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Sample records for cone lassen volcanic

  1. Multiple dendrochronological responses to the eruption of Cinder Cone, Lassen Volcanic National Park, California

    Science.gov (United States)

    Sheppard, P.R.; Ort, M.H.; Anderson, K.C.; Clynne, M.A.; May, E.M.

    2009-01-01

    Two dendrochronological properties – ring width and ring chemistry – were investigated in trees near Cinder Cone in Lassen Volcanic National Park, northeastern California, for the purpose of re-evaluating the date of its eruption. Cinder Cone is thought to have erupted in AD 1666 based on ring-width evidence, but interpreting ring-width changes alone is not straightforward because many forest disturbances can cause changes in ring width. Old Jeffrey pines growing in Cinder Cone tephra and elsewhere for control comparison were sampled. Trees growing in tephra show synchronous ring-width changes at AD 1666, but this ring-width signal could be considered ambiguous for dating the eruption because changes in ring width can be caused by other events. Trees growing in tephra also show changes in ring phosphorus, sulfur, and sodium during the late 1660s, but inter-tree variability in dendrochemical signals makes dating the eruption from ring chemistry alone difficult. The combination of dendrochemistry and ring-width signals improves confidence in dating the eruption of Cinder Cone over the analysis of just one ring-growth property. These results are similar to another case study using dendrochronology of ring width and ring chemistry at Parícutin, Michoacán, Mexico, a cinder cone that erupted beginning in 1943. In both cases, combining analysis with ring width and ring chemistry improved confidence in the dendro-dating of the eruptions.

  2. Geologic Map of Lassen Volcanic National Park and Vicinity, California

    Science.gov (United States)

    Clynne, Michael A.; Muffler, L.J. Patrick

    2010-01-01

    The geologic map of Lassen Volcanic National Park (LVNP) and vicinity encompasses 1,905 km2 at the south end of the Cascade Range in Shasta, Lassen, Tehama, and Plumas Counties, northeastern California (fig. 1, sheet 3). The park includes 430 km2 of scenic volcanic features, glacially sculpted terrain, and the most spectacular array of thermal features in the Cascade Range. Interest in preserving the scenic wonders of the Lassen area as a national park arose in the early 1900s to protect it from commercial development and led to the establishment in 1907 of two small national monuments centered on Lassen Peak and Cinder Cone. The eruptions of Lassen Peak in 1914-15 were the first in the Cascade Range since widespread settling of the West in the late 1800s. Through the printed media, the eruptions aroused considerable public interest and inspired renewed efforts, which had languished since 1907, to establish a national park. In 1916, Lassen Volcanic National Park was established by combining the areas of the previously established national monuments and adjacent lands. The southernmost Cascade Range is bounded on the west by the Sacramento Valley and the Klamath Mountains, on the south by the Sierra Nevada, and on the east by the Basin and Range geologic provinces. Most of the map area is underlain by middle to late Pleistocene volcanic rocks; Holocene, early Pleistocene, and late Pliocene volcanic rocks (Paleozoic and Mesozoic rocks are inferred to underlie the volcanic deposits (Jachens and Saltus, 1983), but the nearest exposures of pre-Tertiary rocks are 15 km to the south, 9 km to the southwest, and 12 km to the west. Diller (1895) recognized the young volcanic geology and produced the first geologic map of the Lassen area. The map (sheet 1) builds on and extends geologic mapping by Williams (1932), Macdonald (1963, 1964, 1965), and Wilson (1961). The Lassen Peak area mapped by Christiansen and others (2002) and published in greater detail (1:24,000) was

  3. Lahar hazard zones for eruption-generated lahars in the Lassen Volcanic Center, California

    Science.gov (United States)

    Robinson, Joel E.; Clynne, Michael A.

    2012-01-01

    lahar generation, we assume that the maximum historical water equivalent, 3.90 m, covers the entire basin area inside the H/L cone. The product of planimetric area of each basin inside the H/L and the maximum historical water equivalent yields the maximum water volume available to generate a lahar. We then double the water volumes to approximate maximum lahar volumes. The maximum lahar volumes and an understanding of the statistical uncertainties inherent to the LAHARZ calculations guided our selection of six hypothetical volumes, 1, 3, 10, 30, 60, and 90x106 m3, to delineate concentric lahar inundation zones. The lahar inundation zones extend, in general, tens of kilometers away from Lassen Peak. The small, more-frequent lahar inundation zones (1 and 3x106 m3) are, on average, 10 km long. The exceptions are the zones in Warner Creek and Mill Creek, which extend much further. All but one of the small, more-frequent lahar inundation zones reach outside of the Lassen Volcanic National Park boundary, and the zone in Mill Creek extends well past the park boundary. All of the medium, moderately frequent lahar inundation zones (10 and 30x106 m3) extend past the park boundary and could potentially impact the communities of Viola and Old Station and State Highways 36 and 44, both north and west of Lassen Peak. The approximately 27-km-long on average, large, less-frequent lahar inundation zones (60 and 90x106 m3) represent worst-case lahar scenarios that are unlikely to occur. Flood hazards continue downstream from the toes of the lahars, potentially affecting communities in the Sacramento River Valley.

  4. 75 FR 61174 - Warner Valley Comprehensive Site Plan, Final Environmental Impact Statement, Lassen Volcanic...

    Science.gov (United States)

    2010-10-04

    ... electronic version was posted at both Lassen Volcanic National Park's Web site http://www.nps.gov/lavo... Control Board, the Northern Sierra Air Quality District, the Almanor Basin Fire Safe Council, and assorted... headquarters and at local public libraries, and an electronic version will also be posted on the Lassen...

  5. Quantitative analysis of the hydrothermal system in Lassen Volcanic National Park and Lassen Known Geothermal Resource Area

    Energy Technology Data Exchange (ETDEWEB)

    Sorey, M.L.; Ingebritsen, S.E.

    1984-01-01

    The Lassen hydrothermal system is in the southern Cascade Range, approximately 70 kilometers east-southeast of Redding, California. The conceptual model of the Lassen system is termed a liquid-dominated hydrothermal system with a parasitic vapor-dominated zone. The essential feature of this model is that steam and steam-heated discharge at relatively high elevations in Lassen Volcanic National Park (LVNP) and liquid discharge with high chloride concentrations at relatively low elevations outside LVNP in the Lassen Known Geothermal Resource Area (KGRA) are both fed by an upflow of high-enthalpy, two-phase fluid within the Park. Liquid flows laterally away from the upflow area towards the areas of high-chloride discharge, and steam rises through a vapor-dominated zone to feed the steam and steam-heated features. The geometric model corresponds to an areally restricted flow regime that connects the Bumpass Hell area in LVNP with regions of chloride hot springs in the Mill Creek canyon in the KGRA south of LVNP. Simulations of thermal fluid withdrawal in the Mill Creek Canyon were carried out in order to determine the effects of such withdrawal on portions of the hydrothermal system within the Park. 19 refs., 17 figs., 4 tabs.

  6. Late Cenozoic volcanism, subduction, and extension in the Lassen Region of California, southern Cascade Range

    Science.gov (United States)

    Guffanti, Marianne; Clynne, Michael A.; Smith, James G.; Muffler, L. J. P.; Bullen, Thomas D.

    1990-11-01

    Hundreds of short-lived, small- to moderate-volume, mostly mafic volcanoes occur throughout the Lassen region of NE California and surround five longer-lived, large-volume, intermediate to silicic volcanic centers younger than 3 Ma. Volcanic rocks older than 7 Ma are scarce in the Lassen region. We identify 537 volcanic vents younger than 7 Ma, and we classify these into five age intervals and five compositional categories based on SiO2 content. Maps of vents by age and composition illustrate regionally representative volcanic trends. By 2 Ma, the eastern limit of voicanism had contracted westward toward the late Quaternary arc. Late Quaternary volcanism is concentrated around and north of the silicic Lassen volcanic center. The belt of most recent volcanism (25-0 ka) has been active since at least 2 Ma. Most mafic volcanism is cakalkaline basalt and basaltic andésite. However, lesser volume of low-potassium olivine tholeiite (LKOT), a geochemically distinctive basalt type found in the northern Basin and Range province, also has erupted throughout the Lassen segment of the Cascade arc since the Pliocene. Thus models of the mantle source and tectonic control of LKOT magmatism should be applicable both within and behind the subduction-related arc. Normal faults and linear groups of vents are evidence of widespread crustal extension throughout most of the Lassen region. NNW alignments of these features indicate NNW orientation of maximum horizontal stress (ENE extension), which is similar to the stress regime in the adjacent northwestern Basin and Range and northern Sierra Nevada provinces. The large, long-lived volcanic centers developed just west of a zone of closely spaced NNW trending normal faults. Within that zone of faulting, pervasive ENE extension has precluded growth of large, long-lived crustal magma systems. We interpret the western limit of the zone of NNW trending normal faults as the western boundary of the Basin and Range province where it overlaps

  7. Astrobiology, Mars Exploration and Lassen Volcanic National Park

    Science.gov (United States)

    Des Marais, David J.

    2015-01-01

    The search for evidence of life beyond Earth illustrates how the charters of NASA and the National Park Service share common ground. The mission of NPS is to preserve unimpaired the natural and cultural resources of the National Park System for the enjoyment, education and inspiration of this and future generations. NASA's Astrobiology program seeks to understand the origins, evolution and distribution of life in the universe, and it abides by the principles of planetary stewardship, public outreach, and education. We cannot subject planetary exploration destinations to Earthly biological contamination both for ethical reasons and to preserve their scientific value for astrobiology. We respond to the public's interest in the mysteries of life and the cosmos by honoring their desire to participate in the process of discovery. We involve youth in order to motivate career choices in science and technology and to perpetuate space exploration. The search for evidence of past life on Mars illustrates how the missions of NASA and NPS can become synergistic. Volcanic activity occurs on all rocky planets in our Solar System and beyond, and it frequently interacts with water to create hydrothermal systems. On Earth these systems are oases for microbial life. The Mars Exploration Rover Spirit has found evidence of extinct hydrothermal system in Gusev crater, Mars. Lassen Volcanic National Park provides a pristine laboratory for investigating how microorganisms can both thrive and leave evidence of their former presence in hydrothermal systems. NASA scientists, NPS interpretation personnel and teachers can collaborate on field-oriented programs that enhance Mars mission planning, engage students and the public in science and technology, and emphasize the ethics of responsible exploration.

  8. Late Cenozoic volcanism, subduction, and extension in the Lassen region of California, Southern Cascade Range

    Energy Technology Data Exchange (ETDEWEB)

    Guffanti, M. (Geological Survey, Reston, VA (USA)); Clynne, M.A.; Smith, J.G.; Muffler, L.J.P.; Bullen, T.D. (Geological Survey, Menlo Park, CA (USA))

    1990-11-10

    The authors identify 537 volcanic vents younger than 7 Ma, and they classify these into five age intervals and five compositional categories based on SiO{sub 2} content. Maps of vents by age and composition illustrate regionally representative volcanic trends. Most mafic volcanism is calcalkaline basalt and basaltic andesite. However, lesser volume of low-potassium olivine tholeiite (LKOT), a geochemically distinctive basalt type found in the northern Basin and Range province, also has erupted throughout the Lassen segment of the Cascade arc since the Pliocene. Normal faults and linear groups of vents are evidence of widespread crustal extension throughout most of the Lassen region. NNW alignments of these features indicate NNW orientation of maximum horizontal stress (ENE extension), which is similar to the stress regime in the adjacent northwestern Basin and Range and northern Sierra Nevada provinces. They interpret the western limit of the zone of NNW trending normal faults as the western boundary of the Basin and Range province where it overlaps the Lassen segment of the Cascade arc. The Lassen volcanic region occurs above the subducting Gorda North plate but also lies within a broad zone of distributed extension that occurs in the North American lithosphere east and southeast of the present Cascadia subduction zone. The scarcity of volcanic rocks older than 7 Ma suggests that a more compressive lithospheric stress regime prior to the late Miocene extensional episode may have suppressed volcanism, even though subduction probably was occurring beneath the Lassen region.

  9. Soil-gas Radon Emanation in Active Hydrothermal Areas at Lassen Volcanic Center, Northern California

    Science.gov (United States)

    Chan, T.; Ararso, I.; Yanez, F.; Swamy, V.; Brandon, J.; Bartelt, E.; Cuff, K. E.

    2004-12-01

    Located along the Southern Cascade Range in Northern California, the Lassen Volcanic Center is one of the youngest major Cascade volcanoes. Aside from Mount Saint Helens, Lassen is the only Cascade volcano to erupt in the 20th century. In an effort to assess outgassing in and around Lassen, and to provide information that will contribute to a better understanding of its hydrothermal system, we have conducted detailed soil-gas radon emanation surveys in several active hydrothermal areas, which possess bubbling mud pots, steaming fumaroles, and boiling hot springs. Dozens of measurements have been made in each of these areas, which are then used to create maps that indicate areas of high outgassing. These maps are then employed to assess the degree to which volcanic and other gases are currently being emitted at Lassen, as well as to investigate patterns associated with these emissions. The mean of measurements made in a specific survey area is considered to represent the average radon flux in that area. Individual values exceeding the mean plus one standard deviation are considered to represent anomalously high emanation, while values less than the mean minus one standard deviation represent anomalously low emanation. Based on preliminary analysis of data collected so far, significant outgassing occurs along well-defined, northwest-southeast trending elongate zones in several areas. Values obtained in these zones are as much as three times background radon flux. These zones are believed to contain fractures that act as pathways for migrating gases. The results of studies conducted thus far indicate that further emanation surveys will generate very useful information.

  10. Magmatic interactions as recorded in plagioclase phenocrysts of Chaos Crags, Lassen Volcanic Center, California

    Science.gov (United States)

    Tepley, F. J.; Davidson, J.P.; Clynne, M.A.

    1999-01-01

    The silicic lava domes of Chaos Crags in Lassen Volcanic National Park contain a suite of variably quenched, hybrid basaltic andesite magmatic inclusions. The inclusions represent thorough mixing between rhyodacite and basalt recharge liquids accompanied by some mechanical disaggregation of the inclusions resulting in crystals mixing into the rhyodacite host preserved by quenching on dome emplacement. 87Sr/86Sr ratios (~0.7037-0.7038) of the inclusions are distinctly lower than those of the host rhyodacite (~0.704-0.7041), which are used to fingerprint the origin of mineral components and to monitor the mixing and mingling process. Chemical, isotopic, and textural characteristics indicate that the inclusions are hybrid magmas formed from the mixing and undercooling of recharge basaltic magma with rhyodacitic magma. All the host magma phenocrysts (biotite, plagioclase, hornblende and quartz crystals) also occur in the inclusions, where they are rimmed by reaction products. Compositional and strontium isotopic data from cores of unresorbed plagioclase crystals in the host rhyodacite, partially resorbed plagioclase crystals enclosed within basaltic andesite inclusions, and partially resorbed plagioclase crystals in the rhyodacitic host are all similar. Rim 87Sr/86Sr ratios of the partially resorbed plagioclase crystals in both inclusions and host are lower and close to those of the whole-rock hybrid basaltic andesite values. This observation indicates that some crystals originally crystallized in the silicic host, were partially resorbed and subsequently overgrown in the hybrid basaltic andesite magma, and then some of these partially resorbed plagioclase crystals were recycled back into the host rhyodacite. Textural evidence, in the form of sieve zones and major dissolution boundaries of the resorbed plagioclase crystals, indicates immersion of crystals into a hotter, more calcic magma. The occurrence of partially resorbed plagioclase together with plagioclase

  11. Hydrogen isotope investigation of amphibole and biotite phenocrysts in silicic magmas erupted at Lassen Volcanic Center, California

    Science.gov (United States)

    Underwood, S.J.; Feeley, T.C.; Clynne, M.A.

    2012-01-01

    Hydrogen isotope ratio, water content and Fe3 +/Fe2 + in coexisting amphibole and biotite phenocrysts in volcanic rocks can provide insight into shallow pre- and syn-eruptive magmatic processes such as vesiculation, and lava drainback with mixing into less devolatilized magma that erupts later in a volcanic sequence. We studied four ~ 35 ka and younger eruption sequences (i.e. Kings Creek, Lassen Peak, Chaos Crags, and 1915) at the Lassen Volcanic Center (LVC), California, where intrusion of crystal-rich silicic magma mushes by mafic magmas is inferred from the varying abundances of mafic magmatic inclusions (MMIs) in the silicic volcanic rocks. Types and relative proportions of reacted and unreacted hydrous phenocryst populations are evaluated with accompanying chemical and H isotope changes. Biotite phenocrysts were more susceptible to rehydration in older vesicular glassy volcanic rocks than coexisting amphibole phenocrysts. Biotite and magnesiohornblende phenocrysts toward the core of the Lassen Peak dome are extensively dehydroxylated and reacted from prolonged exposure to high temperature, low pressure, and higher fO2 conditions from post-emplacement cooling. In silicic volcanic rocks not affected by alteration, biotite phenocrysts are often relatively more dehydroxylated than are magnesiohornblende phenocrysts of similar size; this is likely due to the ca 10 times larger overall bulk H diffusion coefficient in biotite. A simplified model of dehydrogenation in hydrous phenocrysts above reaction closure temperature suggests that eruption and quench of magma ascended to the surface in a few hours is too short a time for substantial H loss from amphibole. In contrast, slowly ascended magma can have extremely dehydrogenated and possibly dehydrated biotite, relatively less dehydrogenated magnesiohornblende and reaction rims on both phases. Eruptive products containing the highest proportions of mottled dehydrogenated crystals could indicate that within a few days

  12. Seismicity and fluid geochemistry at Lassen Volcanic National Park, California: Evidence for two circulation cells in the hydrothermal system

    Science.gov (United States)

    Janik, Cathy J.; McLaren, Marcia K.

    2010-01-01

    Seismic analysis and geochemical interpretations provide evidence that two separate hydrothermal cells circulate within the greater Lassen hydrothermal system. One cell originates south to SW of Lassen Peak and within the Brokeoff Volcano depression where it forms a reservoir of hot fluid (235–270°C) that boils to feed steam to the high-temperature fumarolic areas, and has a plume of degassed reservoir liquid that flows southward to emerge at Growler and Morgan Hot Springs. The second cell originates SSE to SE of Lassen Peak and flows southeastward along inferred faults of the Walker Lane belt (WLB) where it forms a reservoir of hot fluid (220–240°C) that boils beneath Devils Kitchen and Boiling Springs Lake, and has an outflow plume of degassed liquid that boils again beneath Terminal Geyser. Three distinct seismogenic zones (identified as the West, Middle, and East seismic clusters) occur at shallow depths (inversions indicate primarily N–S oriented normal faulting and E–W extension, with some oblique faulting and right lateral shear in the East cluster. The different focal mechanisms as well as spatial and temporal earthquake patterns for the East cluster indicate a greater influence by regional tectonics and inferred faults within the WLB. A fourth, deeper (5–10 km) seismogenic zone (the Devils Kitchen seismic cluster) occurs SE of the East cluster and trends NNW from Sifford Mountain toward the Devils Kitchen thermal area where fumarolic temperatures are ≤123°C. Lassen fumaroles discharge geothermal gases that indicate mixing between a N2-rich, arc-type component and gases derived from air-saturated meteoric recharge water. Most gases have relatively weak isotopic indicators of upper mantle or volcanic components, except for gas from Sulphur Works where δ13C–CO2, δ34S–H2S, and δ15N–N2 values indicate a contribution from the mantle and a subducted sediment source in an arc volcanic setting.

  13. Thermal and mass implications of magmatic evolution in the Lassen volcanic region, California, and minimum constraints on basalt influx to the lower crust

    Science.gov (United States)

    Guffanti, M.; Clynne, M.A.; Muffler, L.J.P.

    1996-01-01

    We have analyzed the heat and mass demands of a petrologic model of basaltdriven magmatic evolution in which variously fractionated mafic magmas mix with silicic partial melts of the lower crust. We have formulated steady state heat budgets for two volcanically distinct areas in the Lassen region: the large, late Quaternary, intermediate to silicic Lassen volcanic center and the nearby, coeval, less evolved Caribou volcanic field. At Caribou volcanic field, heat provided by cooling and fractional crystallization of 52 km3 of basalt is more than sufficient to produce 10 km3 of rhyolitic melt by partial melting of lower crust. Net heat added by basalt intrusion at Caribou volcanic field is equivalent to an increase in lower crustal heat flow of ???7 mW m-2, indicating that the field is not a major crustal thermal anomaly. Addition of cumulates from fractionation is offset by removal of erupted partial melts. A minimum basalt influx of 0.3 km3 (km2 Ma)-1 is needed to supply Caribou volcanic field. Our methodology does not fully account for an influx of basalt that remains in the crust as derivative intrusives. On the basis of comparison to deep heat flow, the input of basalt could be ???3 to 7 times the amount we calculate. At Lassen volcanic center, at least 203 km3 of mantle-derived basalt is needed to produce 141 km3 of partial melt and drive the volcanic system. Partial melting mobilizes lower crustal material, augmenting the magmatic volume available for eruption at Lassen volcanic center; thus the erupted volume of 215 km3 exceeds the calculated basalt input of 203 km3. The minimum basalt input of 1.6 km3 (km2 Ma)-1 is >5 times the minimum influx to the Caribou volcanic field. Basalt influx high enough to sustain considerable partial melting, coupled with locally high extension rate, is a crucial factor in development of Lassen volcanic center; in contrast. Caribou volcanic field has failed to develop into a large silicic center primarily because basalt supply

  14. Localized rejuvenation of a crystal mush recorded in zircon temporal and compositional variation at the Lassen Volcanic Center, northern California.

    Science.gov (United States)

    Klemetti, Erik W; Clynne, Michael A

    2014-01-01

    Zircon ages and trace element compositions from recent silicic eruptions in the Lassen Volcanic Center (LVC) allow for an evaluation of the timing and conditions of rejuvenation (reheating and mobilization of crystals) within the LVC magmatic system. The LVC is the southernmost active Cascade volcano and, prior to the 1980 eruption of Mount St. Helens, was the site of the only eruption in the Cascade arc during the last century. The three most recent silicic eruptions from the LVC were very small to moderate-sized lava flows and domes of dacite (1915 and 27 ka eruptions of Lassen Peak) and rhyodacite (1.1 ka eruption of Chaos Crags). These eruptions produced mixed and mingled lavas that contain a diverse crystal cargo, including zircon. 238U-230Th model ages from interior and surface analyses of zircon reveal ages from ∼17 ka to secular equilibrium (>350 ka), with most zircon crystallizing during a period between ∼60-200 ka. These data support a model for localized rejuvenation of crystal mush beneath the LVC. This crystal mush evidently is the remnant of magmatism that ended ∼190 ka. Most zircon are thought to have been captured from "cold storage" in the crystal mush (670-725°C, Hf >10,000 ppm, Eu/Eu* 0.25-0.4) locally remobilized by intrusion of mafic magma. A smaller population of zircon (>730°C, Hf 0.4) grew in, and are captured from, rejuvenation zones. These data suggest the dominant method to produce eruptible melt within the LVC is small-scale, local rejuvenation of the crystal mush accompanied by magma mixing and mingling. Based on zircon stability, the time required to heat, erupt and then cool to background conditions is relatively short, lasting a maximum of 10 s-1000 s years. Rejuvenation events in the LVC are ephemeral and permit eruption within an otherwise waning and cooling magmatic body.

  15. Morphometric characterization of monogenetic volcanic cones of the Chichinautzin and Michoacán-Guanajuato monogenetic volcanic fields in Mexico

    Science.gov (United States)

    Zarazua-Carbajal, Maria Cristina; De la Cruz-Reyna, Servando; Mendoza-Rosas, Ana Teresa

    2014-05-01

    Morphometric characterization of volcanic edifices is one of the main approaches providing information about a volcano eruptive history, whether it has one or more eruptive vents or if it had any sector collapses. It also provides essential information about the physical processes that modify their shapes during periods of quietness, and quite significantly, about the volcanoes' ages. In the case of monogenetic activity, a volcanic field can be characterized by the size and slope distributions, and other cone's morphometric parameter distributions that may provide valuable information about the temporal evolution of the volcanic field. The increasingly available high-resolution digital elevation models and the continuously developing computer tools have allowed a faster development and more detailed morphometric characterization techniques. We present here a methodology to readily obtain diverse volcanic cone shape parameters from the contour curves such as mean slope, slope distribution, dimensions of the cone and crater, crater location within the cone, orientation of the cone's principal axis, eccentricity, and other morphological features using an analysis algorithm that we developed, programmed in Python and ArcPy. Preliminary results from the implementation of this methodology to the Chichinautzin and Michoacán-Guanajuato monogenetic volcanic fields in Mexico have permitted a preliminary estimation of the age distribution of some of the cones with an acceptable correlation with the available radiometric ages. A large part of the Chichinautzin region DEM was obtained from a LIDAR survey by the Mexican National Institute of Statistics and Geography (INEGI).

  16. Measurements and Slope Analyses of Quaternary Cinder Cones, Camargo Volcanic Field, Chihuahua, Mexico

    Science.gov (United States)

    Gallegos, M. I.; Espejel-Garcia, V. V.

    2012-12-01

    The Camargo volcanic field (CVF) covers ~3000 km2 and is located in the southeast part of the state of Chihuahua, within the Basin and Range province. The CVF represents the largest mafic alkali volcanic field in northern Mexico. Over a 300 cinder cones have been recognized in the Camargo volcanic field. Volcanic activity ranges from 4.7 to 0.09 Ma revealed by 40Ar/39Ar dating methods. Previous studies say that there is a close relationship between the cinder cone slope angle, due to mechanical weathering, and age. This technique is considered a reliable age indicator, especially in arid climates, such as occur in the CVF. Data were acquired with digital topographic maps (DRG) and digital elevation models (DEM) overlapped in the Global Mapper software. For each cone, the average radius (r) was calculated from six measurements, the height (h) is the difference between peak elevation and the altitude of the contour used to close the radius, and the slope angle was calculated using the equation Θ = tan-1(h/r). The slope angles of 30 cinder cones were calculated showing angles ranging from 4 to 15 degrees. A diffusion model, displayed by an exponential relationship between slope angle and age, places the ages of these 30 cones from 215 to 82 ka, within the range marked by radiometric methods. Future work include the analysis of more cinder cones to cover the whole CVF, and contribute to the validation of this technique.

  17. Modeling Lahar Hazard Zones for Eruption-Generated Lahars from Lassen Peak, California

    Science.gov (United States)

    Robinson, J. E.; Clynne, M. A.

    2010-12-01

    Lassen Peak, a high-elevation, seasonally snow-covered peak located within Lassen Volcanic National Park, has lahar deposits in several drainages that head on or near the lava dome. This suggests that these drainages are susceptible to future lahars. The majority of the recognized lahar deposits are related to the May 19 and 22, 1915 eruptions of Lassen Peak. These small-volume eruptions generated lahars and floods when an avalanche of snow and hot rock, and a pyroclastic flow moved across the snow-covered upper flanks of the lava dome. Lahars flowed to the north down Lost Creek and Hat Creek. In Lost Creek, the lahars flowed up to 16 km downstream and deposited approximately 8.3 x 106 m3 of sediment. This study uses geologic mapping of the 1915 lahar deposits as a guide for LAHARZ modeling to assist in the assessment of present-day susceptibility for lahars in drainages heading on Lassen Peak. The LAHARZ model requires a Height over Length (H/L) energy cone controlling the initiation point of a lahar. We chose a H/L cone with a slope of 0.3 that intersects the earth’s surface at the break in slope at the base of the volcanic dome. Typically, the snow pack reaches its annual maximum by May. Average and maximum May snow-water content, a depth of water equal to 2.1 m and 3.5 m respectively, were calculated from a local snow gauge. A potential volume for individual 1915 lahars was calculated using the deposit volume, the snow-water contents, and the areas stripped of snow by the avalanche and pyroclastic flow. The calculated individual lahars in Lost Creek ranged in size from 9 x 106 m3 to 18.4 x 106 m3. These volumes modeled in LAHARZ matched the 1915 lahars remarkably well, with the modeled flows ending within 4 km of the mapped deposits. We delineated six drainage basins that head on or near Lassen Peak with the highest potential for lahar hazards: Lost Creek, Hat Creek, Manzanita Creek, Mill Creek, Warner Creek, and Bailey Creek. We calculated the area of each

  18. Sedimentology, eruptive mechanism and facies architecture of basaltic scoria cones from the Auckland Volcanic Field (New Zealand)

    Science.gov (United States)

    Kereszturi, Gábor; Németh, Károly

    2016-09-01

    Scoria cones are a common type of basaltic to andesitic small-volume volcanoes (e.g. 10- 1-10- 5 km3) that results from gas-bubble driven explosive eruptive styles. Although they are small in volume, they can produce complex eruptions, involving multiple eruptive styles. Eight scoria cones from the Quaternary Auckland Volcanic Field in New Zealand were selected to define the eruptive style variability from their volcanic facies architecture. The reconstruction of their eruptive and pyroclastic transport mechanisms was established on the basis of study of their volcanic sedimentology, stratigraphy, and measurement of their pyroclast density, porosity, Scanning Electron Microscopy, 2D particle morphology analysis and Visible and Near Visible Infrared Spectroscopy. Collection of these data allowed defining three end-member types of scoria cones inferred to be constructed from lava-fountaining, transitional fountaining and Strombolian type, and explosive Strombolian type. Using the physical and field-based characteristics of scoriaceous samples a simple generalised facies model of basaltic scoria cones for the AVF is developed that can be extended to other scoria cones elsewhere. The typical AVF scoria cone has an initial phreatomagmatic phases that might reduce the volume of magma available for subsequent scoria cone forming eruptions. This inferred to have the main reason to have decreased cone volumes recognised from Auckland in comparison to other volcanic fields evolved dominantly in dry eruptive condition (e.g. no external water influence). It suggests that such subtle eruptive style variations through a scoria cone evolution need to be integrated into the hazard assessment of a potentially active volcanic field such as that in Auckland.

  19. The Lassen hydrothermal system

    Science.gov (United States)

    Ingebritsen, Steven E.; Bergfeld, Deborah; Clor, Laura; Evans, William C.

    2016-01-01

    The active Lassen hydrothermal system includes a central vapor-dominated zone or zones beneath the Lassen highlands underlain by ~240 °C high-chloride waters that discharge at lower elevations. It is the best-exposed and largest hydrothermal system in the Cascade Range, discharging 41 ± 10 kg/s of steam (~115 MW) and 23 ± 2 kg/s of high-chloride waters (~27 MW). The Lassen system accounts for a full 1/3 of the total high-temperature hydrothermal heat discharge in the U.S. Cascades (140/400 MW). Hydrothermal heat discharge of ~140 MW can be supported by crystallization and cooling of silicic magma at a rate of ~2400 km3/Ma, and the ongoing rates of heat and magmatic CO2 discharge are broadly consistent with a petrologic model for basalt-driven magmatic evolution. The clustering of observed seismicity at ~4–5 km depth may define zones of thermal cracking where the hydrothermal system mines heat from near-plastic rock. If so, the combined areal extent of the primary heat-transfer zones is ~5 km2, the average conductive heat flux over that area is >25 W/m2, and the conductive-boundary length <50 m. Observational records of hydrothermal discharge are likely too short to document long-term transients, whether they are intrinsic to the system or owe to various geologic events such as the eruption of Lassen Peak at 27 ka, deglaciation beginning ~18 ka, the eruptions of Chaos Crags at 1.1 ka, or the minor 1914–1917 eruption at the summit of Lassen Peak. However, there is a rich record of intermittent hydrothermal measurement over the past several decades and more-frequent measurement 2009–present. These data reveal sensitivity to climate and weather conditions, seasonal variability that owes to interaction with the shallow hydrologic system, and a transient 1.5- to twofold increase in high-chloride discharge in response to an earthquake swarm in mid-November 2014.

  20. Mars Global Surveyor Data Analysis Program. Origins of Small Volcanic Cones: Eruption Mechanisms and Implications for Water on Mars

    Science.gov (United States)

    Fagents, Sarah A.; Greeley, Ronald; Thordarson, Thorvaldur

    2002-01-01

    The goal of the proposed work was to determine the origins of small volcanic cones observed in Mars Global Surveyor (MGS) data, and their implications for regolith ice stores and magma volatile contents. For this 1-year study, our approach involved a combination of: Quantitative morphologic analysis and interpretation of Mars Orbiter Camera (MOC) and Mars Orbiter Laser Altimeter (MOLA) data; Numerical modeling of eruption processes responsible for producing the observed features; Fieldwork on terrestrial analogs in Iceland. Following this approach, this study succeeded in furthering our understanding of (i) the spatial and temporal distribution of near-surface water ice, as defined by the distribution and sizes of rootless volcanic cones ("pseudocraters"), and (ii) the properties, eruption conditions, and volatile contents of magmas producing primary vent cones.

  1. Constraining the origin of La Poruña scoria cone, Central Volcanic Zone, northern Chile

    Science.gov (United States)

    González-Maurel, O. P.; Godoy, B.; Rodriguez, I.; Menzies, A.; le Roux, P. J.; Bertin, D.; Marin, C.

    2017-12-01

    The magmatic arc in the Andean Central Volcanic Zone has evolved over a 70 km thick continental crust. Accordingly, true basalts are scarce, with basaltic-andesite being the least evolved volcanic product. In the active arc of northern Chile, this mafic volcanism is found as isolated lava flows and pyroclastic material. La Poruña (21°53'S; 68°30'W) is a 180 m high scoria cone constituted of pyroclastic material and extensive lava flows that are up to 8 km in length. La Poruña lavas show a range of 40Ar/39Ar ages in whole-rock and groundmass from 110 to 54 ka (Bertin and Amigo, in prep.) and its origin has been related to the evolution of San Pedro, a stratovolcano located 13 km to the east (O'Callaghan and Francis, 1986). Microscopic petrography and automated mineralogy analyses by QEMSCAN show that volcanic products from La Poruña have plagioclase and olivine, with subordinated ortho- and clino- pyroxene phenocrysts. Lavas and pyroclastic flows from the San Pedro volcano are predominantly plagioclase and orthopyroxene phenocrysts, with minor olivine and clinopyroxene. Geochemically, La Poruña samples show basaltic-andesite to andesite compositions (56.0-59.6 wt% SiO2; 482-654 ppm Sr), whilst 87Sr/86Sr and 143Nd/144Nd isotopic ratios vary between 0.7062 to 0.7066, and 0.51239 to 0.51245, respectively. Samples from San Pedro with similar ages as those from La Poruña (140 to 60 ka, 40Ar/39Ar; Bertin and Amigo, in prep.), have mainly andesitic compositions (55.9-63.8 wt% SiO2; 412-639 ppm Sr) with 87Sr/86Sr ratios (0.7064-0.7067) and 143Nd/144Nd ratios (0.51236-0.51243), overlapping those from La Poruña. Although the presented data is similar, there are observable differences on geochemical and isotopic characteristics of flows from La Poruña cone and San Pedro volcano. When related to SiO2 (wt. %) and Sr (ppm) concentrations, the Sr-isotope ratios from La Poruña show a well-defined cluster that has lower values than contemporaneous lavas from San Pedro

  2. Compound maar crater and co-eruptive scoria cone in the Lunar Crater Volcanic Field (Nevada, USA)

    Science.gov (United States)

    Amin, Jamal; Valentine, Greg A.

    2017-06-01

    Bea's Crater (Lunar Crater Volcanic Field, Nevada, USA) consists of two coalesced maar craters with diameters of 440 m and 1050 m, combined with a co-eruptive scoria cone that straddles the northeast rim of the larger crater. The two craters and the cone form an alignment that parallels many local and regional structures such as normal faults, and is interpreted to represent the orientation of the feeder dyke near the surface. The maar formed among a dense cluster of scoria cones; the cone-cluster topography resulted in crater rim that has a variable elevation. These older cones are composed of variably welded agglomerate and scoria with differing competence that subsequently affected the shape of Bea's Crater. Tephra ring deposits associated with phreatomagmatic maar-forming eruptions are rich in basaltic lithics derived from clasts, consistent with ejection from relatively shallow explosions although a diatreme might extend to deeper levels beneath the maar. Interbedding of deposits on the northeastern cone and in the tephra ring record variations in the magmatic volatile driven and phreatomagmatic eruption styles in both space and time along a feeder dike.

  3. Reconstruction of eroded monogenic Strombolian cones of Miocene age: A case study on character of volcanic activity of the Jičín Volcanic Field (NE Bohemia) and subsequent erosional rates estimation

    Czech Academy of Sciences Publication Activity Database

    Rapprich, V.; Cajz, Vladimír; Košťák, M.; Pécskay, Z.; Řídkošil, T.; Raška, P.; Radoň, M.

    2007-01-01

    Roč. 52, 3-4 (2007), s. 169-180 ISSN 0449-2560 R&D Projects: GA AV ČR IAA300130612 Institutional research plan: CEZ:AV0Z30130516 Keywords : cinder cone * Strombolian eruption * volcanic facies * erosion rate * Jičín Volcanic Field * Bohemian Paradise GeoPark Subject RIV: DB - Geology ; Mineralogy

  4. Construction of the North Head (Maungauika) tuff cone: a product of Surtseyan volcanism, rare in the Auckland Volcanic Field, New Zealand

    Science.gov (United States)

    Agustín-Flores, Javier; Németh, Károly; Cronin, Shane J.; Lindsay, Jan M.; Kereszturi, Gábor

    2015-02-01

    The Auckland Volcanic Field (AVF) comprises at least 52 monogenetic eruption centres dispersed over ˜360 km2. Eruptions have occurred sporadically since 250 ka, predominantly when glacio-eustatic sea levels were lower than today. Now that around 35 % of the field is covered by shallow water (up to 30 m depth), any eruption occurring in the present or near future within this area may display Surtseyan dynamics. The North Head tuff cone evidences eruptive dynamics caused by magma interaction with seawater. The first stages of the eruption comprise a phreatomagmatic phase that built a 48-m-high tuff cone. North Head tuff deposits contain few lithic fragments (Auckland area was at least 10-12 m above the pre-eruptive surface. The hazards associated with this type of eruption pose a risk to the densely populated coastal residential zones and the activities of one of the busiest harbours in New Zealand.

  5. A unique volcanic field in Tharsis, Mars: Pyroclastic cones as evidence for explosive eruptions

    Czech Academy of Sciences Publication Activity Database

    Brož, Petr; Hauber, E.

    2012-01-01

    Roč. 218, č. 1 (2012), s. 88-99 ISSN 0019-1035 R&D Projects: GA MŠk ME09011 Institutional research plan: CEZ:AV0Z30120515 Keywords : Mars * volcanism * Mars surface Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 3.161, year: 2012

  6. Aspen Delineation - Lassen National Forest [ds372

    Data.gov (United States)

    California Department of Resources — The database represents delineations of aspen stands associated with stand assessment data (LASSEN_NF_EAGLELAKE_PTS) collected in aspen stands in the in the Eagle...

  7. Aspen Characteristics - Lassen National Forest [ds371

    Data.gov (United States)

    California Department of Resources — The database represents point locations and associated stand assessment data collected in aspen stands in the in the Eagle Lake Ranger District, Lassen National...

  8. El Estribo Volcanic Complex: Evolution from a shield volcano to a cinder cone, Pátzcuaro Lake, Michoacán, México

    Science.gov (United States)

    Pola, A.; Macías, J. L.; Osorio-Ocampo, S.; Sosa-Ceballos, G.; Garduño-Monroy, V. H.; Martínez-Martínez, J.

    2015-09-01

    El Estribo Volcanic Complex (EVC) is located in the northern part of the Michoacán-Guanajuato Volcanic Field within the Trans-Mexican Volcanic Belt (TMVB). El Estribo is located at the southern edge of the E-W Pátzcuaro fault that belongs to the Pátzcuaro-Jarácuaro graben, a western extension of the E-W Morelia-Acambay fault system. Stratigraphy, geochronology, chemistry, and mineral assemblages suggest that the volcanic complex was constructed in two periods separated by a ~ 100 ka volcanic hiatus: a) emission of lava flows that constructed a shield volcano between 126 ka, and b) mixed phreatomagmatic to Strombolian activity that formed a cinder cone ~ 28 ka. The magmas that fed these monogenetic volcanoes were able to use the same feeding system. The cinder cone itself was constructed by Strombolian fallouts and remobilized scoria beds, followed by an erosion period, and by a mixed phreatomagmatic to magmatic phase (Strombolian fallouts ending with lava flows). Soft-sedimentary deformation of beds and impact sags, cross-bedding, as well as pitting and hydrothermal cracks found in particles support the phreatomagmatic phase. The erupted magmas through time ejected basaltic andesitic lava flows (56.21-58.88% SiO2) that built the shield volcano and then basaltic andesitic scoria (57.65-59.05% SiO2) that constructed the cinder cone. Although they used the same feeding system, the geochemical data and the mineral chemistry of the magmas indicate that the shield volcano and the cinder cone were fed by different magma batches erupted thousands of years apart. Therefore, the location of El Estribo Volcanic Complex along an E-W fault that has generated two sector collapses of the shield volcano to the north may be directly linked to this complex redistribution of the magmatic paths to the surface. Our findings show that magmatic feeding systems within monogenetic volcanic fields could be long lived, questioning the classic view of the monogenetic nature of their

  9. Hydrothermal response to a volcano-tectonic earthquake swarm, Lassen, California

    Science.gov (United States)

    Ingebritsen, Steven E.; Shelly, David R.; Hsieh, Paul A.; Clor, Laura; P.H. Seward,; Evans, William C.

    2015-01-01

    The increasing capability of seismic, geodetic, and hydrothermal observation networks allows recognition of volcanic unrest that could previously have gone undetected, creating an imperative to diagnose and interpret unrest episodes. A November 2014 earthquake swarm near Lassen Volcanic National Park, California, which included the largest earthquake in the area in more than 60 years, was accompanied by a rarely observed outburst of hydrothermal fluids. Although the earthquake swarm likely reflects upward migration of endogenous H2O-CO2 fluids in the source region, there is no evidence that such fluids emerged at the surface. Instead, shaking from the modest sized (moment magnitude 3.85) but proximal earthquake caused near-vent permeability increases that triggered increased outflow of hydrothermal fluids already present and equilibrated in a local hydrothermal aquifer. Long-term, multiparametric monitoring at Lassen and other well-instrumented volcanoes enhances interpretation of unrest and can provide a basis for detailed physical modeling.

  10. Possible application of compact electronics for multilayer muon high-speed radiography to volcanic cones

    Science.gov (United States)

    Tanaka, H. K. M.; Yokoyama, I.

    2013-11-01

    Compact data-taking electronics were developed for high-speed multilayer muon radiography in order to minimize operation failure rates. By requiring a linear trajectory within the position sensitive detectors (PSDs), the background (BG) events produced by vertical electromagnetic (EM) showers are effectively reduced. In order to confirm the feasibility of this method, the system comprising four PSD layers was tested by imaging the internal structure of a parasitic cone and the adjacent craterlets formed in the 1910 eruption at the base of the Usu volcano, Hokkaido with a conventional (MURG08) readout system (Kusagaya et al., 2012; Uchida et al., 2009). The new mountain is believed to be a cryptodome since its formation. As knowledge on lava domes is accumulated at various volcanoes, the definition of "cryptodome" is now doubted in its validity. The results of the preliminary 290 h muon radiographic survey revealed that the "cryptodome" is not underlain by any lava mass and that a main craterlet is accompanied by magma intrusions at shallow depths. The former verifies that the new mountain is not a cryptodome but a volcanogenetic mound, and the latter interprets the phreatic explosions forming the craterlets as intrusions of magma into the aquifer. However, a higher data taking failure rate was observed with a software-based MURG08 system when the size of the active area of the detection system was enlarged to improve the detection ability of the system. The newly developed MURG12 is a complete electronics system that can simultaneously process signals from 192 scintillation counters with a data size of 600 kbps ch-1 without operation failure. We anticipate that the observation speed would be further improved by employing MURG12. At the base of the Usu volcano, in the 20th century, four eruptions occurred. Some of them demonstrated three characteristic stages of magma intrusions. First, a magma branch remained at a depth leaving an upheaval of the ground; second, it

  11. Surface exposure dating of Holocene basalt flows and cinder cones in the Kula volcanic field (western Turkey) using cosmogenic 3He and 10Be

    Science.gov (United States)

    Heineke, Caroline; Niedermann, Samuel; Hetzel, Ralf; Akal, Cüneyt

    2015-04-01

    The Kula volcanic field is the youngest volcanic province in western Anatolia and covers an area of about 600 km2 around the town Kula (Richardson-Bunbury, 1996). Its alkali basalts formed by melting of an isotopically depleted mantle in a region of long-lived continental extension and asthenospheric upwelling (Prelevic et al., 2012). Based on morphological criteria and 40Ar/39Ar dating, four phases of Quaternary activity have been distinguished in the Kula volcanic field (Richardson-Bunbury, 1996; Westaway et al., 2006). The youngest lava flows are thought to be Holocene in age, but so far only one sample from this group was dated by 40Ar/39Ar at 7±2 ka (Westaway et al., 2006). In this study, we analysed cosmogenic 3He in olivine phenocrysts from three basalt flows and one cinder cone to resolve the Holocene history of volcanic eruptions in more detail. In addition, we applied 10Be exposure dating to two quartz-bearing xenoliths found at the surface of one flow and at the top of one cinder cone. The exposure ages fall in the range between ~500 and ~3000 years, demonstrating that the youngest volcanic activity is Late Holocene in age and therefore distinctly younger than previously envisaged. Our results show that the Late Holocene lava flows are not coeval but formed over a period of a few thousand years. We conclude that surface exposure dating of very young volcanic rocks provides a powerful alternative to 40Ar/39Ar dating. References Prelevic, D., Akal, C. Foley, S.F., Romer, R.L., Stracke, A. and van den Bogaard, P. (2012). Ultrapotassic mafic rocks as geochemical proxies for post-collisional dynamics of orogenic lithospheric mantle: the case of southwestern Anatolia, Turkey. Journal of Petrology, 53, 1019-1055. Richardson-Bunbury, J.M. (1996). The Kula Volcanic Field, western Turkey: the development of a Holocene alkali basalt province and the adjacent normal-faulting graben. Geological Magazine, 133, 275-283. Westaway, R., Guillou, H., Yurtmen, S., Beck, A

  12. The Lassen Astrobiology Intern Program - Concept, Implementation and Evaluation

    Science.gov (United States)

    Des Marais, D. J.; Dueck, S. L.; Davis, H. B.; Parenteau, M. N.; Kubo, M. D.

    2014-12-01

    The program goal was to provide a hands-on astrobiology learning experience to high school students by introducing astrobiology and providing opportunities to conduct field and lab research with NASA scientists. The program sought to increase interest in interdisciplinary science, technology, engineering, math and related careers. Lassen Volcanic National Park (LVNP), Red Bluff High School and the Ames Team of the NASA Astrobiology Institute led the program. LVNP was selected because it shares aspects of volcanism with Mars and it hosts thermal springs with microbial mat communities. Students documented volcanic deposits, springs and microbial mats. They analyzed waters and sampled rocks, water and microorganisms. They cultured microorganisms and studied chemical reactions between rocks and simulated spring waters. Each student prepared a report to present data and discuss relationships between volcanic rocks and gases, spring waters and microbial mats. At a "graduation" event the students presented their findings to the Red Bluff community. They visited Ames Research Center to tour the facilities and learn about science and technology careers. To evaluate program impact, surveys were given to students after lectures, labs, fieldwork and discussions with Ames scientists. Students' work was scored using rubrics (labs, progress reports, final report, presentation). Students took pre/post tests on core astrobiology concepts. Parents, teachers, rangers, Ames staff and students completed end-of-year surveys on program impact. Several outcomes were documented. Students had a unique and highly valued learning experience with NASA scientists. They understood what scientists do through authentic scientific work, and what scientists are like as individuals. Students became knowledgeable about astrobiology and how it can be pursued in the lab and in the field. The students' interest increased markedly in astrobiology, interdisciplinary studies and science generally.

  13. Turning population trend monitoring into active conservation: Can we save the cascades frog (Rang cascadae) in the Lassen Region of California?

    Science.gov (United States)

    Fellers, G.M.; Pope, K.L.; Stead, J.E.; Koo, M.S.; Welsh, W.H.

    2008-01-01

    Monitoring the distribution, population size, and trends of declining species is necessary to evaluate their vulnerability to extinction. It is the responsibility of scientists to alert management professionals of the need for preemptive action if a species approaches imminent, regional extirpation. This is the case with Rana cascadae (Cascades Frog) populations near Lassen Peak From 1993 to 2007, we conducted 1,873 amphibian surveys at 856 sites within Lassen Volcanic National Park and Lassen National Forest, California, USA. These surveys encompassed all R. cascadae habitats: ponds, lakes, meadows, and streams on those lands. We found frogs at only six sites during 14 years of surveys, and obtained one report of a single frog at one additional locality. These sites represented 12 years. Causes for the decline remain unclear, but introduced trout, disease, and pesticides are likely factors. We recommend that (1) additional protection for R. cascadae within 50 km of Lassen Peak; (2) investigation of the genetics of R. cascadae in California; (3) research into the role of possible causative factors in these declines; and (4) implementation of a feasibility study to captive breed and reintroduce R. cascadae in the Lassen area. Copyright ?? 2008. Gary Fellers. All rights reserved.

  14. Intrusive hyaloclastite and peperitic breccias associated to sill and cryptodome emplacement on an Early Paleocene polymagmatic compound cone-dome volcanic complex from El Guanaco mine, Northern Chile

    Science.gov (United States)

    Páez, G. N.; Permuy Vidal, C.; Galina, M.; López, L.; Jovic, S. M.; Guido, D. M.

    2018-04-01

    This work explores the textural characteristics, morphology and facies architecture of well-preserved Paleocene hyaloclastic and peperitic breccias associated with subvolcanic intrusions at El Guanaco gold mine (Northern Chile). The El Guanaco mine volcanic sequence is part of a polymagmatic compound cone-dome volcanic complex grouping several dacitic domes and maar-diatremes, and subordinated subvolcanic intrusions of basaltic, andesitic and dacitic compositions. The Soledad-Peñafiel Fault System is a first order regional structure controlling the location and style of the volcanism in the region. Three different intrusive bodies (Basaltic sills, Dacitic cryptodomes and Andesitic cryptodomes) were found to intrude into a wet and poorly consolidated pyroclastic sequence representing the upper portions of a maar-diatreme. Consequently, extensive quench fragmentation and fluidization along their contacts occurred, leading to the formation of widespread breccia bodies enclosing a coherent nucleus. Differences in matrix composition allows to define two main breccias types: 1) poorly-sorted monomictic breccias (intrusive hyaloclastites) and 2) poorly-sorted tuff-matrix breccias (peperites). The observed facies architecture is interpreted as the result of the interplay of several factors, including: 1) magma viscosity, 2) the geometry of the intrusives, and 3) variations on the consolidation degree of the host rocks. Additionally, the overall geometry of each intrusive is interpreted to be controlled by the effective viscosity of the magmas along with the available magma volume at the time of the intrusions. The presence of three compositionally different subvolcanic bodies with intrusive hyaloclastite and peperite envelopes indicate, not only that all these intrusions occurred in a short period of time (probably less than 2-3 Ma), but also that the volcaniciclastic pile suffer little or none compaction nor consolidation during that time. The presence of three

  15. Volatile emissions from Cascade cinder cone eruptions: Implications for future hazard assessments in the Central and Southern Cascades

    Science.gov (United States)

    Walsh, L. K.; Wallace, P. J.; Cashman, K. V.

    2012-12-01

    An abundance of hazardous effects including ash fall out, basaltic lava flows and poisonous volcanic gas have been documented at active volcanic centers (e.g. Auckland Volcanic Field, New Zealand; Bebbington and Cronin 2011) and have been inferred using tools such as geologic mapping and geochemical analyses for prehistoric eruptions (e.g. Cerro Negro, Nicaragua; Hill et al. 1995; McKnight and Williams 1997). The Cascades volcanic history is also dominated by prehistoric eruptions; however the associated hazards have yet to be studied in-depth. Short recurrence rates of cinder cone volcanism (1x10-5 to 5x10-4 events/yr; Smid et al. 2009) likely intensify the probability of human experience with cinder cone hazards. Hence, it is important to understand the effects that cinder cone volcanism can have on communities near the Cascades. In this study, we estimate volatile fluxes of prehistoric Cascade cinder cone eruptions by analyzing olivine-hosted melt inclusions and rapidly quenched tephra matrix glass. The melt inclusions provide pre-eruptive volatile concentrations whereas tephra groundmass glass provides post-eruptive volatile concentrations. By comparing initial and final concentrations we can determine the amounts of sulfur, chlorine and fluorine released into the atmosphere. We have analyzed S, Cl and F concentrations in melt inclusions from cinder cones in the Central Oregon Cascades (Collier Cone, Yapoah Crater, Four-in-One Fissure, Garrison Butte) and in Northern California near Mt. Lassen (Cinder Cone, Basalt of Old Railroad Grade, Basalt of Highway 44). Analyses of volatiles in melt inclusions and matrix glasses were done using the Cameca SX100 electron microprobe at the University of Oregon. Melt inclusions and matrix glass were run under 15kV, 50nA, and 10μm-beam conditions. For F analyses, a use of an LTAP crystal and relatively long counting times (160 sec. on peak) resulted in good analytical precision. Preliminary results for melt inclusions from

  16. Brian Lassen - hea ja halva vahel / Kariina Tšursin

    Index Scriptorium Estoniae

    Tšursin, Kariina

    2014-01-01

    EMÜ Veterinaarmeditsiini ja Loomakasvatuse Instituudi vanemteadur Brian Lassen räägib oma tööst, põhimõtetest, kõrghariduse ja ülikooli sisust ja olemusest, oma eesmärkidest idamaiste võitluskunstide kõrgeima astme treenerina Baltimaades

  17. Chemical Analysis of Reaction Rims on Olivine Crystals in Natural Samples of Black Dacite Using Energy-Dispersive X-Ray Spectroscopy, Lassen Peak, CA.

    Science.gov (United States)

    Graham, N. A.

    2014-12-01

    Lassen Volcanic Center is the southernmost volcanic region in the Cascade volcanic arc formed by the Cascadia Subduction Zone. Lassen Peak last erupted in 1915 in an arc related event producing a black dacite material containing xenocrystic olivine grains with apparent orthopyroxene reaction rims. The reaction rims on these olivine grains are believed to have formed by reactions that ensued from a mixing/mingling event that occurred prior to eruption between the admixed mafic andesitic magma and a silicic dacite host material. Natural samples of the 1915 black dacite from Lassen Peak, CA were prepared into 15 polished thin sections and carbon coated for analysis using a FEI Quanta 250 Scanning Electron Microscope (SEM) to identify and measure mineral textures and disequilibrium reaction rims. Observed mineralogical textures related to magma mixing include biotite and amphibole grains with apparent dehydration/breakdown rims, pyroxene-rimmed quartz grains, high concentration of microlites in glass matrix, and pyroxene/amphibole reaction rims on olivine grains. Olivine dissolution is evidenced as increased iron concentration toward convolute edges of olivine grains as observed by Backscatter Electron (BSE) imagery and elemental mapping using NSS spectral imaging software. In an attempt to quantify the area of reaction rim growth on olivine grains within these samples, high-resolution BSE images of 30 different olivine grains were collected along with Energy-Dispersive X-Ray Spectroscopy (EDS) of different phases. Olivine cores and rims were extracted from BSE images using Photoshop and saved as separate image files. ImageJ software was used to calculate the area (μm2) of the core and rim of these grains. Average pyroxene reaction rim width for 30 grains was determined to be 11.68+/-1.65 μm. Rim widths of all 30 grains were averaged together to produce an overall average rim width for the Lassen Peak black dacite. By quantifying the reaction rims on olivine grains

  18. Phreatomagmatic and water-influenced Strombolian eruptions of a small-volume parasitic cone complex on the southern ringplain of Mt. Ruapehu, New Zealand: Facies architecture and eruption mechanisms of the Ohakune Volcanic Complex controlled by an unstable fissure eruption

    Science.gov (United States)

    Kósik, S.; Németh, K.; Kereszturi, G.; Procter, J. N.; Zellmer, G. F.; Geshi, N.

    2016-11-01

    The Ohakune Volcanic Complex is a late Pleistocene tuff ring - scoria/spatter cone complex located south of Ruapehu volcano. This small-volume volcano consists of an outer E-W elongated compound tuff ring edifice, three inner scoria-spatter cones and further volcanic depressions, located on the Ohakune Fault. We quantified accurately the variations of the eruptive styles and processes through time by systematic sampling of key stratigraphic marker beds at proximal and distal locations, and the determination of grain size distribution, componentry, density and vesicularity. Using a Digital Terrain Model coupled with stratigraphic data, we also determined the spatial distribution and volume of each identified unit and individual edifices within the Ohakune Volcanic Complex. Activity began with a shallow phreatomagmatic phase characterized by an almost continuous generation of a low eruptive column, accompanied by wet pyroclastic density currents, together with the ejection of juvenile fragments and accidental lithics from the surrounding country rocks. Subsequent activity was dominated by a variety of Strombolian eruptions exhibiting differing intensities that were at times disrupted by phreatic blasts or phreatomagmatic explosions due to the interaction with external water and/or sudden changes in magma discharge rate. At least three major vent-shifting events occurred during the eruption, which is demonstrated by the truncation of the initial tuff ring and the infilling of the truncated area by several coarse grained surge units. Our study indicates that approx. 12 × 106 m3 DRE magma erupted within maximum 2.5 to 5 months through multiple vents. The erupted magma ascended from a depth of 16-18 km, and reached the surface within approximately 50 h. Alternating eruption styles, frequent vent-shifting and a variety of emplacement mechanisms inferred from the deposits of the Ohakune Volcanic Complex demonstrate the unpredictable nature of small-volume volcanism

  19. Cone biopsy

    Science.gov (United States)

    ... biopsy; HSIL - cone biopsy; Low-grade cone biopsy; High-grade cone biopsy; Carcinoma in situ-cone biopsy; ... the cervix. In: Baggish MS, Karram MM, eds. Atlas of Pelvic Anatomy and Gynecologic Surgery . 4th ed. ...

  20. Inverse Dipolar Magnetic Anomaly Over the Volcanic Cone Linked to Reverse Polarity Magnetizations in Lavas and Tuffs - Implications for the Conduit System

    Science.gov (United States)

    Fucugauchi, J. U.; Perez-Cruz, L. L.; Trigo-Huesca, A.

    2012-12-01

    A combined magnetics and paleomagnetic study of Toluquilla monogenetic volcano and associated lavas and tuffs from Valsequillo basin in Central Mexico provides evidence on a magnetic link between lavas, ash tuffs and the underground volcanic conduit system. Paleomagnetic analyses show that lavas and ash tuffs carry reverse polarity magnetizations, which correlate with the inversely polarized dipolar magnetic anomaly over the volcano. The magnetizations in the lava and tuff show similar southward declinations and upward inclinations, supporting petrological inferences that the tuff was emplaced while still hot and indicating a temporal correlation for lava and tuff emplacement. Conduit geometry is one of the important controlling factors in eruptive dynamics of basaltic volcanoes. However volcanic conduits are often not, or only partly, exposed. Modeling of the dipolar anomaly gives a reverse polarity source magnetization associated with a vertical prismatic body with southward declination and upward inclination, which correlates with the reverse polarity magnetizations in the lava and tuff. The study documents a direct correlation of the paleomagnetic records with the underground magmatic conduit system of the monogenetic volcano. Time scale for cooling of the volcanic plumbing system involves a longer period than the one for the tuff and lava, suggesting that magnetization for the source of dipolar anomaly may represent a long time average as compared to the spot readings in the lava and tuff. The reverse polarity magnetizations in lava and tuff and in the underground source body for the magnetic anomaly are interpreted in terms of eruptive activity of Toluquilla volcano at about 1.3 Ma during the Matuyama reverse polarity C1r.2r chron.

  1. Re-Os isotopic systematics of primitive lavas from the Lassen region of the Cascade arc, California

    Science.gov (United States)

    Borg, L.E.; Brandon, A.D.; Clynne, M.A.; Walker, R.J.

    2000-01-01

    Rhenium-osmium isotopic systematics of primitive calc-alkaline lavas from the Lassen region appear to be controlled by mantle wedge processes. Lavas with a large proportion of slab component have relatively low Re and Os abundances, and have radiogenic Os and mid ocean ridge basalt-like Sr and Pb isotopic compositions. Lavas with a small proportion of slab component have higher Re and Os elemental abundances and display mantle-like Os, Sr, Nd, and Pb isotopic compositions. Assimilation with fractional crystallization can only generate the Re-Os systematics of the Lassen lavas from a common parent if the distribution coefficient for Re in sulfide is ~40-1100 times higher than most published estimates and if most incompatible element abundances decrease during differentiation. High Re/Os ratios in mid ocean ridge basalts makes subducted oceanic crust a potential source of radiogenic Os in volcanic arcs. The slab beneath the southernmost Cascades is estimated to have 187Os/188Os ratios as high as 1.4. Mixing between a slab component and mantle wedge peridotite can generate the Os isotopic systematics of the Lassen lavas provided the slab component has a Sr/Os ratio of ~7.5X105 and Os abundances that are 100-600 times higher than mid ocean ridge basalts. For this model to be correct, Os must be readily mobilized and concentrated in the slab component, perhaps as a result of high water and HCl fugacities in this subduction environment. Another possible mechanism to account for the correlation between the magnitude of the subduction geochemical signature and Os isotopic composition involves increasing the stability of an Os-bearing phase in mantle wedge peridotites as a result of fluxing with the slab component. Melting of such a source could yield low Os magmas that are more susceptible to crustal contamination, and hence have more radiogenic Os isotopic compositions, than magmas derived from sources with a smaller contribution from the slab. Thus, the addition of the

  2. Geomorphological Approach for Regional Zoning In The Merapi Volcanic Area

    Directory of Open Access Journals (Sweden)

    Langgeng Wahyu Santosa

    2013-07-01

    Full Text Available Geomorphologial approach can be used as the basic for identifying and analyzing the natural resources potentials, especially in volcanic landscape. Based on its geomorphology, Merapi volcanic landscape can be divided into 5 morphological units, i.e.: volcanic cone, volcanic slope, volcanic foot, volcanic foot plain, and fluvio-volcanic plain. Each of these morphological units has specific characteristic and natural resources potential. Based on the condition of geomorphology, the regional zoning can be compiled to support the land use planning and to maintain the conservation of environmental function in the Merapi Volcanic area.

  3. 76 FR 23337 - Warner Valley Comprehensive Site Plan/Environmental Impact Statement, Lassen Volcanic National...

    Science.gov (United States)

    2011-04-26

    ... practical the NPS will begin to implement the first phase of restoration work identified in the CSP, including incrementional lowering and removal of Dream Lake Dam, rehabilitation of drainage ditches in...

  4. Volcanic rocks of the eastern and northern parts of the San Francisco volcanic field, Arizona

    Science.gov (United States)

    Moore, Richard B.; Wolfe, Edward W.; Ulrich, George E.

    1976-01-01

    The eastern and northern parts of the San Francisco volcanic field, between San Francisco Mountain and the Little Colorado River, contain about 175 cinder cones, many with one or more associated lava flows, and one center of silicic volcanism, O'Leary Peak. Basaltic flows and cones are divided into five groups, primarily on the bases of stratigraphic and physiographic relations, degree of weathering and erosion, K-Ar and tree-ring age determinations, and, in part, chemical and petrographic data:

  5. California's Vulnerability to Volcanic Hazards: What's at Risk?

    Science.gov (United States)

    Mangan, M.; Wood, N. J.; Dinitz, L.

    2015-12-01

    California is a leader in comprehensive planning for devastating earthquakes, landslides, floods, and tsunamis. Far less attention, however, has focused on the potentially devastating impact of volcanic eruptions, despite the fact that they occur in the State about as frequently as the largest earthquakes on the San Andreas Fault Zone. At least 10 eruptions have occurred in the past 1,000 years—most recently in northern California (Lassen Peak 1914 to 1917)—and future volcanic eruptions are inevitable. The likelihood of renewed volcanism in California is about one in a few hundred to one in a few thousand annually. Eight young volcanoes, ranked as Moderate to Very High Threat [1] are dispersed throughout the State. Partially molten rock (magma) resides beneath at least seven of these—Medicine Lake Volcano, Mount Shasta, Lassen Volcanic Center, Clear Lake Volcanic Field, Long Valley Volcanic Region, Coso Volcanic Field, and Salton Buttes— causing earthquakes, toxic gas emissions, hydrothermal activity, and (or) ground deformation. Understanding the hazards and identifying what is at risk are the first steps in building community resilience to volcanic disasters. This study, prepared in collaboration with the State of California Governor's Office of Emergency Management and the California Geological Survey, provides a broad perspective on the State's exposure to volcano hazards by integrating mapped volcano hazard zones with geospatial data on at-risk populations, infrastructure, and resources. The study reveals that ~ 16 million acres fall within California's volcano hazard zones, along with ~ 190 thousand permanent and 22 million transitory populations. Additionally, far-field disruption to key water delivery systems, agriculture, utilities, and air traffic is likely. Further site- and sector-specific analyses will lead to improved hazard mitigation efforts and more effective disaster response and recovery. [1] "Volcanic Threat and Monitoring Capabilities

  6. Geology and petrology of the Vulsinian volcanic area (Latium, Italy)

    NARCIS (Netherlands)

    Varekamp, J.C.

    1979-01-01

    The Vulsinian volcanic area is situated in Latium, west central Italy. This quarternary volcanic complex consists of a series of layered tuffs, lava flows, ignimbrites, and many small cinder and ash cones. A steep central edifice is lacking due to the relatively large amount of pyroclastic deposits.

  7. Amazonian volcanism inside Valles Marineris on Mars

    Czech Academy of Sciences Publication Activity Database

    Brož, Petr; Hauber, E.; Wray, J. J.; Michael, G.

    2017-01-01

    Roč. 473, September (2017), s. 122-130 ISSN 0012-821X Institutional support: RVO:67985530 Keywords : Mars * Valles Marineris * volcanism * scoria cone * hydrothermal activity Subject RIV: DC - Siesmology, Volcanology, Earth Structure OBOR OECD: Volcanology Impact factor: 4.409, year: 2016

  8. Cinder cones of Mount Slamet, Central Java, Indonesia

    Directory of Open Access Journals (Sweden)

    Igan S. SutawIdjaja

    2014-06-01

    Full Text Available http://dx.doi.org/10.17014/ijog.vol4no1.20096The Mount Slamet volcanic field in Central Java, Indonesia, contains thirty five cinder cones within an area of 90 sq. km in the east flank of the volcano. The cinder cones occur singly or in small groups, with diameter of the base ranges from 130 - 750 m and the height is around 250 m. Within the volcanic field, the cinder cones are spread over the volcanic area at the distance of 4 to 14 km from the eruption center of the Slamet Volcano. They are concentrated within latitudes 7°11’00” - 7°16’00” S,, and longitudes 109°15’00” - 109°18’00” E. The density of the cinder cones is about 1.5 cones/km2. Most of the cinder cones lie on the Tertiary sedimentary rocks along the NW-trending fault system and on radial fractures. The structural pattern may be related to the radial faults in this region. The cone surfaces are commonly blanketed by Slamet air-falls and lava flows. The deposits consist of poorly bedded, very coarse-grained, occasionally overlain by oxidized scoria, and large-sized of ballistic bombs and blocks. There are various kind of volcanic bombs originating from scoriae ballistic rock fragments. The other kind of volcanic bombs are breadcrust bomb, almond seed or contorted shape. All of the cinder cones have undergone degradation, which can be observed from the characters of gully density and surface morphology. By using Porter parameters, Hco is equal to 0.25 Wco, whilst Wcr is equal to 0.40 Wco. The Hco/Wco ratio is higher than Hco = 0.2 Wco reference line. A radiometric dating using K-Ar method carried out on a scoria bomb yields the age of 0.042 + 0.020 Ma.  

  9. Preliminary geologic map of the Sleeping Butte volcanic centers

    International Nuclear Information System (INIS)

    Crowe, B.M.; Perry, F.V.

    1991-07-01

    The Sleeping Butte volcanic centers comprise two, spatially separate, small-volume ( 3 ) basaltic centers. The centers were formed by mildly explosive Strombolian eruptions. The Little Black Peak cone consists of a main scoria cone, two small satellitic scoria mounds, and associated lobate lava flows that vented from sites at the base of the scoria cone. The Hidden Cone center consists of a main scoria cone that developed on the north-facing slope of Sleeping Butte. The center formed during two episodes. The first included the formation of the main scoria cone, and venting of aa lava flows from radial dikes at the northeast base of the cone. The second included eruption of scoria-fall deposits from the summit crater. The ages of the Little Black Peak and the Hidden Cone are estimated to be between 200 to 400 ka based on the whole-rock K-Ar age determinations with large analytical undertainty. This age assignment is consistent with qualitative observations of the degree of soil development and geomorphic degradation of volcanic landforms. The younger episode of the Hidden Cone is inferred to be significantly younger and probably of Late Pleistocene or Holocene age. This is based on the absence of cone slope rilling, the absence of cone-slope apron deposits, and erosional unconformity between the two episodes, the poor horizon- development of soils, and the presence of fall deposits on modern alluvial surfaces. Paleomagnetic data show that the centers record similar but not identical directions of remanent magnetization. Paleomagnetic data have not been obtained for the youngest deposits of the Hidden Cone center. Further geochronology, soils, geomorphic, and petrology studies are planned of the Sleeping Butte volcanic centers 20 refs., 3 figs

  10. Hydrovolcanic tuff rings and cones as indicators for phreatomagmatic explosive eruptions on Mars

    Czech Academy of Sciences Publication Activity Database

    Brož, Petr; Hauber, E.

    2013-01-01

    Roč. 118, č. 8 (2013), s. 1656-1675 ISSN 2169-9097 Institutional support: RVO:67985530 Keywords : Mars surface * volcanism * pyroclastic cone Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 3.440, year: 2013

  11. Monogenetic volcanism: personal views and discussion

    Science.gov (United States)

    Németh, K.; Kereszturi, G.

    2015-11-01

    Monogenetic volcanism produces small-volume volcanoes with a wide range of eruptive styles, lithological features and geomorphic architectures. They are classified as spatter cones, scoria (or cinder) cones, tuff rings, maars (maar-diatremes) and tuff cones based on the magma/water ratio, dominant eruption styles and their typical surface morphotypes. The common interplay between internal, such as the physical-chemical characteristics of magma, and external parameters, such as groundwater flow, substrate characteristics or topography, plays an important role in creating small-volume volcanoes with diverse architectures, which can give the impression of complexity and of similarities to large-volume polygenetic volcanoes. In spite of this volcanic facies complexity, we defend the term "monogenetic volcano" and highlight the term's value, especially to express volcano morphotypes. This study defines a monogenetic volcano, a volcanic edifice with a small cumulative volume (typically ≤1 km3) that has been built up by one continuous, or many discontinuous, small eruptions fed from one or multiple magma batches. This definition provides a reasonable explanation of the recently recognized chemical diversities of this type of volcanism.

  12. Identification of environmental issues: Hybrid wood-geothermal power plant, Wendel-Amedee KGRA, Lassen County, California: First phase report

    Energy Technology Data Exchange (ETDEWEB)

    1981-08-14

    The development of a 55 MWe power plant in Lassen County, California, has been proposed. The proposed power plant is unique in that it will utilize goethermal heat and wood fuel to generate electrical power. This report identifies environmental issues and constraints which may impact the proposed hybrid wood-geothermal power plant. (ACR)

  13. Volcanic gas

    Science.gov (United States)

    McGee, Kenneth A.; Gerlach, Terrance M.

    1995-01-01

    In Roman mythology, Vulcan, the god of fire, was said to have made tools and weapons for the other gods in his workshop at Olympus. Throughout history, volcanoes have frequently been identified with Vulcan and other mythological figures. Scientists now know that the “smoke" from volcanoes, once attributed by poets to be from Vulcan’s forge, is actually volcanic gas naturally released from both active and many inactive volcanoes. The molten rock, or magma, that lies beneath volcanoes and fuels eruptions, contains abundant gases that are released to the surface before, during, and after eruptions. These gases range from relatively benign low-temperature steam to thick hot clouds of choking sulfurous fume jetting from the earth. Water vapor is typically the most abundant volcanic gas, followed by carbon dioxide and sulfur dioxide. Other volcanic gases are hydrogen sulfide, hydrochloric acid, hydrogen, carbon monoxide, hydrofluoric acid, and other trace gases and volatile metals. The concentrations of these gas species can vary considerably from one volcano to the next.

  14. Scoria cones on Mars: detailed investigation of morphometry based on high - resolution Digital Elevation Models

    Czech Academy of Sciences Publication Activity Database

    Brož, Petr; Čadek, O.; Hauber, E.; Rossi, A. P.

    2015-01-01

    Roč. 120, č. 9 (2015), s. 1512-1527 ISSN 2169-9097 Institutional support: RVO:67985530 Keywords : Mars surface * volcanism * pyroclastic cone * scoria cone Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 3.440, year: 2013

  15. Economic study of low temperature geothermal energy in Lassen and Modoc Counties, California

    Energy Technology Data Exchange (ETDEWEB)

    1977-04-01

    The feasibility of using low cost, low temperature geothermal energy in job-producing industries to increase employment and encourage economic development was investigated. The study, encompassing all of Lassen and Modoc Counties, was to be site-specific, referencing candidate geothermal applications to known hot wells and springs as previously determined, or to new wells with specific characteristics as defined in the Scope of Work. The emphasis was to be placed on economically practical and readily achievable applications from known resources. Although both positive and negative findings were found in specific areas of investigation, it is felt that the overall long term prognosis for geothermal energy stimulus to industry in the area is excellent. The applications studied were; greenhouse heating, kiln drying, onion dehydration, feedlots, and aquaculture.

  16. Quotient normed cones

    Indian Academy of Sciences (India)

    general setting of the space CL(X, Y ) of all continuous linear mappings from a normed cone (X, p) to a normed cone (Y, q), extending several well-known results related to open continuous linear mappings between normed linear spaces. Keywords. Normed cone; extended quasi-metric; continuous linear mapping; bicom-.

  17. Volcanic Catastrophes

    Science.gov (United States)

    Eichelberger, J. C.

    2003-12-01

    The big news from 20th century geophysics may not be plate tectonics but rather the surprise return of catastrophism, following its apparent 19th century defeat to uniformitarianism. Divine miracles and plagues had yielded to the logic of integrating observations of everyday change over time. Yet the brilliant interpretation of the Cretaceous-Tertiary Boundary iridium anomaly introduced an empirically based catastrophism. Undoubtedly, decades of contemplating our own nuclear self-destruction played a role in this. Concepts of nuclear winter, volcanic winter, and meteor impact winter are closely allied. And once the veil of threat of all-out nuclear exchange began to lift, we could begin to imagine slower routes to destruction as "global change". As a way to end our world, fire is a good one. Three-dimensional magma chambers do not have as severe a magnitude limitation as essentially two-dimensional faults. Thus, while we have experienced earthquakes that are as big as they get, we have not experienced volcanic eruptions nearly as great as those preserved in the geologic record. The range extends to events almost three orders of magnitude greater than any eruptions of the 20th century. Such a calamity now would at the very least bring society to a temporary halt globally, and cause death and destruction on a continental scale. At maximum, there is the possibility of hindering photosynthesis and threatening life more generally. It has even been speculated that the relative genetic homogeneity of humankind derives from an evolutionary "bottleneck" from near-extinction in a volcanic cataclysm. This is somewhat more palatable to contemplate than a return to a form of Original Sin, in which we arrived at homogeneity by a sort of "ethnic cleansing". Lacking a written record of truly great eruptions, our sense of human impact must necessarily be aided by archeological and anthropological investigations. For example, there is much to be learned about the influence of

  18. The Valle de Bravo Volcanic Field. A monogenetic field in the central front of the Mexican Volcanic Belt

    Science.gov (United States)

    Aguirre-Diaz, G. J.; Jaimes-Viera, M. D.; Nieto-Obreg¢n, J.; Lozano-Santacruz, R.

    2003-12-01

    The Valle de Bravo volcanic field, VBVF, is located in the central-southern front of the Mexican Volcanic Belt just to the southwest of Nevado de Toluca volcano. The VBVF covers 3,703 square Km and includes at least 122 cinder cones, 1 shield volcano, several domes, and the 2 volcanic complexes of Zitacuaro and Villa de Allende. Morphometric parameters calibrated with isotopic ages of the volcanic products indicate four groups or units for the VBVF, Pliocene domes and lava flows, undifferentiated Pleistocene lava flows,> 40 Ka cones and lavas, 40 to 25 Ka cones and lavas, 25 to 10 Ka cones and lavas, and < 10 Ka cones and lavas. Whole-rock chemistry shows that all products of the VBVF range from basaltic andesites to dacites. No basalts were found, in spite of many units are olivine-rich and large some with large weight percent contents of MgO, 1 to 9. There is the possibility that some or all of the olivines in some samples could be xenocrysts. Some andesites are high in Sr, 1000 to 1800 ppm, that correlates with relatively high values of Ba, Cr, Ni, Cu, CaO and MgO. Y and Nb have the typical low values for orogenic rocks. The only shield volcano of the VBVF has a base of 9 Km, and its composition is practically the average composition of the whole field. Stratigraphycally, it is one of the earlier events of the VBVF. Compared with other volcanic fields of the Mexican Volcanic Belt, it lacks basalts and alkalic rocks. All volcanism of this field is calcalkaline

  19. Cones and craters on Mount Pavagadh, Deccan Traps: Rootless ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    The mountain is surrounded by smaller hills, some of which apparently represent individ- ual satellite vents. Rhyolite outcrops, and volcanic breccia deposits with clear quaquaversal dips, are seen in these hills. Here we describe the shal- low cones with craters that are found on the uppermost mafic lava flow of Mount ...

  20. Volcanic features of Io

    Science.gov (United States)

    Carr, M.H.; Masursky, H.; Strom, R.G.; Terrile, R.J.

    1979-01-01

    Volcanic activity is apparently higher on Io than on any other body in the Solar System. Its volcanic landforms can be compared with features on Earth to indicate the type of volcanism present on Io. ?? 1979 Nature Publishing Group.

  1. Bornological Locally Convex Cones

    Directory of Open Access Journals (Sweden)

    Davood Ayaseh

    2014-10-01

    Full Text Available In this paper we define bornological and b-bornological cones and investigate their properties. We give some characterization for these cones. In the special case of locally convex topological vector space both these concepts reduce to the known concept  of bornological spaces. We introduce and investigate the  convex quasiuniform   structures U_{tau}, U_{sigma}(P,P* and \\U_{beta}(P,P* on locally convex cone (P,U.

  2. Economic study of low temperature geothermal energy in Lassen and Modoc counties, California

    Energy Technology Data Exchange (ETDEWEB)

    None

    1977-04-01

    The purpose of this study was to investigate the feasibility of using low cost, low temperature geothermal energy in job-producing industries to increase employment and encourage economic development. The study, encompassing all of Lassen and modoc Counties, was to be site-specific, referencing candidate geothermal applications to known hot wells and springs as previously determined, or to new wells with specific characteristics as defined in the Scope of Work. The emphasis was to be placed on economically practical and readily achievable applications from known resources, thus complimenting the recently completed ERDA-Susanville Study where a designated community was used as a ''laboratory'' in which land-use planning, institutional aspects, geological assessments, technical modeling and socioeconomic impacts were all examined in overview. During the course of the study, monthly progress reports were prepared and reviewed with the Commission so that emphasis on particular features of study could be changed as necessary to reflect updated findings and to redirect efforts into additional areas of potential promise as they became apparent. In this manner, a degree of flexibility was maintained which allowed a more comprehensive study than would have been otherwise possible. Although the report generates both positive and negative findings in specific areas of investigation, it is felt that the overall long term prognosis for geothermal energy stimulus to industry in the area is excellent.

  3. Chemical Analysis of Aerosols for Characterization of Long-Range Transport at Mt. Lassen, CA

    Science.gov (United States)

    Harada, Y.; Waddell, J. A.; Cliff, S. S.; Perry, K. D.; Kelly, P. B.

    2004-12-01

    Effective regional air pollution regulation requires an understanding of long-range aerosol transport and natural aerosol chemistry. Sample collection was performed at the Interagency Monitoring of Protected Visual Environments (IMPROVE) sampling site on Mt. Lassen in the Sierra Nevada range at 1755 m elevation. The site is in Northern California at Longitude 121° 34' 40", Latitude 40° 32' 25". Size segregated and time resolved aerosol samples were collected with an 8 DRUM sampler from April 15th to May 24th 2002 as part of the NOAA Intercontinental Transport and Chemical Transformation Experiment (ITCT). The samples were analyzed with Synchrotron X-Ray Fluorescence (S-XRF) and Time of Flight mass spectroscopy (TOFMS). The total aerosol concentration exhibits a clear daily cycling of total mass, due to a nighttime down-slope air circulation from the free troposphere. The sulfate peaked in concentration during the night. Elemental data is suggestive of dust transport from continental Asia. The micron size ranges were dominated by nitrate, while the sub-micron size ranges had high levels of sulfate. Chemical analysis shows oceanic influence through strong correlations between methyl sulfonic acid (MSA), iodine, and oxalate. The appearance of the oceanic biogenic tracers in the sub-micron fraction is most likely a result of vertical mixing over the Pacific Ocean. MSA follows a diurnal pattern similar to sulfate, however the differences suggest both an oceanic and continental source for sulfate. The carbon particulate signal did not show any diurnal pattern during the measurement period.

  4. Mafic inclusions in Yosemite granites and Lassen Pk lavas: records of complex crust-mantle interactions

    Energy Technology Data Exchange (ETDEWEB)

    Reid, J.B. Jr.; Flinn, J.E.

    1985-01-01

    This study compares three small-scale magmatic systems dominated by mafic/felsic interaction that appear to be analogs to the evolution of their larger host systems: mafic inclusions from modern Lassen Pk lavas along with inclusions and related synplutonic dike materials from granitoids in the Tuolumne Intrusive Series. Each system represents quickly chilled mafic melt previously contaminated by digestion of rewarmed, super-solidus felsic hosts. Contaminants occur in part as megacrysts of reworked oligoclase with lesser hb and biot. Within each group MgO-variation diagrams for Fe, Ca, Ti, Si are strikingly linear (r>.96); alkalis are decidedly less regular, and many hybrid rocks show a curious, pronounced Na enrichment. Field data, petrography, and best fit modeling suggests this may result from flow concentration of oligoclase xenocrysts within contaminated synplutonic dikes, and is preserved in the inclusions when dike cores chill as pillows in their felsic host. Dissolution of mafic inclusions erases these anomalies and creates a more regular series of two-component mafic-felsic mixtures in the large host system. The inclusions and dikes thus appear to record a variety of late-stage mafic-felsic interactive processes that earlier and on a larger scale created much of the compositional variety of their intermediate host rocks.

  5. Eruptive and Geomorphic Processes at the Lathrop Wells Scoria Cone

    Energy Technology Data Exchange (ETDEWEB)

    G. Valentine; D.J. Krier; F.V. Perry; G. Heiken

    2006-08-03

    The {approx}80 ka Lathrop Wells volcano (southern Nevada, U.S.A.) preserves evidence for a range of explosive processes and emplacement mechanisms of pyroclastic deposits and lava fields in a small-volume basaltic center. Early cone building by Strombolian bursts was accompanied by development of a fan-like lava field reaching {approx}800 m distance from the cone, built upon a gently sloping surface. Lava flows carried rafts of cone deposits, which provide indirect evidence for cone facies in lieu of direct exposures in the active quarry. Subsequent activity was of a violent Strombolian nature, with many episodes of sustained eruption columns up to a few km in height. These deposited layers of scoria lapilli and ash in different directions depending upon wind direction at the time of a given episode, reaching up to {approx}20 km from the vent, and also produced the bulk of the scoria cone. Lava effusion migrated from south to north around the eastern base of the cone as accumulation of lavas successively reversed the topography at the base of the cone. Late lavas were emplaced during violent Strombolian activity and continued for some time after explosive eruptions had waned. Volumes of the eruptive products are: fallout--0.07 km{sup 3}, scoria cone--0.02 km{sup 3}, and lavas--0.03 km{sup 3}. Shallow-derived xenolith concentrations suggest an upper bound on average conduit diameter of {approx}21 m in the uppermost 335 m beneath the volcano. The volcano was constructed over a period of at least seven months with cone building occurring only during part of that time, based upon analogy with historical eruptions. Post-eruptive geomorphic evolution varied for the three main surface types that were produced by volcanic activity: (1) scoria cone, (2) low relief surfaces (including lavas) with abundant pyroclastic material, and (3) lavas with little pyroclastic material. The role of these different initial textures must be accounted for in estimating relative ages of

  6. Eruptive and Geomorphic Processes at the Lathrop Wells Scoria Cone

    International Nuclear Information System (INIS)

    G. Valentine; D.J. Krier; F.V. Perry; G. Heiken

    2006-01-01

    The ∼80 ka Lathrop Wells volcano (southern Nevada, U.S.A.) preserves evidence for a range of explosive processes and emplacement mechanisms of pyroclastic deposits and lava fields in a small-volume basaltic center. Early cone building by Strombolian bursts was accompanied by development of a fan-like lava field reaching ∼800 m distance from the cone, built upon a gently sloping surface. Lava flows carried rafts of cone deposits, which provide indirect evidence for cone facies in lieu of direct exposures in the active quarry. Subsequent activity was of a violent Strombolian nature, with many episodes of sustained eruption columns up to a few km in height. These deposited layers of scoria lapilli and ash in different directions depending upon wind direction at the time of a given episode, reaching up to ∼20 km from the vent, and also produced the bulk of the scoria cone. Lava effusion migrated from south to north around the eastern base of the cone as accumulation of lavas successively reversed the topography at the base of the cone. Late lavas were emplaced during violent Strombolian activity and continued for some time after explosive eruptions had waned. Volumes of the eruptive products are: fallout--0.07 km 3 , scoria cone--0.02 km 3 , and lavas--0.03 km 3 . Shallow-derived xenolith concentrations suggest an upper bound on average conduit diameter of ∼21 m in the uppermost 335 m beneath the volcano. The volcano was constructed over a period of at least seven months with cone building occurring only during part of that time, based upon analogy with historical eruptions. Post-eruptive geomorphic evolution varied for the three main surface types that were produced by volcanic activity: (1) scoria cone, (2) low relief surfaces (including lavas) with abundant pyroclastic material, and (3) lavas with little pyroclastic material. The role of these different initial textures must be accounted for in estimating relative ages of volcanic surfaces, and failure to

  7. Chain on a cone

    Directory of Open Access Journals (Sweden)

    Zubelevich Oleg

    2017-11-01

    Full Text Available We consider a loop of a chain thrown like a lasso on a fixed right circular cone. The system is in the standard homogeneous gravity field. The axis of the cone is vertical. It is shown that under certain vertex angles chain’s loop has an oblique equilibrium.

  8. Quaternary basaltic volcanism in the Golden Trout Volcanic Field, southern Sierra Nevada, California

    Science.gov (United States)

    Browne, Brandon L.; Becerra, Raul; Campbell, Colin; Saleen, Phillip; Wille, Frank R.

    2017-09-01

    The Golden Trout Volcanic Field (GTVF) produced the only Quaternary eruptions of mafic magma within the southern Sierra Nevada block. Approximately 38 × 106 m3 of basalt, trachy-basalt, basaltic trachy-andesite, and basaltic andesite (50.1-56.1% SiO2, 1.1-1.9% K2O, and 5.4-9.1% MgO) was erupted from four vents within a 10 km2 portion of the GTVF, which also includes rhyolite domes that are not considered in this study. The vents include, from oldest to youngest: Little Whitney Cone, South Fork Cone, Tunnel Cone, and unglaciated Groundhog Cone. Little Whitney Cone is a 120 m-high pile of olivine-CPX-phyric scoria produced during a Strombolian-style eruption overlying two columnar jointed lava flows. Tunnel Cone formed through a Hawaiian-style eruption along a 400 m-long north-south trending fissure that excavated at least three 25-65 m-wide craters. Crater walls up to 12 m high are composed of plagioclase-olivine-phyric spatter-fed flows that dip radially away from the crater center and crumble to form Tunnel Cone's steep unconsolidated flanks. South Fork Cone is a 170 m-high pile of plagioclase-olivine-phyric scoria that formed during Strombolian to violent Strombolian eruptions. South Fork Cone overlies the South Fork Cone lava, a 9.5 km-long flow ( 12 × 106 km3) that reached the Kern River Canyon to the west. Scoria and airfall deposits originating from South Fork Cone are located up to 2 km from the vent. Groundhog Cone is a 140 m-tall cinder and spatter cone breached on the north flank by a 13 × 106 m3 lava flow that partially buried the South Fork Cone lava and extends 7.5 km west to Kern River Canyon. Incompatible trace element concentrations and ratios show vent-specific trends but are unsystematic when plotted in terms of all mafic GTVF vents, implying that GTVF basalts were derived from a lithospheric mantle source and ascended through thick granitic Sierra Nevada crust as discrete batches that underwent different degrees of crustal contamination

  9. Vredefort shatter cones revisited

    Science.gov (United States)

    Nicolaysen, L. O.; Reimold, W. U.

    1999-03-01

    Shatter cones have been described from a number of circular and polygonal structures worldwide, the origin of which has been alternatively ascribed to the impacts of large extraterrestrial projectiles or to catastrophic endogenic processes. Despite their association with enigmatic, catastrophic processes, the nature of shatter cones and the physics involved in their formation have not been comprehensively researched. Results of detailed field and laboratory studies of shatter cones from three areas in the collar of the Vredefort Dome in South Africa are presented. Vredefort shatter cones are directly related to a widely displayed fracture phenomenon, termed ``multiply striated joint sets (MSJS)''. MSJs are planar to curviplanar fractures occuring at spacings of shock event that affected horizontal strata.

  10. Cone penetrometer comparison testing.

    Science.gov (United States)

    2011-01-01

    A total of 61 cone penetration tests were performed at 14 sites in the state of Wisconsin. Data : reinforced conclusions from practice in Minnesota and previously performed test programs : related to the Marquette Interchange and Mitchell interchange...

  11. Quotient normed cones

    Indian Academy of Sciences (India)

    E-mail: o.valero@uib.es. MS received 16 December 2005. Abstract. Given a normed cone (X, p) and a subcone Y, we construct and study the quotient normed cone (X/Y, ˜p) generated by Y. In particular we characterize the bicompleteness of (X/Y, ˜p) in terms of the bicompleteness of (X, p), and prove that the dual quotient ...

  12. Visible and Near-Infrared Spectroscopy of Hephaestus Fossae Cratered Cones, Mars

    Science.gov (United States)

    Dapremont, A.; Wray, J. J.

    2017-12-01

    Hephaestus Fossae are a system of sub-parallel fractures on Mars (> 500 km long) interpreted as near-surface tensional cracks [1]. Images of the Martian surface from the High Resolution Imaging Science Experiment have revealed cratered cones within the Hephaestus Fossae region. A volcanic origin (cinder/tuff cones) has been proposed for these features based on morphometric measurements and fine-scale surface characteristics [2]. In an effort to further constrain the origin of these cones as the products of igneous or sedimentary volcanism, we use data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). We take advantage of CRISM's S (0.4 - 1.0 microns) and L (1.0 - 3.9 microns) detector wavelength ranges to investigate the presence or absence of spectral signatures consistent with previous identifications of igneous and mud volcanism products on Mars [3,4]. Hephaestus Fossae cratered cone rims exhibit a consistent nanophase ferric oxide signature. We also identify ferrous phases and 3-micron absorptions (attributed to fundamental vibrational stretch frequencies in H2O) on the crater rims of several cones. Mafic signatures on cratered cone rims support an igneous provenance for these features. The 3-micron absorptions are consistent with the presence of structurally bound or adsorbed water. Our CRISM observations are similar to those of small edifice features in Chryse Planitia, which were interpreted as mud volcanism products based on their enrichment of nanophase ferric minerals and 3-micron absorptions on summit crater rims [3]. Hydrothermal activity was invoked for a Coprates Chasma pitted cone (scoria/tuff cone) based on CRISM identification of partially dehydrated opaline silica, which we do not observe in Hephaestus Fossae [4]. Our spectral observations are more consistent with mud volcanism, but we do not definitively rule out an igneous volcanic origin for the cones in our study region. We demonstrate that VNIR spectroscopy is a valuable

  13. Structure of the Hat Creek graben region: Implications for the structure of the Hat Creek graben and transfer of right-lateral shear from the Walker Lane north of Lassen Peak, northern California, from gravity and magnetic anomalies

    Science.gov (United States)

    Langenheim, Victoria; Jachens, Robert C.; Clynne, Michael A.; Muffler, L. J. Patrick

    2016-01-01

    Interpretation of magnetic and new gravity data provides constraints on the geometry of the Hat Creek Fault, the amount of right-lateral offset in the area between Mt. Shasta and Lassen Peak, and confirmation of the influence of pre-existing structure on Quaternary faulting. Neogene volcanic rocks coincide with short-wavelength magnetic anomalies of both normal and reversed polarity, whereas a markedly smoother magnetic field occurs over the Klamath Mountains and its Paleogene cover. Although the magnetic field over the Neogene volcanic rocks is complex, the Hat Creek Fault, which is one of the most prominent normal faults in the region and forms the eastern margin of the Hat Creek Valley, is marked by the eastern edge of a north-trending magnetic and gravity high 20-30 km long. Modeling of these anomalies indicates that the fault is a steeply dipping (~75-85°) structure. The spatial relationship of the fault as modeled by the potential-field data, the youngest strand of the fault, and relocated seismicity suggests that deformation continues to step westward across the valley, consistent with a component of right-lateral slip in an extensional environment. Filtered aeromagnetic data highlight a concealed magnetic body of Mesozoic or older age north of Hat Creek Valley. The body’s northwest margin strikes northeast and is linear over a distance of ~40 km. Within the resolution of the aeromagnetic data (1-2 km), we discern no right-lateral offset of this body. Furthermore, Quaternary faults change strike or appear to end, as if to avoid this concealed magnetic body and to pass along its southeast edge, suggesting that pre-existing crustal structure influenced younger faulting, as previously proposed based on gravity data.

  14. Volcanic sulfur dioxide index and volcanic explosivity index inferred from eruptive volume of volcanoes in Jeju Island, Korea: application to volcanic hazard mitigation

    Science.gov (United States)

    Ko, Bokyun; Yun, Sung-Hyo

    2016-04-01

    Jeju Island located in the southwestern part of Korea Peninsula is a volcanic island composed of lavaflows, pyroclasts, and around 450 monogenetic volcanoes. The volcanic activity of the island commenced with phreatomagmatic eruptions under subaqueous condition ca. 1.8-2.0 Ma and lasted until ca. 1,000 year BP. For evaluating volcanic activity of the most recently erupted volcanoes with reported age, volcanic explosivity index (VEI) and volcanic sulfur dioxide index (VSI) of three volcanoes (Ilchulbong tuff cone, Songaksan tuff ring, and Biyangdo scoria cone) are inferred from their eruptive volumes. The quantity of eruptive materials such as tuff, lavaflow, scoria, and so on, is calculated using a model developed in Auckland Volcanic Field which has similar volcanic setting to the island. The eruptive volumes of them are 11,911,534 m3, 24,987,557 m3, and 9,652,025 m3, which correspond to VEI of 3, 3, and 2, respectively. According to the correlation between VEI and VSI, the average quantity of SO2 emission during an eruption with VEI of 3 is 2-8 × 103 kiloton considering that the island was formed under intraplate tectonic setting. Jeju Island was regarded as an extinct volcano, however, several studies have recently reported some volcanic eruption ages within 10,000 year BP owing to the development in age dating technique. Thus, the island is a dormant volcano potentially implying high probability to erupt again in the future. The volcanoes might have explosive eruptions (vulcanian to plinian) with the possibility that SO2 emitted by the eruption reaches stratosphere causing climate change due to backscattering incoming solar radiation, increase in cloud reflectivity, etc. Consequently, recommencement of volcanic eruption in the island is able to result in serious volcanic hazard and this study provides fundamental and important data for volcanic hazard mitigation of East Asia as well as the island. ACKNOWLEDGMENTS: This research was supported by a grant [MPSS

  15. Volcanic stratigraphy: A review

    Science.gov (United States)

    Martí, Joan; Groppelli, Gianluca; Brum da Silveira, Antonio

    2018-05-01

    Volcanic stratigraphy is a fundamental component of geological mapping in volcanic areas as it yields the basic criteria and essential data for identifying the spatial and temporal relationships between volcanic products and intra/inter-eruptive processes (earth-surface, tectonic and climatic), which in turn provides greater understanding of the geological evolution of a region. Establishing precise stratigraphic relationships in volcanic successions is not only essential for understanding the past behaviour of volcanoes and for predicting how they might behave in the future, but is also critical for establishing guidelines for exploring economic and energy resources associated with volcanic systems or for reconstructing the evolution of sedimentary basins in which volcanism has played a significant role. Like classical stratigraphy, volcanic stratigraphy should also be defined using a systematic methodology that can provide an organised and comprehensive description of the temporal and spatial evolution of volcanic terrain. This review explores different methods employed in studies of volcanic stratigraphy, examines four case studies that use differing stratigraphic approaches, and recommends methods for using systematic volcanic stratigraphy based on the application of the concepts of traditional stratigraphy but adapted to the needs of volcanological environment.

  16. Simulating the development of basaltic volcanic fields for long-term hazard assessment

    Science.gov (United States)

    Connor, C.; Connor, L.; Germa, A.; Richardson, J. A.; Molisee, D. D.

    2017-12-01

    An important application of lava flow simulation is to model topography and surface geology in volcanic terrains with the goal of improving hazard assessments. We use a lava flow simulator, MOLASSES, coupled with codes modeling vent distribution, tephra dispersion and erosion to simulate the development of the surface geology and topography of basaltic volcanic fields. The simulation workflow begins by modeling the potential distribution of vents as a stochastic process using kernel density estimation, informed by geophysical models of the crust. Scoria cone dimensions, lava flow volume and thickness are then used to model multi-vent structures, breached scoria cones, and spatter cones. Tephra2, a tephra dispersion simulator is used to model medial deposition of tephra. MOLASSES is a cellular automata code that forecasts the dimensions of lava flows erupted at a point source on a digital elevation model. Lava and tephra are accumulated to construct topography, updating digital elevation models of the terrain. This topography is modified by erosion using the diffusion-advection equation and variable diffusivity for tephra, spatter and lava. Output from the simulator shows how the map geology of volcanic fields depends on vent density, volume of eruptive products, and the recurrence rate of volcanic activity. The potential for vent burial, which potentially biases hazard models, depends strongly on these factors. The erosion of scoria cones with time depends on vent density, and the likelihood of the scoria cone being re-surfaced by tephra fallout from younger adjacent cones. Our results suggest that quantitative treatment of geologic maps of volcanic fields using computer simulation will improve our understanding of the development of these basaltic volcanic fields and long-term hazard models.

  17. Causes and consequences of inherited cone disorders

    NARCIS (Netherlands)

    Roosing, S.; Thiadens, A.A.H.J.; Hoyng, C.B.; Klaver, C.C.; Hollander, A.I. den; Cremers, F.P.M.

    2014-01-01

    Hereditary cone disorders (CDs) are characterized by defects of the cone photoreceptors or retinal pigment epithelium underlying the macula, and include achromatopsia (ACHM), cone dystrophy (COD), cone-rod dystrophy (CRD), color vision impairment, Stargardt disease (STGD) and other maculopathies.

  18. Amphibole Thermometry and a Comparison of Results from Plutonic and Volcanic Systems

    Science.gov (United States)

    Sherman, T. M.; Putirka, K. D.; De Los Reyes, A. M. A.; Ratschbacher, B. C.

    2015-12-01

    Recent work (Ridolfi and Renzulli 2014) shows that amphiboles can be used to infer magmatic temperatures, even without knowledge of co-existing liquids. Here, we apply this approach, using new calibrations, to investigate felsic-mafic magma interactions, in a volcanic (Lassen Volcanic Center, a Cascade volcano) and plutonic (the Jurassic Guadalupe Igneous Complex) system. Preliminary data suggest that volcanic processes, as might be expected, preserve higher temperatures than plutonic materials (on average, volcanic amphiboles recorded 907±57.3°C while plutonic amphiboles recorded 764±59.7°C). We also find that the average T of a given mineral grain decreases with increased mineral size such that those crystallized below 800°C sometimes reach sizes beyond ~1mm, while those near 900°C appear truncated to ~0.3mm. It is not clear if T is the only control on amphibole crystal growth; however, our results would imply that larger grains not only require more time to grow but require continued undercooling. Significant cooling or heating is also recorded in many volcanically- and plutonically-grown grains, which may reflect transitioning between magmas of different T and composition. Core-to-rim cooling trends (with a common T of drop of 80oC) likely represent mafic-to-felsic magma transitions, whereas core-to-rim heating of similar magnitudes indicate a felsic-mafic transition. Some grains, though, exhibit a constant T (in the range 700-900°C) from core to rim, which perhaps indicates some shielding from magma mixing processes. Amphiboles might thus provide a reliable record of the intensity of magma mingling and mixing experienced by any particular enclave. Interestingly, volcanically-derived amphiboles appear to mostly record cooling towards the rims, while their plutonic counterparts tend to experience heating. It would thus appear that at Lassen, amphiboles are unaffected by later mafic magma recharge, but at the GIC, the plutonic amphiboles are more likely to

  19. Silicate volcanism on Io

    Science.gov (United States)

    Carr, M. H.

    1986-03-01

    This paper is mainly concerned with the nature of volcanic eruptions on Io, taking into account questions regarding the presence of silicates or sulfur as principal component. Attention is given to the generation of silicate magma, the viscous dissipation in the melt zone, thermal anomalies at eruption sites, and Ionian volcanism. According to the information available about Io, it appears that its volcanism and hence its surface materials are dominantly silicic. Several percent of volatile materials such as sulfur, but also including sodium- and potassium-rich materials, may also be present. The volatile materials at the surface are continually vaporized and melted as a result of the high rates of silicate volcanism.

  20. Geologic map of the Simcoe Mountains Volcanic Field, main central segment, Yakama Nation, Washington

    Science.gov (United States)

    Hildreth, Wes; Fierstein, Judy

    2015-01-01

    Mountainous parts of the Yakama Nation lands in south-central Washington are mostly covered by basaltic lava flows and cinder cones that make up the Simcoe Mountains volcanic field. The accompanying geologic map of the central part of the volcanic field has been produced by the U.S. Geological Survey (USGS) on behalf of the Water Resources Program of the Yakama Nation. The volcanic terrain stretches continuously from Mount Adams eastward as far as Satus Pass and Mill Creek Guard Station. Most of the many hills and buttes are volcanic cones where cinders and spatter piled up around erupting vents while lava flows spread downslope. All of these small volcanoes are now extinct, and, even during their active lifetimes, most of them erupted for no more than a few years. On the Yakama Nation lands, the only large long-lived volcano capable of erupting again in the future is Mount Adams, on the western boundary.

  1. Shape of scoria cones on Mars: Insights from numerical modeling of ballistic pathways

    Czech Academy of Sciences Publication Activity Database

    Brož, Petr; Čadek, O.; Hauber, E.; Rossi, A. P.

    2014-01-01

    Roč. 406, November (2014), s. 14-23 ISSN 0012-821X Institutional support: RVO:67985530 Keywords : Mars * explosive volcanism * scoria cone * ballistic pathway Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 4.734, year: 2014

  2. Ejecta evolution during cone impact

    KAUST Repository

    Marston, Jeremy

    2014-07-07

    We present findings from an experimental investigation into the impact of solid cone-shaped bodies onto liquid pools. Using a variety of cone angles and liquid physical properties, we show that the ejecta formed during the impact exhibits self-similarity for all impact speeds for very low surface tension liquids, whilst for high-surface tension liquids similarity is only achieved at high impact speeds. We find that the ejecta tip can detach from the cone and that this phenomenon can be attributed to the air entrainment phenomenon. We analyse of a range of cone angles, including some ogive cones, and impact speeds in terms of the spatiotemporal evolution of the ejecta tip. Using superhydrophobic cones, we also examine the entry of cones which entrain an air layer.

  3. Volcanic ash: a hazard for aviation in Southeast Asia (Invited)

    Science.gov (United States)

    Whelley, P.; Newhall, C. G.

    2013-12-01

    There are more than 500 potentially active volcanoes in Southeast Asia. Ash from eruptions of Volcanic Explosivity Index 3 (VEI 3) and larger pose local hazards while eruptions of VEI 4 or greater could disrupt trade, travel, and daily life in large parts of the region. To better manage and understand the risk volcanic ash presents to Southeast Asia, this study quantifies the long-term probability of an eruption interfering with aviation in the region. Southeast Asian volcanoes are classified into 5 groups, using satellite data, by their morphology and, where known, their eruptive history. ';Laguna' type are fields of maars, cinder cones and spatter cones, named for the Laguna Volcanic Field, Philippines. ';Mayon' type volcanoes are open-vent (i.e., observably degassing), frequently active, steep sided stratocones with small summit craters, spatter ramparts, small pyroclastic fans (typically 5 km and surrounded by ignimbrite sheets (Toba Caldera, Indonesia; Tambora Volcano, Indonesia). In addition, silicic dome complexes that might potentially produce large caldera-forming eruptions are classified as Toba-Tambora type. The eruptive histories of most volcanoes in Southeast Asia are poorly constrained. Assuming that volcanoes with similar morphologies have had similar eruption histories, we use eruption histories of well-studied examples of each morphologic category as proxy histories for understudied volcanoes in the class. Results from this work are used to model volcanic ash contamination scenarios for the Southeast Asia. This new classification scheme can be applied globally for a variety of uses.

  4. Cone Algorithm of Spinning Vehicles under Dynamic Coning Environment

    Directory of Open Access Journals (Sweden)

    Shuang-biao Zhang

    2015-01-01

    Full Text Available Due to the fact that attitude error of vehicles has an intense trend of divergence when vehicles undergo worsening coning environment, in this paper, the model of dynamic coning environment is derived firstly. Then, through investigation of the effect on Euler attitude algorithm for the equivalency of traditional attitude algorithm, it is found that attitude error is actually the roll angle error including drifting error and oscillating error, which is induced directly by dynamic coning environment and further affects the pitch angle and yaw angle through transferring. Based on definition of the cone frame and cone attitude, a cone algorithm is proposed by rotation relationship to calculate cone attitude, and the relationship between cone attitude and Euler attitude of spinning vehicle is established. Through numerical simulations with different conditions of dynamic coning environment, it is shown that the induced error of Euler attitude fluctuates by the variation of precession and nutation, especially by that of nutation, and the oscillating frequency of roll angle error is twice that of pitch angle error and yaw angle error. In addition, the rotation angle is more competent to describe the spinning process of vehicles under coning environment than Euler angle gamma, and the real pitch angle and yaw angle are calculated finally.

  5. Hydrothermal monitoring in a quiescent volcanic arc: Cascade Range, northwestern United States

    Science.gov (United States)

    Ingebritsen, S.E.; Randolph-Flagg, N. G.; Gelwick, K.D.; Lundstrom, E.A.; Crankshaw, I.M.; Murveit, A.M.; Schmidt, M.E.; Bergfeld, D.; Spicer, K.R.; Tucker, D.S.; Mariner, R.H.; Evans, William C.

    2014-01-01

    Ongoing (1996–present) volcanic unrest near South Sister, Oregon, is accompanied by a striking set of hydrothermal anomalies, including elevated temperatures, elevated major ion concentrations, and 3He/4He ratios as large as 8.6 RA in slightly thermal springs. These observations prompted the US Geological Survey to begin a systematic hydrothermal-monitoring effort encompassing 25 sites and 10 of the highest-risk volcanoes in the Cascade volcanic arc, from Mount Baker near the Canadian border to Lassen Peak in northern California. A concerted effort was made to develop hourly, multiyear records of temperature and/or hydrothermal solute flux, suitable for retrospective comparison with other continuous geophysical monitoring data. Targets included summit fumarole groups and springs/streams that show clear evidence of magmatic influence in the form of high 3He/4He ratios and/or anomalous fluxes of magmatic CO2 or heat. As of 2009–2012, summit fumarole temperatures in the Cascade Range were generally near or below the local pure water boiling point; the maximum observed superheat was 3 during periods of hourly record. Hydrothermal responses to these small seismic stimuli were generally undetectable or ambiguous. Evaluation of multiyear to multidecadal trends indicates that whereas the hydrothermal system at Mount St. Helens is still fast-evolving in response to the 1980–present eruptive cycle, there is no clear evidence of ongoing long-term trends in hydrothermal activity at other Cascade Range volcanoes that have been active or restless during the past century (Baker, South Sister, and Lassen). Experience gained during the Cascade Range hydrothermal-monitoring experiment informs ongoing efforts to capture entire unrest cycles at more active but generally less accessible volcanoes such as those in the Aleutian arc.

  6. Volcanic signals in oceans

    KAUST Repository

    Stenchikov, Georgiy L.

    2009-08-22

    Sulfate aerosols resulting from strong volcanic explosions last for 2–3 years in the lower stratosphere. Therefore it was traditionally believed that volcanic impacts produce mainly short-term, transient climate perturbations. However, the ocean integrates volcanic radiative cooling and responds over a wide range of time scales. The associated processes, especially ocean heat uptake, play a key role in ongoing climate change. However, they are not well constrained by observations, and attempts to simulate them in current climate models used for climate predictions yield a range of uncertainty. Volcanic impacts on the ocean provide an independent means of assessing these processes. This study focuses on quantification of the seasonal to multidecadal time scale response of the ocean to explosive volcanism. It employs the coupled climate model CM2.1, developed recently at the National Oceanic and Atmospheric Administration\\'s Geophysical Fluid Dynamics Laboratory, to simulate the response to the 1991 Pinatubo and the 1815 Tambora eruptions, which were the largest in the 20th and 19th centuries, respectively. The simulated climate perturbations compare well with available observations for the Pinatubo period. The stronger Tambora forcing produces responses with higher signal-to-noise ratio. Volcanic cooling tends to strengthen the Atlantic meridional overturning circulation. Sea ice extent appears to be sensitive to volcanic forcing, especially during the warm season. Because of the extremely long relaxation time of ocean subsurface temperature and sea level, the perturbations caused by the Tambora eruption could have lasted well into the 20th century.

  7. Light cone matrix product

    Energy Technology Data Exchange (ETDEWEB)

    Hastings, Matthew B [Los Alamos National Laboratory

    2009-01-01

    We show how to combine the light-cone and matrix product algorithms to simulate quantum systems far from equilibrium for long times. For the case of the XXZ spin chain at {Delta} = 0.5, we simulate to a time of {approx} 22.5. While part of the long simulation time is due to the use of the light-cone method, we also describe a modification of the infinite time-evolving bond decimation algorithm with improved numerical stability, and we describe how to incorporate symmetry into this algorithm. While statistical sampling error means that we are not yet able to make a definite statement, the behavior of the simulation at long times indicates the appearance of either 'revivals' in the order parameter as predicted by Hastings and Levitov (e-print arXiv:0806.4283) or of a distinct shoulder in the decay of the order parameter.

  8. Shatter cones: Diagnostic impact signatures

    Science.gov (United States)

    Mchone, J. F.; Dietz, R. S.

    1988-01-01

    Uniquely fractured target rocks known as shatter cones are associated with more than one half the world's 120 or so presently known impact structures. Shatter cones are a form of tensile rock failure in which a positive conical plug separates from a negative outer cup or mold and delicate ornaments radiating from an apex are preserved on surfaces of both portions. Although distinct, shatter cones are sometimes confused with other striated geologic features such as ventifacts, stylolites, cone-in-cone, slickensides, and artificial blast plumes. Complete cones or solitary cones are rare, occurrences are usually as swarms in thoroughly fractured rock. Shatter cones may form in a zone where an expanding shock wave propagating through a target decays to form an elastic wave. Near this transition zone, the expanding primary wave may strike a pebble or other inhomogeneity whose contrasting transmission properties produce a scattered secondary wave. Interference between primary and secondary scattered waves produce conical stress fields with axes perpendicular to the plane of an advancing shock front. This model supports mechanism capable of producing such shatter cone properties as orientation, apical clasts, lithic dependence, and shock pressure zonation. Although formational mechanics are still poorly understood, shatter cones have become the simplest geologic field criterion for recognizing astroblemes (ancient terrestrial impact structures).

  9. Shatter cones: Diagnostic impact signatures

    International Nuclear Information System (INIS)

    McHone, J.F.; Dietz, R.S.

    1988-01-01

    Uniquely fractured target rocks known as shatter cones are associated with more than one half the world's 120 or so presently known impact structures. Shatter cones are a form of tensile rock failure in which a positive conical plug separates from a negative outer cup or mold and delicate ornaments radiating from an apex are preserved on surfaces of both portions. Although distinct, shatter cones are sometimes confused with other striated geologic features such as ventifacts, stylolites, cone-in-cone, slickensides, and artificial blast plumes. Complete cones or solitary cones are rare, occurrences are usually as swarms in thoroughly fractured rock. Shatter cones may form in a zone where an expanding shock wave propagating through a target decays to form an elastic wave. Near this transition zone, the expanding primary wave may strike a pebble or other inhomogeneity whose contrasting transmission properties produce a scattered secondary wave. Interference between primary and secondary scattered waves produce conical stress fields with axes perpendicular to the plane of an advancing shock front. This model supports mechanism capable of producing such shatter cone properties as orientation, apical clasts, lithic dependence, and shock pressure zonation. Although formational mechanics are still poorly understood, shatter cones have become the simplest geologic field criterion for recognizing astroblemes (ancient terrestrial impact structures)

  10. Light cone thermodynamics

    Science.gov (United States)

    De Lorenzo, Tommaso; Perez, Alejandro

    2018-02-01

    We show that null surfaces defined by the outgoing and infalling wave fronts emanating from and arriving at a sphere in Minkowski spacetime have thermodynamical properties that are in strict formal correspondence with those of black hole horizons in curved spacetimes. Such null surfaces, made of pieces of light cones, are bifurcate conformal Killing horizons for suitable conformally stationary observers. They can be extremal and nonextremal depending on the radius of the shining sphere. Such conformal Killing horizons have a constant light cone (conformal) temperature, given by the standard expression in terms of the generalization of surface gravity for conformal Killing horizons. Exchanges of conformally invariant energy across the horizon are described by a first law where entropy changes are given by 1 /(4 ℓp2) of the changes of a geometric quantity with the meaning of horizon area in a suitable conformal frame. These conformal horizons satisfy the zeroth to the third laws of thermodynamics in an appropriate way. In the extremal case they become light cones associated with a single event; these have vanishing temperature as well as vanishing entropy.

  11. Explosive Volcanic Activity at Extreme Depths: Evidence from the Charles Darwin Volcanic Field, Cape Verdes

    Science.gov (United States)

    Kwasnitschka, T.; Devey, C. W.; Hansteen, T. H.; Freundt, A.; Kutterolf, S.

    2013-12-01

    Volcanic eruptions on the deep sea floor have traditionally been assumed to be non-explosive as the high-pressure environment should greatly inhibit steam-driven explosions. Nevertheless, occasional evidence both from (generally slow-) spreading axes and intraplate seamounts has hinted at explosive activity at large water depths. Here we present evidence from a submarine field of volcanic cones and pit craters called Charles Darwin Volcanic Field located at about 3600 m depth on the lower southwestern slope of the Cape Verdean Island of Santo Antão. We examined two of these submarine volcanic edifices (Tambor and Kolá), each featuring a pit crater of 1 km diameter, using photogrammetric reconstructions derived from ROV-based imaging followed by 3D quantification using a novel remote sensing workflow, aided by sampling. The measured and calculated parameters of physical volcanology derived from the 3D model allow us, for the first time, to make quantitative statements about volcanic processes on the deep seafloor similar to those generated from land-based field observations. Tambor cone, which is 2500 m wide and 250 m high, consists of dense, probably monogenetic medium to coarse-grained volcaniclastic and pyroclastic rocks that are highly fragmented, probably as a result of thermal and viscous granulation upon contact with seawater during several consecutive cycles of activity. Tangential joints in the outcrops indicate subsidence of the crater floor after primary emplacement. Kolá crater, which is 1000 m wide and 160 m deep, appears to have been excavated in the surrounding seafloor and shows stepwise sagging features interpreted as ring fractures on the inner flanks. Lithologically, it is made up of a complicated succession of highly fragmented deposits, including spheroidal juvenile lapilli, likely formed by spray granulation. It resembles a maar-type deposit found on land. The eruption apparently entrained blocks of MORB-type gabbroic country rocks with

  12. Volcanic Rocks and Features

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Volcanoes have contributed significantly to the formation of the surface of our planet. Volcanism produced the crust we live on and most of the air we breathe. The...

  13. Cone rod dystrophies

    Directory of Open Access Journals (Sweden)

    Hamel Christian P

    2007-02-01

    Full Text Available Abstract Cone rod dystrophies (CRDs (prevalence 1/40,000 are inherited retinal dystrophies that belong to the group of pigmentary retinopathies. CRDs are characterized by retinal pigment deposits visible on fundus examination, predominantly localized to the macular region. In contrast to typical retinitis pigmentosa (RP, also called the rod cone dystrophies (RCDs resulting from the primary loss in rod photoreceptors and later followed by the secondary loss in cone photoreceptors, CRDs reflect the opposite sequence of events. CRD is characterized by primary cone involvement, or, sometimes, by concomitant loss of both cones and rods that explains the predominant symptoms of CRDs: decreased visual acuity, color vision defects, photoaversion and decreased sensitivity in the central visual field, later followed by progressive loss in peripheral vision and night blindness. The clinical course of CRDs is generally more severe and rapid than that of RCDs, leading to earlier legal blindness and disability. At end stage, however, CRDs do not differ from RCDs. CRDs are most frequently non syndromic, but they may also be part of several syndromes, such as Bardet Biedl syndrome and Spinocerebellar Ataxia Type 7 (SCA7. Non syndromic CRDs are genetically heterogeneous (ten cloned genes and three loci have been identified so far. The four major causative genes involved in the pathogenesis of CRDs are ABCA4 (which causes Stargardt disease and also 30 to 60% of autosomal recessive CRDs, CRX and GUCY2D (which are responsible for many reported cases of autosomal dominant CRDs, and RPGR (which causes about 2/3 of X-linked RP and also an undetermined percentage of X-linked CRDs. It is likely that highly deleterious mutations in genes that otherwise cause RP or macular dystrophy may also lead to CRDs. The diagnosis of CRDs is based on clinical history, fundus examination and electroretinogram. Molecular diagnosis can be made for some genes, genetic counseling is

  14. Martian volcanism: A review

    International Nuclear Information System (INIS)

    Carr, M.H.

    1987-01-01

    Martian volcanism is reviewed. It is emphasized that lava plains constitute the major type of effusive flow, and can be differentiated by morphologic characteristics. Shield volcanoes, domes, and patera constitute the major constructional landforms, and recent work has suggested that explosive activity and resulting pyroclastic deposits may have been involved with formation of some of the small shields. Analysis of morphology, presumed composition, and spectroscopic data all indicate that Martian volcanism was dominantly basaltic in composition

  15. Mouse models for cone degeneration.

    Science.gov (United States)

    Samardzija, Marijana; Grimm, Christian

    2014-01-01

    Loss of cone vision has devastating effects on everyday life. Even though much effort has been made to understand cone physiology and pathophysiology, no successful therapies are available for patients suffering from cone disorders. As complex retinal interactions cannot be studied in vitro, utilization of different animal models is inevitable. Due to recent advances in transgenesis, mice became the most popular animal model to study human diseases, also in ophthalmology. While there are similarities in retinal anatomy and pathophysiology between mice and humans, there are also differences, most importantly the lack of a cone-rich macula in mice. Instead, cones in mice are rare and distributed over the whole retina, which makes the analysis of cone pathophysiology very difficult in these animals. This hindrance is one of the reasons why our understanding of rod pathophysiological processes is much more advanced. Recently, however, the sparseness of cones was overcome by the generation of the Nrl (- / -) mouse that expresses only cone photoreceptors in the retina. This paper will give a brief overview of some of the known mouse models to study cone degeneration and discuss the current knowledge gained from the analysis of these models.

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

    Science.gov (United States)

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

    1993-01-01

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

  17. Null cone superspace supergravity

    International Nuclear Information System (INIS)

    Downes-Martin, S.G.

    1980-03-01

    The null cone formalism is used to derive a 2(N-1) parameter family of constraints for O(N) extended superspace supergravity. The invariance groups of these constraints is analysed and is found to be [subgroup U submanifold] contains GL(4,R) for N = 1, the submanifold being eliminated for N > 1. The invariance group defines non-Weyl rotations on the superbein which combine to form Weyl transformations on the supertangent space metric. The invariance of the supergravity Lagrangian under these transformations is discussed. (Auth.)

  18. Volcanic hazards to airports

    Science.gov (United States)

    Guffanti, M.; Mayberry, G.C.; Casadevall, T.J.; Wunderman, R.

    2009-01-01

    Volcanic activity has caused significant hazards to numerous airports worldwide, with local to far-ranging effects on travelers and commerce. Analysis of a new compilation of incidents of airports impacted by volcanic activity from 1944 through 2006 reveals that, at a minimum, 101 airports in 28 countries were affected on 171 occasions by eruptions at 46 volcanoes. Since 1980, five airports per year on average have been affected by volcanic activity, which indicates that volcanic hazards to airports are not rare on a worldwide basis. The main hazard to airports is ashfall, with accumulations of only a few millimeters sufficient to force temporary closures of some airports. A substantial portion of incidents has been caused by ash in airspace in the vicinity of airports, without accumulation of ash on the ground. On a few occasions, airports have been impacted by hazards other than ash (pyroclastic flow, lava flow, gas emission, and phreatic explosion). Several airports have been affected repeatedly by volcanic hazards. Four airports have been affected the most often and likely will continue to be among the most vulnerable owing to continued nearby volcanic activity: Fontanarossa International Airport in Catania, Italy; Ted Stevens Anchorage International Airport in Alaska, USA; Mariscal Sucre International Airport in Quito, Ecuador; and Tokua Airport in Kokopo, Papua New Guinea. The USA has the most airports affected by volcanic activity (17) on the most occasions (33) and hosts the second highest number of volcanoes that have caused the disruptions (5, after Indonesia with 7). One-fifth of the affected airports are within 30 km of the source volcanoes, approximately half are located within 150 km of the source volcanoes, and about three-quarters are within 300 km; nearly one-fifth are located more than 500 km away from the source volcanoes. The volcanoes that have caused the most impacts are Soufriere Hills on the island of Montserrat in the British West Indies

  19. Volcanic Successions of the Jebal Remah Volcano, Northeast Jordan

    Directory of Open Access Journals (Sweden)

    AHMAD AL-MALABEH

    2010-06-01

    Full Text Available Jebal Remah volcano is one of huge but very poorly known tephra cones exposed on the basalt province of Harra El-Jabban. Detailed investigations indicate that this volcano is topographically distinct and structurally well-developed. It consists of voluminous air-fall scoria, arranged in three distinct horizons; namely lower black lapilli horizon, middle banded yellow horizon and upper brown blocky horizon. Each horizon consists of friable, loose and well bedded ejecta. Agglutination and lithification are limited to the upper horizon. A comparison among the volcanic successions of three horizons show different volcanic features that nevertheless retain a comparable overall character from one horizon to another. In spite of some similarity in the type of ejecta, actually these differ in total thickness, number of beds and internal stratification. This dissimilarity within volcanic successions of the volcano support the overall increase in fluidity, temperature and decrease in volatile content of the magma with the time. Thus, volcano shows a complete range of thermal facies. The studied volcano appears to have resulted from one prolonged eruptive phase. Its volcanic activity consisted of a series of discrete explosion intervals, separated by quiet periods. Field criteria indicate that the volcano is of strombolian type of volcanicity and resulted in a magmatic fragmentation mode.

  20. Review on resonance cone fields

    International Nuclear Information System (INIS)

    Ohnuma, Toshiro.

    1980-02-01

    Resonance cone fields and lower hybrid heating are reviewed in this report. The resonance cone fields were reported by Fisher and Gould, and they proposed the use of the measurement of resonance cones and structure as a diagnostic tool to determine the plasma density and electron temperature in magnetoplasma. After the resonance cone, a wave-like disturbance persists. Ohnuma et al. have measured bending, reflection and ducting of resonance cones in detail. The thermal modes in inhomogeneous magnetoplasma were seen. The reflection of thermal mode near an electron plasma frequency layer and an insulating plate has been observed. The non-linear effects of resonance cones is reported. Monochromatic electron beam produces the noise of broad band whistler mode. Lower hybrid waves have been the subject of propagation from the edge of plasma to the lower hybrid layer. Linear lower hybrid waves were studied. The lower hybrid and ion acoustic waves radiated from a point source were observed. The parametric decay of finite-extent, cold electron plasma waves was studied. The lower hybrid cone radiated from a point source going along magnetic field lines was observed. Several experimental data on the lower hybrid heating in tokamak devices have been reported. The theories on resonance cones and lower hybrid waves are introduced in this report. (Kato, T.)

  1. Making An Impact: Shatter Cones

    Science.gov (United States)

    Blank, Lisa M.; Plautz, Michael R.; Crews, Jeffrey W.

    2004-01-01

    In 1990, a group of geologists discovered a large number of shatter cones in southwestern Montana. Shatter cones are a type of metamorphosed rock often found in impact structures (the remains of a crater after a meteor impact and years of Earth activity). Scientists have discovered only 168 impact craters around the world. If rocks could talk,…

  2. The holographic entropy cone

    International Nuclear Information System (INIS)

    Bao, Ning; Nezami, Sepehr; Ooguri, Hirosi; Stoica, Bogdan; Sully, James; Walter, Michael

    2015-01-01

    We initiate a systematic enumeration and classification of entropy inequalities satisfied by the Ryu-Takayanagi formula for conformal field theory states with smooth holographic dual geometries. For 2, 3, and 4 regions, we prove that the strong subadditivity and the monogamy of mutual information give the complete set of inequalities. This is in contrast to the situation for generic quantum systems, where a complete set of entropy inequalities is not known for 4 or more regions. We also find an infinite new family of inequalities applicable to 5 or more regions. The set of all holographic entropy inequalities bounds the phase space of Ryu-Takayanagi entropies, defining the holographic entropy cone. We characterize this entropy cone by reducing geometries to minimal graph models that encode the possible cutting and gluing relations of minimal surfaces. We find that, for a fixed number of regions, there are only finitely many independent entropy inequalities. To establish new holographic entropy inequalities, we introduce a combinatorial proof technique that may also be of independent interest in Riemannian geometry and graph theory.

  3. Dynamics of turtle cones.

    Science.gov (United States)

    Naka, K I; Itoh, M A; Chappell, R L

    1987-02-01

    The response dynamics of turtle photoreceptors (cones) were studied by the cross-correlation method using a white-noise-modulated light stimulus. Incremental responses were characterized by the kernels. White-noise-evoked responses with a peak-to-peak excursion of greater than 5 mV were linear, with mean square errors of approximately 8%, a degree of linearity comparable to the horizontal cell responses. Both a spot (0.17 mm diam) and a large field of light produced almost identical kernels. The amplitudes of receptor kernels obtained at various mean irradiances fitted approximately the Weber-Fechner relationship and the mean levels controlled both the amplitude and the response dynamics; kernels were slow and monophasic at low mean irradiance and were fast and biphasic at high mean irradiance. This is a parametric change and is a piecewise linearization. Horizontal cell kernels evoked by the small spot of light were monophasic and slower than the receptor kernels produced by the same stimulus. Larger spots of light or a steady annular illumination transformed the slow horizontal cell kernel into a fast kernel similar to those of the receptors. The slowing down of the kernel waveform was modeled by a simple low-pass circuit and the presumed feedback from horizontal cells onto cones did not appear to play a major role.

  4. QCD on the light cone

    International Nuclear Information System (INIS)

    Brodsky, S.J.

    1992-09-01

    The quantization of gauge theory at fixed light-cone time τ = t - z/c provides new perspectives for solving non-perturbative problems in quantum chromodynamics. The light-cone Fock state expansion provides both a precise definition of the relativistic wavefunctions of hadrons as bound-states of quarks and gluons and a general calculus for predicting QCD processes at the amplitude level. Applications to exclusive processes and weak decay amplitudes are discussed. The problem of computing the hadronic spectrum and the corresponding light-cone wavefunctions of QCD in one space and one time dimension has been successfully reduced to the diagonalization of a discrete representation of the light-cone Hamiltonian. The problems confronting the solution of gauge theories in 3 + 1 dimensions in the light-cone quantization formalism,, including zero modes and non-perturbative renormalization, are reviewed

  5. Seasonality of volcanic eruptions

    Science.gov (United States)

    Mason, B.; Pyle, D.; Dade, B.; Jupp, T.

    2003-04-01

    An analysis of volcanic activity in the last three hundred years reveals that the frequency of onset of volcanic eruptions varies systematically with the time of year. We analysed the Smithsonian catalogue of more than 3200 subaerial eruptions recorded during the last 300 years. We also investigated continuous records, which are not part of the general catalogue, of individual explosions at Sakurajima volcano (Japan, 150 events per year since 1955) and Semeru (Indonesia, 100,000 events during the period 1997-2000). A higher proportion (as much as 18 percent of the average monthly rate) of eruptions occur worldwide between December and March. This observation is statistically significant at above the 99 percent level. This pattern is independent of the time interval considered, and emerges whether individual eruptions are counted with equal weight or with weights proportional to event explosivity. Elevated rates of eruption onset in boreal winter months are observed in northern and southern hemispheres alike, as well as in most volcanically-active regions including, most prominently, the 'Ring of Fire' surrounding the Pacific basin. Key contributors to this regional pattern include volcanoes in Central and South America, the volcanic provinces of the northwest Pacific rim, Indonesia and the southwest Pacific basin. On the smallest spatial scales, some individual volcanoes for which detailed histories exist exhibit peak levels in eruption activity during November-January. Seasonality is attributed to one or more mechanisms associated with the annual hydrological cycle, and may correspond to the smallest time-scale over which fluctuations in stress due to the redistribution of water-masses are felt by the Earth's crust. Our findings have important ramifications for volcanic risk assessment, and offer new insight into possible changes in volcanic activity during periods of long-term changes in global sea level.

  6. Seasonality of volcanic eruptions

    Science.gov (United States)

    Mason, B. G.; Pyle, D. M.; Dade, W. B.; Jupp, T.

    2004-04-01

    An analysis of volcanic activity during the last three hundred years reveals that volcanic eruptions exhibit seasonality to a statistically significant degree. This remarkable pattern is observed primarily along the Pacific "Ring of Fire" and locally at some individual volcanoes. Globally, seasonal fluctuations amount to 18% of the historical average monthly eruption rate. In some regions, seasonal fluctuations amount to as much as 50% of the average eruption rate. Seasonality principally reflects the temporal distribution of the smaller, dated eruptions (volcanic explosivity index of 0-2) that dominate the eruption catalog. We suggest that the pattern of seasonality correlates with the annual Earth surface deformation that accompanies the movement of surface water mass during the annual hydrological cycle and illustrate this with respect to global models of surface deformation and regional measurements of annual sea level change. For example, seasonal peaks in the eruption rate of volcanoes in Central America, the Alaskan Peninsula, and Kamchatka coincide with periods of falling regional sea level. In Melanesia, in contrast, peak numbers of volcanic eruptions occur during months of maximal regional sea level and falling regional atmospheric pressure. We suggest that the well-documented slow deformation of Earth's surface that accompanies the annual movements of water mass from oceans to continents acts to impose a fluctuating boundary condition on volcanoes, such that volcanic eruptions tend to be concentrated during periods of local or regional surface change rather than simply being distributed randomly throughout the year. Our findings have important ramifications for volcanic risk assessment and volcanoclimate feedback mechanisms.

  7. Volcanic activity and climatic changes.

    Science.gov (United States)

    Bryson, R A; Goodman, B M

    1980-03-07

    Radiocarbon dates of volcanic activity suggest variations that appear to be related to climatic changes. Historical eruption records also show variations on the scale of years to centuries. These records can be combined with simple climatic models to estimate the impact of various volcanic activity levels. From this analysis it appears that climatic prediction in the range of 2 years to many decades requires broad-scale volcanic activity prediction. Statistical analysis of the volcanic record suggests that some predictability is possible.

  8. Mud volcanism of South-Caspian depression

    International Nuclear Information System (INIS)

    Aliyev, A.A.

    2002-01-01

    Full text : South-Caspian depression is presented by area of large warping with thick (more than 25 km) sedimentary series and with wide development of mud volcanism. This depression is unique according to its number of mud volcanoes and intensity of their eruptions. There are about 400 mud volcanoes in this area, which is more than than a half of all volcanoes of the planet. Among them - 220 are continental, more 170 are marine, defined by different methods in the South-Caspian aquatorium. As a result of mudvolcanic activity islands, banks, shoals and underwater ridges are formed in marine conditions. Depths of underwater volcanoes vary from few meters to 900 m as the height of cones are different too. Marine mud volcanoes in geological history of Caspian sea evolution and in its recent history had and important significance. Activity of mud volcanoes in sea conditions lead to the formation of positive elements of relief. Products of ejection take part in the formation of microrelief of surrounding areas of sea bottom influence upon its dynamics and composition of bottom sediments. The carried out comparative analysis of mud volcanism manifestation both onshore and offshore showed the basic differences and similarities in morphology of volcanoes and geology-geochemical peculiarities of eruption products. New data on tectonics of mud volcanism development has been obtained over recent years. Mud volcanoes of South-Caspian depression are studied for assessment and oil-gas content of deep-seated deposits. Geochemical method of search of oil and gas deposits in mudvolcanic areas had been worked out.

  9. Modeling volcanic ash dispersal

    CERN Multimedia

    CERN. Geneva

    2010-01-01

    The assessment of volcanic fallout hazard is an important scientific, economic, and political issue, especially in densely populated areas. From a scientific point of view, considerable progress has been made during the last two decades through the use of increasingly powerful computational models and capabilities. Nowadays, models are used to quantify hazard...

  10. Cone and Seed Maturation of Southern Pines

    Science.gov (United States)

    James P. Barnett

    1976-01-01

    If slightly reduced yields and viability are acceptable, loblolly and slash cone collections can begin 2 to 3 weeks before maturity if the cones are stored before processing. Longleaf(P. palestris Mill.) pine cones should be collected only when mature, as storage decreased germination of seeds from immature cones. Biochemical analyses to determine reducing sugar...

  11. Origin and formation of neck in a basin landform: Examples from the Camargo volcanic field, Chihuahua (México)

    Science.gov (United States)

    Aranda-Gómez, José Jorge; Housh, Todd B.; Luhr, James F.; Noyola-Medrano, Cristina; Rojas-Beltrán, Marco Antonio

    2010-11-01

    The term "neck in a basin" (NIB) landform is proposed for volcanic structures characterized by nearly circular to elliptical open basins, located near the headwater of small streams or drainages, which contain small volcanic necks and/or erosion remnants of one (or more) cinder cones. NIB landforms are typically 400-1000 m in diameter and 30-100 m deep and are invariably surrounded by steep walls cut into one or more basaltic lava flows. NIB landforms lack evidence for a primary volcanogenic origin through either collapse or youthful eruptive activity. In the Pliocene portion (4 - 2 Ma) of the Plio-Quaternary Camargo volcanic field of Chihuahua (México), they are relatively numerous and are best developed at the margins of a gently sloping (3-5°) basaltic lava plateau and near major fault scarps. Mature NIB landforms have ring-like circular drainage patterns and central elevations marked by small volcanic necks and associated radial dikes intruded into basaltic scoria-fall and /or agglutinate deposits. We interpret NIB landforms to be erosional in origin. They develop where a cinder cone is surrounded by one or more sheet-like lava flows from one or more separate subsequent vents. Once eruptive activity ceases at the younger volcano(es), fluvial erosion gradually produces a ring-like drainage pattern along the contact between the lava and the older cinder cone. As a response to a marked contrast in resistance to erosion between lava flows and unconsolidated or poorly lithified pyroclastic deposits, the older cinder cone is preferentially eroded. In this manner, a ring-shaped, steep sided erosional basin, preformed by the scoria cone, is produced; eventually fluvial erosion exposes the central neck and dikes. The volume, relief, and age of the volcanic field are key factors in the formation and preservation of a NIB landform. They form in volcanic fields where lava emissions are sufficiently vigorous to engulf earlier cinder cones. Relief and associated high rates

  12. Evidence for explosive volcanic density currents on certain Martian volcanoes

    Science.gov (United States)

    Reimers, C. E.; Komar, P. D.

    1979-01-01

    The morphologies of certain of the smaller Martian volcanoes are discussed as possible results of explosive volcanic density currents. An examination of newly-photographed flank and caldera features of the Martian volcanoes Ceraunius Tholus, Uranius Tholus, Uranius Patera and Hecates Tholus, including steep slope angles, Krakatoa-type caldera morphologies, erosional features (radial channels and anastamosing gullies) and constructional features (blanketed flanks and possible lava deltas) reveals their similarity to terrestrial cones and composite volcanoes such as Barcena Volcano. Crater age data from the surface of Martian domes and shields indicates that such explosive activity occurred more frequently early in Martian geologic history, consistent with the view that the volcanic density currents were base surges rather than nuees ardentes, with the melting of permafrost supplying the water required in base surge generation.

  13. A submarine volcanic eruption leads to a novel microbial habitat.

    Science.gov (United States)

    Danovaro, Roberto; Canals, Miquel; Tangherlini, Michael; Dell'Anno, Antonio; Gambi, Cristina; Lastras, Galderic; Amblas, David; Sanchez-Vidal, Anna; Frigola, Jaime; Calafat, Antoni M; Pedrosa-Pàmies, Rut; Rivera, Jesus; Rayo, Xavier; Corinaldesi, Cinzia

    2017-04-24

    Submarine volcanic eruptions are major catastrophic events that allow investigation of the colonization mechanisms of newly formed seabed. We explored the seafloor after the eruption of the Tagoro submarine volcano off El Hierro Island, Canary Archipelago. Near the summit of the volcanic cone, at about 130 m depth, we found massive mats of long, white filaments that we named Venus's hair. Microscopic and molecular analyses revealed that these filaments are made of bacterial trichomes enveloped within a sheath and colonized by epibiotic bacteria. Metagenomic analyses of the filaments identified a new genus and species of the order Thiotrichales, Thiolava veneris. Venus's hair shows an unprecedented array of metabolic pathways, spanning from the exploitation of organic and inorganic carbon released by volcanic degassing to the uptake of sulfur and nitrogen compounds. This unique metabolic plasticity provides key competitive advantages for the colonization of the new habitat created by the submarine eruption. A specialized and highly diverse food web thrives on the complex three-dimensional habitat formed by these microorganisms, providing evidence that Venus's hair can drive the restart of biological systems after submarine volcanic eruptions.

  14. Geophysical characterization of circular structures in Chubut and Mendoza (Argentina): Impact vs. Volcanism

    Science.gov (United States)

    Prezzi, C.; Orgeira, M. J.; Risso, C.; Acevedo, R.; Ponce, F.; Nullo, F.; Martinez, O.; Rabassa, J.; Margonari, L.; Corbella, H.

    2013-05-01

    This work focuses on two main objectives. One of them is to provide information to discern the genesis of the circular structures present in Bajada del Diablo (Chubut, Argentina) considered as impact craters, and the other one is to contribute to a better knowledge of the circular structures located in the volcanic fields of Llancanelo and Payunia (Mendoza, Argentina). Chubut circular structures have been attributed to the collision of an extraterrestrial body, possibly an asteroid. However, doubts persist about their genesis because of the lack of direct geological evidences. Since detailed geomorphological studies have ruled out an origin by wind deflation, the prevailing alternative hypothesis attributes these circular structures to a volcanic process. On the other hand, the study of the volcanic fields of Payunia and Llancanelo (Mendoza) will contribute to the knowledge of the mechanics of hydromagmatic processes in the area, and the origin of circular structures morphologically similar to those located in Chubut. In the Payunia volcanic field at least 27 cones with evidences of hydromagmatism, in a field of more than 800 pure magmatic cones, have been recognized. This study tries to determine if a relationship between the observed volcanic circular structures and participation of water during the eruption exists. Magnetic and gravity field surveys of the circular volcanic structures in Llancanelo and Payunia volcanic fields were performed in order to determine their relationship with the type of eruption. Electromagnetic, magnetic and gravity field surveys were also carried out in Chubut circular structures. The comparative analysis of geological and geophysical results obtained in the circular structures of Chubut and those obtained in the circular structures in the volcanic areas of Llancanelo and Payunia suggest an impact origin for the circular structures of Chubut.

  15. Petrography and petrology of Quaternary volcanic rocks from Ghezel Ghaleh, northwest Qorveh

    OpenAIRE

    Alireza Bajelan; Morteza Sharifi

    2014-01-01

    Introduction In the east and northeast of Sanandaj in the Qorveh-Bijar-Takab axis, there are series of basaltic composition volcanoes with Quaternary age. The study area is part of the Sanandaj-Sirjan zone and is located between 47°52' and 47°57' E longitudes and 35°26 and '35°30' N latitudes. Due to the location of the volcanic cone on Pliocene clastic sediments and Quaternary travertine, the age of these volcanoes is considered to be Quaternary. The cones mostly consist of low scoria, as...

  16. Light cone approach

    International Nuclear Information System (INIS)

    Brodsky, Stan

    1993-01-01

    One of the most challenging problems in theoretical high energy physics is to compute the bound state structure of the proton and other hadrons from quantum chromodynamics (QCD), the field theory of quarks and gluons. The goal is not only to calculate the spectrum of hadrons masses from first principles, but also to derive the momentum and spin distributions of the quarks and gluons which control high energy hadron interactions. One approach to these difficult calculations is to simulate QCD on an artificial lattice. Recently, several new methods based on ''light-cone'' quantization have been proposed as alternatives to lattice theory for solving non-perturbative problems in QCD and other field theories. The basic idea is a generalization of Heisenberg's pioneer matrix formulation of quantum mechanics: if one could numerically diagonalize the matrix of the Hamiltonian representing the underlying QCD interaction, then the resulting eigenvalues would give the hadron spectrum, while the corresponding eigenstates would describe each hadron in terms of its quark and gluon degrees of freedom

  17. Volcanic eruptions on Io

    Science.gov (United States)

    Strom, R. G.; Schneider, N. M.; Terrile, R. J.; Cook, A. F.; Hansen, C.

    1981-09-01

    Nine eruption plumes which were observed during the Voyager 1 encounter with Io are discussed. During the Voyager 2 encounter, four months later, eight of the eruptions were still active although the largest became inactive sometime between the two encounters. Plumes range in height from 60 to over 300 km with corresponding ejection velocities of 0.5 to 1.0 km/s and plume sources are located on several plains and consist of fissures or calderas. The shape and brightness distribution together with the pattern of the surface deposition on a plume 3 is simulated by a ballistic model with a constant ejection velocity of 0.5 km/s and ejection angles which vary from 0-55 deg. The distribution of active and recent eruptions is concentrated in the equatorial regions and indicates that volcanic activity is more frequent and intense in the equatorial regions than in the polar regions. Due to the geologic setting of certain plume sources and large reservoirs of volatiles required for the active eruptions, it is concluded that sulfur volcanism rather than silicate volcanism is the most likely driving mechanism for the eruption plumes.

  18. Io - Volcanic Eruption

    Science.gov (United States)

    1979-01-01

    This photo of a volcanic eruption on Jupiter's satellite Io (dark fountain-like feature near the limb) was taken March 4, 1979, about 12 hours before Voyager 1's closest approach to Jupiter. This and the accompanying photo present the evidence for the first active volcanic eruption ever observed on another body in the solar system. This photo taken from a distance of 310,000 miles (499,000 kilometers), shows a plume-like structure rising more than 60 miles (100 kilometers) above the surface, a cloud of material being produced by an active eruption. At least four eruptions have been identified on Voyager 1 pictures and many more may yet be discovered on closer analysis. On a nearly airless body like Io, particulate material thrown out of a volcano follows a ballistic trajectory, accounting for the dome-like shape of the top of the cloud, formed as particles reach the top of their flight path and begin to fall back. Spherical expansion of outflowing gas forms an even larger cloud surrounding the dust. Several regions have been identified by the infrared instrument on Voyager 1 as being several hundred degrees Fahrenheit warmer than surrounding terrain, and correlated with the eruptions. The fact that several eruptions appear to be going on simultaneously makes Io the most active surface in the solar system and suggests to scientists that Io is undergoing continuous volcanism, revising downward the age of Io's surface once again. JPL manages and controls the Voyager Project for NASA's Office of Space Science.

  19. Morphology of cone-fields in SW Elysium Planitia - Traces of hydrothermal venting on Mars?

    Science.gov (United States)

    Lanz, J. K.; Saric, M. B.

    2008-09-01

    Introduction Small cone-shaped features with summit pits can be found in several regions on Mars; mainly in Isidis Planitia; Elysium Planitia; Amazonis Planitia; Acidalia Planitia; in the Cydonia Region; in Cerberus Planum; the Phlegra Montes and on several volcanic flanks. They vary greatly in size and morphology and have been compared to terrestrial features of various origins; namely (1) cinder cones (e.g. [1]), (2) tuff cones or tuff rings (e.g. [2]), (3) rootless cones (pseudocraters) (e.g. [3], [4]), (4) pingos (e.g. [5], [6]) and (5) mud volcanoes (e.g. [7]). They are often found near volcanic centers and large lava fields or cluster in regions where the volatile content of the Martian regolith was/is supposedly high. This has led to the assumption that (ground-) water or ground ice was a trigger or driving force of cone formation. They could therefore, be an important indicator of the history of water on the planet. We have studied an area in western Elysium Planitia, bordering the Aeolis Planum plateau, which exhibits a large number of pitted cones, ridges and dome-like structures. Their distribution and morphology differs strongly from pitted cones elsewhere in Elysium Planitia, which have mainly been interpreted as hydrovolcanic rootless cones, and from other regions on Mars. Based on our observations, we present an alternative model for cone formation in the study area that might hint towards hydrothermal processes in the Aeolis Planum region and possibly young igneous activity. Aeolis Planum Cones The Aeolis Planum pitted cones (referred to as APCs from now on) cluster along the southern edges of the broad shallow valley that borders the Aeolis Planum Formation (APF) to the north. Cones along the northern edges of the valley are rare and can only be found in association with APF remnants where they strongly resemble the cones in the south. Along the southern border the cone coverage is almost continuous, describing a narrow band approximately 2 to 3 km

  20. Gravitons and light cone fluctuations

    International Nuclear Information System (INIS)

    Ford, L.H.

    1995-01-01

    Gravitons in a squeezed vacuum state, the natural result of quantum creation in the early Universe or by black holes, will introduce metric fluctuations. These metric fluctuations will introduce fluctuations of the light cone. It is shown that when the various two-point functions of a quantized field are averaged over the metric fluctuations, the light cone singularity disappears for distinct points. The metric-averaged functions remain singular in the limit of coincident points. The metric-averaged retarded Green's function for a massless field becomes a Gaussian which is nonzero both inside and outside of the classical light cone. This implies some photons propagate faster than the classical light speed, whereas others propagate slower. The possible effects of metric fluctuations upon one-loop quantum processes are discussed and illustrated by the calculation of the one-loop electron self-energy

  1. Mach Cones in Viscous Matter

    Science.gov (United States)

    Bouras, I.; El, A.; Fochler, O.; Lauciello, F.; Reining, F.; Uphoff, J.; Wesp, C.; Molnar, E.; Niemi, H.; Xu, Z.; Greiner, C.

    2011-01-01

    Employing a microscopic transport model we investigate the evolution of high energetic jets moving through a viscous medium. For the scenario of an unstoppable jet we observe a clearly strong collective behavior for a low dissipative system η/s approx 0.005, leading to the observation of cone-like structures. Increasing the dissipation of the system to η/s approx 0.32 the Mach Cone structure vanishes. Furthermore, we investigate jet-associated particle correlations. A double-peak structure, as observed in experimental data, is even for low-dissipative systems not supported, because of the large influence of the head shock.

  2. Mach Cones in Viscous Matter

    Energy Technology Data Exchange (ETDEWEB)

    Bouras, I; El, A; Fochler, O; Lauciello, F; Reining, F; Uphoff, J; Wesp, C; Xu, Z; Greiner, C [Institut fuer Theoretische Physik, Johann Wolfgang Goethe-Universitat, Max-von-Laue-Str. 1, D-60438 Frankfurt am Main (Germany); Molnar, E; Niemi, H, E-mail: bouras@th.physik.uni-frankfurt.de [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Str. 1, D-60438 Frankfurt am Main (Germany)

    2011-01-01

    Employing a microscopic transport model we investigate the evolution of high energetic jets moving through a viscous medium. For the scenario of an unstoppable jet we observe a clearly strong collective behavior for a low dissipative system {eta}/s {approx} 0.005, leading to the observation of cone-like structures. Increasing the dissipation of the system to {eta}/s {approx} 0.32 the Mach Cone structure vanishes. Furthermore, we investigate jet-associated particle correlations. A double-peak structure, as observed in experimental data, is even for low-dissipative systems not supported, because of the large influence of the head shock.

  3. Mach Cones in Viscous Matter

    International Nuclear Information System (INIS)

    Bouras, I; El, A; Fochler, O; Lauciello, F; Reining, F; Uphoff, J; Wesp, C; Xu, Z; Greiner, C; Molnar, E; Niemi, H

    2011-01-01

    Employing a microscopic transport model we investigate the evolution of high energetic jets moving through a viscous medium. For the scenario of an unstoppable jet we observe a clearly strong collective behavior for a low dissipative system η/s ∼ 0.005, leading to the observation of cone-like structures. Increasing the dissipation of the system to η/s ∼ 0.32 the Mach Cone structure vanishes. Furthermore, we investigate jet-associated particle correlations. A double-peak structure, as observed in experimental data, is even for low-dissipative systems not supported, because of the large influence of the head shock.

  4. Sensitivity to volcanic field boundary

    Science.gov (United States)

    Runge, Melody; Bebbington, Mark; Cronin, Shane; Lindsay, Jan; Rashad Moufti, Mohammed

    2016-04-01

    Volcanic hazard analyses are desirable where there is potential for future volcanic activity to affect a proximal population. This is frequently the case for volcanic fields (regions of distributed volcanism) where low eruption rates, fertile soil, and attractive landscapes draw populations to live close by. Forecasting future activity in volcanic fields almost invariably uses spatial or spatio-temporal point processes with model selection and development based on exploratory analyses of previous eruption data. For identifiability reasons, spatio-temporal processes, and practically also spatial processes, the definition of a spatial region is required to which volcanism is confined. However, due to the complex and predominantly unknown sub-surface processes driving volcanic eruptions, definition of a region based solely on geological information is currently impossible. Thus, the current approach is to fit a shape to the known previous eruption sites. The class of boundary shape is an unavoidable subjective decision taken by the forecaster that is often overlooked during subsequent analysis of results. This study shows the substantial effect that this choice may have on even the simplest exploratory methods for hazard forecasting, illustrated using four commonly used exploratory statistical methods and two very different regions: the Auckland Volcanic Field, New Zealand, and Harrat Rahat, Kingdom of Saudi Arabia. For Harrat Rahat, sensitivity of results to boundary definition is substantial. For the Auckland Volcanic Field, the range of options resulted in similar shapes, nevertheless, some of the statistical tests still showed substantial variation in results. This work highlights the fact that when carrying out any hazard analysis on volcanic fields, it is vital to specify how the volcanic field boundary has been defined, assess the sensitivity of boundary choice, and to carry these assumptions and related uncertainties through to estimates of future activity and

  5. Volcanic Eruptions and Climate

    Science.gov (United States)

    LeGrande, Allegra N.; Anchukaitis, Kevin J.

    2015-01-01

    Volcanic eruptions represent some of the most climatically important and societally disruptive short-term events in human history. Large eruptions inject ash, dust, sulfurous gases (e.g. SO2, H2S), halogens (e.g. Hcl and Hbr), and water vapor into the Earth's atmosphere. Sulfurous emissions principally interact with the climate by converting into sulfate aerosols that reduce incoming solar radiation, warming the stratosphere and altering ozone creation, reducing global mean surface temperature, and suppressing the hydrological cycle. In this issue, we focus on the history, processes, and consequences of these large eruptions that inject enough material into the stratosphere to significantly affect the climate system. In terms of the changes wrought on the energy balance of the Earth System, these transient events can temporarily have a radiative forcing magnitude larger than the range of solar, greenhouse gas, and land use variability over the last millennium. In simulations as well as modern and paleoclimate observations, volcanic eruptions cause large inter-annual to decadal-scale changes in climate. Active debates persist concerning their role in longer-term (multi-decadal to centennial) modification of the Earth System, however.

  6. Uranium series, volcanic rocks

    Science.gov (United States)

    Vazquez, Jorge A.

    2014-01-01

    Application of U-series dating to volcanic rocks provides unique and valuable information about the absolute timing of crystallization and differentiation of magmas prior to eruption. The 238U–230Th and 230Th-226Ra methods are the most commonly employed for dating the crystallization of mafic to silicic magmas that erupt at volcanoes. Dates derived from the U–Th and Ra–Th methods reflect crystallization because diffusion of these elements at magmatic temperatures is sluggish (Cherniak 2010) and diffusive re-equilibration is insignificant over the timescales (less than or equal to 10^5 years) typically associated with pre-eruptive storage of nearly all magma compositions (Cooper and Reid 2008). Other dating methods based on elements that diffuse rapidly at magmatic temperatures, such as the 40Ar/39Ar and (U–Th)/He methods, yield dates for the cooling of magma at the time of eruption. Disequilibrium of some short-lived daughters of the uranium series such as 210Po may be fractionated by saturation of a volatile phase and can be employed to date magmatic gas loss that is synchronous with volcanic eruption (e.g., Rubin et al. 1994).

  7. Bases for Cones and Reflexivity | Polyrakis | Quaestiones ...

    African Journals Online (AJOL)

    It is proved that a Banach space E is non-reflexive if and only if E has a closed cone with an unbounded, closed, dentable base. If E is a Banach lattice, the same characterization holds with the extra assumption that the cone is contained in E+. This article is also a survey of the geometry (dentability) of bases for cones.

  8. Intrinsic volumes of symmetric cones

    OpenAIRE

    Amelunxen, Dennis; Bürgisser, Peter

    2012-01-01

    We compute the intrinsic volumes of the cone of positive semidefinite matrices over the real numbers, over the complex numbers, and over the quaternions, in terms of integrals related to Mehta's integral. Several applications for the probabilistic analysis of semidefinite programming are given.

  9. DOS cones along atomic chains

    International Nuclear Information System (INIS)

    Kwapiński, Tomasz

    2017-01-01

    The electron transport properties of a linear atomic chain are studied theoretically within the tight-binding Hamiltonian and the Green’s function method. Variations of the local density of states (DOS) along the chain are investigated. They are crucial in scanning tunnelling experiments and give important insight into the electron transport mechanism and charge distribution inside chains. It is found that depending on the chain parity the local DOS at the Fermi level can form cone-like structures (DOS cones) along the chain. The general condition for the local DOS oscillations is obtained and the linear behaviour of the local density function is confirmed analytically. DOS cones are characterized by a linear decay towards the chain which is in contrast to the propagation properties of charge density waves, end states and Friedel oscillations in one-dimensional systems. We find that DOS cones can appear due to non-resonant electron transport, the spin–orbit scattering or for chains fabricated on a substrate with localized electrons. It is also shown that for imperfect chains (e.g. with a reduced coupling strength between two neighboring sites) a diamond-like structure of the local DOS along the chain appears. (paper)

  10. Seawave Slot-Cone Generator

    DEFF Research Database (Denmark)

    Vicinanza, Diego; Margheritini, Lucia; Contestabile, Pasquale

    2009-01-01

    This paper discusses a new type of Wave Energy Converter (WEC) named Seawave Slot-Cone Generator (SSG). The SSG is a WEC of the overtopping type. The structure consists of a number of reservoirs one on the top of each others above the mean water level in which the water of incoming waves is store...

  11. Friction in volcanic environments

    Science.gov (United States)

    Kendrick, Jackie E.; Lavallée, Yan

    2016-04-01

    Volcanic landscapes are amongst the most dynamic on Earth and, as such, are particularly susceptible to failure and frictional processes. In rocks, damage accumulation is frequently accompanied by the release of seismic energy, which has been shown to accelerate in the approach to failure on both a field and laboratory scale. The point at which failure occurs is highly dependent upon strain-rate, which also dictates the slip-zone properties that pertain beyond failure, in scenarios such as sector collapse and pyroclastic flows as well as the ascent of viscous magma. High-velocity rotary shear (HVR) experiments have provided new opportunities to overcome the grand challenge of understanding faulting processes during volcanic phenomena. Work on granular ash material demonstrates that at ambient temperatures, ash gouge behaves according to Byerlee's rule at low slip velocities, but is slip-weakening, becoming increasingly lubricating as slip ensues. In absence of ash along a slip plane, rock-rock friction induces cataclasis and heating which, if sufficient, may induce melting (producing pseudotachylyte) and importantly, vesiculation. The viscosity of the melt, so generated, controls the subsequent lubrication or resistance to slip along the fault plane thanks to non-Newtonian suspension rheology. The shear-thinning behaviour and viscoelasticity of frictional melts yield a tendency for extremely unstable slip, and occurrence of frictional melt fragmentation. This velocity-dependence acts as an important feedback mechanism on the slip plane, in addition to the bulk composition, mineralogy and glass content of the magma, that all influence frictional behaviour. During sector collapse events and in pyroclastic density currents it is the frictional properties of the rocks and ash that, in-part, control the run-out distance and associated risk. In addition, friction plays an important role in the eruption of viscous magmas: In the conduit, the rheology of magma is integral

  12. Timing and sources of neogene and quaternary volcanism in South-Central Guatemala

    Science.gov (United States)

    Reynolds, James H.

    1987-08-01

    Five new and six existing radiometric age dates place constraints on the timing of volcanic episodes in a 1400-km 2 area east of Guatemala City. The source of the voluminous Miocene rhyolitic welded tuffs was the newly discovered Santa Rosa de Lima caldera, in the northern part of the area, not fissure eruptions as was previously believed. Resurgence during the Pliocene included the eruption of more silicic tuffs, followed by post-collapse volcanism around the perimeter. Volcanism in the southern part of the area occurred along the Neogene volcanic front. The sources for these Late Miocene and Pliocene andesitic lavas were not fissure eruptions, as was once believed, but were four large volcanic centers, Cerro Pinula, Ixhuatán, Teanzul, and Cerro La Gabia. The Santa Rosa de Lima caldera structure deflects the Jalpatagua Fault forming tensional fractures along which eruptions in the Quaternary Cuilapa-Barbarena cinder cone field took place. Pleistocene ash flows were erupted from Ixhuatán and Tecuamburro volcanoes in the southern part of the area. Tephras from Ayarza, Amatitlán, and Atitlán blanket the northern and central portions. Present-day activity is restricted to hot springs around the northern and eastern base of Tecuamburro volcano. Based on the work in this area it is proposed that rocks of the Miocene Chalatenango Formation throughout northern Central America were erupted from calderas behind the Neogene volcanic front. Rocks of the Mio-Pliocene Bálsamo Formation in Guatemala and El Salvador were erupted from discrete volcanic centers along the Neogene volcanic front. Pliocene rocks of the Cuscatlán Formation probably represent post-collapse volcanism around earlier caldera structures.

  13. The Subduction Component at Volcan El Jorullo: Young but Subdued

    Science.gov (United States)

    Rubin, K. H.; Zellmer, G. F.; Jurado-Chichay, Z.; Moran-Zenteno, D.; Pyle, D.

    2006-12-01

    Volcan El Jorullo (1759 to 1774) was produced in one of two historical eruptions within the Michoacan- Guanajuato Volcanic field (MGVF) in the western Trans Mexican Volcanic Belt. The MGVF has experienced widespread Pleistocene volcanism primarily at monogenetic fissures and cones; its exact relationship to the Mexican Subduction zone has been the subject of some discussion in the literature. Here we demonstrate that Jorullo basalts and basaltic andesites have U-series disequilibria characteristic of arc magmatism, and constrain melting and melt transport from a previously slab-fluid enriched source within the past few thousand years. All Jorullo lavas have excess 238U relative to 230Th (a slab-fluid signature found almost exclusive in arc magmas) and excess ^{226}Ra relative to 230Th (a short-lived melting signature common in all young volcanics enhanced by slab derived fluids at arcs). These signatures are well correlated with other chemical indicators of fluid enrichment in the lavas, and are consistent with a recent Jorullo melt inclusion volatile study indicating relatively high water contents inherrited from the magma source (Johnson et al., EOS 85, Fall Meet. Suppl, 2004). ^{226}Ra excesses in Jorullo lavas reach 70%, a value which is similar to but greater than those reported by Reid (IAVCEI, 1987) for Paricutin (the other historical MGVF eruption). This result is consistent with a similar but slightly shorter crustal residence time of the more mafic Jorullo magmas. Jorullo 238U excesses (5-10%) are at the low end of values reported for Paricutin (up to 20%; Condomines et al., 1988). We have previously reported (Rubin et al., EOS 85, Fall Meet. Suppl, 2004) that country rock assimilation is a more widespread occurrence at Jorullo than previously thought (Luhr and Carmichael, CMP 90, 1985); this significantly impacts the trace element and radiogenic isotope (e.g., Sr, Nd, Pb) composition of some Jorullo lavas. Assimilation also disrupts the U-series system

  14. Martian mud volcanism: Terrestrial analogs and implications for formational scenarios

    Science.gov (United States)

    Skinner, J.A.; Mazzini, A.

    2009-01-01

    The geology of Mars and the stratigraphic characteristics of its uppermost crust (mega-regolith) suggest that some of the pervasively-occurring pitted cones, mounds, and flows may have formed through processes akin to terrestrial mud volcanism. A comparison of terrestrial mud volcanism suggests that equivalent Martian processes likely required discrete sedimentary depocenters, volatile-enriched strata, buried rheological instabilities, and a mechanism of destabilization to initiate subsurface flow. We outline five formational scenarios whereby Martian mud volcanism might have occurred: (A) rapid deposition of sediments, (B) volcano-induced destabilization, (C) tectonic shortening, (D) long-term, load-induced subsidence, and (E) seismic shaking. We describe locations within and around the Martian northern plains that broadly fit the geological context of these scenarios and which contain mud volcano-like landforms. We compare terrestrial and Martian satellite images and examine the geological settings of mud volcano provinces on Earth in order to describe potential target areas for piercement structures on Mars. Our comparisons help to evaluate not only the role of water as a functional component of geological processes on Mars but also how Martian mud volcanoes could provide samples of otherwise inaccessible strata, some of which could contain astrobiological evidence.

  15. Effusive and explosive volcanism on the ultraslow-spreading Gakkel Ridge, 85°E

    Science.gov (United States)

    Pontbriand, Claire W.; Soule, S. Adam; Sohn, Robert A.; Humphris, Susan E.; Kunz, Clayton; Singh, Hanumant; Nakamura, Ko-Ichi; Jakobsson, Martin; Shank, Timothy

    2012-10-01

    We use high-definition seafloor digital imagery and multibeam bathymetric data acquired during the 2007 Arctic Gakkel Vents Expedition (AGAVE) to evaluate the volcanic characteristics of the 85°E segment of the ultraslow spreading Gakkel Ridge (9 mm yr-1full rate). Our seafloor imagery reveals that the axial valley is covered by numerous, small-volume (order ˜1000 m3) lava flows displaying a range of ages and morphologies as well as unconsolidated volcaniclastic deposits with thicknesses up to 10 cm. The valley floor contains two prominent volcanic lineaments made up of axis-parallel ridges and small, cratered volcanic cones. The lava flows appear to have erupted from a number of distinct source vents within the ˜12-15 km-wide axial valley. Only a few of these flows are fresh enough to have potentially erupted during the 1999 seismic swarm at this site, and these are associated with the Oden and Loke volcanic cones. We model the widespread volcaniclastic deposits we observed on the seafloor as having been generated by the explosive discharge of CO2 that accumulated in (possibly deep) crustal melt reservoirs. The energy released during explosive discharge, combined with the buoyant rise of hot fluid, lofted fragmented clasts of rapidly cooling magma into the water column, and they subsequently settled onto the seafloor as fall deposits surrounding the source vent.

  16. Status of volcanic hazard studies for the Nevada Nuclear Waste Storage Investigations

    International Nuclear Information System (INIS)

    Crowe, B.M.; Vaniman, D.T.; Carr, W.J.

    1983-03-01

    Volcanism studies of the Nevada Test Site (NTS) region are concerned with hazards of future volcanism with respect to underground disposal of high-level radioactive waste. The hazards of silicic volcanism are judged to be negligible; hazards of basaltic volcanism are judged through research approaches combining hazard appraisal and risk assessment. The NTS region is cut obliquely by a N-NE trending belt of volcanism. This belt developed about 8 Myr ago following cessation of silicic volcanism and contemporaneous with migration of basaltic activity toward the southwest margin of the Great Basin. Two types of fields are present in the belt: (1) large-volume, long-lived basalt and local rhyolite fields with numerous eruptive centers and (2) small-volume fields formed by scattered basaltic scoria cones. Late Cenozoic basalts of the NTS region belong to the second field type. Monogenetic basalt centers of this region were formed mostly by Strombolian eruptions; Surtseyean activity has been recognized at three centers. Geochemically, the basalts of the NTS region are classified as straddle A-type basalts of the alkalic suite. Petrological studies indicate a volumetric dominance of evolved hawaiite magmas. Trace- and rare-earth-element abundances of younger basalt ( - 8 to 10 - 10 as calculated for a 1-yr period. Potential disruptive and dispersal effects of magmatic penetration of a repository are controlled primarily by the geometry of basalt feeder systems, the mechanism of waste incorporation in magma, and Strombolian eruption processes

  17. The Western Arabian intracontinental volcanic fields as a potential UNESCO World Heritage site

    Science.gov (United States)

    Németh, Károly; Moufti, Mohammed R.

    2017-04-01

    UNESCO promotes conservation of the geological and geomoprhological heritage through promotion of protection of these sites and development of educational programs under the umbrella of geoparks among the most globally significant ones labelled as UNESCO Global Geoparks. UNESCO also maintains a call to list those natural sites that provide universal outstanding values to demonstrate geological features or their relevance to our understanding the evolution of Earth. Volcanoes currently got a surge in nomination to be UNESCO World Heritage sites. Volcanic fields in the contrary fell in a grey area of nominations as they represents the most common manifestation of volcanism on Earth hence they are difficult to view as having outstanding universal values. A nearly 2500-km long 300-km wide region of dispersed volcanoes located in the Western Arabian Penninsula mostly in the Kingdom of Saudi Arabia form a near-continuous location that carries universal outstanding value as one of the most representative manifestation of dispersed intracontinental volcanism on Earth to be nominated as an UNESCO World Heritage site. The volcanic fields formed in the last 20 Ma along the Red Sea as group of simple basaltic to more mature and long-lived basalt to trachyte-to-rhyolite volcanic fields each carries high geoheritage values. While these volcanic fields are dominated by scoria and spatter cones and transitional lava fields, there are phreatomagmatic volcanoes among them such as maars and tuff rings. Phreatomagmatism is more evident in association with small volcanic edifices that were fed by primitive magmas, while phreatomagmatic influences during the course of a larger volume eruption are also known in association with the silicic eruptive centres in the harrats of Rahat, Kishb and Khaybar. Three of the volcanic fields are clearly bimodal and host small-volume relatively short-lived lava domes and associated block-and-ash fans providing a unique volcanic landscape commonly not

  18. Closer look at lunar volcanism

    International Nuclear Information System (INIS)

    Vaniman, D.T.; Heiken, G.; Taylor, G.J.

    1984-01-01

    Although the American Apollo and Soviet Luna missions concentrated on mare basalt samples, major questions remain about lunar volcanism. Lunar field work will be indispensable for resolving the scientific questions about ages, compositions, and eruption processes of lunar volcanism. From a utilitarian standpoint, a better knowledge of lunar volcanism will also yield profitable returns in lunar base construction (e.g., exploitation of rille or lava-tube structures) and in access to materials such as volatile elements, pure glass, or ilmenite for lunar industry

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

    Science.gov (United States)

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

    2017-04-01

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

  20. Volcanology: Volcanic bipolar disorder explained

    Science.gov (United States)

    Jellinek, Mark

    2014-02-01

    Eruptions come in a range of magnitudes. Numerical simulations and laboratory experiments show that rare, giant super-eruptions and smaller, more frequent events reflect a transition in the essential driving forces for volcanism.

  1. Cardiac cone-beam CT

    International Nuclear Information System (INIS)

    Manzke, Robert

    2005-01-01

    This doctoral thesis addresses imaging of the heart with retrospectively gated helical cone-beam computed tomography (CT). A thorough review of the CT reconstruction literature is presented in combination with a historic overview of cardiac CT imaging and a brief introduction to other cardiac imaging modalities. The thesis includes a comprehensive chapter about the theory of CT reconstruction, familiarizing the reader with the problem of cone-beam reconstruction. The anatomic and dynamic properties of the heart are outlined and techniques to derive the gating information are reviewed. With the extended cardiac reconstruction (ECR) framework, a new approach is presented for the heart-rate-adaptive gated helical cardiac cone-beam CT reconstruction. Reconstruction assessment criteria such as the temporal resolution, the homogeneity in terms of the cardiac phase, and the smoothness at cycle-to-cycle transitions are developed. Several reconstruction optimization approaches are described: An approach for the heart-rate-adaptive optimization of the temporal resolution is presented. Streak artifacts at cycle-to-cycle transitions can be minimized by using an improved cardiac weighting scheme. The optimal quiescent cardiac phase for the reconstruction can be determined automatically with the motion map technique. Results for all optimization procedures applied to ECR are presented and discussed based on patient and phantom data. The ECR algorithm is analyzed for larger detector arrays of future cone-beam systems throughout an extensive simulation study based on a four-dimensional cardiac CT phantom. The results of the scientific work are summarized and an outlook proposing future directions is given. The presented thesis is available for public download at www.cardiac-ct.net

  2. Monogenetic volcanic hazards and assessment

    Science.gov (United States)

    Connor, C.; Connor, L. J.; Richardson, J. A.

    2012-12-01

    Many of the Earth's major cities are build on the products of monogenetic volcanic eruptions and within geologically active basaltic volcanic fields. These cities include Mexico City (Mexico), Auckland (New Zealand), Melbourne (Australia), and Portland (USA) to name a few. Volcanic hazards in these areas are complex, and involve the potential formation of new volcanic vents and associated hazards, such as lava flows, tephra fallout, and ballistic hazards. Hazard assessment is complicated by the low recurrence rate of volcanism in most volcanic fields. We have developed a two-stage process for probabilistic modeling monogenetic volcanic hazards. The first step is an estimation of the possible locations of future eruptive vents based on kernel density estimation and recurrence rate of volcanism using Monte Carlo simulation and accounting for uncertainties in age determinations. The second step is convolution of this spatial density / recurrence rate model with hazard codes for modeling lava inundation, tephra fallout, and ballistic impacts. A methodology is presented using this two-stage approach to estimate lava flow hazard in several monogenetic volcanic fields, including at a nuclear power plant site near the Shamiram Plateau, a Quaternary volcanic field in Armenia. The location of possible future vents is determined by estimating spatial density from a distribution of 18 mapped vents using a 2-D elliptical Gaussian kernel function. The SAMSE method, a modified asymptotic mean squared error approach, uses the distribution of known eruptive vents to optimally determine a smoothing bandwidth for the Gaussian kernel function. The result is a probability map of vent density. A large random sample (N=10000) of vent locations is drawn from this probability map. For each randomly sampled vent location, a lava flow inundation model is executed. Lava flow input parameters (volume and average thickness) are determined from distributions fit to field observations of the low

  3. Prescriptionless light-cone integrals

    International Nuclear Information System (INIS)

    Suzuki, A.T.; Schmidt, A.G.M.

    2000-01-01

    Perturbative quantum gauge field theory as seen within the perspective of physical gauge choices such as the light-cone gauge entails the emergence of troublesome poles of the type (k.n) -α in the Feynman integrals. These come from the boson field propagator, where α=1,2,.. and n μ is the external arbitrary four-vector that defines the gauge properly. This becomes an additional hurdle in the computation of Feynman diagrams, since any graph containing internal boson lines will inevitably produce integrands with denominators bearing the characteristic gauge-fixing factor. How one deals with them has been the subject of research over decades, and several prescriptions have been suggested and tried in the course of time, with failures and successes. However, a more recent development at this fronteer which applies the negative dimensional technique to compute light-cone Feynman integrals shows that we can altogether dispense with prescriptions to perform the calculations. An additional bonus comes to us attached to this new technique, in that not only it renders the light-cone prescriptionless but, by the very nature of it, it can also dispense with decomposition formulas or partial fractioning tricks used in the standard approach to separate pole products of the type (k.n) -α [(k-p).n] -β (β=1,2,..). In this work we demonstrate how all this can be done. (orig.)

  4. Volcanic crisis in

    Directory of Open Access Journals (Sweden)

    Mgs. Víctor Manuel Pérez Martínez

    2007-01-01

    Full Text Available The article is the result of an investigation which is focussed on some deontological aspects of the scientificjournalism. In the first place it gives a theoretical vision about science, journalism, internet and including some reflectionsabout the deontological principles in handling the information about science and technology. This focus is useful as it formsthe base of an investigation where we deal with the information about a possible ”volcanic crisis” in El Teide during the years2004-2005 done by the digital newspaper” El Dïa” a canarian newspaper from Tenerife. The work required the revision of theinformation which was published and a followed analysis of its context. It was used the digital version with the purpose ofvisualizing the news which was published. It was also compared with a printed version, with local cover but divulged theinformation to the public who was most affected by this particular news. The results give rise to some questions regardinghow the information is given to a topic which is of local interest as well as national and international interest due to therepercussions in the social, economical and tourist field (the tourist field is the main industrial sector in Tenerife by receivingthis type of news.

  5. Volcanic Zone, New Zealand

    Directory of Open Access Journals (Sweden)

    Graham J. Weir

    2001-01-01

    Full Text Available A conceptual model of the Taupo Volcanic Zone (TVZ is developed, to a depth of 25 km, formed from three constant density layers. The upper layer is formed from eruption products. A constant rate of eruption is assumed, which eventually implies a constant rate of extension, and a constant rate of volumetric creation in the middle and bottom layers. Tectonic extension creates volume which can accomodate magmatic intrusions. Spreading models assume this volume is distributed throughout the whole region, perhaps in vertical dykes, whereas rifting models assume the upper crust is thinned and the volume created lies under this upper crust. Bounds on the heat flow from such magmatic intrusions are calculated. Heat flow calculations are performed and some examples are provided which match the present total heat output from the TVZ of about 4200 MW, but these either have extension rates greater than the low values of about 8 ± 4 mm/a being reported from GPS measurements, or else consider extension rates in the TVZ to have varied over time.

  6. Swellable clay minerals in weathering products of volcanic sediments related to landslides by 2016 Kumamoto Earthquake

    Science.gov (United States)

    Isobe, H.; Torii, M.

    2016-12-01

    2016 Kumamoto Earthquake triggered numerous landslides in Aso caldera area, Japan and incurred heavy casualties. Landslides occurred not only on steep slopes at the caldera cliffs or the barranco but also on relatively gradual slopes at the side of the central cones in the Aso caldera. The Aso volcano is a volcanic complex with huge caldera formed by catastrophic eruption at approximately 90ka and central cones formed by subsequent activities to recent years. The central cones are volcanic peaks contain various rocks including basaltic, andesitic and rhoyolitic lavas and pyroclastic materials. In this study, we analyzed the samples collected from the bottom surface of landslides occurred at the gradual hillside on the western flank of the Aso central cones. The subsurface geology of the site is Takanoobane rhyolite lava, 51ka, covered by dark silty or pelitic tuffs and black soil strata including Kusasenri pumice layer, 31ka. The bottom plane of the landslides can be seen as flat surfaces at boundaries between units in the Kusasenri pumice or bottom of the Kusasenri pumice on the pelitic tuff with charcoaled plants. The Kusasenri pumice layer is a coarse grained and highly permeable but poorly continuous. X-ray diffraction analysis revealed that the main component of the samples is halloysite (10Å). Halloysite (10Å) is alteration product of fine grained volcanic ash, and swellable clay with interlayer water molecules which bring sticky and deformable characteristics. The landslides caused by 2016 Kumamoto Earthquake occurred without precipitation within a week. Strong earthquake may fluidize swellable clay layers in gradual slopes and triggered heavy landslides.

  7. Primitive magmas at five Cascade volcanic fields: Melts from hot, heterogeneous sub-arc mantle

    Science.gov (United States)

    Bacon, C.R.; Bruggman, P.E.; Christiansen, R.L.; Clynne, M.A.; Donnelly-Nolan, J. M.; Hildreth, W.

    1997-01-01

    Major and trace element concentrations, including REE by isotope dilution, and Sr, Nd, Pb, and O isotope ratios have been determined for 38 mafic lavas from the Mount Adams, Crater Lake, Mount Shasta, Medicine Lake, and Lassen volcanic fields, in the Cascade arc, northwestern part of the United States. Many of the samples have a high Mg# [100Mg/(Mg + FeT) > 60] and Ni content (>140 ppm) such that we consider them to be primitive. We recognize three end-member primitive magma groups in the Cascades, characterized mainly by their trace-element and alkali-metal abundances: (1) High-alumina olivine tholeiite (HAOT) has trace element abundances similar to N-MORB, except for slightly elevated LILE, and has Eu/Eu* > 1. (2) Arc basalt and basaltic andesite have notably higher LILE contents, generally have higher SiO2 contents, are more oxidized, and have higher Cr for a given Ni abundance than HAOT. These lavas show relative depletion in HFSE, have lower HREE and higher LREE than HAOT, and have smaller Eu/Eu* (0.94-1.06). (3) Alkali basalt from the Simcoe volcanic field east of Mount Adams represents the third end-member, which contributes an intraplate geochemical signature to magma compositions. Notable geochemical features among the volcanic fields are: (1) Mount Adams rocks are richest in Fe and most incompatible elements including HFSE; (2) the most incompatible-element depleted lavas occur at Medicine Lake; (3) all centers have relatively primitive lavas with high LILE/HFSE ratios but only the Mount Adams, Lassen, and Medicine Lake volcanic fields also have relatively primitive rocks with an intraplate geochemical signature; (4) there is a tendency for increasing 87Sr/86Sr, 207Pb/204Pb, and ??18O and decreasing 206Pb/204Pb and 143Nd/144Nd from north to south. The three end-member Cascade magma types reflect contributions from three mantle components: depleted sub-arc mantle modestly enriched in LILE during ancient subduction; a modern, hydrous subduction component

  8. NW-SE Pliocene-Quaternary extension in the Apan-Acoculco region, eastern Trans-Mexican Volcanic Belt

    Science.gov (United States)

    García-Palomo, Armando; Macías, José Luis; Jiménez, Adrián; Tolson, Gustavo; Mena, Manuel; Sánchez-Núñez, Juan Manuel; Arce, José Luis; Layer, Paul W.; Santoyo, Miguel Ángel; Lermo-Samaniego, Javier

    2018-01-01

    The Apan-Acoculco area is located in the eastern portion of the Mexico basin and the Trans-Mexican Volcanic Belt. The area is transected by right-stepping variably dipping NE-SW normal faults. The Apan-Tlaloc Fault System is a major discontinuity that divides the region into two contrasting areas with different structural and volcanic styles. a) The western area is characterized by a horst-graben geometry with widespread Quaternary monogenetic volcanism and scattered outcrops of Miocene and Pliocene rocks. b) The eastern area is dominated by tilted horsts with a domino-like geometry with widespread Miocene and Pliocene rocks, scattered Quaternary monogenetic volcanoes and the Acoculco Caldera. Gravity data suggest that this structural geometry continues into the Mesozoic limestones. Normal faulting was active since the Pliocene with three stages of extension. One of them, an intense dilatational event began during late Pliocene and continues nowadays, contemporaneously with the emplacement of the Apan-Tezontepec Volcanic Field and the Acoculco caldera. Statistical analysis of cone elongation, cone instability, and the kinematic analysis of faults attest for a NW50°SE ± 7° extensional regime in the Apan-Acoculco area. The activity in some portions of the Apan-Tlaloc Fault System continues today as indicated by earthquake swarms recorded in 1992 and 1996, that disrupted late Holocene paleosols, and Holocene volcanism.

  9. Programming Retinal Stem Cells into Cone Photoreceptors

    Science.gov (United States)

    2015-12-01

    researchers that want to reprogram stem cells for clinical applications. Lastly, we attempted to transplant cone photoreceptors derived from human retinal...AWARD NUMBER: W81XWH-14-1-0566 TITLE: Programming Retinal Stem Cells into Cone Photoreceptors PRINCIPAL INVESTIGATOR: Joseph A. Brzezinski IV...SUBTITLE 5a. CONTRACT NUMBER Programming Retinal Stem Cells into Cone Photoreceptors 5b. GRANT NUMBER W81XWH-14-1-0566 5c. PROGRAM ELEMENT NUMBER 6

  10. Case of Unilateral Peripheral Cone Dysfunction

    OpenAIRE

    Yujin Mochizuki; Kei Shinoda; Celso Soiti Matsumoto; Gerd Klose; Emiko Watanabe; Keisuke Seki; Itaru Kimura; Atsushi Mizota

    2012-01-01

    Purpose: Peripheral cone dystrophy is a subgroup of cone dystrophy, and only 4 cases have been reported. We present a patient with unilateral peripheral cone dysfunction and report the functional changes determined by electrophysiological tests and ultrastructural changes determined by spectral domain optical coherence tomography (SD-OCT). Case: A 34-year-old woman complained of blurred vision in both eyes. Our examination showed that her visual acuity was 0.05 OD and 0.2 OS. A relative affer...

  11. The Carrán-Los Venados volcanic field and its relationship with coeval and nearby polygenetic volcanism in an intra-arc setting

    Science.gov (United States)

    Bucchi, Francisco; Lara, Luis E.; Gutiérrez, Francisco

    2015-12-01

    Understanding the relationship between monogenetic and polygenetic volcanism has been a long-standing goal in volcanology, especially in cases where these two styles of volcanism are coeval and geographically adjacent. We studied the Carrán-Los Venados (CLV) volcanic field and made comparisons with published data on CLV's polygenetic neighbor Puyehue-Cordón Caulle (PCC) in the Southern Andean arc, using quantitative tools and recent numerical simulations of magma reservoir formation. CLV is a basaltic to basaltic andesitic volcanic field composed of 65 post-glacial scoria cones and maars and a 1-km-high Pleistocene stratovolcano, whereas PCC is a basaltic to rhyolitic composite volcano. Our results point to three main differences between CLV and PCC: (1) the CLV magmas differentiate at low-crustal reservoirs, followed by rapid ascent to the surface, while the PCC magmas stagnate and differentiate in lower- and upper-crustal reservoirs; (2) CLV is elongated in the NE direction while PCC is elongated in the NW direction. Under the current stress field (N60°E σHmax), these two volcanic alignments correspond, respectively, to local extensional and compressive deformation zones within the arc; and (3), the post-glacial CLV magma flux was estimated to be 3.1 ± 1.0 km3/ky, which is similar to the average magma flux estimated for PCC; however, the PCC magma flux is estimated at approximately twice this value during peak eruptive periods (5.5 ± 1.1 km3/ky). Based on numerical simulations, CLV is in a limit situation to create and sustain a mush-type upper-crustal reservoir containing highly crystalline magma, which is however not eruptible. The PCC volcanic system would have been able to create a stable reservoir containing eruptible silicic magma during periods of peak magma flux. We postulate that monogenetic volcanism occurs at CLV due to both low magma flux and an extensional/transtensional regime that favors rapid magma rise without storage and differentiation in

  12. Vacuum Compatible Percussive Dynamic Cone Penetrometer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Honeybee Robotics proposes to develop a vacuum compatible percussive dynamic cone penetrometer (PDCP), for establishing soil bin characteristics, with the ultimate...

  13. Light-cones, almost light-cones and almost-complex light-cones

    Science.gov (United States)

    Newman, Ezra T.

    2017-08-01

    We point out (and then apply to a general situation) an unusual relationship among a variety of null geodesic congruences; (a) the generators of ordinary light-cones and (b) certain (related) shear-free but twisting congruences in Minkowski space-time as well as (c) asymptotically shear-free null geodesic congruences that exist in the neighborhood of Penrose's I^{ +} in Einstein or Einstein-Maxwell asymptotically flat-space-times. We refer to these geodesic congruences respectively as: Lignt-Cones (LCs), as "Almost-Complex"-Light-Cones (ACLCs), [though they are real they resemble complex light-cones in complex Minkowski space] and finally to a family of congruences in asymptotically flat-spaces as ` Almost Light-Cones' (ALC). The two essential points of resemblance among the three families are: (1) they are all either shear-free or asymptotically shear-free and (2) in each family the individual members of the family can be labeled by the points in a real or complex four-dimensional manifold. As an example, the Minkowski space LCs are labeled by the (real) coordinate value of their apex. In the case of (ACLCs) (complex coordinate values), the congruences will have non-vanishing twist whose magnitude is determined by the imaginary part of the complex coordinate values. In studies of gravitational radiation, Bondi-type of null surfaces and their associated Bondi coordinates have been almost exclusively used for calculations. It turns out that some surprising relations arise if, instead of the Bondi coordinates, one uses ALCs and their associated coordinate systems in the analysis of the Einstein-Maxwell equations in the neighborhood of I+. More explicitly and surprisingly, the asymptotic Bianchi Identities (arising directly from the Einstein equations), expressed in the coordinates of the ALCs, turn directly into many of the standard definitions and equations and relations of classical mechanics coupled with Maxwell's equations. These results extend and generalize the

  14. Tectonics control over instability of volcanic edifices in transtensional tectonic regimes

    Science.gov (United States)

    Norini, G.; Capra, L.; Lagmay, A. M. F.; Manea, M.; Groppelli, G.

    2009-04-01

    We present the results of analogue modeling designed to investigate the interactions between volcanic edifices and transtensional basement faulting. Three sets of experiments were run to account for three examples of stratovolcanoes in active transtensive tectonics regimes, the Nevado de Toluca and Jocotitlan volcanoes in Mexico, and the Mayon volcano in the Philippines. All these volcanoes show different behavior and relationship among volcanism, instability of the volcanic edifice, and basement tectonics. Field geological and structural data gave the necessary constrains to the models. The modeling apparatus consisted of a sand cone on a sheared basal layer. Injections of vegetable oil were used to model the rising of magma inside the deformed analogue cones. Set 1: In the case of a volcano directly on top of a basal transtensive shear producing a narrow graben, as observed on the Nevado de Toluca volcano, the analogue models reveal a strong control of the basement faulting on the magma migration path and the volcano instability. Small lateral collapses are directed parallel to the basal shear and affect a limited sector of the cone. Set 2: If the graben generated by transtensive tectonics is bigger in respect to the volcanic edifice and the volcano sits on one boundary fault, as in the case of Mayon volcano, the combined normal and transcurrent movements of the analogue basement fault generate a sigmoidal structure in the sand cone, inducing major sector collapses directed at approx 45° relative to the basement shear toward the downthrown block. Set 3: For volcanoes located near major transtensive faults, as the Jocotitlan volcano, analogue modelling shows an important control of the regional tectonics on the geometry of the fractures and migration paths of magma inside the cone. These structures render unstable the flanks of the volcano and promote sector collapses perpendicular to the basement shear and directed toward the graben formed by the transtensive

  15. Rate of volcanism on Venus

    International Nuclear Information System (INIS)

    Fegley, B. Jr.; Prinn, R.G.

    1988-07-01

    The maintenance of the global H 2 SO 4 clouds on Venus requires volcanism to replenish the atmospheric SO 2 which is continually being removed from the atmosphere by reaction with calcium minerals on the surface of Venus. The first laboratory measurements of the rate of one such reaction, between SO 2 and calcite (CaCO 3 ) to form anhydrite (CaSO 4 ), are reported. If the rate of this reaction is representative of the SO 2 reaction rate at the Venus surface, then we estimate that all SO 2 in the Venus atmosphere (and thus the H 2 SO 4 clouds) will be removed in 1.9 million years unless the lost SO 2 is replenished by volcanism. The required rate of volcanism ranges from about 0.4 to about 11 cu km of magma erupted per year, depending on the assumed sulfur content of the erupted material. If this material has the same composition as the Venus surface at the Venera 13, 14 and Vega 2 landing sites, then the required rate of volcanism is about 1 cu km per year. This independent geochemically estimated rate can be used to determine if either (or neither) of the two discordant (2 cu km/year vs. 200 to 300 cu km/year) geophysically estimated rates is correct. The geochemically estimated rate also suggests that Venus is less volcanically active than the Earth

  16. Cone Storage and Seed Quality in Longleaf Pine

    Science.gov (United States)

    F.T. Bonner

    1987-01-01

    Immature cones of longleaf pine (Pinus palustris Mill.) can be stored for at least 5 weeks without adversely affecting extraction or seed quality. Cone moisture should be below 50 percent before using heat to open cones.

  17. Quaternary basaltic volcanism in the Payenia volcanic province, Argentina

    DEFF Research Database (Denmark)

    Søager, Nina

    in basalts from all the studied volcanic fields in Payenia is signs of lower crustal contamination indicating assimilation of, in some cases, large amounts of trace element depleted, mafic, plagioclase-bearing rocks. The northern Payenia is dominated by backarc basalts erupted between late Pliocene to late...... are isotopically similar to the Andean Southern Volcanic Zone arc rocks and their mantle source possibly resembled the source of South Atlantic N-MORB prior to addition of fluids and melts from the subduction channel. However, it must have been more enriched than the estimates of depleted upper mantle from...

  18. Energy integration in south cone

    International Nuclear Information System (INIS)

    Ribeiro, M.A.K.

    1990-01-01

    The economic development of a geo-political region is directly related to the energy resources available to its productive system. The analysis carried out in this paper focus a region limited by Paraguay, Uruguay, the Argentina north and the Brazilian south, the core of the so called South Cone. The region has a diversified energy matrix that assures strong connections between the countries. The main resources available are hydroelectric but the approach gives a strong emphasis in coal and natural gas. The outlined model of a self sustained development of the region can be used as the foundation of the independent economic development of South America. (author)

  19. Anomalous Geologic Setting of the Spencer-High Point Volcanic Field, Eastern Snake River Plain, Idaho

    Science.gov (United States)

    Iwahashi, G. S.; Hughes, S. S.

    2006-12-01

    The Spencer-High Point (SHP) volcanic field comprises an ~1700 sq km mafic volcanic rift zone located near Yellowstone in the eastern Snake River Plain (ESRP). SHP lava flows are both similar to and distinct from typical olivine tholeiite lavas of the ESRP. SHP has unique physical volcanic features characterized by numerous cinder cones and short lava flows; whereas, spatter ramparts, fissures and longer flows dominate in other ESRP regions. Topography and aerial photos indicate that vents are generally aligned northwest- southeast, which is sub-parallel to adjacent Basin and Range faults in much of the ESRP. Yet individual vents and other structural elements in SHP where Basin and Range, ESRP and thrust-faulted mountain belts all intersect, are elongated in a more east-west direction. Distinct structural control is manifested in an overall southward slope over the entire volcanic field. Short lava flows tend to flow north or south off of a central topographically higher zone of overlapping lava flows and smaller vents. Several smaller vents appear to be parasitic cones adjacent to larger eruptive centers. Contrary to these relations, preliminary geochemical data by Leeman (1982) and Kuntz et al. (1992) suggest SHP lavas are typical ESRP olivine tholeiite basalts, which notably have coarsely diktytaxitic texture. The central and eastern sections of the SHP field contain lavas with large (3-8cm), clear, euhedral plagioclase phenocrysts but without diktytaxitic texture. Lava flows in the central and eastern sections of SHP volcanic field are pahoehoe. These also contain crustal xenoliths implying a prolonged crustal history. Geochemical whole rock and microprobe analyses are currently being processed for petrogenetic history.

  20. The use of luminescence for dating young volcanic eruptions

    Science.gov (United States)

    Schmidt, Christoph; Schaarschmidt, Maria; Kolb, Thomas; Richter, Daniel; Tchouankoue, Jean Pierre; Zöller, Ludwig

    2017-04-01

    Reliable chronologies of volcanic eruptions are vital for hazard analysis, but dating of Holocene and Late Pleistocene volcanism poses a major challenge. Established techniques such as 40Ar/39Ar are often problematic due to the long half-life of 40K or the absence of datable materials. In this context, luminescence dating methods are an alternative since they are applicable to Earth's most common minerals and to a range of different datable events. Luminescence signal resetting during volcanic activity can be caused by heat (lava, contact to lava), light (disintegration of ejecta) or (temperature-assisted) pressure in the course of phreatomagmatic explosions. While volcanogenic minerals assembling basalt or other volcanic rocks are less suitable for luminescence dating due to so-called anomalous fading, the signal of volcanogenically heated or fragmented country rock actually relates to the time of eruption as well and further provides reproducible results. This contribution aims to illustrate the potential of this latter approach by presenting two case studies. The first refers to two Late Pleistocene scoria cones in the Westeifel Volcanic Field (WEVF), Germany, of which the Wartgesberg locality was dated by 40Ar/39Ar and 14C, while the closeby Facher Höhe is chronologically poorly constrained (Mertz et al. 2015; pers comm. Luise Eichhorn, 2016). The former locality allows testing the accuracy of various luminescence techniques (thermoluminescence, TL, optically stimulated luminescence, OSL, infrared stimulated luminescence, IRSL) applied to quartz and feldspar against independent age control. The other study site is the monogenetic Lake Nyos Maar as part of the Cameroon Volcanic Line, having killed 1,700 people in 1986 following the release of large amounts of CO2. Previous dating efforts of the last explosive activity are inconsistent and yielded age estimates ranging from 400 a (14C) to >350 ka (K-Ar) (Aka et al. 2008). Our results demonstrate that multiple

  1. Correlation Between Cone Penetration Rate And Measured Cone Penetration Parameters In Silty Soils

    DEFF Research Database (Denmark)

    Poulsen, Rikke; Nielsen, Benjaminn Nordahl; Ibsen, Lars Bo

    2013-01-01

    This paper shows, how a change in cone penetration rate affects the cone penetration measurements, hence the cone resistance, pore pressure, and sleeve friction in silty soil. The standard rate of penetration is 20 mm/s, and it is generally accepted that undrained penetration occurs in clay while...... penetration tests with varying penetration rates conducted at a test site where the subsoil primary consists of sandy silt. It is shown how a reduced penetration rate influences the cone penetration measurements e.g. the cone resistance, pore pressure, and sleeve friction....

  2. Weighted vaginal cones for urinary incontinence.

    Science.gov (United States)

    Herbison, G Peter; Dean, Nicola

    2013-07-08

    For a long time pelvic floor muscle training (PFMT) has been the most common form of conservative (non-surgical) treatment for stress urinary incontinence (SUI). Weighted vaginal cones can be used to help women to train their pelvic floor muscles. Cones are inserted into the vagina and the pelvic floor is contracted to prevent them from slipping out. The objective of this review is to determine the effectiveness of vaginal cones in the management of female urinary stress incontinence (SUI).We wished to test the following comparisons in the management of stress incontinence: 1. vaginal cones versus no treatment; 2. vaginal cones versus other conservative therapies, such as PFMT and electrostimulation; 3. combining vaginal cones and another conservative therapy versus another conservative therapy alone or cones alone; 4. vaginal cones versus non-conservative methods, for example surgery or injectables.Secondary issues which were considered included whether:1. it takes less time to teach women to use cones than it does to teach the pelvic floor exercise; 2. self-taught use is effective;3. the change in weight of the heaviest cone that can be retained is related to the level of improvement;4. subgroups of women for whom cone use may be particularly effective can be identified. We searched the Cochrane Incontinence Group Specialised Trials Register (searched 19 September 2012), MEDLINE (January 1966 to March 2013), EMBASE (January 1988 to March 2013) and reference lists of relevant articles. Randomised or quasi-randomised controlled trials comparing weighted vaginal cones with alternative treatments or no treatment. Two reviewers independently assessed studies for inclusion and trial quality. Data were extracted by one reviewer and cross-checked by the other. Study authors were contacted for extra information. We included 23 trials involving 1806 women, of whom 717 received cones. All of the trials were small, and in many the quality was hard to judge. Outcome measures

  3. Volcanisms and Earthquakes Related to the Pacific Plate Subduction in Northeast Asia

    Science.gov (United States)

    Liu, J.; Chen, X.

    2012-04-01

    It is very known that an integrated plate system displays in Northeast Asia from the Pacific Plate subduction zone via arc islands and back-arc basin to the continental margin with rifting system. Based on this geological background many huge earthquakes and volcanic eruptions occurred in this area from the Mesozoic to the present such as Fujiyama Volcano in Japan, Cheju Volcano in South Korea, Changbaishan Volcano in China and M 7.3 deep focus earthquake in Wangqing, Northeast China of June 28,2002, M9 earthquake in Northeast Japan of March 11,2011 and so on. Now it is tectonic active phase in the Northeast Asia, even in the globe. The Changbaishan Volcano is huge volcanic group with some 12-103 km2 area and hundreds volcanic cones crossed the boundary between China and Korea covered 41° -42.5° latitude north and 127° -129° longitude east. It is among largest active and dangerous volcanoes on the Globe and composed of three main volcanoes (eruptive centers): Tianchi(2755 m a.s.l.), Wangtian'e (2438m a.s.l.) and South Paotaishan (2434m a.s.l.), which distribution assumes as tripod. These three eruptive centers have similar magma system and different ages. They were built from the Early Miocene to the Recent by basaltic flow as lava plateau, trachyte composing of volcanic cones and pyroclastic deposits covering the tops of the mountains and other places. Tianchi volcano is younger than others. According to historic documents the largest eruption of Tianchi volcano occurred in 1014-1019 AD., after that there were still several eruptions until 1903 AD. The frequencies of Changbaishan volcanic eruptions corresponded to those of the Pacific, especially Japan. There is systematic magma evolution from basic basalt, intermediate trachyte to acid pantellerite with 87Sr/86Sr 0.704771-0.710096, 143Nd/144Nd 0.512487-0.512602, which indicated that the magma derived from rich mantle. Geophysical data reveal a buried magmatic reservoir is lying below the volcanoes. Recently

  4. Cone Penetrometer N Factor Determination Testing Results

    Energy Technology Data Exchange (ETDEWEB)

    Follett, Jordan R.

    2014-03-05

    This document contains the results of testing activities to determine the empirical 'N Factor' for the cone penetrometer in kaolin clay simulant. The N Factor is used to releate resistance measurements taken with the cone penetrometer to shear strength.

  5. A Hydraulically Operated Pine Cone Cutter

    Science.gov (United States)

    Carl W. Fatzinger; M.T. Proveaux

    1971-01-01

    Mature cones of slash pine (Pinus elliottii Engelm. var. elliottii) and longleaf pine (P. palustris Mill.) can be easily bisected along their longitudinal axes with the hydraulic pine cone cutter described. This cutter eliminates the two major problems of earlier models--undue operator fatigue and the...

  6. Cones and foci for protocol verification revisited

    NARCIS (Netherlands)

    W.J. Fokkink (Wan); J. Pang

    2002-01-01

    textabstractWe define a cones and foci proof method, which rephrases the question whether two system specifications are branching bisimilar in terms of proof obligations on relations between data objects. Compared to the original cones and foci method from Groote and Springintveld cite{GroSpr01},

  7. Cone calorimeter tests of wood composites

    Science.gov (United States)

    Robert H. White; Kuma Sumathipala

    2013-01-01

    The cone calorimeter is widely used for the determination of the heat release rate (HRR) of building products and other materials. As part of an effort to increase the availability of cone calorimeter data on wood products, the U.S. Forest Products Laboratory and the American Wood Council conducted this study on composite wood products in cooperation with the Composite...

  8. Terminal Pleistocene to early Holocene volcanic eruptions at Zuni Salt Lake, west-central New Mexico, USA

    Science.gov (United States)

    Onken, Jill; Forman, Steven

    2017-01-01

    Zuni Salt Lake (ZSL) is a large maar in the Red Hill-Quemado volcanic field located in west-central New Mexico in the southwestern USA. Stratigraphic analysis of sections in and around the maar, coupled with optically stimulated luminescence (OSL) and accelerator mass spectrometry (AMS) 14C dating, indicate that ZSL volcanic activity occurred between ˜13.4 and 9.9 ka and was most likely confined to a ≤500-year interval sometime between ˜12.3 and 11.0 ka. The basal volcanic unit consists of locally widespread basaltic ash fallout interpreted to represent a violent or wind-aided strombolian eruption tentatively attributed to Cerro Pomo, a scoria cone ˜10 km south of ZSL. Subsequent eruptions emanated from vents near or within the present-day ZSL maar crater. Strombolian eruptions of multiple spatter and scoria cones produced basaltic lava and scoria lapilli fallout. Next, a phreatomagmatic eruption created the maar crater and surrounding tephra rim and apron. ZSL eruptions ended with strombolian eruptions that formed three scoria cones on the crater floor. The revised age range of ZSL is younger and more precise than the 190-24 ka 2-sigma age range derived from previous argon dating. This implies that other morphologically youthful, argon-dated volcanoes on the southern margin of the Colorado Plateau might be substantially younger than previously reported.

  9. Double Dirac cones in phononic crystals

    KAUST Repository

    Li, Yan

    2014-07-07

    A double Dirac cone is realized at the center of the Brillouin zone of a two-dimensional phononic crystal (PC) consisting of a triangular array of core-shell-structure cylinders in water. The double Dirac cone is induced by the accidental degeneracy of two double-degenerate Bloch states. Using a perturbation method, we demonstrate that the double Dirac cone is composed of two identical and overlapping Dirac cones whose linear slopes can also be accurately predicted from the method. Because the double Dirac cone occurs at a relatively low frequency, a slab of the PC can be mapped onto a slab of zero refractive index material by using a standard retrieval method. Total transmission without phase change and energy tunneling at the double Dirac point frequency are unambiguously demonstrated by two examples. Potential applications can be expected in diverse fields such as acoustic wave manipulations and energy flow control.

  10. The Volcanism Ontology (VO): a model of the volcanic system

    Science.gov (United States)

    Myer, J.; Babaie, H. A.

    2017-12-01

    We have modeled a part of the complex material and process entities and properties of the volcanic system in the Volcanism Ontology (VO) applying several top-level ontologies such as Basic Formal Ontology (BFO), SWEET, and Ontology of Physics for Biology (OPB) within a single framework. The continuant concepts in BFO describe features with instances that persist as wholes through time and have qualities (attributes) that may change (e.g., state, composition, and location). In VO, the continuants include lava, volcanic rock, and volcano. The occurrent concepts in BFO include processes, their temporal boundaries, and the spatio-temporal regions within which they occur. In VO, these include eruption (process), the onset of pyroclastic flow (temporal boundary), and the space and time span of the crystallization of lava in a lava tube (spatio-temporal region). These processes can be of physical (e.g., debris flow, crystallization, injection), atmospheric (e.g., vapor emission, ash particles blocking solar radiation), hydrological (e.g., diffusion of water vapor, hot spring), thermal (e.g., cooling of lava) and other types. The properties (predicates) relate continuants to other continuants, occurrents to continuants, and occurrents to occurrents. The ontology also models other concepts such as laboratory and field procedures by volcanologists, sampling by sensors, and the type of instruments applied in monitoring volcanic activity. When deployed on the web, VO will be used to explicitly and formally annotate data and information collected by volcanologists based on domain knowledge. This will enable the integration of global volcanic data and improve the interoperability of software that deal with such data.

  11. Geology of Newberry National Volcanic Monument, Oregon, USA

    Science.gov (United States)

    Donnelly-Nolan, J. M.; Jensen, R. A.; Robinson, J. E.

    2014-12-01

    Volcanic geology is the dominant theme at Newberry National Volcanic Monument in central Oregon. Established almost 25 years ago, the NNVM (like the Mt. St. Helens National Volcanic Monument) is managed by the U.S. Forest Service. The monument encompasses some 90 square miles in Deschutes National Forest of the 1200-sq-mi Newberry Volcano, including the 4x5 mi scenic central caldera and the volcano's youngest lava flow, the 1300-yr-old Big Obsidian Flow. The seismically-monitored Newberry Volcano is considered by the USGS to be a very high threat volcano, with the potential to impact adjacent populations in Bend, Sunriver, and LaPine and damage infrastructure including highways, railroads, and power lines. Unspectacular from a distance, the broad shield shape of Newberry Volcano hides the abundance and youthfulness of volcanic activity. Included in NNVM are 7-ka basalt to andesite lavas of the Northwest Rift Zone (NWRZ) that erupted from spatter and cinder cones over a N-S distance of 20 miles and temporarily blocked the flow of the adjacent Deschutes River. These well-exposed lavas are post-Mazama in age, having erupted after a blanket of ash and pumice was deposited on the volcano when Mt. Mazama erupted at 7.7 ka to form Crater Lake. Images from lidar data obtained in 2011 clearly display the post-Mazama lavas, which not only are unmantled by the tephra, but also lack the thick forest that has grown in the tephra further obscuring many of the youthful volcanic features across this massive rear-arc Cascades volcano. NNVM features interpretive trails at the Big Obsidian Flow in the caldera and at Lava Cast Forest and Lava Butte flow along the NWRZ. Also within the monument are two of the premier drivable viewpoints in Oregon, on Lava Butte and at the 7984-ft top of Paulina Peak on the rim of the caldera. On a clear day, views from Paulina Peak encompass much of the High Cascades, extending from Mt. Shasta in California to Mt. Adams in Washington.

  12. Candidate constructional volcanic edifices on Mercury

    OpenAIRE

    Wright, J.; Rothery, D. A.; Balme, M. R.; Conway, S. J.

    2018-01-01

    [Introduction] Studies using MESSENGER data suggest that Mercury’s crust is predominantly a product of effusive volcanism that occurred in the first billion years following the planet’s formation. Despite this planet-wide effusive volcanism, no constructional volcanic edifices, characterized by a topographic rise, have hitherto been robustly identified on Mercury, whereas constructional volcanoes are common on other planetary bodies in the solar system with volcanic histories. Here, we descri...

  13. Disruptive event analysis: volcanism and igneous intrusion

    International Nuclear Information System (INIS)

    Crowe, B.M.

    1979-01-01

    Three basic topics are addressed for the disruptive event analysis: first, the range of disruptive consequences of a radioactive waste repository by volcanic activity; second, the possible reduction of the risk of disruption by volcanic activity through selective siting of a repository; and third, the quantification of the probability of repository disruption by volcanic activity

  14. A Conceptual Model of Future Volcanism at Medicine Lake Volcano, California - With an Emphasis on Understanding Local Volcanic Hazards

    Science.gov (United States)

    Molisee, D. D.; Germa, A.; Charbonnier, S. J.; Connor, C.

    2017-12-01

    Medicine Lake Volcano (MLV) is most voluminous of all the Cascade Volcanoes ( 600 km3), and has the highest eruption frequency after Mount St. Helens. Detailed mapping by USGS colleagues has shown that during the last 500,000 years MLV erupted >200 lava flows ranging from basalt to rhyolite, produced at least one ash-flow tuff, one caldera forming event, and at least 17 scoria cones. Underlying these units are 23 additional volcanic units that are considered to be pre-MLV in age. Despite the very high likelihood of future eruptions, fewer than 60 of 250 mapped volcanic units (MLV and pre-MLV) have been dated reliably. A robust set of eruptive ages is key to understanding the history of the MLV system and to forecasting the future behavior of the volcano. The goals of this study are to 1) obtain additional radiometric ages from stratigraphically strategic units; 2) recalculate recurrence rate of eruptions based on an augmented set of radiometric dates; and 3) use lava flow, PDC, ash fall-out, and lahar computational simulation models to assess the potential effects of discrete volcanic hazards locally and regionally. We identify undated target units (units in key stratigraphic positions to provide maximum chronological insight) and obtain field samples for radiometric dating (40Ar/39Ar and K/Ar) and petrology. Stratigraphic and radiometric data are then used together in the Volcano Event Age Model (VEAM) to identify changes in the rate and type of volcanic eruptions through time, with statistical uncertainty. These newly obtained datasets will be added to published data to build a conceptual model of volcanic hazards at MLV. Alternative conceptual models, for example, may be that the rate of MLV lava flow eruptions are nonstationary in time and/or space and/or volume. We explore the consequences of these alternative models on forecasting future eruptions. As different styles of activity have different impacts, we estimate these potential effects using simulation

  15. A Volcanic Hydrogen Habitable Zone

    International Nuclear Information System (INIS)

    Ramirez, Ramses M.; Kaltenegger, Lisa

    2017-01-01

    The classical habitable zone (HZ) is the circular region around a star in which liquid water could exist on the surface of a rocky planet. The outer edge of the traditional N 2 –CO 2 –H 2 O HZ extends out to nearly ∼1.7 au in our solar system, beyond which condensation and scattering by CO 2 outstrips its greenhouse capacity. Here, we show that volcanic outgassing of atmospheric H 2 can extend the outer edge of the HZ to ∼2.4 au in our solar system. This wider volcanic-hydrogen HZ (N 2 –CO 2 –H 2 O–H 2 ) can be sustained as long as volcanic H 2 output offsets its escape from the top of the atmosphere. We use a single-column radiative-convective climate model to compute the HZ limits of this volcanic hydrogen HZ for hydrogen concentrations between 1% and 50%, assuming diffusion-limited atmospheric escape. At a hydrogen concentration of 50%, the effective stellar flux required to support the outer edge decreases by ∼35%–60% for M–A stars. The corresponding orbital distances increase by ∼30%–60%. The inner edge of this HZ only moves out ∼0.1%–4% relative to the classical HZ because H 2 warming is reduced in dense H 2 O atmospheres. The atmospheric scale heights of such volcanic H 2 atmospheres near the outer edge of the HZ also increase, facilitating remote detection of atmospheric signatures.

  16. A Volcanic Hydrogen Habitable Zone

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, Ramses M.; Kaltenegger, Lisa, E-mail: rmr277@cornell.edu [Carl Sagan Institute, Cornell University, Ithaca, NY (United States)

    2017-03-01

    The classical habitable zone (HZ) is the circular region around a star in which liquid water could exist on the surface of a rocky planet. The outer edge of the traditional N{sub 2}–CO{sub 2}–H{sub 2}O HZ extends out to nearly ∼1.7 au in our solar system, beyond which condensation and scattering by CO{sub 2} outstrips its greenhouse capacity. Here, we show that volcanic outgassing of atmospheric H{sub 2} can extend the outer edge of the HZ to ∼2.4 au in our solar system. This wider volcanic-hydrogen HZ (N{sub 2}–CO{sub 2}–H{sub 2}O–H{sub 2}) can be sustained as long as volcanic H{sub 2} output offsets its escape from the top of the atmosphere. We use a single-column radiative-convective climate model to compute the HZ limits of this volcanic hydrogen HZ for hydrogen concentrations between 1% and 50%, assuming diffusion-limited atmospheric escape. At a hydrogen concentration of 50%, the effective stellar flux required to support the outer edge decreases by ∼35%–60% for M–A stars. The corresponding orbital distances increase by ∼30%–60%. The inner edge of this HZ only moves out ∼0.1%–4% relative to the classical HZ because H{sub 2} warming is reduced in dense H{sub 2}O atmospheres. The atmospheric scale heights of such volcanic H{sub 2} atmospheres near the outer edge of the HZ also increase, facilitating remote detection of atmospheric signatures.

  17. The southern cone petroleum market

    International Nuclear Information System (INIS)

    Pisani, W.

    1992-01-01

    The Argentine oil sector has been moving strongly toward complete deregulation since 1989. Price controls on byproducts has been lifted, old petroleum contracts became into concessions, and the state oil company, YPF, is under process of privatization. In this context, the international companies scouting for opportunities can find an important menu of potential investments But here remain some problems connected with this deregulation, too. The lack of a reference crude and product market price is one of them. This paper focuses how to overcome this trouble with the establishment of an institutional market for crude and products, not only for Argentina but also for the entire Southern Cone Region (Argentina, Bolivia, Brazil, Chile, Paraguay and Uruguay), inquiring into the benefits of its creation

  18. Lyapunov Functions and Cone Families

    Science.gov (United States)

    Barreira, Luis; Dragičević, Davor; Valls, Claudia

    2012-07-01

    We describe systematically the relation between Lyapunov functions and nonvanishing Lyapunov exponents, both for maps and flows. This includes a brief survey of the existing results in the area. In particular, we consider separately the cases of nonpositive and arbitrary Lyapunov functions, thus yielding optimal criteria for negativity and positivity of the Lyapunov exponents of linear cocycles over measure-preserving transformations. Moreover, we describe converse results of these criteria with the explicit construction of eventually strict Lyapunov functions for any map or flow with nonzero Lyapunov exponents. We also construct examples showing that in general the existence of an eventually strict invariant cone family does not imply the existence of an eventually strict Lyapunov function.

  19. Dirac cones in isogonal hexagonal metallic structures

    Science.gov (United States)

    Wang, Kang

    2018-03-01

    A honeycomb hexagonal metallic lattice is equivalent to a triangular atomic one and cannot create Dirac cones in its electromagnetic wave spectrum. We study in this work the low-frequency electromagnetic band structures in isogonal hexagonal metallic lattices that are directly related to the honeycomb one and show that such structures can create Dirac cones. The band formation can be described by a tight-binding model that allows investigating, in terms of correlations between local resonance modes, the condition for the Dirac cones and the consequence of the third structure tile sustaining an extra resonance mode in the unit cell that induces band shifts and thus nonlinear deformation of the Dirac cones following the wave vectors departing from the Dirac points. We show further that, under structure deformation, the deformations of the Dirac cones result from two different correlation mechanisms, both reinforced by the lattice's metallic nature, which directly affects the resonance mode correlations. The isogonal structures provide new degrees of freedom for tuning the Dirac cones, allowing adjustment of the cone shape by modulating the structure tiles at the local scale without modifying the lattice periodicity and symmetry.

  20. Global Martian volcanism as a new interpretation of geological past of terrestrial bodies and moons in the Solar System

    Science.gov (United States)

    Zalewska, N.

    2017-09-01

    When we look at the volcanic cones and the various other volcanic forms on Earth, we also notice that craters, especially those that are inactive for millions of years, are strikingly similar to the conically formed domes and caldera craters on Mars and terrestrial planets, additionally including moons of Jupiter and moons of other large planets as well as our Moon. The difference between the impact crater and the volcanic crater on terrestrial bodies can be very difficult to recognize because of close similarity between them, especially in morphology as well as the geometric distortion of images made by spectrometers in the nadir. In this case, the geochemistry and the degree of melting or lack there at the moment of impact must be taken into account. Whether shocked varieties of quartz are found in the crater or not, will tell us which phenomenon occurred. This would require precise on site research using rovers.

  1. Cone penetrometer moisture probe acceptance test report

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, G.A.

    1996-04-23

    This Acceptance Test Report (ATR) documents the results of WHC-SD-WM-ATP-146 (Prototype Cone Penetrometer Moisture Probe Acceptance Test Procedure) and WHC-SD-WM-ATP-145 (Cone Penetrometer Moisture Probe Acceptance Test Procedure). The master copy of WHC-SD-WM-ATP-145 can be found in Appendix A and the master copy of WHC-SD-WM-ATP-146 can be found in Appendix B. Also included with this report is a matrix showing design criteria of the cone penetrometer moisture probe and the verification method used (Appendix C).

  2. Potential volcanic impacts on future climate variability

    Science.gov (United States)

    Bethke, Ingo; Outten, Stephen; Otterå, Odd Helge; Hawkins, Ed; Wagner, Sebastian; Sigl, Michael; Thorne, Peter

    2017-11-01

    Volcanic activity plays a strong role in modulating climate variability. Most model projections of the twenty-first century, however, under-sample future volcanic effects by not representing the range of plausible eruption scenarios. Here, we explore how sixty possible volcanic futures, consistent with ice-core records, impact climate variability projections of the Norwegian Earth System Model (NorESM) under RCP4.5 (ref. ). The inclusion of volcanic forcing enhances climate variability on annual-to-decadal timescales. Although decades with negative global temperature trends become ~50% more commonplace with volcanic activity, these are unlikely to be able to mitigate long-term anthropogenic warming. Volcanic activity also impacts probabilistic projections of global radiation, sea level, ocean circulation, and sea-ice variability, the local-scale effects of which are detectable when quantifying the time of emergence. These results highlight the importance and feasibility of representing volcanic uncertainty in future climate assessments.

  3. A Study by Remote Sensing Methods of Volcanism at Craters of the Moon National Park, Idaho

    Science.gov (United States)

    Haberle, C. W.; Hughes, S. S.; Kobs-Nawotniak, S. E.; Lim, D. S. S.; Garry, B.; Sears, D. W. G.; Downs, M.; Busto, J.; Skok, J. R.; Elphic, R. C.; Kobayashi, L.; Heldmann, J. L.; Christensen, P. R.

    2014-12-01

    Craters of the Moon (COTM) National Park, on the eastern Snake River Plain, and its associated lava fields are currently a focus of the NASA SSERVI FINESSE (Field Investigations to Enable Solar System Science and Exploration) team. COTM was selected for study owing to similarities with volcanic features observed on the Moon, Mars and Vesta. The COTM basaltic lava fields emanate from an 80 km long rift zone where at least eight eruptive episodes, occurring 15,000 to 2,000 BP, have created an expansive volcanic field covering an area of approximately 1,650 km2. This polygenetic volcanic field hosts a diverse collection of basaltic volcanic edifices such as phreatic explosion craters, eruptive fissures, cinder cones, spatter cones, shield volcanoes and expansive lava flows. Engineering challenges and high cost limit the number of robotic and human field investigations of planetary bodies and, due to these constraints, exhaustive remote sensing investigations of planetary surface properties are undertaken prior to field deployment. This creates an unavoidable dependence upon remote sensing, a critical difference between field investigations of planetary bodies and most terrestrial field investigations. Studies of this nature have utility in terrestrial investigations as they can help link spatially encompassing datasets and conserve field resources. We present preliminary results utilizing Earth orbital datasets to determine the efficacy of products derived from remotely sensed data when compared to geologic field observations. Multispectral imaging data (ASTER, AVIRIS, TIMS) collected at a range of spatial and spectral resolutions are paired with high resolution imagery from both orbit and unmanned aircraft systems. This enables the creation of derived products detailing morphology, compositional variation, mineralogy, relative age and vegetation. The surface morphology of flows within COTM differs from flow to flow and observations of these properties can aid in

  4. Genetics Home Reference: cone-rod dystrophy

    Science.gov (United States)

    ... common cause of autosomal recessive cone-rod dystrophy , accounting for 30 to 60 percent of cases. At ... Patient Support and Advocacy Resources (4 links) American Foundation for the Blind Foundation Fighting Blindness Retina International ...

  5. Work plan for cone penetrometer comparison testing.

    Science.gov (United States)

    2011-01-01

    The work plan and experimental design are developed around aiding engineers and geologists within the : Wisconsin Department of Transportation to understand the mechanisms controlling cone penetration test : results so that they can decide when the t...

  6. Venus volcanism and El Chichon

    Science.gov (United States)

    Bell, Peter M.

    Reinterpretations of telemetry data returned to earth from the Pioneer Venus Orbiter suggest that the surface of Venus may be characterized by violent immense volcanic activity. L.W. Esposito has made an interactive analysis of Pioneer ultraviolet spectral data and similar data from the earth's atmosphere [Science, 223, 1072-1074, 1984]. Spacecraft analysis of sulfur dioxide in the earth's upper atmosphere, apparently released by El Chich[acu]on, Mexico, in March 1982 (EOS, June 14, 1983, p. 411, and August 16, 1983, p. 506) prompted reanalysis of accumulated Pioneer ultraviolet data. Massive injections of sulfur dioxide into the Venus atmosphere could be the result of volcanic eruptions about the size of the Krakatoa explosive eruption that took place between Java and Summatra in 1883.

  7. Source mechanisms of volcanic tsunamis.

    Science.gov (United States)

    Paris, Raphaël

    2015-10-28

    Volcanic tsunamis are generated by a variety of mechanisms, including volcano-tectonic earthquakes, slope instabilities, pyroclastic flows, underwater explosions, shock waves and caldera collapse. In this review, we focus on the lessons that can be learnt from past events and address the influence of parameters such as volume flux of mass flows, explosion energy or duration of caldera collapse on tsunami generation. The diversity of waves in terms of amplitude, period, form, dispersion, etc. poses difficulties for integration and harmonization of sources to be used for numerical models and probabilistic tsunami hazard maps. In many cases, monitoring and warning of volcanic tsunamis remain challenging (further technical and scientific developments being necessary) and must be coupled with policies of population preparedness. © 2015 The Author(s).

  8. Uranium deposits in volcanic rocks

    International Nuclear Information System (INIS)

    1985-01-01

    Twenty-eight papers were presented at the meeting and two additional papers were provided. Three panels were organized to consider the specific aspects of the genesis of uranium deposits in volcanic rocks, recognition criteria for the characterization of such deposits, and approaches to exploration. The papers presented and the findings of the panels are included in the Proceedings. Separate abstracts were prepared for each of these papers

  9. On the Kleiman-Mori cone

    OpenAIRE

    Fujino, Osamu

    2005-01-01

    The Kleiman-Mori cone plays important roles in the birational geometry. In this paper, we construct complete varieties whose Kleiman-Mori cones have interesting properties. First, we construct a simple and explicit example of complete non-projective singular varieties for which Kleiman's ampleness criterion does not hold. More precisely, we construct a complete non-projective toric variety $X$ and a line bundle $L$ on $X$ such that $L$ is positive on $\\overline{\\mathit{NE...

  10. Light-cone superspace BPS theory

    Science.gov (United States)

    Hearin, Patrick

    2011-05-01

    The BPS bound is formulated in light-cone superspace for the N=4 super-Yang-Mills theory. As a consequence of the superalgebra all momenta are shown to be expressed as a quadratic form in the relevant supertransformations, and these forms are used to derive the light-cone superspace BPS equations. Finally, the superfield expressions are expanded out to component form, and the Wu-Yang monopole boosted to the infinite momentum frame is shown to be a solution.

  11. A novel mechanism of cone photoreceptor adaptation.

    Directory of Open Access Journals (Sweden)

    Marcus H C Howlett

    2017-04-01

    Full Text Available An animal's ability to survive depends on its sensory systems being able to adapt to a wide range of environmental conditions, by maximizing the information extracted and reducing the noise transmitted. The visual system does this by adapting to luminance and contrast. While luminance adaptation can begin at the retinal photoreceptors, contrast adaptation has been shown to start at later stages in the retina. Photoreceptors adapt to changes in luminance over multiple time scales ranging from tens of milliseconds to minutes, with the adaptive changes arising from processes within the phototransduction cascade. Here we show a new form of adaptation in cones that is independent of the phototransduction process. Rather, it is mediated by voltage-gated ion channels in the cone membrane and acts by changing the frequency response of cones such that their responses speed up as the membrane potential modulation depth increases and slow down as the membrane potential modulation depth decreases. This mechanism is effectively activated by high-contrast stimuli dominated by low frequencies such as natural stimuli. However, the more generally used Gaussian white noise stimuli were not effective since they did not modulate the cone membrane potential to the same extent. This new adaptive process had a time constant of less than a second. A critical component of the underlying mechanism is the hyperpolarization-activated current, Ih, as pharmacologically blocking it prevented the long- and mid- wavelength sensitive cone photoreceptors (L- and M-cones from adapting. Consistent with this, short- wavelength sensitive cone photoreceptors (S-cones did not show the adaptive response, and we found they also lacked a prominent Ih. The adaptive filtering mechanism identified here improves the information flow by removing higher-frequency noise during lower signal-to-noise ratio conditions, as occurs when contrast levels are low. Although this new adaptive mechanism can

  12. Modified superstring in light cone gauge

    International Nuclear Information System (INIS)

    Kamimura, Kiyoshi; Tatewaki, Machiko.

    1988-01-01

    We analyze the covariant superstring theory proposed by Siegel in light cone gauge. The physical states are the direct product of those of Green-Schwarz Superstring and the additional internal space spanned by light cone spinors. At clasical level, there is no difference among observables in Siegel's modified Superstring theory (SMST) and Green-Schwarz's one (GSST). However SMST can not be quantized with additional constraints as the physical state conditions. (author)

  13. Design of a trichromatic cone array.

    Directory of Open Access Journals (Sweden)

    Patrick Garrigan

    2010-02-01

    Full Text Available Cones with peak sensitivity to light at long (L, medium (M and short (S wavelengths are unequal in number on the human retina: S cones are rare (<10% while increasing in fraction from center to periphery, and the L/M cone proportions are highly variable between individuals. What optical properties of the eye, and statistical properties of natural scenes, might drive this organization? We found that the spatial-chromatic structure of natural scenes was largely symmetric between the L, M and S sensitivity bands. Given this symmetry, short wavelength attenuation by ocular media gave L/M cones a modest signal-to-noise advantage, which was amplified, especially in the denser central retina, by long-wavelength accommodation of the lens. Meanwhile, total information represented by the cone mosaic remained relatively insensitive to L/M proportions. Thus, the observed cone array design along with a long-wavelength accommodated lens provides a selective advantage: it is maximally informative.

  14. Volcanism and associated hazards: The Andean perspective

    Science.gov (United States)

    Tilling, R.I.

    2009-01-01

    Andean volcanism occurs within the Andean Volcanic Arc (AVA), which is the product of subduction of the Nazca Plate and Antarctica Plates beneath the South America Plate. The AVA is Earth's longest but discontinuous continental-margin volcanic arc, which consists of four distinct segments: Northern Volcanic Zone, Central Volcanic Zone, Southern Volcanic Zone, and Austral Volcanic Zone. These segments are separated by volcanically inactive gaps that are inferred to indicate regions where the dips of the subducting plates are too shallow to favor the magma generation needed to sustain volcanism. The Andes host more volcanoes that have been active during the Holocene (past 10 000 years) than any other volcanic region in the world, as well as giant caldera systems that have produced 6 of the 47 largest explosive eruptions (so-called "super eruptions") recognized worldwide that have occurred from the Ordovician to the Pleistocene. The Andean region's most powerful historical explosive eruption occurred in 1600 at Huaynaputina Volcano (Peru). The impacts of this event, whose eruptive volume exceeded 11 km3, were widespread, with distal ashfall reported at distances >1000 km away. Despite the huge size of the Huaynaputina eruption, human fatalities from hazardous processes (pyroclastic flows, ashfalls, volcanogenic earthquakes, and lahars) were comparatively small owing to the low population density at the time. In contrast, lahars generated by a much smaller eruption (Chile, Colombia, Ecuador, and Peru has spurred significant improvements in reducing volcano risk in the Andean region. But much remains to be done.

  15. Disruptive event analysis: volcanism and igneous intrusion

    International Nuclear Information System (INIS)

    Crowe, B.M.

    1980-08-01

    An evaluation is made of the disruptive effects of volcanic activity with respect to long term isolation of radioactive waste through deep geologic storage. Three major questions are considered. First, what is the range of disruption effects of a radioactive waste repository by volcanic activity. Second, is it possible, by selective siting of a repository, to reduce the risk of disruption by future volcanic activity. And third, can the probability of repository disruption by volcanic activity be quantified. The main variables involved in the evaluation of the consequences of repository disruption by volcanic activity are the geometry of the magma-repository intersection (partly controlled by depth of burial) and the nature of volcanism. Potential radionuclide dispersal by volcanic transport within the biosphere ranges in distance from several kilometers to global. Risk from the most catastrophic types of eruptions can be reduced by careful site selection to maximize lag time prior to the onset of activity. Certain areas or volcanic provinces within the western United States have been sites of significant volcanism and should be avoided as potential sites for a radioactive waste repository. Examples of projection of future sites of active volcanism are discussed for three areas of the western United States. Probability calculations require two types of data: a numerical rate or frequency of volcanic activity and a numerical evaluation of the areal extent of volcanic disruption for a designated region. The former is clearly beyond the current state of art in volcanology. The latter can be approximated with a reasonable degree of satisfaction. In this report, simplified probability calculations are attempted for areas of past volcanic activity

  16. Stratigraphy, sedimentology and eruptive mechanisms in the tuff cone of El Golfo (Lanzarote, Canary Islands)

    Science.gov (United States)

    Pedrazzi, Dario; Martí, Joan; Geyer, Adelina

    2013-07-01

    The tuff cone of El Golfo on the western coast of Lanzarote (Canary Islands) is a typical hydrovolcanic edifice. Along with other edifices of the same age, it was constructed along a fracture oriented NEE-SWW that coincides with the main structural trend of recent volcanism in this part of the island. We conducted a detailed stratigraphic study of the succession of deposits present in this tuff cone and here interpret them in light of the depositional processes and eruptive dynamics that we were able to infer. The eruptive sequence is represented by a succession of pyroclastic deposits, most of which were emplaced by flow, plus a number of air-fall deposits and ballistic blocks and bombs. We distinguished five different eruptive/depositional stages on the basis of differences in inferred current flow regimes and fragmentation efficiencies represented by the resulting deposits; the different stages may be related to variations in the explosive energy. Eight lithofacies were identified based on sedimentary discontinuities, grain size, components, variations in primary laminations and bedforms. The volcanic edifice was constructed very rapidly around the vent, and this is inferred to have controlled the amount of water that was able to enter the eruption conduit. The sedimentological characteristics of the deposits and the nature and distribution of palagonitic alteration suggest that most of the pyroclastic succession in El Golfo was deposited in a subaerial environment. This type of hydrovolcanic explosive activity is common in the coastal zones of Lanzarote and the other Canary Islands and is one of the main potential hazards that could threaten the human population of this archipelago. Detailed studies of these hydrovolcanic eruptions such as the one we present here can help volcanologists understand the hazards that this type of eruption can generate and provide essential information for undertaking risk assessment in similar volcanic environments.

  17. Global CO2 Emission from Volcanic Lakes

    Science.gov (United States)

    Perez, N.; Hernandez Perez, P. A.; Padilla, G.; Melian Rodriguez, G.; Padron, E.; Barrancos, J.; Calvo, D.; Kusukabe, M.; Mori, T.; Nolasco, D.

    2009-12-01

    During the last two decades, scientists have paid attention to CO2 volcanic emissions and its contribution to the global C budget. Excluding MORBs as a net source of CO2 to the atmosphere, the global CO2 discharge from subaerial volcanism has been estimated about 300 Mt y-1 and this rate accounts for both visible (plume & fumaroles) and non-visible (diffuse) volcanic gas emanations (Mörner & Etíope, 2002). However, CO2 emissions from volcanic lakes have not been considered to estimate the global CO2 discharge from subaerial volcanoes. In order to improve this global CO2 emission rate and estimate the global CO2 emission from volcanic lakes, an extensive research on CO2 emission of volcanic lakes from Phillipines, Nicaragua, Guatemala, Mexico, Indonesia, Germany, France, Cameroon, Costa Rica, El Salvador and Ecuador had been recently carried out. In-situ measurements of CO2 efflux from the surface environment of volcanic lakes were performed by means of a modified floating device of the accumulation chamber method. To quantify the total CO2 emission from each volcanic lake, CO2 efflux maps were constructed using sequential Gaussian simulations (sGs). CO2 emission rates were normalized by the lake area (km2), and volcanic lakes were grouped following classification in acid, alkaline and neutral lakes. The observed average normalized CO2 emission rate values increase from alkaline (5.5 t km-2 d-1), neutral (210.0 t km-2 d-1), to acid (676.8 t km-2 d-1) volcanic lakes. Taking into account (i) these normalized CO2 emission rates from 31 volcanic lakes, (ii) the number of volcanic lakes in the world (~ 1100), (iii) the fraction of the investigated alkaline (45%), neutral (39%), and acid (16%) volcanic lakes, and (iv) the average areas of the investigated alkaline (36,8 km2), neutral (3,7 km2), and acid (0,5 km2) volcanic lakes; the global CO2 emission from volcanic lakes is about ~ 182 Mt year-1. This estimated value is about ~ 50% of the actual estimated global CO2

  18. Yang-Mills instantons on cones and sine-cones over nearly Kähler manifolds

    Science.gov (United States)

    Gemmer, Karl-Philip; Lechtenfeld, Olaf; Nölle, Christoph; Popov, Alexander D.

    2011-09-01

    We present a unified eight-dimensional approach to instanton equations on several seven-dimensional manifolds associated to a six-dimensional homogeneous nearly Kähler manifold. The cone over the sine-cone on a nearly Kähler manifold has holonomy group Spin(7) and can befoliated by submanifolds with either holonomy group G 2, a nearly parallel G 2-structure or a cocalibrated G 2-structure. We show that there is a G 2-instanton on each of these seven-dimensional manifolds which gives rise to a Spin(7)-instanton in eight dimensions. The well-known octonionic instantons on {mathbb{R}^7} and {mathbb{R}^8} are contained in our construction as the special cases of an instanton on the cone and on the cone over the sine-cone, both over the six-sphere, respectively.

  19. Felsic Volcanics on the Moon

    Science.gov (United States)

    Jolliff, B. L.; Lawrence, S. J.; Stopar, J.; Braden, S.; Hawke, B. R.; Robinson, M. S.; Glotch, T. D.; Greenhagen, B. T.; Seddio, S. M.

    2012-12-01

    Lunar Reconnaissance Orbiter (LRO) imaging and thermal data provide new morphologic and compositional evidence for features that appear to be expressions of nonmare silicic volcanism. Examples reflecting a range of sizes and volcanic styles include the Gruithuisen and Mairan Domes, and the Hansteen Alpha (H-A) and Compton-Belkovich (C-B) volcanic complexes. In this work we combine new observations with existing compositional remote sensing and Apollo sample data to assess possible origins. Images and digital topographic data at 100 m scale (Wide Angle Camera) and ~0.5 to 2 m (Narrow Angle Camera) reveal (1) slopes on volcanic constructs of ~12° to 27°, (2) potential endogenic summit depressions, (3) small domical features with dense boulder populations, and (4) irregular collapse features. Morphologies in plan view range from the circular to elliptical Gruithuisen γ and δ domes (~340 km2 each), to smaller cumulodomes such as Mairan T and C-B α (~30 km2, each), to the H-A (~375 km2) and C-B (~680 km2) volcanic complexes. Heights range from ~800-1800 m, and most domes are relatively flat-topped or have a central depression. Positions of the Christiansen Feature in LRO Diviner data reflect silicic compositions [1]. Clementine UVVIS-derived FeO varies from ~5 to 10 wt%. Lunar Prospector Th data indicate model values of 20-55 ppm [2,3], which are consistent with compositions ranging from KREEP basalt to lunar granite. The Apollo collection contains small rocks and breccia clasts of felsic/granitic lithologies. Apollo 12 samples include small, pristine and brecciated granitic rock fragments and a large, polymict breccia (12013) consisting of felsic material (quartz & K-feldspar-rich) and mafic phases (similar to KREEP basalt). Many of the evolved lunar rocks have geochemically complementary compositions. The lithologic associations and the lack of samples with intermediate composition suggest a form of magmatic differentiation that produced mafic and felsic

  20. Volcanic deposits in Antarctic snow and ice

    Science.gov (United States)

    Delmas, Robert J.; Legrand, Michel; Aristarain, Alberto J.; Zanolini, FrançOise

    1985-12-01

    Major volcanic eruptions are able to spread large amounts of sulfuric acid all over the world. Acid layers of volcanic origin were detected for the first time a few years ago by Hammer in Greenland ice. The present paper deals with volcanic deposits in the Antarctic. The different methods that can be used to find volcanic acid deposits in snow and ice cores are compared: electrical conductivity, sulfate, and acidity measurements. Numerous snow and ice samples collected at several Antarctic locations were analyzed. The results reveal that the two major volcanic events recorded by H2SO4, fallout in Antarctic ice over the last century are the eruptions of Krakatoa (1883) and Agung (1963), both located at equatorial latitudes in the southern hemisphere. The volcanic signals are found to be particularly well defined at central Antarctic locations apparently in relation to the low snow accumulation rates in these areas. It is demonstrated that volcanic sulfuric acid in snow is not even partially neutralized by ammonia. The possible influence of Antarctic volcanic activity on snow chemistry is also discussed, using the three recent eruptions of the Deception Island volcano as examples. Only one of them seems to have had a significant effect on the chemistry of snow at a location 200 km from this volcano. It is concluded that Antarctic volcanic ice records are less complicated than Greenland records because of the limited number of volcanos in the southern hemisphere and the apparently higher signal to background ratio for acidity in Antarctica than in Greenland.

  1. Volcanic Ash Nephelometer Probe, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced dropsondes that could effectively be guided through atmospheric regions of interest such as volcanic plumes may enable unprecedented observations of...

  2. Nephelometric Dropsonde for Volcanic Ash, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced dropsondes that could effectively be guided through atmospheric regions of interest such as volcanic plumes could enable unprecedented observations of...

  3. Collision-induced post-plateau volcanism: Evidence from a seamount on Ontong Java Plateau

    Science.gov (United States)

    Hanyu, Takeshi; Tejada, Maria Luisa G.; Shimizu, Kenji; Ishizuka, Osamu; Fujii, Toshiyuki; Kimura, Jun-Ichi; Chang, Qing; Senda, Ryoko; Miyazaki, Takashi; Hirahara, Yuka; Vaglarov, Bogdan S.; Goto, Kosuke T.; Ishikawa, Akira

    2017-12-01

    Many seamounts on the Ontong Java Plateau (OJP) occur near the Stewart Arch, a topographic high that extends parallel to the North Solomon Trench along the southern margins of the plateau. Despite the thick sediment cover, several volcanic cones with strong acoustic reflection were discovered on the submarine flank of the Nuugurigia Seamount. From such volcanic cones, basalts were successfully sampled by dredging. Radiometric dating of basalts and ferromanganese encrustation indicate eruption age of 20-25 Ma, significantly younger than the 122 Ma main OJP plateau and post-plateau basalts. The age range coincides with the collision of the OJP with the Solomon Arc. The Nuugurigia basalts geochemically differ from any other rocks sampled on the OJP so far. They are alkali basalts with elevated Sr, low Zr and Hf, and Enriched Mantle-I (EMI)-like isotopic composition. Parental magmas of these alkali basalts may have formed by small-degree melting of peridotitic mantle impregnated with recycled pyroxenite material having enriched geochemical composition in the OJP's mantle root. We conclude that small-volume alkali basalts from the enriched mantle root migrated through faults or fractures caused by the collision along the Stewart Arch to form the seamount. Our results suggest that the collision of the OJP with the Solomon arc played an important role in the origin of similar post-plateau seamounts along the Stewart Arch.

  4. Thermal vesiculation during volcanic eruptions.

    Science.gov (United States)

    Lavallée, Yan; Dingwell, Donald B; Johnson, Jeffrey B; Cimarelli, Corrado; Hornby, Adrian J; Kendrick, Jackie E; von Aulock, Felix W; Kennedy, Ben M; Andrews, Benjamin J; Wadsworth, Fabian B; Rhodes, Emma; Chigna, Gustavo

    2015-12-24

    Terrestrial volcanic eruptions are the consequence of magmas ascending to the surface of the Earth. This ascent is driven by buoyancy forces, which are enhanced by bubble nucleation and growth (vesiculation) that reduce the density of magma. The development of vesicularity also greatly reduces the 'strength' of magma, a material parameter controlling fragmentation and thus the explosive potential of the liquid rock. The development of vesicularity in magmas has until now been viewed (both thermodynamically and kinetically) in terms of the pressure dependence of the solubility of water in the magma, and its role in driving gas saturation, exsolution and expansion during decompression. In contrast, the possible effects of the well documented negative temperature dependence of solubility of water in magma has largely been ignored. Recently, petrological constraints have demonstrated that considerable heating of magma may indeed be a common result of the latent heat of crystallization as well as viscous and frictional heating in areas of strain localization. Here we present field and experimental observations of magma vesiculation and fragmentation resulting from heating (rather than decompression). Textural analysis of volcanic ash from Santiaguito volcano in Guatemala reveals the presence of chemically heterogeneous filaments hosting micrometre-scale vesicles. The textures mirror those developed by disequilibrium melting induced via rapid heating during fault friction experiments, demonstrating that friction can generate sufficient heat to induce melting and vesiculation of hydrated silicic magma. Consideration of the experimentally determined temperature and pressure dependence of water solubility in magma reveals that, for many ascent paths, exsolution may be more efficiently achieved by heating than by decompression. We conclude that the thermal path experienced by magma during ascent strongly controls degassing, vesiculation, magma strength and the effusive

  5. CRALBP supports the mammalian retinal visual cycle and cone vision

    OpenAIRE

    Xue, Yunlu; Shen, Susan Q.; Jui, Jonathan; Rupp, Alan C.; Byrne, Leah C.; Hattar, Samer; Flannery, John G.; Corbo, Joseph C.; Kefalov, Vladimir J.

    2015-01-01

    Mutations in the cellular retinaldehyde-binding protein (CRALBP, encoded by RLBP1) can lead to severe cone photoreceptor-mediated vision loss in patients. It is not known how CRALBP supports cone function or how altered CRALBP leads to cone dysfunction. Here, we determined that deletion of Rlbp1 in mice impairs the retinal visual cycle. Mice lacking CRALBP exhibited M-opsin mislocalization, M-cone loss, and impaired cone-driven visual behavior and light responses. Additionally, M-cone dark ad...

  6. Compound pollen cone in a Paleozoic conifer.

    Science.gov (United States)

    Hernandez-Castillo, G R; Rothwell, G W; Mapes, G

    2001-06-01

    A rich fossil biota from a Pennsylvanian age deposit of eastern North America contains numerous vegetative and fertile specimens that conform to a single species of primitive walchian conifers. Among the specimens is a compound pollen cone that comprises closely spaced, helically arranged, leaf-like bracts with axillary dwarf shoots. The specimen looks superficially similar to an ultimate vegetative conifer shoot, but there are small appendages in the axil of each bract that represent the fertile dwarf shoots. Dwarf shoots consist of an axis that bears sterile scales and sporophylls with erect pollen sacs. Pollen found in the sacs is monosaccate and conforms to the sporae dispersae genus Potonieisporites Bhardwaj. This cone is a compound shoot system that is morphologically equivalent to the ovulate cones of conifers and to the pollen cones of Paleozoic cordaitaleans and modern gnetophytes. Therefore, it is fundamentally different from the simple pollen cones of other fossil and modern conifers. Discovery of this specimen unexpectedly supports molecular studies that predict a close relationship between Coniferales and Gnetales, and provides fossil evidence to help reconcile the discordant phylogenetic hypotheses of seed plant systematics that have been developed from morphological and molecular data.

  7. Resonance cones in non-Maxwellian plasmas

    International Nuclear Information System (INIS)

    Oelerich-Hill, G.; Piel, A.

    1989-01-01

    Resonance cones are studied experimentally in hot drifting plasmas and in various beam--plasma situations. In a drifting plasma the upstream--downstream asymmetry of the main cone is suitable for diagnostics of plasma drifts. The evaluation of electron temperature from the interference pattern is discussed in terms of the low-temperature--low-drift approximation (LTLDA) and by comparing with numerical kinetic theory calculations. In this way the range of applicability of this method is extended above the LTLDA. In a beam--plasma situation, the downstream resonance cone exhibits a new interference pattern, which can be attributed to resonant particle effects. The upstream resonance cone is only slightly affected and is found still applicable for T/sub e/ and n/sub e/ diagnostics. As a result of comparison with numerical calculations, in which the actual distribution function is used, the downstream interference pattern is proposed to be useful as a diagnostic method for obtaining the mean beam energy. The waves generated by the beam--plasma interaction are analyzed by digital cross-correlation techniques, and found to propagate obliquely to the magnetic field direction at the resonance cone angle

  8. Resonance cones in non-Maxwellian plasmas

    International Nuclear Information System (INIS)

    Oelerich-Hill, G.; Piel, A.

    1988-05-01

    Resonance cones are studied experimentally in hot drifting plasmas and in various beam-plasma situations. In a drifting plasma the upstream-downstream asymmetry of the main cone is suitable for diagnostics of plasma drifts. The evaluation of electron temperature from the interference pattern is discussed in terms of the low-temperature-low-drift-approximation (LTLDA) and by comparing with numerical kinetic theory calculations. In this way the range of applicability of this method is extended above the LTLDA. In a beam-plasma situation, the downstream resonance cone exhibits a new interference pattern, which can be attributed to resonant particle effects. The upstream resonance cone is only slightly affected and is found still applicable for T e and n e diagnostics. As a result of the comparison with numerical calculations, in which the actual distribution function is used, the downstream interference pattern is proposed to be useful as a diagnostic method for obtaining the mean beam energy. The waves generated by the beam plasma interaction are analyzed by digital cross-correlation techniques. They are found to be Whistler waves propagating obliquely to the magnetic field direction at the resonance cone angle. (orig.)

  9. Geomorphology and petrography of the Angeles lava flow and the Monte de la Cruz cinder cone, Barva Volcano, Costa Rica

    International Nuclear Information System (INIS)

    Rojas, Vanessa; Barahona, Dione; Alvarado, Guillermo E

    2017-01-01

    A geomorphological and pretrographic study was carried out at the lava flow Angeles and the Monte de la Cruz cone in the foothills of the Volcan Barva in Costa Rica. The 1967 aerial photographs at scale 1: 17,000 and 1: 13,000, 1992 at scale 1: 60,000 and TERRA 1997 at scale 1: 40,000 were used for the photogeological study, supplemented with the analysis of the eastern sector of the Hoja Topografica Barva (1: 50 000) of the Instituto Geografico Nacional (IGN) and other topographic maps at different scales (1: 25 000 and 1: 10 000), in addition to the digital elevation models developed through Sistemas de Informacion Geografica (SIG). The information extracted from the wells of the Sistema Nacional de Aguas Subterraneas, Riego y Avenamiento (SENARA) for underground control was reinterpreted. In the field work thicknesses were measured and an estimation of the volumes, dimensions of the cast and other associated geoforms was made. Likewise, 9 samples of rock were selected for the elaboration of thin sections and for their respective petrographic analysis, which allowed to define the main lava flow units and their possible flows. As a result of the volcanic activity of the cone, two flow units of the Angeles wash were identified, the Lower Angels unit and the Superior Angels unit. Petrographically, Angeles Inferior was reciprocated with an andesitic vesical basaltic lava with a porphyritic to slightly glomeroporphyric hypocrystalline texture, with plagioclase, clinopyroxene, orthopyroxene, olivine and opaque phenocrysts. On the other hand, Superior Angeles has been vesicular andesitic with a hypocrystalline texture, glomeroporfiritica to serial glomeroporfiritica, with plagioclase, clinopyroxene, orthopyroxene, olivine and opaque phenocrysts. Morphologically, kipukas and levees were observed. Regionally, it was observed that the Monte de la Cruz cone, along with other smaller satellite cones, are aligned N19 O W along 8.5 km, evidencing an origin associated with a

  10. Mass wasting on the Orange Cone of the Atlantic Margin, South Africa

    Science.gov (United States)

    Fielies, Anthony; Murphy, Alain; Johnson, Sean; Thovhogi, Tshifhiwa

    2017-04-01

    The South African Atlantic Margin represents the rift-drift passive volcanic margin sequence which records the break-up of Gondwana around 155 Ma and the subsequent opening of the South Atlantic Ocean. The Orange Cone - the morphological expression of the sediment buildout and modification of the continental margin along the southwest African continental margin - has undergone extensive mass failure and slope modification over a protracted period. This failure extends all the way to the present-day toe of the Orange Cone. This paper outlines the data and analysis by South Arica in support of its Submission to the Commission on the Limits of the Continental Shelf. South Africa has, in its submission, identified and mapped a considerable number of gravity-driven failure features and deposits as evidence of the Orange Cone being classified as a slope in the sense of Article 76 of UNCLOS. Sediment mass failure, which includes slumping, sliding, mass transport deposits, etc., are known to be continental slope phenomena because they are gravity-driven and thus require a free slope upon which gravitational forces can cause kinetic action. Upper slope failure is ubiquitous on the Orange Cone and has been well documented. The most striking example of slope modification and downslope movement in the upper slope of the Orange Cone/Basin is the paired, gravity-driven deformation system, over 100 km across, with extension high on the submarine slope and contraction toward the toe of slope. The lower slope of the Orange Cone has experienced multiple episodes of failure in the form of glides, slides and debris flows. Failure on the lower slope is highly relevant for the purposes of delineating the foot of the continental slope as the deposition location represents the terminus of the slope processes. These gravity-driven failures are inherently linked to upper slope failure processes although their expression is markedly different. The change in gradients between the upper and

  11. Geochemical differences between along-arc and across-arc volcanics in west-central Nicaragua

    Science.gov (United States)

    Geilert, Sonja; Freundt, Armin; Wörner, Gerhard; Kutterolf, Steffen

    2012-04-01

    The La Paz Centro - Malpaisillo Lineament (LPML) in west-central Nicaragua is a north-south striking, 20 km long chain of maars and cinder cones, which intersects the northwest-southeast striking main volcanic front. A tectonic control of LPML volcanism is likely but only evident for the Malpaisillo fissure at the northern end of the LPML. Previous work demonstrated geochemical variations implying changes in mantle-source composition (i.e., added slab components) along the Central American Volcanic Arc at spatial scales of some 10's of kilometers. Our study of the LPML shows that minor but systematic changes also occur across the arc within 20 km distance. Variations in trace element ratios such as Zr/Nb, Ba/Th, Ba/La, Th/Zr, U/La and La/Yb along the LPML, i.e. across the volcanic front indicate little change in the degree of partial melting but an increase particularly in the hemipelagic sediment component in the mantle source from the fore arc towards the arc front, followed by a decrease behind the arc. Interestingly, the slab component is most prominent just in front of the arc. About 60 km southeast of the LPML, the Nejapa-Miraflores volcanic and tectonic lineament, which marks a 20 km north-south offset in the arc, differs substantially from the LPML. There is a wide scatter in incompatible trace element ratios indicating a heterogeneous mantle source at small spatial scales (c. 1 km). This mantle heterogeneity may represent vertical rather than across-arc variations and is probably related to the arc offset, because in the absence of such offset at the LPML mantle source conditions vary much less but more systematically.

  12. The influence of volcanic ash on GPS SNR signals through a laboratory experiment

    Science.gov (United States)

    Aranzulla, Massimo; Cannavo', Flavio; Scollo, Simona; Puglisi, Giuseppe

    2017-04-01

    Recent studies carried out in different worldwide volcanoes (e.g. Mt. Redoubt in Alaska, Mt. Etna in Italy) have shown the capability to detect volcanic plumes by using GNSS Signal to Noise Ratio (SNR). Those studies are based on the direct satellite signal measured by the SNR. For the GNSS frequency bands, the SNR signal should not be sensitive to water vapour variations, and the direct signal can be only attenuated in presence of anomalies. In order to further investigate the interaction between GNSS SNR and volcanic ash, to constrain the limitations of the proposed approach, a laboratory experiment was conducted. In particular, the experiment set-up was designed to measure the interaction among the GPS L1, L2 carriers and volcanic ash and consisted of: i) n. 2 identical high-frequency GNSS receivers; ii) n. 1 weather station; iii) n. 1 container; iv) n. 1 ground humidity sensor. A conical container having the same length, width and height of 1 m was used to hold the volcanic ash having two different particle sizes (namely fine and coarse classes). The container was built using a material transparent to the GPS L1 and L2 carriers. The container shape was a truncated cone with a vertex angle of 100°able to contain a volume of about 60 dm3. One receiver was placed below the container while the other one, used as reference, was located nearby in free air. The differences between the L1 and L2 signals of the two receivers was used to study the contribution of the volcanic ash.. We performed different type of measurements: i) in absence of ash (bottom); ii) changing the height of the 'fine' ash inside the container in steps of quarter-wave; iii) changing the height of the 'coarse' ash inside the container in steps of quarter-wave. Preliminary important results are here shown and described.

  13. Imaging subsurface density structure in Luynnier volcanic field, Saudi Arabia, using 3D gravity inversion technique

    Science.gov (United States)

    Aboud, Essam; El-shrief, Adel; Alqahtani, Faisal; Mogren, Saad

    2017-04-01

    On 19 May, 2009, an earthquake of magnitude (M=5.4) shocked the most volcanically active recent basaltic fields, Luynnier volcanic field, northwestern Saudi Arabia. This event was the largest recorded one since long time ago. Government evacuated the surrounding residents around the epicenter for over 3 months away from any future volcanic activity. The seismic event caused damages to buildings in the village around the epicenter and resulted in surface fissure trending in NNW-SSE direction with about 8 km length. Seismologists from Saudi Geological Survey (SGS) worked out on locating the epicenter and the cause of this earthquake. They collected seismic data from Saudi Geological Surveys Station Network as well as installed broadband seismic stations around the region of the earthquake. They finally concluded that the main cause of the M=5.4 event is dike intrusion at depth of about 5 km (not reached to the surface). In the present work, we carried out detailed ground/airborne gravity survey around the surficial fissure to image the subsurface volcanic structure where about 380 gravity stations were recorded covering the main fissure in an area of 600 km2. Gravity data was analyzed using CET edge detection tools and 3D inversion technique. The results revealed that, there is a magma chamber/body beneath the surface at 5-20 km depth and the main reason for the M=5.4 earthquake is tectonic settings of the Red Sea. Additionally, the area is characterized by set of faults trending in NW direction, parallel to the Red Sea, and most of the volcanic cones were located on faults/contacts implying that, they are structurally controlled. The 8-km surficial crack is extended SE underneath the surface.

  14. Cenozoic volcanic rocks of Saudi Arabia

    Science.gov (United States)

    Coleman, R.G.; Gregory, R.T.; Brown, G.F.

    2016-01-01

    The Cenozoic volcanic rocks of Saudi Arabia cover about 90,000 km2, one of the largest areas of alkali olivine basalt in the world. These volcanic rocks are in 13 separate fields near the eastern coast of the Red Sea and in the western Arabian Peninsula highlands from Syria southward to the Yemen Arab Republic.

  15. Resonance in a Cone-Topped Tube

    Directory of Open Access Journals (Sweden)

    Angus Cheng-Huan Chia

    2011-06-01

    Full Text Available The relationship between ratio of the upper opening diameter of a cone-topped cylinder to the cylinder diameter,and the ratio of the length of the air column to resonant period was examined. Plastic cones with upper openings ranging from 1.3 cm to 3.6 cm and tuning forks with frequencies ranging from 261.6 Hz to 523.3 Hz were used. The transition from a standing wave in a cylindrical column to a Helmholtz-type resonance in a resonant cavity with a narrow opening was observed.

  16. Integrity of the cone photoreceptor mosaic in oligocone trichromacy

    DEFF Research Database (Denmark)

    Michaelides, Michel; Rha, Jungtae; Dees, Elise W

    2011-01-01

    Oligocone trichromacy (OT) is an unusual cone dysfunction syndrome characterized by reduced visual acuity, mild photophobia, reduced amplitude of the cone electroretinogram with normal rod responses, normal fundus appearance, and normal or near-normal color vision. It has been proposed that these...... that these patients have a reduced number of normal functioning cones (oligocone). This paper has sought to evaluate the integrity of the cone photoreceptor mosaic in four patients previously described as having OT....

  17. Oblique cone formation in Ge by Ar+ sputtering

    International Nuclear Information System (INIS)

    Chini, T.K.; Bhattaracharyya, S.R.; Ghose, D.; Basu, D.

    1992-01-01

    Sharp oblique cones are only formed on polished germanium surfaces by 30 keV Ar + bombardment, in the presence of tungsten seed atoms; substantiating Wehner's hypothesis that higher melting point seed material is the crucial factor for cone formation. The morphology of the cone is characterized by the formation of a sloped ridge, consistent with the observations of earlier workers. Moreover, some strange wing-like structures are associated with these cones. (author)

  18. Volcanic Ash on Slopes of Karymsky

    Science.gov (United States)

    2007-01-01

    A volcanic eruption can produce gases, lava, bombs of rock, volcanic ash, or any combination of these elements. Of the volcanic products that linger on the land, most of us think of hardened lava flows, but volcanic ash can also persist on the landscape. One example of that persistence appeared on Siberia's Kamchatka Peninsula in spring 2007. On March 25, 2007, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this image of the area around the Karymsky Volcano. In this image, volcanic ash from earlier eruptions has settled onto the snowy landscape, leaving dark gray swaths. The ash stains are confined to the south of the volcano's summit, one large stain fanning out toward the southwest, and another toward the east. At first glance, the ash stain toward the east appears to form a semicircle north of the volcano and sweep back east. Only part of this dark shape, however, is actually volcanic ash. Near the coast, the darker color may result from thicker vegetation. Similar darker coloring appears to the south. Volcanic ash is not really ash at all, but tiny, jagged bits of rock and glass. These jagged particles pose serious health risks to humans and animals who might inhale them. Likewise, the ash poses hazards to animals eating plants that have been coated with ash. Because wind can carry volcanic ash thousands of kilometers, it poses a more far-reaching hazard than other volcanic ejecta. Substantial amounts of ash can even affect climate by blocking sunlight. Karymsky is a stratovolcano composed of alternating layers of solidified ash, hardened lava, and volcanic rocks. It is one of many active volcanoes on Russia's Kamchatka Peninsula, which is part of the 'Ring of Fire' around the Pacific Rim. NASA image created by Jesse Allen, using data provided courtesy of the NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.

  19. Vegetation - Lassen Foothills [ds564

    Data.gov (United States)

    California Department of Resources — In 2007 Aerial Information Systems, Inc. (AIS) was contracted by the California Native Plant Society (CNPS) to produce a vegetation map for approximately 100,000...

  20. Vegetation - Lassen Foothills [ds564

    Data.gov (United States)

    California Natural Resource Agency — In 2007 Aerial Information Systems, Inc. (AIS) was contracted by the California Native Plant Society (CNPS) to produce a vegetation map for approximately 100,000...

  1. Cones and craters on Mount Pavagadh, Deccan Traps: Rootless ...

    Indian Academy of Sciences (India)

    Rootless cones, also (erroneously) called pseudocraters, form due to explosions that ensue when a lava flow enters a surface water body, ice, or wet ground. They do not represent primary vents connected by vertical conduits to a subsurface magma source. Rootless cones in Iceland are well studied. Cones on Mars ...

  2. Cones and craters on Mount Pavagadh, Deccan Traps: Rootless ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Rootless cones, also (erroneously) called pseudocraters, form due to explosions that ensue when a lava flow enters a surface water body, ice, or wet ground. They do not represent primary vents connected by vertical conduits to a subsurface magma source. Rootless cones in Iceland are well studied. Cones on Mars ...

  3. Distribution of the cone insect, Dioryctria disclusa, in red pine.

    Science.gov (United States)

    William J. Mattson

    1976-01-01

    Within the crowns of red pine, Pinus resinosa Ait., trees, larvae of the cone insect, Dioryctria disclusa Heinrich, tended to follow the distributions of their foods. Between-tree distributions of larvae, however, were relatable to food distributions in only two of five years. Cone damage/tree by D. disclusa increased linearly with cone abundance per tree when insect...

  4. Funnel cone for focusing intense ion beams on a target

    International Nuclear Information System (INIS)

    Bieniosek, F.M.; Henestroza, E.; Ni, P.

    2009-01-01

    We describe a funnel cone for concentrating an ion beam on a target. The cone utilizes the reflection characteristic of ion beams on solid walls to focus the incident beam andincrease beam intensity on target. The cone has been modeled with the TRIM code. A prototype has been tested and installed for use in the 350-keV K+ NDCX target chamber.

  5. Combining probabilistic hazard assessment with cost-benefit analysis to support decision making in a volcanic crisis from the Auckland Volcanic Field, New Zealand

    Science.gov (United States)

    Sandri, Laura; Jolly, Gill; Lindsay, Jan; Howe, Tracy; Marzocchi, Warner

    2010-05-01

    One of the main challenges of modern volcanology is to provide the public with robust and useful information for decision-making in land-use planning and in emergency management. From the scientific point of view, this translates into reliable and quantitative long- and short-term volcanic hazard assessment and eruption forecasting. Because of the complexity in characterizing volcanic events, and of the natural variability of volcanic processes, a probabilistic approach is more suitable than deterministic modeling. In recent years, two probabilistic codes have been developed for quantitative short- and long-term eruption forecasting (BET_EF) and volcanic hazard assessment (BET_VH). Both of them are based on a Bayesian Event Tree, in which volcanic events are seen as a chain of logical steps of increasing detail. At each node of the tree, the probability is computed by taking into account different sources of information, such as geological and volcanological models, past occurrences, expert opinion and numerical modeling of volcanic phenomena. Since it is a Bayesian tool, the output probability is not a single number, but a probability distribution accounting for aleatory and epistemic uncertainty. In this study, we apply BET_VH in order to quantify the long-term volcanic hazard due to base surge invasion in the region around Auckland, New Zealand's most populous city. Here, small basaltic eruptions from monogenetic cones pose a considerable risk to the city in case of phreatomagmatic activity: evidence for base surges are not uncommon in deposits from past events. Currently, we are particularly focussing on the scenario simulated during Exercise Ruaumoko, a national disaster exercise based on the build-up to an eruption in the Auckland Volcanic Field. Based on recent papers by Marzocchi and Woo, we suggest a possible quantitative strategy to link probabilistic scientific output and Boolean decision making. It is based on cost-benefit analysis, in which all costs

  6. Deformation of volcanic materials by pore pressurization: analog experiments with simplified geometry

    Science.gov (United States)

    Hyman, David; Bursik, Marcus

    2018-03-01

    The pressurization of pore fluids plays a significant role in deforming volcanic materials; however, understanding of this process remains incomplete, especially scenarios accompanying phreatic eruptions. Analog experiments presented here use a simple geometry to study the mechanics of this type of deformation. Syrup was injected into the base of a sand medium, simulating the permeable flow of fluids through shallow volcanic systems. The experiments examined surface deformation over many source depths and pressures. Surface deformation was recorded using a Microsoft® Kinect™ sensor, generating high-spatiotemporal resolution lab-scale digital elevation models (DEMs). The behavior of the system is controlled by the ratio of pore pressure to lithostatic loading (λ =p/ρ g D). For λ feedback between deformation and pressurization wherein higher pressure ratios yielded larger deformations. For λ >10, fluid expulsion from the layer was much faster, vertically fracturing to the surface with larger pressure ratios yielding less deformation. The temporal behavior of deformation followed a characteristic evolution that produced an approximately exponential increase in deformation with time until complete layer penetration. This process is distinguished from magmatic sources in continuous geodetic data by its rapidity and characteristic time evolution. The time evolution of the experiments compares well with tilt records from Mt. Ontake, Japan, in the lead-up to the deadly 2014 phreatic eruption. Improved understanding of this process may guide the evolution of magmatic intrusions such as dikes, cone sheets, and cryptodomes and contribute to caldera resurgence or deformation that destabilizes volcanic flanks.

  7. Climatic Impact of Volcanic Eruptions

    Directory of Open Access Journals (Sweden)

    Gregory A. Zielinski

    2002-01-01

    Full Text Available Volcanic eruptions have the potential to force global climate, provided they are explosive enough to emit at least 1–5 megaton of sulfur gases into the stratosphere. The sulfuric acid produced during oxidation of these gases will both absorb and reflect incoming solar radiation, thus warming the stratosphere and cooling the Earth’s surface. Maximum global cooling on the order of 0.2–0.3°C, using instrumental temperature records, occurs in the first 2 years after the eruption, with lesser cooling possibly up to the 4th year. Equatorial eruptions are able to affect global climate, whereas mid- to high-latitude events will impact the hemisphere of origin. However, regional responses may differ, including the possibility of winter warming following certain eruptions. Also, El Niño warming may override the cooling induced by volcanic activity. Evaluation of different style eruptions as well as of multiple eruptions closely spaced in time beyond the instrumental record is attained through the analysis of ice-core, tree-ring, and geologic records. Using these data in conjunction with climate proxy data indicates that multiple eruptions may force climate on decadal time scales, as appears to have occurred during the Little Ice Age (i.e., roughly AD 1400s–1800s. The Toba mega-eruption of ~75,000 years ago may have injected extremely large amounts of material into the stratosphere that remained aloft for up to about 7 years. This scenario could lead to the initiation of feedback mechanisms within the climate system, such as cooling of sea-surface temperatures. These interacting mechanisms following a mega-eruption may cool climate on centennial time scales.

  8. Supersonic Laminar Viscous Flow Past a Cone at Angle of Attack in Spinning and Coning Motion

    Science.gov (United States)

    Agarwal, Ramesh; Rakich, John V.

    1982-01-01

    Computational results obtained with a parabolic Navier-Stokes marching code are presented for supersonic viscous flow past a pointed cone at angle of attack undergoing a combined spinning and coning motion. The code takes into account the asymmetries in the flowfield resulting from the motion and computes the asymmetric shock shape, crossflow and streamwise shear, heat transfer, crossflow separation and vortex structure. The side force and moment are also computed. Reasonably good agreement is obtained with the side force measurements of Schiff and Tobak. Comparison is also made with the only available numerical inviscid analysis. It is found that the asymmetric pressure loads due lo coning motion are much larger than all other viscous forces due lo spin and coning, making viscous forces negligible in the combined motion.

  9. Products and processes in Pliocene-Recent, subaqueous to emergent volcanism in the Antarctic Peninsula: examples of englacial Surtseyan volcano construction

    Science.gov (United States)

    Smellie, J. L.; Hole, M. J.

    Pliocene-Recent volcanic outcrops at Seal Nunataks and Beethoven Peninsula (Antarctic Peninsula) are remnants of several monogenetic volcanoes formed by eruption of vesiculating basaltic magma into shallow water, in an englacial environment. The diversity of sedimentary and volcanic lithofacies present in the Antarctic Peninsula outcrops provides a clear illustration of the wide range of eruptive, transportational and depositional processes which are associated with englacial Surtseyan volcanism. Early-formed pillow lava and glassy breccia, representing a pillow volcano stage of construction, are draped by tephra erupted explosively during a tuff cone stage. The tephra was resedimented around the volcano flanks, mainly by coarse-grained sediment gravity flows. Fine-grained lithofacies are rare, and fine material probably bypassed the main volcanic edifice, accumulating in the surrounding englacial basin. The pattern of sedimentation records variations in eruption dynamics. Products of continuous-uprush eruptions are thought to be represented by stacks of poorly bedded gravelly sandstone, whereas better bedded, lithologically more diverse sequences accumulated during periods of quiescence or effusive activity. Evidence for volcano flank failure is common. In Seal Nunataks, subaerial lithofacies (mainly lavas and cinder cone deposits) are volumetrically minor and occur at a similar stratigraphical position to pillow lava, suggesting that glacial lake drainage may have occurred prior to or during deposition of the subaerial lithofacies. By contrast, voluminous subaerial effusion in Beethoven Peninsula led to the development of laterally extensive stratified glassy breccias representing progradation of hyaloclastite deltas.

  10. Still in Light-Cone Superspace

    Science.gov (United States)

    Ramond, P.

    2010-01-01

    The recently formulated Bagger-Lambert-Gustavsson (BLG) theory in three dimensions is described in terms of a constrained chiral superfield in light-cone superspace. We discuss the use of Superconformal symmetry to determine the form of its interactions, in complete analogy with N = 4 Super Yang-Mills in four dimensions.

  11. Analog Experiment for rootless cone eruption

    Science.gov (United States)

    Noguchi, R.; Hamada, A.; Suzuki, A.; Kurita, K.

    2017-09-01

    Rootless cone is a unique geomorphological landmark to specify igneous origin of investigated terrane, which is formed by magma-water interaction. To understand its formation mechanism we conducted analog experiment for heat-induced vesiculation by using hot syrup and sodium bicarbonate solution.

  12. Epigenomic landscapes of retinal rods and cones

    Science.gov (United States)

    Mo, Alisa; Luo, Chongyuan; Davis, Fred P; Mukamel, Eran A; Henry, Gilbert L; Nery, Joseph R; Urich, Mark A; Picard, Serge; Lister, Ryan; Eddy, Sean R; Beer, Michael A; Ecker, Joseph R; Nathans, Jeremy

    2016-01-01

    Rod and cone photoreceptors are highly similar in many respects but they have important functional and molecular differences. Here, we investigate genome-wide patterns of DNA methylation and chromatin accessibility in mouse rods and cones and correlate differences in these features with gene expression, histone marks, transcription factor binding, and DNA sequence motifs. Loss of NR2E3 in rods shifts their epigenomes to a more cone-like state. The data further reveal wide differences in DNA methylation between retinal photoreceptors and brain neurons. Surprisingly, we also find a substantial fraction of DNA hypo-methylated regions in adult rods that are not in active chromatin. Many of these regions exhibit hallmarks of regulatory regions that were active earlier in neuronal development, suggesting that these regions could remain undermethylated due to the highly compact chromatin in mature rods. This work defines the epigenomic landscapes of rods and cones, revealing features relevant to photoreceptor development and function. DOI: http://dx.doi.org/10.7554/eLife.11613.001 PMID:26949250

  13. Chloride equilibrium potential in salamander cones

    Directory of Open Access Journals (Sweden)

    Bryson Eric J

    2004-12-01

    Full Text Available Abstract Background GABAergic inhibition and effects of intracellular chloride ions on calcium channel activity have been proposed to regulate neurotransmission from photoreceptors. To assess the impact of these and other chloride-dependent mechanisms on release from cones, the chloride equilibrium potential (ECl was determined in red-sensitive, large single cones from the tiger salamander retinal slice. Results Whole cell recordings were done using gramicidin perforated patch techniques to maintain endogenous Cl- levels. Membrane potentials were corrected for liquid junction potentials. Cone resting potentials were found to average -46 mV. To measure ECl, we applied long depolarizing steps to activate the calcium-activated chloride current (ICl(Ca and then determined the reversal potential for the current component that was inhibited by the Cl- channel blocker, niflumic acid. With this method, ECl was found to average -46 mV. In a complementary approach, we used a Cl-sensitive dye, MEQ, to measure the Cl- flux produced by depolarization with elevated concentrations of K+. The membrane potentials produced by the various high K+ solutions were measured in separate current clamp experiments. Consistent with electrophysiological experiments, MEQ fluorescence measurements indicated that ECl was below -36 mV. Conclusions The results of this study indicate that ECl is close to the dark resting potential. This will minimize the impact of chloride-dependent presynaptic mechanisms in cone terminals involving GABAa receptors, glutamate transporters and ICl(Ca.

  14. Cone beam computed tomography in veterinary dentistry

    NARCIS (Netherlands)

    van Thielen, B.; Siguenza, F.; Hassan, B.

    2012-01-01

    The purpose of this study was to assess the feasibility of cone beam computed tomography (CBCT) in imaging dogs and cats for diagnostic dental veterinary applications. CBCT scans of heads of six dogs and two cats were made. Dental panoramic and multi-planar reformatted (MPR) para-sagittal

  15. Characterization of a cone beam optical scanner

    International Nuclear Information System (INIS)

    Ravindran, P B; Thomas, H M

    2013-01-01

    The use of radiochromic FX gel for mapping 3D dose distribution is hampered by the diffusion of gel and the slow scanning techniques. The development of fast optical cone beam scanning has improved the chances of using radiochromic gel as a feasible dosimeter for radiotherapy applications. In this work an optical cone beam scanner has been developed in-house and its performance characteristics have been studied. The reconstructed image of the optical scanner was analyzed by studying the resolution, signal-to-noise ratio and contrast to noise ratio (CNR). The resolution of the optical cone beam CT scanner was studied by scanning a catheter of 1 mm outer diameter and the scanner was able to detect the catheter. The geometrical accuracy of the reconstruction was studied by placing catheters in spiral geometry in the gel phantom and measuring the distances. It has been observed that the in-house Optical Cone beam scanner is suitable for scanning radiochromic gels for radiotherapy applications.

  16. Cone beam CT, wat moet ik ermee?

    NARCIS (Netherlands)

    Hoogeveen, R.

    2013-01-01

    De cone beam-ct-scan (cbct-scan) maakt een opmars in de tandheelkunde vanwege de toegevoegde waarde van de derde dimensie in de diagnostiek. Deze extra informatie wordt verkregen ten koste van een hogere stralenbelasting en een daarmee gepaard gaand hoger risico voor de patiënt. Om de clinicus te

  17. Perturbation theory in light-cone quantization

    Energy Technology Data Exchange (ETDEWEB)

    Langnau, Alex [Stanford Univ., CA (United States)

    1992-01-01

    A thorough investigation of light-cone properties which are characteristic for higher dimensions is very important. The easiest way of addressing these issues is by analyzing the perturbative structure of light-cone field theories first. Perturbative studies cannot be substituted for an analysis of problems related to a nonperturbative approach. However, in order to lay down groundwork for upcoming nonperturbative studies, it is indispensable to validate the renormalization methods at the perturbative level, i.e., to gain control over the perturbative treatment first. A clear understanding of divergences in perturbation theory, as well as their numerical treatment, is a necessary first step towards formulating such a program. The first objective of this dissertation is to clarify this issue, at least in second and fourth-order in perturbation theory. The work in this dissertation can provide guidance for the choice of counterterms in Discrete Light-Cone Quantization or the Tamm-Dancoff approach. A second objective of this work is the study of light-cone perturbation theory as a competitive tool for conducting perturbative Feynman diagram calculations. Feynman perturbation theory has become the most practical tool for computing cross sections in high energy physics and other physical properties of field theory. Although this standard covariant method has been applied to a great range of problems, computations beyond one-loop corrections are very difficult. Because of the algebraic complexity of the Feynman calculations in higher-order perturbation theory, it is desirable to automatize Feynman diagram calculations so that algebraic manipulation programs can carry out almost the entire calculation. This thesis presents a step in this direction. The technique we are elaborating on here is known as light-cone perturbation theory.

  18. A 40-foot static cone penetrometer

    Science.gov (United States)

    Beard, R.M.; Lee, H.J.

    1982-01-01

    The Navy needs a lightweight device for testing seafloor soils to sub bottom depths of 12 meters in water depths to 60 meters. To meet this need a quasistatic cone penetration device that uses water jetting to reduce friction on the cone rod has been developed. This device is called the XSP-40. The 5-ton XSP-40 stands 15 meters tall and pushes a standard 5-ton cone into the seafloor. It is remotely controlled with an electronic unit on the deck of the support vessel. All cone outputs are recorded directly as a function of penetration depth with a strip chart recorder. A full suite of gauges is provided. on the electronic unit for monitoring the XSP-40's performance during a test .. About 40 penetration tests have been performed with very good success. The XSP-40 was field tested in Norton Sound, off the west coast of Alaska. The general objective, in addition to evaluation of the device, was to gather geotechnical information on sediments that may be involved in processes potentially hazardous to offshore development. Four example penetration records are presented from gas charged sediment zones and areas near the Yukon River delta. In general it was determined that soil classification from cone data agreed well with classifications from core samples. Relative densities of the silt-sand to sandy-silt soils were usually very high. The significance of these results are discussed with respect to storm wave, liquefaction. It is concluded that the XSP-40 is a durable and reliable piece of equipment capable of achieving penetration beyond that possible when not using the water jet system.

  19. Eruptive dynamics and hazards associated with obsidian bearing ignimbrites of the Geghama Volcanic Highland, Central Armenia: a textural insight

    Science.gov (United States)

    Matthews, Zoe; Manning, Christina J.

    2017-04-01

    The Geghama Volcanic highland in central Armenia is an ideal setting to study the young ( 750-25 ka [1]) volcanism that characterises the Lesser Caucasus region. The volcanism in the area is bimodal in composition: the eastern highlands are dominated by numerous monogenetic scoria cones, whilst the west shows more evolved volcanism centered on two obsidian bearing, polygenetic domes (Hatis and Gutanasar) [2]. Activity at Hatis and Gutanasar is thought to have spanned 550ka-200ka [3] and produced a range of products including obsidian flows, ignimbrites and basaltic scoria cones, consistent with long lived and complex magma storage systems. During a similar time period there is evidence for the presence of hominin groups in the surrounding region [3] and it is likely that at least some of the volcanic activity at Hatis and Gutanasar impacted on their distribution [4]. A better understanding of the eruptive behaviour of these volcanoes during this period could therefore shed light on the effect of volcanic activity on the dispersal of man through this period. Whilst large regional studies have striven to better understand the timing and source of volcanism in Armenia, there have been few detailed studies on single volcanoes. Obsidian is ubiquitous within the volcanic material of both Gutanasar and Hatis as lava flows, dome deposits and within ignimbrites. This study aims to better understand the eruptive history of Gutanasar, with specific focus upon the determination of the petrogenetic history of obsidian lenses observed within the ignimbrite deposits. Identification of these obsidians as the result of welding or in-situ melting will help constrain eruptive volumes and flow thickness, important for the reconstruction of palaeo-volcanic hazards. In order to interpret how this obsidian was deposited, macro textural analysis is combined with micro textural measurements of microlite crystals. Quantitative measurements of microlites in obsidian can provide significant

  20. CRALBP supports the mammalian retinal visual cycle and cone vision.

    Science.gov (United States)

    Xue, Yunlu; Shen, Susan Q; Jui, Jonathan; Rupp, Alan C; Byrne, Leah C; Hattar, Samer; Flannery, John G; Corbo, Joseph C; Kefalov, Vladimir J

    2015-02-01

    Mutations in the cellular retinaldehyde-binding protein (CRALBP, encoded by RLBP1) can lead to severe cone photoreceptor-mediated vision loss in patients. It is not known how CRALBP supports cone function or how altered CRALBP leads to cone dysfunction. Here, we determined that deletion of Rlbp1 in mice impairs the retinal visual cycle. Mice lacking CRALBP exhibited M-opsin mislocalization, M-cone loss, and impaired cone-driven visual behavior and light responses. Additionally, M-cone dark adaptation was largely suppressed in CRALBP-deficient animals. While rearing CRALBP-deficient mice in the dark prevented the deterioration of cone function, it did not rescue cone dark adaptation. Adeno-associated virus-mediated restoration of CRALBP expression specifically in Müller cells, but not retinal pigment epithelial (RPE) cells, rescued the retinal visual cycle and M-cone sensitivity in knockout mice. Our results identify Müller cell CRALBP as a key component of the retinal visual cycle and demonstrate that this pathway is important for maintaining normal cone-driven vision and accelerating cone dark adaptation.

  1. Micro focusing of fast electrons with opened cone targets

    International Nuclear Information System (INIS)

    Liu Feng; Liu Xiaoxuan; Ding Wenjun; Du Fei; Li Yutong; Ma Jinglong; Liu Xiaolong; Chen Liming; Lu Xin; Dong Quanli; Wang Weimin; Wang Zhaohua; Wei Zhiyi; Liu Bicheng; Sheng Zhengming; Zhang Jie

    2012-01-01

    Using opened reentrant cone silicon targets, we have demonstrated the effect of micro focusing of fast electrons generated in intense laser-plasma interactions. When an intense femtosecond laser pulse is focused tightly onto one of the side walls of the cone, fast electron beam emitted along the side wall is observed. When a line focus spot, which is long enough to irradiate both of the side walls of the cone simultaneously, is used, two electron beams emitted along each side wall, respectively, are observed. The two beams should cross each other near the open tip of the cone, resulting in micro focusing. We use a two-dimensional Particle-In-Cell code to simulate the electron emission both in opened and closed cone targets. The simulation results of the opened cone targets are in agreement with the experimental observation while the results of the closed cone targets do not show the micro focusing effect.

  2. Active Volcanic Plumes on Io

    Science.gov (United States)

    1997-01-01

    This color image, acquired during Galileo's ninth orbit around Jupiter, shows two volcanic plumes on Io. One plume was captured on the bright limb or edge of the moon (see inset at upper right), erupting over a caldera (volcanic depression) named Pillan Patera after a South American god of thunder, fire and volcanoes. The plume seen by Galileo is 140 kilometers (86 miles) high and was also detected by the Hubble Space Telescope. The Galileo spacecraft will pass almost directly over Pillan Patera in 1999 at a range of only 600 kilometers (373 miles).The second plume, seen near the terminator (boundary between day and night), is called Prometheus after the Greek fire god (see inset at lower right). The shadow of the 75-kilometer (45- mile) high airborne plume can be seen extending to the right of the eruption vent. The vent is near the center of the bright and dark rings. Plumes on Io have a blue color, so the plume shadow is reddish. The Prometheus plume can be seen in every Galileo image with the appropriate geometry, as well as every such Voyager image acquired in 1979. It is possible that this plume has been continuously active for more than 18 years. In contrast, a plume has never been seen at Pillan Patera prior to the recent Galileo and Hubble Space Telescope images.North is toward the top of the picture. The resolution is about 6 kilometers (3.7 miles) per picture element. This composite uses images taken with the green, violet and near infrared filters of the solid state imaging (CCD) system on NASA's Galileo spacecraft. The images were obtained on June 28, 1997, at a range of more than 600,000 kilometers (372,000 miles).The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http

  3. Palaeoclimate: Volcanism caused ancient global warming

    Science.gov (United States)

    Meissner, Katrin J.; Bralower, Timothy J.

    2017-08-01

    A study confirms that volcanism set off one of Earth's fastest global-warming events. But the release of greenhouse gases was slow enough for negative feedbacks to mitigate impacts such as ocean acidification. See Letter p.573

  4. Volcanic Ash Advisory Database, 1983-2003

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Volcanic ash is a significant hazard to aviation and can also affect global climate patterns. To ensure safe navigation and monitor possible climatic impact, the...

  5. Volcanism and associated hazards: the Andean perspective

    Directory of Open Access Journals (Sweden)

    R. I. Tilling

    2009-12-01

    Full Text Available Andean volcanism occurs within the Andean Volcanic Arc (AVA, which is the product of subduction of the Nazca Plate and Antarctica Plates beneath the South America Plate. The AVA is Earth's longest but discontinuous continental-margin volcanic arc, which consists of four distinct segments: Northern Volcanic Zone, Central Volcanic Zone, Southern Volcanic Zone, and Austral Volcanic Zone. These segments are separated by volcanically inactive gaps that are inferred to indicate regions where the dips of the subducting plates are too shallow to favor the magma generation needed to sustain volcanism. The Andes host more volcanoes that have been active during the Holocene (past 10 000 years than any other volcanic region in the world, as well as giant caldera systems that have produced 6 of the 47 largest explosive eruptions (so-called "super eruptions" recognized worldwide that have occurred from the Ordovician to the Pleistocene.

    The Andean region's most powerful historical explosive eruption occurred in 1600 at Huaynaputina Volcano (Peru. The impacts of this event, whose eruptive volume exceeded 11 km3, were widespread, with distal ashfall reported at distances >1000 km away. Despite the huge size of the Huaynaputina eruption, human fatalities from hazardous processes (pyroclastic flows, ashfalls, volcanogenic earthquakes, and lahars were comparatively small owing to the low population density at the time. In contrast, lahars generated by a much smaller eruption (<0.05 km3 in 1985 of Nevado del Ruiz (Colombia killed about 25 000 people – the worst volcanic disaster in the Andean region as well as the second worst in the world in the 20th century. The Ruiz tragedy has been attributed largely to ineffective communications of hazards information and indecisiveness by government officials, rather than any major deficiencies in scientific data. Ruiz's disastrous outcome, however, together with responses to subsequent

  6. Upper Cretaceous to Pleistocene melilitic volcanic rocks of the Bohemian Massif: petrology and mineral chemistry

    Directory of Open Access Journals (Sweden)

    Skála Roman

    2015-06-01

    Full Text Available Upper Cretaceous to Pleistocene volcanic rocks of the Bohemian Massif represent the easternmost part of the Central European Volcanic Province. These alkaline volcanic series include rare melilitic rocks occurring as dykes, sills, scoria cones and flows. They occur in three volcanic periods: (i the Late Cretaceous to Paleocene period (80–59 Ma in northern Bohemia including adjacent territories of Saxony and Lusatia, (ii the Mid Eocene to Late Miocene (32.3–5.9 Ma period disseminated in the Ohře Rift, the Cheb–Domažlice Graben, Vogtland, and Silesia and (iii the Early to Late Pleistocene period (1.0–0.26 Ma in western Bohemia. Melilitic magmas of the Eocene to Miocene and Pleistocene periods show a primitive mantle source [(143Nd/144Ndt=0.51280–0.51287; (87Sr/86Srt=0.7034–0.7038] while those of the Upper Cretaceous to Paleocene period display a broad scatter of Sr–Nd ratios. The (143Nd/144Ndt ratios (0.51272–0.51282 of the Upper Cretaceous to Paleocene rocks suggest a partly heterogeneous mantle source, and their (87Sr/86Srt ratios (0.7033–0.7049 point to an additional late- to post-magmatic hydrothermal contribution. Major rock-forming minerals include forsterite, diopside, melilite, nepheline, sodalite group minerals, phlogopite, Cr- and Ti-bearing spinels. Crystallization pressures and temperatures of clinopyroxene vary widely between ~1 to 2 GPa and between 1000 to 1200 °C, respectively. Nepheline crystallized at about 500 to 770 °C. Geochemical and isotopic similarities of these rocks occurring from the Upper Cretaceous to Pleistocene suggest that they had similar mantle sources and similar processes of magma development by partial melting of a heterogeneous carbonatized mantle source.

  7. Timing and composition of continental volcanism at Harrat Hutaymah, western Saudi Arabia

    Science.gov (United States)

    Duncan, Robert A.; Kent, Adam J R; Thornber, Carl; Schliedler, Tyler D; Al-Amri, Abdullah M

    2016-01-01

    Harrat Hutaymah is an alkali basalt volcanic field in north-central Saudi Arabia, at the eastern margin of a large Neogene continental, intraplate magmatic province. Lava flow, tephra and spatter cone compositions in the field include alkali olivine basalts and basanites. These compositions contrast with the predominantly tholeiitic, fissure-fed basalts found along the eastern margin of the Red Sea. The Hutaymah lava flows were erupted through Proterozoic arc-associated plutonic and meta-sedimentary rocks of the Arabian shield, and commonly contain a range of sub-continental lithospheric xenoliths, although the lavas themselves show little indication of crustal contamination. Previous radiometric dating of this volcanic field (a single published K–Ar age; 1.8 Ma) is suspiciously old given the field measurement of normal magnetic polarity only (i.e. Brunhes interval, ≤ 780 Ka). We report new age determinations on 14 lava flows by the 40Ar–39Ar laser step heating method, all younger than ~ 850 Ka, to better constrain the time frame of volcanism, and major, trace and rare earth element compositions to describe the chemical variation of volcanic activity at Harrat Hutaymah. Crystal fractionation was dominated by olivine ± clinopyroxene at a range of upper mantle and crustal pressures. Rapid ascent and eruption of magma is indicated by the array of lower crustal and lithospheric xenoliths observed in lava flows and tephra. Modeling suggests 1–7% melting of an enriched asthenospheric mantle source occurred beneath Harrat Hutaymah under a relatively thick lithospheric cap (60–80 km).

  8. Shape measurements of volcanic particles by CAMSIZER

    OpenAIRE

    Lo Castro, Maria Deborah; Andronico, Daniele; Nunnari, Giuseppe; Spata, Alessandro; Torrisi, Alessio

    2009-01-01

    The shape of volcanic particles is an important parameter holding information related to physical and geochemical processes. The study of particle shape may help improving knowledge on the main eruptive processes (fragmentation, transport and sedimentation) during explosive activity. In general, volcanic ash is formed by different components, namely juvenile, lithic and crystal particles, each one characterized by peculiar morphology. Moreover, quantifying the shape of pyroclasts is needed by...

  9. Imaging volcanic CO2 and SO2

    Science.gov (United States)

    Gabrieli, A.; Wright, R.; Lucey, P. G.; Porter, J. N.

    2017-12-01

    Detecting and quantifying volcanic carbon dioxide (CO2) and sulfur dioxide (SO2) emissions is of relevance to volcanologists. Changes in the amount and composition of gases that volcanoes emit are related to subsurface magma movements and the probability of eruptions. Volcanic gases and related acidic aerosols are also an important atmospheric pollution source that create environmental health hazards for people, animals, plants, and infrastructures. For these reasons, it is important to measure emissions from volcanic plumes during both day and night. We present image measurements of the volcanic plume at Kīlauea volcano, HI, and flux derivation, using a newly developed 8-14 um hyperspectral imaging spectrometer, the Thermal Hyperspectral Imager (THI). THI is capable of acquiring images of the scene it views from which spectra can be derived from each pixel. Each spectrum contains 50 wavelength samples between 8 and 14 um where CO2 and SO2 volcanic gases have diagnostic absorption/emission features respectively at 8.6 and 14 um. Plume radiance measurements were carried out both during the day and the night by using both the lava lake in the Halema'uma'u crater as a hot source and the sky as a cold background to detect respectively the spectral signatures of volcanic CO2 and SO2 gases. CO2 and SO2 path-concentrations were then obtained from the spectral radiance measurements using a new Partial Least Squares Regression (PLSR)-based inversion algorithm, which was developed as part of this project. Volcanic emission fluxes were determined by combining the path measurements with wind observations, derived directly from the images. Several hours long time-series of volcanic emission fluxes will be presented and the SO2 conversion rates into aerosols will be discussed. The new imaging and inversion technique, discussed here, are novel allowing for continuous CO2 and SO2 plume mapping during both day and night.

  10. Ice Nuclei Production in Volcanic Clouds

    Science.gov (United States)

    Few, A. A.

    2012-12-01

    The paper [Durant et al., 2008] includes a review of research on ice nucleation in explosive volcanic clouds in addition to reporting their own research on laboratory measurements focused on single-particle ice nucleation. Their research as well as the research they reviewed were concerned with the freezing of supercooled water drops (250 to 260 K) by volcanic ash particles acting as ice freezing nuclei. Among their conclusions are: Fine volcanic ash particles are very efficient ice freezing nuclei. Volcanic clouds likely contain fine ash concentrations 104 to 105 times greater than found in meteorological clouds. This overabundance of ice nuclei will produce a cloud with many small ice crystals that will not grow larger as they do in meteorological clouds because the cloud water content is widely distributed among the numerous small ice crystals. The small ice crystals have a small fall velocity, thus volcanic clouds are very stable. The small ice crystals are easily lofted into the stratosphere transporting water and adsorbed trace gasses. In this paper we examine the mechanism for the production of the small ice nuclei and develop a simple model for calculating the size of the ice nuclei based upon the distribution of magma around imbedded bubbles. We also have acquired a volcanic bomb that exhibits bubble remnants on its entire surface. The naturally occurring fragments from the volcanic bomb reveal a size distribution consistent with that predicted by the simple model. Durant, A. J., R. A. Shaw, W. I. Rose, Y. Mi, and G. G. J. Ernst (2008), Ice nucleation and overseeding of ice in volcanic clouds, J. Geophys. Res., 113, D09206, doi:10.1029/2007JD009064.

  11. Medical effects of volcanic eruptions

    Science.gov (United States)

    Baxter, Peter J.

    1990-09-01

    Excluding famine and tsunamis, most deaths in volcanic eruptions have been from pyroclastic flows and surges (nuées ardentes) and wet debris flows (lahars). Information on the causes of death and injury in eruptions is sparse but the available literature is summarised for the benefit of volcanologists and emergency planners. In nuées, thermal injury may be at least as important as asphyxia in causing immediate deaths. The high temperature of the gases and entrained particles readily causes severe burns to the skin and the air passages and the presence of both types of injury in an individual may combine to increase the delayed mortality risk from respiratory complications or from infection of burns. Trauma from missiles or body displacement is also common, but the role of asphyxiant or irritant gases, and steam, remains unclear. The ratio of dead: injured is much higher than in other natural disasters. At the periphery of a nuée being protected inside buildings which remain intact appears to greatly increase the chances of survival. In lahars, infected wounds and crush injury are the main delayed causes of death, and the scope for preventive measures, other than evacuation, is small. The evidence from Mount St. Helens, 1980, and other major eruptions indicates that, although mortality is high within the main zone of devastation and in the open, emergency planning should concentrate on the periphery of a nuée where preventive measures are feasible and could save many lives in densely populated areas.

  12. Local and remote infrasound from explosive volcanism

    Science.gov (United States)

    Matoza, R. S.; Fee, D.; LE Pichon, A.

    2014-12-01

    Explosive volcanic eruptions can inject large volumes of ash into heavily travelled air corridors and thus pose a significant societal and economic hazard. In remote volcanic regions, satellite data are sometimes the only technology available to observe volcanic eruptions and constrain ash-release parameters for aviation safety. Infrasound (acoustic waves ~0.01-20 Hz) data fill this critical observational gap, providing ground-based data for remote volcanic eruptions. Explosive volcanic eruptions are among the most powerful sources of infrasound observed on earth, with recordings routinely made at ranges of hundreds to thousands of kilometers. Advances in infrasound technology and the efficient propagation of infrasound in the atmosphere therefore greatly enhance our ability to monitor volcanoes in remote regions such as the North Pacific Ocean. Infrasound data can be exploited to detect, locate, and provide detailed chronologies of the timing of explosive volcanic eruptions for use in ash transport and dispersal models. We highlight results from case studies of multiple eruptions recorded by the International Monitoring System and dedicated regional infrasound networks (2008 Kasatochi, Alaska, USA; 2008 Okmok, Alaska, USA; 2009 Sarychev Peak, Kuriles, Russian Federation; 2010 Eyjafjallajökull, Icleand) and show how infrasound is currently used in volcano monitoring. We also present progress towards characterizing and modeling the variability in source mechanisms of infrasound from explosive eruptions using dedicated local infrasound field deployments at volcanoes Karymsky, Russian Federation and Sakurajima, Japan.

  13. Examples of transport of volcanic ash

    Science.gov (United States)

    Bursik, M. I.

    2011-12-01

    Examination of the transport of volcanic aerosol clouds can be implemented by utilizing models for introduction and early stage spread of eruption plumes, and long-range transport. As a plume rises into the atmosphere, it is subject to the atmospheric circulation. Average wind patterns in the troposphere and stratosphere are useful in determining general features of volcanic cloud transport, but daily, seasonal and year to year variance must be taken into account in any one particular case. Tropospheric circulation plays a small role relative to stratospheric circulation, although the effects of the tropospheric portion of eruptions can be significant to catastrophic, as was the case with the April, 2010, eruption of Eyjafjallajokull, Iceland. Stratospheric circulation plays an important role in the long-term influence of volcanic aerosol, since residence time is great, due to limited mixing and vertical motion. The eruptions of Eyjafjallajokull and Laki, Iceland; Hudson, Chile; El Chichon, Mexico, and Pinatubo, Phillipines, provide examples of how volcanic clouds interact with the atmospheric circulation. Eruption clouds from low latitudes spread across both hemispheres, while eruption clouds from high latitudes remain in the hemisphere of the eruption. Cloud form and dispersal pattern are determined by season; the shape of a volcanic cloud is altitude dependent. The size of a volcanic cloud in relation to atmospheric eddies is important in determining how it is dispersed.

  14. Volcanic loading: The dust veil index

    Energy Technology Data Exchange (ETDEWEB)

    Lamb, H.H. [Univ. of East Anglia, Norwich (United Kingdom). Climatic Research Unit

    1985-09-01

    Dust ejected into the high atmosphere during explosive volcanic eruptions has been considered as a possible cause for climatic change. Dust veils created by volcanic eruptions can reduce the amount of light reaching the Earth`s surface and can cause reductions in surface temperatures. These climatic effects can be seen for several years following some eruptions and the magnitude and duration of the effects depend largely on the density or amount of tephra (i.e. dust) ejected, the latitude of injection, and atmospheric circulation patterns. Lamb (1970) formulated the Dust Veil Index (DVI) in an attempt to quantify the impact on the Earth`s energy balance of changes in atmospheric composition due to explosive volcanic eruptions. The DVI is a numerical index that quantifies the impact on the Earth`s energy balance of changes in atmospheric composition due to explosive volcanic eruptions. The DVI is a numerical index that quantifies the impact of a particular volcanic eruptions release of dust and aerosols over the years following the event. The DVI for any volcanic eruptions are available and have been used in estimating Lamb`s dust veil indices.

  15. On Krasnoselskii's Cone Fixed Point Theorem

    Directory of Open Access Journals (Sweden)

    Man Kam Kwong

    2008-04-01

    Full Text Available In recent years, the Krasnoselskii fixed point theorem for cone maps and its many generalizations have been successfully applied to establish the existence of multiple solutions in the study of boundary value problems of various types. In the first part of this paper, we revisit the Krasnoselskii theorem, in a more topological perspective, and show that it can be deduced in an elementary way from the classical Brouwer-Schauder theorem. This viewpoint also leads to a topology-theoretic generalization of the theorem. In the second part of the paper, we extend the cone theorem in a different direction using the notion of retraction and show that a stronger form of the often cited Leggett-Williams theorem is a special case of this extension.

  16. Dirac cones in two-dimensional borane

    Science.gov (United States)

    Martinez-Canales, Miguel; Galeev, Timur R.; Boldyrev, Alexander I.; Pickard, Chris J.

    2017-11-01

    We introduce two-dimensional borane, a single-layered material of BH stoichiometry, with promising electronic properties. We show that, according to density functional theory calculations, two-dimensional borane is semimetallic, with two symmetry-related Dirac cones meeting right at the Fermi energy Ef. The curvature of the cones is lower than in graphene, thus closer to the ideal linear dispersion. Its structure, formed by a puckered trigonal boron network with hydrogen atoms connected to each boron atom, can be understood as distorted, hydrogenated borophene [Mannix et al., Science 350, 1513 (2015), 10.1126/science.aad1080]. Chemical bonding analysis reveals the boron layer in the network being bound by delocalized four-center two-electron σ bonds. Finally, we suggest high pressure could be a feasible route to synthesize two-dimensional borane.

  17. Basic principle of cone beam computed tomography

    International Nuclear Information System (INIS)

    Choi, Yong Suk; Kim, Gyu Tae; Hwang, Eui Hwan

    2006-01-01

    The use of computed tomography for dental procedures has increased recently. Cone beam computed tomography(CBCT) systems have been designed for imaging hard tissues of the dentomaxillofacial region. CBCT is capable of providing high resolution in images of high diagnostic quality. This technology allows for 3-dimensional representation of the dentomaxillofacial skeleton with minimal distortion, but at lower equipment cost, simpler image acquisition and lower patient dose. Because this technology produces images with isotropic sub-millimeter spatial resolution, it is ideally suited for dedicated dentomaxillofacial imaging. In this paper, we provide a brief overview of cone beam scanning technology and compare it with the fan beam scanning used in conventional CT and the basic principles of currently available CBCT systems

  18. Variability of silver fir (Abies alba Mill. cones – variability of cone parameters

    Directory of Open Access Journals (Sweden)

    Aniszewska Monika

    2016-09-01

    Full Text Available This study aimed at determining the shape of closed silver fir cones from the Jawor Forest District (Wroclaw, based purely on measurements of their length and thickness. Using these two parameters, the most accurate estimations were achieved with a fourth-degree polynomial fitting function. We then calculated the cones’ surface area and volume in three different ways: 1 Using the fourth-degree polynomial shape estimation, 2 Introducing indicators of compliance (k1, k2, k3 to calculate the volume and then comparing it to its actual value as measured in a pitcher filled with water, 3 Comparing the surface area of the cones as calculated with the polynomial function to the value obtained from ratios of indicators of compliance (ratios k4 and k5. We found that the calculated surface area and volume were substantially higher than the corresponding measured values. Test values of cone volume and surface area as calculated by our model were 8% and 5% lower, respectively, compared to direct measurements. We also determined the fir cones apparent density to be 0.8 g·cm-3on average. The gathered data on cone surface area, volume and bulk density is a valuable tool for optimizing the thermal peeling process in mill cabinets to acquire high quality seeds.

  19. The NLO jet vertex in the small-cone approximation for kt and cone algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Colferai, D.; Niccoli, A. [Dipartimento di Fisica e Astronomia, Università di Firenze and INFN, Sezione di Firenze, 50019 Sesto Fiorentino (Italy)

    2015-04-15

    We determine the jet vertex for Mueller-Navelet jets and forward jets in the small-cone approximation for two particular choices of jet algoritms: the kt algorithm and the cone algorithm. These choices are motivated by the extensive use of such algorithms in the phenomenology of jets. The differences with the original calculations of the small-cone jet vertex by Ivanov and Papa, which is found to be equivalent to a formerly algorithm proposed by Furman, are shown at both analytic and numerical level, and turn out to be sizeable. A detailed numerical study of the error introduced by the small-cone approximation is also presented, for various observables of phenomenological interest. For values of the jet “radius” R=0.5, the use of the small-cone approximation amounts to an error of about 5% at the level of cross section, while it reduces to less than 2% for ratios of distributions such as those involved in the measure of the azimuthal decorrelation of dijets.

  20. The NLO jet vertex in the small-cone approximation for kt and cone algorithms

    International Nuclear Information System (INIS)

    Colferai, D.; Niccoli, A.

    2015-01-01

    We determine the jet vertex for Mueller-Navelet jets and forward jets in the small-cone approximation for two particular choices of jet algoritms: the kt algorithm and the cone algorithm. These choices are motivated by the extensive use of such algorithms in the phenomenology of jets. The differences with the original calculations of the small-cone jet vertex by Ivanov and Papa, which is found to be equivalent to a formerly algorithm proposed by Furman, are shown at both analytic and numerical level, and turn out to be sizeable. A detailed numerical study of the error introduced by the small-cone approximation is also presented, for various observables of phenomenological interest. For values of the jet “radius” R=0.5, the use of the small-cone approximation amounts to an error of about 5% at the level of cross section, while it reduces to less than 2% for ratios of distributions such as those involved in the measure of the azimuthal decorrelation of dijets.

  1. Hadronic wavefunctions in light-cone quantization

    International Nuclear Information System (INIS)

    Hyer, T.

    1994-05-01

    The analysis of light-cone wavefunctions seems the most promising theoretical approach to a detailed understanding of the structure of relativistic bound states, particularly hadrons. However, there are numerous complications in this approach. Most importantly, the light-cone approach sacrifices manifest rotational invariance in exchange for the elimination of negative-energy states. The requirement of rotational invariance of the full theory places important constraints on proposed light-cone wavefunctions, whether they are modelled or extracted from some numerical procedure. A formulation of the consequences of the hidden rotational symmetry has been sought for some time; it is presented in Chapter 2. In lattice gauge theory or heavy-quark effective theory, much of the focus is on the extraction of numerical values of operators which are related to the hadronic wavefunction. These operators are to some extent interdependent, with relations induced by fundamental constraints on the underlying wavefunction. The consequences of the requirement of unitarity are explored in Chapter 3, and are found to have startling phenomenological relevance. To test model light-cone wavefunctions, experimental predictions must be made. The reliability of perturbative QCD as a tool for making such predictions has been questioned. In Chapter 4, the author presents a computation of the rates for nucleon-antinucleon annihilation, improving the reliability of the perturbative computation by taking into account the Sudakov suppression of exclusive processes at large transverse impact parameter. In Chapter 5, he develops the analysis of semiexclusive production. This work focuses on processes in which a single isolated meson is produced perturbatively and recoils against a wide hadronizing system. At energies above about 10 GeV, semiexclusive processes are shown to be the most sensitive experimental probes of hadronic structure

  2. Lessons from the light-cone box

    CERN Document Server

    Leibbrandt, G

    2000-01-01

    Working in the noncovariant light-cone gauge, we discuss the explicit computation of the 1PI four-point function ("box diagram") in Yang- Mills theory. The complete box diagram which consists of 16 box subdiagrams, 8 lynx subdiagrams and 4 fish subdiagrams, yields both local and nonlocal UV divergent terms. The nonlocal terms are consistent with gauge symmetry and correspond to a nonlocal renormalization of the wave function. (14 refs).

  3. Instantons on Calabi-Yau cones

    Science.gov (United States)

    Sperling, Marcus

    2015-12-01

    The Hermitian Yang-Mills equations on certain vector bundles over Calabi-Yau cones can be reduced to a set of matrix equations; in fact, these are Nahm-type equations. The latter can be analysed further by generalising arguments of Donaldson and Kronheimer used in the study of the original Nahm equations. Starting from certain equivariant connections, we show that the full set of instanton equations reduce, with a unique gauge transformation, to the holomorphicity condition alone.

  4. Variation among individuals in cone production in Pinus palustris (Pinaceae).

    Science.gov (United States)

    Haymes, Kelly L; Fox, Gordon A

    2012-04-01

    Reproductive output varies considerably among individuals within plant populations, and this is especially so in cone production of conifers. While this variation can have substantial effects on populations, little is known about its magnitude or causes. We studied variation in cone production for 2 years within a population of Pinus palustris Mill. (longleaf pine; Pinaceae). Using hurdle models, we evaluated the importance of burn treatments, tree size (dbh), canopy status (open, dominant, subordinate), and number of conspecific neighbors within 4 m (N(4)). Cone production of individuals-even after accounting for other variables-was strongly correlated between years. Trees in plots burned every 1, 2, or 5 years produced more cones than those burned every 7 years, or unburned. Larger trees tend to produce more cones, but the large effects of the other factors studied caused substantial scatter in the dbh-cone number relationship. Among trees in the open, dbh had little explanatory power. Subordinate trees with three neighbors produced no cones. Tree size alone was a weak predictor of cone production. Interactions with neighbors play an important role in generating reproductive heterogeneity, and must be accounted for when relating cone production to size. The strong between-year correlation, together with the large variance in cone production among trees without neighbors, suggests that still more of the variance may be explainable, but requires factors outside of our study.

  5. Hydrogeologic setting and hydrologic data of the Smoke Creek Desert basin, Washoe County, Nevada, and Lassen County, California, water years 1988-90

    Science.gov (United States)

    Maurer, D.K.

    1993-01-01

    Smoke Creek Desert is a potential source of water for urban development in Washoe County, Nevada. Hydrogeologic data were collected from 1988 to 1990 to learn more about surface- and ground-water flow in the basin. Impermeable rocks form a boundary to ground-water flow on the east side of the basin and at unknown depths at the base of the flow system. Permeable volcanic rocks on the west and north sides of the basin represent a previously unrecognized aquifer and provide potential avenues for interbasin flow. Geophysical data indicate that basin-fill sediments are about 2,000 feet thick near the center of the basin. The geometry of the aquifers, however, remains largely unknown. Measurements of water levels, pressure head, flow rate, water temperature, and specific conductance at 19 wells show little change from 1988 to 1990. Chemically, ground water begins as a dilute sodium and calcium bicarbonate water in the mountain blocks, changes to a slightly saline sodium bicarbonate solution beneath the alluvial fans, and becomes a briny sodium chloride water near the playa. Concentrations of several inorganic constituents in the briny water near the playa commonly exceed Nevada drinking-water standards. Ground water in the Honey Lake basin and Smoke Creek Desert basin has similar stable-isotope composition, except near Sand Pass. If interbasin flow takes place, it likely occurs at depths greater than 400-600 feet beneath Sand Pass or through volcanic rocks to the north of Sand Pass. Measure- ments of streamflow indicate that about 2,800 acre-feet/year discharged from volcanic rocks to streamflow and a minimum of 7.300 acre-feet/year infiltrated and recharged unconsolidated sediments near Smoke, Buffalo, and Squaw Creeks during the period of study. Also about 1,500 acre-feet per year was lost to evapotranspiration along the channel of Smoke Creek, and about 1,680 acre-feet per year of runoff from Smoke, Buffalo, and Squaw Creeks was probably lost to evaporation from the

  6. The Auckland volcanic field, New Zealand: Geophysical evidence for structural and spatio-temporal relationships

    Science.gov (United States)

    Cassidy, John; Locke, Corinne A.

    2010-08-01

    Geophysical data from the monogenetic Auckland volcanic field reveal complex structural and spatio-temporal relationships at different scales. The volcanic field is coincident with regional magnetic and gravity anomalies that mark a major crustal suture and with a discontinuity marking a significant structural asperity. Here, the linear regional magnetic anomaly splays into a wide band of NNW-trending lineaments, arising from serpentinised shear zones in the upper crust, that matches the extent of the volcanic field and that may reflect a region of crustal weakness creating preferential permeability. However, there appears to be no simple correlation between the locations of individual vents and these lineaments that might delineate more shallow structural controls with this orientation, probably as a consequence of other structural influences. High-resolution aeromagnetic data over the volcanic field show that the volcanoes have a wide range of magnetic signatures indicating a variability of subsurface structure. Scoria cone volcanoes typically have strong anomalies (up to several 100 nT) whilst tuff-ring volcanoes typically have weak anomalies (less than 50 nT), though the surface geology is not always an indicator of the nature and extent of the subsurface deposits. Both cone and tuff-ring volcanoes in the Auckland field appear to be underlain by subsurface bowl-shaped bodies of basalt, implying that their eruption histories commonly involve lava ponding into early excavated craters. The present geophysical data give no evidence for subsurface dyke-like structures or for substantial near-surface volumes of basaltic rocks where there are no known eruption centres or buried flows. Aeromagnetic and palaeomagnetic data suggest that a number of adjacent vents with an implied structural linkage may be contemporaneous, though other examples occur where vents of clearly different ages exploit the same apparent structure. A unique feature of the Auckland field is that at

  7. La Purísima volcanic field, Baja California Sur (Mexico): Miocene to Quaternary volcanism related to subduction and opening of an asthenospheric window

    Science.gov (United States)

    Bellon, Hervé; Aguillón-Robles, Alfredo; Calmus, Thierry; Maury, René C.; Bourgois, Jacques; Cotten, Joseph

    2006-04-01

    Geological mapping and geochemical analyses combined with 40K- 40Ar ages for lavas from the Late Miocene to Quaternary La Purísima volcanic field (Baja California Sur) provide evidence for five volcanic events. These, in turn, may reflect plate interactions in the region. The oldest event (event 1), prior to 11 Ma, corresponds to the emission of normal to K-rich calc-alkaline lavas, exposed as large mesas in the eastern part of the studied area and as pyroclastic breccias and volcaniclastic sediments to the west. It is associated with the end of the Comondú arc activity resulting from subduction of the Farallon and Guadalupe plates. Between 10.6 and 8.8 Ma (event 2), magnesian andesites and tholeiites were emplaced. At 5.5 Ma (event 3) and 2.5 Ma (event 4) small volumes of magnesian andesites erupted in the central and southern parts of the volcanic field. Finally, between 1.2 Ma and Holocene (event 5), numerous basaltic and magnesian andesitic fissural and central emissions resulted in the formation of strombolian cones and associated lava flows, mainly distributed within a NNW-SSE trending graben located SE of the town of La Purísima. Magmatic events 2 to 5 occurred well after the supposed end of the subduction event. Their geochemical characteristics are still typical of subduction-modified sources and possibly indicate partial melting of hot slab and formation of an asthenospheric window due to a slab rupture event which followed ridge-trench collision, prior to the continental breakup of the Gulf of California extensional province.

  8. Volcanism on differentiated asteroids (Invited)

    Science.gov (United States)

    Wilson, L.

    2013-12-01

    after passing through optically dense fire fountains. At low eruption rates and high volatile contents many clasts cooled to form spatter or cinder deposits, but at high eruption rates and low volatile contents most clasts landed hot and coalesced into lava ponds to feed lava flows. Lava flow thickness varies with surface slope, acceleration due to gravity, and lava yield strength induced by cooling. Low gravity on asteroids caused flows to be relatively thick which reduced the effects of cooling, and many flows probably attained lengths of tens of km and stopped as a result of cessation of magma supply from the reservoir rather than cooling. On most asteroids larger than 100 km radius experiencing more than ~30% mantle melting, the erupted volcanic deposits will have buried the original chondritic surface layers of the asteroid to such great depths that they were melted, or at least heavily thermally metamorphosed, leaving no present-day meteoritical evidence of their prior existence. Tidal stresses from close encounters between asteroids and proto-planets may have very briefly increased melting and melt migration speeds in asteroid interiors but only gross structural disruption would have greatly have changed volcanic histories.

  9. A model for calculating eruptive volumes for monogenetic volcanoes — Implication for the Quaternary Auckland Volcanic Field, New Zealand

    Science.gov (United States)

    Kereszturi, Gábor; Németh, Károly; Cronin, Shane J.; Agustín-Flores, Javier; Smith, Ian E. M.; Lindsay, Jan

    2013-10-01

    Monogenetic basaltic volcanism is characterised by a complex array of behaviours in the spatial distribution of magma output and also temporal variability in magma flux and eruptive frequency. Investigating this in detail is hindered by the difficulty in evaluating ages of volcanic events as well as volumes erupted in each volcano. Eruptive volumes are an important input parameter for volcanic hazard assessment and may control eruptive scenarios, especially transitions between explosive and effusive behaviour and the length of eruptions. Erosion, superposition and lack of exposure limit the accuracy of volume determination, even for very young volcanoes. In this study, a systematic volume estimation model is developed and applied to the Auckland Volcanic Field in New Zealand. In this model, a basaltic monogenetic volcano is categorised in six parts. Subsurface portions of volcanoes, such as diatremes beneath phreatomagmatic volcanoes, or crater infills, are approximated by geometrical considerations, based on exposed analogue volcanoes. Positive volcanic landforms, such as scoria/spatter cones, tephras rings and lava flow, were defined by using a Light Detection and Ranging (LiDAR) survey-based Digital Surface Model (DSM). Finally, the distal tephra associated with explosive eruptions was approximated using published relationships that relate original crater size to ejecta volumes. Considering only those parts with high reliability, the overall magma output (converted to Dense Rock Equivalent) for the post-250 ka active Auckland Volcanic Field in New Zealand is a minimum of 1.704 km3. This is made up of 1.329 km3 in lava flows, 0.067 km3 in phreatomagmatic crater lava infills, 0.090 km3 within tephra/tuff rings, 0.112 km3 inside crater lava infills, and 0.104 km3 within scoria cones. Using the minimum eruptive volumes, the spatial and temporal magma fluxes are estimated at 0.005 km3/km2 and 0.007 km3/ka. The temporal-volumetric evolution of Auckland is

  10. Modeling Io volcanism: Maximum volcanic temperatures, depths of melting and magma composition

    Science.gov (United States)

    Crumpler, L. S.; Strom, R. G.

    1984-01-01

    Interim results of thermal and structural modeling of volcanism on Io were presented. The final results of the modeling are summarized. The basic analysis is an evaluation of the magma trigger mechanism for initiating and maintaining eruptions. Secondary aspects include models of the mechanical mode of magma emplacement, interactions with a sulphur-rich upper crust, and more speculative implications for Io's volcanism.

  11. Volcanic Supersites as cross-disciplinary laboratories

    Science.gov (United States)

    Provenzale, Antonello; Beierkuhnlein, Carl; Giamberini, Mariasilvia; Pennisi, Maddalena; Puglisi, Giuseppe

    2017-04-01

    Volcanic Supersites, defined in the frame of the GEO-GSNL Initiative, are usually considered mainly for their geohazard and geological characteristics. However, volcanoes are extremely challenging areas from many other points of view, including environmental and climatic properties, ecosystems, hydrology, soil properties and biogeochemical cycling. Possibly, volcanoes are closer to early Earth conditions than most other types of environment. During FP7, EC effectively fostered the implementation of the European volcano Supersites (Mt. Etna, Campi Flegrei/Vesuvius and Iceland) through the MED-SUV and FUTUREVOLC projects. Currently, the large H2020 project ECOPOTENTIAL (2015-2019, 47 partners, http://www.ecopotential-project.eu/) contributes to GEO/GEOSS and to the GEO ECO Initiative, and it is devoted to making best use of remote sensing and in situ data to improve future ecosystem benefits, focusing on a network of Protected Areas of international relevance. In ECOPOTENTIAL, remote sensing and in situ data are collected, processed and used for a better understanding of the ecosystem dynamics, analysing and modelling the effects of global changes on ecosystem functions and services, over an array of different ecosystem types, including mountain, marine, coastal, arid and semi-arid ecosystems, and also areas of volcanic origin such as the Canary and La Reunion Islands. Here, we propose to extend the network of the ECOPOTENTIAL project to include active Volcanic Supersites, such as Mount Etna and other volcanic Protected Areas, and we discuss how they can be included in the framework of the ECOPOTENTIAL workflow. A coordinated and cross-disciplinary set of studies at these sites should include geological, biological, ecological, biogeochemical, climatic and biogeographical aspects, as well as their relationship with the antropogenic impact on the environment, and aim at the global analysis of the volcanic Earth Critical Zone - namely, the upper layer of the Earth

  12. Volcanic Lightning in Eruptions of Sakurajima Volcano

    Science.gov (United States)

    Edens, Harald; Thomas, Ronald; Behnke, Sonja; McNutt, Stephen; Smith, Cassandra; Farrell, Alexandra; Van Eaton, Alexa; Cimarelli, Corrado; Cigala, Valeria; Eack, Ken; Aulich, Graydon; Michel, Christopher; Miki, Daisuke; Iguchi, Masato

    2016-04-01

    In May 2015 a field program was undertaken to study volcanic lightning at the Sakurajima volcano in southern Japan. One of the main goals of the study was to gain a better understanding of small electrical discharges in volcanic eruptions, expanding on our earlier studies of volcanic lightning at Augustine and Redoubt volcanoes in Alaska, USA, and Eyjafjallajökull in Iceland. In typical volcanic eruptions, electrical activity occurs at the onset of an eruption as a near-continual production of VHF emissions at or near to the volcanic vent. These emissions can occur at rates of up to tens of thousands of emissions per second, and are referred to as continuous RF. As the ash cloud expands, small-scale lightning flashes of several hundred meters length begin to occur while the continuous RF ceases. Later on during the eruption larger-scale lightning flashes may occur within the ash cloud that are reminiscent of regular atmospheric lightning. Whereas volcanic lightning flashes are readily observed and reasonably well understood, the nature and morphology of the events producing continuous RF are unknown. During the 2015 field program we deployed a comprehensive set of instrumentation, including a 10-station 3-D Lightning Mapping Array (LMA) that operated in 10 μs high time resolution mode, slow and fast ΔE antennas, a VHF flat-plate antenna operating in the 20-80 MHz band, log-RF waveforms within the 60-66 MHz band, an infra-red video camera, a high-sensitivity Watec video camera, two high-speed video cameras, and still cameras. We give an overview of the Sakurajima field program and present preliminary results using correlated LMA, waveforms, photographs and video recordings of volcanic lightning at Sakurajima volcano.

  13. Pulsar average waveforms and hollow cone beam models

    Science.gov (United States)

    Backer, D. C.

    1975-01-01

    An analysis of pulsar average waveforms at radio frequencies from 40 MHz to 15 GHz is presented. The analysis is based on the hypothesis that the observer sees one cut of a hollow-cone beam pattern and that stationary properties of the emission vary over the cone. The distributions of apparent cone widths for different observed forms of the average pulse profiles (single, double/unresolved, double/resolved, triple and multiple) are in modest agreement with a model of a circular hollow-cone beam with random observer-spin axis orientation, a random cone axis-spin axis alignment, and a small range of physical hollow-cone parameters for all objects.

  14. Techniques for optimizing nanotips derived from frozen taylor cones

    Science.gov (United States)

    Hirsch, Gregory

    2017-12-05

    Optimization techniques are disclosed for producing sharp and stable tips/nanotips relying on liquid Taylor cones created from electrically conductive materials with high melting points. A wire substrate of such a material with a preform end in the shape of a regular or concave cone, is first melted with a focused laser beam. Under the influence of a high positive potential, a Taylor cone in a liquid/molten state is formed at that end. The cone is then quenched upon cessation of the laser power, thus freezing the Taylor cone. The tip of the frozen Taylor cone is reheated by the laser to allow its precise localized melting and shaping. Tips thus obtained yield desirable end-forms suitable as electron field emission sources for a variety of applications. In-situ regeneration of the tip is readily accomplished. These tips can also be employed as regenerable bright ion sources using field ionization/desorption of introduced chemical species.

  15. Volcanic Alert System (VAS) developed during the (2011-2013) El Hierro (Canary Islands) volcanic process

    Science.gov (United States)

    Ortiz, Ramon; Berrocoso, Manuel; Marrero, Jose Manuel; Fernandez-Ros, Alberto; Prates, Gonçalo; De la Cruz-Reyna, Servando; Garcia, Alicia

    2014-05-01

    In volcanic areas with long repose periods (as El Hierro), recently installed monitoring networks offer no instrumental record of past eruptions nor experience in handling a volcanic crisis. Both conditions, uncertainty and inexperience, contribute to make the communication of hazard more difficult. In fact, in the initial phases of the unrest at El Hierro, the perception of volcanic risk was somewhat distorted, as even relatively low volcanic hazards caused a high political impact. The need of a Volcanic Alert System became then evident. In general, the Volcanic Alert System is comprised of the monitoring network, the software tools for the analysis of the observables, the management of the Volcanic Activity Level, and the assessment of the threat. The Volcanic Alert System presented here places special emphasis on phenomena associated to moderate eruptions, as well as on volcano-tectonic earthquakes and landslides, which in some cases, as in El Hierro, may be more destructive than an eruption itself. As part of the Volcanic Alert System, we introduce here the Volcanic Activity Level which continuously applies a routine analysis of monitoring data (particularly seismic and deformation data) to detect data trend changes or monitoring network failures. The data trend changes are quantified according to the Failure Forecast Method (FFM). When data changes and/or malfunctions are detected, by an automated watchdog, warnings are automatically issued to the Monitoring Scientific Team. Changes in the data patterns are then translated by the Monitoring Scientific Team into a simple Volcanic Activity Level, that is easy to use and understand by the scientists and technicians in charge for the technical management of the unrest. The main feature of the Volcanic Activity Level is its objectivity, as it does not depend on expert opinions, which are left to the Scientific Committee, and its capabilities for early detection of precursors. As a consequence of the El Hierro

  16. Water-quality effects on Baker Lake of recent volcanic activity at Mount Baker, Washington

    Science.gov (United States)

    Bortleson, Gilbert Carl; Wilson, Reed T.; Foxworthy, B.L.

    1976-01-01

    Increased volcanic activity on Mount Baker, which began in March 1975, represents the greatest known activity of a Cascade Range volcano since eruptions at Lassen Peak, Calif. during 1914-17. Emissions of dust and increased emanations of steam, other gases, and heat from the Sherman Crater area of the mountain focused attention on the possibility of hazardous events, including lava flows, pyroclastic eruptions, avalanches, and mudflows. However, the greatest undesirable natural results that have been observed after one year of the increased activity are an increase in local atmospheric pollution and a decrease in the quality of some local water resources, including Baker Lake. Baker Lake, a hydropower reservoir behind Upper Baker Dam, supports a valuable fishery resource and also is used for recreation. The lake's feedwater is from Baker River and many smaller streams, some of which, like Boulder Creek, drain parts of Mount Baker. Boulder Creek receives water from Sherman Crater, and its channel is a likely route for avalanches or mudflows that might originate in the crater area. Boulder Creek drains only about 5 percent of the total drainage area of Baker Lake, but during 1975 carried sizeable but variable loads of acid and dissolved minerals into the lake. Sulfurous gases and the fumarole dust from Sherman Crater are the main sources for these materials, which are brought into upper Boulder Creek by meltwater from the crater. In September 1973, before the increased volcanic activity, Boulder Creek near the lake had a pH of 6.0-6.6; after the increase the pH ranged as low as about 3.5. Most nearby streams had pH values near 7. On April 29, in Boulder Creek the dissolved sulfate concentration was 6 to 29 times greater than in nearby creeks or in Baker River; total iron was 18-53 times greater than in nearby creeks; and other major dissolved constituents generally 2 to 7 times greater than in the other streams. The short-term effects on Baker Lake of the acidic

  17. Closed graph and open mapping theorems for normed cones

    Indian Academy of Sciences (India)

    Abstract. A quasi-normed cone is a pair (X, p) such that X is a (not necessarily cancellative) cone and q is a quasi-norm on X. The aim of this paper is to prove a closed graph and an open mapping type theorem for quasi-normed cones. This is done with the help of appropriate notions of completeness, continuity and ...

  18. Power Analysis of an Automated Dynamic Cone Penetrometer

    Science.gov (United States)

    2015-09-01

    ARL-TR-7494 ● SEP 2015 US Army Research Laboratory Power Analysis of an Automated Dynamic Cone Penetrometer by C Wesley...Automated Dynamic Cone Penetrometer by C Wesley Tipton IV and Donald H Porschet Sensors and Electron Devices Directorate, ARL...Dynamic Cone Penetrometer 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) C Wesley Tipton IV and Donald H

  19. Bat eyes have ultraviolet-sensitive cone photoreceptors.

    Directory of Open Access Journals (Sweden)

    Brigitte Müller

    Full Text Available Mammalian retinae have rod photoreceptors for night vision and cone photoreceptors for daylight and colour vision. For colour discrimination, most mammals possess two cone populations with two visual pigments (opsins that have absorption maxima at short wavelengths (blue or ultraviolet light and long wavelengths (green or red light. Microchiropteran bats, which use echolocation to navigate and forage in complete darkness, have long been considered to have pure rod retinae. Here we use opsin immunohistochemistry to show that two phyllostomid microbats, Glossophaga soricina and Carollia perspicillata, possess a significant population of cones and express two cone opsins, a shortwave-sensitive (S opsin and a longwave-sensitive (L opsin. A substantial population of cones expresses S opsin exclusively, whereas the other cones mostly coexpress L and S opsin. S opsin gene analysis suggests ultraviolet (UV, wavelengths <400 nm sensitivity, and corneal electroretinogram recordings reveal an elevated sensitivity to UV light which is mediated by an S cone visual pigment. Therefore bats have retained the ancestral UV tuning of the S cone pigment. We conclude that bats have the prerequisite for daylight vision, dichromatic colour vision, and UV vision. For bats, the UV-sensitive cones may be advantageous for visual orientation at twilight, predator avoidance, and detection of UV-reflecting flowers for those that feed on nectar.

  20. Cone formation on copper by ion-beam sputtering

    International Nuclear Information System (INIS)

    Den, A.K.; Ghose, D.

    1991-01-01

    The phenomenon of cone formation on solid surfaces by ion-beam sputtering has been the subject of extensive studies in recent years. The reason for this is that not only do such studies provide a better understanding of the physical processes underlying the cone formation, they also show the importance and relevance of ion-induced textured surfaces in different technologies and experimental techniques. Usually cones are formed by impurity contamination of the target surface during sputtering. In the absence of impurities, a particular target crystallography can result in a high density of cone formation. In the present work the formation and morphologies of cones were studied on a Cu substrate by seeding W-impurities during Kr + -ion sputtering. The results showed that the surface was eroded unevenly and several regions of densely populated cones were formed. The simultaneous appearance of short and tall cones apparently supports both the left-standing and the growth models of cone formation. The cone apex angle was measured and also theoretically predicted. The discrepancy between the two values is possibly due to the neglect of so-called secondary effects. (author)

  1. Volcanic activity: a review for health professionals.

    Science.gov (United States)

    Newhall, C G; Fruchter, J S

    1986-03-01

    Volcanoes erupt magma (molten rock containing variable amounts of solid crystals, dissolved volatiles, and gas bubbles) along with pulverized pre-existing rock (ripped from the walls of the vent and conduit). The resulting volcanic rocks vary in their physical and chemical characteristics, e.g., degree of fragmentation, sizes and shapes of fragments, minerals present, ratio of crystals to glass, and major and trace elements composition. Variability in the properties of magma, and in the relative roles of magmatic volatiles and groundwater in driving an eruption, determine to a great extent the type of an eruption; variability in the type of an eruption in turn influences the physical characteristics and distribution of the eruption products. The principal volcanic hazards are: ash and larger fragments that rain down from an explosion cloud (airfall tephra and ballistic fragments); flows of hot ash, blocks, and gases down the slopes of a volcano (pyroclastic flows); "mudflows" (debris flows); lava flows; and concentrations of volcanic gases in topographic depressions. Progress in volcanology is bringing improved long- and short-range forecasts of volcanic activity, and thus more options for mitigation of hazards. Collaboration between health professionals and volcanologists helps to mitigate health hazards of volcanic activity.

  2. Ages of plains volcanism on Mars

    Science.gov (United States)

    Hauber, Ernst; Jagert, Felix; Broz, Petr

    2010-05-01

    Plain-style volcanism [1] is widespread in the Tharsis and Elysium volcanic provinces on Mars, [2,3]. Detailed images and topographic data reveal the morphology and topography of clusters of low shields and associated lava flows. The landforms of plains volcanism on Mars have all well-known terrestrial analogues in basaltic volcanic regions, such as Hawaii, Iceland, and in particular the Snake River Plains [4]. The very gentle flank slopes (J. (1981) Icarus, 45, 586-601. [3] Hodges C.A. and Moore H.J. (1994) Atlas of volcanic features on Mars: USGS Prof. Paper 1534, 194 p. [4] Hauber E. et al. (2009) J. Volcanol. Geotherm. Res. 185, 69-95. [5] Wilson L. et al. (2009) J. Volcanol. Geotherm. Res. 185, 28-46. [6] Vaucher, J. et al. (2009) Icarus 204, 418-442. [7] Baratoux D. et al. (2009) J. Volcanol. Geotherm. Res. 185, 47-68. [8] Bleacher J.E. et al. (2009) J. Volcanol. Geotherm. Res. 185, 96-102. [9] Ivanov B.A. (2001) Space Sci. Rev. 96, 87-104. [10] Hartmann W.H. and Neukum G. (2001) Space Sci. Rev. 96, 165-194 [11] Kneissl T. et al. (2010) LPS XVI, submitted. [12] Michael, G.G. and Neukum G. (2010) Earth Planet. Sci. Lett., in press. . [13] Malin M.C. et al. (2007) JGR 112, E05S04, doi: 10.1029/2006JE002808.

  3. Preliminary Findings of Petrology and Geochemistry of The Aladaǧ Volcanic System and Surrounding Areas (Kars, Turkey)

    Science.gov (United States)

    Duru, Olgun; Keskin, Mehmet

    2017-04-01

    Between the towns of Sarıkamış and Kaǧızman, NE Turkey, a medium-sized strato-volcano with satellite cones and domes on its slopes unconformably overlies the Erzurum-Kars Volcanic Plateau (EKVP) with a subhorizontal contact. It is called the Aladaǧ volcanic system (AVS). Dating results indicate that the AVS is Pliocene in age. The EKVP is known to be formed by a widespread volcanism between Middle Miocene to Pliocene. The young volcanism in E Turkey including the study area is linked to a collision between the Eurasia and Arabian continents, started almost 15 Ma ago. The EKVP lies over 2000 m above the sea level, and is deeply cut by the river Aras. On the slopes of the valley, one of the best volcano-stratigraphic transects of Eastern Anatolia, almost half a km thick, is exposed. That transect is composed of aphyric andesites-dacites, ignimbrites, tuffs, perlite and obsidian bands. Pyroclastic fall and surge-related pumice deposits are also widespread. Top of the plateau is composed of the andesitic to basaltic andesitic lavas containing plagioclase (Plg) and ortho/clino pyroxene (Opx/Cpx) phenocrysts set in glassy groundmass. In the northwest of the study area, an eroded stratovolcano, probably coeval with the plateau sequence is situated. It also consists of high-silica rhyolites and pyroclastic equivalents. The AVS is composed basically of intermediate lavas. The largest volcanic edifice of the Aladaǧ volcanic system, namely the Greater Aladaǧ stratovolcano reaches up to 3000 m height and includes a horseshoe shaped crater open to the North. Small volcanic cones and domes sit on the flanks of the Greater Aladaǧ volcano. The Aladaǧ lavas are divided into four sub-groups on the basis of their stratigraphic positions, mineral assemblages and textural properties. (1) The oldest products of the Greater Aladaǧ stratovolcano are andesitic and dasitic lavas. They directly sit on the EKVP. These are Plg and Opx/Cpx bearing lavas with porphric, vitrophyric

  4. Remote Sensing and GIS as Tools for Identifying Risk for Phreatomagmatic Eruptions in the Bishoftu Volcanic Field, Ethiopia

    Science.gov (United States)

    Pennington, H. G.; Graettinger, A.

    2017-12-01

    Bishoftu is a fast-growing town in the Oromia region of Ethiopia, located 47 km southeast of the nation's capital, Addis Ababa. It is situated atop a monogenetic basaltic volcanic field, called the Bishoftu Volcanic Field (BVF), which is composed of maar craters, scoria cones, lava flows, and rhyolite domes. Although not well dated, the morphology and archeological evidence have been used to infer a Holocene age, indicating that the community is exposed to continued volcanic risk. The presence of phreatomagmatic constructs in particular indicates that the hazards are not only vent-localized, but may have far reaching impacts. Hazard mapping is an essential tool for evaluating and communicating risks. This study presents the results of GIS analyses of proximal and distal syn-eruptive hazards associated with phreatomagmatic eruptions in the BVF. A digitized infrastructure map based on a SPOT 6 satellite image is used to identify the areas at risk from eruption scenarios. Parameters such as wind direction, vent location, and explosion energy are varied for hazard simulations to quantify the area impacted by different eruption scenarios. Proximal syn-eruptive hazards include tephra fall, base pyroclastic surges, and ballistic bombs. Distal hazards include predominantly ash fall. Eruption scenarios are simulated using Eject and Plumeria models as well as similar case studies from other urban volcanic fields. Within 5 km of the volcanic field center, more than 30 km2 of residential and commercial/industrial infrastructure will be damaged by proximal syn-eruptive hazards, in addition to 34 km2 of agricultural land, 291 km of roads, more than 10 km of railway, an airport, and two health centers. Within 100 km of the volcanic field center, ash fall will affect 3946 km2 of agricultural land, 179 km2 of residential land, and 28 km2 of commercial/industrial land. Approximately 2700 km of roads and railways, 553 km of waterways, an airport, and 14 health centers are located

  5. National volcanic ash operations plan for aviation

    Science.gov (United States)

    ,; ,

    2007-01-01

    The National Aviation Weather Program Strategic Plan (1997) and the National Aviation Weather Initiatives (1999) both identified volcanic ash as a high-priority informational need to aviation services. The risk to aviation from airborne volcanic ash is known and includes degraded engine performance (including flameout), loss of visibility, failure of critical navigational and operational instruments, and, in the worse case, loss of life. The immediate costs for aircraft encountering a dense plume are potentially major—damages up to $80 million have occurred to a single aircraft. Aircraft encountering less dense volcanic ash clouds can incur longer-term costs due to increased maintenance of engines and external surfaces. The overall goal, as stated in the Initiatives, is to eliminate encounters with ash that could degrade the in-flight safety of aircrews and passengers and cause damage to the aircraft. This goal can be accomplished by improving the ability to detect, track, and forecast hazardous ash clouds and to provide adequate warnings to the aviation community on the present and future location of the cloud. To reach this goal, the National Aviation Weather Program established three objectives: (1) prevention of accidental encounters with hazardous clouds; (2) reduction of air traffic delays, diversions, or evasive actions when hazardous clouds are present; and (3) the development of a single, worldwide standard for exchange of information on airborne hazardous materials. To that end, over the last several years, based on numerous documents (including an OFCMsponsored comprehensive study on aviation training and an update of Aviation Weather Programs/Projects), user forums, and two International Conferences on Volcanic Ash and Aviation Safety (1992 and 2004), the Working Group for Volcanic Ash (WG/VA), under the OFCM-sponsored Committee for Aviation Services and Research, developed the National Volcanic Ash Operations Plan for Aviation and Support of the

  6. Light-cone quantization and QCD phenomenology

    International Nuclear Information System (INIS)

    Brodsky, S.J.; Robertson, D.G.

    1995-01-01

    In principle, quantum chromodynamics provides a fundamental description of hadronic and nuclear structure and dynamics in terms of their elementary quark and gluon degrees of freedom. In practice, the direct application of QCD to reactions involving the structure of hadrons is extremely complex because of the interplay of nonperturbative effects such as color confinement and multi-quark coherence. A crucial tool in analyzing such phenomena is the use of relativistic light-cone quantum mechanics and Fock state methods to provide tractable and consistent treatments of relativistic many-body systems. In this article we present an overview of this formalism applied to QCD, focusing in particular on applications to the final states in deep inelastic lepton scattering that will be relevant for the proposed European Laboratory for Electrons (ELFE), HERMES, HERA, SLAC, and CEBAF. We begin with a brief introduction to light-cone field theory, stressing how it many allow the derivation of a constituent picture, analogous to the constituent quark model, from QCD. We then discuss several applications of the light-cone Fock state formalism to QCD phenomenology. The Fock state representation includes all quantum fluctuations of the hadron wavefunction, including far off-shell configurations such as intrinsic charm and, in the case of nuclei, hidden color. In some applications, such as exclusive processes at large momentum transfer, one can make first-principle predictions using factorization theorems which separate the hard perturbative dynamics from the nonpertubative physics associated with hadron binding. The Fock state components of the hadron with small transverse size, which dominate hard exclusive reactions, have small color dipole moments and thus diminished hadronic interactions. Thus QCD predicts minimal absorptive corrections, i.e., color transparency for quasi-elastic exclusive reactions in nuclear targets at large momentum transfer

  7. Chloride currents in cones modify feedback from horizontal cells to cones in goldfish retina

    NARCIS (Netherlands)

    Endeman, Duco; Fahrenfort, Iris; Sjoerdsma, Trijntje; Steijaert, Marvin; ten Eikelder, Huub; Kamermans, Maarten

    2012-01-01

    In neuronal systems, excitation and inhibition must be well balanced to ensure reliable information transfer. The cone/horizontal cell (HC) interaction in the retina is an example of this. Because natural scenes encompass an enormous intensity range both in temporal and spatial domains, the balance

  8. Revisit of combined parallel-beam/cone-beam or fan-beam/cone-beam imaging.

    Science.gov (United States)

    Zeng, Gengsheng L

    2013-10-01

    This aim of this paper is to revisit the parallel-beam/cone-beam or fan-beam/cone-beam imaging configuration, and to investigate whether this configuration has any advantages. Twenty years ago, it was suggested to simultaneously use a parallel-beam (or a fan-beam) collimator and a cone-beam collimator to acquire single photon emission computed tomography data. The motivation was that the parallel-beam (or the fan-beam) collimator can provide sufficient sampling, while the cone-beam collimator is able to provide higher photon counts. Even with higher total counts, this hybrid system does not give significant improvement (if any) in terms of image noise and artifacts reduction. If a conventional iterative maximum-likelihood expectation-maximization algorithm is used to reconstruct the image, the resultant reconstruction may be worse than the parallel-beam-only (or fan-beam-only) system. This paper uses the singular value decomposition (SVD) analysis to explain this phenomenon. The SVD results indicate that the parallel-beam-only and the fan-beam-only system outperform the combined systems. The optimal imaging system does not necessary to be the one that generates the projections with highest signal-to-noise ratio and best resolution.

  9. Tropical Volcanic Soils From Flores Island, Indonesia

    Directory of Open Access Journals (Sweden)

    Hikmatullah

    2010-01-01

    Full Text Available Soils that are developed intropical region with volcanic parent materials have many unique properties, and high potential for agricultural use.The purpose of this study is to characterize the soils developed on volcanic materials from Flores Island, Indonesia,and to examine if the soils meet the requirements for andic soil properties. Selected five soils profiles developed fromandesitic volcanic materials from Flores Island were studied to determine their properties. They were compared intheir physical, chemical and mineralogical characteristics according to their parent material, and climatic characteristicdifferent. The soils were developed under humid tropical climate with ustic to udic soil moisture regimes withdifferent annual rainfall. The soils developed from volcanic ash parent materials in Flores Island showed differentproperties compared to the soils derived from volcanic tuff, even though they were developed from the sameintermediary volcanic materials. The silica contents, clay mineralogy and sand fractions, were shown as the differences.The different in climatic conditions developed similar properties such as deep solum, dark color, medium texture, andvery friable soil consistency. The soils have high organic materials, slightly acid to acid, low to medium cationexchange capacity (CEC. The soils in western region have higher clay content and showing more developed than ofthe eastern region. All the profiles meet the requirements for andic soil properties, and classified as Andisols order.The composition of sand mineral was dominated by hornblende, augite, and hypersthenes with high weatherablemineral reserves, while the clay fraction was dominated by disordered kaolinite, and hydrated halloysite. The soilswere classified into subgroup as Thaptic Hapludands, Typic Hapludands, and Dystric Haplustands

  10. Cone penetrometer: Innovative technology summary report

    International Nuclear Information System (INIS)

    1996-04-01

    Cone penetrometer technology (CPT) provides cost-effective, real-time data for use in the characterization of the subsurface. Recent innovations in this baseline technology allow for improved access to the subsurface for environmental restoration applications. The technology has been improved by both industry and government agencies and is constantly advancing due to research efforts. The U.S. Department of Energy (DOE) Office of Science and Technology (formerly Technology Development) has contributed significantly to these efforts. This report focuses on the advancements made in conjunction with DOE's support but recognizes Department of Defense (DOD) and industry efforts

  11. Mach cone in a shallow granular fluid

    International Nuclear Information System (INIS)

    Heil, Patrick; Rericha, E. C.; Goldman, Daniel I.; Swinney, Harry L.

    2004-01-01

    We study the V-shaped wake (Mach cone) formed by a cylindrical rod moving through a thin, vertically vibrated granular layer. The wake, analogous to a shock (hydraulic jump) in shallow water, appears for rod velocities v R greater than a critical velocity c. We measure the half angle θ of the wake as a function of v R and layer depth h. The angle satisfies the Mach relation, sin θ=c/v R , where c=√(gh), even for h as small as one-particle diameter

  12. Origin of the magmatic varieties of the Serdán-Oriental Basin, eastern Trans-Mexican Volcanic Belt

    Science.gov (United States)

    Mori, L.; Gomez-Tuena, A.; Becerra Torres, E.; Landa-Piedra, L.

    2013-12-01

    Quaternary magmatic activity in the Serdán-Oriental Basin (SOB) of the eastern Trans-Mexican Volcanic Belt produced mafic-intermediate monogenetic cones of variable geochemical affinities, that are built on >45 km thick crust at ~360-420 km distance from the trench, in a region under which the Cocos plate lays at >120 km depth. For these features, the volcanic sequences of the SOB offer the opportunity to understand the mechanisms of element recycling and the origin of magmatic diversity in the Mexican arc. Our data permit to observe a relationship between the geochemical diversity of magmatism and its geographic distribution. Most cones emplaced at the volcanic front, south of Malinche and Pico de Orizaba stratovolcanoes, vary in composition from calc-alkaline basalt to andesite, and display typical arc-like geochemical features such as high LILE-LREE/HFSE and moderate REE ratios. The southern part of the basin also hosts a few high-K mafic cones with stronger LILE-LREE enrichments at similar HFSE contents, and more fractionated REE patterns; interestingly, high Gd/Yb ratios in these rocks are coupled with high Nb/Ta and Sm/Zr. The basalts and basaltic andesites emplaced at larger distance from the trench display progressively higher Ti and HFSE contents than those of the volcanic front at similar LILE. On the other hand, the mafic cones emplaced north of Malinche display the lowest LILE-LREE/HFSE ratios, with high-Nb compositions similar to those of intraplate magmas. The distribution pattern of volcanism recognized in the SOB is consistent with different degrees of mantle melting produced by variable contributions from the oceanic plate. In particular, decreasing Ba-La/Nb and Zr/Nb ratios in the volcanic products emplaced from the front to the rear-arc reflect a gradual decrease in slab fluxes added to the wedge, and hence lower degrees of mantle melting, as the Cocos plate sinks to higher depths. The geochemical features of the high-K suite indicate that the

  13. Volcanic air pollution hazards in Hawaii

    Science.gov (United States)

    Elias, Tamar; Sutton, A. Jeff

    2017-04-20

    Noxious sulfur dioxide gas and other air pollutants emitted from Kīlauea Volcano on the Island of Hawai‘i react with oxygen, atmospheric moisture, and sunlight to produce volcanic smog (vog) and acid rain. Vog can negatively affect human health and agriculture, and acid rain can contaminate household water supplies by leaching metals from building and plumbing materials in rooftop rainwater-catchment systems. U.S. Geological Survey scientists, along with health professionals and local government officials are working together to better understand volcanic air pollution and to enhance public awareness of this hazard.

  14. Volcanic Eruptions and Climate: Outstanding Research Issues

    Science.gov (United States)

    Robock, Alan

    2016-04-01

    Large volcanic eruptions inject sulfur gases into the stratosphere, which convert to sulfate aerosols with an e-folding residence time of about one year. The radiative and chemical effects of this aerosol cloud produce responses in the climate system. Based on observations after major eruptions of the past and experiments with numerical models of the climate system, we understand much about their climatic impact, but there are also a number of unanswered questions. Volcanic eruptions produce global cooling, and are an important natural cause of interannual, interdecadal, and even centennial-scale climate change. One of the most interesting volcanic effects is the "winter warming" of Northern Hemisphere continents following major tropical eruptions. During the winter in the Northern Hemisphere following every large tropical eruption of the past century, surface air temperatures over North America, Europe, and East Asia were warmer than normal, while they were colder over Greenland and the Middle East. This pattern and the coincident atmospheric circulation correspond to the positive phase of the Arctic Oscillation. While this response is observed after recent major eruptions, most state-of-the-art climate models have trouble simulating winter warming. Why? High latitude eruptions in the Northern Hemisphere, while also producing global cooling, do not have the same impact on atmospheric dynamics. Both tropical and high latitude eruptions can weaken the Indian and African summer monsoon, and the effects can be seen in past records of flow in the Nile and Niger Rivers. Since the Mt. Pinatubo eruption in the Philippines in 1991, there have been no large eruptions that affected climate, but the cumulative effects of small eruptions over the past decade have had a small effect on global temperature trends. Some important outstanding research questions include: How much seasonal, annual, and decadal predictability is possible following a large volcanic eruption? Do

  15. Beginning and end of lunar mare volcanism

    International Nuclear Information System (INIS)

    Schultz, P.H.; Spudis, P.D.

    1983-01-01

    Having presented the inferred distribution and style of the early phases of mare volcanism, based on current evidence, it is suggested that certain regions of the Moon underwent two distinct pulses of igneous activity. Crater statistics for the post-Lichtenberg mare unit and other selected units are examined and it is concluded that mare volcanism extended to a time comparable with that of the Copernicus impact, or approximately 1 Myr BP. These reassessments of the oldest and youngest maria provide new constraints on geophysical models of the internal thermal history of the Moon. (U.K.)

  16. Atmospheric Despersal and Disposition of Tephra From a Potential Volcanic Eruption at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    G. Keating; W.Statham

    2004-01-01

    The purpose of this model report is to provide documentation of the conceptual and mathematical model (ASHPLUME) for atmospheric dispersal and subsequent deposition of ash on the land surface from a potential volcanic eruption at Yucca Mountain, Nevada. This report also documents the ash (tephra) redistribution conceptual model. The ASHPLUME conceptual model accounts for incorporation and entrainment of waste fuel particles associated with a hypothetical volcanic eruption through the Yucca Mountain repository and downwind transport of contaminated tephra. The ASHPLUME mathematical model describes the conceptual model in mathematical terms to allow for prediction of radioactive waste/ash deposition on the ground surface given that the hypothetical eruptive event occurs. This model report also describes the conceptual model for tephra redistribution from a basaltic cinder cone. Sensitivity analyses and model validation activities for the ash dispersal and redistribution models are also presented. Analyses documented in this model report will improve and clarify the previous documentation of the ASHPLUME mathematical model and its application to the Total System Performance Assessment (TSPA) for the License Application (TSPA-LA) igneous scenarios. This model report also documents the redistribution model product outputs based on analyses to support the conceptual model

  17. Atmospheric Dispersal and Dispostion of Tephra From a Potential Volcanic Eruption at Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    G. Keating; W.Statham

    2004-02-12

    The purpose of this model report is to provide documentation of the conceptual and mathematical model (ASHPLUME) for atmospheric dispersal and subsequent deposition of ash on the land surface from a potential volcanic eruption at Yucca Mountain, Nevada. This report also documents the ash (tephra) redistribution conceptual model. The ASHPLUME conceptual model accounts for incorporation and entrainment of waste fuel particles associated with a hypothetical volcanic eruption through the Yucca Mountain repository and downwind transport of contaminated tephra. The ASHPLUME mathematical model describes the conceptual model in mathematical terms to allow for prediction of radioactive waste/ash deposition on the ground surface given that the hypothetical eruptive event occurs. This model report also describes the conceptual model for tephra redistribution from a basaltic cinder cone. Sensitivity analyses and model validation activities for the ash dispersal and redistribution models are also presented. Analyses documented in this model report will improve and clarify the previous documentation of the ASHPLUME mathematical model and its application to the Total System Performance Assessment (TSPA) for the License Application (TSPA-LA) igneous scenarios. This model report also documents the redistribution model product outputs based on analyses to support the conceptual model.

  18. Morphostructure Control Towards the Development of Mahawu Volcanic Complex, North Sulawesi

    Directory of Open Access Journals (Sweden)

    S. Poedjoprajitno

    2014-06-01

    Full Text Available DOI: 10.17014/ijog.v7i1.134The studied area, situated in northeastern part of North Sulawesi Arm, is dominantly occupied by the Mahawu, Linau, Tompusu, and Kasurutan volcanic rocks. Using remote sensing data, such as landsat image, black and white panchromatic aerial photograph, and IFSAR image, morphology-origin unit and morphology lineament can be interpreted. Four morphology-origin units, those are Mahawu Volcano Complex, Intra-montane Plain structure, Linau Volcano Complex, and Lacustrine Plain are recognized. Furthermore, morphological lineament pattern was statistically processed to find out the general stress direction in the area to determine the probability of the structural morphology occurrence in the Mahawu Volcano Complex. The result shows that generally the development pattern of volcanic cones are irregular, except the Mahawu Volcano Complex showing a linear pattern. This lineament pattern is interpreted as a NW - SE fault pattern controlling the rise of magma. At least, two tectonic and two eruption periods occurred regularly at different time from the Quaternary age till the present.

  19. Volcanic Eruptions in the Southern Red Sea During 2007–2013

    KAUST Repository

    Jonsson, Sigurjon

    2015-04-03

    The first volcanic eruption known to occur in the southern Red Sea in over a century started on Jebel at Tair Island in September 2007. The early phase of the eruption was energetic, with lava reaching the shore of the small island within hours, destroying a Yemeni military outpost and causing a few casualties. The eruption lasted several months, producing a new summit cone and lava covering an area of 5.9 km2, which is about half the area of the island. The Jebel at Tair activity was followed by two more eruptions within the Zubair archipelago, about 50 km to the southeast, in 2011–2012 and 2013, both of which started on the seafloor and resulted in the formation of new islands. The first of these eruptions started in December 2011 in the northern part of the archipelago and lasted for about one month, generating a small (0.25 km2) oval-shaped island. Coastal erosion during the first two years following the end of the eruption has reduced the size of the island to 0.19 km2. The second event occurred in the central part of the Zubair Islands and lasted roughly two months (September–November, 2013), forming a larger (0.68 km2) island. The recent volcanic eruptions in the southern Red Sea are a part of increased activity seen in the entire southern Red Sea region following the onset of a rifting episode in Afar (Ethiopia) in 2005.

  20. Alexander von Humboldt’s ideas on volcanism and their influence on Russian scientists

    Directory of Open Access Journals (Sweden)

    Alexander Zemtsov

    2005-10-01

    Full Text Available Article in English, Abstract in English.The article provides historical background for Alexander von Humboldt’s expedition into Russia in 1829. It includes information on Humboldt’s works and publications in Russia over the course of his lifetime, as well as an explanation of the Russian scientific community’s response to those works. Humboldt’s ideas on the existence of an active volcano in Central Asia attracted the attention of two prominent Russian geographers, P. Semenov and P. Kropotkin, whose views on the nature of volcanism were quite different. P. Semenov personally met Humboldt in Berlin. P. Kropotkin made one of the most important geological discoveries of the 19th Century: he found the fresh volcanic cones near Lake Baikal.Soon after Humboldt’s Russian expedition, and partly as a result of it, an important mineral was found in the Ilmen mountains – samarskite, which later gave its name to the chemical element Samarium, developed in 1879. At the beginning of the 20th Century, the Russian scientist V. Vernadskiy pointed out that samarskite was the first uranium-rich mineral found in Russia.

  1. The Maars of the Tuxtla Volcanic Field: the Example of 'laguna Pizatal'

    Science.gov (United States)

    Espindola, J.; Zamora-Camacho, A.; Hernandez-Cardona, A.; Alvarez del Castillo, E.; Godinez, M.

    2013-12-01

    Los Tuxtlas Volcanic Field (TVF), also known as Los Tuxtlas massif, is a structure of volcanic rocks rising conspicuously in the south-central part of the coastal plains of eastern Mexico. The TVF seems related to the upper cretaceous magmatism of the NW part of the Gulf's margin (e.g. San Carlos and Sierra de Tamaulipas alkaline complexes) rather than to the nearby Mexican Volcanic Belt. The volcanism in this field began in late Miocene and has continued in historical times, The TVF is composed of 4 large volcanoes (San Martin Tuxtla, San Martin Pajapan, Santa Marta, Cerro El Vigia), at least 365 volcanic cones and 43 maars. In this poster we present the distribution of the maars, their size and depths. These maars span from a few hundred km to almost 1 km in average diameter, and a few meters to several tens of meters in depth; most of them filled with lakes. As an example on the nature of these structures we present our results of the ongoing study of 'Laguna Pizatal or Pisatal' (18° 33'N, 95° 16.4'W, 428 masl) located some 3 km from the village of Reforma, on the western side of San Martin Tuxtla volcano. Laguna Pisatal is a maar some 500 meters in radius and a depth about 40 meters from the surrounding ground level. It is covered by a lake 200 m2 in extent fed by a spring discharging on its western side. We examined a succession of 15 layers on the margins of the maar, these layers are blast deposits of different sizes interbedded by surge deposits. Most of the contacts between layers are irregular; which suggests scouring during deposition of the upper beds. This in turn suggests that the layers were deposited in a rapid series of explosions, which mixed juvenile material with fragments of the preexisting bedrock. We were unable to find the extent of these deposits since the surrounding areas are nowadays sugar cane plantations and the lake has overspilled in several occassions.

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

    Science.gov (United States)

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

    2010-12-01

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

  3. Post-rift volcanic structures of the Pernambuco Plateau, northeastern Brazil

    Science.gov (United States)

    Buarque, Bruno V.; Barbosa, José A.; Magalhães, José R. G.; Cruz Oliveira, Jefferson T.; Filho, Osvaldo J. Correia

    2016-10-01

    The Pernambuco marginal basin is located on the eastern continental margin of northeastern Brazil, covers an area of 20,800 km2, and represents one of the most prominent frontiers for deep water oil and gas exploration off the Brazilian coast. The onshore region of this basin was highly affected by extrusive and intrusive magmatism during the Upper Albian, and the relation of that event with the volcanic structures observed in the offshore sector has not been thoroughly characterized to date. This study aims to characterize the major extrusive and intrusive volcanic structures of the offshore portion of this basin, which is dominated by the Pernambuco Plateau, and its stratigraphic relations. A set of 143 2D multichannel seismic sections that cover the Pernambuco Plateau region are used to interpret the major tectono-stratigraphic sequences and describe the distribution of volcanoes, sills, vent complexes and related volcaniclastic sequences. The interpretations are supported by aeromagnetic and gravimetric geophysical surveys. Volcanoes are classified into two groups that differ in terms of their morphology: shield-like structures and cone-shaped volcanic structures. Sill intrusions are mainly identified beneath the volcanic structures and are characterized by high-amplitude reflectors with short extensions and abrupt terminations. Volcaniclastic sequences are found adjacent to the volcanoes and are characterized by high-amplitude, disrupted reflections with local chaotic configurations. Vent complexes are classified on the basis of their morphologies as either eye-shaped or crater-shaped. The volcanic features identified within the available seismic dataset are concentrated in two main areas: in the centre of the plateau and near its northeastern border. These two regions are host basement outer highs and are surrounded by hyper-extended continental crust, which forms the plateau itself. The extrusive and intrusive features described in the offshore region were

  4. Integrity of the cone photoreceptor mosaic in oligocone trichromacy

    DEFF Research Database (Denmark)

    Michaelides, Michel; Rha, Jungtae; Dees, Elise W

    2011-01-01

    Oligocone trichromacy (OT) is an unusual cone dysfunction syndrome characterized by reduced visual acuity, mild photophobia, reduced amplitude of the cone electroretinogram with normal rod responses, normal fundus appearance, and normal or near-normal color vision. It has been proposed that these...

  5. Advances in Valveless Piezoelectric Pump with Cone-shaped Tubes

    Science.gov (United States)

    Zhang, Jian-Hui; Wang, Ying; Huang, Jun

    2017-07-01

    This paper reviews the development of valveless piezoelectric pump with cone-shaped tube chronologically, which have widely potential application in biomedicine and micro-electro-mechanical systems because of its novel principles and deduces the research direction in the future. Firstly, the history of valveless piezoelectric pumps with cone-shaped tubes is reviewed and these pumps are classified into the following types: single pump with solid structure or plane structure, and combined pump with parallel structure or series structure. Furthermore, the function of each type of cone-shaped tubes and pump structures are analyzed, and new directions of potential expansion of valveless piezoelectric pumps with cone-shaped tubes are summarized and deduced. The historical argument, which is provided by the literatures, that for a valveless piezoelectric pump with cone-shaped tubes, cone angle determines the flow resistance and the flow resistance determines the flow direction. The argument is discussed in the reviewed pumps one by one, and proved to be convincing. Finally, it is deduced that bionics is pivotal in the development of valveless piezoelectric pump with cone-shaped tubes from the perspective of evolution of biological structure. This paper summarizes the current valveless piezoelectric pumps with cone-shaped tubes and points out the future development, which may provide guidance for the research of piezoelectric actuators.

  6. Scoria Cone Construction Mechanism, Lathrop Wells Volcano, Southern Nevada

    Energy Technology Data Exchange (ETDEWEB)

    G. Valentine; D. Krier; F. Perry; G. Heiken

    2005-01-18

    Scoria cones are commonly assumed to have been constructed by the accumulation of ballistically-ejected clasts from discrete and relatively coarse-grained Strombolian bursts and subsequent avalanching such that the cone slopes are at or near the angle of repose for loose scoria. The cone at the hawaiitic Lathrop Wells volcano, southern Nevada, contains deposits that are consistent with the above processes during early cone-building phases; these early deposits are composed mainly of coarse lapilli and fluidal bombs and are partially welded, indicating relatively little cooling during flight. However, the bulk of the cone is comprised of relatively fine-grained (ash and lapilli), planar beds with no welding, even within a few tens of meters of the vent. This facies is consistent with deposition by direct fallout from sustained eruption columns of relatively well-fragmented material, primarily mantling cone slopes and with a lesser degree of avalanching than is commonly assumed. A laterally extensive fallout deposit (up to 20 km from the vent) is inferred to have formed contemporaneously with these later cone deposits. This additional mechanism for construction of scoria cones may also be important at other locations, particularly where the magmas are relatively high in volatile content and where conditions promote the formation of abundant microlites in the rising mafic magma.

  7. Gene therapy rescues cone function in congenital achromatopsia.

    Science.gov (United States)

    Komáromy, András M; Alexander, John J; Rowlan, Jessica S; Garcia, Monique M; Chiodo, Vince A; Kaya, Asli; Tanaka, Jacqueline C; Acland, Gregory M; Hauswirth, William W; Aguirre, Gustavo D

    2010-07-01

    The successful restoration of visual function with recombinant adeno-associated virus (rAAV)-mediated gene replacement therapy in animals and humans with an inherited disease of the retinal pigment epithelium has ushered in a new era of retinal therapeutics. For many retinal disorders, however, targeting of therapeutic vectors to mutant rods and/or cones will be required. In this study, the primary cone photoreceptor disorder achromatopsia served as the ideal translational model to develop gene therapy directed to cone photoreceptors. We demonstrate that rAAV-mediated gene replacement therapy with different forms of the human red cone opsin promoter led to the restoration of cone function and day vision in two canine models of CNGB3 achromatopsia, a neuronal channelopathy that is the most common form of achromatopsia in man. The robustness and stability of the observed treatment effect was mutation independent, but promoter and age dependent. Subretinal administration of rAAV5-hCNGB3 with a long version of the red cone opsin promoter in younger animals led to a stable therapeutic effect for at least 33 months. Our results hold promise for future clinical trials of cone-directed gene therapy in achromatopsia and other cone-specific disorders.

  8. Insectos de cones y semillas de las coniferas de Mexico

    Science.gov (United States)

    David Cibrián-Tovar; Bernard H. Ebel; Harry O. Yates; José Tulio Mhdez-Montiel

    1986-01-01

    The hosts, description, damage, life cycle, habits, and importance of 54 known cone and seed destroying insects attacking Mexican conifer trees are discussed. Distribution maps and color photos are provided. New species described are three species of Cydia (seedworm), four species of Dioryctria (coneworm), and four species of cone...

  9. Polynomial Primal-Dual Cone Affine Scaling for Semidefinite Programming

    NARCIS (Netherlands)

    A.B. Berkelaar (Arjan); J.F. Sturm; S. Zhang (Shuzhong)

    1996-01-01

    textabstractIn this paper we generalize the primal--dual cone affine scaling algorithm of Sturm and Zhang to semidefinite programming. We show in this paper that the underlying ideas of the cone affine scaling algorithm can be naturely applied to semidefinite programming, resulting in a new

  10. Scatter corrections for cone beam optical CT

    Energy Technology Data Exchange (ETDEWEB)

    Olding, Tim; Holmes, Oliver [Department of Physics, Queen' s University (United Kingdom); Schreiner, L John [Medical Physics Department, Cancer Centre of Southeastern Ontario (Canada)], E-mail: Tim.Olding@krcc.on.ca

    2009-05-01

    Cone beam optical computed tomography (OptCT) employing the VISTA scanner (Modus Medical, London, ON) has been shown to have significant promise for fast, three dimensional imaging of polymer gel dosimeters. One distinct challenge with this approach arises from the combination of the cone beam geometry, a diffuse light source, and the scattering polymer gel media, which all contribute scatter signal that perturbs the accuracy of the scanner. Beam stop array (BSA), beam pass array (BPA) and anti-scatter polarizer correction methodologies have been employed to remove scatter signal from OptCT data. These approaches are investigated through the use of well-characterized phantom scattering solutions and irradiated polymer gel dosimeters. BSA corrected scatter solutions show good agreement in attenuation coefficient with the optically absorbing dye solutions, with considerable reduction of scatter-induced cupping artifact at high scattering concentrations. The application of BSA scatter corrections to a polymer gel dosimeter lead to an overall improvement in the number of pixel satisfying the (3%, 3mm) gamma value criteria from 7.8% to 0.15%.

  11. Optical coherence tomography in progressive cone dystrophy.

    Science.gov (United States)

    Zahlava, Jiri; Lestak, Jan; Karel, Ivan

    2014-12-01

    The aim of the study was to analyse different clinical pictures in patients with progressive cone dystrophy (PCD), to compare these with the results of optical coherence tomography (OCT) and to evaluate the benefits of this method for diagnosis. The group consisted of 16 patients (32 eyes) with PCD. All patients were examined for visual acuity, colour sense and visual field. We performed biomicroscopic examination, photo-documentation, fluorescein angiography, electrophysiological tests and OCT. Using biomicroscopy and fluorescein angiography, we found changes in the retinal pigment epithelium ranging from barely detectable changes up to the typical bull's eye appearance. In all the eyes, OCT established statistically significant reduction in the thickness and structural changes in the neuroretina of the macula. Atrophy was evident especially in the outer nuclear layer, in the photoreceptor inner segment/outer segment junction and in the retinal pigment epithelium. Visual acuity was mainly dependent on the degree to which the continuity of the photoreceptor inner segment/outer segment junction layer was maintained. Eyes with better preserved neuroretinal structure in the fovea centralis had generally less reduced thickness of the retina and a better visual acuity. OCT specifies the quantitative and qualitative changes in the macula and may contribute significantly to the diagnosis of the progressive cone dystrophy, particularly in the early stages of the disease which is difficult to diagnose.

  12. O grande manancial do Cone Sul

    Directory of Open Access Journals (Sweden)

    Gerôncio Albuquerque Rocha

    1997-08-01

    Full Text Available O Cone Sul abriga um manancial de águas subterrâneas de extensão continental, denominado Aqüífero Guarani, cujo volume de água doce disponível é suficiente para abastecer permanentemente os 15 milhões de habitantes de sua região de ocorrência. Neste trabalho é feita uma descrição sumária do reservatório. São estabelecidas bases para o aproveitamento dos recursos hídricos e propostos mecanismos e arranjos institucionais, em âmbito internacional, com vistas a iniciar um processo participativo de gestão do manancial.The South Cone bears a groundwater source of continental extent called Guarani Aquifer, in which the volume of freshwater available is sufficient to supply the 15 million inhabitants of the region. The present paper gives a briefing on this reservoir, establishes the basis for the good use of the water resources, as well as proposes institutional means and arrangements at international level with a view to initiating a joint process to manage the source.

  13. Electrical charging of ash in Icelandic volcanic plumes

    OpenAIRE

    Aplin, Karen L; Houghton, Isobel M P; Nicoll, Keri A

    2014-01-01

    The existence of volcanic lightning and alteration of the atmospheric potential gradient in the vicinity of near-vent volcanic plumes provides strong evidence for the charging of volcanic ash. More subtle electrical effects are also visible in balloon soundings of distal volcanic plumes. Near the vent, some proposed charging mechanisms are fractoemission, triboelectrification, and the so-called "dirty thunderstorm" mechanism, which is where ash and convective clouds interact electrically to e...

  14. Cones in the Euclidean space with vanishing scalar curvature

    Directory of Open Access Journals (Sweden)

    João Lucas M. Barbosa

    2004-12-01

    Full Text Available Given a hypersurface M on a unit sphere of the Euclidean space, we define the cone based on M as the set of half-lines issuing from the origin and passing through M. By assuming that the scalar curvature of the cone vanishes, we obtain conditions under which bounded domains of such cone are stable or unstable.Dada uma hipersuperfície M de uma esfera unitária do espaço euclidiano, definimos o cone sobre M como o conjunto das semi-retas que saem da origem e passam por M. Admitindo que a curvatura escalar de um dado cone é nula, estabelecemos condições para que os seus domínios limitados sejam estáveis ou instáveis.

  15. Unsupervised learning of cone spectral classes from natural images.

    Science.gov (United States)

    Benson, Noah C; Manning, Jeremy R; Brainard, David H

    2014-06-01

    The first step in the evolution of primate trichromatic color vision was the expression of a third cone class not present in ancestral mammals. This observation motivates a fundamental question about the evolution of any sensory system: how is it possible to detect and exploit the presence of a novel sensory class? We explore this question in the context of primate color vision. We present an unsupervised learning algorithm capable of both detecting the number of spectral cone classes in a retinal mosaic and learning the class of each cone using the inter-cone correlations obtained in response to natural image input. The algorithm's ability to classify cones is in broad agreement with experimental evidence about functional color vision for a wide range of mosaic parameters, including those characterizing dichromacy, typical trichromacy, anomalous trichromacy, and possible tetrachromacy.

  16. Unsupervised learning of cone spectral classes from natural images.

    Directory of Open Access Journals (Sweden)

    Noah C Benson

    2014-06-01

    Full Text Available The first step in the evolution of primate trichromatic color vision was the expression of a third cone class not present in ancestral mammals. This observation motivates a fundamental question about the evolution of any sensory system: how is it possible to detect and exploit the presence of a novel sensory class? We explore this question in the context of primate color vision. We present an unsupervised learning algorithm capable of both detecting the number of spectral cone classes in a retinal mosaic and learning the class of each cone using the inter-cone correlations obtained in response to natural image input. The algorithm's ability to classify cones is in broad agreement with experimental evidence about functional color vision for a wide range of mosaic parameters, including those characterizing dichromacy, typical trichromacy, anomalous trichromacy, and possible tetrachromacy.

  17. A free boundary problem on three-dimensional cones

    Science.gov (United States)

    Allen, Mark

    2017-12-01

    We consider a free boundary problem on cones depending on a parameter c and study when the free boundary is allowed to pass through the vertex of the cone. We show that when the cone is three-dimensional and c is large enough, the free boundary avoids the vertex. We also show that when c is small enough but still positive, the free boundary is allowed to pass through the vertex. This establishes 3 as the critical dimension for which the free boundary may pass through the vertex of a right circular cone. In view of the well-known connection between area-minimizing surfaces and the free boundary problem under consideration, our result is analogous to a result of Morgan that classifies when an area-minimizing surface on a cone passes through the vertex.

  18. Geochemistry of middle Tertiary volcanic rocks in the northern Aquarius Mountains, west-central Arizona

    Energy Technology Data Exchange (ETDEWEB)

    Simmons, A.M.; Haxel, G.B.

    1993-04-01

    The northern Aquarius Mountains volcanic field ([approximately]50km east of Kingman) covers an area of 400 km[sup 2], bounded by upper Trout Creek (S), the Truxton Valley (N), the Big Sandy Valley (W), and Cross Mountain (E). The volcanic sequence rests upon a pre-middle Eocene erosional surface. The lowest units is a 250 m-thick unit of rhyolitic pyroclastic breccias and airfall tuffs. Successively younger units are: basanite flows and cinder cones; hornblende latite flows and domes; porphyritic dacite flows, domes, and breccias; alkali basalt intrusions; and low-silica rhyolite domes and small high=silica rhyolite flows. Dacite is volumetrically dominant, and erupted primarily from vents in and around Cedar Basin (Penitentiary Mtn 7.5[prime] quad.). Other geologists have obtained K-Ar dates [approximately]24--20 Ma for the basanites and latites. The alkali basalts, latites, dacites, and rhyolites evidently constitute a genetically-related high-K to shoshonitic calcalkaline suite with chemistry typical of subduction-related magmatism: enrichment in LILE and LREE, and depletion of Nb and Ta relative to K and La and of Ti relative to Hf and Yb. Each rock type is unique and distinguishable in K/Rb and Rb/Sr. The basanites are primitive (mg=0.75--0.78), have intraplate affinities (La/Nb[<=]1), and show consistent and distinctive depletion of K relative to the other LILE. The presence of these basanites in an early Miocene volcanic sequence is unusual or unexpected, as they predate (by [approximately]10 m.y.) the regional eruption of asthenosphere-derived basalts associated with Basin-and-Range extension.

  19. Evaluation of Risk from Volcanic Ashfalls at the Los Tuxtlas Region, Veracruz, Mexico

    Science.gov (United States)

    Espindola, J. M.; Godinez, M. L.; Zamora-Camacho, A.

    2014-12-01

    The Los Tuxtlas region is an area in the eastern Mexican State of Veracruz, located over the Tuxtla volcanic field and surroundings. This field is composed of 353 distinct cones, 4 large composite volcanoes, and 42 maars. Eruptive activity in the TVF began in the late Miocene, underwent a quiescent period approximately 2.6-0.8 Ma, and continues into historic times with the most recent eruptions occurring at San Martín Tuxtla volcano in 1640 and 1793. Due to the historical occurrence of these eruptions, the volcano is considered hazardous. Although no casualties were derived from those eruptions, the population in the area has grown at a fast pace and a similar eruption occurring today would cause enormous social problems. According to INEGI, the country's organism in charge of demographic studies, there are some 200,000 people settled 20 km around the volcano. Furthermore, since the volcanic field is basaltic, the magma's transfer time from depth to surface is short, and volcanic eruptions such as that of 1793 occur without much warning time. These aspects point out to the need for an estimation of the effects of a similar eruption in our days. Espindola et al. (2010; JVGR, 197, 188-208) estimated the isopachs of the ash deposited during that eruption of 1793; we used these isopachs to the 1 cm contour to evaluate some of those effects. The 1 cm isopach spans an area of 541 km2 of which 385 km2 is grazing lands and plantations, more than 149 km2 are covered by dense vegetation and 5 km2 are occupied by settlements of various sizes. There are about 34 km of paved roads that are also the main communication access to the southern State of Veracruz. These figures are a basis for the estimation of the cost of the assistance to the region in case of an eruption and the elaboration of plan of contingency in case of eruption.

  20. On the climatic implications of volcanic cooling

    Science.gov (United States)

    Lindzen, Richard S.; Giannitsis, Constantine

    1998-03-01

    A simple energy balance model is used to investigate the response to a volcanic-type radiative forcing under different assumptions about the climatic sensitivity of the system. Volcanic eruptions are used as control experiments to investigate the role of the ocean-atmosphere coupling and of diffusive heat uptake by the thermocline. The effect of varying equilibrium climate sensitivity by varying the coupling of the atmosphere and ocean is examined, high sensitivity being associated with weak coupling. A model representing a coupled land-ocean system, with a reasonably realistic representation of the large-scale physics is used. It is found that systems with large equilibrium sensitivities not only respond somewhat more strongly to radiative perturbations but also return to equilibrium with much longer timescales. Based on this behavior pattern, we examine the model response to a series of volcanic eruptions following Krakatoa in 1883. Comparison between the model results and past temperature records seems to suggest that use of small sensitivity parameters is more appropriate. Despite the uncertainties associated with both the physics and the quantitative characteristics of the radiative forcing and the temperature anomalies produced by volcanic eruptions, the present study constitutes a possible test of different assumptions about the sensitivity of the climate system.

  1. Volcanic sunset-glow stratum: origin.

    Science.gov (United States)

    Meinel, A B; Meinel, M P

    1967-01-13

    Reexamination of the phenomenon of volcanic-dust sunsets, as typified by the Krakatoa event, supports a theory that the scattering layer is produced by the interaction of ozone and sulfur dioxide in much the same manner as is the normal "Junge"aerosol layer at 20 kilometers.

  2. A case study from Wadi Natash volcanic

    Indian Academy of Sciences (India)

    This paper aims at revealing the spectral characteristics of the olivine basalts exposed at Wadi Natash area, Egypt, using FieldSpec spectroradiometer. It also evaluates band ratios and fusion techniques for mapping purposes using ASTER data. Several volcanic episodes occurred during Early- to Late-Cretaceous are ...

  3. Monitoring and forecasting Etna volcanic plumes

    Directory of Open Access Journals (Sweden)

    S. Scollo

    2009-09-01

    Full Text Available In this paper we describe the results of a project ongoing at the Istituto Nazionale di Geofisica e Vulcanologia (INGV. The objective is to develop and implement a system for monitoring and forecasting volcanic plumes of Etna. Monitoring is based at present by multispectral infrared measurements from the Spin Enhanced Visible and Infrared Imager on board the Meteosat Second Generation geosynchronous satellite, visual and thermal cameras, and three radar disdrometers able to detect ash dispersal and fallout. Forecasting is performed by using automatic procedures for: i downloading weather forecast data from meteorological mesoscale models; ii running models of tephra dispersal, iii plotting hazard maps of volcanic ash dispersal and deposition for certain scenarios and, iv publishing the results on a web-site dedicated to the Italian Civil Protection. Simulations are based on eruptive scenarios obtained by analysing field data collected after the end of recent Etna eruptions. Forecasting is, hence, supported by plume observations carried out by the monitoring system. The system was tested on some explosive events occurred during 2006 and 2007 successfully. The potentiality use of monitoring and forecasting Etna volcanic plumes, in a way to prevent threats to aviation from volcanic ash, is finally discussed.

  4. Payenia volcanic province, southern Mendoza, Argentina

    DEFF Research Database (Denmark)

    Søager, Nina; Holm, Paul Martin; Llambias, Eduardo Jorge

    2013-01-01

    The Pleistocene to Holocene Payenia volcanic province is a backarc region of 60,000 km2 in Mendoza, Argentina, which is dominated by transitional to alkaline basalts and trachybasalts. We present major and trace element compositions of 139 rocks from this area of which the majority are basaltic r...

  5. The Elusive Evidence of Volcanic Lightning.

    Science.gov (United States)

    Genareau, K; Gharghabi, P; Gafford, J; Mazzola, M

    2017-11-14

    Lightning strikes are known to morphologically alter and chemically reduce geologic formations and deposits, forming fulgurites. A similar process occurs as the result of volcanic lightning discharge, when airborne volcanic ash is transformed into lightning-induced volcanic spherules (LIVS). Here, we adapt the calculations used in previous studies of lightning-induced damage to infrastructure materials to determine the effects on pseudo-ash samples of simplified composition. Using laboratory high-current impulse experiments, this research shows that within the lightning discharge channel there is an ideal melting zone that represents roughly 10% or less of the total channel radius at which temperatures are sufficient to melt the ash, regardless of peak current. The melted ash is simultaneously expelled from the channel by the heated, expanding air, permitting particles to cool during atmospheric transport before coming to rest in ash fall deposits. The limited size of this ideal melting zone explains the low number of LIVS typically observed in volcanic ash despite the frequent occurrence of lightning during explosive eruptions.

  6. Geochemistry and petrogenesis of anorogenic basic volcanic ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    anorogenic setting for the basic rocks of Kundal area is suggested, which is in conformity with the similar setting for Malani Igneous Suite. 1. Introduction. The Malani magmatism is characterized by sub- volcanic setting, volcano-plutonic ring structures, anorogenic (A-type), high heat producing magma- tism and controlled by ...

  7. A great volcanic eruption around AD 1300 recorded in lacustrine ...

    Indian Academy of Sciences (India)

    The Sr and Nd isotope compositions at 61 cm are in excellent agreement with those in volcanic materials, but they are significantly different from those in terrigenous dust, implying a possible material input from historical volcanic eruptions in the lacustrine sediment. DY6. The documented great Samalas volcanic eruption at ...

  8. Compositional Differences between Felsic Volcanic rocks from the ...

    African Journals Online (AJOL)

    Pliocene felsic rift margin and Quaternary rift center volcanic rocks from the northern Main Ethiopian Rift (MER) exhibit contrasts in major and trace element contents and Sr-Nd isotopic ratios. Quaternary rift center felsic volcanic rocks are mainly peralkaline trachytes and rhyolites, whereas Pliocene felsic rift margin volcanic ...

  9. Réunion (Indian Ocean) Oceanic Island Volcanism: Seismic Structure and Heterogeneity of the Upper Lithosphere

    Science.gov (United States)

    Hirn, A.

    2002-12-01

    Réunion island in the Indian Ocean is commonly considered as the recent and active expression of the hotspot that formed the Deccan traps, although both the hypothesis of recent small hotspots for both Reunion and Mauritius, or of relation with the plate heterogeneity have been proposed. Structural studies by seismic methods, from the scale of the upper cone of the active Fournaise volcano to that of the crust 100 km around, have been carried out. At this scale significant departures appear from the Hawaiian case to which it is traditionally compared, with the seismic signature of active volcanism showing differences too. Refraction-reflection seismics do not see a geometry of the top of the underlying plate towards the island, expected in plate flexure modelling by analogy with other hotspot island. Where it is sampled, doming is suggested instead. There appears to be less magmatic products than if there was a large amount buried in a flexural depression. The velocity structure resolved for the volcanic island, apart from high velocity cores under the volcanoes leads to smaller overall density than usually considered in flexure modelling. The same appears to hold for the material of the cone of about 120 km radius rising above the regional sea-bottom level to the 30 km radius island, from coincident reflection and refraction seismics on several lines radial to the southeastern half of the island. At the crust-mantle level, there is evidence from reflection-refraction line extending 150 km either side of the island for a layer of velocity intermediate between normal crust and mantle values. Two radial reflection line to the SSW, close to each other detect a differences in depth of the oceanic basement. This may coincide with a fracture zone suggested from the reconstruction of the sea-floor spreading history from the magnetic anomaly pattern. The latter has been interpreted previously to indicate that the western part of Réunion developed atop a Paleogene fossil

  10. Microphysical Properties of Alaskan Volcanic Ash

    Science.gov (United States)

    Puthukkudy, A.; Espinosa, R.; Rocha Lima, A.; Remer, L.; Colarco, P. R.; Whelley, P.; Krotkov, N. A.; Young, K.; Dubovik, O.; Wallace, K.; Martins, J. V.

    2017-12-01

    Volcanic ash has the potential to cause a variety of severe problems for human health and the environment. Therefore, effective monitoring of the dispersion and fallout from volcanic ash clouds and characterization of the aerosol particle properties are essential. One way to acquire information from volcanic clouds is through satellite remote sensing: such images have greater coverage than ground-based observations and can present a "big picture" perspective. A challenge of remote sensing is that assumptions of certain properties of the target are often a pre-requisite for making accurate and quantitative retrievals. For example, detailed information about size distribution, sphericity, and optical properties of the constituent matter is needed or must be assumed. The same kind of information is also needed for atmospheric transport models to properly simulate the dispersion and fallout of volcanic ash. Presented here is a laboratory method to determine the microphysical and optical properties of volcanic ash samples collected from two Alaskan volcanoes with markedly different compositions. Our method uses a Polarized Imaging Nephelometer (PI-Neph) and a system that re-suspends the particles in an air flow. The PI-Neph measures angular light scattering and polarization of the re-suspended particles from 3o to 175o in scattering angle, with an angular resolution of 1o . Primary measurements include phase function and polarized phase function at three wavelengths (445nm, 532nm, and 661nm). Size distribution, sphericity, and complex refractive index are retrieved indirectly from the PI-Neph measurements using the GRASP (Generalized Retrieval of Aerosol and Surface Properties) inversion algorithm. We report the results of this method applied to samples from the Mt. Okmok (2008) and Mt. Katmai (1912) volcanic eruptions. To our knowledge, this is the first time direct measurements of phase matrix elements of ash from Mt. Okmok and Mt. Katmai have been reported. Retrieved

  11. Sources of Quaternary volcanism in the Itasy and Ankaratra volcanic fields, Madagascar

    Science.gov (United States)

    Rasoazanamparany, C.; Widom, E.; Kuentz, D. C.; Raharimahefa, T.; Rakotondrazafy, F. M. A.; Rakotondravelo, K. M.

    2017-12-01

    We present new major and trace element and Sr, Nd, Pb and Os isotope data for Quaternary basaltic lavas and tephra from the Itasy and Ankaratra volcanic fields, representing the most recent volcanism in Madagascar. Mafic magmas from Itasy and Ankaratra exhibit significant inter- and intra-volcanic field geochemical heterogeneity. The Itasy eruptive products range in composition from foidite to phonotephrite whereas Ankaratra lavas range from basanite to trachybasalts. Trace element signatures of samples from both volcanic fields are very similar to those of ocean island basalts (OIB), with significant enrichment in Nb and Ta, depletion in Rb, Cs, and K, and relatively high Nb/U and Ce/Pb. However, the Itasy volcanic rocks show enrichment relative to those of Ankaratra in most incompatible elements, indicative of a more enriched source and/or lower degrees of partial melting. Significant inter- and intra-volcanic field heterogeneity is also observed in Sr, Nd, Pb and Os isotope signatures. The Itasy volcanic rocks generally have less radiogenic Sr and Nd isotopic ratios but more radiogenic Pb isotopic signatures than the Ankaratra volcanic field. Together, the Itasy and Ankaratra volcanic rocks form a well-defined negative correlation in Sr vs. Pb isotopes that could be attributed to lithospheric contamination or variable degrees of mixing between distinct mantle sources. However, the lack of correlation between isotopes and indices of crustal contamination (e.g. MgO and Nb/U) are inconsistent with shallow lithospheric contamination, and instead suggest mixing between compositionally distinct mantle sources. Furthermore, although Sr-Pb isotope systematics are apparently consistent with mixing between two different sources, distinct trends in Sr vs. Nd isotopes displayed by samples from Itasy and Ankaratra, respectively, argue for more complex source mixing involving three or more sources. The current data demonstrate that although the Itasy and Ankaratra volcanic

  12. Formation of shatter cones in MEMIN impact experiments

    Science.gov (United States)

    Wilk, J.; Kenkmann, T.

    2016-08-01

    Shatter cones are the only macroscopic feature considered as evidence for shock metamorphism. Their presence is diagnostic for the discovery and verification of impact structures. The occurrence of shatter cones is heterogeneous throughout the crater record and their geometry can diverge from the typical cone shape. The precise formation mechanism of shatter cones is still not resolved. In this study, we aim at better constraining the boundary conditions of shatter cone formation in impact experiments and test a novel approach to qualitatively and quantitatively describe shatter cone geometries by white light interferometry. We recovered several ejected fragments from MEMIN cratering experiments that show slightly curved, striated surfaces and conical geometries with apices of 36°-52°. These fragments fulfilling the morphological criteria of shatter cones were found in experiments with 20-80 cm sized target cubes of sandstone, quartzite and limestone, but not in highly porous tuff. Targets were impacted by aluminum, steel, and iron meteorite projectiles at velocities of 4.6-7.8 km s-1. The projectile sizes ranged from 2.5-12 mm in diameter and produced experimental peak pressures of up to 86 GPa. In experiments with lower impact velocities shatter cones could not be found. A thorough morphometric analysis of the experimentally generated shatter cones was made with 3D white light interferometry scans at micrometer accuracy. SEM analysis of the surfaces of recovered fragments showed vesicular melt films alternating with smoothly polished surfaces. We hypothesize that the vesicular melt films predominantly form at strain releasing steps and suggest that shatter cones are probably mixed mode fractures.

  13. Seed cone anatomy of Cheirolepidiaceae (Coniferales): reinterpreting Pararaucaria patagonica Wieland.

    Science.gov (United States)

    Escapa, Ignacio H; Rothwell, Gar W; Stockey, Ruth A; Cúneo, N Rubén

    2012-06-01

    Seed cone morphology and anatomy reflect some of the most important changes in the phylogeny and evolutionary biology of conifers. Reexamination of the enigmatic Jurassic seed cone Pararaucaria patagonica reveals previously unknown systematically informative characters that demonstrate affinities with the Cheirolepidiaceae. This paper documents, for the first time, internal anatomy for seed cones of this important extinct Mesozoic conifer family, which may represent the ghost lineage leading to modern Pinaceae. Morphology and anatomy of cones from the Jurassic La Matilde Formation in Patagonia are described from a combination of polished wafers and thin section preparations. New photographic techniques are employed to reveal histological details of thin sections in which organic cell wall remains are not preserved. Specific terminology for conifer seed cones is proposed to help clarify hypotheses of homology for the various structures of the cones. Specimens are demonstrated to have trilobed ovuliferous scale tips along with a seed enclosing pocket of ovuliferous scale tissue. Originally thought to represent a seed wing in P. patagonica, this pocket-forming tissue is comparable to the flap of tissue covering seeds of compressed cheirolepidiaceous cones and is probably the most diagnostic character for seed cones of the family. Pararaucaria patagonica is assigned to Cheirolepidiaceae, documenting anatomical features for seed cones of the family and providing evidence for the antiquity of pinoid conifers leading to the origin of Pinaceae. A list of key morphological and anatomical characters for seed cones of Cheirolepidiaceae is developed to facilitate assignment of a much broader range of fossil remains to the family. This confirms the presence of Cheirolepidiaceae in the Jurassic of the Southern Hemisphere, which was previously suspected from palynological records.

  14. How `Monogenetic' is the Auckland Volcanic Field?

    Science.gov (United States)

    Spargo, S. R.; Smith, I. E.; Wilson, C. J.

    2007-05-01

    The Auckland Field is the youngest basaltic intraplate volcanic field in New Zealand; it is located about 350-400 km behind the present day active convergent plate boundary. The field contains about 50 recognised late Pleistocene to Holocene eruptive centres generated by the rise and eruption of very small volume (mainly less than 0.35 km3) batches of magma. The field covers approximately 100 km2 of the Auckland urban area and has been termed monogenetic, implying that individual centres erupt single magma batches during brief eruptive periods. Detailed studies of individual centres reveal significant compositional diversity. The following trends are recognised: 1). Single trends from early evolved to later less evolved compositions representing deep near source fractionation of a single magma batch generated in the garnet peridotite stability field (e.g. Crater Hill about 29 ka, 0.1 km3), this is demonstrably monogenetic behaviour. 2). Multiple compositional trends in magmas from a single eruption event signifying the sequential rise and fractionation of magma batches generated from different sources (3-8 percent melt of a garnet peridotite source at depths of about 80-50 km and 5-12 percent melt of spinel peridotite at depths about 50- 22km), for example Pupuke (about 250 ka, 0.1 km3) this is polygenetic behaviour. 3). Multiple compositional trends in temporarily discrete eruption events from the same centre (Rangitoto, 8 to 700 a, 2.3 km3) this is also polygenetic behaviour. The chemical diversity observed within these three volcanic centres, representing the life span of the Auckland Volcanic Field, questions how well we actually understand this very common type of global volcanism. The range of compositions observed in individual centres of the Auckland Volcanic Field reflects the interplay of melting and fractionation processes at different depths in the mantle and calls into question the use of the term monogenetic to describe them.

  15. Petrography and petrology of Quaternary volcanic rocks from Ghezel Ghaleh, northwest Qorveh

    Directory of Open Access Journals (Sweden)

    Alireza Bajelan

    2014-10-01

    Full Text Available Introduction In the east and northeast of Sanandaj in the Qorveh-Bijar-Takab axis, there are series of basaltic composition volcanoes with Quaternary age. The study area is part of the Sanandaj-Sirjan zone and is located between 47°52' and 47°57' E longitudes and 35°26 and '35°30' N latitudes. Due to the location of the volcanic cone on Pliocene clastic sediments and Quaternary travertine, the age of these volcanoes is considered to be Quaternary. The cones mostly consist of low scoria, ash, volcanic bombs, lapilli deposits and basaltic lava (Moein Vaziri and Aminsobhani, 1985. Petrological and geochemical studies have been carried out to evaluate Quaternary magmatism in the area and to determine the nature of the lithological characteristics, such as the evaluation of source rocks and magma type, degree of partial melting and the tectonic setting of Ghezel Ghaleh rocks (Moein Vaziri, 1997. Simplified geological map of the study area is characterized by ER-Mapper software. Materials and methods In the course of field studies in the region, 40 samples were taken, 30 thin sections were prepared and polished. XRD analyses were performed on some whole rock samples. All major, minor and trace elements were assessed by ICP-MS at Lab Weft Laboratory in Australia. Results Based on the classification of structural zones, the area is located in the Sanandaj-Sirjan zone, hundred kilometers away from the main Zagros thrust along the NW-SE direction. After early Cimmerian orogeny, andesitic volcanic activity took place (Moein Vaziri and Aminsobhani, 1985. A major secondary mineral in these rocks is iddingsite, formed by hydration and oxidation of the olivine (Shelley, 1993. According to SiO2 against Na2O + K2O (TAS diagram (Irvine and Baragar , 1971 and cationic R1 and R2 diagram (De La Roche et el., 1980, volcanic rocks of the area indicate alkaline series. Discussion To obtain more information on the tectonic setting of these rocks, the Zr/Y-Zr diagram

  16. Variability of silver fir (Abies alba Mill.) cones – variability of cone parameters

    OpenAIRE

    Aniszewska, Monika; Błuszkowska, Urszula

    2016-01-01

    This study aimed at determining the shape of closed silver fir cones from the Jawor Forest District (Wroclaw), based purely on measurements of their length and thickness. Using these two parameters, the most accurate estimations were achieved with a fourth-degree polynomial fitting function. We then calculated the cones’ surface area and volume in three different ways: 1) Using the fourth-degree polynomial shape estimation, 2) Introducing indicators of compliance (k1, k2, k3) to calculate the...

  17. Cone beam computed tomography in endodontic

    Energy Technology Data Exchange (ETDEWEB)

    Durack, Conor; Patel, Shanon, E-mail: conordurack1@hotmail.com [Unit of Endodontology, Department of Conservative Dentistry, King' s College London, London (United Kingdom)

    2012-07-01

    Cone beam computed tomography (CBCT) is a contemporary, radiological imaging system designed specifically for use on the maxillofacial skeleton. The system overcomes many of the limitations of conventional radiography by producing undistorted, three-dimensional images of the area under examination. These properties make this form of imaging particularly suitable for use in endodontic. The clinician can obtain an enhanced appreciation of the anatomy being assessed, leading to an improvement in the detection of endodontic disease and resulting in more effective treatment planning. In addition, CBCT operates with a significantly lower effective radiation dose when compared with conventional computed tomography (CT). The purpose of this paper is to review the current literature relating to the limitations and potential applications of CBCT in endodontic practice. (author)

  18. Contact interactions for light-cone superstrings

    International Nuclear Information System (INIS)

    Restuccia, A.; Taylor, J.G.

    1990-01-01

    It was pointed out recently that the cubic interactions of the original light-cone gauge superstring field theory were incomplete. The addition of a quartic term H 4 was required in order to ensure that the total Hamiltonian, now (H 2 + H 3 + H 4 ) instead of (H 2 + H 3 ), be positive (where H n denotes a contribution to the L.C. field theory Hamiltonian of degree n in the fields). This latter is a condition guaranteed by [10]-SUSY; its violation would correspond to a violation of [10]-SUSY, which, however, the theory is supposed to possess. The construction of the full [10]-SUSY algebra was proposed in, but not completed there. These questions were analysed more fully in previous papers It is the purpose of this article to survey these developments. (author)

  19. Chemical profile of Taxodium distichum winter cones

    Directory of Open Access Journals (Sweden)

    Đapić Nina M.

    2017-01-01

    Full Text Available This work is concerned with the chemical profile of Taxodium distichum winter cones. The extract obtained after maceration in absolute ethanol was subjected to qualitative analysis by gas chromatography/mass spectrometry and quantification was done by gas chromatography/ flame ionization detector. The chromatogram revealed the presence of 53 compounds, of which 33 compounds were identified. The extract contained oxygenated monoterpenes (12.42%, sesquiterpenes (5.18%, oxygenated sesquiterpenes (17.41%, diterpenes (1.15%, and oxygenated diterpenes (30.87%, while the amount of retinoic acid was 0.32%. Monoacylglycerols were detected in the amount of 4.32%. The most abundant compounds were: caryophyllene oxide (14.27%, 6,7-dehydro-ferruginol (12.49%, bornyl acetate (10.96%, 6- deoxy-taxodione (9.50% and trans-caryophyllene (4.20%.

  20. Numerical Aspects of Cone Beam Contour Reconstruction

    Science.gov (United States)

    Louis, Alfred K.

    2017-12-01

    We describe a method for directly calculating the contours of a function from cone beam data. The algorithm is based on a new inversion formula for the gradient of a function presented in Louis (Inverse Probl 32(11):115005, 2016. http://stacks.iop.org/0266-5611/32/i=11/a=115005). The Radon transform of the gradient is found by using a Grangeat type of formula, reducing the inversion problem to the inversion of the Radon transform. In that way the influence of the scanning curve, vital for all exact inversion formulas for complete data, is avoided Numerical results are presented for the circular scanning geometry which neither fulfills the Tuy-Kirillov condition nor the much weaker condition given by the author in Louis (Inverse Probl 32(11):115005, 2016. http://stacks.iop.org/0266-5611/32/i=11/a=115005).

  1. Hybrid radial-cones trajectory for accelerated magnetic resonance imaging

    Science.gov (United States)

    Johnson, Kevin M.

    2016-01-01

    Purpose To design and develop ultra-short echo time k-space sampling schemes, radial-cones, which enable high sampling efficiency while maintaining compatibility with parallel imaging and compressed sensing reconstructions. Theory and Methods Radial-cones is a trajectory which samples 3D k-space utilizing a single base cone distributed along radial dimensions through a cost function based optimization. Trajectories were generated for highly undersampled, short readout sampling and compared to 3D radial sampling in point spread function (PSF) analysis, digital and physical phantoms, and initial human volunteers. Parallel imaging reconstructions were evaluated with and without the use of compressed sensing based regularization. Results Compared to 3D radial sampling, radial-cones reduced the peak value and energy of PSF aliasing. In both digital and physical phantoms, this improved sampling behavior corresponded to a reduction in the root-mean square error with a further reduction utilizing compressed sensing. A slight increase in noise and corresponding increase in apparent resolution was observed with radial-cones. In in-vivo feasibility testing, radial-cones reconstructed images has markedly lower apparent artifacts. Ultimate gains in imaging performance were limited by off-resonance blurring. Conclusion Radial-cones is an efficient Non-Cartesian sampling scheme enabling short echo readout with a high level of compatibility with parallel imaging and compressed sensing. PMID:27017991

  2. Optics of cone photoreceptors in the chicken (Gallus gallus domesticus).

    Science.gov (United States)

    Wilby, David; Toomey, Matthew B; Olsson, Peter; Frederiksen, Rikard; Cornwall, M Carter; Oulton, Ruth; Kelber, Almut; Corbo, Joseph C; Roberts, Nicholas W

    2015-10-06

    Vision is the primary sensory modality of birds, and its importance is evident in the sophistication of their visual systems. Coloured oil droplets in the cone photoreceptors represent an adaptation in the avian retina, acting as long-pass colour filters. However, we currently lack understanding of how the optical properties and morphology of component structures (e.g. oil droplet, mitochondrial ellipsoid and outer segment) of the cone photoreceptor influence the transmission of light into the outer segment and the ultimate effect they have on receptor sensitivity. In this study, we use data from microspectrophotometry, digital holographic microscopy and electron microscopy to inform electromagnetic models of avian cone photoreceptors to quantitatively investigate the integrated optical function of the cell. We find that pigmented oil droplets primarily function as spectral filters, not light collection devices, although the mitochondrial ellipsoid improves optical coupling between the inner segment and oil droplet. In contrast, unpigmented droplets found in violet-sensitive cones double sensitivity at its peak relative to other cone types. Oil droplets and ellipsoids both narrow the angular sensitivity of single cone photoreceptors, but not as strongly as those in human cones. © 2015 The Authors.

  3. Cadmium Removal from Aqueous Solutions by Ground Pine Cone

    Directory of Open Access Journals (Sweden)

    H Izanloo, S Nasseri

    2005-01-01

    Full Text Available A study on the removal of cadmium ions from aqueous solutions by pine cone was conducted in batch conditions. Kinetic data and equilibrium removal isotherms were obtained. The influence of different experimental parameters such as contact time, initial concentration of cadmium, pine cone mass and particle size, and temperature on the kinetics of cadmium removal was studied. Results showed that the main parameters that played an important role in removal phenomenon were initial cadmium concentration, particle size and pine cone mass. The necessary time to reach equilibrium was between 4 and 7 hours based on the initial concentration of cadmium. The capacity of cadmium adsorption at equilibrium increased with the decrease of pine cone particle size. The capacity of cadmium adsorption at equilibrium by pine cone increased with the quantity of pine cone introduced (1–4 g/L. Temperature in the range of 20-30°C showed a restricted effect on the removal kinetics (13.56 mg/g at 20°C and a low capacity of adsorption about 11.48 mg/g at 30°C. The process followed pseudo second-order kinetics. The cadmium uptake of pine cone was quantitatively evaluated using adsorption isotherms. Results indicated that the Langmuir model gave a better fit to the experimental data in comparison with the Freundlich equation.

  4. On intense proton beam generation and transport in hollow cones

    Directory of Open Access Journals (Sweden)

    J.J. Honrubia

    2017-01-01

    Full Text Available Proton generation, transport and interaction with hollow cone targets are investigated by means of two-dimensional PIC simulations. A scaled-down hollow cone with gold walls, a carbon tip and a curved hydrogen foil inside the cone has been considered. Proton acceleration is driven by a 1020 W·cm−2 and 1 ps laser pulse focused on the hydrogen foil. Simulations show an important surface current at the cone walls which generates a magnetic field. This magnetic field is dragged by the quasi-neutral plasma formed by fast protons and co-moving electrons when they propagate towards the cone tip. As a result, a tens of kT Bz field is set up at the cone tip, which is strong enough to deflect the protons and increase the beam divergence substantially. We propose using heavy materials at the cone tip and increasing the laser intensity in order to mitigate magnetic field generation and proton beam divergence.

  5. The Ngorongoro Volcanic Highland and its relationships to volcanic deposits at Olduvai Gorge and East African Rift volcanism.

    Science.gov (United States)

    Mollel, Godwin F; Swisher, Carl C

    2012-08-01

    The Ngorongoro Volcanic Highland (NVH), situated adjacent and to the east of Olduvai Gorge in northern Tanzania, is the source of the immense quantities of lava, ignimbrite, air fall ash, and volcaniclastic debris that occur interbedded in the Plio-Pleistocene sedimentary deposits in the Laetoli and Olduvai areas. These volcanics have proven crucial to unraveling stratigraphic correlations, the age of these successions, the archaeological and paleontological remains, as well as the source materials from which the bulk of the stone tools were manufactured. The NVH towers some 2,000 m above the Olduvai and Laetoli landscapes, affecting local climate, run-off, and providing varying elevation - climate controlled ecosystem, habitats, and riparian corridors extending into the Olduvai and Laetoli lowlands. The NVH also plays a crucial role in addressing the genesis and history of East African Rift (EAR) magmatism in northern Tanzania. In this contribution, we provide age and petrochemical compositions of the major NVH centers: Lemagurut, basalt to benmorite, 2.4-2.2 Ma; Satiman, tephrite to phonolite, 4.6-3.5 Ma; Oldeani, basalt to trachyandesite, 1.6-1.5 Ma; Ngorongoro, basalt to rhyolite, 2.3-2.0 Ma; Olmoti, basalt to trachyte, 2.0-1.8 Ma; Embagai, nephelinite to phonolite, 1.2-0.6 Ma; and Engelosin, phonolite, 3-2.7 Ma. We then discuss how these correlate in time and composition with volcanics preserved at Olduvai Gorge. Finally, we place this into context with our current understanding as to the eruptive history of the NVH and relationship to East African Rift volcanism. Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. Soil CO2 efflux measurement network by means of closed static chambers to monitor volcanic activity at Tenerife, Canary Islands

    Science.gov (United States)

    Amonte, Cecilia; García-Merino, Marta; Asensio-Ramos, María; Melián, Gladys; García-Hernández, Rubén; Pérez, Aaron; Hernández, Pedro A.; Pérez, Nemesio M.

    2017-04-01

    Tenerife (2304 km2) is the largest of the Canary Islands and has developed a central volcanic complex (Cañadas edifice), that started to grow about 3.5 My ago. Coeval with the construction of the Cañadas edifice, shield basaltic volcanism continued until the present along three rift zones oriented NW-SE, NE-SW and NS (hereinafter referred as NW, NE and NS respectively). Main volcanic historical activity has occurred along de NW and NE rift-zones, although summit cone of Teide volcano, in central volcanic complex, is the only area of the island where surface geothermal manifestations are visible. Uprising of deep-seated gases occurs along the aforementioned volcanic structures causing diffuse emissions at the surface environment of the rift-zones. In the last 20 years, there has been considerable interest in the study of diffuse degassing as a powerful tool in volcano monitoring programs. Diffuse degassing studies are even more important volcanic surveillance tool at those volcanic areas where visible manifestations of volcanic gases are absent. Historically, soil gas and diffuse degassing surveys in volcanic environments have focused mainly on CO2 because it is, after water vapor, the most abundant gas dissolved in magma. One of the most popular methods used to determine CO2 fluxes in soil sciences is based on the absorption of CO2 through an alkaline medium, in its solid or liquid form, followed by gravimetric, conductivity, or titration analyses. In the summer of 2016, a network of 31 closed static chambers was installed, covering the three main structural zones of Tenerife (NE, NW and NS) as well as Cañadas Caldera with volcanic surveillance porpoises. 50 cc of 0.1N KOH solution is placed inside the chamber to absorb the CO2 released from the soil. The solution is replaced weekly and the trapped CO2 is then analyzed at the laboratory by titration. The are expressed as weekly integrated CO2 efflux values. The CO2 efflux values ranged from 3.2 to 12.9 gṡm-2

  7. Conceptual model of volcanism and volcanic hazards of the region of Ararat valley, Armenia

    Science.gov (United States)

    Meliksetian, Khachatur; Connor, Charles; Savov, Ivan; Connor, Laura; Navasardyan, Gevorg; Manucharyan, Davit; Ghukasyan, Yura; Gevorgyan, Hripsime

    2015-04-01

    Armenia and the adjacent volcanically active regions in Iran, Turkey and Georgia are located in the collision zone between the Arabian and Eurasian lithospheric plates. The majority of studies of regional collision related volcanism use the model proposed by Keskin, (2003) where volcanism is driven by Neo-Tethyan slab break-off. In Armenia, >500 Quaternary-Holocene volcanoes from the Gegham, Vardenis and Syunik volcanic fields are hosted within pull-apart structures formed by active faults and their segments (Karakhanyan et al., 2002), while tectonic position of the large in volume basalt-dacite Aragats volcano and periphery volcanic plateaus is different and its position away from major fault lines necessitates more complex volcano-tectonic setup. Our detailed volcanological, petrological and geochemical studies provide insight into the nature of such volcanic activity in the region of Ararat Valley. Most magmas, such as those erupted in Armenia are volatile-poor and erupt fairly hot. Here we report newly discovered tephra sequences in Ararat valley, that were erupted from historically active Ararat stratovolcano and provide evidence for explosive eruption of young, mid K2O calc-alkaline and volatile-rich (>4.6 wt% H2O; amph-bearing) magmas. Such young eruptions, in addition to the ignimbrite and lava flow hazards from Gegham and Aragats, present a threat to the >1.4 million people (~ ½ of the population of Armenia). We will report numerical simulations of potential volcanic hazards for the region of Ararat valley near Yerevan that will include including tephra fallout, lava flows and opening of new vents. Connor et al. (2012) J. Applied Volcanology 1:3, 1-19; Karakhanian et al. (2002), JVGR, 113, 319-344; Keskin, M. (2003) Geophys. Res. Lett. 30, 24, 8046.

  8. Volcanic Gases and Hot Spring Water to Evaluate the Volcanic Activity of the Mt. Baekdusan

    Science.gov (United States)

    Yun, S. H.; Lee, S.; Chang, C.

    2017-12-01

    This study performed the analysis on the volcanic gases and hot spring waters from the Julong hot spring at Mt. Baekdu, also known as Changbaishan on the North Korea(DPRK)-China border, during the period from July 2015 to August 2016. Also, we confirmed the errors that HCO3- concentrations of hot spring waters in the previous study (Lee et al. 2014) and tried to improve the problem. Dissolved CO2 in hot spring waters was analyzed using gas chromatograph in Lee et al.(2014). Improving this, from 2015, we used TOC-IC to analysis dissolved CO2. Also, we analyzed the Na2CO3 standard solutions of different concentrations using GC, and confirmed the correlation between the analytical concentrations and the real concentrations. However, because the analytical results of the Julong hot spring water were in discord with the estimated values based on this correlation, we can't estimate the HCO3-concentrations of 2014 samples. During the period of study, CO2/CH4 ratios in volcanic gases are gradually decreased, and this can be interpreted in two different ways. The first interpretation is that the conditions inside the volcanic edifice are changing into more reduction condition, and carbon in volcanic gases become more favorable to distribute into CH4 or CO than CO2. The second interpretation is that the interaction between volcanic gases and water becomes greater than past, and the concentrations of CO2which have much higher solubility in water decreased, relatively. In general, the effect of scrubbing of volcanic gas is strengthened during the quiet periods of volcanic activity rather than active periods. Meanwhile, the analysis of hot spring waters was done on the anion of acidic gases species, the major cations, and some trace elements (As, Cd, Re).This work was funded by the Korea Meteorological Administration Research and Development Program under Grant KMIPA 2015-3060.

  9. Prebiotic Synthesis in Volcanic Discharges: Exposing Ash to Volcanic/Primordial Gas Atmospheres

    Science.gov (United States)

    Scheu, B.; Dingwell, D. B.; Cimarelli, C.; Bada, J.; Chalmers, J. H.; Burton, A. S.

    2017-12-01

    Few topics in natural science are as heavily debated as context for the emergence of life on Earth more than 3.5 billion years ago. The spark discharge experiments by Miller (1953) are widely recognized as the first efficient abiotic synthesis of organic compounds under simulated primitive Earth conditions; however, since then our understanding of conditions on the early Earth have significantly advanced. Still, considerable uncertainty remains regarding when, where and how the raw materials needed for prebiotic reactions and molecular evolution originated. Recently volcanic lightning has been successfully reproduced in rapid decompression experiments, showing a direct relation between amount of electrical discharges and the abundance of finer ash ejected. This correlation suggests that efficient fragmentation and particle clustering in the plume provide favorable conditions for charge generation and discharge. In the context of the origin of life, volcanic lightning is of special interest because within volcanic plumes the volcanic gases will mix with the primordial atmosphere, widening the possible gas spectrum. Here we present a first study on volcanic discharges generated from the energetic ejection of volcanic ash into different controlled atmospheres. Ash from Sakurajima volcano (Japan), well known for the electrical activity associated with its frequent explosive eruptions, was loaded in our experimental volcano (a shock-tube-based apparatus), slowly pressurized and ejected into atmospheres of various compositions (N2, CH4, NH3, CO2). We monitored ash ejection as well as charge generation and discharges. The recollected ash was analyzed for interesting prebiotic compounds. Analyses indicated that simple amino acids such as glycine were synthesized in the experiments as long as there was a reduced gas (either ammonia or methane) present. We are now carrying out a systematic series of analyses to determine whether essential prebiotic reagents are generated

  10. Evolution of the Red Sea volcanic margin, western Yemen

    Science.gov (United States)

    Menzies, Martin; Baker, Joel; Chazot, Gilles; Al'Kadasi, Mohamed

    The temporal relationships between rifting processes associated with the breakup of the Afro-Arabian Plate and the opening of the Red Sea have been studied on the uplifted volcanic margin in western Yemen. Excellent exposure allows for the application of absolute and relative dating techniques. Magmatism: 40Ar/39Ar dating of feldspars in the volcanic rocks indicates that (a) volcanism began at 29-31 Ma, (b) a change from basic to silicic volcanism occurred at ca. 29 Ma, (c) large volume volcanism lasted until 26.5 Ma, and (d) eruption rates decreased with time. Exhumation: fission track (FT) analyses of apatites from basement metamorphic and sedimentary rocks reveal that the volcanic margin was rapidly and deeply exhumed, at the earliest, in the Oligo-Miocene. This result is consistent with a major erosional break in the volcanic stratigraphy, bracketed by 40Ar/39Ar dating as having formed between 26 and 19 Ma. Extension: field evidence indicates that extension was largely post-volcanic because the volcanic stratigraphy is devoid of major faults. In highly extended terranes 40Ar/39Ar ages of "hanging wall" volcanic rocks and apatite FT ages of "footwall" basement rocks demonstrate that extension occurred in the late Oligocene-early Miocene. Surface uplift: field evidence for surface uplift may exist in the change from marine to continental sedimentation found in the pre-volcanic sedimentary rocks (>31 Ma). Exhumation, the presumed response to surface uplift, occurred some 6 m.y. later, allowing that amount of time for the volcanic margin to be uplifted by >2-3 km. Integration of field and laboratory data reveals that the Red Sea volcanic margin evolved in response to contemporaneous surface uplift and volcanism that predated extension and exhumation by as much as 5 m.y.

  11. [Effects of volcanic eruptions on human health in Iceland. Review].

    Science.gov (United States)

    Gudmundsson, Gunnar; Larsen, Guðrun

    2016-01-01

    Volcanic eruptions are common in Iceland and have caused health problems ever since the settlement of Iceland. Here we describe volcanic activity and the effects of volcanic gases and ash on human health in Iceland. Volcanic gases expelled during eruptions can be highly toxic for humans if their concentrations are high, irritating the mucus membranes of the eyes and upper respiratory tract at lower concentrations. They can also be very irritating to the skin. Volcanic ash is also irritating for the mucus membranes of the eyes and upper respiratory tract. The smalles particles of volcanic ash can reach the alveoli of the lungs. Described are four examples of volcanic eruptions that have affected the health of Icelanders. The eruption of Laki volcanic fissure in 1783-1784 is the volcanic eruption that has caused the highest mortality and had the greatest effects on the well-being of Icelanders. Despite multiple volcanic eruptions during the last decades in Iceland mortality has been low and effects on human health have been limited, although studies on longterm effects are lacking. Studies on the effects of the Eyjafjallajökul eruption in 2010 on human health showed increased physical and mental symptoms, especially in those having respiratory disorders. The Directorate of Health in Iceland and other services have responded promptly to recurrent volcanic eruptions over the last few years and given detailed instructions on how to minimize the effects on the public health. Key words: volcanic eruptions, Iceland, volcanic ash, volcanic gases, health effects, mortality. Correspondence: Gunnar Guðmundsson, ggudmund@landspitali.is.

  12. Managing the effects of accelerated glacial melting on volcanic collapse and debris flows: Planchon-Peteroa Volcano, Southern Andes

    Science.gov (United States)

    Tormey, Daniel

    2010-11-01

    Glaciated mountains are among the most sensitive environments to climatic changes, and recent work has shown that large-scale glacial melting, including at the end of the Pleistocene, caused a significant increase in the incidence of large volcanic sector collapse and debris flows on then-active volcanoes. With current accelerated rates of glacial melting, glaciated active volcanoes are at an increasing risk of sector collapse, debris flow and landslide. These catastrophic events are Earth's most damaging erosion phenomenon, causing extensive property damage and loss of life. This paper illustrates these effects in well-studied settings, focusing on the end-Pleistocene to Holocene glaciovolcanic growth and destruction of the cone of the active volcano Planchon-Peteroa in the Andean Southern Volcanic Zone at latitude 35° 15' S, along the border between Chile and Argentina. The development of the volcano over the last 14,000 years illustrates how glacial melting and magmatic activity can trigger landslides and sector collapses. Planchon had a large sector collapse that produced a highly mobile and erosive debris avalanche 11,000 years BP, and other slope instabilities during the end-Pleistocene/early Holocene deglaciation. The summit amphitheater left after the sector collapse was subject to alternating periods of glaciation and melting-induced lake formation. Breaching of the moraine dams then formed lahars and landslides originating at the western edge of the summit amphitheater, and the deposits are preserved along the western flank of the volcano. Deep incision of moraine deposits further down the western slope of the volcano indicates that the lahars and landslides were water-rich and had high erosive power. As illustrated by Planchon-Peteroa, the interplay among glacial growth and melting, magmatic activity, and slope stability is complex, but must be accounted for in volcanic hazard assessment. Planchon-Peteroa currently has the southernmost temperate zone

  13. Hermitian Yang-Mills instantons on Calabi-Yau cones

    Science.gov (United States)

    Paccetti Correia, Filipe

    2009-12-01

    We study and construct non-abelian hermitian Yang-Mills (HYM) instantons on Calabi-Yau cones. By means of a particular isometry preserving ansatz, the HYM equations are reduced to a novel Higgs-Yang-Mills flow on the Einstein-Kähler base. For any 2dBbb C-dimensional Calabi-Yau cone, we find explicit solutions of the flow equations that correspond to non-trivial SU(dBbb C) HYM instantons. These can be regarded as deformations of the spin connection of the Calabi-Yau cone.

  14. Instantaneous interactions of hadrons on the light cone

    International Nuclear Information System (INIS)

    Hyer, T.

    1994-01-01

    Hadron wave functions are most naturally defined in the framework of light-cone quantization, a Hamiltonian formulation quantized at equal light-cone ''time'' τ≡t+z. One feature of the light-cone perturbation theory is the presence of instantaneous interactions, which complicate the consideration of processes involving bound states. We show that these interactions can be written in a simple and general form, parametrized by an instantaneous contribution ψ to the hadronic wave function. We use the rotational invariance of Feynman diagrams to relate this instantaneous piece of the meson wave function to the propagating part, and to obtain constraints relating wave functions and quark fragmentation amplitudes

  15. Concrescence: Cone-Beam Computed Tomography Imaging Perspective.

    Science.gov (United States)

    Syed, Ali Zakir; Alluri, LeelaSubhashini Choudary; Mallela, Dhiraj; Frazee, Troy

    2016-01-01

    Concrescence is a form of twinning, formed by the confluence of cementum of two teeth at the root level. The diagnosis of concrescence has largely relied on the conventional 2D imaging. The 2D imaging has inherent limitations such as distortion and superimposition. Cone-Beam CT eliminates these limitations. The aim of this article was to describe a case of dental abnormality using Cone-Beam CT imaging modality. Volumetric data demonstrated confluence of left mandibular third molar with a paramolar, a supernumerary tooth. To our knowledge, this is the second case in the dental literature reported demonstrating the use of Cone-Beam CT in the diagnosis of concrescence.

  16. Alopecia associated with unexpected leakage from electron cone

    Energy Technology Data Exchange (ETDEWEB)

    Wen, B.C.; Pennington, E.C.; Hussey, D.H.; Jani, S.K.

    1989-06-01

    Excessive irradiation due to unexpected leakage was found on a patient receiving electron beam therapy. The cause of this leakage was analyzed and the amount of leakage was measured for different electron beam energies. The highest leakage occurred with a 6 x 6 cm cone using a 12 MeV electron beam. The leakage dose measured along the side of the cone could be as great as 40%. Until the cones are modified or redesigned, it is advised that all patient setups be carefully reviewed to assure that no significant patient areas are in the side scatter region.

  17. Alopecia associated with unexpected leakage from electron cone

    International Nuclear Information System (INIS)

    Wen, B.C.; Pennington, E.C.; Hussey, D.H.; Jani, S.K.

    1989-01-01

    Excessive irradiation due to unexpected leakage was found on a patient receiving electron beam therapy. The cause of this leakage was analyzed and the amount of leakage was measured for different electron beam energies. The highest leakage occurred with a 6 x 6 cm cone using a 12 MeV electron beam. The leakage dose measured along the side of the cone could be as great as 40%. Until the cones are modified or redesigned, it is advised that all patient setups be carefully reviewed to assure that no significant patient areas are in the side scatter region

  18. Formation of focused laser beams with a hollow metal cone

    International Nuclear Information System (INIS)

    Wu, Pinghui; Pan, Quanjun; Wei, Kaihua; Wu, Bo; Jiang, Peipei; Li, Jia; Peng, Xuefeng

    2015-01-01

    A hollow metal cone is designed to focus a laser beam into a tiny highly localized beam spot. The finite difference time domain method has been introduced to investigate the beam focusing effect along the propagation direction. Without considering the laser–plasma nonlinear interaction, the numerical calculation results show that a focal spot with a full width at half maximum of ∼0.7λ at greatly enhanced intensity and a depth of focus of ∼3λ can be achieved. In addition, the influences of cone angle, cone tip size, metal materials, sidewall thickness and incident wavelength on the focusing properties are analyzed in detail. (letter)

  19. Pulsar average wave forms and hollow-cone beam models

    Science.gov (United States)

    Backer, D. C.

    1976-01-01

    Pulsar wave forms have been analyzed from observations conducted over a wide radio-frequency range to assess the wave-form morphologies and to measure wave-form widths. The results of the analysis compare favorably with the predictions of a model with a hollow-cone beam of fixed dimensions and with random orientation of both the observer and the cone axis with respect to the pulsar spin axis. A class of three-component wave forms is included in the model by adding a central pencil beam to the hollow-cone hypothesis. The consequences of a number of discrepancies between observations and quantitative predictions of the model are discussed.

  20. Focusing of relativistic electron beams by a solid cone

    International Nuclear Information System (INIS)

    Chen, M; Sheng, Z M; Ma, Y Y; Li, Y T; Yuan, X H; Zhang, J

    2008-01-01

    A scheme for focusing relativistic electron beams has been proposed by use of a solid cone based upon two dimensional particle-in-cell simulations. We compare the transport of hot electrons, produced during the interaction of ultra-intense laser pulse with the targets, through the cone shape target and a flat target. It is found that relativistic electrons can be confined and focused effectively in the cone target case, where both the electron density and temperature have been increased more significantly than the flat target case

  1. Geology and petrology of the basalts of Crater Flat: applications to volcanic risk assessment for the Nevada Nuclear Waste Storage investigations

    International Nuclear Information System (INIS)

    Vaniman, D.; Crowe, B.

    1981-06-01

    Volcanic hazard studies of the south-central Great Basin, Nevada, are being conducted for the Nevada Nuclear Waste Storage Investigations. This report presents the results of field and petrologic studies of the basalts of Crater Flat, a sequence of Pliocene to Quaternary-age volcanic centers located near the southwestern part of the Nevada Test Site. Crater Flat is one of several basaltic fields constituting a north-northeast-trending volcanic belt of Late Cenozoic age extending from southern Death Valley, California, through the Nevada Test Site region to central Nevada. The basalts of Crater Flat are divided into three distinct volcanic cycles. The cycles are characterized by eruption of basalt magma of hawaiite composition that formed cinder cone clusters and associated lava flows. Total volume of erupted magma for respective cycles is given. The basalts of Crater Flat are sparsely to moderately porphyritic; the major phenocryst phase is olivine, with lesser amounts of plagioclase, clinopyroxene, and rare amphibole. The consistent recurrence of evolved hawaiite magmas in all three cycles points to crystal fractionation from more primitive magmas at depth. A possible major transition in mantle source regions through time may be indicated by a transition from normal to Rb-depleted, Sr-enriched hawaiites in the younger basaltic cycles. The recurrence of small volumes of hawaiite magma at Crater Flat supports assumptions required for probability modeling of future volcanic activity and provides a basis for estimating the effects of volcanic disruption of a repository site in the southwestern Nevada Test Site region. Preliminary data suggest that successive basalt cycles at Crater Flat may be of decreasing volume but recurring more frequently

  2. Trace Element Geochemistry of Basaltic Tephra in Maar Cores; Implications for Centre Correlation, Field Evolution, and Mantle Source Characteristics of the Auckland Volcanic Field, New Zealand

    Science.gov (United States)

    Hopkins, J. L.; Leonard, G.; Timm, C.; Wilson, C. J. N.; Neil, H.; Millet, M. A.

    2014-12-01

    Establishing volcanic hazard and risk management strategies hinges on a detailed understanding of the type, timing and tephra dispersal of past eruptions. In order to unravel the pyroclastic eruption history of a volcanic field, genetic links between the deposits and eruption source centre need to be established. The Auckland Volcanic Field (AVF; New Zealand) has been active for ca. 200 kyr and comprises ca. 53 individual centres covering an area of ca. 360km2. These centres show a range of sizes and eruptive styles from maar craters and tuff rings, to scoria cones and lava flows consistent with both phreatomagmatic and magmatic eruptions. Superimposition of the metropolitan area of Auckland (ca. 1.4 million inhabitants) on the volcanic field makes it critically important to assess the characteristics of the volcanic activity, on which to base assessment and management of the consequent hazards. Here we present a geochemical approach for correlating tephra deposits to their source centres. To acquire the most complete stratigraphic record of pyroclastic events, maar crater cores from different locations, covering various depths and thus ages across the field were selected. Magnetic susceptibility and x-ray density scanning of the cores was used to identify the basaltic tephra horizons, which were sampled and in-situ analysis of individual shards undertaken for major and trace elements using EPMA and LA-ICP-MS techniques, respectively. Our results show that tephra shard trace element ratios are comparable and complementary to the AVF whole rock database. The use of specific trace element ratios (e.g. Gd/Yb vs. Zr/Yb) allows us to fingerprint and cross correlate tephra horizons between cores and, when coupled with newly acquired 40Ar-39Ar age dating and eruption size estimates, correlate horizons to their source centres. This integrated style of study can provide valuable information to help volcanic hazard management and forecasting, and mitigation of related risks.

  3. Volcanic ash impacts on critical infrastructure

    Science.gov (United States)

    Wilson, Thomas M.; Stewart, Carol; Sword-Daniels, Victoria; Leonard, Graham S.; Johnston, David M.; Cole, Jim W.; Wardman, Johnny; Wilson, Grant; Barnard, Scott T.

    2012-01-01

    Volcanic eruptions can produce a wide range of hazards. Although phenomena such as pyroclastic flows and surges, sector collapses, lahars and ballistic blocks are the most destructive and dangerous, volcanic ash is by far the most widely distributed eruption product. Although ash falls rarely endanger human life directly, threats to public health and disruption to critical infrastructure services, aviation and primary production can lead to significant societal impacts. Even relatively small eruptions can cause widespread disruption, damage and economic loss. Volcanic eruptions are, in general, infrequent and somewhat exotic occurrences, and consequently in many parts of the world, the management of critical infrastructure during volcanic crises can be improved with greater knowledge of the likely impacts. This article presents an overview of volcanic ash impacts on critical infrastructure, other than aviation and fuel supply, illustrated by findings from impact assessment reconnaissance trips carried out to a wide range of locations worldwide by our international research group and local collaborators. ‘Critical infrastructure’ includes those assets, frequently taken for granted, which are essential for the functioning of a society and economy. Electricity networks are very vulnerable to disruption from volcanic ash falls. This is particularly the case when fine ash is erupted because it has a greater tendency to adhere to line and substation insulators, where it can cause flashover (unintended electrical discharge) which can in turn cause widespread and disruptive outages. Weather conditions are a major determinant of flashover risk. Dry ash is not conductive, and heavy rain will wash ash from insulators, but light rain/mist will mobilise readily-soluble salts on the surface of the ash grains and lower the ash layer’s resistivity. Wet ash is also heavier than dry ash, increasing the risk of line breakage or tower/pole collapse. Particular issues for water

  4. Volcanic Origin of Alkali Halides on Io

    Science.gov (United States)

    Schaefer, L.; Fegley, B., Jr.

    2003-01-01

    The recent observation of NaCl (gas) on Io confirms our earlier prediction that NaCl is produced volcanically. Here we extend our calculations by modeling thermochemical equilibrium of O, S, Li, Na, K, Rb, Cs, F, Cl, Br, and I as a function of temperature and pressure in a Pele-like volcanic gas with O/S/Na/Cl/K = 1.518/1/0.05/0.04/0.005 and CI chondritic ratios of the other (as yet unobserved) alkalis and halogens. For reference, the nominal temperature and pressure for Pele is 1760 plus or minus 210 K and 0.01 bars based on Galileo data and modeling.

  5. Skywave Radar Detectability of Volcanic Aersols

    Science.gov (United States)

    1984-08-01

    ash and gas ; (v) gases released explosively from the silicate liquid in the erupted magma ; and 4 "(vi) gases released explosively from the silicate...stratosphere by an erupting volcano on Java. This paper presents some theoretical estimates of the detectability of such clouds usingskyi:ave radar...prior to eruption ; (b) pumice - a rock froth formed by the rapid quenching of magma , composed . - -...-. of volcanic glass, crystals of several

  6. Volcanic disasters and incidents: A new database

    Science.gov (United States)

    Witham, C. S.

    2005-12-01

    A new database on human mortality and morbidity, and civil evacuations arising from volcanic activity is presented. The aim is to quantify the human impacts of volcanic phenomena during the 20th Century. Data include numbers of deaths, injuries, evacuees and people made homeless, and the nature of the associated volcanic phenomena. The database has been compiled from a wide range of sources, and discrepancies between these are indicated where they arise. The quality of the data varies according to the source and the impacts reported. Data for homelessness are particularly poor and effects from ashfall and injuries appear to be under-reported. Of the 491 events included in the database, ˜53% resulted in deaths, although the total death toll of 91,724 is dominated by the disasters at Mt Pelée and Nevado del Ruiz. Pyroclastic density currents account for the largest proportion of deaths, and lahars for the most injuries incurred. The Philippines, Indonesia, and Southeast Asia, as a region, were the worst affected, and middle-income countries experienced greater human impacts than low or high-income countries. Compilation of the database has highlighted a number of problems with the completeness and accuracy of the existing CRED EM-DAT disaster database that includes volcanic events. This database is used by a range of organisations involved with risk management. The new database is intended as a resource for future analysis and will be made available via the Internet. It is hoped that it will be maintained and expanded.

  7. K-Ar ages, paleomagnetism, and geochemistry of the South Auckland volcanic field, North Island, New Zealand

    International Nuclear Information System (INIS)

    Briggs, R.M.; Okada, T.; Itaya, T.; Shibuya, H.; Smith, I.E.M.

    1994-01-01

    The South Auckland volcanic field is one of the Pliocene-Quaternary intraplate basaltic fields in northern North Island. It consists of at least 97 monogenetic volcanic centres covering an area of c. 300 km 2 , 38 km south of Auckland. Fifty-nine of the volcanic centres are characterised by mainly magmatic or effusive activity that constructed scoria cones and lava flows, while 38 are mainly phreatomagmatic or explosive that produced tuff rings and maars. Rock types consist of basanites, hawaiites, nepheline hawaiites, transitional basalts, and ol-tholeiitic basalts, with relatively minor amounts of nephelinites, alkali basalts, Q-tholeiitic basalts, and nepheline mugearites. Forty-three new K-Ar ages are presented, which range from 0.51 to 1.59 Ma, and show two peaks of activity at 0.6 and 1.3 Ma. Paleomagnetic determinations at 26 selected sites agree well with the paleomagnetic reversal time scale and support the K-Ar age data. Age data from each of the volcanic fields of Okete, Ngatutura, South Auckland, and Auckland, which constitute the Auckland intraplate basaltic province, show that they have developed within a time span of 0.3-1.1 Ma. After activity ceased in any particular field, a new field then developed 35-38 km to the north. These consistent time/space patterns indicate the possibility of a mantle source migrating northwards at c. 5 cm/yr. There is no correlation of rock composition with time, which is consistent with observations in the Northland intraplate province, but is not consistent with the formerly invoked rising diapir model. (author). 30 refs., 8 figs., 3 tabs

  8. Preliminary volcano-hazard assessment for the Katmai volcanic cluster, Alaska

    Science.gov (United States)

    Fierstein, Judy; Hildreth, Wes

    2000-01-01

    , 1999, 2000, 2001; Hildreth and Fierstein, 2000), only half of which had been named previously—the four stratovolcanoes Mounts Katmai, Mageik, Martin, and Griggs; the cone cluster called Trident Volcano; Snowy Mountain; and the three lava domes Novarupta, Mount Cerberus, and Falling Mountain. The most recent eruptions were from Trident Volcano (1953–74), but there have been at least eight other, probably larger, explosive events from the volcanoes of this area in the past 10,000 years. This report summarizes what has been learned about the volcanic histories and styles of eruption of all these volcanoes. Many large earthquakes occurred before and during the 1912 eruption, and the cluster of Katmai volcanoes remains seismically active. Because we expect an increase in seismicity before eruptions, seismic monitoring efforts to detect volcanic unrest and procedures for eruption notification and dissemination of information are included in this report. Most at risk from future eruptions of the Katmai volcanic cluster are (1) air-traffic corridors of the North Pacific, including those approaching Anchorage, one of the Pacific’s busiest international airports, (2) several regional airports and military air bases, (3) fisheries and navigation on the Naknek Lake system and Shelikof Strait, (4) pristine wildlife habitat, particularly that of the Alaskan brown bear, and (5) tourist facilities in and near Katmai National Park.

  9. Geothermal and volcanism in west Java

    Science.gov (United States)

    Setiawan, I.; Indarto, S.; Sudarsono; Fauzi I, A.; Yuliyanti, A.; Lintjewas, L.; Alkausar, A.; Jakah

    2018-02-01

    Indonesian active volcanoes extend from Sumatra, Jawa, Bali, Lombok, Flores, North Sulawesi, and Halmahera. The volcanic arc hosts 276 volcanoes with 29 GWe of geothermal resources. Considering a wide distribution of geothermal potency, geothermal research is very important to be carried out especially to tackle high energy demand in Indonesia as an alternative energy sources aside from fossil fuel. Geothermal potency associated with volcanoes-hosted in West Java can be found in the West Java segment of Sunda Arc that is parallel with the subduction. The subduction of Indo-Australian oceanic plate beneath the Eurasian continental plate results in various volcanic products in a wide range of geochemical and mineralogical characteristics. The geochemical and mineralogical characteristics of volcanic and magmatic rocks associated with geothermal systems are ill-defined. Comprehensive study of geochemical signatures, mineralogical properties, and isotopes analysis might lead to the understanding of how large geothermal fields are found in West Java compared to ones in Central and East Java. The result can also provoke some valuable impacts on Java tectonic evolution and can suggest the key information for geothermal exploration enhancement.

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

    Science.gov (United States)

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

    2014-06-01

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

  11. The palaeogeographic setting and the local environmental impact of the 130 ka Falconiera tuff-cone eruption (Ustica island, Italy)

    Science.gov (United States)

    de Vita, Sandro; Foresta Martin, Franco

    2017-04-01

    This research focuses on the effects of the last eruption at Ustica (Suthern Tyrrhenian Sea, Italy), which formed the Falconiera tuff-cone at around 130 ka BP in the north-eastern tip of the island. This eruption was mainly explosive and phreatomagmatic, and emplaced a series of pyroclastic surge beds that formed an asymmetric tuff cone. This is the most easily recognizable volcanic edifice on Ustica, although its north-eastern sector has been partially eroded. A section of the feeding conduit is exposed northward, and is composed of lavas that fed the last stages of the eruption characterized by an intracrateric lava lake and a Strombolian scoria-fallout deposit. The eruption occurred during Upper Pleistocene Marine Isotopic Substage 5.5, a warm period characterized by a high sea-level stand (6±3 m above the present sea level in stable areas) and the diffusion of subtropical flora and fauna across the Mediterranean sea. This eruption slightly modified the morphology of Ustica, but impacted both marine and terrestrial environments, burying beach deposits rich in mollusk shells (i.e. Strombus bubonius, Conus testudinarius, Brachidontes puniceus), colonies of corals (Cladocora caespitosa) and subaerial plants (Chamaerops humilis). These organisms, found in some cases in their life position, along with other lines of evidence, provide information on the palaeogeography of this sector of the island at the time of the eruption, and on the local impact of this event on the environment.

  12. Morphometric and magmatic evolution at the Boset-Bericha Volcanic Complex in the Main Ethiopian Rift

    Science.gov (United States)

    Siegburg, Melanie; Gernon, Thomas; Bull, Jonathan; Keir, Derek; Taylor, Rex; Nixon, Casey; Abebe, Bekele; Ayele, Atalay

    2017-04-01

    Tectono-magmatic interactions are an intrinsic feature of continental rifting and break up in the Main Ethiopian Rift (MER). The Boset-Bericha volcanic complex (BBVC) is one of the largest stratovolcanoes in the MER (with a total area of ˜870 km2), with volcanism largely occurring over the last ˜2 Myr. Despite the fact that 4 million people live within 100 km of the volcano, little is known about its eruptive history and how the volcanic system interacts with rift valley tectonics. Here, we present a detailed relative eruption chronology combined with morphometric analyses of different elements of the volcanic complex and petrological analyses to constrain morphometric and magmatic evolution at the BBVC. Additionally, tectonic activity has been characterised around the BBVC, all based on field observations and mapping using high-resolution digital elevation data. The BBVC consists of the Gudda Volcano and the younger Bericha Volcano, two silicic eruption centres located along the NNE-SSW trending rift axis. The fault population predominantly comprises distributed extensional faults parallel to the rift axis, as well as localised discrete faults with displacements of up to 50 m in the rift centre, and up to 200 m in the NE-SW trending border fault system. Multiple cones, craters and fissure systems are also oriented parallel to the rift axis, i.e. perpendicular to the minimum compressive stress. The eruption history of BBVC can be differentiated into 5 main eruption stages, subdivided into at least 12 eruptive phases with a total of 128 mappable lava flows. Crosscutting relationships of lava flows provide a relative chronology of the eruptive history of the BBVC, starting with pre-BBVC rift floor basalts, pre-caldera and caldera activity, three post-caldera phases at the Gudda Volcano and two phases forming the Bericha Volcano. At least four fissure eruption phases occurred along the rift axis temporally in between the main eruptive phases. Morphometric analyses

  13. CO2 diffuse emission from maar lake: An example in Changbai volcanic field, NE China

    Science.gov (United States)

    Sun, Yutao; Guo, Zhengfu; Liu, Jiaqi; Du, Jianguo

    2018-01-01

    Numerous maars and monogenetic volcanic cones are distributed in northeast China, which are related to westward deep subduction of the Pacific Ocean lithosphere, comprising a significant part of the "Pacific Ring of Fire". It is well known that diffuse CO2 emissions from monogenetic volcanoes, including wet (e.g., maar lake) and dry degassing systems (e.g., soil diffuse emission, fault degassing, etc.), may contribute to budget of globally nature-derived greenhouse gases. However, their relationship between wet (e.g., maar lake) and concomitant dry degassing systems (e.g., soil diffuse emission, fault degassing, etc.) related to monogenetic volcanic field is poorly understood. Yuanchi maar, one of the typical monogenetic volcanic systems, is located on the eastern flank of Tianchi caldera in Changbai volcanic field of northeast China, which displays all of three forms of CO2 degassing including the maar lake, soil micro-seepage and fault degassing. Measurements of efflux of CO2 diffusion from the Yuanchi maar system (YMS) indicate that the average values of CO2 emissions from soil micro-seepage, fault degassing and water-air interface diffusion are 24.3 ± 23.3 g m- 2 d- 1, 39.2 ± 22.4 g m- 2 d- 1 and 2.4 ± 1.1 g m- 2 d- 1, respectively. The minimum output of CO2 diffuse emission from the YMS to the atmosphere is about 176.1 ± 88.3 ton/yr, of which 80.4% results from the dry degassing system. Degassing from the fault contributes to the most of CO2 emissions in all of the three forms of degassing in the YMS. Contributions of mantle, crust, air and organic CO2 to the soil gas are 0.01-0.10%, 10-20%, 32-36% and 48-54%, respectively, which are quantitatively constrained by a He-C isotope coupling calculation model. We propose that CO2 exsolves from the upper mantle melting beneath the Tianchi caldera, which migrates to the crustal magma chamber and further transports to the surface of YMS along the deep fault system. During the transportation processes, the emission

  14. Global volcanic emissions: budgets, plume chemistry and impacts

    Science.gov (United States)

    Mather, T. A.

    2012-12-01

    Over the past few decades our understanding of global volcanic degassing budgets, plume chemistry and the impacts of volcanic emissions on our atmosphere and environment has been revolutionized. Global volcanic emissions budgets are needed if we are to make effective use of regional and global atmospheric models in order to understand the consequences of volcanic degassing on global environmental evolution. Traditionally volcanic SO2 budgets have been the best constrained but recent efforts have seen improvements in the quantification of the budgets of other environmentally important chemical species such as CO2, the halogens (including Br and I) and trace metals (including measurements relevant to trace metal atmospheric lifetimes and bioavailability). Recent measurements of reactive trace gas species in volcanic plumes have offered intriguing hints at the chemistry occurring in the hot environment at volcanic vents and during electrical discharges in ash-rich volcanic plumes. These reactive trace species have important consequences for gas plume chemistry and impacts, for example, in terms of the global fixed nitrogen budget, volcanically induced ozone destruction and particle fluxes to the atmosphere. Volcanically initiated atmospheric chemistry was likely to have been particularly important before biological (and latterly anthropogenic) processes started to dominate many geochemical cycles, with important consequences in terms of the evolution of the nitrogen cycle and the role of particles in modulating the Earth's climate. There are still many challenges and open questions to be addressed in this fascinating area of science.

  15. Propagation characteristics of resonance cone in a nonuniform magnetic field

    International Nuclear Information System (INIS)

    Ohnuma, T.; Sanuki, H.

    1984-01-01

    Propagation characteristics of resonance cone field for frequencies below the electron cyclotron frequency are described in a mirror magnetic field on the basis of fluid equation. Theoretical results are compared qualitatively with those of experiment

  16. New fixed and periodic point results on cone metric spaces

    Directory of Open Access Journals (Sweden)

    Ghasem Soleimani Rad

    2014-05-01

    Full Text Available In this paper, several xed point theorems for T-contraction of two maps on cone metric spaces under normality condition are proved. Obtained results extend and generalize well-known comparable results in the literature.

  17. Determination of the Resistance of Cone-Shaped Solid Electrodes

    DEFF Research Database (Denmark)

    Frandsen, Henrik Lund; Hendriksen, Peter Vang; Koch, Søren

    2017-01-01

    during processing can be avoided. Newman's formula for current constriction in the electrolyte is then used to deduce the active contact area based on the ohmic resistance of the cell, and from this the surface specific electro-catalytic activity. However, for electrode materials with low electrical...... conductivity (like Ce1-xPrxO2-δ), the resistance of the cell is significantly influenced by the ohmic resistance of the cone electrode, wherefore it must be included. In this work the ohmic resistance of a cone is modelled analytically based on simplified geometries. The two analytical models only differ...... by a model specific pre-factor, which is consequently determined by a finite element model. The model was applied to measurements on cones of Ce1-xPrxO2-δ  characterized on an YSZ electrolyte. Conclusively, the finite element model was used to obtain a formula for the resistance for different cone angles...

  18. Holographic entanglement entropy for hollow cones and banana shaped regions

    Energy Technology Data Exchange (ETDEWEB)

    Dorn, Harald [Institut für Physik und IRIS Adlershof, Humboldt-Universität zu Berlin,Zum Großen Windkanal 6, D-12489 Berlin (Germany)

    2016-06-09

    We consider banana shaped regions as examples of compact regions, whose boundary has two conical singularities. Their regularised holographic entropy is calculated with all divergent as well as finite terms. The coefficient of the squared logarithmic divergence, also in such a case with internally curved boundary, agrees with that calculated in the literature for infinite circular cones with their internally flat boundary. For the otherwise conformally invariant coefficient of the ordinary logarithmic divergence an anomaly under exceptional conformal transformations is observed. The construction of minimal submanifolds, needed for the entanglement entropy of cones, requires fine-tuning of Cauchy data. Perturbations of such fine-tuning leads to solutions relevant for hollow cones. The divergent parts for the entanglement entropy of hollow cones are calculated. Increasing the difference between the opening angles of their outer and inner boundary, one finds a transition between connected solutions for small differences to disconnected solutions for larger ones.

  19. Effect of loss cone on confinement in toroidal helical device

    International Nuclear Information System (INIS)

    Itoh, K.; Itoh, S.-I.; Fukuyama, A.; Hanatani, K.

    1988-12-01

    Analytical estimation is given on the loss cone in the toroidal helical devices in the presence of the radial electric field and the modulation of the helical ripple. The minimum energy of particles entering the loss cone is calculated. The modulation is not always effective in reducing the loss in the presence of the radial electric field. The plasma loss due to the loss cone is estimated in the collisionless limit. The radial electric field is estimated in the presence of the loss cone. It is found that the transition to the solution with positive radial electric field, which is necessary to achieve the high-ion-temperature mode, becomes difficult. This difficulty is large for the systems with the small helical ripple. (author)

  20. Development of pits and cones on ion bombarded copper

    International Nuclear Information System (INIS)

    Tanovic, L.A.; Carter, G.; Nobes, M.J.; Whitton, I.L.; Williams, J.S.

    1980-01-01

    The formation of pits and cones on Ar ion bombarded copper has been studied. Carefully polished surfaces of large grained 99.999% pure copper crystals have been bombarded at normal incidence with 40 keV argon ions. The cone formation has been investigated for annealed and non-annealed crystals at room temperature and at 30 K and in the case of monocrystal and polycrystal samples. Although in the most other studies the presence of impurities is as a necessary condition for generation of cones and pits the obtained experimental results show that under certain conditions these features are formed on clean surfaces. It is shown that the dominant parameter in the production of cones on copper is the crystal orientation [ru

  1. Syndecan Promotes Axon Regeneration by Stabilizing Growth Cone Migration

    Directory of Open Access Journals (Sweden)

    Tyson J. Edwards

    2014-07-01

    Full Text Available Growth cones facilitate the repair of nervous system damage by providing the driving force for axon regeneration. Using single-neuron laser axotomy and in vivo time-lapse imaging, we show that syndecan, a heparan sulfate (HS proteoglycan, is required for growth cone function during axon regeneration in C. elegans. In the absence of syndecan, regenerating growth cones form but are unstable and collapse, decreasing the effective growth rate and impeding regrowth to target cells. We provide evidence that syndecan has two distinct functions during axon regeneration: (1 a canonical function in axon guidance that requires expression outside the nervous system and depends on HS chains and (2 an intrinsic function in growth cone stabilization that is mediated by the syndecan core protein, independently of HS. Thus, syndecan is a regulator of a critical choke point in nervous system repair.

  2. Helical cardiac cone beam reconstruction using retrospective ECG gating

    International Nuclear Information System (INIS)

    Grass, M; Manzke, R; Nielsen, T; Koken, P; Proksa, R; Natanzon, M; Shechter, G

    2003-01-01

    In modern computer tomography (CT) systems, the fast rotating gantry and the increased detector width enable 3D imaging of the heart. Cardiac volume CT has a high potential for non-invasive coronary angiography with high spatial resolution and short scan time. Due to the increased detector width, true cone beam reconstruction methods are needed instead of adapted 2D reconstruction schemes. In this paper, the extended cardiac reconstruction method is introduced. It integrates the idea of retrospectively gated cardiac reconstruction for helical data acquisition into a cone beam reconstruction framework. It leads to an efficient and flexible algorithmic scheme for the reconstruction of single- and multi-phase cardiac volume datasets. The method automatically adapts the number of cardiac cycles used for the reconstruction. The cone beam geometry is fully taken into account during the reconstruction process. Within this paper, results are presented on patient datasets which have been acquired using a 16-slice cone beam CT system

  3. Theory of suppression of loss cone instabilities by electron beams

    International Nuclear Information System (INIS)

    Sinha, A.; Sinha, M.

    1981-01-01

    A new mechanism for the suppression of Drift Cyclotron Loss Cone instabilities by electron beams injected along the field lines is given. The mechanism explains some of the recent observations. (author)

  4. Direct cone beam SPECT reconstruction with camera tilt

    International Nuclear Information System (INIS)

    Jianying Li; Jaszczak, R.J.; Greer, K.L.; Coleman, R.E.; Zongjian Cao; Tsui, B.M.W.

    1993-01-01

    A filtered backprojection (FBP) algorithm is derived to perform cone beam (CB) single-photon emission computed tomography (SPECT) reconstruction with camera tilt using circular orbits. This algorithm reconstructs the tilted angle CB projection data directly by incorporating the tilt angle into it. When the tilt angle becomes zero, this algorithm reduces to that of Feldkamp. Experimentally acquired phantom studies using both a two-point source and the three-dimensional Hoffman brain phantom have been performed. The transaxial tilted cone beam brain images and profiles obtained using the new algorithm are compared with those without camera tilt. For those slices which have approximately the same distance from the detector in both tilt and non-tilt set-ups, the two transaxial reconstructions have similar profiles. The two-point source images reconstructed from this new algorithm and the tilted cone beam brain images are also compared with those reconstructed from the existing tilted cone beam algorithm. (author)

  5. Breakaway safety feature for an intra-oral cone system

    International Nuclear Information System (INIS)

    Biggs, P.J.; Wang, C.C.

    1984-01-01

    With an increasing number of high energy accelerators in operation, intra-oral electron radiotherapy is likely to become a more widely-used modality in the treatment of lesions of the oral cavity. However, there is one potential problem associated with this modality which concerns patient safety. There must never be any uncontrolled movement of the couch or gantry while the cone is in the patients's mouth, otherwise serious consequences could occur. In an effort to overcome this problem, a set of cones previously constructed by the authors for use in intra-oral electron radiotherapy has been modified to include a breakaway safety feature. This modification consists of separating the plate into which each of the treatment cones screws, into two pieces, the dividing line being in the shape of a cone frustum flaring out in the upward direction

  6. Testing the reliability of ice-cream cone model

    Science.gov (United States)

    Pan, Zonghao; Shen, Chenglong; Wang, Chuanbing; Liu, Kai; Xue, Xianghui; Wang, Yuming; Wang, Shui

    2015-04-01

    Coronal Mass Ejections (CME)'s properties are important to not only the physical scene itself but space-weather prediction. Several models (such as cone model, GCS model, and so on) have been raised to get rid of the projection effects within the properties observed by spacecraft. According to SOHO/ LASCO observations, we obtain the 'real' 3D parameters of all the FFHCMEs (front-side full halo Coronal Mass Ejections) within the 24th solar cycle till July 2012, by the ice-cream cone model. Considering that the method to obtain 3D parameters from the CME observations by multi-satellite and multi-angle has higher accuracy, we use the GCS model to obtain the real propagation parameters of these CMEs in 3D space and compare the results with which by ice-cream cone model. Then we could discuss the reliability of the ice-cream cone model.

  7. Volcanic hazards from Bezymianny- and Bandai-type eruptions

    Science.gov (United States)

    Siebert, L.; Glicken, H.; Ui, T.

    1987-01-01

    Major slope failures are a significant degradational process at volcanoes. Slope failures and associated explosive eruptions have resulted in more than 20 000 fatalities in the past 400 years; the historic record provides evidence for at least six of these events in the past century. Several historic debris avalanches exceed 1 km3 in volume. Holocene avalanches an order of magnitude larger have traveled 50-100 km from the source volcano and affected areas of 500-1500 km2. Historic eruptions associated with major slope failures include those with a magmatic component (Bezymianny type) and those solely phreatic (Bandai type). The associated gravitational failures remove major segments of the volcanoes, creating massive horseshoe-shaped depressions commonly of caldera size. The paroxysmal phase of a Bezymianny-type eruption may include powerful lateral explosions and pumiceous pyroclastic flows; it is often followed by construction of lava dome or pyroclastic cone in the new crater. Bandai-type eruptions begin and end with the paroxysmal phase, during which slope failure removes a portion of the edifice. Massive volcanic landslides can also occur without related explosive eruptions, as at the Unzen volcano in 1792. The main potential hazards from these events derive from lateral blasts, the debris avalanche itself, and avalanche-induced tsunamis. Lateral blasts produced by sudden decompression of hydrothermal and/or magmatic systems can devastate areas in excess of 500km2 at velocities exceeding 100 m s-1. The ratio of area covered to distance traveled for the Mount St. Helens and Bezymianny lateral blasts exceeds that of many pyroclastic flows or surges of comparable volume. The potential for large-scale lateral blasts is likely related to the location of magma at the time of slope failure and appears highest when magma has intruded into the upper edifice, as at Mount St. Helens and Bezymianny. Debris avalanches can move faster than 100 ms-1 and travel tens of

  8. Geophysical expression of caldera related volcanism, structures and mineralization in the McDermitt volcanic field

    Science.gov (United States)

    Rytuba, J. J.; Blakely, R. J.; Moring, B.; Miller, R.

    2013-12-01

    The High Rock, Lake Owyhee, and McDermitt volcanic fields, consisting of regionally extensive ash flow tuffs and associated calderas, developed in NW Nevada and SE Oregon following eruption of the ca. 16.7 Ma Steens flood basalt. The first ash flow, the Tuff of Oregon Canyon, erupted from the McDermitt volcanic field at 16.5Ma. It is chemically zoned from peralkaline rhyolite to dacite with trace element ratios that distinguish it from other ash flow tuffs. The source caldera, based on tuff distribution, thickness, and size of lithic fragments, is in the area in which the McDermitt caldera (16.3 Ma) subsequently formed. Gravity and magnetic anomalies are associated with some but not all of the calderas. The White Horse caldera (15.6 Ma), the youngest caldera in the McDermitt volcanic field has the best geophysical expression, with both aeromagnetic and gravity lows coinciding with the caldera. Detailed aeromagnetic and gravity surveys of the McDermitt caldera, combined with geology and radiometric surveys, provides insight into the complexities of caldera collapse, resurgence, post collapse volcanism, and hydrothermal mineralization. The McDermitt caldera is among the most mineralized calderas in the world, whereas other calderas in these three Mid Miocene volcanic fields do not contain important hydrothermal ore deposits, despite having similar age and chemistry. The McDermitt caldera is host to Hg, U, and Li deposits and potentially significant resources of Ga, Sb, and REE. The geophysical data indicate that post-caldera collapse intrusions were important in formation of the hydrothermal systems. An aeromagnetic low along the E caldera margin reflects an intrusion at a depth of 2 km associated with the near-surface McDermitt-hot-spring-type Hg-Sb deposit, and the deeper level, high-sulfidation Ga-REE occurrence. The Li deposits on the W side of the caldera are associated with a series of low amplitude, small diameter aeromagnetic anomalies that form a continuous

  9. A Clinical Evaluation Of Cone Beam Computed Tomography

    Science.gov (United States)

    2016-06-01

    reliability of multidetector computed tomography and cone beam computed tomography in the assessment of dental implant site dimensions. Dentomaxillofacial...A CLINICAL EVALUATION OF CONE BEAM COMPUTED TOMOGRAPHY by Bryan James Behm, D.D.S. Lieutenant, Dental Corps United States Navy A thesis...submitted to the Faculty of the Endodontic Graduate Program Naval Postgraduate Dental School Uniformed Services University of the Health Sciences in

  10. Weather effects on the success of longleaf pine cone crops

    Science.gov (United States)

    Daniel J. Leduc; Shi-Jean Susana Sung; Dale G. Brockway; Mary Anne Sword Sayer

    2016-01-01

    We used National Oceanic and Atmospheric Administration weather data and historical records of cone crops from across the South to relate weather conditions to the yield of cones in 10 longleaf pine (Pinus palustris Mill.) stands. Seed development in this species occurs over a three-year time period and weather conditions during any part of this...

  11. Dimensional regularization and dimensional reduction in the light cone

    Science.gov (United States)

    Qiu, J.

    2008-06-01

    We calculate all of the 2 to 2 scattering process in Yang-Mills theory in the light cone gauge, with the dimensional regulator as the UV regulator. The IR is regulated with a cutoff in q+. It supplements our earlier work, where a Lorentz noncovariant regulator was used, and the final results bear some problems in gauge fixing. Supersymmetry relations among various amplitudes are checked by using the light cone superfields.

  12. Delayed cone-opponent signals in the luminance pathway.

    Science.gov (United States)

    Stockman, Andrew; Henning, G Bruce; Anwar, Sharif; Starba, Robert; Rider, Andrew T

    2018-02-01

    Cone signals in the luminance or achromatic pathway were investigated by measuring how the perceptual timing of M- or L-cone-detected flicker depended on temporal frequency and chromatic adaptation. Relative timings were measured, as a function of temporal frequency, by superimposing M- or L-cone-isolating flicker on "equichromatic" flicker (flicker of the same wavelength as the background) and asking observers to vary contrast and phase to cancel the perception of flicker. Measurements were made in four observers on up to 35 different backgrounds varying in wavelength and radiance. Observers showed substantial perceptual delays or advances of L- and M-cone flicker that varied systematically with cone class, background wavelength, and radiance. Delays were largest for M-cone-isolating flicker. Although complex, the results can be characterised by a surprisingly simple model in which the representations of L- and M-cone flicker are comprised not only of a fast copy of the flicker signal, but also of a slow copy that is delayed by roughly 30 ms and varies in strength and sign with both background wavelength and radiance. The delays, which are too large to be due to selective cone adaptation by the chromatic backgrounds, must arise postreceptorally. Clear evidence for the slow signals can also be found in physiological measurements of horizontal and magnocellular ganglion cells, thus placing the origin of the slow signals in the retina-most likely in an extended horizontal cell network. Luminance-equated stimuli chosen to isolate chromatic channels may inadvertently generate slow signals in the luminance channel.

  13. Operational Based Vision Assessment Cone Contrast Test: Description and Operation

    Science.gov (United States)

    2016-06-02

    The primary intensities required to generate a particular cone excitation levels is determined by This application uses the CIE 2006 LMS... mathematics needed to implement the technique were published by Estevez and Spekreijse in 1982 [5]. Because a test stimulus in the OBVA CCT...at a criterion level ) is primarily determined by the most sensitive mechanism. 2. Cone-opponent mechanisms are more sensitive than the achromatic

  14. A tuff cone erupted under frozen-bed ice (northern Victoria Land, Antarctica): linking glaciovolcanic and cosmogenic nuclide data for ice sheet reconstructions

    Science.gov (United States)

    Smellie, J. L.; Rocchi, S.; Johnson, J. S.; Di Vincenzo, G.; Schaefer, J. M.

    2018-01-01

    The remains of a small volcanic centre are preserved on a thin bedrock ridge at Harrow Peaks, northern Victoria Land, Antarctica. The outcrop is interpreted as a monogenetic tuff cone relict formed by a hydrovolcanic (phreatomagmatic) eruption of mafic magma at 642 ± 20 ka (by 40Ar-39Ar), corresponding to the peak of the Marine Isotope Stage 16 (MIS16) glacial. Although extensively dissected and strewn with glacial erratics, the outcrop shows no evidence for erosion by ice. From interpretation of the lithofacies and eruptive mechanisms, the weight of the evidence suggests that eruptions took place under a cold-based (frozen-bed) ice sheet. This is the first time that a tuff cone erupted under cold ice has been described. The most distinctive feature of the lithofacies is the dominance of massive lapilli tuff rich in fine ash matrix and abraded lapilli. The lack of stratification is probably due to repeated eruption through a conduit blasted through the ice covering the vent. The ice thickness is uncertain but it might have been as little as 100 m and the preserved tephra accumulated mainly as a crater (or ice conduit) infill. The remainder of the tuff cone edifice was probably deposited supraglacially and underwent destruction by ice advection and, particularly, collapse during a younger interglacial. Dating using 10Be cosmogenic exposure of granitoid basement erratics indicates that the erratics are unrelated to the eruptive period. The 10Be ages suggest that the volcanic outcrop was most recently exposed by ice decay at c. 20.8 ± 0.8 ka (MIS2) and the associated ice was thicker than at 642 ka and probably polythermal rather than cold-based, which is normally assumed for the period.

  15. Functional complexity of the axonal growth cone: a proteomic analysis.

    Directory of Open Access Journals (Sweden)

    Adriana Estrada-Bernal

    Full Text Available The growth cone, the tip of the emerging neurite, plays a crucial role in establishing the wiring of the developing nervous system. We performed an extensive proteomic analysis of axonal growth cones isolated from the brains of fetal Sprague-Dawley rats. Approximately 2000 proteins were identified at ≥ 99% confidence level. Using informatics, including functional annotation cluster and KEGG pathway analysis, we found great diversity of proteins involved in axonal pathfinding, cytoskeletal remodeling, vesicular traffic and carbohydrate metabolism, as expected. We also found a large and complex array of proteins involved in translation, protein folding, posttranslational processing, and proteasome/ubiquitination-dependent degradation. Immunofluorescence studies performed on hippocampal neurons in culture confirmed the presence in the axonal growth cone of proteins representative of these processes. These analyses also provide evidence for rough endoplasmic reticulum and reveal a reticular structure equipped with Golgi-like functions in the axonal growth cone. Furthermore, Western blot revealed the growth cone enrichment, relative to fetal brain homogenate, of some of the proteins involved in protein synthesis, folding and catabolism. Our study provides a resource for further research and amplifies the relatively recently developed concept that the axonal growth cone is equipped with proteins capable of performing a highly diverse range of functions.

  16. Meaning of visualizing retinal cone mosaic on adaptive optics images.

    Science.gov (United States)

    Jacob, Julie; Paques, Michel; Krivosic, Valérie; Dupas, Bénédicte; Couturier, Aude; Kulcsar, Caroline; Tadayoni, Ramin; Massin, Pascale; Gaudric, Alain

    2015-01-01

    To explore the anatomic correlation of the retinal cone mosaic on adaptive optics images. Retrospective nonconsecutive observational case series. A retrospective review of the multimodal imaging charts of 6 patients with focal alteration of the cone mosaic on adaptive optics was performed. Retinal diseases included acute posterior multifocal placoid pigment epitheliopathy (n = 1), hydroxychloroquine retinopathy (n = 1), and macular telangiectasia type 2 (n = 4). High-resolution retinal images were obtained using a flood-illumination adaptive optics camera. Images were recorded using standard imaging modalities: color and red-free fundus camera photography; infrared reflectance scanning laser ophthalmoscopy, fluorescein angiography, indocyanine green angiography, and spectral-domain optical coherence tomography (OCT) images. On OCT, in the marginal zone of the lesions, a disappearance of the interdigitation zone was observed, while the ellipsoid zone was preserved. Image recording demonstrated that such attenuation of the interdigitation zone co-localized with the disappearance of the cone mosaic on adaptive optics images. In 1 case, the restoration of the interdigitation zone paralleled that of the cone mosaic after a 2-month follow-up. Our results suggest that the interdigitation zone could contribute substantially to the reflectance of the cone photoreceptor mosaic. The absence of cones on adaptive optics images does not necessarily mean photoreceptor cell death. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. CRYOVOLCANISM AND THE MYSTERY OF THE PATOM CONE

    Directory of Open Access Journals (Sweden)

    Vladimir R. Alekseyev

    2012-01-01

    Full Text Available In the Earth’s regions with cold climate, cryovolcanism is widespread. This phenomena is manifested as eruptions of material due to freezing of closed-type or open-type water-bearing systems which is accompanied by generation of effusive topographic forms, such as «pingo». The Patom cone is a typical structure created by cryovolcanism in fractured bedrocksof the Proterozoic age. The cone was shaped a result of the long-term, possibly multistage freezing of the hydrogeological structure during continuous and complicated phase of cryo- and speleo-genesis. The ice-saturated breccia containing limestone, sandstone and shale, which composed the cone, was subject to slow spreading due to its plastic properties; the top of the mound developed into a subsidence cone bordered by ring-shaped ramparts and a knoll in the middle, while thelongitudinal profile took on an asymmetric form. The absence of soil and vegetation cover on the surface of the cone, and a relatively weak degree of weathering of the rudaceous deposits bear no evidence that the geological object is young. The question as to the age of the cone is still open.

  18. Modulation of growth cone filopodial length by carbon monoxide.

    Science.gov (United States)

    Estes, Stephen; Artinian, Liana; Rehder, Vincent

    2017-06-01

    Carbon monoxide (CO) is physiologically produced via heme degradation by heme oxygenase enzymes. Whereas CO has been identified as an important physiological signaling molecule, the roles it plays in neuronal development and regeneration are poorly understood. During these events, growth cones guide axons through a rich cellular environment to locate target cells and establish synaptic connections. Previously, we have shown that another gaseous signaling molecule, nitric oxide (NO), has potent effects on growth cone motility. With NO and CO sharing similar cellular targets, we wanted to determine whether CO affected growth cone motility as well. We assessed how CO affected growth cone filopodial length and determined the signaling pathway by which this effect was mediated. Using two well-characterized neurons from the freshwater snail, Helisoma trivolvis, it was found that the CO donor, carbon monoxide releasing molecule-2 (CORM-2), increased filopodial length. CO utilized a signaling pathway that involved the activation of soluble guanylyl cyclase, protein kinase G, and ryanodine receptors. While increases in filopodial length often occur from robust increases in intracellular calcium levels, the timing in which CO increased filopodial length corresponded with low basal calcium levels in growth cones. Taken together with findings of a heme oxygenase-like protein in the Helisoma nervous system, these results provide evidence for CO as a modulator of growth cone motility and implicate CO as a neuromodulatory signal during neuronal development and/or regeneration. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 677-690, 2017. © 2016 Wiley Periodicals, Inc.

  19. A reconstruction algorithms for helical cone-beam SPECT

    International Nuclear Information System (INIS)

    Weng, Y.; Zeng, G.L.; Gullberg, G.T.

    1993-01-01

    Cone-beam SPECT provides improved sensitivity for imaging small organs like the brain and heart. However, current cone-beam tomography with the focal point traversing a planar orbit does not acquire sufficient data to give an accurate reconstruction. In this paper, the authors employ a data-acquisition method which obtains complete data for cone-beam SPECT by simultaneously rotating the gamma camera and translating the patient bed, so that cone-beam projections can be obtained with the focal point traversing a helix surrounding the patient. An implementation of Grangeat's algorithm for helical cone-beam projections is developed. The algorithm requires a rebinning step to convert cone-beam data to parallel-beam data which are then reconstructed using the 3D Radon inversion. A fast new rebinning scheme is developed which uses all of the detected data to reconstruct the image and properly normalizes any multiply scanned data. This algorithm is shown to produce less artifacts than the commonly used Feldkamp algorithm when applied to either a circular planar orbit or a helical orbit acquisition. The algorithm can easily be extended to any arbitrary orbit

  20. Singularities of plane complex curves and limits of Kähler metrics with cone singularities. I: Tangent Cones

    Directory of Open Access Journals (Sweden)

    Borbon Martin de

    2017-02-01

    Full Text Available The goal of this article is to provide a construction and classification, in the case of two complex dimensions, of the possible tangent cones at points of limit spaces of non-collapsed sequences of Kähler-Einstein metrics with cone singularities. The proofs and constructions are completely elementary, nevertheless they have an intrinsic beauty. In a few words; tangent cones correspond to spherical metrics with cone singularities in the projective line by means of the Kähler quotient construction with respect to the S1-action generated by the Reeb vector field, except in the irregular case ℂβ₁×ℂβ₂ with β₂/ β₁ ∉ Q.

  1. Computation of supersonic laminar viscous flow past a pointed cone at angle of attack in spinning and coning motion

    Science.gov (United States)

    Agarwal, R.; Rakich, J. V.

    1978-01-01

    Computational results obtained with a parabolic Navier-Stokes marching code are presented for supersonic viscous flow past a pointed cone at angle of attack undergoing a combined spinning and coning motion. The code takes into account the asymmetries in the flow field resulting from the motion and computes the asymmetric shock shape, crossflow and streamwise shear, heat transfer, crossflow separation and vortex structure. The side force and moment are also computed. Reasonably good agreement is obtained with the side force measurements of Schiff and Tobak. Comparison is also made with the only available numerical inviscid analysis. It is found that the asymmetric pressure loads due to coning motion are much larger than all other viscous forces due to spin and coning, making viscous forces negligible in the combined motion.

  2. Cone beam computed tomography in veterinary dentistry.

    Science.gov (United States)

    Van Thielen, Bert; Siguenza, Francis; Hassan, Bassam

    2012-01-01

    The purpose of this study was to assess the feasibility of cone beam computed tomography (CBCT) in imaging dogs and cats for diagnostic dental veterinary applications. CBCT scans of heads of six dogs and two cats were made. Dental panoramic and multi-planar reformatted (MPR) para-sagittal reconstructions were created using specialized software. Image quality and visibility of anatomical landmarks were subjectively assessed by two observers. Good image quality was obtained for the MPR para-sagittal reconstructions through multiple teeth. The image quality of the panoramic reconstructions of dogs was moderate while the panoramic reconstructions of cats were poor since the images were associated with an increased noise level. Segmental panoramic reconstructions of the mouth seem to be useful for studying the dental anatomy especially in dogs. The results of this study using human dental CBCT technology demonstrate the potential of this scanning technology in veterinary medicine. Unfortunately, the moderate image quality obtained with the CBCT technique reported here seems to be inferior to the diagnostic image quality obtained from 2-dimensional dental radiographs. Further research is required to optimize scanning and reconstruction protocols for veterinary applications.

  3. Supervolcanoes Within an Ancient Volcanic Province in Arabia Terra, Mars

    Science.gov (United States)

    Michalski, Joseph. R.; Bleacher, Jacob E.

    2014-01-01

    Several irregularly shaped craters located within Arabia Terra, Mars represent a new type of highland volcanic construct and together constitute a previously unrecognized martian igneous province. Similar to terrestrial supervolcanoes, these low-relief paterae display a range of geomorphic features related to structural collapse, effusive volcanism, and explosive eruptions. Extruded lavas contributed to the formation of enigmatic highland ridged plains in Arabia Terra. Outgassed sulfur and erupted fine-grained pyroclastics from these calderas likely fed the formation of altered, layered sedimentary rocks and fretted terrain found throughout the equatorial region. Discovery of a new type of volcanic construct in the Arabia volcanic province fundamentally changes the picture of ancient volcanism and climate evolution on Mars. Other eroded topographic basins in the ancient Martian highlands that have been dismissed as degraded impact craters should be reconsidered as possible volcanic constructs formed in an early phase of widespread, disseminated magmatism on Mars.

  4. Preservation of cone photoreceptors after a rapid yet transient degeneration and remodeling in cone-only Nrl−/− mouse retina

    Science.gov (United States)

    Roger, Jerome E; Ranganath, Keerthi; Zhao, Lian; Cojocaru, Radu I; Brooks, Matthew; Gotoh, Norimoto; Veleri, Shobi; Hiriyanna, Avinash; Rachel, Rivka A; Campos, Maria Mercedes; Fariss, Robert N; Wong, Wai T; Swaroop, Anand

    2012-01-01

    Cone photoreceptors are the primary initiator of visual transduction in the human retina. Dysfunction or death of rod photoreceptors precedes cone loss in many retinal and macular degenerative diseases, suggesting a rod-dependent trophic support for cone survival. Rod differentiation and homeostasis are dependent on the basic motif leucine zipper transcription factor NRL. The loss of Nrl (Nrl−/−) in mice results in a retina with predominantly S-opsin containing cones that exhibit molecular and functional characteristics of WT cones. Here we report that Nrl−/− retina undergoes a rapid but transient period of degeneration in early adulthood, with cone apoptosis, retinal detachment, alterations in retinal vessel structure, and activation and translocation of retinal microglia. However, cone degeneration stabilizes by four months of age, resulting in a thinner but intact outer nuclear layer with residual cones expressing S- and M-opsins and a preserved photopic ERG. At this stage, microglia translocate back to the inner retina and reacquire a quiescent morphology. Gene profiling analysis during the period of transient degeneration reveals misregulation of genes related to stress response and inflammation, implying their involvement in cone death. The Nrl−/− mouse illustrates the long-term viability of cones in the absence of rods and RPE defects in a rodless retina. We propose that Nrl−/− retina may serve as a model for elucidating mechanisms of cone homeostasis and degeneration that would be relevant to understanding diseases of the cone-dominant human macula. PMID:22238088

  5. Los volcanes del Sistema Volcánico Transversal

    Directory of Open Access Journals (Sweden)

    Esperanza Yarza de la Torre

    2012-02-01

    Full Text Available Si hizo la selección de textos referentes a algunos de los volcanes que integran el Sistema Volcánico Transversal. Publicado en: Yarza de De la Torre, E. (1992, "Los volcanes del Sistema Volcánico Transversal", Volcanes de México, 4a ed. corregida y aumentada, Instituto de Geografía, UNAM, México, pp. 82-83, 89-136.

  6. Los volcanes del Sistema Volcánico Transversal

    OpenAIRE

    Esperanza Yarza de De la Torre

    2003-01-01

    Si hizo la selección de textos referentes a algunos de los volcanes que integran el Sistema Volcánico Transversal. Publicado en: Yarza de De la Torre, E. (1992), "Los volcanes del Sistema Volcánico Transversal", Volcanes de México, 4a ed. corregida y aumentada, Instituto de Geografía, UNAM, México, pp. 82-83, 89-136.

  7. Volcanism Studies: Final Report for the Yucca Mountain Project

    International Nuclear Information System (INIS)

    Crowe, Bruce M.; Perry, Frank V.; Valentine, Greg A.; Bowker, Lynn M.

    1998-01-01

    This report synthesizes the results of volcanism studies conducted by scientists at the Los Alamos National Laboratory and collaborating institutions on behalf of the Department of Energy's Yucca Mountain Project. An assessment of the risk of future volcanic activity is one of many site characterization studies that must be completed to evaluate the Yucca Mountain site for potential long-term storage of high-level radioactive waste. The presence of several basaltic volcanic centers in the Yucca Mountain region of Pliocene and Quaternary age indicates that there is a finite risk of a future volcanic event occurring during the 10,000-year isolation period of a potential repository. Chapter 1 introduces the volcanism issue for the Yucca Mountain site and provides the reader with an overview of the organization, content, and significant conclusions of this report. The risk of future basaltic volcanism is the primary topic of concern including both events that intersect a potential repository and events that occur near or within the waste isolation system of a repository. Future volcanic events cannot be predicted with certainty but instead are estimated using formal methods of probabilistic volcanic hazard assessment (PVHA). Chapter 2 describes the volcanic history of the Yucca Mountain region (YMR) and emphasizes the Pliocene and Quaternary volcanic record, the interval of primary concern for volcanic risk assessment. The distribution, eruptive history, and geochronology of Plio-Quaternary basalt centers are described by individual center emphasizing the younger postcaldera basalt ( than about 7 x 10 -8 events yr -1 . Simple probability estimates are used to assess possible implications of not drilling aeromagnetic anomalies in the Amargosa Valley. The sensitivity of the disruption probability to the location of northeast boundaries of volcanic zones near the Yucca Mountain sit

  8. Out-of-plane magnetized cone-shaped magnetic nanoshells

    Science.gov (United States)

    Ball, D. K.; Günther, S.; Fritzsche, M.; Lenz, K.; Varvaro, G.; Laureti, S.; Makarov, D.; Mücklich, A.; Facsko, S.; Albrecht, M.; Fassbender, J.

    2017-03-01

    The geometry of a magnetic nano-object, namely its shape and dimensions determines the complex electromagnetic responses. Here, we address the geometry-induced changes of the magnetic properties of thin ferromagnetic Co/Pd multilayers with out-of-plane magnetic anisotropy deposited on three-dimensionally curved templates. For this purpose, arrays of self-assembled cone-shaped nano-objects with a chracteristic size of either 30 or 70 nm were created in GaSb(0 0 1) by the ion erosion technique. The templates are designed in the way that the shape of the cone remains the same for all the samples; namely, we keep the opening angle at about 55° by adjusting the ratio between the cone height and its base diameter to be about 1. In this case, we are able to address the impact of the linear dimensions of the object on the magnetic properties and exclude the impact of the shape from the consideration. The deposition of 15 nm thick Co/Pd multilayers on top of the cone templates results in the formation of a close-packed array of 2D magnetic cone-shaped shells. Integral angle-dependent magnetometry measurements demonstrate that the local curvature results in the spread of the easy axes of magnetization following the shape of the nanocones independent of the linear dimensions of the cones. At the same time different local magnetic domain patterns are observed for samples prepared on 30 and 70 nm large cones. When the thickness of the magnetic shell is only half of the linear dimension of a cone, a clear multidomain state is observed. Remarkably, we find that the neighboring magnetic cone-shaped shells are exchange decoupled when the linear dimension of a cone is four times larger compared to the thickness of the magnetic shell. These findings are relevant for the further development of tilted bit patterned magnetic recording media as well as for the emergent field of magnetism in curved geometries.

  9. Gravity and magnetic investigation of maar volcanoes, Auckland volcanic field, New Zealand

    Science.gov (United States)

    Cassidy, John; France, Sian J.; Locke, Corinne A.

    2007-01-01

    Detailed gravity and aeromagnetic data over maars in the Auckland volcanic field reveal contrasting anomalies, even where surface geology is similar. Pukaki and Pukekiwiriki, almost identical maars marked by sediment-filled craters and tuff rings, have gravity and magnetic anomalies of - 6 g.u. and 20 nT, and 8 g.u. and 160 nT, respectively. The Domain and Waitomokia maars, with similar tuff rings but each with a small central scoria cone, have gravity and magnetic anomalies of 32 g.u. and 300 nT, and 21 g.u. and 310 nT, respectively. These differences in geophysical expression are attributed to varying volumes of dense, magnetic basalt in the form of shallow bowl-shaped bodies up to several hundreds of metres in diameter and up to 140 m thick beneath the maar centres. These bodies are interpreted as solidified magma that ponded into early-formed phreatomagmatic explosion craters. Where magma supply was limited relative to groundwater availability, no residual subsurface basalt occurs (as at Pukaki); continued magma supply, but limited groundwater, resulted in ponding (e.g. at Pukekiwiriki) and eventually the building of a scoria cone (as at Domain and Waitomokia). There is no evidence in these geophysical data for diatreme structures below the maars or for shallow and/or extensive feeder dykes associated with these maars. If diatreme structures do occur, their lack of geophysical signature must be a consequence of either their small geophysical contrast with host Miocene sediments and/or masking by the stronger anomalies associated with the subsurface basalt. In addition, any magma conduits appear to be confined centrally beneath the maars, at least to shallow depths (upper 100 m).

  10. The Quaternary history of effusive volcanism of the Nevado de Toluca area, Central Mexico

    Science.gov (United States)

    Torres-Orozco, R.; Arce, J. L.; Layer, P. W.; Benowitz, J. A.

    2017-11-01

    Andesite and dacite lava flows and domes, and intermediate-mafic cones from the Nevado de Toluca area were classified into five groups using field data and 40Ar/39Ar geochronology constraints. Thirty-four lava units of diverse mineralogy and whole-rock major-element geochemistry, distributed between the groups, were identified. These effusive products were produced between ∼1.5 and ∼0.05 Ma, indicating a mid-Pleistocene older-age for Nevado de Toluca volcano, coexisting with explosive products that suggest a complex history for this volcano. A ∼0.96 Ma pyroclastic deposit attests for the co-existence of effusive and explosive episodes in the mid-Pleistocene history. Nevado de Toluca initiated as a composite volcano with multiple vents until ∼1.0 Ma, when the activity began to centralize in an area close to the present-day crater. The modern main edifice reached its maximum height at ca. 50 ka after bulky, spiny domes erupted in the current summit of the crater. Distribution and geochemical behavior in major elements of lavas indicate a co-magmatic relationship between different andesite and dacite domes and flows, although unrelated to the magmatism of the monogenetic volcanism. Mafic-intermediate magma likely replenished the system at Nevado de Toluca since ca. ∼1.0 Ma and contributed to the eruption of new domes, cones, as well as effusive-explosive activity. Altogether, field and laboratory data suggest that a large volume of magma was ejected around 1 Ma in and around the Nevado de Toluca.

  11. Basaltic volcanic episodes of the Yucca Mountain region

    Energy Technology Data Exchange (ETDEWEB)

    Crowe, B.M.

    1990-03-01

    The purpose of this paper is to summarize briefly the distribution and geologic characteristics of basaltic volcanism in the Yucca Mountain region during the last 10--12 Ma. This interval largely postdates the major period of silicic volcanism and coincides with and postdates the timing of major extensional faulting in the region. Field and geochronologic data for the basaltic rocks define two distinct episodes. The patterns in the volume and spatial distribution of these basaltic volcanic episodes in the central and southern part of the SNVF are used as a basis for forecasting potential future volcanic activity in vicinity of Yucca Mountain. 33 refs., 2 figs.

  12. Integrating Multiple Space Ground Sensors to Track Volcanic Activity

    Science.gov (United States)

    Chien, Steve; Davies, Ashley; Doubleday, Joshua; Tran, Daniel; Jones, Samuel; Kjartansson, Einar; Thorsteinsson, Hrobjartur; Vogfjord, Kristin; Guomundsson, Magnus; Thordarson, Thor; hide

    2011-01-01

    Volcanic activity can occur with little or no warning. Increasing numbers of space borne assets can enable coordinated measurements of volcanic events to enhance both scientific study and hazard response. We describe the use of space and ground measurements to target further measurements as part of a worldwide volcano monitoring system. We utilize a number of alert systems including the MODVOLC, GOESVOLC, US Air Force Weather Advisory, and Volcanic Ash Advisory Center (VAAC) alert systems. Additionally we use in-situ data from ground instrumentation at a number of volcanic sites, including Iceland.

  13. Identification, distribution and significance of lunar volcanic domes.

    Science.gov (United States)

    Smith, E. I.

    1973-01-01

    Over 300 previously unrecognized volcanic domes were identified on Lunar Orbiter photographs using the following criteria: (1) the recognition of land forms on the Moon similar in morphology to terrestrial volcanic domes, (2) structural control, (3) geomorphic discordance, and (4) the recognition of land forms modified by dome-like swellings. Many terrestrial volcanic domes are similar in morphology to lunar domes. This analogy suggests that some lunar hills are in fact extrusive volcanic domes. Many of the domes identified in this paper seem to be related to basins and craters, and with the exception of local tectonic grid control few domes are related to any observable Moon-wide pattern.

  14. Effect of volcanic tuff on the characteristics of cement mortar

    Directory of Open Access Journals (Sweden)

    Jehad Al-Zou'by

    2014-06-01

    Full Text Available This paper examines how Jordanian volcanic tuff aggregates affect the characteristics of cement mortar. Five mortar mixes were prepared by replacing normal aggregate (standard sand with volcanic tuff aggregate in ratios of 0, 25, 50, 75, and 100% (M1 to M5, respectively. Compressive strength, flexural strength, and unit weight were tested at mortar ages of 3, 7, 28, and 56 days. The results revealed improved compressive and flexural strength, which were maximal for the M3 sample. Unit weight decreased as the ratio of volcanic tuff increased. Based on these results, adding Jordanian volcanic tuff in the appropriate ratio will improve these mortar characteristics.

  15. The change of magma chamber depth in and around the Baekdu Volcanic area from late Cenozoic

    Science.gov (United States)

    Lee, S. H.; Oh, C. W.; Lee, Y. S.; Lee, S. G.; Liu, J.

    2016-12-01

    The Baekdu Volcano is a 2750m high stratovolcanic cone resting on a basaltic shield and plateau and locates on the North Korea-China border. Its volcanic history can be divided into four stages (from the oldest to the youngest): (i) preshield plateau-forming eruptions, (ii) basalt shield formation, (iii) construction of a trachytic composite cone, and (iv) explosive ignimbrite forming eruptions. In the First stage, a fissure eruption produced basalts from the Oligocene to the Miocene (28-13 Ma) forming preshield plateau. Fissure and central eruptions occurred together during the shield-forming eruptions (4.21-1.70 Ma). In the third stage, the trachytic composite volcano formed during the Pleistocene (0.61-0.09 Ma). In this stage, magma changed to an acidic melt. The latest stage has been characterized by explosive ignimbrite-forming eruptions during the Holocene. The composite volcanic part consists of the Xiaobaishan, Lower, Middle and Upper Trachytes with rhyolites. The whole rock and clinopyroxene in basalts, trachytic and rhyolite, are analyzed to study the depth of magma chambers under the Baekdu Volcano. From the rhyolite, 9.8-12.7kbar is obtained for the depth of magma chamber. 3.7-4.1, 8.9-10.5 and 8.7 kbar are obtained from the middle, lower and Xiaobaishan trachytes. From the first and second stage basalts, 16.9-17.0 kbar and 14-14.4kbar are obtained respectively. The first stage basalt give extrusive age of 11.98 Ma whereas 1.12 and 1.09 Ma are obtained from the feldspar and groundmass in the second stage basalt. The Xiaobaishan trachyte and rhyolite give 0.25 and 0.21 Ma whereas the Middle trachyte gives 0.07-0.06 Ma. These data indicate that the magma chambers of the first and second stage basalts were located in the mantle and the magma chamber for the second stage basalt may have been underplated below continental crust. The Xiaobisan trachyte and rhyolite originated from the magma chamber in the depth of ca. 30-40 km and the Middle trachyte

  16. VOLCANIC RISK ASSESSMENT - PROBABILITY AND CONSEQUENCES

    International Nuclear Information System (INIS)

    G.A. Valentine; F.V. Perry; S. Dartevelle

    2005-01-01

    Risk is the product of the probability and consequences of an event. Both of these must be based upon sound science that integrates field data, experiments, and modeling, but must also be useful to decision makers who likely do not understand all aspects of the underlying science. We review a decision framework used in many fields such as performance assessment for hazardous and/or radioactive waste disposal sites that can serve to guide the volcanological community towards integrated risk assessment. In this framework the underlying scientific understanding of processes that affect probability and consequences drive the decision-level results, but in turn these results can drive focused research in areas that cause the greatest level of uncertainty at the decision level. We review two examples of the determination of volcanic event probability: (1) probability of a new volcano forming at the proposed Yucca Mountain radioactive waste repository, and (2) probability that a subsurface repository in Japan would be affected by the nearby formation of a new stratovolcano. We also provide examples of work on consequences of explosive eruptions, within the framework mentioned above. These include field-based studies aimed at providing data for ''closure'' of wall rock erosion terms in a conduit flow model, predictions of dynamic pressure and other variables related to damage by pyroclastic flow into underground structures, and vulnerability criteria for structures subjected to conditions of explosive eruption. Process models (e.g., multiphase flow) are important for testing the validity or relative importance of possible scenarios in a volcanic risk assessment. We show how time-dependent multiphase modeling of explosive ''eruption'' of basaltic magma into an open tunnel (drift) at the Yucca Mountain repository provides insight into proposed scenarios that include the development of secondary pathways to the Earth's surface. Addressing volcanic risk within a decision

  17. Hubble Captures Volcanic Eruption Plume From Io

    Science.gov (United States)

    1997-01-01

    The Hubble Space Telescope has snapped a picture of a 400-km-high (250-mile-high) plume of gas and dust from a volcanic eruption on Io, Jupiter's large innermost moon.Io was passing in front of Jupiter when this image was taken by the Wide Field and Planetary Camera 2 in July 1996. The plume appears as an orange patch just off the edge of Io in the eight o'clock position, against the blue background of Jupiter's clouds. Io's volcanic eruptions blasts material hundreds of kilometers into space in giant plumes of gas and dust. In this image, material must have been blown out of the volcano at more than 2,000 mph to form a plume of this size, which is the largest yet seen on Io.Until now, these plumes have only been seen by spacecraft near Jupiter, and their detection from the Earth-orbiting Hubble Space Telescope opens up new opportunities for long-term studies of these remarkable phenomena.The plume seen here is from Pele, one of Io's most powerful volcanos. Pele's eruptions have been seen before. In March 1979, the Voyager 1 spacecraft recorded a 300-km-high eruption cloud from Pele. But the volcano was inactive when the Voyager 2 spacecraft flew by Jupiter in July 1979. This Hubble observation is the first glimpse of a Pele eruption plume since the Voyager expeditions.Io's volcanic plumes are much taller than those produced by terrestrial volcanos because of a combination of factors. The moon's thin atmosphere offers no resistance to the expanding volcanic gases; its weak gravity (one-sixth that of Earth) allows material to climb higher before falling; and its biggest volcanos are more powerful than most of Earth's volcanos.This image is a contrast-enhanced composite of an ultraviolet image (2600 Angstrom wavelength), shown in blue, and a violet image (4100 Angstrom wavelength), shown in orange. The orange color probably occurs because of the absorption and/or scattering of ultraviolet light in the plume. This light from Jupiter passes through the plume and is

  18. An Analysis Model for Water Cone Subsidence in Bottom Water Drive Reservoirs

    Science.gov (United States)

    Wang, Jianjun; Xu, Hui; Wu, Shucheng; Yang, Chao; Kong, lingxiao; Zeng, Baoquan; Xu, Haixia; Qu, Tailai

    2017-12-01

    Water coning in bottom water drive reservoirs, which will result in earlier water breakthrough, rapid increase in water cut and low recovery level, has drawn tremendous attention in petroleum engineering field. As one simple and effective method to inhibit bottom water coning, shut-in coning control is usually preferred in oilfield to control the water cone and furthermore to enhance economic performance. However, most of the water coning researchers just have been done on investigation of the coning behavior as it grows up, the reported studies for water cone subsidence are very scarce. The goal of this work is to present an analytical model for water cone subsidence to analyze the subsidence of water cone when the well shut in. Based on Dupuit critical oil production rate formula, an analytical model is developed to estimate the initial water cone shape at the point of critical drawdown. Then, with the initial water cone shape equation, we propose an analysis model for water cone subsidence in bottom water reservoir reservoirs. Model analysis and several sensitivity studies are conducted. This work presents accurate and fast analytical model to perform the water cone subsidence in bottom water drive reservoirs. To consider the recent interests in development of bottom drive reservoirs, our approach provides a promising technique for better understanding the subsidence of water cone.

  19. Slab dehydration in Cascadia and its relationship to volcanism, seismicity, and non-volcanic tremor

    Science.gov (United States)

    Delph, J. R.; Levander, A.; Niu, F.

    2017-12-01

    The characteristics of subduction beneath the Pacific Northwest (Cascadia) are variable along strike, leading to the segmentation of Cascadia into 3 general zones: Klamath, Siletzia, and Wrangelia. These zones show marked differences in tremor density, earthquake density, seismicity rates, and the locus and amount of volcanism in the subduction-related volcanic arc. To better understand what controls these variations, we have constructed a 3D shear-wave velocity model of the upper 80 km along the Cascadia margin from the joint inversion of CCP-derived receiver functions and ambient noise surface wave data using 900 temporary and permanent broadband seismic stations. With this model, we can investigate variations in the seismic structure of the downgoing oceanic lithosphere and overlying mantle wedge, the character of the crust-mantle transition beneath the volcanic arc, and local to regional variations in crustal structure. From these results, we infer the presence and distribution of fluids released from the subducting slab and how they affect the seismic structure of the overriding lithosphere. In the Klamath and Wrangelia zones, high seismicity rates in the subducting plate and high tremor density correlate with low shear velocities in the overriding plate's forearc and relatively little arc volcanism. While the cause of tremor is debated, intermediate depth earthquakes are generally thought to be due to metamorphic dehydration reactions resulting from the dewatering of the downgoing slab. Thus, the seismic characteristics of these zones combined with rather sparse arc volcanism may indicate that the slab has largely dewatered by the time it reaches sub-arc depths. Some of the water released during earthquakes (and possibly tremor) may percolate into the overriding plate, leading to slow seismic velocities in the forearc. In contrast, Siletzia shows relatively low seismicity rates and tremor density, with relatively higher shear velocities in the forearc

  20. Modelling ground deformation patterns associated with volcanic processes at the Okataina Volcanic Centre

    Science.gov (United States)

    Holden, L.; Cas, R.; Fournier, N.; Ailleres, L.

    2017-09-01

    The Okataina Volcanic Centre (OVC) is one of two large active rhyolite centres in the modern Taupo Volcanic Zone (TVZ) in the North Island of New Zealand. It is located in a complex section of the Taupo rift, a tectonically active section of the TVZ. The most recent volcanic unrest at the OVC includes the 1315 CE Kaharoa and 1886 Tarawera eruptions. Current monitoring activity at the OVC includes the use of continuous GPS receivers (cGPS), lake levelling and seismographs. The ground deformation patterns preceding volcanic activity the OVC are poorly constrained and restricted to predictions from basic modelling and comparison to other volcanoes worldwide. A better understanding of the deformation patterns preceding renewed volcanic activity is essential to determine if observed deformation is related to volcanic, tectonic or hydrothermal processes. Such an understanding also means that the ability of the present day cGPS network to detect these deformation patterns can also be assessed. The research presented here uses the finite element (FE) modelling technique to investigate ground deformation patterns associated with magma accumulation and diking processes at the OVC in greater detail. A number of FE models are produced and tested using Pylith software and incorporate characteristics of the 1315 CE Kaharoa and 1886 Tarawera eruptions, summarised from the existing body of research literature. The influence of a simple ring fault structure at the OVC on the modelled deformation is evaluated. The ability of the present-day continuous GPS (cGPS) GeoNet monitoring network to detect or observe the modelled deformation is also considered. The results show the modelled horizontal and vertical displacement fields have a number of key features, which include prominent lobe based regions extending northwest and southeast of the OVC. The results also show that the ring fault structure increases the magnitude of the displacements inside the caldera, in particular in the

  1. Laboratory simulations of volcanic ash charging and conditions for volcanic lightning on Venus

    Science.gov (United States)

    Airey, Martin; Warriner-Bacon, Elliot; Aplin, Karen

    2017-04-01

    Lightning may be important in the emergence of life on Earth and elsewhere, as significant chemical reactions occur in the superheated region around the lightning channel. This, combined with the availability of phosphates in volcanic clouds, suggests that volcanic lightning could have been the catalyst for the formation of biological compounds on the early Earth [1]. In addition to meteorological lightning, volcanic activity also generates electrical discharges within charged ash plumes, which can be a significant contributor to atmospheric electricity on geologically active planets. The physical properties of other planetary atmospheres, such as that of Venus, have an effect on the processes that lead to the generation of volcanic lightning. Volcanism is known to have occurred on Venus in the past, and recent observations made by ESA's Venus Express satellite have provided evidence for currently active volcanism [2-4], and lightning discharges [e.g. 5]. Venusian lightning could potentially be volcanic in origin, since no meteorological mechanisms are known to separate charge effectively in its clouds [6]. The hunt for further evidence for lightning at Venus is ongoing, for example by means of the Lightning and Airglow Camera (LAC) [7] on Akatsuki, the current JAXA mission at Venus. Our laboratory experiments simulate ash generation and measure electrical charging of the ash under typical atmospheric conditions on Earth and Venus. The study uses a 1 litre chamber, which, when pressurised and heated, can simulate the high-pressure, high-temperature, carbon dioxide-dominated atmosphere of Venus at 10 km altitude ( 5 MPa, 650 K). A key finding of previous work [8] is that ash plume-forming eruptions are more likely to occur at higher altitudes such as these on Venus. The chamber contains temperature/pressure monitoring and logging equipment, a rock collision apparatus (based on [9]) to generate the charged rock fragments, and charge measurement electrodes connected

  2. Rangitoto Volcano Drilling Project: Life of a Small 'Monogenetic' Basaltic Shield in the Auckland Volcanic Field

    Science.gov (United States)

    Shane, P. A. R.; Linnell, T.; Lindsay, J. M.; Smith, I. E.; Augustinus, P. M.; Cronin, S. J.

    2014-12-01

    Rangitoto is a small basaltic shield volcano representing the most recent and most voluminous episode of volcanism in the Auckland Volcanic Field, New Zealand. Auckland City is built on the field, and hence, Rangitoto's importance in hazard-risk modelling. The symmetrical edifice, ~6 km wide and 260 m high, has volume of 1.78 km3. It comprises summit scoria cones and a lava field. However, the lack of deep erosion dissection has prevented the development of an eruptive stratigraphy. Previous studies suggested construction in a relatively short interval at 550-500 yrs BP. However, microscopic tephra have been interpreted as evidence of intermittent activity from 1498 +/- 140 to 504 +/- 6 yrs BP, a longevity of 1000 years. A 150-m-deep hole was drilled through the edifice in February 2014 to obtain a continuous core record. The result is an unparalleled stratigraphy of the evolution of a small shield volcano. The upper 128 m of core comprises at least 27 lava flows with thicknesses in the range 0.3-15 m, representing the main shield-building phase. Underlying marine sediments are interbedded with 8 m of pyroclastic lapilli, and a thin lava flow, representing the explosive phreatomagmatic birth of the volcano. Preliminary geochemical analyses reveal suite of relatively uniform transitional basalts (MgO = 8.1 to 9.7 wt %). However, 4 compositional groups are distinguished that were erupted in sequential order. High-MgO magmas were erupted first, followed by a two more heterogeneous groups displaying differentiation trends with time. Finally, distinct low-MgO basalts were erupted. Each magma type appears to represent a new magma batch. The core places the magma types in a time series, which can be correlated to the surface lava field. Hence, allowing a geometrical reconstruction of the shield growth. Additional petrologic investigations are providing insight to magmatic ascent processes, while radiocarbon and paleomagnetic secular variation studies will reveal the

  3. The shape of Vesuvius before the 79 A.D. eruption according to a new finding from a Pompei fresco and Vesuvius central cone history in the las 2000 years

    Energy Technology Data Exchange (ETDEWEB)

    Nazzaro, A. [Osservatorio Vesuviano, Ercolano, NA (Italy)

    1999-08-01

    The history of Vesuvius and its central cone or Great Cone (Gran Cono) is important because it enables to improve our understanding of the structural evolution of Somma-Vesuvius. Apart of geological and stratigraphic studies, investigations of literary and artistic testimonies can also help to clarify some unresolved problems. Recently a detailed study of the consequences of the 1631 eruption on the volcano morphology as well as that of the following the volcanic activity has shown that the present central cone was formed in the last few centuries after that eruption. With regard to the history of the central cone prior to the 1631 eruption, rare writing and iconographic records help clarify this question. In this short communication we announce the discovery of a new image representing Vesuvius before the 79 A.D. eruption identified in a fresco from Pompei excavations. This fresco could confirm the interpretation of a well-known Strabo quotation according to which there already existed a large caldera prior to the 79 A.D. eruption.

  4. Actinobacterial diversity in volcanic caves and associated geomicrobiological interactions

    Directory of Open Access Journals (Sweden)

    Cristina eRiquelme

    2015-12-01

    Full Text Available Volcanic caves are filled with colorful microbial mats on the walls and ceilings. These volcanic caves are found worldwide, and studies are finding vast bacteria diversity within these caves. One group of bacteria that can be abundant in volcanic caves, as well as other caves, is Actinobacteria. As Actinobacteria are valued for their ability to produce a variety of secondary metabolites, rare and novel Actinobacteria are being sought in underexplored environments. The abundance of novel Actinobacteria in volcanic caves makes this environment an excellent location to study these bacteria. Scanning electron microscopy (SEM from several volcanic caves worldwide revealed diversity in the morphologies present. Spores, coccoid and filamentous cells, many with hair-like or knobby extensions, were some of the microbial structures observed within the microbial mat samples. In addition, the SEM study pointed out that these features figure prominently in both constructive and destructive mineral processes. To further investigate this diversity, we conducted both Sanger sequencing and 454 pyrosequencing of the Actinobacteria in volcanic caves from four locations, two islands in the Azores, Portugal and Hawai`i and New Mexico, USA. This comparison represents one of the largest sequencing efforts of Actinobacteria in volcanic caves to date. The diversity was shown to be dominated by Actinomycetales, but also included several newly described orders, such as Euzebyales, and Gaiellales. Sixty-two percent of the clones from the four locations shared less than 97% similarity to known sequences, and nearly 71% of the clones were singletons, supporting the commonly held belief that volcanic caves are an untapped resource for novel and rare Actinobacteria. The amplicon libraries depicted a wider view of the microbial diversity in Azorean volcanic caves revealing three additional orders, Rubrobacterales, Solirubrobacterales and Coriobacteriales. Studies of microbial

  5. Actinobacterial Diversity in Volcanic Caves and Associated Geomicrobiological Interactions.

    Science.gov (United States)

    Riquelme, Cristina; Marshall Hathaway, Jennifer J; Enes Dapkevicius, Maria de L N; Miller, Ana Z; Kooser, Ara; Northup, Diana E; Jurado, Valme; Fernandez, Octavio; Saiz-Jimenez, Cesareo; Cheeptham, Naowarat

    2015-01-01

    Volcanic caves are filled with colorful microbial mats on the walls and ceilings. These volcanic caves are found worldwide, and studies are finding vast bacteria diversity within these caves. One group of bacteria that can be abundant in volcanic caves, as well as other caves, is Actinobacteria. As Actinobacteria are valued for their ability to produce a variety of secondary metabolites, rare and novel Actinobacteria are being sought in underexplored environments. The abundance of novel Actinobacteria in volcanic caves makes this environment an excellent location to study these bacteria. Scanning electron microscopy (SEM) from several volcanic caves worldwide revealed diversity in the morphologies present. Spores, coccoid, and filamentous cells, many with hair-like or knobby extensions, were some of the microbial structures observed within the microbial mat samples. In addition, the SEM study pointed out that these features figure prominently in both constructive and destructive mineral processes. To further investigate this diversity, we conducted both Sanger sequencing and 454 pyrosequencing of the Actinobacteria in volcanic caves from four locations, two islands in the Azores, Portugal, and Hawai'i and New Mexico, USA. This comparison represents one of the largest sequencing efforts of Actinobacteria in volcanic caves to date. The diversity was shown to be dominated by Actinomycetales, but also included several newly described orders, such as Euzebyales, and Gaiellales. Sixty-two percent of the clones from the four locations shared less than 97% similarity to known sequences, and nearly 71% of the clones were singletons, supporting the commonly held belief that volcanic caves are an untapped resource for novel and rare Actinobacteria. The amplicon libraries depicted a wider view of the microbial diversity in Azorean volcanic caves revealing three additional orders, Rubrobacterales, Solirubrobacterales, and Coriobacteriales. Studies of microbial ecology in

  6. VOLCANIC TSUNAMI GENERATING SOURCE MECHANISMS IN THE EASTERN CARIBBEAN REGION

    Directory of Open Access Journals (Sweden)

    George Pararas-Carayannis

    2004-01-01

    Full Text Available Earthquakes, volcanic eruptions, volcanic island flank failures and underwater slides have generated numerous destructive tsunamis in the Caribbean region. Convergent, compressional and collisional tectonic activity caused primarily from the eastward movement of the Caribbean Plate in relation to the North American, Atlantic and South American Plates, is responsible for zones of subduction in the region, the formation of island arcs and the evolution of particular volcanic centers on the overlying plate. The inter-plate tectonic interaction and deformation along these marginal boundaries result in moderate seismic and volcanic events that can generate tsunamis by a number of different mechanisms. The active geo-dynamic processes have created the Lesser Antilles, an arc of small islands with volcanoes characterized by both effusive and explosive activity. Eruption mechanisms of these Caribbean volcanoes are complex and often anomalous. Collapses of lava domes often precede major eruptions, which may vary in intensity from Strombolian to Plinian. Locally catastrophic, short-period tsunami-like waves can be generated directly by lateral, direct or channelized volcanic blast episodes, or in combination with collateral air pressure perturbations, nuéss ardentes, pyroclastic flows, lahars, or cascading debris avalanches. Submarine volcanic caldera collapses can also generate locally destructive tsunami waves. Volcanoes in the Eastern Caribbean Region have unstable flanks. Destructive local tsunamis may be generated from aerial and submarine volcanic edifice mass edifice flank failures, which may be triggered by volcanic episodes, lava dome collapses, or simply by gravitational instabilities. The present report evaluates volcanic mechanisms, resulting flank failure processes and their potential for tsunami generation. More specifically, the report evaluates recent volcanic eruption mechanisms of the Soufriere Hills volcano on Montserrat, of Mt. Pel

  7. Méthode analytique généralisée pour le calcul du coning. Nouvelle solution pour calculer le coning de gaz, d'eau et double coning dans les puits verticaux et horizontaux Generalized Analytical Method for Coning Calculation. New Solution to Calculation Both the Gas Coning, Water Coning and Dual Coning for Vertical and Horizontal Wells

    Directory of Open Access Journals (Sweden)

    Pietraru V.

    2006-11-01

    Full Text Available Une nouvelle méthode analytique d'évaluation du coning d'eau par bottom water drive et/ou de gaz par gas-cap drive dans les puits horizontaux et verticaux a été développée pour les réservoirs infinis [1]. Dans cet article, une généralisation de cette méthode est présentée pour les réservoirs confinés d'extension limitée dont le toit est horizontal. La généralisation proposée est basée sur la résolution des équations différentielles de la diffusivité avec prise en compte des effets de drainage par gravité et des conditions aux limites pour un réservoir confiné. La méthode est applicable aux réservoirs isotropes ou anisotropes. L'hypothèse de pression constante à la limite de l'aire de drainage dans l'eau et/ou dans le gaz a été adoptée. Les pertes de charge dans l'aquifère et dans le gas-cap sont donc négligées. Les principales contributions de cet article sont : - L'introduction de la notion de rayon de cône, différent du rayon de puits. La hauteur du cône et le débit critique dépendent du rayon de cône alors qu'ils sont indépendants du rayon du puits. - Une nouvelle corrélation pour le calcul du débit critique sous forme adimensionnelle en fonction de trois paramètres : le temps, la longueur du drain horizontal (nulle pour un puits vertical et le rayon de drainage. - Des corrélations pour le calcul du rapport des débits gaz/huile (GOR ou de la fraction en eau (fw, pendant les périodes critique et postcritique, qui tiennent compte de la pression capillaire et des perméabilités relatives. - Des corrélations pour le calcul des rapports de débits gaz/huile et eau/huile pendant les périodes pré, post et supercritique en double coning. - Des critères pour le calcul du temps de percée au puits en simple coning de gaz ou d'eau, ou en double coning de gaz et d'eau. A new analytical method for assessing water and/or gas coning in horizontal and vertical wells has been developed for infinite

  8. Isotope and trace element systematics in a spinel-lherzolite-bearing suite of basanitic volcanic rocks from San Luis Potosi, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Pier, J.E.G.

    1989-01-01

    Lherzolite-bearing basanitic magmas of Quaternary age have erupted to form maars, lava/cinder cones and lava flows in two volcanic fields (Ventura and Santo Domingo) in the central Mexican state of San Luis Potosi. The systematics of the radiogenic isotopes of Sr, Nd, and Pb and the relationship between these parameters and elemental compositions are used to investigate the petrogenesis of the volcanic rocks and the nature of their mantle sources. Sr and Nd isotopic data are presented for 19 basanitic rocks, 5 kaersutites, and 6 lherzolitic xenoliths; Pb data presented for the same 19 volcanic rocks and 4 of the 5 kaersutites. The isotopic compositions for all of these samples fall within the mantle range defined by MORBs and OIBs. The basanites generally plot within the OIB field on isotopic diagrams; most of the kaersutites are displaced to slightly more-depleted (i.e. MORB-like) values than the volcanic samples and the xenoliths, with one exception, are significantly more-depleted than either of these sample-types. As crustal contamination is considered unlikely for most of the volcanic samples, these trends are thought to arise from mixing multiple mantle components. The absence of similar isotopic elemental relationships for Epsilon Nd and the lack of correlation between {sup 206}Pb/{sup 204}Pb and the other Pb isotopes require a mixture of at least three mantle reservoirs: a depleted reservoir analogous to that of the MORBs, a St. Helena-type component, and a third component, which primarily affects Sr and {sup 208}Pb/{sup 204}Pb composition. This third component carries relatively radiogenic Sr and {sup 208}Pb/{sup 204}Pb and appears to be correlated with the degree of melting.

  9. A volcanic district between the Hoggar uplift and the Tenere Rifts: Volcanology, geochemistry and age of the In-Ezzane lavas (Algerian Sahara)

    Science.gov (United States)

    Yahiaoui, Rachid; Dautria, Jean-Marie; Alard, Olivier; Bosch, Delphine; Azzouni-Sekkal, Abla; Bodinier, Jean-Louis

    2014-04-01

    The In-Ezzane volcanic district (EZD), located at the triple junction of Algeria, Niger and Libya belongs to the Eastern Hoggar, covers 350 km2 and includes 9 volcanic edifices that are probably aligned along NW-SE faults, parallel to the Tafassasset valley. The low volume (0.7 and 1 km3) of emitted lavas, the similar morphology of the monogenic cones and the lack of differentiated rocks indicate that the volcanic activity of the EZD was restricted in time and volume. The new K-Ar age (i.e. 2.86 ± 0.07 Ma) indicates that the EZD is contemporaneous with the last alkali volcanism paroxysm in Hoggar and with the nearby Libyan volcanics. The EZD alkali basalts (mainly basanite) show a remarkable homogeneous compositions both in major elements (44.8 ⩽ SiO2 ⩽ 45.8 wt.%; 5.2 ⩽ (Na2O + K2O) ⩽ 6.2 wt.%), trace elements (4.3 ⩽ Th ⩽ 5.5 ppm; 34.7 ⩽ La ⩽ 44.7 ppm; 16.1 < La/Yb(N) < 21.6) and radiogenic isotopes (0.70285 < 87Sr/86Sr < 0.70303; 0.51298 < 143Nd/144Nd < 0.51301; (19.212 < 206Pb/204Pb < 19.340, 15.589 < 207Pb/204Pb < 15.602 and 38.834 < 208Pb/204Pb < 38.903). Relative to the Hoggar alkaly basalts the EZD basalts appear systematically impoverished in incompatible elements and show a depleted signature both in Sr and Nd isotopes (almost MORB-like). The Pb isotopes are relatively enriched and intermediate between tholeiites and alkali basalts of the Hoggar. This unusual geochemical signature, is uneasy to reconcile with the known characteristics of the Hoggar swell, and would rather fingerprint a circum cratonic mantle lying beneath the west border of the Murzuq craton (Libya).

  10. Petrologic evaluation of Pliocene basaltic volcanism in Eastern Anatolian region, Turkey: Evidence for mixing of melts derived from both shallow and deep mantle sources

    Science.gov (United States)

    Oyan, Vural; Özdemir, Yavuz; Keskin, Mehmet; Güleç, Nilgün

    2017-04-01

    Collision-related Neogene volcanism in the Eastern Anatolia region (EAR) began after the continent-continent collision between the Arabia and the Eurasia plates, and spreads in a wide zone from the Erzurum-Kars Plateau in the northeast to the Karacadaǧ in the south. Volcanic activity in the EAR started 15 Ma ago (Middle Miocene) in the south of the region. Voluminous basaltic lavas from local eruption centers formed basaltic lava plateaus and volcanic cones as a result of high production level of volcanism during the Pliocene time interval. Our dating results (Ar-Ar and K-Ar) indicate that age of this Late Miocene-Pliocene magmatic activity range between 6 and 3.5 Ma. Volcanic products contain alkaline and subalkaline lavas, ranging in composition from basalts to andesites and trachyandesites. Our EC-AFC and AFC modeling, based on trace element and Sr, Nd, Pb isotopic compositions, suggests about 2-7 % crustal contamination in the evolved andesites and trachyandesites. MORB and primitive mantle normalized patterns of the lavas and isotopic compositions imply that alkaline and subalkaline basalts erupted in Pliocene time interval in the EAR could have been derived from a mantle source that had previously been enriched by a clear subduction component. A partial melting model was conducted to evaluate partial melting processes in the mantle source of the Pliocene basalts. Our melting model calculations suggest that basaltic melts in the EAR could have been produced by melting of mantle sources containing spinel, garnet and amphibole with melting degree in the range of 0.7-7%. The products of mixing of these derivative melts are the Pliocene basaltic lavas of the Eastern Anatolian Region.

  11. Explosive mafic volcanism on Earth and Mars

    Science.gov (United States)

    Gregg, Tracy K. P.; Williams, Stanley N.

    1993-01-01

    Deposits within Amazonia Planitia, Mars, have been interpreted as ignimbrite plains on the basis of their erosional characteristics. The western flank of Hecates Tholus appears to be mantled by an airfall deposit, which was produced through magma-water interactions or exsolution of magmatic volatiles. Morphologic studies, along with numerical and analytical modeling of Martian plinian columns and pyroclastic flows, suggest that shield materials of Tyrrhena and Hadriaca paterae are composed of welded pyroclastic flows. Terrestrial pyroclastic flows, ignimbrites, and airfall deposits are typically associated with silicic volcanism. Because it is unlikely that large volumes of silicic lavas have been produced on Mars, we seek terrestrial analogs of explosives, mafic volcanism. Plinian basaltic airfall deposits have been well-documented at Masaya, Nicaragua, and basaltic ignimbrite and surge deposits also have been recognized there. Ambrym and Yasour, both in Vanuatu, are mafic stratovolcanioes with large central calderas, and are composed of interbedded basaltic pyrocalstic deposits and lava flows. Zavaritzki, a mafic stratovolcano in the Kurile Islands, may have also produced pyroclastic deposits, although the exact nature of these deposits in unknown. Masaya, Ambrym and Yasour are known to be located above tensional zones. Hadriaca and Tyrrhena Paterae may also be located above zones of tension, resulting from the formation and evolution of Hellas basin, and, thus, may be directly analogous to these terrestrial mafic, explosive volcanoes.

  12. Mantle updrafts and mechanisms of oceanic volcanism

    Science.gov (United States)

    Anderson, Don L.; Natland, James H.

    2014-10-01

    Convection in an isolated planet is characterized by narrow downwellings and broad updrafts-consequences of Archimedes' principle, the cooling required by the second law of thermodynamics, and the effect of compression on material properties. A mature cooling planet with a conductive low-viscosity core develops a thick insulating surface boundary layer with a thermal maximum, a subadiabatic interior, and a cooling highly conductive but thin boundary layer above the core. Parts of the surface layer sink into the interior, displacing older, colder material, which is entrained by spreading ridges. Magma characteristics of intraplate volcanoes are derived from within the upper boundary layer. Upper mantle features revealed by seismic tomography and that are apparently related to surface volcanoes are intrinsically broad and are not due to unresolved narrow jets. Their morphology, aspect ratio, inferred ascent rate, and temperature show that they are passively responding to downward fluxes, as appropriate for a cooling planet that is losing more heat through its surface than is being provided from its core or from radioactive heating. Response to doward flux is the inverse of the heat-pipe/mantle-plume mode of planetary cooling. Shear-driven melt extraction from the surface boundary layer explains volcanic provinces such as Yellowstone, Hawaii, and Samoa. Passive upwellings from deeper in the upper mantle feed ridges and near-ridge hotspots, and others interact with the sheared and metasomatized surface layer. Normal plate tectonic processes are responsible both for plate boundary and intraplate swells and volcanism.

  13. Mantle updrafts and mechanisms of oceanic volcanism.

    Science.gov (United States)

    Anderson, Don L; Natland, James H

    2014-10-14

    Convection in an isolated planet is characterized by narrow downwellings and broad updrafts--consequences of Archimedes' principle, the cooling required by the second law of thermodynamics, and the effect of compression on material properties. A mature cooling planet with a conductive low-viscosity core develops a thick insulating surface boundary layer with a thermal maximum, a subadiabatic interior, and a cooling highly conductive but thin boundary layer above the core. Parts of the surface layer sink into the interior, displacing older, colder material, which is entrained by spreading ridges. Magma characteristics of intraplate volcanoes are derived from within the upper boundary layer. Upper mantle features revealed by seismic tomography and that are apparently related to surface volcanoes are intrinsically broad and are not due to unresolved narrow jets. Their morphology, aspect ratio, inferred ascent rate, and temperature show that they are passively responding to downward fluxes, as appropriate for a cooling planet that is losing more heat through its surface than is being provided from its core or from radioactive heating. Response to doward flux is the inverse of the heat-pipe/mantle-plume mode of planetary cooling. Shear-driven melt extraction from the surface boundary layer explains volcanic provinces such as Yellowstone, Hawaii, and Samoa. Passive upwellings from deeper in the upper mantle feed ridges and near-ridge hotspots, and others interact with the sheared and metasomatized surface layer. Normal plate tectonic processes are responsible both for plate boundary and intraplate swells and volcanism.

  14. Reduced cooling following future volcanic eruptions

    Science.gov (United States)

    Hopcroft, Peter O.; Kandlbauer, Jessy; Valdes, Paul J.; Sparks, R. Stephen J.

    2017-11-01

    Volcanic eruptions are an important influence on decadal to centennial climate variability. Large eruptions lead to the formation of a stratospheric sulphate aerosol layer which can cause short-term global cooling. This response is modulated by feedback processes in the earth system, but the influence from future warming has not been assessed before. Using earth system model simulations we find that the eruption-induced cooling is significantly weaker in the future state. This is predominantly due to an increase in planetary albedo caused by increased tropospheric aerosol loading with a contribution from associated changes in cloud properties. The increased albedo of the troposphere reduces the effective volcanic aerosol radiative forcing. Reduced sea-ice coverage and hence feedbacks also contribute over high-latitudes, and an enhanced winter warming signal emerges in the future eruption ensemble. These findings show that the eruption response is a complex function of the environmental conditions, which has implications for the role of eruptions in climate variability in the future and potentially in the past.

  15. Volcanic Activity at Tvashtar Catena, Io

    Science.gov (United States)

    Milazzo, M. P.; Keszthelyi, L. P.; Radebaugh, J.; Davies, A. G.; McEwen, A. S.

    2004-01-01

    Tvashtar Catena (63 N, 120 W) is one of the most interesting features on Io. This chain of large paterae (caldera-like depressions) has exhibited highly variable volcanic activity in a series of observations. Tvashtar is the type example of a style of volcanism seen only at high latitudes, with short-lived Pele-type plumes and short-lived by intense thermal events. Evidence for a hot spot at Tvashtar was first detected in an eclipse observation in April 1997 (orbit G7) by the Solid State Imager (SSI) on the Galileo Spacecraft. Tvashtar was originally targeted for observation at higher resolution in the close flyby in November 1999 (I25) because of its interesting large-scale topography. There are relatively few but generally larger paterae at high latitudes on Io. I25 images revealed a 25 km long, 1-2 km high lava curtain via a pattern of saturation and bleeding in the CCD image, which requires very high temperatures.

  16. Polymagmatic Activity at a Monogenetic Volcanic Centre: Defining the Evolution of a Plumbing System

    Science.gov (United States)

    Brenna, M.; Cronin, S. J.; Smith, I. E.; Sohn, Y.; Nemeth, K.

    2009-12-01

    Detailed stratigraphic samples of the Udo Tuff Cone and lava shield offshore of Jeju Island, South Korea provide insight into the evolutionary processes that affected the composition of the basaltic magma batches that fed the eruption. These are compared and contrasted with the model proposed by Smith et al. (2008, Contributions to Mineralogy and Petrology 155, 511-527) for the magmatic evolution of the Crater Hill monogenetic centre in the Auckland Volcanic Field. The eruption started in both cases with the most evolved alkalic magma, having lowest concentrations of MgO and highest of incompatible trace elements. The erupted magma became more primitive as the eruptions proceeded. However, at Crater Hill the eruption terminated with extrusion of the most primitive magma, whereas at Udo the last magma to erupt had shifted back to an intermediate composition. At Crater Hill, the chemical compositions show a single uninterrupted spectrum, but at Udo the eruption sequence can be subdivided into lower and upper tuff stages separated by a small MgO gap from c. 8.0 to c. 9.0 wt%. Furthermore, at Udo, a second tholeiitic magma batch forming the lava shield erupted shortly after the alkalic tuff cone, with no evidence of weathering or reworked material at their contact. Fractionation processes for the Udo tuff can be modelled similarly to those of Crater Hill. A primary magma generated in garnet peridotite at c. 2.5 to 3 GPa underwent mainly clinopyroxene ± spinel fractionation at c. 1.5 GPa. Slightly enriched LREEs in the Udo magma (compared to the Crater Hill) suggest that crystal fractionation possibly occurred in the presence of residual amphibole in the upper mantle. The tholeiitic magma at Udo was generated in a chemically different source with residual garnet at c. 1.5 to 2.5 GPa and evolved through olivine fractionation at a shallower level compared to the alkalic magma and without residual amphibole. The Crater Hill model can be adapted to Udo by assuming the two

  17. Elovl4 5-bp deletion does not accelerate cone photoreceptor degeneration in an all-cone mouse.

    Directory of Open Access Journals (Sweden)

    Christian Schori

    Full Text Available Mutations in the elongation of very long chain fatty acid 4 (ELOVL4 gene cause Stargardt macular dystrophy 3 (STGD3, a rare, juvenile-onset, autosomal dominant form of macular degeneration. Although several mouse models have already been generated to investigate the link between the three identified disease-causing mutations in the ELOVL4 gene, none of these models recapitulates the early-onset cone photoreceptor cell death observed in the macula of STGD3 patients. To address this specifically, we investigated the effect of mutant ELOVL4 in a mouse model with an all-cone retina. Hence, we bred mice carrying the heterozygously mutated Elovl4 gene on the R91W;Nrl-/- all-cone background and analyzed the retinal lipid composition, morphology, and function over the course of 1 year. We observed a reduction of total phosphatidylcholine-containing very long chain-polyunsaturated fatty acids (PC-VLC-PUFAs by 39% in the R91W;Nrl-/-;Elovl4 mice already at 6 weeks of age with a pronounced decline of the longest forms of PC-VLC-PUFAs. Total levels of shorter-chain fatty acids (< C26 remained unaffected. However, this reduction in PC-VLC-PUFA content in the all-cone retina had no impact on morphology or function and did not accelerate retinal degeneration in the R91W;Nrl-/-;Elovl4 mice. Taken together, mutations in the ELOVL4 gene lead to cone degeneration in humans, whereas mouse models expressing the mutant Elovl4 show predominant rod degeneration. The lack of a phenotype in the all-cone retina expressing the mutant form of the protein supports the view that aberrant function of ELOVL4 is especially detrimental for rods in mice and suggests a more subtle role of VLC-PUFAs for cone maintenance and survival.

  18. Pollen cone anatomy of Classostrobus crossii sp. nov. (Cheirolepidiaceae)

    Energy Technology Data Exchange (ETDEWEB)

    Rothwell, Gar W.; Mapes, Gene [Department of Environmental and Plant Biology, Ohio University, Athens OH 45701 (United States); Hilton, Jason [Department of Earth Sciences, School of Geography, Earth and Environmental Sciences, The University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom); Hollingworth, Neville T. [Centre for Ecology and Hydrology, Winfrith Technology Centre, Winfrith Newburgh, Dorchester, Dorset, DT2 8ZD (United Kingdom)

    2007-01-02

    Discovery of a permineralized fossil cone in Mesozoic deposits of southern England provides an opportunity to document the first detailed evidence of internal pollen cone anatomy for the extinct conifer family Cheirolepidiaceae. The specimen, described here as Classostrobus crossii sp. nov., occurs in a calcareous nodule recovered from Middle Jurassic marine sediments of the Lower Callovian Sigaloceras calloviense biozone, Kellaways, near Cirencester, England. The cone is 2.0 cm long and 1.8 cm wide. Sporophylls diverge helically from the axis. Each sporophyll displays a narrow stalk and a distal lamina approx. 11 mm long that tapers to a pointed tip. There is also a basal keel that bends inward at the bottom and sides to form a shallow pocket. A single vascular bundle diverges from the cone axis, extends distally into the sporophyll stalk at the contact of two distinctly different histological zones, and further expands into the distal lamina as transfusion tracheids. Several pollen sacs are attached abaxially at the juncture of the sporophyll stalk and keel. Pollen is roughly spheroidal, 26-35 {mu}m in diameter, with unequal polar caps separated by a striated belt with a subequatorial furrow. This specimen helps clarify the range of variation in the morphology of Mesozoic conifer pollen cones. (author)

  19. Venomics-Accelerated Cone Snail Venom Peptide Discovery.

    Science.gov (United States)

    Himaya, S W A; Lewis, Richard J

    2018-03-09

    Cone snail venoms are considered a treasure trove of bioactive peptides. Despite over 800 species of cone snails being known, each producing over 1000 venom peptides, only about 150 unique venom peptides are structurally and functionally characterized. To overcome the limitations of the traditional low-throughput bio-discovery approaches, multi-omics systems approaches have been introduced to accelerate venom peptide discovery and characterisation. This "venomic" approach is starting to unravel the full complexity of cone snail venoms and to provide new insights into their biology and evolution. The main challenge for venomics is the effective integration of transcriptomics, proteomics, and pharmacological data and the efficient analysis of big datasets. Novel database search tools and visualisation techniques are now being introduced that facilitate data exploration, with ongoing advances in related omics fields being expected to further enhance venomics studies. Despite these challenges and future opportunities, cone snail venomics has already exponentially expanded the number of novel venom peptide sequences identified from the species investigated, although most novel conotoxins remain to be pharmacologically characterised. Therefore, efficient high-throughput peptide production systems and/or banks of miniaturized discovery assays are required to overcome this bottleneck and thus enhance cone snail venom bioprospecting and accelerate the identification of novel drug leads.

  20. Generalized Fourier slice theorem for cone-beam image reconstruction.

    Science.gov (United States)

    Zhao, Shuang-Ren; Jiang, Dazong; Yang, Kevin; Yang, Kang

    2015-01-01

    The cone-beam reconstruction theory has been proposed by Kirillov in 1961, Tuy in 1983, Feldkamp in 1984, Smith in 1985, Pierre Grangeat in 1990. The Fourier slice theorem is proposed by Bracewell 1956, which leads to the Fourier image reconstruction method for parallel-beam geometry. The Fourier slice theorem is extended to fan-beam geometry by Zhao in 1993 and 1995. By combining the above mentioned cone-beam image reconstruction theory and the above mentioned Fourier slice theory of fan-beam geometry, the Fourier slice theorem in cone-beam geometry is proposed by Zhao 1995 in short conference publication. This article offers the details of the derivation and implementation of this Fourier slice theorem for cone-beam geometry. Especially the problem of the reconstruction from Fourier domain has been overcome, which is that the value of in the origin of Fourier space is 0/0. The 0/0 type of limit is proper handled. As examples, the implementation results for the single circle and two perpendicular circle source orbits are shown. In the cone-beam reconstruction if a interpolation process is considered, the number of the calculations for the generalized Fourier slice theorem algorithm is O(N^4), which is close to the filtered back-projection method, here N is the image size of 1-dimension. However the interpolation process can be avoid, in that case the number of the calculations is O(N5).

  1. The photocurrent response of human cones is fast and monophasic

    Directory of Open Access Journals (Sweden)

    Lamb TD

    2006-04-01

    Full Text Available Abstract Background The precise form of the light response of human cone photoreceptors in vivo has not been established with certainty. To investigate the response shape we compare the predictions of a recent model of transduction in primate cone photoreceptors with measurements extracted from human cones using the paired-flash electroretinogram method. As a check, we also compare the predictions with previous single-cell measurements of ground squirrel cone responses. Results The predictions of the model provide a good description of the measurements, using values of parameters within the range previously determined for primate retina. The dim-flash response peaks in about 20 ms, and flash responses at all intensities are essentially monophasic. Three time constants in the model are extremely short: the two time constants for inactivation (of visual pigment and of transducin/phosphodiesterase are around 3 and 10 ms, and the time constant for calcium equilibration lies in the same range. Conclusion The close correspondence between experiment and theory, using parameters previously derived for recordings from macaque retina, supports the notion that the electroretinogram approach and the modelling approach both provide an accurate estimate of the cone photoresponse in the living human eye. For reasons that remain unclear, the responses of isolated photoreceptors from the macaque retina, recorded previously using the suction pipette method, are considerably slower than found here, and display biphasic kinetics.

  2. Venomics-Accelerated Cone Snail Venom Peptide Discovery

    Science.gov (United States)

    Himaya, S. W. A.

    2018-01-01

    Cone snail venoms are considered a treasure trove of bioactive peptides. Despite over 800 species of cone snails being known, each producing over 1000 venom peptides, only about 150 unique venom peptides are structurally and functionally characterized. To overcome the limitations of the traditional low-throughput bio-discovery approaches, multi-omics systems approaches have been introduced to accelerate venom peptide discovery and characterisation. This “venomic” approach is starting to unravel the full complexity of cone snail venoms and to provide new insights into their biology and evolution. The main challenge for venomics is the effective integration of transcriptomics, proteomics, and pharmacological data and the efficient analysis of big datasets. Novel database search tools and visualisation techniques are now being introduced that facilitate data exploration, with ongoing advances in related omics fields being expected to further enhance venomics studies. Despite these challenges and future opportunities, cone snail venomics has already exponentially expanded the number of novel venom peptide sequences identified from the species investigated, although most novel conotoxins remain to be pharmacologically characterised. Therefore, efficient high-throughput peptide production systems and/or banks of miniaturized discovery assays are required to overcome this bottleneck and thus enhance cone snail venom bioprospecting and accelerate the identification of novel drug leads. PMID:29522462

  3. Venomics-Accelerated Cone Snail Venom Peptide Discovery

    Directory of Open Access Journals (Sweden)

    S. W. A. Himaya

    2018-03-01

    Full Text Available Cone snail venoms are considered a treasure trove of bioactive peptides. Despite over 800 species of cone snails being known, each producing over 1000 venom peptides, only about 150 unique venom peptides are structurally and functionally characterized. To overcome the limitations of the traditional low-throughput bio-discovery approaches, multi-omics systems approaches have been introduced to accelerate venom peptide discovery and characterisation. This “venomic” approach is starting to unravel the full complexity of cone snail venoms and to provide new insights into their biology and evolution. The main challenge for venomics is the effective integration of transcriptomics, proteomics, and pharmacological data and the efficient analysis of big datasets. Novel database search tools and visualisation techniques are now being introduced that facilitate data exploration, with ongoing advances in related omics fields being expected to further enhance venomics studies. Despite these challenges and future opportunities, cone snail venomics has already exponentially expanded the number of novel venom peptide sequences identified from the species investigated, although most novel conotoxins remain to be pharmacologically characterised. Therefore, efficient high-throughput peptide production systems and/or banks of miniaturized discovery assays are required to overcome this bottleneck and thus enhance cone snail venom bioprospecting and accelerate the identification of novel drug leads.

  4. Large Scale Plasmonic nanoCones array For Spectroscopy Detection

    KAUST Repository

    Das, Gobind

    2015-09-24

    Advanced optical materials or interfaces are gaining attention for diagnostic applications. However, the achievement of large device interface as well as facile surface functionalization largely impairs their wide use. The present work is aimed to address different innovative aspects related to the fabrication of large area 3D plasmonic arrays, their direct and easy functionalization with capture elements and their spectroscopic verifications through enhanced Raman and enhanced fluorescence techniques. In detail we have investigated the effect of Au-based nanoCones array, fabricated by means of direct nanoimprint technique over large area (mm2), on protein capturing and on the enhancement in optical signal. A selective functionalization of gold surfaces was proposed by using a peptide (AuPi3) previously selected by phage display. In this regard, two different sequences, labeled with fluorescein and biotin, were chemisorbed on metallic surfaces. The presence of Au nanoCones array consents an enhancement in electric field on the apex of cone, enabling the detection of molecules. We have witnessed around 12-fold increase in fluorescence intensity and SERS enhancement factor around 1.75 ×105 with respect to the flat gold surface. Furthermore, a sharp decrease in fluorescence lifetime over nanoCones confirms the increase in radiative emission (i.e. an increase in photonics density at the apex of cones).

  5. Exact cone beam CT with a spiral scan

    International Nuclear Information System (INIS)

    Tam, K.C.; Samarasekera, S.; Sauer, F.

    1998-01-01

    A method is developed which makes it possible to scan and reconstruct an object with cone beam x-rays in a spiral scan path with area detectors much shorter than the length of the object. The method is mathematically exact. If only a region of interest of the object is to be imaged, a top circle scan at the top level of the region of interest and a bottom circle scan at the bottom level of the region of interest are added. The height of the detector is required to cover only the distance between adjacent turns in the spiral projected at the detector. To reconstruct the object, the Radon transform for each plane intersecting the object is computed from the totality of the cone beam data. This is achieved by suitably combining the cone beam data taken at different source positions on the scan path; the angular range of the cone beam data required at each source position can be determined easily with a mask which is the spiral scan path projected on the detector from the current source position. The spiral scan algorithm has been successfully validated with simulated cone beam data. (author)

  6. Spray cone angle and air core diameter of hollow cone swirl rocket injector

    Directory of Open Access Journals (Sweden)

    Ahmad Hussein Abdul Hamid

    2011-12-01

    Full Text Available ABSTRACT : Fuel injector for liquid rocket is a very critical component since that small difference in its design can dramatically affect the combustion efficiency. The primary function of the injector is to break the fuel up into very small droplets. The smaller droplets are necessary for fast quiet ignition and to establish a flame front close to the injector head, thus shorter combustion chamber is possible to be utilized. This paper presents an experimetal investigation of a mono-propellant hollow cone swirl injector. Several injectors with different configuration were investigated under cold flow test, where water is used as simulation fluid. This investigation reveals that higher injection pressure leads to higher spray cone angle. The effect of injection pressure on spray cone angle is more prominent for injector with least number of tangential ports. Furthermore, it was found that injector with the most number of tangential ports and with the smallest tangential port diameter produces the widest resulting spray. Experimental data also tells that the diameter of an air core that forms inside the swirl chamber is largest for the injector with smallest tangential port diameter and least number of tangential ports.ABSTRAK : Injektor bahan api bagi roket cecair merupakan satu komponen yang amat kritikal memandangkan perbezaan kecil dalam reka bentuknya akan secara langsung mempengaruhi kecekapan pembakaran. Fungsi utama injektor adalah untuk memecahkan bahan api kepada titisan yang amat kecil. Titisan kecil penting untuk pembakaran pantas secara senyap dan untuk mewujudkan satu nyalaan di hadapan, berhampiran dengan kepala injektor, maka kebuk pembakaran yang lebih pendek berkemungkinan dapat digunakan. Kertas kerja ini mebentangkan satu penyelidikan eksperimental sebuah injektor ekabahan dorong geronggang kon pusar. Beberapa injektor dengan konfigurasi berbeza telah dikaji di bawah ujian aliran sejuk, di mana air digunakan sebagai bendalir

  7. Waning Miocene subduction and arc volcanism in Baja California: the San Luis Gonzaga volcanic field

    Science.gov (United States)

    Martín, Arturo; Fletcher, John M.; López-Martínez, Margarita; Mendoza-Borunda, Ramón

    2000-03-01

    Subduction of the Guadalupe-Magdalena microplate beneath Baja California ended in the middle Miocene, and the last volcanic events in the frontal arc extinguished along the present-day eastern margin of the Baja California peninsula. The San Luis Gonzaga area in the north-central Gulf coast contains one of the younger arc-related volcanic centers in northern Baja California. The volcanic succession contains three sequences. The basal sequence (Group 1) is composed of stratified pyroclastic deposits, up to 500 m thick, and subordinate lava flows. The near-vent facies crop out in tilted fault blocks along the present shoreline, whereas the distal facies are exposed across ˜12 km toward the west and includes epiclastic deposits and at least three ash flow tuffs. This sequence is internally concordant and overlies smooth paleosurface developed on granitic basement, and pinches out across the Gulf escarpment. The Potrero Andesite (Group 2) is a series of dacite to basaltic-andesite lava flows from a shield volcano located ˜15 km west of today's coastline; similar source vents also occurs further south of the San Luis Gonzaga area. A sequence of dacite domes (Group 3) intrudes the near-vent facies of Group 1 and contains subordinate volcanic breccia and minor lava flows that overlie Group 1 sequence. Cross-cutting relationships and the abundance of volcanic breccia associated with the domes suggest that these domes were emplaced as semi-rigid intrusions (spines) with low explosive activity. The San Luis Gonzaga volcanic suite ranges in composition from basaltic andesite to dacite with predominant plagioclase and pyroxene and variable amounts of hornblende. Trace-element patterns indicate calc-alkaline to mildly alkaline magmas with high Ba and low Nb contents. Incompatible-element ratios and mineralogical characteristics suggest different magma batches and/or different amount of crustal assimilation for the three sequences that produced contrasting eruptive styles. A

  8. Compositional Differences between Felsic Volcanic rocks from the ...

    African Journals Online (AJOL)

    The elemental and Sr-Nd isotopic compositions of the volcanic rocks suggest that fractional crystallization from differing basic parents accompanied by a limited assimilation (AFC) was the dominant process controlling the genesis of the MER felsic volcanic rocks. Keywords: Ethiopia; Northern Main Ethiopian Rift; Bimodal ...

  9. Monitoring gas emissions can help forecast volcanic eruptions

    Science.gov (United States)

    Kern, Christoph; Maarten de Moor,; Bo Galle,

    2015-01-01

    As magma ascends in active volcanoes, dissolved volatiles partition from melt into a gas phase, rise, and are released into the atmosphere from volcanic vents. The major components of high-temperature volcanic gas are typically water vapor, carbon dioxide, and sulfur dioxide. 

  10. Ice nucleation and overseeding of ice in volcanic clouds

    Science.gov (United States)

    Durant, A. J.; Shaw, R. A.; Rose, W. I.; Mi, Y.; Ernst, G. G. J.

    2008-05-01

    Water is the dominant component of volcanic gas emissions, and water phase transformations, including the formation of ice, can be significant in the dynamics of volcanic clouds. The effectiveness of volcanic ash particles as ice-forming nuclei (IN) is poorly understood and the sparse data that exist for volcanic ash IN have been interpreted in the context of meteorological, rather than volcanic clouds. In this study, single-particle freezing experiments were carried out to investigate the effect of ash particle composition and surface area on water drop freezing temperature. Measured freezing temperatures show only weak correlations with ash IN composition and surface area. Our measurements, together with a review of previous volcanic ash IN measurements, suggest that fine-ash particles (equivalent diameters between approximately 1 and 1000 μm) from the majority of volcanoes will exhibit an onset of freezing between ˜250-260 K. In the context of explosive eruptions where super-micron particles are plentiful, this result implies that volcanic clouds are IN-rich relative to meteorological clouds, which typically are IN-limited, and therefore should exhibit distinct microphysics. We can expect that such "overseeded" volcanic clouds will exhibit enhanced ice crystal concentrations and smaller average ice crystal size, relative to dynamically similar meteorological clouds, and that glaciation will tend to occur over a relatively narrow altitude range.

  11. Mylonitic volcanics near Puging, Upper Siang district, Arunachal ...

    Indian Academy of Sciences (India)

    The Abor volcanics of the continental flood basalt affinity are extensively exposed in different parts of the Siang valley. These are associated with Yinkiong Group of rocks of Paleocene–Eocene age and represent syn-sedimentary volcanism in a rift setting. Subsequent folding and thrusting of the Siyom and Rikor sequences ...

  12. Interpretation of magnetic fabrics in the Dalma volcanic rocks and ...

    Indian Academy of Sciences (India)

    70

    The generations of the Fe-Ti oxides are different in the meta-sediments and volcanics, the former .... distribution of the volcanic rocks at Chandil (north of Dalma) and the absence of 1500-1600. Ma old charnockites ..... But according to petrography the quartzites are not that rich in primary titano-magnetite which can define a.

  13. Mylonitic volcanics near Puging, Upper Siang district, Arunachal ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 125; Issue 6. Mylonitic volcanics near ... This paper provides field evidence proving that the compression due the Burmese plate made oblique slip thrusting and zones of mylonitised volcanics possible and associated metasediments were formed. The kinematic ...

  14. Retinal cone photoreceptors of the deer mouse Peromyscus maniculatus: development, topography, opsin expression and spectral tuning.

    Directory of Open Access Journals (Sweden)

    Patrick Arbogast

    Full Text Available A quantitative analysis of photoreceptor properties was performed in the retina of the nocturnal deer mouse, Peromyscus maniculatus, using pigmented (wildtype and albino animals. The aim was to establish whether the deer mouse is a more suitable model species than the house mouse for photoreceptor studies, and whether oculocutaneous albinism affects its photoreceptor properties. In retinal flatmounts, cone photoreceptors were identified by opsin immunostaining, and their numbers, spectral types, and distributions across the retina were determined. Rod photoreceptors were counted using differential interference contrast microscopy. Pigmented P. maniculatus have a rod-dominated retina with rod densities of about 450.000/mm(2 and cone densities of 3000-6500/mm(2. Two cone opsins, shortwave sensitive (S and middle-to-longwave sensitive (M, are present and expressed in distinct cone types. Partial sequencing of the S opsin gene strongly supports UV sensitivity of the S cone visual pigment. The S cones constitute a 5-15% minority of the cones. Different from house mouse, S and M cone distributions do not have dorsoventral gradients, and coexpression of both opsins in single cones is exceptional (<2% of the cones. In albino P. maniculatus, rod densities are reduced by approximately 40% (270.000/mm(2. Overall, cone density and the density of cones exclusively expressing S opsin are not significantly different from pigmented P. maniculatus. However, in albino retinas S opsin is coexpressed with M opsin in 60-90% of the cones and therefore the population of cones expressing only M opsin is significantly reduced to 5-25%. In conclusion, deer mouse cone properties largely conform to the general mammalian pattern, hence the deer mouse may be better suited than the house mouse for the study of certain basic cone properties, including the effects of albinism on cone opsin expression.

  15. Deep Explosive Volcanism on the Gakkel Ridge and Seismological Constraints on Shallow Recharge at TAG Active Mound

    Science.gov (United States)

    Pontbriand, Claire Willis

    Seafloor digital imagery and bathymetric data are used to evaluate the volcanic characteristics of the 85°E segment of the ultraslow spreading Gakkel Ridge (9 mm yr-1 ). Imagery reveals that ridges and volcanic cones in the axial valley are covered by numerous, small-volume lava flows, including a few flows fresh enough to have potentially erupted during the 1999 seismic swarm at the site. The morphology and distribution of volcaniclastic deposits observed on the seafloor at depths of ˜3800 m, greater than the critical point for steam generation, are consistent with having formed by explosive discharge of magma and C02 from source vents. Microearthquakes recorded on a 200 m aperture seismometer network deployed on the Trans-Atlantic Geotraverse active mound, a seafloor massive sulfide on the Mid-Atlantic Ridge at 26°N, are used to image subsurface processes at the hydrothermal system. Over nine-months, 32,078 local microearthquakes (ML = -1) with single-phase arrivals cluster on the southwest flank of the deposit at depths <125 m. Microearthquakes characteristics are consistent with reaction-driven cracking driven by anhydrite deposition in the shallow secondary circulation system. Exit fluid temperatures recorded at diffuse vents on the mound during the microearthquake study are used to explore linkages between seismicity and venting. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs mit.edu)

  16. The Auckland Volcanic Field - a basaltic field showing random behavior?

    Science.gov (United States)

    Le Corvec, N.; Rowland, J. V.; Lindsay, J. M.

    2012-04-01

    Basaltic monogenetic volcanism is a worldwide phenomenon typically producing fields of volcanic centers that increase in number with time. The process of field growth is not constant but punctuated by single eruptions, flare-ups and hiatuses. The development of a volcanic field involves physical processes that occur in the mantle, where batches of basaltic magma originate, and within the intervening lithosphere through which magma is transferred to the surface. The spatial and temporal distribution of volcanic centers within such volcanic fields results from, and thus may provide insights to, these physical processes (e.g., magma production, tectonic controls), thereby aiding in our understanding of a volcanic field's future development. The Auckland Volcanic Field (AVF), which lies in the most populated area of New Zealand, comprises 50 volcanic centers and produced its last eruption ~600 years ago. A recent study has provided a relative chronology of the entire sequence of eruptions, which is here used together with the spatial distribution of volcanic centers to investigate the evolution of the field in time and space. Two methods were used: 1) the Poisson Nearest Neighbor (PNN) analysis which evaluates the spatial distribution of a natural population over the spatial distribution of a statistical random model, the Poisson model; and 2) the Voronoi analysis which evaluates the spatial characteristics of each volcanic center by dividing a region (i.e., the volcanic field) into a set of polygons. The results of the PNN analysis show that the temporal evolution of the spatial distribution of the volcanic centers within the AVF follows the Poisson model, therefore they cannot be used to extrapolate the future evolution of the volcanic field. The preliminary results of the Voronoi analysis show in combination with the geochemical signatures from some volcanic centers a possible zonation within the source region, and/or the magmas may be variably affected on their way

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

    Science.gov (United States)

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

    2013-12-01

    Iwojima is an active volcanic island located within a 10 km wide submarine caldera about 1250 km to the south of Tokyo, Japan. The seismometer and GPS network of National Research Institute for Earth Science and Disaster Prevention (NIED) in Iwojima has observed a repeating island wide uplift more than 1 m associated with large number of volcanic earthquakes every several years. During 2006-2012, we observed more than 20000 volcanic earthquakes and an uplift of about 3 m, and precursory volcanic earthquakes and rapid crustal deformation just before the small submarine eruption near the northern coast of Iwojima in April 2012. In a restless volcano such as Iwojima, it is important issue to distinguish whether rapid crustal deformation and intense earthquake activity lead to an eruption or not. According to a long period geodetic observation by Ukawa et al. (2006), the crustal deformation of Iwojima can be classify into 2 phases. The first is an island wide large uplift centering on Motoyama area (the eastern part of the island, the center of the caldera), and the second is contraction and subsidence at local area centering on Motoyama and uplift around that area. They are interpreted by superposition of crustal deformations by a shallow contraction source and a deep seated inflation source beneath Motoyama. The earthquake activity of Iwojima highly correlates with the island wide large uplift, suggesting the earthquakes are almost controlled by a magma accumulation into a deep seated magma chamber. In contrast to the activity, the precursory activity of the eruption in 2012 is deviated from the correlation. The rapid crustal deformation just before and after the eruption in 2012 can be interpreted by rapid inflation and deflation of a shallow sill source about 1km deep, respectively, suggesting that it was caused by a shallow hydrothermal activity. The result shows that we can probably distinguish an abnormal activity related with a volcanic eruption when we observe

  18. Correlating geochemistry, tectonics, and volcanic volume along the Central American volcanic front

    Science.gov (United States)

    Bolge, Louise L.; Carr, Michael J.; Milidakis, Katherine I.; Lindsay, Fara N.; Feigenson, Mark D.

    2009-12-01

    The Central American volcanic front consists of several distinct volcanic lineaments or segments, separated by right steps and/or changes in strike. Each volcanic line is rotated slightly counterclockwise from the strike of the inclined seismic zone. Right stepping volcanic lines, oblique to the strike of the slab, create a sawtooth pattern in the depth to the slab. Zr/Nb is the first geochemical signature with consistent large offsets at the right steps in the volcanic front. Moreover, Zr/Nb mirrors the sawtooth variation in depth to the slab; within a segment it increases from SE to NW, and at the right steps, separating segments, it abruptly decreases. Unfortunately, there is no simple negative correlation between Zr/Nb and depth to the slab because Zr/Nb also has a regional variation, similar to previously documented regional variations in slab tracers in Central America (e.g., Ba/La, U/Th, and 87Sr/86Sr). Within a segment, Zr/Nb decreases with increasing depth to slab. This can be explained in two ways: a Nb retaining mineral, e.g., amphibole, in the subducting slab is breaking down gradually with increasing depth causing more Nb to be released and consequently a smaller Nb depletion in deeper melts; alternatively, all melts have the same initial Nb depletion which is then diluted by acquiring Nb from the surrounding mantle wedge as melts rise and react. Deeper melts have longer paths and therefore more reaction with the mantle wedge diluting the initial Nb depletion. Within each volcanic segment there is variation in eruptive volume. The largest volcanoes generally occur in the middle of the segments, and the smaller volcanoes tend to be located at the ends. Connecting the largest volcanoes in each segment suggests an axis of maximum productivity. This is likely the surface projection of the center of the melt aggregation zone. The largest volcanoes tap the entire melt zone. Those with shallow depths to the slab tap just the front part of the melt zone and

  19. Distinguishing high surf from volcanic long-period earthquakes

    Science.gov (United States)

    Lyons, John; Haney, Matt; Fee, David; Paskievitch, John F.

    2014-01-01

    Repeating long-period (LP) earthquakes are observed at active volcanoes worldwide and are typically attributed to unsteady pressure fluctuations associated with fluid migration through the volcanic plumbing system. Nonvolcanic sources of LP signals include ice movement and glacial outburst floods, and the waveform characteristics and frequency content of these events often make them difficult to distinguish from volcanic LP events. We analyze seismic and infrasound data from an LP swarm recorded at Pagan volcano on 12–14 October 2013 and compare the results to ocean wave data from a nearby buoy. We demonstrate that although the events show strong similarity to volcanic LP signals, the events are not volcanic but due to intense surf generated by a passing typhoon. Seismo-acoustic methods allow for rapid distinction of volcanic LP signals from those generated by large surf and other sources, a critical task for volcano monitoring.

  20. Assessment of volcanic hazards, vulnerability, risk and uncertainty (Invited)

    Science.gov (United States)

    Sparks, R. S.

    2009-12-01

    A volcanic hazard is any phenomenon that threatens communities . These hazards include volcanic events like pyroclastic flows, explosions, ash fall and lavas, and secondary effects such as lahars and landslides. Volcanic hazards are described by the physical characteristics of the phenomena, by the assessment of the areas that they are likely to affect and by the magnitude-dependent return period of events. Volcanic hazard maps are generated by mapping past volcanic events and by modelling the hazardous processes. Both these methods have their strengths and limitations and a robust map should use both approaches in combination. Past records, studied through stratigraphy, the distribution of deposits and age dating, are typically incomplete and may be biased. Very significant volcanic hazards, such as surge clouds and volcanic blasts, are not well-preserved in the geological record for example. Models of volcanic processes are very useful to help identify hazardous areas that do not have any geological evidence. They are, however, limited by simplifications and incomplete understanding of the physics. Many practical volcanic hazards mapping tools are also very empirical. Hazards maps are typically abstracted into hazards zones maps, which are some times called threat or risk maps. Their aim is to identify areas at high levels of threat and the boundaries between zones may take account of other factors such as roads, escape routes during evacuation, infrastructure. These boundaries may change with time due to new knowledge on the hazards or changes in volcanic activity levels. Alternatively they may remain static but implications of the zones may change as volcanic activity changes. Zone maps are used for planning purposes and for management of volcanic crises. Volcanic hazards maps are depictions of the likelihood of future volcanic phenomena affecting places and people. Volcanic phenomena are naturally variable, often complex and not fully understood. There are

  1. SU-F-J-205: Effect of Cone Beam Factor On Cone Beam CT Number Accuracy

    Energy Technology Data Exchange (ETDEWEB)

    Yao, W; Hua, C; Farr, J; Brady, S; Merchant, T [St. Jude Children’s Research Hospital, Memphis, TN (United States)

    2016-06-15

    Purpose: To examine the suitability of a Catphan™ 700 phantom for image quality QA of a cone beam computed tomography (CBCT) system deployed for proton therapy. Methods: Catphan phantoms, particularly Catphan™ 504, are commonly used in image quality QA for CBCT. As a newer product, Catphan™ 700 offers more tissue equivalent inserts which may be useful for generating the electron density – CT number curve for CBCT based treatment planning. The sensitometry-and-geometry module used in Catphan™ 700 is located at the end of the phantom and after the resolution line pair module. In Catphan™ 504 the line pair module is located at the end of the phantom and after the sensitometry-and-geometry module. To investigate the effect of difference in location on CT number accuracy due to the cone beam factor, we scanned the Catphan™ 700 with the central plane of CBCT at the center of the phantom, line pair and sensitometry-andgeometry modules of the phantom, respectively. The protocol head and thorax scan modes were used. For each position, scans were repeated 4 times. Results: For the head scan mode, the standard deviation (SD) of the CT numbers of each insert under 4 repeated scans was up to 20 HU, 11 HU, and 11 HU, respectively, for the central plane of CBCT located at the center of the phantom, line pair, and sensitometry-and-geometry modules of the phantom. The mean of the SD was 9.9 HU, 5.7 HU, and 5.9 HU, respectively. For the thorax mode, the mean of the SD was 4.5 HU, 4.4 HU, and 4.4 HU, respectively. The assessment of image quality based on resolution and spatial linearity was not affected by imaging location changes. Conclusion: When the Catphan™ 700 was aligned to the center of imaging region, the CT number accuracy test may not meet expectations. We recommend reconfiguration of the modules.

  2. String/flux tube duality on the light cone

    International Nuclear Information System (INIS)

    Brower, Richard C.; Tan, C.-I; Thorn, Charles B.

    2006-01-01

    The equivalence of quantum field theory and string theory as exemplified by the AdS/CFT correspondence is explored from the point of view of light cone quantization. On the string side we discuss the light cone version of the static string connecting a heavy external quark source to a heavy external antiquark source, together with small oscillations about the static string configuration. On the field theory side we analyze the weak/strong coupling transition in a ladder diagram model of the quark-antiquark system, also from the point of view of the light cone. Our results are completely consistent with those obtained by more standard covariant methods in the limit of infinitely massive quarks

  3. Concrescence: Cone-Beam Computed Tomography Imaging Perspective

    Directory of Open Access Journals (Sweden)

    Ali Zakir Syed

    2016-01-01

    Full Text Available Concrescence is a form of twinning, formed by the confluence of cementum of two teeth at the root level. The diagnosis of concrescence has largely relied on the conventional 2D imaging. The 2D imaging has inherent limitations such as distortion and superimposition. Cone-Beam CT eliminates these limitations. The aim of this article was to describe a case of dental abnormality using Cone-Beam CT imaging modality. Volumetric data demonstrated confluence of left mandibular third molar with a paramolar, a supernumerary tooth. To our knowledge, this is the second case in the dental literature reported demonstrating the use of Cone-Beam CT in the diagnosis of concrescence.

  4. Effect of inlet cone pipe angle in catalytic converter

    Science.gov (United States)

    Amira Zainal, Nurul; Farhain Azmi, Ezzatul; Arifin Samad, Mohd

    2018-03-01

    The catalytic converter shows significant consequence to improve the performance of the vehicle start from it launched into production. Nowadays, the geometric design of the catalytic converter has become critical to avoid the behavior of backpressure in the exhaust system. The backpressure essentially reduced the performance of vehicles and increased the fuel consumption gradually. Consequently, this study aims to design various models of catalytic converter and optimize the volume of fluid flow inside the catalytic converter by changing the inlet cone pipe angles. Three different geometry angles of the inlet cone pipe of the catalytic converter were assessed. The model is simulated in Solidworks software to determine the optimum geometric design of the catalytic converter. The result showed that by decreasing the divergence angle of inlet cone pipe will upsurge the performance of the catalytic converter.

  5. An ice-cream cone model for coronal mass ejections

    Science.gov (United States)

    Xue, X. H.; Wang, C. B.; Dou, X. K.

    2005-08-01

    In this study, we use an ice-cream cone model to analyze the geometrical and kinematical properties of the coronal mass ejections (CMEs). Assuming that in the early phase CMEs propagate with near-constant speed and angular width, some useful properties of CMEs, namely the radial speed (v), the angular width (α), and the location at the heliosphere, can be obtained considering the geometrical shapes of a CME as an ice-cream cone. This model is improved by (1) using an ice-cream cone to show the near real configuration of a CME, (2) determining the radial speed via fitting the projected speeds calculated from the height-time relation in different azimuthal angles, (3) not only applying to halo CMEs but also applying to nonhalo CMEs.

  6. Genesis and evolution of the Cerro Prieto Volcanic Complex, Baja California, Mexico

    Science.gov (United States)

    García-Sánchez, L.; Macías, J. L.; Sosa-Ceballos, G.; Arce, J. L.; Garduño-Monroy, V. H.; Saucedo, R.; Avellán, D. R.; Rangel, E.; Layer, P. W.; López-Loera, H.; Rocha, V. S.; Cisneros, G.; Reyes-Agustín, G.; Jiménez, A.; Benowitz, J. A.

    2017-06-01

    The Cerro Prieto Volcanic Complex (CPVC), located in northwestern Mexico, is the only surface manifestation of the Cerro Prieto Geothermal Field, the third largest producer of geothermal energy in the world. This geothermal field and the Salton Sea in the USA sit in a pull-apart basin that belongs to the trans-tensional tectonic zone that includes the San Andreas Fault system and the Salton Trough basin to the NW and the East Pacific Rise to the SE. In spite of its strategic importance in the generation of geothermal energy, the origin of Cerro Prieto and its relationship with the geothermal reservoir were unknown. In this contribution, we discuss the origin, evolution, and mechanisms of formation of this small monogenetic volcano and the magmas that fed the system. The volcanic complex is located on top of the Cerro Prieto left lateral fault to the northwest of the Cerro Prieto Geothermal Field. The complex consists of a lava cone and a series of domes (˜0.15 km3) protruding from Tertiary sandstones and recent unconsolidated sediments of the alluvial plain of the Colorado River. The Cerro Prieto Volcanic Complex consists of seven stratigraphic units emplaced in a brief time span around 78-81 ka. Its activity began with the extrusion of a dacitic lava that came into contact with water-saturated sediments, causing brecciation of the lava. The activity continued with the emplacement of dacitic domes and a dyke that were destroyed by a phreatic explosion emplacing a lithic-rich breccia. This phreatic explosion formed a 300-m-wide and 40-m-deep circular crater. The activity then migrated ˜650 m to the SW where three dacitic lava domes were extruded and ended with the emplacement of a fissure-fed lava flow. Subsequent remobilization of the rocks in the complex has generated debris and hyperconcentrated flow deposits interbedded with fluviatile sediments in the surrounding terrain. All rocks of the CPVC are dacites with phenocrysts of plagioclase, orthopyroxene, and Fe

  7. ATMOSPHERIC DISPERSAL AND DEPOSITION OF TEPHRA FROM A POTENTIAL VOLCANIC ERUPTION AT YUCCA MOUNTAIN, NEVADA

    International Nuclear Information System (INIS)

    C. Harrington

    2004-01-01

    The purpose of this model report is to provide documentation of the conceptual and mathematical model (Ashplume) for atmospheric dispersal and subsequent deposition of ash on the land surface from a potential volcanic eruption at Yucca Mountain, Nevada. This report also documents the ash (tephra) redistribution conceptual model. These aspects of volcanism-related dose calculation are described in the context of the entire igneous disruptive events conceptual model in ''Characterize Framework for Igneous Activity'' (BSC 2004 [DIRS 169989], Section 6.1.1). The Ashplume conceptual model accounts for incorporation and entrainment of waste fuel particles associated with a hypothetical volcanic eruption through the Yucca Mountain repository and downwind transport of contaminated tephra. The Ashplume mathematical model describes the conceptual model in mathematical terms to allow for prediction of radioactive waste/ash deposition on the ground surface given that the hypothetical eruptive event occurs. This model report also describes the conceptual model for tephra redistribution from a basaltic cinder cone. Sensitivity analyses and model validation activities for the ash dispersal and redistribution models are also presented. Analyses documented in this model report update the previous documentation of the Ashplume mathematical model and its application to the Total System Performance Assessment (TSPA) for the License Application (TSPA-LA) igneous scenarios. This model report also documents the redistribution model product outputs based on analyses to support the conceptual model. In this report, ''Ashplume'' is used when referring to the atmospheric dispersal model and ''ASHPLUME'' is used when referencing the code of that model. Two analysis and model reports provide direct inputs to this model report, namely ''Characterize Eruptive Processes at Yucca Mountain, Nevada and Number of Waste Packages Hit by Igneous Intrusion''. This model report provides direct inputs to

  8. Structure and development of an axial volcanic ridge: Mid-Atlantic Ridge, 45°N

    Science.gov (United States)

    Searle, R. C.; Murton, B. J.; Achenbach, K.; LeBas, T.; Tivey, M.; Yeo, I.; Cormier, M. H.; Carlut, J.; Ferreira, P.; Mallows, C.; Morris, K.; Schroth, N.; van Calsteren, P.; Waters, C.

    2010-10-01

    We describe the most comprehensive and detailed high resolution survey of an axial volcanic ridge (AVR) ever conducted, at 45°N on the Mid-Atlantic Ridge. We use 3 m resolution sidescan sonar, deep-towed magnetic field measurements, video observations from eleven ROV dives, and two very-high-resolution bathymetry and magnetic surveys. The most recently active AVR has high topographic relief, high acoustic backscatter, high crustal magnetization and little faulting. It is sharp-crested, 25 × 4 km in extent and 500 m high, and is covered by approximately 8000 volcanic "hummocks" whose detailed nature is revealed for the first time. Each is an individual volcano ≤ 450 m in diameter and ≤ 200 m high, ranging from steep-sided (45°) cones to low domes. Many have suffered significant flank collapse. Hummocks tend to align in rows parallel to the AVR axis, parallel to its NE-trending spurs or, on its lower flanks, sub-normal to the AVR trend. These latter are spaced 1-2 km apart and comprise 1-2 km-long rows of single volcanoes. We infer that their emplacement is controlled by down-flank magma transport, possibly via lava tubes. The AVR contains only one large flat-topped seamount. The flanking median valley floor consists of either older hummocky volcanic terrain or flat-lying, mostly sediment-covered lavas. These typically have low-relief lobate surfaces, inflation and collapse structures, and occasional lava tubes and tumuli. The AVR displays open fissures, mostly along its crest. There is direct evidence for only a few small faults on the AVR, though steep, outward-facing slopes draped by elongate pillows may be small normal faults covered by lava. The surrounding median valley floor is heavily fissured. Normal faults cut it and an older AVR, the latter displaying significant outward facing faults. High crustal magnetization, an approximate proxy for crustal age within the Brunhes, is confined to the active AVR. Magnetic palaeointensity measurements are

  9. ATMOSPHERIC DISPERSAL AND DEPOSITION OF TEPHRA FROM A POTENTIAL VOLCANIC ERUPTION AT YUCCA MOUNTAIN, NEVADA

    Energy Technology Data Exchange (ETDEWEB)

    C. Harrington

    2004-10-25

    The purpose of this model report is to provide documentation of the conceptual and mathematical model (Ashplume) for atmospheric dispersal and subsequent deposition of ash on the land surface from a potential volcanic eruption at Yucca Mountain, Nevada. This report also documents the ash (tephra) redistribution conceptual model. These aspects of volcanism-related dose calculation are described in the context of the entire igneous disruptive events conceptual model in ''Characterize Framework for Igneous Activity'' (BSC 2004 [DIRS 169989], Section 6.1.1). The Ashplume conceptual model accounts for incorporation and entrainment of waste fuel particles associated with a hypothetical volcanic eruption through the Yucca Mountain repository and downwind transport of contaminated tephra. The Ashplume mathematical model describes the conceptual model in mathematical terms to allow for prediction of radioactive waste/ash deposition on the ground surface given that the hypothetical eruptive event occurs. This model report also describes the conceptual model for tephra redistribution from a basaltic cinder cone. Sensitivity analyses and model validation activities for the ash dispersal and redistribution models are also presented. Analyses documented in this model report update the previous documentation of the Ashplume mathematical model and its application to the Total System Performance Assessment (TSPA) for the License Application (TSPA-LA) igneous scenarios. This model report also documents the redistribution model product outputs based on analyses to support the conceptual model. In this report, ''Ashplume'' is used when referring to the atmospheric dispersal model and ''ASHPLUME'' is used when referencing the code of that model. Two analysis and model reports provide direct inputs to this model report, namely ''Characterize Eruptive Processes at Yucca Mountain, Nevada and Number of Waste Packages Hit

  10. Numerical modelling of collapsing volcanic edifices

    Science.gov (United States)

    Costa, Ana; Marques, Fernando; Kaus, Boris

    2017-04-01

    The flanks of Oceanic Volcanic Edifice's (OVEs) can occasionally become unstable. If that occurs, they can deform in two different modes: either slowly along localization failure zones (slumps) or catastrophically as debris avalanches. Yet the physics of this process is incompletely understood, and the role of factors such as the OVE's strength (viscosity, cohesion, friction angle), dimensions, geometry, and existence of weak layers remain to be addressed. Here we perform numerical simulations to study the interplay between viscous and plastic deformation on the gravitational collapse of an OVE (diffuse deformation vs. localization of failure along discrete structures). We focus on the contribution of the edifice's strength parameters for the mode of deformation, as well as on the type of basement. Tests were performed for a large OVE (7.5 km high, 200 km long) and either purely viscous (overall volcano edifice viscosities between 1019-1023 Pa.s), or viscoplastic rheology (within a range of cohesion and friction angle values). Results show that (a) for a strong basement (no slip basal boundary condition), the deformation pattern suggests wide/diffuse "listric" deformation within the volcanic edifice, without the development of discrete plastic failure zones; (b) for a weak basement (free slip basal boundary condition), rapid collapse of the edifice through the propagation of plastic failure structures within the edifice occurs. Tests for a smaller OVE (4.5 km by 30 km) show that failure localization along large-scale listric structures occurs more readily for different combinations of cohesion and friction angles. In these tests, high cohesion values combined with small friction angles lead to focusing of deformation along a narrower band. Tests with a weak layer underlying part of the volcanic edifice base show deformation focused along discrete structures mainly dipping towards the distal sector of the volcano. These tests for a small OVE constitute a promising

  11. Magnetic signature of the Sicily Channel volcanism

    Science.gov (United States)

    Lodolo, E.; Civile, D.; Zanolla, C.; Geletti, R.

    2012-03-01

    Widespread Late Miocene to Quaternary volcanic activity is know to have occurred in the Sicily Channel continuing up to historical time. New magnetic anomaly data acquired in the Pantelleria Graben, one of the three main tectonic depressions forming the WNW-trending Sicily Channel rift system, integrated with available profiles, are used to identify and map volcanic bodies in this sector of the northern African margin. Some of these manifestations, both outcropping at the sea-floor or buried beneath a variable thickness of Plio-Quaternary sedimentary cover, have been imaged by seismic reflection profiles. Three main positive magnetic anomalies have been found: to the S-E of the Pantelleria Island, the largest emerged caldera of the Sicily Channel, along the eastern margin of the Nameless Bank, and at the north-western termination of the Linosa Graben. Only the anomaly located off the south-eastern coast of the Pantelleria Island, associated with a large outcropping body gradually buried beneath a substantially undisturbed Upper Pliocene-Quaternary sediments, aligns with the trend of the tectonic depression. 2-D geophysical models produced along seismic transects perpendicularly crossing the Pantelleria Graben have allowed to derive its deep crustal structure, and detect the presence of buried magmatic bodies which generate the anomalies. Marginal faults seem to have played a major role in focussing magma emplacement in this sector of the Sicily Channel. The other anomalies represent off-axis volcanic episodes and generally do not show evident magmatic manifestations at the sea-floor. These magnetic maxima seem to follow a NNE-SSW-trending belt extending from Linosa Island to the Nameless Bank, where pre-existing crustal anisotropies may have conditioned magma emplacement both at deep and shallow crustal levels. In general, data analysis has shown that there is a structural control on magma emplacement, with the major magmatic features located in specific locations

  12. Loss-cone-driven ion cyclotron waves in the magnetosphere

    International Nuclear Information System (INIS)

    Denton, R.E.; Hudson, M.K.; Roth, I.

    1992-01-01

    The theoretical properties of linear ion cyclotron waves propagating in the magnetosphere at arbitrary angles to the background magnetic field are explored. It is found that in some cases the linear wave growth of modes with oblique propagation can dominate that of the parallel propagating electromagnetic ion cyclotron (EMIC) wave. In particular, when the hot ring current protons have a loss cone and their temperature anisotropy A ≡ T perpendicular /T parallel - 1 is reduced, the parallel propagating EMIC wave becomes stable, while the obliquely propagating loss-cone-driven mode persists. The growth rate of the loss-cone-driven model depends strongly on the depth of the loss cone. Unlike the parallel propagating EMIC wave, it can be unstable with A = 0. Other conditions that favor the loss-cone-driven mode in comparison to the parallel mode are stronger background magnetic field, lower density of cold hydrogen, and a lower temperature for the hot anisotropic component of hydrogen. A simple analytical theory is presented which explains the scaling of the growth rate of the oblique mode with respect to various parameters. The loss-cone-driven mode is an electromagnetic mode which is preferentially nearly linearly polarized. It is nearly electrostatic in the sense that the wave electric field is aligned with the perpendicular (to B 0 ) component of the wave vector k and k perpendicular > k parallel . Since the electric and magnetic wave fields are perpendicular to B 0 , they would be difficult to distinguish from those of a linearly polarized parallel propagating electromagnetic wave with the same k parallel

  13. Real Time Volcanic Cloud Products and Predictions for Aviation Alerts

    Science.gov (United States)

    Krotkov, Nickolay A.; Habib, Shahid; da Silva, Arlindo; Hughes, Eric; Yang, Kai; Brentzel, Kelvin; Seftor, Colin; Li, Jason Y.; Schneider, David; Guffanti, Marianne; hide

    2014-01-01

    Volcanic eruptions can inject significant amounts of sulfur dioxide (SO2) and volcanic ash into the atmosphere, posing a substantial risk to aviation safety. Ingesting near-real time and Direct Readout satellite volcanic cloud data is vital for improving reliability of volcanic ash forecasts and mitigating the effects of volcanic eruptions on aviation and the economy. NASA volcanic products from the Ozone Monitoring Insrument (OMI) aboard the Aura satellite have been incorporated into Decision Support Systems of many operational agencies. With the Aura mission approaching its 10th anniversary, there is an urgent need to replace OMI data with those from the next generation operational NASA/NOAA Suomi National Polar Partnership (SNPP) satellite. The data provided from these instruments are being incorporated into forecasting models to provide quantitative ash forecasts for air traffic management. This study demonstrates the feasibility of the volcanic near-real time and Direct Readout data products from the new Ozone Monitoring and Profiling Suite (OMPS) ultraviolet sensor onboard SNPP for monitoring and forecasting volcanic clouds. The transition of NASA data production to our operational partners is outlined. Satellite observations are used to constrain volcanic cloud simulations and improve estimates of eruption parameters, resulting in more accurate forecasts. This is demonstrated for the 2012 eruption of Copahue. Volcanic eruptions are modeled using the Goddard Earth Observing System, Version 5 (GEOS-5) and the Goddard Chemistry Aerosol and Radiation Transport (GOCART) model. A hindcast of the disruptive eruption from Iceland's Eyjafjallajokull is used to estimate aviation re-routing costs using Metron Aviation's ATM Tools.

  14. Volcanic and Hydrothermal Activity of the North Su Volcano: New Insights from Repeated Bathymetric Surveys and ROV Observations

    Science.gov (United States)

    Thal, J.; Bach, W.; Tivey, M.; Yoerger, D.

    2013-12-01

    Bathymetric data from cruises in 2002, 2006, and 2011 were combined and compared to determine the evolution of volcanic activity, seafloor structures, erosional features and to identify and document the distribution of hydrothermal vents on North Su volcano, SuSu Knolls, eastern Manus Basin (Papua New Guinea). Geologic mapping based on ROV observations from 2006 (WHOI Jason-2) and 2011 (MARUM Quest-4000) combined with repeated bathymetric surveys from 2002 and 2011 are used to identify morphologic features on the slopes of North Su and to track temporal changes. ROV MARUM Quest-4000 bathymetry was used to develop a 10 m grid of the top of North Su to precisely depict recent changes. In 2006, the south slope of North Su was steeply sloped and featured numerous white smoker vents discharging acid sulfate waters. These vents were covered by several tens of meters of sand- to gravel-sized volcanic material in 2011. The growth of this new cone changed the bathymetry of the south flank of North Su up to ~50 m and emplaced ~0.014 km3 of clastic volcanic material. This material is primarily comprised of fractured altered dacite and massive fresh dacite as well as crystals of opx, cpx, olivine and plagioclase. There is no evidence for pyroclastic fragmentation, so we hypothesize that the fragmentation is likely related to hydrothermal explosions. Hydrothermal activity varies over a short (~50 m) lateral distance from 'flashing' black smokers to acidic white smoker vents. Within 2 weeks of observation time in 2011, the white smoker vents varied markedly in activity suggesting a highly episodic hydrothermal system. Based on ROV video recordings, we identified steeply sloping (up to 30°) slopes exposing pillars and walls of hydrothermal cemented volcaniclastic material representing former fluid upflow zones. These features show that hydrothermal activity has increased slope stability as hydrothermal cementation has prevented slope collapse. Additionally, in some places

  15. Mafic Volcanism Along the Sinaloa Coast, Mexico, and its Relation to the Opening of the Gulf of California

    Science.gov (United States)

    Orozco Esquivel, T.; Ferrari, L.; Lopez Martinez, M.

    2007-05-01

    We report on new localities with mafic volcanism along the Sinaloa coast, which record changes in the magma generation processes along the eastern margin of the Gulf of California. South of Culiacán, Sinaloa, isolated outcrops of basaltic lavas built a ca. 60 km long belt aligned to the SE. The similarity in the mineralogy and composition of the lavas suggest that these outcrops could have been part of a single flow. Lavas contain abundant plagioclase (up to 3 mm), and olivine (up to 1.5 mm) phenocrysts, and scarce clinopyroxene, in a relatively coarse matrix. In multiement diagrams, the lavas show the negative Nb and Ta, and positive Pb and Sr anomalies characteristic of subduction related rocks. The age determination of these rocks is in process, nevertheless, rocks with similar compositions are known from ~11 Ma mafic dikes that outcrop in southern Sinaloa. The Pericos volcanic field, located about 25 km to the NW of Culiacán is composed by lava flows, shield volcanoes, and cinder cones of basaltic composition that cover an area of aprox. 20 x 32 km, and have a well preserved morphology suggestive of a Pliocene-Quaternary age. Lavas are porphyritic and contain olivine, plagioclase and clinopyroxene in a microcrystalline matrix. Some lava flows contain abundant megacrysts of green clinopyroxene (up to 8 cm), olivine (up to 1 cm), and/or plagioclase (up to 1 cm), or aggregates of olivine and clinopyroxene. Trace element abundances are remarkably uniform among all analyzed samples and are characteristic of intraplate magmas. Rocks with very similar composition, mineralogy, and also containing megacrysts, have been reported in the Pliocene Punta Piaxtla and Mesa Cacaxtla, located 200 km to the SSE at the Sinaloa coast. Those similarities indicate that mafic intraplate volcanism related to the opening of the Gulf of California is more broadly represented in the area than previously considered.

  16. Suitability of simple rheological laws for the numerical simulation of dense pyroclastic flows and long-runout volcanic avalanches

    Science.gov (United States)

    Kelfoun, Karim

    2011-08-01

    The rheology of volcanic rock avalanches and dense pyroclastic flows is complex, and it is difficult at present to constrain the physics of their processes. The problem lies in defining the most suitable parameters for simulating the behavior of these natural flows. Existing models are often based on the Coulomb rheology, sometimes with a velocity-dependent stress (e.g., Voellmy), but other laws have also been used. Here I explore the characteristics of flows, and their deposits, obtained on simplified topographies by varying source conditions and rheology. The Coulomb rheology, irrespective of whether there is a velocity-dependent stress, forms cone-shaped deposits that do not resemble those of natural long-runout events. A purely viscous or a purely turbulent flow can achieve realistic velocities and thicknesses but cannot form a deposit on slopes. The plastic rheology, with (e.g., Bingham) or without a velocity-dependent stress, is more suitable for the simulation of dense pyroclastic flows and long-runout volcanic avalanches. With this rheology, numerical flows form by pulses, which are often observed during natural flow emplacement. The flows exhibit realistic velocities and deposits of realistic thicknesses. The plastic rheology is also able to generate the frontal lobes and lateral levées which are commonly observed in the field. With the plastic rheology, levée formation occurs at the flow front due to a divergence of the driving stresses at the edges. Once formed, the levées then channel the remaining flow mass. The results should help future modelers of volcanic flows with their choice of which mechanical law corresponds best to the event they are studying.

  17. Correlation of engineering parameters of the presumpscot formation to the seismic cone penetration test (SCPTU).

    Science.gov (United States)

    2015-08-01

    The seismic cone penetration test with pore pressure measurement (SCPTu) is a geotechnical investigation technique which : involves pushing a sensitized cone into the subsurface at a constant rate while continuously measuring tip resistance, sleeve :...

  18. Evaluation of cone penetration testing (CPT) for use with transportation projects.

    Science.gov (United States)

    2011-04-01

    Cone Penetration Testing (CPT) has many advantages as a means for subsurface investigation. CPT consists of pushing a steel : cone into the ground and recording the penetration resistance using sensors. Pore pressure, shear wave velocity and other : ...

  19. Light-cone quantized QCD and novel hadron phenomenology

    International Nuclear Information System (INIS)

    Brodsky, S.J.

    1997-09-01

    The authors reviews progress made in solving gauge theories such as collinear quantum chromodynamics using light-cone Hamiltonian methods. He also shows how the light-cone Fock expansion for hadron wavefunctions can be used to compute operator matrix elements such as decay amplitudes, form factors, distribution amplitudes, and structure functions, and how it provides a tool for exploring novel features of QCD. The author also reviews commensurate scale relations, leading-twist identities which relate physical observables to each other, thus eliminating renormalization scale and scheme ambiguities in perturbative QCD predictions

  20. Gauge-invariant correlation functions in light-cone superspace

    Science.gov (United States)

    Ananth, Sudarshan; Kovacs, Stefano; arikh, Sarthak

    2012-05-01

    We initiate a study of correlation functions of gauge-invariant operators in {N} = 4 super Yang-Mills theory using the light-cone superspace formalism. Our primary aim is to develop efficient methods to compute perturbative corrections to correlation functions. This analysis also allows us to examine potential subtleties which may arise when calculating off-shell quantities in light-cone gauge. We comment on the intriguing possibility that the manifest {N} = 4 supersymmetry in this approach may allow for a compact description of entire multiplets and their correlation functions.

  1. PVC Cable Fire Toxicity using the Cone Calorimeter

    OpenAIRE

    Al-Sayegh, WA; Aljumaiah, O; Andrews, GE; Phylaktou, HN

    2017-01-01

    Electrical cables with PVC sheaths were investigated for their ignition characteristics, heat release and toxic yields using the cone calorimeter. 40 KW/m² was required to get a significant heat release for PVC. A heated Temet Gasmet FTIR was used for the toxic gas analysis. Gas samples were taken from the cone calorimeter diluted exhaust duct and transferred to the FTIR using a 190°C heated sample line, heated pump and filter and a second 190°C heated sample line between the pump and the FTI...

  2. Light-cone quantized QCD and novel hadron phenomenology

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, S.J.

    1997-09-01

    The authors reviews progress made in solving gauge theories such as collinear quantum chromodynamics using light-cone Hamiltonian methods. He also shows how the light-cone Fock expansion for hadron wavefunctions can be used to compute operator matrix elements such as decay amplitudes, form factors, distribution amplitudes, and structure functions, and how it provides a tool for exploring novel features of QCD. The author also reviews commensurate scale relations, leading-twist identities which relate physical observables to each other, thus eliminating renormalization scale and scheme ambiguities in perturbative QCD predictions.

  3. [Cone-beam pseudo lambda tomography under FDK framework].

    Science.gov (United States)

    Huang, Jing; Ma, Jian-hua; Chen, Ling-jian; Bi, Yi-ming; Chen, Wu-fan

    2009-10-01

    The medical CT scanner is rapidly evolving from the fan-beam mode to the cone-beam geometry mode. In this paper, a new cone-beam pseudo Lambda tomography was proposed based on the Noo's fan beam super-short scan formula and FDK framework. The proposed pseudo-LT algorithm, which avoids the computation of any PI line and any differential operation, has a significant practical implementation, thus leading to the images with quality improvement and reduced artifacts. The results in the simulation studies confirm the observation that the new algorithm can improve the image resolution over the traditional algorithms with noise projection data.

  4. Kamchatkan Volcanic Eruption Response Team (KVERT), Russia: preventing the danger of volcanic eruptions to aviation.

    Science.gov (United States)

    Girina, O.; Neal, Ch.

    2012-04-01

    The Kamchatkan Volcanic Eruption Response Team (KVERT) has been a collaborative project of scientists from the Institute of Volcanology and Seismology, the Kamchatka Branch of Geophysical Surveys, and the Alaska Volcano Observatory (IVS, KB GS and AVO). The purpose of KVERT is to reduce the risk of costly, damaging, and possibly deadly encounters of aircraft with volcanic ash clouds. To reduce this risk, KVERT collects all possible volcanic information and issues eruption alerts to aviation and other emergency officials. KVERT was founded by Institute of Volcanic Geology and Geochemistry FED RAS in 1993 (in 2004, IVGG merged with the Institute of Volcanology to become IVS). KVERT analyzes volcano monitoring data (seismic, satellite, visual and video, and pilot reports), assigns the Aviation Color Code, and issues reports on eruptive activity and unrest at Kamchatkan (since 1993) and Northern Kurile (since 2003) volcanoes. KVERT receives seismic monitoring data from KB GS (the Laboratory for Seismic and Volcanic Activity). KB GS maintains telemetered seismic stations to investigate 11 of the most active volcanoes in Kamchatka. Data are received around the clock and analysts evaluate data each day for every monitored volcano. Satellite data are provided from several sources to KVERT. AVO conducts satellite analysis of the Kuriles, Kamchatka, and Alaska as part of it daily monitoring and sends the interpretation to KVERT staff. KVERT interprets MODIS and MTSAT images and processes AVHRR data to look for evidence of volcanic ash and thermal anomalies. KVERT obtains visual volcanic information from volcanologist's field trips, web-cameras that monitor Klyuchevskoy (established in 2000), Sheveluch (2002), Bezymianny (2003), Koryaksky (2009), Avachinsky (2009), Kizimen (2011), and Gorely (2011) volcanoes, and pilots. KVERT staff work closely with staff of AVO, AMC (Airport Meteorological Center) at Yelizovo Airport and the Tokyo Volcanic Ash Advisory Center (VAAC), the

  5. SOURCES OF QUATERNARY POTASSIC VOLCANIC ROCKS FROM WUDALIANCHI, CHINA: CONTROL BY TRANSTENSION AT THE LITHOSPHERE–ASTHENOSPHERE BOUNDARY LAYER

    Directory of Open Access Journals (Sweden)

    S. V. Rasskazov

    2016-01-01

    the first volcano (Wohushan fall within the data field of background rocks. Rock compositions of the second and third volcanoes (Bijiashan and Laoheishan changed on each of them from similar to the background to the ones distinguished by the lower silica and alkalis contents. On the Bijiashan volcano, eruptions were exhibited by trachyandesites of a lava shield and by basaltic trachyandesites and phonotephrites of a volcanic cone. The trachyandesites were comparable to the background rocks, the basaltic trachyandesites and phonotephrites differed from them. On the Laoheishan volcano, rocks were subdivided into three groups: (1 basaltic trachyandesites and phonotephrites, (2 trachyandesites, and (3 phonotephrites. The first group was recorded in pyroclastic material from the late volcanic cone and lavas from the northern bocca, the second group in pyroclastic material from the northwestern edge of the late crater, and the third group in bombs from its southwestern edge. On the fourth volcano (Huoshaoshan, rocks are basaltic trachyandesites and phonotephrites.In terms of Na2O, K2O, and SiO2 contents, peripheral lavas of volcanic fans in the Bijiashan, Laoheishan, and Huoshaoshan volcanoes were close to background rocks. The contents of these oxides, differed from the background signatures, characterize rocks from volcanic cones in a linear progression that demonstrates the transition from compositions of the Wohushan volcano, close to background ones, through the intermediate values in the Bijiashan and Laoheishan volcanoes to the final compositions in the Huoshaoshan volcanic cone.In the background rocks, K2O concentrations range from 4.8 to 6.0 wt % with its relative decrease in the rocks of the beginning and end of volcanic evolution. Initial lava flows with K2O contents as low as 4.0 wt % erupted along the Laoshantou – Old Gelaqiushan north-south locus from 2.5 to 2.0 Ma and in the final cone of the Huoshaoshan volcano, erupted in 1721, fell to 3.2 wt %. Since 1

  6. Volcanism Studies: Final Report for the Yucca Mountain Project

    Energy Technology Data Exchange (ETDEWEB)

    Bruce M. Crowe; Frank V. Perry; Greg A. Valentine; Lynn M. Bowker

    1998-12-01

    This report synthesizes the results of volcanism studies conducted by scientists at the Los Alamos National Laboratory and collaborating institutions on behalf of the Department of Energy's Yucca Mountain Project. An assessment of the risk of future volcanic activity is one of many site characterization studies that must be completed to evaluate the Yucca Mountain site for potential long-term storage of high-level radioactive waste. The presence of several basaltic volcanic centers in the Yucca Mountain region of Pliocene and Quaternary age indicates that there is a finite risk of a future volcanic event occurring during the 10,000-year isolation period of a potential repository. Chapter 1 introduces the volcanism issue for the Yucca Mountain site and provides the reader with an overview of the organization, content, and significant conclusions of this report. The risk of future basaltic volcanism is the primary topic of concern including both events that intersect a potential repository and events that occur near or within the waste isolation system of a repository. Future volcanic events cannot be predicted with certainty but instead are estimated using formal methods of probabilistic volcanic hazard assessment (PVHA). Chapter 2 describes the volcanic history of the Yucca Mountain region (YMR) and emphasizes the Pliocene and Quaternary volcanic record, the interval of primary concern for volcanic risk assessment. The distribution, eruptive history, and geochronology of Plio-Quaternary basalt centers are described by individual center emphasizing the younger postcaldera basalt (<5 Ma). The Lathrop Wells volcanic center is described in detail because it is the youngest basalt center in the YMR. The age of the Lathrop Wells center is now confidently determined to be about 75 thousand years old. Chapter 3 describes the tectonic setting of the YMR and presents and assesses the significance of multiple alternative tectonic models. The Crater Flat volcanic zone is

  7. Paleoarchean trace fossils in altered volcanic glass.

    Science.gov (United States)

    Staudigel, Hubert; Furnes, Harald; DeWit, Maarten

    2015-06-02

    Microbial corrosion textures in volcanic glass from Cenozoic seafloor basalts and the corresponding titanite replacement microtextures in metamorphosed Paleoarchean pillow lavas have been interpreted as evidence for a deep biosphere dating back in time through the earliest periods of preserved life on earth. This interpretation has been recently challenged for Paleoarchean titanite replacement textures based on textural and geochronological data from pillow lavas in the Hooggenoeg Complex of the Barberton Greenstone Belt in South Africa. We use this controversy to explore the strengths and weaknesses of arguments made in support or rejection of the biogenicity interpretation of bioalteration trace fossils in Cenozoic basalt glasses and their putative equivalents in Paleoarchean greenstones. Our analysis suggests that biogenicity cannot be taken for granted for all titanite-based textures in metamorphosed basalt glass, but a cautious and critical evaluation of evidence suggests that biogenicity remains the most likely interpretation for previously described titanite microtextures in Paleoarchean pillow lavas.

  8. A remote control neutron cone scanner and measurement of the d(T,n) α neutron cone

    International Nuclear Information System (INIS)

    Suwanakachorn, D.; Vilaithong, T.; Vilaithong, C.; Boonyawan, D.; Chimooy, T.; Sornphorm, P.; Hoyce, G.; Pairsuwan, W.; Singkarat, S.

    1988-01-01

    We have measured the neutron cone associated with alpha particles from the d(T,n)α reaction by using a remote-control cone scanner. This scanner has two principal parts. The first part is the neutron detector scanner which can move the detector in the horizontal and vertical axis using to stepping-motors. The neutron detector can be moved in 0.5 cm increments over the whole rage of 30 cm. The second part is the remote-control electronic circuit using digital ICs. The rotation of stepping-motors is controlled by pulse signals from this circuit and the position of the detector is known by counting the number of pulses. The position of the neutron detector is indicated directly on a 3 digit display at the control panel. The method of measuring the neutron cone by the Time-of-Flight technique is also described

  9. Intracaldera volcanism and sedimentation - Creede Caldera, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Heiken, G.; Krier, D.; Snow, M.G. [and others

    1997-06-01

    Within the Creede caldera, Colorado, many of the answers to its postcaldera volcanic and sedimentary history lie within the sequence of tuffaceous elastic sedimentary rocks and tuffs known as the Creede Formation. The Creede Formation and its interbedded ash deposits were sampled by research coreholes Creede 1 and 2, drilled during the fall of 1991. In an earlier study of the Creede Formation, based on surface outcrops and shallow mining company coreholes, Heiken and Krier concluded that the process of caldera structural resurgence was rapid and that a caldera lake had developed in an annulus ({open_quotes}moat{close_quotes}) located between the resurgent dome and caldera wall. So far we have a picture of intracaldera activity consisting of intermittent hydrovolcanic eruptions within a caldera lake for the lower third of the Creede Formation, and both magmatic and hydrovolcanic ash eruptions throughout the top two-thirds. Most of the ash deposits interbedded with the moat sedimentary rocks are extremely fine-grained. Ash fallout into the moat lake and unconsolidated ash eroded from caldera walls and the slopes of the resurgent dome were deposited over stream delta distributaries within relatively shallow water in the northwestern moat, and in deeper waters of the northern moat, where the caldera was intersected by a graben. Interbedded with ash beds and tuffaceous siltstones are coarse-grained turbidites from adjacent steep slopes and travertine from fissure ridges adjacent to the moat. Sedimentation rates and provenance for elastic sediments are linked to the frequent volcanic activity in and near the caldera; nearly all of the Creede Formation sedimentary rocks are tuffaceous.

  10. Gravimetric control of active volcanic processes

    Science.gov (United States)

    Saltogianni, Vasso; Stiros, Stathis

    2017-04-01

    Volcanic activity includes phases of magma chamber inflation and deflation, produced by movement of magma and/or hydrothermal processes. Such effects usually leave their imprint as deformation of the ground surfaces which can be recorded by GNSS and other methods, on one hand, and on the other hand they can be modeled as elastic deformation processes, with deformation produced by volcanic masses of finite dimensions such as spheres, ellipsoids and parallelograms. Such volumes are modeled on the basis of inversion (non-linear, numerical solution) of systems of equations relating the unknown dimensions and location of magma sources with observations, currently mostly GNSS and INSAR data. Inversion techniques depend on the misfit between model predictions and observations, but because systems of equations are highly non-linear, and because adopted models for the geometry of magma sources is simple, non-unique solutions can be derived, constrained by local extrema. Assessment of derived magma models can be provided by independent observations and models, such as micro-seismicity distribution and changes in geophysical parameters. In the simplest case magmatic intrusions can be modeled as spheres with diameters of at least a few tens of meters at a depth of a few kilometers; hence they are expected to have a gravimetric signature in permanent recording stations on the ground surface, while larger intrusions may also have an imprint in sensors in orbit around the earth or along precisely defined air paths. Identification of such gravimetric signals and separation of the "true" signal from the measurement and ambient noise requires fine forward modeling of the wider areas based on realistic simulation of the ambient gravimetric field, and then modeling of its possible distortion because of magmatic anomalies. Such results are useful to remove ambiguities in inverse modeling of ground deformation, and also to detect magmatic anomalies offshore.

  11. Professional conduct of scientists during volcanic crises

    Science.gov (United States)

    IAVCEI SubcommitteeCrisis Protocols; Newhall, Chris; Aramaki, Shigeo; Barberi, Franco; Blong, Russell; Calvache, Marta; Cheminee, Jean-Louis; Punongbayan, Raymundo; Siebe, Claus; Simkin, Tom; Sparks, Stephen; Tjetjep, Barry; Newhall, Chris

    Stress during volcanic crises is high, and any friction between scientists can distract seriously from both humanitarian and scientific effort. Friction can arise, for example, if team members do not share all of their data, if differences in scientific interpretation erupt into public controversy, or if one scientist begins work on a prime research topic while a colleague with longer-standing investment is still busy with public safety work. Some problems arise within existing scientific teams; others are brought on by visiting scientists. Friction can also arise between volcanologists and public officials. Two general measures may avert or reduce friction: (a) National volcanologic surveys and other scientific groups that advise civil authorities in times of volcanic crisis should prepare, in advance of crises, a written plan that details crisis team policies, procedures, leadership and other roles of team members, and other matters pertinent to crisis conduct. A copy of this plan should be given to all current and prospective team members. (b) Each participant in a crisis team should examine his or her own actions and contribution to the crisis effort. A personal checklist is provided to aid this examination. Questions fall generally in two categories: Are my presence and actions for the public good? Are my words and actions collegial, i.e., courteous, respectful, and fair? Numerous specific solutions to common crisis problems are also offered. Among these suggestions are: (a) choose scientific team leaders primarily for their leadership skills; (b) speak publicly with a single scientific voice, especially when forecasts, warnings, or scientific disagreements are involved; (c) if you are a would-be visitor, inquire from the primary scientific team whether your help would be welcomed, and, in general, proceed only if the reply is genuinely positive; (d) in publications, personnel evaluations, and funding, reward rather than discourage teamwork. Models are

  12. Bifurcation of volcanic plumes in a crosswind

    Science.gov (United States)

    Ernst, Gerald G. J.; Davis, John P.; Sparks, R. Stephen J.

    1994-08-01

    Bent-over buoyant jets distorted by a crosscurrent develop a vortex pair structure and can bifurcate to produce two distinct lobes which diverge from one another downwind. The region downwind of the source between the lobes has relatively low proportions of discharged fluid. Factors invoked by previous workers to cause or enhance bifurcation include buoyancy, release of latent heat at the plume edge by evaporating water droplets, geometry and orientation of the source, and the encounter with a density interface on the rising path of the plume. We suggest that the pressure distribution around the vortex pair of a rising plume may initially trigger bifurcation. We also report new experimental observations confirming that bifurcation becomes stronger for stronger bent-over plumes, identifying that bifurcation can also occur for straight-edged plumes but gradually disappears for stronger plumes which form a gravity current at their final level and spread for a significant distance against the current. Observations from satellites and the ground are reviewed and confirm that volcanic plumes can show bifurcation and a large range of bifurcation angles. Many of the bifurcating plumes spread out at the tropopause level and suggest the tropopause may act on the plumes as a density interface enhancing bifurcation. Even for quite moderate bifurcation angles, the two plume lobes become rapidly separated downwind by distances of tens of kilometers. Such bifurcating plumes drifting apart can only result in bilobate tephra fall deposits. The tephra fall deposit from the 16 km elevation, SE spreading, bifurcating volcanic plume erupted on 15 May 1981 from Mt Pagan was sampled by previous workers and clearly displayed bilobate characteristics. Examples of bilobate tephra fall deposits are reviewed and their origin briefly discussed. Bilobate deposits are common and may result from many causes. Plume bifurcation should be considered one of the possible mechanisms which can account

  13. Electrochemical sensor monitoring of volcanic gases

    Science.gov (United States)

    Roberts, Tjarda; Freshwater, Ray; Oppenheimer, Clive; Saffell, John; Jones, Rod; Griffiths, Paul; Braban, Christine; Mead, Iqbal

    2010-05-01

    Advances in instrumentation have fuelled a recent growth of interest in using portable sensor systems for environmental monitoring of pollution. Developments in wireless technology are enabling such systems to operate remotely and autonomously, generating a wealth of environmental data. We report here on the application of miniature Alphasense electrochemical sensors to the detection and characterisation of gases in volcanic plumes. A highly portable sensor system was developed to operate an array of 6 low cost electrochemical sensors to detect CO, H2, HCl, SO2, H2S and NO2 at 1 Hz. A miniature pump draws air over all sensors simultaneously (i.e. sensors arranged in parallel). The sensor output in these campaigns was logged on PDAs for real-time viewing, and later download (with a view to future data-streaming). The instrument was deployed at a number of volcanoes and was subject to extremely harsh conditions including highly acidic environments, low (Antarctic) temperatures, and transport over rough terrain. Analysis methods are demonstrated that consider calibration, cross-sensitivities of the sensors to multiple gases, differing sensor response times, temperature dependence, and background sensor drift with time. The analysis is applied to a range of plume field-measurements to extract gas concentrations ranging from 100's ppmv to sub-ppmv and to characterise the individual volcano emissions. Applications of similar sensor systems for real-time long-term monitoring of volcanic emissions (which may indicate and ultimately predict eruptive behavior), and UAV and balloon-borne plume sampling are now already being realised. This work focused on demonstrating the application of electrochemical sensors to monitoring of environmental pollution from volcanoes. Other applications for similar sensors include the near-source monitoring of industrial emissions, and of pollutant levels enhanced by traffic emissions in the urban environment.

  14. Intraretinal variability and specialization of cones in Japanese anchovy (Engraulis japonicus, Engraulidae).

    Science.gov (United States)

    Kondrashev, S L; Kornienko, M S; Gnyubkina, V P; Frolova, L T

    2016-04-01

    The retina of anchovies is characterized by an unusual arrangement and ultrastructure of cones. In the retina of Japanese anchovies, Engraulis japonicus, three types of cones are distributed into rows. The nasal, central, temporal, and ventro-temporal regions of the retina were occupied exclusively by the long and short cones. Triple cones, made up of two lateral components and one smaller central component, were found only in the dorsal and ventro-nasal retinal regions. In the outer segments of all short and long cones from the ventro-temporal region, the lamellae were oriented along the cell axis and were perpendicular to the lamellae in the long cones, providing a morphological basis for the detection of polarization. This lamellar orientation is unique to all vertebrates. The cones were examined with respect to regional differentiation in their size and spectral properties via light microscopy, transmission electron microscopy, and microspectrophotometry. Various dimensions of cones were measured in preparations of isolated cells. The cones from the ventro-temporal region had different dimensions than cones of the same type located in other retinal regions. Triple cones from the dorsal region were significantly larger than triple cones from the ventro-nasal region. The spectral absorbance of the lateral components of triple cones in the ventro-nasal retina was identical to the absorbance of all long and short cones from the ventro-temporal region. These are shifted to shorter wavelengths relative to the absorbance of the lateral components of the triple cones located in the dorsal retina. Thus, the retina of the Japanese anchovy shows some features of regional specialization common in other fishes that improves spatial resolution for the upwards and forwards visual axis and provides spectral tuning in downwelling light environment. That results from the differentiation of cone types by size and by different spectral sensitivity of various retinal areas. © 2016

  15. Volcanic history and petrography of the Pliocene Etrüsk Stratovolcano, E Turkey

    Science.gov (United States)

    Oyan, Vural; Keskin, Mehmet; Lebedev, Vladimir; Sharkov, Evgenii; Lustrino, Michele; Mattioli, Michele

    2010-05-01

    The Pliocene Etrusk volcano, with its 3100 m elevation and ~500 km2 area, is one of the major centers of the collision-related volcanism in E Anatolia. It is located in the northeast of Lake Van, sitting almost on the culmination of the "Lake Van dome" structure forming the vertex of the eastern Turkish high plateau (Sengor et al., 2008). A ~5-km-wide horseshoe-shaped caldera, open to the south, is located in the center of the volcano. Apart from two trace element analyses and two K/Ar dates, there are virtually no data available in the literature on this major erup