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Sample records for juan caldera cluster

  1. Central San Juan caldera cluster: regional volcanic framework

    Science.gov (United States)

    Lipman, Peter W.

    2000-01-01

    Eruption of at least 8800 km3 of dacitic-rhyolitic magma as 9 major ash-slow sheets (individually 150-5000 km3) was accompanied by recurrent caldera subsidence between 28.3 and about 26.5 Ma in the central San Juan Mountains, Colorado. Voluminous andesitic-decitic lavas and breccias were erupted from central volcanoes prior to the ash-flow eruptions, and similar lava eruptions continued within and adjacent to the calderas during the period of explosive volcanism, making the central San Juan caldera cluster an exceptional site for study of caldera-related volcanic processes. Exposed calderas vary in size from 10 to 75 km in maximum diameter, the largest calderas being associated with the most voluminous eruptions. After collapse of the giant La Garita caldera during eruption if the Fish Canyon Tuff at 17.6 Ma, seven additional explosive eruptions and calderas formed inside the La Garita depression within about 1 m.y. Because of the nested geometry, maximum loci of recurrently overlapping collapse events are inferred to have subsided as much as 10-17 km, far deeper than the roof of the composite subvolcanic batholith defined by gravity data, which represents solidified caldera-related magma bodies. Erosional dissection to depths of as much as 1.5 km, although insufficient to reach the subvolcanic batholith, has exposed diverse features of intracaldera ash-flow tuff and interleaved caldera-collapse landslide deposits that accumulated to multikilometer thickness within concurrently subsiding caldera structures. The calderas display a variety of postcollapse resurgent uplift structures, and caldera-forming events produced complex fault geometries that localized late mineralization, including the epithermal base- and precious-metal veins of the well-known Creede mining district. Most of the central San Juan calderas have been deeply eroded, and their identification is dependent on detailed geologic mapping. In contrast, the primary volcanic morphology of the

  2. Geologic Map of the Central San Juan Caldera Cluster, Southwestern Colorado

    Science.gov (United States)

    Lipman, Peter W.

    2006-01-01

    The San Juan Mountains are the largest erosional remnant of a composite volcanic field that covered much of the southern Rocky Mountains in middle Tertiary time. The San Juan field consists mainly of intermediate-composition lavas and breccias, erupted about 35-30 Ma from scattered central volcanoes (Conejos Formation) and overlain by voluminous ash-flow sheets erupted from caldera sources. In the central San Juan Mountains, eruption of at least 8,800 km3 of dacitic-rhyolitic magma as nine major ash flow sheets (individually 150-5,000 km3) was accompanied by recurrent caldera subsidence between 28.3 Ma and about 26.5 Ma. Voluminous andesitic-dacitic lavas and breccias erupted from central volcanoes prior to the ash-flow eruptions, and similar lava eruptions continued within and adjacent to the calderas during the period of more silicic explosive volcanism. Exposed calderas vary in size from 10 to 75 km in maximum dimension; the largest calderas are associated with the most voluminous eruptions.

  3. Geologic map of the central San Juan caldera cluster, southwestern Colorado

    Science.gov (United States)

    Lipman, Peter W.

    2006-01-01

    The San Juan Mountains are the largest erosional remnant of a composite volcanic field that covered much of the southern Rocky Mountains in middle Tertiary time. The San Juan field consists mainly of intermediate-composition lavas and breccias, erupted about 35-30 Ma from scattered central volcanoes (Conejos Formation) and overlain by voluminous ash-flow sheets erupted from caldera sources. In the central San Juan Mountains, eruption of at least 8,800 km3 of dacitic-rhyolitic magma as nine major ash flow sheets (individually 150-5,000 km3) was accompanied by recurrent caldera subsidence between 28.3 Ma and about 26.5 Ma. Voluminous andesitic-dacitic lavas and breccias erupted from central volcanoes prior to the ash-flow eruptions, and similar lava eruptions continued within and adjacent to the calderas during the period of more silicic explosive volcanism. Exposed calderas vary in size from 10 to 75 km in maximum dimension; the largest calderas are associated with the most voluminous eruptions.

  4. Determining the physical processes behind four large eruptions in rapid sequence in the San Juan caldera cluster (Colorado, USA)

    Science.gov (United States)

    Curry, Adam; Caricchi, Luca; Lipman, Peter

    2017-04-01

    Large, explosive volcanic eruptions can have both immediate and long-term negative effects on human societies. Statistical analyses of volcanic eruptions show that the frequency of the largest eruptions on Earth (> ˜450 km3) differs from that observed for smaller eruptions, suggesting different physical processes leading to eruption. This project will characterize the petrography, whole-rock geochemistry, mineral chemistry, and zircon geochronology of four caldera-forming ignimbrites from the San Juan caldera cluster, Colorado, to determine the physical processes leading to eruption. We collected outflow samples along stratigraphy of the three caldera-forming ignimbrites of the San Luis caldera complex: the Nelson Mountain Tuff (>500 km3), Cebolla Creek Tuff (˜250 km3), and Rat Creek Tuff (˜150 km3); and we collected samples of both outflow and intracaldera facies of the Snowshoe Mountain Tuff (>500 km3), which formed the Creede caldera. Single-crystal sanidine 40Ar/39Ar ages show that these eruptions occurred in rapid succession between 26.91 ± 0.02 Ma (Rat Creek) and 26.87 ± 0.02 Ma (Snowshoe Mountain), providing a unique opportunity to investigate the physical processes leading to a rapid sequence of large, explosive volcanic eruptions. Recent studies show that the average flux of magma is an important parameter in determining the frequency and magnitude of volcanic eruptions. High-precision isotope-dilution thermal ionization mass spectrometry (ID-TIMS) zircon geochronology will be performed to determine magma fluxes, and cross-correlation of chemical profiles in minerals will be performed to determine the periodicity of magma recharge that preceded these eruptions. Our project intends to combine these findings with similar data from other volcanic regions around the world to identify physical processes controlling the regional and global frequency-magnitude relationships of volcanic eruptions.

  5. Revised volcanic history of the San Juan, Uncompahgre, Silverton, and Lake City calderas in the western San Juan Mountains, Colorado

    Science.gov (United States)

    Lipman, Peter W.; Steven, Thomas A.; Luedke, Robert G.; Burbank, Wilbur

    1973-01-01

    The sequence of mid-Cenozoic volcanic events in the western San Juan Mountains is closely analogous to that elsewhere in the San Juan volcanic field. The Lake Fork, Picayune, and San Juan Formations were erupted from a cluster of central volcanoes from 35 to 30 m.y. ago, when dominant activity shifted to more silicic ash-flow eruptions with accompanying caldera collapses. The Uncompahgre and San Juan calderas, each about 20 km across, formed mainly from eruption of the 28-m.y.-old Sapinero Mesa Tuff. Collapse occurred concurrently with eruption, and intracaldera tuffs accumulated to a thickness of more than 700 m. Both calderas were resurgently domed together; the northeast-trending Eureka graben formed along the distended crest of that dome. The Uncompahgre caldera was then flooded by several 27- to 28-m.y.-old ash-flow sheets from easterly sources, and also by one apparently erupted from the Silverton caldera nested within the older San Juan caldera. The Lake City caldera, located within the older Uncompahgre caldera, formed about 22.5 m.y. ago in response to eruption of the Sunshine Peak Tuff.

  6. Geologic map of the Cochetopa Park and North Pass Calderas, northeastern San Juan Mountains, Colorado

    Science.gov (United States)

    Lipman, Peter W.

    2012-01-01

    The San Juan Mountains in southwestern Colorado have long been known as a site of exceptionally voluminous mid-Tertiary volcanism, including at least 22 major ignimbrite sheets (each 150-5,000 km3) and associated caldera structures active at 33-23 Ma. Recent volcanologic and petrologic studies in the San Juan region have focused mainly on several ignimbrite-caldera systems: the southeastern area (Platoro complex), western calderas (Uncompahgre-Silverton-Lake City), and the central cluster (La Garita-Creede calderas). Far less studied has been the northeastern San Juan region, which occupies a transition between earlier volcanism in central Colorado and large-volume younger ignimbrite-caldera foci farther south and west. The present map is based on new field coverage of volcanic rocks in seventeen 7.5' quadrangles in northeastern parts of the volcanic field, high-resolution age determinations for 120 new sites, and petrologic studies involving several hundred new chemical analyses. This mapping and the accompanying lab results (1) document volcanic evolution of the previously unrecognized North Pass caldera and the morphologically beautifully preserved but enigmatic Cochetopa basin, including unique features not previously described from ignimbrite calderas elsewhere; (2) provide evidence for a more rapid recurrence of large ignimbrite eruptions than previously known elsewhere; (3) quantify the regional time-space-volume progression from the earlier Sawatch magmatic trend southward into the San Juan region; and (4) permit more rigorous comparison between the broad mid-Tertiary magmatic belt in the western U.S. Cordillera and the type continental-margin arc volcanism in the central Andes.

  7. Eruptive and noneruptive calderas, northeastern San Juan Mountains, Colorado: Where did the ignimbrites come from?

    Science.gov (United States)

    Lipman, P.W.; McIntosh, W.C.

    2008-01-01

    The northeastern San Juan Mountains, the least studied portion of this well-known segment of the Southern Rocky Mountains Volcanic Field are the site of several newly identified and reinterpreted ignimbrite calderas. These calderas document some unique eruptive features not described before from large volcanic systems elsewhere, as based on recent mapping, petrologic data, and a large array of newly determined high-precision, laser-fusion 40Ar/39Ar ages (140 samples). Tightly grouped sanidine ages document exceptionally brief durations of 50-100 k.y. or less for individual Oligocene caldera cycles; biotite ages are more variable and commonly as much as several hundred k.y. older than sanidine from the same volcanic unit. A previously unknown ignimbrite caldera at North Pass, along the Continental Divide in the Cochetopa Hills, was the source of the newly distinguished 32.25-Ma Saguache Creek Tuff (???400-500 km3). This regionally, distinctive crystal-poor alkalic rhyolite helps fill an apparent gap in the southwestward migration from older explosive activity, from calderas along the N-S Sawatch locus in central Colorado (youngest, Bonanza Tuff at 33.2 Ma), to the culmination of Tertiary volcanism in the San Juan region, where large-volume ignimbrite eruptions started at ca. 29.5 Ma and peaked with the enormous Fish Canyon Tuff (5000 km3) at 28.0 Ma. The entire North Pass cycle, including caldera-forming Saguache Creek Tuff, thick caldera-filling lavas, and a smaller volume late tuff sheet, is tightly bracketed at 32.25-32.17 Ma. No large ignimbrites were erupted in the interval 32-29 Ma, but a previously unmapped cluster of dacite-rhyolite lava flows and small tuffs, areally associated with a newly recognized intermediate-composition intrusion 5 ?? 10 km across (largest subvolcanic intrusion in San Juan region) centered 15 km north of the North Pass caldera, marks a near-caldera-size silicic system active at 29.8 Ma. In contrast to the completely filled North Pass

  8. Pyroclastic eruptions from Axial caldera, Juan de Fuca Ridge, NE Pacific Ocean

    Energy Technology Data Exchange (ETDEWEB)

    Helo, Christoph; Stix, John [Department of Earth and Planetary Sciences, McGill University, 3450 University Street, Montreal, Quebec H3A 2A7 (Canada); Clague, Dave A [Monterey Bay Aquarium Research Institute 7700 Sandholdt Road, Moss Landing, CA 95039-9644 (United States)

    2008-10-01

    Unconsolidated volcaniclastic glass deposits on the flanks of Axial Seamount, a caldera system situated on the Juan de Fuca Ridge in the NE Pacific Ocean, demonstrate the occurrence of explosive events, in addition to effusive activity. The variety of produced glass fragments ranges from various angular forms to thin deep-sea limu o Pele, with dominantly moderately fractionated to occasionally primitive MOR basalt composition. A model involving the collapse of a magmatic foam layer may account for the observed spectrum of glass fragments.

  9. How Frequently Can a "Supervolcano" Erupt? Rapid Emplacement of Voluminous Compositionally Diverse Ignimbrites, Central San Juan Calderas, Colorado

    Science.gov (United States)

    Lipman, P. W.; McIntosh, W. C.

    2006-12-01

    High-resolution single-crystal laser-fusion 40Ar/39Ar age determinations on sanidine phenocrysts document sequential eruption of four multi-hundred cubic-kilometer ignimbrites and associated lavas flows from calderas in the central San Juan Mountains, Colorado within a cumulative time interval of less than 50-100 ka. The tight recurrence interval was not evident from previous incremental-heating 40Ar/39Ar plateau ages, which were stratigraphically inconsistent on time scales beyond analytical precision. The new single- crystal results show that three tuff sheets, Rat Creek (>150 km3), Cebolla Creek (>250 km3), and Nelson Mountain Tuffs Creek (>500 km3) from spatially overlapping sources in the San Luis- Cochetopa caldera complex, erupted between 26.92±0.05 and 26.91±0.03 Ma (9 separate samples). A sequence of four postcollapse lavas at Cochetopa erupted at 26.86±0.04 Ma (6 samples) while an andesitic stratocone grew within San Luis caldera complex. Concurrently, Snowshoe Mountain Tuff (>500 km3) erupted from the Creede caldera, 20 km to the south, at 26.87±0.05 Ma (5 samples). Within this limited time interval, eruptive compositions fluctuated widely. Rat Creek and Nelson Mountain Tuffs are compositionally zoned from crystal-poor low-Si rhyolite to cpx-bearing dacite, while the intervening Cebolla Creek Tuff is uniform mafic hbl-rich dacite. Cochetopa Dome lavas are nearly aphyric high-Si rhyolite, while Snowshoe Mountain Tuff is crystal-rich low-Si cpx-bearing dacite. For comparison, four ignimbrites from Aso caldera in southern Japan, with a cumulative volume of ~300 km3, erupted at 270, 140, 120, and 90 ka (Nakada et al., 2003); four overlapping caldera collapses at Santorini in the Aegean were each associated with silicic tuff with volumes of several tens of kilometers, at 203, ~100, 21, and 3.6 ka (Druitt, 1999). In contrast, larger "supervolcano" systems, such as Yellowstone, commonly have repose periods of 0.5- 1x106 m.y., even when eruptive compositions

  10. AUV Mapping of Axial Seamount, Juan de Fuca Ridge: The Southern Caldera Floor and Upper South Rift

    Science.gov (United States)

    Clague, D. A.; Caress, D.; Paduan, J. B.; Chadwick, W. W.; Butterfield, D. A.; Thomas, H.; Conlin, D.; Thompson, D. R.

    2007-12-01

    During September 2006 and August 2007 NOAA NeMO cruises, we conducted 7 high-resolution near-bottom seafloor mapping surveys of Axial Seamount using the MBARI Mapping AUV D. Allan B. The 200 kHz multibeam and 110 kHz sidescan surveys of the south caldera and upper south rift, conducted at 50 m vehicle altitude, achieved sub-meter resolution bathymetry and sidescan imagery. Numerous previous and concurrent submersible or ROV dives provide ground-truth of what the maps depict. A companion poster presents the AUV surveys of the north caldera and northeastern caldera rim. The southern caldera wall is buried beneath at least 5 voluminous lava flows, including the 1998 flow, each erupted from fissures extending along the southeastern edge of the caldera roughly parallel to the upper south rift zone. The caldera wall here was not as tall as on the southwest, north, and northeast of the caldera, and may have been as low as 35 m tall before it was buried. Active and inactive hydrothermal vents are generally located along the inferred buried caldera wall. Eruptive fissures are characterized by series of depressions aligned along each fissure; no ramparts or other constructional edifices were constructed along them. The aligned depressions suggest that lava drained back down the fissures at the end of the eruptions. The fissure eruptions were large volume and had large effusion rates as seen by their interwoven channels and the extent of the flows. Most of these flows have central channels of lineated sheet flows, bordered by folded and then jumbled sheet flows, surrounded by lobate flows with lava pillars and collapse structures and pillowed flow margins. As an example, the 1998 eruption in and near the caldera issued from 5 en echelon fissures extending at least 3 km. The largest flow lobe extending to the south was mapped along its entire western boundary using JASON II, but the flow extends to the southeast beyond the mapped region. An unusual km-across feature was mapped

  11. Rhyolitic calderas and centers clustered within the active andesitic belt of Ecuador's Eastern Cordillera

    Energy Technology Data Exchange (ETDEWEB)

    Mothes, Patricia A; Hall, Minard L [Instituto Geofisico, Escuela Politecnica Nacional, Quito (Ecuador)], E-mail: pmothes@igepn.edu.ec

    2008-10-01

    In the Ecuadorian volcanic arc a cluster of scattered rhyolitic and dacitic centers within the mainly andesitic Eastern Cordillera includes large caldera structures (Chalupas, Chacana, Cosanga) as well as smaller edifices, built upon the Paleozoic-Mesozoic metamorphic basement. At the Chacana caldera magmatism dates from 2.7 Ma to historic times. These centers erupted enormous ash flows and thick pumice lapilli falls that covered the InterAndean Valley near Quito. The role of the 50-70 km-thick crust with a notable negative gravity anomaly appears to be related to the generation of this highly silicic magmatism occurring along the crest of the Andes in the NVZ.

  12. Calderas and mineralization: volcanic geology and mineralization in the Chianti caldera complex, Trans-Pecos Texas

    Energy Technology Data Exchange (ETDEWEB)

    Duex, T.W.; Henry, C.D.

    1981-01-01

    This report describes preliminary results of an ongoing study of the volcanic stratigraphy, caldera activity, and known and potential mineralization of the Chinati Mountains area of Trans-Pecos Texas. Many ore deposits are spatially associated with calderas and other volcanic centers. A genetic relationship between calderas and base and precious metal mineralization has been proposed by some and denied by others. Steven and others have demonstrated that calderas provide an important setting for mineralization in the San Juan volcanic field of Colorado. Mineralization is not found in all calderas but is apparently restricted to calderas that had complex, postsubsidence igneous activity. A comparison of volcanic setting, volcanic history, caldera evolution, and evidence of mineralization in Trans-Pecos to those of the San Juan volcanic field, a major mineral producer, indicates that Trans-Pecos Texas also could be an important mineralized region. The Chianti caldera complex in Trans-Pecos Texas contains at least two calderas that have had considerable postsubsidence activity and that display large areas of hydrothermal alteration and mineralization. Abundant prospects in Trans-Pecos and numerous producing mines immediately south of the Trans-Pecos volcanic field in Mexico are additional evidence that ore-grade deposits could occur in Texas.

  13. Collapse calderas

    Science.gov (United States)

    Aguirre-Diaz, G. J.; Marti, J.

    2007-05-01

    A collapse caldera is a volcanic explosive structure that forms during the collapse of crustal blocks on top of a shallow magma chamber. During this collapse, a large volume of magma is evacuated, first explosively, in the form of pyroclastic fallouts and pyroclastic flows, and then effusively, as lava domes or flows after collapse. The result is a catastrophic explosive volcanic collapse that forms a depression that could end with different shapes, circular, oval, rectangular, or irregular. Three main types of collapse calderas can be defined, 1) summit caldera, 2) classic caldera, and 3) graben caldera. Summit calderas are those formed at the top of large volcanoes and are related to relatively small-volume pyroclastic products that include plinian fallouts and ignimbrites, such as Crater Lake, Las Cañadas, and Somma-Vesuvio. Classic calderas are semi-circular to irregular-shaped large structures, several km in diameter that are related to relatively large-volume pyroclastic products including pumice fallouts and widespread ignimbrites, such as Long-Valley, Campi Flegrei, and Los Humeros. Graben calderas are explosive volcano-tectonic collapse structures from which large-volume, ignimbrite-forming eruptions occurred through several vents along the graben walls and the intra-graben block faults causing the collapse of the graben or of a sector of the graben. The main products of graben calderas are surge-deposits and large-volume widespread ignimbrite sheets. Pumice fallouts are practically absent. Examples include the Sierra Madre Occidental in Mexico, La Pacana (Andes), Catalan Pyrenees, and perhaps Scafell (United Kingdom). Any of the three caldera types mentioned above could have collapsed in three different ways, 1) piston, when the collapse occurs as a single crustal block; 2) trap-door, when collapse occurs unevenly along one side while the opposite side remains with no collapse; 3) piece-meal, when collapse occurs as broken pieces of the crust on top of

  14. Contemporaneous trachyandesitic and calc-alkaline volcanism of the Huerto Andesite, San Juan Volcanic Field, Colorado, USA

    Science.gov (United States)

    Parat, F.; Dungan, M.A.; Lipman, P.W.

    2005-01-01

    Locally, voluminous andesitic volcanism both preceded and followed large eruptions of silicic ash-flow tuff from many calderas in the San Juan volcanic field. The most voluminous post-collapse lava suite of the central San Juan caldera cluster is the 28 Ma Huerto Andesite, a diverse assemblage erupted from at least 5-6 volcanic centres that were active around the southern margins of the La Garita caldera shortly after eruption of the Fish Canyon Tuff. These andesitic centres are inferred, in part, to represent eruptions of magma that ponded and differentiated within the crust below the La Garita caldera, thereby providing the thermal energy necessary for rejuvenation and remobilization of the Fish Canyon magma body. The multiple Huerto eruptive centres produced two magmatic series that differ in phenocryst mineralogy (hydrous vs anhydrous assemblages), whole-rock major and trace element chemistry and isotopic compositions. Hornblende-bearing lavas from three volcanic centres located close to the southeastern margin of the La Garita caldera (Eagle Mountain - Fourmile Creek, West Fork of the San Juan River, Table Mountain) define a high-K calc-alkaline series (57-65 wt % SiO2) that is oxidized, hydrous and sulphur rich. Trachyandesitic lavas from widely separated centres at Baldy Mountain-Red Lake (western margin), Sugarloaf Mountain (southern margin) and Ribbon Mesa (20 km east of the La Garita caldera) are mutually indistinguishable (55-61 wt % SiO2); they are characterized by higher and more variable concentrations of alkalis and many incompatible trace elements (e.g. Zr, Nb, heavy rare earth elements), and they contain anhydrous phenocryst assemblages (including olivine). These mildly alkaline magmas were less water rich and oxidized than the hornblende-bearing calc-alkaline suite. The same distinctions characterize the voluminous precaldera andesitic lavas of the Conejos Formation, indicating that these contrasting suites are long-term manifestations of San Juan

  15. Heat flux measured acoustically at Grotto Vent, a hydrothermal vent cluster on the Endeavour Segment, Juan de Fuca Ridge

    Science.gov (United States)

    Xu, G.; Jackson, D. R.; Bemis, K. G.; Rona, P. A.

    2013-12-01

    Over the past several decades, quantifying the heat output has been a unanimous focus of studies at hydrothermal vent fields discovered around the global ocean. Despite their importance, direct measurements of hydrothermal heat flux are very limited due to the remoteness of most vent sites and the complexity of hydrothermal venting. Moreover, almost all the heat flux measurements made to date are snapshots and provide little information on the temporal variation that is expected from the dynamic nature of a hydrothermal system. The Cabled Observatory Vent Imaging Sonar (COVIS, https://sites.google.com/a/uw.edu/covis/) is currently connected to the Endeavour node of the NEPTUNE Canada observatory network (http://www.neptunecanada.ca) to monitor the hydrothermal plumes issuing from a vent cluster (Grotto) on the Endeavour Segment of the Juan de Fuca Ridge. COVIS is acquiring a long-term (20-months to date) time series of the vertical flow rate and volume flux of the hydrothermal plume above Grotto through the Doppler analysis of the acoustic backscatter data (Xu et al., 2013). We then estimate the plume heat flux from vertical flow rate and volume flux using our newly developed inverse method. In this presentation, we will briefly summarize the derivation of the inverse method and present the heat-flux time series obtained consequently with uncertainty quantification. In addition, we compare our heat-flux estimates with the one estimated from the plume in-situ temperatures measured using a Remotely Operative Vehicle (ROV) in 2012. Such comparison sheds light on the uncertainty of our heat flux estimation. Xu, G., Jackson, D., Bemis, K., and Rona, P., 2013, Observations of the volume flux of a seafloor hydrothermal plume using an acoustic imaging sonar, Geochemistry, Geophysics Geosystems, 2013 (in press).

  16. Sericite from the Silverton caldera, Colorado: correlation among structure, composition, origin, and particle thickness.

    Science.gov (United States)

    Eberl, D.D.; Srodon, J.; Lee, M.; Nadeau, P.H.; Northrop, H.R.

    1987-01-01

    The mineralogy and the origin of a suite of almost pure sericites, collected from fractures in hydrothermally altered volcanic rocks in the vicinity of the Silverton caldera in the western San Juan Mountains of Colorado, USA, are analysed.-J.A.Z.

  17. Renewed Geodetic Unrest at Santorini Caldera, Greece

    Science.gov (United States)

    Newman, A. V.; Stiros, S. C.; Moschas, F.; Saltogianni, V.; Feng, L.; Farmer, G. T.; Psimoulis, P.; Jiang, Y.

    2012-04-01

    Santorini Caldera, in the southern Aegean, is part of a well-developed, and very active volcanic system fueled by subduction along the Hellenic arc that is responsible for the largest volcanic eruption in human history (~1650 B.C.). After approximately 50 years of relative seismic quiescence within the caldera and an episode of minor inflation, the volcano has recently reawakened with an exponentially increasing inflation signal, beginning in January 2011. The GPS network, including 3 continuous stations and biennial surveys of 19 campaign stations, showed essentially no deformation between 2006 and 2010. Following a cluster of microseismicity within the caldera two surveys in June and August 2011 were made, while two additional permanent GPS stations were installed. From this data, we found uplift and nearly-radial expansion up to 1 cm/month. This deformation is well-explained by a Mogi-source at the northern part of the caldera, with an approximately 6-10 million m3 volumetric growth at approximately 4 km depth, and tendency for development of a new dome offshore. It is likely that stresses from this magma source are responsible for a cluster of microseismity that began in January 2011 along a radial lineament of young volcanics, called the 'Kameni Line'.

  18. PREFACE: Collapse Calderas Workshop

    Science.gov (United States)

    Gottsmann, Jo; Aguirre-Diaz, Gerardo

    2008-10-01

    Caldera-formation is one of the most awe-inspiring and powerful displays of nature's force. Resultant deposits may cover vast areas and significantly alter the immediate topography. Post-collapse activity may include resurgence, unrest, intra-caldera volcanism and potentially the start of a new magmatic cycle, perhaps eventually leading to renewed collapse. Since volcanoes and their eruptions are the surface manifestation of magmatic processes, calderas provide key insights into the generation and evolution of large-volume silicic magma bodies in the Earth's crust. Despite their potentially ferocious nature, calderas play a crucial role in modern society's life. Collapse calderas host essential economic deposits and supply power for many via the exploitation of geothermal reservoirs, and thus receive considerable scientific, economic and industrial attention. Calderas also attract millions of visitors world-wide with their spectacular scenic displays. To build on the outcomes of the 2005 calderas workshop in Tenerife (Spain) and to assess the most recent advances on caldera research, a follow-up meeting was proposed to be held in Mexico in 2008. This abstract volume presents contributions to the 2nd Calderas Workshop held at Hotel Misión La Muralla, Querétaro, Mexico, 19-25 October 2008. The title of the workshop `Reconstructing the evolution of collapse calderas: Magma storage, mobilisation and eruption' set the theme for five days of presentations and discussions, both at the venue as well as during visits to the surrounding calderas of Amealco, Amazcala and Huichapan. The multi-disciplinary workshop was attended by more than 40 scientist from North, Central and South America, Europe, Australia and Asia. Contributions covered five thematic topics: geology, geochemistry/petrology, structural analysis/modelling, geophysics, and hazards. The workshop was generously supported by the International Association of Volcanology and the Chemistry of The Earth's Interior

  19. Seismic constraints on caldera dynamics from the 2015 Axial Seamount eruption

    Science.gov (United States)

    Wilcock, William S. D.; Tolstoy, Maya; Waldhauser, Felix; Garcia, Charles; Tan, Yen Joe; Bohnenstiehl, DelWayne R.; Caplan-Auerbach, Jacqueline; Dziak, Robert P.; Arnulf, Adrien F.; Mann, M. Everett

    2016-12-01

    Seismic observations in volcanically active calderas are challenging. A new cabled observatory atop Axial Seamount on the Juan de Fuca ridge allows unprecedented real-time monitoring of a submarine caldera. Beginning on 24 April 2015, the seismic network captured an eruption that culminated in explosive acoustic signals where lava erupted on the seafloor. Extensive seismic activity preceding the eruption shows that inflation is accommodated by the reactivation of an outward-dipping caldera ring fault, with strong tidal triggering indicating a critically stressed system. The ring fault accommodated deflation during the eruption and provided a pathway for a dike that propagated south and north beneath the caldera’s east wall. Once north of the caldera, the eruption stepped westward, and a dike propagated along the extensional north rift.

  20. Caldera types and collapse styles

    Science.gov (United States)

    Aguirre-Diaz, G. J.

    2008-12-01

    Three main types of collapse calderas can be defined, 1) summit caldera, 2) classic caldera, and 3) graben caldera. Summit calderas are those formed at the top of large volcanoes and are related to relatively small- volume pyroclastic products that include plinian fallouts and ignimbrites, such as Crater Lake, Las Cañadas, and Somma-Vesuvio. Classic calderas are semi-circular to irregular-shaped large structures, several km in diameter that are related to relatively large-volume pyroclastic products including pumice fallouts and widespread ignimbrites, such as Long-Valley, Campi Flegrei, and Los Humeros. Graben calderas are explosive volcano-tectonic collapse structures from which large-volume, ignimbrite-forming eruptions occurred through several vents along the graben walls and the intra-graben block faults causing the collapse of the graben or of a sector of the graben. The main products of graben calderas are surge-deposits and large-volume widespread ignimbrite sheets. Pumice fallouts are practically absent. Examples include the Sierra Madre Occidental in Mexico, La Pacana (Andes), Catalan Pyrenees, and perhaps Scafell (United Kingdom). Any of the three caldera types mentioned above could have collapsed at least in three different ways, 1) piston, when the collapse occurs as a single crustal block; 2) trap-door, when collapse occurs unevenly along one side while the opposite side remains with no collapse; 3) piece-meal, when collapse occurs as broken pieces of the crust on top of the magma chamber.

  1. Reconstruction of caldera collapse and resurgence processes in the offshore sector of the Campi Flegrei caldera (Italy)

    Science.gov (United States)

    Steinmann, Lena; Spiess, Volkhard; Sacchi, Marco

    2015-04-01

    system. Moreover, a dome-like structure associated with a cluster of normal faults and an apical depression was identified in the center of the caldera, which corresponds very well with the on land observed location of the long-term uplift. Based on the seismic dataset, a conceptual reconstruction of the caldera deformation and depositional processes was developed. Furthermore, the seismic data show indications for a shallow ring-fault system associated with the collapse of the NYT caldera. In addition, major stratigraphic units such as the CI and NYT could be traced on a regional scale, thereby providing information about the eruptive processes and vent locations. Besides the volcano-tectonic aspects, a system tract analysis was carried out in order to reveal the interplay between eustatic sea-level variations and tectonically induced uplift and subsidence.

  2. Entrevista: Juan Pablo Gramsch

    Directory of Open Access Journals (Sweden)

    Juan Pablo Gramsch

    2015-04-01

    A cargo de este Programa, se desempeña prácticamente desde sus inicios como Coordinador General el Arquitecto señor Juan Pablo Gramsch Labra, titulado en la Pontificia Universidad Católica de Chile y con estudios de Post Grado como Diplomado en Ciencias Sociales en la Academia de Humanismo Cristiano y Magíster en Desarrollo Urbano de la Universidad de Lovaina, Bélgica. A continuación presentamos la entrevista concedida por Juan Pablo Gramsch a nuestra revista.

  3. Nonstatistical dynamics on the caldera

    CERN Document Server

    Collins, Peter; Carpenter, Barry K; Ezra, Gregory S; Wiggins, Stephen

    2014-01-01

    We explore both classical and quantum dynamics of a model potential exhibiting a caldera: that is, a shallow potential well with two pairs of symmetry related index one saddles associated with entrance/exit channels. Classical trajectory simulations at several different energies confirm the existence of the `dynamical matching' phenomenon originally proposed by Carpenter, where the momentum direction associated with an incoming trajectory initiated at a high energy saddle point determines to a considerable extent the outcome of the reaction (passage through the diametrically opposing exit channel). By studying a `stretched' version of the caldera model, we have uncovered a generalized dynamical matching: bundles of trajectories can reflect off a hard potential wall so as to end up exiting predominantly through the transition state opposite the reflection point. We also investigate the effects of dissipation on the classical dynamics. In addition to classical trajectory studies, we examine the dynamics of quan...

  4. Calderas of the Central Sector of the Mexican Volcanic Belt

    Science.gov (United States)

    Aguirre-Diaz, G. J.

    2001-12-01

    calderas cluster at 4-6 Ma and at 370-420 km from the actual trench. This peak in caldera eruptions coincides with major plate reorganizations offshore SW Mexico, such as the opening of the Gulf of California, an eastward jump of the East Pacific Rise (EPR), and a change from fast to slower spreading rates at the EPR and the Rivera-Pacific rise, which may be related to an increase in explosive volcanism in the central MVB.

  5. Nonstatistical dynamics on the caldera

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Peter; Wiggins, Stephen, E-mail: stephen.wiggins@mac.com [School of Mathematics, University of Bristol, Bristol BS8 1TW (United Kingdom); Kramer, Zeb C., E-mail: zck3@cornell.edu; Ezra, Gregory S., E-mail: gse1@cornell.edu [Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853 (United States); Carpenter, Barry K., E-mail: CarpenterB1@cardiff.ac.uk [School of Chemistry, Cardiff University, Cardiff CF10 3AT (United Kingdom)

    2014-07-21

    We explore both classical and quantum dynamics of a model potential exhibiting a caldera: that is, a shallow potential well with two pairs of symmetry related index one saddles associated with entrance/exit channels. Classical trajectory simulations at several different energies confirm the existence of the “dynamical matching” phenomenon originally proposed by Carpenter, where the momentum direction associated with an incoming trajectory initiated at a high energy saddle point determines to a considerable extent the outcome of the reaction (passage through the diametrically opposing exit channel). By studying a “stretched” version of the caldera model, we have uncovered a generalized dynamical matching: bundles of trajectories can reflect off a hard potential wall so as to end up exiting predominantly through the transition state opposite the reflection point. We also investigate the effects of dissipation on the classical dynamics. In addition to classical trajectory studies, we examine the dynamics of quantum wave packets on the caldera potential (stretched and unstretched). These computations reveal a quantum mechanical analogue of the “dynamical matching” phenomenon, where the initial expectation value of the momentum direction for the wave packet determines the exit channel through which most of the probability density passes to product.

  6. Subsidence of ash-flow calderas: Relation to caldera size and magma-chamber geometry

    Science.gov (United States)

    Lipman, P.W.

    1997-01-01

    Diverse subsidence geometries and collapse processes for ash-flow calderas are inferred to reflect varying sizes, roof geometries, and depths of the source magma chambers, in combination with prior volcanic and regional tectonic influences. Based largely on a review of features at eroded pre-Quaternary calderas, a continuum of geometries and subsidence styles is inferred to exist, in both island-arc and continental settings, between small funnel calderas and larger plate (piston) subsidences bounded by arcuate faults. Within most ring-fault calderas, the subsided block is variably disrupted, due to differential movement during ash-flow eruptions and postcollapse magmatism, but highly chaotic piecemeal subsidence appears to be uncommon for large-diameter calderas. Small-scale downsag structures and accompanying extensional fractures develop along margins of most calderas during early stages of subsidence, but downsag is dominant only at calderas that have not subsided deeply. Calderas that are loci for multicyclic ash-flow eruption and subsidence cycles have the most complex internal structures. Large calderas have flared inner topographic walls due to landsliding of unstable slopes, and the resulting slide debris can constitute large proportions of caldera fill. Because the slide debris is concentrated near caldera walls, models from geophysical data can suggest a funnel geometry, even for large plate-subsidence calderas bounded by ring faults. Simple geometric models indicate that many large calderas have subsided 3-5 km, greater than the depth of most naturally exposed sections of intracaldera deposits. Many ring-fault platesubsidence calderas and intrusive ring complexes have been recognized in the western U.S., Japan, and elsewhere, but no well-documented examples of exposed eroded calderas have large-scale funnel geometry or chaotically disrupted caldera floors. Reported ignimbrite "shields" in the central Andes, where large-volume ash-flows are inferred to

  7. Remembering Juan Navia.

    Science.gov (United States)

    Dasanayake, A P; Li, Y; Maetz, H M; Vermund, S H

    2013-10-01

    Juan Navia died on September 4, 2010. Those who knew him as the director of the University of Alabama's John J. Sparkman Center for International Public Health Education and later the dean of UAB School of Public Health watched him train and shape the next generation of global public health leaders with a kind heart and a firm, but gentle, hand. On this third anniversary of Professor Navia's passing, in response to an invitation from the Journal of Dental Research to write an essay on an educator who influenced the professional trajectories of many people, we have put together an account of some of his contributions and attributes to highlight this remarkable leader's accomplishments in and impact on dental public health and global nutrition.

  8. Conversation with Juan Carlos Negrete.

    Science.gov (United States)

    Negrete, Juan Carlos

    2013-08-01

    Juan Carlos Negrete is Emeritus Professor of Psychiatry, McGill University; Founding Director, Addictions Unit, Montreal General Hospital; former President, Canadian Society of Addiction Medicine; and former WHO/PAHO Consultant on Alcoholism, Drug Addiction and Mental Health.

  9. Kuwae caldera (Vanuatu) and climate confusion

    Science.gov (United States)

    Nemeth, K.; Cronin, S. J.; White, J. D.

    2006-12-01

    A circular argument was developed and further propagated through a series of studies that link a major climate- modifying eruption in the 15th century with Kuwae caldera in Vanuatu (New Hebrides). Although the Kuwae submarine caldera structure is large (12x6 km) and comparable in size to other major calderas, our recent work reveals no evidence for high intensity eruptions that may have caused major climatic forcing at this time from this centre. Instead, the youngest volcanic strata, predominantly traceable on the adjacent islands including Tongoa, record a variety of small dacitic eruptions with locally restricted effects. The identified deposits are not more than 20 m thick within 2 km of the caldera, quickly pinch out, and do not overtop pre- caldera scoria cones that are only a few 10's of m higher. The wedge-like geometry of the pumice deposits on Tongoa, contained only in the low coastal areas appear to record multiple small-volume pyroclastic density currents. The depositional characteristics of the near-shoreline deposits, especially on neighbouring Laika Island are characteristic for shallow subaqueous deposition. The characteristics and dispersal of the preserved subaerial deposits imply eruptions were of small to moderate magnitude and intensity. An alternative possibility is that Kuwae caldera formed by a largely submarine eruption, in which a large, shallow magma body was erupted as underwater pyroclastic flows. This would reconcile a large-volume caldera with the absence of any evidence for a high-intensity eruption into the atmosphere. Partial escape to the atmosphere of some eruptive products from sites at the margins of the subsiding caldera could, in this scenario, have produced the small volume deposits from different source vents that are represented on the circum-caldera islands.

  10. Relating seismic swarms and deformation in Long Valley Caldera, California

    Science.gov (United States)

    Montgomery-Brown, E. K.; Ellsworth, W. L.; Hill, D. P.; Shelly, D. R.; Langbein, J. O.; Lisowski, M.; Llenos, A. L.

    2013-12-01

    Earthquake swarm activity in the South Moat Seismic Zone (SMSZ) in Long Valley caldera began increasing following the onset of slow inflation of the resurgent dome in 2011. From 1980 through 1999 the caldera produced recurring earthquake swarms in the SMSZ accompanied by an 80-cm uplift of the resurgent dome. Since 2000, the caldera has been quieter than from 1980 to 1999, but it experienced a gradual 7-cm uplift episode in 2002-2003 and currently the caldera has been gradually uplifting since 2011 at less than half of the peak uplift velocity observed in the late 1990's. Two of the recent swarms in October/November of 2012 and March 2013 have been accompanied by small deformation transients during which caldera uplift paused for about a week despite otherwise steady inflation. To better understand this recent activity, we cross correlate seismic velocity waveforms from individual events recorded by the Long Valley seismic network to identify similar clusters (families) of earthquakes and analyze their temporal recurrence. Then, we use representative waveforms from each family as templates to search the continuous waveforms from the deep borehole seismometers in the Long Valley Exploratory Well (MDH1) for repeating, yet smaller, earthquakes. MDH1 consists of two three-component instruments, located 2592 m and 2263 m below ground level, that provide 6 channels with very low background noise relative to surface seismometers. The cross correlations identify about 25 times more earthquakes with most magnitudes ranging from -1 to +0.5, determined from an empirical relationship between catalog magnitude and observed amplitude on MDH1. We apply an ETAS model to the augmented catalog to detect subtle changes in background earthquake rates that might suggest a change in stressing rate. For comparison with the change in seismicity rates, a geodetically determined stress change is estimated from a simple model of the continuous GPS data. We model the uplift from 2011 to

  11. Crustal magma pathway beneath Aso caldera inferred from three-dimensional electrical resistivity structure

    Science.gov (United States)

    Hata, Maki; Takakura, Shinichi; Matsushima, Nobuo; Hashimoto, Takeshi; Utsugi, Mitsuru

    2016-10-01

    At Naka-dake cone, Aso caldera, Japan, volcanic activity is raised cyclically, an example of which was a phreatomagmatic eruption in September 2015. Using a three-dimensional model of electrical resistivity, we identify a magma pathway from a series of northward dipping conductive anomalies in the upper crust beneath the caldera. Our resistivity model was created from magnetotelluric measurements conducted in November-December 2015; thus, it provides the latest information about magma reservoir geometry beneath the caldera. The center of the conductive anomalies shifts from the north of Naka-dake at depths >10 km toward Naka-dake, along with a decrease in anomaly depths. The melt fraction is estimated at 13-15% at 2 km depth. Moreover, these anomalies are spatially correlated with the locations of earthquake clusters, which are distributed within resistive blocks on the conductive anomalies in the northwest of Naka-dake but distributed at the resistive sides of resistivity boundaries in the northeast.

  12. Temporal models for the episodic volcanism of Campi Flegrei caldera (Italy) with uncertainty quantification

    Science.gov (United States)

    Bevilacqua, Andrea; Flandoli, Franco; Neri, Augusto; Isaia, Roberto; Vitale, Stefano

    2016-11-01

    After the large-scale event of Neapolitan Yellow Tuff ( 15 ka B.P.), intense and mostly explosive volcanism has occurred within and along the boundaries of the Campi Flegrei caldera (Italy). Eruptions occurred closely spaced in time, over periods from a few centuries to a few millennia, and were alternated with periods of quiescence lasting up to several millennia. Often events also occurred closely in space, thus generating a cluster of events. This study had two main objectives: (1) to describe the uncertainty in the geologic record by using a quantitative model and (2) to develop, based on the uncertainty assessment, a long-term subdomain specific temporal probability model that describes the temporal and spatial eruptive behavior of the caldera. In particular, the study adopts a space-time doubly stochastic nonhomogeneous Poisson-type model with a local self-excitation feature able to generate clustering of events which are consistent with the reconstructed record of Campi Flegrei. Results allow the evaluation of similarities and differences between the three epochs of activity as well as to derive eruptive base rate of the caldera and its capacity to generate clusters of events. The temporal probability model is also used to investigate the effect of the most recent eruption of Monte Nuovo (A.D. 1538) in a possible reactivation of the caldera and to estimate the time to the next eruption under different volcanological and modeling assumptions.

  13. Entrevista con Juan Marichal.

    Directory of Open Access Journals (Sweden)

    - Consejo de Redacción

    1997-01-01

    Full Text Available Juan Marichal nació en Santa Cruz de Tenerife, en 1922, en el seno de una familia ligada al partido republicano insular. Muy joven, en 1935, se trasladó a Madrid, ciudad en la que vive el estallido de la guerra civil. En 1937, pasa a Valencia y luego a Barcelona; tras su exilio en 1938, prosigue sus estudios secundarios en un liceo de París, concluyéndolos en Casablanca. En 1941 emigra a México, formándose en la UNAM: fue alumno de los exiliados José Gaos y Joaquín Xirau así como del mexicano Edmundo O 'Gorman. Luego, becado en Princeton desde 1946, lo fue de América Castro, donde preparó una tesis sobre Feijoo. Apoyado en las vastas perspectivas de sus maestros, fue orientándose hada nuestra historia intelectual, desde el siglo XV hasta hoy. Su carrera profesional se ha desarrollado en los Estados Unidos (coincidiendo con Amado Alonso y con Ferrater Mora: ha sido profesor de estudios hispánicos en la Universidad de Harvard, desde 1948 hasta 1988, año en que se jubiló voluntariamente como numerario (aunque había permanecido en el Bryn Mawr College, entre 1953 y 1957. A este trabajo se suman, con todo, sus conferencias en América Latina y en España. Ha colaborado en las revistas más importantes, en este campo, de México, Nueva York, Puerto Rico, La Habana, Buenos Aires o París así como de las españolas, desde los sesenta. Juan Marichal -hoy, miembro de la Junta Directiva de los Amigos de la Residencia de Estudiantes, director del Boletín de la Institución Libre de Enseñanza y asociado al Instituto Universitario Ortega y Gasset-, reside en España desde otoño de 1989: se considera a sí mismo «voluntario en Madrid», como había dicho Alfonso Reyes en su estancia madrileña (1914-1924.

  14. Hydrothermal system of Long Valley caldera, California

    Energy Technology Data Exchange (ETDEWEB)

    Sorey, M.L.; Lewis, R.E.; Olmsted, F.H.

    1978-01-01

    The geologic and hydrologic setting of the hydrothermal system are described. The geochemical and thermal characteristics of the system are presented. A mathematical model of the Long Valley caldera is analyzed. (MHR)

  15. 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.

  16. Can we see the distal dyke communicate with the caldera? Examples of temporal correlation analysis using seismicity from the Bárðarbunga volcano

    Science.gov (United States)

    Jónsdóttir, Kristín; Jónasson, Kristján; Tumi Guðmundsson, Magnús; Hensch, Martin; Hooper, Andrew; Holohan, Eoghan; Sigmundsson, Freysteinn; Halldórsson, Sæmundur Ari; Vogfjörð, Kristín; Roberts, Matthew; Barsotti, Sara; Ófeigsson, Benedikt; Hjörleifsdóttir, Vala; Magnússon, Eyjólfur; Pálsson, Finnur; Parks, Michelle; Dumont, Stephanie; Einarsson, Páll; Guðmundsson, Gunnar

    2016-04-01

    The Bárðarbunga volcano is composed of a large oval caldera (7x11 km) and fissures extending tens of kilometers away from the caldera along the rift zone, which marks the divergent plate boundary across Iceland. On August 16th, 2014 an intense seismic swarm started below the Bárðarbunga caldera and in the two weeks that followed a dyke migrated some 47 km laterally in the uppermost 6-10 km of the crust along the rift. The dyke propagation terminated in lava fields just north of Vatnajökull glacier, where a major (1.5 km3) six months long eruption took place. Intense earthquake activity in the caldera started in the period August 21-24 with over 70 M5 earthquakes accompanying slow caldera collapse, as verified by various geodetic measurements. The subsidence is likely due to magma withdrawal from a reservoir at depth beneath the caldera. During a five months period, October-February, the seismic activity was separated by over 30 km in two clusters; one along the caldera rims (due to piecewise caldera subsidence) and the other at the far end of the dyke (as a result of small shear movements). Here we present statistical analysis comparing the temporal behaviour of seismicity recorded in the two clusters. By comparing the earthquake rate in the dyke in temporal bins before and after caldera subsidence earthquakes to the rate away from these bins (background rate), we show posing a statistical p-value test, that the number of dyke earthquakes was significantly higher (p earthquake (>M4.6) in the caldera. Increased dyke seismicity was also observed 0-3 hours following a large caldera earthquake. Elevated seismicity in the dyke before a large caldera earthquake may occur when a constriction in the dyke was reduced, followed by pressure drop in the chamber. Assuming that the large caldera earthquakes occurred when chamber pressure was lowest, the subsiding caldera piston may have caused temporary higher pressure in the dyke and thereby increased the likelihood of an

  17. Origin of calderas: discriminating between collapses and explosions

    Directory of Open Access Journals (Sweden)

    Izumi Yokoyama

    2017-01-01

    Full Text Available Origins of calderas may differ according to their subsurface structure that may be characterized by high or low density deposits that may be observed as high or low gravity anomalies, respectively. In the Introduction, the pioneering work of Fouqué[1879] on Santorini caldera is referred to in relation to definition of calderas. First, our discussion is focused on four calderas that were seen forming during the period from 1815 (the Tambora eruption to 1991 (the Pinatubo eruption. Coincidently, these four calderas are all low-gravity-anomaly type. Their formation processes and subsurface structure are summarized by the existing data analyzed by various authors. These results are confirmed by results of drillings at some other calderas. Then, caldera formation of both types is discussed: High-gravity-anomaly-type calderas are expected to originate from subsidence of high-density ejecta into the summit magma reservoir. On the calderas of this type, the genetic eruptions believed to be accompanied by subsidences were not actually observed, and consequently three examples are mentioned only briefly. The low-gravity-anomaly-type calderas are discussed from standpoint of both the models of collapses and explosions. It is also emphasized that dynamic pressure ofexplosions is an important factor in the caldera formation, not only volume of the ejecta. To confirm the possibility that volcanic ejecta and edifices collapse into magma reservoirs, we discuss stress propagation from a depleted reservoir upward towards the Earth surface. Formation mechanisms of large calderas of this type are speculated; large calderas measuring about 20 km across may develop by successive merging of component calderas over a long period of times. A Kamchatka caldera under enlargement during the Holocene period is interpreted by successive merging of five component calderas.

  18. Origin of calderas: discriminating between collapses and explosions

    OpenAIRE

    Izumi Yokoyama

    2017-01-01

    Origins of calderas may differ according to their subsurface structure that may be characterized by high or low density deposits that may be observed as high or low gravity anomalies, respectively. In the Introduction, the pioneering work of Fouqué[1879] on Santorini caldera is referred to in relation to definition of calderas. First, our discussion is focused on four calderas that were seen forming during the period from 1815 (the Tambora eruption) to 1991 (the Pinatubo eruption). Coincident...

  19. Geochronology and geology of late Oligocene through Miocene volcanism and mineralization in the western San Juan Mountains, Colorado

    Science.gov (United States)

    Bove, D.J.; Hon, Ken; Budding, K.E.; Slack, J.F.; Snee, L.W.; Yeoman, R.A.

    2000-01-01

    Twenty-five new 40Ar/39Ar ages from volcanic rocks and veins in the western San Juan Mountains clarify relationships between volcanism and mineralization in this classic area. Five calc-alkaline ash-flow sheets erupted from caldera sources (Ute Ridge, Blue Mesa, Dillon Mesa, Sapinero Mesa, and Crystal Lake Tuffs) from 28.6 to 27.6 Ma. This is a much more restricted time interval than previously thought and indicates that the underlying batholith rose and evolved very rapidly beneath the western San Juan Mountains. The new ages and geologic relations constrain the timing of joint resurgence of the Uncompahgre and San Juan calderas to between 28.2 and 27.6 Ma. The collapse of the Silverton caldera produced a set of strong ring fractures that intersected with graben faults on the earlier resurgent dome to produce the complex set of structures that localized the mid-Miocene epithermal gold veins. Later calc-alkaline monzonitic to quartz monzontic plutons solidified at 26.5-26.0 Ma as the underlying batholith rose through its volcanic cover. A new age from lavas near Uncompahgre Peak supports earlier interpretations that these lavas were fed by nearby 26 Ma monzonite intrusions. Nearly all of these intrusions are associated with subeconomic Mo and Cu mineralization and associated alteration, and new ages of 26.40 and 25.29 Ma from the Ute-Ulay and Lilly veins in the Lake City region show that some of the most important silver and base-metal veins were temporally and possibly genetically connected to these plutons. In addition, the Golden Fleece telluride vein cuts all of the post-Uncompahgre caldera volcanics in the area and is probably temporally related to this cycle, though its age of 27.5 ? 0.3 Ma was determined by less precise U/Pb methods. The 22.9 Ma Lake City caldera collapsed within the older Uncompahgre caldera structure but is petrologically unrelated to the older calc-alkaline activity. The distinctive suite of high-silica rhyolite tuff and alkaline

  20. Recent geodetic unrest at Santorini Caldera, Greece

    Science.gov (United States)

    Newman, Andrew V.; Stiros, Stathis; Feng, Lujia; Psimoulis, Panos; Moschas, Fanis; Saltogianni, Vasso; Jiang, Yan; Papazachos, Costas; Panagiotopoulos, Dimitris; Karagianni, Eleni; Vamvakaris, Domenikos

    2012-03-01

    After approximately 60 years of seismic quiescence within Santorini caldera, in January 2011 the volcano reawakened with a significant seismic swarm and rapidly expanding radial deformation. The deformation is imaged by a dense network of 19 survey and 5 continuous GPS stations, showing that as of 21 January 2012, the volcano has extended laterally from a point inside the northern segment of the caldera by about 140 mm and is expanding at 180 mm/yr. A series of spherical source models show the source is not migrating significantly, but remains about 4 km depth and has expanded by 14 million m3 since inflation began. A distributed sill model is also tested, which shows a possible N-S elongation of the volumetric source. While observations of the current deformation sequence are unprecedented at Santorini, it is not certain that an eruption is imminent as other similar calderas have experienced comparable activity without eruption.

  1. Closing crack earthquakes within the Krafla caldera, North Iceland

    Science.gov (United States)

    Mildon, Zoë K.; Pugh, David J.; Tarasewicz, Jon; White, Robert S.; Brandsdóttir, Bryndís

    2016-11-01

    Moment tensor analysis with a Bayesian approach was used to analyse a non-double-couple (non-DC) earthquake (Mw ˜ 1) with a high isotropic (implosive) component within the Krafla caldera, Iceland. We deduce that the earthquake was generated by a closing crack at depth. The event is well located, with high signal-to-noise ratio and shows dilatational P-wave first arrivals at all stations where the first arrival can be picked with confidence. Coverage of the focal sphere is comprehensive and the source mechanism stable across the full range of uncertainties. The non-DC event lies within a cluster of microseismic activity including many DC events. Hence, we conclude that it is a true non-DC closing crack earthquake as a result of geothermal utilization and observed magma chamber deflation in the region at present.

  2. Mineral and chemical variations within an ash-flow sheet from Aso caldera, Southwestern Japan

    Science.gov (United States)

    Lipman, P.W.

    1967-01-01

    Although products of individual volcanic eruptions, especially voluminous ash-flow eruptions, have been considered among the best available samples of natural magmas, detailed petrographic and chemical study indicates that bulk compositions of unaltered Pleistocene ash-flow tuffs from Aso caldera, Japan, deviate significantly from original magmatic compositions. The last major ash-flow sheet from Aso caldera is as much as 150 meters thick and shows a general vertical compositional change from phenocryst-poor rhyodacite upward into phenocryst-rich trachyandesite; this change apparently reflects in inverse order a compositionally zoned magma chamber in which more silicic magma overlay more mafic magma. Details of these magmatic variations were obscured, however, by: (1) mixing of compositionally distinct batches of magma during upwelling in the vent, as indicated by layering and other heterogeneities within single pumice lumps; (2) mixing of particulate fragments-pumice lumps, ash, and phenocrysts-of varied compositions during emplacement, with the result that separate pumice lenses from a single small outcrop may have a compositional range nearly as great as the bulk-rook variation of the entire sheet; (3) density sorting of phenocrysts and ash during eruption and emplacement, resulting in systematic modal variations with distance from the caldera; (4) addition of xenocrysts, resulting in significant contamination and modification of proportions of crystals in the tuffs; and (5) ground-water leaching of glassy fractions during hydration after cooling. Similar complexities characterize ash-flow tuffs under study in southwestern Nevada and in the San Juan Mountains, Colorado, and probably are widespread in other ash-flow fields as well. Caution and careful planning are required in study of the magmatic chemistry and phenocryst mineralogy of these rocks. ?? 1967 Springer-Verlag.

  3. A geologic and anthropogenic journey from the Precambrian to the new energy economy through the San Juan volcanic field

    Science.gov (United States)

    Yager, Douglas B.; Burchell,; Johnson, Raymond H.

    2010-01-01

    The San Juan volcanic field comprises 25,000 km2 of intermediate composition mid-Tertiary volcanic rocks and dacitic to rhyolitic calderas including the San Juan–Uncompahgre and La Garita caldera-forming super-volcanoes. The region is famous for the geological, ecological, hydrological, archeological, and climatological diversity. These characteristics supported ancestral Puebloan populations. The area is also important for its mineral wealth that once fueled local economic vitality. Today, mitigating and/or investigating the impacts of mining and establishing the region as a climate base station are the focuses of ongoing research. Studies include advanced water treatment, the acid neutralizing capacity (ANC) of propylitic bedrock for use in mine-lands cleanup, and the use of soil amendments including biochar from beetle-kill pines. Biochar aids soil productivity and revegetation by incorporation into soils to improve moisture retention, reduce erosion, and support the natural terrestrial carbon sequestration (NTS) potential of volcanic soils to help offset atmospheric CO2 emissions. This field trip will examine the volcano-tectonic and cultural history of the San Juan volcanic field as well as its geologic structures, economic mineral deposits and impacts, recent mitigation measures, and associated climate research. Field trip stops will include a visit to (1) the Summitville Superfund site to explore quartz alunite-Au mineralization, and associated alteration and new water-quality mitigation strategies; (2) the historic Creede epithermal-polymetallic–vein district with remarkably preserved resurgent calderas, keystone-graben, and moat sediments; (3) the historic mining town of Silverton located in the nested San Juan–Silverton caldera complex that exhibits base-metal Au-Ag mineralization; and (4) the site of ANC and NTS studies. En route back to Denver, we will traverse Grand Mesa, a high NTS area with Neogene basalt-derived soils and will enjoy a soak

  4. The geology and petrology of Volcán San Juan (Nayarit, México) and the compositionally zoned Tepic Pumice

    Science.gov (United States)

    Luhr, James F.

    2000-01-01

    Volcán San Juan is the westernmost Quaternary composite volcano in the Mexican Volcanic Belt. Its activity is divided into three stages of decreasing eruptive volume. During stage-1 activity, the main cone of San Juan and the adjacent Cerro Alto grew to a combined volume of ˜60 km 3 through eruption of hornblende-bearing andesites, dacites, and rhyodacites. Stage 1 included explosive eruptions of hornblende-dacite and an andesite dated at 33,750 a (years ago) and 23,010 a. Stage-2 activity involved a major Plinian eruption 14,770 a that produced the hypersthene-hornblende-bearing, compositionally zoned, rhyodacitic-andesitic Tepic Pumice and led to formation of an oval-shaped caldera 4×1 km in diameter. Tepic, the capital city of Nayarit State, with a population of ˜250,000, lies at the NE foot of Volcán San Juan. This location was buried under 2-9 m of rhyodacitic pumice-fall deposits from the Tepic Pumice eruption. Erosion has since removed virtually all exposures of Tepic Pumice >15 km from the caldera. The estimated volume of erupted tephra is 5.6 km 3, equivalent to 1.2 km 3 of magma. Modeling of the eruption dynamics indicates that as the eruption evolved the column height increased from ˜15 km to ˜24 km and maximum mass discharge rate increased from ˜3×10 6 kg/s to ˜6×10 7 kg/s. During stage-3 activity, a hornblende-andesitic lava dome partially filled the caldera and sent block lava flows down the north slope of the cone; total erupted volume was ˜0.55 km 3. Compared to other composite volcanoes of the western Mexican Volcanic Belt, the products from San Juan have the highest Sr contents and the lowest Rb, Y, Yb, and Lu contents, resulting in high La/Yb and Sr/Y, with low Rb/Sr. These observations indicate a strong slab-melt component at San Juan, consistent with its proximity to the Middle America Trench where young, hot lithosphere is subducting. The San Juan andesites, dacites, and rhyodacites also have relatively high 87Sr/ 86Sr, 206Pb/ 204

  5. Precaldera lavas of the southeast San Juan Volcanic Field: Parent magmas and crustal interactions

    Science.gov (United States)

    Colucci, M. T.; Dungan, M. A.; Ferguson, K. M.; Lipman, P. W.; Moorbath, S.

    1991-07-01

    Early intermediate composition volcanic rocks of the Oligocene (circa 34-29 Ma) southeast San Juan volcanic field, southern Colorado, comprise the Conejos Formation. Conejos lavas include both high-K calc-alkaline and alkaline magma series (54-69% SiO2) ranging in composition from basaltic andesite (basaltic trachyandesite) to dacite (trachydacite). The subsequent Platoro caldera complex (29-27 Ma) was superimposed on a cluster of broadly precursory Conejos stratocones. Precaldera volcanism occurred in three pulses corresponding to three time-stratigraphic members: (1) the Horseshoe Mountain member, (2) the Rock Creek member, and (3) the Willow Mountain member. Each member exhibits distinctive phenocryst modes and incompatible trace element contents. Horseshoe Mountain lavas (hornblende-phyric) have relatively low alkali and incompatible element abundances, Rock Creek lavas (anhydrous phenocrysts) and ash-flow tuffs have the highest abundances, and Willow Mountain lavas (diverse mineralogy) are intermediate. All Conejos lavas exhibit low ratios of lead (206Pb/204Pb = 17.5 to 18.2) and neodymium (ɛNd = -8 to -4) isotopes and high 87Sr/86Sr (0.7045 to 0.7056) compared to depleted asthenospheric mantle. These values lie between those of likely mantle compositions and the isotopic composition of Proterozoic crust of the southern Rocky Mountains. Mafic lavas of the Horseshoe Mountain member have the lowest Pb and Nd isotope ratios among Conejos members but trend toward higher isotopic values with increasing degrees of differentiation. Compositions within the Rock Creek series trend toward higher Pb and lower Nd isotope ratios with increasing SiO2. Willow mountain volcanic sequences define diverse chemical-isotopic correlations. We interpret the chemical and isotopic differences observed between mafic lavas of each member to reflect derivation from compositionally distinct mantle derived parent magmas that have experienced extensive deep level crustal contamination

  6. The Christmas Mountains caldera complex, Trans-Pecos Texas

    Science.gov (United States)

    Henry, Christopher D.; Price, Jonathan G.

    1989-12-01

    The Christmas Mountains caldera complex developed approximately 42 Ma ago over an elliptical (8×5 km) laccolithic dome that formed during emplacement of the caldera magma body. Rocks of the caldera complex consist of tuffs, lavas, and volcaniclastic deposits, divided into five sequences. Three of the sequences contain major ash-flow tuffs whose eruption led to collapse of four calderas, all 1 1.5 km in diameter, over the dome. The oldest caldera-related rocks are sparsely porphyritic, rhyolitic, air-fall and ash-flow tuffs that record formation and collapse of a Plinian-type eruption column. Eruption of these tuffs induced collapse of a wedge along the western margin of the dome. A second, more abundantly porphyritic tuff led to collapse of a second caldera that partly overlapped the first. The last major eruptions were abundantly porphyritic, peralkaline quartz-trachyte ash-flow tuffs that ponded within two calderas over the crest of the dome. The tuffs are interbedded with coarse breccias that resulted from failure of the caldera walls. The Christmas Mountains caldera complex and two similar structures in Trans-Pecos Texas constitute a newly recognized caldera type, here termed a laccocaldera. They differ from more conventional calderas by having developed over thin laccolithic magma chambers rather than more deep-seated bodies, by their extreme precaldera doming and by their small size. However, they are similar to other calderas in having initial Plinian-type air-fall eruption followed by column collapse and ash-flow generation, multiple cycles of eruption, contemporaneous eruption and collapse, apparent pistonlike subsidence of the calderas, and compositional zoning within the magma chamber. Laccocalderas could occur else-where, particularly in alkalic magma belts in areas of undeformed sedimentary rocks.

  7. Microearthquakes at Valles Caldera, New Mexico: Improved Detection and Location with Two Additional Caldera Stations

    Science.gov (United States)

    Roberts, P. M.; House, L. S.; Ten Cate, J. A.

    2015-12-01

    The Los Alamos Seismic Network (LASN) has operated for 43 years, providing data to locate more than 2,500 earthquakes in north-central New Mexico. Roughly 1-2 earthquakes are detected and located per month within about 150 km of Los Alamos, a total of over 900 from 1973 to present. LASN's primary purpose is to monitor seismicity close to the Los Alamos National Laboratory (LANL) for seismic hazards; monitoring seismicity associated with the nearby Valles Caldera is secondary. Until 2010 the network was focused on monitoring seismic hazards and comprised only 7 stations, all near LANL or in the nearby Jemez Mountains. Just one station—PER, installed in 1998—was close enough to Valles Caldera to be able to detect microearthquakes located in or near the caldera. An initial study of the data from station PER between 1998 and 2002 identified and located 13 events with magnitudes less than 0.5 using the single-station hodogram technique. Those events were all located south of the caldera within a few kilometers of PER. Recently, two new digital broadband stations were installed inside the caldera, one on a northeastern ring-fracture dome, station CDAB, and the other on a northwestern dome, station SAMT. Also, station PER was upgraded with digital broadband instrumentation. Thus, LASN now can detect and record microearthquakes as small as magnitude -1.5 near the caldera, and they can be located using multiple arrival times. Several recent events located near station SAMT on the caldera's ring fracture are the first that have been seen in that area. Additional events were recorded (by all three stations) and located in the area south of the caldera where the earlier hodogram-only events were located. These new multi-station event recordings allow a more quantitative assessment of the uncertainties in the initial single-station hodogram locations. Each event is located using multiple arrival times as well as the hodogram method at as many as three stations. Thus

  8. Valles Caldera, New Mexico Microearthquakes: Improved Detection and Location with Expanded Caldera Station Coverage

    Science.gov (United States)

    House, L. S.; Roberts, P. M.; Ten Cate, J. A.

    2016-12-01

    The Los Alamos Seismic Network (LASN) has operated for 44 years, providing data to locate more than 2,500 earthquakes in north-central New Mexico. Roughly 1-2 earthquakes are detected and located per month within about 150 km of Los Alamos, a total of over 900 from 1973 to present. LASN's primary purpose is to monitor seismicity close to the Los Alamos National Laboratory (LANL) for seismic hazards; monitoring seismicity associated with the nearby Valles Caldera is secondary. Until 2010 the network comprised only 7 stations, all near LANL or in the nearby Jemez Mountains. Just one station (PER, installed in 1998) was close enough to Valles Caldera to be able to detect microearthquakes located in or near the caldera. An initial study of the data from station PER between 1998 and 2002 identified and located 13 events with magnitudes less than 0.5 using the single-station hodogram technique. Those events were all located south of the caldera within a few kilometers of PER. Recently, two new digital broadband stations were installed inside the caldera, one on a northeastern ring-fracture dome, station CDAB, and the other on a northwestern dome, station SAMT. Also, station PER was upgraded with digital broadband instrumentation. Thus, LASN now can detect and record microearthquakes as small as magnitude -1.5 near the caldera, and they can be located using arrival times at multiple stations. Several recent events located near station SAMT on the caldera's ring fracture are the first that have been seen in that area. Additional events were recorded (by all three stations) and located in the area south of the caldera where the earlier hodogram-only events were located. These new multi-station event recordings allow a more quantitative assessment of the uncertainties in the initial single-station hodogram locations. Each event is located using multiple arrival times as well as the hodogram method at as many as three stations. Thus, improvements can be made to the

  9. Geochemistry of Los Humeros Caldera, Puebla, Mexico

    Science.gov (United States)

    Verma, S. P.; Lopez, M.

    1982-03-01

    Geochemistry of Pliocene to recent volcanic rocks from Los Humeros caldera (19°30' N - 19°50' N and 97°15° W - 97°35' W) in East-Central mexico is described. The volcanic rocks from this area seem to represent both alkali and high-alumina basalt series, or both calcalkaline and high-K calc-alkaline sequences. The available bulk-chemical analyses (23 this study and 18 from unpublished literature) show that the entire sequence of rocks from basalts to rhyolites are present in this area. Different degrees of partial melting of the source region followed by extensive shallow-level crystal differentiation seem to have taken place before most volcanic eruptions. These processes are perhaps the most important mechanisms for magma genesis in Los Humeros caldera. Geophysical studies in this area are not sufficient and more detailed geophysical surveys and a better geological interpretation are needed in order to delimit the underlying magma chamber.

  10. Caldera rim collapse: A hidden volcanic hazard

    OpenAIRE

    Merle, Olivier; Michon, Laurent; Bachèlery, Patrick

    2008-01-01

    International audience; Following the emblematic flank collapse of Mount St Helens in 1981, numerous models of flank sliding have been proposed. These models have allowed to largely improve the understanding of mechanisms involved in such landslides, which represent a tremendous risk for populations living around volcanoes. In this article, a new mode of landslide formation, related to buried calderas, is described. The model emphasizes the paramount importance of the hidden ring fault that, ...

  11. California's restless giant: the Long Valley Caldera

    Science.gov (United States)

    Hill, David P.; Bailey, Roy A.; Hendley, James W.; Stauffer, Peter H.; Marcaida, Mae

    2014-01-01

    Scientists have monitored geologic unrest in the Long Valley, California, area since 1980. In that year, following a swarm of strong earthquakes, they discovered that the central part of the Long Valley Caldera had begun actively rising. Unrest in the area persists today. The U.S. Geological Survey (USGS) continues to provide the public and civil authorities with current information on the volcanic hazard at Long Valley and is prepared to give timely warnings of any impending eruption.

  12. Buried caldera of mauna kea volcano, hawaii.

    Science.gov (United States)

    Porter, S C

    1972-03-31

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

  13. Juan Villoro: miradas del ensayo

    OpenAIRE

    Walker, Carlos

    2009-01-01

    El presente trabajo analiza los dos libros que el escritor mexicano Juan Villoro inscribe bajo la rúbrica del ensayo -Efectos personales (2001) y De eso se trata (2007). Dicho análisis dará pie a un desarrollo sobre el lugar del ensayo como terreno privilegiado para la reflexión crítica. A partir de los célebres textos que György Lukács y Theodor Adorno dedicaran a la forma del ensayo, se establece una divergencia en los métodos que uno y otro proponen para el quehacer del ensayista. Lukács a...

  14. Magnetic study of the Furnas caldera (Azores

    Directory of Open Access Journals (Sweden)

    J. M. Torta

    1997-06-01

    Full Text Available A local ground magnetic study of the Furnas caldera (S. Miguel Island, Azores has provided new insight into the magnetic structure of this volcano. Analysis of the data comprised removal of the IGRF, reduction to the pole, pseudogravity integration and upward continuation. Also, a spectral method was applied to estimate the depth to the magnetic sources, as well as a 2.5D forward modelling technique. Magnetic properties obtained at the laboratory for some representative sample rocks were considered in the modelling process. The most relevant features are the existence of an important negative anomaly inside the caldera and of an intense positive anomaly to the south of the coast. The former points out a decrease in the magnetization of the caldera filling materials with respect to the surrounding rocks, which could be explained as the result of post-eruption processes such as hydrothermal alteration. This is expected as Furnas has an active hydrothermal system probably related with a magmatic reservoir at high temperature. The positive anomaly suggests the existence of a strongly-magnetized body beneath the south coast.

  15. Caldera collapse and the generation of waves

    Science.gov (United States)

    Gray, J. P.; Monaghan, J. J.

    2003-02-01

    The aim of this paper is to begin a study of the waves produced by the collapse of a caldera connected to the sea. An example is the bronze age collapse of the caldera of Santorini (Thera), which is thought to have involved an area of approximately 70 km2 subsiding to a depth close to the present 390 m. In this paper, we concentrate on the purely mechanical aspects of the flow and adopt a simple geometry that replicates some of the features of the pre-bronze age caldera of Santorini. By combining laboratory experiments with computer simulations, we have been able to determine the amplitude of the waves for a wide range of cavity parameters. For cavities with a width comparable to the depth of water entering the cavity, we have determined a scaling relation for the amplitude in terms of the geometry of the system. In the case of wider cavities, the flow begins like a breaking dam flow; it then becomes similar to a classical bore before breaking up into waves. The computer simulations agree well with experiment and will allow us to simulate more complicated geometries.

  16. Caldera processes and magma-hydrothermal systems continental scientific drilling program: thermal regimes, Valles caldera research, scientific and management plan

    Energy Technology Data Exchange (ETDEWEB)

    Goff, F.; Nielson, D.L. (eds.)

    1986-05-01

    Long-range core-drilling operations and initial scientific investigations are described for four sites in the Valles caldera, New Mexico. The plan concentrates on the period 1986 to 1993 and has six primary objectives: (1) study the origin, evolution, physical/chemical dynamics of the vapor-dominated portion of the Valles geothermal system; (2) investigate the characteristics of caldera fill and mechanisms of caldera collapse and resurgence; (3) determine the physical/chemical conditions in the heat transfer zone between crystallizing plutons and the hydrothermal system; (4) study the mechanism of ore deposition in the caldera environment; (5) develop and test high-temperature drilling techniques and logging tools; and (6) evaluate the geothermal resource within a large silicic caldera. Core holes VC-2a (500 m) and VC-2b (2000 m) are planned in the Sulphur Springs area; these core holes will probe the vapor-dominated zone, the underlying hot-water-dominated zone, the boiling interface and probable ore deposition between the two zones, and the deep structure and stratigraphy along the western part of the Valles caldera fracture zone and resurgent dome. Core hole VC-3 will involve reopening existing well Baca number12 and deepening it from 3.2 km (present total depth) to 5.5 km, this core hole will penetrate the deep-crystallized silicic pluton, investigate conductive heat transfer in that zone, and study the evolution of the central resurgent dome. Core hole VC-4 is designed to penetrate deep into the presumably thick caldera fill in eastern Valles caldera and examine the relationship between caldera formation, sedimentation, tectonics, and volcanism. Core hole VC-5 is to test structure, stratigraphy, and magmatic evolution of pre-Valles caldera rocks, their relations to Valles caldera, and the influences of regional structure on volcanism and caldera formation.

  17. Yellowstone and Long Valley - A Comparison of Two Restless Calderas

    Science.gov (United States)

    Hill, D. P.; Smith, R. B.

    2007-12-01

    Three large, silicic calderas in the conterminous United States have explosively erupted volumes > 300 km3 within in the last 2 million years -- Yellowstone caldera (Wyoming) Long Valley caldera (California) and the Vallez caldera (New Mexico) all located in extensional tectonic environments. All have shown varying levels of historic unrest. Pronounced unrest episodes at Yellowstone and Long Valley calderas over the past three decades stimulated extensive research on these two closely monitored calderas, and we explore some emerging similarities and differences. Yellowstone caldera is underlain by a long-lived (> 17 my) upper-mantle hot-spot that has fed a series of caldera-forming, extending to the southwest across southern Idaho to central Oregon including three caldera-forming eruptions from the Yellowstone caldera system in the last 2 my, the most recent at 600,000 ybp. It is marked by relatively low density and low seismic velocities extending to depths of at least 400 km and a regional topographic swell with elevations exceeding 2000 m. The extensive Yellowstone hydrothermal system has a thermal output of 5 GW. The most recent magmatic eruption dated at 70,000 ybp. By comparison, Long Valley caldera is underlain by a relatively modest "hot-spot", the locus of which appears to be influenced by a dilatational jog between the dextral Eastern California Shear Zone and the Walker Lane and westward delamination of the dense lithospheric root of the adjacent Sierra Nevada. The Long Valley system has fed multiple eruptions of over the past 4 my and a single caldera-forming eruption at 760,000 ybp. It is marked by a limited topographic swell but with the elevation of the caldera floor and adjacent basins comparable to the 2000-plus m elevation of the Yellowstone swell. Long Valley caldera hydrothermal system has a thermal output of 0.3 GW (including a 40 MW geothermal power plant). The most recent eruptions from the Long Valley Caldera- Mono Domes volcanic field

  18. Fluid-driven uplift at Long Valley Caldera, California: Geologic perspectives

    Science.gov (United States)

    Hildreth, Wes

    2017-07-01

    Since persistent seismicity began in the Sierra Nevada adjacent to Long Valley caldera in 1978-1980, intracaldera unrest has been marked by (1) episodes of uplift totaling 83 cm, centered on the middle Pleistocene resurgent dome, and (2) recurrent earthquake swarms along a 12-km-long segment of the caldera's ring-fault zone that is contiguous with both the dome and the Sierran seismogenic domain. Others have attributed the recent unrest to magmatic intrusion(s), but it is argued here that evidence for new magma is lacking and that ongoing uplift and ring-fault-zone seismicity are both promoted by ascent of aqueous fluid released by second boiling of the residue of the enormous Pleistocene rhyolitic reservoir terminally crystallizing at depths ≥ 10 km. For 2 Myr, eruptive vent clusters migrated southwestward from Glass Mountain to Mammoth Mountain. There has been no eruption on the resurgent dome since 500 ka, and since 230 ka volcanism has been restricted to the caldera's west moat and contiguous Sierran terrain, both outside the structural caldera. High-temperature hydrothermal activity in the central caldera waned after 300 ka, cooling the Pleistocene rhyolitic focus to the extent that drilling on the resurgent dome found mid-caldera temperature to be only 100 °C and isothermal at depths of 2-3 km. Beneath most of the resurgent dome, there is little seismicity at any depth, no emission of magmatic CO2 or other magmatic gases, no elevated 3He/4He ratios, and only normal to below-normal heat flow. Most of the 75-km-long ring-fault zone is likewise aseismic, excepting only the 12-km segment contiguous with the extracaldera seismogenic domain in the Sierra. Since 1980, the Sierran seismicity has released 3.6 times more cumulative seismic energy than have intracaldera earthquakes. The caldera seismicity is not driven by stresses associated with the adjacent uplift but, instead, by the extracaldera tectonic stressfield. Sierran seismicity activated the directly

  19. Trois biographies de Juan Rulfo

    OpenAIRE

    2014-01-01

    L’article s’intéresse à la fortune éditoriale des biographies de Rulfo à l’occasion de la célébration des cinquante ans de la parution de El llano en llamas (1953) et de Pedro Páramo (1955). L’étude de trois d’entre elles (écrites par Nuria Amat, Reina Roffé et Juan Ascensio) permet de voir le processus de légitimation de la biographie et les positions qu’adoptent les différents auteurs (tout spécialement en ce qui concerne leur relation avec l’auteur “biographié”) Les auteurs justifient leur...

  20. Juan de Mairena en Srebrenica

    Directory of Open Access Journals (Sweden)

    Sánchez, J. Jorge

    1997-09-01

    Full Text Available Not available.Dos hilos impulsan estas líneas: la reflexión sobre uno de los acontecimientos cruciales de este fin de siglo en Europa, la masacre de Srebrenica, y la necesidad de contribuir a la tarea colectiva de reconstruir una tradición filosófica en lengua castellana más allá de las clásicas distinciones de géneros. Ambos propósitos confluirían, metonímica y metafóricamente, en un nombre, Machado, y una obra, el Juan de Mairena. Los textos del apócrifo del poeta, tan próximo en algunos momentos al pensamiento de Lévinas o Heidegger, pueden contribuir a articular un examen crítico, insertado en una tradición, sobre ese símbolo de nuestra época.

  1. The Chacana caldera complex in Ecuador

    Energy Technology Data Exchange (ETDEWEB)

    Hall, Minard L; Mothes, Patricia A [Instituto Geofisico, Escuela Politecnica Nacional, Quito (Ecuador)], E-mail: volcan_pete@yahoo.com

    2008-10-01

    The Chacana caldera, located immediately east of Quito, capital of Ecuador, forms the most-northern edifice of Ecuadoros rhyolite province. It is a 50X30 km Pleistocene structure that has remained active into historic times. Vitrophyres, welded tuffs, and ignimbrites of rhyolitic and dacitic composition constitute the outer flanks, meantime syngenetic breccias and tuffs, capped later by extensive dacite lava flows and basin sediments, filled the calderaos depression. A notable resurgence occurred that lifted quiet-water sediments to over 4000 m in elevation. The area has numerous hot springs, and little seismic activity.

  2. The graben caldera of Guanajuato, Mexico

    Science.gov (United States)

    Aguirre-Diaz, G. J.; Tristán-González, M.; Labarthe-Hernández, G.; Marti, J.

    2013-05-01

    Guanajuato has been an important gold and silver mineral district of Mexico since the 16th century until Present. Famous mines such as Rayas, La Valenciana and El Cubo, are part of this important mining development. Stratigraphy and structures are well known, and major faults and vein systems are precisely mapped. The series include a Mesozoic metamorphosed volcano-sedimentary sequence interpreted as a tectonically accreted terrane during Early Cretaceous subduction; a >1000 m thick red beds sequence, apparently Eocene and interpreted originally as molasses posterior to K/T Laramide orogeny, but more probably fanglomerates filling a graben formed during mid-Tertiary extension; an Eocene-Miocene volcanic sequence that accumulated in this tectonic basin and the surrounding area, including andesitic lavas, silicic ignimbrites and surge deposits, and rhyolitic domes. Pyroclastic rocks have not been studied with a volcanological approach, with the purpose of understanding the physical volcanic processes that formed them. Randall (1994) suggested a caldera source for some of them. Our purpose is to describe the volcanic processes involved in the mid-Tertiary units of Guanajuato. There are dacitic and andesitic lavas that were apparently contemporaneous with deposition of the Red Conglomerate of Guanajuato. The ignimbrites correspond to the Sierra Madre Occidental volcanic province. These units were originated as two main pyroclastic densety currents sequences that formed the Loseros-Bufa and the Calderones formations. The former is rhyolitic and the later andesitic-dacitic. Loseros is composed of a series of thin-bedded to laminated pyroclastic surge deposits in continuous and concordant contact with overlying Bufa massive ignimbrite. Bufa ignimbrite is partly welded, with columnar jointing, completely devitrified, and highly silicified by post-deposition hydrothermalism and/or vapor phase alteration. Co-ignimbrite lithic lag breccias are observed at several sites in

  3. The Amazcala caldera, Queretaro, Mexico. Geology and geochronology

    Science.gov (United States)

    Aguirre-Díaz, Gerardo J.; López-Martínez, Margarita

    2001-11-01

    The Amazcala caldera is located 30 km NE of Querétaro City, near Amazcala, state of Querétaro. This caldera is the northernmost caldera within the central sector of the Mexican Volcanic Belt (MVB). It has a 11×14 km 2 elliptical shape, and was formed 7.3-6.6 Ma ago. All caldera products are rhyolites. The oldest caldera unit, the Ezequiel Montes pumice (EMP), is a widespread pumice fallout emplaced around 7.3 Ma ago. An isopach map of the EMP shows two dispersal axes, oriented to the SW and SE with respect to the caldera. The EMP is 5 m thick 40 km to the SW and 35 km to the SE of the caldera. An isopleth map of the EMP shows that pumice fragments increase in size toward the caldera, from 1 cm at 40 km to 25 cm near the caldera rim. The EMP is a regional stratigraphic marker. The Colón ignimbrite, dated at 7.3±0.5 Ma, is stratigraphically above the EMP. It consists of several ash-flow units interbedded with minor pumice fall lapilli and ash, with a minimum thickness of about 80 m at Colón. The caldera rim is occupied by several rhyolite lava domes and flows, some of which extend 10 km from the rim. These domes contain parts of fresh, aphyric obsidian. The last caldera event is an intracaldera rhyolitic dome near the NE rim at about 6.6 Ma. The dome is 4×2 km 2 and is elongated in the NE direction. The Amazcala caldera is 480 km from the Middle America Trench and represents the farthest inland caldera in the central sector of the MVB. Its age of 7.3-6.6 Ma indicates that it is the oldest caldera of the MVB so far reported. This confirms the general view that the volcanic activity of the MVB initiated at its northern margin, and then migrated southward in time.

  4. Graafikatriennaalil osalev Juan Manuel Echavarria saabub Tallinna

    Index Scriptorium Estoniae

    2011-01-01

    12.-15. aprillini 2011 külastab Tallinna Columbia kunstnik Juan Manuel Echavarria. Tema holograafiliste trükiste sarjast "Reekviem NN" (2008-2010), mida eksponeeritakse Tallinna XV graafikatriennaalil Kumu Kunstimuuseumis

  5. Graafikatriennaalil osalev Juan Manuel Echavarria saabub Tallinna

    Index Scriptorium Estoniae

    2011-01-01

    12.-15. aprillini 2011 külastab Tallinna Columbia kunstnik Juan Manuel Echavarria. Tema holograafiliste trükiste sarjast "Reekviem NN" (2008-2010), mida eksponeeritakse Tallinna XV graafikatriennaalil Kumu Kunstimuuseumis

  6. Geologic Map of the Valles Caldera, Jemez Mountains, New Mexico

    Science.gov (United States)

    Goff, F.; Gardner, J. N.; Reneau, S. L.; Kelley, S. A.; Kempter, K. A.; Lawrence, J. R.

    2011-12-01

    Valles caldera is famous as the type locality of large resurgent calderas (Smith and Bailey, 1968), the location of a classic 260-300 °C liquid-dominated geothermal system (Goff and Gardner, 1994), and the site of a long-lived late Pleistocene lake (Fawcett et al., 2011). We have published a detailed color geologic map of the Valles caldera and surrounding areas at 1:50,000 scale obtainable from New Mexico Bureau of Geology and Mineral Resources (geoinfo.nmt.edu/publications/maps/geologic/gm/79/). The new Valles map has been compiled from all or parts of nine 1:24,000 geologic maps completed between 2004 and 2008 (Bland, Cerro del Grant, Jarosa, Jemez Springs, Polvadera Peak, Redondo Peak, Seven Springs, Valle San Antonio, and Valle Toledo). Our map provides more detailed geology on the resurgent dome, caldera collapse breccias, post-caldera lava and tuff eruptions, intracaldera sedimentary and lacustrine deposits, and precaldera volcanic and sedimentary rocks than previous maps and incorporates recent stratigraphic revisions to the geology of the Jemez Mountains volcanic field. Three cross sections supported by surface geology, geophysical data and deep borehole logs (≤4500 m) show an updated view of the caldera interior, depict a modern interpretation of caldera collapse and resurgence, and provide caldera-wide subsurface isotherms (≤500 °C). A 30 page booklet included with the map contains extensive rock descriptions for 162 stratigraphic units and figures showing physiographic features, structural relations between Valles (1.25 Ma) and the earlier, comparably sized Toledo caldera (1.62 Ma), correlation charts of map units, and the distribution of pre- and post-caldera hydrothermal alteration styles, including recently documented zeolite-type alteration. Finally, the booklet includes a generalized model showing our interpretation of intracaldera structure and subjacent magma chambers, and relations of Valles to earlier Quaternary-Precambrian units.

  7. Krakatau caldera deposits: revisited and verification by geophysical means

    Directory of Open Access Journals (Sweden)

    Izumi Yokoyama

    2014-10-01

    Full Text Available  One of the differences between volcanic craters and calderas is that the latter bottoms are flatways filled with caldera deposit with lower density in comparison to country rocks. The 1883 Krakatau eruption affords us important knowledge on caldera formation even if it was not observed with modern sophisticated instruments. First, volcanic activities of the Krakatau Islands before and after the 1883 eruption are reexamined: previous suppositions involving a caldera-forming eruption of the proto-Krakatau prior to 1883 proved to be unsupported by the bathymetric topographies and gravity anomalies on and around the Krakatau Islands. Then, Anak Krakatau is interpreted as a parasitic cone of the main Krakatau volcano. As supplementary knowledge to discussion of caldera deposits, the results of drillings at several calderas in Japan and Mexico are introduced. Mass deficiency of the caldera deposit at Krakatau caldera is estimated by the gravity anomaly observed there and converted to probable volume with suitable density. For quantitative examination of the subsurface structure beneath the Krakatau complex, spatial distributions of seismic S-wave attenuation and Vp/Vs ratios have been already studied by temporary seismological observations and their results have been published. The high ratios of Vp/Vs observed approximately at Krakatau caldera may be attributable to the caldera deposit that is low density and contain much water. As additional remarks, a zone having both the characters, S-wave attenuation and zones of relatively high Vp/Vs ratio, may be a probable magma reservoir centering at a depth of about 10 km.

  8. Caldera collapse at near-ridge seamounts: an experimental investigation

    Science.gov (United States)

    Coumans, Jason P.; Stix, John

    2016-10-01

    Collapse calderas are sub-circular volcanic depressions caused by subsidence of the magma reservoir roof during an eruption. Scaled physical models of caldera collapse using flat topography have been instrumental in investigating the spatial and temporal development of calderas, in particular, two distinctive sets of concentric ring faults, one reverse and one normal. More recent analog studies have investigated the effect of non-flat topography which alters the principle stress trajectories and resulting collapse structure. This work provides the basis for investigating how naturally scaled topographic loads may affect caldera collapse in relation to shallow magma reservoirs. The objective of this study is to understand how a near-ridge seamount affects caldera collapse from both a central and offset position as the seamount migrates above the magma reservoir as a result of plate motion. We utilize scaled analog models of caldera collapse in conjunction with three-dimensional (3D) laser scanning and digital particle image velocimetry (DPIV) to investigate caldera collapse dynamics at near-ridge seamounts. Experiments using a seamount cone positioned centrally above the magma reservoir result in (1) increased subsidence along the interior outward-dipping faults and (2) a preference to more symmetric collapse patterns as indicated by the subsidence profile and structure of the caldera relative to experiments with an offset cone. When the cone is offset, the collapse is asymmetric and trapdoor in nature, with the center of greatest subsidence displaced away from the region of largest topographic load. For these latter experiments, subsidence is focused where the roof is thinnest along an initial reverse fault, followed by a transition to an antithetic graben structure. The asymmetric collapse in the experiments results in a caldera with a tilted profile. Offset calderas at near-ridge seamounts are tilted towards the ridge axis, suggesting that they may have collapsed

  9. How piecemeal is your caldera? Going beyond modelling to investigate the structural evolution of explosive caldera volcanoes

    Science.gov (United States)

    Willcox, Chris; Branney, Mike; Carrasco-Núñez, Gerardo

    2008-10-01

    Despite a profusion of analogue models relatively little is known about the internal structure and temporal evolution of explosive caldera volcanoes. So how can modellers test their predictions given that the internal structures of many young calderas are concealed? Mapping ancient exhumed calderas has proven advantageous, yet this requires a large investment of time and expertise to constrain the structural evolution in sufficient detail. We aim to investigate the interplay between the structural evolution and eruption style over time at a modern caldera. We have selected Los Humeros (Mexico) because it is thought to be an example of a caldera with some piecemeal development, and it also has a well-exposed pyroclastic succession and abundant borehole data.

  10. 33 CFR 165.754 - Safety Zone: San Juan Harbor, San Juan, PR.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Safety Zone: San Juan Harbor, San Juan, PR. 165.754 Section 165.754 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY REGULATED NAVIGATION AREAS AND LIMITED ACCESS AREAS Specific Regulated Navigation Areas and...

  11. Evolution of deep collapse caldera: from structural to gravitational process

    Science.gov (United States)

    Geshi, N.; Acocella, V.; Ruch, J.

    2012-04-01

    We discuss the evolution of deep-subsiding caldera mainly controlled by gravitational process. Progress of caldera subsidence increases its subsidence/diameter ratio (S/D ratio). We investigate the surface features of calderas undergoing significant subsidence with regard to their diameter. First, we consider the evolution of the 2000 Miyakejima caldera, from double-concentric ring faults at earlier collapsing stages, to a gravitational-erosion dominant stage at a mature stage. When the topographic S/D approaches 0.33, the topographic S/D (hereafter S/Dt) becomes significantly different from the structural S/D (hereafter S/Ds), owing to the gravitational erosion on the caldera wall and accumulation of the debris on the floor. As collapse progresses, the peripheral block bounded by the inner reverse fault and outer normal fault extends and tilts towards the caldera center; it finally collapses towards the caldera floor and the double-ring faults disappeares. Subsidence of the caldera floor induces the gravitational erosion of the wall. This process increases the topographic diameter and the filling of the floor decreases the topographic depth. Consequently, the S/Dt decreases, while the continuous caldera subsidence increases the S/Ds. This evolution finds close similarities with the caldera collapses of Krakatau (1883), Katmai (1912), Fernandina (1968), Tolbachik (1975-76), Pinatubo (1991) and Dolomieu (2007). Analogue experiments mimic the observed variation, evolving from a depression controlled by the activity of the double-ring faults to that controlled by the gravitational slumping of the wall and sedimentation at the floor. The transition occurs for S/Dt ~0.34. These results show that the control on the shape of mature calderas (S/Ds>0.07) and approaching S/Dt=0.3 passes from a mainly structural to a mainly gravitational type. Both S/Dt and S/Ds are needed to describe the evolution of a collapse and the processes accompanying it. Evaluating the S/Dt and S

  12. Regional and local tectonics at Erta Ale caldera, Afar (Ethiopia)

    Science.gov (United States)

    Acocella, Valerio

    2006-10-01

    Erta Ale volcano lies along the on-shore Red Sea Rift (northern Afar, Ethiopia), separating the Nubia and Danakil plates. Erta Ale has a NNW-SSE elongated caldera, with a subvertical rim scarp, hosting a lava lake. Structural field work was aimed at defining the deformation pattern around the caldera. The caldera consists of along-rim and across-rim structures, resulting from local and regional (maximum extension ˜NE-SW) stress fields, respectively. These structures cross-cut each other at high angles, suggesting that the two stress fields remain distinct, each prevailing during rifting or caldera collapse. The local along-rim extensional fractures are gravity-driven structures that formed due to the retreat of the caldera wall after collapse, and are confined to the region of caldera subsidence. The across-rim structures are mainly located to the N and S of the caldera, where they form rift zones each accommodating a similar amount of extension (˜6.3 m), but displaying different trends and extension directions. Analogue models of interacting fractures are consistent with the Southern Rift being representative of the regional fault kinematics, while the Northern Rift is a local perturbation, resulting from the interaction between two right-stepping rift segments along the Erta Ale Range.

  13. Geodetic Characterization of Santorini Caldera From Continuous GPS Measurements

    Science.gov (United States)

    Farmer, G. T.; Newman, A. V.; Psimoulis, P.; Stiros, S.

    2007-12-01

    Santorini Caldera, in the southern Aegean, is part of a well developed, and very active volcanic system fueled by subduction along the Hellenic arc. The caldera is partially submerged, with only pieces of caldera wall, flanks, and central post-caldera lavas exposed above the sea level comprising a grouping of five small islands. The system had its most recent caldera-forming event around 1650 B.C. in a massive series of Plinean eruptions that expelled some 60 km3 of volcanic material, burying the previous island surface. The system remains active with ongoing smaller pyroclastic and phreatic eruptions, forming the central islets atop of the submerged caldera floor. In late-spring 2006, with UNAVCO field support and support form the Santorini Volcano Observatory, a network of two continuous GPS monuments spanning the caldera was established, and completion of a third monument is planned for this coming year. Additionally, 18 existing and new geodetic markers were first established with GPS across the 5-island group in 2006. These locations cover the caldera rim and flanks, and the central volcanic flows. Preliminary data from the two continuous GPS sites suggest that deformation across the caldera is currently minimal, and below the detection threshold for the 1.5 year continuous network. Through continuing analysis of the continuous network, along with additional campaign measurements, we hope to establish the temporal character and spatial extent of potential deformation in the volcanic complex, and determine if there exists any significant transient deformation associated with ongoing magma movement or edifice cooling. Monitoring such a rate over time may be useful for early hazard awareness and mitigation during regional volcanic crises.

  14. Stratigraphy of Reforma Caldera, Baja California Sur, Mexico

    Science.gov (United States)

    García Sánchez, L.; Macias, J. L.; Osorio, L. S.; Pola, A.; Avellán, D. R.; Arce, J. L.; Saucedo, R.; Sánchez, J. M.; García-Tenorio, F.; Cisneros, G.; Reyes-Agustín, G.; Cardona, S.; Jimenez, A.

    2015-12-01

    The Reforma caldera is located at ~35 km to the northwest of Santa Rosalía in the central part of the Baja California peninsula. It has 10 km in diameter and a maximum height of 1200 masl in the center and between 100 and 500 masl in its slopes. Reforma is within a tectonic zone affected by two fault systems: A NW-SE normal fault system linked to the opening of the Gulf of California, and a NNW-SSE and NW-SE strike-slip fault system associated with an active Riedel system. Reforma was built upon Cretaceous granites that outcrop at the caldera center, Miocene to Pliocene volcano-sedimentary rocks of the Comondú group, and Miocene marine sediments of the Santa Rosalía basin. On top of these rocks outcrop at least four submarine to subaerial ignimbrites interbedded with marine fossiliferous beds and the lower Pleistocene deposits associated to the Reforma caldera. These deposits are formed by a ignimbrite that shifts to different lithofacies that change gradually their welding, here dubbed basal, transitional, intermediate, and upper (all of then enriched in black fiammes), followed by a pumice-rich, white fiammes, and vitrophyre lithofacies, which are distributed around the 9 km wide caldera and have been associated to the caldera formation episode. Deposits related to post-caldera volcanism are andesite-basaltic lava flows erupted along the caldera rim through localized feeding dikes and andesitic and rhyolitic domes, and scoria cinder cones exposed inside and outside the caldera. On top of these deposits rest the middle Pleistocene Aguajito caldera deposits.

  15. Fray Juan Rizi en Italia

    Directory of Open Access Journals (Sweden)

    Salort Pons, Salvador

    1999-03-01

    Full Text Available Since Tormo, Gusi and Lafuente wrote fray Juan Rizi's monograph in 1930, and Ángulo & Pérez Sánchez revised years later this study in their book Pintura madrileña del segundo tercio del siglo XVII, very little has been published about the life and work of the Benedictine painter. Furthermore, the Italian journey of Rizi, that involved the last 20 years of his life, has always been an enigma, resolved only in certain aspects, thanks to few news supplied by his biographers and the manuscripts the monk wrote during his staying in the Montecassino abbey. Our recent discovery of 8 new canvases painted by Rizi to decorate the Saints Cosme and Damian's chapel in the main church of Trevi nel Lazio (Frosinone, Italy, as well as the location of several new drawings in the Montecassino and Vatican libraries, will allow us to study his activity as painter in Italy and also to profile, with more accuracy, the history of the last years of his life.No disponible

  16. 76 FR 12692 - San Juan National Forest Resource Advisory Committee

    Science.gov (United States)

    2011-03-08

    ... Forest Service San Juan National Forest Resource Advisory Committee AGENCY: Forest Service, USDA. ACTION: Notice of meeting. SUMMARY: The San Juan National Forest Resource Advisory Council (RAC) will meet in... comments should be sent to Attn: San Juan National Forest RAC, 15 Burnett Court, Durango, CO 81301...

  17. 76 FR 40876 - San Juan National Forest Resource Advisory Committee

    Science.gov (United States)

    2011-07-12

    ... Forest Service San Juan National Forest Resource Advisory Committee AGENCY: Forest Service, USDA. ACTION: Notice of meeting. SUMMARY: The San Juan National Forest Resource Advisory Council (RAC) will meet in... Sonoran Meeting Rooms. Written comments should be sent to Attn: San Juan National Forest RAC, 15 Burnett...

  18. 75 FR 48306 - San Juan National Forest Resource Advisory Committee

    Science.gov (United States)

    2010-08-10

    ... Forest Service San Juan National Forest Resource Advisory Committee AGENCY: Forest Service, USDA. ACTION: Notice of meeting. SUMMARY: The San Juan National Forest Resource Advisory Council (RAC) will meet in... comments should be sent to Attn: San Juan National Forest RAC, 15 Burnett Court, Durango, CO 81301...

  19. Magma storage in a strike-slip caldera

    Science.gov (United States)

    Saxby, J.; Gottsmann, J.; Cashman, K.; Gutiérrez, E.

    2016-07-01

    Silicic calderas form during explosive volcanic eruptions when magma withdrawal triggers collapse along bounding faults. The nature of specific interactions between magmatism and tectonism in caldera-forming systems is, however, unclear. Regional stress patterns may control the location and geometry of magma reservoirs, which in turn may control the spatial and temporal development of faults. Here we provide new insight into strike-slip volcano-tectonic relations by analysing Bouguer gravity data from Ilopango caldera, El Salvador, which has a long history of catastrophic explosive eruptions. The observed low gravity beneath the caldera is aligned along the principal horizontal stress orientations of the El Salvador Fault Zone. Data inversion shows that the causative low-density structure extends to ca. 6 km depth, which we interpret as a shallow plumbing system comprising a fractured hydrothermal reservoir overlying a magmatic reservoir with vol% exsolved vapour. Fault-controlled localization of magma constrains potential vent locations for future eruptions.

  20. Magma storage in a strike-slip caldera.

    Science.gov (United States)

    Saxby, J; Gottsmann, J; Cashman, K; Gutiérrez, E

    2016-07-22

    Silicic calderas form during explosive volcanic eruptions when magma withdrawal triggers collapse along bounding faults. The nature of specific interactions between magmatism and tectonism in caldera-forming systems is, however, unclear. Regional stress patterns may control the location and geometry of magma reservoirs, which in turn may control the spatial and temporal development of faults. Here we provide new insight into strike-slip volcano-tectonic relations by analysing Bouguer gravity data from Ilopango caldera, El Salvador, which has a long history of catastrophic explosive eruptions. The observed low gravity beneath the caldera is aligned along the principal horizontal stress orientations of the El Salvador Fault Zone. Data inversion shows that the causative low-density structure extends to ca. 6 km depth, which we interpret as a shallow plumbing system comprising a fractured hydrothermal reservoir overlying a magmatic reservoir with vol% exsolved vapour. Fault-controlled localization of magma constrains potential vent locations for future eruptions.

  1. Juan Eduardo Cirlot on Skryabin's Synesthetic Art

    OpenAIRE

    2012-01-01

    En este trabajo mostramos cómo el poeta y pensador español Juan Eduardo Cirlot (Barcelona, 1916–1973) y el compositor ruso Aleksandr Skriabin compartieron un interés artístico poro el fenómeno de la sinestesia, a pesar de la distancia cronológica entre ambos y la falta de relaciones diplomáticas y (al menos, oficialmente) culturales entre sus respectivos países, durante la vida creativa de Juan Eduardo Cirlot.

  2. Can the structure of an explosive caldera affect eruptive behaviour?

    Science.gov (United States)

    Willcox, C. P.; Branney, M.; Carrasco-Nuñez, G.; Barford, D.

    2010-12-01

    Explosive caldera volcanoes cause catastrophic events at the Earth’s surface, yet we know little about how their internal structures evolve with time, and whether this can affect both differentiation and eruptive behaviour. Distinguishing how structural evolution impacts upon eruption behaviour and periodicity is challenging because the resolution of eruption frequencies can be difficult at ancient exhumed calderas, whereas at young volcanoes, most of the caldera floor faults and associated conduits are hidden. Some exhumed calderas reveal caldera floor faults and conduits; some of these apparently underwent a single collapse event that was piecemeal, i.e. fragmentation into several, variously subsided fault-blocks (e.g. Scafell caldera, UK). In contrast, the present study tests whether some caldera volcanoes may become more intensely fractured with time as a result of successive distinct caldera-collapse eruptions (“multi-cyclic calderas”). It has been proposed that this scenario could lead to an increase in eruption frequency, with smaller eruptions over time. Magma leakage through the increasingly fractured volcano might also lead to less evolved compositions with time due to shorter residence times. We have returned to the volcano where this hypothesis was formulated, the ~ 20 km diameter, hydrothermally active Los Humeros caldera in eastern central México. We aim to see how well the structural evolution of this modern caldera can be reconstructed, and whether changes in structure affected the styles and periodicity of large explosive eruptions. How a caldera evolves structurally could have important implications for predicting future catastrophic eruptions. Detailed structural mapping (e.g. of fault scarps, vent positions, and tilted strata), documentation of draping and cross-cutting field relations, together with logging, optical and SEM petrography, XRF major and trace element geochemistry and new 40Ar-39Ar and radiocarbon dating of the pyroclastic

  3. Submarine Volcanic Morphology of Santorini Caldera, Greece

    Science.gov (United States)

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

    2012-04-01

    Santorini volcanic group form the central part of the modern Aegean volcanic arc, developed within the Hellenic arc and trench system, because of the ongoing subduction of the African plate beneath the European margin throughout Cenozoic. It comprises three distinct volcanic structures occurring along a NE-SW direction: Christianna form the southwestern part of the group, Santorini occupies the middle part and Koloumbo volcanic rift zone extends towards the northeastern part. The geology of the Santorini volcano has been described by a large number of researchers with petrological as well as geochronological data. The offshore area of the Santorini volcanic field has only recently been investigated with emphasis mainly inside the Santorini caldera and the submarine volcano of Kolumbo. In September 2011, cruise NA-014 on the E/V Nautilus carried out new surveys on the submarine volcanism of the study area, investigating the seafloor morphology with high-definition video imaging. Submarine hydrothermal vents were found on the seafloor of the northern basin of the Santorini caldera with no evidence of high temperature fluid discharges or massive sulphide formations, but only low temperature seeps characterized by meter-high mounds of bacteria-rich sediment. This vent field is located in line with the normal fault system of the Kolumbo rift, and also near the margin of a shallow intrusion that occurs within the sediments of the North Basin. Push cores have been collected and they will provide insights for their geochemical characteristics and their relationship to the active vents of the Kolumbo underwater volcano. Similar vent mounds occur in the South Basin, at shallow depths around the islets of Nea and Palaia Kameni. ROV exploration at the northern slopes of Nea Kameni revealed a fascinating underwater landscape of lava flows, lava spines and fractured lava blocks that have been formed as a result of 1707-1711 and 1925-1928 AD eruptions. A hummocky topography at

  4. San Juan Islands National Wildlife Refuge : San Juan Wilderness : Wilderness management plan

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document is a plan regarding management of the San Juan Wilderness. After introducing the area, it analyzes current management practices against current public...

  5. Venus - A Large Elongated Caldera 'Sacajawea Patera

    Science.gov (United States)

    1991-01-01

    This Magellan image reveals Sacajawea Patera, a large, elongate caldera located in Western Ishtar Terra on the smooth plateau of Lakshmi Planum. The image is centered at 64.5 degrees North latitude and 337 degrees East longitude. It is approximately 420 kilometers (252 miles) wide at the base. Sacajawea is a depression approximately 1-2 kilometers (0.6-1.2 miles) deep and 120 x 215 kilometers (74 x 133 miles) in diameter; it is elongate in a southwest-northeast direction. The depression is bounded by a zone of circumferential curvilinear structures interpreted to be graben and fault scarps. These structures are spaced 0.5-4 kilometers (0.3-2.5 miles) apart, are 0.6-4.0 kilometers (0.4-2.5 miles) in width and up to 100 kilometers (62 miles) in length. Extending up to approximately 140 kilometers (87 miles) in length from the southeast of the patera is a system of linear structures thought to represent a flanking rift zone along which the lateral injection and eruption of magma may have occurred. A shield edifice 12 kilometers (7 miles) in diameter with a prominent central pit lies along the trend of one of these features. The impact crater Zlata, approximately 6 kilometers (4 miles) in diameter is located within the zone of graben to the northwest of the patera. Few flow features are observed in association with Sacajawea, possibly due to age and state of degradation of the flows. Mottled bright deposits 4-20 kilometers (2.5-12 miles) in width are located near the periphery and in the center of the patera floor within local topographic lows. Diffuse patches of dark material approximately 40 kilometers (25 miles) in width are observed southwest of the patera, superposed on portions of the surrounding graben. The formation of Sacajawea is thought to be related to the drainage and collapse of a large magma chamber. Gravitational relaxation may have caused the resultant caldera to sag, producing the numerous faults and graben that circumscribe the patera. Regions of

  6. Geology and structure of the Malpaso caldera and El Ocote ignimbrite, Aguascalientes, Mexico

    Science.gov (United States)

    Nieto-Obregón, Jorge; Aguirre-Díaz, Gerardo

    2008-10-01

    A new caldera, named Malpaso, is reported west of the city of Aguascalientes, Mexico. The Malpaso caldera is a volcano-tectonic depression, highly fractured and faulted, and was filled by voluminous pyroclastic products related to the caldera collapse. Due to these characteristics it as a graben caldera. It is truncated by younger normal faults of the Calvillo and Aguascalientes grabens. In this work we present a summary of the geologic and structural observations on this caldera, as well as a description of the main caldera product, the high-grade El Ocote ignimbrite.

  7. Saga y fugas de Don Juan

    OpenAIRE

    Pérez-Bustamante Mourier, Ana Sofía

    1998-01-01

    Ensayo acerca de las diversas versiones e interpretaciones que a lo largo de la historia ha suscitado el mito de Don Juan Tenorio. Lectura original del donjuanismo a partir de las teorías del filósofo José Antonio Marina en torno al ingenio y sus productos.

  8. On Byronic Heroism in Don Juan

    Institute of Scientific and Technical Information of China (English)

    李曼琦

    2011-01-01

    Byron is the chief exponent and the most important figure of the "Romantic Movement".And Byronic heroism is one of his most important representatives of his literary contribution.In his masterpiece Don Juan,Byron exploits the whole range of his feelings a

  9. Juan Carlos D'Olivo: A portrait

    Science.gov (United States)

    Aguilar-Arévalo, Alexis A.

    2013-06-01

    This report attempts to give a brief bibliographical sketch of the academic life of Juan Carlos D'Olivo, researcher and teacher at the Instituto de Ciencias Nucleares of UNAM, devoted to advancing the fields of High Energy Physics and Astroparticle Physics in Mexico and Latin America.

  10. San Juan Uchucuanicu: évolution historique

    Directory of Open Access Journals (Sweden)

    1975-01-01

    Full Text Available La communauté de San Juan est reconnue depuis 1939. Une première partie concerne l’organisation de la reducción de San Juan vers le milieu du XVIe siècle. Le poids fiscal s’exerce durement sur le village et la crise est générale dans toute la vallée du Chancay au XVIIe. siècle. La christianisation des habitants est définitive au milieu de ce même siècle. C’est vers la fin du XVIIe siècle et durant tout le XVIIIe que se multiplient les conflits entre San Juan et les villages voisins liés aux terrains de pâture et à la possession de l’eau. La deuxième partie du travail concerne les rapports de la communauté de San Juan avec le Pérou contemporain : contrainte fiscale toujours très lourde durant la fin de l’époque coloniale, exactions des militaires juste avant l’indépendance. La période républicaine voit toujours les conflits avec les villages voisins mais aussi la naissance de familles qui cherchent à retirer le maximum de la communauté. Les terres sont divisées et attribuées : la détérioration de l’organisation communale traditionnelle est manifeste. L4es conflits se multiplient entre petits propriétaires, mais aussi avec les haciendas voisines : c’est l’apparition d’une véritable lutte de classes. La situation actuelle est incertaine, le poids de l’économie marchande se développe avec l’exode des jeunes. Que sera la communauté San Juan à la fin de ce siècle? La comunidad de San Juan está reconocida desde 1939. La primera parte concierne a la organización de la 'reducción' de San Juan hacia mediados del siglo XVI. El peso fiscal se ejerce duramente sobre el pueblo y en el siglo XVII la crisis es general en todo el valle de Chancay. Hacia mediados del mismo siglo la cristianización de los habitantes es definitiva. Es hacia fines del siglo XVII y durante todo el siglo XVIII que se multiplican los conflictos entre San Juan y los pueblos vecinos, los que están relacionados con los terrenos de

  11. Science guide for the Long Valley Caldera deep hole

    Energy Technology Data Exchange (ETDEWEB)

    Rundle, J.B.; Eichelberger, J.C. (eds.)

    1989-05-01

    The Magma Energy Program of the US Department of Energy, Geothermal Technology Division, is planning to begin drilling a deep (6 km) exploration well in Long Valley Caldera, California, in September 1988. The location of the well is in the central part of the caldera, coincident with a large number of shallow (5-7 km) geophysical anomalies identified through many independent investigations. Results from the hole will permit the following: direct investigation of the geophysical anomalies interpreted to be magma; investigation of the patterns and conditions of deep fluid circulation and heat transport below the caldera floor; determination of the amount of collapse and subsequent resurgence of the central portion of Long Valley caldera; and determination of the intrusion history of the central plutonic complex beneath the caldera, and establishment of the relationship of intrusive to eruptive events. The hole will thus provide a stringent test of the hypothesis that magma is still present within the central plutonic complex. If the interpretation of geophysical anomalies is confirmed, the hole will provide the first observations of the environment near a large silicic magma chamber. 80 refs., 7 figs., 2 tabs.

  12. Scaling properties of planetary calderas and terrestrial volcanic eruptions

    Directory of Open Access Journals (Sweden)

    L. Sanchez

    2012-11-01

    Full Text Available Volcanism plays an important role in transporting internal heat of planetary bodies to their surface. Therefore, volcanoes are a manifestation of the planet's past and present internal dynamics. Volcanic eruptions as well as caldera forming processes are the direct manifestation of complex interactions between the rising magma and the surrounding host rock in the crust of terrestrial planetary bodies. Attempts have been made to compare volcanic landforms throughout the solar system. Different stochastic models have been proposed to describe the temporal sequences of eruptions on individual or groups of volcanoes. However, comprehensive understanding of the physical mechanisms responsible for volcano formation and eruption and more specifically caldera formation remains elusive. In this work, we propose a scaling law to quantify the distribution of caldera sizes on Earth, Mars, Venus, and Io, as well as the distribution of calderas on Earth depending on their surrounding crustal properties. We also apply the same scaling analysis to the distribution of interevent times between eruptions for volcanoes that have the largest eruptive history as well as groups of volcanoes on Earth. We find that when rescaled with their respective sample averages, the distributions considered show a similar functional form. This result implies that similar processes are responsible for caldera formation throughout the solar system and for different crustal settings on Earth. This result emphasizes the importance of comparative planetology to understand planetary volcanism. Similarly, the processes responsible for volcanic eruptions are independent of the type of volcanism or geographical location.

  13. Geodetic Observations of Ongoing Unrest at Santorini Caldera, Greece

    Science.gov (United States)

    Newman, A. V.; Stiros, S. C.; Moschas, F.; Saltogianni, V.; Feng, L.; Psimoulis, P.; Jiang, Y.; Karakas, O.; Polster, S.

    2012-12-01

    After approximately 60 years of seismic quiescence within Santorini caldera, in January 2011 the volcano reawakened with a significant seismic swarm and rapidly expanding near-radial deformation. Using a combination of 10 continuous and 22 campaign GPS stations with observations beginning in 2006, we've captured the onset, and 3D shape of surface deformation. Deformation primarily radiates from inside the northern half of the caldera, with episodic growth periods lasting several months at a time. As of this writing, the caldera has expanded laterally about 185 mm, and uplifted at least 80 mm (with the maximum uplift likely occurring under the submerged caldera floor—unobservable by GPS). We will discuss the current geodetic evolution including continuous and 4 GPS campaigns during the period of unrest, exploring new numerical models to address the accompanying stress evolution of the system. We recognize that only anelastic inflation models including volumetric addition and viscoelastic relaxation or discrete dislocation will allow such growth to occur without a long-term stress increase. While observations of the current deformation sequence are unprecedented at Santorini, it is not certain that they mark the early stages of a process leading to an eruption given that other similar calderas have experienced comparable activity without eruption.

  14. The magmatic engine of unrest episodes at Campi Flegrei caldera (southern Italy)

    OpenAIRE

    Moretti, R.; G. Berrino; Arienzo, I.; Chiodini, G.; L. Civetta; Orsi, G.

    2009-01-01

    Volcanic calderas are affected by unrest episodes usually dominated by hybrid magmatic-hydrothermal system dynamics, but which can evolve to variable intensity eruptions, up to Plinian. Campi Flegrei caldera...

  15. Thermogladius calderae gen. nov., sp. nov., an anaerobic, hyperthermophilic crenarchaeote from a Kamchatka hot spring.

    Science.gov (United States)

    Kochetkova, Tatiana V; Kublanov, Ilya V; Toshchakov, Stepan V; Osburn, Magdalena R; Novikov, Andrei A; Bonch-Osmolovskaya, Elizaveta A; Perevalova, Anna A

    2016-01-21

    An obligately anaerobic, hyperthermophilic, organoheterotrophic archaeon, strain 1633T, was isolated from a terrestrial hot spring of the Uzon Caldera (Kamchatka Peninsula, Russia). Cells were regular cocci, 0.5-0.9 μm in diameter, with one flagellum. The temperature range for growth was 80-95°C, with an optimum at 84°C. Strain 1633T grew on yeast extract, beef extract, peptone, cellulose and cellobiose. No growth was detected on other sugars or carbohydrates, organic acids, or under autotrophic conditions. The only detected growth products were CO2, acetate, and H2. Growth rate was stimulated by elemental sulfur, which was reduced to hydrogen sulfide. In silico calculated G+C content of strain 1633T genomic DNA was 55.64 mol%. 16S rRNA gene sequence analysis placed the strain 1633T together with the non-validly published "Thermogladius shockii" strain WB1 in a separate genus-level cluster within the Desulfurococcaceae family. ANI results revealed 75.72% identity between 1633T and WB1. Based on these results we propose a novel genus and species, for which the name Thermogladius calderae gen. nov., sp. nov. (type strain 1633T=DSM 22663T=VKM B-2946T) is proposed.

  16. Post-eruptive flooding of Santorini caldera and implications for tsunami generation

    OpenAIRE

    Nomikou, P.; Druitt, TH; H?bscher, C; Mather, TA; Paulatto, M.; Kalnins, LM; Kelfoun, K.; Papanikolaou, D.; Bejelou, K.; Lampridou, D; Pyle, DM; Carey, S.; Watts, AB; Wei, B.; Parks, MM

    2016-01-01

    Caldera-forming eruptions of island volcanoes generate tsunamis by the interaction of different eruptive phenomena with the sea. Such tsunamis are a major hazard, but forward models of their impacts are limited by poor understanding of source mechanisms. The caldera-forming eruption of Santorini in the Late Bronze Age is known to have been tsunamigenic, and caldera collapse has been proposed as a mechanism. Here, we present bathymetric and seismic evidence showing that the caldera was not ope...

  17. Cluster-cluster clustering

    Science.gov (United States)

    Barnes, J.; Dekel, A.; Efstathiou, G.; Frenk, C. S.

    1985-01-01

    The cluster correlation function xi sub c(r) is compared with the particle correlation function, xi(r) in cosmological N-body simulations with a wide range of initial conditions. The experiments include scale-free initial conditions, pancake models with a coherence length in the initial density field, and hybrid models. Three N-body techniques and two cluster-finding algorithms are used. In scale-free models with white noise initial conditions, xi sub c and xi are essentially identical. In scale-free models with more power on large scales, it is found that the amplitude of xi sub c increases with cluster richness; in this case the clusters give a biased estimate of the particle correlations. In the pancake and hybrid models (with n = 0 or 1), xi sub c is steeper than xi, but the cluster correlation length exceeds that of the points by less than a factor of 2, independent of cluster richness. Thus the high amplitude of xi sub c found in studies of rich clusters of galaxies is inconsistent with white noise and pancake models and may indicate a primordial fluctuation spectrum with substantial power on large scales.

  18. Cluster-cluster clustering

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, J.; Dekel, A.; Efstathiou, G.; Frenk, C.S.

    1985-08-01

    The cluster correlation function xi sub c(r) is compared with the particle correlation function, xi(r) in cosmological N-body simulations with a wide range of initial conditions. The experiments include scale-free initial conditions, pancake models with a coherence length in the initial density field, and hybrid models. Three N-body techniques and two cluster-finding algorithms are used. In scale-free models with white noise initial conditions, xi sub c and xi are essentially identical. In scale-free models with more power on large scales, it is found that the amplitude of xi sub c increases with cluster richness; in this case the clusters give a biased estimate of the particle correlations. In the pancake and hybrid models (with n = 0 or 1), xi sub c is steeper than xi, but the cluster correlation length exceeds that of the points by less than a factor of 2, independent of cluster richness. Thus the high amplitude of xi sub c found in studies of rich clusters of galaxies is inconsistent with white noise and pancake models and may indicate a primordial fluctuation spectrum with substantial power on large scales. 30 references.

  19. Modes and times of caldera resurgence: The Ischia Caldera, Italy, from high-precision archaeomagnetic dating

    Science.gov (United States)

    Vezzoli, Luigina; Principe, Claudia; Malfatti, Jonas; Arrighi, Simone; Tanguy, Jean-Claude; Le Goff, Maxime

    2009-10-01

    Ischia is a well exposed and densely populated late Quaternary caldera in the Campanian magmatic province of Italy. Ischia Caldera experienced an average uplift rate of 3.3 cm/year in the last ca. 30 ka and is still actively resurging. During the last 10 ka, coeval with the resurgence, a volcanic field of alkali-trachytic to trachyandesitic lava domes, lava flows, tuff and scoria rings, and pumice cones developed, mainly on the eastern sector of the caldera, along both resurgence-related faults and regional NNW- and NE-striking faults. In order to improve both our understanding of the recent volcanic history and the evaluation of future risks on Ischia Island, a high-precision archaeomagnetic dating method was applied to the products of 12 volcanic centres with probable age Ischia volcanism occurred in five periods separated by phases of quiescence and coeval with earthquake and landslide events. This fact suggests a pulsating mode of uplifting and deformations of the Ischia resurgence. During the two oldest periods of activity (7200-6800 BC and 4100-2300 BC), resurgence probably produced a dome-shaped structure. Location and geometry of vents suggest the occurrence of magma uprise along the fractures produced by bending of the overburden crustal block. Most of magma was emplaced as intrusions at the interior of the resurgent block, whereas volcanism was represented by very viscous, differentiated, and crystallized lavas that emplaced as domes and high aspect-ratio flows. The resurgent dome caused recurrent lateral collapses that removed about 2.5 km 3 of rocks. During the three youngest periods of activity (1800-1000 BC; 650 BC -355 AD; and 1302 AD), resurgence affected a fault-bounded, asymmetric block. This resulted from both (a) hydrostatic rebound of the crustal block after removal of material involved into huge slope instability triggering an increase in uplift rate, and (b) new influxes of less evolved magma batches into the shallow reservoir that, in turn

  20. Stable Isotopes of Tilted Ignimbrite Calderas in Nevada

    Science.gov (United States)

    John, D. A.; Watts, K. E.; Hofstra, A. H.; Colgan, J. P.; Henry, C.; Bindeman, I. N.

    2013-12-01

    Mid-Tertiary calderas are exceptionally well exposed in tilted fault blocks of the northern Great Basin, facilitating detailed evolutionary models of their magmatic-hydrothermal systems. The 29.4 Ma Job Canyon caldera, the oldest of 3 overlapping calderas in the Stillwater Range, west-central Nevada, is tilted ~90° exposing a 10-km-thick section of the crust. Large parts of the >7 km-diameter caldera system, including >2 km thickness of intracaldera rhyolitic tuff, lower parts of an ~2 km thick sequence of post-caldera intermediate lavas, and the upper 500 m of the resurgent granodioritic IXL pluton, were pervasively altered to propylitic, argillic, and sericitic assemblages. Sparse quartz×calcite veins cut the tuff. δ18O values of altered whole rock samples range from +4.8 to -9.1‰ but are mostly -6 to -9‰ at paleodepths >2 km. Calculated magmatic δ18O and δD values range from +6.4 to 8.2‰ and ~-70‰, respectively. Calculated fluid compositions using temperatures from fluid inclusions and mineral assemblages are δ18OH2O=-9.5 to -15‰ and δDH2O=-125 to -135‰ (chlorite) and -70 to -80‰ (epidote). Chlorite-whole rock data suggest fluids that were derived from moderately 18O-exchanged meteoric water. Fault blocks in north-central Nevada expose a >5 km upper crustal cross section through the 12-17 x 20 km, 34 Ma Caetano caldera, including >3 km thickness intracaldera rhyolitic Caetano Tuff. Asymmetric caldera subsidence left a depression >1 km deep partly filled with a lake. Magma resurgence and emplacement of shallow granite porphyry plutons drove a hydrothermal system that altered >120 km2 of the caldera to depths >1.5 km. Alteration was focused in an early granite porphyry intrusion and surrounding upper Caetano Tuff and lacustrine sediments. Early pervasive quartz-kaolinite-pyrite alteration grades outward and downward into more restricted quartz-illite/smectite-pyrite alteration. Hematite, quartz, and barite veins and hydrothermal breccias cut

  1. Carbonatite ring-complexes explained by caldera-style volcanism.

    Science.gov (United States)

    Andersson, Magnus; Malehmir, Alireza; Troll, Valentin R; Dehghannejad, Mahdieh; Juhlin, Christopher; Ask, Maria

    2013-01-01

    Carbonatites are rare, carbonate-rich magmatic rocks that make up a minute portion of the crust only, yet they are of great relevance for our understanding of crustal and mantle processes. Although they occur in all continents and from Archaean to present, the deeper plumbing system of carbonatite ring-complexes is usually poorly constrained. Here, we show that carbonatite ring-complexes can be explained by caldera-style volcanism. Our geophysical investigation of the Alnö carbonatite ring-complex in central Sweden identifies a solidified saucer-shaped magma chamber at ~3 km depth that links to surface exposures through a ring fault system. Caldera subsidence during final stages of activity caused carbonatite eruptions north of the main complex, providing the crucial element to connect plutonic and eruptive features of carbonatite magmatism. The way carbonatite magmas are stored, transported and erupt at the surface is thus comparable to known emplacement styles from silicic calderas.

  2. Magmatic evolution of the Ilopango Caldera, El Salvador, Central America

    Science.gov (United States)

    Zezin, D.; Mann, C. P.; Hernández, W.; Stix, J.

    2010-12-01

    The Ilopango caldera (16 x 13 km) is an active, long-lived magmatic system, erupting voluminous amounts of pyroclastic material numerous times over the course of its evolution. The caldera is presently water filled and the most recent activity is a dome growth event in 1880. Established age constraints from extracaldera pyroclastic sequences, indicate caldera forming events occur ~ every 10,000 years over the last 40,000 years. The most recent pyroclastic eruption (TBJ) is constrained to A.D. 429 erupting 70 km3 DRE of pyroclastic material. We combine major element and trace element chemistry with 40Ar/39Ar age constraints of the intracaldera domes and intracaldera pyroclastic deposits to extent the caldera history. The intracaldera domes are andesitic to rhyolitic in composition (57 - 76 wt. % SiO2), some with basaltic enclaves (54 wt. % SiO2) and pyroclastic units observed inside the caldera (San Agustín Pumice Breccia) are dacitic to rhyolitic in composition (69 -75 wt. % SiO2). Formation of an intracaldera andesitic dome at 359±7.9 ka provides a minimum age of caldera formation and extends the caldera history back ~ 320 ka years. The variable composition of the intracaldera domes, the presence of mafic enclaves in the dome lavas, mafic clasts in the TB4 plinian fall, mafic banding in the TB3 and TB2, attest to the obvious involvement of a more mafic magma The highly evolved compositions of the pyroclastic units and the volume of erupted material, point towards a large evolving magma reservoir at depth. The mafic magma may replenish the subsurface reservoir and act as a catalyst for volcanic eruption. The presence of an intracaldera lake, the regularity with which the volcano erupts and the presence of a more mafic magma are the ingredients for a catastrophic disaster. The Ilopango caldera, located 10 km to the east of the capital city of San Salvador (~ 1.5 million people) poses a threat both locally and globally as demonstrated 1600 years ago as it

  3. Workshop on recent research in the Valles caldera

    Energy Technology Data Exchange (ETDEWEB)

    Heiken, G. (comp.)

    1985-02-01

    Over the last 5 years, there has been increased interest in the geology of the Jemez Mountains volcanic field, New Mexico. Of special interest is the Toledo-Valles caldera complex, which is targeted for research coring as part of the Continental Scientific Drilling Program. The general topics covered in this workshop were (1) hydrothermal systems and rock-water interactions, (2) volcanology and structural framework of the Jemez volcanic field, (3) determining the presence or absence of melt below the Valles caldera, and (4) deep coring and drilling technology. Separate abstracts were prepared for each presentation.

  4. Sobre Juan Bautista Maíno

    Directory of Open Access Journals (Sweden)

    Pérez Sánchez, Alfonso E.

    1997-06-01

    Full Text Available This article published new documents about the activity of the Domenican painter Juan Bautista Maíno specially concerning his concept of the practice of Painting in relation to the other arts. Works hitherto unknown are published here for the first time. Also illustrated are portraits of the Conde de Añover de Tajo and his wife, whose collections were, in addition given valuation by the artista.No disponible

  5. Sobre Juan Bautista Maíno

    OpenAIRE

    Pérez Sánchez, Alfonso E.

    1997-01-01

    This article published new documents about the activity of the Domenican painter Juan Bautista Maíno specially concerning his concept of the practice of Painting in relation to the other arts. Works hitherto unknown are published here for the first time. Also illustrated are portraits of the Conde de Añover de Tajo and his wife, whose collections were, in addition given valuation by the artista.No disponible

  6. Seismicity, Vp/Vs and shear wave anisotropy variations during the 2011 unrest at Santorini caldera, southern Aegean

    Science.gov (United States)

    Konstantinou, K. I.; Evangelidis, C. P.; Liang, W.-T.; Melis, N. S.; Kalogeras, I.

    2013-11-01

    The Santorini caldera has been the focus of several large explosive eruptions in the past, the last of which occurred in the early 1950s. The volcano was dormant until early 2011 when increasing number of earthquakes accompanied significant intra-caldera uplift. This seismic activity was recorded by 8 temporary as well as 19 permanent seismic stations that were installed on Santorini and nearby islands after the onset of the unrest. Using data from January 2011 until June 2012 we calculated accurate relative locations for 490 events utilizing both catalog and waveform cross-correlation differential travel times of P- and S-phases. The distribution of relocated events exhibits a large cluster between Thera and Nea Kameni islands along the caldera rim, suggesting the activation of a preexisting ring fault. All hypocenters are located between 5 and 11 km resulting in a sharp cutoff of seismicity above and below these depths. We also used P and S travel times in order to calculate average Vp/Vs ratios and estimated shear wave splitting parameters (fast direction φ, delay time δt) for events within the shear wave window. The Vp/Vs ratios at several stations exhibit a majority of values consistently below the regional one (~ 1.77). Their temporal variations can be explained as periods of gas influx and depletion in the upper crust beneath the caldera. A comparison of δt for a number of earthquake doublets shows a progressive decrease of delay times towards the end of the unrest probably as a result of cracks closing owing to stress relaxation. The seismological observations presented here are compatible with petrological models that suggest the existence of a deep (11-14 km) dacitic magma reservoir and a shallower (< 5 km) rhyolitic magma chamber.

  7. Sobre el teatro del absurdo (de Juan del Encina a Juan Mateu

    Directory of Open Access Journals (Sweden)

    Serralta, Frédéric

    2005-06-01

    Full Text Available From the analysis of a few comic devices of the absurd in Don Juan Tenorio «El refugiao» —a parodical play by exiled playwright Juan Mateu, first performed in Toulouse in 1958—, this article aims at showing that a tradition is still alive —a tradition that can, non only be traced back to La venganza de don Mendo by Muñoz Seca (who did not, as has been claimed, invent the theatre of the absurd, but which is also part of an old trend stemming from Juan del Encina's famous Disparates, which has been exemplified by the burlesque plays of the seventeenth century, which was obvious in the nineteenth and early twentieth century popular liking for parodical drama, and which is still today one of the sources of what could be called humour the Spanish way.A partir del análisis de algunos mecanismos cómicos del absurdo en Don Juan Tenorio «El refugiao» —obra paródica del dramaturgo exiliado Juan Mateu estrenada en Toulouse en 1958—, el artículo pretende demostrar la persistencia de una tradición que no se remonta sólo a La venganza de don Mendo de Muñoz Seca (el cual no fue ni mucho menos, como demasiadas veces se ha dicho, el inventor del teatro del absurdo, sino que se inscribe en una vieja trayectoria arraigada en los famosos Disparates de Juan del Encina, ilustrada luego por la comedia burlesca del siglo XVII, patente en la afición popular del XIX y principios del XX al teatro paródico y que todavía hoy es una de las fuentes de lo que se podría llamar un humor «a la española».

  8. Application of the Gauss theorem to the study of silicic calderas: The calderas of La Primavera, Los Azufres, and Los Humeros (Mexico)

    Science.gov (United States)

    Campos-Enríquez, J. O.; Domínguez-Méndez, F.; Lozada-Zumaeta, M.; Morales-Rodríguez, H. F.; Andaverde-Arredondo, J. A.

    2005-10-01

    We explored applications (including limitations) of Gauss's theorem to the study of silicic calderas. First it enables us to determine the mass deficiency from calderas. Mass deficiency itself has also other potential applications. It enables to make qualitative comparisons between calderas. We can use the mass deficiency to test, in a quick way and as a preliminary step to a formal gravity inversion, for the feasibility of caldera types of simple geometry (i.e., piston subsidence and funnel models). This application can be done in a straightforward way, once the mass deficiency has been determined. For this purpose the mass deficiency is converted to the volume of material missing at the caldera. Subsequently, for example, this volume and the respective caldera diameter enable us to estimate the height of the cylinder fitting the piston subsidence model. If the obtained parameters are congruent with the known geology and geophysical information then the model may be considered further in the inversion of the gravity data for the detailed structure. Other simple models (i.e., the funnel model) can also be analyzed in this way. In particular, when working with a piston subsidence caldera type, the Gauss theorem enables us to estimate the caldera collapse (very difficult to obtain based on geologic information alone). These possible uses of Gauss's theorem are illustrated with the calderas of La Primavera, Los Azufres, and Los Humeros caldera (Mexico). The obtained mass deficiency from these calderas follow the linear mass deficiency-diameter trend observed for other calderas. In particular, because of their diameters and mass deficiencies, La Primavera and Krakatau calderas can be considered equiparable. This comparison is of the most importance considering that La Primavera is located in the neighbourhood of a metropolis (Guadalajara City). Since geophysical studies have already established a piston subsidence model for these calderas, we assessed Gauss's theorem

  9. A tale of ambiguities and interpretation pitfalls: seismology based source models for the Bárðarbunga caldera collapse earthquakes, Iceland

    Science.gov (United States)

    Heimann, Sebastian; Cesca, Simone; Hensch, Martin; Dahm, Torsten; Hjörleifsdóttir, Vala

    2016-04-01

    The 2014-2015 collapse of the Bárðarbunga caldera was accompanied by a notable seismic sequence of more than 80 events with Mw >= 4.5. We analyse these earthquakes using broadband recordings from the Icelandic regional seismic network using standard and probabilistic centroid moment tensor inversion. Our results reveal that the centroids of the events cluster beneath the northern and southern caldera rims and are characterized by the superposition of a near-vertical negative compensated linear vector dipole (CLVD) and shear faulting of different orientations. It is well known that moment tensor decompositions are non-unique. We demonstrate that in this particular case, applying the standard moment tensor decomposition scheme would lead to wrong conclusions, incompatible with independent observations like the fault orientations at the caldera rims. We propose an alternative decomposition scheme which is well compatible with the observations. Furthermore, we propose a simple mechanical model for asymmetric, drainage-driven caldera collapses, capable of explaining the seismological observations at regional distances: an initial failure along a steep fault is followed by a deformation response of a deeper magmatic source. The shear faulting contribution occurs either as thrust faulting along an outward dipping fault (northern rim) or as normal faulting along an inward dipping fault (southern rim). As a side note, we discuss the parameter trade-offs in our full and deviatoric centroid moment tensor inversion problems and show how to rigorously quantify uncertainties on the results.

  10. Seismological characteristics of the 2011 unrest in Santorini caldera: Implications for observed deformation and volcano-tectonics

    Science.gov (United States)

    Konstantinou, Konstantinos; Evangelidis, Christos; Melis, Nikolaos; Liang, Wen-Tzong

    2013-04-01

    Santorini caldera has experienced several explosive eruptions in the past, the most well-known of these being the Late Bronze Age (ca. 1628 BC) eruption that may have been responsible for the demise of the Minoan civilization. Since the early 1950's the volcano has been dormant without exhibiting any significant activity except from discharge of low-temperature hydrothermal fluids. In January 2011 both deformation and seismic activity increased considerably signaling a period of unrest which however, did not result in an eruption. One permanent and seven temporary seismic stations equipped with three-component sensors were deployed by the National Observatory of Athens. These were combined with seismic stations from the University of Thessaloniki, seven with only a vertical component and four with three-component sensors and all operated under the Hellenic Unified Seismic Network, thus densely monitoring the Santorini Volcano. These seismic stations have recorded the seismic activity from its start up to now. About 290 micro-earthquakes recorded by at least 5 stations were analyzed for the purpose of obtaining accurate epicentral and hypocentral locations using both catalog and differential travel times from waveform cross-correlation. All of these events exhibit clear P- and S-phases indicating that they resulted from shear failure of rock rather than fluid-flow within volcanic conduits. Results show two well-defined clusters in Palea and Nea Kameni islands within the caldera with hypocentral depths ranging between 5-10 km. Interestingly, one more cluster of events with depths between 15-19 km appears near the area of Cape Coloumbo and developed almost simultaneously with the clusters within the caldera. The Mogi source depth inferred from geodetic observations previously is shallower (~4 km) and does not coincide spatially with the clusters within the caldera. This points to the possibility that seismicity and deformation may be excited by deeper pressure changes

  11. Juan de Fuca slab geometry and its relation to Wadati-Benioff zone seismicity

    Science.gov (United States)

    McCrory, Patricia A.; Blair, J. Luke; Waldhause, Felix; Oppenheimer, David H.

    2012-01-01

    A new model of the subducted Juan de Fuca plate beneath western North America allows first-order correlations between the occurrence of Wadati-Benioff zone earthquakes and slab geometry, temperature, and hydration state. The geo-referenced 3D model, constructed from weighted control points, integrates depth information from earthquake locations and regional seismic velocity studies. We use the model to separate earthquakes that occur in the Cascadia forearc from those that occur within the underlying Juan de Fuca plate and thereby reveal previously obscured details regarding the spatial distribution of earthquakes. Seismicity within the slab is most prevalent where the slab is warped beneath northwestern California and western Washington suggesting that slab flexure, in addition to expected metamorphic dehydration processes, promotes earthquake occurrence within the subducted oceanic plate. Earthquake patterns beneath western Vancouver Island are consistent with slab dehydration processes. Conversely, the lack of slab earthquakes beneath western Oregon is consistent with an anhydrous slab. Double-differenced relocated seismicity resolves a double seismic zone within the slab beneath northwestern California that strongly constrains the location of the plate interface and delineates a cluster of seismicity 10 km above the surface that includes the 1992 M7.1 Mendocino earthquake. We infer that this earthquake ruptured a surface within the Cascadia accretionary margin above the Juan de Fuca plate. We further speculate that this earthquake is associated with a detached fragment of former Farallon plate. Other subsurface tectonic elements within the forearc may have the potential to generate similar damaging earthquakes.

  12. Igneous evolution of a complex laccolith-caldera, the Solitario, Trans-Pecos Texas: Implications for calderas and subjacent plutons

    Science.gov (United States)

    Henry, C.D.; Kunk, M.J.; Muehlberger, W.R.; McIntosh, W.C.

    1997-01-01

    The Solitario is a large, combination laccolith and caldera (herein termed "laccocaldera"), with a 16-km-diameter dome over which developed a 6 x 2 km caldera. This laccocaldera underwent a complex sequence of predoming sill, laccolith, and dike intrusion and concurrent volcanism; doming with emplacement of a main laccolith; ash-flow eruption and caldera collapse; intracaldera sedimentation and volcanism; and late intrusion. Detailed geologic mapping and 40Ar/39Ar dating reveal that the Solitario evolved over an interval of approximately 1 m.y. in three distinct pulses at 36.0, 35.4, and 35.0 Ma. The size, duration, and episodicity of Solitario magmatism are more typical of large ash-flow calderas than of most previously described laccoliths. Small volumes of magma intruded as abundant rhyolitic to trachytic sills and small laccoliths and extruded as lavas and tuffs during the first pulse at 36.0 Ma. Emplacement of the main laccolith, doming, ash-flow eruption, and caldera collapse occurred at 35.4 Ma during the most voluminous pulse. A complex sequence of debris-flow and debris-avalanche deposits, megabreccia, trachyte lava, and minor ash-flow tuff subsequently filled the caldera. The final magmatic pulse at 35.0 Ma consisted of several small laccoliths or stocks and numerous dikes in caldera fill and along the ring fracture. Solitario rocks appear to be part of a broadly cogenetic, metaluminous suite. Peralkaline rhyolite lava domes were emplaced north and west of the Solitario at approximately 35.4 Ma, contemporaneous with laccolith emplacement and the main pulse in the Solitario. The spatial and temporal relation along with sparse geochemical data suggest that the peralkaline rhyolites are crustal melts related to the magmatic-thermal flux represented by the main pulse of Solitario magmatism. Current models of laccolith emplacement and evolution suggest a continuum from initial sill emplacement through growth of the main laccolith. Although the Solitario

  13. Communication between earthquake clusters separated by over 30 km supports simple volcano plumbing

    Science.gov (United States)

    Jonsdottir, K.; Jonasson, K.; Gudmundsson, M. T.; Hensch, M.; Hooper, A. J.; Holohan, E. P.; Sigmundsson, F.; Halldorsson, S. A.; Hognadottir, T.; Magnússon, E.; Pálsson, F.; Walter, T. R.; Ofeigsson, B.; Parks, M.; Roberts, M. J.; Hjorleifsdottir, V.; Cesca, S.; Guðmundsson, G.; Hreinsdottir, S.; Jarosch, A. H.; Dumont, S.; Fridriksdóttir, H. M.; Barsotti, S.; Einarsson, P.

    2015-12-01

    The subglacial Bárðarbunga volcano is composed of a large oval caldera (7x11 km) and fissures extending tens of kilometers away from the caldera along the rift zone, which marks the divergent plate boundary across Iceland. On August 16th, 2014 an intense seismic swarm started below the Bárðarbunga caldera and in the two weeks that followed a dyke migrated some 47 km laterally in the uppermost 6-10 km of the crust along the rift. The dyke propagation terminated in lava fields just north of Vatnajökull glacier, where a major (1.5 km3) six months long eruption took place. Intense earthquake activity in the caldera started in the period August 21-24 with over 70 M5 earthquakes accompanying slow caldera collapse, as verified by various geodetic measurements. The subsidence is likely due to magma withdrawal from a reservoir at depth beneath the caldera. During a five months period, October-February, the seismic activity was separated by over 30 km in two clusters; one along the caldera rims (due to piecewise caldera subsidence) and the other at the far end of the dyke (as a result of small shear movements). Here we present statistical analysis comparing the temporal behaviour of seismicity recorded in the two clusters. By comparing the earthquake rate in the dyke in temporal bins before and after caldera subsidence earthquakes to the rate away from these bins (background rate), we show that the number of dyke earthquakes was significantly higher (p earthquake (>M4.6) in the caldera. Increased dyke seismicity was also observed 0-3 hours following a large caldera earthquake. Elevated seismicity in the dyke before a large caldera earthquake may occur when a constriction in the dyke was reduced, followed by pressure drop in the chamber. Assuming that the large caldera earthquakes occurred when chamber pressure was lowest, the subsiding caldera piston may have caused temporary higher pressure in the dyke and thereby increased the likelihood of an earthquake. Our results

  14. GPS time series at Campi Flegrei caldera (2000-2013

    Directory of Open Access Journals (Sweden)

    Prospero De Martino

    2014-05-01

    Full Text Available The Campi Flegrei caldera is an active volcanic system associated to a high volcanic risk, and represents a well known and peculiar example of ground deformations (bradyseism, characterized by intense uplift periods, followed by subsidence phases with some episodic superimposed mini-uplifts. Ground deformation is an important volcanic precursor, and, its continuous monitoring, is one of the main tool for short time forecast of eruptive activity. This paper provides an overview of the continuous GPS monitoring of the Campi Flegrei caldera from January 2000 to July 2013, including network operations, data recording and processing, and data products. In this period the GPS time series allowed continuous and accurate tracking of ground deformation of the area. Seven main uplift episodes were detected, and during each uplift period, the recurrent horizontal displacement pattern, radial from the “caldera center”, suggests no significant change in deformation source geometry and location occurs. The complete archive of GPS time series at Campi Flegrei area is reported in the Supplementary materials. These data can be usefull for the scientific community in improving the research on Campi Flegrei caldera dynamic and hazard assessment.

  15. Vesuvius, the Tengger Mountains and the problem of calderas

    NARCIS (Netherlands)

    Escher, B.G.

    1926-01-01

    Until recently there was no good general map of the Tengger Mountains, so that in 1914 F. von Wolff (bibl. 1) in his work „Der Vulkanismus”, vol. I, p. 510—511, gives a reproduction of Pr. Junghuhn's map of 1844. For a volcanic district that has frequently been used as an example of a caldera and ha

  16. Potential Hazards of Eruptions around the Tianchi Caldera Lake, China

    Institute of Scientific and Technical Information of China (English)

    WEI Haiquan; HONG Hanjing; R.S.J. SPARKS; J.S. WALDER; HAN Bin

    2004-01-01

    Since the eruption of the Tianchi volcano about 1000 years ago, there have been at least 3 to 5 eruptions of small to moderate size. In addition, hazardous avalanches, rock falls and debris flows have occurred during periods between eruptions. A future eruption of the Tianchi volcano is likely to involve explosive interaction between magma and the caldera lake. The volume of erupted magma is almost in a range of 0.1-0.5 km3. Tephra fallout may damage agriculture in a large area near the volcano. If only 1% of the lake water were ejected during an eruption and then precipitated over an area of 200 km2, the average rainfall would be 100 mm. Moreover, lahars are likely to occur as both tephra and water ejected from the caldera lake fall onto flanks of the volcano. Rocks avalanching into the caldera lake also would bring about grave hazards because seiches would be triggered and lake water with the volume equal to that of the landslide would spill out of the existing breach in the caldera and cause flooding downstream.

  17. Structure of La Primavera caldera, Jalisco, Mexico, deduced from gravity anomalies and drilling results

    Science.gov (United States)

    Yokoyama, I.; Mena, M.

    1991-07-01

    Previous studies of La Primavera caldera have mostly been based on surface geology and topography. Since 1980, many wells, exploring for geothermal energy, have reached depths of about 2 to 3 km at the center of the caldera. The results of the drillings, together with those of the gravity surveys, provide information about the subsurface structure of the caldera, and shed light on its formation. The drilling results and gravity anomalies at La Primavera caldera and San Marcos, located at about 40 km distance from the caldera, suggest that regional gravity anomalies can be interpreted in terms of depths of the granitic basements: the basement beneath La Primavera caldera is about 3 km deep and consists of roughly the same horizon as that beneath San Marcos. The drilling results within the caldera reveal that the depth of the caldera fills ranges from 0.3 to 1 km at the drilling sites. The andesite basement, about 1 km deep, remains approximately horizontal, and the granitic basement has a depth of about 3 km. The surface topographies, such as the postcaldera domes, scarcely disturb the subsurface strata. The local gravity anomalies show two lows within the caldera reflecting the configuration of caldera bottom, two funnel-shaped depressions, one of which corresponds to a vent of the Tala tuff deduced from geological observations. The mass deficiency within the caldera estimated from the gravity anomaly, satisfies the general relationship that the mass deficiency is proportional to the caldera diameter cubed. This means that caldera structure is three-dimensional: the larger the diameter, the deeper the funnel-shape. At present this argument may be limited to funnel-shaped calderas.

  18. Una Visita al Viejo San Juan (A Visit to Old San Juan).

    Science.gov (United States)

    Cabello, Victor; And Others

    Written in Spanish, this black and white illustrated booklet provides a tour of Old San Juan, Puerto Rico's oldest and most historic city. Brief historical information is provided on the Perro de San Jeronimo, a statue of a barking dog found in front of the Castillo; Plaza de Colon, a small plaza dedicated to Christopher Columbus; the Catedral de…

  19. Una Visita al Viejo San Juan (A Visit to Old San Juan).

    Science.gov (United States)

    Cabello, Victor; And Others

    Written in Spanish, this black and white illustrated booklet provides a tour of Old San Juan, Puerto Rico's oldest and most historic city. Brief historical information is provided on the Perro de San Jeronimo, a statue of a barking dog found in front of the Castillo; Plaza de Colon, a small plaza dedicated to Christopher Columbus; the Catedral de…

  20. Chinanteco de San Juan Lealao, Oaxaca (Chinantec of San Juan Lealao, Oaxaca).

    Science.gov (United States)

    Mexico Coll. (Mexico City)

    This document is one of 17 volumes on indigenous Mexican languages and is the result of a project undertaken by the Archivo de Lenguas Indigenas de Mexico. This volume contains information on Chinantec, an indigenous language of Mexico spoken in San Juan Lealao, in the state of Oaxaca. The objective of collecting such a representative sampling of…

  1. Trique de San Juan Copala, Oaxaca (Trique of San Juan Copala, Oaxaca).

    Science.gov (United States)

    Mexico Coll. (Mexico City)

    This document is one of 17 volumes on indigenous Mexican languages and is the result of a project undertaken by the Archivo de Lenguas Indigenas de Mexico. This volume contains information on Trique, an indigenous language of Mexico spoken in San Juan Copala, in the state of Oaxaca. The objective of collecting such a representative sampling of the…

  2. Juan's Dilemma: A New Twist on the Old Lemon Battery

    Science.gov (United States)

    Hunt, Vanessa; Sorey, Timothy; Balandova, Evguenia; Palmquist, Bruce

    2010-01-01

    When life hands you lemons, make a battery! In this article, the authors describe an activity they refer to as "Juan's Dilemma," an extension of the familiar lemon-battery activity (Goodisman 2001). Juan's Dilemma integrates oxidation and reduction chemistry with circuit theory in a fun, real-world exercise. The authors designed this activity for…

  3. 33 CFR 80.1385 - Strait of Juan de Fuca.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Strait of Juan de Fuca. 80.1385 Section 80.1385 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Thirteenth District § 80.1385 Strait of Juan de Fuca. The 72 COLREGS shall apply on all waters of...

  4. 77 FR 47358 - San Juan National Forest Resource Advisory Committee

    Science.gov (United States)

    2012-08-08

    ... Forest Service San Juan National Forest Resource Advisory Committee AGENCY: Forest Service, USDA. ACTION: Notice of meeting. SUMMARY: The San Juan National Forest Resource Advisory Council (RAC) will meet in... recommendations to the Forest Service concerning projects and funding consistent with Title II of the Act. The...

  5. Juan's Dilemma: A New Twist on the Old Lemon Battery

    Science.gov (United States)

    Hunt, Vanessa; Sorey, Timothy; Balandova, Evguenia; Palmquist, Bruce

    2010-01-01

    When life hands you lemons, make a battery! In this article, the authors describe an activity they refer to as "Juan's Dilemma," an extension of the familiar lemon-battery activity (Goodisman 2001). Juan's Dilemma integrates oxidation and reduction chemistry with circuit theory in a fun, real-world exercise. The authors designed this activity for…

  6. An Inquiry into Juan Ramon's Interest in Walter Pater

    Directory of Open Access Journals (Sweden)

    John C. Wilcox

    1983-01-01

    Full Text Available The evidence for Juan Ramon's interest in Pater, which began around 1920 and was still active twenty years later, is discussed in this paper. Pater's view of death and dying and his attitude toward the decadent persona are described in so far as they indicate the spiritual affinity that exists between him and Juan Ramón. Pater's aesthetic idealism, and the presence of similar ideals in Juan Ramon's own work are then examined. The second part of the paper concentrates on the great interest Juan Ramón took in Pater's evocation of the Mona Lisa. The potential impact of the aesthetic idealism inherent in this passage, its Platonism in particular, receives special analysis in the light of Espacio , and in consideration of Juan Ramon's 1943 remark: "I am, have been, and always will be a Platonist."

  7. JUAN SOLDADO, PROTECTOR SOBRENATURAL DE LOS MIGRANTES

    OpenAIRE

    González Pérez, Cándido; Reynoso Rábago, Alfonso; Universidad de Guadalajara

    2013-01-01

    Los trabajadores mexicanos han emigrado a Estados Unidos de América desde mediados del siglo XIX y como producto de la profunda tradición religiosa heredada de España, han buscado apoyo sobrenatural para lograr sus objetivos: cruzar la frontera de manera ilegal y obtener un puesto de trabajo que haga posible enviar recursos económicos a sus familiares. En este tenor se creó un “protector sobrenatural inédito”:Juan Soldado quien en vida hab...

  8. Programa educativo del Infante D. Juan Manuel

    OpenAIRE

    Sánchez, Marciano

    1986-01-01

    RESUMEN: Si hemos de creer al Prólogo-Dedicatoria, el infante D. JUAN MANUEL parece que se sentía muy preocupado por los problemas de su tiempo, hasta el punto de que le hacían «perder el dormir». Como terapia contra este insomnio utilizaba el leer y escribir. En consecuencia, si el origen de este Libro del cauallero et del escudero, calificado por Díaz Plaja como «curiosa enciclopedia didáctica de su tiempo», hay que buscarlo en las noches de insomnio que padecía en Sevilla, es lícito conclu...

  9. Temperature data from wells in Long Valley Caldera, California

    Science.gov (United States)

    Farrar, Christopher; DeAngelo, Jacob; Williams, Colin; Grubb, Frederick; Hurwitz, Shaul

    2010-01-01

    The 30-by-20-km Long Valley Caldera (LVC) in eastern California (fig.1) formed at 0.76 Ma in a cataclysmic eruption that resulted in the deposition of 600 km? of Bishop Tuff outside the caldera rim (Bailey, 1989). By approximately 0.6 Ma, uplift of the central part of the caldera floor and eruption of rhyolitic lava formed the resurgent dome. The most recent eruptive activity in the area occurred approximately 600 yr ago along the Mono-Inyo craters volcanic chain (Bailey, 2004; Hildreth, 2004). LVC hosts an active hydrothermal system that includes hot springs, fumaroles, mineral deposits, and an active geothermal well field and power plant at Casa Diablo along the southwestern boundary of the resurgent dome (Sorey and Lewis, 1976; Sorey and others, 1978; Sorey and others, 1991). Electric power generation began in 1985 with about 10 Mwe net capacity and was expanded to about 40 Mwe (net) in 1991 (Campbell, 2000; Suemnicht and others, 2007). Plans for further expansion are focused mainly on targets in the caldera?s western moat (Sass and Priest, 2002) where the most recent volcanic activity has occurred (Hildreth, 2004). LVC has been the site of extensive research on geothermal resources and volcanic hazards (Bailey and others, 1976; Muffler and Williams, 1976; Miller and others, 1982; Hill and others 2002). The first geothermal exploratory drilling was done in the shallow (geothermal exploration and by the U.S. Geological Survey (USGS) and Sandia National Laboratory for volcanic and geothermal research and exploration. Temperature logs were obtained in some of these wells during or immediately following drilling, before thermal equilibration was complete. Most of the temperature logs, however, were obtained weeks, months, or years after well completion and are representative of dynamic thermal equilibrium. The maximum reservoir temperature for LVC is estimated to be about 220?C on the basis of chemical geothermometers (Fournier and Truesdell, 1973) using analytical

  10. 33 CFR 165.776 - Security Zone; Coast Guard Base San Juan, San Juan Harbor, Puerto Rico

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Security Zone; Coast Guard Base San Juan, San Juan Harbor, Puerto Rico 165.776 Section 165.776 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY REGULATED NAVIGATION AREAS AND LIMITED ACCESS AREAS Specific...

  11. The effect of pressurized magma chamber growth on melt migration and pre-caldera vent locations through time at Mount Mazama, Crater Lake, Oregon

    Science.gov (United States)

    Karlstrom, Leif; Wright, Heather M.; Bacon, Charles R.

    2015-01-01

    The pattern of eruptions at long-lived volcanic centers provides a window into the co-evolution of crustal magma transport, tectonic stresses, and unsteady magma generation at depth. Mount Mazama in the Oregon Cascades has seen variable activity over the last 400 ky, including the 50 km3 climactic eruption at ca. 7.7 ka that produced Crater Lake caldera. The physical mechanisms responsible for the assembly of silicic magma reservoirs that are the precursors to caldera-forming eruptions are poorly understood. Here we argue that the spatial and temporal distribution of geographically clustered volcanic vents near Mazama reflects the development of a centralized magma chamber that fed the climactic eruption. Time-averaged eruption rates at Mount Mazama imply an order of magnitude increase in deep magma influx prior to the caldera-forming event, suggesting that unsteady mantle melting triggered a chamber growth episode that culminated in caldera formation. We model magma chamber–dike interactions over ∼50 ky preceding the climactic eruption to fit the observed distribution of surface eruptive vents in space and time, as well as petrologically estimated deep influx rates. Best fitting models predict an expanding zone of dike capture caused by a growing, oblate spheroidal magma chamber with 10–30 MPa of overpressure. This growing zone of chamber influence causes closest approaching regional mafic vent locations as well as more compositionally evolved Mazama eruptions to migrate away from the climactic eruptive center, returning as observed to the center after the chamber drains during the caldera-forming eruption.

  12. Juan Antonio Rubio Rodriguez (1944 – 2010)

    CERN Multimedia

    His colleagues and friends

    2010-01-01

    It was with deep sorrow and great sadness that we learnt that Juan Antonio Rubio Rodriguez had passed away on 16th January 2010. Juan Antonio was born in Madrid on 4th June 1944, and received his Ph. D. in Physics in 1971 from“Universidad Complutense de Madrid”. He was a CERN Fellow (1968 – 1971) and subsequently worked at JEN (currently CIEMAT) as a researcher (1971 – 1976). He was leader of the HEP group (1977 – 1981), leader of the Nuclear and Particle Physics Division (1981 – 1983), Director for Basic Research (1983 – 1987) and Scientific Director (1984 – 1987). He was instrumental in the Spanish accession to CERN approved by the Spanish Government at the end of 1982 and ratified by the Spanish Parliament in June 1983. He served at CERN (1987 – 2004) as Group Leader (1987 – 1990), Scientific Advisor to the Director-General (1990 – 2000) and as Division Leader of the Education and Technology T...

  13. Programa educativo del Infante D. Juan Manuel

    Directory of Open Access Journals (Sweden)

    Marciano SÁNCHEZ

    2010-03-01

    Full Text Available RESUMEN: Si hemos de creer al Prólogo-Dedicatoria, el infante D. JUAN MANUEL parece que se sentía muy preocupado por los problemas de su tiempo, hasta el punto de que le hacían «perder el dormir». Como terapia contra este insomnio utilizaba el leer y escribir. En consecuencia, si el origen de este Libro del cauallero et del escudero, calificado por Díaz Plaja como «curiosa enciclopedia didáctica de su tiempo», hay que buscarlo en las noches de insomnio que padecía en Sevilla, es lícito concluir que los temas educativos constituían una preocupación para el Infante. Si bien no es tanto un tratado sistemático de educación cuanto una «fabliella» —género literario de la época que funde lo novelesco y lo didáctico— da pautas suficientes para, de una parte, deducir cuál sería el método de educación imperante entre los nobles junto con sus principales contenidos educativos, y, de otra, inferir el sistema ideal para don Juan Manuel.

  14. Hollow volcanic tumulus caves of Kilauea Caldera, Hawaii County, Hawaii

    Directory of Open Access Journals (Sweden)

    William R. Halliday

    1998-01-01

    Full Text Available In addition to lava tube caves with commonly noted features, sizable subcrustal spaces of several types exist on the floor of Kilauea Caldera. Most of these are formed by drainage of partially stabilized volcanic structures enlarged or formed by injection of very fluid lava beneath a plastic crust. Most conspicuous are hollow tumuli, possibly first described by Walker in 1991. Walker mapped and described the outer chamber of Tumulus E-I Cave. Further exploration has revealed that it has a hyperthermic inner room beneath an adjoining tumulus with no connection evident on the surface. Two lengthy, sinuous hollow tumuli also are present in this part of the caldera. These findings support Walkers conclusions that hollow tumuli provide valuable insights into tumulus-forming mechanisms, and provide information about the processes of emplacement of pahoehoe sheet flows.

  15. Volcanic hazard assessment at the Campi Flegrei caldera

    OpenAIRE

    Mastrolorenzo, G.; Pappalardo, L; C. Troise; S. Rossano; Panizza, A; G. De Natale

    2006-01-01

    Previous and new results from probabilistic approaches based on available volcanological data from real eruptions of Campi Flegrei, are assembled in a comprehensive assessment of volcanic hazards at the Campi Flegrei caldera, in order to compare the volcanic hazards related to the different types of events. Hazard maps based on a very wide set of numerical simulations, produced using field and laboratory data as input parameters relative to the whole range of fallout and pyrocl...

  16. Long Valley Caldera Lake and reincision of Owens River Gorge

    Science.gov (United States)

    Hildreth, Wes; Fierstein, Judy

    2016-12-16

    Owens River Gorge, today rimmed exclusively in 767-ka Bishop Tuff, was first cut during the Neogene through a ridge of Triassic granodiorite to a depth as great as its present-day floor and was then filled to its rim by a small basaltic shield at 3.3 Ma. The gorge-filling basalt, 200 m thick, blocked a 5-km-long reach of the upper gorge, diverting the Owens River southward around the shield into Rock Creek where another 200-m-deep gorge was cut through the same basement ridge. Much later, during Marine Isotope Stage (MIS) 22 (~900–866 ka), a piedmont glacier buried the diversion and deposited a thick sheet of Sherwin Till atop the basalt on both sides of the original gorge, showing that the basalt-filled reach had not, by then, been reexcavated. At 767 ka, eruption of the Bishop Tuff blanketed the landscape with welded ignimbrite, deeply covering the till, basalt, and granodiorite and completely filling all additional reaches of both Rock Creek canyon and Owens River Gorge. The ignimbrite rests directly on the basalt and till along the walls of Owens Gorge, but nowhere was it inset against either, showing that the basalt-blocked reach had still not been reexcavated. Subsidence of Long Valley Caldera at 767 ka produced a steep-walled depression at least 700 m deeper than the precaldera floor of Owens Gorge, which was beheaded at the caldera’s southeast rim. Caldera collapse reoriented proximal drainages that had formerly joined east-flowing Owens River, abruptly reversing flow westward into the caldera. It took 600,000 years of sedimentation in the 26-km-long, usually shallow, caldera lake to fill the deep basin and raise lake level to its threshold for overflow. Not until then did reestablishment of Owens River Gorge begin, by incision of the gorge-filling ignimbrite.

  17. Uplift, thermal unrest and magma intrusion at Yellowstone caldera.

    Science.gov (United States)

    Wicks, Charles W; Thatcher, Wayne; Dzurisin, Daniel; Svarc, Jerry

    2006-03-02

    The Yellowstone caldera, in the western United States, formed approximately 640,000 years ago when an explosive eruption ejected approximately 1,000 km3 of material. It is the youngest of a series of large calderas that formed during sequential cataclysmic eruptions that began approximately 16 million years ago in eastern Oregon and northern Nevada. The Yellowstone caldera was largely buried by rhyolite lava flows during eruptions that occurred from approximately 150,000 to approximately 70,000 years ago. Since the last eruption, Yellowstone has remained restless, with high seismicity, continuing uplift/subsidence episodes with movements of approximately 70 cm historically to several metres since the Pleistocene epoch, and intense hydrothermal activity. Here we present observations of a new mode of surface deformation in Yellowstone, based on radar interferometry observations from the European Space Agency ERS-2 satellite. We infer that the observed pattern of uplift and subsidence results from variations in the movement of molten basalt into and out of the Yellowstone volcanic system.

  18. Nova Scotia Power response to Hurricane Juan

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-10-01

    Hurricane Juan hit the Halifax Regional Municipality on September 28, 2003, creating the largest outage in Nova Scotia Power's history. This detailed report documents the extensive damage that Hurricane Juan caused to the power transmission and distribution system in Nova Scotia. It also reviews the massive power restoration effort, with reference to numerous interviews, computer records and data logs which offer a wide range of observations, statistics and insights into the preparation and performance of Nova Scotia Power Inc. (NSPI) and the efforts of other key organizations following the storm. NSPI organized a recovery effort that matched the intensity of the hurricane. A fire in the Scotia Square Office Tower caused the evacuation of the company's call centre. The Tufts Cove station in Dartmouth, which generates 400 megawatts of power, was forced to shut down. Excess electricity was moved into New Brunswick and other jurisdictions to maintain system stability. The main priority was to restore customers back to service. Within 5 days of the hurricane, 95 per cent of those who lost power had service restored. Hurricane Juan caused the most damage to the transmission and distribution system in NSPI's history. Three out of five high capacity transmission lines were put out of service. Three 120-foot high transmission towers fell, and 17 main transmission lines were damaged and put out of service. Forty-five major substations were affected and 145 distribution feeders were damaged or tripped off, including 106 in the Halifax Regional Municipality. Large portions of 4,500 kilometres of local distribution lines in the Halifax Regional Municipality were damaged, including thousands of kilometers across the Northeast. The power crew, consisting of 2,000 individuals from the region and neighbouring utilities in New Brunswick and Maine, worked for 15 consecutive days to replace 275 transformers, 760 power poles, and 125,000 metres of conductor wire. NSPI

  19. Un San Juan Bautista firmado por Juan Simón Gutiérrez

    Directory of Open Access Journals (Sweden)

    Requena Bravo de Laguna, José Luis

    2003-12-01

    Full Text Available El conocimiento de la pintura sevillana de la segunda mitad del siglo XVII supone uno de los grandes retos de nuestra historiografía artística. Efectivamente, el amplio abanico de discípulos e imitadores del arte de Murillo necesita una profunda revisión metodológica que sepa clarificar la nada fácil tarea de aislar las distintas personalidades que constituyen este importante grupo de artistas. En este sentido la personalidad de Juan Simón Gutiérrez (h. 1634-1724 continua siendo bastante confusa si bien con algunos interrogantes se le van atribuyendo ciertas obras que puedan responder al todavía escaso conocimiento de su estilo frente al amplio grupo de pintores pertenecientes a la escuela de Murillo. Este inédito San Juan Bautista predicando en el desierto (fig. 1, firmado por Juan Simón Gutiérrez (figs. 2-3 procedente de una colección cordobesa…

  20. A kuroko-type polymetallic sulfide deposit in a submarine silicic caldera

    Science.gov (United States)

    Iizasa; Fiske; Ishizuka; Yuasa; Hashimoto; Ishibashi; Naka; Horii; Fujiwara; Imai; Koyama

    1999-02-12

    Manned submersible studies have delineated a large and actively growing Kuroko-type volcanogenic massive sulfide deposit 400 kilometers south of Tokyo in Myojin Knoll submarine caldera. The sulfide body is located on the caldera floor at a depth of 1210 to 1360 meters, has an area of 400 by 400 by 30 meters, and is notably rich in gold and silver. The discovery of a large Kuroko-type polymetallic sulfide deposit in this arc-front caldera raises the possibility that the numerous unexplored submarine silicic calderas elsewhere might have similar deposits.

  1. Virgilio según Juan Pablo II

    Directory of Open Access Journals (Sweden)

    Antonio Arbea

    2003-09-01

    Full Text Available El año 1981, con motivo de la conmemoración de los dos mil años de lamuerte de Virgilio, el Papa Juan Pablo II pronunció un ilustrado discurso, en latín, en torno a la figura y la obra del poeta latino. En este artículo se traducen y comentan algunos pasajes destacados de esta singular pieza oratoria. (In 1981, Pope John Paul II delivered an enlightened speech in Latin about poet Virgil’s work and figure, to commemorate the 2000th anniversary of his death. This article translates and comments on some selected passages of this uncommon piece of oratory.

  2. Juan Ruiz político

    OpenAIRE

    Georges Martin

    2007-01-01

    Más bien que en la vida amorosa del Arcipreste de Hita, de la que no sabemos nada, quizá tengamos que ver en el importantísimo conflicto con incidencias dinásticas virtualmente devastadoras entre María de Portugal, la mujer legítima de Alfonso XI, y Leonor de Guzmán, su concubina oficial, o, si se quiere, en el “loco amor” del rey y en el partido (el de María) que –sugiero- escogió Juan Ruiz, la causa del encarcelamiento del autor del Libro de buen amor. También se comprendería que dicho cont...

  3. San Juan, Puerto Rico Tsunami Forecast Grids for MOST Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The San Juan, Puerto Rico Forecast Model Grids provides bathymetric data strictly for tsunami inundation modeling with the Method of Splitting Tsunami (MOST) model....

  4. Strait of Juan de Fuca 1 arc-second DEM

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The 1-second Strait of Juan de Fuca Washington Elevation Grid provides bathymetric data in ASCII raster format of 1-second resolution in geographic coordinates. This...

  5. Strait of Juan de Fuca 6 arc-second DEM

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The 6-second Strait of Juan de Fuca Washington Elevation Grid provides bathymetric data in ASCII raster format of 6-second resolution in geographic coordinates. This...

  6. Strait of Juan de Fuca 36 arc-second DEM

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The 36-second Strait of Juan de Fuca Washington Elevation Grid provides bathymetric data in ASCII raster format of 36-second resolution in geographic coordinates....

  7. Un nuevo retrato de Juan Pantoja de la Cruz

    Directory of Open Access Journals (Sweden)

    de la Torre Fazio, Julia

    2010-06-01

    Full Text Available The author attributes an early 17th century Spanish portrait of an unknown young lady in a French private collection to Juan Pantoja de la Cruz.

    Atribución de un retrato español de joven dama desconocida de principios del siglo XVII, conservado en una colección particular francesa, a Juan Pantoja de la Cruz.

  8. Multiwell Ojo Alamo development advancing in San Juan basin

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-04-27

    Commercial production from a new formation is rare in a basin as mature as the San Juan. Such a development can be economically attractive because with so many existing wellbores, behind pipe formations can be placed on production quickly and inexpensively. That is happening on the east side of the San Juan, where what appears to be the first significant commercial gas production from Tertiary Ojo Alamo sandstone started last year. The deposit is briefly described.

  9. Juan-Ron fever: A rare case report.

    Science.gov (United States)

    Acharya, Sourya; Shukla, Samarth

    2015-01-01

    Juan-Ron fever named after Juan Rosai and Ronald Dorfman is the fever associated with Rosai-Dorfman disease also known as sinus histiocytosis with massive lymphadenopathy (SHML). It is a rare disorder of unknown etiology that is characterized by abundant macrophages in the lymph nodes throughout the body. Usually patient presents with painless lymphadenopathy. We present a case of a 45-year-old male who presented to us with bilateral cervical lymphadenopathy and fever, later on diagnosed to have SHML.

  10. Early postcaldera rhyolite and structural resurgence at Long Valley Caldera, California

    Science.gov (United States)

    Hildreth, Wes; Fierstein, Judy; Calvert, Andrew

    2017-04-01

    After the 767-ka caldera-forming eruption of 650 km3 of rhyolite magma as the Bishop Tuff, 90-100 km3 of similar rhyolite erupted in the west-central part of Long Valley caldera in as many as 40 batches spread over the 110,000-year interval from 750 ka to 640 ka. Centrally, this Early Rhyolite (ER) is as thick as 622 m, but it spread radially to cover much of the caldera floor, where half its area is now concealed by post-ER sediments and lavas. At least 75% of the ER is aphyric rhyolite tuff. Drillholes encountered 22 (altered) ER lava flows intercalated in the pyroclastic pile, and another 11 units of (largely fresh) ER lava are exposed on the caldera's resurgent dome and at Lookout Mountain. Exposed units have been distinguished, mapped, studied petrographically and chemically, and radioisotopically dated; each is described in detail. Their phenocryst contents range from 0 to 2.5 wt%. All the phyric units have plagioclase, orthopyroxene, and ilmenite; most have biotite and rare tiny magnetite, and a few contain rare zircon. The compositional range of fresh obsidians is narrow-74.3-75.0% SiO2, 1.21-1.37% FeO*, and 5.12-5.26% K2O, but wider variations in Ti, Ba, Sr, and Zr permit distinction of individual units and eruptive groups. The limited chemical and petrographic variability shown by so many ER batches released episodically for 110,000 years suggests a thermally buffered and well-stirred reservoir. The ER central area, where ER eruptions had taken place, was uplifted 400 m to form a structural dome 10 km in diameter. Most of the inflation is attributable to 10 sills of ER that intrude the Bishop Tuff beneath the uplift, but other processes potentially contributing to resurgence are also considered. As shown by erratics of Mesozoic rocks ice-rafted from the Sierra Nevada and dropped on ER lavas, much of the ER had erupted early enough and at low enough elevation to be inundated by the intracaldera lake and was only later lifted by the resurgence that also

  11. Geologic map of the Caetano caldera, Lander and Eureka counties, Nevada

    Science.gov (United States)

    Colgan, Joseph P.; Henry, Christopher D.; John, David A.

    2011-01-01

    The Eocene (34 Ma) Caetano caldera in north-central Nevada offers an exceptional opportunity to study the physical and petrogenetic evolution of a large (20 km by 10–18 km pre-extensional dimensions) silicic magma chamber, from precursor magmatism to caldera collapse and intrusion of resurgent plutons. Caldera-related rocks shown on this map include two units of crystal-rich intracaldera tuff totaling over 4 km thickness, caldera collapse breccias, tuff dikes that fed the eruption, hydrothermally altered post-eruption rocks, and two generations of resurgent granitic intrusions (John et al., 2008). The map also depicts middle Miocene (about 16–12 Ma) normal faults and synextensional basins that accommodated >100 percent extension and tilted the caldera into a series of ~40° east-dipping blocks, producing exceptional 3-D exposures of the caldera interior (Colgan et al., 2008). This 1:75,000-scale map is a compilation of published maps and extensive new mapping by the authors (fig. 1), and supersedes a preliminary 1:100,000-scale map published by Colgan et al. (2008) and John et al. (2008). New mapping focused on the margins of the Caetano caldera, the distribution and lithology of rocks within the caldera, and on the Miocene normal faults and sedimentary basins that record Neogene extensional faulting. The definition of geologic units and their distribution within the caldera is based entirely on new mapping, except in the northern Toiyabe Range, where mapping by Gilluly and Gates (1965) was modified with new field observations. The distribution of pre-Cenozoic rocks outside the caldera was largely compiled from existing sources with minor modifications, with the exception of the northeastern caldera margin (west of the Cortez Hills Mine), which was remapped in the course of this work and published as a stand-alone 1:6000-scale map (Moore and Henry, 2010).

  12. Decoding micro-structural damage related to caldera collapse at Santorini Volcano

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    Drymoni, Kyriaki; Browning, John; Gudmundsson, Agust; Mitchell, Thomas

    2017-04-01

    Deformation in damage zones, as micro fracture density, can be estimated at a given distance from a fault as a function of fault displacement, based on empirical relationships derived from detailed quantitative field studies of natural faults that cut through low porosity, crystalline rocks in strike-slip tectonic environments. For the first time, we attempt to apply the same method to study the characteristics of a damage zone generated by caldera collapse along a bounding circumferential ring-fault. We have undertaken a field campaign at Santorini Volcano, Greece, and mapped sections of a dyke swarm in the northern caldera wall. The dykes, associated lavas, and eruptive units are partially cut by a series of historic caldera collapses. The dykes represent elastic inclusions in an otherwise heterogeneous and complex edifice which makes up the Santorini Volcano. To study caldera-related damage we sampled dykes at varying distance from the inferred caldera fault. The collected samples were cut into several different orientations to map micro-fracture density and orientation with relation to the strike of the historic caldera faults. In addition, benchtop ultrasonic wave velocity measurements were made on all samples. Preliminary fracture analysis of plagioclase crystals and velocity data suggests relationship between proximity to the fault and micro-fracture density. We also find a mechanical anisotropy control which may relate to the orientation of fractures generated by historic caldera collapses on Santorini. An analysis of the anisotropy and micro-fractures may help to identify the mechanism of caldera faulting at Santorini (e.g. near-surface tension fractures and normal faulting or reverse faulting). In addition to our micro-structural study, we will investigate the presence of hydrothermal/chemical alteration within the inferred caldera damage zone. Our aim is to set up numerical models to investigate stress distribution within the dykes and host rock during

  13. Implications of a Caldera Origin of the Lunar Crater Copernicus

    Science.gov (United States)

    Green, J.

    2007-12-01

    The forthcoming renaissance in lunar exploration will focus on many objectives such as Copernicus. Copernicus appears to be a caldera for at least 8 reasons. If a caldera we see (1) transient activity (2) no overturned impact flap at the crater margins (3) internal sinuous leveed lava flow channels (4) a lava covered floor (5) terraces of different ages (6) multiple central volcanoes, one showing a directed volcanic blast (7) olivine-rich komatiitic lavas on central volcanoes and (8) magmatic inflation/deflation on caldera flanks localizing craterlets and extinct fumaroles in "loop" patterns. Regarding (6), directed volcanic blasts can remove a segment of the volcano wall as evidenced in terrestrial analogs at Mt. St. Helens and Bezymianny. Impact mechanisms to produce this feature in Copernicus are contrived. For (7) Clementine spectral data show a high olivine content of the central mountains on Copernicus which I interpret as forsteritic spinifex mineralization in komatiitic lavas and not as impact rebound of olivine-rich deep seated rocks. (8) MacDonald (1956) documented loop patterns on the flank of Halemaumau in Hawaii defining arcuate fractures localizing fumaroles and craterlets. Inflation/deflation of subjacent magma bodies are interpreted as the cause for these loops. Inflation/deflation mechanisms on caldera flanks are common around terrestrial calderas. "Loop" patterns on the flank of Copernicus localizing "gouge" craterlets have been interpreted as ballistic features resulting from the meteorite impact of this crater. Questioned is the logic of a linear N26E trending array of fragments within Copernicus to serve as a source of ballistic projectiles to form the loops localizing conjugate craterlets. The fused craterlet axes on the lunar loops do not point back to a presumed impact center in Copernicus. The axes are oriented parallel to a regional northwest (N35-60W) fracture zone. Implications for an endogenic origin of Copernicus would involve

  14. Prevalence of the Metabolic Syndrome in San Juan, Puerto Rico

    Science.gov (United States)

    Pérez, Cynthia M.; Guzmán, Manuel; Ortiz, Ana P.; Estrella, Mayra; Valle, Yari; Pérez, Naydi; Haddock, Lillian; Suárez, Erick

    2009-01-01

    Objective The metabolic syndrome is associated with a high risk of diabetes and cardiovascular disease, and Hispanics in the United States have higher rates than do other ethnic groups. We assessed the prevalence of the metabolic syndrome and its individual components in Puerto Rican adults. Methods We conducted a cross-sectional study that used a probability cluster design to select a sample of households of the San Juan metropolitan area from 2005 through 2007. A total of 859 persons aged 21–79 years completed a face-to-face interview, blood pressure and waist circumference measurements, and blood sampling. Our primary outcome measure was metabolic syndrome as defined by the updated NCEP-ATP criteria. Results Prevalence of the metabolic syndrome was 43.3%; 45.3% for men and 42.2% for women (P>.05). Prevalence significantly rose with age, from 12.8% among participants aged 21–29 years to 58.2% for participants aged 70–79 years (P<.001). Corresponding increases in the prevalence of the metabolic syndrome in both men and women were also observed; the prevalence peaked in men aged 50–59 years (62.6%) and in women aged 70–79 years (65.2%). Elevated glucose (49.8%) and abdominal obesity (49.0%) were the most common components of the metabolic syndrome, followed by elevated blood pressure (46.1%), reduced high-density lipoprotein cholesterol (46.0%), and elevated triglycerides (31.3%). Substantial variations were found between men and women in the prevalence of individual components. Conclusions Puerto Ricans have a high prevalence of the metabolic syndrome. This health disparity has implications for diabetes and cardiovascular prevention programs. PMID:19157247

  15. Aeromagnetic Study of Tke Huichapan Caldera; Central Volcanic Belt

    Science.gov (United States)

    Gonzalez, T.; Martin, A.; Alfaro, G.; Oyarzabal, E.

    2013-12-01

    Analysis of the aeromagnetic anomalies over the central sector of the Mexican Volcanic Belt sheds new light on the structure of the Huichapan Caldera. This volcanic center located 100 Km to the north- northwest of Mexico City is approximately 10 km in diameter and related to an ignimbrite sequence. Milan et al, (1993) and. Aguirre-Diaz and Lopez-Martinez (2009) mapped Huichapan area and described the geology and petrology of the erupted products in the region. Aguirre-Diaz and Lopez-Martinez (2009) suggest the idea of two overlapping calderas related to an ignimbrite sequence. The analyzed region is a rectangular area, approximately from 20.25 N to 20.42 N and between 99.42 W and 99.6 W. The total field aeromagnetic data was obtained with a Geometrics G-803 proton magnetometer at a flight altitude of 300 m above ground level. For the analysis of the anomalies, the data was further smoothed to construct a 1 km regularly spaced grid. The anomaly map was compared with the surface geology and larger anomalies were correlated with major volcanic features. Since our main interest was in mapping the subsurface intrusive and volcanic bodies, the total field magnetic anomalies were reduced to the pole by using the double integral Fourier method. The reduced to the pole anomaly map results in a simplified pattern of isolated positive and negative anomalies, which show an improved correlation with all major volcanic structures. For the analysis and interpretation of the anomalies, the reduced to the pole anomalies were continued upward at various reference levels. These operations result in smoothing of the anomaly field by the filtering of high frequency anomalies that may be related to shallow sources. Two profiles were selected that cross the major anomalies on the Huichapan Caldera. The Talwani algorithm for 2-D polygonal bodies has been used for calculating the theoretical anomalies.

  16. Caldera development during the Minoan eruption, Thira, Cyclades, Greece

    Energy Technology Data Exchange (ETDEWEB)

    Heiken, G.; McCoy F. Jr.

    1984-09-30

    The well-known caldera of Thira (Santorini), Greece, was not formed during a single eruption but is composed of two overlapping calderas superimposed upon a complex volcanic field that developed along a NE trending line of vents. Before the Minoan eruption of 1400 B.C., Thira consisted of three lava shields in the northern half of the island and a flooded depression surrounded by tuff deposits in the southern half. Andesitic lavas formed the overlapping shields of the north and were contemporaneous with and, in many places, interbedded with the southern tuff deposits. Although there appears to be little difference between the composition of magmas erupted, differences in eruption style indicate that most of the activity in the northern half of the volcanic field was subaerial, producing lava flows, whereas in the south, eruptions within a flooded depression produced a sequence of mostly phreatomagmatic tuffs. Many of these tuffs are plastered onto the walls of what appears to have been an older caldera, most probably associated with an eruption of rhyodiacitic tephra 100,000 years ago. The Minoan eruption of about 1400 B.C. had four distinct phases, each reflecting a different vent geometry and eruption mechanism. The Minoan activity was preceded by minor eruptions of fine ash. (1) The eruption began with a Plinian phase, from subaerial vent(s) located on the easternmost of the lave shields. (2) Vent(s) grew toward the SW into the flooded depression. Subsequent activity deposited large-scale base surge deposits during vent widening by phreatomagnetic activity. (3) The third eruptive phase was also phreatomagmatic and produced 60% of the volume of the Minoan Tuff. This activity was nearly continuous and formed a large featureless tuff ring with poorly defined bedding.

  17. How caldera collapse shapes the shallow emplacement and transfer of magma in active volcanoes

    Science.gov (United States)

    Corbi, F.; Rivalta, E.; Pinel, V.; Maccaferri, F.; Bagnardi, M.; Acocella, V.

    2015-12-01

    Calderas are topographic depressions formed by the collapse of a partly drained magma reservoir. At volcanic edifices with calderas, eruptive fissures can circumscribe the outer caldera rim, be oriented radially and/or align with the regional tectonic stress field. Constraining the mechanisms that govern this spatial arrangement is fundamental to understand the dynamics of shallow magma storage and transport and evaluate volcanic hazard. Here we show with numerical models that the previously unappreciated unloading effect of caldera formation may contribute significantly to the stress budget of a volcano. We first test this hypothesis against the ideal case of Fernandina, Galápagos, where previous models only partly explained the peculiar pattern of circumferential and radial eruptive fissures and the geometry of the intrusions determined by inverting the deformation data. We show that by taking into account the decompression due to the caldera formation, the modeled edifice stress field is consistent with all the observations. We then develop a general model for the stress state at volcanic edifices with calderas based on the competition of caldera decompression, magma buoyancy forces and tectonic stresses. These factors control: 1) the shallow accumulation of magma in stacked sills, consistently with observations; 2) the conditions for the development of circumferential and/or radial eruptive fissures, as observed on active volcanoes. This top-down control exerted by changes in the distribution of mass at the surface allows better understanding of how shallow magma is transferred at active calderas, contributing to forecasting the location and type of opening fissures.

  18. Magma transfer at Campi Flegrei caldera (Italy) before the 1538 AD eruption

    Science.gov (United States)

    di Vito, Mauro A.; Acocella, Valerio; Aiello, Giuseppe; Barra, Diana; Battaglia, Maurizio; Carandente, Antonio; Del Gaudio, Carlo; de Vita, Sandro; Ricciardi, Giovanni P.; Ricco, Ciro; Scandone, Roberto; Terrasi, Filippo

    2016-08-01

    Calderas are collapse structures related to the emptying of magmatic reservoirs, often associated with large eruptions from long-lived magmatic systems. Understanding how magma is transferred from a magma reservoir to the surface before eruptions is a major challenge. Here we exploit the historical, archaeological and geological record of Campi Flegrei caldera to estimate the surface deformation preceding the Monte Nuovo eruption and investigate the shallow magma transfer. Our data suggest a progressive magma accumulation from ~1251 to 1536 in a 4.6 ± 0.9 km deep source below the caldera centre, and its transfer, between 1536 and 1538, to a 3.8 ± 0.6 km deep magmatic source ~4 km NW of the caldera centre, below Monte Nuovo; this peripheral source fed the eruption through a shallower source, 0.4 ± 0.3 km deep. This is the first reconstruction of pre-eruptive magma transfer at Campi Flegrei and corroborates the existence of a stationary oblate source, below the caldera centre, that has been feeding lateral eruptions for the last ~5 ka. Our results suggest: 1) repeated emplacement of magma through intrusions below the caldera centre; 2) occasional lateral transfer of magma feeding non-central eruptions within the caldera. Comparison with historical unrest at calderas worldwide suggests that this behavior is common.

  19. Long Valley Caldera 2003 through 2014: overview of low level unrest in the past decade

    Science.gov (United States)

    Wilkinson, Stuart K.; Hill, David P.; Langbein, John O.; Lisowski, Michael; Mangan, Margaret T.

    2014-01-01

    Long Valley Caldera is located in California along the eastern escarpment of the Sierra Nevada Range. The caldera formed about 760,000 years ago as the eruption of 600 km3 of rhyolite magma (Bishop Tuff) resulted in collapse of the partially evacuated magma chamber. Resurgent doming in the central part of the caldera occurred shortly afterwards, and the most recent eruptions inside the caldera occurred about 50,000 years ago. The caldera remains thermally active, with many hot springs and fumaroles, and has had significant deformation and seismicity since at least 1978. Periods of intense unrest in the 1980s to early 2000s are well documented in the literature (Hill and others, 2002; Ewert and others, 2010). In this poster, we extend the timeline forward, documenting seismicity and deformation over the past decade.

  20. Preliminary geologic studies of Sierra El Aguajito (Baja California, Mexico): a resurgent-type caldera

    Science.gov (United States)

    Garduño-Monroy, V. H.; Vargas-Ledezma, H.; Campos-Enriquez, J. O.

    1993-12-01

    Geologic field studies conducted in the Quaternary volcanic field of Tres Virgenes (State of Baja California Sur, Mexico) revealed the existence of a resurgent caldera. The caldera's eruptive products, the Aguajito sequence, overlie the products of the nearby Reforma caldera (Reforma sequence) whose youngest products have already been dated as Quaternary. The rim of the Aguajito caldera is inferred by the existence of an arcuate alignment of rhyolitic domes. The mean diameter of this subcircular feature is 10 km. The volume of its mapped acidic products is a minimum of 10 km 3. Several horizons within the sequence contain shells. K/Ar dates of the ignimbrites and domes of El Aguajito formation confirm that the unit are Pleistocene. The detailed stratigraphy also shows the evolution of a marine regression partly related to the caldera.

  1. Juan Ruiz político

    Directory of Open Access Journals (Sweden)

    Georges Martin

    2007-01-01

    Full Text Available Más bien que en la vida amorosa del Arcipreste de Hita, de la que no sabemos nada, quizá tengamos que ver en el importantísimo conflicto con incidencias dinásticas virtualmente devastadoras entre María de Portugal, la mujer legítima de Alfonso XI, y Leonor de Guzmán, su concubina oficial, o, si se quiere, en el “loco amor” del rey y en el partido (el de María que –sugiero- escogió Juan Ruiz, la causa del encarcelamiento del autor del Libro de buen amor. También se comprendería que dicho contexto haya dado lugar a una obra que, tan ortodoxa en su sententia como genialmente paradójica en su littera, no tergiversa sobre los fundamentos a la vez sociales y espirituales del “buen amor” como tampoco se muestra muy propicia a la realeza tal y como la encarnaba entonces Alfonso XI de Castilla.Plutôt que dans la vie amoureuse de l’Archiprêtre de Hita, dont nous ne savons rien, peut-être faudrait-il voir dans le grave conflit aux incidences dynastiques virtuellement dévastatrices qui opposa Marie de Portugal, femme légitime d’Alphonse XI, et Aliénor de Guzmán, sa concubine officielle, ou, si l’on veut, dans le « fol amour » du roi et dans le parti (celui de Marie que choisit –je le suggère– Juan Ruiz, la cause de l’emprisonnement de l’auteur du Libro de buen amor. L’on comprendrait aussi que ce contexte ait donné lieu à une œuvre qui, aussi orthodoxe dans sa sententia que génialement paradoxale dans sa littera, ne tergiverse nullement sur les fondements sociaux et spirituels du « bon amour » mais ne se montre pas non plus favorable à une royauté telle que l’incarne alors Alphonse XI de Castille.

  2. Las Silvas de Juan Lorenzo Palmireno

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    Lee, Lilith

    2006-12-01

    Full Text Available This paper examines the works titled Silva by Juan Lorenzo Palmireno. The analysis of these texts sheds light on Palmireno’s understanding of the word and its possible implications in the sixteenth century. The study identifies an interpretation of silva as a way of writing different from his predecessor, Pedro Mexía, who first used it to title his work Silva de varia lección twenty years ago. The lack of any intention to arrange its structure gives these silvas the characteristic of a literary draft, a feature derived from one of the meanings of silva inherited from the Classical Age. Moreover, Palmireno’s works reveal an encyclopedic project of which the miscellany (represented by silva forms a part. Furthermore, the silvas of Palmireno act as a transition to the later development of silva as a genre, which finds its educational objective being taken over gradually by the anxiety to provide entertainment.El artículo examina las obras tituladas Silva de Juan Lorenzo Palmireno. El análisis de estos textos deja constancia de cómo el humanista entiende la palabra y sus implicaciones en el siglo XVI. El estudio identifica una interpretación de silva como una manera de escribir distinta de su predecesor, Pedro Mexía, quien veinte años antes la utilizó para nombrar a su obra Silva de varia lección. La falta de la intención en ordenar los textos les otorga a las silvas palmirenianas la característica de un borrador literario, uno de los significados de la silva desde la Edad Clásica. Además, las obras del humanista aragonés muestra su proyecto enciclopédico del autor que integra la miscelánea (representada por la silva como una parte. Estas silvas también actúan como la transición para el desarrollo de la silva como género que encuentra su objetivo educacional sustituido gradualmente por la finalidad de ofrecer entretenimiento.

  3. Structure of the Nemrut caldera (Eastern Anatolia, Turkey) and associated hydrothermal fluid circulation

    Science.gov (United States)

    Ulusoy, İnan; Labazuy, Philippe; Aydar, Erkan; Ersoy, Orkun; Çubukçu, Evren

    2008-07-01

    Plio-Quaternary volcanism played an important role in the present physical state of Eastern Anatolia. Mount Nemrut, situated to the west of Lake Van is one of the main volcanic centers in the region, with a spectacular summit caldera 8.5 × 7 km in diameter. The most recent eruptions of the volcano were in 1441, 1597 and 1692. Nemrut Lake covers the western half of the caldera; it is a deep, half-bowl-shaped lake with a maximum depth of 176 m. Numerous eruption centers are exposed within the caldera as a consequence of magma-water interaction. Current activity of Nemrut caldera is revealed as hot springs, fumaroles and a small, hot lake. Self-potential and bathymetric surveys carried out in the caldera were used to characterize the structure of the caldera and the associated hydrothermal fluid circulation. In addition, analyses based on digital elevation models and satellite imagery were used to improve our knowledge about the structure of the caldera. According to SP results, the flanks of the volcano represent "the hydrogeologic zone", whereas the intra-caldera region is an "active hydrothermal area" where the fluid circulation is controlled by structural discontinuities. There is also a northern fissure zone which exhibits hydrothermal signatures. Nemrut caldera collapsed piecemeal, with three main blocks. Stress controlling the collapse mechanism seems to be highly affected by the regional neotectonic regime. In addition to the historical activity, current hydrothermal and hydrogeologic conditions in the caldera, in which there is a large lake and shallow water table, increase the risk of the quiescent volcano.

  4. A multidisciplinary study of the 2014-2015 Bárðarbunga caldera collapse, Iceland

    Science.gov (United States)

    Tumi Gudmundsson, Magnus; Jonsdóttir, Kristin; Hooper, Andy; Holohan, Eoghan; Halldorsson, Saemundur

    2016-04-01

    The collapse of the ice-filled Bárðarbunga caldera in central Iceland occurred in autumn and winter, when weather was highly unsettled and conditions for monitoring in many ways difficult. Nevertheless several detailed time series could be obtained on the collapse and to a degree the associated flood-basalt eruption in Holuhraun. This was achieved through applying an array of sensors, that were ground, air and satellite based, partly made possible through the EU-funded FUTUREVOLC supersite project. This slow caldera collapse lasted six months, ending in February 2015. The array of sensors used, coupled with the long duration of the event, allowed unprecedented detail in observing a caldera collapse. The deciphering of the course of events required the use of aircraft altimeter surveys of the ice surface, seismic and GPS monitoring, the installation of a GPS station on the glacier surface in the centre of the caldera that continuously recorded the subsidence. Full Stokes 3-D modelling of the 700-800 m thick ice in the caldera, constrained by observations, was applied to remove the component of ice deformation that had a minor effect on the measured subsidence. The maximum subsidence of the subglacial caldera floor was about 65 meters. The combined interpretation of geochemical geobarometers, subsidence geometry with GPS and InSAR deformation signals, seismicity and distinct element deformation modelling of the subsidence provided unprecedented detail of the process and mechanism of caldera collapse. The collapse involved the re-activation of pre-existing ring faults, and was initiated a few days after magma started to drain from underneath the caldera towards the eventual eruption site in Holuhraun, 45 km to the northeast. The caldera collapse was slow and gradual, and the flow rate from underneath the caldera correlates well with the lava flow rate in Holuhraun, both in terms of total volume and variations in time.

  5. Juan Bautista Perolli. Obras genovesas. II

    Directory of Open Access Journals (Sweden)

    López Torrijos, Rosa

    2002-06-01

    Full Text Available In this article the study of Perolli's work in Genoa is continued, demonstrating his varied artistic activities and his relationship with families under Spanish influence. His last work in Genoa (the Spinola Chapel in the church of San Francisco had to be completed by other artists because Perolli was engaged by Don Alvaro de Bazán to work in his Spanish palace of El Viso. In December 1574, Bazán paid Perolli's debts and shortly afterwards Juan Bautista left for Spain.

    Continúa el estudio de la obra de Perolli en Génova, mostrando su participación en trabajos de arquitectura, escultura y pintura para varias familias genovesas, todas ellas relacionadas con España. Se estudia también su última obra realizada en Génova, la capilla Spinola de la iglesia de San Francisco, desaparecida y totalmente desconocida hasta ahora. Este último trabajo queda interrumpido en diciembre de 1574 cuando don Álvaro de Bazán paga las deudas de Perolli para que éste venga a España a trabajar en el palacio del Viso.

  6. JUAN SIN MIEDO VA A LA ESCUELA

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    Silvia Méndez-Anchía

    2009-01-01

    Full Text Available Tomando como base la lectura del cuento "Juan Sin Miedo" realizada por tres sujetos adolescentes, pretendo responder a la pregunta sobre los principales temores que enfrenta la población costarricense adolescente en la actualidad. Las respuestas giran en torno a tres núcleos significativos: el miedo a la exclusión económica y social, materializada en el trato discriminatorio hacia quienes no se adecuan a los criterios impuestos por la sociedad de consumo; el miedo a la escuela, en tanto excluye a quienes no se ajustan a la norma esperada de desempeño académico; y el miedo al otro, en particular a la calle y la escuela como espacios de violencia. Concluyo señalando que, detrás de dichos temores, es posible leer un anhelo de pertenencia; de aprecio sincero y gratuito, en que no medie el rendimiento académico de la persona; así como un anhelo de seguridad en el entorno cercano.

  7. Origin of Hot Creek Canyon, Long Valley caldera, California

    Energy Technology Data Exchange (ETDEWEB)

    Maloney, N.J. (California State Univ., Fullerton, CA (United States). Dept. of Geological Sciences)

    1993-04-01

    Hot Creek has eroded a canyon some thirty meters deep across the Hot Creek rhyolite flows located in the southeastern moat of Long Valley Caldera. Maloney (1987) showed that the canyon formed by headward erosion resulting from spring sapping along hydrothermally altered fractures in the rhyolite, and the capture of Mammoth Creek. This analysis ignored the continuing uplift of the central resurgent dome. Reid (1992) concluded that the downward erosion of the canyon must have kept pace with the uplift. Long Valley Lake occupied the caldera until 100,000 to 50,000 years before present. The elevation of the shoreline, determined by trigonometric leveling, is 2,166 m where the creek enters the canyon and 2,148 m on the downstream side of the rhyolite. The slope of the strand line is about equal to the stream gradient. The hill was lower and the stream gradient less at the time of stream capture. Rotational uplift increased the stream gradient which increased the rate of downward erosion and formed the V-shaped canyon

  8. Renewed inflation of Long Valley Caldera, California (2011 to 2014)

    Science.gov (United States)

    Montgomery-Brown, Emily; Wicks, Chuck; Cervelli, Peter F.; Langbein, John O.; Svarc, Jerry L.; Shelly, David R.; Hill, David P.; Lisowski, Michael

    2015-01-01

    Slow inflation began at Long Valley Caldera in late 2011, coinciding with renewed swarm seismicity. Ongoing deformation is concentrated within the caldera. We analyze this deformation using a combination of GPS and InSAR (TerraSAR-X) data processed with a persistent scatterer technique. The extension rate of the dome-crossing baseline during this episode (CA99 to KRAC) is 1 cm/yr, similar to past inflation episodes (1990–1995 and 2002–2003), and about a tenth of the peak rate observed during the 1997 unrest. The current deformation is well modeled by the inflation of a prolate spheroidal magma reservoir ∼7 km beneath the resurgent dome, with a volume change of ∼6 × 106 m3/yr from 2011.7 through the end of 2014. The current data cannot resolve a second source, which was required to model the 1997 episode. This source appears to be in the same region as previous inflation episodes, suggesting a persistent reservoir.

  9. Months between rejuvenation and volcanic eruption at Yellowstone caldera, Wyoming

    Science.gov (United States)

    Till, Christy B.; Vazquez, Jorge A.; Boyce, Jeremy W

    2015-01-01

    Rejuvenation of previously intruded silicic magma is an important process leading to effusive rhyolite, which is the most common product of volcanism at calderas with protracted histories of eruption and unrest such as Yellowstone, Long Valley, and Valles, USA. Although orders of magnitude smaller in volume than rare caldera-forming super-eruptions, these relatively frequent effusions of rhyolite are comparable to the largest eruptions of the 20th century and pose a considerable volcanic hazard. However, the physical pathway from rejuvenation to eruption of silicic magma is unclear particularly because the time between reheating of a subvolcanic intrusion and eruption is poorly quantified. This study uses geospeedometry of trace element profiles with nanometer resolution in sanidine crystals to reveal that Yellowstone’s most recent volcanic cycle began when remobilization of a near- or sub-solidus silicic magma occurred less than 10 months prior to eruption, following a 220,000 year period of volcanic repose. Our results reveal a geologically rapid timescale for rejuvenation and effusion of ~3 km3 of high-silica rhyolite lava even after protracted cooling of the subvolcanic system, which is consistent with recent physical modeling that predict a timescale of several years or less. Future renewal of rhyolitic volcanism at Yellowstone is likely to require an energetic intrusion of mafic or silicic magma into the shallow subvolcanic reservoir and could rapidly generate an eruptible rhyolite on timescales similar to those documented here.

  10. Sheet flow caves of Kilauea Caldera, Hawaii County, Hawaii

    Directory of Open Access Journals (Sweden)

    William R. Halliday

    1998-01-01

    Full Text Available Terminal lobes of sheet flows of pahoehoe lava sometimes form three-dimensional nests, initially separated by partitions consisting of accreted ‘skins” of each lobe. Melting breaks down these partitions, forming a uniform flow unit. In Kilauea Caldera we have found and mapped sizable drained cavities in low-slope sheet flows. Their general pattern includes three-dimensional nests, with partially melted septa evident in some examples. Christmas Cave is the most extensive found to date, with 632 meters surveyed on two levels. It is located at the lower end of an inflated sheet flow tongue which underwent local deflation as a result of drainage through the cave after its parameters were partially fixed. Small conduit remnants persist in its boundary ridges. The major part of the cave consists of wide, low nestled chambers. Meltdown of such partitions is one of the few emplacement mechanisms of thermal erosion which may not involve any mechanical element. Additional caves in this caldera are being identified and studied.

  11. Summary of recent research in Long Valley Caldera, California

    Science.gov (United States)

    Sorey, M.L.; McConnell, V.S.; Roeloffs, E.

    2003-01-01

    Since 1978, volcanic unrest in the form of earthquakes and ground deformation has persisted in the Long Valley caldera and adjacent parts of the Sierra Nevada. The papers in this special volume focus on periods of accelerated seismicity and deformation in 1980, 1983, 1989-1990, and 1997-1998 to delineate relations between geologic, tectonic, and hydrologic processes. The results distinguish between earthquake sequences that result from relaxation of existing stress accumulation through brittle failure and those in which brittle failure is driven by active intrusion. They also indicate that in addition to a relatively shallow (7-10-km) source beneath the resurgent dome, there exists a deeper (???15-km) source beneath the south moat. Analysis of microgravimety and deformation data indicates that the composition of the shallower source may involve a combination of silicic magma and hydrothermal fluid. Pressure and temperature fluctuations in wells have accompanied periods of crustal unrest, and additional pressure and temperature changes accompanying ongoing geothermal power production have resulted in land subsidence. The completion in 1998 of a 3000-m-deep drill hole on the resurgent dome has provided useful information on present and past periods of circulation of water at temperatures of 100-200??C within the crystalline basement rocks that underlie the post-caldera volcanics. The well is now being converted to a permanent geophysical monitoring station. ?? 2003 Elsevier B.V. All rights reserved.

  12. Physical volcanology of the mafic segment of the subaqueous New Senator caldera, Abitibi greenstone belt, Quebec, Canada

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Lyndsay N; Mueller, Wulf U [Universite du Quebec a Chicoutimi, 555 boul. du l' Universite, Chicoutimi, Quebec, G7H2B1 (Canada)], E-mail: lyndsay.moore@uqac.ca

    2008-10-01

    Archean calderas provide valuable insight into internal geometries of subaqueous calderas. The New Senator caldera, Abitibi greenstone belt, Canada, is an Archean example of a subaqueous nested caldera with a basal stratigraphy dominated by gabbro-diorite dykes and sills, ponded magmas and basalt and andesite lava flows. The aim of our study is to focus on the use of physical volcanology to differentiate between the various mafic units found at the base of the New Senator caldera. Differentiation between these various mafic units is important from an exploration point of view because in modern subaqueous summit calders (e.g. Axial Seamount) margins of ponded magmas are often sites of VMS formation.

  13. Lithologic descriptions and temperature profiles of five wells in the southwestern Valles caldera region, New Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Shevenell, L.; Goff, F.; Miles, D.; Waibel, A.; Swanberg, C.

    1988-01-01

    The subsurface stratigraphy and temperature profiles of the southern and western Valles caldera region have been well constrained with the use of data from the VC-1, AET-4, WC 23-4, PC-1 and PC-2 wells. Data from these wells indicate that thermal gradients west of the caldera margin are between 110 and 140)degrees)C/km, with a maximum gradient occurring in the bottom of PC-1 equal to 240)degrees)C/km as a result of thermal fluid flow. Gradients within the caldera reach a maximum of 350)degrees)C/km, while the maximum thermal gradient measured southwest of the caldera in the thermal outflow plume is 140)degrees)C/km. The five wells exhibit high thermal gradients (>60)deghrees)C/km) resulting from high conductive heat flow associated with the Rio Grande rift and volcanism in the Valles caldera, as well as high convective heat flow associated with circulating geothermal fluids. Gamma logs run in four of the five wells appear to be of limited use for stratigraphic correlations in the caldera region. However, stratigraphic and temperature data from the five wells provide information about the structure and thermal regime of the southern and western Valles caldera region. 29 refs., 9 figs. 2 tabs.

  14. SMCRA bond release - the initial steps at San Juan mine

    Energy Technology Data Exchange (ETDEWEB)

    Estrada, O.; Clark, D. [BHP San Juan Coal Company, Waterflow, NM (United States)

    2001-07-01

    San Juan Coal Company has submitted to the State of New Mexico's Mining and Minerals Division the final phase III bond release application for the approval and release of 241 acres of permitted lands at its San Juan Mine located in San Juan County, New Mexico. The SMCRA (Surface Mining Control and Reclamation Act) and New Mexico Surface Coal Mining Regulations mandate a minimum 10-year liability period following final reclamation, during which no additional treatments other than approved postmining land uses and approved interseedings may be applied to an area for which bond release is sought. Site-specific revegetation success standards must be met for two of the last four years of liability, beginning no sooner than year eight of the bonding period. Successful reclamation of the site was demonstrated by exceeding cover, production, shrub density, and diversity standards while supporting the primary postmining land use of livestock grazing. 11 refs., 1 fig., 8 tabs.

  15. Subsurface architecture of a strike-slip collapse structure: insights from Ilopango caldera, El Salvador

    Science.gov (United States)

    Saxby, Jennifer; Gottsmann, Joachim; Cashman, Katherine; Gutierrez, Eduardo

    2016-04-01

    While most calderas are created by roof collapse along ring-like faults into an emptying magma reservoir during a large and violent explosive eruption, an additional condition for caldera formation may be tectonically induced extensional stresses. Here we provide geophysical insights into the shallow sub-volcanic plumbing system of a collapse caldera in a major strike-slip tectonic setting by inverting Bouguer gravity data from the Ilopango caldera in El Salvador. Despite a long history of catastrophic eruptions with the most recent in 500 A.D., the internal architecture of the caldera has not been investigated, although studies of the most recent eruption have not identified the ring faults commonly associated with caldera collapse. The gravity data show that low-density material aligned along the principal stress orientations of the El Salvador Fault Zone (ESFZ) forms a pronounced gravity low beneath the caldera. Extending to around 6 km depth, the low density structure likely maps a complex stacked shallow plumbing system composed of magmatic and fractured hydrothermal reservoirs. A substantial volume of the plumbing system must be composed of a vapour phase to explain the modeled negative density contrasts. We use these constraints to map the possible multi-phase parameter space contributing to the subsurface architecture of the caldera and propose that the local extension along the complex ESFZ controls accumulation, ascent and eruption of magma at Ilopango. The data further suggest that future eruptions at Ilopango could be facilitated by rapid rise of magma along conjugate fault damage zones through a mechanically weak crust under tension. This may explain the absence of clear ring fault structures at the caldera.

  16. Anomalías magnéticas en la Caldera Piedra Parada, Patagonia, Argentina

    OpenAIRE

    Aragón, Eugenio; Pinotti, Lucio; D´Eramo, Fernando Javier; GÓMEZ-ORTIZ, DAVID; Tejero López, Rosa; Tubia, José María; Cavarozzi, Claudia Ernestina; Aguilera, Yolanda Emilia; Ribot, Alejandro Mario; Gianibelli, Julio; Chernicoff, Carlos Jorge

    2009-01-01

    La caldera de Piedra Parada constituye el principal edificio volcánico del Complejo Volcánico Piroclástico del curso medio del río Chubut, situado en la provincia argentina de Chubut. Los materiales intracaldera están constituidos por coladas riolíticas, sills andesíticos, domos riolíticos y tobas de composición riolítica. Con objeto de investigar la estructura de la caldera, se han obtenido tanto datos magnéticos terrestres como aeromagnéticos. Los mapas magnéticos muestran que la caldera se...

  17. LOD First Estimates In 7406 SLR San Juan Argentina Station

    Science.gov (United States)

    Pacheco, A.; Podestá, R.; Yin, Z.; Adarvez, S.; Liu, W.; Zhao, L.; Alvis Rojas, H.; Actis, E.; Quinteros, J.; Alacoria, J.

    2015-10-01

    In this paper we show results derived from satellite observations at the San Juan SLR station of Felix Aguilar Astronomical Observatory (OAFA). The Satellite Laser Ranging (SLR) telescope was installed in early 2006, in accordance with an international cooperation agreement between the San Juan National University (UNSJ) and the Chinese Academy of Sciences (CAS). The SLR has been in successful operation since 2011 using NAOC SLR software for the data processing. This program was designed to calculate satellite orbits and station coordinates, however it was used in this work for the determination of LOD (Length Of Day) time series and Earth Rotation speed.

  18. Field procedures manual: INYO-4, Long Valley Caldera, California

    Energy Technology Data Exchange (ETDEWEB)

    Goff, S.

    1989-01-01

    This Field Procedures Manual is the comprehensive operations guide to be used to curate samples obtained from the INYO-4 site in the Long Valley Caldera, California. This site is a diamond drilling project in small-diameter holes that will produce continuous core. Fluid samples will also be of primary importance at this site. Detailed core and fluid handling procedures are therefore the major focus of this manual. The manual provides a comprehensive operations guide for the well-site geoscientists working at the Department of Energy/Office of Basic Energy Sciences (DOE/OBES) Continental Scientific Drilling Program (CSDP)/Thermal Regimes drill sites. These procedures modify and improve those in previous DOE/OBES field manuals. 1 ref.; 6 figs.

  19. Geologic field-trip guide to Long Valley Caldera, California

    Science.gov (United States)

    Hildreth, Wes; Fierstein, Judy

    2017-07-26

    This guide to the geology of Long Valley Caldera is presented in four parts: (1) An overview of the volcanic geology; (2) a chronological summary of the principal geologic events; (3) a road log with directions and descriptions for 38 field-trip stops; and (4) a summary of the geophysical unrest since 1978 and discussion of its causes. The sequence of stops is arranged as a four-day excursion for the quadrennial General Assembly of the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI), centered in Portland, Oregon, in August 2017. Most stops, however, are written freestanding, with directions that allow each one to be visited independently, in any order selected.

  20. Oblique synoptic images, produced from digital data, display strong evidence of a "new" caldera in southwestern Guatemala

    Science.gov (United States)

    Duffield, W.; Heiken, G.; Foley, D.; McEwen, A.

    1993-01-01

    The synoptic view of broad regions of the Earth's surface as displayed in Landsat and other satellite images has greatly aided in the recognition of calderas, ignimbrite plateaus and other geologic landforms. Remote-sensing images that include visual representation of depth are an even more powerful tool for geologic interpretation of landscapes, but their use has been largely restricted to the exploration of planets other than Earth. By combining Landsat images with digitized topography, we have generated regional oblique views that display compelling evidence for a previously undocumented late-Cenozoic caldera within the active volcanic zone of southwestern Guatemala. This "new" caldera, herein called Xela, is a depression about 30 km wide and 400-600 m deep, which includes the Quezaltenango basin. The caldera depression is breached only by a single river canyon. The caldera outline is broadly circular, but a locally scalloped form suggests the occurrence of multiple caldera-collapse events, or local slumping of steep caldera walls, or both. Within its northern part, Xela caldera contains a toreva block, about 500 m high and 2 km long, that may be incompletely foundered pre-caldera bedrock. Xela contains several post-caldera volcanoes, some of which are active. A Bouguer gravity low, tens of milligals in amplitude, is approximately co-located with the proposed caldera. The oblique images also display an extensive plateau that dips about 2?? away from the north margin of Xela caldera. We interpret this landform to be underlain by pyroclastic outflow from Xela and nearby Atitla??n calderas. Field mapping by others has documented a voluminous rhyolitic pumiceous fallout deposit immediately east of Xela caldera. We speculate that Xela caldera was the source of this deposit. If so, the age of at least part of the caldera is between about 84 ka and 126 ka, the ages of deposits that stratigraphically bracket this fallout. Most of the floor of Xela caldera is covered

  1. Maars to calderas: end-members on a spectrum of explosive volcanic depressions

    Directory of Open Access Journals (Sweden)

    Danilo M. Palladino

    2015-07-01

    Full Text Available We discuss maar-diatremes and calderas as end-members on a spectrum of negative volcanic landforms (depressions produced by explosive eruptions (note – we focus on calderas formed during explosive eruptions, recognizing that some caldera types are not related to such activity. The former are dominated by ejection of material during numerous discrete phreatomagmatic explosions, brecciation, and subsidence of diatreme fill, while the latter are dominated by subsidence over a partly evacuated magma chamber during sustained, magmatic volatile-driven discharge. Many examples share characteristics of both, including landforms that are identified as maars but preserve deposits from non-phreatomagmatic explosive activity, and ambiguous structures that appear to be coalesced maars but that also produced sustained explosive eruptions with likely magma reservoir subsidence. A convergence of research directions on issues related to magma-water interaction and shallow reservoir mechanics is an important avenue toward developing a unified picture of the maar-diatreme-caldera spectrum.

  2. Field trip guide to the Valles Caldera and its geothermal systems

    Energy Technology Data Exchange (ETDEWEB)

    Goff, F.E.; Bolivar, S.L.

    1983-12-01

    This field trip guide has been compiled from extensive field trips led at Los Alamos National Laboratory during the past six years. The original version of this guide was designed to augment a workshop on the Valles Caldera for the Continental Scientific Drilling Program (CSDP). This workshop was held at Los Alamos, New Mexico, 5-7 October 1982. More stops were added to this guide to display the volcanic and geothermal features at the Valles Caldera. The trip covers about 90 miles (one way) and takes two days to complete; however, those who wish to compress the trip into one day are advised to use the designated stops listed in the Introduction. Valles Caldera and vicinity comprise both one of the most exciting geothermal areas in the United States and one of the best preserved Quaternary caldera complexes in the world.

  3. Steady subsidence of a repeatedly erupting caldera through InSAR observations: Aso, Japan

    KAUST Repository

    Nobile, Adriano

    2017-04-05

    The relation between unrest and eruption at calderas is still poorly understood. Aso caldera, Japan, shows minor episodic phreatomagmatic eruptions associated with steady subsidence. We analyse the deformation of Aso using SAR images from 1993 to 2011 and compare it with the eruptive activity. Although the dataset suffers from limitations (e.g. atmospheric effects, coherence loss, low signal-to-noise ratio), we observe a steady subsidence signal from 1996 to 1998, which suggests an overall contraction of a magmatic source below the caldera centre, from 4 to 5 km depth. We propose that the observed contraction may have been induced by the release of the magmatic fluids feeding the eruptions. If confirmed by further data, this hypothesis suggests that degassing processes play a crucial role in triggering minor eruptions within open conduit calderas, such as at Aso. Our study underlines the importance of defining any eruptive potential also from deflating magmatic systems with open conduit.

  4. Entrevista a Juan Alberto Puyana, autor de El Preticante.

    OpenAIRE

    Carrión Jiménez, Andoni

    2012-01-01

    Juan Alberto Puyana es un tipo particular. Por su negra melena rizada y su perilla, propia del seguidor de Metallica que es, nadie diría que, además de enfermero, Alberto es un escritor con dos libros publicados.

  5. [Psychiatric Hospital San Juan de Dios. One hundred years later].

    Science.gov (United States)

    Cocula-León, Horacio

    2014-01-01

    Mental health and psychiatric diseases have always attracted people's and health authorities' attention due to its magical approach, the lack of knowledge that surrounds them, and, at the same time, the religious fear they provoke. Both have played an important role in the history of humanity, of public health politics, and of physicians. The places where psychiatric patients were treated are of historical interest, because through the historical knowledge we can identify an approach from the science and the health policies that prevailed in each age. At the beginning of the 20th century, it was developed in México a new model of hospital care attention to psychiatric patients. La Casa de Salud San Juan de Dios para Pacientes Alienados is an example; the concept "alienated patients" suggests a social and cultural perspective. This paper presents a chronological type description of one of the major institutions involved in mental health care in México. Similarly, it shows a review of the events that affected the religious order San Juan de Dios from 1901 to 2012, when the hospitaller order was reinstated in México and established the Casa de Salud San Juan de Dios para Pacientes Alienados in the town of Zapopan, Jalisco, institution that exists up to the present day and keeps participating in the mental health care in the state of Jalisco, with the current name of Servicios de Salud San Juan de Dios.

  6. Don Juan Huarte de San Juan: El doctor que anticipó la melancolía de Don Quijote Don Juan Huarte de San Juan: The doctor who antocipated Don Quixote´s Melancholy

    Directory of Open Access Journals (Sweden)

    Pedro García Martín

    2009-03-01

    Full Text Available El estado de enajenación del ingenioso hidalgo don Quijote lo había aprendido Cervantes a través del doctor Juan Huarte San Juan, autor del famoso ensayo Examen de ingenios, donde formula la teoría de los humores para explicar el cuerpo y el carácter del hombre. En este artículo, pues, repasaremos la biografía de este personaje, analizaremos la formación de los médicos en las universidades de la España del Siglo de Oro, la influencia del Examen en la Europa de su tiempo y en la obra cervantina a través de la melancolía de don Quijote y de la locura del Licenciado Vidriera. Para terminar con la aplicación literaria de las tesis sobre ingenios que definiera nuestro dilecto médico de resonancia mundial.Cervantes learned about Don Quixote's derangement through Juan Huarte de San Juan's famous treatise Examen de ingenios, where he deployed the humoral theory to explain human body and character. In this article Huarte's biography will be summarized, analyzing the academic background of golden age Spanish doctors, and the impact of Examen in Early Modern Europe and in Cervante's work by examining Don Quixote's melancholy and Licenciado Vidriera's madness. Finally, I will show how the internationally famous Spanish doctor's thesis was used in literature.

  7. Ladrillo and Tales of Juan Bobo: Puerto Rican Folk Tales.

    Science.gov (United States)

    Matos, Reinaldo; Matos, Ana

    These two illustrated elementary readers contain the Spanish and English versions of the Puerto Rican folk tales, "Ladrillo" and "Cuentos de Juan Bobo." They are part of a series of reading materials for elementary-level migrant children. These materials are intended to help the child relate to his culture, develop interest in knowing about it and…

  8. Ladrillo and Tales of Juan Bobo: Puerto Rican Folk Tales.

    Science.gov (United States)

    Matos, Reinaldo; Matos, Ana

    These two illustrated elementary readers contain the Spanish and English versions of the Puerto Rican folk tales, "Ladrillo" and "Cuentos de Juan Bobo." They are part of a series of reading materials for elementary-level migrant children. These materials are intended to help the child relate to his culture, develop interest in…

  9. El silencio como estrategia en la obra de Juan Rulfo

    OpenAIRE

    Gómez López-Quiñones, Loreto

    2013-01-01

    Juan Rulfo utiliza el silencio como un espacio para oír y decir mejor en el contexto del México postrevolucionario. Inspirándonos en la terminología de Spivak, pretendemos mostrar el silencio de Rulfo como una estrategia de resistencia ante la representación occidental del Otro.

  10. San Juan Basin, USA; coalbed methane development and production

    Energy Technology Data Exchange (ETDEWEB)

    Gluskoter, H. [US Geological Survey, Reston, VA (USA)

    2002-07-01

    Twenty one slides/overheads outline the talk on production of coalbed methane from sedimentary basins in the USA. Figures are given for production and reserves for the year 2000. The San Juan basin's geologic structure, containing resources of the Cretaceous coal age, primarily in the Fruitland Formation, is described. 4 refs.

  11. Offshore finfish mariculture in the Strait of Juan de Fuca

    Energy Technology Data Exchange (ETDEWEB)

    Rensel, Jack; Kiefer, Dale; Forster, John R.; Woodruff, Dana L.; Evans, Nathan R.

    2007-10-07

    Finfish mariculture has existed in the U.S. Pacific Northwest for over thirty years, but for the past 15 years most effort has focused on culture of Atlantic salmon in protected, inshore cage sites. The Strait of Juan de Fuca (the "Strait") is a large area with relatively sparce shoreline development and several apparent advantages for mariculture using offshore technology.

  12. Putting Educational Attainment First: An Interview with Juan Sepulveda

    Science.gov (United States)

    Carreon, Joe

    2011-01-01

    This article presents an interview with Juan Sepulveda. Sepulveda was appointed by U.S. Secretary of Education Arne Duncan to the position of Executive Director of the White House Initiative on Educational Excellence for Hispanics on May 19, 2009. In this capacity, Sepulveda is responsible for directing the efforts of the White House Initiative in…

  13. Ladrillo and Tales of Juan Bobo: Puerto Rican Folk Tales.

    Science.gov (United States)

    Matos, Reinaldo; Matos, Ana

    These two illustrated elementary readers contain the Spanish and English versions of the Puerto Rican folk tales, "Ladrillo" and "Cuentos de Juan Bobo." They are part of a series of reading materials for elementary-level migrant children. These materials are intended to help the child relate to his culture, develop interest in…

  14. Long Valley Caldera-Mammoth Mountain unrest: The knowns and unknowns

    Science.gov (United States)

    Hill, David P.

    2017-01-01

    This perspective is based largely on my study of the Long Valley Caldera (California, USA) over the past 40 years. Here, I’ll examine the “knowns” and the “known unknowns” of the complex tectonic–magmatic system of the Long Valley Caldera volcanic complex. I will also offer a few brief thoughts on the “unknown unknowns” of this system.

  15. Gravity study of Los Humeros caldera complex, Mexico: Structure and associated geothermal system

    Science.gov (United States)

    Campos-Enriquez, J. O.; Arredondo-Fragoso, J. J.

    1992-01-01

    Los Humeros caldera lies in the eastern portion of the Trans-Mexican Volcanic Belt. A geothermal system is associated with this silicic caldera. The volcano-sedimentary products of the caldera itself rest on a basement of calcareous rocks and granitic intrusives. A well-marked density contrast exists between these geologic units. Consequently, gravity measurements have proved to be a useful tool to estimate depths to the local basement. A detailed interpretation of the gravity anomaly of this caldera was conducted. Digital processing included vertical derivatives, downward, and upward continuations. In this way, it was possible to infer the main features of the subsurface structure of this caldera. The 3-D structural model so created was also constrained by geology and well data. It was tested by 3-D forward modelling. Two nested depressions are subsurficial expressions of two corresponding collapses. The western rim of the caldera complex is constituted by a structural high, representing a major weakness zone that controlled the location of several vents in the caldera complex. The geothermal system is located along this structure. A straightforward correlation is observed between the subsurficial structure (nested depressions, the minor central and major western structural highs respectively) and magnetic and resistivity anomalies (MT and d.c. resistivity studies). The enhanced permeability associated with the faulting along this major structural high accounts for the observed correlation with the resistivity data. Two relatively shallow heat sources are interpreted to exist at depths around 10 km. One is related to the actual geothermal production zone; the second, is located just to the southwest of the caldera complex. Because several other geological and geophysical parameters point to the possible existence of geothermal activity, this zone is considered a target for exploration, by means of wells, for geothermal fluids.

  16. Proceedings of the second workshop on hydrologic and geochemical monitoring in the Long Valley Caldera

    Energy Technology Data Exchange (ETDEWEB)

    Sorey, M.L.; Farrar, C.D.; Wollenberg, H.A. (eds.)

    1986-12-01

    A workshop was held to review the results of hydrologic and geochemical monitoring and scientific drilling in the Long Valley caldera. Such monitoring is being done to detect changes in the hydrothermal system induced by ongoing magmatic and techonic processes. Data from a 2400-ft deep core hole completed in June 1986 were presented at the 1986 workshop and participants discussed the need and rationale for siting locations for future scientific drilling in the caldera.

  17. How caldera collapse shapes the shallow emplacement and transfer of magma in active volcanoes

    Science.gov (United States)

    Corbi, Fabio; Rivalta, Eleonora; Pinel, Virginie; Maccaferri, Francesco; Bagnardi, Marco; Acocella, Valerio

    2016-04-01

    Calderas are topographic depressions formed by the collapse of a partly drained magma reservoir. At volcanic edifices with calderas, eruptive fissures can circumscribe the outer caldera rim, be oriented radially and/or align with the regional tectonic stress field. Constraining the mechanisms that govern this spatial arrangement is fundamental to understand the dynamics of shallow magma storage and transport and evaluate volcanic hazard. Here we use numerical models to show that the previously unappreciated unloading effect of caldera formation may contribute significantly to the stress budget of a volcano. We first test this hypothesis against the ideal case of Fernandina, Galápagos, where previous models only partly explained the peculiar pattern of circumferential and radial eruptive fissures and the geometry of the intrusions determined by inverting the deformation data. We show that by taking into account the decompression due to the caldera formation, the modeled edifice stress field is consistent with all the observation. We then develop a general model for the stress state at volcanic edifices with calderas based on the competition of caldera decompression, magma buoyancy forces and tectonic stresses. These factors control the shallow accumulation of magma in stacked sills, consistently with observations as well as the conditions for the development of circumferential and/or radial eruptive fissures, as observed on active volcanoes. This top-down control exerted by changes in the distribution of mass at the surface allows better understanding of how shallow magma is transferred at active calderas, contributing to forecasting the location and type of opening fissures.

  18. Proceedings of the second workshop on hydrologic and geochemical monitoring in the Long Valley Caldera

    Energy Technology Data Exchange (ETDEWEB)

    Sorey, M.L.; Farrar, C.D.; Wollenberg, H.A. (eds.)

    1986-12-01

    A workshop was held to review the results of hydrologic and geochemical monitoring and scientific drilling in the Long Valley caldera. Such monitoring is being done to detect changes in the hydrothermal system induced by ongoing magmatic and techonic processes. Data from a 2400-ft deep core hole completed in June 1986 were presented at the 1986 workshop and participants discussed the need and rationale for siting locations for future scientific drilling in the caldera.

  19. Post-eruptive flooding of Santorini caldera and implications for tsunami generation

    Science.gov (United States)

    Nomikou, Paraskevi; Druitt, Tim; Hübscher, Christian; Mather, Tamsin; Paulatto, Michele; Kalnins, Lara; Kelfoun, Karim; Papanikolaou, Dimitris; Bejelou, Konstantina; Lampridou, Danai; Pyle, David; Carey, Steven; Watts, Anthony; Weiß, Benedikt; Parks, Michelle

    2017-04-01

    Caldera-forming eruptions of island volcanoes generate tsunamis by the interaction of different eruptive phenomena with the sea. Such tsunamis are a major hazard, but forward models of their impacts are limited by poor understanding of source mechanisms. The eruption of Santorini 3600 years ago was one of the largest of eruptions known worldwide from the past 10,000 years - and was at least 3 times larger than the catastrophic eruption of Krakatoa. This huge eruption evacuated large volumes of magma, causing collapse of the large caldera, which is now filled with seawater. Tsunamis from this eruption have been proposed to have played a role in the demise of the Minoan culture across the southern Aegean, through damage to coastal towns, harbors, shipping and maritime trade. Before the eruption, there was an older caldera in the northern part of Santorini, partly filled with a shallow lagoon. In our study, we present bathymetric and seismic evidence showing that the caldera was not open to the sea during the main phase of the eruption, but was flooded once the eruption had finished. Following subsidence of the caldera floor, rapid inflow of seawater and landslides cut a deep 2.0-2.5 km3 submarine channel into the northern flank of the caldera wall. Hydrodynamic modelling indicates that the caldera was flooded through this breach in less than a couple of days. It was previously proposed that collapse of the caldera could have led to the formation of a major tsunami; but this is ruled out by our new evidence. Any tsunami's generated were most likely caused by entry of pyroclastic flows into the sea, combined with slumping of submarine pyroclastic accumulations. This idea is consistent with previous assertions that pyroclastic flows were the main cause of tsunamis at Krakatau.

  20. Conduit enlargement during the precursory Plinian eruption of Aira Caldera, Japan

    Science.gov (United States)

    Geshi, Nobuo; Miyabuchi, Yasuo

    2016-09-01

    Increase in magma flux as the result of conduit enlargement is one of the key processes that triggered caldera collapse and eruption of the Ito ignimbrite from Aira Caldera at ~29 ka. We examine the total volume of the pumice fall deposit, vertical variations in grain size of pumice, and the lithic content in the Osumi pumice deposit to investigate the trigger for caldera collapse. Wider distribution of the later-stage unit and the upward coarsening of grain size throughout the Osumi pumice fall deposit indicate an increase in magma discharge toward the onset of collapse. The total volume of lithic fragments in the Osumi pumice fall deposit is estimated as ~1.6 km3, based on the lithic content in several representative outcrops and the total volume of the Osumi pumice fall deposit. The lithic fragments in the Osumi pumice fall deposit indicate intense mechanical erosion of the conduit during the Plinian eruption prior to caldera collapse. Caldera collapse requires decompression of the magma chamber by withdrawal of magma; effective enlargement of the conduit diameter during precursory eruptive phases is one of the important processes that subsequently allow the rapid discharge of a large volume of magma, which in turn facilitates decompression of the reservoir and induces caldera collapse.

  1. Hydrothermal activity in the Tulancingo-Acoculco Caldera Complex, central Mexico. Exploratory studies

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Hernandez, Aida [Gerencia de Proyectos Geotermoelectricos, CFE, Alejandro Volta 655, 58290 Morelia, Michoacan (Mexico); Centro de Geociencias, Universidad Nacional Autonoma de Mexico, Campus Juriquilla, Queretaro, Qro., 76230 (Mexico); Garcia-Estrada, Gerardo; Palma-Guzman, Hugo; Quijano-Leon, Jose L. [Gerencia de Proyectos Geotermoelectricos, CFE, Alejandro Volta 655, 58290 Morelia, Michoacan (Mexico); Aguirre-Diaz, Gerardo; Gonzalez-Partida, Eduardo [Centro de Geociencias, Universidad Nacional Autonoma de Mexico, Campus Juriquilla, Queretaro, Qro., 76230 (Mexico)

    2009-09-15

    Mineral alteration and fluid inclusion studies of drill cuttings and core samples indicate that the sedimentary basement rocks and the volcanic rocks associated with Tulancingo-Acoculco Caldera Complex have been the site of two distinct and major hydrothermal events. The complex, located in the eastern portion of the Trans-Mexican Volcanic Belt, is formed by the Pliocene Tulancingo Caldera and the younger (Pleistocene) Acoculco Caldera, which developed within the older depression. The volcanic rocks are underlain by Cretaceous sedimentary rocks of the Sierra Madre Oriental. The earliest important hydrothermal event occurred during the emplacement of Mid-Tertiary granitic intrusions that metamorphosed the sedimentary rocks; these intrusives are not exposed at the surface. However, granitic rocks were encountered at the bottom of exploratory borehole EAC-1, drilled within the Caldera Complex. The second main event occurred during the formation of the Tulancingo and Acoculco Calderas. Both episodes lead to secondary mineralization that reduced the permeability of the reservoir rocks. A possible third hydrothermal event may be associated with the recent magmatic activity within the Acoculco Caldera.Thermal logs from well EAC-1 display a conductive thermal gradient with maximum temperatures exceeding 300 C at 2000 m depth. Although there are no active thermal springs in the area, there is extensive fossil surface hydrothermal alteration and cold gas discharges with high He{sup 3}/He{sup 4} ratios. (author)

  2. Post-eruptive flooding of Santorini caldera and implications for tsunami generation

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    Nomikou, P.; Druitt, T. H.; Hübscher, C.; Mather, T. A.; Paulatto, M.; Kalnins, L. M.; Kelfoun, K.; Papanikolaou, D.; Bejelou, K.; Lampridou, D.; Pyle, D. M.; Carey, S.; Watts, A. B.; Weiß, B.; Parks, M. M.

    2016-11-01

    Caldera-forming eruptions of island volcanoes generate tsunamis by the interaction of different eruptive phenomena with the sea. Such tsunamis are a major hazard, but forward models of their impacts are limited by poor understanding of source mechanisms. The caldera-forming eruption of Santorini in the Late Bronze Age is known to have been tsunamigenic, and caldera collapse has been proposed as a mechanism. Here, we present bathymetric and seismic evidence showing that the caldera was not open to the sea during the main phase of the eruption, but was flooded once the eruption had finished. Inflow of water and associated landsliding cut a deep, 2.0-2.5 km3, submarine channel, thus filling the caldera in less than a couple of days. If, as at most such volcanoes, caldera collapse occurred syn-eruptively, then it cannot have generated tsunamis. Entry of pyroclastic flows into the sea, combined with slumping of submarine pyroclastic accumulations, were the main mechanisms of tsunami production.

  3. P, S velocity and VP/VS ratio beneath the Toba caldera complex (Northern Sumatra) from local earthquake tomography

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    Koulakov, Ivan; Yudistira, Tedi; Luehr, Birger-G.; Wandono

    2009-06-01

    In this paper, we investigate the crustal and uppermost mantle structure beneath Toba caldera, which is known as the location of one of the largest Cenozoic eruptions on Earth. The most recent event occurred 74000 yr BP, and had a significant global impact on climate and the biosphere. In this study, we revise data on local seismicity in the Toba area recorded by a temporary PASSCAL network in 1995. We applied the newest version of the LOTOS-07 algorithm, which includes absolute source location, optimization of the starting 1-D velocity model, and iterative tomographic inversion for 3-D seismic P, S (or the VP/VS ratio) and source parameters. Special attention is paid to verification of the obtained results. Beneath the Toba caldera and other volcanoes of the arc, we observe relatively moderate (for volcanic areas) negative P- and S-velocity anomalies that reach 18 per cent in the uppermost layer, 10-12 per cent in the lower crust and about 7 per cent in the uppermost mantle. Much stronger contrasts are observed for the VP/VS ratio that is a possible indicator of dominant effect of melting in origin of seismic anomalies. At a depth of 5 km beneath active volcanoes, we observe small patterns (7-15 km size) with a high VP/VS ratio that might be an image of actual magmatic chambers filled with partially molten material feeding the volcanoes. In the mantle wedge, we observe a vertical anomaly with low P and S velocities and a high VP/VS ratio that link the cluster of events at 120-140 km depth with Toba caldera. This may be an image of ascending fluids and melts released from the subducted slab due to phase transitions. However, taking into account poor vertical resolution, these results should be interpreted with prudence. Although the results show clear signatures that are quite typical for volcanic areas (low velocity and high VP/VS ratio beneath volcanoes), we do not observe any specific features in seismic structure that could characterize Toba as a super volcano.

  4. O narrador solidário de Juan Coytisolo

    Directory of Open Access Journals (Sweden)

    Annete de Almeida Faria

    2011-11-01

    Full Text Available Resumo: Este artigo se propõe a analisar a construção do narrador de Cuaderno de Sarajevo: anotaciones de un viaje a la barbarie (1993, do escritor espanhol Juan Goytisolo, como expressão estética do seu compromisso ético. Tomamos como referência O narrador de Walter Benjamin para entender o narrador goytisolano como aquele que através das viagens busca o “outro”, elabora um arquivo memorial polifônico, misturando diferentes tipos de linguagem para dar voz às minorias.Palavras-chave: Literatura espanhola; Juan Goytisolo; Cuaderno de Sarajevo: anotaciones de un viaje a la barbarie; Walter Benjamin; O narrador; polifonia.Resumen: El propósito de este artículo consiste en analizar la construcción del narrador de Cuaderno de Sarajevo: anotaciones de un viaje a la barbarie (1993, del escritor español Juan Goytisolo, como expresión estética de su compromisso ético. Tomamos como base el ensayo El narrador, de Walter Benjamin, para comprender al narrador goytisolano como el que viaja en busca del “oro” (otredad para componer un archivo memorial polifónico, mezclando diferentes tipos de lenguaje para dar voz a las minorías.Palabras-clave: Literatura española; Juan Goytisolo; Cuaderno de Sarajevo: anotaciones de un viaje a la barbarie; Walter Benjamin; El narrador; polifonía.Keywords: Spanish literature; Juan Goytisolo; Cuaderno de Sarajevo: anotaciones de un viaje a la barbarie; Walter Benjamin; El narrador; poliphony.

  5. Martian Hot Springs? Silica deposits in the Nili Patera Caldera.

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    Skok, J. R.; Mustard, J. F.; Ehlmann, B. L.; Murchie, S. L.

    2011-12-01

    The caldera of the Syrtis Major volcanic complex shows evidence of a late-stage, chemically evolved eruption that emplaced a volcanic cone and an evolved dacitic lava flow. This cone and flow contain several light-toned deposits, spectrally defined, with the CRISM instrument, by a broad asymmetrical absorption centered at 2.21 μm that is characteristic of a Si-OH bond. Additional weak 1.4 and 1.9 μm OH- and H2O related absorption features were detected that combined with the 2.21 μm feature confirms the detection of hydrated silica (SiO2 nH2O). The deposits are expressed morphologically as low mounds in stereo HiRISE data that superpose and post-date the volcanic flows. This mineral detection and volcanic context is consistent with several formation mechanisms, notably volcanic outgassing leading to fumarole surface alteration or silica deposition in volcanically driven hot springs. Since current orbital observations do not allow conclusive determination of precise mechanism, we here focus on the hot spring silica depositional hypothesis and investigate what the current observations tell us about such a system. These deposits would occur as post-eruption volcanic heat-driven hydrothermal convection of ground and possibly magmatic waters. Convecting, heated water would dissolve the igneous minerals in the basalt that forms the majority of the caldera mobilizing significant silica. Silica saturated fluids that reach the surface cool and deposit amorphous silica as the silica solubility in the fluids decreases. The large size and mound building nature of individual deposits require a significant and sustained fluid source for deposition. That amorphous silica deposits were detected in several distinct regions illustrates the prevalence of this process in this volcanic complex. The largest deposit is located on the southern flank of the cone and forms a fan-shaped morphology as the material is sourced from a vent and flows downslope. Another small deposit was

  6. The confirmation of a work hypothesis: a new caldera in the center of the Mexican Volcanic Belt; La confirmacion de una hipotesis de trabajo: una nueva caldera en el centro del Cinturon Volcanico Mexicano

    Energy Technology Data Exchange (ETDEWEB)

    Anguita Virella, Francisco; Pal Verma, Surendra; Milan, Marcos; Garcia Cacho, Luis; Samaniego M, Daniel [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1991-12-31

    After synthesizing the most relevant aspects of the current volcanology and the genesis process of the collapse calderas, a process is described on the location and confirmation of a new caldera (the Mazahua) in the central part of the Mexican Volcanic Belt (MVB). [Espanol] Tras sintetizar los aspectos mas destacados de la vulcanologia actual y el proceso de genesis de las calderas de colapso, se describe el proceso de localizacion y confirmacion de una nueva caldera (la Mazahua) en la parte central del Cinturon Volcanico Mexicano (CVM).

  7. Seismic and gravity signature of the Ischia Island Caldera (Italy)

    Science.gov (United States)

    Capuano, P.; de Matteis, R.; Russo, G.

    2009-04-01

    The Campania (Italy) coasts are characterized by the presence of several volcanoes. The island of Ischia, located at the northwestern end of the Gulf of Naples, belongs to the Neapolitan Volcanic District together with Phlegrean Fields and Vesuvius, having all these Pleistocene volcanoes erupted in historical times, and it is characterized by diffuse hydrothermal phenomena The island represents the emergent part of a more extensive volcanic area developed mainly westward of the island, with underwater volcanoes aligned along regional fault patterns. The activity of Ischia volcano is testified by the occurrence of eruptions in historical times, the presence of intense hydrothermal phenomena, and by seismic activity (e.g. the 1883 Casamicciola earthquake). Ischia is populated by about 50,000 inhabitants increasing, mainly in the summer, due to thriving tourism business, partially due to its active volcanic state. Hazard assessment at active, densely populated volcanoes is critically based on knowledge of the volcanoes past behavior and the definition of its present state. As a contribution to the definition of the present state of the Ischia island volcano, we obtain a model of the shallow crust using geophysical observables through seismic tomography and 3D gravity inversion. In particular we use travel times collected during the Serapis experiment on the island and its surroundings and free air anomaly. A new 3D gravity inversion procedure has been developed to take better into account the shape and the effects of topography approximating it by a triangular mesh. Below each triangle, a sequence of triangular prisms is built, the uppermost prism having the upper face coincident with the triangle following the topography. The inversion is performed searching for a regularized solution using the minimum norm stabilizer. The main results inferable from the 3D seismic and gravity images are the definition of the caldera rims hypothesize by many authors along the

  8. Building and interpreting a database to understand recent caldera unrest from monitoring data

    Science.gov (United States)

    Di Lorenzo, Riccardo; Acocella, Valerio; Scandone, Roberto; Geshi, Nobuo

    2014-05-01

    Calderas are among the most spectacular, dangerous and active volcanoes on the Earth. Activation of seismicity, surface deformation and anomalous degassing are commonly observed at many calderas, denoting unrest. The unrest can be intermittent, lasting for months to years, or persistent, over decades to centuries. Although most caldera unrest episodes do not lead to an eruption, the possibility of an impending eruption warrants detailed monitoring and study. To better understand caldera unrest, we built a database from all available publications and reports on the recent unrest episodes at calderas in the world. We focused our attention on the unrest episodes which have occurred in the last 25 years, being complementary to Newhall and Dzurisin (1988). We considered the monitoring data from more than 45 unresting calderas, 35 of which characterized by eruptions. Attention has been given to seismicity, deformation and gas variations, along with their possible interaction. The database consists of an excel sheet containing the: (a) caldera descriptive parameters (caldera name, UTM coordinates, maximum and minimum diameter, area, date of last eruption, magma composition); (b) seismic data (width, maximum and minimum depth of area undergoing seismicity, frequency and duration and maximum magnitude; (c) geodetic data (location and width of deformed area, intensity and duration of the deformation); (d) geochemical data (location of anomalies, changes in maximum temperature, variations in chemical composition, duration of the anomaly, pH changes); (e) presence of eruptions and their characterization. The preliminary analysis of the database confirms that all eruptions are preceded by an unrest episode, but not all unrest episodes culminate in an eruption; this suggests that these indicators are a necessary condition to establish the state of unrest, which may anticipate an impending eruption; however, the indicators are not always adequate to determine the occurrence of

  9. Gravity Variations at a Dynamic Basaltic Caldera: Before and After the 2005 Eruption of Sierra Negra Volcano, Galapagos Islands

    Science.gov (United States)

    Geist, D.; Vigouroux, N.; Williams-Jones, G.; Chadwick, W.; Johnson, D.

    2007-12-01

    Sierra Negra volcano, an active basaltic volcano in the western Galapagos, last erupted in October 2005 following a period of accelerated uplift of the central caldera floor that started in April 2003. Deformation data indicate that a shallow (~ 2 km) sill underlies the caldera floor, and an intrusion rate of 64 x 106 m3/y for the 6 months prior to eruption was calculated from a continuous GPS network installed in 2002. Micro-gravity measurements were conducted in 2005, 2006, and 2007 at three stations in the center of the caldera and one station on the outer flank of the volcano and referenced to a base station on the NE rim of the caldera. From June 2005 to June 2006, residual gravity measured in the caldera increased by 1500 microgals at the center of the caldera to 184 microgals halfway to the northern edge of the caldera. This increase in residual gravity (height corrected) was accompanied by an uplift rate of ~ 212 cm/y until February 2006 after which the uplift rate decreased to 73 cm/y in 2006 and 44 cm/y in 2007. Similarly, from June 2006 to June 2007 gravity increased less dramaticaly than in 2005-2006 with an average increase of 11 microgals at the center of the caldera and 132 microgals at the more northern part of the caldera. Interestingly, the center of maximum gravity change shifted from the center of the caldera to the northern part sometime between June 2006 and June 2007. Gravity measurements on the outer rim of the caldera showed a 300 and a 200 microgal decrease from June 2005 to June 2006 and June 2006 to June 2007, respectively accompanied by low rates of inflation (1.8 cm/y). The coupling of gravity and deformation change supports the hypothesis of significant mass increase in the central-northern part of the caldera.

  10. The initiation and development of a caldera-forming Plinian eruption (172 ka Lower Pumice 2 eruption, Santorini, Greece)

    Science.gov (United States)

    Simmons, J. M.; Cas, R. A. F.; Druitt, T. H.; Carey, R. J.

    2017-07-01

    The rhyodacitic 172 ka Lower Pumice 2 (LP2) eruption terminated the first magmatic cycle at Santorini (Greece), producing a proximal caldera collapse, facilitated the ingress of water into the magmatic system, the development of widespread PDCs and the deposition of a caldera collapse, the enlargement of a pre-existing flooded caldera and the discharge of lithic-rich PDCs, depositing proximal < 9 m thick lithic lag breccias (LP2-D).

  11. Geochemical and geochronologic data from the Hall Creek caldera, Toiyabe Range, Nevada

    Science.gov (United States)

    Colgan, Joseph P.; Henry, Christopher D.

    2017-01-01

    The magmatic, tectonic, and topographic evolution of what is now the northern Great Basin remains controversial, notably the temporal and spatial relation between magmatism and extensional faulting. This controversy is exemplified in the northern Toiyabe Range of central Nevada, where previous geologic mapping suggested the presence of a caldera that sourced the late Eocene (34.0 mega-annum [Ma]) tuff of Hall Creek. This region was also inferred to be the locus of large-magnitude middle Tertiary extension (more than 100 percent strain) localized along the Bernd Canyon detachment fault, and to be the approximate location of a middle Tertiary paleodivide that separated east and west-draining paleovalleys. Geologic mapping, 40Ar/39Ar dating, and geochemical analyses document the geologic history and extent of the Hall Creek caldera, define the regional paleotopography at the time it formed, and clarify the timing and kinematics of post-caldera extensional faulting. During and after late Eocene volcanism, the northern Toiyabe Range was characterized by an east-west trending ridge in the area of present-day Mount Callaghan, probably localized along a Mesozoic anticline. Andesite lava flows erupted around 35–34 Ma ponded hundreds of meters thick in the erosional low areas surrounding this structural high, particularly in the Simpson Park Mountains. The Hall Creek caldera formed ca. 34.0 Ma during eruption of the approximately 400 cubic kilometers (km3) tuff of Hall Creek, a moderately crystal-rich rhyolite (71–77 percent SiO2) ash-flow tuff. Caldera collapse was piston-like with an intact floor block, and the caldera filled with thick (approximately 2,600 meters) intracaldera tuff and interbedded breccia lenses shed from the caldera walls. The most extensive exposed megabreccia deposits are concentrated on or close to the caldera floor in the southwestern part of the caldera. Both silicic and intermediate post-caldera lavas were locally erupted within 400 thousand

  12. PANEGÍRICO A JUAN ANTONIO SAMARANCH: Juan Antonio Samaranch Torelló: Una obra inabarcable

    Directory of Open Access Journals (Sweden)

    Alejandro Blanco Bravo

    2010-06-01

    Full Text Available Me gustaría abstraerme de mis sentimientos personales para poder describir en estas pocas líneas la figura del tristemente desaparecido Juan Antonio Samaranch Torrelló. Pero mi amistad y, sobre todo, mi admiración por él me lo impide. Necesitaría más espacio, más tiempo y más palabras para expresar mis sentimientos. Toda su vida la dedicó al deporte y a su gestión. Ha muerto con 89 años y lo hizo sin concederse un respiro, sin renunciar un instante a vivir el deporte desde todas sus aristas. Seguro que en sus últimos instantes pensó que la vida se le había quedado corta, que le faltó tiempo para seguir trabajando. Su obra es inabarcable. Fue un hombre de una inteligencia superior, que tuvo la paciencia y el deseo ferviente de llevar de la mano a todo un universo deportivo. El deporte era su pasión y el trabajo su devoción.

  13. Stress field control during large caldera-forming eruptions

    Science.gov (United States)

    Costa, Antonio; Marti, Joan

    2016-10-01

    Crustal stress field can have a significant influence on the way magma is channelled through the crust and erupted explosively at the surface. Large Caldera Forming Eruptions (LCFEs) can erupt hundreds to thousands of cubic kilometres of magma in a relatively short time along fissures under the control of a far-field extensional stress. The associated eruption intensities are estimated in the range 109 - 1011 kg/s. We analyse syn-eruptive dynamics of LCFEs, by simulating numerically explosive flow of magma through a shallow dyke conduit connected to a magma chamber that in turn is fed by a deeper magma reservoir, both under the action of an extensional far-field stress. Results indicate that huge amounts of high viscosity silicic magma can be erupted over timescales of a few to several hours. Our study provides answers to outstanding questions relating to the intensity and duration of catastrophic volcanic eruptions in the past. In addition, it presents far-reaching implications for the understanding of dynamics and intensity of large-magnitude volcanic eruptions on Earth and to highlight the necessity of a future research to advance our knowledge of these rare catastrophic events.

  14. Gravity modelling of the Ramadas Caldera (Argentinean Puna, central Andes)

    Energy Technology Data Exchange (ETDEWEB)

    Casas, A. [Barcelona Univ. (Spain). Facultad de Geologia; Hernandez, E.; Marti, J. [Consejo Superior de Investigaciones Cientificas, Barcelona (Spain). Inst. de Ciencias de la Terra Jaume Almera; Petrinovic, I. [Universidad Nacional de Salta (Argentina)

    1995-12-31

    In order to identify and characterize the event area of abundant Upper Miocene proximal rhyolitic pyroclastic deposits and extrusive domes which concentrate in the Ramadas area, near Sant`Antonio de los Cobres (Salta) at the Puna Altiplano (Central Andes), a detailed gravity survey has been carried out. Regional Bouguer gravity data were augmented with new 173 gravity observations measured sufficiently close-spaced to resolve the short wavelength produced by the structure of interest. Besides, the geophysical survey was done in conjunction with geologic and geochemical studies which were critically important to our interpretation. After the separation of the regional trend, the residual anomaly map displays a circular gravity low reaching-80 m Gal centered over scarce outcrops of rhyolitic and pyroclastic. This gravity low is interpreted as produced by block subsidence along ring fractures during eruption and/or deflation of the chamber. As the accumulation of thick, low density rock types in the zone of collapse is responsible of the prominent negative gravity anomalies, them has been used to estimated the thickness of caldera infill. (author). 8 refs., 4 figs

  15. Volcanic calderas delineate biogeographic provinces among Yellowstone thermophiles.

    Science.gov (United States)

    Takacs-Vesbach, Cristina; Mitchell, Kendra; Jackson-Weaver, Olan; Reysenbach, Anna-Louise

    2008-07-01

    It has been suggested that the distribution of microorganisms should be cosmopolitan because of their enormous capacity for dispersal. However, recent studies have revealed that geographically isolated microbial populations do exist. Geographic distance as a barrier to dispersal is most often invoked to explain these distributions. Here we show that unique and diverse sequences of the bacterial genus Sulfurihydrogenibium exist in Yellowstone thermal springs, indicating that these sites are geographically isolated. Although there was no correlation with geographic distance or the associated geochemistry of the springs, there was a strong historical signal. We found that the Yellowstone calderas, remnants of prehistoric volcanic eruptions, delineate biogeographical provinces for the Sulfurihydrogenibium within Yellowstone (chi(2): 9.7, P = 0.002). The pattern of distribution that we have detected suggests that major geological events in the past 2 million years explain more of the variation in sequence diversity in this system than do contemporary factors such as habitat or geographic distance. These findings highlight the importance of historical legacies in determining contemporary microbial distributions and suggest that the same factors that determine the biogeography of macroorganisms are also evident among bacteria.

  16. Tourism Development Based on Geopark in Bakkara Caldera Toba, Indonesia

    Science.gov (United States)

    Ginting, N.; Vinky Rahman, N.; Sembiring, G.

    2017-03-01

    Bakkara Caldera Toba is an outstanding product of natural phenomena of Toba Supervolcano which has fascinating nature and culture. Bakkara has a great potential to develop world tourism further. It requires a model of sustainable planning Geopark to develop Bakkara. This sustainable concept helps to improve the local community and tourist’s quality of life and also still maintain the quality of the environment. through field observation and depth interview. The Collected data with a triangulation method. Development tourism destination such as attractions and environment; facilities and services; accessibility; image; and price to consume. It associated based on Geopark aspects there are; geological heritage; geo-conservation activities; sustainable tourism activities; educational; activities; community involvement products; strong management structure; and secure basis, infrastructure, and activities. The results of this study indicate that the Bakkara has the potential to become a tourist destination by applying the concept of Geotourism which accentuate its natural side, by optimizing the management of its destination attractions, its facilities and services, and its accessibilities.

  17. Stress field control during large caldera-forming eruptions

    Directory of Open Access Journals (Sweden)

    Antonio Costa

    2016-10-01

    Full Text Available Crustal stress field can have a significant influence on the way magma is channelled through the crust and erupted explosively at the surface. Large Caldera Forming Eruptions (LCFEs can erupt hundreds to thousands of cubic kilometres of magma in a relatively short time along fissures under the control of a far-field extensional stress. The associated eruption intensities are estimated in the range 109 - 1011 kg/s. We analyse syn-eruptive dynamics of LCFEs, by simulating numerically explosive flow of magma through a shallow dyke conduit connected to a magma chamber that in turn is fed by a deeper magma reservoir, both under the action of an extensional far-field stress. Results indicate that huge amounts of high viscosity silicic magma can be erupted over timescales of a few to several hours. Our study provides answers to outstanding questions relating to the intensity and duration of catastrophic volcanic eruptions in the past. In addition, it presents far-reaching implications for the understanding of dynamics and intensity of large-magnitude volcanic eruptions on Earth and to highlight the necessity of a future research to advance our knowledge of these rare catastrophic events.

  18. Qualitative and Quantitative Assessment of Naturals Hazards in the Caldera of Mount Bambouto (West Cameroon)

    Science.gov (United States)

    Zangmo Tefogoum, G.; Kagou Dongmo, A.; Nkouathio, D. G.; Wandji, P.

    2009-04-01

    Mount Bambouto is polygenic stratovolcano of the Cameroon Volcanic Line, build between 21 Ma and 4,5Ma (Nkouathio et al., 2008). It is situated at about 200 km NE of mount Cameroon, at 09°55' and 10°15' East and, 05°25' and 05°50' Nord. This volcano covers an area of 500 Km2 and culminates at 2740 m at Meletan hill and bears a collapse caldera (13 x 8 km). Fissural, extrusive and explosive dynamism are responsible of the construction in three main stages this volcano including the edification of a sommital large rim caldera. Mount Bambouto structure gives rise to different natural hazards, of volcanological origin and meteorological origin. In the past time, landslides, floodings, firebush, blocks collapse took place in this area with catastrophic impact on the population. New research program had been carried out in the caldera concerning qualitative and quantitative evaluation of natural risks and catastrophes. The main factors of instability are rain, structure of the basement, slopes, lithology and anthropic activities; particularly, the occurrence of exceptional rainfall due to global change are relevant; this gives opportunity to draw landslides hazards zonation map of the Bambouto caldera which is the main risk in this area. We evaluate the financial potential of the caldera base on the average income of breeding, farming, school fees and the cost of houses and equipments for each family. The method of calculation revealed that, the yearly economy of the mounts Bambouto caldera represents about 2 billions FCFA. Some recommendations have been made in order to prevent and reduced the potential losses and the number of victims in particular by better land use planning. These help us to estimate the importance of destruction of the environment and biodiversity in case of catastrophes. We conclude that in the Bambouto caldera there is moderate to high probability that destructive phenomena due to landslides occurs within the upcoming years with enormous

  19. The Tala Tuff, La Primavera caldera Mexico. Pre-eruptive conditions and magma processes before eruption

    Science.gov (United States)

    Sosa-Ceballos, G.

    2015-12-01

    La Primavera caldera, Jalisco Mexico, is a Pleistocenic volcanic structure formed by dome complexes and multiple pyroclastic flows and fall deposits. It is located at the intersection of the Chapala, Colima, and Tepic grabens in western Mexico. The first volcanic activity associated to La Primavera started ~0.1 Ma with the emission of pre-caldera lavas. The caldera collapse occurred 95 ka and is associated to the eruption of ~20 km3of pumice flows known as the Tala tuff (Mahood 1980). The border of the caldera was replaced by a series of domes dated in 75-30 ky, which partially filled the inner depression of the caldera with pyroclastic flows and falls. For more than a decade the Federal Commission of Electricity in Mexico (CFE) has prospected and evaluated the geothermal potential of the Cerritos Colorados project at La Primavera caldera. In order to better understand the plumbing system that tapped the Tala tuff and to investigate its relation with the potential geothermal field at La Primavera we performed a series of hydrothermal experiments and studied melt inclusions hosted in quartz phenocrysts by Fourier Infra red stectroscopy (FTIR). Although some post caldera products at La Primavera contain fayalite and quartz (suggesting QFM conditions) the Tala tuff does not contain fayalite and we ran experiments under NNO conditions. The absence of titanomagnetite does not allowed us to calculate pre-eruptive temperature. However, the stability of quartz and plagioclase, which are natural phases, suggest that temperature should be less than 750 °C at a pressure of 200 MPa. The analyses of H2O and CO2 dissolved in melt inclusions yielded concentrations of 2-5 wt.% and 50-100 ppm respectively. This data confirm that the pre-eruptive pressure of the Tala tuff is ~200 MPa and in addition to major elements compositions suggest that the Tala tuff is either, compositionally zoned or mixed with other magma just prior to eruption.

  20. Stratigraphy of Pyroclastic Deposits of EL Aguajito Caldera, Baja California Sur, MÉXICO

    Science.gov (United States)

    Osorio Ocampo, L. S.; Macias, J. L.; García Sánchez, L.; Pola, A.; Saucedo, R.; Sánchez, J. M.; Avellán, D. R.; Cardona, S.; Reyes-Agustín, G.; Arce, J. L.

    2015-12-01

    El Aguajito caldera is located in the State of Baja California Sur, it comprises an area of 450 km2 and sits within the Santa Rosalía Basin which is controlled by NE-SW extensional structures and the NW-SE Cimarron Fault that transects the caldera structure. The oldest rocks are ~90 Ma granodiorites covered by an Oligocene-Miocene volcano-sedimentary sequence, the Miocene Santa Lucia Formation and La Esperanza basalt. Pliocene volcanism is represented by La Reforma caldera, El Aguajito caldera, and the Tres Vírgenes Volcanic complex. This study focuses on the cartography and stratigraphy of area in order to understand the evolution of the volcanic system. The stratigraphy from base to top consists of a series of shallow marine sediments (fossiliferous sandstones) covered by a thick sequence of ignimbrites and pyroclastic flows interbedded with volcaniclastic deposits (Gloria and El Infierno Formations). On top of these deposits is El Aguajito caldera, it consists of a 2 m thick pumice fallout followed by an ignimbrite with three transitional lithofacies: a ≤30-m thick light-pink pyroclastic flow enriched in pumice at the base that gradually becomes enrich in lithics towards the top with the occurrence of degasing pipes. On top rests a 15 m-thick light-purple ignimbrite slightly welded with fiammes and a sequence of pumiceous pyroclastic flows and fallouts. These deposits have been associate to the caldera formation with a collapse diameter of ~8 km marked by rhyolitic domes exposed along a ring collapse crowned the sequence as well as NW-SE aligned rhyolitic domes parallel to the seashore. This cartography allowed to present a preliminary new geological map with four stratigraphic units recognized so far, that were emplaced under subaerial conditions beginning with a Plinian column followed by the emplacement of El Aguajito ignimbrite with its subsequent caldera collapse and finally the extrusion of resurgent domes.

  1. MGS-TES thermal inertia study of the Arsia Mons Caldera

    Science.gov (United States)

    Cushing, G.E.; Titus, T.N.

    2008-01-01

    Temperatures of the Arsia Mons caldera floor and two nearby control areas were obtained by the Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES). These observations revealed that the Arsia Mons caldera floor exhibits thermal behavior different from the surrounding Tharsis region when compared with thermal models. Our technique compares modeled and observed data to determine best fit values of thermal inertia, layer depth, and albedo. Best fit modeled values are accurate in the two control regions, but those in the Arsia Mons' caldera are consistently either up to 15 K warmer than afternoon observations, or have albedo values that are more than two standard deviations higher than the observed mean. Models of both homogeneous and layered (such as dust over bedrock) cases were compared, with layered-cases indicating a surface layer at least thick enough to insulate itself from diurnal effects of an underlying substrate material. Because best fit models of the caldera floor poorly match observations, it is likely that the caldera floor experiences some physical process not incorporated into our thermal model. Even on Mars, Arsia Mons is an extreme environment where CO2 condenses upon the caldera floor every night, diurnal temperatures range each day by a factor of nearly 2, and annual average atmospheric pressure is only around one millibar. Here, we explore several possibilities that may explain the poor modeled fits to caldera floor and conclude that temperature dependent thermal conductivity may cause thermal inertia to vary diurnally, and this effect may be exaggerated by presence of water-ice clouds, which occur frequently above Arsia Mons. Copyright 2008 by the American Geophysical Union.

  2. Un contrato inédito de Juan de Juanes. El retablo de la Cofradía de la Sangre de Cristo de Valencia (1539

    Directory of Open Access Journals (Sweden)

    Gómez-Ferrer, Mercedes

    2012-03-01

    Full Text Available This article is based on an unpublished contract signed in 1539 by Vicente and Juan Macip for an altarpiece for the Valencian Brotherhood of the Blood of Christ. The agreement stipulates that Juan, later known as Juan de Juanes, had to paint the scenes. Thus the document reinforces the hypothesis that Juan Macip was the most important painter in the Macip workshop during the 1530’s. It also fills a documental void in between the completion of the Silversmith’s Guild altarpiece (1534-1539 and the contract for the Fuente la Higuera altarpiece (1548. This study also verifies the popularity of the iconography of the seven sheddings of the Blood of Christ and processions of disciplinants.

    Se presenta un contrato inédito suscrito por la Cofradía de la Sangre de Cristo de la ciudad de Valencia con Vicente y Juan Macip en 1539. En él se especifica que sea pintado por Juan, más conocido con posterioridad como Juan de Juanes. Se refuerza la hipótesis que permite concretar a Juan Macip como el pintor más importante del taller de los Macip durante la década de los 30, al tiempo que se llena un vacío documental entre la entrega del retablo del gremio de plateros (1534-1539 y la contratación del retablo de Fuente la Higuera (1548. Se constata igualmente la popularidad de la iconografía de los siete derramamientos de la Sangre de Cristo y la procesión de los disciplinantes.

  3. Juan Gabriel and audience interpretation. cultural impressions of effeminacy and sexuality in Mexico.

    Science.gov (United States)

    Sowards, S K

    2000-01-01

    Juan Gabriel's purported effeminacy and sexuality have made him a controversial subject in Mexico, but still loved by fans. Juan Gabriel, by trying to gain acceptance into Mexican society, has become part of a hybrid culture, between the feminine/masculine and homosexual/bisexual/heterosexual groups. This study focuses on interviews with 20 participants who discuss Juan Gabriel's popularity and sexuality. The findings of the study indicate that Juan Gabriel may be considered by his fans to be effeminate, and consequently homosexual. Even though homophobia is widespread in Mexico, Juan Gabriel's fans tend to ignore or exoticize his sexuality, thus affording his success. It is also possible that Juan Gabriel, consciously or not, uses his controversial sexuality as a way to generate popular interest.

  4. Entrevista a Juan José Aquerreta (Arte y Parte)

    OpenAIRE

    Latorre-Izquierdo, J. (Jorge)

    2009-01-01

    Esta entrevista de Jorge Latorre al artista Juan José Aquerreta fue publicada en Arte y Parte con ocasión de una exposición de obra reciente del artista que tuvo lugar en la galería Marlborough de Madrid (Orfila, 1) desde el 25 de marzo de 2009. Un año antes había visto la luz el catálogo de toda su obra, publicado por el Gobierno de Navarra, y que incluye textos de Francisco Calvo Serraller, Enrique Andrés Ruíz o el propio Aquerreta, además de una larga entrevista que le hizo Juan Manuel Bon...

  5. Il mestiere di tradurre 5: Juan Carlos Reche

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    Juan Carlos Reche

    2015-07-01

    Full Text Available En la última década el traductor y poeta Juan Carlos Reche (Córdoba, 1976 ha dado a conocer algunos de los textos poéticos más relevantes y complejos de la literatura italiana de los últimos tiempos. Galardonado en 2013 con el Premio Nazionale per la Traduzione concedido por el Ministerio Italiano de Cultura, es además autor de poemarios propios como El dolor y la velocidad (Ed. Renacimiento, Sevilla, 1999 o Carrera del fruto (Ed. Pre-Textos, Valencia, 2006. Su doble condicion de poeta y traductor, el riesgo de enfrentarse a autores como Maurizio Cucchi, Giorgio Caproni o Giovanni Raboni, y la reciente aparición de la revista Años diez, que dirije junto al poeta Abraham Gragera, nos ha llevado a plantearle algunas preguntas sobre su labor en ambos campos. Entrevista de Juan Pérez Andrés.

  6. Oral anatomy in the sixteenth century: Juan Valverde de Amusco.

    Science.gov (United States)

    López-Valverde, A; Gómez de Diego, R; De Vicente, J

    2013-08-01

    In 1554 Juan Valverde de Amusco, a Spanish anatomist, wrote the History of the composition of the human body, a complete anatomical treatise that took as its model the Vesalius school of thought (La fábrica of Vesalius). Considered one of the most complete anatomical treatises of the Renaissance and one of the most widely read books of the sixteenth century, it was translated into four languages in its day. The first chapter, devoted to bones, provides a meticulously detailed analysis of the bones of the facial structures and of the teeth, their supporting structures, vascularisation and innervation. Juan Valverde de Amusco even describes techniques for reducing mandibular luxations. Even with the imprecise observations typical of the time the treatise must be considered an exceptional document.

  7. San Juan implements one-man survey system

    Energy Technology Data Exchange (ETDEWEB)

    Andrae, S. (San Juan Coal Co., Waterflow, NM (United States))

    1994-07-01

    Describes the one-man survey system which has been implemented at the San Juan surface mine in northwestern New Mexico. The Geodimeter System 4000, produced by Geotronics of Sweden, consists of a tripod-mounted electronic total station and a range rod-mounted remote positioning unit (RPU). A radio link between the tripod-mounted total station and the RPU enables one person to control the instrument and collect data. At San Juan the system has been used to survey overburden removal and mining. Only in cases where the pits become very long, and control cannot be set in the pit, is a two-person crew used. The system is useful for surveys of compliance projects and lends itself well to regrading work. 3 photos.

  8. 33 CFR 110.74c - Bahia de San Juan, PR.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Bahia de San Juan, PR. 110.74c Section 110.74c Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Special Anchorage Areas § 110.74c Bahia de San Juan, PR. The waters of San Antonio Channel, Bahia de San Juan, eastward...

  9. Magma Storage, Recharge and the Caldera Cycle at Rabaul, Papua New Guinea

    Science.gov (United States)

    Fabbro, G.; Bouvet de Maisonneuve, C.; Sindang, M.

    2015-12-01

    Many calderas have a history of repeated caldera-forming eruptions, interspersed with periods of more minor activity. Rabaul, for instance, has had at least 11 ignimbrite-forming eruptions over the last 200 ky. The most recent of these was the '1400 BP' eruption, which led to caldera collapse. Since then, there has been multiple smaller eruptions, including the ongoing activity from Tavurvur and Vulcan. An important question facing volcanology today is what controls the size of eruptions at calderas such as Rabaul.Detailed stratigraphic sampling of the 1400BP eruption reveals that prior to eruption, the magma reservoir below Rabaul contained a well-mixed dacite with whole-rock SiO2 contents of 65.0-66.4 wt%. The dacite contains a single phenocryst assemblage of plag (An44-52), cpx (En43-46Fs13-15Wo40-41), opx (En69-71Fs25-28Wo3) and magnetite, along with minor apatite. The homogeneity of the dacite is underscored by the narrow range of compositions of both the matrix glass and the melt inclusions (67.8-69.0 wt% SiO2). The only exception to this is at the top of the ignimbrite, representing some of the last magma to have been withdrawn. Dispersed throughout the dacitic pumices are darker, more mafic blebs. Streaks of mingled magma with a range of SiO2 contents, down to 59.9 wt% SiO2 are also found in the pumice, suggesting that a mafic recharge magma was intruded into the base of the reservoir shortly before eruption. High TiO2 contents rule out the direct involvement of basalt, and instead imply the magma that intruded into the reservoir was an andesite with at least 56 wt% SiO2. Phenocrysts related to this recharge magma are rare, and the crystals found in the dark blebs are identical in composition to those found in the dacite, indicating that the recharge was aphyric. The present-day, post-caldera recharge magma is different to the pre-1400 BP recharge magma: it is basaltic. This suggests that the plumbing system of Rabaul is different during the pre-caldera and

  10. Azorín y Don Juan (1922): vidas paralelas

    OpenAIRE

    Pérez-Bustamante Mourier, Ana Sofía

    1998-01-01

    Análisis de la novela "Don Juan" (1922), de José Martínez Ruiz (a) Azorín, dentro de la tradición del Tenorio arrepentido y redimido. En este caso la ejemplaridad cristiana se une a la perspectiva regeneracionista, y el tema del arrepentimiento se desarrolla a través de una estética impresionista y simbolista.

  11. Teaching and Communicating Astronomy at Rey Juan Carlos University

    Science.gov (United States)

    Hernán-Obispo, M.; Serrano, A.; Aguirre, J.; Martín, P. San

    We present our activities of popularization of Astronomy at Rey Juan Carlos University in Madrid, especially our 30-h workshop for people older than 55 (University for the Elderly) held since the academic year 2002/2003. Our course aims to introduce the basic topics on Astronomy to a group of motivated students who, in most cases, were not able to complete their education in their youth due to the historical environment of Spain in the middle of the twentieth century.

  12. Gravity field at unrest caldera: an application to Campi Flegrei area

    Science.gov (United States)

    Russo, Guido; Capuano, Paolo

    2010-05-01

    Campi Flegrei is a well known volcanic caldera which is characterized by a slow sequence of uplifts and downlifts (bradyseism) superimposed to a sporadic but remarkable explosive activity. Last eruption occurred in 1538, while the most recent uplift episodes (1970-72 and 1982-84) produced about 3 m of cumulative displacement at the town of Pozzuoli. This behavior and the proximity of the densely urbanized town of Naples increases the volcanic hazard of the area. The knowledge of the structural characteristics of the caldera is important to better understand and interpret measured data as well as the past volcanic history. In this frame, gravity data inversion can provide useful information. We collected and inverted about 1500 gravity data covering Campi Flegrei caldera and Ischia island, which is the other main volcanic center of the area, and was characterized in the past by several explosive eruptions (the last one in 1301), and presently by hydrothermal activity. The 3D inversion method was developed by us to deal with scattered data and the presence of topography, and is based on Thichonov regularization theory. As to Campi Flegrei caldera, its shape and bordering structure is clearly singled out in agreement with seismic tomography results. Less marked borders are also present at shallow depth on the NE part of the area. As to Ischia island, our results show the presence of a central high density block and the border of a caldera roughly coinciding with the coastline of the island.

  13. Long Valley caldera and the UCERF depiction of Sierra Nevada range-front faults

    Science.gov (United States)

    Hill, David P.; Montgomery-Brown, Emily K.

    2015-01-01

    Long Valley caldera lies within a left-stepping offset in the north-northwest-striking Sierra Nevada range-front normal faults with the Hilton Creek fault to the south and Hartley Springs fault to the north. Both Uniform California Earthquake Rupture Forecast (UCERF) 2 and its update, UCERF3, depict slip on these major range-front normal faults as extending well into the caldera, with significant normal slip on overlapping, subparallel segments separated by ∼10  km. This depiction is countered by (1) geologic evidence that normal faulting within the caldera consists of a series of graben structures associated with postcaldera magmatism (intrusion and tumescence) and not systematic down-to-the-east displacements consistent with distributed range-front faulting and (2) the lack of kinematic evidence for an evolving, postcaldera relay ramp structure between overlapping strands of the two range-front normal faults. The modifications to the UCERF depiction described here reduce the predicted shaking intensity within the caldera, and they are in accord with the tectonic influence that underlapped offset range-front faults have on seismicity patterns within the caldera associated with ongoing volcanic unrest.

  14. HISTORICAL ECOTOXICOLOGICALASSESSMENT OF SAN JUAN ECOSYSTEM, SANTIAGO DE CUBA, CUBA

    Directory of Open Access Journals (Sweden)

    Argota, George

    2013-07-01

    Full Text Available Currently, the environmental decision-making related to watershed preservation is oriented under the precepts of an historical environmental assessment. The objective of this research was to conduct a historical ecotoxicological assessment of the San Juan de Santiago de Cuba ecosystem. This was considered a systematic environmental monitoring which ran from 2010 to 2013, made q?uarterly. Physicochemical parameters such as electrical conductivity, total alkalinity, total hardness, pH, total solids, dissolved oxygen, biochemical oxygen demand and chemical oxygen demand were determined. All parameters of environmental risk prediction were performed using the GECOTOX program. The concentrations of Cu, Zn, Pb and Cd on three target organs (brain, gills and liver in the biomonitor adult Gambusia punctata (Poecilidae were analyzed. In this species, the effect of total protein and enzymatic activity of acetylcholinesterase as biomarkers were evaluated. In general, the parameters were outside the values set used by the Cuban quality standards. The GECOTOX program said that the waters of the San Juan ecosystem presented a high rate of risk. The highest concentrations of metals were determined in the gills, liver and brain, respectively. Biomarker values w? ere high, being higher for females. Finally, it was concluded that from one year to another all responses were ascending; thus, the San Juan ecosystem presented ecotoxicological effects in time.

  15. La encrucijada en Pedro Páramo de Juan Rulfo / The Crossroads in Pedro Páramo by Juan Rulfo

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    Lilia Leticia García-Peña

    2015-08-01

    Full Text Available La obra de Juan Rulfo sintetiza la realidad del campo mexicano, captura el contorno de las identidades individuales y de la estructura de la interacción social del mundo que tanto le preocupó y del que es intérprete indiscutible, pero también supo convertir en materia narrativa aquellas atmósferas que rebasan el contexto mexicano y social. En este trabajo abordaré el tema de la encrucijada en el imaginario simbólico de Pedro Páramo (1955 como expresión de una reelaboración del mito de Hermes, analizaré cómo la novela de Juan Rulfo muestra estos ecos herméticos y qué sentido estético y sociocultural tiene esta resonancia mítica.

  16. Caldera of Godean, Sleman, Yogyakarta: A Volcanic Geomorphology Review

    Directory of Open Access Journals (Sweden)

    Hill Gendoet Hartono

    2017-07-01

    Full Text Available Godean hills is located approximately 10 km westward from the Yogyakarta City. The landscape of Godean hills and plains is affected by various factors, such as lithology, geological structure, and sub-aerial process. The purpose of this study was to reveal the landscape of Godean. The method consisted of field study, morphological variables assessment, rock sampling, and laboratory analysis. The results of field mapping indicated that the landscape of Godean  is an isolated hill with a steep slope of >40° and an elevation of +231 m a.s.l, passed by the rivers flows from northeast to southwest that disembogue into the west part of Kulon Progo. The morphologhy of Godean hills varies including G. (Gunung/Mountain So (+173 m amsl, G. Gede (+218 m a.s.l, G. Wungkal (+187 m a.s.l, G. Butak (+154 m a.s.l, and G. Berjo ( + 175 m a.s.l, dominated by the lithology of igneous rock, which is composed of porphyry andesite-microdiorite, pumice lapilli, and quartz rich lapilli-tuff. In addition, most of the igneous rocks have weathered and have been altered to clays, while the deposition from Merapi volcano formed a landscape with an altitude between +100–+150 m a.s.l surrounding Godean hills. Sentolo Formation was found in Kembang, Bantul, which is located approximately ±5km in the south of the study area N93ºE/12º,  while the distribution in the southwest and northeast relatively covers the Godean hills in curve shape. The results of the analysis provide information related with Godean landscape that it is the remains of the volcanic caldera, with various igneous rock types and volcaniclastics deposits, as well as endured the occurrences of hydrothermal alteration and mineralization. Further geophysical research is required to determine the configuration of igneous rocks under the earth's surface.

  17. Aprendizajes del Accidente de San Juan Ixhuatepec-México Learning from the Accident in San Juan Ixhuatepec-Mexico

    Directory of Open Access Journals (Sweden)

    Antioco López-Molina

    2012-01-01

    Full Text Available El índice Dow de fuego y explosión y la metodología del análisis cuantitativo del riesgo son aplicados para analizar uno de los accidentes más desafortunados en la historia mexicana: la explosión de tanques de almacenamiento de gas en la planta de San Juan Ixhuatepec en México. Estimaciones adicionales de la sobrepresión y radiación térmica producida durante el siniestro son llevadas a cabo para explicar el efecto dominó producido como consecuencia del incidente. Estas estimaciones dan evidencia de que las instalaciones en la planta de San Juan Ixhuatepec tenían un nivel de riesgo moderado lo cual se contrapone a la percepción de la sociedad en relación al riesgo de la compañía Pemex, propietaria de la planta. Este trabajo concluye que el accidente fue principalmente debido a errores humanos, así como a la pésima ubicación de la planta.The Dow fire and explosion index and the quantitative risk assessment methodology are applied to analyze one of the most unfortunate accidents in Mexican history: the explosion of gas storage tanks at the San Juan Ixhuatepec plant in Mexico. Additional calculations of over-pressure and thermal radiation are carried out to further explain the domino effect produced as a consequence of the accident. The results give evidence that facilities in San Juan Ixhuatepec had a moderate risk level which is in disagreement with people’s perception of the Pemex company, proprietary of the plant. This study concludes that the accident was mainly due to human error, as well as the inappropriate location of the plant.

  18. Characterizing Volcanic Processes using Near-bottom, High Resolution Magnetic Mapping of the Caldera and Inner Crater of the Kick'em Jenny Submarine Volcano

    Science.gov (United States)

    Ruchala, T. L.; Chen, M.; Tominaga, M.; Carey, S.

    2016-12-01

    Kick'em Jenny (KEJ) is an active submarine volcano located in the Lesser Antilles subduction zone, 7.5 km north of the Caribbean island Grenada. KEJ, known as one of the most explosive volcanoes in Caribbean, erupted 12 times since 1939 with recent eruptions in 2001 and possibly in 2015. Multiple generations of submarine landslides and canyons have been observed in which some of them can be attributed to past eruptions. The structure of KEJ can be characterized as a 1300 m high conical profile with its summit crater located around 180 m in depth. Active hydrothermal venting and dominantly CO2 composition gas seepage take place inside this 250m diameter crater, with the most activity occurring primarily within a small ( 70 x 110 m) depression zone (inner crater). In order to characterize the subsurface structure and decipher the processes of this volcanic system, the Nautilus NA054 expedition in 2014 deployed the underwater Remotely Operated Vehicle (ROV) Hercules to conduct near-bottom geological observations and magnetometry surveys transecting KEJ's caldera. Raw magnetic data was corrected for vehicle induced magnetic noise, then merged with ROV to ship navigation at 1 HZ. To extract crustal magnetic signatures, the reduced magnetic data was further corrected for external variations such as the International Geomagnetic Reference Field and diurnal variations using data from the nearby San Juan Observatory. We produced a preliminary magnetic anomaly map of KEJ's caldera for subsequent inversion and forward modeling to delineate in situ magnetic source distribution in understanding volcanic processes. We integrated the magnetic characterization of the KEJ craters with shipboard multibeam, ROV visual descriptions, and photomosaics. Initial observations show the distribution of short wavelength scale highly magnetized source centered at the north western part of the inner crater. Although locations of gas seeps are ubiquitous over the inner crater area along ROV

  19. La construcción de un mito : fortuna crítica de Juan de Juanes en los siglos XVI y XVII

    Directory of Open Access Journals (Sweden)

    Miguel Falomir Faus

    1999-01-01

    Full Text Available Este artículo pretende analizar los inicios de la fortuna crítica de Juan de Juanes en los siglos XVI y XVII. La «leyenda» de Juanes se asentó en su triple condición de gloria local, pintor ejemplar y artista piadoso, y quienes la forjaron, de Escolano a Vicente Vitoria pasando por Pacheco o Jusepe Martínez, no dudaron en potenciar, e incluso distorsionar, aquellas facetas de la personalidad de Juanes afines a sus intereses particulares.This article seeks to analyze the origins of the historiographical treatment of Juan de Juanes in the sixteenth and seventeenth centuries. The «myth» of Juanes was posited on three aspects: as exemplary and illustrious citizen, model forpainters, and pious artist. Those who forged this image of the artist, from Escolano to Vicente Vitoria and passing by Pacheco or Jusepe Martínez, did not doubt in emphasizing and even distorting those aspects of his personality and life that affirmed their individual interests.

  20. Hydrologic data from wells at or in the vicinity of the San Juan coal mine, San Juan County, New Mexico

    Science.gov (United States)

    Stewart, Anne M.; Thomas, Nicole

    2015-01-01

    In 2010, in cooperation with the Mining and Minerals Division (MMD) of the State of New Mexico Energy, Minerals and Natural Resources Department, the U.S. Geological Survey (USGS) initiated a 4-year assessment of hydrologic conditions at the San Juan coal mine (SJCM), located about 14 miles west-northwest of the city of Farmington, San Juan County, New Mexico. The mine produces coal for power generation at the adjacent San Juan Generating Station (SJGS) and stores coal-combustion byproducts from the SJGS in mined-out surface-mining pits. The purpose of the hydrologic assessment is to identify groundwater flow paths away from SJCM coal-combustion-byproduct storage sites that might allow metals that may be leached from coal-combustion byproducts to eventually reach wells or streams after regional dewatering ceases and groundwater recovers to predevelopment levels. The hydrologic assessment, undertaken between 2010 and 2013, included compilation of existing data. The purpose of this report is to present data that were acquired and compiled by the USGS for the SJCM hydrologic assessment.

  1. The 2014-2015 slow collapse of the Bárðarbunga caldera, Iceland

    Science.gov (United States)

    Tumi Gudmundsson, Magnus; Jónsdóttir, Kristín; Roberts, Matthew; Ófeigsson, Benedikt G.; Högnadóttir, Thórdís; Magnússon, Eyjólfur; Jarosch, Alexander H.; Pálsson, Finnur; Einarsson, Páll; Sigmundsson, Freysteinn; Drouin, Vincent; Hjörleifsdóttir, Vala; Reynolds, Hannah I.; Dürig, Tobias; Vogfjörd, Kristín; Hensch, Martin; Munoz-Cobo Belart, Joaquin; Oddsson, Björn

    2015-04-01

    The Bárðarbunga caldera is located in central Iceland, under in NW corner of Vatnajökull ice cap. The caldera is about 65 km2 in area, with 500-600 m high topographic rims and is fully covered with up to 800 m thick ice. On 16 August 2014 an intense earthquake swarm started in Bárðarbunga, the beginning of a major volcano-tectonic rifting event forming a 45 km long dyke extending from the caldera to Holuhraun lava field outside the northern margin of Vatnajökull (Sigmundsson et al., 2014). A large basaltic, effusive fissure eruption began in Holuhraun on 31 August that by January had formed a lava field of volume in excess of one cubic kilometre. The collapse of the caldera is expected to have begun a few days after the onset of the earthquake swarm, probably coinciding with the first M5 earthquake. This slow caldera collapse has been monitored through repeated mapping of the gradually increasing subsidence bowl (~80 km2 in December) with airborne profiling of the ice surface, satellite mapping, an online GPS station set up in September on the glacier surface in the centre of the caldera with a strong motion sensor added in November, and indirectly through recording of seismic activity. Satellite interferograms constrain both ice movements and the rate of collapse. The rate of collapse was greatest in the first two weeks or 0.5-1 m/day in the centre, but has since gradually declined with time. The daily rate was 0.1-0.2 m/day in January, when the maximum lowering had reached about 60 m. A gradual widening of the subsidence bowl has been observed since early September. It is asymmetric, deepest in the NE part of the caldera. Downwards displacement extends outside the pre-existing topographic caldera rims, particularly on the south side where the rims have subsided by over 10 meters. Ice-flow modelling indicates that the ice is mostly passively subsiding with the caldera floor. Thus, horizontal ice flow has had little effect on the shape of the subsidence bowl

  2. Understanding volcanic hazard at the most populated caldera in the world: Campi Flegrei, Southern Italy

    Science.gov (United States)

    De Natale, Giuseppe; Troise, Claudia; Kilburn, Christopher R. J.; Somma, Renato; Moretti, Roberto

    2017-05-01

    Naples and its hinterland in Southern Italy are one of the most urbanized areas in the world under threat from volcanic activity. The region lies within range of three active volcanic centers: Vesuvius, Campi Flegrei, and Ischia. The Campi Flegrei caldera, in particular, has been in unrest for six decades. The unrest followed four centuries of quiescence and has heightened concern about an increased potential for eruption. Innovative modeling and scientific drilling are being used to investigate Campi Flegrei, and the results highlight key directions for better understanding the mechanisms of caldera formation and the roles of magma intrusion and geothermal activity in determining the volcano's behavior. They also provide a framework for evaluating and mitigating the risk from this caldera and other large ones worldwide.

  3. Graben calderas of the Sierra Madre Occidental: The case of Guanajuato, central Mexico

    Science.gov (United States)

    Aguirre-Diaz, G. J.; Tristán-González, M.; Labarthe-Hernández, G.; Marti, J.

    2013-12-01

    The Sierra Madre Occidental (SMO) volcanic province is characterized by voluminous silicic ignimbrites that reach an accumulated thickness of 500 to 1500 m. A single ignimbrite can reach up to 350 m thick in its outflow facies. This ignimbrite sequence formed mostly within 38-23 Ma, building up a total estimated volume of ca. 580,000 km3 making the SMO the largest ignimbrite province of the world. We have showed that several and probably most of the SMO ignimbrites were erupted from fissures associated to Basin and Range fault systems or grabens (Geology, 2003), thus naming these volcano-tectonic structures as graben calderas (Caldera Volcanism book, Elsevier, 2008). Generally, the sequence observed in graben calderas include, from oldest to youngest, alluvial fan deposits combined with lacustrine deposits, pyroclastic surge deposits and minor volume ignimbrites, a large-volume ignimbrite that could be massive or made of successive layers, and sometimes silicic lava domes and/or mafic fissural lavas both with vents aligned with the graben trend. Fallout deposits, plinian or non-plinian, are not observed in the sequence. Thus, onset of caldera collapse represented by the major ignimbrite must occur just after deposition of continental sediments within the graben domain. A similar volcano-tectonic development is observed in pull-apart grabens. Therefore, extensional or transtensional tectonics, before and during caldera collapse, and the emplacement of a subgraben shallow silicic magma chamber are the necessary conditions for the development of graben calderas. We describe here the case of the Guanajuato graben caldera, located in the central part of Mexico and in the southeastern portion of the SMO volcanic province. The caldera is part of the economically important mining district of Guanajuato, with 28 silver mines, some active since the 16th century. The caldera structure, a rectangle of 10 x 16 km, was controlled by NW and NE regional fault systems. Most ore

  4. Electrical structure of Plaine des Sables caldera, Piton de la Fournaise volcano (Reunion Island

    Directory of Open Access Journals (Sweden)

    P. A. Schnegg

    1997-06-01

    Full Text Available An Audio Magnetotelluric (AMT profile has been carried out across the Plaine des Sables, a former caldera of the active Piton de la Fournaise volcano, Reunion Island. Located in the Western Indian Ocean, between the Mascarene and Madagascar basins, this basaltic shield volcano originates from the activity of a hot spot. Our aim was to determine the internal structure of the volcano, in particular the shallow electrical properties of an area extending between the old and the new caldera rims. Although several teams had already conducted AMT work in this region a few years ago, there was a need for more a detailed, in depth survey. Our final model displays a noticeable slope of the Plaine des Sables basement oriented toward the present Fournaise summit. This slope is interpreted as resulting from successive landslides toward the ocean. We conclude that this dipping, electrically good conducting layer, probably belongs to the flat layering of an older caldera.

  5. Doubly stochastic models for volcanic hazard assessment at Campi Flegrei caldera

    CERN Document Server

    Bevilacqua, Andrea

    2016-01-01

    This study provides innovative mathematical models for assessing the eruption probability and associated volcanic hazards, and applies them to the Campi Flegrei caldera in Italy. Throughout the book, significant attention is devoted to quantifying the sources of uncertainty affecting the forecast estimates. The Campi Flegrei caldera is certainly one of the world’s highest-risk volcanoes, with more than 70 eruptions over the last 15,000 years, prevalently explosive ones of varying magnitude, intensity and vent location. In the second half of the twentieth century the volcano apparently once again entered a phase of unrest that continues to the present. Hundreds of thousands of people live inside the caldera and over a million more in the nearby city of Naples, making a future eruption of Campi Flegrei an event with potentially catastrophic consequences at the national and European levels.

  6. Recrystallization and anatexis along the plutonic-volcanic contact of the Turkey Creek caldera, Arizona

    Science.gov (United States)

    du Bray, E.A.; Pallister, J.S.

    1999-01-01

    Unusual geologic and geochemical relations are preserved along the contact between intracaldera tuff and a resurgent intrusion within the 26.9 Ma Turkey Creek caldera of southeast Arizona. Thick intracaldera tuff is weakly argillically altered throughout, except in zones within several hundred meters of its contact with the resurgent intrusion, where the groundmass of the tuff has been variably converted to granophyre and unaltered sanidine phenocrysts are present. Dikes of similarly granophyric material originate at the tuff-resurgent intrusion contact and intrude overlying intracaldera megabreccia and tuff. Field relations indicate that the resurgent intrusion is a laccolith and that it caused local partial melting of adjacent intracaldera tuff. Geochemical and petrographic relations indicate that small volumes of partially melted intracaldera tuff assimilated and mixed with dacite of the resurgent intrusion along their contact, resulting in rocks that have petrographic and compositional characteristics transitional between those of tuff and dacite. Some of this variably contaminated, second-generation magma coalesced, was mobilized, and was intruded into overlying intracaldera rocks. Interpretation of the resurgent intrusion in the Turkey Creek and other calderas as intracaldera laccoliths suggests that intrusions of this type may be a common, but often unrecognized, feature of calderas. Development of granophyric and anatectic features such as those described here may be equally common in other calderas. The observations and previously undocumented processes described here can be applied to identification and interpretation of similarly enigmatic relations and rocks in other caldera systems. Integration of large-scale field mapping with detailed petrographic and chemical data has resulted in an understanding of otherwise intractable but petrologically important caldera-related features.

  7. Scientific core hole Valles caldera No. 2b (VC-2b), New Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Garner, J.N.; Hulen, J.B.; Lysne, P.; Jacobson, R.; Goff, F.; Nielson, D.L.; Pisto, L.; Criswell, C.W.; Gribble, R. (Los Alamos National Lab., NM (USA); Utah Univ. Research Inst., Salt Lake City, UT (USA); Sandia National Labs., Albuquerque, NM (USA); Los Alamos National Lab., NM (USA); Utah Univ. Research Inst., Salt Lake City, UT (USA); Tonto Drilling Services, Inc., Salt Lake City, UT (USA); Los Alamo

    1989-01-01

    Research core hole was continuously cored to 1.762 km on the western flank of the caldera's resurgent dome in 1988. Bottom hole temperature is about 295{degree}C within Precambrian (1.5 Ga) quartz monzonite, deep within the liquid-dominated portions of the Sulphur Springs hydrothermal system. VC-2b may be the deepest, hottest, continuously cored hole in North America. Core recovery was 99.2%. The only major drilling problems encountered were when temperatures at the bit exceeded 225{degree}C below depths of about 1000 m. The result of these conditions was loss of viscosity and/or lubricity in the mud, apparently caused by breakdown of the high temperature polymers. Lithologies in caldera-fill indicate the drill site may be proximal to ignimbrite vents and that an intracaldera lake with temperatures approaching boiling formed soon after the caldera itself. Structural correlations between VC-2b and the 528-m-deep companion hole VC-2a indicate the earlier Toledo caldera (1.45 Ma; Otowi Member tuffs) and even older Lower Tuffs caldera experienced no structural resurgence similar to the 1.12 million year old Valles caldera. The hydrothermal system penetrated by these bores, consists of a shallow vapor-rich cap, which has evolved from an earlier 200{degree}C liquid-dominated system, overlying stacked, liquid-dominated zones up to about 300{degree}C. Geochemistry of mud returns collected during drilling suggests chloride-rich geothermal fluids were entering the bore and mixing with the drilling fluids in the fractured lower Paleozoic and Precambrian sections. 23 refs., 5 figs., 1 tab.

  8. Inflation of Aira Caldera (Japan detected over Kokubu urban area using SAR interferometry ERS data

    Directory of Open Access Journals (Sweden)

    D. Remy

    2006-08-01

    Full Text Available Nine ERS-1 and ERS-2 descending orbit data acquired over the Aira Caldera between June 1995 and November 1998 were used to create 31 differential interferograms. Although the interferograms exhibit a relatively low level of coherence, even for couples sampling short time intervals (6 months, Differential Interferometric Synthetic Aperture Radar (DinSAR reveals a pattern of range change signal during the observation period in the urban area of Kokubu city. The analysis of the ground deformation time series relative to the earliest ERS images evidenced a maximum uplift of 23 mm between the north and the south of the city during the studied period. Taking the reduced surface of the coherent area into account, we performed a simple modelling of the deformation field assuming a spherical inflating source within an elastic half-space medium. This simple model predicts a source located beneath the centre of Aira Caldera with a maximum volume increase of 30 106 m3 between 1995 and 1997, which would produced an inflation of about 7 cm of the centre of Aira Caldera and 4 cm of the south of Kokubu city. These results are in good agreement with other geophysical observations carried out on Aira caldera during this unrest period. Despite the limited spatial extent of the coherent areas around Aira Caldera, this study shows that DinSAR method using ERS data can be successfully used to detect subtle ground displacement changes of the volcanic complex and thus provides complementary information to ground-based geodetic monitoring of dynamic processes at Aira Caldera and Sakurajima volcano.

  9. Identification of Calderas Associated With The Acidic Jurassic Volcanism of Southern Patagonia, Argentina

    Science.gov (United States)

    Chernicoff, C. J.; Salani, F. M.

    During the Jurassic, the Patagonian region was subject to a predominantly acidic volcanism locally known as the Chon Aike Volcanic Province, related to the breakup of Gondwana. It comprises ignimbrites, breccias and agglomerates, and a minor component of rhyolitic and dacitic lava domes. In the study area (Río Seco region, Santa Cruz Province), the Jurassic volcanics are largely overlain by Neogene and Quaternary sediments. However, the aeromagnetic survey of this region has unravelled the magnetic pattern of the volcanics, notably two conspicuous calderas, since the young cover sediments are non-magnetic. The magnetic susceptibility of the volcanic rocks ranges 50 to 80 x 10-5 S.I., as oppossed to the nearly null values of the overlying sediments. The geological interpretation of the aeromagnetic survey is mostly based on the analytic signal of the total magnetic intensity, where two distinct sub-circular magnetic lineaments have been recognized and regarded as calderic structures. The eastern caldera, 30 km wide, is centered at 48º 52' S.L./ 68º 02' W.L., and the western caldera, 23 km wide, is centered at 48º 53' S.L. / 68º 29' W.L.. In addition, a number of smaller, high gradient magnetic anomalies have been identified and interpreted as intra- and extracaldera domes. In the eastern caldera, a number of domes follow an anular pattern of fractures regarded as the boundary of an older, outer caldera. A magnetic circular lineament located within the latter structure has been interpreted as a younger, inner caldera which presents a number of small domes in its central depression; additional domes are also located in between the two calderic structures. The western caldera is less complex since it comprises a single structure with intra-caldera domes. The total magnetic gradient (analytic signal) associated with the domes is one order of magnitude higher (0.1 to 0.2) than the mean value of the region (0.03). In addition to the anular fractures and domes, a

  10. Spasmodic tremor and possible magma injection in Long Valley caldera, eastern California

    Energy Technology Data Exchange (ETDEWEB)

    Ryall, A.; Ryall, F.

    1983-03-25

    Intensive microearthquake swarms with the appearance of volcanic tremor have been observed in the southwest part of Long Valley caldera, southeastern California. This activity, possibly associated with magma injection, began 6 weeks after several strong (magnitude 6+) earthquakes in an area south of the caldera and has continued sporadically to the present time. The earthquake sequence and magmatic activity are part of a broad increase in tectonic activity in a 15,000-square-kilometer region surrounding the White Mountains seismic gap, an area with high potential for the next earthquake in the western Great Basin.

  11. Rhyodacites of Kulshan caldera, North Cascades of Washington: Postcaldera lavas that span the Jaramillo

    Science.gov (United States)

    Hildreth, W.; Lanphere, M.A.; Champion, D.E.; Fierstein, J.

    2004-01-01

    Kulshan caldera (4.5??8 km), at the northeast foot of Mount Baker, is filled with rhyodacite ignimbrite (1.15 Ma) and postcaldera lavas and is only the third Quaternary caldera identified in the Cascade arc. A gravity traverse across the caldera yields a steep-sided, symmetrical, complete Bouguer anomaly of -16 mGal centered over the caldera. Density considerations suggest that the caldera fill, which is incised to an observed thickness of 1 km, may be about 1.5 km thick and is flat-floored, overlying a cylindrical piston of subsided metamorphic rocks. Outflow sheets have been stripped by advances of the Cordilleran Ice Sheet, but the climactic fallout (Lake Tapps tephra) is as thick as 30 cm some 200 km south of the caldera. Ten precaldera units, which range in 40Ar/39Ar age from 1.29 to 1.15 Ma, are dikes and erosional scraps that probably never amounted to a large edifice. A dozen postcaldera rhyodacite lavas and dikes range in age from 1.15 to 0.99 Ma; rhyodacites have subsequently been absent, the silicic reservoir having finally crystallized. At least 60 early Pleistocene intermediate dikes next intruded the caldera fill, helping energize an acid-sulfate hydrothermal system and constituting the main surviving record of an early postcaldera andesite-dacite pile presumed to have been large. Most of the pre- and postcaldera rhyodacites were dated by 40Ar/39Ar or K-Ar methods, and 13 were drilled for remanent magnetic directions. In agreement with the radiometric ages, the paleomagnetic data indicate that eruptions took place before, during, and after the Jaramillo Normal Polarity Subchron, and that one rhyodacite with transitional polarity may represent the termination of the Jaramillo. Most of the biotite-hornblende-orthopyroxene-plagioclase rhyodacite lavas, dikes, and tuffs are in the range 68-73% SiO2, but there were large compositional fluctuations during the 300-kyr duration of the rhyodacite episode. The rhyodacitic magma reservoir was wider (11 km) than

  12. Estimates of flow direction for calc-alkaline welded tuffs and paleomagnetic data reliability from anisotropy of magnetic susceptibility measurements: Central San Juan Mountains, southwest Colorado

    Science.gov (United States)

    Ellwood, Brooks B.

    1982-07-01

    Flow directions are estimated from the measurement of the magnetic fabric of 106 samples, collected at 18 sites in four welded tuff units in the central San Juan Mountains of southern Colorado. The estimates assume that the tuffs generally flowed directly away from the extrusive vents and that the lineations of magnetic grains within the tuffs represent the flow direction at individual sites. Errors in the estimation may arise from topographic variation, rheomorphism (post-emplacement mass flow) within the tuff, and other factors. Magnetic lineation is defined as the site mean anisotropy of magnetic susceptibility maximum azimuth. A test on the flow directions for individual units is based on the projection of lineation azimuths and their intersection within or near the known source caldera for the tuff. This test is positive for the four units examined. Paleomagnetic results for these tuffs are probably reliable indicators of the geomagnetic field direction in southwest Colorado, during the time (28.2-26.5 Ma) of emplacement.

  13. An Analysis of Sulfur Content and Multiple Sulfur Isotope Fractionation of Tephra Deposits at Valles Caldera, New Mexico: Variations over the Course of Two Caldera-Forming Eruptions

    Science.gov (United States)

    Campbell, M. E.; Wing, B. A.; Stix, J.

    2010-12-01

    Caldera-forming eruptions leave behind a record of their tempo and mode in their associated tephra deposits. Interpreting this record requires monitors of the pre-eruptive state of the host magma chamber, potential triggers of the eruption, as well as a proxy for volatile evolution during the eruption. Because of the coexistence of multiple S-bearing species in a magma-gas system, S isotopes stand as a potentially powerful tool to interrogate the eruptive records of caldera-forming events. To date, few S isotopic profiles have been measured through the full eruptive cycle of an explosive silicic complex. Here, we present the first multiple S isotope dataset of the complete evolution of a large, silicic, caldera-forming system. High-silica rhyolite samples from Valles Caldera, New Mexico, were gathered from formations spanning two entire caldera cycles: the Lower Bandelier Tuff (LBT, which formed Toledo caldera at 1.6 Ma), the Cerro Toledo Rhyolite, the Upper Bandelier Tuff (UBT, which formed Valles caldera at 1.2 Ma), and the Valles Rhyolite. Whole-rock S was chemically extracted to Ag2S from samples collected from various units within these formations, and S isotopic compositions were subsequently evaluated by fluorination of the Ag2S and mass spectrometry of the resulting SF6. All S isotopic measurements are reported relative to the V-CDT scale. Concurrent analyses of in-house standard materials demonstrate 1 sigma uncertainties for the full analytical procedure on Δ34S, Δ33S, and Δ36S of better than 0.1‰, 0.01‰, and 0.1‰ respectively. Measured δ34S values range from 0.6 to 8.3‰, while Δ33S and Δ36S values vary from -0.06 to 0.02‰ and -0.5 to 0.3‰, respectively. The lowest δ34S values are from units occurring within or immediately before the earliest-erupted plinian Pumice Beds of the LBT and UBT (0.6 to 2.6‰), while the most elevated δ34S values are from the latest-erupted UBT plinian Pumice Bed unit that we sampled (7.0 and 8.3‰). δ34S

  14. Don Juan, de Gonzalo Torrente Ballester: el monstruo en su laberinto

    OpenAIRE

    1995-01-01

    Estudio de la novela "Don Juan" (1963), de Gonzalo Torrente Ballester, dentro de la tradición del mito de Don Juan y como relato de técnica impecable que consigue el reto de hacer una novela fantástica larga.

  15. 77 FR 61632 - Final Environmental Impact Statement for Cattle Point Road Relocation, San Juan Island National...

    Science.gov (United States)

    2012-10-10

    ... National Park Service Final Environmental Impact Statement for Cattle Point Road Relocation, San Juan.... ACTION: Notice of Availability of the Final Environmental Impact Statement for Cattle Point Road... bluff erosion that threatens a segment of the Cattle Point Road located in San Juan Island...

  16. CHARACTERIZING THE ORGANIC MATTER IN SURFACE SEDIMENTS FROM THE SAN JUAN BAY ESTUARY

    Science.gov (United States)

    The San Juan Bay Estuary (SJBE) is located on the north coast of Puerto Rico and includes the San Juan Bay, San José Lagoon, La Torrecilla Lagoon and Piñones Lagoon, as well as the Martín Peña and the Suárez Canals. The SJBE watershed has the highest...

  17. 33 CFR 110.240 - San Juan Harbor, P.R.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false San Juan Harbor, P.R. 110.240 Section 110.240 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Anchorage Grounds § 110.240 San Juan Harbor, P.R. (a) The anchorage...

  18. CHARACTERIZING THE ORGANIC MATTER IN SURFACE SEDIMENTS FROM THE SAN JUAN BAY ESTUARY.

    Science.gov (United States)

    The San Juan Bay Estuary (SJBE) is located on the north coast of Puerto Rico and includes the San Juan Bay, San José Lagoon, La Torrecilla Lagoon and Piñones Lagoon, as well as the Martín Peña and the Suárez Canals. The SJBE watershed has the highest...

  19. La lengua salvada: Acerca de dibaxu de Juan Gelman

    Directory of Open Access Journals (Sweden)

    Enrique Abel Foffani

    2000-11-01

    Full Text Available Se intenta leer el libro dibaxu de Juan Gelman escrito en sefardí desde el horizonte de la tradición poética latinoamericana. A través de la metáfora acerca de "la lengua salvada" de Elías Canetti (una imagen-aconteciªmiento de su propia autobiografía es posible reflexionar sobre la condición de judío y también sobre la relación de la lengua materna y la infancia. En la estela de Rubén Darío y de los poetas posteriores que se vieron en la situación de cambiar de lengua por diversos motivos, Juan Gelman elige el ladino o español sefardí como un doble extrañamiento de la lengua poética: por un lado pertenece a la línea azkenazí y no sefardita y por el otro recupera el español del siglo XV en consonancia con otras propuestas poéticas en las que había ya ensayado el rescate de la voz de poetas españoles como San Juan de la Cruz , Santa Teresa y los poetas místicos árabes. Desde esta perspectiva, el artículo analiza desde la extraterritorialización de la lengua poética los temas de dibaxu y otros libros anteriores a fin de señalar ciertas constantes y sus modos diferentes de articulación en el texto poético.

  20. La lengua salvada: Acerca de dibaxu de Juan Gelman

    Directory of Open Access Journals (Sweden)

    Enrique Abel Foffani

    2001-11-01

    Full Text Available Se intenta leer el libro dibaxu de Juan Gelman escrito en sefardí desde el horizonte de la tradición poética latinoamericana. A través de la metáfora acerca de "la lengua salvada" de Elías Canetti (una imagen-aconteciªmiento de su propia autobiografía es posible reflexionar sobre la condición de judío y también sobre la relación de la lengua materna y la infancia. En la estela de Rubén Darío y de los poetas posteriores que se vieron en la situación de cambiar de lengua por diversos motivos, Juan Gelman elige el ladino o español sefardí como un doble extrañamiento de la lengua poética: por un lado pertenece a la línea azkenazí y no sefardita y por el otro recupera el español del siglo XV en consonancia con otras propuestas poéticas en las que había ya ensayado el rescate de la voz de poetas españoles como San Juan de la Cruz , Santa Teresa y los poetas místicos árabes. Desde esta perspectiva, el artículo analiza desde la extraterritorialización de la lengua poética los temas de dibaxu y otros libros anteriores a fin de señalar ciertas constantes y sus modos diferentes de articulación en el texto poético.

  1. Animales en la obra de Juan José Arreola

    OpenAIRE

    Samperio, Guillermo

    2004-01-01

    Los bestiarios medievales son una tentativa, aunque sea parcial, por explicar la creación. En la letras latinoamericanas, Jorge Luis Borges, Julio Cortázar y Juan José Arreola renuevan los bestiarios de la edad Media. En este artículo se analizará la obra de Arreola, pues en ella, la imagen del animal trasciende de la forma simbólica del bestiario medieval y toma la forma nominalista del signo para la formulación de metáforas que transforman, no sólo a los hombres, sino también a los objetos,...

  2. Il mestiere di tradurre 1: entrevista a Juan Antonio Vivanco

    Directory of Open Access Journals (Sweden)

    Juan Antonio Vivanco Gefaell

    2013-01-01

    Full Text Available Hijo del poeta Luis Felipe Vivanco y de la escritora María Luisa Gefaell, Juan Antonio Vivanco Gefaell lleva más de tres décadas desarrollando una prestigiosa labor como traductor. Por sus manos han pasado autores italianos tan dispares como Roberto Saviano (La belleza y el infierno, Debolsillo, 2010, Paolo Maurensig (Canon inverso, Mondadori, 1997, Pier Paolo Pasolini (Escritos corsarios, Ed. Del Oriente, 2009 o Paolo Cottino (La ciudad imprevista, Bellaterra, 2005, por citar unos pocos.Traductor minucioso y preciso no sólo de textos narrativos, también se deben a él textos técnicos que abarcan media docena de especialidades humanísticas: desde  libros de antropología como el interesante Genes, pueblos y lengua de Luca Cavalli Sforza (Crítica, 1997, a textos de etnografía como La tierra del remordimiento de Ernesto de Martino (Bellaterra, 1999 en cuya traducción, nos comenta, disfrutó de forma especial, hasta llegar a densos manuales como la Historia de España de Joseph Pérez (Crítica, 1999 o Crisis e inflación entre la Antigüedad y la Edad Media de Georges Depeyrot (Crítica, 1996. Intentar abarcar el trabajo de Juan Antonio Vivanco implicaría, sin duda, citar las mejores editoriales de nuestro país y una amplia variedad temática hasta abarcar disciplinas tan diversas como la micología, el alpinismo, la historia del Arte y, especialmente, sus múltiples traducciones de estudios sobre Islam y Oriente Medio.Zibaldone. Estudios italianos le agradece que se haya prestado a inaugurar este espacio, Il mestiere di tradurre, contestando a unas preguntas sobre su trayectoria y su  profesión. Entrevista de Juan José Tejero y Juan Pérez Andrés. 

  3. Mito, peregrinación y modernidad en Juan Rulfo.

    OpenAIRE

    2014-01-01

    Aunque confiesa a Luis Harss (1) que se considera de San Gabriel, donde pasó su infancia, Juan Rulfo nació en Sayula, Jalisco, en 1918. Autor de un libro de cuentos, una novela y unos guiones cinematográficos, así como de expresivas fotografías que revelan la hondura de su alma,, de su tierra, y de su pueblo, se desempeño durante largo tiempo como empleado en el Instituto Indigenista de México.

  4. Juan Valdez in the coffe market of France

    OpenAIRE

    Rodriguez Maldonado, Edna Katherine

    2010-01-01

    El objetivo de este trabajo es presentar un marco organizacional en profundidad de las operaciones de Juan Valdez y sus posibilidades de incursionar en el mercado Francés. El Análisis se presenta en base a una investigación de mercados que tiene como referencia las tendencias de consumo, más exactamente hacía bebidas con alto contenido de cafeína, (Bebidas energizantes, deportivas, café etc.). Igualmente se analizan los socios estratégicos con más fuerza de realizar alianzas con la empresa c...

  5. Mediastinal pathology and the contributions of Dr. Juan Rosai.

    Science.gov (United States)

    Wick, Mark R

    2016-09-01

    Dr. Juan Rosai is one of the most prolific contributors to the literature on mediastinal pathology, and he has added steadily to that body of work over a 50-year period. Rosai has written several landmark articles in this topical area, including articles on thymic epithelial lesions, mediastinal neuroendocrine tumors, mediastinal lymphoma and other hematopoietic lesions, thymolipoma, thymoliposarcoma, mediastinal solitary fibrous tumor, intrathymic langerhans-cell histiocytosis, mediastinal germ cell neoplasms, and multilocular thymic cyst. This review recounts his role as one of the principal figures in the surgical pathology of mediastinal diseases.

  6. Juan Rodríguez Freile (cronista colonial

    Directory of Open Access Journals (Sweden)

    Julio Enrique Cuervo Escobar

    1963-06-01

    Full Text Available Juan Rodríguez Freile -1566-1638-. Aspirante al sacerdocio, soldado en los albores de la Conquista y más tarde hombre pacífico, que cambió las armas por instrumentos de labranza y en la vejez por la pluma, escribiendo sobre la "Conquista y Descubrimiento del Nuevo Reino. de Granada . .. " (El título completo equivale al índice 1, crónica santafereña que ha pasado a la posteridad con el título familiar de '·'EI Carnero".

  7. Iglesia de San Juan de Mayorga : un espacio recuperado

    OpenAIRE

    Valle González, Roberto

    2014-01-01

    El Museo del Pan ha sido diseñado a partir del edificio existente de la Iglesia de San Juan, en la localidad de Mayorga. La iglesia es de estilo mudéjar y estaba abandonada desde hace mucho tiempo. Siendo insuficiente su superficie para albergar los contenidos del museo, se hizo necesario construir un nuevo edificio en el solar disponible, adosado a la iglesia por el lado opuesto a la cabecera. El nuevo edificio queda así determinado por la forma del solar, el edificio adosado medianero y ...

  8. LA POÉTICA DE LA CONCIENCIA JUAN CARLOS MESTRE

    OpenAIRE

    CARLOS EDUARDO ORDÓÑEZ ORDÓÑEZ

    2015-01-01

    A trajetória poética de Juan Carlos Mestre (León, España, 1957) se urde em diversas geografias cujos contextos influem de forma determinante no seu pensamento poético: a visão melancólica e trágica de Villafranca del Bierzo, sua cidade natal; a agitada Barcelona dos movimentos de oposição ao franquismo, onde o poeta realizou estudos universitários; o âmbito chileno, entre utopia e desgraça, durante os últimos anos da ditadura de Augusto Pinochet; a Madri de finais dos anos oite...

  9. A morte e as mortes na obra de Juan Rulfo

    OpenAIRE

    Euzébio, Vilmar Machado

    2008-01-01

    Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão. Programa de Pós-Graduação em Literatura A presente dissertação realiza uma trajetória pela narrativa de el Llano en Llamas (1953) e Pedro Páramo (1955) de Juan Rulfo. Nessas obras, a morte - grande conflito humano - aparece como tema recorrente. Os personagens de el Llano en Llamas "vivem"ensimesmados na solidão do campo, enquanto os personagens de Pedro Páramo sofrem coletivamente sob o dom...

  10. Rabia canina en san Juan de Lurigancho y en Jicamarca

    OpenAIRE

    2004-01-01

    Hasta la tercera semana de noviembre se han confirmado cuatro casos de rabia canina en la DISA Lima Norte, el último caso se presentó el 20 de noviembre en la granja porcina «Pradera del Paraíso» en el distrito de San Juan de Lurigancho (SJL), perteneciente a la referida Dirección de Salud. Dicho caso sucedió en momentos que un trabajador de la granja trató de separar la pelea entre los perros guardianes de la granja y un perro de origen desconocido, siendo finalmente mordido en una de...

  11. El realismo mágico en "Juan Girador"

    OpenAIRE

    Arguedas, María Eugenia

    2015-01-01

    El realismo mágico es un elemento vital en el "Juan girador" una de las leyendas en "El espejo de Lida Sal". Este análisis comprende el barroco y el mito y la leyenda, todos los cuales aparecen en diferentes niveles textuales, dando como resultado una creación literaria altamente inusual. La leyenda se analiza como una narración corta que se utiliza para presentar una realidad mítica. Se da especial importancia al uso de Asturias de un elemento puramente latinoamericano, el indio, como una co...

  12. Magma genesis and chamber processes at Los Humeros caldera, Mexico-Nd and Sr isotope data

    Science.gov (United States)

    Verma, Surendra P.

    1983-03-01

    The Mexican volcanic belt (MVB), a roughly east-west structure, consists of many late Tertiary and Quaternary cindercones, domes, calderas and stratovolcanoes1,2. Los Humeros caldera (approximately 19°40' N latitude, 97°25' W longitude) lies on the northeastern part of the MVB where the belt overlaps with another major volcanic province, the Eastern cordillera3 (Fig. 1). A compilation6 of the bulk chemical analyses of the two major volcanic provinces indicates that the MVB is characterized largely by calc-alkaline series whereas rocks of the alkaline series dominate the Eastern cordiliera (EC). Pleistocene to Recent basaltic to rhyolitic volcanism in Los Humeros caldera, one of the best known examples of a well-developed caldera in Mexico7-9, presumably associated with the subduction of Cocos plate along the Middle America trench, shows that the initial 87Sr/86Sr ratios range from 0.7039 to 0.7048 and the initial 143Nd/144Nd ratios from 0.5126 to 0.5129. We show here that these isotope ratios are negatively correlated and lie on the mantle array defined by MORB and oceanic island rocks; implying that Los Humeros magmas were generated in the upper mantle with very little, if any, contribution from the subducted oceanic crust, sediments or continental crust.

  13. The Caetano Caldera, Nevada: 5 km Thickness of Intracaldera Rhyolite Ignimbrite and Co-Magmatic Batholith

    Science.gov (United States)

    John, D. A.; Henry, C. D.; Colgan, J. P.

    2008-12-01

    The Caetano caldera in northern Nevada is cut by Miocene extensional faults that extraordinarily expose a complete, thick (>4 km) intracaldera rhyolite ignimbrite (Caetano Tuff) and underlying cogenetic granitic plutons in tilted blocks reaching to >5 km of paleodepth. The caldera contains (1) a 1-km-thick upper unit of Caetano Tuff composed of multiple, thin cooling units and interbedded sedimentary rocks, (2) a >3.5- km-thick lower compound cooling unit of Caetano Tuff, and (3) 5 shallowly emplaced (locally 50 km2. Ten sanidine 40Ar/39Ar ages from the stratigraphically lowest Caetano Tuff through the youngest shallow pluton are indistinguishable at 33.8 Ma, indicating that eruption of >1000 km3 of rhyolite tuff, caldera collapse, magma resurgence, and pluton emplacement occurred in residual magma from the reservoir that fed the later parts of the eruption. Field, geochemical, and geochronologic data prove a shallow batholith-scale magma reservoir erupted to form the Caetano caldera and fed cogenetic granite plutons. Additional geochemical and geochronologic (SHRIMP) studies are underway to constrain magma sources, duration of assembly, and compositional zoning of the Caetano magma reservoir.

  14. Quantifying volcanic hazard at Campi Flegrei caldera (Italy) with uncertainty assessment: 1. Vent opening maps

    Science.gov (United States)

    Bevilacqua, Andrea; Isaia, Roberto; Neri, Augusto; Vitale, Stefano; Aspinall, Willy P.; Bisson, Marina; Flandoli, Franco; Baxter, Peter J.; Bertagnini, Antonella; Esposti Ongaro, Tomaso; Iannuzzi, Enrico; Pistolesi, Marco; Rosi, Mauro

    2015-04-01

    Campi Flegrei is an active volcanic area situated in the Campanian Plain (Italy) and dominated by a resurgent caldera. The great majority of past eruptions have been explosive, variable in magnitude, intensity, and in their vent locations. In this hazard assessment study we present a probabilistic analysis using a variety of volcanological data sets to map the background spatial probability of vent opening conditional on the occurrence of an event in the foreseeable future. The analysis focuses on the reconstruction of the location of past eruptive vents in the last 15 ka, including the distribution of faults and surface fractures as being representative of areas of crustal weakness. One of our key objectives was to incorporate some of the main sources of epistemic uncertainty about the volcanic system through a structured expert elicitation, thereby quantifying uncertainties for certain important model parameters and allowing outcomes from different expert weighting models to be evaluated. Results indicate that past vent locations are the most informative factors governing the probabilities of vent opening, followed by the locations of faults and then fractures. Our vent opening probability maps highlight the presence of a sizeable region in the central eastern part of the caldera where the likelihood of new vent opening per kilometer squared is about 6 times higher than the baseline value for the whole caldera. While these probability values have substantial uncertainties associated with them, our findings provide a rational basis for hazard mapping of the next eruption at Campi Flegrei caldera.

  15. Long-term magmatic evolution at the Campi Flegrei caldera (Southern Italy)

    Science.gov (United States)

    Forni, Francesca; Bachmann, Olivier; De Astis, Gianfilippo; Mollo, Silvio

    2017-04-01

    Understanding the mechanisms that lead to the accumulation of large silicic upper-crustal magma bodies, potentially resulting in high magnitude caldera-forming eruptions, is fundamental to better constraining volcanic hazard of populous regions on Earth. Campi Flegrei is an excellent example of active and restless volcano, located in a densely populated area, which hosted, during the last 60 ka, two cataclysmic caldera-forming eruptions (Campanian Ignimbrite, 39 ka and Neapolitan Yellow Tuff, 15 ka) and a number of smaller magnitude volcanic events. Here we use detailed petrological data to reconstruct magma storage conditions and understand the past, present and future evolution of the magmatic system at Campi Flegrei. Our data reveal that during the two major eruptions most of the eruptible crystal-poor magma and part of the cumulate crystal mush were efficiently evacuated from the upper crustal reservoir, leading to a caldera collapse. Subsequently, the magmatic reservoir was replenished by more mafic magmas of deeper origin, which evolved through time towards more silicic, colder and more volatile-rich compositions. The most recent eruption at Monte Nuovo (1538 AD), characterized by highly evolved, low temperature and wet magmas akin to those that fed the pre-caldera magmatic activity, suggests that a potentially explosive magma reservoir might be currently present at Campi Flegrei.

  16. Monitoring super-volcanoes: Geophysical and geochemical signals at Yellowstone and other large caldera systems

    Science.gov (United States)

    Lowenstern, J. B.; Smith, R.B.; Hill, D.P.

    2006-01-01

    Earth's largest calderas form as the ground collapses during immense volcanic eruptions, when hundreds to thousands of cubic kilometres of magma are explosively withdrawn from the Earth's crust over a period of days to weeks. Continuing long after such great eruptions, the resulting calderas often exhibit pronounced unrest, with frequent earthquakes, alternating uplift and subsidence of the ground, and considerable heat and mass flux. Because many active and extinct calderas show evidence for repetition of large eruptions, such systems demand detailed scientific study and monitoring. Two calderas in North America, Yellowstone (Wyoming) and Long Valley (California), are in areas of youthful tectonic complexity. Scientists strive to understand the signals generated when tectonic, volcanic and hydrothermal (hot ground water) processes intersect. One obstacle to accurate forecasting of large volcanic events is humanity's lack of familiarity with the signals leading up to the largest class of volcanic eruptions. Accordingly, it may be difficult to recognize the difference between smaller and larger eruptions. To prepare ourselves and society, scientists must scrutinize a spectrum of volcanic signals and assess the many factors contributing to unrest and toward diverse modes of eruption. ?? 2006 The Royal Society.

  17. Steady subsidence of a repeatedly erupting caldera through InSAR observations: Aso, Japan

    Science.gov (United States)

    Nobile, Adriano; Acocella, Valerio; Ruch, Joel; Aoki, Yosuke; Borgstrom, Sven; Siniscalchi, Valeria; Geshi, Nobuo

    2016-04-01

    The relation between unrest and eruption at calderas is still poorly understood. Aso caldera, Japan, shows minor episodic eruptions, mainly phreatic, associated with steady subsidence. We analyse the recent deformation of Aso using SAR images from 1993 to 2011 and compare this with the eruptive activity. Although the dataset suffers from limitations (e.g., atmospheric effects, coherence loss, low signal to noise ratio), we observe a steady subsidence signal from 1996 to 1998, that suggests an overall contraction of a magmatic source below the caldera centre, from 4.5 to 7 km depth. Because of the similar volumes of the contracting source and erupted material, we propose that the contraction may have been induced by the release of the magmatic fluids feeding the eruptions. If confirmed by further data, this hypothesis suggests that degassing processes play a crucial role in triggering minor eruptions within open conduit calderas, as at Aso. These features underline the importance of defining any eruptive potential also from deflating magmatic systems with open conduit.

  18. Applying hydrology to land management on the Valles Caldera National Preserve

    Science.gov (United States)

    Robert R. Parmenter

    2009-01-01

    Since 2004, the Valles Caldera National Preserve (VCNP) in the Jemez Mountains of northern New Mexico has hosted extensive field hydrology research by scientists from the Center for Sustainability of semi- Arid Hydrology and Riparian Areas (SAHRA) at the University of Arizona. With the development of a detailed hydrologic understanding of VCNP's climate, geology,...

  19. Identification of a Kulshan caldera correlative tephra in the Palouse loess of Washington State, northwest USA

    Science.gov (United States)

    King, Georgina E.; Pearce, Nicholas J. G.; Roberts, Helen M.; Smith, Victoria C.; Westgate, John A.; Gaylord, David R.; Sweeney, Mark R.

    2016-09-01

    The Kulshan caldera formed at ∼1.15 Ma on the present-day site of Mt. Baker, Washington State, northwest USA and erupted a compositionally zoned (dacite-rhyolite) magma and a correlative eruptive, the Lake Tapps tephra. This tephra has previously been described, but only from the Puget Lowland of NW Washington. Here an occurrence of a Kulshan caldera correlative tephra is described from the Quaternary Palouse loess at the Washtucna site (WA-3). Site WA-3 is located in east-central Washington, ∼340 km southeast of the Kulshan caldera and ∼300 km east-southeast of the Lake Tapps occurrence in the Puget Lowland. Major- and trace element chemistry and location of the deposit at Washtucna within reversed polarity sediments indicates that it is not correlative with the Mesa Falls, Rockland, Bishop Ash, Lava Creek B or Huckleberry Ridge tephras. Instead the Washtucna deposit is related to the Lake Tapps tephra by fractional crystallisation, but is chemically distinct, a consequence of its eruption from a compositionally zoned magma chamber. The correlation of the Washtucna occurrence to the Kulshan caldera-forming eruption indicates that it had an eruptive volume exceeding 100 km3, and that its tephra could provide a valuable early-Pleistocene chronostratigraphic marker in the Pacific Northwest.

  20. Monitoring super-volcanoes: geophysical and geochemical signals at Yellowstone and other large caldera systems.

    Science.gov (United States)

    Lowenstern, Jacob B; Smith, Robert B; Hill, David P

    2006-08-15

    Earth's largest calderas form as the ground collapses during immense volcanic eruptions, when hundreds to thousands of cubic kilometres of magma are explosively withdrawn from the Earth's crust over a period of days to weeks. Continuing long after such great eruptions, the resulting calderas often exhibit pronounced unrest, with frequent earthquakes, alternating uplift and subsidence of the ground, and considerable heat and mass flux. Because many active and extinct calderas show evidence for repetition of large eruptions, such systems demand detailed scientific study and monitoring. Two calderas in North America, Yellowstone (Wyoming) and Long Valley (California), are in areas of youthful tectonic complexity. Scientists strive to understand the signals generated when tectonic, volcanic and hydrothermal (hot ground water) processes intersect. One obstacle to accurate forecasting of large volcanic events is humanity's lack of familiarity with the signals leading up to the largest class of volcanic eruptions. Accordingly, it may be difficult to recognize the difference between smaller and larger eruptions. To prepare ourselves and society, scientists must scrutinize a spectrum of volcanic signals and assess the many factors contributing to unrest and toward diverse modes of eruption.

  1. Topographic modelling of caldera analogues using Structure from Motion - Multiview stereo-photogrammetry

    Science.gov (United States)

    Ulusoy, İnan; Aydın, Eda; Evren Çubukçu, H.

    2016-04-01

    Analogue caldera models have long been used in volcanology to investigate structural evolution of volcanoes during tumescence and collapse periods. Influence of tectonic forces on volcanic features are also in the scope of those experiments. As well as interior modelling of the caldera experiments, topographic modelling is essential for digital monitoring and quantification purposes. Topographic modelling of those sandbox models is possible using laser scanning techniques. Particle tracking using still images is another way to demonstrate and quantify the structure and movement during the experiment. The quantum leap in the digital photography and computation tools and ease of access to both, provides the use of a new modelling technique in various scales and applications in Geology. Although the roots are older, Structure from Motion - Multiview stereo-photogrammetry (SfM-MVS) is a relatively new technique for surface modelling via several high resolution photographs. We have used SfM-MVS to digitally model the elevation of the tumescence and collapse cycles in analogue caldera experiments. Several sandbox experiments have been modelled using SfM-MVS technique stage by stage during tumescence and collapse periods. It has been possible to evaluate the structural evolution of the collapse models. Additionally, using particle tracking via still images acquired during the experiments, we have modelled the superficial evolution of the caldera structure. SfM-MVS is an effective low budget method for modelling in decimetric scale down to millimetre/micrometre precision.

  2. A three-dimensional gravity model of the geologic structure of Long Valley caldera

    Energy Technology Data Exchange (ETDEWEB)

    Carle, S.F.; Goldstein, N.E.

    1987-03-01

    Several attempts to define and interpret this anomaly have been made in the past using 2-D and 3-D models. None of the previous interpretations have yielded definitive results, but in fairness, the interpretation here has benefited from a larger gravity data base and more subsurface control than available to previous workers. All published 3-D models simplistically assumed constant density of fill. All 2-D models suffered from the inherent three-dimensionality of the complicated density structure of Long Valley caldera. In addition, previous interpreters have lacked access to geological data, such as well lithologies and density logs, seismic refraction interpretations, suface geology, and structural geology interpretations. The purpose of this study is to use all available gravity data and geological information to constrain a multi-unit, 3-D density model based on the geology of Long Valley caldera and its vicinity. Insights on the geologic structure of the caldera fill can help other geophysical interpretations in determining near-surface effects so that deeper structure may be resolved. With adequate control on the structure of the caldera fill, we are able to examine the gravity data for the presence of deeper density anomalies in the crust. 20 refs., 7 figs.

  3. Galileo's Last Fly-Bys of Io: NIMS Observations of Loki, Tupan, and Emakong Calderas

    Science.gov (United States)

    Lopes, Rosaly M. C.; Kamp, L. W.; Davies, A. G.; Smythe, W. D.; Carlson, R. W.; Doute, S.; McEwen, A.; Turtle, E. P.; Leader, F.; Mehlman, R.

    2002-01-01

    NIMS results from the 2001 Galileo fly-bys of Io will be presented, focusing on three calderas that may contain lava lakes. Preliminary results from the January 2002 Io fly-by will be presented. Additional information is contained in the original extended abstract.

  4. A short review of our current understanding of the development of ring faults during collapse caldera formation

    Directory of Open Access Journals (Sweden)

    Adelina eGeyer

    2014-09-01

    Full Text Available The term collapse caldera refers to those volcanic depressions resulting from the sinking of the chamber roof due to the rapid withdrawal of magma during the course of an eruption. During the last three decades, collapse caldera dynamics has been the focus of attention of numerous, theoretical, numerical and experimental studies. Nonetheless, even if there is a tendency to go for a general and comprehensive caldera dynamics model, some key aspects remain unclear, controversial or completely unsolved. This is the case of ring fault nucleation points and propagation and dip direction. Since direct information on calderas’ deeper structure comes mainly from partially eroded calderas or few witnessed collapses, ring faults layout at depth remains still uncertain. This has generated a strong debate over the detailed internal fault and fracture configuration of a caldera collapse and, in more detail, how ring faults initiate and propagate. We offer here a very short description of the main results obtained by those analogue and theoretical/mathematical models applied to the study of collapse caldera formation. We place special attention on those observations related to the nucleation and propagation of the collapse-controlling ring faults. This summary is relevant to understand the current state-of-the-art of this topic and it should be taken under consideration in future works dealing with collapse caldera dynamics.

  5. Plio-pleistocene volcano-tectonic evolution of la Reforma Caldera, Baja California, Mexico

    Science.gov (United States)

    Demant, Alain; Ortlieb, Luc

    1981-01-01

    La Reforma volcanic complex, in east-central Baja California, shows a characteristic caldera structure, 10 km in diameter. The first eruptive stage, during the Pliocene, was manifested by ash and pumice falls and by subaqueous pumitic flows. In a second stage basic flows were deposited in a near-shore environment (subaerial and pillow lavas). During the early Pleistocene a large ignimbritic eruption, producing mainly pantelleritic tuffs, immediately predated the formation of the caldera itself. Afterwards, along marginal fractures of the caldera, some rhyolitic domes and flows partially covered the thick ignimbritic sheet. A block of Miocene substratum, in the center of the caldera, has been uplifted, nearly 1 km, by "resurgent doming". Small outcrops of diorite might constitute the top of coarse-grained crystallized magmatic bodies, and thus support the "resurgent doming" interpretation. A few basaltic cones were finally built on the flanks of the caldera complex; the latter are not related to the caldera history but to the extension tectonics of the Gulf of California which are also responsible for the Tortuga Island and the Holocene Tres Virgenes tholeiitic cones. South of la Reforma are found the highest (+300 m) Pleistocene marine deposits of the Gulf coast of Baja California. The uplift of this area is due in part to the positive epeirogenic movements of the whole peninsular crustal block, and also to the late doming of the caldera. On the coastal (eastern) flank of La Reforma complex up to seven stepped wave-cut terraces have been preserved, the highest reaching more than +150 m and the lowest ones +25 m. Lateral correlations of the marine terraces along the whole Gulf of California suggest that this volcano-tectonic uplift, that is still active, is of the order of 240 mm/10 3 y. The set of terraces is interpreted to be Middle (700-125 × 10 3y) to Upper (125-80 × 10 3y) Pleistocene, and is tentatively correlated with the paleoclimatic chronology of deep

  6. Activity and abundance of denitrifying bacteria in the subsurface biosphere of diffuse hydrothermal vents of the Juan de Fuca Ridge

    Science.gov (United States)

    Bourbonnais, A.; Juniper, S. K.; Butterfield, D. A.; Devol, A. H.; Kuypers, M. M. M.; Lavik, G.; Hallam, S. J.; Wenk, C. B.; Chang, B. X.; Murdock, S. A.; Lehmann, M. F.

    2012-11-01

    Little is known about fixed nitrogen (N) transformation and elimination at diffuse hydrothermal vents where anoxic fluids are mixed with oxygenated crustal seawater prior to discharge. Oceanic N sinks that remove bio-available N ultimately affect chemosynthetic primary productivity in these ecosystems. Using 15N paired isotope techniques, we determined potential rates of fixed N loss pathways (denitrification, anammox) and dissimilatory nitrate reduction to ammonium (DNRA) in sulfidic hydrothermal vent fluids discharging from the subsurface at several sites at Axial Volcano and the Endeavour Segment on the Juan de Fuca Ridge. We also measured physico-chemical parameters (i.e., temperature, pH, nutrients, H2S and N2O concentrations) as well as the biodiversity and abundance of chemolithoautotrophic nitrate-reducing, sulfur-oxidizing γ-proteobacteria (SUP05 cluster) using sequence analysis of amplified small subunit ribosomal RNA (16S rRNA) genes in combination with taxon-specific quantitative polymerase chain reaction (qPCR) assays. Denitrification was the dominant N loss pathway in the subsurface biosphere of the Juan de Fuca Ridge, with rates of up to ~1000 nmol N l-1 day-1. In comparison, anammox rates were always waters. Taxon-specific qPCR revealed that γ-proteobacteria of the SUP05 cluster sometimes dominated the microbial community (SUP05/total bacteria up to 38%). Significant correlations were found between fixed N loss (i.e., denitrification, anammox) rates and in situ nitrate and dissolved inorganic nitrogen (DIN) deficits in the fluids, indicating that DIN availability may ultimately regulate N loss in the subsurface. Based on our rate measurements, and on published data on hydrothermal fluid fluxes and residence times, we estimated that up to ~10 Tg N yr-1 could globally be removed in the subsurface biosphere of hydrothermal vents systems, thus, representing a small fraction of the total marine N loss (~275 to > 400 Tg N yr-1).

  7. Evidence from cosmic-ray exposure dating based on 36Cl for the pre-Minoan caldera on Santorini, Greece

    Science.gov (United States)

    Athanassas, Constantin; Bourlès, Didier; Braucher, Regis; Druitt, Tim; Nomikou, Paraskevi; Léanni, Laetitia

    2016-04-01

    The physiography of Santorini prior to the Minoan (Late Bronze Age) eruption (17th century BCE) is of great archaeological interest, given the importance of Santorini as a commercial centre and port in the Minoan empire. However, the paleogeography of the pre-Minoan caldera has been a point of controversy: Heiken and McCoy (1984) advocated the existence, in the southern part of the present-day caldera, of a pre-existing caldera formed during the 172 ka Lower Pumice eruption, whereas Druitt and Francaviglia (1992), based on the presence of in situ plinian pumice from the Minoan eruption adhering to the modern cliff, conceived the pre-Minoan (22 ka) caldera as having occupied much of the northern basin of the present-day caldera. With the goal of settling the debate we performed cosmic ray exposure dating employing in situ-produced cosmogenic 36Cl to date different generations of caldera cliffs at Santorini, and hence to identify those cliffs predating the Minoan eruption. Our methodology involved the determination of the in situ-produced cosmogenic 36Cl in basaltic and andesitic rocks cropping out in the cliffs. The samples returned 36Cl CRE ages consistent with previously published field mapping of cliff populations based on geomorphological and stratigraphic arguments (Druitt and Francaviglia 1992), suggesting that much of the present cliff line of northern Santorini predated the Minoan eruption, or was superficially modified by landslips and rockfalls during that eruption. The 36Cl CRE ages enable us to better define the paleogeography of the pre-Minoan caldera. References [1] Druitt, T. H. and Francaviglia, V.1992. Caldera formation on Santorini and the physiography of the islands in the Late Bronze Age. Bulletin of Volcanology 54, 484-493. [2] Heiken G and McCoy F (1984) Caldera development during the Minoan eruption, Thira, Cyclades, Greece. Journal of Geophysical Research: 89 (B10), 8841-8862.

  8. Paralelismos y divergencias entre Juan Tenorio de Tirso de Molina y Miguel Páramo, personaje de Juan Rulfo.

    Directory of Open Access Journals (Sweden)

    Herlinda Ramírez-Barradas.

    2009-01-01

    Full Text Available Resumen: En este breve artículo se presentan algunas características de Miguel Páramo que, primero, permiten incluirlo en la larga lista de personajes donjuanescos derivados de la obra de Tirso de Molina y que, además, hacen posible entender su función trágica.Summary: This article presents some of Miguel Páramo's characteristics that, first, allow including him in the long list of prominent Don Juan figures derived from Tirso de Molina's work and, in addition, make it possible to understand his tragic function.

  9. Aprendizajes del Accidente de San Juan Ixhuatepec-México Learning from the Accident in San Juan Ixhuatepec-Mexico

    OpenAIRE

    Antioco López-Molina; Richart Vázquez-Román; Christian Díaz-Ovalle

    2012-01-01

    El índice Dow de fuego y explosión y la metodología del análisis cuantitativo del riesgo son aplicados para analizar uno de los accidentes más desafortunados en la historia mexicana: la explosión de tanques de almacenamiento de gas en la planta de San Juan Ixhuatepec en México. Estimaciones adicionales de la sobrepresión y radiación térmica producida durante el siniestro son llevadas a cabo para explicar el efecto dominó producido como consecuencia del incidente. Estas estimaciones dan eviden...

  10. La encrucijada en Pedro Páramo de Juan Rulfo / The Crossroads in Pedro Páramo by Juan Rulfo

    OpenAIRE

    Lilia Leticia García-Peña

    2015-01-01

    La obra de Juan Rulfo sintetiza la realidad del campo mexicano, captura el contorno de las identidades individuales y de la estructura de la interacción social del mundo que tanto le preocupó y del que es intérprete indiscutible, pero también supo convertir en materia narrativa aquellas atmósferas que rebasan el contexto mexicano y social. En este trabajo abordaré el tema de la encrucijada en el imaginario simbólico de Pedro Páramo (1955) como expresión de una reelaboración del mito de Hermes...

  11. Nonlinear teleseismic tomography at Long Valley caldera, using three-dimensional minimum travel time ray tracing

    Energy Technology Data Exchange (ETDEWEB)

    Weiland, C.M. [Univ. of California, Santa Barbara, CA (United States); Steck, L.K. [Los Alamos National Lab., NM (United States); Dawson, P.B. [Geological Survey, Menlo Park, CA (United States)] [and others

    1995-10-10

    The authors explore the impact of three-dimensional minimum travel time ray tracing on nonlinear teleseismic inversion. This problem has particular significance when trying to image strongly contrasting low-velocity bodies, such as magma chambers, because strongly refracted/and/or diffracted rays may precede the direct P wave arrival traditionally used in straight-ray seismic tomography. They use a simplex-based ray tracer to compute the three-dimensional, minimum travel time ray paths and employ an interative technique to cope with nonlinearity. Results from synthetic data show that their algorithm results in better model reconstructions compared with traditional straight-ray inversions. The authors reexamine the teleseismic data collected at Long Valley caldera by the U.S. Geological Survey. The most prominent feature of their result is a 25-30% low-velocity zone centered at 11.5 km depth beneath the northwestern quandrant of the caldera. Beneath this at a depth of 24.5 km is a more diffuse 15% low-velocity zone. In general, the low velocities tend to deepen to the south and east. The authors interpret the shallow feature to be the residual Long Valley caldera magma chamber, while the deeper feature may represent basaltic magmas ponded in the midcrust. The deeper position of the prominent low-velocity region in comparison to earlier tomographic images is a result of using three-dimensional rays rather than straight rays in the ray tracing. The magnitude of the low-velocity anomaly is a factor of {approximately}3 times larger than earlier models from linear arrival time inversions and is consistent with models based on observations of ray bending at sites within the caldera. These results imply the presence of anywhere from 7 to 100% partial melt beneath the caldera. 40 refs., 1 fig., 1 tab.

  12. Finite-element modeling of magma chamber-host rock interactions prior to caldera collapse

    Science.gov (United States)

    Kabele, Petr; Žák, Jiří; Somr, Michael

    2017-06-01

    Gravity-driven failure of shallow magma chamber roofs and formation of collapse calderas are commonly accompanied by ejection of large volumes of pyroclastic material to the Earth's atmosphere and thus represent severe volcanic hazards. In this respect, numerical analysis has proven as a key tool in understanding the mechanical conditions of caldera collapse. The main objective of this paper is to find a suitable approach to finite-element simulation of roof fracturing and caldera collapse during inflation and subsequent deflation of shallow magma chambers. Such a model should capture the dominant mechanical phenomena, for example, interaction of the host rock with magma and progressive deformation of the chamber roof. To this end, a comparative study, which involves various representations of magma (inviscid fluid, nearly incompressible elastic, or plastic solid) and constitutive models of the host rock (fracture and plasticity), was carried out. In particular, the quasi-brittle fracture model of host rock reproduced well the formation of tension-induced radial and circumferential fractures during magma injection into the chamber (inflation stage), especially at shallow crustal levels. Conversely, the Mohr-Coulomb shear criterion has shown to be more appropriate for greater depths. Subsequent magma withdrawal from the chamber (deflation stage) results in further damage or even collapse of the chamber roof. While most of the previous studies of caldera collapse rely on the elastic stress analysis, the proposed approach advances modeling of the process by incorporating non-linear failure phenomena and nearly incompressible behaviour of magma. This leads to a perhaps more realistic representation of the fracture processes preceding roof collapse and caldera formation.

  13. Cuisine Preference of Local Tourists in San Juan, Batangas, Philippines

    Directory of Open Access Journals (Sweden)

    RYENE SELLINE B. KALALO

    2014-08-01

    Full Text Available This study aimed to determine the cuisine preference of the local tourist in San Juan, Batangas. More specifically, it aimed to describe the demographic profile of local tourist; to identify the preferred cuisine by different restaurants; to determine the significant difference when group according to demographic profile; and to determine the cuisine preference of local tourists in San Juan, Batangas. The research design used the descriptive method because it is the most appropriate method. It was found that the over-all assessment was frequent. Hamburger received the highest weighted mean followed by Sandwiches interpreted as frequent. Doughnut and Roasted Turkey got the lowest. Chinese Cuisine is frequently served. Lumpiang Shanghai has the highest weighted mean that is frequently offered and Siomai being the second highest. Siopao and Dumpling got the lowest weighted mean that makes it sometimes offered in every restaurant. Japanese cuisine has an over-all assessment of frequent. Tempura has the highest weighted mean followed by Teriyaki. Ramen has the second to the lowest weighted mean and Tonkatsu got the lowest. French Cuisine has a composite mean with an over-all assessment of sometimes. Mediterranean salad has the highest weighted followed by French Macaroons. Lamb and Ratatouille has the lowest weighted mean

  14. Juan O’Gorman. Formas de no ser arquitecto

    Directory of Open Access Journals (Sweden)

    Javier Jerez González

    2015-12-01

    Full Text Available La obra proyectada y construida por Juan O’Gorman a lo largo de su vida traza un recorrido largo y sincopado entre formas de entender la arquitectura totalmente antagónicas. Su primera etapa de radical racionalismo desarrolla, según procedimientos estrictamente técnicos, un lenguaje revolucionario basado en la austeridad y la precisión. A pesar de ello muchas de sus obras destacan por la plasticidad de sus composiciones volumétricas, la riqueza espacial o, incluso, por la creación de atmósferas oníricas. Los primeros años de frenética actividad dan paso a un periodo de voluntario alejamiento de la práctica profesional de la arquitectura: ni una sola obra, ni un solo proyecto durante cerca de 15 años. Tan solo su actividad docente le mantiene en contacto con el mundo de la arquitectura. Cuando Juan O’Gorman vuelve a ejercer como arquitecto, lo hace construyendo algunos de los iconos del movimiento de integración plástica de México: la biblioteca central de la UNAM y su casa en San Jerónimo. A pesar de las enormes diferencias, o más bien oposiciones, entre unos momentos y otros, puede identificarse una invariante clara como señal de identidad personal: una velada voluntad de no ser arquitecto

  15. Juan de Arfe Villafañe y Sebastiano Serlio

    Directory of Open Access Journals (Sweden)

    Heredia Moreno, Mª del Carmen

    2003-12-01

    Full Text Available Juan de Arfe's awareness and utilization of Italian art treatises, particularly that of Sebastiano Serlio, are analyzed in this study. The author demonstrates that Serlio's influence is perceptible in much of this artisan's production, from the Avila monstrance to that of Valladolid. It is especially manifest in Arfe's creations carried out in Seville, particularly in Books I and IV of his Varia Commensuracion and in the monstrance for the cathedral.

    En este artículo se analiza el conocimiento y la utilización de los tratadistas italianos, particularmente de Sebastiano Serlio, por parte de Juan de Arfe. También se tratará de demostrar que la influencia de Serlio se percibe en buena parte de la producción del artífice, desde la custodia de Ávila hasta la de Valladolid, aunque se manifiesta de manera especial en los trabajos que Arfe realizó en Sevilla, sobre todo en los Libros I y IV de la Varia Commensuracion y en la custodia de la catedral.

  16. SCAP optimization of the Pasajes de San Juan power station

    Energy Technology Data Exchange (ETDEWEB)

    Perez, L.; Perez, J.M.; Cerezo, J.; Catediano, J.; Martin-Sanchez, J.M. [Iberdrola, Bilbao (Spain)

    1995-08-01

    In July 1990 the company Iberduero, now Iberdrola, decided to carry out a development project using the Spanish technology SCAP in the Pasajes de San Juan power plant. This methodology, featured by the utilization of adaptive predictive control methodology, had been successfully applied in order to achieve the optimization of other industrial processes. The ultimate aim of this project was the replacement of the power station conventional control system, with a SCAP control system with a distributed structure able to optimize the electric energy generation process by optimizing power station operation, maximizing efficiency and working life, reducing maintenance costs, and increasing safety and availability. The project was divided into two stages to evaluate the quality of SCAP technology in the control and optimization of a power station. In the present report, the results obtained in the control of the most critical variables during the power station operation are gathered together. Beforehand, and in order to place these results in a suitable context, the project proceedings summarized in the following phases are considered: the SCAP technology; problems in a thermal power plant; and the Pasajes de San Juan power plant and its control system. The results are presented through comparative graphs that show the performance of the SCAP system as compared to the power station conventional control. 17 figs., 4 tabs., 11 refs.

  17. TRAFFIC SAFETY AND DRIVER EDUCATION IN SAN JUAN ARGENTINA

    Directory of Open Access Journals (Sweden)

    Arístides Osvaldo Fernández DE CIEZA

    2000-01-01

    Full Text Available With over 8,100 traffic fatalities in 1997 and an accident rate per 100 million vehicle kilometres travelled, approximately five times that of United States, Argentinean road authorities are now beginning to focus attention on traffic safety and driver education. One of the main problems in the search of causes for car accidents in Argentina is the lack of a reliable and updated data base. The results and conclusions presented in this paper are based on a thorough analysis of car accidents in the Province of San Juan, Argentina. A seven-year data base of car accidents has been compiled from police reports, including the results of traffic counts at intersections and other collision locations. In addition, topographic and filmed reports of such places and their surroundings bring about parameters such as stop lines, visibility triangles, road size, traffic light performance, etc., which allow to carrying out of a traffic flow analysis for proposing measures aiming to minimize accidents. For San Juan province, in general, the main causes are: high absolute car speeds, speed differences between vehicles, lack of good lighting, poor driving habits, lack of traffic control devices such as signs, signals, and an absence of road markings.

  18. Geothermal hydrology of Valles Caldera and the southwestern Jemez Mountains, New Mexico

    Science.gov (United States)

    Trainer, Frank W.; Rogers, Robert J.; Sorey, M.L.

    2000-01-01

    The Jemez Mountains in north-central New Mexico are volcanic in origin and have a large central caldera known as Valles Caldera. The mountains contain the Valles geothermal system, which was investigated during 1970-82 as a source of geothermal energy. This report describes the geothermal hydrology of the Jemez Mountains and presents results of an earlier 1972-75 U.S. Geological Survey study of the area in light of more recent information. Several distinct types of thermal and nonthermal ground water are recognized in the Jemez Mountains. Two types of near-surface thermal water are in the caldera: thermal meteoric water and acid sulfate water. The principal reservoir of geothermal fluids is at depth under the central and western parts of the caldera. Nonthermal ground water in Valles Caldera occurs in diverse perched aquifers and deeper valley-fill aquifers. The geothermal reservoir is recharged by meteorically derived water that moves downward from the aquifers in the caldera fill to depths of 6,500 feet or more and at temperatures reaching about 330 degrees Celsius. The heated geothermal water rises convectively to depths of 2,000 feet or less and mixes with other ground water as it flows away from the geothermal reservoir. A vapor zone containing steam, carbon dioxide, and other gases exists above parts of the liquid-dominated geothermal zone. Two subsystems are generally recognized within the larger geothermal system: the Redondo Creek subsystem and the Sulphur Creek subsystem. The permeability in the Redondo Creek subsystem is controlled by stratigraphy and fault-related structures. Most of the permeability is in the high-angle, normal faults and associated fractures that form the Redondo Creek Graben. Faults and related fractures control the flow of thermal fluids in the subsystem, which is bounded by high-angle faults. The Redondo Creek subsystem has been more extensively studied than other parts of the system. The Sulphur Springs subsystem is not as well

  19. Digital Geologic Map of Mount Mazama and Crater Lake Caldera, Oregon

    Science.gov (United States)

    Bacon, C. R.; Ramsey, D. W.

    2002-12-01

    Crater Lake caldera formed ~7700 cal yr B.P. by the eruption of 50 km3 of mainly rhyodacitic magma and the resulting collapse of Mount Mazama. A new 1:24,000-scale digital geologic map compiled in ArcInfo depicts the geology of this volcanic center, peripheral volcanoes, the caldera walls and floor, and superjacent pyroclastic, talus, and glacial deposits. The geology of the caldera walls was mapped in the field on photographs taken from the lake (see accompanying abstract and poster, "Geologic panoramas of the walls of Crater Lake caldera,Oregon"); the geology of the flanks of Mount Mazama and the surrounding area was mapped on aerial photographs; and features of the caldera floor were mapped on a multibeam echo-sounding bathymetric map (Gardner et al., 2001; Bacon et al., 2002). Volcanic map units are defined on the basis of chemical composition and petrographic characteristics. Map unit colors were chosen to indicate the compositions of volcanic rocks, cooler colors for mafic units and warmer colors for silicic units. Map unit color intensity indicates age, with more intense coloring for younger units. Ages of many units have been determined by K-Ar and 40Ar/39Ar dating by M.A. Lanphere. Several undated units have been correlated using paleomagnetic secular variation measurements by D.E. Champion. Crystallization facies of some of the larger lava flows are mapped separately (e.g., vitrophyre, felsite, carapace), as are breccia and lava facies of submerged postcaldera volcanoes. Also shown on the caldera floor are landslide (debris avalanche) and sediment gravity-flow deposits. A major north-south normal fault system traverses the map area west of the caldera and displaces dated late Pleistocene lava flows, allowing determination of a long-term slip rate of ~0.3 mm/yr (Bacon et al., 1999). Faults bounding large downdropped blocks of the south caldera wall are also shown. Where practical, lava flow margins are represented as intra-unit contacts. A number of small

  20. Cluster headache

    Science.gov (United States)

    Histamine headache; Headache - histamine; Migrainous neuralgia; Headache - cluster; Horton's headache; Vascular headache - cluster ... A cluster headache begins as a severe, sudden headache. The headache commonly strikes 2 to 3 hours after you fall ...

  1. Cluster Forests

    CERN Document Server

    Yan, Donghui; Jordan, Michael I

    2011-01-01

    Inspired by Random Forests (RF) in the context of classification, we propose a new clustering ensemble method---Cluster Forests (CF). Geometrically, CF randomly probes a high-dimensional data cloud to obtain "good local clusterings" and then aggregates via spectral clustering to obtain cluster assignments for the whole dataset. The search for good local clusterings is guided by a cluster quality measure $\\kappa$. CF progressively improves each local clustering in a fashion that resembles the tree growth in RF. Empirical studies on several real-world datasets under two different performance metrics show that CF compares favorably to its competitors. Theoretical analysis shows that the $\\kappa$ criterion is shown to grow each local clustering in a desirable way---it is "noise-resistant." A closed-form expression is obtained for the mis-clustering rate of spectral clustering under a perturbation model, which yields new insights into some aspects of spectral clustering.

  2. Understanding the initiation and development of explosive Plinian eruptions: the conduit processes, eruption dynamics and dispersal processes of the ignimbrite and caldera-forming Lower Pumice 1 (184 ka) and Lower Pumice 2 (172 ka) eruptions, Santorini Caldera, Greece

    OpenAIRE

    Simmons, Jack Michael

    2017-01-01

    In this thesis, the internal stratigraphy, facies, and facies architecture of the rhyodacitic 184 ka Lower Pumice 1 (LP1) and 172 ka Lower Pumice 2 (LP2) eruption sequences, erupted from Santorini Caldera, Greece, are reassessed as the basis for understanding the initiation and development of caldera-forming Plinian eruptions, including the changing conditions of the magmatic system, the conduit and eruption processes, the transition between eruption phases and ultimately the evolution of the...

  3. Star Clusters

    OpenAIRE

    Gieles, M.

    1993-01-01

    Star clusters are observed in almost every galaxy. In this thesis we address several fundamental problems concerning the formation, evolution and disruption of star clusters. From observations of (young) star clusters in the interacting galaxy M51, we found that clusters are formed in complexes of stars and star clusters. These complexes share similar properties with giant molecular clouds, from which they are formed. Many (70%) of the young clusters will not survive the fist 10 Myr, due to t...

  4. How medium-size resurgent calderas work: the case of Pantelleria, Ischia and the unrest Campi Flegrei structures

    Science.gov (United States)

    Orsi, Giovanni; Civetta, Lucia; Arienzo, Ilenia; Carandente, Antonio; D'Antonio, Massimo; de Vita, Sandro; di Renzo, Valeria; di Vito, Mauro; Marotta, Enrica; Belviso, Pasquale

    2010-05-01

    Assessment of time and space relationships among magmatism, volcanism, and resurgence of medium-size calderas is a necessary tool to formulate a general model for their dynamics which also permits to forecast their evolution. To define a general hypothesis for the Campi Flegrei caldera, in a persistent state of unrest, the Ischia and Pantelleria medium-size resurgent structures, in variable stages of evolution, have been investigated. In particular some parameters such as the structural and volcanological evolution, with emphasis on resurgence dynamics and coeval volcanism, and the evolution, present state and role of the magmatic system in resurgence, have been defined. For the Campi Flegrei caldera, the data collected during unrest episodes have also been taken into account. This innovative approach adds a time-perspective on how resurgent calderas behave. The proposed general hypothesis will help in long- and short-term volcanic hazards assessment and will support Civil Defence Authorities in elaborating actions devoted to volcanic risk reduction.

  5. Understanding the link between circumferential dikes and eruptive fissures around calderas based on numerical and analog models

    Science.gov (United States)

    Corbi, Fabio; Rivalta, Eleonora; Pinel, Virginie; Maccaferri, Francesco; Acocella, Valerio

    2016-06-01

    Active calderas are seldom associated with circumferential eruptive fissures, but eroded magmatic complexes reveal widespread circumferential dikes. This suggests that, while the conditions to emplace circumferential dikes are easily met, mechanisms must prevent them from reaching the surface. We explain this discrepancy with experiments of air injection into gelatin shaped as a volcano with caldera. Analog dikes show variable deflection, depending on the competition between overpressure, Pe, and topographic unloading, Pl; when Pl/Pe = 4.8-5.3, the dikes propagate orthogonal to the least compressive stress. Due to the unloading, they become circumferential and stall below the caldera rim; buoyancy is fundamental for the further rise and circumferential fissure development. Numerical models quantitatively constrain the stress orientation within the gelatin, explaining the observed circumferential dikes. Our results explain how dikes propagate below the rim of felsic and mafic calderas, but only in the latter they are prone to feed circumferential fissures.

  6. Geologic field trip guide to Mount Mazama and Crater Lake Caldera, Oregon

    Science.gov (United States)

    Bacon, Charles R.; Wright, Heather M.

    2017-08-08

    Crater Lake partly fills one of the most spectacular calderas of the world—an 8 by 10 kilometer (km) basin more than 1 km deep formed by collapse of the Mount Mazama volcano during a rapid series of explosive eruptions ~7,700 years ago. Having a maximum depth of 594 meters (m), Crater Lake is the deepest lake in the United States. Crater Lake National Park, dedicated in 1902, encompasses 645 square kilometers (km2) of pristine forested and alpine terrain, including the lake itself, and virtually all of Mount Mazama. The geology of the area was first described in detail by Diller and Patton (1902) and later by Williams (1942), whose vivid account led to international recognition of Crater Lake as the classic collapse caldera. Because of excellent preservation and access, Mount Mazama, Crater Lake caldera, and the deposits formed by the climactic eruption constitute a natural laboratory for study of volcanic and magmatic processes. For example, the climactic ejecta are renowned among volcanologists as evidence for systematic compositional zonation within a subterranean magma chamber. Mount Mazama’s climactic eruption also is important as the source of the widespread Mazama ash, a useful Holocene stratigraphic marker throughout the Pacific Northwest United States, adjacent Canada, and offshore. A detailed bathymetric survey of the floor of Crater Lake in 2000 (Bacon and others, 2002) provides a unique record of postcaldera eruptions, the interplay between volcanism and filling of the lake, and sediment transport within this closed basin. Knowledge of the geology and eruptive history of the Mount Mazama edifice, enhanced by the caldera wall exposures, gives exceptional insight into how large volcanoes of magmatic arcs grow and evolve. In addition, many smaller volcanoes of the High Cascades beyond the limits of Mount Mazama provide information on the flux of mantle-derived magma through the region. General principles of magmatic and eruptive processes revealed by

  7. Evolution of the Creede Caldera and its relation to mineralization in the Creede mining district, Colorado

    Science.gov (United States)

    Barton, Paul B.; Rye, Robert O.; Bethke, Philip M.

    2000-01-01

    At 25 Ma a major epithermal silver and base metal deposit formed in rhyolitic welded tuff near Creede, Colorado. Nearly 24000 metric tons of silver, appreciable lead, and small amounts of zinc, copper, and gold, have been produced from large, crustified veins under Bachelor and Bulldog Mountains north and northwest of Creede. Prior geologic, hydrologic, and stable-isotope studies showed that ore deposition was associated with the mixing and boiling of waters from diverse sources and suggester that a critical part of the ore-forming fluid may have originated within the ancient lake and sediments of the lacustrine Creede Formation that filled the Creede caldera. Two drill holes that sampled the heretofore hidden lower half of the Creede Formation are the focus of this book. The Creede caldera formed at 26.9 Ma within a high constructional plateau of silicic ashflows that covered and were sporadically interlayed with, intermediate lavas and lahars from large stratovolcanoes. The Creede caldera lake had an inflow evaporation balance that did not permit rapid filling to create a brim-full deep lake. Thus salts were evaporatively concentrated; but, with the exception of possible gypsum, no evaporite minerals preserved. Cool springs deposited travertine as mounds and contributed to limestone interlaminations within the sediment. The lake bottom was anoxic, and bacterial reduction of sulfate led to extreme sulfur isotopic fractionation in diagenetic pyrite. The caldera gradually resurged, converting the initial equant lake into an arcuate moat. Resurgent doming, alluvial fans, lacustrine sediments, ashfalls, and lava domes displaced water, lifted the lake so that it overlapped what later became the southern edge of the mineralized are, and eventually filled the basin. At 25.1 Ma an unseen pluton intruded beneath the northen part of the Creede district and created a convecting olume that drew in brine from the Creede caldera fill, meteotic water from highlands to the north

  8. The eruption, pyroclastic flow behaviour, and caldera in-filling processes of the extremely large volume (> 1290 km3), intra- to extra-caldera, Permian Ora (Ignimbrite) Formation, Southern Alps, Italy

    Science.gov (United States)

    Willcock, M. A. W.; Cas, R. A. F.; Giordano, G.; Morelli, C.

    2013-09-01

    The Permian Ora Formation (277-274 Ma) preserves the products of the Ora caldera 'super-eruption', Northern Italy. The stratigraphic architecture of the exceptionally well preserved intra-caldera succession provides evidence for caldera collapse at the onset of the eruption, a multiple discharge point, fissure eruption style, and progressive, incremental caldera in-filling by numerous pyroclastic flow pulses within the caldera. The ignimbrites of the Ora Formation are voluminous (> 1290 km3), crystal-rich (~ 25 to 55%), and ubiquitously welded. The Ora Formation has been divided into four members (a-d), which also define the principal eruption phases. The eruption proceeded in four main stages: (1) early caldera collapse and vent opening, producing locally distributed, basal co-ignimbrite lithic breccia (member a); (2) vent clearing, which produced the eutaxitic, lithic-rich ignimbrite and minor thin ground and ash-cloud surge deposits (member b); (3) waxing and steady eruption, which produced the dominant eutaxitic, coarse-crystal-rich ignimbrite, with local lithic-rich and fine-crystal-rich ignimbrite and minor surge deposits (member c); and (4) waning eruption, recorded by the eutaxitic, fine-crystal-rich ignimbrite, with local lithic-rich ignimbrite deposits (member d).

  9. Bedrock aquifers of eastern San Juan County, Utah

    Science.gov (United States)

    Avery, Charles

    1986-01-01

    This study is one of a series of studies appraising the waterbearing properties of the Navajo Sandstone and associated formations in southern Utah.  The study area is about 4,600 square miles, extending from the Utah-Arizona State line northward to the San Juan-Grand County line and westward from the Utah-Colorado State line to the longitude of about 109°50'.Some of the water-yielding formations are grouped into aquifer systems. The C aquifer is comprised of the DeChelly Sandstone Member of the Cutler Formation.  The P aquifer is comprised of the Cedar Mesa Member of the Cutler Formation and the undifferentiated Cutler Formation. The N aquifer is comprised of the sedimentary section that includes the Wingate Sandstone, Kayenta Formation, Navajo Sandstone, Carmel Formation, and Entrada sandstone.  The M aquifer is comprised of the Bluff Sandstone Member and other sandstone units of the Morrison Formation.  The D aquifer is comprised of the Burro Canyon Formation and Dakota Sandstone.  Discharge from the ground-water reservoir to the San Juan River between gaging stations at Four Corners and Mexican Hat is about 66 cubic feet per second.The N aquifer is the main aquifer in the study area. Recharge by infiltration of precipitation is estimated to be 25,000 acre-feet per year.  A major ground-water divide exists under the broad area east of Monticello.  The thickness of the N aquifer, where the sedimentary section is fully preserved and saturated, generally is 750 to 1,250 feet.   Hydraulic conductivity values obtained from aquifer tests range from 0.02 to 0.34 foot per day.  The total volume of water in transient storage is about 11 million acre-feet. Well discharge somewhat exceeded 2,340 acre-feet during 1981.  Discharge to the San Juan River from the N aquifer is estimated to be 6.9 cubic feet per second. Water quality ranges from a calcium bicarbonate to sodium chloride type water

  10. Postcaldera volcanism and hydrothermal activity revealed by autonomous underwater vehicle surveys in Myojin Knoll caldera, Izu-Ogasawara arc

    Science.gov (United States)

    Honsho, Chie; Ura, Tamaki; Kim, Kangsoo; Asada, Akira

    2016-06-01

    Myojin Knoll caldera, one of the submarine silicic calderas lying on the volcanic front of the northern Izu-Ogasawara arc, has attracted increasing attention since the discovery of a large hydrothermal field called the Sunrise deposit. Although numerous submersible surveys have been conducted in Myojin Knoll caldera, they have not sufficiently explored areas to produce a complete picture of the caldera and understand the origin of the Sunrise deposit. We conducted comprehensive deep-sea surveys using an autonomous underwater vehicle and obtained high-resolution bathymetric and magnetic data and sonar images from ~70% of the caldera. The detailed bathymetric map revealed that faulting and magma eruptions, possibly associated with an inflation-deflation cycle of the magma reservoir during postcaldera volcanism, had generally occurred in the caldera wall. The main dome of the central cone was covered with lava flows and exhibits exogenous growth, which is unusual for rhyolitic domes. The magnetization distribution in the central cone indicates preferential magma intrusion along a NW-SE direction. It is presumed that magma migrated along this direction and formed a rhyolite dome at the foot of the southeastern caldera wall, where the Sunrise deposit occurs. The Sunrise deposit is composed mainly of three ridges extending in slope directions and covers ~400 × ~400 m. Magnetization reduction in the deposit area is small, indicating that the alteration zone beneath the Sunrise deposit is slanting rather than vertical. It is presumed that several slanting and near-vertical volcanic vents serve as pathways of hydrothermal fluid in Myojin Knoll caldera.

  11. Plio-Pleistocene volcanic history of the Ahuachapan geothermal system, El Salvador: the Concepcion de Ataco caldera

    Energy Technology Data Exchange (ETDEWEB)

    Partida, Eduardo Gonzalez; Rodriguez, Vicente Torres; Birkle, Peter [Instituto de Investigaciones Electricas (IIE), Dept. de Geotermia, Cuernavaca, Morelos (Mexico)

    1997-12-01

    The Concepcion de Ataco caldera in the Ahuachapan-Chipilapa region is part of the southern, Plio-Pleistocene volcanic belt that borders the Central Graben of El Salvador. About 17 km{sup 3} of primitive lavas erupted between 1.7 and 0.77 Ma, covering basaltic-andesitic lavas and older agglomerates forming the Cuyanausul, Apaneca and Empalizada volcanoes. These lavas preceded the evacuation of 63 km{sup 3} of silicic pyroclastics (i.e. breccias, surge deposits, and ignimbrites) associated with the main caldera cycle. The eruption of this pyroclastic material led to the collapse of a 5 km by 3.5 km caldera between the times of the youngest pre-caldera eruptions (0.77 Ma) and the intrusion of the Himalaya dome (0.28 Ma). The caldera collapse was reactivated at its north eastern flank by a new eruption of pyroclastics of limited areal distribution. These distinctive pyroclastics correspond to laminated tuffs (Cebra tuffs). Domes of dacitic-to-andesitic composition erupted along the caldera border as well as within it. Their magmatism is calc-alkaline; their ages vary between 0.28 and 0.1 Ma. Three phreatic explosions, whose craters are in the eastern part of the Concepcion de Ataco caldera structure, only deposited debris locally. A hydrothermal systems was emplaced during the final stage of the post-magmatic activity, evidenced by areas of hydrothermal alteration and surface manifestations. Four main fault systems, oriented NE-SW, NW-SE, NNW-SSE, and semicircular, have been identified. These faults created relatively high-permeability regions within the caldera and nearby grabens, that are favorable for the development of geothermal systems. (Author)

  12. Norma y uso: las ideas educativas en Juan de Robles / Etymology and use: The educational ideas of Juan de Robles

    Directory of Open Access Journals (Sweden)

    Alejandro Gómez Camacho

    2014-10-01

    Full Text Available Resumen: Juan de Robles es uno de los más brillantes humanistas de nuestro Siglo de Oro, entre cuyas obras destaca El culto sevillano (1631. En este trabajo se analizan sus ideas educativas, centradas en la relación entre la ortografía y el aprendizaje de la escritura. Entre las ideas pedagógicas de Juan de Robles es muy relevante el rechazo vehemente de la ortografía fonética, entre otros motivos, porque no favorecía el aprendizaje de la lectura y de la escritura; en consecuencia, censura la creación de nuevas letras y de un nuevo orden para el alfabeto español. Los ortógrafos defensores de la ortografía fonética en el siglo XVII argumentaban que la nueva escritura permitiría a los niños aprender a leer y a escribir con más rapidez y facilidad; así como que la creación de nuevas letras y el establecimiento de un nuevo orden del alfabeto facilitarían su enseñanza. Frente a estas pretensiones, Juan de Robles defendió el alfabeto tradicional y la ortografía etimológica de origen latino porque eran los instrumentos adecuados para la alfabetización en nuestra lengua. También critica los colegios jesuitas y la Ratio Studiorum; las principales discrepancias entre la pedagogía de la Compañía de Jesús y las ideas educativas de Juan de Robles podrían concretarse en la primacía del español sobre el latín, y en el uso de cuentos y refranes populares para la educación en El culto sevillano. En conclusión, con la obra de Juan de Robles se incorpora definitivamente el argumento pedagógico que relaciona la ortografía y la gramática españolas con el aprendizaje de la lectura y de la escritura a la polémica sobre la ortografía española del Siglo de Oro, en defensa de la ortografía etimológica frente a las pretensiones de imponer una ortografía fonética en el primer tercio del siglo XVII. Abstract: Juan de Robles is considered one of the main humanists in the Spanish Golden Century. The most important of his works is

  13. Pyroclastic deposits as a guide for reconstructing the multi-stage evolution of the Somma-Vesuvius Caldera

    Science.gov (United States)

    Cioni, Raffaello; Santacroce, Roberto; Sbrana, Alessandro

    The evolution of the Somma-Vesuvius caldera has been reconstructed based on geomorphic observations, detailed stratigraphic studies, and the distribution and facies variations of pyroclastic and epiclastic deposits produced by the past 20,000years of volcanic activity. The present caldera is a multicyclic, nested structure related to the emptying of large, shallow reservoirs during Plinian eruptions. The caldera cuts a stratovolcano whose original summit was at 1600-1900m elevation, approximately 500m north of the present crater. Four caldera-forming events have been recognized, each occurring during major Plinian eruptions (18,300 BP "Pomici di Base", 8000 BP "Mercato Pumice", 3400 BP "Avellino Pumice" and AD 79 "Pompeii Pumice"). The timing of each caldera collapse is defined by peculiar "collapse-marking" deposits, characterized by large amounts of lithic clasts from the outer margins of the magma chamber and its apophysis as well as from the shallow volcanic and sedimentary units. In proximal sites the deposits consist of coarse breccias resulting from emplacement of either dense pyroclastic flows (Pomici di Base and Pompeii eruptions) or fall layers (Avellino eruption). During each caldera collapse, the destabilization of the shallow magmatic system induced decompression of hydrothermal-magmatic and hydrothermal fluids hosted in the wall rocks. This process, and the magma-ground water interaction triggered by the fracturing of the thick Mesozoic carbonate basement hosting the aquifer system, strongly enhanced the explosivity of the eruptions.

  14. Urban ecology of Triatoma infestans in San Juan, Argentina

    Directory of Open Access Journals (Sweden)

    Silvana L Vallvé

    1996-08-01

    Full Text Available This study was performed in an urban neighborhood of the capital city of the province of San Juan, Argentina. Erected as a housing complex, the place consists of 768 flats distributed in buildings of three and seven floors each. A survey was carried out in 33% of the dwellings, enquiring about the number of Triatoma infestans found indoors, stage of the bug development - nymph or adult - and how these insects had entered their homes. Adult T.infestans were found on all floors; 163 people (64% had found them at least once, and 130 (51% several times. Dispersal flight seems to have been the main mechanism of infestation by adult bugs in this area, and a total of 51% of the surveyed inhabitants reported that the insects had flown into their flats.

  15. Lengua y conocimiento en Juan de Valdés

    OpenAIRE

    2011-01-01

    Na presente pesquisa, é abordada a concepção de língua e conhecimento presente na atividade do biblicista espanhol Juan de Valdés (Cuenca, ca. 1500- Nápoles, 1541). Com tal fim, são analisados os critérios estilísticos propostos pelo autor no Diálogo de la Lengua, composto em torno de 1535 e dedicado ao uso e aprendizado da língua vernácula. Adotando como fundamentação teórica a hermenêutica do filósofo alemão Hans-George Gadamer e realizando uma revisão dos principais estudos sobre o autor e...

  16. Juan Manuel Roca: desde la patria de la infancia

    Directory of Open Access Journals (Sweden)

    Guillermo Linero Montes

    2003-05-01

    Full Text Available Desde que publicó Memoria del agua, su primer libro de poesía, en 1973, Juan Manuel Roca (Medellín, 1946 ha sido uno de los poetas colombianos más representativos de su época. Su reputación, alentada como ninguna otra por el interés de los jóvenes, tiene la singularidad de provenir de un hecho afortunado: de la exacta simbiosis entre los contenidos, la presentación y expresión de su poesía, y entre las necesidades espirituales de una sociedad en crisis. Un maridaje tanto acorazado como maleable, pues le ha permitido resistir, asimilándolas, las cardiacas transformaciones recientes.

  17. Diagnostic electron microscopy and the influence of Dr. Juan Rosai.

    Science.gov (United States)

    Wick, Mark R

    2016-09-01

    Transmission electron microscopy (TEM) was introduced by Ruska and Knoll as a laboratory technique in 1933. Thereafter, several decades passed before the methods required for its optimal implementation were fully developed. Early uses of TEM were in Botany, rather than in Medicine; however, isolated publications did catalog the ultrastructural characteristics of several individual human tumor types. Finally, in 1968, Rosai and Rodriguez authored an important article, introducing the concept that TEM could be used for the differential diagnosis of histologically similar neoplasms. This publication heralded the steadily increasing application of TEM in anatomic pathology over the following decade, including continuing contributions by Dr. Juan Rosai. This brief review summarizes his influence on clinical electron microscopy, and lists some of the lesions for which that procedure is still a useful means of analysis.

  18. Thermal performance of neighbourhood prototypes built in San Juan, Argentina

    Energy Technology Data Exchange (ETDEWEB)

    Blasco Lucas, I.; Albarracin, O.; Carestia, C. [Universidad Nacional de San Juan (Argentina)

    2000-07-01

    The research work produces a contrasted quantification of the thermal performance of inhabited dwelling houses built in different neighborhoods of San Juan, Argentina. They correspond to five prototypes aimed at families with low and medium income levels, massive spread in their versions with two or three bedrooms. From all of them it can be obtained yearly energy consumption indexes per unit area, under homogeneous conditions respect to minimal thermal comfort levels and inhabitant behaviors. The evolution of their inner temperatures and relative humidity with and without auxiliary thermal conditioning is analyzed. Conclusions assess the deficit level of the studied prototypes contrasted to international standards and the global valuation of the impact on the sectorial annual energy consumption caused by them. (author)

  19. Juan Antonio Rubio appointed as Director-General of CIEMAT

    CERN Multimedia

    2004-01-01

    Juan Antonio Rubio, Head of CERN's ETT unit (Education and Technology Transfer) has been appointed by the Spanish Ministry of Education and Science as the Director General of the Research Centre for Energy, Environment and Technology, CIEMAT. Dr Rubio's career began at the Spanish Nuclear Energy Commission where he held the posts of Investigator, Head of the High Energy Group and Head of Nuclear Physics and High Energy Division. Later, he was named Director of the Department of Basic Investigation and Scientific Director of the CIEMAT. In 1987 he joined CERN as Scientific Adviser to the Director General and Group Leader of the Scientific Assessment Group. Up to now, Dr Rubio has been the Head of the ETT unit, as well as Coordinator for Latin America and Commissioner for the 50th Anniversary of the Organization. He was born on 4 June 1944 in Madrid, and holds a Doctorate in Physical Sciences from the Universidad Complutense de Madrid.

  20. Sea level Variability and Juan de Fuca Bathymetry

    Science.gov (United States)

    Huybers, P. J.; Boulahanis, B.; Proistosescu, C.; Langmuir, C. H.; Carbotte, S. M.; Katz, R. F.

    2015-12-01

    That deglaciation influences mid-ocean ridge volcanism is well established for Iceland, where depressurization associated with melting a ~2 km ice cap led to order of magnitude increases in volcanism during the last deglaciation. The case was also made that the more subtle ~100 m changes in sea level that accompany glacial cycles have identifiable implications for undersea mid-ocean ridge systems using both models and data from the Australian-Antarctic Ridge (Crowley et al., 2015). Sea level rising at ~1 cm/year during deglaciation leads to an expectation of ~10% decreases in melt production at ridges, given mantle upwelling rates of ˜3 cm/yr at intermediate spreading ridges and mantle density being ~3 times that of seawater. The implications of variations in melt production for bathymetry, however, involve numerous considerations, including whether melt signals are cancelled within the melt column, appreciably alter accretionary or fault processes, and have identifiable surface expressions. Further empirical assessment of bathymetry is thus useful for purposes of confirming patterns and constraining processes. Here we report on spectral analyses of bathymetry recently acquired from the Juan de Fuca ridge between 44°30'N and 45°15'N during the SeaVOICE expedition. Multibeam swath sonar data were acquired with an EM122 sonar insonfiying seafloor to crustal ages of ˜2 ma with 35 m spatial resolution. We examine (1.) the statistical significance of concentrations of bathymetric variability at the 100 ky, 41 ky, and 23 ky periods characteristic of late-Pleistocene sea level variability; (2.) whether sea level responses are primarily at 41 ky periods in crust accreted during the early Pleistocene, when global sea level variations were primarily at this period; and (3.) if sea level responses are superimposed on bathymetry variations or, instead, align with fault features. We also note that Juan de Fuca's proximity to the Cordilleran Ice Sheet implies that regional

  1. La visión exiliar de Juan Gelman

    Directory of Open Access Journals (Sweden)

    María Ángeles PÉREZ LÓPEZ

    2009-11-01

    Full Text Available RESUMEN: En el poeta argentino Juan Gelman (1930, la traumática experiencia del exilio no viene a conformar sólo una parte importante de su producción, la comprendida entre 1975 y 1988, sino que además, y fundamentalmente, establece el desplazamiento hacia zonas de sentido en las que el lenguaje es también «el expulsado», el «vacío-pasión», «la marca de una ausencia que no cesa de no escribirse», en sus propios términos. De ahí que resulte tan relevante su encuentro con la poesía mística española, en la medida en que el místico es un exiliado de Dios (Citas y Comentarios, 1982, y con la poesía sefardí (Dibaxu, 1994, «como si la soledad extrema del exilio me empujara a buscar raíces en la lengua, las más profundas y exiliadas de la lengua».ABSTRACT: In the life of the Argentine poet Juan Gelman (1930, the traumatic experience of exile informs not only an important part of his production, the one that falls between 1975 and 1988, but also, and fundamentaly, it establishes the displacement to areas of significance in which language is also «the rejected», the «empty-passion», «the sign of an absence that does not finish writing itself», in his own words. From this, one discovers the importance of his encounter with Spanish mystical poetry, to the extent that the mystic is estranged from God (Citations and Comentaries, 1982 and with Sephardic poetry (Dibaxu, 1994, «as if the extreme solitude of exile compelled me to search for roots in language, the deepest and most estranged from language».

  2. The Campi Flegrei caldera (Italy): Formation and evolution in interplay with sea-level variations since the Campanian Ignimbrite eruption at 39 ka

    Science.gov (United States)

    Steinmann, Lena; Spiess, Volkhard; Sacchi, Marco

    2016-11-01

    To date, the origin of the Campi Flegrei caldera is still under debate and may be related to (1) a single caldera collapse associated with the Neapolitan Yellow Tuff (NYT) eruption, (2) two subsequent caldera collapses associated with the NYT and the preceding Campanian Ignimbrite (CI) eruptions forming a nested-caldera complex, or (3) not related to a caldera collapse after all. Here, we study the submerged portion of the caldera, which has favored a marine depositional setting and, thus, represents an ideal location for the reconstruction of its formation history, utilizing multichannel seismic data. Volcanic deposits and edifices were seismically distinguished from sedimentary successions, and the stratigraphy could be refined and extended back to the Campanian Ignimbrite eruption at 39 ka. High-resolution multichannel reflection seismic data revealed the existence of a nested-caldera complex formed during the CI eruption at 39 ka and the more recent NYT eruption at 15 ka. A ring-fault bounding an inner caldera collapse structure was clearly imaged. It appears that this inner ring-fault was initially activated during the CI caldera collapse and later reactivated during the NYT caldera collapse with different amounts of subsidence. The NYT caldera probably formed during an asymmetrical collapse with a maximum subsidence of 75 m in the offshore portion. The vertical displacement related to the CI caldera collapse may be significantly larger. The submerged caldera depression accommodates post-eruption sediments. Within this high-resolution archive, two major unconformities developed at 8.6 ka and 5 ka, when resurgence-related uplift exceeded the rate of sea-level rise concurrent with the emersion of the La Starza terrace. A previously unknown post-collapse submarine volcanic mound located between Nisida Island and Nisida Bank probably formed between 4.8 and 3.7 ka. Also, the Penta Palummo Bank appears to be constructed of at least two monogenetic volcanic edifices

  3. Interpreting compositional zonation of the Zaragoza ignimbrite from Los Humeros caldera, Central Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Carrasco-Nunez, Gerardo [Centro de Geociencias, UNAM, Campus Juriquilla, Queretaro, Qro. (Mexico); McCurry, Michael [Department of Geology, Idaho State University, Pocatello, ID (United States); Branney, Michael J [Department of Geology, University of Leicester, Leicester (United Kingdom)

    2008-10-01

    Compositional zonation in ignimbrites is relatively common, and is often inferred to record gradual withdrawal by an eruption of a density-stratified magma chamber (with silicic magma towards the top and more dense, mafic magma at the bottom). We show that this model does not match observations at the ca. 0.1 Ma Zaragoza ignimbrite from Los Humeros caldera in central Mexico. Detailed petrologic studies reveal a more complex scenario: the ignimbrite exhibits a 'double' vertical zonation based on the compositions of pumice lapilli. We present evidence for mingling and limited mixing occurred during or immediately before the caldera-forming eruption. One possibility to explain the observations is that the ignimbrite eruption occurred in response to intrusion of a hybridized andesitic magma into a rhyodacitic magma chamber.

  4. Interpreting compositional zonation of the Zaragoza ignimbrite from Los Humeros caldera, Central Mexico

    Science.gov (United States)

    Carrasco-Núñez, Gerardo; McCurry, Michael; Branney, Michael J.

    2008-10-01

    Compositional zonation in ignimbrites is relatively common, and is often inferred to record gradual withdrawal by an eruption of a density-stratified magma chamber (with silicic magma towards the top and more dense, mafic magma at the bottom). We show that this model does not match observations at the ca. 0.1 Ma Zaragoza ignimbrite from Los Humeros caldera in central Mexico. Detailed petrologic studies reveal a more complex scenario: the ignimbrite exhibits a `double' vertical zonation based on the compositions of pumice lapilli. We present evidence for mingling and limited mixing occurred during or immediately before the caldera-forming eruption. One possibility to explain the observations is that the ignimbrite eruption occurred in response to intrusion of a hybridized andesitic magma into a rhyodacitic magma chamber.

  5. Alkali and alkaline earth element geochemistry of Los Humeros Caldera, Puebla, Mexico

    Science.gov (United States)

    Verma, Surendra P.

    1984-03-01

    Results of the measurements of alkali (K, Rb and Cs) and alkaline earth (Ba and Sr) elements on seven pre-caldera and twenty post-caldera samples of Los Humeros volcanics (Pliocene to Recent) are described. These data are interpreted in terms of the known solid-liquid partition coefficients. It appears that fractional crystallization is a dominant petrogenetic process and is controlled by the observed modal phases, namely plagioclase, olivine and clinopyroxene (in decreasing importance), and perhaps, in addition, biotite and titanomagnetite in the later stages of the differentiation sequence. The available major element chemistry and mass-balance calculations support these conclusions. Sr and Nd isotopic data further suggest that these magmas were generated in the underlying mantle, fractionated in a shallow-level magma chamber and underwent very insignificant sialic contamination before eruption.

  6. The structural setting of the Ischia Island Caldera (Italy): first evidence from seismic and gravity data

    Science.gov (United States)

    Capuano, Paolo; De Matteis, Raffaella; Russo, Guido

    2015-09-01

    Ischia Island is one of the active volcanoes of the Neapolitan area (Italy). Hazard assessment of active, densely populated volcano is primarily based on knowledge of the volcano's past behaviour and of its present state. As a contribution to the definition of the present structural setting of Ischia Island, we constructed a new model of the shallow crust using geophysical data: seismic wave travel times and Bouguer anomaly data. We analysed these data sets through seismic tomography and gravity data inversion. The main results inferable from the 3D seismic and gravity images are the definition of the caldera rim along the perimeter of the island, as hypothesized by many authors, and the presence of a high velocity and density area inside the caldera consistent with extension of the resurgent block that characterizes the recent deformation of the island.

  7. 3D Imaging of Brittle/Ductile transition of the crust beneath the resurgent calderas

    Science.gov (United States)

    Tizzani, P.; Castaldo, R.; Pepe, S.; Solaro, G.

    2012-04-01

    Rheology is a crucial factor to understand the mechanical behaviour and evolution of the crust in young and tectonically active belts. The aim of this paper is to investigate the rheological properties of the crust beneath resurgent calderas as Long Valley caldera (California USA) and Campi Flegrei (Southern Italy). Through the rheological proprieties of the calderas area, we highlight the driving process that determine the cut off of the local seismicity [K. Ito, 1993]. In this context, we consider the thermal proprieties and mechanical heterogeneity of the crust in order to develop a 3D conductive time dependent thermal model of the upper crust beneath the two calderas. More specifically we integrate geophysical information (gravimetric, seismic and boreholes data) available for the considered area in FEM environment [Manconi A. et al., 2010]. We performed a numerical solution of Fourier equation to carry out an advance optimization of the real measured data. We produce a set of forward models and propose, in order to analyse and solve the statistical problem, the Monte Carlo optimization procedures as Genetic Algorithm [Manconi A. et al., 2009]. In particular we search for the heat production, the volume source distribution and the surface emissivity parameters that providing the best-fit of the geothermal profiles data measured at boreholes, by solving the non stationary heat flow equation (Campanian Ignimbrite eruption about 40 kyr for Campi Flegrei caldera and Bishop tuff eruption about 700 kyr for Long Valley caldera). The performed thermal fields allow us to obtain the rheological stratification of the crust beneath two resurgent calderas; the models suggest that the uprising of a ductile layer which connects the upper mantle to the volcanic feeding system could determine the stress conditions that controlled the distribution of seismicity. In fact, the computed 3D imaging of Brittle/Ductile transition well agrees with the seismic hypocentral distribution

  8. Zircon oxygen isotopes reveal Ivrea-Verbano Zone source characteristics of the Sesia Valley Caldera

    Science.gov (United States)

    Economos, R. C.; Quick, J. E.; Sinigoi, S.; de Silva, S. L.

    2013-12-01

    The Sesia Valley, in the Italian Alpine foothills, contains >14 km diameter caldera adjacent to and structurally shallower than the famous Ivrea-Verbano Zone deep crustal section. The caldera and its associated eruptive sequence presents opportunity to explore volcanic magmatism in light of exposed and well characterized source candidates, namely lower crustal gabbros and the mid-crustal metasedimentary Kinzigite formation. Original geochemical characteristics of volcanic units have been obscured by the effects of subsequent hydrothermal alteration. The resistance of the mineral zircon to fluid alteration makes it a prime candidate for the preservation and exploration of these geochemical signals, such as O isotopes. Lower crustal gabbros in the Ivrea-Verbano Zone have broadly monotonic whole-rock δ18O values between +8 and +9‰VSMOW (Sinigoi et al., 1994). Kinzigites preserve a much higher and more heterogeneous δ18O values, typically ranging from +10‰ up to +15‰ (Baker, 1990). Zircons from the caldera-forming rhyolitic eruption units and a pre-caldera rhyodacitic unit were analyzed by ion microprobe at UCLA for in-situ oxygen isotope ratios. External reproducibility of within-mount standard R33 grains range from 0.27 to 0.36‰. Rhyolites from the caldera-forming eruption yield a range of δ18O(zircon) values from 6.3‰ to 8.3‰. This range displays rough correlation with CL activity - CL active grains have lower δ18O(zircon) values while CL dark grains have higher δ18O(zircon) values. This variation may correlate with U contents, which are notoriously low in zircons from Ivrea-Verbano Zone gabbros. We argue that the range in O isotope values suggests zircons are a good fit for magmas influenced by gabbro and Kinzigite sources. However, these zircons do not appear to be inherited directly from either the gabbro or Kinzigite sources as their O isotope signatures are typically intermediate between the two. The pre-caldera rhyodacite sample displays a

  9. Gradual caldera collapse at Bárdarbunga volcano, Iceland, regulated by lateral magma outflow.

    Science.gov (United States)

    Gudmundsson, Magnús T; Jónsdóttir, Kristín; Hooper, Andrew; Holohan, Eoghan P; Halldórsson, Sæmundur A; Ófeigsson, Benedikt G; Cesca, Simone; Vogfjörd, Kristín S; Sigmundsson, Freysteinn; Högnadóttir, Thórdís; Einarsson, Páll; Sigmarsson, Olgeir; Jarosch, Alexander H; Jónasson, Kristján; Magnússon, Eyjólfur; Hreinsdóttir, Sigrún; Bagnardi, Marco; Parks, Michelle M; Hjörleifsdóttir, Vala; Pálsson, Finnur; Walter, Thomas R; Schöpfer, Martin P J; Heimann, Sebastian; Reynolds, Hannah I; Dumont, Stéphanie; Bali, Eniko; Gudfinnsson, Gudmundur H; Dahm, Torsten; Roberts, Matthew J; Hensch, Martin; Belart, Joaquín M C; Spaans, Karsten; Jakobsson, Sigurdur; Gudmundsson, Gunnar B; Fridriksdóttir, Hildur M; Drouin, Vincent; Dürig, Tobias; Aðalgeirsdóttir, Guðfinna; Riishuus, Morten S; Pedersen, Gro B M; van Boeckel, Tayo; Oddsson, Björn; Pfeffer, Melissa A; Barsotti, Sara; Bergsson, Baldur; Donovan, Amy; Burton, Mike R; Aiuppa, Alessandro

    2016-07-15

    Large volcanic eruptions on Earth commonly occur with a collapse of the roof of a crustal magma reservoir, forming a caldera. Only a few such collapses occur per century, and the lack of detailed observations has obscured insight into the mechanical interplay between collapse and eruption. We use multiparameter geophysical and geochemical data to show that the 110-square-kilometer and 65-meter-deep collapse of Bárdarbunga caldera in 2014-2015 was initiated through withdrawal of magma, and lateral migration through a 48-kilometers-long dike, from a 12-kilometers deep reservoir. Interaction between the pressure exerted by the subsiding reservoir roof and the physical properties of the subsurface flow path explain the gradual, near-exponential decline of both collapse rate and the intensity of the 180-day-long eruption.

  10. San Juan Basin, CO and NM coal resources calculation area (sjbbndg)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This shapefile and polygon coverage outline the area underlain by the Fruitland Formation in the San Juan Basin, Colorado and New Mexico. Also, it delimits the area...

  11. Final unioned polygon coverage used in coal resource calculations, San Juan Basin, CO and NM (sjbfing)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This is a shapefile and the final unioned polygon coverage used to calculate coal resources of the Fruitland Formation, San Juan Basin coal assessment area, Colorado...

  12. Letter to Silverton and San Juan County Regarding Potential Superfund Listing

    Science.gov (United States)

    Feb. 12, 2016 Update: EPA added a letter to the Town of Silverton and San Juan County regarding the agency’s commitment to the Town and County’s involvement during a potential Superfund listing process.

  13. 33 CFR 165.758 - Security Zone; San Juan, Puerto Rico.

    Science.gov (United States)

    2010-07-01

    ... yards around all cruise ships entering, departing, moored or anchored in the Port of San Juan, Puerto... granted, all persons and vessels must comply with the instructions of the Captain of the Port or...

  14. La Reforma Universitaria como kulturkampf. La lectura gramsciana de Juan Carlos Portantiero

    National Research Council Canada - National Science Library

    Bustelo, Natalia

    2013-01-01

    .... Compartiendo ese interes, el presente trabajo se propone analizar las novedades introducidas por la lectura gramsciana de la Reforma Universitaria que propone Juan Carlos Portantiero en la decada del setenta...

  15. Sobre el nacimiento y procedencia de San Juan de Dios y su obra

    Directory of Open Access Journals (Sweden)

    Martínez Gil, José Luis

    2006-06-01

    Full Text Available This article studies the figure of St. Juan de Dios inside the historical context of Granada during the middle of XVIth century. The article tackles, from a chronological perspective, the main subjects of the biography of St. Juan and this assitencial work with poors and ills. The author goes more deeply into the situation of the hospitals in Granada in St. Juan de Dios day.Estudio de la figura de san Juan de Dios enmarcado en el contexto histórico de la Granada de mediados del siglo XVI. Se abordan, desde una perspectiva cronológica, los principales aspectos de la biografía del santo, así como su obra asistencial respecto a pobres y enfermos, profundizando en la situación de los hospitales en Granada en este período.

  16. Don Juan Basin, Wright Valley, Antarctica: Model for Surface Processes on Mars

    Science.gov (United States)

    Englert, P.; Bishop, J. L.; Gibson, E. K.; Patel, S.; Koeberl, C.

    2014-09-01

    Mineral, chemical, and soluble salt composition of drill core samples from Don Juan Basin, Wright Valley, Antarctica, indicate that the formation of the most saline terrestrial pond may include groundwater discharge and near surface flow processes.

  17. Using InSAR to investigate long term caldera unrest: case studies from Yellowstone and Long Valley

    Science.gov (United States)

    battaglia, maurizio

    2016-04-01

    Interpreting geodetic measurements can be particularly difficult in the case of slow, years-to-decades deformation, such as that commonly observed at large Quaternary silicic calderas. For example, Yellowstone caldera has shown a complex behavior over recent decades: uplift of resurgent domes within the caldera started sometime after 1923, reaching a total of 90 cm, but in 1984 the deformation reversed to subsidence at a rate of 1-2 cm/yr until 1992. Starting in 1992, the deformation began migrating from one resurgent dome to the other, and deformation was also detected along the caldera boundary - the so-called Northern Caldera Rim - starting in the mid-1990s. Evidence from geodetic surveys suggests that magma intrusion and/or pressurization of hydrothermal fluids may both drive uplift at Yellowstone. Geodetic measurements at Long Valley caldera have also revealed multiple episodes of caldera uplift, but in contrast to Yellowstone, deformation is largely restricted to the caldera's single resurgent dome. The fact that the energy released during the resurgent dome uplift is much larger than that which can be explained by seismic activity within and around the caldera, together with the observation that the onset of accelerated deformation precedes increases in earthquake activity by several weeks, suggests that the major source of caldera unrest is probably magma intrusion beneath the resurgent dome. Here we present time series of surface deformation for Yellowstone and Long Valley retrieved by applying the SBAS InSAR technique. We estimate the average regional deformation signal by using the mean velocity values derived from coherent SAR pixels belonging to areas outside the caldera. This tectonic signal is removed from the InSAR displacement and we modeled the InSAR, leveling, and gravity measurements to retrieve the best fitting source parameters. For Yellowstone caldera, different distinct sources, either hydrothermal or magmatic, have been intermittently

  18. Decadal to monthly timescales of magma transfer and reservoir growth at a caldera volcano.

    Science.gov (United States)

    Druitt, T H; Costa, F; Deloule, E; Dungan, M; Scaillet, B

    2012-02-01

    Caldera-forming volcanic eruptions are low-frequency, high-impact events capable of discharging tens to thousands of cubic kilometres of magma explosively on timescales of hours to days, with devastating effects on local and global scales. Because no such eruption has been monitored during its long build-up phase, the precursor phenomena are not well understood. Geophysical signals obtained during recent episodes of unrest at calderas such as Yellowstone, USA, and Campi Flegrei, Italy, are difficult to interpret, and the conditions necessary for large eruptions are poorly constrained. Here we present a study of pre-eruptive magmatic processes and their timescales using chemically zoned crystals from the 'Minoan' caldera-forming eruption of Santorini volcano, Greece, which occurred in the late 1600s BC. The results provide insights into how rapidly large silicic systems may pass from a quiescent state to one on the edge of eruption. Despite the large volume of erupted magma (40-60 cubic kilometres), and the 18,000-year gestation period between the Minoan eruption and the previous major eruption, most crystals in the Minoan magma record processes that occurred less than about 100 years before the eruption. Recharge of the magma reservoir by large volumes of silicic magma (and some mafic magma) occurred during the century before eruption, and mixing between different silicic magma batches was still taking place during the final months. Final assembly of large silicic magma reservoirs may occur on timescales that are geologically very short by comparison with the preceding repose period, with major growth phases immediately before eruption. These observations have implications for the monitoring of long-dormant, but potentially active, caldera systems.

  19. Las parodias dramáticas de Don Juan Tenorio en el siglo XIX

    OpenAIRE

    Noh Kang, Sook-Hwa

    2016-01-01

    Zorrilla was, undoubtedly, the one who approached the myth of Don Juan the closest. Tirso has paternity. Madariaga thinks the Don Juan of Moliere lacks spontaneity and displays a conscious rebellion against the laws. That of Byron is a reflective character. The Don Giovanni created by Da Ponte for Mozart's opera is very civilised and lacks spontaneity, as well. Madariaga does not forgive Pushkin for the appearance of Laura on a balcony in Madrid and not in Seville. Obviously Madariaga is righ...

  20. Estrategias de producción teatral : "Don Juan Tenorio" en 1950

    OpenAIRE

    Cornejo Ibares, Mª Paz

    2007-01-01

    Este artículo supone un análisis de las estrategias de producción escénica de los distintos montajes de Don Juan Tenorio de José Zorrilla representados en Madrid durante 1950. This article is an analysis of the scenic production’s strategies in the different staging of Don Juan Tenorio by José Zorrilla performed in Madrid during 1950.

  1. Stenocercus doellojuradoi (Iguanidae, Tropidurinae: una nueva especie para la provincia de San Juan, Argentina

    Directory of Open Access Journals (Sweden)

    Laspiur, Alejandro

    2006-05-01

    Full Text Available República Argentina, Provincia de San Juan, Depto. Valle Fértil, 3 km al norte de la localidad de Las Tumanas sobre la Ruta Provincial 510 (30°52’ S, 67°20’ W. COLECTOR: Alejandro Laspiur. FECHA: 25 /02/ 2006. MATERIAL DE REFERENCIA: Instituto y Museo de Ciencias Naturales, Universidad Nacional de San Juan: IMCNUNSJ 3000. Un ejemplar macho (LHC: 54 mm..

  2. Juan L. Ortíz: Primeros diálogos

    Directory of Open Access Journals (Sweden)

    Roxana Haydée Páez

    1996-11-01

    Full Text Available Emergencia, contextualización y diferencia de la poética de Juan L. Ortiz. El intertexto de lo que Julia Kristeva considera la primera vanguardia o vanguardia de fin de siglo, de los poetas argentinos posmodernistas, de Juan Ramón Jiménez. Vinculaciones del impresionismo de Ortiz, a través del simbolismo, el modernismo y el sencillismo

  3. Datos biográficos del sr. dr. juan de dios carrasquilla l. 1833-1908

    OpenAIRE

    Revista de la, Facultad de Medicina

    2012-01-01

    Nació el Dr. Juan de Dios Carrasquilla Lema en la ciudad deBogotá, el día 19 de Marzo de 1833, en la casa marcada hoy con el número 210 de la carrera 8, antigua Calle de Florián.  Fueron sus padres D. Juan Manuel Carrasquilla y D. Candelaria Lema, naturales de Medellín.

  4. Juan L. Ortíz: Primeros diálogos

    Directory of Open Access Journals (Sweden)

    Roxana Haydée Páez

    1996-11-01

    Full Text Available Emergencia, contextualización y diferencia de la poética de Juan L. Ortiz. El intertexto de lo que Julia Kristeva considera la primera vanguardia o vanguardia de fin de siglo, de los poetas argentinos posmodernistas, de Juan Ramón Jiménez. Vinculaciones del impresionismo de Ortiz, a través del simbolismo, el modernismo y el sencillismo

  5. THE SONG OF SONGS IN THE WORK OF LUIS DE LEON, SAN JUAN DE LA CRUZ Y JUAN GELMAN LANGUAGE, CHILDREN AND SPIRITUAL EXPERIENCE

    Directory of Open Access Journals (Sweden)

    Geneviève Fabry

    2015-04-01

    Full Text Available This paper aims to study the intertextual traces dell Song of Songs in the work of Luis de León, San Juan de la Cruz and Juan Gelman from a particular point of view: the resonance in the vernacular of small biblical book as founder dimension of an experience spiritual, emotional and literary time. Choosing our corpus may surprise but, for one, would like to emphasize the importance of two pivotal moments in the reception of the Song: the Spanish Renaissance, whose approach to the Bible is enriched by new currents philological and exegetical of which Luis de León is a sublime representative; the late twentieth century in which an insistent intertextuality observed with sanjuanista work in one direction often foreign to Christian spirituality, as in the case of the Argentine Juan Gelman.

  6. Hydrologic data for the San Juan and Animas River valleys in the Farmington, Aztec, Bloomfield, and Cedar Hill areas, San Juan County, New Mexico

    Science.gov (United States)

    McAda, D.P.; Shelton, S.G.

    1987-01-01

    In July 1985, the U.S. Geological Survey initiated a three-year study in San Juan County, New Mexico, to determine the concentrations of chemical constituents in the groundwater in the San Juan and Animas River valleys and to determine the direction and rate of groundwater flow and its relation to river stage. The study was conducted in cooperation with the San Juan County Commission and the New Mexico Oil Conservation Division. The data that was collected during the first 1-1/2 yr of the study is completed. The report includes well records for 51 wells and water levels from 23 wells, hydrographs from four observation wells and one river stage site, and available chemical analyses from 50 wells and 14 surface water sites. Water samples from six wells and one surface-water site were analyzed for purgeable organic chemicals; none were detected. (Lantz-PTT)

  7. Surface Deformation of Los Humeros Caldera, Mexico, Estimated by Interferometric Synthetic Aperture Radar (InSAR).

    Science.gov (United States)

    Santos Basurto, R.; Lopez Quiroz, P.; Carrasco Nuñez, G.; Doin, M. P.

    2014-12-01

    Los Humeros caldera is located in the eastern part of the Trans-Mexican Volcanic Belt, to the north of the state of Puebla and bordering the west side of the state of Veracruz. The study of the caldera, is of great interest because there is a geothermal field currently working inside of it. In fact, Los Humeros, is the third more important geothermal field in Mexico. In this work, we used InSAR to estimate the surface deformation on the caldera, aiming to contribute to its modeling and to help preventing subsidence related hazards on the geothermal field and surroundings. On this study, we calculated 34 interferograms from 21 SAR images of the ENVISAT European Space Agency Mission. The analysis of the interferograms, allow us to detect, decorrelation of the interferometric signal increased, when time spans were greater than 70 days. Also, for those with good signal correlation, the atmospheric signal dominated the interferogram, masking completely the deformation. Moreover, residual orbital ramps were detected, in some of the calculated interferograms. An algorithm capable to remove all the interferogram signal contributions but the deformation related, has been implemented. Resulting deformation and its correlation with several variables like the geology, the hydrogeology and the seismic records, were analysed through its integration in a Geographic Information System.

  8. Proceedings of the symposium on the Long Valley Caldera: A pre-drilling data review

    Energy Technology Data Exchange (ETDEWEB)

    Goldstein, N.E. (ed.)

    1987-09-01

    This proceedings volume contains papers or abstracts of papers presented at a two-day symposium held at the Lawrence Berkeley Laboratory (LBL) on 17 and 18 March 1987. Speakers presented a large body of new scientific results and geologic-hydrogeoloic interpretations for the Long Valley caldera. The talks and the discussions that followed focused on concepts and models for the present-day magmatic-hydrothermal system. Speakers at the symposium also addressed the topic of where to site future scientific drill holes in the caldera. Deep scientific drilling projects such as those being contemplated by the DOE Division of Geothermal Technology (DGT), under the Magma Energy Program, and by the DOE Office of Energy Research, Division of Engineering and Geosciences (DEG), along with the USGS and NSE, under the Continental Scientific Drilling Program (CSDP), will be major and expensive national undertakings. DOE/DEG is sponsoring a program of relatively shallow coreholes in the caldera, and DOE/DGT is considering the initiation of a multiphase program to drill a deep hole for geophysical observations and sampling of the ''near magmatic'' environment as early as FY 1988, depending on the DOE budget. Separate abstracts have been prepared for the individual papers.

  9. Weighted Clustering

    DEFF Research Database (Denmark)

    Ackerman, Margareta; Ben-David, Shai; Branzei, Simina

    2012-01-01

    We investigate a natural generalization of the classical clustering problem, considering clustering tasks in which different instances may have different weights.We conduct the first extensive theoretical analysis on the influence of weighted data on standard clustering algorithms in both...... the partitional and hierarchical settings, characterizing the conditions under which algorithms react to weights. Extending a recent framework for clustering algorithm selection, we propose intuitive properties that would allow users to choose between clustering algorithms in the weighted setting and classify...

  10. A new record for American Bullfrog (Lithobates catesbeianus in San Juan, Argentina Nuevo registro de rana toro americana (Lithobates catesbeianus en San Juan, Argentina

    Directory of Open Access Journals (Sweden)

    Eduardo Sanabria

    2011-03-01

    Full Text Available We report a new record of Lithobates catesbeianus (American bullfrog from Argentina. L. catesbeianus was first introduced to San Juan Province 11 years ago in Calingasta Department, where the habitat is pre-cordilleran. The new record is for Zonda Department, San Juan Province, in the Monte desert region. Here, L. catesbeianus uses artificial ponds for reproduction and tadpole development. These ponds receive water from an irrigation system that connects the whole agriculture land in the region. The tadpoles use the irrigation canals to move among ponds. We suggest that legislation should be established to prevent future invasions and to achieve sustainable management of the wild American bullfrog populations in San Juan. Prevention of future invasion and management of established populations of this species requires the cooperation of numerous stake holders.Se presenta un nuevo registro de Lithobates catesbeianus (rana toro americana en Argentina. L. catesbeianus fue introducida por primera vez a la provincia de San Juan hace 11 años en el Departamento Calingasta, donde el hábitat es pre-cordillerano. El nuevo registro es para el Departamento Zonda en la provincia de San Juan, en el desierto del Monte. En este sitio, L. catesbeianus usa estanques artificiales para la reproducción y desarrollo del renacuajo. Los estanques reciben agua de un sistema de riego que conecta todas las tierras de la agricultura en la región. Los renacuajos utilizan los canales de riego para moverse entre los estanques. Sugerimos que se establezcan leyes para prevenir invasiones futuras y para lograr un manejo integrado de las poblaciones silvestres de rana toro que se encuentran en San Juan. La prevención de futuras invasiones y el manejo de las poblaciones establecidas de esta especie requieren la cooperación de numerosas entidades tanto gubernamentales como privadas.

  11. Juan Gelman: Fábulas y revolución poética = Juan Gelman: Fables and poetic revolution

    Directory of Open Access Journals (Sweden)

    Lin, Ching-Yu

    2016-09-01

    Full Text Available Resumen: El presente estudio se centra en Fábulas de Juan Gelman para analizar la vinculación entre el género fabulístico y la revolución poética subyacente en su obra. Se trata de un nuevo modo de contar la realidad y las circunstancias sociales. Los poemas mezclan la historia oficial y la ficción para proponer miradas alternativas y subvertir convencionalismos y formalismos. Además, se crean personajes anónimos a fin de relatar visiones fabulosas en relación con la identidad colectiva. Esta técnica causa un efecto del extrañamiento y distanciamiento que desemboca en una reflexión profunda sobre la vida real. Finalmente, se reescriben leyendas exóticas, inventando episodios, con la finalidad de llamar la atención sobre ciertos fenómenos de la sociedad actual e inspirar solidaridad. = Abstract: This study focuses on Fábulas of Juan Gelman. The aim is to analyze the relationship between fable genre and poetic revolution in this work, in which Gelman provides a new way of describing reality and social circumstances. His poems combine official history with fiction to propose alternative views and subvert conventionalism and formalism. In addition, this poet creates anonymous characters to relate fabulous visions regarding the collective identity. This technique results in estrangement and distancing, which lead to profound reflection on real life. Finally, exotic legends are rewritten by means of invented episodes to draw attention to certain phenomena of modern society and inspire solidarity.

  12. Demistifikasi Tokoh Don Juan dalam La Nuit De Valognes Karya Eric-Emmanuel Schmitt

    Directory of Open Access Journals (Sweden)

    Talha Bachmid

    2006-10-01

    Full Text Available Don Juan is a myth about a seducer, a man with many love adventures, a women’s heat conqueror, and many other predicates. Don Juan as a myth is well-known world wide over, appearing in about 50 writings such as novels, plays, operas. But a French writer Eric-Emannuel Schmitt proposes a new figure of Don Juan in his play La Nuit de Valognes (Night in Valognes: the seducer is judged by five victims and convicted to marry one of his victims in order to stop his adventures. Surprisingly, Don Juan accepts this verdict without conditions. This sudden change becomes the theme of the play: the demythification of Don Juan. A flash back scene shows the beginning of this change and the interpretations that might arise from here. One possible interpretation is proposed and discussed in this paper: Don Juan found the way to a purer love, which is the union with God, and decides to begin his journey. This play can thus be categorised as a sufi text.

  13. Facies analysis of an ancient, dismembered, large caldera complex and implications for intra-arc subsidence: Middle Jurassic strata of Cobre Ridge, southern Arizona, USA

    Science.gov (United States)

    Riggs, Nancy R.; Busby-Spera, Cathy J.

    1991-11-01

    The Middle Jurassic (˜ 170 Ma) Cobre Ridge caldera is an elongate caldera complex that formed during the eruption of the tuff of Pajarito, a crystal-rich rhyodacite ignimbrite with an estimated volume > 1000 km 3. The caldera subsided in two subequal blocks: to the southeast, caldera-forming ignimbrite is as much as 3000 m thick, whereas the northwest half of the caldera subsided to lesser depths during the initial eruption, but was the locus of subsidence during subsequent eruptions, providing a depocenter for a > 1.5 km-thick section of secondary- and post-collapse volcanic and sedimentary strata. These strata record moat formation and filling and waning volcanism, including: (1) areally restricted ignimbrites up to several tens of meters thick that may have been ponded between caldera margins and/or fault scarps; (2) a ⩾ 600 m-thick ignimbrite whose eruption probably caused further collapse of the caldera or enlargement of the caldera margins; (3) a localized debris apron deposit up to 500 m thick that represents material reworked from intra-caldera pyroclastic deposits and possibly caldera walls; and (4) eolian and fluvial sandstones and water-lain tuffs. Megabreccia blocks as large as 0.5 km along strike probably demarcate approximate caldera margins, suggesting that the composite caldera was approximately 50 km long by 25 km wide. The preserved thickness of the strata of Cobre Ridge ( > 4500 m) is greater than many ancient continental volcanic sequences, suggesting external (i.e. tectonic) controls on subsidence, but preservation of this great thickness of strata is apparently due entirely to volcanic subsidence.

  14. Reconstructing the evoluortunity to study processes related to composite volction of an eroded Miocene caldera volcano (Yamanlar volcano, İzmir, Turkey)

    Science.gov (United States)

    Karaoğlu, Özgür; Brown, Richard J.

    2016-05-01

    The Miocene Yamanlar composite volcano is located in the central part of a shear zone in western Turkey. The volcano's deeply-eroded interior provides excellent three-dimensional exposure of a faulted caldera-floor and caldera-fill rocks as well as surrounding extracaldera ignimbrites. We present a much-revised stratigraphy and geological map of Yamanlar in order to quantify the evolutionary stages of the volcano. The Yamanlar volcanic cone was composed of > 800 m of basaltic-andesite to andesite lavas and lava domes. The volcano underwent at least one phase of caldera formation associated with an explosive eruption that deposited an ignimbrite sheet within and outside the caldera. Lithofacies architecture analysis is applied to the proximal and medial exposures of the Early-Middle Yamanlar Formation, which occurs outside of the caldera. Field evidence of the succession indicates a caldera-forming eruption. Our results indicate that the formation of the Yamanlar caldera resulted from one major catastrophic eruption that generated several sustained pyroclastic density currents (PDCs) subdivided by fall deposits with sharp contacts. The ignimbrite sheet is composed of four flow units. The presence of numerous coarse-grained lithic-rich horizons within the ignimbrite sheet is consistent with caldera subsidence. Post-caldera volcanism is indicated by intrusions and lava domes erupted along the inferred caldera-bounding faults, some of which record ~ 90 m of displacement. Widespread, coarse-grained breccias that overlie the ignimbrite sheet are interpreted as debris avalanche deposits resulting from gravitational failure of the flanks of the volcano or the caldera wall during or after caldera subsidence.

  15. Eruptive history, geochronology, and post-eruption structural evolution of the late Eocene Hall Creek Caldera, Toiyabe Range, Nevada

    Science.gov (United States)

    Colgan, Joseph P.; Henry, Christopher D.

    2017-02-24

    The magmatic, tectonic, and topographic evolution of what is now the northern Great Basin remains controversial, notably the temporal and spatial relation between magmatism and extensional faulting. This controversy is exemplified in the northern Toiyabe Range of central Nevada, where previous geologic mapping suggested the presence of a caldera that sourced the late Eocene (34.0 mega-annum [Ma]) tuff of Hall Creek. This region was also inferred to be the locus of large-magnitude middle Tertiary extension (more than 100 percent strain) localized along the Bernd Canyon detachment fault, and to be the approximate location of a middle Tertiary paleodivide that separated east and west-draining paleovalleys. Geologic mapping, 40Ar/39Ar dating, and geochemical analyses document the geologic history and extent of the Hall Creek caldera, define the regional paleotopography at the time it formed, and clarify the timing and kinematics of post-caldera extensional faulting. During and after late Eocene volcanism, the northern Toiyabe Range was characterized by an east-west trending ridge in the area of present-day Mount Callaghan, probably localized along a Mesozoic anticline. Andesite lava flows erupted around 35–34 Ma ponded hundreds of meters thick in the erosional low areas surrounding this structural high, particularly in the Simpson Park Mountains. The Hall Creek caldera formed ca. 34.0 Ma during eruption of the approximately 400 cubic kilometers (km3) tuff of Hall Creek, a moderately crystal-rich rhyolite (71–77 percent SiO2) ash-flow tuff. Caldera collapse was piston-like with an intact floor block, and the caldera filled with thick (approximately 2,600 meters) intracaldera tuff and interbedded breccia lenses shed from the caldera walls. The most extensive exposed megabreccia deposits are concentrated on or close to the caldera floor in the southwestern part of the caldera. Both silicic and intermediate post-caldera lavas were locally erupted within 400 thousand

  16. Measurement of high turbidity water behavior by ADCP at Izena Caldera in Okinawa Trough

    Science.gov (United States)

    Furuta, S.; Arai, R.; Yamazaki, T.

    2012-12-01

    Hydrothermal processes associated with spreading centers of plate-tectonics form hydrothermal activities and the resulted seafloor massive sulfide (SMS) deposits. Given that the SMS deposits found in the western Pacific have been considered to be potential sources of gold, silver, copper, zinc, and lead, there is a strong possibility that they will be mined near future. In order to take measures against environmental impacts during the mining of SMS deposits, it is important to measure components of hydrothermal origin with high temporal and spatial resolution on site, and to understand the mass circulation and transfer systems around the mining area. The Acoustic Doppler Current Profiler (ADCP) is effective tool for measurement of current field in water column in general. In addition, it is also useful for detection of turbidity profile in the water column simultaneously, applying an acoustic propagation model to the data. Izena Caldera, which is 3 km in short, 6 km in long axes and is generically from1,600 m to 1,700 m in depth, is located at the northwest of Okinawa Island. There both attractive SMS deposits and active hydrothermal vent systems have been confirmed. Because of the active vent systems and a bowl-like geographical structure, a quite unique mass circulation and transfer background condition is expected in Izena Caldera. The mining operation will add plenty of suspended materials into the background condition. For a primary understanding of the background condition, the authors analyzed the ADCP data and found two high-turbidity water zones in Izena Caldera and their behavior relationships with the current structure. The vertical downward current affects one of the high-turbidity zones around 1,220 m in depth. The current velocity against north-south direction and east-west direction affects the other high-turbidity zone 1,550 m in depth. Also the zones are recognized the higher synchronization with the lumi-solar diurnal tide, about 24 hours. The

  17. Volcano hazards implications of rhyolitic melt or magma at shallow depth under Krafla Caldera

    Science.gov (United States)

    Eichelberger, John; Papale, Paolo; Sigmundsson, Freysteinn

    2014-05-01

    Krafla Caldera in northern Iceland is a well-monitored and extensively drilled caldera system that underwent a major rifting and eruption episode in 1975 to 1984. The recent surprise discovery of ~900oC "magma" (crystal+melt felsite and possibly crystal-poor rhyolite magma as well) in the Iceland Deep Drilling Project borehole #1 (IDDP-1) in 2009, as well as previous less publicized drilling encounters with rhyolite melt, challenges our understanding of caldera unrest. Further drilling may lead to improved understanding of volcanic hazards in calderas and better interpretation of precursory deformation and seismic signals that may herald eruption. Salient features of the IDDP-1 discovery relative to volcanic hazards are: 1. The rhyolite magma is at only 2.1 km depth. If such magma were known to have intruded to such shallow depth in a populated caldera, there would likely be serious discussion of evacuating the population. 2. The drill site was chosen because magma was not expected at shallow depth, based on the occurrence of seismicity to twice that depth beneath the site during the last eruption, and on 3-D resistivity structure. 3. The eruption was entirely basaltic; no rhyolite reached the surface. Thus, rhyolite magma intruded to shallow depth and was stored there without erupting and without being detected either geophysically or petrologically. An alternative, which seems unlikely, is that the rhyolite evolved from basalt or by basalt-induced partial melting after 1984. If it is possible to return to this magmatic body through further drilling, as recently proposed to the International Continental Scientific Drilling Program (ICDP) by the Krafla Magma Drilling Project, complementary field, laboratory experiments, and computational experiments can be conducted to understand the "source" and how it produces deformation, seismic, and geochemical signals at the surface. Experiments could include injection of fluid with tracers directly into the melt-bearing zone

  18. Inter- and Intraspecific Variations of Bacterial Communities Associated with Marine Sponges from San Juan Island, Washington

    KAUST Repository

    Lee, O. O.

    2009-04-10

    This study attempted to assess whether conspecific or congeneric sponges around San Juan Island, Washington, harbor specific bacterial communities. We used a combination of culture-independent DNA fingerprinting techniques (terminal restriction fragment length polymorphism and denaturing gradient gel electrophoresis [DGGE]) and culture-dependent approaches. The results indicated that the bacterial communities in the water column consisted of more diverse bacterial ribotypes than and were drastically different from those associated with the sponges. High levels of similarity in sponge-associated bacterial communities were found only in Myxilla incrustans and Haliclona rufescens, while the bacterial communities in Halichondria panicea varied substantially among sites. Certain terminal restriction fragments or DGGE bands were consistently obtained for different individuals of M. incrustans and H. rufescens collected from different sites, suggesting that there are stable or even specific associations of certain bacteria in these two sponges. However, no specific bacterial associations were found for H. panicea or for any one sponge genus. Sequencing of nine DGGE bands resulted in recovery of seven sequences that best matched the sequences of uncultured Proteobacteria. Three of these sequences fell into the sponge-specific sequence clusters previously suggested. An uncultured alphaproteobacterium and a culturable Bacillus sp. were found exclusively in all M. incrustans sponges, while an uncultured gammaproteobacterium was unique to H. rufescens. In contrast, the cultivation approach indicated that sponges contained a large proportion of Firmicutes, especially Bacillus, and revealed large variations in the culturable bacterial communities associated with congeneric and conspecific sponges. This study revealed sponge species-specific but not genus- or site-specific associations between sponges and bacterial communities and emphasized the importance of using a combination

  19. Inter- and Intraspecific Variations of Bacterial Communities Associated with Marine Sponges from San Juan Island, Washington▿

    Science.gov (United States)

    Lee, On On; Wong, Yue Him; Qian, Pei-Yuan

    2009-01-01

    This study attempted to assess whether conspecific or congeneric sponges around San Juan Island, Washington, harbor specific bacterial communities. We used a combination of culture-independent DNA fingerprinting techniques (terminal restriction fragment length polymorphism and denaturing gradient gel electrophoresis [DGGE]) and culture-dependent approaches. The results indicated that the bacterial communities in the water column consisted of more diverse bacterial ribotypes than and were drastically different from those associated with the sponges. High levels of similarity in sponge-associated bacterial communities were found only in Myxilla incrustans and Haliclona rufescens, while the bacterial communities in Halichondria panicea varied substantially among sites. Certain terminal restriction fragments or DGGE bands were consistently obtained for different individuals of M. incrustans and H. rufescens collected from different sites, suggesting that there are stable or even specific associations of certain bacteria in these two sponges. However, no specific bacterial associations were found for H. panicea or for any one sponge genus. Sequencing of nine DGGE bands resulted in recovery of seven sequences that best matched the sequences of uncultured Proteobacteria. Three of these sequences fell into the sponge-specific sequence clusters previously suggested. An uncultured alphaproteobacterium and a culturable Bacillus sp. were found exclusively in all M. incrustans sponges, while an uncultured gammaproteobacterium was unique to H. rufescens. In contrast, the cultivation approach indicated that sponges contained a large proportion of Firmicutes, especially Bacillus, and revealed large variations in the culturable bacterial communities associated with congeneric and conspecific sponges. This study revealed sponge species-specific but not genus- or site-specific associations between sponges and bacterial communities and emphasized the importance of using a combination

  20. History of surface displacements at the Yellowstone Caldera, Wyoming, from leveling surveys and InSAR observations, 1923-2008

    Science.gov (United States)

    Dzurisin, Daniel; Wicks, Charles W.; Poland, Michael P.

    2012-01-01

    Modern geodetic studies of the Yellowstone caldera, Wyoming, and its extraordinary tectonic, magmatic, and hydrothermal systems date from an initial leveling survey done throughout Yellowstone National Park in 1923 by the U.S. Coast and Geodetic Survey. A repeat park-wide survey by the U.S. Geological Survey (USGS) and the University of Utah during 1975-77 revealed that the central part of the caldera floor had risen more than 700 mm since 1923, at an average rate of 14±1 mm/yr. From 1983 to 2007, the USGS conducted 15 smaller surveys of a single level line that crosses the northeast part of the caldera, including the area where the greatest uplift had occurred from 1923 to 1975-77. The 1983 and 1984 surveys showed that uplift had continued at an average rate of 22±1 mm/yr since 1975-77, but no additional uplift occurred during 1984-85 (-2±5 mm/yr), and during 1985-95 the area subsided at an average rate of 19±1 mm/yr. The change from uplift to subsidence was accompanied by an earthquake swarm, the largest ever recorded in the Yellowstone area (as of March 2012), starting in October 1985 and located near the northwest rim of the caldera. Interferometric synthetic aperture radar (InSAR) images showed that the area of greatest subsidence migrated from the northeast part of the caldera (including the Sour Creek resurgent dome) during 1992-93 to the southwest part (including the Mallard Lake resurgent dome) during 1993-95. Thereafter, uplift resumed in the northeast part of the caldera during 1995-96, while subsidence continued in the southwest part. The onset of uplift migrated southwestward, and by mid-1997, uplift was occurring throughout the entire caldera (essentially rim to rim, including both domes). Consistent with these InSAR observations, leveling surveys indicated 24±3 mm of uplift in the northeast part of the caldera during 1995-98. The beginning of uplift was coincident with or followed shortly after an earthquake swarm near the north caldera rim

  1. Is there a geochemical link between volcanic and plutonic rocks in the Organ Mountains caldera?

    Science.gov (United States)

    Memeti, V.; Davidson, J.

    2013-12-01

    Results from separate volcanic and plutonic studies have led to inconsistent conclusions regarding the origins and thus links between volcanic and plutonic systems in continental arcs and the magmatic processes and time scales responsible for their compositional variations. Some have suggested that there is a geochemical and geochronological disconnect between volcanic and plutonic rocks and hence have questioned the existence of magma mush columns beneath active volcanoes. Investigating contemporary volcanic and plutonic rocks that are spatially connected is thus critical in exploring these issues. The ca. 36 Ma Organ Mountains caldera in New Mexico, USA, represents such a system exposing contemporaneous volcanic and plutonic rocks juxtaposed at the surface due to tilting during extensional tectonics along the Rio Grande Rift. Detailed geologic and structural mapping [1] and 40Ar/39Ar ages of both volcanics and plutons [2] demonstrate the spatial and temporal connection of both rock types with active magmatism over >2.5 myr. Three caldera-forming ignimbrites erupted within 600 kyr [2] from this system with a total erupted volume of 500-1,000 km3 as well as less voluminous pre- and post-caldera trachyte and andesite lavas. The ignimbrite sequence ranges from a crystal-poor, high-SiO2 rhyolite at the base to a more crystal-rich, low-SiO2 rhyolite at the top. Compositional zoning with quartz-monzonite at the base grading to syenite and alaskite at the top is also found in the Organ Needle pluton, the main intrusion, which is interpreted to be the source for the ignimbrites [1]. Other contemporaneous and slightly younger plutons have dioritic to leucogranitic compositions. We examined both volcanic and plutonic rocks with petrography and their textural variations with color cathodoluminescence, and used whole rock element and Sr, Nd and Pb isotope geochemistry to constrain magma compositions and origins. Electron microprobe analyses on feldspars have been completed to

  2. Description and validation of an automated methodology for mapping mineralogy, vegetation, and hydrothermal alteration type from ASTER satellite imagery with examples from the San Juan Mountains, Colorado

    Science.gov (United States)

    Rockwell, Barnaby W.

    2012-01-01

    The efficacy of airborne spectroscopic, or "hyperspectral," remote sensing for geoenvironmental watershed evaluations and deposit-scale mapping of exposed mineral deposits has been demonstrated. However, the acquisition, processing, and analysis of such airborne data at regional and national scales can be time and cost prohibitive. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor carried by the NASA Earth Observing System Terra satellite was designed for mineral mapping and the acquired data can be efficiently used to generate uniform mineral maps over very large areas. Multispectral remote sensing data acquired by the ASTER sensor were analyzed to identify and map minerals, mineral groups, hydrothermal alteration types, and vegetation groups in the western San Juan Mountains, Colorado, including the Silverton and Lake City calderas. This mapping was performed in support of multidisciplinary studies involving the predictive modeling of surface water geochemistry at watershed and regional scales. Detailed maps of minerals, vegetation groups, and water were produced from an ASTER scene using spectroscopic, expert system-based analysis techniques which have been previously described. New methodologies are presented for the modeling of hydrothermal alteration type based on the Boolean combination of the detailed mineral maps, and for the entirely automated mapping of alteration types, mineral groups, and green vegetation. Results of these methodologies are compared with the more detailed maps and with previously published mineral mapping results derived from analysis of high-resolution spectroscopic data acquired by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) sensor. Such comparisons are also presented for other mineralized and (or) altered areas including the Goldfield and Cuprite mining districts, Nevada and the central Marysvale volcanic field, Wah Wah Mountains, and San Francisco Mountains, Utah. The automated

  3. Ultrastructure and potential sub-seafloor evidence of bacteriogenic iron oxides from Axial Volcano, Juan de Fuca Ridge, north-east Pacific Ocean.

    Science.gov (United States)

    Kennedy, C B; Scott, S D; Ferris, F G

    2003-03-01

    Iron oxides from the caldera of Axial Volcano, a site of hydrothermal vent activity along the Juan de Fuca Ridge, were found to consist predominantly of microbial structures in hydrated whole mounts examined using an environmental scanning electron microscope. Novel observations were made of the iron oxides revealing the spatial relationships of the bacteria within to be more consistent with microbial mats than mineral precipitates. The bacterial structures are attributed to the sheaths of Leptothrix ochracea, the stalks of Gallionella ferruginea, and the filaments of a novel iron oxidizing PV-1 strain, based on the distinctive morphological characteristics of these three bacteria. Energy dispersive X-ray spectroscopy revealed the presence and distribution of Fe, Si, and Cl on the bacterial sheaths, stalks and filaments. The iron oxides were identified by X-ray diffraction to be two-line ferrihydrite, a poorly ordered iron oxyhydroxide. Adsorption of Si in particular to two-line ferrihydrite likely contributes to its stability on the seafloor, and might also be a preservation mechanism creating microfossils of the bacterial structures encrusted with ferrihydrite. Presumptive evidence of the sub-seafloor presence of L. ochracea, G. ferruginea and PV-1 at Axial Volcano was obtained from the presence of these bacteria on a trap that had been placed within an active vent, and also in a vent fluid sample. If indeed these bacteria are present in the sub-seafloor, it may be an indication that the surface expression of iron oxide deposits at Axial Volcano is minimal in comparison to what exists beneath the seafloor.

  4. Reseña de: Rosario Moreno Soldevila, Juan Martos (eds.. Amor y sexo en la literatura latina

    Directory of Open Access Journals (Sweden)

    Gema Molina Mellado

    2017-02-01

    Full Text Available Rosario Moreno Soldevila, Juan Martos (eds.. Amor y sexo en la literatura latina. Review of: Rosario Moreno Soldevila, Juan Martos (eds.. Amor y sexo en la literatura latina. Anexo II de Exemplaria Classica. Huelva: Servicio de Publicaciones, 2015. 267 págs. ISSN 2173-6839. // Rosario Moreno Soldevila, Juan Martos (eds.. Amor y sexo en la literatura latina // Reseña de: Rosario Moreno Soldevila, Juan Martos (eds.. Amor y sexo en la literatura latina. Anexo II de Exemplaria Classica. Huelva: Servicio de Publicaciones, 2015. 267 págs. ISSN 2173-6839.

  5. Ruprecht 3: An old star cluster remnant?

    Science.gov (United States)

    Pavani, D. B.; Bica, E.; Ahumada, A. V.; Clariá, J. J.

    2003-02-01

    2MASS J and H photometry and integrated spectroscopy are employed to study the nature of the poorly populated compact concentration of stars Ruprecht 3, which was previously catalogued as an open cluster. The integrated spectrum remarkably resembles that of a moderately metal-rich globular cluster. The distribution of the object stars in the colour-magnitude diagram is compatible with that of a 1.5 +/- 0.5 Gyr open cluster or older, depending on whether the bluer stars are interpreted as turnoff stars or blue stragglers, respectively. We derive for the object a distance from the Sun dsun = 0.72 +0.04-0.03 kpc and a colour excess E(B-V) = 0.04. Although a globular cluster remnant cannot be ruled out, the integrated spectrum resemblance to that of a globular cluster probably reflects a stochastic effect owing to the few brighter stars. The structural and photometric properties of Ruprecht 3 are compatible with what would be expected for an intermediate-age open cluster remnant. Based on observations made at Complejo Astronómico El Leoncito, which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba and San Juan, Argentina.

  6. Magma plumbing system at the beginning of repeated caldera eruption: A case study on Aso-1 erupted about 270 ky ago from Aso caldera, SW Japan

    Science.gov (United States)

    Miyagi, I.; Hoshizumi, H.; Miyabuchi, Y.

    2015-12-01

    In order to understand the commencement of magma plumbing system of a polygenetic caldera, we started petrological study on the earliest eruptive product of Aso caldera, SW Japan. Aso caldera is one of the active volcano in Japan which have produced four stages (Aso-1, -2, -3, -4) of large-scale pyroclastic flow deposits 270 to 90 ky. ago. A suite of samples were collected from the bottom of Aso-1 pyroclastic flow deposit and from the underlying tephra layer (Ono et al., 1979). The tephra comprises more than 10 pumice fall units inter-layered by dark gray volcanic ash. For whole rock chemistry, coarser pumice fragments were separated. For mineral and glass chemistry, phenocrysts and glass particles were handpicked from the sieved 500-1000 um fractions under a binocular microscope. This fraction consist of plagioclase, orthopyroxene, variably vesiculated volcanic glass fragments, and clinopyroxene phenocrysts. They were analyzed using an electron micro-probe. The suite of samples are similar and major temporal change is the chemical composition of orthopyroxenes; those from upper horizon are relatively Mg rich. Anorthite content of plagioclase phenocryst is bimodal 49-53 mol. % (major) and 57-70 mol. % (minor). Silica content of matrix glass fall in a narrow range 68-70 wt. %. Temperature and oxygen fugacity were estimated to be 865-905 deg-C and FMQ+2 log unit, respectively, using ILMAT (Lepage, 2003). Pressure and water content of the magma are estimated to be 5-7 kbar and 0.5-1 wt. % H2O, respectively, using rhyolite-MELTS (Gualda et al., 2012) on the most undifferentiated tholeiitic basalt of Aso 4KC-03 (Hunter, 1998) to reproduce the observed composition of matrix glass (68-70 wt. % SiO2) and plagioclase (An 49-53 mol. %). The calcic plagioclase (An 57-70 mol. %), however, suggest that the basalt was initially hydrous and require magma degassing before the differentiation. If we assume degassing by magma convection in a conduit (Kazahaya et al., 1994), the

  7. Early Miocene Kırka-Phrigian Caldera, western Turkey (Eskişehir province), preliminary volcanology, age and geochemistry data

    Science.gov (United States)

    Seghedi, Ioan; Helvacı, Cahit

    2016-11-01

    Large rhyolitic ignimbrite occurrences are closely connected to the Early Miocene initiation of extension in the central-western Anatolia crossing the Tavşanlı-Afyon zones. Field and laboratory data performed at the apex of the Eskişehir-Afyon-Isparta volcanic area allowed recognition of newly identified caldera structure, named here "Kırka-Phrigian caldera". Transtensive/distensive tectonic stresses since 25 Ma ago resulted in the NNW-SSE elongation of the magma chamber and influenced the roughly elliptical shape of the subsided block (caldera floor). The caldera, which is roughly oval (24 km × 15 km) in shape, formed during a series of collapse events, starting at 19 Ma, by the generation of a huge volume of extra- and intracaldera ignimbrites. Intracaldera post-collapse sedimentation and further volcanism at the northern edge (at 18.6 Ma) were controlled through subsidence-related faults with generation of a series of volcanic structures (domes and lavas) showing a large compositional range. Enriched mantle components within the subcontinental lithospheric mantle began to melt via decompression melting during the initiation of extension. The heat resulting from the fractionation of ascending mantle melts produced the silicic compositions in large mushy crustal reservoirs; interaction of these melts with fertile crustal rocks further caused crustal anataxis and consequently two different compositions: Rhyolite-1 and Rhyolite-2. The eruptions of Kırka-Phrigian caldera-related ignimbrites were probably triggered by basaltic intrusion. Rock volumes and geochemical evidence suggest that silicic volcanic rocks come from a long-lived complex magma chamber system. After caldera generation there was a northern shift to small volume extra- and intra-caldera episodic rhyolitic, basaltic-trachy andesitic, trachytic and lamproitic volcanism, the latter being the youngest (16.2 Ma) indicating a more primitive magma input which originated in an enriched mantle

  8. Conductive heat flux in VC-1 and the thermal regime of Valles caldera, Jemez Mountains, New Mexico ( USA).

    Science.gov (United States)

    Sass, J.H.; Morgan, P.

    1988-01-01

    Over 5% of heat in the western USA is lost through Quaternary silicic volcanic centers, including the Valles caldera in N central New Mexico. These centers are the sites of major hydrothermal activity and upper crustal metamorphism, metasomatism, and mineralization, producing associated geothermal resources. Presents new heat flow data from Valles caldera core hole 1 (VC-1), drilled in the SW margin of the Valles caldera. Thermal conductivities were measured on 55 segments of core from VC-1, waxed and wrapped to preserve fluids. These values were combined with temperature gradient data to calculate heat flow. Above 335 m, which is probably unsaturated, heat flow is 247 + or - 16 mW m-2. Inteprets the shallow thermal gradient data and the thermal regime at VC-1 to indicate a long-lived hydrothermal (and magmatic) system in the southwestern Valles caldera that has been maintained through the generation of shallow magma bodies during the long postcollapse history of the caldera. High heat flow at the VC-1 site is interpreted to result from hot water circulating below the base of the core hole, and we attribute the lower heat flow in the unsaturated zone is attributed to hydrologic recharge. -from Authors

  9. A catalogue of caldera unrest at Taupo Volcanic Centre, New Zealand, using the Volcanic Unrest Index (VUI)

    Science.gov (United States)

    Potter, Sally H.; Scott, Bradley J.; Jolly, Gill E.; Johnston, David M.; Neall, Vince E.

    2015-09-01

    Caldera unrest occurs frequently at Taupo Volcanic Centre (TVC), New Zealand, occasionally resulting in deleterious socio-economic impacts. This large silicic volcano most recently erupted in 232 AD in an explosive, caldera-forming rhyolitic eruption, devastating the central North Island. Eruptions are preceded by volcanic unrest, often consisting of seismicity, deformation, degassing, and/or geothermal system changes. These phenomena may also occur due to non-magmatic processes, complicating eruption forecasting. As volcanic unrest may or may not lead to an eruption, it needs to be characterised to provide effective warnings; this is best achieved by understanding past unrest. In this research, a catalogue of caldera unrest at TVC is developed using an historical chronology methodology, spanning from 1872 to December 2011. The Volcanic Unrest Index (VUI), which is introduced by Potter et al. (2015), is estimated for the catalogue, demonstrating its use and providing a characterisation of unrest at TVC. Sixteen episodes of unrest are identified; 4 are classified as moderate unrest (VUI 3), and 12 are classified as minor unrest (VUI 2). There has been median interval of approximately 3 years between unrest episodes and a median unrest episode duration of just under 5 months. This research provides context for future caldera unrest crises at TVC and contributes to the global caldera unrest dataset.

  10. Meaningful Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Sanfilippo, Antonio P.; Calapristi, Augustin J.; Crow, Vernon L.; Hetzler, Elizabeth G.; Turner, Alan E.

    2004-05-26

    We present an approach to the disambiguation of cluster labels that capitalizes on the notion of semantic similarity to assign WordNet senses to cluster labels. The approach provides interesting insights on how document clustering can provide the basis for developing a novel approach to word sense disambiguation.

  11. The geochemical and petrological characteristics of prenatal caldera volcano: a case of the newly formed small dacitic caldera, Hijiori, Northeast Japan

    Science.gov (United States)

    Miyagi, Isoji; Kita, Noriko; Morishita, Yuichi

    2017-09-01

    Evaluating the magma depth and its physical properties is critical to conduct a better geophysical assessment of magma chambers of caldera volcanoes that may potentially cause future volcanic hazards. To understand pre-eruptive conditions of a magma chamber before its first appearance at the surface, this paper describes the case of Hijiori caldera volcano in northeastern Japan, which emerged approximately 12,000 years ago at a place where no volcano ever existed. We estimated the depth, density, bulk modulus, vesicularity, crystal content, and bulk H_2O content of the magma chamber using petrographic interpretations, bulk and microchemical compositions, and thermodynamic calculations. The chemical mass balance calculations and thermodynamic modeling of the erupted magmas indicate that the upper portion of the Hijiori magmatic plumbing system was located at depths between 2 and 4 km, and had the following characteristics: (1) pre-eruptive temperature: about 780 °C; (2) bulk magma composition: 66 ± 1.5 wt% SiO2; (3) bulk magmatic H_2O: approximately 2.5 wt%, and variable characteristics that depend on depth; (4) crystal content: ≤57 vol%; (5) bulk modulus of magma: 0.1-0.8 GPa; (6) magma density: 1.8-2.3 g/cm3; and (7) amount of excess magmatic H_2O: 11-32 vol% or 48-81 mol%. The range of melt water contents found in quartz-hosted melt inclusions (2-9 wt%) suggests the range of depth phenocrysts growth to be wide (2˜13 km). Our data suggest the presence of a vertically elongated magma chamber whose top is nearly solidified but highly vesiculated; this chamber has probably grown and re-mobilized by repeated injections of a small amount of hot dacitic magma originated from the depth.

  12. Umbrales: La escritura cinemática de Juan Emar

    Directory of Open Access Journals (Sweden)

    Wolfgang Bongers

    2014-07-01

    Full Text Available Este trabajo desarrollará la idea de que la escritura crítica, metaficcional y autorreferente de Juan Emar -desde las "Notas de Arte" (1924-1927 hasta el proyecto monumental de Umbral (1940-1964- puede comprenderse, por un lado, como espacio de resonancia de una estructura cinemática de percepción que se perfila como fundamental experiencia de vida durante la primera mitad del siglo XX. Por otro lado, sus textos, en diferentes niveles enunciativos, son parte de la conceptualización de esta misma experiencia. En este sentido, lo cinemático es un imaginario multiforme de la percepción del movimiento que culmina en el cine de vanguardia de los años veinte; mientras que lo cinematográfico se relaciona con el fenómeno del cine propiamente tal, sus posibilidades tecnológicas y los elementos que lo convierten en espectáculo. Estos polos tensionan la escritura de Emar en el nivel referencial, reflexivo, y estético-formal.

  13. The Yale/San Juan Southern Proper Motion Program

    Science.gov (United States)

    van Altena, W. F.; Girard, T. M.; Platais, I.; Kozhurina-Platais, V.; Ostheimer, J.; Lopez, C. E.; Mendez, R. A.

    1999-09-01

    The SPM is based on photographic plates taken at our observatory at El Leoncito, Argentina and will yield absolute proper motions and positions to magnitude B 19 for approximately 1 million stars south of declination -20 degrees. The SPM is a joint program between the Yale Southern Observatory and the Universidad Nacional de San Juan, Argentina. The SPM Catalog 2.0 provides positions, absolute proper motions, and photographic BV photometry for over 320,000 stars and galaxies. All objects contained in the SPM 1.0 Catalog (the South Galactic Pole region) are also included in this version. Note that SPM 1.0 has been replaced by SPM 1.1 which has slightly different astrometry (mostly proper motions) due to refinement of the magnitude equation correction in the SPM 2.0 Catalog. The Catalog covers an area of 3700 square degrees in an irregularly bounded band between declinations of -43 and -22 degrees, but excluding fields in the plane of the Milky Way. Stars cover the magnitude range 5 astrom/. Our web-site contains several useful plots showing the sky coverage, error distribution, a quick comparison with the Hipparcos proper motions, etc.

  14. Juan Rulfo y el ensueño del tiempo

    Directory of Open Access Journals (Sweden)

    Juan Manuel Rodríguez

    2003-01-01

    Full Text Available Este ensayo discute la temporalidad en la narrativa de Juan Rulfo a través de los recursos que utiliza para exponer las tramas de sus personajes. La temporalidad del fantasma Rulfiano es determinante en los enigmas que devienen del campo simbólico en el que se desarrolla la obra. Estos personajes plantean fronteras móviles en su actuación pues la muerte les da un carácter ilimitado de acción perdiendo la secuencia histórica del presente-pasado-futuro. Asimismo se plantean algunas relaciones hipotéticas entre el autor y su obra señalando la polisemia resultante del uso de la metáfora. La estructura de la obra y la suspensión de las tramas hacen del lector un co-autor. A través del ensueño Rulfo inventa una manera de leer y escribir la muerte a través de su fantasmagoría.

  15. Juan Carandell Pericay (1893-1937 y Sierra Nevada

    Directory of Open Access Journals (Sweden)

    Antonio López Ontiveros

    2000-01-01

    Full Text Available Juan Carandell Pericay (1893-1937, geólogo y geógrafo ligado a la Institución Libre de Enseñanza, escribió unos trescientos títulos, con una actividad científica e intelectual muy polifacética: geología, geografía física, humana y regional, libros de viaje y excursiones pedagógicas, semiología gráfica, divulgación científica y otras actividades intelectuales y artísticas. Una parte significativa de dichas obras estuvo dedicada a las Béticas, en general, y a Sierra Nevada en particular. Aspectos considerados por Carandell sobre Sierra Nevada son los relativos a su geología, geomorfología y tectónica, la erosión y sus causas físicas y humanas, la geografía humana –con especial importancia para el tema del hábitat– y otra variada gama de temas entre los que merece mención la faceta de las representaciones del paisaje, en todas las cuales demostró no sólo sus sólidos conocimientos geológicos y geográficos, sino incluso una calidad artística más que apreciable.

  16. Juan Valentin: un gelogo que supo resumir la geologa argentina Juan Valentin: a geologist that compiled the geology of Argentina

    Directory of Open Access Journals (Sweden)

    Florencio Gilberto Aceolaza

    2011-09-01

    Full Text Available Juan Valentin fue un destacado gelogo alemn que arrib a nuestra patria en 1894 para integrarse a los equipos que entonces desarrollaban investigaciones desde el Museo de La Plata y el Museo Nacional de Buenos Aires. Su trabajo lo llev, inicialmente, a estudiar las sierras de Buenos Aires y luego tambin lo hizo en Crdoba, San Luis, Salta y Jujuy. Fue grande su actividad, motivo por el cual, se lo incorpor a la Sociedad Cientfica Argentina asumiendo la revisin y compaginacin de los Anales que en ese tiempo editaba la mencionada institucin. Esta actividad ms el conocimiento de campo logrado, lo llev a confeccionar un extenso artculo donde describi la geologa de la Argentina, el cual fue agregado a la edicin del Segundo Censo Nacional. A este trabajo se lo considera una importante sntesis sobre la constitucin geolgica del pas. Entusiasmado con el apoyo que vena logrando planific un programa de investigacin para desarrollar en el norte de la Patagonia e incrementar el conocimiento de la estratigrafa regional. As fue que, en octubre de en 1897, se dirigi a Puerto Madryn donde llev adelante sus primeros trabajos en el valle del ro Chubut y la zona de Cabo Raso. Revisando afloramientos en las cercanas de Aguada de Reyes muri en un fatal accidente, como dice la crnica, con sus bolsillos repletos de los fsiles que haba coleccionado. Haca poco ms de dos aos que se desempeaba en el pas y contaba con 30 aos recin cumplidos. La mencin histrica narra que su cuerpo fue sepultado en la ciudad de Rawson.Juan Valentin was a German geologist that arrived to Argentina in 1894 to join the staff members of the Museum of La Plata and the National Museum of Buenos Aires. His work initially took him to explore the Buenos Aires ranges, and then those of Crdoba, San Luis, Salta and Jujuy. He joined the Argentine Scientific Society, assuming the edition of the Annals. His activities and the achieved knowledge in the field led him to prepare a lengthy article describing the

  17. Activity and abundance of denitrifying bacteria in the subsurface biosphere of diffuse hydrothermal vents of the Juan de Fuca Ridge

    Directory of Open Access Journals (Sweden)

    A. Bourbonnais

    2012-11-01

    Full Text Available Little is known about fixed nitrogen (N transformation and elimination at diffuse hydrothermal vents where anoxic fluids are mixed with oxygenated crustal seawater prior to discharge. Oceanic N sinks that remove bio-available N ultimately affect chemosynthetic primary productivity in these ecosystems. Using 15N paired isotope techniques, we determined potential rates of fixed N loss pathways (denitrification, anammox and dissimilatory nitrate reduction to ammonium (DNRA in sulfidic hydrothermal vent fluids discharging from the subsurface at several sites at Axial Volcano and the Endeavour Segment on the Juan de Fuca Ridge. We also measured physico-chemical parameters (i.e., temperature, pH, nutrients, H2S and N2O concentrations as well as the biodiversity and abundance of chemolithoautotrophic nitrate-reducing, sulfur-oxidizing γ-proteobacteria (SUP05 cluster using sequence analysis of amplified small subunit ribosomal RNA (16S rRNA genes in combination with taxon-specific quantitative polymerase chain reaction (qPCR assays. Denitrification was the dominant N loss pathway in the subsurface biosphere of the Juan de Fuca Ridge, with rates of up to ~1000 nmol N l−1 day−1. In comparison, anammox rates were always < 5 nmol N l−1 day−1 and below the detection limit at most of the sites. DNRA rates were up to ~150 nmol N l−1 day−1. These results suggest that bacterial denitrification out-competes anammox in sulfidic hydrothermal vent waters. Taxon-specific qPCR revealed that γ-proteobacteria of the SUP05 cluster sometimes dominated the microbial community (SUP05/total bacteria up to 38%. Significant correlations were found between fixed N loss (i.e., denitrification, anammox rates and in situ nitrate and dissolved inorganic nitrogen (DIN deficits in the fluids, indicating that DIN availability may ultimately regulate N loss in the subsurface

  18. Insights into deposition and deformation of intra-caldera ignimbrites, central Nevada

    Science.gov (United States)

    MacDonald, William D.; Palmer, H. Currie; Deino, Alan L.; Shen, Po-Yu

    2012-11-01

    Magnetic studies, together with structural and 40Ar/39Ar age analyses, were used to investigate the development and deformation of ignimbrites of the Caetano Tuff formation in central-north Nevada. Magnetic susceptibility, susceptibility anisotropy (AMS) and magnetic remanence approaches were used to decipher events accompanying emplacement and subsequent deformation of that tuff, for both intracaldera tuffs and outflow deposits. 40Ar/39Ar ages, both those presented here and previously published ages, indicate about 33.8 Ma for the age of Caetano ignimbrites, approximately at the Eocene/Oligocene boundary. Although extensive faulting associated with regional extension of the Great Basin region has dissected these deposits, the thickness of the intra-caldera ignimbrites has been estimated at 3.5 km or more. Thermal modeling for cooling of a caldera filling of 3.5 km thickness indicates acquisition of remanent magnetization can persist up to 25 ka, sufficient to average secular variation. This contrasts with rapid cooling and remanence acquisition in outflow ignimbrites typically only tens of meters thick. A 750 m thick reference section was selected for more detailed study about 10 km to the west of the type area. This reference section, fault-bounded at both base and top, represents the upper part of the formation. Its lower member includes the uppermost 250 m of the lower massive resistant unit of ignimbrites, a middle member of 375 m of well stratified pyroclastic deposits, vitrophyres and sediments, and an upper member of about 125 m of recessive ignimbrite and thin-bedded clastic and pyroclastic deposits. Structural and magnetic remanence measurements suggest 13° eastward tilting of the caldera floor occurred early during deposition of the middle member. Flow directions inferred from AMS Kmax axes in the middle member diverge about 45° relative to those in the underlying member and suggest a change in vent source accompanying the deposition of the middle

  19. Cluster Lenses

    CERN Document Server

    Kneib, Jean-Paul; 10.1007/s00159-011-0047-3

    2012-01-01

    Clusters of galaxies are the most recently assembled, massive, bound structures in the Universe. As predicted by General Relativity, given their masses, clusters strongly deform space-time in their vicinity. Clusters act as some of the most powerful gravitational lenses in the Universe. Light rays traversing through clusters from distant sources are hence deflected, and the resulting images of these distant objects therefore appear distorted and magnified. Lensing by clusters occurs in two regimes, each with unique observational signatures. The strong lensing regime is characterized by effects readily seen by eye, namely, the production of giant arcs, multiple-images, and arclets. The weak lensing regime is characterized by small deformations in the shapes of background galaxies only detectable statistically. Cluster lenses have been exploited successfully to address several important current questions in cosmology: (i) the study of the lens(es) - understanding cluster mass distributions and issues pertaining...

  20. The observed analysis on the wave spectra of Hurricane Juan (2003)

    Institute of Scientific and Technical Information of China (English)

    XU Fumin; BUI THI Thuy Duyen; PERRIE Will

    2014-01-01

    Hurricane Juan provides an excellent opportunity to probe into the detailed wave spectral patterns and spectral parameters of a hurricane system, with enough wave spectral observations around Juan’s track in the deep ocean and shallow coastal water. In this study, Hurricane Juan and wave observation stations around Juan’s track are introduced. Variations of wave composition are discussed and analyzed based on time series of one-dimensional frequency spectra, as well as wave steepness around Juan’s track:before, dur-ing, and after Juan’s passing. Wave spectral involvement is studied based on the observed one-dimensional spectra and two-dimensional spectra during the hurricane. The standardization method of the observed wave spectra during Hurricane Juan is discussed, and the standardized spectra show relatively conservative behavior, in spite of the huge variation in wave spectral energy, spectral peak, and peak frequency during this hurricane. Spectral widths’ variation during Hurricane Juan are calculated and analyzed. A two-layer nesting WW3 model simulation is applied to simulate the one-dimensional and two-dimensional wave spectra, in order to examine WW3’s ability in simulating detailed wave structure during Hurricane Juan.

  1. Survey and assessment of post volcanic activities of a young caldera lake, Lake Cuicocha, Ecuador

    Directory of Open Access Journals (Sweden)

    G. Gunkel

    2009-05-01

    Full Text Available Cuicocha is a young volcano adjacent to the inactive Pleistocene Cotacachi volcano complex, located in the western cordilleras of the Ecuadorian Andes. A series of eruptions with intensive ash emission and collapse of the caldera occurred around 4500–3000 y BP. A crater 3.2 km in diameter and a maximum depth of 450 m was formed. Further eruptions of the volcano occurred 1300 y BP and formed four smaller domes within the caldera. Over the last few hundred years, a caldera lake has developed, with a maximum depth of 148 m. The lake water is characterized by sodium carbonate with elevated concentrations of manganese, calcium and chloride. Nowadays, an emission of gases, mainly CO2, and an input of warm spring water occur in Lake Cuicocha. The zone of high activity is in the western basin of the lake at a depth of 78 m, and continuous gas emissions with sediment resuspension were observed using sonar. In the hypolimnion of the lake, CO2 accumulation occurs up to 0.2% saturation, but the risk of a limnic eruption can be excluded at present. The lake possesses monomictic stratification behaviour, and during overturn an intensive gas exchange with the atmosphere occurs. Investigations concerning the sedimentation processes of the lake suggest only a thin sediment layer of up to 10–20 cm in the deeper lake basin; in the western bay, in the area of gas emissions, the lake bottom is partly depleted of sediment in the form of holes, and no lake colmation exists. Decreases in the lake water level of about 30 cm y−1 indicate a percolation of water into fractures and fissures of the volcano, triggered by a nearby earthquake in 1987.

  2. New proximal tephras at Somma-Vesuvius: evidences of a pre-caldera, large (?) explosive eruption

    Science.gov (United States)

    Sparice, Domenico; Scarpati, Claudio; Mazzeo, Fabio Carmine; Petrosino, Paola; Arienzo, Ilenia; Gisbert, Guillem; Petrelli, Maurizio

    2017-04-01

    A 5 m thick pyroclastic and volcaniclastic sequence, never reported before, comprising a pumice fall deposit has been recognized in a disused quarry near Pollena Trocchia, on the NW slope of Somma-Vesuvius. It is composed of three stratigraphic units: a pumice fall deposit that underlies a pyroclastic density current deposit; they are overlain by a volcaniclastic unit emplaced during a quiescent period of the volcano. The pyroclastic deposits are separated by a horizon of reworked material indicating the emplacement from two distinct eruptive events. The pumice fall deposit has been subject of a detailed investigation. It consists of an ash bed overlaid by a roughly stratified pumice fall layer. The presence of ballistic clasts indicates the proximal nature of this deposit and its stratigraphic position below the Pomici di Base (22 ka) Plinian deposit allows constraining its age to the pre-caldera period (22-39 ky) of activity of Somma-Vesuvius. Samples have been collected in order to perform sedimentological (grain size and componentry), geochemical and isotopic analyses. Samples range from moderately to poorly sorted and show a trachytic composition. The comparison with literature data of compatible deposits vented from Somma-Vesuvius (Schiava, Taurano and Codola eruptions as well as borehole data) allows excluding any correlation with already known Vesuvian products suggesting that the analysed products are ascribable to a new, pre-caldera, explosive eruption. We name this new event ;Carcavone eruption;. Based on thickness, maximum lithic clasts and orientation of impact sags, showing a provenance from SE, we envisage the emplacement from a Plinian style eruption vented in the northern sector of the current caldera.

  3. A fluid-driven earthquake swarm on the margin of the Yellowstone caldera

    Science.gov (United States)

    Shelly, David R.; Hill, David P.; Massin, Frederick; Farrell, Jamie; Smith, Robert B.; Taira, Taka'aki

    2013-01-01

    Over the past several decades, the Yellowstone caldera has experienced frequent earthquake swarms and repeated cycles of uplift and subsidence, reflecting dynamic volcanic and tectonic processes. Here, we examine the detailed spatial-temporal evolution of the 2010 Madison Plateau swarm, which occurred near the northwest boundary of the Yellowstone caldera. To fully explore the evolution of the swarm, we integrated procedures for seismic waveform-based earthquake detection with precise double-difference relative relocation. Using cross-correlation of continuous seismic data and waveform templates constructed from cataloged events, we detected and precisely located 8710 earthquakes during the three-week swarm, nearly four times the number of events included in the standard catalog. This high-resolution analysis reveals distinct migration of earthquake activity over the course of the swarm. The swarm initiated abruptly on January 17, 2010 at about 10 km depth and expanded dramatically outward (both shallower and deeper) over time, primarily along a NNW-striking, ~55º ENE-dipping structure. To explain these characteristics, we hypothesize that the swarm was triggered by the rupture of a zone of confined high-pressure aqueous fluids into a pre-existing crustal fault system, prompting release of accumulated stress. The high-pressure fluid injection may have been accommodated by hybrid shear and dilatational failure, as is commonly observed in exhumed hydrothermally affected fault zones. This process has likely occurred repeatedly in Yellowstone as aqueous fluids exsolved from magma migrate into the brittle crust, and it may be a key element in the observed cycles of caldera uplift and subsidence.

  4. Ignimbrite Analyses of Batur Caldera, Bali, based on 14C Dating

    Directory of Open Access Journals (Sweden)

    Igan S. Sutawidjaja

    2014-06-01

    Full Text Available http://dx.doi.org/10.17014/ijog.vol4no3.20094The Batur Caldera, in the northeastern part of Bali Island, is an elliptical collapse structure 13.8 by 10 km in size and another circular composite collapse structure with a diameter of 7.5 km in its centre. Two stages of the collapse were interrupted by silicic andesite lavas and domes. The first collapse was initiated by the eruption of about 84 km3 of the dacitic "Ubud Ignimbrite", about 29,300 years B.P., which caused a steep-walled depression about 1 km deep. The second ignimbrite was erupted from a large crater about the present lake, and it  produced about 19 km3 of a similar voluminous dacitic ignimbrite, called the "Gunungkawi Ignimbrite" about 20,150 years B.P. This second eruption trig- gered a second collapse, which created the central circular caldera, and formed a basin structure. Both the Ubud and Gunungkawi Ignimbrites consist of a similar dacitic composition, white to red (the most abundant nearly 90 % and dark grey to black dacitic pumice clasts. The large clasts, up to 20 cm in diameter, are in the non-welded ignimbrite, particularly in the upper part of the Gunungkawi Ignimbrite. The intracaldera ignimbrite, called the "Batur Ignimbrite" about 5 km3  in volume is a densely welded ignimbrite and generally shows typical welded features. The ignimbrite comprises at least five different flow units, separated by thin (15 - 40 cm welded pumiceous airfall deposits, with flattened pumice clasts. Another large eruption occurred about 5,500 years B.P., producing around 0.09 km3  andesitic ignimbrite. This was initiated by phreatomagmatic eruptions, indicated by thick phreatomagmatic and surge deposits, underlying the ignimbrite. The caldera and its vicinity are partly filled, and variably mantled by later eruptive products of dacitic and andesitic phreatomagmatic and airfall deposits.  

  5. Electromagnetic imaging of the deep Campi Flegrei caldera structure (Southern Italy)

    Science.gov (United States)

    Giulia Di Giuseppe, Maria; Isaia, Roberto; Patella, Domenico; Piochi, Monica; Troiano, Antonio

    2017-04-01

    The Campi Flegrei caldera (CFc) is the most hazardous volcano in Europe. Enormous investigative efforts have been done aimed to share its inner structure and to understand its unrest dynamics, making the CFc one of the main subjects of interest of modern volcanology. Due to the destructive potential and the active geothermal system, the CFc geological structures have been investigated through many different methodologies. A key role belongs to the applied geophysics that allows to gain knowledge about the volcanic setting and consequently to understand the dynamics of this active caldera system. So far, the main CFc structures have been not yet clearly defined. The strong heterogeneity of the territory associated to the composite coastal morphology and the extreme urbanization represent a major obstacle to apply the geophysical techniques. Therefore the geometry and configuration of the CFc plumbing system are still largely undefined, although seismic surveys nowadays detected findings of melt-bearing rocks, at least locally. Here a deep electromagnetic (EM) imaging the CFc is presented. A Magnetotelluric (MT) profile has been carried out across a 12 km-long transect, ideally intersecting the main recent volcano-tectonic structures. The peculiar sensitivity to subsurface fluids and melts, associated with huge electric conductivity contrasts, make the MT particularly well suited to be applied in active volcanic settings. The obtained results highlight the buried structures down to 10 km of depth providing an interpretative key into the overall caldera dynamics. In particular, the deep magmatic source is revealed, as well as the main ascent pathway of magmatic fluids and the related structures which critically contributing to the shallower-level of deformation at CFc.

  6. The Laramide Mesa formation and the Ojo de Agua caldera, southeast of the Cananea copper mining district, Sonora, Mexico

    Science.gov (United States)

    Cox, Dennis P.; Miller, Robert J.; Woodbourne, Keith L.

    2006-01-01

    The Mesa Formation extends from Cananea, Mexico, southeast to the Sonora River and is the main host rock of Laramide porphyry copper deposits in the Cananea District and at the Alacran porphyry prospect to the east. The Mesa consists of two members-a lower andesite and an upper dacite. The lowest part of the dacite member is a crystal tuff about 100 m thick. This tuff is the outfall of a caldera centered near the village of Ojo de Agua, dated by 40Ar/39Ar at 65.8 Ma ?0.4. The Ojo de Agua Caldera is about 9 km in diameter and is filled by a light gray biotite dacite tuff with abundant flattened pumice fragments. The volume of the caldera is estimated to be 24 km3.

  7. An unusual syn-eruptive bimodal eruption: The Holocene Cuicuiltic Member at Los Humeros caldera, Mexico

    Science.gov (United States)

    Dávila-Harris, Pablo; Carrasco-Núñez, Gerardo

    2014-02-01

    The Cuicuiltic Member (CM) at Los Humeros Caldera, eastern Mexican Volcanic Belt is a Holocene (6.4 ka B.P.) succession of alternated fallout deposits of contrasting composition (trachydacite pumice and basaltic andesite scoria). The CM covers approximately 250 km2 on its proximal facies and its thickness ranges from 1.5 m to 8.0 m. It postdates two caldera-forming ignimbrites (Xaltipan and Zaragoza) and numerous Plinian successions. It is subdivided in 9 units (C1 to C9) according to its textural and chemical characteristics. Sub-horizontal, topography-draping layers of trachydacite pumice lapilli, andesitic pumice lapilli and basaltic-andesite scoria lapilli with sporadic one-meter blocks are common lithofacies. The base is formed by coarse trachydacite pumice lapilli (C1 and C2), overlain by a layer with banded pumice (C3). Thin layers of ash and ash-tuff are intermittent on lower units, whilst continuous at the base of C4. The middle units, C4 and C6 are basaltic-andesite pumice, and scoria lapilli to blocks; C5 is in-between the two mafic units and it is represented by a layer of pale grey pumice lapilli. Units C7 and C8 are a mixture of white trachydacite pumice, scoria lapilli and banded pumice. The uppermost layer, C9, is a brown to grey andesitic pumice lapilli. Extensive fieldwork allowed a close and reliable correlation of layers that helps to understand the complexity of stratigraphic relations and sources for those layers. The distribution of these units is varied across the caldera, with the trachydacite layers dispersal from the centre towards the NW, whilst the andesitic units have maximum thicknesses over the SE and NE sectors of the caldera. Isopach and isopleth maps, combined with detailed mapping of near-vent spatter facies, orientation of local bomb sags and variation of mean clasts size for some layers were very useful to determine the vent location, particularly for the andesitic-basaltic layers.

  8. Reservoir processes and fluid origins in the Baca geothermal system, Valles Caldera, New Mexico ( USA).

    Science.gov (United States)

    Truesdell, A.H.; Janik, C.J.

    1986-01-01

    At the Baca geothermal field in the Valles caldera, New Mexico, 19 deep wells were drilled in an attempt to develop a 50-MW (megawatts electric) power plant. The chemical and isotopic compositions of steam and water samples have been used to indicate uniquely the origin of reservoir fluids and natural reservoir processes. Two distinct reservoir fluids exist at Baca. These fluids originate from the same deep, high-temperature (335oC), saline (2500 mg/kg Cl) parent water but have had different histories during upflow which are described.-after Authors

  9. ESTUDIO MORFOGENÉTICO DE BAHÍA CALDERA, COSTA RICA

    OpenAIRE

    Saborío, Víctor

    2011-01-01

    La zona de estudio denominada Unidad Caldera, está comprendida en la hoja básica Barranca No. 3.245.I, escala 1:50.000 del IGN, cubriendo un área de 42 km2. Esta caracterizada por una precipitación promedio anual de 1. 600- 2. 000 milímetros; las temperaturas promedios oscilan entre 25- 30º C., lo que determinan un clima cálido seco- húmedo alternado. Los vientos predominantes son los alisios del noreste y de influencia monzónica provenientes del Sur franco y del Suroeste. Las direcciones del...

  10. Hydrothermal precious-metal deposits related to graben-calderas of the Sierra Madre Occidental

    Science.gov (United States)

    Aguirre-Diaz, G. J.; Labarthe-Hernandez, G.; Nieto-Obregon, J.; Tristan-Gonzalez, M.; Gonzalez-Partida, E.

    2007-05-01

    The Sierra Madre Occidental (SMO) covers the NW portion of Mexico and it is the host for several important precious metal mine operations, such as Tayoltita, Cienega, Topia, Fresnillo, Zacatecas, Guanajuato and Bolaños, just to mention a few. The southern part of the Basin and Range extension affected also NW Mexico and formed NW- to NE-trending normal faults that bound many large grabens, which are particularly long and deep in the southern SMO. Both graben formation and mid-Tertiary silicic volcanic activity coincided in space and time, particularly for the 38-23 Ma period, the Ignimbrite Flare-up event, but this activity dates back to Eocene and was as young as Miocene. This volcanism included large rhyolitic domes, too. At the southern SMO, the vents of this silicic volcanism are related to graben's master faults and we have named them graben-calderas. Evidences include large pyroclastic dikes and post-ignimbrite aligned rhyolitic domes and lava dikes. All these features were found along the graben-caldera walls or on the graben's shoulders. Some of these vents are related to gold and silver hydrothermal mineralization. In most cases a paleo-lake filled the graben-caldera for a period of time, either during the ignimbrite emplacement or after it. Some of the graben-caldera ignimbrites were deposited in subaqueous environments and post-ignimbrite rhyolitic domes and dikes were intruded in non-consolidated water-saturated tuffs or sedimentary deposits. This lacustrine environment provided the necessary water for the hydrothermal system. The combination of all these factors in space and time, grabens+volcanism+water, resulted in the development of precious-metal hydrothermal ore deposits. Bolaños mine in the Bolaños graben represent our case-study, but we have confirmed the same tectono-volcanic-lake relationship at other mine-districts along the SMO. We conclude that locating the fissural vents of the silicic ignimbrites by means of just geologic mapping is be

  11. Modificaciones en las calderas igneotubulares cubanas // Modifications in the Cuban boilers of fire tube

    Directory of Open Access Journals (Sweden)

    I. Pérez Mallea

    1998-01-01

    Full Text Available El objetivo de este trabajo es optimizar y diseñar las calderas igneotubulares nacionales, incluyendo las de inversión de llama yagua caliente. Con este fin se creo un software como soporte científico técnico que permite realizar los diferentes cálculosverificativos a través de los cuales se optimiza._________________________________________________________________________Abstract .The objective of this work is the optimizing and designing of the Cuban boilers of fire tube, including those of inverting offlame and hot water. A software have been developed as technical scientific supper for different calculations and optimizingprocess.

  12. The marine digital terrain model of the Panarea caldera (Aeolian Islands, Southern Italy

    Directory of Open Access Journals (Sweden)

    M. Anzidei

    1998-06-01

    Full Text Available A Marine Digital Elevation Model (MDEM of the still active volcanic area of Panarea caldera is presented in this paper. A fast and accurate survey was performed by means of the Differential Global Positioning System (DGPS geodetic technique coupled with an echo-sounding gear and a real time navigation software. The instrumentation was installed on board of a low draught boat in order to collect data starting from the bathymeter of one meter. Planar positions and depths were obtained with average accuracies of 30 cm and 10 cm respectively providing a 3D map of the seafloor useful for geomorphological, geophysical and volcanic hazard applications.

  13. Cartas de Juan Carlos Onetti para Julio Payró =Letters from Juan Carlos Onetti to Julio Payró

    Directory of Open Access Journals (Sweden)

    Lucena, Karina de Castilhos

    2014-01-01

    Full Text Available Este artigo analisa as cartas enviadas pelo escritor uruguaio Juan Carlos Onetti (1909- 1994 ao crítico de arte argentino Julio Payró (1899-1971 entre 1937 e 1955. A análise desses documentos contradiz uma faceta generalizante presente na fortuna crítica do autor, que o descreve como homem solitário e frio. Nos textos aqui estudados, Onetti manifesta seu carinho e admiração por Payró. Da mesma forma, as cartas oferecem dados que contestam a imagem do Onetti descompromissado, já que ele demonstra preocupação com os rumos da política de seu país. A correspondência também revela inseguranças e vaidades que a figura pública fazia questão de manter escondidas. Nesse sentido, este trabalho sugere que investigações a partir de documentos pessoais de escritores podem ampliar fortemente a interpretação de sua obra e às vezes se opor a juízos estabelecidos pelos críticos que não tiveram acesso a esse material.

  14. 33 CFR 334.1180 - Strait of Juan de Fuca, Wash.; air-to-surface weapon range, restricted area.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Strait of Juan de Fuca, Wash.; air-to-surface weapon range, restricted area. 334.1180 Section 334.1180 Navigation and Navigable... REGULATIONS § 334.1180 Strait of Juan de Fuca, Wash.; air-to-surface weapon range, restricted area. (a) The...

  15. 33 CFR 162.260 - Channel leading to San Juan Harbor, P.R.; use, administration, and navigation.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Channel leading to San Juan Harbor, P.R.; use, administration, and navigation. 162.260 Section 162.260 Navigation and Navigable... WATERWAYS NAVIGATION REGULATIONS § 162.260 Channel leading to San Juan Harbor, P.R.; use, administration...

  16. Friday Harbor Marina Expansion Study--San Juan Island, Washington: Final Detailed Project Report and Environmental Assessment.

    Science.gov (United States)

    1981-04-01

    Juan Marina Inc. Don F. Brown Self Steve F. Brown San Juan Marina Inc. Thoms Chittenden Self Alex D. Crichton Self Alan C,-mings KGMI-Bellingham Lois...Self Susan E. Risser Self Noble W. Starr Self Thomas C. Starr Self Corinne R. Towne Se"I Michael P. Vouri Bellingham Marine Industries June M. Vynne Self

  17. Resurgent Toba – field, chronologic, and model constraints on time scales and mechanisms of resurgence at large calderas

    Directory of Open Access Journals (Sweden)

    Shanaka L De Silva

    2015-06-01

    Full Text Available New data reveal details of the post-caldera history at the Earth’s youngest resurgent supervolcano, Toba caldera in Sumatra. Resurgence after the caldera-forming ~74 ka Youngest Toba Tuff eruption uplifted the caldera floor as a resurgent dome, Samosir Island, capped with 100m of lake sediments. 14C age data from the uppermost datable sediments reveal that Samosir Island was submerged beneath lake level (~900m a.s.l ~33.7 ky. Since then, Samosir experienced 700m of uplift as a tilted block dipping to the west. Using 14C ages and elevations of sediment along a transect of Samosir reveal that minimum uplift rates were ~4.9 cm/yr from ~33.7 to 22.5 ka, but diminished to ~0.7 cm/yr after 22.5ka. Thermo-mechanical models informed by these rates reveal that detumescence does not produce the uplift nor the uplift rates estimated for Samosir. However, models calculating the effect of volume change of the magma reservoir within a temperature-dependent viscoelastic host rock reveal that a single pulse of ~475 km3 of magma produces a better fit to the uplift data than a constant flux. Reproducing the uplift rates require more sophisticated models. Motivation for resurgent uplift of the caldera floor is rebound of remnant magma as the system re-established magmastatic and isostatic equilibrium after the caldera collapse. Previous assertions that the caldera floor was apparently at 400m a.s.l or lower requires that uplift must have initiated between sometime between 33.7 ka and 74 ka at a minimum average uplift rate of ~1.1 cm/ year. The change in uplift rate from pre-33.7 ka to immediately post-33.7 ka suggests a role for deep recharge augmenting rebound. Average minimum rates of resurgent uplift at Toba are at least an order of magnitude slower than net rates of restlessness at currently active calderas. This connotes a distinction between resurgence and restlessness controlled by different processes, scales of process, and controlling variables.

  18. The Juan non-LTR retrotransposon in mosquitoes: genomic impact, vertical transmission and indications of recent and widespread activity

    Directory of Open Access Journals (Sweden)

    Tu Zhijian

    2007-07-01

    Full Text Available Abstract Background In contrast to DNA-mediated transposable elements (TEs, retrotransposons, particularly non-long terminal repeat retrotransposons (non-LTRs, are generally considered to have a much lower propensity towards horizontal transfer. Detailed studies on site-specific non-LTR families have demonstrated strict vertical transmission. More studies are needed with non-site-specific non-LTR families to determine whether strict vertical transmission is a phenomenon related to site specificity or a more general characteristic of all non-LTRs. Juan is a Jockey clade non-LTR retrotransposon first discovered in mosquitoes that is widely distributed in the mosquito family Culicidae. Being a non-site specific non-LTR, Juan offers an opportunity to further investigate the hypothesis that non-LTRs are genomic elements that are primarily vertically transmitted. Results Systematic analysis of the ~1.3 Gbp Aedes aegypti (Ae. aegypti genome sequence suggests that Juan-A is the only Juan-type non-LTR in Aedes aegypti. Juan-A is highly reiterated and comprises approximately 3% of the genome. Using minimum cutoffs of 90% length and 70% nucleotide (nt identity, 663 copies were found by BLAST using the published Juan-A sequence as the query. All 663 copies are at least 95% identical to Juan-A, while 378 of these copies are 99% identical to Juan-A, indicating that the Juan-A family has been transposing recently in evolutionary history. Using the 0.34 Kb 5' UTR as the query, over 2000 copies were identified that may contain internal promoters, leading to questions on the genomic impact of Juan-A. Juan sequences were obtained by PCR, library screening, and database searches for 18 mosquito species of six genera including Aedes, Ochlerotatus, Psorophora, Culex, Deinocerites, and Wyeomyia. Comparison of host and Juan phylogenies shows overall congruence with few exceptions. Conclusion Juan-A is a major genomic component in Ae. aegypti and it has been

  19. Successful operation of a cooperative SLR station of China and Argentina in San Juan

    Institute of Scientific and Technical Information of China (English)

    HAN YanBen; E ALONSO; XIANG QingGe; HUANG DongPing; YIN ZhiQiang; LIU WeiDong; E ACTIS; R PODESTA; WANG TanQiang; GUO TangYong; QU Feng; A M PACHECO; AA GONZALEZ

    2008-01-01

    We introduced the observations and researches using a Satellite Laser Ranging (SLR) system with high precision,which was designed and made in China and installed in the Observatory of San Juan Uni-versity,Argentina,the capability of the system and the achievement of the cooperative procedure be-tween China and Argentina.The SLR station in San Juan,set up by China and Argentina,is quite sig-nificant for improving the distribution of SLR stations and enhancing the orbital coverage of the whole earth.Since the SLR system started to work in the Observatory of San Juan University in the beginning of 2006,the operation is rather good,and rich data with high precision have been obtained.Further plan of the cooperation for the near future is also presented.

  20. A jewel in the desert: BHP Billiton's San Juan underground mine

    Energy Technology Data Exchange (ETDEWEB)

    Buchsbaum, L.

    2007-12-15

    The Navajo Nation is America's largest native American tribe by population and acreage, and is blessed with large tracks of good coal deposits. BHP Billiton's New Mexico Coal Co. is the largest in the Navajo regeneration area. The holdings comprise the San Juan underground mine, the La Plata surface mine, now in reclamation, and the expanding Navajo surface mine. The article recounts the recent history of the mines. It stresses the emphasis on sensitivity to and helping to sustain tribal culture, and also on safety. San Juan's longwall system is unique to the nation. It started up as an automated system from the outset. Problems caused by hydrogen sulfide are being tackled. San Juan has a bleederless ventilation system to minimise the risk of spontaneous combustion of methane and the atmospheric conditions in the mine are heavily monitored, especially within the gob areas. 3 photos.

  1. Data Clustering

    Science.gov (United States)

    Wagstaff, Kiri L.

    2012-03-01

    On obtaining a new data set, the researcher is immediately faced with the challenge of obtaining a high-level understanding from the observations. What does a typical item look like? What are the dominant trends? How many distinct groups are included in the data set, and how is each one characterized? Which observable values are common, and which rarely occur? Which items stand out as anomalies or outliers from the rest of the data? This challenge is exacerbated by the steady growth in data set size [11] as new instruments push into new frontiers of parameter space, via improvements in temporal, spatial, and spectral resolution, or by the desire to "fuse" observations from different modalities and instruments into a larger-picture understanding of the same underlying phenomenon. Data clustering algorithms provide a variety of solutions for this task. They can generate summaries, locate outliers, compress data, identify dense or sparse regions of feature space, and build data models. It is useful to note up front that "clusters" in this context refer to groups of items within some descriptive feature space, not (necessarily) to "galaxy clusters" which are dense regions in physical space. The goal of this chapter is to survey a variety of data clustering methods, with an eye toward their applicability to astronomical data analysis. In addition to improving the individual researcher’s understanding of a given data set, clustering has led directly to scientific advances, such as the discovery of new subclasses of stars [14] and gamma-ray bursts (GRBs) [38]. All clustering algorithms seek to identify groups within a data set that reflect some observed, quantifiable structure. Clustering is traditionally an unsupervised approach to data analysis, in the sense that it operates without any direct guidance about which items should be assigned to which clusters. There has been a recent trend in the clustering literature toward supporting semisupervised or constrained

  2. DOCTOR JUAN CLIMACO HERNANDEZ (Tunja,1881-1961

    Directory of Open Access Journals (Sweden)

    Alfonso Vargas Rubiano

    1984-07-01

    Full Text Available

    Hace un tiempo vengo estudiando con fervorosa dedicación la obra pedagógica, sociopolítica, etnológica y cultural de uno de los grandes boyacenses de este siglo, el médico Juan Clímaco Hernández y he encontrado datos muy valiosos de la historia de nuestra educación médica en las postrimerías del pasado siglo y comienzos del actual, que bien valen la pena ser conocidos puesto que las Memorias de Ibáñez terminan en 1884 y el estudio hecho por el Dr. Juan N. Corpas si bien comprende hasta 1922, es muy poco lo que refiere al período que en nuestra historia nacional se conoce como de la Guerra de los 1000 días.


    EL NACIMIENTO Y BACHILLERATO EN TUNJA (1881-1897

    El 22 de noviembre de 1879, en la solemne sesión de clausura de estudios de la recientemente fundada Facultad de Medicina de la Universidad Nacional de los Estados Unidos de Colombia, recibían el grado de médicos los jóvenes Rodolfo Rueda, Manuel J
    Urruchurtu, Rafael Baquero, Eugenio de la Hoz y Miguel Hernández. Este último, nacido en Santa Marta, de 34 años de edad, había sido maestro de escuela superior en el Departamento del Magdalena, y recién graduado se trasladó a la ciudad de Tunja, como médico del Batallón Bolívar y allí ejerció su profesión hasta su muerte en 1911, alternándola con el periodismo y la política; fue elegido Diputado a la Asamblea de Boyacá en el período 1880-82 por el liberalismo de la provincia. Dicen las crónicas de la época que "a la Botica del Negro Hernández acudían todas las clases sociales, sin distinción alguna, a solicitar sus servicios médicos; los pobres sabían muy bien que en él tenían un defensor de sus derechos, listo siempre a aliviar sus dolores y miserias; y algunos contertulios iban en busca de distracción, charla agradable, tresillo tras los frascos y también, en noches especiales una mesa redonda con carpeta verde dejaba que los dados corriesen libremente

  3. JUAN PABLO LLINÁS CUENTAS (1924-2011

    Directory of Open Access Journals (Sweden)

    Alfredo Jácome Roca

    2011-04-01

    Full Text Available

    Guardo en mi biblioteca tres libros de tipo biográfico con dedicatoria del autor, el académico Juan Pablo Llinás Cuentas (1924-2011. Investigó este culto colega en los años ochenta sobre la vida de algunos de nuestros prohombres, como Atanasio Girardot, José Hilario López y José Celestino Mutis, siendo este último libro comentado en mi columna semanal de otrora, la del diario barranquillense El Heraldo. Como todos los que llevan los genes Llinás, sus raíces estaban en Sabanalarga, de donde  era también el ilustre profesor y académico César Augusto Pantoja. Me honró Llinás con su amistad (al igual que su hijo Adolfo, el ortopedista. Edgardo Coronado –escritor e historiador de la segunda ciudad del Atlántico (por tamaño, pero la primera en antigüedad y en abolengos– dijo de él que “su experiencia de 30 años como profesor le dio paciencia, entendimiento y sabiduría, lo que le permitió escribir diez libros sobre temas de historia, ética, medicina y filosofía, que fueron su satisfacción y el camino para encontrarse y encontrar a los demás”. 

    Mi contacto personal con Llinás fue precisamente en la década de los ochenta, cuando en su condición de Coordinador del Programa de Ciencias Básicas de la recién fundada Universidad del Norte, me llamó en varias ocasiones para que dictara mis cursos de fisiología endocrina en este centro académico de excelencia, faro de ciencia y de cultura. Su fuerte eran –por supuesto– las humanidades. De vocablo educado y gentiles maneras, Juan Pablo sabía de medicina, de historia, de filosofía, de artes plásticas y de poesía. En un grupo de amigos de las letras y de las artes en Barranquilla, organizaba reuniones con amigos personales como el poeta Eduardo Carranza, o divagaba sobre el significado imaginario de esculturas enigmáticas del maestro Edgar Negret.

     Fue Fundador, Decano y Profesor de la Facultad de Medicina

  4. Meteorologically Driven Simulations of Dengue Epidemics in San Juan, PR.

    Directory of Open Access Journals (Sweden)

    Cory W Morin

    2015-08-01

    Full Text Available Meteorological factors influence dengue virus ecology by modulating vector mosquito population dynamics, viral replication, and transmission. Dynamic modeling techniques can be used to examine how interactions among meteorological variables, vectors and the dengue virus influence transmission. We developed a dengue fever simulation model by coupling a dynamic simulation model for Aedes aegypti, the primary mosquito vector for dengue, with a basic epidemiological Susceptible-Exposed-Infectious-Recovered (SEIR model. Employing a Monte Carlo approach, we simulated dengue transmission during the period of 2010-2013 in San Juan, PR, where dengue fever is endemic. The results of 9600 simulations using varied model parameters were evaluated by statistical comparison (r2 with surveillance data of dengue cases reported to the Centers for Disease Control and Prevention. To identify the most influential parameters associated with dengue virus transmission for each period the top 1% of best-fit model simulations were retained and compared. Using the top simulations, dengue cases were simulated well for 2010 (r2 = 0.90, p = 0.03, 2011 (r2 = 0.83, p = 0.05, and 2012 (r2 = 0.94, p = 0.01; however, simulations were weaker for 2013 (r2 = 0.25, p = 0.25 and the entire four-year period (r2 = 0.44, p = 0.002. Analysis of parameter values from retained simulations revealed that rain dependent container habitats were more prevalent in best-fitting simulations during the wetter 2010 and 2011 years, while human managed (i.e. manually filled container habitats were more prevalent in best-fitting simulations during the drier 2012 and 2013 years. The simulations further indicate that rainfall strongly modulates the timing of dengue (e.g., epidemics occurred earlier during rainy years while temperature modulates the annual number of dengue fever cases. Our results suggest that meteorological factors have a time-variable influence on dengue transmission relative to other

  5. Juan Valentin: un gelogo que supo resumir la geologa argentina

    Directory of Open Access Journals (Sweden)

    Florencio Gilberto Aceolaza

    2011-09-01

    Full Text Available Juan Valentin fue un destacado gelogo alemn que arrib a nuestra patria en 1894 para integrarse a los equipos que entonces desarrollaban investigaciones desde el Museo de La Plata y el Museo Nacional de Buenos Aires. Su trabajo lo llev, inicialmente, a estudiar las sierras de Buenos Aires y luego tambin lo hizo en Crdoba, San Luis, Salta y Jujuy. Fue grande su actividad, motivo por el cual, se lo incorpor a la Sociedad Cientfica Argentina asumiendo la revisin y compaginacin de los Anales que en ese tiempo editaba la mencionada institucin. Esta actividad ms el conocimiento de campo logrado, lo llev a confeccionar un extenso artculo donde describi la geologa de la Argentina, el cual fue agregado a la edicin del Segundo Censo Nacional. A este trabajo se lo considera una importante sntesis sobre la constitucin geolgica del pas. Entusiasmado con el apoyo que vena logrando planific un programa de investigacin para desarrollar en el norte de la Patagonia e incrementar el conocimiento de la estratigrafa regional. As fue que, en octubre de en 1897, se dirigi a Puerto Madryn donde llev adelante sus primeros trabajos en el valle del ro Chubut y la zona de Cabo Raso. Revisando afloramientos en las cercanas de Aguada de Reyes muri en un fatal accidente, como dice la crnica, con sus bolsillos repletos de los fsiles que haba coleccionado. Haca poco ms de dos aos que se desempeaba en el pas y contaba con 30 aos recin cumplidos. La mencin histrica narra que su cuerpo fue sepultado en la ciudad de Rawson.

  6. Cluster Chemistry

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    @@ Cansisting of eight scientists from the State Key Laboratory of Physical Chemistry of Solid Surfaces and Xiamen University, this creative research group is devoted to the research of cluster chemistry and creation of nanomaterials.After three-year hard work, the group scored a series of encouraging progresses in synthesis of clusters with special structures, including novel fullerenes, fullerene-like metal cluster compounds as well as other related nanomaterials, and their properties study.

  7. Thermomechanical controls on magma supply and volcanic deformation: application to Aira caldera, Japan

    Science.gov (United States)

    Hickey, James; Gottsmann, Joachim; Nakamichi, Haruhisa; Iguchi, Masato

    2016-09-01

    Ground deformation often precedes volcanic eruptions, and results from complex interactions between source processes and the thermomechanical behaviour of surrounding rocks. Previous models aiming to constrain source processes were unable to include realistic mechanical and thermal rock properties, and the role of thermomechanical heterogeneity in magma accumulation was unclear. Here we show how spatio-temporal deformation and magma reservoir evolution are fundamentally controlled by three-dimensional thermomechanical heterogeneity. Using the example of continued inflation at Aira caldera, Japan, we demonstrate that magma is accumulating faster than it can be erupted, and the current uplift is approaching the level inferred prior to the violent 1914 Plinian eruption. Magma storage conditions coincide with estimates for the caldera-forming reservoir ~29,000 years ago, and the inferred magma supply rate indicates a ~130-year timeframe to amass enough magma to feed a future 1914-sized eruption. These new inferences are important for eruption forecasting and risk mitigation, and have significant implications for the interpretations of volcanic deformation worldwide.

  8. Thermomechanical controls on magma supply and volcanic deformation: application to Aira caldera, Japan

    Science.gov (United States)

    Hickey, James; Gottsmann, Joachim; Nakamichi, Haruhisa; Iguchi, Masato

    2016-01-01

    Ground deformation often precedes volcanic eruptions, and results from complex interactions between source processes and the thermomechanical behaviour of surrounding rocks. Previous models aiming to constrain source processes were unable to include realistic mechanical and thermal rock properties, and the role of thermomechanical heterogeneity in magma accumulation was unclear. Here we show how spatio-temporal deformation and magma reservoir evolution are fundamentally controlled by three-dimensional thermomechanical heterogeneity. Using the example of continued inflation at Aira caldera, Japan, we demonstrate that magma is accumulating faster than it can be erupted, and the current uplift is approaching the level inferred prior to the violent 1914 Plinian eruption. Magma storage conditions coincide with estimates for the caldera-forming reservoir ~29,000 years ago, and the inferred magma supply rate indicates a ~130-year timeframe to amass enough magma to feed a future 1914-sized eruption. These new inferences are important for eruption forecasting and risk mitigation, and have significant implications for the interpretations of volcanic deformation worldwide. PMID:27619897

  9. The Campi Flegrei Deep Drilling Project `CFDDP': Understanding the Magma-Aquifers Interaction at Large Calderas

    Science.gov (United States)

    de Natale, G.; Troise, C.; Sacchi, M.

    2007-05-01

    Campi Flegrei caldera is a good example of the most explosive volcanism on the Earth, a potential source of global catastrophes. Alike several similar volcanic areas (Yellowstone and Long Valley, USA; Santorini, Greece; Iwo Jima, Japan, etc.) its volcanic activity, i.e. eruptions and unrests, is dominated by physical mechanisms involving the strict interaction between shallow magma sources and geothermal systems. Furthermore, just like similar areas, it should be characterised by very large shallow magma chambers, filled by residual magma left after the ignimbritic caldera forming eruptions. However, neither the physical mechanisms of magma-water interaction, nor the evidence for such large magma chamber, have been ever clear enough to be used for detailed volcanological interpretation and eruption forecast. The CFDDP project aims to understand, for the first time, the location and rehology of large residual magma chambers and the mechanisms of interaction between magma and aquifer systems to generate eruptions and unrests. CFDDP is then structured as a large multidisciplinary project, with a main volcanological aim and with a further goal to launch a geothermal energy exploitation project in the area. A larger goal of the CFDDP project is to establish at Campi Flegrei, a densely urbanised area in a developed western country, a natural laboratory to study volcanic risk, environmental issues, monitoring technologies, geothermal energy exploitation.

  10. Magma storage and evolution of the most recent effusive and explosive eruptions from Yellowstone Caldera

    Science.gov (United States)

    Befus, Kenneth S.; Gardner, James E.

    2016-04-01

    Between 70 and 175 ka, over 350 km3 of high-silica rhyolite magma erupted both effusively and explosively from within the Yellowstone Caldera. Phenocrysts in all studied lavas and tuffs are remarkably homogenous at the crystal, eruption, and caldera-scale, and yield QUILF temperatures of 750 ± 25 °C. Phase equilibrium experiments replicate the observed phenocryst assemblage at those temperatures and suggest that the magmas were all stored in the upper crust. Quartz-hosted glass inclusions contain 1.0-2.5 % H2O and 50-600 ppm CO2, but some units are relatively rich in CO2 (300-600 ppm) and some are CO2-poor (50-200 ppm). The CO2-rich magmas were stored at 90-150 MPa and contained a fluid that was 60-75 mol% CO2. CO2-poor magmas were stored at 50-70 MPa, with a more H2O-rich fluid (X_{{{text{CO}}2 }} = 40-60 %). Storage pressures and volatiles do not correlate with eruption age, volume, or style. Trace-element contents in glass inclusions and host matrix glass preserve a systematic evolution produced by crystal fractionation, estimated to range from 36 ± 12 to 52 ± 12 wt%. Because the erupted products contain Yellowstone magmatic system may undergo rapid changes. The variations in depth suggest the magmas were sourced from multiple chambers that follow similar evolutionary paths in the upper crust.

  11. El anti-don Juan de María de Zayas

    Directory of Open Access Journals (Sweden)

    Trambaioli, Marcella

    2014-12-01

    Full Text Available All critics agree on considering that María de Zayas writes inspired by the anger that she feels for the women condition. Both in her prose and in the only play we know, La traición en la amistad, Zayas censures with irony and wit the don-Juan type who deceives women leaving them without honour. She does it elaborating an intertextual relationship with El burlador de Sevilla. Specifically, in the play she uses three characters: Liseo, who deceives three women, Fenisa, who is a don-Juan female even more exaggerated than Liseo, and don Juan, the less donjuanesco of all. As a matter of fact, Zayas creates an anti-don Juan similar to the one that Ventura de la Vega will realize in the XIX century with his play El hombre de mundo, a parody of Zorrilla’s Don Juan Tenorio; nevertheless it has a clear ethical purpose: to warn women of his age in order to avoid men’s abuses.Los críticos concuerdan en que María de Zayas escribe inspirada por la cólera que le provoca la condición femenina coetánea. Tanto en sus novelas como en la única comedia conservada, La traición en la amistad, Zayas censura con sutil ironía al tipo donjuanesco que se burla de las mujeres dejándolas sin honor, y lo hace entablando un complejo e ingenioso diálogo intertextual con El burlador de Sevilla. De forma especial, en la pieza lo hace a través de tres figuras: Liseo, que engaña a tres mujeres, Fenisa, un don Juan mujer aún más hiperbólico que Liseo, y don Juan, el menos donjuanesco de todos. En definitiva, crea un anti-don Juan parecido al que Ventura de la Vega realizará en el siglo XIX con El hombre de mundo, parodia del Tenorio de Zorrilla, pero con una clara intencionalidad ética: la de aleccionar a las mujeres de su época para que aprendan a esquivar a los hombres que abusan de ellas.

  12. [The medical world of Juan Gil de Zamora's Historia Naturalis (ca. 1275-1296)].

    Science.gov (United States)

    García Ballester, L; Domínguez, A

    1994-01-01

    The article describes the authors and works which were quoted by the Franciscan Juan Gil de Zamora in his Historia naturalis, a scientific encyclopaedia written between c. 1275 and before 1296, probably in the Franciscan monastery of Zamora (Kingdom of Castille). Juan Gil made wide use of the Avicenna's Canon, Gilbertus de Aquila (Anglicus)'s Compendium medicine, and Salernitan medical literature. His work contributed to the diffusion of these medical authors and works throughout the Christian intellectual milieu of late medieval Castille. This diffusion was not without problems.

  13. Juan Mayorga's adaptations of Lope: La dama boba in the 21st century

    Directory of Open Access Journals (Sweden)

    Mónica Molanes

    2012-12-01

    Full Text Available The adaptations made by one of today’s most eminent playwrights, Juan Mayorga, on the texts by Lope de Vega which were represented during the first decade of the 21st century allow us to analyse some of the most relevant aspects in the reception, canonization and theatrical interpretation of 17th century theatre. This study will thus focus on Lope’s La Dama Boba and the adaptation offered by Juan Mayorga for the Compañía Nacional de Teatro Clásico, directed by Helena Pimenta in 2002.

  14. O estudante endiabrado: representação do mito de Dom Juan em espronceda

    OpenAIRE

    Pandolfi, Maira Angélica [UNESP

    2011-01-01

    The present study is a reflection on the representation of the literary myth of Dom Juan in the work El estudiante de Salamanca (1836-1840), by Joseph de Espronceda. It highlights the most significant aspects of their recreation donjuanesca, since the classic elements taken from the founding work of Tirso de Molina to Romantic Titan which characterizes Dom Félix de Montemar. O presente estudo faz uma reflexão sobre a representação do mito literário de Dom Juan na obra El estudiante de Sala...

  15. Bibliography of literature pertaining to Long Valley Caldera and associated volcanic fields

    Science.gov (United States)

    Ewert, John W.; Harpel, Christopher J.; Brooks, Suzanna K.; Marcaida, Mae

    2011-01-01

    On May 25-27, 1980, Long Valley caldera was rocked by four M=6 earthquakes that heralded the onset of a wave of seismic activity within the caldera which has continued through the present. Unrest has taken the form of seismic swarms, uplift of the resurgent dome, and areas of vegetation killed by increased CO2 emissions, all interpreted as resulting from magma injection into different levels beneath the caldera, as well as beneath Mammoth Mountain along the southwest rim of the caldera. Continuing economic development in the Mammoth Lakes area has swelled the local population, increasing the risk to people and property if an eruption were to occur. The U.S. Geological Survey (USGS) has been monitoring geophysical activity in the Long Valley area since the mid-1970s and continues to track the unrest in real time with a sophisticated network of geophysical sensors. Hazards information obtained by this monitoring is provided to local, State, and Federal officials and to the public through the Long Valley Observatory. The Long Valley area also was scientifically important before the onset of current unrest. Lying at the eastern foot of the Sierra Nevada, the deposits from this active volcanic system have provided fertile ground for research into Neogene tectonics, Quaternary geology and geomorphology, regional stratigraphy, and volcanology. In the early 1970s, intensive studies of the area began through the USGS Geothermal Investigations Program, owing to the presence of a large young silicic volcanic system. The paroxysmal eruption of Long Valley caldera about 760,000 years ago produced the Bishop Tuff and associated Bishop ash. The Bishop Tuff is a well-preserved ignimbrite deposit that has continued to provide new and developing insights into the dynamics of ignimbrite-forming eruptions. Another extremely important aspect of the Bishop Tuff is that it is the oldest known normally magnetized unit of the Brunhes Chron. Thus, the age of the Bishop Tuff is used to

  16. Phreatomagmatic explosive eruptions along fissures on the top of mafic stratovolcanoes with overlapping compound calderas

    Science.gov (United States)

    Nemeth, Karoly; Geshi, Nobuo

    2017-04-01

    On near summit flank eruptions on stratovolcanoes it is commonly inferred that external water to have little or no influence on the course of the eruptions. Hence eruptions are typicaly "dry" that form spatter-dominated fissures and scoria cones. This assumption is based on that in elevated regions - especially on steep slopes - the hydrogeological conditions are not favourable to store large volume of ground water that can have effect on the eruptions. However there is some controversial trend of eruption progression from an early dry eruption below the summit that later turn to be phreatomagmatic as the eruption locus migrates toward the summit. The Suoana Ccrater on top of Miyakejima Island's mafic stratovolcano is a fine example to demonstrate such process. Suona Crater is the topmost crater of the 3 km long fissure aligned chain of small-volume volcanoes that formed in the 7th century flank of the summit region of the Miyakejima mafic stratovolcano. The oval shape crater of Suona (400 x 300 m) is surrounded by a tuff ring that developed over lava flows and epiclastic deposits accumulated in an older caldera forming about a tuff ring that is about 25 m in its thickest section with a basal consistent lava spatter dominated unit gradually transforming into a more scoria-dominated middle unit. A caldera-forming eruption in AD 2000 half-sectioned the Suona Crater exposing of its internal diatreme - crater in-fill - tephra rim succession providing a unique opportunity to understand the 3D architecture of the volcano. Toward the top of the preserved and exposed tuff ring section a clear gradual transition can be seen toward more abundance of chilled dark juvenile particles providing a matrix of a coarse ash that commonly hold cauliflower lapilli and bomb. This transition indicates that the eruption progressed from an early dry explosive phase such as lava fountaining to be a more Strombolian style explosive eruption that later on turned to be heavily influenced by

  17. Geology of the Mid-Miocene Rooster Comb Caldera and Lake Owyhee Volcanic Field, eastern Oregon: Silicic volcanism associated with Grande Ronde flood basalt

    Science.gov (United States)

    Benson, Thomas R.; Mahood, Gail A.

    2016-01-01

    The Lake Owyhee Volcanic Field (LOVF) of eastern Oregon consists of rhyolitic caldera centers and lava fields contemporaneous with and spatially related to Mid-Miocene Columbia River flood basalt volcanism. Previous studies delineated two calderas in the southeastern part of LOVF near Owyhee Reservoir, the result of eruptions of two ignimbrites, the Tuff of Leslie Gulch and the Tuff of Spring Creek. Our new interpretation is that these two map units are differentially altered parts of a single ignimbrite produced in a major phreatomagmatic eruption at ~ 15.8 Ma. Areas previously mapped as Tuff of Spring Creek are locations where the ignimbrite contains abundant clinoptilolite ± mordenite, which made it susceptible to erosion. The resistant intracaldera Tuff of Leslie Gulch has an alteration assemblage of albite ± quartz, indicative of low-temperature hydrothermal alteration. Our new mapping of caldera lake sediments and pre- and post-caldera rhyolitic lavas and intrusions that are chemically similar to intracaldera Tuff of Leslie Gulch point to a single ~ 20 × 25 km caldera, which we name the Rooster Comb Caldera. Erosion of the resurgently uplifted southern half of the caldera created dramatic exposures of intracaldera Tuff of Leslie Gulch cut by post-caldera rhyolite dikes and intrusions that are the deeper-level equivalents of lava domes and flows that erupted into the caldera lake preserved in exposures to the northeast. The Rooster Comb Caldera has features in common with more southerly Mid-Miocene calderas of the McDermitt Volcanic Field and High Rock Caldera Complex, including formation in a basinal setting shortly after flood basalt eruptions ceased in the region, and forming on eruption of peralkaline ignimbrite. The volcanism at Rooster Comb Caldera postdates the main activity at McDermitt and High Rock, but, like it, begins ~ 300 ky after flood basalt volcanism begins in the area, and while flood basalts don't erupt through the silicic focus, are

  18. Clustered regression with unknown clusters

    CERN Document Server

    Barman, Kishor

    2011-01-01

    We consider a collection of prediction experiments, which are clustered in the sense that groups of experiments ex- hibit similar relationship between the predictor and response variables. The experiment clusters as well as the regres- sion relationships are unknown. The regression relation- ships define the experiment clusters, and in general, the predictor and response variables may not exhibit any clus- tering. We call this prediction problem clustered regres- sion with unknown clusters (CRUC) and in this paper we focus on linear regression. We study and compare several methods for CRUC, demonstrate their applicability to the Yahoo Learning-to-rank Challenge (YLRC) dataset, and in- vestigate an associated mathematical model. CRUC is at the crossroads of many prior works and we study several prediction algorithms with diverse origins: an adaptation of the expectation-maximization algorithm, an approach in- spired by K-means clustering, the singular value threshold- ing approach to matrix rank minimization u...

  19. [Dietary prescriptions for the elites of the kingdom of Navarre in the 16th century: the cases of Juan Rena and Juan de Alarcón].

    Science.gov (United States)

    Serrano Larráyoz, Fernando

    2014-01-01

    The aim of this article is to present and analyse four dietary prescriptions from the 16th century prepared for Juan Rena, a cleric of Venetian origin, and his servant Juan de Alarcón, which are kept at the Archivo General de Navarra. These documents demonstrate the interest of the patients and physicians in dietetics, understood as a group of health and hygienic measures based on the Galenic res naturales and res non naturales. These four prescriptions are closely related to the ad personam or consilia health regimens, which represent a genre of medical literature whose significance in Renaissance Spain has received little attention. The cases studied reveal the high esteem in which the elites held the possession of therapeutic resources adapted to their individual needs, which were compiled and copied for personal use.

  20. Subspace clustering through attribute clustering

    Institute of Scientific and Technical Information of China (English)

    Kun NIU; Shubo ZHANG; Junliang CHEN

    2008-01-01

    Many recently proposed subspace clustering methods suffer from two severe problems. First, the algorithms typically scale exponentially with the data dimensionality or the subspace dimensionality of clusters. Second, the clustering results are often sensitive to input parameters. In this paper, a fast algorithm of subspace clustering using attribute clustering is proposed to over-come these limitations. This algorithm first filters out redundant attributes by computing the Gini coefficient. To evaluate the correlation of every two non-redundant attributes, the relation matrix of non-redundant attributes is constructed based on the relation function of two dimensional united Gini coefficients. After applying an overlapping clustering algorithm on the relation matrix, the candidate of all interesting subspaces is achieved. Finally, all subspace clusters can be derived by clustering on interesting subspaces. Experiments on both synthesis and real datasets show that the new algorithm not only achieves a significant gain of runtime and quality to find subspace clusters, but also is insensitive to input parameters.

  1. Tensor controlled-source audiomagnetotelluric survey over the Sulphur Springs Thermal area, Valles Caldera, New Mexico, U.S.A.; Implication for structure of the western Caldera and for CSAMT methodology

    Energy Technology Data Exchange (ETDEWEB)

    Wannamaker, P.E.

    1994-06-01

    We have carried Out an extensive tensor CSAMT survey of the Sulphur Springs geothermal area, Valles Caldera, New Mexico. This survey, consisting of 45 high-quality sites, has been acquired by in support of Continental Scientific Drilling Program (CSDP) drillholes VC-2A and VC-2B. Two independent transmitter dipoles were energized for tensor measurements using a 30 kW generator placed approximately 13 km south of the VC-2B wellhead. The soundings in the Sulphur Springs area were arranged in four profiles to cross major structural features. The electric bipoles parallel to each profile were deployed contiguously to ensure against spatial aliasing of the impedance response corresponding to current flow across structural trends. The frequency range of acquisition was 4096 Hz down to 1 Hz for the central line, but only down to 4 Hz for most sites of the other lines. Data quality is high overall and is established by repeatability of measurements. Agreement between the CSAMT and available natural field MT data is very good over almost all the period range of overlap indicating that we are free of calibration problems and that far-field results are generally being obtained. Non plane-wave effects in the CSAMT around Sulphur Springs are apparent at 1 to 2 Hz, and perhaps slightly even at 4 Hz, however, which is near the bottom of our frequency range. CSAMT and MT data taken outside the Valles Caldera to the west were modeled in an attempt to compare resistivity structure exterior to the caldera to that within. With the availability of tensor CSAMT and MT data both inside and outside Valles Caldera, assumptions and methods of CSAMT are tested. In the Sulphur Springs area, near-coincident CSAMT and MT data near well VC -2B indicate that non-lane-wave effects in the apparent resistivity and impedance phase occure at a frequency near to that predicted from the resistivity structure local to the wester caldera.

  2. Quantifying volcanic hazard at Campi Flegrei caldera (Italy) with uncertainty assessment: 2. Pyroclastic density current invasion maps

    Science.gov (United States)

    Neri, Augusto; Bevilacqua, Andrea; Esposti Ongaro, Tomaso; Isaia, Roberto; Aspinall, Willy P.; Bisson, Marina; Flandoli, Franco; Baxter, Peter J.; Bertagnini, Antonella; Iannuzzi, Enrico; Orsucci, Simone; Pistolesi, Marco; Rosi, Mauro; Vitale, Stefano

    2015-04-01

    Campi Flegrei (CF) is an example of an active caldera containing densely populated settlements at very high risk of pyroclastic density currents (PDCs). We present here an innovative method for assessing background spatial PDC hazard in a caldera setting with probabilistic invasion maps conditional on the occurrence of an explosive event. The method encompasses the probabilistic assessment of potential vent opening positions, derived in the companion paper, combined with inferences about the spatial density distribution of PDC invasion areas from a simplified flow model, informed by reconstruction of deposits from eruptions in the last 15 ka. The flow model describes the PDC kinematics and accounts for main effects of topography on flow propagation. Structured expert elicitation is used to incorporate certain sources of epistemic uncertainty, and a Monte Carlo approach is adopted to produce a set of probabilistic hazard maps for the whole CF area. Our findings show that, in case of eruption, almost the entire caldera is exposed to invasion with a mean probability of at least 5%, with peaks greater than 50% in some central areas. Some areas outside the caldera are also exposed to this danger, with mean probabilities of invasion of the order of 5-10%. Our analysis suggests that these probability estimates have location-specific uncertainties which can be substantial. The results prove to be robust with respect to alternative elicitation models and allow the influence on hazard mapping of different sources of uncertainty, and of theoretical and numerical assumptions, to be quantified.

  3. Ballistic blocks around Kīlauea Caldera: Their vent locations and number of eruptions in the late 18th century

    Science.gov (United States)

    Swanson, Donald A.; Zolkos, Scott P.; Haravitch, Ben

    2012-01-01

    Thousands of ballistic blocks occur around Kīlauea Caldera and record part of the latest major period of explosive activity on the volcano, in late 1790 or within a few years thereafter. The sizes of the blocks – the largest of which is more than 2 m in nominal diameter – and differences in rock types allow the definition of at least 6 dispersal lobes of mostly undetermined relative age. The orientations of the lobes help approximate the locations of vents or explosion sources on the floor of the caldera, now deeply buried by younger lava flows. The vents may have been distributed northward for about 2 km from near the site of the modern Halema'uma'u Crater and were apparently confined to the western half of the caldera. The blocks are entirely lithic except for those in one dispersal lobe, which contains cored bombs and blocks as well as juvenile lapilli. Eruption parameters calculated from EJECT! suggest that the phreatic and phreatomagmatic explosions could have been generated at the water table, about 600 m below the high point on the caldera rim.

  4. Simulation of Tsunami Related To Caldera Collapse and A Case Study of Thera Volcano In Aegean Sea

    Science.gov (United States)

    Yalciner, A. C.; Imamura, F.; Synolakis, C. E.

    Based on the seismic characteristics of the Aegean Sea and the surrounding regions, the earthquakes and volcanic eruptions had also generated several tsunamis in his- tory. It is therefore extremely important that the possible occurrence of a tsunami in these regions require careful and intensive investigations. One such approach is the investigation of the historical documents and determines the degree of effects of those tsunamis The eruption of volcano in Thera (Santorini) island in late Minoan time in Aegean sea resulted in a submarine caldera have generated tsunamis. The generation, and coastal effects of those tsunami waves have not been understood yet. However the tsunami deposits suggesting the sea water inundation related to Thera eruption are found at the sites, Crete (Gouves), Anatolia (Didim, Fethiye) and presented in Minoura et. al. (2000). In this study the generation of tsunamis related to caldera collapse, relation between the size, duration and level of caldera collapse with the generation of tsunami are in- vestigated by mathematical modeling and compared. The tsunami propagation related to this Thera caldera collapse is also investigated in this very irregular bathymetric domain of Southern Aegean Sea with TUNAMI-N2. The results are discussed and compared with the existing findings at coastal sites. Minoura et. al., (2000), "Discovery of Minoan Tsunami Deposits" Geology, V: 28, No 1 pp: 59-62

  5. Volcanic flood simulation of magma effusion using FLO-2D for drainage of a caldera lake at the Mt. Baekdusan

    Science.gov (United States)

    Lee, Khil-Ha; Kim, Sung-Wook; Kim, Sang-Hyun

    2014-05-01

    Many volcanic craters and calderas are filled with large amounts of water that can pose significant flood hazards to downstream communities due to their high elevation and the potential for catastrophic releases of water. Recent reports pointed out the Baekdusan volcano that is located between the border of China and North Korea as a potential active volcano. Since Millennium Eruption around 1000 AD, smaller eruptions have occurred at roughly 100-year intervals, with the last one in 1903. Sudden release of huge volume of water stored in temporarily elevated caldera lakes are a recurrent feature of volcanic environments, due to the case with which outlet channels are blocked by and re-cut through, unwelded pyroclastic deposits. The volcano is showing signs of waking from a century-long slumber recently. Volcanic floods, including breakouts from volcanic lakes, can affect communities beyond the areas immediately affected by a volcanic eruption and cause significant hydrological hazards because floods from lake-filled calderas may be particularly large and high. Although a number of case studies have been presented in the literature, investigation of the underlying physical processes is required as well as a method for interpreting the process of the rapid release of water stored in a caldera lake. The development of various forecasting techniques to prevent and minimize economic and social damage is in urgent need. This study focuses on constructing a flood hazard map triggered by the magma effusion in the Baekdusan volcano. A physically-based uplift model was developed to compute the amount of water and time to peak flow. The ordinary differential equation was numerically solved using the finite difference method and Newton-Raphson iteration method was used to solve nonlinear equation. The magma effusion rate into the caldera lake is followed by examples at other volcanic activities. As a result, the hydrograph serves as an upper boundary condition when hydrodynamic

  6. La "Paráfrasis a Juan" de Nono de Panópolis. Consideraciones literarias

    OpenAIRE

    Villarrubia Medina, Antonio

    2007-01-01

    Este artículo ofrece algunas observaciones generales sobre la Paráfrasis a Juan de Nono de Panópolis, el autor de las Dionisíacas, basadas en el análisis detallado de algunos aspectos literarios de este extenso poema cristiano hexamétrico.

  7. Mediated Debate, Historical Framing, and Public Art: The Juan de Onate Controversy in El Paso

    Science.gov (United States)

    Perez, Frank G.; Ortega, Carlos F.

    2008-01-01

    In 1988, the El Paso, Texas, city council accepted a proposal to build twelve statues of historically important individuals as part of a downtown revitalization initiative. Juan de Onate was selected as the centerpiece statue of the XII Travelers Memorial of the Southwest. The decision to honor the Spanish colonizer triggered a local controversy…

  8. Juan Rulfo and Machado de Assis: Toward an Integrated New Narrative

    Science.gov (United States)

    Wiseman, David P.; Krause, James R.

    2016-01-01

    Despite apparent connections between Brazilian and Spanish American narratives, comparative scholarship has only recently begun to investigate actively these important points of contact. In this study, we introduce a vital crossover between the two traditions, involving Juan Rulfo and Joaquim Maria Machado de Assis. Rulfo's outspoken affinity for…

  9. Juan Linz ja eestlane Aleksander Kesküla / Kaido Jaanson

    Index Scriptorium Estoniae

    Jaanson, Kaido, 1940-

    2002-01-01

    Eestlasest revolutsionääri Aleksander Kesküla elust Hispaanias aastail 1934-1963. Artikli aluseks on A. Kesküla Hispaania-perioodi väheste sõprade, eelkõige tänaseks rahvusvaheliselt tunnustatud sotsioloogi Juan Linz'i meenutused

  10. El cuento de Juan José Arreola: entre el arte y el horror

    OpenAIRE

    Evangelista Ávila, Iram Isaí

    2016-01-01

    La investigación aborda dos temas en la cuentística de Juan José Arreola: el arte y el horror. Arte y horror aparecen simbolizados dentro de sus cuentos como vehículos miméticos que, al interpretarlos, nos dan la posibilidad de acercarnos a una conce

  11. Isopachs of net coal thickness, Fruitland Formation, San Juan Basin, NM and CO (sjbthkg)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This as a shapefile and coverage showing the isopachs of total net coal in beds greater than 1.2' thick for the Fruitland Formation, San Juan Basin, Colorado and New...

  12. Los derechos humanos a la luz del pensamiento de Juan Duns Scoto

    OpenAIRE

    2012-01-01

    Con este aporte, quiero presentar a usted querido lector y lectora una aproximación a un problema tan cercano a nosotros en Colombia, como es el caso de los Derechos Humanos, iluminando dicha realidad desde un autor franciscano: Juan Duns Scoto, quien es recordado y celebrado este año (2008) en sus 700 años de muerte.

  13. 78 FR 72060 - Chimney Rock National Monument Management Plan; San Juan National Forest; Colorado

    Science.gov (United States)

    2013-12-02

    ...; ] DEPARTMENT OF AGRICULTURE Forest Service Chimney Rock National Monument Management Plan; San Juan National...) to establish management direction for the land and resources within Chimney Rock National Monument... establishing Chimney Rock National Monument (the Monument) requires preparation of a management plan....

  14. Colombia kunstnik Juan Manuel Echavarría Tallinnas / Kadri Karro

    Index Scriptorium Estoniae

    Karro, Kadri

    2011-01-01

    Juan Manuel Echavarría külastab Tallinna 12.-15. aprillini 2011, 13. apr.-l toimub Eesti Kunstiakadeemia Rüütelkonna hoones tema artist talk. Kunstniku holograafiliste trükiste sarjast "Reekviem NN" (2008-2010), mida eksponeeritakse Tallinna 15. graafikatriennaalil Kumu Kunstimuuseumis

  15. Hurricane recovery at Cabezas de San Juan, Puerto Rico, and research opportunities at Conservation Trust Reserves

    Science.gov (United States)

    Peter L. Weaver; Elizabeth Padilla Rodriguez

    2009-01-01

    The Cabezas de San Juan Natural Reserve (El Faro), an exposed peninsular area located in the Subtropical dry forest of northeastern Puerto Rico, was impacted by hurricanes Hugo (1989) and Georges (1998). From 1998 to 2008, a 0.10 ha plot was used to assess forest structure, species composition, and stem growth. During post-hurricane recovery, stem density, tree height...

  16. JUAN JOSÉ CABALLERO RODRÍGUEZ [Material gráfico

    OpenAIRE

    1980-01-01

    JUAN JOSÉ CABALLERO, TALLISTA DE MADERA DE SANTA MARÍA DE GUÍA, DURANTE LA CELEBRACIÓN DE UNA FERIA REGIONAL. DESTACA COMO UN ARTISTA DE LA TALLA, DESARROLLANDO UNA LABOR EXTRAORDINARIA E INCLUSO EN MEDIOS DOCENTES Copia digital. Madrid: Ministerio de Educación, Cultura y Deporte. Subdirección General de Coordinación Bibliotecaria, 2015

  17. Juan Linz ja eestlane Aleksander Kesküla / Kaido Jaanson

    Index Scriptorium Estoniae

    Jaanson, Kaido, 1940-

    2002-01-01

    Eestlasest revolutsionääri Aleksander Kesküla elust Hispaanias aastail 1934-1963. Artikli aluseks on A. Kesküla Hispaania-perioodi väheste sõprade, eelkõige tänaseks rahvusvaheliselt tunnustatud sotsioloogi Juan Linz'i meenutused

  18. Primer registro de Aplectana hylambatis (Nematoda, Cosmocercidae para anfibios de la provincia de San Juan

    Directory of Open Access Journals (Sweden)

    Quiroga, Lorena B.

    2012-11-01

    Full Text Available La presente nota representa los primeros registros de parásitos (nematodos para anfibios de la provincia de San Juan. Además, se discute la variación morfológica de los nematodos encontrados con otras poblaciones de Argentina.

  19. Los hombres. Juan Ramón Jiménez y Jaime Robledo Uribe

    Directory of Open Access Journals (Sweden)

    Boletín Cultural y Bibliográfico Banco de la República

    1958-05-01

    Full Text Available En el documento se realiza sendas notas de conmemoración  del fallecimiento de don Juan Ramón Jiménez  y don Jaime Robledo Uribe. Esta pequeña nota tiene como fin realizar un homenaje a tan reputados miembros del círculo cultural del país.

  20. Alegoría de la retórica en un biombo de Juan Correa

    Directory of Open Access Journals (Sweden)

    Arnulfo Herrera

    2014-03-01

    Full Text Available A partir de un análisis iconográfico se decodifica una alegoría de la retórica incluida en el Biombo de los cuatro elementos y las artes liberales, pintado en México hacia el año 1700 por Juan Correa.

  1. Reef Fish Inventory of Juan De Nova's Natural Park (Western Indian ...

    African Journals Online (AJOL)

    This paper constitutes the first study on reef fish communities at Juan de Nova, one of ... military base, represent sites which experience minimal direct human influence. ... the resilience of coral reef communities to environmental disturbances.. Keywords: reef fishes, diversity, Eparses Islands, natural reserve, western Indian ...

  2. Juan Rulfo and Machado de Assis: Toward an Integrated New Narrative

    Science.gov (United States)

    Wiseman, David P.; Krause, James R.

    2016-01-01

    Despite apparent connections between Brazilian and Spanish American narratives, comparative scholarship has only recently begun to investigate actively these important points of contact. In this study, we introduce a vital crossover between the two traditions, involving Juan Rulfo and Joaquim Maria Machado de Assis. Rulfo's outspoken affinity for…

  3. Colombia kunstnik Juan Manuel Echavarría Tallinnas / Kadri Karro

    Index Scriptorium Estoniae

    Karro, Kadri

    2011-01-01

    Juan Manuel Echavarría külastab Tallinna 12.-15. aprillini 2011, 13. apr.-l toimub Eesti Kunstiakadeemia Rüütelkonna hoones tema artist talk. Kunstniku holograafiliste trükiste sarjast "Reekviem NN" (2008-2010), mida eksponeeritakse Tallinna 15. graafikatriennaalil Kumu Kunstimuuseumis

  4. Hazard assessment of inorganics to endangered fish in the San Juan River, New Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, S.J.; Buhl, K.J. [National Biological Service, Yankton, SD (United States)

    1995-12-31

    Acute toxicity tests were conducted with larval Colorado squawfish (Ptychocheilus lucius) and razorback sucker (Xyrauchen texanus) in a constituted water quality simulating the San Juan River near Shiprock, New Mexico. Tests were conducted with arsenate, copper, selenate, selenite, zinc, and five mixtures of seven to nine inorganics simulating environmental mixtures reported for sites along the San Juan River (Ojo Amarillo Canyon, Gallegos Canyon, Hogback East Drain, Mancos River, and McElmo Creek). Razorback suckers were significantly more sensitive to arsenate, selenate, selenite, Hogback East Drain mixture, and Ojo Amarillo Canyon mixture than were Colorado squawfish. The Gallegos Canyon mixture had greater than additive, i.e., synergistic, toxicity to both species, the Ojo Amarillo Canyon mixture had less than additive, i.e., antagonistic, toxicity to both species, and the Mancos River and McElmo Creek mixtures had additive toxicity to both species. The Hogback East Drain mixture had additive toxicity to Colorado squawfish, but synergistic toxicity to razorback suckers. The major toxic component in the five mixtures was copper. Comparison of 96-hour LC50 values with a limited number of environmental water concentrations from the San Juan River revealed high hazard ratios for copper and all five environmental mixtures. The high hazard ratios suggest inorganic contaminants could adversely affect larval Colorado squawfish and razorback suckers in the San Juan River at sites receiving elevated inorganics.

  5. Comments on the Hurricane Juan report to the Nova Scotia Utility and Review Board

    Energy Technology Data Exchange (ETDEWEB)

    Tedesco, R.R.

    2004-05-14

    Nova Scotia Power Inc. (NSPI) has responded to several recommendations made by an independent consultant regarding its emergency response to Hurricane Juan which hit the Halifax Regional Municipality on September 28, 2003. NSPI is in agreement with most of the recommendations and is enhancing its preparedness for use in disaster scenarios similar to Hurricane Juan. Several recommendations have already been implemented by the power company including, improvements to call centre technology and processes, and better coordination with the electricity market operator and municipal responders. Lessons learned from Hurricane Juan were applied during a snow storm in February 2004, particularly in terms of communications. NSPI strongly disagrees with the consultant's recommendation to bring in hundreds of line crews from outside the region in advance of a major storm. NSPI argues that doing so, would have tripled or quadrupled Hurricane Juan costs to $40 or $50 million with little or no improvement on restoration times. Nova Scotia Power Inc. is a wholly-owned subsidiary of Emera (EMA-TSX). The utility provides more than 97 per cent of electric generation, transmission, and distribution to more than 460,000 customers across Nova Scotia. NSPI is committed to supporting Nova Scotian communities by providing safe, reliable power.

  6. 78 FR 35801 - Safety and Security Zones, San Juan Captain of the Port Zone

    Science.gov (United States)

    2013-06-14

    ... departing from Port of San Juan, Puerto Rico. The safety zone remains in effect until the cruise ship is... arrivals and departures of vessels via a broadcast notice to mariners. (c) Definitions. (1) Cruise ship. For the purposes of this section, Cruise ship means a passenger vessel greater than 100 feet in...

  7. Caldera resurgence: new insights from the study of the Siwi-Yenkahe-Yasur system (Vanuatu)

    Science.gov (United States)

    Brothelande, E.; Lenat, J.; Merle, O.; Peltier, A.

    2013-12-01

    On Tanna Island (Vanuatu), the Siwi caldera hosts a complex association between a permanently active explosive volcano (Yasur) and one of the fastest growing resurgent dome on Earth (Yenkahe). Uplifted coral terraces and marine tuff indicate a very high resurgence rate over the past 1000 yrs (15.6 cm.yr-1) making the Yenkahe dome one of the most relevant example of active post-caldera resurgence, but also one of the most dangerous structure of that kind. New data acquired between 2008 and 2012 brought further constraints on resurgent processes involved. Tectonic patterns inferred from structural observations on satellite images and on the field, completed by a meticulous photogrammetry study, argue for a relatively extended and shallow source of deformation. Two different approaches, using analogue and numerical modeling, were developed to explore the doming effects of different sources within the first kilometers. These models provide the first quantitative estimations on the depth and the shape of the source (magmatic and/or hydrothermal) that generated the Yenkahe dome. Analysis of external surface features, such as faults patterns and collapse scars revealed by photogrammetry and field observations, also provided new data for proposing hypotheses of a multi-step construction of the Yenkahe and discussing the potential instabilities of the dome, notably on the shore-bordering eastern flank. Geophysical investigations, combining electrical methods (T.D.E.M., E.R.T., S.P.), gravimetry and magnetism, were performed providing a wide range of information in terms of internal structure. Lithology units can be distinguished at different scales, and tectonic features connected to the surface can be defined. Conductive bodies representing the hydrothermal system can be located in relationship with these features, broaching the question of a possible phreatic or phreato-magmatic activity in the future. The combination of a wide panel of methods brings here a new image on

  8. Using StaMPS to process RADARSAT images of Askja caldera

    Science.gov (United States)

    de Zeeuw-van Dalfsen, E.; Hooper, A. J.; Sigmundsson, F.; Pedersen, R.; Jaupart, C. P.

    2009-12-01

    We have used RADARSAT SLC images from the Canadian Space Agency to create complex interferograms from part of the northern volcanic zone in Iceland. The dataset covers the 2000-2009 period and is a valuable addition to the limited number of good interferometric image pairs available for the area during this time, due to problems with the ERS in 2000 and limited other coverage for part of the period. Here, the Stanford Method for Persistent Scatterers (StaMPS) has been applied to RADARSAT data for the first time. This has enhanced the quality of the interferograms with respect to earlier processing using the Doris software package developed by the Delft Institute for Earth-Oriented Space Research (DEOS), Delft University of Technology. The StaMPS software was adapted for general use with RADARSAT data. Of our particular interest is the Askja caldera and its surroundings which are covered by the images. The Askja caldera has been gradually deflating since 1983 and InSAR images provide an excellent tool to monitor this deformation. In the last two years, previously undetected activity has been observed in the area. Since 2006 small magnitude lower-crustal earthquake swarms have been detected around the Askja caldera (Soosalu et al., 2009). Furthermore, 20 km to the east of Askja in the vicinity of the Upptyppingar mountain, intense persistent deep-seated seismic activity has been recorded since the beginning of 2007 (Jakobsdóttir et al. 2008). Both of these observations, even though very different in character, suggest magma movement at deep levels. The events may relate to recharging of the volcanic systems in the area, or alternatively to flow of magma away from the central part of the Askja system. Detailed monitoring of the area is therefore important. The time series of RADARSAT interferograms shows that Askja continues to subside into summer 2009, but further analysis can test if the rate of subsidence has slowed down in relation to the unrest in the area. We

  9. Storage and eruption of large volumes of rhyolite lava: Example from Solfatara Plateau, Yellowstone Caldera

    Science.gov (United States)

    Befus, K.; Gardner, J. E.; Zinke, R.

    2010-12-01

    The cataclysmic volcanic history of Yellowstone caldera has been extensively documented in both popular media and scholarly journals. High-silica magmas should erupt explosively because of their high viscosity and volatile content; however, numerous passively-erupted, large-volume rhyolite lava flows have also erupted from Yellowstone caldera. We use petrologic observations of one such flow, the Solfatara Plateau obsidian lava, to provide insights into the eruptive dynamics and pre-eruptive magmatic conditions of large-volume rhyolite lava. Solfatara Plateau, a 7 km3 high-silica rhyolite lava that extends 4-15 km from vent, erupted 103±8 ka within the Yellowstone caldera1. Quartz and sanidine are the dominant phenocrysts, with crystal contents of 5-10% throughout. FTIR analyses of glass inclusions in quartz and sanidine phenocrysts indicate that pre-eruptive dissolved volatile contents were up to 3.0 wt. % H2O and 250 ppm CO2. Myrmekite blebs partially envelop quartz and sanidine phenocrysts in all samples from along the margins of the flow (up to 3 km from flow front). Sanidines in samples from near vent are unzoned at Or49±2. Those at the flow front have similar cores, but rims are more sodic (Or44±6). Alkali feldspars in myrmekite range from Or27 to Or50. Petrologic observations, such as heavily embayed quartz phenocrysts and dissolution of myrmekite indicate disequilibrium within the system, likely as a result of significant heating that caused portions of the magma body to go from near-solidus to near-liquidus conditions prior to erupting. When it did erupt, volatile loss during eruptive ascent led to undercooling and significant microlite crystallization of Fe-Ti oxide and clinopyroxene microlites. Fe-Ti microlites occur as roughly equidimensional crystals, 1-10 µm across, as well as high-aspect-ratio needles, 3-60 µm long. Clinopyroxene microlites occur primarily as individual prismatic crystals, but also occur as linked, curved chains or as overgrowths

  10. Reticulite‐producing fountains from ring fractures in Kīlauea Caldera ca. 1500 CE: Chapter 16

    Science.gov (United States)

    May, Michael; Carey, Rebecca J.; Swanson, Don; Houghton, Bruce F.; Carey, Rebecca; Cayol, Valérie; Poland, Michael P.; Weis, Dominique

    2015-01-01

    A widely dispersed reticulite bed occurs close to the base of the Keanakākoʻi Tephra at Kīlauea Volcano. It can be divided into six subunits in the northern sector of the volcano; the reticulite also occurs in the southern sector, but outcrops are sparse owing to penecontemporaneous erosion and burial. Multilobate isopachs for each subunit and the total deposit suggest that multiple fountaining vents were distributed in the northern half of the caldera, possibly along ring fractures for the newly formed caldera. Isopach maps also show a sharp decline in thickness along the dispersal axis of each lobe, which could be explained by remobilization of tephra and/or inclined fountains. Despite such isopach characteristics, thinning rates calculated from the isopach data indicate that the fountains were among the most intense and powerful of all studied Kīlauea fountains. Density analyses of the pyroclasts suggest that fountaining was high (>600m) yet complex, possibly due to lava ponding and reentrainment. The calculated volume of the reticulite deposited around the caldera rim is approximately 0.2km3, more voluminous than the deposits of the 1959 Kīlauea Iki eruption; this volume is a minimum, however, as the low-density tephra is easily remobilized, and 600m high caldera walls probably trapped tephra within the caldera, which is deeply buried today and not accounted for in the volume calculations. The duration of this eruption was most likely at least a few days to weeks, based on the calculated volume and estimated discharge rates as seen during the Kīlauea Iki 1959 eruption.

  11. Dynamics and pre-eruptive conditions of catastrophic, ignimbrite-producing eruptions from the Yenkahe Caldera, Vanuatu

    Science.gov (United States)

    Firth, Chris W.; Cronin, Shane J.; Turner, Simon P.; Handley, Heather K.; Gaildry, Clement; Smith, Ian

    2015-12-01

    A combined stratigraphic and geochemical examination of 43 kyr of volcanic activity is presented for the Yenkahe Caldera, a mafic-intermediate volcanic system on the island of Tanna, in the Vanuatu Arc. Through this period two catastrophic ignimbrite-producing eruptions have occurred: the Siwi eruption and the older, Old Tanna Ignimbrite eruption. The latter was previously linked with a different edifice to the north-east, however re-examination has shown it was derived from the Yenkahe Caldera. Radiocarbon dating of this ignimbrite gives an age of 43 kyr B.P. Both eruptions produced voluminous ignimbrite sheets, however differences in deposit sequences show that the eruptions followed distinct courses. Deposits from the more recent Siwi eruption display greater evidence for phreatomagmatic phases during eruption onset. Both ignimbrites are distributed asymmetrically about the caldera, indicating partial collapse in each case. The early stages of the Siwi eruption produced directed pyroclastic surges and spatter fountains. Between these two major eruptions, volcanic activity was maintained through the formation of small, discrete volcanic cones, such as Yasur, which is active today. Whole rock major and trace element data show that intra-caldera activity between cataclysmic eruptions produced magmas of uniform basaltic-trachy-andesitic composition (SiO2 56 wt.%). Minerals within these lavas appear to be in equilibrium with their host. The Siwi eruption produced the most evolved, trachy-andesitic magma (SiO2 > 58 wt.%), while the Old Tanna eruption is associated with less evolved, basaltic-andesite magma (SiO2 53 wt.%). Juvenile clasts from both ignimbrites display diverse mineral chemistry and mineral disequilibrium textures. From these variations in geochemistry and petrology we suggest that a crystal mush or resident magma remained following low-magnitude, intra-caldera activity. MELTS modelling suggest that this was stored at shallow depths, equivalent to

  12. A preliminary study of older hot spring alteration in Sevenmile Hole, Grand Canyon of the Yellowstone River, Yellowstone Caldera, Wyoming

    Science.gov (United States)

    Larson, Peter B.; Phillips, Allison; John, David A.; Cosca, Michael A.; Pritchard, Chad; Andersen, Allen; Manion, Jennifer

    2009-01-01

    Erosion in the Grand Canyon of the Yellowstone River, Yellowstone Caldera (640 ka), Wyoming, has exposed a cross section of older hydrothermal alteration in the canyon walls. The altered outcrops of the post-collapse tuff of Sulphur Creek (480 ka) extend from the canyon rim to more than 300 m beneath it. The hydrothermal minerals are zoned, with an advanced argillic alteration consisting of an association of quartz (opal) + kaolinite ± alunite ± dickite, and an argillic or potassic alteration association with quartz + illite ± adularia. Disseminated fine-grained pyrite or marcasite is ubiquitous in both alteration types. These alteration associations are characteristic products of shallow volcanic epithermal environments. The contact between the two alteration types is about 100 m beneath the rim. By analogy to other active geothermal systems including active hydrothermal springs in the Yellowstone Caldera, the transition from kaolinite to illite occurred at temperatures in the range 150 to 170 °C. An 40Ar/39Ar age on alunite of 154,000 ± 16,000 years suggests that hydrothermal activity has been ongoing since at least that time. A northwest-trending linear array of extinct and active hot spring centers in the Sevenmile Hole area implies a deeper structural control for the upflowing hydrothermal fluids. We interpret this deeper structure to be the Yellowstone Caldera ring fault that is covered by the younger tuff of Sulphur Creek. The Sevenmile Hole altered area lies at the eastern end of a band of hydrothermal centers that may mark the buried extension of the Yellowstone Caldera ring fault across the northern part of the Caldera.

  13. High-resolution AUV mapping of the 2015 flows at Axial Seamount, Juan de Fuca Ridge

    Science.gov (United States)

    Paduan, J. B.; Chadwick, W. W., Jr.; Clague, D. A.; Le Saout, M.; Caress, D. W.; Thomas, H. J.; Yoerger, D.

    2016-12-01

    Lava flows erupted in April 2015 at Axial Seamount were mapped at 1-m resolution with the AUV Sentry in August 2015 and the MBARI Mapping AUVs in July 2016 and observed and sampled with ROVs on those same expeditions. Thirty percent of terrain covered by new flows had been mapped by the MBARI AUVs prior to the eruption. Differencing of before and after maps (using ship-collected bathymetry where the AUV had not mapped before) allows calculation of extents and volumes of flows and shows new fissures. The maps reveal unexpected fissure patterns and shifts in the style of flow emplacement through a single eruption. There were 11 separate flows totaling 1.48 x 108 m3 of lava erupted from numerous en echelon fissures over 19 km on the NE caldera floor, on the NE flank, and down the N rift zone. Flows in and around the caldera have maximum thicknesses of 5-19 m. Most erupted as sheet flows and spread along intricate channels that terminated in thin margins. Some utilized pre-existing fissures. Some flows erupted from short fissures, while at least two longer new fissures produced little or no lava. A flow on the upper N rift has a spectacular lava channel flanked by narrow lava pillars supporting a thin roof left after the flow drained. A shatter ring still emanating warm fluid is visible in the map as a 15-m wide low cone. Hundreds of exploded pillows were observed but are not discernable in the bathymetry. The northern-most three flows deep on the N rift are similar in area to the others but comprise the bulk of the eruption volume. Differencing of ship-based bathymetry shows only these flows. Near the eruptive fissures they are sheet flows, but as they flowed downslope they built complexes of coalesced pillow mounds up to 67-128 m thick. Changes in flow morphology occurred through the course of the eruption. Large pillow mounds had molten cores that deformed as the eruption progressed. One flow began as a thin, effusive sheet flow but as the eruption rate decreased, a

  14. Cluster editing

    DEFF Research Database (Denmark)

    Böcker, S.; Baumbach, Jan

    2013-01-01

    . The problem has been the inspiration for numerous algorithms in bioinformatics, aiming at clustering entities such as genes, proteins, phenotypes, or patients. In this paper, we review exact and heuristic methods that have been proposed for the Cluster Editing problem, and also applications......The Cluster Editing problem asks to transform a graph into a disjoint union of cliques using a minimum number of edge modifications. Although the problem has been proven NP-complete several times, it has nevertheless attracted much research both from the theoretical and the applied side...

  15. Weighted Clustering

    CERN Document Server

    Ackerman, Margareta; Branzei, Simina; Loker, David

    2011-01-01

    In this paper we investigate clustering in the weighted setting, in which every data point is assigned a real valued weight. We conduct a theoretical analysis on the influence of weighted data on standard clustering algorithms in each of the partitional and hierarchical settings, characterising the precise conditions under which such algorithms react to weights, and classifying clustering methods into three broad categories: weight-responsive, weight-considering, and weight-robust. Our analysis raises several interesting questions and can be directly mapped to the classical unweighted setting.

  16. Cluster analysis

    CERN Document Server

    Everitt, Brian S; Leese, Morven; Stahl, Daniel

    2011-01-01

    Cluster analysis comprises a range of methods for classifying multivariate data into subgroups. By organizing multivariate data into such subgroups, clustering can help reveal the characteristics of any structure or patterns present. These techniques have proven useful in a wide range of areas such as medicine, psychology, market research and bioinformatics.This fifth edition of the highly successful Cluster Analysis includes coverage of the latest developments in the field and a new chapter dealing with finite mixture models for structured data.Real life examples are used throughout to demons

  17. Rock physics of fibrous rocks akin to Roman concrete explains uplifts at Campi Flegrei Caldera

    Science.gov (United States)

    Vanorio, Tiziana; Kanitpanyacharoen, Waruntorn

    2015-08-01

    Uplifts in the Campi Flegrei caldera reach values unsurpassed anywhere in the world (~2 meters). Despite the marked deformation, the release of strain appears delayed. The rock physics analysis of well cores highlights the presence of two horizons, above and below the seismogenic area, underlying a coupled process. The basement is a calc-silicate rock housing hydrothermal decarbonation reactions, which provide lime-rich fluids. The caprock above the seismogenic area has a pozzolanic composition and a fibril-rich matrix that results from lime-pozzolanic reactions. These findings provide evidence for a natural process reflecting that characterizing the cementitious pastes in modern and Roman concrete. The formation of fibrous minerals by intertwining filaments confers shear and tensile strength to the caprock, contributing to its ductility and increased resistance to fracture.

  18. SELECTED CHEMICAL ANALYSES AND GEOTHERMOMETRY OF HOT SPRING WATERS FROM THE CALABOZOS CALDERA, CENTRAL CHILE.

    Science.gov (United States)

    Thompson, J.M.; Grunder, A.L.; Hildreth, Wes

    1983-01-01

    Hot springs discharging from the active hydrothermal system associated with the Calabozos caldera, Chile, have measured orifice temperatures as high as 98. 5 degree C and calculated geothermometer temperatures as high as 250 degree C. Three types of spring waters can be identified from the chemical analyses: a Na-Cl type, a Na-HCO//3 type and a Na-mixed anion type. Chloride-enthalpy relations indicate that the hydrothermal reservoir water may attain temperatures near 342 degree C and that most spring waters are mixed with cold meteoric water. Despite the proximity of Mesozoic marine gypsum deposits, the Cl/Br weight ratio of the Calabozos spring waters does not appear to indicate that these waters have a significant 'marine' signature. Refs.

  19. Geology and hazard implications of the Maraunot notch in the Pinatubo Caldera, Philippines

    Science.gov (United States)

    Lagmay, A. M. F.; Rodolfo, K. S.; Siringan, F. P.; Uy, H.; Remotigue, C.; Zamora, P.; Lapus, M.; Rodolfo, R.; Ong, J.

    2007-06-01

    The 1991 Pinatubo eruption left 5 6 km3 of debris on the volcano slopes, much of which has been mobilized into large lahars in the following rainy seasons. Also during the eruption, collapse, localized in part along preexisting faults, left a caldera 2.5 km in diameter that almost immediately began to accumulate a 1.6 × 108 m3 lake. By 2001, the water had risen to the fault-controlled Maraunot Notch, the lowest, northwestern portion of the caldera rim comprising the physiographic sill of the Caldera Lake. That year, a narrow artificial canal dug into an old volcanic breccia underlying the outlet channel failed to induce a deliberate lake breakout, but discharge from heavy rains in July 2002 rapidly deepened the notch by 23 m, releasing an estimated 6.5 × 107 m3 of lake water that bulked up into lahars with a volume well in excess of 1.6 × 108 m3. Lakes in other volcanoes have experienced multiple breakouts, providing practical motivation for this study. Fieldwork and high-resolution digital elevation models reveal andesites and ancient lacustrine deposits, strongly fractured and deformed along a segment of the Maraunot Fault, a prominent, steeply dipping, left-lateral fault zone that trends N35° 40°W within and parallel to the notch. Seismicity in 1991 demonstrated that the Maraunot Fault is still active. The fault zone appears to have previously been the erosional locus for a large channel, filled with avalanche or landslide deposits of an earlier eruption that were exhumed by the 2002 breakout floods. The deformed lacustrine sediments, with an uncalibrated 14C age of 14,760 ± 40 year BP from a single charcoal sample, attest to the existence of an earlier lake, possibly within the Tayawan Caldera, rim remnants of which survive as arcuate escarpments. That lake may well have experienced one or more ancient breakouts as well. The 2002 event greatly reduced the possibility of another such event by scouring away the erodible breccia, leaving less erodible

  20. Workshop on hydrologic and geochemical monitoring in the Long Valley Caldera: proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Sorey, M.L.; Farrar, C.D.; Wollenberg, H.A.

    1984-10-01

    A workshop reviewed the results of hydrologic and geochemical monitoring in the Long Valley caldera. Such monitoring is being done to detect changes in the hydrothermal system induced by ongoing magmatic and tectonic processes. Workshop participants discussed the need to instrument sites for continuous measurements of several parameters and to obtain additional hydrologic and chemical information from intermediate and deep drill holes. In addition to seismic and deformation monitoring, programs are currently in progress to monitor changes in the discharge characteristics of hot springs, fumaroles, and soil gases, as well as pressures and temperatures in wells. Some hydrochemical parameters are measured continuously, others are measured monthly or at longer intervals. This report summarizes the information presented at the hydrologic monitoring workshop, following the workshop agenda which was divided into four sessions: (1) overview of the hydrothermal system; (2) monitoring springs, fumaroles, and wells; (3) monitoring gas emissions; and (4) conclusions and recommendations.

  1. PRESENT STATE OF THE HYDROTHERMAL SYSTEM IN LONG VALLEY CALDERA, CALIFORNIA.

    Science.gov (United States)

    Sorey, Michael L.

    1985-01-01

    Results of test drilling to depths of 2 km and data on the chemical and isotopic content of waters from hot springs and fumaroles permit a conceptual model of the present-day hydrothermal system in Long Valley caldera to be delineated. The model consists of two principal zones in which hot water flows laterally from west to east at depths less than 1 km within and around the resurgent dome. Maximum measured temperatures within these zones are near 170 degree C, but estimates from chemical geothermometers and extrapolation of a high temperature gradient measured in a recent drill hole indicate that a source reservoir at temperatures near 240 degree C may exist at greater depths in the Bishop Tuff beneath the west moat.

  2. Fuzzy Clustering

    DEFF Research Database (Denmark)

    Berks, G.; Keyserlingk, Diedrich Graf von; Jantzen, Jan

    2000-01-01

    A symptom is a condition indicating the presence of a disease, especially, when regarded as an aid in diagnosis.Symptoms are the smallest units indicating the existence of a disease. A syndrome on the other hand is an aggregate, set or cluster of concurrent symptoms which together indicate...... and clustering are the basic concerns in medicine. Classification depends on definitions of the classes and their required degree of participant of the elements in the cases' symptoms. In medicine imprecise conditions are the rule and therefore fuzzy methods are much more suitable than crisp ones. Fuzzy c......-mean clustering is an easy and well improved tool, which has been applied in many medical fields. We used c-mean fuzzy clustering after feature extraction from an aphasia database. Factor analysis was applied on a correlation matrix of 26 symptoms of language disorders and led to five factors. The factors...

  3. Fiber-Reinforced Rocks Akin to Roman Concrete Help Explain Ground Deformation at Campi Flegrei Caldera

    Science.gov (United States)

    Vanorio, Tiziana; Kanitpanyacharoen, Waruntorn

    2016-04-01

    The caldera of Campi Flegrei is one of the active hydrothermal systems of the Mediterranean region experiencing notable unrest episodes in a densely populated area. During the last crisis of 1982-1984, nearly 40,000 people were evacuated for almost two years from the main town of Pozzuoli, the Roman Puteoli, due to the large uplifts (~2 m over two years) and the persistent seismic activity. The evacuation severely hampered the economy and the social make-up of the community, which included the relocation of schools and commercial shops as well as the harbor being rendered useless for docking. Despite the large uplifts, the release of strain appears delayed. Seismicity begins and reaches a magnitude of 4.0 only upon relatively large uplifts (~ 70-80 cm) contrary to what is generally observed for calderas exhibiting much lower deformation levels. Over and above the specific mechanism causing the unrest and the lack of identification of a shallow magmatic reservoir (concrete. The formation of fibrous minerals by intertwining filaments confers shear and tensile strength to the caprock, contributing to its ductility and increased resistance to fracture. The importance of the findings reported in this study lies not only on the fibrous and compositionally nature of the caprock but also on its possible physicochemical deterioration. Given the P-T-XCO2 conditions regulating the decarbonation reactions, the influx of new fluids into the Campi Flegrei system lowers the temperature of the decarbonation reaction and dilutes the existing CO2, thus triggering additional CO2, methane, and steam to form. As these gases rise toward the surface, the natural cement layer halts them, leading to pore pressure increase and subsequent ground deformations.

  4. Petrogenesis of Rinjani Post-1257-Caldera-Forming-Eruption Lava Flows

    Directory of Open Access Journals (Sweden)

    Heryadi Rachmat

    2016-08-01

    Full Text Available After the catastrophic 1257 caldera-forming eruption, a new chapter of Old Rinjani volcanic activity beganwith the appearance of Rombongan and Barujari Volcanoes within the caldera. However, no published petrogeneticstudy focuses mainly on these products. The Rombongan eruption in 1944 and Barujari eruptions in pre-1944, 1966,1994, 2004, and 2009 produced basaltic andesite pyroclastic materials and lava flows. A total of thirty-one sampleswere analyzed, including six samples for each period of eruption except from 2004 (only one sample. The sampleswere used for petrography, whole-rock geochemistry, and trace and rare earth element analyses. The Rombonganand Barujari lavas are composed of calc-alkaline and high K calc-alkaline porphyritic basaltic andesite. The magmashows narrow variation of SiO2 content that implies small changes during its generation. The magma that formedRombongan and Barujari lavas is island-arc alkaline basalt. Generally, data show that the rocks are enriched in LargeIon Lithophile Elements (LILE: K, Rb, Ba, Sr, and Ba and depleted in High Field Strength Elements (HFSE: Y, Ti,and Nb which are typically a suite from a subduction zone. The pattern shows a medium enrichment in Light REEand relatively depleted in Heavy REE. The processes are dominantly controlled by fractional crystallization andmagma mixing. All of the Barujari and Rombongan lavas would have been produced by the same source of magmawith little variation in composition caused by host rock filter process. New flux of magma would likely have occurredfrom pre-1944 until 2009 period that indicates slightly decrease and increase of SiO2 content. The Rombongan andBarujari lava generations show an arc magma differentiation trend.

  5. Abrupt transition from fractional crystallization to magma mixing at Gorely volcano (Kamchatka) after caldera collapse

    Science.gov (United States)

    Gavrilenko, Maxim; Ozerov, Alexey; Kyle, Philip R.; Carr, Michael J.; Nikulin, Alex; Vidito, Christopher; Danyushevsky, Leonid

    2016-07-01

    A series of large caldera-forming eruptions (361-38 ka) transformed Gorely volcano, southern Kamchatka Peninsula, from a shield-type system dominated by fractional crystallization processes to a composite volcanic center, exhibiting geochemical evidence of magma mixing. Old Gorely, an early shield volcano (700-361 ka), was followed by Young Gorely eruptions. Calc-alkaline high magnesium basalt to rhyolite lavas have been erupted from Gorely volcano since the Pleistocene. Fractional crystallization dominated evolution of the Old Gorely magmas, whereas magma mixing is more prominent in the Young Gorely eruptive products. The role of recharge-evacuation processes in Gorely magma evolution is negligible (a closed magmatic system); however, crustal rock assimilation plays a significant role for the evolved magmas. Most Gorely magmas differentiate in a shallow magmatic system at pressures up to 300 MPa, ˜3 wt% H2O, and oxygen fugacity of ˜QFM + 1.5 log units. Magma temperatures of 1123-1218 °C were measured using aluminum distribution between olivine and spinel in Old and Young Gorely basalts. The crystallization sequence of major minerals for Old Gorely was as follows: olivine and spinel (Ol + Sp) for mafic compositions (more than 5 wt% of MgO); clinopyroxene and plagioclase crystallized at ˜5 wt% of MgO (Ol + Cpx + Plag) and magnetite at ˜3.5 wt% of MgO (Ol + Cpx + Plag + Mt). We show that the shallow magma chamber evolution of Old Gorely occurs under conditions of decompression and degassing. We find that the caldera-forming eruption(s) modified the magma plumbing geometry. This led to a change in the dominant magma evolution process from fractional crystallization to magma mixing. We further suggest that disruption of the magma chamber and accompanying change in differentiation process have the potential to transform a shield volcanic system to that of composite cone on a global scale.

  6. Petrogenesis of Rinjani Post-1257-Caldera-Forming-Eruption Lava Flows

    Directory of Open Access Journals (Sweden)

    Heryadi Rachmat

    2016-06-01

    Full Text Available DOI:10.17014/ijog.3.2.107-126After the catastrophic 1257 caldera-forming eruption, a new chapter of Old Rinjani volcanic activity beganwith the appearance of Rombongan and Barujari Volcanoes within the caldera. However, no published petrogeneticstudy focuses mainly on these products. The Rombongan eruption in 1944 and Barujari eruptions in pre-1944, 1966,1994, 2004, and 2009 produced basaltic andesite pyroclastic materials and lava flows. A total of thirty-one sampleswere analyzed, including six samples for each period of eruption except from 2004 (only one sample. The sampleswere used for petrography, whole-rock geochemistry, and trace and rare earth element analyses. The Rombonganand Barujari lavas are composed of calc-alkaline and high K calc-alkaline porphyritic basaltic andesite. The magmashows narrow variation of SiO2 content that implies small changes during its generation. The magma that formedRombongan and Barujari lavas is island-arc alkaline basalt. Generally, data show that the rocks are enriched in LargeIon Lithophile Elements (LILE: K, Rb, Ba, Sr, and Ba and depleted in High Field Strength Elements (HFSE: Y, Ti,and Nb which are typically a suite from a subduction zone. The pattern shows a medium enrichment in Light REEand relatively depleted in Heavy REE. The processes are dominantly controlled by fractional crystallization andmagma mixing. All of the Barujari and Rombongan lavas would have been produced by the same source of magmawith little variation in composition caused by host rock filter process. New flux of magma would likely have occurredfrom pre-1944 until 2009 period that indicates slightly decrease and increase of SiO2 content. The Rombongan andBarujari lava generations show an arc magma differentiation trend.

  7. New constraints on mechanisms of remotely triggered seismicity at Long Valley Caldera

    Science.gov (United States)

    Brodsky, E.E.; Prejean, S.G.

    2005-01-01

    Regional-scale triggering of local earthquakes in the crust by seismic waves from distant main shocks has now been robustly documented for over a decade. Some of the most thoroughly recorded examples of repeated triggering of a single site from multiple, large earthquakes are measured in geothermal fields of the western United States like Long Valley Caldera. As one of the few natural cases where the causality of an earthquake sequence is apparent, triggering provides fundamental constraints on the failure processes in earthquakes. We show here that the observed triggering by seismic waves is inconsistent with any mechanism that depends on cumulative shaking as measured by integrated energy density. We also present evidence for a frequency-dependent triggering threshold. On the basis of the seismic records of 12 regional and teleseismic events recorded at Long Valley Caldera, long-period waves (>30 s) are more effective at generating local seismicity than short-period waves of comparable amplitude. If the properties of the system are stationary over time, the failure threshold for long-period waves is ~0.05 cm/s vertical shaking. Assuming a phase velocity of 3.5 km/s and an elastic modulus of 3.5 x 1010Pa, the threshold in terms of stress is 5 kPa. The frequency dependence is due in part to the attenuation of the surface waves with depth. Fluid flow through a porous medium can produce the rest of the observed frequency dependence of the threshold. If the threshold is not stationary with time, pore pressures that are >99.5% of lithostatic and vary over time by a factor of 4 could explain the observations with no frequency dependence of the triggering threshold. Copyright 2005 by the American Geophysical Union.

  8. Isotopic and trace element characteristics of rhyolites from the Valles Caldera, New Mexico. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Self, S.; Sykes, M.L. [Hawaii Univ., Honolulu, HI (United States). Dept. of Geology and Geophysics; Wolff, J.A. [Texas Univ., Arlington, TX (United States). Dept. of Geology; Skuba, C.E. [McMaster Univ., Hamilton, ON (Canada). Dept. of Geology

    1991-09-01

    This report is a summary of work supported by DOE grant No. DE-FGO5-87ER13795 that was completed or is still in progress. The stated purpose of this grant was to collect geochemical information (trace element, radiogenic isotope and stable oxygen and hydrogen isotope) on samples from core holes VC-I and VC-2a in the Valles caldera in order to establish a consistent detailed intracaldera stratigraphy and relate this to extracaldera volcanic rock units of the Jemez Mountains. Careful stratigraphic control of the intracaldera units is necessary to evaluate models of caldera formation, ignimbrite deposition, and resurgence. Combined stable and radiogenic isotope and trace element data will also provide major insights to petrogenesis of the Bandelier magma system. The composition of non-hydrothermally altered samples from outflow units of the Bandelier Tuff and related volcanics must be known to assess isotopic variations of intracaldera ignimbrite samples. On detailed examination of the VC-2a core samples, it became apparent that hydrothermal alteration is so extensive that no geochemical information useful for stratigraphic fingerprinting or petrogenesis could be obtained, and that correlation with other intracaldera units and extracaldera units must be made on the basis of stratigraphic position and gross lithologic characteristics. Accordingly, we emphasize geochemical data from the extracaldera Bandelier Tuffs and related units which will be useful for comparison with proposed drill hole VC-4 and for any future studies of the region. The stable isotope, radiogenic isotope and trace element data obtained from this project, combined with existing major and trace element data for volcanic rocks from this area, provide an extensive data base essential to future Continental Scientific Drilling Program projects in the Jemez Mountains of New Mexico.

  9. Juan Moctezuma y Cortés: cacique, cura e insurgente (1754/57-1816)1/Juan Moctezuma and Cortés: Cacique, Priest and Insurgent (1754/57-1816)

    National Research Council Canada - National Science Library

    Patricia Cruz Pazos

    2011-01-01

    This paper analyses Juan Moctezuma and Cortés' figure, one of the four hundred insurgent priests that lived in New Spain, in order to tackle his origin and vital experience during the last years of colonial period...

  10. Cultura y espiritualidad en la edad moderna valenciana: Juan de Juanes y el ostensorio bifaz de la iglesia parroquial de San Andrés de l’Alcúdia

    Directory of Open Access Journals (Sweden)

    Franco Llopis, Borja

    2009-09-01

    Full Text Available Taking as a starting point the paintings of Juan de Juanes for the church of l’Alcúdia, the author analyses the social questions that might have had a bearing on his artistic production, iconography and diffusion in the Valencian sphere. The possible influence of Erasmus, intimist philosophy, the Christology of Eiximenis and the indoctrination of the Moriscos are some of the aspects discussed.

    En este artículo, partiendo de las pinturas de Juan de Juanes en l’Alcúdia, analizamos las cuestiones sociales que pudieron incidir en su producción artística, iconografía y difusión dentro del ámbito valenciano. La posible influencia del erasmismo, la filosofía intimista, la cristología de Eiximenis o el adoctrinamiento a los moriscos son algunos aspectos sobre los que centramos nuestra reflexión.

  11. Phylogenetic and Physiological Diversity of Subseafloor Microbial Communities at Axial Seamount, Juan de Fuca Ridge: Summary of Results From the New Millenium Observatory (NeMO), 1998-2004

    Science.gov (United States)

    Baross, J. A.; Huber, J. A.; Mehta, M. P.; Opatkiewicz, A.; Bolton, S. A.; Butterfield, D. A.; Sogin, M. L.; Embley, R. W.

    2005-12-01

    Axial Seamount (45 ° 58' N; 130 ° 00' W) is an active submarine volcano located on the Juan de Fuca Ridge, approximately 300 miles off the coast of Oregon. Lying at the intersection of a seamount chain and a spreading axis, Axial is a unique study site from both the geological and biological perspective. In January of 1998, Axial experienced a week-long series of earthquakes, and subsequent water column and seafloor observations on the southeast portion of the caldera found temperature and chemical anomalies, extensive new seafloor lava flows, large "snow blower" type vents, and other characteristics commonly associated with diking-eruptive events. Due to its high activity and close proximity to shore, Axial was chosen as a site for a multi-year observatory (New Millenium Observatory, NeMO) to document changes and interactions between geology, chemistry, and biology on the mid-ocean ridge system. From 1998 through 2004, we extensively sampled diffuse vents at Axial Seamount to determine the physiological and phylogenetic diversity of subseafloor microbial communities and their relationship to the geochemical environment. Here we present a summary of those studies, including molecular-based phylogenetic surveys of bacteria, archaea, and potential nitrogen-fixing organisms, culturing results of thermophiles and hyperthermophiles from over 20 sites, and the distribution of one particular group of hyperthermophiles at diffuse vents throughout the caldera and how that distribution may be linked to the geochemical habitat. Results indicate that Axial supports a diverse subseafloor microbial community, including hydrogen and sulfur oxidizers, hyperthermophilic methane producers and heterotrophs, and many organisms with the potential to fix nitrogen. In addition, we find that the species composition of the microbial community changes in response to changes in the physical and chemical conditions at each vent site. The extent of seawater mixing with hydrothermal fluids

  12. Magnetic structure of Bayonnaise knoll caldera including Hakurei hydrothermal site obtained from near-bottom magnetic vector field mapping by autonomous underwater vehicle

    Science.gov (United States)

    Honsho, C.; Ura, T.; Kim, K.

    2012-12-01

    The Bayonnaise knoll caldera is one of the silicic submarine calderas in the Izu-Ogasawara Arc in Japan. In 2003, a large-scale hydrothermal deposit was found in the caldera, called the Hakurei deposit. The caldera had been explored by four surveys using autonomous underwater vehicles (AUVs) from 2008 to 2011, and the near-bottom magnetic field was mapped over about 75% of the caldera floor. We carried out detailed correction for the magnetic field produced by the vehicle body, which allowed us to take advantage of the vector anomaly instead of the total anomaly for the magnetic inversion. We applied the inversion method using the block model together with the Akaike's Bayesian information criterion (ABIC). One remarkable thing is that we recognized significant difference between the magnetic inversion result using the vector anomaly and that using the total anomaly: the latter result explains the observed total anomalies excellently, but does not explain the vector anomalies adequately. Except for a rare case where the vector anomaly is perpendicular to the main field throughout, the total anomaly should be sufficient for evaluating the entire field, provided that the data is collected in sufficiently high density. In fact, the track lines of our survey sometimes separate from each other by about twice the altitude of the vehicle (100 m), which can lead to considerable aliasing in the sampled field. The vector anomaly can provide vital information in such a situation. The obtained magnetization distribution is well correlated with the topography. The caldera rim and central cone have weak magnetization, which is consistent with the fact that they consist of dacite rocks. On the other hand, the caldera floor shows high magnetization, which implies the existence of basaltic rocks. The high magnetization appears to continue north and south beyond the caldera rim, forming an NS-trending high magnetization zone. Because the caldera floor is generally covered with

  13. Alteration in the Madera limestone and Sandia formation from core hole VC-1 Valles Caldera, New Mexico

    Science.gov (United States)

    Keith, Terry E. C.

    1988-06-01

    Core hole VC-1 penetrated the southwestern ring fracture zone of the 1.1 Ma Valles caldera and at a depth of 333 m intersected the top of the Paleozoic section including the Abo Formation, Madera Limestone, and Sandia Formation, reaching a total depth of 856 m. The Paleozoic rocks, which consist of thin-bedded limestone, siltstone, mudstone, sandstone, and local conglomerate, are overlain by volcanic rocks of the caldera moat that are less than 0.6 Ma. Diagenetic and at least three hydrothermal alteration stages were identified in the Madera Limestone and Sandia Formation. Diagenetic clay alteration was pervasive throughout the sedimentary rocks. Volcanic activity at 16.5 Ma and continuing through the formation of the Valles caldera resulted in high thermal gradients, which caused recrystallization of diagenetic clay minerals. Interstratified smectite-illite is the most diagnostic clay mineral throughout the section; structurally, the illite component in the ordered interstratified illite-smectite changes gradationally from 70% at the top of the Madera Limestone to 95% at the base of the section in the Sandia Formation. Pyrite that occurs as small clots and lenses as well as finely disseminated is interpreted as being of diagenetic origin, especially in organic-rich beds. Low permeability of much of the Paleozoic section precluded the deposition of hydrothermal minerals except in fractures and intergranular space in some of the more permeable sandstone and brecciated horizons. Three stages of hydrothermal mineral deposition are defined. Stage I is widespread and includes mainly chlorite, calcite, pyrite, and interstratified smectite-illite that was formed prior to caldera development at temperatures approximating 200°C. Stage II is characterized by quartz, sericite, and scarce sulfides deposited locally by fluids at approximately 275°C shortly before or at the time of early caldera-related volcanism. The Stage III hydrothermal event, associated with formation of

  14. Data points (drill locations) used to assess coal resources in the San Juan Basin, CO and NM (sjbptsg)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This is a shapefile and coverage of data points used in the assessment of coal resources of the Fruitland Formation in the San Juan Basin, Colorado and New Mexico....

  15. Digital Geologic Map of San Juan Island National Historical Park and vicinity, Washington (NPS, GRD, GRE, SAJH, SAJH digital map)

    Data.gov (United States)

    National Park Service, Department of the Interior — The Digital Geologic Map of San Juan Island National Historical Park and vicinity, Washington is composed of GIS data layers complete with ArcMap 9.2 layer (.LYR)...

  16. Geology of the Orcopampa 30 minute quadrangle, southern Peru with special focus on the evolution of the Chinchon and Huayta calderas

    Science.gov (United States)

    Swanson, Kirk Edward

    The 30 minute Orcopampa quadrangle, southern Peru, was a site of several episodes of Neogene volcanism, hydrothermal activity and precious-metal mineralization. Lavas of pyroxene andesite and associated silicic tuffs of the early Miocene Santa Rosa volcanics are the remnants of stratovolcanoes overlying an irregular erosional surface developed on a transgressive Mesozoic marine succession. Major ash-flow volcanism then resulted in the 20.1 Ma Manto Tuff and the associated Chinchon caldera. Deep dissection, locally >2 km, has exposed the steep caldera margin, slide blocks and related (19.9 Ma) dikes. Flows and domes of hornblende-biotite dacite comprising the Sarpane volcanics were erupted between about 18.5--19.5 Ma over much of the northern part of the quadrangle. Early Miocene rocks were folded during the Quechua I tectonic event, and related ENE-trending normal faults host the 17.8 Ma Ag-Au veins of the Orcopampa district. Eruption of the ca. 11.6 Ma tuffs of Cerro Huayta and Cerro Hospicio resulted in formation of the Huayta caldera, nested within the northern part of the Chinchon caldera. Caldera formation was associated with, and followed by, the eruption of intermediate lavas of Cerro Sahuarque ( ca. 11.4 Ma) and the emplacement of rhyolite domes. The adularia-sericite type Au-Ag veins of Mina Shila were formed along the southern margin of the Huayta caldera several million years after collapse. The 7.3 Ma tuff of Laguna Pariguanas, erupted from vents northeast of the Huayta caldera, appears to be deformed; however, the 6.2 Ma tuff of Umachulco postdates Quechua II/III tectonism. Flows and domes of the ca. 7.2 Ma andesite of Cerro Aseruta were emplaced within the Huayta caldera, and approximately contemporaneous lavas of silicic to intermediate composition were erupted in the northern part of the quadrangle. A large area of largely barren acid-sulfate alteration (Chuchanne) formed within the Huayta caldera shortly after the eruption of the andesite of Cerro

  17. Pucarilla-Cerro Tipillas volcanic complex: the oldest recognized caldera in the southeastern portion of central volcanic zone of Central Andes?

    Energy Technology Data Exchange (ETDEWEB)

    Guzman, Silvina; Petrinovic, Ivan [CONICET -IBIGEO. Museo de Cs. Naturales, Universidad de Salta, Mendoza 2 (4400), Salta (Argentina)], E-mail: guzmansilvina@gmail.com

    2008-10-01

    We recognize the most eastern and oldest collapse caldera structure in the southern portion of the Central Volcanic Zone of the Andes. A description of Middle-Upper Miocene successions related to explosive- effusive events is presented. The location of this centre close to Cerro Galn Caldera attests a recurrence in the volcanism between 12 and 2 Ma in this portion of the Altiplano - Puna Plateau.

  18. The Highly Polarized Open Cluster Trumpler 27

    Science.gov (United States)

    Feinstein, Carlos; Baume, Gustavo; Vazquez, Ruben; Niemela, Virpi; Cerruti, Miguel Angel

    2000-10-01

    We have carried out multicolor linear polarimetry (UBVRI) of the brightest stars in the area of the open cluster Trumpler 27. Our data show a high level of polarization in the stellar light with a considerable dispersion, from P=4% to P=9.5%. The polarization vectors of the cluster members appear to be aligned. Foreground polarization was estimated from the data of some nonmember objects, for which two different components were resolved: the first one associated with a dust cloud close to the Sun producing Pλmax=1.3% and θ=146°, and a second component, the main source of polarization for the cluster members, originating in another dust cloud, which polarizes the light in the direction of θ=29.5d. From a detailed analysis, we found that the two components have associated values EB-V0.75 for the other. Due the difference in the orientation of both polarization vectors, almost 90° (180° at the Stokes representation), the first cloud (θ~146°) depolarizes the light strongly polarized by the second one (θ~29.5d). Based on observations obtanined at Complejo Astronómico El Leoncito (CASLEO), operated under agreement between CONICET and the National Universities of La Plata, Córdoba, and San Juan, Argentina.

  19. Cluster forcing

    DEFF Research Database (Denmark)

    Christensen, Thomas Budde

    .g. sustainability or quality of life. The purpose of this paper is to explore how and to what extent public sector interventions that aim at forcing cluster development in industries can support sustainable development as defined in the Brundtland tradition and more recently elaborated in such concepts as eco......, Portugal and New Zealand have adopted the concept. Public sector interventions that aim to support cluster development in industries most often focus upon economic policy goals such as enhanced employment and improved productivity, but rarely emphasise broader societal policy goals relating to e...... to the automotive sector in Wales. Specifically, the paper evaluates the "Accelerates" programme initiated by the Welsh Development Agency and elaborates on how and to what extent the Accelerate programme supports the development of a sustainable automotive industry cluster. The Accelerate programme was set up...

  20. Some aspects of the volcanology and geochemistry of the Tengger Caldera, Java, Indonesia: eruption of a K-rich tholeiitic series

    Science.gov (United States)

    van Gerven, M.; Pichler, H.

    The Tengger Caldera together with the active Mount Bromo is situated in Java, Indonesia. Though activity of Mt Bromo has been recorded since 1804, little modern petrographic and geochemical data is available. In this study we provide a detailed petrographic and stratigraphic description of the two major caldera units, i.e. the "pre-caldera formation" and the "post-caldera formation". A zonal arrangement of the alkali content of the Sunda arc volcanoes, i.e. an increase of the alkali content in the lavas across the arc from the trench to the backarc basin, has been noticed for many years. In contrast to the common classification of the geochemistry and magmatic affinity of the Javanese volcanoes related to the depth of the Benioff zone (100-150 km for tholeiitic rocks and 150-250 km for calc-alkaline rocks), we found a tholeiitic trend expressed by increasing FeO∗/MgO with increasing SiO 2 and an average {Zr}/{Y} ratio of 4.9 for the Tengger Caldera volcanics (Benioff zone depth ca 200 km), despite high alkali contents (K 2O > 2 wt%). These features characterize the Tengger Caldera volcanics as medium to high-K tholeiitic andesites and basaltic andesites.

  1. First CSDP (Continental Scientific Drilling Program)/thermal regimes core hole project at Valles Caldera, New Mexico (VC-1): Drilling report

    Energy Technology Data Exchange (ETDEWEB)

    Rowley, J.; Hawkins, W.; Gardner, J. (comps.)

    1987-02-01

    This report is a review and summary of the core drilling operations of the first Valles Caldera research borehole (VC-1) under the Thermal Regimes element of the Continental Scientific Drilling Program (CSDP). The project is a portion of a broader program that seeks to answer fundamental scientific questions about magma, rock/water interactions, and volcanology through shallow (<1-km) core holes at Long Valley, California; Salton Sea, California; and the Valles Caldera, New Mexico. The report emphasizes coring operations with reference to the stratigraphy of the core hole, core quality description, core rig specifications, and performance. It is intended to guide future research on the core and in the borehole, as well as have applications to other areas and scientific problems in the Valles Caldera. The primary objectives of this Valles Caldera coring effort were (1) to study the hydrogeochemistry of a subsurface geothermal outflow zone of the caldera near the source of convective upflow, (2) to obtain structural and stratigraphic information from intracaldera rock formations in the southern ring-fracture zone, and (3) to obtain continuous core samples through the youngest volcanic unit in Valles Caldera, the Banco Bonito rhyolite (approximately 0.1 Ma). All objectives were met. The high percentage of core recovery and the excellent quality of the samples are especially notable. New field sample (core) handling and documentation procedures were successfully utilized. The procedures were designed to provide consistent field handling of the samples and logs obtained through the national CSDP.

  2. EL CAMINO DEL INCA ENTRE TOCOTA Y VILLA NUEVA (VALLE DE IGLESIA, SAN JUAN / The Inka road between Tocota and Villa Nueva (Iglesia Valley, San Juan

    Directory of Open Access Journals (Sweden)

    Alejandro García

    2011-12-01

    Full Text Available La vialidad estatal incaica en los valles longitudinales de la provincia de San Juan, en el extremo SE del Tawantinsuyu, ha sido objeto de diversas consideraciones durante el último siglo. Sin embargo, no se han realizado estudios específicos destinados a comprobar su existencia, la cual incluso ha sido negada recientemente. A fin de aclarar el tema se realizó el relevamiento de un sector del Valle de Iglesia. En este artículo se presentan los resultados de ese estudio, junto con una revisión y discusión de los antecedentes y de algunas ideas vinculadas con el tema. Fundamentalmente, se verifica la presencia del Qhapaq Ñan en la parte baja del sector analizado, se refuta la propuesta de que el trazado longitudinal principal se habría extendido por la parte alta del sector precordillerano y se sostiene que el tramo relevado fue recorrido por Debenedetti a principios del siglo XX, aunque sin advertir que se trataba del camino incaico.   Palabras clave: Inca; Camino del Inca; Dominación incaica; Collasuyo; San Juan   Abstract The Inka road system in the longitudinal valleys of San Juan province, in the southeastern end of Tawantinsuyu, has been subject of several considerations during the last century. However, no specific studies have been undertaken to verify its existence, which recently has been even denied. To clarify the issue we surveyed a section of Iglesia Valley. This article presents the results of that study, along with a review and discussion of the background and of some ideas related to the topic. Basically, the presence of the Qhapaq Ñan at the bottom of the surveyed sector is verified, and the suggestion that the main inka longitudinal route would have extended over the top of the precordilleran mountain region is refused. Also, it is argued that the analyzed stretch was traveled by Debenedetti in the beginnings of the twentieth century, but without realizing that it was the Inka road.   Keywords: Inka; Inka Road; Inka

  3. Typology of Natural Hazards and Assessment of Associated Risks in the Mount Bambouto Caldera (Cameroon Line, West Cameroon)

    Institute of Scientific and Technical Information of China (English)

    Ghislain T. ZANGMO; Armand D. KAGOU; David G. NKOUATHIO; Pierre WANDJI

    2009-01-01

    Mount Bambouto is a polygenic stratovoicano of the Cameroon Volcanic Line, built between 21 Ma and 4.5 Ma. It is situated approximately 200 km NE of Mount Cameroon, between 09°55' and 10°15' longitude east and, 05°25' and 05°50' latitude north. The volcano covers an area of (13×8 km). Mount Bambouto is characterized by several natural hazards of different origins: meteorological, such as landslides and rock falls; anthropogenic, such as bushfires, tribal wars and deforestation; and volcanological, such as volcanic eruption. The thematic map shows that 55-60% of the caldera has high probability of occurrence of mass movement. The caldera has a high population density (3000 inhabitants), which increases the level of risk, evaluated at approximately $US3.8 million for patrimony, 3000 civilian deaths and destruction of biodiversity.

  4. Rapid differentiation in a sill-like magma reservoir: a case study from the campi flegrei caldera.

    Science.gov (United States)

    Pappalardo, Lucia; Mastrolorenzo, Giuseppe

    2012-01-01

    In recent decades, geophysical investigations have detected wide magma reservoirs beneath quiescent calderas. However, the discovery of partially melted horizons inside the crust is not sufficient to put constraints on capability of reservoirs to supply cataclysmic eruptions, which strictly depends on the chemical-physical properties of magmas (composition, viscosity, gas content etc.), and thus on their differentiation histories. In this study, by using geochemical, isotopic and textural records of rocks erupted from the high-risk Campi Flegrei caldera, we show that the alkaline magmas have evolved toward a critical state of explosive behaviour over a time span shorter than the repose time of most volcanic systems and that these magmas have risen rapidly toward the surface. Moreover, similar results on the depth and timescale of magma storage were previously obtained for the neighbouring Somma-Vesuvius volcano. This consistency suggests that there might be a unique long-lived magma pool beneath the whole Neapolitan area.

  5. Overview for geologic field-trip guides to Mount Mazama, Crater Lake Caldera, and Newberry Volcano, Oregon

    Science.gov (United States)

    Bacon, Charles R.; Donnelly-Nolan, Julie M.; Jensen, Robert A.; Wright, Heather M.

    2017-08-16

    These field-trip guides were written for the occasion of the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI) quadrennial scientific assembly in Portland, Oregon, in August 2017. The guide to Mount Mazama and Crater Lake caldera is an updated and expanded version of the guide (Bacon, 1989) for part of an earlier IAVCEI trip to the southern Cascade Range. The guide to Newberry Volcano describes the stops included in the 2017 field trip. Crater Lake and Newberry are the two best-preserved and most recent calderas in the Cascades Volcanic Arc. Although located in different settings in the arc, with Crater Lake on the arc axis and Newberry in the rear-arc, both volcanoes are located at the intersection of the arc and the northwest corner region of the extensional Basin and Range Province.

  6. Caldera collapse: Perspectives from comparing Galápagos volcanoes, nuclear-test sinks, sandbox models, and volcanoes on Mars

    Science.gov (United States)

    Howard, K.A.

    2010-01-01

    The 1968 trapdoor collapse (1.5 km3) of Fernandina caldera in the Galapágos Islands developed the same kinds of structures as found in small sandbox-collapse models and in concentrically zoned sinks formed in desert alluvium by fault subsidence into underground nuclear-explosion cavities. Fernandina’s collapse developed through shear failure in which the roof above the evacuating chamber was lowered mostly intact. This coherent subsidence contrasts to chaotic piecemeal collapse at small, rocky pit craters, underscoring the role of rock strength relative to subsidence size. The zoning at Fernandina implies that the deflated magma chamber underlay a central basin and a bordering inward-dipping monocline, which separates a blind inner reverse fault from an outer zone of normal faulting. Similar concentric zoning patterns can be recognized in coherent subsidence structures ranging over 16 orders of magnitude in size, from sandbox experiments to the giant Olympus Mons caldera on Mars.

  7. Visit of His Excellency Mr Juan Martabit, Ambassador, Permanent Representative of Chile to the United Nations Office in Geneva and other international organisations in Switzerland.

    CERN Multimedia

    Maximilien Brice

    2005-01-01

    Secretary-General; Mrs Juan Martabit. 0502017_07.jpg His Excellency Mr Juan Martabit, Ambassador,Permanent Representative of Chile to the United Nations Office in Geneva and other international organisations in Switzerland visiting the ATLAS building site. From left to right: Prof. Giora Mikenberg, ATLAS Collaboration; Mr Maximilian Metzger, Secretary-General and His Excellency Mr Juan Martabit. 0502017_08.jpg His Excellency Mr Juan Martabit, Ambassador,Permanent Representative of Chile to the United Nations Office in Geneva and other international organisations in Switzerland visiting the ATLAS cavern. From left to right: From left to right: Prof. Giora Mikenberg, ATLAS Collaboration; Mr Maximilian Metzger, Secretary-General; His Excellency Mr Juan Martabit and Mrs Juan Martabit.

  8. Aquifer Recharge Estimation through Atmospheric Chloride Mass Balance at Las Cañadas Caldera, Tenerife, Canary Islands, Spain

    OpenAIRE

    Rayco Marrero-Diaz; Alcalá, Francisco J.; Pérez, Nemesio M.; Dina L. López; Melián, Gladys V.; Eleazar Padrón; Germán D. Padilla

    2015-01-01

    The atmospheric chloride mass balance (CMB) method was used to estimate net aquifer recharge in Las Cañadas Caldera, an endorheic summit aquifer area about 2000 m a.s.l. with negligible surface runoff, which hosts the largest freshwater reserve in Tenerife Island, Canary Islands, Spain. The wet hydrological year 2005–2006 was selected to compare yearly atmospheric chloride bulk deposition and average chloride content in recharge water just above the water table, both deduced from periodical...

  9. The Late Cretaceous Middle Fork caldera, its resurgent intrusion, and enduring landscape stability in east-central Alaska

    Science.gov (United States)

    Bacon, Charles R.; Dusel-Bacon, Cynthia; Aleinikoff, John N.; Slack, John F.

    2014-01-01

    Dissected caldera structures expose thick intracaldera tuff and, uncommonly, cogenetic shallow plutons, while remnants of correlative outflow tuffs deposited on the pre-eruption ground surface record elements of ancient landscapes. The Middle Fork caldera encompasses a 10 km × 20 km area of rhyolite welded tuff and granite porphyry in east-central Alaska, ∼100 km west of the Yukon border. Intracaldera tuff is at least 850 m thick. The K-feldspar megacrystic granite porphyry is exposed over much of a 7 km × 12 km area having 650 m of relief within the western part of the caldera fill. Sensitive high-resolution ion microprobe with reverse geometry (SHRIMP-RG) analyses of zircon from intracaldera tuff, granite porphyry, and outflow tuff yield U-Pb ages of 70.0 ± 1.2, 69.7 ± 1.2, and 71.1 ± 0.5 Ma (95% confidence), respectively. An aeromagnetic survey indicates that the tuff is reversely magnetized, and, therefore, that the caldera-forming eruption occurred in the C31r geomagnetic polarity chron. The tuff and porphyry have arc geochemical signatures and a limited range in SiO2 of 69 to 72 wt%. Although their phenocrysts differ in size and abundance, similar quartz + K-feldspar + plagioclase + biotite mineralogy, whole-rock geochemistry, and analytically indistinguishable ages indicate that the tuff and porphyry were comagmatic. Resorption of phenocrysts in tuff and porphyry suggests that these magmas formed by thermal rejuvenation of near-solidus or solidified crystal mush. A rare magmatic enclave (54% SiO2, arc geochemical signature) in the porphyry may be similar to parental magma and provides evidence of mafic magma and thermal input.

  10. Numerical models for ground deformation and gravity changes during volcanic unrest: simulating the hydrothermal system dynamics of an active caldera

    OpenAIRE

    Coco, A.; Gottsmann, J.; F. Whitaker; Rust, A; G. Currenti; A. Jasim; S. Bunney

    2015-01-01

    Ground deformation and gravity changes in active calderas during periods of unrest can signal an impending eruption and thus must be correctly interpreted for hazard evaluation. It is critical to differentiate variation of geophysical observables related to volume and pressure changes induced by magma migration from shallow hydrothermal activity associated with hot fluids of magmatic origin rising from depth. In this paper we present a nu...

  11. Evidence fromcosmic ray exposure (CRE) dating for the existence of a pre-Minoan caldera on Santorini, Greece

    OpenAIRE

    Athanassas, C. D.; Bourles, D.L.; Braucher, R.; Druitt, T. H.; Nomikou, P.; Leanni, Laetitia

    2016-01-01

    Cosmic ray exposure (CRE) datingwas performed on the caldera cliffs of Santorini with the aim of detecting cliff segments predating the Minoan eruption (17th century BCE). The methodology involved the determination of in situ-produced cosmogenic Cl-36 concentration in basaltic-torhyodacitic whole rocks cropping out in the cliffs. After the samples were processed following the chemical protocol of Cl-36 preparation for silicate rocks, Cl-36 concentrations were measured by accelerator mass spec...

  12. Juan Puma, el hijo del oso. Cuento quechua de La Jalca, Chachapoyas

    Directory of Open Access Journals (Sweden)

    1997-01-01

    Full Text Available JUAN PUMA, LE FILS DE L'OURS . CONTE QUECHUA DE LA JALCA, CHACHAPOYAS. Une des fêtes les plus importantes de la communauté de La Jalca, Province de Chachapoyas, Amazonas, est celle de la Saint-Pierre où l’on exécute une danse de l’ours très semblable à celle des ukukus du sud péruvien. Le narrateur du récit que nous publions ici assimile ce rite à l’histoire de Juan Oso (Jean de l’Ours très connue dans le monde andin. L’importance de l’ours dans cette culture des hautes terres amazoniennes est fondamentale. En quechua local, l’ours s’appelle “puma” et partage avec le puma de la forêt les caractéristiques de puissance effrayante et de pouvoirs surnaturels. Le fils de l’ours, Juan, évoque les relations ambiguës liant les “chrétiens” des hautes terres d’Amazonas et les “sauvages” de la forêt. Una de las fiestas más importantes de la comunidad de La Jalca, Provincia de Chachapoyas, Amazonas, es la de San Pedro en la que se representa un baile del oso muy semejante al baile de los ukukus del sur peruano. El narrador del cuento que publicamos aquí asimila este rito a la historia de Juan Oso, muy conocido en el mundo andino. La importancia del oso en esta cultura de la ceja de selva alta es fundamental. En quechua local, el oso se llama “puma” y comparte con el puma de la selva las características de fuerza temible y poderes sobrenaturales. El hijo del oso, Juan, evoca las relaciones ambiguas existentes entre los “cristianos” de la serranía de Amazonas y los “chunchos” de la selva. JUAN PUMA, THE BEAR'S SON. A QUECHUA TALE FROM LA JALCA, CHACHAPOYAS. One of the most important feasts of the community of La Jalca, Province of Amazonas, is that of Saint Peter in which a bear dance similar to the southern Peruvian dance of the ukukus is performed. In the story published here, the narrator assimilates this rite with the tale of Juan Oso, another story which is well known throughout the Andes. The importance of bears

  13. ["Is it an animal inside? "Melanie Klein's unpublished Don Juan Paper (1939)].

    Science.gov (United States)

    Frank, Claudia

    2008-01-01

    Klein had been asked to contribute an article to the birthday number of the International Journal for Jones. The author outlines how she hurriedly wrote a text about Don Juan which, however, was rejected by the editor. Essential parts of it are presented in German translation. The manuscript is discussed in the context of Klein's published work as well as of the relevant contemporary literature. In Klein's view, Don Juan's genitality is determined by oral impulses and fears. By his manic acting out he attempts to ward off a depressive break-down. The paper ends with some reflections about why Klein--ontrary to her intention--failed to revise her manuscript for later publication.

  14. An unpublished Roman inscription from Cortinal de San Juan (Salvatierra de Tormes, Salamanca

    Directory of Open Access Journals (Sweden)

    Verónica PÉREZ DE DIOS

    2015-11-01

    Full Text Available In this paper is presented a slate with a Roman inscription found in archaeological survey work conducted in September 2014 in Cortinal de San Juan (Salvatierra de Tormes. This site has been, since its discovery and cataloging, a place of reference for the late Roman and Visigothic settlement Southeast Salamanca. Currently, this archaeological site is partially flooded by the Santa Teresa swamp. The main feature of this Roman inscription is that the slate support isn’t usual in the chronology proposed for such inscription. Despite the fact that other archaeological materials of Cortinal de San Juan are associated with late Roman or Visigothic chronocultural context, the type of capital letter, the large size of the letter, and the parallels established with other finds of similar chronology suggest this inscription could be part of a Roman anthroponym as the most successful interpretive hypothesis.

  15. Juan Ramón Jiménez y el mercado editorial

    OpenAIRE

    Sánchez García, Raquel

    2003-01-01

    Este trabajo pretende analizar las vinculaciones de Juan Ramón Jiménez con el mundo de la edición. El objetivo es ver el camino que siguió para dar a conocer sus versos: con qué empresas editoriales contrató la publicación de sus libros, cómo logró los medios para llevarlo a cabo y de qué canales se sirvió para distribuirlos. Se trata de analizar un fenómeno muy frecuente entre los autores del primer tercio del siglo XX: la autoedición. También se abordará la participación de Juan Ramón en al...

  16. Investigating the activity of the Campi Flegrei caldera (Italy) through remote and in situ sensors (Invited)

    Science.gov (United States)

    Trasatti, E.; Polcari, M.; Bignami, C.; Bonafede, M.; Buongiorno, F.; Stramondo, S.

    2013-12-01

    Campi Flegrei is a nested caldera in Italy, whose structure includes submerged and continental parts at the western edge of the Bay of Naples. Together with Vesuvius and Etna, it is one of the Italian GeoHazard Supersites. The last eruption took place in 1538 A.D. and since then intense degassing, seismic swarms and several episodes of ground uplift have been observed. The area is characterized by one of the highest volcanic hazard in the world, due to the very high density of inhabitants. A major unrest episode took place in 1982-84, when the town of Pozzuoli, located at the caldera center, was uplifted by 1.80 m (~1 m/yr). During the following decades the area has been generally subsiding but minor uplift episodes of the order of few cm, seismic swarms and degassing episodes took place in 1989, 2000-01 and 2004-06, showing that the caldera is in a critical state on the verge of instability. Since March 1970 leveling surveys were regularly carried out to monitor the elevation changes. In the following decades many efforts have been done to monitor the different aspects of the activity of the area, and nowadays Campi Flegrei is subjected to intense geodetic, geophysical and geochemical monitoring. In the last 30 years a number of geophysical investigations has provided important constraints to the description of the subsurface structure and the historical volcanic activity. Surface deformation, microgravity changes and geochemical anomalies at Campi Flegrei have been interpreted either in terms of instabilities of the hydrothermal system or variations in the magmatic source. In particular, discerning between magmatic vs hydrothermal origin of the source responsible of the large uplift episode during 1982-84 (most probably due to deep magmatic source) and of the mini-uplifts (e.g. 2000 and 2004-06, most probably due to pressure variations in the shallow aquifer) may have important implications in terms of civil protection. In the last two decades, the precise and

  17. Cluster forcing

    DEFF Research Database (Denmark)

    Christensen, Thomas Budde

    The cluster theory attributed to Michael Porter has significantly influenced industrial policies in countries across Europe and North America since the beginning of the 1990s. Institutions such as the EU, OECD and the World Bank and governments in countries such as the UK, France, The Netherlands...

  18. Evidence from cosmic ray exposure (CRE) dating for the existence of a pre-Minoan caldera on Santorini, Greece

    Science.gov (United States)

    Athanassas, C. D.; Bourlès, D. L.; Braucher, R.; Druitt, T. H.; Nomikou, P.; Léanni, L.

    2016-05-01

    Cosmic ray exposure (CRE) dating was performed on the caldera cliffs of Santorini with the aim of detecting cliff segments predating the Minoan eruption (17th century BCE). The methodology involved the determination of in situ-produced cosmogenic 36Cl concentration in basaltic-to-rhyodacitic whole rocks cropping out in the cliffs. After the samples were processed following the chemical protocol of 36Cl preparation for silicate rocks, 36Cl concentrations were measured by accelerator mass spectrometry (AMS). Important challenges during the implementation procedure were related to large amounts of radiogenic 36Cl, complex modeling of inherited 36Cl, and dominance of the thermal and epithermal (low-energy) neutron capture production pathway. Nevertheless, quantitative assessments on the basis of the contribution of the low-energy neutron capture pathway percent to the total production rate validated the calculated CRE dates. Current CRE ages demonstrate that an ancient caldera existed on pre-Minoan Santorini, occupying at least the northern half of the modern-day caldera.

  19. A three-dimensional QP imaging of the shallowest subsurface of Campi Flegrei offshore caldera, southern Italy

    Science.gov (United States)

    Serlenga, Vincenzo; Lorenzo, Salvatore; Russo, Guido; Amoroso, Ortensia; Garambois, Stephane; Virieux, Jean; Zollo, Aldo

    2016-11-01

    To improve the knowledge of the shallowest subsurface of Campi Flegrei caldera, a 3-D P wave attenuation tomography of the area was performed. We analyzed about 18,000 active seismic traces, which provided a data set of 11,873 Δt* measurements, e.g., the differential travel times to quality factor ratios. These were inverted through an adapted tomographic inversion procedure. The 3-D tomographic images reveal an average QP about 70, interpreted as water-saturated volcanic and marine sediments. An arc-like, low-QP structure at 0.5-1 km depths was interpreted as a densely fractured, fluid-saturated rock volume, well matching the buried rim of Campi Flegrei caldera. The spatial distribution of high- and low-QP bodies in the inner caldera is correlated with low-Vp values and may reflect either the differences in the percentage of fluid saturation of sediments or the presence of vapor state fluids beneath fumarole manifestations.

  20. Evidence for water influx from a caldera lake during the explosive hydromagmatic eruption of 1790, Kilauea volcano, Hawaii

    Science.gov (United States)

    Mastin, L.G.

    1997-01-01

    In 1790 a major hydromagmatic eruption at the summit of Kilauea volcano, Hawaii, deposited up to 10 m of pyroclastic fall and surge deposits and killed several dozen Hawaiian natives who were crossing the island. Previous studies have hypothesized that the explosivity of this eruption was due to the influx of groundwater into the conduit and mixing of the groundwater with ascending magma. This study proposes that surface water, not groundwater, was the agent responsible for the explosiveness of the eruption. That is, a lake or pond may have existed in the caldera in 1790 and explosions may have taken place when magma ascended into the lake from below. That assertion is based on two lines of evidence: (1) high vesicularity (averaging 73% of more than 3000 lapilli) and high vesicle number density (105-107 cm-3 melt) of pumice clasts suggest that some phases of the eruption involved vigorous, sustained magma ascent; and (2) numerical calculations suggest that under most circumstances, hydrostatic pressure would not be sufficient to drive water into the eruptive conduit during vigorous magma ascent unless the water table were above the ground surface. These results are supported by historical data on the rate of infilling of the caldera floor during the early 1800s. When extrapolated back to 1790, they suggest that the caldera floor was below the water table.