and earthquake catalogues, and we test the hypothesis that the events are interconnected in time and space. Earthquakes in the Kaoiki area occur in sequence with eruptions from the NERZ, and earthquakes in the Kona and Hilea areas occur in sequence with eruptions from the SWRZ. Using three-dimensional numerical models, we demonstrate that elastic stress transfer can explain the observed volcano-earthquake interaction. We examine stress changes due to typical intrusions and earthquakes. We find that intrusions change the Coulomb failure stress along the decollement fault so that NERZ intrusions encourage Kaoiki earthquakes and SWRZ intrusions encourage Kona and Hilea earthquakes. On the other hand, earthquakes decompress the magma chamber and unclamp part of the Mauna Loa rift zone, i.e., Kaoiki earthquakes encourage NERZ intrusions, whereas Kona and Hilea earthquakes encourage SWRZ intrusions. We discuss how changes of the static stress field affect the occurrence of earthquakes as well as the occurrence, location, and volume of dikes and of associated eruptions and also the lava composition and fumarolic activity.

Walter, Thomas R.; Amelung, Falk

2006-05-01

408

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

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

409

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 CO? 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

410

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

PubMed Central

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

411

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

412

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.

Jessica Fries-Gaither

413

Characterization of viscoelastic properties of submarine sediments  

E-print Network

CHARACTERIZATION OF VISCOELASTIC PROPERTIES OF SUBMARINE SEDIMENTS A Thesis by Jim Bob King Submitted to the Graduate College of Texas AAM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE December... 1975 Major Subject: Civil Engineering CHARACTERIZATION OF VISCOELASTIC PROPERTIES OF SUBMARINE SEDIMENTS A Thesis by Jim Bob King Approved as to sty1e and content by: Chair an of Commi tee Head of Department Member Member December 1975...

King, Jim Bob

1975-01-01

414

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

415

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.

416

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

417

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

418

Submarine landslides: processes, triggers and hazard prediction.  

PubMed

Huge landslides, mobilizing hundreds to thousands of km(3) of sediment and rock are ubiquitous in submarine settings ranging from the steepest volcanic island slopes to the gentlest muddy slopes of submarine deltas. Here, we summarize current knowledge of such landslides and the problems of assessing their hazard potential. The major hazards related to submarine landslides include destruction of seabed infrastructure, collapse of coastal areas into the sea and landslide-generated tsunamis. Most submarine slopes are inherently stable. Elevated pore pressures (leading to decreased frictional resistance to sliding) and specific weak layers within stratified sequences appear to be the key factors influencing landslide occurrence. Elevated pore pressures can result from normal depositional processes or from transient processes such as earthquake shaking; historical evidence suggests that the majority of large submarine landslides are triggered by earthquakes. Because of their tsunamigenic potential, ocean-island flank collapses and rockslides in fjords have been identified as the most dangerous of all landslide related hazards. Published models of ocean-island landslides mainly examine 'worst-case scenarios' that have a low probability of occurrence. Areas prone to submarine landsliding are relatively easy to identify, but we are still some way from being able to forecast individual events with precision. Monitoring of critical areas where landslides might be imminent and modelling landslide consequences so that appropriate mitigation strategies can be developed would appear to be areas where advances on current practice are possible. PMID:16844646

Masson, D G; Harbitz, C B; Wynn, R B; Pedersen, G; Løvholt, F

2006-08-15

419

Volcano seismicity in Alaska  

NASA Astrophysics Data System (ADS)

I examine the many facets of volcano seismicity in Alaska: from the short-lived eruption seismicity that is limited to only the few weeks during which a volcano is active, to the seismicity that occurs in the months following an eruption, and finally to the long-term volcano seismicity that occurs in the years in which volcanoes are dormant. I use the rich seismic dataset that was recorded during the 2009 eruption of Redoubt Volcano to examine eruptive volcano seismicity. I show that the progression of magma through the conduit system at Redoubt could be readily tracked by the seismicity. Many of my interpretations benefited greatly from the numerous other datasets collected during the eruption. Rarely was there volcanic activity that did not manifest itself in some way seismically, however, resulting in a remarkably complete chronology within the seismic record of the 2009 eruption. I also use the Redoubt seismic dataset to study post-eruptive seismicity. During the year following the eruption there were a number of unexplained bursts of shallow seismicity that did not culminate in eruptive activity despite closely mirroring seismic signals that had preceded explosions less than a year prior. I show that these episodes of shallow seismicity were in fact related to volcanic processes much deeper in the volcanic edifice by demonstrating that earthquakes that were related to magmatic activity during the eruption were also present during the renewed shallow unrest. These results show that magmatic processes can continue for many months after eruptions end, suggesting that volcanoes can stay active for much longer than previously thought. In the final chapter I characterize volcanic earthquakes on a much broader scale by analyzing a decade of continuous seismic data across 46 volcanoes in the Aleutian arc to search for regional-scale trends in volcano seismicity. I find that volcanic earthquakes below 20 km depth are much more common in the central region of the arc than they are in the eastern and western regions. I tie these observations to trends in magma geochemistry and regional t