Science.gov

Sample records for active lava domes

  1. Lava flows and domes

    SciTech Connect

    Fink, J. )

    1989-01-01

    This book discusses emplacement of silicic domes and mafic lava flows. The authors have utilized the combination of field, experimental and theoretical methods to constrain various characteristics of recently-emplaced lavas, including dimensions, growth rates, surface morphology, deformation styles, rheology, and volatile contents. Filed measurements from numerous volcanoes are presented. Focus is on data from Mount St. Helens. The value of such investigations is addressed.

  2. What factors control superficial lava dome explosivity?

    PubMed Central

    Boudon, Georges; Balcone-Boissard, Hélène; Villemant, Benoît; Morgan, Daniel J.

    2015-01-01

    Dome-forming eruption is a frequent eruptive style and a major hazard on numerous volcanoes worldwide. Lava domes are built by slow extrusion of degassed, viscous magma and may be destroyed by gravitational collapse or explosion. The triggering of lava dome explosions is poorly understood: here we propose a new model of superficial lava-dome explosivity based upon a textural and geochemical study (vesicularity, microcrystallinity, cristobalite distribution, residual water contents, crystal transit times) of clasts produced by key eruptions. Superficial explosion of a growing lava dome may be promoted through porosity reduction caused by both vesicle flattening due to gas escape and syn-eruptive cristobalite precipitation. Both processes generate an impermeable and rigid carapace allowing overpressurisation of the inner parts of the lava dome by the rapid input of vesiculated magma batches. The relative thickness of the cristobalite-rich carapace is an inverse function of the external lava dome surface area. Explosive activity is thus more likely to occur at the onset of lava dome extrusion, in agreement with observations, as the likelihood of superficial lava dome explosions depends inversely on lava dome volume. This new result is of interest for the whole volcanological community and for risk management. PMID:26420069

  3. What factors control superficial lava dome explosivity?

    NASA Astrophysics Data System (ADS)

    Boudon, Georges; Balcone-Boissard, Hélène; Villemant, Benoît; Morgan, Daniel J.

    2015-09-01

    Dome-forming eruption is a frequent eruptive style and a major hazard on numerous volcanoes worldwide. Lava domes are built by slow extrusion of degassed, viscous magma and may be destroyed by gravitational collapse or explosion. The triggering of lava dome explosions is poorly understood: here we propose a new model of superficial lava-dome explosivity based upon a textural and geochemical study (vesicularity, microcrystallinity, cristobalite distribution, residual water contents, crystal transit times) of clasts produced by key eruptions. Superficial explosion of a growing lava dome may be promoted through porosity reduction caused by both vesicle flattening due to gas escape and syn-eruptive cristobalite precipitation. Both processes generate an impermeable and rigid carapace allowing overpressurisation of the inner parts of the lava dome by the rapid input of vesiculated magma batches. The relative thickness of the cristobalite-rich carapace is an inverse function of the external lava dome surface area. Explosive activity is thus more likely to occur at the onset of lava dome extrusion, in agreement with observations, as the likelihood of superficial lava dome explosions depends inversely on lava dome volume. This new result is of interest for the whole volcanological community and for risk management.

  4. What factors control the superficial lava dome explosivity?

    NASA Astrophysics Data System (ADS)

    Boudon, Georges; Balcone-Boissard, Hélène; Villemant, Benoit; Morgan, Daniel J.

    2015-04-01

    Dome-forming eruption is a frequent eruptive style; lava domes result from intermittent, slow extrusion of viscous lava. Most dome-forming eruptions produce highly microcrystallized and highly- to almost totally-degassed magmas which have a low explosive potential. During lava dome growth, recurrent collapses of unstable parts are the main destructive process of the lava dome, generating concentrated pyroclastic density currents (C-PDC) channelized in valleys. These C-PDC have a high, but localized, damage potential that largely depends on the collapsed volume. Sometimes, a dilute ash cloud surge develops at the top of the concentrated flow with an increased destructive effect because it may overflow ridges and affect larger areas. In some cases, large lava dome collapses can induce a depressurization of the magma within the conduit, leading to vulcanian explosions. By contrast, violent, laterally directed, explosions may occur at the base of a growing lava dome: this activity generates dilute and turbulent, highly-destructive, pyroclastic density currents (D-PDC), with a high velocity and propagation poorly dependent on the topography. Numerous studies on lava dome behaviors exist, but the triggering of lava dome explosions is poorly understood. Here, seven dome-forming eruptions are investigated: in the Lesser Antilles arc: Montagne Pelée, Martinique (1902-1905, 1929-1932 and 650 y. BP eruptions), Soufrière Hills, Montserrat; in Guatemala, Santiaguito (1929 eruption); in La Chaîne des Puys, France (Puy de Dome and Puy Chopine eruptions). We propose a new model of superficial lava-dome explosivity based upon a textural and geochemical study (vesicularity, microcrystallinity, cristobalite distribution, residual water contents, crystal transit times) of clasts produced by these key eruptions. Superficial explosion of a growing lava dome may be promoted through porosity reduction caused by both vesicle flattening due to gas escape and syn-eruptive cristobalite

  5. Phenocryst fragments in rhyolitic lavas and lava domes

    NASA Astrophysics Data System (ADS)

    Allen, S. R.; McPhie, J.

    2003-08-01

    Although rhyolitic lavas and lava domes are characterised by evenly porphyritic textures, not all the phenocrysts are whole euhedra. We undertook image analysis of 46 rhyolitic lava and lava dome samples to determine the abundance and shape of quartz and feldspar phenocryst fragments. Phenocryst fragments were identified in nearly all samples. On average, fragments amount to ˜5% of the total phenocryst population, or ˜0.5 modal%. The abundance of fragments in lavas and lava domes is not related to the groundmass texture (whether vesicular, flow banded, massive, glassy or crystalline), nor to distance from source. Fragments are, however, more abundant in samples with higher phenocryst contents. The phenocryst fragments in rhyolitic lavas and lava domes are mainly medium to large (0.5-3.5 mm), almost euhedral crystals with only a small portion removed, or chunky, equant, subhedral fragments, and occur in near-jigsaw-fit or clast-rotated pairs or groups. The fragments probably formed in response to decompression of large melt inclusions. Shear during laminar flow then dismembered the phenocrysts; continued laminar shear separated and rotated the fragments. Fractures probably formed preferentially along weaknesses in the phenocrysts, such as zones of melt inclusions, cleavage planes and twin composition planes. Rare splintery fragments are also present, especially within devitrified domains. Splinters are attributed to comminution of solid lava adjacent to fractures that were later healed. For comparison, we measured crystal abundance in a further 12 rhyolite samples that include block and ash flow deposits and ignimbrite. Phenocryst fragments within clasts in the block and ash flow samples showed similar shapes and abundances to those fragments within the lava and lava domes. Crystal fragments are much more abundant in ignimbrite (exceeding 67% of the crystal population) however, and dominated by small, equant, anhedral chunks or splinters. The larger crystals in

  6. Experimental Studies of Lava Dome Fracture

    NASA Astrophysics Data System (ADS)

    Smith, R.; Sammonds, P. R.; Kilburn, C. R.

    2005-12-01

    Renewed extrusion at andesitic to dacitic lava domes and collapses of these domes are usually preceded by fracturing and frictional sliding of material in and around the lava dome and magma conduit. This is observed through the occurrence of shallow high frequency earthquakes. Samples of andesite from Mount Shasta in the Cascades, a typical material for both lava domes and shallow underlying country rock, have been deformed in compression and tension, at temperatures of up to 900°C, and under confining pressures of up to 70MPa. During these tests the axial load, sample deformation and acoustic emissions were recorded, in order to compare the results with field observations of deformation and short period seismicity at lava domes. Typical strengths at room temperature and pressure were 6MPa in tension, and 100MPa in compression. Increased temperatures increased the tensile strength, but reduced the compressive strength, whereas both strengths increased with increasing confining pressure. There were ~10 times more acoustic emissions at room temperature than at maximum test temperatures, indicating that increased temperatures favour ductile, rather than brittle, failure. These results suggest that young, hot lava domes may collapse or erupt with little precursory short period seismicity, whilst older, cooler domes are likely to exhibit stronger short period seismic precursors. However, hotter material is likely to exhibit more recognisable deformation precursors. This is consistent with the seismicity observed after the 18 May 1980 climactic eruption at Mount St Helens, where there was ~100 times more seismicity prior to eruptions in 1985 and 1986 than there was prior to eruptions in 1980 and 1981. During these later eruptions, the interior of the dome would still have been ductile due to its temperature and the overburden weight acting as a confining pressure, but the large amount of pre-failure deformation in this zone could drive fracturing of the cooler outer

  7. The longevity of lava dome eruptions

    NASA Astrophysics Data System (ADS)

    Wolpert, Robert L.; Ogburn, Sarah E.; Calder, Eliza S.

    2016-02-01

    Understanding the duration of past, ongoing, and future volcanic eruptions is an important scientific goal and a key societal need. We present a new methodology for forecasting the duration of ongoing and future lava dome eruptions based on a database (DomeHaz) recently compiled by the authors. The database includes duration and composition for 177 such eruptions, with "eruption" defined as the period encompassing individual episodes of dome growth along with associated quiescent periods during which extrusion pauses but unrest continues. In a key finding, we show that probability distributions for dome eruption durations are both heavy tailed and composition dependent. We construct objective Bayesian statistical models featuring heavy-tailed Generalized Pareto distributions with composition-specific parameters to make forecasts about the durations of new and ongoing eruptions that depend on both eruption duration to date and composition. Our Bayesian predictive distributions reflect both uncertainty about model parameter values (epistemic uncertainty) and the natural variability of the geologic processes (aleatoric uncertainty). The results are illustrated by presenting likely trajectories for 14 dome-building eruptions ongoing in 2015. Full representation of the uncertainty is presented for two key eruptions, Soufriére Hills Volcano in Montserrat (10-139 years, median 35 years) and Sinabung, Indonesia (1-17 years, median 4 years). Uncertainties are high but, importantly, quantifiable. This work provides for the first time a quantitative and transferable method and rationale on which to base long-term planning decisions for lava dome-forming volcanoes, with wide potential use and transferability to forecasts of other types of eruptions and other adverse events across the geohazard spectrum.

  8. Lava dome morphometry and geochronology of the youngest eruptive activity in Eastern Central Europe: Ciomadul (Csomád), East Carpathians, Romania

    NASA Astrophysics Data System (ADS)

    Karátson, D.; Telbisz, T.; Harangi, Sz.; Magyari, E.; Kiss, B.; Dunkl, I.; Veres, D.; Braun, M.

    2012-04-01

    Volcanic evolution of the Ciomadul (Csomád) lava dome complex, site of the youngest (Late Pleistocene, late Marine Isotope Stage 3) eruptive activity in the Carpathians, has been studied by advanced morphometry and radiometric (U/Pb, U/He and 14C) geochronology. The volcano produced alternating effusive and intermittent explosive eruptions from individual domes, typical of common andesitic-dacitic lava domes. A comparative morphometry shows steep ≥30° mean slopes of domes' upper flank and the Csomád domes fit well to the 100-200 ka domes worldwide. Morphometric ages obtained from the mean slope vs age precipitation correlation results in ≤100 ka ages. The morphometric approach is supported by U/Pb and U/He chronology: preliminary results of zircon dating indicate ages ranging between 200(250) and 30 ka. The youngest ages of the data set obtained both from lavas and pumiceous pyroclastics argue for a more or less coeval effusive and explosive volcanism. Based also on volcanological data, we propose vulcanian eruptions and explosive dome collapses especially toward the end of volcanic activity. Moreover, radiometric chronology suggests that, possibly subsequently to the peripheral domes, a central lava dome complex built up ≤100 ka ago. This dome complex, exhibiting even more violent, up to sub-plinian explosions, emplaced pumiceous pyroclastic flow and fall deposits as far as 17 km. We propose that the explosive activity produced caldera-forming eruptions as well, creating a half-caldera. This caldera rim is manifested by the asymmetric morphology of the central edifice: the present-day elevated ridge of Ciomadul Mare (Nagy Csomád), encompassing the twin craters of Mohoş (Mohos) peat bog and Sf. Ana (Szent [St.] Anna). These latter craters may have been formed subsequently, ca. ~100-30 ka ago, after the caldera formation. Drilling of lacustrine sediments in the St. Anna crater shows that beneath the Holocene gyttja several meters of Late Pleistocene

  9. Emplacement of the final lava dome of the 2009 eruption of Redoubt Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Bull, Katharine F.; Anderson, Steven W.; Diefenbach, Angela K.; Wessels, Rick L.; Henton, Sarah M.

    2013-06-01

    After more than 8 months of precursory activity and over 20 explosions in 12 days, Redoubt Volcano, Alaska began to extrude the fourth and final lava dome of the 2009 eruption on April 4. By July 1 the dome had filled the pre-2009 summit crater and ceased to grow. By means of analysis and annotations of time-lapse webcam imagery, oblique-image photogrammetry techniques and capture and analysis of forward-looking infrared (FLIR) images, we tracked the volume, textural, effusive-style and temperature changes in near-real time over the entire growth period of the dome. The first month of growth (April 4-May 4) produced blocky intermediate- to high-silica andesite lava (59-62.3 wt.% SiO2) that initially formed a round dome, expanding by endogenous growth, breaking the surface crust in radial fractures and annealing them with warmer, fresh lava. On or around May 1, more finely fragmented and scoriaceous andesite lava (59.8-62.2 wt.% SiO2) began to appear at the top of the dome coincident with increased seismicity and gas emissions. The more scoriaceous lava spread radially over the dome surface, while the dome continued to expand from endogenous growth and blocky lava was exposed on the margins and south side of the dome. By mid-June the upper scoriaceous lava had covered 36% of the dome surface area. Vesicularity of the upper scoriaceous lava range from 55 to 66%, some of the highest vesicularity measurements recorded from a lava dome. We suggest that the stability of the final lava dome primarily resulted from sufficient fracturing and clearing of the conduit by preceding explosions that allowed efficient degassing of the magma during effusion. The dome was thus able to grow until it was large enough to exceed the magmastatic pressure in the chamber, effectively shutting off the eruption.

  10. Using structure-from-motion for monitoring active lava flows and domes

    NASA Astrophysics Data System (ADS)

    James, Mike R.; Robson, Stuart; Varley, Nick

    2016-04-01

    3-D reconstruction software based on structure-from-motion (SfM) algorithms can substantially reduce the requirements and learning curve for generating topographic data from photographs, and thus offers strong potential for data collection in many dynamic environments. Unfortunately, SfM-based software tends not to provide the rigorous metrics that are used to assess the quality of results in conventional photogrammetry software. Here, we use examples of repeat oblique airborne acquisitions from a volcanic dome (Volcán de Colima, Mexico) and terrestrial time-lapse stereo-photography (Mt. Etna, Sicily) to examine the sensitivity of results to imaging characteristics and SfM processing procedures. At Volcán de Colima, photographs were acquired with a relatively favourable convergent geometry, from an opened window in a light aircraft. However, hazards prevent the deployment of ground control, so the derived topographic shape relies entirely on the image tie points generated automatically by the software. In contrast, at Mt. Etna, control targets could be used but, with only two (mildly convergent) cameras, the image geometry is naturally weaker that at Colima. We use both of these cases to explore some of the challenges involved with understanding the error inherent in projects processed using SfM-based approaches. Results are compared with those achieved using a rigorous close-range photogrammetry package.

  11. Small domes on Venus - Probable analogs of Icelandic lava shields

    NASA Technical Reports Server (NTRS)

    Garvin, James B.; Williams, Richard S., Jr.

    1990-01-01

    On the basis of observed shapes and volumetric estimates, small, dome-like features on radar images of Venus are interpreted to be analogs of Icelandic lava-shield volcanoes. Morphometric data for Venusian domes in Aubele and Slyuta as well as measurements of representative dome volumes and areas from Tethus Regio are used to demonstrate that the characteristic aspect ratios and flank slopes of these features are consistent with a subclass of low Icelandic lava-shield volcanoes (LILS).

  12. The longevity of lava dome eruptions: analysis of the global DomeHaz database

    NASA Astrophysics Data System (ADS)

    Ogburn, S. E.; Wolpert, R.; Calder, E.; Pallister, J. S.; Wright, H. M. N.

    2015-12-01

    The likely duration of ongoing volcanic eruptions is a topic of great interest to volcanologists, volcano observatories, and communities near volcanoes. Lava dome forming eruptions can last from days to centuries, and can produce violent, difficult-to-forecast activity including vulcanian to plinian explosions and pyroclastic density currents. Periods of active dome extrusion are often interspersed with periods of relative quiescence, during which extrusion may slow or pause altogether, but persistent volcanic unrest continues. This contribution focuses on the durations of these longer-term unrest phases, hereafter eruptions, that include periods of both lava extrusion and quiescence. A new database of lava dome eruptions, DomeHaz, provides characteristics of 228 eruptions at 127 volcanoes; for which 177 have duration information. We find that while 78% of dome-forming eruptions do not continue for more than 5 years, the remainder can be very long-lived. The probability distributions of eruption durations are shown to be heavy-tailed and vary by magma composition. For this reason, eruption durations are modeled with generalized Pareto distributions whose governing parameters depend on each volcano's composition and eruption duration to date. Bayesian predictive distributions and associated uncertainties are presented for the remaining duration of ongoing eruptions of specified composition and duration to date. Forecasts of such natural events will always have large uncertainties, but the ability to quantify such uncertainty is key to effective communication with stakeholders and to mitigation of hazards. Projections are made for the remaining eruption durations of ongoing eruptions, including those at Soufrière Hills Volcano, Montserrat and Sinabung, Indonesia. This work provides a quantitative, transferable method and rationale on which to base long-term planning decisions for dome forming volcanoes of different compositions, regardless of the quality of an

  13. Magma ascent dynamic through Ti diffusion in magnetites. Application to lava dome-forming eruptions. Implications to lava dome superifical explosivity.

    NASA Astrophysics Data System (ADS)

    Boudon, Georges; Balcone-Boissard, Hélène; Morgan, Dan J.

    2016-04-01

    Superficial lava dome explosivity represents a major hazard during lava dome growth. But the origin of this explosive activity remains unclear until recently. By using geochemical (residual water content, silica abundance) and textural (vesicularity, microcristallinity) data, we constrain the occurrence of such hazard to the beginning of the lava dome activity. During the first stages of growth, the lava dome is small enough to develop an impermeable carapace that isolates a less degassed batch of magma inside, thus allowing an internal overpressurization of the volcano (Boudon et al., 2015). This study more precisely details the petrology and the texture of titano-magnetites as archive of magma ascent dynamic within the conduit. Titano-magnetites may exhibit two types of textures: exsolved or "limpid". When they are exsolved, no time constrain may be extracted as they re-equilibrate. On the contrary, when they are unexsolved, major element distribution, in particular Ti, may act as a powerful tool to decipher magma dynamic (differentiation, mixing) and estimate time that corresponds to the magma ascent time. The composition and elemental diffusion profiles are acquired by EPMA, following textural investigations by SEM. The time is then obtained by modelling the profile as a diffusion profile using the intracristalline diffusion coefficients published in literature. We applied this methodology to examples of lava dome superficial explosivity on Montagne Pelée in Martinique (Lesser Antilles Arc), and on Puy Chopine volcano in La Chaine des Puys, (French Massif Central). More precisely, the first phase of the Puy Chopine lava dome growth experienced a superficial explosion, as for Montagne Pelée, the first stages of the 1902 eruption (several superficial explosions occurred) and the 650 y. BP eruption (two superficial explosions destroyed the growing lava dome). We show that, for a single event, the vesiculated, undegassed batch of magma responsible of the

  14. Small domes on Venus: probable analogs of Icelandic lava shields

    USGS Publications Warehouse

    Garvin, James B.; Williams, Richard S.

    1990-01-01

    On the basis of observed shapes and volumetric estimates, we interpret small, dome-like features on radar images of Venus to be analogs of Icelandic lava-shield volcanoes. Using morphometric data for venusian domes in Aubele and Slyuta (in press), as well as our own measurements of representative dome volumes and areas from Tethus Regio, we demonstrate that the characteristic aspect ratios and flank slopes of these features are consistent with a subclass of low Icelandic lava-shield volcanoes (LILS ). LILS are slightly convex in cross-section with typical flank slopes of ∼3°. Plausible lava-shield-production rates for the venusian plains suggest formation of ∼53 million shields over the past 0.25 Ga. The cumulative global volume of lava that would be associated with this predicted number of lava shields is only a factor of 3–4 times that of a single oceanic composite shield volcano such as Mauna Loa. The global volume of all venusian lava shields in the 0.5–20-km size range would only contribute a meter of resurfacing over geologically significant time scales. Thus, venusian analogs to LILS may represent the most abundant landform on the globally dominant plains of Venus, but would be insignificant with regard to the global volume of lava extruded. As in Iceland, associated lavas from fissure eruptions probably dominate plains volcanism and should be evident on the higher resolution Magellan radar images.

  15. Photogrammetric monitoring of lava dome growth during the 2009 eruption of Redoubt Volcano

    NASA Astrophysics Data System (ADS)

    Diefenbach, Angela K.; Bull, Katharine F.; Wessels, Rick L.; McGimsey, Robert G.

    2013-06-01

    The 2009 eruption of Redoubt Volcano, Alaska, began with a phreatic explosion on 15 March followed by a series of at least 19 explosive events and growth and destruction of at least two, and likely three, lava domes between 22 March and 4 April. On 4 April explosive activity gave way to continuous lava effusion within the summit crater. We present an analysis of post-4 April lava dome growth using an oblique photogrammetry approach that provides a safe, rapid, and accurate means of measuring dome growth. Photogrammetric analyses of oblique digital images acquired during helicopter observation flights and fixed-wing volcanic gas surveys produced a series of digital elevation models (DEMs) of the lava dome from 16 April to 23 September. The DEMs were used to calculate estimates of volume and time-averaged extrusion rates and to quantify morphological changes during dome growth. Effusion rates ranged from a maximum of 35 m3 s- 1 during the initial two weeks to a low of 2.2 m3 s- 1 in early summer 2009. The average effusion rate from April to July was 9.5 m3 s- 1. Early, rapid dome growth was characterized by extrusion of blocky lava that spread laterally within the summit crater. In mid-to-late April the volume of the dome had reached 36 × 106 m3, roughly half of the total volume, and dome growth within the summit crater began to be limited by confining crater walls to the south, east, and west. Once the dome reached the steep, north-sloping gorge that breaches the crater, growth decreased to the south, but the dome continued to inflate and extend northward down the gorge. Effusion slowed during 16 April-1 May, but in early May the rate increased again. This rate increase was accompanied by a transition to exogenous dome growth. From mid-May to July the effusion rate consistently declined. The decrease is consistent with observations of reduced seismicity, gas emission, and thermal anomalies, as well as declining rates of geodetic deflation or inflation. These trends

  16. Transition from Effusive to Explosive Activity during Lava Dome Eruption: The Example of the 2010 of Merapi Volcano (Java, Indonesia)

    NASA Astrophysics Data System (ADS)

    Drignon, M. J.; Arbaret, L.; Burgisser, A.; Komorowski, J. C.; Martel, C.; Putra, R.

    2014-12-01

    Understanding the transition between effusive and explosive activity in dome-forming volcanoes remains a challenging question for eruption forecasting and eruptive scenario definition. The explosive activity of 26 Oct. and 5 Nov. during the 2010 eruption of Merapi volcano offers the opportunity to explore this transition by quantifying the mechanisms that led to the dome explosion. Forty-three pumice samples were analyzed by 1) scanning electron microscope for textural analysis and 2) elemental analyzer for water content. The SEM images were processed so as to determine the proportions of gas bubbles, microlites and glass in each sample. These data were combined with the glass water content to feed the simple physical model developed by Burgisser et al. [1,2] to calculate pre-explosive pressure, depth, and porosity level for each pyroclastic pumice sample. Preliminary results indicate that the water content in the melt is high, reaching 7 wt.%. These water contents yield a wide range of pre-eruptive pressures. Samples from 26 Oct. originated at pressures from a few MPa to 280 MPa. These pressures correspond to depths ranging from a few hundred meters to more than 10 km. This suggests that large overpressures were associated with conduit evacuation that reached unexpected depths. Samples from the 5 Nov. event range from ~10 to ~100 MPa. This suggests that this event also evacuated a large part of the volcanic conduit. Pre-explosive porosities of both events are low (<10 vol. %) along the depth of the entire conduit, which suggests extensive permeable outgassing of the magma-filed conduit prior to each explosive evacuation. Ongoing work includes analysis of melt CO2 content due to preliminary evidence that it played an important role in the 2010 Merapi eruption. The modeled conduit properties serve as baseline data for conduit flow modeling and building plausible eruptive scenarios. [1] Burgisser et al. (2010) J. Volcanol. Geotherm. Res. 194, 27-41. [2] Burgisser et

  17. Hydrogen-isotope evidence for extrusion mechanisms of the Mount St Helens lava dome

    NASA Technical Reports Server (NTRS)

    Anderson, Steven W.; Fink, Jonathan H.

    1989-01-01

    Hydrogen isotope analyses were used to determine water content and deuterium content for 18 samples of the Mount St Helens dome dacite in an attempt to identify the triggering mechanisms for periodic dome-building eruptions of lava. These isotope data, the first ever collected from an active lava dome, suggest a steady-state process of magma evolution combining crystallization-induced volatile production in the chamber with three different degassing mechanisms: closed-system volatile loss in the magma chamber, open-system volatile release during ascent, and kinetically controlled degassing upon eruption at the surface. The data suggest the future dome-building eruptions may require a new influx of volatile-rich magma into the chamber.

  18. Key variables influencing patterns of lava dome growth and collapse

    NASA Astrophysics Data System (ADS)

    Husain, T.; Elsworth, D.; Voight, B.; Mattioli, G. S.; Jansma, P. E.

    2013-12-01

    Lava domes are conical structures that grow by the infusion of viscous silicic or intermediate composition magma from a central volcanic conduit. Dome growth can be characterized by repeated cycles of growth punctuated by collapse, as the structure becomes oversized for its composite strength. Within these cycles, deformation ranges from slow long term deformation to sudden deep-seated collapses. Collapses may range from small raveling failures to voluminous and fast-moving pyroclastic flows with rapid and long-downslope-reach from the edifice. Infusion rate and magma rheology together with crystallization temperature and volatile content govern the spatial distribution of strength in the structure. Solidification, driven by degassing-induced crystallization of magma leads to the formation of a continuously evolving frictional talus as a hard outer shell. This shell encapsulates the cohesion-dominated soft ductile core. Here we explore the mechanics of lava dome growth and failure using a two-dimensional particle-dynamics model. This meshless model follows the natural evolution of a brittle carapace formed by loss of volatiles and rheological stiffening and avoids difficulties of hour-glassing and mesh-entangelment typical in meshed models. We test the fidelity of the model against existing experimental and observational models of lava dome growth. The particle-dynamics model follows the natural development of dome growth and collapse which is infeasible using simple analytical models. The model provides insight into the triggers that lead to the transition in collapse mechasnism from shallow flank collapse to deep seated sector collapse. Increase in material stiffness due to decrease in infusion rate results in the transition of growth pattern from endogenous to exogenous. The material stiffness and strength are strongly controlled by the magma infusion rate. Increase in infusion rate decreases the time available for degassing induced crystallization leading to a

  19. Tensile strength of dome rocks and lavas at Santiaguito dome complex, Guatemala

    NASA Astrophysics Data System (ADS)

    Hornby, Adrian; Lamb, Oliver; Lamur, Anthony; Lavallée, Yan

    2015-04-01

    Lava domes are inherently unstable structures, subject to intense gas flux and rapid variations in the state of stress. At shallow depths confining stresses are minimal and deformation is dilatant, occurring predominantly through tensile fractures. This fracture mode facilitates outgassing and contributes to the development of gas-and-ash activity as well as vulcanian eruptions. However, there is a paucity of tensile strength data for volcanic materials in the published literature, and we know of no paper which addresses this at high temperatures. We study the tensile strength of dome rocks collected at the Santiaguito dome complex, Guatemala, over a porosity range of 3-25%. Indirect tensile (Brazilian) tests were conducted on 40-mm diameter cores, by imposing a compressive displacement rate (radial to the core) of 4 micron/s at room temperature as well as an eruptive temperature of ca. 850 °C. An acoustic monitoring system is employed to track the nucleation, propagation and coalescence of fractures leading to complete sample failure. We find that the rocks' tensile strength exhibits a nonlinear decrease with porosity. Preliminary tests at high temperature indicate that some rocks exhibit a higher tensile strength (than at room temperature); in these experiments, samples containing a higher fraction of interstitial melt revealed an additional component of viscous flow. Further experiments conducted at higher strain rates will define the brittle response of the liquid during tensile failure. The data is compared against similar datasets for volcanic rocks. We will discuss implications for shallow volcanic processes ranging from dilation bands and tuffisite formation to gas-and-ash explosions and dome structural stability.

  20. Computational modeling of lava domes using particle dynamics to investigate the effect of conduit flow mechanics on flow patterns

    NASA Astrophysics Data System (ADS)

    Husain, Taha Murtuza

    Large (1--4 x 106 m3) to major (> 4 x 106 m3) dome collapses for andesitic lava domes such as Soufriere Hills Volcano, Montserrat are observed for elevated magma discharge rates (6--13 m3/s). The gas rich magma pulses lead to pressure build up in the lava dome that result in structural failure of the over steepened canyon-like walls which may lead to rockfall or pyroclastic flow. This indicates that dome collapse intimately related to magma extrusion rate. Variation in magma extrusion rate for open-system magma chambers is observed to follow alternating periods of high and low activity. Periodic behavior of magma exhibits a rich diversity in the nature of its eruptive history due to variation in magma chamber size, total crystal content, linear crystal growth rate and magma replenishment rate. Distinguished patterns of growth were observed at different magma flow rates ranging from endogenous to exogenous dome growth for magma with varying strengths. Determining the key parameters that control the transition in flow pattern of the magma during its lava dome building eruption is the main focus. This dissertation examines the mechanical effects on the morphology of the evolving lava dome on the extrusion of magma from a central vent using a 2D particle dynamics model. The particle dynamics model is coupled with a conduit flow model that incorporates the kinetics of crystallization and rheological stiffening to investigate important mechanisms during lava dome building eruptions. Chapter I of this dissertation explores lava dome growth and failure mechanics using a two-dimensional particle-dynamics model. The model follows the evolution of fractured lava, with solidification driven by degassing induced crystallization of magma. The particle-dynamics model emulates the natural development of dome growth and rearrangement of the lava dome which is difficult in mesh-based analyses due to mesh entanglement effects. The deformable talus evolves naturally as a frictional

  1. An assessment of hydrothermal alteration in the Santiaguito lava dome complex, Guatemala: implications for dome collapse hazards

    USGS Publications Warehouse

    Ball, Jessica L.; Calder, Eliza S.; Hubbard, Bernard E.; Bernstein, Marc L.

    2013-01-01

    A combination of field mapping, geochemistry, and remote sensing methods has been employed to determine the extent of hydrothermal alteration and assess the potential for failure at the Santiaguito lava dome complex, Guatemala. The 90-year-old complex of four lava domes has only experienced relatively small and infrequent dome collapses in the past, which were associated with lava extrusion. However, existing evidence of an active hydrothermal system coupled with intense seasonal precipitation also presents ideal conditions for instability related to weakened clay-rich edifice rocks. Mapping of the Santiaguito dome complex identified structural features related to dome growth dynamics, potential areas of weakness related to erosion, and locations of fumarole fields. X-ray diffraction and backscattered electron images taken with scanning electron microscopy of dacite and ash samples collected from around fumaroles revealed only minor clay films, and little evidence of alteration. Mineral mapping using ASTER and Hyperion satellite images, however, suggest low-temperature (<150 °C) silicic alteration on erosional surfaces of the domes, but not the type of pervasive acid-sulfate alteration implicated in collapses of other altered edifices. To evaluate the possibility of internal alteration, we re-examined existing aqueous geochemical data from dome-fed hot springs. The data indicate significant water–rock interaction, but the Na–Mg–K geoindicator suggests only a short water residence time, and δ18O/δD ratios show only minor shifts from the meteoric water line with little precipitation of secondary (alteration) minerals. Based on available data, hydrothermal alteration on the dome complex appears to be restricted to surficial deposits of hydrous silica, but the study has highlighted, importantly, that the 1902 eruption crater headwall of Santa María does show more advanced argillic alteration. We also cannot rule out the possibility of advanced alteration

  2. Effects of lava-dome emplacement on the Mount St. Helens crater glacier

    NASA Astrophysics Data System (ADS)

    Walder, J. S.; Schilling, S. P.; Denlinger, R. P.; Vallance, J. W.

    2004-12-01

    Since the end of the 1981-1986 episode of lava-dome growth at Mount St. Helens, an unusual glacier has grown rapidly within the crater of the volcano. The glacier, which is fed primarily by avalanching from the crater walls, contains about 30% rock debris by volume, has a maximum thickness of about 220 m and a volume of about 120 million cubic m, and forms a crescent that wraps around the old lava dome on both east and west sides. The new (October 2004) lava dome in the south of the crater began to grow centered roughly on the contact between the old lava dome and the glacier, in the process uplifting both ice and old dome rock. As the new dome is spreading to the south, the adjacent glacier is bulging upward. Firn layers on the outer flank of the glacier bulge have been warped upward almost vertically. In contrast, ice adjacent to the new dome has been thoroughly fractured. The overall style of deformation is reminiscent of that associated with salt-dome intrusion. Drawing an analogy to sand-box experiments, we suggest that the glacier is being deformed by high-angle reverse faults propagating upward from depth. Comparison of Lidar images of the glacier from September 2003 and October 2004 reveals not only the volcanogenic bulge but also elevated domains associated with the passage of kinematic waves, which are caused by glacier-mass-balance perturbations and have nothing to do with volcanic activity. As of 25 October 2004, growth of the new lava dome has had negligible hydrological consequences. Ice-surface cauldrons are common consequences of intense melting caused by either subglacial eruptions (as in Iceland) or subglacial venting of hot gases (as presently taking place at Mount Spurr, Alaska). However, there has been a notable absence of ice-surface cauldrons in the Mount St. Helens crater glacier, aside from a short-lived pond formed where the 1 October eruption pierced the glacier. We suggest that heat transfer to the glacier base is inefficient because

  3. Blowing off steam: Tuffisite formation as a regulator for lava dome eruptions

    NASA Astrophysics Data System (ADS)

    Kendrick, Jackie; Lavallée, Yan; Varley, Nick; Wadsworth, Fabian; Lamb, Oliver; Vasseur, Jérémie

    2016-04-01

    Tuffisites are veins of variably sintered, pyroclastic particles that form in conduits and lava domes as a result of localized fragmentation events during gas-and-ash explosions. Those observed in-situ on the active 2012 lava dome of Volcán de Colima range from voids with intra-clasts showing little movement and interpreted to be failure-nuclei, to sub-parallel lenses of sintered granular aggregate interpreted as fragmentation horizons, through to infilled fractures with evidence of viscous remobilization. All tuffisites show evidence of sintering. Further examination of the complex fracture-and-channel patterns reveals viscous backfill by surrounding magma, suggesting that lava fragmentation was followed by stress relaxation and continued viscous deformation as the tuffisites formed. The natural tuffisites are more permeable than the host andesite, and have a wide range of porosity and permeability compared to a narrower window for the host rock, and gauging from their significant distribution across the dome, we posit that the tuffisite veins may act as important outgassing pathways. To investigate tuffisite formation we crushed and sieved andesite from the lava dome and sintered it at magmatic temperatures for different times. We then assessed the healing and sealing ability by measuring porosity and permeability, showing that sintering reduces both over time. During sintering the porosity-permeability reduction occurs due to the formation of viscous necks between adjacent grains, a process described by the neck-formation model of Frenkel (1945). This process leads the granular starting material to a porosity-permeability regime anticipated for effusive lavas, and which describes the natural host lava as well as the most impervious of natural tuffisites. This suggests that tuffisite formation at Volcán de Colima constructed a permeable network that enabled gas to bleed passively from the magma. We postulate that this progressively reduced the lava dome

  4. Alteration minerals on the Santiaguito lava dome complex, Santa María volcano, Guatemala

    NASA Astrophysics Data System (ADS)

    Ball, J. L.; Calder, E. S.; Giese, R.

    2010-12-01

    Santiaguito is a relatively young complex of four lava domes located at the foot of the Santa María volcano in Guatemala. The domes have been erupting intermittently since 1922, and have shown various degrees of hydrothermal activity throughout their development. Hydrothermal systems in older volcanic edifices (Casita in Nicaragua, La Soufriere of Guadeloupe) are known to weaken rock and promote collapses, but their effects and development in young lava domes is less well constrained. Santiaguito has experienced several relatively small dome collapses (≦ 3 million m3) in the past, but it is unclear what role hydrothermal processes have played in these collapses. Currently, low-temperature active fumaroles are present on the domes, indicating the presence of a hydrothermal system. Samples of unconsolidated ash and sediment and rock chips were collected from the interior of fumaroles on the El Brujo lava dome to determine if hydrothermal alteration minerals were present. X-ray diffraction (XRD) was used to identify the presence of clay minerals in the powdered samples. Additional semi-quantitative identification was obtained using backscattered electron images (BSE) collected with a scanning electron microscope (SEM). Both analyses were performed at the University at Buffalo. Preliminary XRD analyses were unable to conclusively detect alteration minerals in powdered samples; however, BSE images of the same samples appeared to show alteration minerals (montmorillonite, saponite) adhering to individual ash grains. Further SEM analyses are being conducted on thin sections of the rock chips to determine if alteration minerals are present in dome rock as well as in the unconsolidated material. Development of alteration minerals on the relatively young (~50-90 year old) Santiaguito lava domes may indicate an increased risk for alteration-driven instabilities and collapses. Altered volcanic rocks are less competent, have lower shear strength and are more susceptible to

  5. A new application of a finite element heat and mass transfer numerical modeling code (FEHM) to heat and fluid circulation in lava domes

    NASA Astrophysics Data System (ADS)

    Ball, J. L.; Stauffer, P. H.; Calder, E. S.

    2012-12-01

    Lava domes have been well-characterized in terms of their surface structure and activity, but there is much to be learned about their internal structure and geothermal systems. Even when a lava dome is no longer actively erupting, subsurface studies are often difficult to conduct; lava domes are highly complex structures, but their rugged nature often precludes systematic drilling and/or geophysical surveys. Because of this, we know little about the internal geothermal activity that may still contribute to both hazards and opportunities for exploitation of mineral deposits and hot groundwater. Despite the difficulty of studying the interior of lava domes directly, numerical modeling can still provide insights into the behavior of their geothermal systems. Lava domes have the potential to be highly transmissive structures, and the presence of hot springs in the vicinity of lava domes (Santiaguito in Guatemala, La Soufriere on Guadeloupe) suggests that water circulation may be an important process in post-eruptive dome evolution. FEHM, a heat and mass transfer modeling code developed at Los Alamos National Laboratory (fehm.lanl.gov) is an ideal tool to study fluid and gas circulation in geologic structures. FEHM was developed for subsurface reservoir modeling (originally for the Hot Dry Rock geothermal project) and is capable of dealing with both high- (magmatic) and low-temperature fluids. In this study, FEHM has been used in combination with a LANL-developed grid-generating utility (LaGriT) to create an idealized model of water circulation in a saturated lava dome. Multiple material regions are used to represent the dome core, outer talus layer, conduit, and volcanic substrate. Material properties (such as permeability, porosity, density, etc.) were chosen from a combination of literature review and sensitivity testing using a simplified dome geometry and a continuum modeling approach that accounts for fractures (Equivalent Porous Medium) was used when applying

  6. Laboratory Studies of High Temperature Deformation and Fracture of Lava Domes

    NASA Astrophysics Data System (ADS)

    Smith, R.; Sammonds, P.; Tuffen, H.; Meredith, P.

    2007-12-01

    The high temperature fracture mechanics of magma at high temperatures exerts a fundamental control on the stability of lava domes and the timing and style of eruptions at andesitic to dacitic volcanoes. This is evidenced in the pervasive fracturing seen in both ancient and active magma conduits and lava domes; in addition to the volcanic earthquakes that occur before and during episodes of dome growth and dome collapse. Uniaxial and triaxial deformation experiments have been performed on crystal rich and crystal free magmas (andesite from Ancestral Mount Shasta, California, USA and a rhyolitic obsidian from Krafla, Iceland) at a range of temperatures (up to 900°C), confining pressures (up to 50 MPa) and strain rates (10-5s-1) to 10-3s-1) whilst recording acoustic emissions (AE). Results from these experiments provide useful inputs into models of lava dome stability, extrusion mechanisms, and source mechanisms for volcanic earthquakes. However, the large sample sizes used to ensure valid results (25mm diameter and 75mm length) made it difficult to maintain stable high temperatures under confined conditions. Also, only rudimentary AE data could be obtained, due to the distance of the transducers from the samples to keep them away from the high temperatures. Here, we present modifications to this apparatus, which include a new furnace, improved loading system, additional pore pressure and permeability measurement capability, and vastly improved acoustic monitoring. This allows (1)stable higher temperatures (up to 1000°C) to be achieved under confined conditions, (2) high temperature and moderate pressure (up to 70 MPa) hydrostatic measurements of permeability and acoustic velocities, (3) high temperature triaxial deformation under different pore fluid and pressure conditions, and (4) full waveform AE monitoring for all deformation experiments. This system can thus be used to measure the physical properties and strength of rocks under volcanic conditions and to

  7. Venusian pancake domes: Insights from terrestrial voluminous silicic lavas and thermal modeling

    NASA Technical Reports Server (NTRS)

    Manley, Curtis R.

    1993-01-01

    The so-called 'pancake' domes, and several other volcanoes on Venus, appear to represent large extrusions of silicic lava. Similar voluminous rhyolite lava flows, often associated with mantle plumes, are known on Earth. Venus' high ambient temperature, and insulation by the dome's brecciated carapace, both act to prolong cooling of a dome's interior, allowing for episodic lava input over an extended period of time. Field relations and aspect ratios of terrestrial voluminous rhyolite lavas imply continuous, non-episodic growth, reflecting tapping of a large volume of dry, anatectic silicic magma. Petrogenetically, the venusian domes may be analogous to chains of small domes on Earth, which represent 'leakage' of evolved material from magma bodies fractionating from much more mafic liquids.

  8. Topaz rhyolites of Nathrop, Colorado: Lava domes or rheomorphic flows?

    NASA Astrophysics Data System (ADS)

    Hernandez, B. M.; Panter, K. S.; Van Der Voo, R.

    2013-12-01

    Deposits of topaz-bearing rhyolite at Ruby and Sugarloaf Mountains in central Colorado are considered to be remnants of lava domes. The deposits are part of the Late Eocene-Oligocene Central Colorado Volcanic Field [1] that lies along the eastern margin of the Arkansas Graben of the Rio Grande Rift. Topaz-bearing rhyolite lava domes and flows have been identified elsewhere in Colorado and the western U.S., but an assortment of geomorphological, lithostratigraphical, and textural features of Ruby and Sugarloaf Mountains call into question their strict classification as such. Alternatively, the lava flows may be interpreted as rheomorphic ignimbrites. The volcanic deposits encompass a sequence of steeply (~70°) west-dipping units that form two N-S elongated edifices ~0.5 km long and a few hundred meters high. Their common lithostratigraphy from bottom to top is tuff breccia, vitrophyre, and flow-banded rhyolite. The tuff breccia includes large (up to ~1 m) pumice blocks and lithics that vary from nearly absent to moderately abundant (10-20%). At Sugarloaf lithics include rare cobble-sized clasts of granite, but the majority consists of flow-banded rhyolite. The tuff breccia grades normally upward into the vitrophyre with increased welding and a eutaxitic fabric defined by fiamme with increasing aspect ratios. Lithics are abundant in the vitrophyre at Sugarloaf but are rare or absent in the vitrophyre at Ruby Mountain. The transition from the vitrophyre to the flow-banded rhyolite is abrupt (<1 m) at both locations, though the lower rhyolite is less competent. The flow-banded rhyolite at Sugarloaf is crystal-rich (up to 50%), containing plagioclase, sanidine, smoky quartz, and biotite, while at Ruby the rhyolite is relatively crystal poor (2-3%) and biotite is absent. Pumiceous zones and lithophysae occur within the rhyolite at both locations. Zones of auto-brecciation are often associated with convoluted flow banding, especially along a vertical contact with

  9. The 2006 lava dome eruption of Merapi Volcano (Indonesia): Detailed analysis using MODIS TIR

    NASA Astrophysics Data System (ADS)

    Carr, Brett B.; Clarke, Amanda B.; Vanderkluysen, Loÿc

    2016-02-01

    Merapi is one of Indonesia's most active and dangerous volcanoes. Prior to the 2010 VEI 4 eruption, activity at Merapi during the 20th century was characterized by the growth and collapse of a series of lava domes. Periods of very slow growth were punctuated by short episodes of increased eruption rates characterized by dome collapse-generated pyroclastic density currents (PDCs). An eruptive event of this type occurred in May-June, 2006. For effusive eruptions such as this, detailed extrusion rate records are important for understanding the processes driving the eruption and the hazards presented by the eruption. We use thermal infrared (TIR) images from the Moderate Resolution Imaging Spectrometer (MODIS) instrument on NASA's Aqua and Terra satellites to estimate extrusion rates at Merapi Volcano during the 2006 eruption using the method of Harris and Ripepe (2007). We compile a set of 75 nighttime MODIS images of the eruptive period to produce a detailed time series of thermal radiance and extrusion rate that reveal multiple phases of the 2006 eruption. These data closely correspond to the published ground-based observational record and improve observation density and detail during the eruption sequence. Furthermore, additional analysis of radiance values for thermal anomalies in Band 21 (λ = 3.959 μm) of MODIS images results in a new framework for detecting different styles of activity. We successfully discriminate among slow dome growth, rapid dome growth, and PDC-producing dome collapse. We also demonstrate a positive correlation between PDC frequency and extrusion rate, and provide evidence that extrusion rate can increase in response to external events such as dome collapses or tectonic earthquakes. This study represents a new method of documenting volcanic activity that can be applied to other similar volcanic systems.

  10. Electrical resistivity tomography applied to a complex lava dome: 2D and 3D models comparison

    NASA Astrophysics Data System (ADS)

    Portal, Angélie; Fargier, Yannick; Lénat, Jean-François; Labazuy, Philippe

    2015-04-01

    The study of volcanic domes growth (e.g. St. Helens, Unzen, Montserrat) shows that it is often characterized by a succession of extrusion phases, dome explosions and collapse events. Lava dome eruptive activity may last from days to decades. Therefore, their internal structure, at the end of the eruption, is complex and includes massive extrusions and lava lobes, talus and pyroclastic deposits as well as hydrothermal alteration. The electrical resistivity tomography (ERT) method, initially developed for environmental and engineering exploration, is now commonly used for volcano structure imaging. Because a large range of resistivity values is often observed in volcanic environments, the method is well suited to study the internal structure of volcanic edifices. We performed an ERT survey on an 11ka years old trachytic lava dome, the Puy de Dôme volcano (French Massif Central). The analysis of a recent high resolution DEM (LiDAR 0.5 m), as well as other geophysical data, strongly suggest that the Puy de Dôme is a composite dome. 11 ERT profiles have been carried out, both at the scale of the entire dome (base diameter of ~2 km and height of 400 m) on the one hand, and at a smaller scale on the summit part on the other hand. Each profile is composed of 64 electrodes. Three different electrode spacing have been used depending on the study area (35 m for the entire dome, 10 m and 5 m for its summit part). Some profiles were performed with half-length roll-along acquisitions, in order to keep a good trade-off between depth of investigation and resolution. Both Wenner-alpha and Wenner-Schlumberger protocols were used. 2-D models of the electrical resistivity distribution were computed using RES2DINV software. In order to constrain inversion models interpretation, the depth of investigation (DOI) method was applied to those results. It aims to compute a sensitivity index on inversion results, illustrating how the data influence the model and constraining models

  11. Lava Dome Growth at Volcan de Fuego MEXICO (Colima Volcano), October 2001 to May 2002

    NASA Astrophysics Data System (ADS)

    Suarez-Plascencia, C.; Nunez-Cornu, F. J.; Reyes-Davila, G. A.

    2002-12-01

    The Volcan de Fuego (19.512 N, 103.617 W) is located on the border between the States of Jalisco and Colima, Mexico, it is also known as Colima Volcano or Zapotl n Volcano, is a stratovolcano rising nearly 4000 m above sea level, and is the most active volcano in Mexico. Recent activity has been characterized by at least 3 different phases since January 1998 when seismic swarms began and ended with the extrusion of blocky lava in November 22, 1998 by the West vent as the 1991 eruptive process. That extrusive period lasted until the end of January, 1999 when was possible to observe a change in the seismic pattern, which mark the beginning of a new eruptive regime, an explosive one. On February 10, 1999 at approximately 0154 local time, 0754 gmt, an explosive event happens at the summit dome of Volc n de Fuego, four more big explosions took place at the summit the last one at dawn February 22, 2001. These explosions opened a new crater at the summit with a elliptical form with radius of 260 x 225 m and depth between 40 m and 15 m. A small dome structure inside the new crater was reported by March 2001. A reconnaissance flight in August 2001 shows two main features in the main crater an steep-sided mound(scoria cone) over the West vent and an inner crater on the NE vent. On October 31 Civil Defense members at Nevado Base on Nevado de Colima observed a neddle over the main crater rim, reconnaissance flight shows a spiny, 40 m high with a diameter of 20 m grows from the NE vent, the spiny seems to formed by material of the 1976 eruption. Continuous aerial observations allow us to follow the growth of a new dome pushing out the spiny. On November 23 the dimensions of the dome under the spiny were a radius of about 14 m and 21 m high for a total extrusion of 86,000 m3 which implies a extrusion rate of 0.027m3 /seg. By December the dome push out the spiny and began to grow from the NW vent. By December 29 an increase in the rate of extrusion was observed reaching a value

  12. Deformation, lava dome evolution, and eruption cyclicity at Merapi volcano, Indonesia

    NASA Astrophysics Data System (ADS)

    Young, Kirby D.

    Deformation monitoring results are reported here for the period 1988-1998 at Merapi volcano, one of the most active and dangerous volcanoes in Indonesia. Comprehensive databases of various geophysical parameters were concurrently studied and analyzed to 2000, and similar data were subsequently considered during periods of eruption crisis in 2001 and 2006. Of particular emphasis was the study of lava eruption rates based on dome volume estimates and seismic proxies for dome collapse volumes. The detailed study period of deformation includes a major resumption in lava effusion in January 1992 and major dome collapses in November 1994, January 1997, and July 1998. Monitoring techniques employed in the field are of two types. Translational movements were recorded via electronic distance measurements (EDM) on a summit trilateration network, slope distance changes measured to the upper flanks, and other data collected from 1988 to 1995. Tilt changes were detected by a summit and flank network of tilt stations that operated at various times from 1993 to 1998. A major consequence of the deformation results is the documentation of a significant 4-year period of deformation precursory to the 1992 eruption. Cross-crater strain rates accelerated from less than 3 x 10-6/day between 1988 and 1990 to more than 11 x 10-6/day just prior to the January 1992 activity, representing a general, asymmetric extension of the summit during highlevel conduit pressurization. After the vent opened and effusion of lava resumed, strain occurred at a much reduced rate of less than 2 x 10-6/day. The Gendol breach, a pronounced depression formed by the juxtaposition of old lava coulees on the southeast flank, functioned as a major displacement discontinuity. An elevated phase of magma production with respect to the long-term rate for the 20th Century characterized the activity at Merapi volcano, Central Java/Yogyakarta, Indonesia, for the period 1992-2006. Most large (0.2 - 3.4 x 106 m3) dome

  13. Impact of hydrothermal alteration on lava dome stability: a numerical modelling approach

    NASA Astrophysics Data System (ADS)

    Detienne, Marie; Delmelle, Pierre

    2016-04-01

    Lava domes are a common feature of many volcanoes worldwide. They represent a serious volcanic hazard as they are prone to repeated collapses, generating devastating debris avalanches and pyroclastic flows. While it has long been known that hydrothermal alteration degrades rock properties and weakens rock mass cohesion and strength, there is still little quantitative information allowing the description of this effect and its consequences for assessing the stability of a volcanic rock mass such as a lava dome. In this study, we use the finite difference numerical model FLAC 3D to investigate the impact of hydrothermal alteration on the stability of a volcanic dome lying on a flat surface. Different hydrothermal alteration distributions were tested to encompass the variability observed in natural lava domes. Rock shear strength parameters (minimum, maximum and mean cohesion "c" and friction angle "φ" values) representative of various degrees of hydrothermal rock alteration were used in the simulations. The model predicts that reduction of the basement rock's shear strength decreases the factor of safety significantly. A similar result is found by increasing the vertical and horizontal extension of hydrothermal alteration in the basement rocks. In addition, pervasive hydrothermal alteration within the lava dome is predicted to exert a strong negative influence on the factor of safety. Through reduction of rock porosity and permeability, hydrothermal alteration may also affect pore fluid pressure within a lava dome. The results of new FLAC 3D runs which simulate the effect of hydrothermal alteration-induced pore pressure changes on lava dome stability will be presented.

  14. Using Horizontal Cosmic Muons to Investigate the Density Distribution of the Popocatepetl Volcano Lava Dome

    NASA Astrophysics Data System (ADS)

    Grabski, V.; Lemus, V.; Nuñez-Cadena, R.; Aguilar, S.; Menchaca-Rocha, A.; Fucugauchi, J. U.

    2013-05-01

    Study of volcanic inner density distributions using cosmic muons is an innovative method, which is still in stage of development[1]. The method can be used to determine the average density along the muon track, as well as the density distribution of any volume by measuring the attenuation of cosmic muon flux in it[2]. In this study we present an analysis of using the muon radiography, integrating geophysical data to determine the density distribution of the Popocatepetl volcano. Popocatepelt is a large andesitic stratovolcano built in the Trans-Mexican volcanic arc, which has been active over the past years. The recent activity includes emplacement of a lava dome, with vulcanian explosions and frequent scoria and ash emissions. The study is directed to detect any variations in the dome and magmatic conduit system in some interval of time in the volume of Popocatepetl volcano lava dome. The study forms part of a long-term project of volcanic hazard monitoring that includes the Popocatepetl and Colima volcanoes[3]. The volcanoes are being studied by conventional geophysical techniques, including aerogeophysical surveys directed to determine the internal structure and characterize source characteristics and mechanism. The detector design mostly depends on the volume size to be investigated as well as the image-taking frequency to detect dynamic density variations. In this study we present a detector prototype design and suggestions on data taking, transferring and analyzing systems. We also present the approximate cost estimation of the suggested detector and discussion on a proposal about the creation of a national network for a volcanic alarm system. References [1] eg.H. Tanaka, et al., Nucl. Instr. and Meth. A 507 (2003) 657. [2] V. Grabski et al, NIM A 585 (2008) 128-135. [3] G. Conte, J. Urrutia-Fucugauchi, et al., International Geology Review, Vol. 46, 2004, p. 210-225.

  15. Effect of temperature on the permeability of lava dome rocks from the 2004-2008 eruption of Mount St. Helens

    NASA Astrophysics Data System (ADS)

    Gaunt, H. Elizabeth; Sammonds, Peter R.; Meredith, Philip G.; Chadderton, Amy

    2016-04-01

    As magma ascends to shallow levels in the volcanic conduit, volatile exsolution can produce a dramatic increase in the crystal content of the magma. During extrusion, low porosity, highly crystalline magmas are subjected to thermal stresses which generate permeable microfracture networks. How these networks evolve and respond to changing temperature has significant implications for gas escape and hence volcano explosivity. Here, we report the first laboratory experimental study on the effect of temperature on the permeability of lava dome rocks under environmental conditions designed to simulate the shallow volcanic conduit and lava dome. Samples were collected for this study from the 2004-2008 lava dome eruption of Mount St. Helens (Washington State, USA). We show that the evolution of microfracture networks, and their permeability, depends strongly on temperature changes. Our results show that permeability decreases by nearly four orders of magnitude as temperature increases from room temperature to 800 °C. Above 800 °C, the rock samples become effectively impermeable. Repeated cycles of heating leads to sample compaction and a reduction in fracture density and therefore a decrease in permeability. We argue that changes in eruption regimes from effusive to explosive activity can be explained by strongly decreasing permeability caused by repeated heating of magma, conduit walls and volcanic plugs or domes. Conversely, magma becomes more permeable as it cools, which will reduce explosivity.

  16. Volcano-tectonic control of Merapi's lava dome splitting observed from high resolution TerraSAR-X data

    NASA Astrophysics Data System (ADS)

    Luehr, Birger-G.; Walter, Thomas R.; Subandriyo, Joko; Sri Brotopuspito, Kirbani; Vasyura-Bathke, Hannes; Suryanto, Wiwit; Aisyah, Naning; Darmawan, Herlan; Nikkhoo, Mehdi; Richter, Nicole; Jousset, Philippe; Dahm, Torsten

    2015-04-01

    Volcanism at active andesite-dacite volcanoes is often associated with the formation and collapse of circular shaped protrusions of extruded, highly viscous lava, the so-called domes, which are emplaced in the near summit region. Growing domes may experience stable and instable structural phases, with a gradual transition in between. Dome collapse and the break-off of instable blocks of viscous lava may lead to pyroclastic flows, one of the most lethal hazards at stratovolcanoes. At Merapi volcano, Indonesia, nearly 50 % of all eruptions are accompanied by these phenomena. After the climactic eruption in 2010 which left an amphitheater in the summit region, a new dome started growing. Three years later, the dome reached a height of approximately 100 m and diameters of 220 and 190 m with a plateau-like surface area of 40,000m2 approximately. On 18/11/2013, an explosion occurred without identified precursors, leaving a major fracture cutting the complete dome structure. Based on high resolution TerraSAR-X satellite radar imagery, we could identify this linear fracture, traceable over ~200m in the long axis, and up to 40m width. After geocoding of the radar amplitude imagery, the fractures azimuthal trend could be compared to other structural lineaments, indicative of a significant NNW-SSE structural direction that has formed on Merapi volcano in the past. This alignment is also visible in a seismic velocity tomographic imagery for the upper crust, down to 15 km depth. The Merapi dome fractured in a NW-SE direction, and is consistent with the alignment of regional tectonic structures and of anticipated directions of pyroclastic flows. The fracture may be part of a larger volcano-tectonic system and may affect the dynamics and the stability of the Merapi dome.

  17. Instant snapshot of the internal structure of Unzen lava dome, Japan with airborne muography

    PubMed Central

    Tanaka, Hiroyuki K. M.

    2016-01-01

    An emerging elementary particle imaging technique called muography has increasingly been used to resolve the internal structures of volcanoes with a spatial resolution of less than 100 m. However, land-based muography requires several days at least to acquire satisfactory image contrast and thus, it has not been a practical tool to diagnose the erupting volcano in a real time manner. To address this issue, airborne muography was implemented for the first time, targeting Heisei-Shinzan lava dome of Unzen volcano, Japan. Obtained in 2.5 hours, the resultant image clearly showed the density contrast inside the dome, which is essential information to predict the magnitude of the dome collapse. Since airborne muography is not restricted by topographic conditions for apparatus placements, we anticipate that the technique is applicable to creating images of this type of lava dome evolution from various angles in real time. PMID:28008978

  18. Instant snapshot of the internal structure of Unzen lava dome, Japan with airborne muography

    NASA Astrophysics Data System (ADS)

    Tanaka, Hiroyuki K. M.

    2016-12-01

    An emerging elementary particle imaging technique called muography has increasingly been used to resolve the internal structures of volcanoes with a spatial resolution of less than 100 m. However, land-based muography requires several days at least to acquire satisfactory image contrast and thus, it has not been a practical tool to diagnose the erupting volcano in a real time manner. To address this issue, airborne muography was implemented for the first time, targeting Heisei-Shinzan lava dome of Unzen volcano, Japan. Obtained in 2.5 hours, the resultant image clearly showed the density contrast inside the dome, which is essential information to predict the magnitude of the dome collapse. Since airborne muography is not restricted by topographic conditions for apparatus placements, we anticipate that the technique is applicable to creating images of this type of lava dome evolution from various angles in real time.

  19. Volumes and eruption rates for the 2008-2009 Chaitén rhyolite lava dome

    NASA Astrophysics Data System (ADS)

    Pallister, J. S.; Diefenbach, A. K.; Griswold, J.; Muñoz, J.; Lara, L. E.; Valenzuela, C.; Burton, W. C.; Keeler, R.

    2010-12-01

    The 2008 eruption of Chaitén caldera, southern Chile, was one of the most explosive on Earth in the past two decades. The eruption began early on 2 May 2008 (UTC) and produced sub-plinian to plinian ash columns between 2 May and 9 May, before transitioning from explosive eruption of tephra to effusive eruption of rhyolite lava. A series of lava flow lobes accumulated within the caldera between late May and the end of the year, burying most of Chaitén’s prehistoric lava dome. A prominent lava spine was also extruded, starting in late 2008. The spine collapsed on 19 February 2009, producing a pyroclastic flow that extended out of the caldera and 7 km down the Río Chaitén. Dome growth continued through 2009, filling in much of the spine-collapse area and further expanding the composite dome through endogenous growth. Dome volumes are computed and eruption rates estimated using satellite data from 2008-10, photogrammetric analysis of oblique aerial photographs taken in January 2010, and digital elevation models derived from ASTER, SRTM, LIDAR and topographic maps. The 2008-10 dome has a total volume of approximately 0.8 km3. About 0.5 km3 erupted within the first four months, when extrusion rates were in the range 10-100 m3s-1. Extrusion rates decreased exponentially over the eruptive period. The 2008-10 dome is similar in volume and composition to the prehistoric lava dome, which has a volume of at least 0.5 km3. Together the two domes constitute about 20-40% of the 3.5-7 km3 collapse volume of the prehistoric caldera. The unusually rapid extrusion rates during the first four months are among the highest ever measured for silicic lava. Chaitén’s 2008-10 lava is obsidian and microcrystalline rhyolite with 75.35+/-0.02% SiO2. A large volume of low viscosity crystal-poor magma (about 0.1% phenocrysts) coupled with high extrusion pressures during the extended transition from explosive to effusive eruption style resulted in these exceptionally high extrusion rates.

  20. Permeable structures at Ceboruco lava dome, Mexico: the challenge of upscaling laboratory measurements to field constraint

    NASA Astrophysics Data System (ADS)

    Lamur, Anthony; Lavallee, Yan; De Angelis, Silvio

    2015-04-01

    Lava domes are, in their lifespan, variably permeable volcanic structures. During magma ascent, construction of a permeable network is facilitated by the coalescence of vesicles and fractures, which regulates magma outgassing and control whether eruption proceeds effusively or explosively. Here, we present a combined laboratory and field study of dome rock permeability, focusing on a ca. 19th century lava dome at Ceboruco, Mexico. The lava dome has a perfectly rounded shape with a diameter of ~80 metres and a height of ~35 metres. The dome consists of blocks ranging in size between centimetres and 5 metres, which reveal a range of porous structures: the rocks are commonly dense, but porosity occasionally reach 38%; some blocks are entirely massive, whilst others display tensile and shear fractures. Microscopic analysis reveals and equally intricate fracture networks. Permeability measurements are currently being performed on 4 rocks (with different porosities) in a hydrostatic pressure vessel at confining pressures of 6, 10, 15, 20, 30 and 40 MPa and averaged pore pressure of 5 MPa (with differential of 1 MPa). For each sample, the uniaxial compressive strength will be determined and permeability will be measured on samples, which have undergone fracture damage due to loading at different fractions of the uniaxial compressive strength (e.g., 80%, 90% and 100%). The laboratory study will be complemented by an electrical resistivity survey of the dome structure (to be undertaken this coming February-March 2015). We will optically measure the density of fractures (i.e., spacing), and width. The resistivity study will be performed at different scales (1-200 metres) to assess the extent of fractures in individual blocks as well as through the entire dome and its underlying root. Mesoscale permeability measurements will be attempted by introducing salinated water into cracks on metre-size blocks whilst performing 3D electrical resistivity tomography. We aim to discuss

  1. 3D Density Modeling with Gravity and Muon-Radiographic Observations in Showa-Shinzan Lava Dome, Usu, Japan

    NASA Astrophysics Data System (ADS)

    Nishiyama, Ryuichi; Miyamoto, Seigo; Okubo, Shuhei; Oshima, Hiromitsu; Maekawa, Tokumitsu

    2017-03-01

    We performed three-dimensional density modeling of Showa-Shinzan lava dome, Usu, Japan, by joint inversion of the gravity anomaly and recently obtained muon radiography data. Our multilayer emulsion muon detector significantly reduces the background noise in our measurements of the muon flux through the dome. The high-quality muon data enables us to more accurately reconstruct the density structure of the lava dome compared with our own previous work. We find that the lava dome consists of a cylindrical column of massive lava with a diameter of 300 m, and that there is no evidence of magma intrusion in the shallow part of the plateau, located east of the dome.

  2. Monitoring lava-dome growth during the 2004-2008 Mount St. Helens, Washington, eruption using oblique terrestrial photography

    USGS Publications Warehouse

    Major, J.J.; Dzurisin, D.; Schilling, S.P.; Poland, Michael P.

    2009-01-01

    We present an analysis of lava dome growth during the 2004–2008 eruption of Mount St. Helens using oblique terrestrial images from a network of remotely placed cameras. This underutilized monitoring tool augmented more traditional monitoring techniques, and was used to provide a robust assessment of the nature, pace, and state of the eruption and to quantify the kinematics of dome growth. Eruption monitoring using terrestrial photography began with a single camera deployed at the mouth of the volcano's crater during the first year of activity. Analysis of those images indicates that the average lineal extrusion rate decayed approximately logarithmically from about 8 m/d to about 2 m/d (± 2 m/d) from November 2004 through December 2005, and suggests that the extrusion rate fluctuated on time scales of days to weeks. From May 2006 through September 2007, imagery from multiple cameras deployed around the volcano allowed determination of 3-dimensional motion across the dome complex. Analysis of the multi-camera imagery shows spatially differential, but remarkably steady to gradually slowing, motion, from about 1–2 m/d from May through October 2006, to about 0.2–1.0 m/d from May through September 2007. In contrast to the fluctuations in lineal extrusion rate documented during the first year of eruption, dome motion from May 2006 through September 2007 was monotonic (± 0.10 m/d) to gradually slowing on time scales of weeks to months. The ability to measure spatial and temporal rates of motion of the effusing lava dome from oblique terrestrial photographs provided a significant, and sometimes the sole, means of identifying and quantifying dome growth during the eruption, and it demonstrates the utility of using frequent, long-term terrestrial photography to monitor and study volcanic eruptions.

  3. Integrated, multi-parameter, investigation of eruptive dynamics at Santiaguito lava dome, Guatemala

    NASA Astrophysics Data System (ADS)

    Lavallée, Yan; De Angelis, Silvio; Rietbrock, Andreas; Lamb, Oliver; Hornby, Adrian; Lamur, Anthony; Kendrick, Jackie E.; von Aulock, Felix W.; Chigna, Gustavo

    2016-04-01

    Understanding the nature of the signals generated at volcanoes is central to hazard mitigation efforts. Systematic identification and understanding of the processes responsible for the signals associated with volcanic activity are only possible when high-resolution data are available over relatively long periods of time. For this reason, in November 2014, the Liverpool Earth Observatory (LEO), UK, in collaboration with colleagues of the Instituto Nacional de Sismologia, Meteorologia e Hidrologia (INSIVUMEH), Guatemala, installed a large multi-parameter geophysical monitoring network at Santiaguito - the most active volcano in Guatemala. The network, which is to date the largest temporary deployment on Santiaguito, includes nine three-component broadband seismometers, three tiltmeters, and five infrasound microphones. Further, during the initial installation campaign we conducted visual and thermal infrared measurements of surface explosive activity and collected numerous rock samples for geochemical, geophysical and rheological characterisation. Activity at Santiaguito began in 1922, with the extrusion of a series of lava domes. In recent years, persistent dome extrusion has yielded spectacularly episodic piston-like motion displayed by characteristic tilt/seismic patterns (Johnson et al, 2014). This cyclicity episodically concludes with gas emissions or gas-and-ash explosions, observed to progress along a complex fault system in the dome. The explosive activity is associated with distinct geophysical signals characterised by the presence of very-long period earthquakes as well as more rapid inflation/deflation cycles; the erupted ash further evidences partial melting and thermal vesiculation resulting from fault processes (Lavallée et al., 2015). One year of data demonstrates the regularity of the periodicity and intensity of the explosions; analysis of infrasound data suggests that each explosion expulses on the order of 10,000-100,000 kg of gas and ash. We

  4. The Collapse of the Lava Dome at Soufriere Hills Volcano, 12-13 July 2003

    NASA Astrophysics Data System (ADS)

    Herd, R.; Edmonds, M.; Strutt, M.; Ottermeiler, L.

    2003-12-01

    A large dome collapse took place at the Soufriere Hills Volcano, Montserrat, on 12 July 2003. Around 120 million m3 of lava dome and talus collapsed to the east, generating large pyroclastic flows in the Tar River Valley. The collapse took place after a three-day-long hybrid earthquake swarm, which merged into a continuous tremor in the early morning of 12 July 2003. A period of brief but intense period of rainfall occurred between 6:30 and 9:30 am, which coincided with the onset of pyroclastic flow activity. Pyroclastic flows continued throughout the day, slowly increasing in volume and energy as the hotter interior of the talus and dome were exposed, this stage being similar to the evolution of dome collapses on 20 March 2000 and 29 July 2001. At 18:00 phreatic explosions began to take place where the block and ash flows were hitting sea on the Tar River Fan, sending black jets 50-100 metres vertically above the Fan. By 20:00 the pyroclastic flows were associated with energetic surges that were observed to be traveling 2-3 km over the surface of the sea at the mouth of the Tar River Valley. From 22:30 to 01:30 13 July the most energetic sequence of events took place, with one very large vulcanian explosion from the exposed upper conduit and dome remnants and 3-4 smaller explosive events. These explosions took place shortly after large volumes of dome material slumped into the sea down the Tar River Valley, the largest occurring at 23:34. This event caused a 1 metre high tsunami in Guadeloupe. The subsequent explosions were recorded by pressure sensors both on Montserrat and on the island of Martinique, 260 km to the south. This large single flow in the Tar River was associated with a block and ash flow that was confined to the Tar River valley and a powerful surge component derived from the lower reaches of the Tar River valley, which spread northwards, covering 10 km2 and reaching as far as Spanish Point, Bethel Village and White's Yard. This surge was immensely

  5. Miocene lava flows and domes, cooling fractures, carapace breccia, and avalanche deposits near Goldstone, California

    NASA Astrophysics Data System (ADS)

    Buesch, D.

    2013-12-01

    Mapping and petrography of volcanic rocks in western Fort Irwin (FI), California, provide insights into the cooling history of lava flows and domes and the formation of associated carapace breccia and avalanche deposits. The rocks formed on the eastern margin of the 19-16 Ma Eagle Crags volcanic field (Sabin and others, 1994). Lava compositions range from porphyritic olivine basalt to aphyric rhyolite. Basalt flows are 1-5 m thick and <1-2 km long, and sequences 5-50 m thick are traceable for >7 km. Andesite to rhyolite flows are 30-80 m thick and <1-3 km long, and domes have 100-300 m relief and radial length of 0.6-1.2 km. Cooling fractures, identified by occurrence of margins and geometry, are in all lava flows and domes. Similar to a 'rim' (Buesch and others, 1996 & 1999; Buesch, 2006), a 'margin' is a region along a fracture wall with a finer texture or different type of crystallinity or vesicularity compared to rock inward from the fracture. At FI, margins occur on many fractures and typically are 0.5-3 mm wide. They indicate that a fracture formed during initial cooling, before the bulk of the rock crystallized. Planarity and surface roughness are used to analyze fractures (Buesch and others, 1996). Typically at FI, cooling fractures are planar and smooth, and post-cooling fractures are slightly irregular and slightly rough. Typically, plan views of cooling fractures are 5-6 sided in olivine basalt, and 4-sided in andesite to rhyolite. Fracture sets are mostly perpendicular to the original surface of a flow, and some bend toward the interior. Many lava flows and domes have lateral and capping breccias referred to as carapace breccia. Similar breccia also cloaks individual lobes of composite domes. Carapace breccia can grade down into a non-brecciated interior, but in some cases, compositionally similar late-stage flow-banded lava was injected beneath the breccia, Breccia fragments are vitric or crystallized, and many have margins that do not match those of

  6. Mechanical behaviour of dacite from Mount St. Helens (USA): A link between porosity and lava dome extrusion mechanism (dome or spine)?

    NASA Astrophysics Data System (ADS)

    Heap, M. J.; Russell, J. K.; Kennedy, L. A.

    2016-12-01

    There is a rich diversity in lava dome morphology, from blocky domes and lobes to imposing spine and whaleback structures. The latter extrude via seismically active, gouge-rich conduit-margin faults, a manifestation of a brittle failure mode. Brittle versus ductile behaviour in volcanic rocks is known to be porosity dependent, and therefore offers a tantalising link between the properties of the material near the conduit margin and the extrusion mechanism (dome or spine). We test this hypothesis by complementing published data on the mechanical behaviour of dacites from the 2004-2008 spine-forming eruption at Mount St. Helens (MSH) with new data on dacite lavas collected from the 1980 dome. The 1980 dacite samples were deformed at room temperature under a range of pressures (i.e., depths) to investigate their mechanical behaviour and failure mode (brittle or ductile). Low-porosity dacite (porosity 0.19) is brittle up to an effective pressure of 30 MPa (depth 1 km) and is ductile at 40 MPa (depth 1.5 km). High-porosity dacite (porosity 0.32) is ductile above an effective pressure of 5 MPa (depth 200 m). Samples deformed in the brittle regime show well-developed ( 1 mm) shear fracture zones comprising broken glass and crystal fragments. Samples deformed in the ductile regime feature anastomosing bands of collapsed pores. The combined dataset is used to explore the influence of strain rate, temperature, and porosity on the mechanical behaviour and failure mode of dacite. A decrease in strain rate does not influence the strength of dacite at low temperature, but reduces strength at high temperature (850 °C). Due to the extremely low glass content of these materials, such weakening is attributed to the increased efficiency of subcritical crack growth at high temperature. However, when strain rate is kept constant, temperature does not significant impact strength reflecting the highly crystallised nature of dacite from MSH. Dacite from the 2004-2008 eruption is stronger

  7. The unique radar scattering properties of silicic lava flows and domes

    NASA Technical Reports Server (NTRS)

    Plaut, Jeffrey J.; Stofan, Ellen R.; Anderson, Steven W.; Crown, David A.

    1995-01-01

    Silicic (silica-rich) lava flows, such as rhyolite, rhyodacite, and dacite, possess unique physical properties primarily because of the relatively high viscosity of the molten lava. Silicic flows tend to be thicker than basaltic flows, and the resulting large-scale morphology is typically a steep-sided dome or flow lobe, with aspect ratios (height/length) sometimes approaching unity. The upper surfaces of silicic domes and flows are normally emplaced as relatively cool, brittle slabs that fracture as they are extruded from the central vent areas, and are then rafted away toward the flow margin as a brittle carapace above a more ductile interior layer. This mode of emplacement results in a surface with unique roughness characteristics, which can be well-characterized by multiparameter synthetic aperture radar (SAR) observations. In this paper, we examine the scattering properties of several silicic domes in the Inyo volcanic chain in the Eastern Sierra of California, using AIRSAR and TOPSAR data. Field measurements of intermediate-scale (cm to tens of m) surface topography and block size are used to assess the mechanisms of the scattering process, and to quantify the unique roughness characteristics of the flow surfaces.

  8. The danger of collapsing lava domes; lessons for Mount Hood, Oregon

    USGS Publications Warehouse

    Brantley, S.R.; Scott, W.E.

    1993-01-01

    Nestled in the crater of Oregon's majestic Mount Hood volcano is Crater Rock, a prominent feature known to thousands of skiers, climbers, and tourists who journey each year to the famous Timberline Lodge located high on the volcano's south flank. Crater Rock stands about 100m above the sloping crater floor and warm fumaroles along its base emit sulfur gases and a faint steam plume that is sometimes visible from the lodge. What most visitors do not know, however, is that Crater Rock is a volcanic lava dome only 200 years old. 

  9. Emplacement of a silicic lava dome through a crater glacier: Mount St Helens, 2004-06

    USGS Publications Warehouse

    Walder, J.S.; LaHusen, R.G.; Vallance, J.W.; Schilling, S.P.

    2007-01-01

    The process of lava-dome emplacement through a glacier was observed for the first time after Mount St Helens reawakened in September 2004. The glacier that had grown in the crater since the cataclysmic 1980 eruption was split in two by the new lava dome. The two parts of the glacier were successively squeezed against the crater wall. Photography, photogrammetry and geodetic measurements document glacier deformation of an extreme variety, with strain rates of extraordinary magnitude as compared to normal alpine glaciers. Unlike normal temperate glaciers, the crater glacier shows no evidence of either speed-up at the beginning of the ablation season or diurnal speed fluctuations during the ablation season. Thus there is evidently no slip of the glacier over its bed. The most reasonable explanation for this anomaly is that meltwater penetrating the glacier is captured by a thick layer of coarse rubble at the bed and then enters the volcano's groundwater system rather than flowing through a drainage network along the bed.

  10. The Taylor Creek Rhyolite of New Mexico: a rapidly emplaced field of lava domes and flows

    USGS Publications Warehouse

    Duffield, W.A.; Dalrymple, G.B.

    1990-01-01

    The Tertiary Taylor Creek Rhyolite of southwest New Mexico comprises at least 20 lava domes and flows. Each of the lavas was erupted from its own vent, and the vents are distributed throughout a 20 km by 50 km area. The volume of the rhyolite and genetically associated pyroclastic deposits is at least 100 km3 (denserock equivalent). The rhyolite contains 15%-35% quartz, sanidine, plagioclase, ??biotite, ??hornblende phenocrysts. Quartz and sanidine account for about 98% of the phenocrysts and are present in roughly equal amounts. With rare exceptions, the groundmass consists of intergrowths of fine-grained silica and alkali feldspar. Whole-rock major-element composition varies little, and the rhyolite is metaluminous to weakly peraluminous; mean SiO2 content is about 77.5??0.3%. Similarly, major-element compositions of the two feldsparphenocryst species also are nearly constant. However, whole-rock concentrations of some trace-elements vary as much as several hundred percent. Initial radiometric age determinations, all K-Ar and fission track, suggest that the rhyolite lava field grew during a period of at least 2 m.y. Subsequent 40Ar/39Ar ages indicate that the period of growth was no more than 100 000 years. The time-space-composition relations thus suggest that the Taylor Creek Rhyolite was erupted from a single magma reservoir whose average width was at least 30 km, comparable in size to several penecontemporaneous nearby calderas. However, this rhyolite apparently is not related to a caldera structure. Possibly, the Taylor Creek Phyolite magma body never became sufficiently volatile rich to produce a large-volume pyroclastic eruption and associated caldera collapse, but instead leaked repeatedly to feed many relatively small domes and flows. The new 40Ar/39Ar ages do not resolve preexisting unknown relative-age relations among the domes and flows of the lava field. Nonetheless, the indicated geologically brief period during which Taylor Creek Rhyolite magma was

  11. Preliminary paragenetic interpretation of the Quaternary topaz rhyolite lava domes of the Blackfoot volcanic field, southeastern Idaho

    NASA Astrophysics Data System (ADS)

    Lochridge, W. K., Jr.; McCurry, M. O.; Goldsby, R.

    2015-12-01

    The Quaternary topaz rhyolite lava domes of the bimodal, basalt-dominated Blackfoot volcanic field (BVF), SE Idaho occur in three clusters. We refer to these as the China Hat lava dome field (southernmost; ~ 57 ka), and the 1.4 to 1.5 Ma Sheep Island and White Mountain (northernmost) lava dome fields. The rhyolites and surrounding, more voluminous basalt lavas closely resemble coeval Quaternary rocks erupted to the north along the Eastern Snake River Plain segment of the Yellowstone-Snake River Plain volcanic track. However rhyolites in BVF are distinguished by having more evolved Sr- and Nd-isotopic ratios, as well as having phenocryst assemblages that includes hydrous phases (biotite and hornblende), thorite, and vapor-phase topaz. This study seeks to improve our understanding of the unique conditions of magma evolution that led to these differences. We focus on textural features of major and accessory phenocrysts as a basis for inferring paragenesis for rhyolites from the China Hat lava dome field. Preliminary work indicates that there are three sequentially formed populations of textures among magmatic phases: 1. population of anhedral quartz and plagioclase; 2. population of euhedral grains that includes quartz, sandine, plagioclase, biotite, hornblende, Fe-Ti oxides, zircon and apatite; 3. boxy cellular (skeletal?) sanidine and quartz. We speculate that the first population are resorbed antecrysts, the second formed prior to eruption as autocrysts (at or near equilibrium?), and the third formed soon before or during eruption.

  12. Rheology of Lava Flows on Europa and the Emergence of Cryovolcanic Domes

    NASA Technical Reports Server (NTRS)

    Quick, Lynnae C.; Glaze, Lori S.; Baloga, Steve M.

    2015-01-01

    There is ample evidence that Europa is currently geologically active. Crater counts suggest that the surface is no more than 90 Myr old, and cryovolcanism may have played a role in resurfacing the satellite in recent geological times. Europa's surface exhibits many putative cryovolcanic features, and previous investigations have suggested that a number of domes imaged by the Galileo spacecraft may be volcanic in origin. Consequently, several Europa domes have been modeled as viscous effusions of cryolava. However, previous models for the formation of silicic domes on the terrestrial planets contain fundamental shortcomings. Many of these shortcomings have been alleviated in our new modeling approach, which warrants a re-assessment of the possibility of cryovolcanic domes on Europa.

  13. An experimental insight into the evolution of permeability at high temperatures and applications for shallow conduit and lava dome degassing

    NASA Astrophysics Data System (ADS)

    Chadderton, Amy; Sammonds, Peter; Meredith, Philip; Smith, Rosanna; Tuffen, Hugh; Gaunt, Elizabeth

    2016-04-01

    Two recent eruptions in Chile, at Chaitén Volcano in 2008-10 and Cordón Caulle in 2011-12, allowed the first detailed observations of rhyolitic activity and provided insights into the evolution of highly silicic eruptions. Both events exhibited simultaneous explosive and effusive activity, with both lava and ash plumes emitted from the same vent [1]. The permeability of fracture networks that act as fluid flow pathways is key to understanding such eruptive behaviour. Here, we report results from a systematic experimental investigation of permeability in volcanic rocks at magmatic temperatures and pressures, in the presence of pore fluids using our newly-developed high-temperature permeability facility. Enhancements to the High Temperature Triaxial Deformation Cell at UCL [2] have enabled us to make permeability measurements on 25mm x 50mm cores at both elevated temperature and elevated hydrostatic pressure [3]. We present results from several suites of permeability measurements on samples of dome dacite from the 2004-08 eruption of Mount St Helens, and rhyolite collected from the lava dome formed during the 2008-10 eruption of Chaitén, Chile. Tests were conducted at temperatures up to 900oC and under an effective pressure of 5 MPa, using the steady-state flow technique. Samples were cooled to room temperature between each high temperature test, and the permeability of each sample was re-measured before heating to the next temperature increment in the series. Additional longer duration high temperature tests were also conducted to investigate the development of a permeable network at high temperatures over time. The results show a complex permeability evolution that includes a reduction in permeability by approximately 3 orders of magnitude up to 600oC. Together with thermal cracking tests, AE data and SEM/thin section analysis these new experimental permeability results are applied to enhance our understanding of the complex issue of shallow conduit and lava

  14. Comment on: Cyclic extrusion of a lava dome based on a stick-slip mechanism, by Costa et al. (2012)

    NASA Astrophysics Data System (ADS)

    Alexandrov, D. V.; Bashkirtseva, I. A.; Ryashko, L. B.

    2017-02-01

    Costa et al. (2012) obtained a simple set of nonlinear equations that describe the cyclic extrusions of a lava dome based on a stick-slip model. Here we correct some sign errors in the published derivation of these equations and show that it has exact analytical solutions.

  15. Muon radiography and deformation analysis of the lava dome formed by the 1944 eruption of Usu, Hokkaido —Contact between high-energy physics and volcano physics—

    PubMed Central

    TANAKA, Hiroyuki K. M.; YOKOYAMA, Izumi

    2008-01-01

    Lava domes are one of the conspicuous topographic features on volcanoes. The subsurface structure of the lava dome is important to discuss its formation mechanism. In the 1944 eruption of Volcano Usu, Hokkaido, a new lava dome was formed at its eastern foot. After the completion of the lava dome, various geophysical methods were applied to the dome to study its subsurface structure, but resulted in a rather ambiguous conclusion. Recently, from the results of the levelings, which were repeated during the eruption, “pseudo growth curves” of the lava dome were obtained. The curves suggest that the lava dome has a bulbous shape. In the present work, muon radiography, which previously proved effective in imaging the internal structure of Volcano Asama, has been applied to the Usu lava dome. The muon radiography measures the distribution of the “density length” of volcanic bodies when detectors are arranged properly. The result obtained is consistent with the model deduced from the pseudo growth curves. The measurement appears to afford useful method to clarify the subsurface structure of volcanoes and its temporal changes, and in its turn to discuss volcanic processes. This is a point of contact between high-energy physics and volcano physics. PMID:18941290

  16. Catastrophic lava dome failure at Soufrière Hills Volcano, Montserrat, 12-13 July 2003

    USGS Publications Warehouse

    Herd, Richard A.; Edmonds, Marie; Bass, Venus A.

    2005-01-01

    The lava dome collapse of 12–13 July 2003 was the largest of the Soufrière Hills Volcano eruption thus far (1995–2005) and the largest recorded in historical times from any volcano; 210 million m3 of dome material collapsed over 18 h and formed large pyroclastic flows, which reached the sea. The evolution of the collapse can be interpreted with reference to the complex structure of the lava dome, which comprised discrete spines and shear lobes and an apron of talus. Progressive slumping of talus for 10 h at the beginning of the collapse generated low-volume pyroclastic flows. It undermined the massive part of the lava dome and eventually prompted catastrophic failure. From 02:00 to 04:40 13 July 2003 large pyroclastic flows were generated; these reached their largest magnitude at 03:35, when the volume flux of material lost from the lava dome probably approached 16 million m3 over two minutes. The high flux of pyroclastic flows into the sea caused a tsunami and a hydrovolcanic explosion with an associated pyroclastic surge, which flowed inland. A vulcanian explosion occurred during or immediately after the largest pyroclastic flows at 03:35 13 July and four further explosions occurred at progressively longer intervals during 13–15 July 2003. The dome collapse lasted approximately 18 h, but 170 of the total 210 million m3 was removed in only 2.6 h during the most intense stage of the collapse.

  17. Monitoring the Surface Changes and Growth of the Soufriére Hills Lava Dome: Thermal Infrared Analyses of Field and Spaceborne Data

    NASA Astrophysics Data System (ADS)

    Kuhn, S. S.; Ramsey, M.

    2002-12-01

    The Advanced Spaceborne Thermal Emission Reflectance Radiometer (ASTER) is the only high resolution multispectral thermal infrared (TIR) imager currently in Earth-orbit. The data being returned are ideal for discerning physical variations on the surface of active lava domes such as Soufriére Hills, Montserrat. The 90 meter spatial resolution of the TIR data provides accurate measurements of the surface temperature and emissivity. This information can be used to map the glass, vesicle and petrological distribution on the dome's surface, and therefore provide fundamental insights into lava emplacement processes. For this study, six nighttime ASTER scenes of the dome and surrounding region captured over the past two years were chosen. These images show the entire dome, are relatively cloud-free and have significant thermal anomalies present, including summit and pyroclastic flow deposits. In order to validate the image data, detailed field-based information was collected including temperature, GPS and spectroscopic data (similar to the ASTER spectral band passes). In addition, a searchable database of activity based on Montserrat Volcano Observatory (MVO) reports has been created and used as a framework for the image data. Field measurements were taken in conjunction with a nighttime overpass of ASTER. Active areas were determined both visually and with the aid of high resolution radiometers. The heightened activity precluded close field measurements; therefore, long range laser profiling and GPS were used to locate anomalies on the dome surface. A CIMEL spectro-radiometer with identical TIR wavelengths to ASTER and a FRIR were used to map surface temperature and spectral variations. Numerous target areas were chosen including spines, lobes, incandescence, and fresh pyroclastic deposits. Samples of the most recent pyroclastic deposits have been collected and are being analyzed for mineral, phenocryst, and vesicle content using both petrographic and infrared analyses

  18. Geophysical imaging of the inner structure of a lava dome and its environment through gravimetry and magnetism

    NASA Astrophysics Data System (ADS)

    Portal, A.; Gailler, L.-S.; Labazuy, P.; Lénat, J.-F.

    2016-06-01

    Volcanic lava domes are compound edifices resulting from complex growth processes including intrusion and extrusion phases, explosions and collapses. Here, we present the study of a complex volcanic system, located in the Chaîne des Puys volcanic field (French Massif Central, France) and centred on the Puy de Dôme volcano, an 11,000 years old volcano. Our approach is based on a morpho-structural analysis of a high resolution DTM (0.5 m) and geophysical imaging methods. Both gravity and magnetic high resolution surveys have been carried out on the lava dome and the nearby volcanic structures. We computed 3D inverse and 2D forwards models. Based on our current knowledges about volcanic dome structure, the geophysical models allow us to propose a synthetic geological model of the inner structure of the Puy de Dôme and surrounding areas. This model suggests a scenario for the formation of the lava dome and the inferred intrusions located on both sides. The Puy de Dôme could possibly be the southern tip of the northern intrusion.

  19. Modeling the dynamic response of a crater glacier to lava-dome emplacement: Mount St Helens, Washington, USA

    USGS Publications Warehouse

    Price, Stephen F.; Walder, Joseph S.

    2007-01-01

    The debris-rich glacier that grew in the crater of Mount St Helens after the volcano's cataclysmic 1980 eruption was split in two by a new lava dome in 2004. For nearly six months, the eastern part of the glacier was squeezed against the crater wall as the lava dome expanded. Glacier thickness nearly doubled locally and surface speed increased substantially. As squeezing slowed and then stopped, surface speed fell and ice was redistributed downglacier. This sequence of events, which amounts to a field-scale experiment on the deformation of debris-rich ice at high strain rates, was interpreted using a two-dimensional flowband model. The best match between modeled and observed glacier surface motion, both vertical and horizontal, requires ice that is about 5 times stiffer and 1.2 times denser than normal, temperate ice. Results also indicate that lateral squeezing, and by inference lava-dome growth adjacent to the glacier, likely slowed over a period of about 30 days rather than stopping abruptly. This finding is supported by geodetic data documenting dome growth.

  20. Gravitational Failures of Lava Domes at Intersections With Tectonic Faults: Examples from Tatun Volcanic Group, Northern Taiwan

    NASA Astrophysics Data System (ADS)

    Belousova, M.; Belousov, A.; Chen, C.

    2009-12-01

    The dominantly andesitic Tatun Volcanic Group of Northern Taiwan was formed during the Pleistocene - Early Holocene. The volcanoes are represented by lava domes of moderate sizes: heights up to 350 m (absolute altitudes 800 - 1120 m a.s.l.), base diameters up to 1.5 km, and volumes up to 0.3 km3. Many of the domes have broad, shallow horseshoe-shaped scars (0.5-1.0 km across) formed by gravitational collapses. Field examination revealed deposits of collapses of volcanoes Datun, Cising, Siaoguanyin, Cigu, and Dajianhou. The largest of the collapses (V ~ 0.1 km3) occurred at Mt. Datun. The collapse formed a typical debris avalanche deposit composed mainly of block facies. The avalanche traveled a distance L ~ 5 km, dropped a height H ~ 1 km, and was moderately mobile H/L ~ 0.2. The age of the collapse is > 24,000 yrs because the related debris avalanche deposit is covered by a younger debris avalanche deposit of Siaoguanyin volcano containing charcoal having calibrated 14C age 22,600-23,780 BP. The Siaoguanyin debris avalanche deposit (V~ 0.02 km3; L ~ 6 km; H ~ 1 km; H/L ~ 0.16) is composed of massive, very coarse-grained, fines-poor, gravelly material represented predominantly by very dense, dark-grey andesite. The avalanche was hot during deposition; material of a lava dome which had no time to cool down completely after extrusion was involved into the collapse. The avalanche speed was 40 m/s at a distance 5 km from the source, basing on 80 m of the avalanche run-up. The latest (calibrated age 6000-6080 BP) large-scale collapse (V~0.05 km3, H/L ~ 0.25) occurred at Mt. Cising in the form of numerous retrogressive landslide blocks, which did not transform into a long runout debris avalanche. The leading snout of the landslide traveled 2.0 km, while rear slide blocks traveled only several hundred meters and stopped near the landslide source. Its maximum dropped height is only ~0.5 km. A former lava coulee, which was involved in the collapse, underwent weak

  1. Magma ascent and lava dome evolution at Volcán de Colima, Mexico

    NASA Astrophysics Data System (ADS)

    Varley, N. R.; Arámbula, R.; Lavallée, Y.; Bernstein, M.; Ryan, A. G.; Maskell, A.

    2009-12-01

    The transition between explosive and effusive activity can be triggered by subtle variations in parameters which dictate the efficiency and speed of degassing from an ascending magma body. Indirect methods have to be utilized to constrain these parameters, to test and refine numerical models, which ultimately permit a more powerful interpretation of monitoring data. Recent activity at Volcán de Colima has included many transitions between different regimes, offering a great opportunity to examine conduit processes. Explosive activity peaked in 2005 with 30 Vulcanian eruptions producing pyroclastic flows, some reaching >5km from the volcano. Each event was associated with a swarm of long-period (LP) seismic events. A poor correlation between swarm characteristics and the size of the explosion suggests independence between the source mechanisms of each phenomenon. The LP events were divided into 10 families, all of which reappeared in different swarms and the majority continued to occur after the Vulcanian explosion. This is evidence of the complexity of the upper edifice, with the source regions for the LP events remaining unaffected by the explosions. We believe they are produced by brittle deformation once a certain strain-rate threshold has been surpassed. The explosions were associated with rapidly ascending magma bodies that were degassing and crystallizing near the surface, each one being destroyed in the subsequent explosion. Magma sometimes reached the crater, with small short-lived domes being observed. In some cases a post-explosion increase in amplitude of the LP events might have reflected an increase in effusion rate after an unloading of material higher in the vent. Volcán de Colima has produced 5 episodes of effusive activity in the last 11 years. These have been of variable duration and intensity, with over 2 orders of magnitude variation in the effusion rate. The current phase has been characterised by a remarkably sustained (from Jan. 07 to at

  2. Pyroclastic flows generated by gravitational instability of the 1996-97 lava dome of Soufriere Hills Volcano, Montserrat

    USGS Publications Warehouse

    Cole, P.D.; Calder, E.S.; Druitt, T.H.; Hoblitt, R.; Robertson, R.; Sparks, R.S.J.; Young, S.R.

    1998-01-01

    Numerous pyroclastic flows were produced during 1996-97 by collapse of the growing andesitic lava dome at Soufriere Hills Volcano, Montserrat. Measured deposit volumes from these flows range from 0.2 to 9 ?? 106 m3. Flows range from discrete, single pulse events to sustained large scale dome collapse events. Flows entered the sea on the eastern and southern coasts, depositing large fans of material at the coast. Small runout distance (<1 km) flows had average flow front velocities in the order of 3-10 m/s while flow fronts of the larger runout distance flows (up to 6.5 km) advanced in the order of 15-30 m/s. Many flows were locally highly erosive. Field relations show that development of the fine grained ash cloud surge component was enhanced during the larger sustained events. Periods of elevated pyroclastic flow productivity and sustained dome collapse events are linked to pulses of high magma extrusion rates.Numerous pyroclastic flows were produced during 1996-97 by collapse of the growing andesitic lava dome at Soufriere Hills Volcano, Montserrat. Measured deposit volumes from these flows range from 0.2 to 9??106 m3. Flows range from discrete, single pulse events to sustained large scale dome collapse events. Flows entered the sea on the eastern and southern coasts, depositing large fans of material at the coast. Small runout distance (<1 km) flows had average flow front velocities in the order of 3-10 m/s while flow fronts of the larger runout distance flows (up to 6.5 km) advanced in the order of 15-30 m/s. Many flows were locally highly erosive. Field relations show that development of the fine grained ash cloud surge component was enhanced during the larger sustained events. Periods of elevated dome pyroclastic flow productivity and sustained collapse events are linked to pulses of high magma extrusion rates.

  3. Merapi's lava dome splitting explosion on 18 November 2013 observed by lidar and digital image correlation analysis.

    NASA Astrophysics Data System (ADS)

    Darmawan, Herlan; Walter, Thomas; Nikkhoo, Mehdi; Richter, Nicole

    2015-04-01

    After the 2010 Merapi eruption, the lava dome in the summit of the volcano was firstly growing and then subject to gradual cooling and contraction. In November 2013, a major phreatomagmatic explosion occurred, which caused an eruption column rising over 2 km high and destroyed a number of monitoring instruments in the near field. Bombs were thrown out over 1 km distance. The eruption produced volcanic ash and very fine materials. Deformation data from tilt or EDM showed no wide inflation or deflation associated with this eruption. In addition, high resolution TerraSAR-X data analysis also showed no edifice-wide deformation (Walter et al., 2015). Here we further examine two datasets to determine the morphologic and structural effects of this eruption. First we exploit fixed installed monitoring cameras and use a digital image correlation method to investigate geometric changes before and after the eruption. Second we acquired a high resolution terrestrial Lidar data set after the explosion and compared this another lidar data set acquired before. The result shows details on the splitted dome, the volume of the eruption and thickness of the deposits, and suggests that a new block at the front of the dome is inherently unstable and might break off to form a block and ash flow in the near future. Reference: TR Walter, Subandriyo J, Kirbani S, Bathke H, Suryanto W, Aisyah N, Darmawan H, Jousset P, Lühr BG, Dahm T (2015) Volcano-tectonic control of Merapi's lava dome splitting: The November 2013 fracture observed from high resolution TerraSAR-X data. Tectonophysics 639, 12 January 2015, Pages 23-33. doi:10.1016/j.tecto.2014.11.007

  4. Downstream aggradation owing to lava dome extrusion and rainfall runoff at Volcán Santiaguito, Guatemala

    USGS Publications Warehouse

    Harris, Andrew J. L.; Vallance, James W.; Kimberly, Paul; Rose, William I.; Matías, Otoniel; Bunzendahl, Elly; Flynn, Luke P.; Garbeil, Harold

    2006-01-01

    Persistent lava extrusion at the Santiaguito dome complex (Guatemala) results in continuous lahar activity and river bed aggradation downstream of the volcano. We present a simple method that uses vegetation indices extracted from Landsat Thematic Mapper (TM) data to map impacted zones. Application of this technique to a time series of 21 TM images acquired between 1987 and 2000 allow us to map, measure, and track temporal and spatial variations in the area of lahar impact and river aggradation.In the proximal zone of the fluvial system, these data show a positive correlation between extrusion rate at Santiaguito (E), aggradation area 12 months later (Aprox), and rainfall during the intervening 12 months (Rain12): Aprox=3.92+0.50 E+0.31 ln(Rain12) (r2=0.79). This describes a situation in which an increase in sediment supply (extrusion rate) and/or a means to mobilize this sediment (rainfall) results in an increase in lahar activity (aggraded area). Across the medial zone, we find a positive correlation between extrusion rate and/or area of proximal aggradation and medial aggradation area (Amed): Amed=18.84-0.05 Aprox - 6.15 Rain12 (r2=0.85). Here the correlation between rainfall and aggradation area is negative. This describes a situation in which increased sediment supply results in an increase in lahar activity but, because it is the zone of transport, an increase in rainfall serves to increase the transport efficiency of rivers flowing through this zone. Thus, increased rainfall flushes the medial zone of sediment.These quantitative data allow us to empirically define the links between sediment supply and mobilization in this fluvial system and to derive predictive relationships that use rainfall and extrusion rates to estimate aggradation area 12 months hence.

  5. Structure and evolution of an active resurgent dome evidenced by geophysical investigations: The Yenkahe dome-Yasur volcano system (Siwi caldera, Vanuatu)

    NASA Astrophysics Data System (ADS)

    Brothelande, E.; Lénat, J.-F.; Chaput, M.; Gailler, L.; Finizola, A.; Dumont, S.; Peltier, A.; Bachèlery, P.; Barde-Cabusson, S.; Byrdina, S.; Menny, P.; Colonge, J.; Douillet, G. A.; Letort, J.; Letourneur, L.; Merle, O.; Di Gangi, F.; Nakedau, D.; Garaebiti, E.

    2016-08-01

    In this contribution, we focus on one of the most active resurgences on Earth, that of the Yenkahe dome in the Siwi caldera (Tanna Island, Vanuatu), which is associated with the persistently active Yasur volcano. Gravity and magnetic surveys have been carried out over the past few years in the area, as well as electrical methods including electrical resistivity tomography (ERT), time domain electro-magnetics (TDEM) and self-potential (SP). These investigations were completed by thermometry, CO2 soil gas measurements, field observations and sampling. This multi-method approach allows geological structures within the caldera to be identified, as well as associated hydrothermal features. The global structure of the caldera is deduced from gravity data, which shows the caldera rim as a high density structure. Large lava fields, emplaced before and after the onset of resurgence, are evidenced by combined gravity, magnetic and resistivity signals. In the middle of the caldera, the Yenkahe dome apparently results from a combination of volcanic and tectonic events, showing that lava extrusion and resurgence have been operating simultaneously or alternately during the Siwi caldera post-collapse history. There is a clear distinction between the western and eastern parts of the dome. The western part is older and records the growth of an initial volcanic cone and the formation of a small caldera. This small caldera (paleo-Yasur caldera), partially filled with lava flows, is the present-day focus of volcanic activity and associated fluid circulation and alteration. The eastern part of the dome is presumably younger, and is characterized by intense, extensive hydrothermal alteration and activity. Its northern part is covered by lava flow piles and exhibits a shallow hydrothermal zone in ERT. The southern part has hydrothermal alteration and activity extending at least down to the base of the resurgent dome. This part of the dome is built up of low cohesion rock and is thus

  6. Circulation patterns in active lava lakes

    NASA Astrophysics Data System (ADS)

    Redmond, T. C.; Lev, E.

    2014-12-01

    Active lava lakes provide a unique window into magmatic conduit processes. We investigated circulation patterns of 4 active lava lakes: Kilauea's Halemaumau crater, Mount Erebus, Erta Ale and Nyiragongo, and in an artificial "lava lake" constructed at the Syracuse University Lava Lab. We employed visual and thermal video recordings collected at these volcanoes and use computer vision techniques to extract time-dependent, two-dimensional surface velocity maps. The large amount of data available from Halemaumau enabled us to identify several characteristic circulation patterns. One such pattern is a rapid acceleration followed by rapid deceleration, often to a level lower than the pre-acceleration level, and then a slow recovery. Another pattern is periodic asymmetric peaks of gradual acceleration and rapid deceleration, or vice versa, previously explained by gas pistoning. Using spectral analysis, we find that the dominant period of circulation cycles at approximately 30 minutes, 3 times longer than the dominant period identified previously for Mount Erebus. Measuring a complete surface velocity field allowed us to map and follow locations of divergence and convergence, therefore upwelling and downwelling, thus connecting the surface flow with that at depth. At Nyiragongo, the location of main upwelling shifts gradually, yet is usually at the interior of the lake, for Erebus it is usually along the perimeter yet often there is catastrophic downwelling at the interior; For Halemaumau upwelling/downwelling position is almost always on the perimeter. In addition to velocity fields, we developed an automated tool for counting crustal plates at the surface of the lava lakes, and found a correlation, and a lag time, between changes if circulation vigor and the average size of crustal plates. Circulation in the artificial basaltic lava "lake" was limited by its size and degree of foaming, yet we measured surface velocities and identify patterns. Maximum surface velocity

  7. Intrusive and extrusive growth of the Mount St Helens lava dome

    NASA Technical Reports Server (NTRS)

    Fink, Jonathan H.; Malin, Michael C.; Anderson, Steven W.

    1990-01-01

    High-resolution, digital topographic maps of the Mount St. Helens dome derived from aerial photographs are used here to make a quantitative assessment of the partitioning of magma into endogenous intrusion and exogenous lobes. The endogenous growth is found to be predictable, which shows that the cooling dome controls its own development independently of such deep-seated factors as magma overpressure and extrusion rate. The observed regular decrease in exogenous growth rate also allows volume prediction. Knowledge of the volume can be used to determine when an ongoing eruptive event should end. Finally, the observed transition from predominantly exogenous to predominantly endogenous growth reflects the increase in crust thickness, which in turn seems to depend on long repose periods rather than some fundamental change in the character of the dome.

  8. Linking Seismicity at Depth to the Mechanics of a Lava Dome Failure - a Forecasting Approach

    NASA Astrophysics Data System (ADS)

    Salvage, R. O.; Neuberg, J. W.; Murphy, W.

    2014-12-01

    Soufriere Hills volcano (SHV), Montserrat has been in a state of ongoing unrest since 1995. Prior to eruptions, an increase in the number of seismic events has been observed. We use the Material Failure Law (MFL) (Voight, 1988) to investigate how an accelerating number of low frequency seismic events are related to the timing of a large scale dome collapse in June 1997. We show that although the forecasted timing of a dome collapse may coincide with the known timing, the accuracy of the application of the MFL to the data is poor. Using a cross correlation technique we show how characterising seismicity into similar waveform "families'' allows us to focus on a single process at depth and improve the reliability of our forecast. A number of families are investigated to assess their relative importance. We show that despite the timing of a forecasted dome collapse ranging between several hours of the known timing of collapse, each of the families produces a better forecast in terms of fit to the seismic acceleration data than when using all low frequency seismicity. In addition, we investigate the stability of such families between major dome collapses (1997 and 2003), assessing their potential for use in real-time forecasting. Initial application of Grey's Incidence Analysis suggests that a key parameter influencing the potential for a large scale slumping on the dome of SHV is the rate of low frequency seismicity associated with magma movement and dome growth. We undertook numerical modelling of an andesitic dome with a hydrothermally altered layer down to 800m. The geometry of the dome is based on SHV prior to the collapse of 2003. We show that a critical instability is reached once slope angles exceed 25°, corresponding to a summit height of just over 1100m a.s.l.. The geometry of failure is in close agreement with the identified failure plane suggesting that the input mechanical properties are broadly consistent with reality. We are therefore able to compare

  9. The Sequential Emplacement of the Chaos Crags Dome Complex in Lassen National Park and a Subsequent Avalanche Event Revealing the Internal Structure of a Crystal-Rich Lava Dome

    NASA Astrophysics Data System (ADS)

    Watts, R. B.; Clynne, M. A.; Sparks, R. S.; Christiansen, R. L.

    2013-12-01

    The Chaos Crags are an aptly named and spectacularly well-preserved nest of 6 crystal-rich rhyodacitic lava domes that lie in the shadow of the renowned Lassen Peak in Lassen National Park, northern California. Each of the domes is composed of a precarious pile of large angular lava blocks indicative of a relatively fast extrusion rate. However, the 2 southernmost domes (i.e. Group 1) exhibit a coulée-like appearance with asymmetric appearance, a thick, glassy basal breccia and distinct concentric flow ridges on the upper surface. The 4 northernmost domes (i.e. Group 2) are notably more dome-like, lacking lateral flow-features and any basal breccia but displaying steeper, blocky flanks and overall low Aspect Ratio. Petrologically, the 2 Groups are very similar in whole-rock composition except there is a distinct difference in the amount of mafic inclusions present - that is ~2 vol% (Group1 domes) and ~10vol% (Group 2 domes). The age of emplacement of the Crags has been previously determined as between 1125 and 375 years B.P (Clynne & Muffler, 1989). Following a period of quiescence, a series of 3 rock-fall avalanches, most likely triggered by a tectonic earthquake, collapsed away from one of the Group 2 domes to produce the 'Jumbles Avalanche' deposit. This impressive deposit (total volume of ~7km2) spilled across the northeastern landscape focused away from the base of Dome C, one of the Group 2 domes. The avalanche events left behind a near-vertical scarp composed of shattered, massive lava riddled with closely-spaced sigmoidal cooling joints to produce a very unstable ~250 meter high and ~300 meter wide metastable structure. On its upper surface, the remnants of a smooth semi-cylindical surface scored with striations is evident. Sampling from this surface and other points away from this surface highlighted the presence of highly fragmented lava with broken jigsaw-style phenocrysts up to one meter away from the smooth surface. Samples taken from a larger

  10. Origin and potential geothermal significance of China Hat and other late Pleistocene topaz rhyolite lava domes of the Blackfoot Volcanic Field, SE Idaho

    NASA Astrophysics Data System (ADS)

    McCurry, M. O.; Pearson, D. M.; Welhan, J. A.; Kobs-Nawotniak, S. E.; Fisher, M. A.

    2014-12-01

    The Snake River Plain and neighboring regions are well known for their high heat flow and robust Neogene-Quaternary tectonic and magmatic activity. Interestingly, however, there are comparatively few surficial manifestations of geothermal activity. This study is part of a renewed examination of this region as a possible hidden or blind geothermal resource. We present a testable, integrated volcanological, petrogenetic, tectonic and hydrothermal conceptual model for 57 ka China Hat and cogenetic topaz rhyolite lava domes of the Blackfoot Volcanic Field. This field is well suited for analysis as a blind resource because of its distinctive combination of (1) young bimodal volcanism, petrogenetic evidence of shallow magma storage and evolution, presence of coeval extension, voluminous travertine deposits, and C- and He-isotopic evidence of active magma degassing; (2) a paucity of hot springs or other obvious indicators of a geothermal resource in the immediate vicinity of the lava domes; and (3) proximity to a region of high crustal heat flow, high-T geothermal fluids at 2.5-5 km depth and micro-seismicity characterized by its swarming nature. Eruptions of both basalt and rhyolite commonly evolve from minor phreatomagmatic to effusive. In our model, transport of both magmatic and possible deep crustal aqueous fluids may be controlled by preexisting crustal structures, including west-dipping thrust faults. Geochemical evolution of rhyolite magma is dominated by mid- to upper-crustal fractional crystallization (with pre-eruption storage and phenocryst formation at ~14 km). Approximately 1.2 km3 of topaz rhyolite have been erupted since 1.4 Ma, yielding an average eruption rate of 0.8 km3/m.y. Given reasonable assumptions of magma cumulate formation and eruption rates, and initial and final volatile concentrations, we infer average H2O and CO2 volatile fluxes from the rhyolite source region of ~2MT/year and 340 T/day, respectively. Lithium flux may be comparable to CO2.

  11. Evidence for the development of permeability anisotropy in lava domes and volcanic conduits

    NASA Astrophysics Data System (ADS)

    Farquharson, Jamie I.; Heap, Michael J.; Lavallée, Yan; Varley, Nick R.; Baud, Patrick

    2016-09-01

    The ease at which exsolving volatiles can migrate though magma and outgas influences the explosivity of a volcanic eruption. Volcanic rocks often contain discrete discontinuities, providing snapshots of strain localisation processes that occur during magma ascent and extrusion. Whether these features comprise pathways for or barriers to fluid flow is thus of relevance for volcanic eruption and gas emission modelling. We report here on nine discontinuity-bearing andesite blocks collected from Volcán de Colima, Mexico. We present a systematic porosity and permeability study of fifty cores obtained from the blocks collected, and interpret the genetic processes of the discontinuities through detailed microstructural examination. Bands in pumiceous blocks were inferred to be relicts of inhomogeneous bubble expansion which, despite significantly increasing porosity, do not markedly affect permeability. Other discontinuities in our blocks are interpreted to be shear strain-induced flow banding, cavitation porosity, and/or variably healed fractures. In each of these cases, an increase in permeability (up to around three orders of magnitude) was measured relative to the host material. A final sample contained a band of lower porosity than the host rock, characterised by variably infilled pores. In this case, the band was an order of magnitude less permeable than the host rock, highlighting the complex interplay between dilatant and densifying processes in magma. We therefore present evidence for significant permeability anisotropy within the conduit and/or dome of a volcanic system. We suggest that the abundance and distribution of strain localisation features will influence the escape or entrapment of volatiles and therefore the evolution of pore pressure within active volcanic systems. Using a simple upscaling model, we illustrate the relative importance of permeable structures over different lengthscales. Strain localisation processes resulting in permeability

  12. Underwater observations of active lava flows from Kilauea volcano, Hawaii

    USGS Publications Warehouse

    Tribble, G.W.

    1991-01-01

    Underwater observation of active submarine lava flows from Kilauea volcano, Hawaii, in March-June 1989 revealed both pillow lava and highly channelized lava streams flowing down a steep and unconsolidated lava delta. The channelized streams were 0.7-1.5 m across and moved at rates of 1-3 m/s. The estimated flux of a stream was 0.7 m3/s. Jets of hydrothermal water and gas bubbles were associated with the volcanic activity. The rapidly moving channelized lava streams represent a previously undescribed aspect of submarine volcanism. -Author

  13. Long-period events, the most characteristic seismicity accompanying the emplacement and extrusion of a lava dome in Galeras Volcano, Colombia, in 1991

    USGS Publications Warehouse

    Gil, Cruz F.; Chouet, B.A.

    1997-01-01

    Since its reactivation in 1988 the principal eruptions of Galeras Volcano occurred on May 4-9, 1989, July 16, 1992, and January 14, March 23, April 3, April 14 and June 7, 1993. The initial eruption was a phreatic event which clearly marked a new period of activity. A lava dome was extruded within the main crater in October 1991 and subsequently destroyed in an explosive eruption on July 16, 1992. The eruptions that followed were all vulcanian-type explosions. The seismicity accompanying the emplacement, extrusion, and destruction of the lava dome was dominated by a mix of long-period (LP) events and tremor displaying a variety of waveforms. Repetitive LP events with dominant periods in the range 0.2-1 s were observed in October and November 1991 and visually correlated with short energetic pulses of gas venting through a crack bisecting the dome surface. Each LP event was characterized by a weak precursory signal with dominant periods in the range 0.05-0.1 s lasting roughly 7 s. Using the fluid-driven crack model of Chouet (1988, 1992), we infer that two distinct cracks may have acted as sources for the LP and precursor signals. Spectral analyses of the data yield the following parameters for the LP source: crack length, 240-360 m; crack width, 130-150 m; crack aperture, 0.5-3.4 mm; crack stiffness, 100-500; sound speed of fluid, 880 m/s; and excess pressure, 0.01-0.19 MPa. Similar analyses yield the parameters of the precursor source: crack length, 20-30 m; crack width, 15-25 m; crack aperture, 2.3-8.7 mm; crack stiffness, 5-15; sound speed of fluid, 140 m/s; and excess pressure, 0.06-0.15 MPa. Combined with geologic and thermodynamic constraints obtained from field observations, these seismic parameters suggest a gas-release mechanism in which the episodic collapse of a foam layer trapped at the top of the magma column subjacent to the dome releases a slug of pressurized gas which escapes to the surface while dilating a preexisting system of cracks in the dome

  14. The Rise and Fall of the Soufriere Hills Volcano Lava Dome, Montserrat, BWI, July 2001-July 2003: Science, Hazards, and Volatile Public Perceptions

    NASA Astrophysics Data System (ADS)

    Dunkley, P.; Voight, B.; Edmonds, M.; Herd, R.; Strutt, M.; Thompson, G.; Bass, V.; Aspinall, W. P.; Neuberg, J.; Sparks, R.; Mattioli, G.; Hidayat, D.; Elsworth, D.; Widiwijayanti, C.

    2003-12-01

    Days after the major collapse (45 x 106 m3) of the eastern flank of the lava dome on 29 July 2001, new dome growth was observed within the 200-m deep collapse amphitheatre. accompanied by cyclic seismicity. By January 2002 the summit was broad with an altitude of 990m. A switch in dome activity occurred in April, but Growth nearly stagnated in June and part of July, with the top of the extrusion lobe at 1048m. but GPS monitoring suggested that the magma reservoir continued to inflate, and growth resumed in late July. In August, a lobe grew toward the north and buried the northern buttress and an important drainage channel that formerly led to the east. One of the regular six-monthly meetings of the Risk Assessment Panel (RAP) took place on 3-4 Sept 02 and concluded that if a NW switch in dome growth were to occur, the margins of the Belham Valley on the west could be at high risk; a flow and surge hazard line was provided to officials, crossing the populated area near Salem. Shortly after the RAP Report was finalized, a switch in growth direction toward the northwest in fact occurred. On 7 Oct, the RAP were asked to re-appraise Belham Valley risks given the altered but not unanticipated circumstances; they judged that a potential existed for a hazardous flow down Belham Valley, although RAP emphasized that their assessment did not predict that a large flow would occur soon, nor in that sector. On 8 Oct the Governor ordered an evacuation of an exclusion zone defined by the RAP's hazard line as adjusted to permit administrative control, and the boundary remained in force until Aug 03, with growing public discontent toward the Governor's exercise of Emergency Powers, and toward MVO, as expressed by a caustic vocal minority with provocative exacerbation by the local newspaper and some politicians. Meanwhile, dome growth continued with some switches in direction, a collapse of 5 x 106 m3 occurred eastward on 8 Dec to Spanish Point, and pyroclastic flows occurred in

  15. Compositional gradients in large reservoirs of silicic magma as evidenced by ignimbrites versus Taylor Creek Rhyolite lava domes

    NASA Astrophysics Data System (ADS)

    Duffield, Wendell A.; Ruiz, Joaquin

    1992-04-01

    The Taylor Creek Rhyolite of southwest New Mexico consists of 20 lava domes and flows that were emplaced during a period of a few thousand years or less in late Oligocene time. Including genetically associated pyroclastic deposits, which are about as voluminous as the lava domes and flows, the Taylor Creek Rhyolite represents roughly 100 km3 of magma erupted from vents distributed throughout an area of several hundred square kilometers. Major-element composition is metaluminous to weakly peraluminous high-silica rhyolite and is nearly constant throughout the lava field. The magma reservoir for the Taylor Creek Rhyolite was vertically zoned in trace elements, 87Sr/86Sr, and phenocryst abundance and size. Mean trace-element concentrations, ranges in concentrations, and element-pair correlations are similar to many subalkaline silicic ignimbrites. However, the polarity of the zonation was opposite that in reservoirs for ignimbrites, for most constituents. For example, compared to the Bishop Tuff, only 87Sr/86Sr and Sc increased upward in both reservoirs. Quite likely, a dominant but nonerupted volume of the magma reservoir for the Taylor Creek Rhyolite was zoned like that for the Bishop Tuff, whereas an erupted, few-hundred-meter-thick cap on the magma body was variably contaminated by roof rocks whose contribution to this part of the magma system moderated relatively extreme trace-element concentrations of uncontaminated Taylor Creek Rhyolite but did not change the sense of correlation for most element pairs. The contaminant probably was a Precambrian rock of broadly granitic composition and with very high 87Sr/86Sr. Although examples apparently are not yet reported in the literature, evidence for a similar thin contaminated cap on reservoirs for large-volume silicic ignimbrites may exist in the bottom few meters of ignimbrites or perhaps only in the pumice fallout that normally immediately precedes ignimbrite emplacement. 87Sr/86Sr in sanidine phenocrysts of the

  16. Compositional gradients in large reservoirs of silicic magma as evidenced by ignimbrites versus Taylor Creek Rhyolite lava domes

    USGS Publications Warehouse

    Duffield, W.A.; Ruiz, J.

    1992-01-01

    The Taylor Creek Rhyolite of southwest New Mexico consists of 20 lava domes and flows that were emplaced during a period of a few thousand years or less in late Oligocene time. Including genetically associated pyroclastic deposits, which are about as voluminous as the lava domes and flows, the Taylor Creek Rhyolite represents roughly 100 km3 of magma erupted from vents distributed throughout an area of several hundred square kilometers. Major-element composition is metaluminous to weakly peraluminous high-silica rhyolite and is nearly constant throughout the lava field. The magma reservoir for the Taylor Creek Rhyolite was vertically zoned in trace elements, 87Sr/86Sr, and phenocryst abundance and size. Mean trace-element concentrations, ranges in concentrations, and element-pair correlations are similar to many subalkaline silicic ignimbrites. However, the polarity of the zonation was opposite that in reservoirs for ignimbrites, for most constituents. For example, compared to the Bishop Tuff, only 87Sr/86Sr and Sc increased upward in both reservoirs. Quite likely, a dominant but nonerupted volume of the magma reservoir for the Taylor Creek Rhyolite was zoned like that for the Bishop Tuff, whereas an erupted, few-hundred-meter-thick cap on the magma body was variably contaminated by roof rocks whose contribution to this part of the magma system moderated relatively extreme trace-element concentrations of uncontaminated Taylor Creek Rhyolite but did not change the sense of correlation for most element pairs. The contaminant probably was a Precambrian rock of broadly granitic composition and with very high 87Sr/86Sr. Although examples apparently are not yet reported in the literature, evidence for a similar thin contaminated cap on reservoirs for large-volume silicic ignimbrites may exist in the bottom few meters of ignimbrites or perhaps only in the pumice fallout that normally immediately precedes ignimbrite emplacement. 87Sr/86Sr in sanidine phenocrysts of the

  17. Factors controlling permeability and fluid flow within the 2004-2008 Mount St Helens lava dome complex

    NASA Astrophysics Data System (ADS)

    Gaunt, H. E.; Meredith, P. G.; Sammonds, P.; Smith, R.; Kilburn, C.

    2011-12-01

    Magma degassing is an important control on whether an eruption will be explosive or effusive. Although the process of gas exsolution has been well-studied, the factors that determine how gases subsequently escape are still poorly understood, especially from high-viscosity magmas with evolved compositions, such as dacite. A preferred model for viscous magmas is that shear fracturing during ascent can occur along conduit margins and lead to the development of a permeable fracture network. Such fracture networks facilitate gas escape and the effusion of magma as a lava dome or flow. The model, however, has yet to be tested against direct laboratory measurements on the potential for magma to develop permeable networks of fractures. Between 2004 and 2008, dacite magma was extruded almost continuously from Mount St Helens (Cascade Range, USA) as a succession of gas-poor and solidified lava spines. The dacite is thought to have solidified about 1 km below the vent and to have experienced intense strain localisation at the conduit margins during ascent. The most prominent of all the spines, Spine 4, formed a smooth 'whaleback' feature and had a distinct internal structure analogous to that of a tectonic fault zone. Extruded dacite lava was coated with a thick (~1m) layer of fault gouge, containing multiple sets of sub-parallel slickensides and shear bands orientated preferentially in the direction of spine growth. To investigate the controls on degassing processes, we have measured how permeability varied progressively with increasing temperature and deformation on samples from the 2004-2008 dome at Mount St Helens. Permeability was measured on cylindrical samples, 25 mm in diameter, in a hydrostatic permeameter at confining pressures up to 30 MPa (a depth of c.1.2 km) and, also, in a high temperature deformation apparatus at temperatures up to 900oC, confining pressures of 12 MPa and pore fluid pressures of 4 MPa. Samples of intact dacite from the interior of Spine 4 were

  18. Remote camera observations of lava dome growth at Mount St. Helens, Washington, October 2004 to February 2006: Chapter 11 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Poland, Michael P.; Dzurisin, Daniel; LaHusen, Richard G.; Major, John J.; Lapcewich, Dennis; Endo, Elliot T.; Gooding, Daniel J.; Schilling, Steve P.; Janda, Christine G.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    Images from a Web-based camera (Webcam) located 8 km north of Mount St. Helens and a network of remote, telemetered digital cameras were used to observe eruptive activity at the volcano between October 2004 and February 2006. The cameras offered the advantages of low cost, low power, flexibility in deployment, and high spatial and temporal resolution. Images obtained from the cameras provided important insights into several aspects of dome extrusion, including rockfalls, lava extrusion rates, and explosive activity. Images from the remote, telemetered digital cameras were assembled into time-lapse animations of dome extrusion that supported monitoring, research, and outreach efforts. The wide-ranging utility of remote camera imagery should motivate additional work, especially to develop the three-dimensional quantitative capabilities of terrestrial camera networks.

  19. Shallow outgassing changes disrupt steady lava lake activity, Kilauea Volcano

    NASA Astrophysics Data System (ADS)

    Patrick, M. R.; Orr, T. R.; Swanson, D. A.; Lev, E.

    2015-12-01

    Persistent lava lakes are a testament to sustained magma supply and outgassing in basaltic systems, and the surface activity of lava lakes has been used to infer processes in the underlying magmatic system. At Kilauea Volcano, Hawai`i, the lava lake in Halema`uma`u Crater has been closely studied for several years with webcam imagery, geophysical, petrological and gas emission techniques. The lava lake in Halema`uma`u is now the second largest on Earth, and provides an unprecedented opportunity for detailed observations of lava lake outgassing processes. We observe that steady activity is characterized by continuous southward motion of the lake's surface and slow changes in lava level, seismic tremor and gas emissions. This normal, steady activity can be abruptly interrupted by the appearance of spattering - sometimes triggered by rockfalls - on the lake surface, which abruptly shifts the lake surface motion, lava level and gas emissions to a more variable, unstable regime. The lake commonly alternates between this a) normal, steady activity and b) unstable behavior several times per day. The spattering represents outgassing of shallowly accumulated gas in the lake. Therefore, although steady lava lake behavior at Halema`uma`u may be deeply driven by upwelling of magma, we argue that the sporadic interruptions to this behavior are the result of shallow processes occurring near the lake surface. These observations provide a cautionary note that some lava lake behavior is not representative of deep-seated processes. This behavior also highlights the complex and dynamic nature of lava lake activity.

  20. Vulcanian explosions in the process of building-destruction of the lava dome of andesitic volcano: Insight from the seismic signals recorded at Volcán de Colima, México

    NASA Astrophysics Data System (ADS)

    Zobin, Vyacheslav M.; Peral, Juan J.; Nava, Fernando; Bretón, Mauricio

    2015-07-01

    The seismic signals associated with the Vulcanian explosive events at Volcán de Colima, México during its 1998-2014 eruption were discriminated into three types according the waveforms of their initial phases. This classification includes about 85-90% of all seismic signals associated with explosive events. It was shown that the classification of the explosive seismic signals gave a useful tool for analysis of the eruption development. Analysis was performed for two 6-month stages of the eruption, the 2003 post-effusive stage culminated with large explosions and the 2007 co-effusive stage during the beginning of new lava dome growth in the crater of the volcano. The predominance (95%) of the type 1 and 3 events with low-frequency (LF) and high + low frequency (HF + LF) initial phases in the sample of the 2003 post-effusive stage explosive events identifies the termination of the lava effusion and preparation to the stage of large explosions. The high participation (37%) of the type 2 events with high-frequency (HF) initial phases in the sample of the 2007 co-effusive stage explosive events indicates the process of the lava dome growth beginning. The introduction of multi-stage conceptual model of explosive process allows the interpretation of peculiarities of the seismic signals associated with explosive activity. Analysis of the spectral content of the initial LF phases of the seismic signals associated with the explosions showed that the sources of LF initial phases, corresponding to the ascent of magma within the volcanic conduit above the fragmentation zone, were common for post-effusive and co-effusive stages. The source of events with the HF initial phases differed from the source of events with the LF first phases. The sources of explosions at explosion level were situated at different sites during post-effusive and co-effusive stages.

  1. Explosive activity associated with the growth of volcanic domes

    USGS Publications Warehouse

    Newhall, C.G.; Melson, W.G.

    1983-01-01

    Domes offer unique opportunities to measure or infer the characteristics of magmas that, at domes and elsewhere, control explosive activity. A review of explosive activity associated with historical dome growth shows that: 1. (1) explosive activity has occurred in close association with nearly all historical dome growth; 2. (2) whole-rock SiO2 content, a crude but widely reported indicator of magma viscosity, shows no systematic relationship to the timing and character of explosions; 3. (3) the average rate of dome growth, a crude indicator of the rate of supply of magma and volatiles to the near-surface enviornment, shows no systematic relationship to the timing or character of explosions; and 4. (4) new studies at Arenal and Mount St. Helens suggest that water content is the dominant control on explosions from water-rich magmas, whereas the crystal content and composition of the interstitial melt (and hence magma viscosity) are equally or more important controls on explosions from water-poor magmas. New efforts should be made to improve current, rather limited techniques for monitoring pre-eruption volatile content and magma viscosity, and thus the explosive potential of magmas. ?? 1983.

  2. Glacier melting during lava dome growth at Nevado de Toluca volcano (Mexico): Evidences of a major threat before main eruptive phases at ice-caped volcanoes

    NASA Astrophysics Data System (ADS)

    Capra, L.; Roverato, M.; Groppelli, G.; Caballero, L.; Sulpizio, R.; Norini, G.

    2015-03-01

    Nevado de Toluca volcano is one of the largest stratovolcanoes in the Trans-Mexican Volcanic Belt. During Late Pleistocene its activity was characterized by large dome growth and subsequent collapse emplacing large block and ash flow deposits, intercalated by Plinian eruptions. Morphological and paleoclimate studies at Nevado de Toluca and the surrounding area evidenced that the volcano was affected by extensive glaciation during Late Pleistocene and Holocene. During the older recognized glacial period (27-60 ka, MIS 3), the glacier was disturbed by the intense magmatic and hydrothermal activity related to two dome extrusion episodes (at 37 ka and 28 ka). Glacier reconstruction indicates maximum ice thickness of 90 m along main valleys, as at the Cano ravines, the major glacial valley on the northern slope of the volcano. Along this ravine, both 37 and 28 ka block-and-ash deposits are exposed, and they directly overlay a fluviatile sequence, up to 40 m-thick, which 14C ages clearly indicate that their emplacement occurred just before the dome collapsed. These evidences point to a clear interaction between the growing dome and its hydrothermal system with the glacier. During dome growth, a large amount of melting water was released along major glacial valleys forming thick fluvioglacial sequences that were subsequently covered by the block-and-ash flow deposits generated by the collapse of the growing dome. Even though this scenario is no longer possible at the Nevado de Toluca volcano, the data presented here indicate that special attention should be paid to the possible inundation areas from fluviatile/lahar activity prior to the main magmatic eruption at ice-capped volcanoes.

  3. Crystallization conditions and petrogenesis of the lava dome from the ˜900 years BP eruption of Cerro Machín Volcano, Colombia

    NASA Astrophysics Data System (ADS)

    Laeger, Kathrin; Halama, Ralf; Hansteen, Thor; Savov, Ivan P.; Murcia, Hugo F.; Cortés, Gloria P.; Garbe-Schönberg, Dieter

    2013-12-01

    The last known eruption at Cerro Machín Volcano (CMV) in the Central Cordillera of Colombia occurred ˜900 years BP and ended with the formation of a dacitic lava dome. The dome rocks contain both normally and reversely zoned plagioclase (An24-54), unzoned and reversely zoned amphiboles of dominantly tschermakite and pargasite/magnesio-hastingsite composition and olivine xenocrysts (Fo = 85-88) with amphibole/clinopyroxene overgrowth, all suggesting interaction with mafic magma at depth. Plagioclase additionally exhibits complex oscillatory zoning patterns reflecting repeated replenishment, fractionation and changes in intrinsic conditions in the magma reservoir. Unzoned amphiboles and cores of the reversely zoned amphiboles give identical crystallization conditions of 910 ± 30 °C and 360 ± 70 MPa, corresponding to a depth of about 13 ± 2 km, at moderately oxidized conditions (f = +0.5 ± 0.2 ΔNNO). The water content in the melt, calculated based on amphibole chemistry, is 7.1 ± 0.4 wt.%. Rims of the reversely zoned amphiboles are relatively enriched in MgO and yield higher crystallization temperatures (T = 970 ± 25 °C), slightly lower melt H2O contents (6.1 ± 0.7 wt.%) and overlapping pressures (410 ± 100 MPa). We suggest that these rims crystallized following an influx of mafic melt into a resident magma reservoir at mid-crustal depths, further supported by the occurrence of xenocrystic olivine. Crystallization of biotite, albite-rich plagioclase and quartz occurred at comparatively low temperatures (probably <800 °C) during early stages of ascent or storage at shallower levels. Based on amphibole mineral chemistry, the felsic resident melt had a rhyolitic composition (71 ± 2 wt.% SiO2), whereas the hybrid magma, from which the amphibole rims crystallized, was dacitic (64 ± 3 wt.% SiO2). The bulk rock chemistry of the CMV lava dome dacites is homogenous. They have elevated (La/Nb)N ratios of 3.8-4.5, typical for convergent margin magmas, and display

  4. Volcanic ash at Santiaguito dome complex, Guatemala

    NASA Astrophysics Data System (ADS)

    Hornby, Adrian; Kendrick, Jackie; Lavallée, Yan; Cimarelli, Corrado; von Aulock, Felix; Rhodes, Emma; Kennedy, Ben; Wadsworth, Fabian

    2015-04-01

    Dome-building volcanoes often suffer episodic explosions. Examination of eruptive activity at Santiaguito dome complex (Guatemala) reveals that gas-and-ash explosions are concordant with rapid inflation/ deflation cycles of the active dome. During these explosions strain is accommodated along marginal faults, where tensional fracture mechanisms and friction dominate, complicating the model of ash generation by bubble rupture in magma. Here, we describe textural features, morphology and petrology of ash collected before, during and after a dome collapse event at Santiaguito dome complex on the 28th November 2012. We use QEM-scan (on more than 35000 grains), laser diffraction granulometry and optical and scanning microscopy to characterise the samples. The ash samples show a bimodal size distribution and a range of textures, crystal content and morphologies. The ash particles are angular to sub-angular and are relatively dense, so do not appear to comprise of pore walls. Instead the ash is generally blocky (>70%), similar to the products of shear magma failure. The ash samples show minor variation before, during and after dome collapse, specifically having a smaller grain size and a higher fraction of phenocrysts fragments before collapse. Textural analysis shows vestiges of chemically heterogeneous glass (melt) filaments originating from the crystals and crosscut by fragmentation during volcanic ash formation. High-velocity friction can induce melting of dome lavas, producing similar disequilibrium melting textures. This work shows the importance of deformation mechanisms in ash generation at lava domes and during Vulcanian activity.

  5. Seafloor doming driven by active mantle degassing offshore Naples (Italy)

    NASA Astrophysics Data System (ADS)

    Ventura, Guido; Passaro, Salvatore; Tamburrino, Stella; Vallefuoco, Mattia; Tassi, Franco; Vaselli, Orlando; Giannini, Luciano; Caliro, Stefano; Chiodini, Giovanni; Sacchi, Marco; Rizzo, Andrea

    2016-04-01

    Structures and processes associated with shallow water hydrothermal fluid discharges on continental shelves are poorly known. We report geomorphological, geophysical, and geochemical evidences of a 5.5 x 5.3 km seabed doming located 5 km offshore the Naples harbor (Italy). The dome lies between 100 and 170 m of water depth and it is 15-20 m higher than the surrounding seafloor. It is characterized by a hummocky morphology due to 280 sub-circular to elliptical mounds, about 660 cones, and 30 pockmarks. The mounds and pockmarks alignments follow those of the main structural discontinuity affecting the Gulf of Naples. The seafloor swelling and breaching require relatively low pressures (about 2-3 MPa), and the sub-seafloor structures, which consists of 'pagodas' affecting the present-day seabed, record the active upraise, pressurization, and release of magmatic fluids. The gas composition of the sampled submarine emissions is consistent with that of the emissions from the hydrothermal systems of Ischia, CampiFlegrei and Somma-Vesuvius active volcanoes, and CO2 has a magmatic/thermometamorphic origin. The 3He/4He ratios (1.66-1.96 Ra) are slightly lower than in the Somma-Vesuvius and Campi Flegrei volcanoes (~2.6-3.0 Ra) indicating the contamination of fluids originated from the same magmatic source by crustal-derived radiogenic 4He. All these evidences concur to hypothesize an extended magmatic reservoir beneath Naples and its offshore. Seabed doming, faulting, and hydrothermal discharges are manifestations of non-volcanic unrests potentially preluding submarine eruptions and/or hydrothermal explosions. We conclude that seabed deformations and hydrothermal discharge must be included in the coastal hazard studies.

  6. Effects of lava-dome growth on the crater glacier of Mount St. Helens, Washington: Chapter 13 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Walder, Joseph S.; Schilling, Steve P.; Vallance, James W.; LaHusen, Richard G.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    The process of lava-dome emplacement through a glacier was observed for the first time as the 2004-6 eruption of Mount St. Helens proceeded. The glacier that had grown in the crater since the cataclysmic 1980 eruption was split in two by the new lava dome. The two parts of the glacier were successively squeezed against the crater wall. Photography, photogrammetry, and geodetic measurements document glacier deformation of an extreme variety, with strain rates of extraordinary magnitude as compared to normal temperate alpine glaciers. Unlike such glaciers, the Mount St. Helens crater glacier shows no evidence of either speed-up at the beginning of the ablation season or diurnal speed fluctuations during the ablation season. Thus there is evidently no slip of the glacier over its bed. The most reasonable explanation for this anomaly is that meltwater penetrating the glacier is captured by a thick layer of coarse rubble at the bed and then enters the volcano’s groundwater system rather than flowing through a drainage network along the bed. Mechanical consideration of the glacier-squeeze process also leads to an estimate for the driving pressure applied by the growing lava dome.

  7. Discrete Slip, Amorphous Silica and Pore Structure of Slickensided Gouge Layers in 2004-2006 Mt. St. Helens Lava Domes

    NASA Astrophysics Data System (ADS)

    White, J. C.; Kennedy, L. A.; Russell, J. K.; Friedlander, B.

    2012-12-01

    Spines of dacite lava formed during the 2004-2006 Mt. St. Helens (MSH) effusion event are enveloped by extrusion gouges created during upward movement of crystallized magma. Multiple slickenside sets form one of the most distinctive feature types within this gouge carapace. Macroscopically, slickenside surfaces are seen to be composite features composed of discrete slip surfaces in Y- and R-shear orientations. In general, the spacing between the slip surfaces decreases toward the outer, exposed slickensided surface until they appear to coalesce. Slickensides are formed in association with all MSH spines, unlike some other fault rock fabrics within the gouge; therefore, their morphology can be inferred to be independent of syn-faulting residence time. As a significant record of the extrusion process, the MSH slickensides have been characterized by analytical scanning/transmission electron microscopy (STEM) to elucidate the mechanisms of energy dissipation and material transport. At the scale of these observations, the individual surfaces within a slickenside set comprise comminution bands (10-20 μm wide), each bounded by a discrete slip surface. The internal structure of these shear bands consists of a consistent sense of decreasing grain size toward the slip surface away and away from the spire core; grain size is routinely less than 100nm within the bands. The 1-5 μm wide slip layers that bound comminution bands are variously composed of amorphous silica or polycrystalline aggregates of sub-100nm grain size plagioclase, k-feldspar and quartz. Grain aggregates in the slip layer form an extended fabric parallel to the displacement direction, creating a "flow" foliation at edges of the shears. Specific to the slip bands are nano-scale pores, often silica-filled, whose circular cross-sections indicate the presence of fluids throughout slickenside formation. It is contended that the development of discrete slip surfaces is consistent with formation of the gouge by

  8. Observations of actively forming lava tubes and associated structures, Hawaii.

    NASA Technical Reports Server (NTRS)

    Greeley, R.

    1971-01-01

    Fluid basalts were erupted in August, 1970, from a vent near Alae Crater and flowed southeast. Forming exclusively in pahoehoe basalt, tubes in general evolve from lava channels by crustal formation, although some tubes develop directly from the vent. The observation discussed shows that channel crusts and tube roofs form in several ways. Lava channels usually form along the axis of highest velocity within the flow and are often centered along older lava channels, stream beds, rifts, grabens, or fracture zones.

  9. Observations of actively forming lava tubes and associated structures, Hawaii, part 2

    NASA Technical Reports Server (NTRS)

    Greeley, R.

    1971-01-01

    A ground examination is made of lave tubes and channels. The surface morphology and the changes noted through lava flow activity are cited, and compared to earlier aerial observations. The lava activity was believed to be caused by a small lava lake exposed by the collapse of a crust covering it. Drainage of the lake was caused by a fissure erruption. New tubes or extensions of existing ones were noted from the flow. Molten lava was not seen in any tubes examined on the ground, but some of the flows were not sufficiently cooled to allow subsurface examination and survey of the tubes.

  10. Using thermal remanent magnetisation (TRM) to distinguish block and ash flow and debris flow deposits, and to estimate their emplacement temperature: 1991-1995 lava dome eruption at Mt. Unzen Volcano, Japan

    NASA Astrophysics Data System (ADS)

    Uehara, D.; Cas, R. A. F.; Folkes, C.; Takarada, S.; Oda, H.; Porreca, M.

    2015-09-01

    The 1991-1995 Mt. Unzen eruption (Kyushu, Japan) produced 13 lava domes, approximately 9400 block and ash pyroclastic flows (BAF) resulting from lava dome collapse events and syn- and post-dome collapse debris flow (DF) events. In the field, it can be very difficult to distinguish from field facies characteristics which deposits are primary hot BAF, cold BAF or rock avalanche, or secondary DF deposits. In this study we use a combination of field observations and thermal remanent magnetisation (TRM) analysis of juvenile, lava dome derived clasts from seven deposits of the 1991-1995 Mt. Unzen eruption in order to distinguish between primary BAF deposits and secondary DF deposits and to determine their emplacement temperature. Four major TRM patterns were identified: (1) Type I: clasts with a single magnetic component oriented parallel to the Earth's magnetic field at time and site of emplacement. This indicates that these deposits were deposited at very high temperature, between the Curie temperature of magnetite (~ 540 °C) and the glass transition temperature of the lava dome (~ 745 °C). These clasts are found in high temperature BAF deposits. (2) Type II: clasts with two magnetic components of magnetisation. The lower temperature magnetic components are parallel to the Earth's magnetic field at time of the Unzen eruption. Temperature estimations for these deposits can range from 80 to 540 °C. We found this paleomagnetic behaviour in moderate temperature BAF or warm DF deposits. (3) Type III: clasts with three magnetic components, with a lower temperature component oriented parallel to the Earth's magnetic field at Unzen. The individual clast temperatures estimated for this kind of deposit are usually less than 300 °C. We interpret this paleomagnetic behaviour as the effect of different thermal events during their emplacement history. There are several interpretations for this paleomagnetic behaviour including remobilisation of moderate temperature BAF, warm DF

  11. Dome growth at Mount Cleveland, Aleutian Arc, quantified by time-series TerraSAR-X imagery

    USGS Publications Warehouse

    Wang, Teng; Poland, Michael; Lu, Zhong

    2016-01-01

    Synthetic aperture radar imagery is widely used to study surface deformation induced by volcanic activity; however, it is rarely applied to quantify the evolution of lava domes, which is important for understanding hazards and magmatic system characteristics. We studied dome formation associated with eruptive activity at Mount Cleveland, Aleutian Volcanic Arc, in 2011–2012 using TerraSAR-X imagery. Interferometry and offset tracking show no consistent deformation and only motion of the crater rim, suggesting that ascending magma may pass through a preexisting conduit system without causing appreciable surface deformation. Amplitude imagery has proven useful for quantifying rates of vertical and areal growth of the lava dome within the crater from formation to removal by explosive activity to rebirth. We expect that this approach can be applied at other volcanoes that host growing lava domes and where hazards are highly dependent on dome geometry and growth rates.

  12. A comparative Study of Circulation Patterns at Active Lava Lakes

    NASA Astrophysics Data System (ADS)

    Lev, Einat; Oppenheimer, Clive; Spampinato, Letizia; Hernandez, Pedro; Unglert, Kathi

    2016-04-01

    Lava lakes present a rare opportunity to study magma dynamics in a large scaled-up "crucible" and provide a unique natural laboratory to ground-truth dynamic models of magma circulation. The persistence of lava lakes allows for long-term observations of flow dynamics and of lava properties, especially compared to surface lava flows. There are currently five persistent lava lakes in the world: Halemaumau in Kilauea (Hawaii, USA), Erta Ale (Ethiopia), Nyiragongo (Congo), Erebus (Antarctica), and Villarica (Chile). Marum and Benbow craters of Ambrym volcano (Vanuatu) and Masaya (Nicaragua) have often hosted lava lakes as well. We use visible-light and thermal infrared time-lapse and video footage collected at all above lakes (except Villarica, where the lake is difficult to observe), and compare the circulation patterns recorded. We calculate lake surface motion from the footage using the optical flow method (Lev et al., 2012) to produce 2D velocity fields. We mined both the surface temperature field and the surface velocity field for patterns using machine learning techniques such as "self-organizing maps (SOMs)" and "principle component analysis (PCA)". We use automatic detection technique to study the configuration of crustal plates at the lakes' surface. We find striking differences among the lakes, in flow direction, flow speed, frequency of changes in flow direction and speed, location and consistency of upwelling and downwelling, and crustal plate configuration. We relate the differences to lake size, shallow conduit geometry, lava viscosity, crystal and gas content, and crust integrity.

  13. A history of semi-active laser dome and window materials

    NASA Astrophysics Data System (ADS)

    Sullivan, Roger M.

    2014-05-01

    Semi-Active Laser (SAL) guidance systems were developed starting in the mid-1960's and today form an important class of precision guided weapons. The laser wavelengths generally fall in the short wave infrared region of the spectrum. Relative to passive, image based, infrared seekers the optical demands placed on the domes or windows of SAL seekers is very modest, allowing the use of low cost, easily manufactured materials, such as polycarbonate. This paper will examine the transition of SAL window and dome science and technology from the laboratory to battlefield, with special emphasis on the story of polycarbonate domes.

  14. Estimating eruption temperature from thermal emission spectra of lava fountain activity in the Erta'Ale (Ethiopia) volcano lava lake: Implications for observing Io's volcanoes

    USGS Publications Warehouse

    Davies, A.G.; Keszthelyi, L.; McEwen, A.S.

    2011-01-01

    We have analysed high-spatial-resolution and high-temporal-resolution temperature measurements of the active lava lake at Erta'Ale volcano, Ethiopia, to derive requirements for measuring eruption temperatures at Io's volcanoes. Lava lakes are particularly attractive targets because they are persistent in activity and large, often with ongoing lava fountain activity that exposes lava at near-eruption temperature. Using infrared thermography, we find that extracting useful temperature estimates from remote-sensing data requires (a) high spatial resolution to isolate lava fountains from adjacent cooler lava and (b) rapid acquisition of multi-color data. Because existing spacecraft data of Io's volcanoes do not meet these criteria, it is particularly important to design future instruments so that they will be able to collect such data. Near-simultaneous data at more than two relatively short wavelengths (shorter than 1 ??m) are needed to constrain eruption temperatures. Resolving parts of the lava lake or fountains that are near the eruption temperature is also essential, and we provide a rough estimate of the required image scale. ?? 2011 by the American Geophysical Union.

  15. Estimating eruption temperature from thermal emission spectra of lava fountain activity in the Erta'Ale (Ethiopia) volcano lava lake: Implications for observing Io's volcanoes

    USGS Publications Warehouse

    Davies, Ashley G.; Keszthelyi, Laszlo P.; McEwen, Alfred S.

    2011-01-01

    We have analysed high-spatial-resolution and high-temporal-resolution temperature measurements of the active lava lake at Erta'Ale volcano, Ethiopia, to derive requirements for measuring eruption temperatures at Io's volcanoes. Lava lakes are particularly attractive targets because they are persistent in activity and large, often with ongoing lava fountain activity that exposes lava at near-eruption temperature. Using infrared thermography, we find that extracting useful temperature estimates from remote-sensing data requires (a) high spatial resolution to isolate lava fountains from adjacent cooler lava and (b) rapid acquisition of multi-color data. Because existing spacecraft data of Io's volcanoes do not meet these criteria, it is particularly important to design future instruments so that they will be able to collect such data. Near-simultaneous data at more than two relatively short wavelengths (shorter than 1 μm) are needed to constrain eruption temperatures. Resolving parts of the lava lake or fountains that are near the eruption temperature is also essential, and we provide a rough estimate of the required image scale.

  16. A Sinuous Tumulus over an Active Lava Tube at Klauea Volcano: Evolution, Analogs, and Hazard Forecasts

    NASA Technical Reports Server (NTRS)

    Orr, Tim R.; Bleacher, Jacob E.; Patrick, Matthew R.; Wooten, Kelly M.

    2015-01-01

    Inflation of narrow tube-fed basaltic lava flows (tens of meters across), such as those confined by topography, can be focused predominantly along the roof of a lava tube. This can lead to the development of an unusually long tumulus, its shape matching the sinuosity of the underlying lava tube. Such a situation occurred during Klauea Volcanos (Hawaii, USA) ongoing East Rift Zone eruption on a lava tube active from July through November 2010. Short-lived breakouts from the tube buried the flanks of the sinuous, ridge-like tumulus, while the tumulus crest, its surface composed of lava formed very early in the flows emplacement history, remained poised above the surrounding younger flows. At least several of these breakouts resulted in irrecoverable uplift of the tube roof. Confined sections of the prehistoric Carrizozo and McCartys flows (New Mexico, USA) display similar sinuous, ridge-like features with comparable surface age relationships. We contend that these distinct features formed in a fashion equivalent to that of the sinuous tumulus that formed at Kilauea in 2010. Moreover, these sinuous tumuli may be analogs for some sinuous ridges evident in orbital images of the Tharsis volcanic province on Mars. The short-lived breakouts from the sinuous tumulus at Kilauea were caused by surges in discharge through the lava tube, in response to cycles of deflation and inflation (DI events) at Kilauea's summit. The correlation between DI events and subsequent breakouts aided in lava flow forecasting. Breakouts from the sinuous tumulus advanced repeatedly toward the sparsely populated Kalapana Gardens subdivision, destroying two homes and threatening others. Hazard assessments, including flow occurrence and advance forecasts, were relayed regularly to the Hawai?i County Civil Defense to aid their lava flow hazard mitigation efforts while this lava tube was active.

  17. Three-dimensional representations of salt-dome margins at four active strategic petroleum reserve sites.

    SciTech Connect

    Rautman, Christopher Arthur; Stein, Joshua S.

    2003-01-01

    Existing paper-based site characterization models of salt domes at the four active U.S. Strategic Petroleum Reserve sites have been converted to digital format and visualized using modern computer software. The four sites are the Bayou Choctaw dome in Iberville Parish, Louisiana; the Big Hill dome in Jefferson County, Texas; the Bryan Mound dome in Brazoria County, Texas; and the West Hackberry dome in Cameron Parish, Louisiana. A new modeling algorithm has been developed to overcome limitations of many standard geological modeling software packages in order to deal with structurally overhanging salt margins that are typical of many salt domes. This algorithm, and the implementing computer program, make use of the existing interpretive modeling conducted manually using professional geological judgement and presented in two dimensions in the original site characterization reports as structure contour maps on the top of salt. The algorithm makes use of concepts of finite-element meshes of general engineering usage. Although the specific implementation of the algorithm described in this report and the resulting output files are tailored to the modeling and visualization software used to construct the figures contained herein, the algorithm itself is generic and other implementations and output formats are possible. The graphical visualizations of the salt domes at the four Strategic Petroleum Reserve sites are believed to be major improvements over the previously available two-dimensional representations of the domes via conventional geologic drawings (cross sections and contour maps). Additionally, the numerical mesh files produced by this modeling activity are available for import into and display by other software routines. The mesh data are not explicitly tabulated in this report; however an electronic version in simple ASCII format is included on a PC-based compact disk.

  18. Analysis of Active Lava Flows on Kilauea Volcano, Hawaii, Using SIR-C Radar Correlation Measurements

    NASA Technical Reports Server (NTRS)

    Zebker, H. A.; Rosen, P.; Hensley, S.; Mouginis-Mark, P. J.

    1995-01-01

    Precise eruption rates of active pahoehoe lava flows on Kilauea volcano, Hawaii, have been determined using spaceborne radar data acquired by the Space Shuttle Imaging Radar-C (SIR-C). Measurement of the rate of lava flow advance, and the determination of the volume of new material erupted in a given period of time, are among the most important observations that can be made when studying a volcano.

  19. Extrusion rate of the Mount St. Helens lava dome estimated from terrestrial imagery, November 2004-December 2005: Chapter 12 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Major, Jon J.; Kingsbury, Cole G.; Poland, Michael P.; LaHusen, Richard G.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    Oblique, terrestrial imagery from a single, fixed-position camera was used to estimate linear extrusion rates during sustained exogenous growth of the Mount St. Helens lava dome from November 2004 through December 2005. During that 14-month period, extrusion rates declined logarithmically from about 8-10 m/d to about 2 m/d. The overall ebbing of effusive output was punctuated, however, by episodes of fluctuating extrusion rates that varied on scales of days to weeks. The overall decline of effusive output and finer scale rate fluctuations correlated approximately with trends in seismicity and deformation. Those correlations portray an extrusion that underwent episodic, broad-scale stick-slip behavior superposed on the finer scale, smaller magnitude stick-slip behavior that has been hypothesized by other researchers to correlate with repetitive, nearly periodic shallow earthquakes.

  20. "Active" and "Passive" Lava Resurfacing Processes on Io: A Comparative Study of Loki Patera and Prometheus

    NASA Technical Reports Server (NTRS)

    Davies, A. G.; Matson, D. L.; Leone, G.; Wilson, L.; Keszthelyi, L. P.

    2004-01-01

    Studies of Galileo Near Infrared Mapping Spectrometer (NIMS) data and ground based data of volcanism at Prometheus and Loki Patera on Io reveal very different mechanisms of lava emplacement at these two volcanoes. Data analyses show that the periodic nature of Loki Patera s volcanism from 1990 to 2001 is strong evidence that Loki s resurfacing over this period resulted from the foundering of a crust on a lava lake. This process is designated passive , as there is no reliance on sub-surface processes: the foundering of the crust is inevitable. Prometheus, on the other hand, displays an episodicity in its activity which we designate active . Like Kilauea, a close analog, Prometheus s effusive volcanism is dominated by pulses of magma through the nearsurface plumbing system. Each system affords views of lava resurfacing processes through modelling.

  1. FAMoUS goes to Guatemala: Integrated thermal and high-speed imaging of explosive activity at Santiaguito dome and Volcan de Fuego

    NASA Astrophysics Data System (ADS)

    Scarlato, P.; Andronico, D.; Cimarelli, C.; Del Bello, E.; Taddeucci, J.; Johnson, J. B.

    2012-04-01

    The combined use of high-speed visible and infrared cameras is a novel technique capable of unparalleled resolution of different eruptive processes at different time and space scales. In January 2012, a field campaign to Guatemala has been carried out to study the current activity of Santiaguito and Fuego, two of the most active volcanoes of the world, showing different eruptive styles. While Santiaguito was approached by a multiparametric experiment combining also tilt, seismo-acoustic and photogrammetric monitoring (see expedition account at http://expedicionsantiaguito.blogspot.com/), at Fuego only the FAMoUS (Fast MoUltiparametric Setup) equipment has been deployed. The equipment comprises a synchronised high-speed infrared (FLIR SC645) and visible range (Optronis) cameras acquiring images at 100-200 and 500 fps, respectively, and two microphones. A GPS receiver allowed the synchronisation of the acquired data with other installed monitoring systems. At Santiaguito dome the activity was characterised by the production of highly viscous lavas flows and coulée venting from the dome's summit, rolling of (incandescent and not) metric-sized blocks and eventually block and ash flows, accompanied by intermittent summit explosions. These latter occurred from eruptive fissures which were oriented according to the local stress field at the top of the dome. Continuous recordings and observation during four days of activity from a distance of ca. 2.5 km and ca. 1.2 km above, remarkably revealed that i) two geometrically-distinct systems of fractures are periodically and sequentially activated: one controlled by the flow field at the upheaved lava tumuli at the summit, and a second system marking the rim between the issuing lavas and the confining wall rocks; ii) tilt inflation/deflation cycles occurr with about 20 minute periods; iii) recurring explosions (ca. 20 minutes to 2 hours) cause gas- and ash-emission streaming through the two fracture systems eventually ejecting

  2. The ongoing dome emplacement and destruction cyclic process at Popocatépetl volcano, Central Mexico

    NASA Astrophysics Data System (ADS)

    Gómez-Vazquez, Angel; De la Cruz-Reyna, Servando; Mendoza-Rosas, Ana Teresa

    2016-09-01

    The ongoing eruptive activity of Popocatépetl volcano has been characterized by emplacement and subsequent destruction of a succession of lava domes. Between the onset of the current eruption in 1994 and the time of this submission, 38 episodes of lava dome formation and removal have been identified. Each dome has showed particular features related to the magma extrusion process. Among other manifestations, dome-emplacement events have been usually accompanied by relatively low-intensity, protracted explosions referred to as exhalations. After variable times of residence, emplacements have ended in partial or total destruction of the domes by strong vulcanian explosions that produced sizeable ash plumes, with most of them also ejecting incandescent debris onto the volcano flanks. Here, we present a detailed account for the observed activity related to the domes' growth and destruction, related seismic monitoring signals, and morphological features of the domes based on 19 years of visual observations and image analysis. We then discuss a model for the process of dome growth and destruction and its hazard implications.

  3. Additional Observations of Actively Forming Lava Tubes and Associated Structures, Hawaii

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald

    1972-01-01

    Extensive changes occurred after the initial observations (Greeley, 1971) of lava tube and channel formation associated with the eruption of Mauna Ulu. Individual vents, which apparently acted somewhat independently, merged by collapse of intervening sections to form an elongate trench. Lava erupted from the summit vent flowed down the trench to the lower end and drained through lava tubes into Alae lava lake. Alae lava lake is in turn drained occasionally by other lava tubes and lava tube networks.

  4. Idunn Mons on Venus: Location and extent of recently active lava flows

    NASA Astrophysics Data System (ADS)

    D'Incecco, Piero; Müller, Nils; Helbert, Jörn; D'Amore, Mario

    2017-02-01

    From 2006 until 2014 the ESA Venus Express probe observed the atmosphere and surface of the Earth's twin planet. The Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) has provided data that indicate the occurrence of recent volcanic activity on Venus. We selected the eastern flank of Idunn Mons - Imdr Regio's single large volcano - as the study area, since it was identified in VIRTIS data as one of the regions with relatively high values of thermal emissivity at 1 μm wavelength. Using the capabilities of specific techniques developed in the Planetary Emissivity Laboratory group at DLR in Berlin, our study intends to identify location and extent of the sources of such anomalies, thus the lava flows responsible for the relatively high emissivity observed by VIRTIS over the eastern flank of Idunn Mons. We map the lava flow units on the top and eastern flank of Idunn Mons, varying the values of simulated 1 μm emissivity assigned to the mapped units. For each configuration we calculate the total RMS error in comparison with the VIRTIS observations. In the best-fit configuration, the flank lava flows are characterized by high values of 1 μm simulated emissivity. Hence, the lava flow units on the eastern flank on Idunn Mons are likely responsible for the relatively high 1 μm emissivity anomalies observed by VIRTIS. This result is supported by the reconstructed post-eruption stratigraphy, displaying the relative dating of the mapped lava flows, that is independent of the 1 μm emissivity modeling. Values of average microwave emissivity extracted from the lava flow units range around the global mean, which is consistent with dry basalts.

  5. Volcanic gas emissions during active dome growth at Mount Cleveland, Alaska, August 2015

    NASA Astrophysics Data System (ADS)

    Werner, Cynthia; Kern, Christoph; Lyons, John; Kelly, Peter; Schneider, David; Wallace, Kristi; Wessels, Rick

    2016-04-01

    Volcanic gas emissions and chemistry data were measured for the first time at Mount Cleveland (1730 m) in the Central Aleutian arc, Alaska, on August 14-15, 2015 as part of the NSF-GeoPRISMS initiative, and co-funded by the Deep Carbon Observatory (DCO) and the USGS Alaska Volcano Observatory. The measurements were made in the month following two explosive events (July 21 and August 7, 2015) that destroyed a small dome (˜50x85 m), which had experienced episodic growth in the crater since November, 2014. These explosions resulted in the elevation of the aviation color code and alert level from Yellow/Advisory to Orange/Watch on July 21, 2015. Between the November, 2014 and July, 2015 dome-destroying explosions, the volcano experienced: (1) frequent periods of elevated surface temperatures in the summit region (based on Mid-IR satellite observations), (2) limited volcano-seismic tremor, (3) visible degassing as recorded in webcam images with occasionally robust plumes, and (4) at least one aseismic volcanic event that deposited small amounts of ash on the upper flanks of the volcano (detected by infrasound, observed visually and in Landsat 8 images). Intermittent plumes were also sometimes detectable up to 60 km downwind in Mid-IR satellite images, but this was not typical. Lava extrusion resumed following the explosion as indicated in satellite data by highly elevated Mid-IR surface temperatures, but was not identifiable in seismic data. By early-mid August, 2015, a new dome growing in the summit crater had reached 80 m across with temperatures of 550-600 C as measured on August 4 with a helicopter-borne thermal IR camera. A semitransparent plume extended several kilometers downwind of the volcano during the field campaign. A helicopter instrumented with an upward-looking UV spectrometer (mini DOAS) and a Multi-GAS was used to measure SO2 emission rates and in situ mixing ratios of H2O, CO2, SO2, and H2S in the plume. On August 14 and 15, 2015, a total of 14

  6. Submarine Analogs to Venusian Pancake Domes

    NASA Technical Reports Server (NTRS)

    Bridges, Nathan T.

    1995-01-01

    The morphology and dimensions of the large diameter, steep-sided, flat-topped "pancake domes" on Venus make them unlike any type of terrestrial subaerial volcano. Comparisons between images of Hawaiian seamounts and pancake domes show similarities in shapes and secondary features. The morphometry of pancake domes is closer to that of Pacific seamounts than subaerial lava domes. Considering both morphology and morphometry, seamounts seem a better analog to the pancake domes. The control of volatile exsolution by pressure on Venus and the seafloor can cause lavas to have similar viscosities and densities, although the latter will be counteracted by high buoyancy underwater. However, analogous effects of the Venusian and seafloor alone are probably not sufficient to produce similar volcanoes. Rather, Venusian lavas of various compositions may behave like basalt on the seafloor if appropriate rates and modes of extrusion and planetary thermal structure are also considered.

  7. Petrology of the 2004-2006 Mount St. Helens lava dome -- implications for magmatic plumbing and eruption triggering: Chapter 30 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Pallister, John S.; Thornber, Carl R.; Cashman, Katharine V.; Clynne, Michael A.; Lowers, Heather; Mandeville, Charles W.; Brownfield, Isabelle K.; Meeker, Gregory P.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    The question of new versus residual magma has implications for the long-term eruptive behavior of Mount St. Helens, because arrival of a new batch of dacitic magma from the deep crust could herald the beginning of a new long-term cycle of eruptive activity. It is also important to our understanding of what triggered the eruption and its future course. Two hypotheses for triggering are considered: (1) top-down fracturing related to the shallow groundwater system and (2) an increase in reservoir pressure brought about by recent magmatic replenishment. With respect to the future course of the eruption, similarities between textures and character of eruption of the 2004-6 dome and the long-duration (greater than 100 years) pre-1980 summit dome, along with the low eruptive rate of the current eruption, suggest that the eruption could continue sluggishly or intermittently for years to come.

  8. DomeHaz, a Global Hazards Database: Understanding Cyclic Dome-forming Eruptions, Contributions to Hazard Assessments, and Potential for Future Use and Integration with Existing Cyberinfrastructure

    NASA Astrophysics Data System (ADS)

    Ogburn, S. E.; Calder, E.; Loughlin, S.

    2013-12-01

    Dome-forming eruptions can extend for significant periods of time and can be dangerous; nearly all dome-forming eruptions have been associated with some level of explosive activity. Large Plinian explosions with a VEI ≥ 4 sometimes occur in association with dome-forming eruptions. Many of the most significant volcanic events of recent history are in this category. The 1902-1905 eruption of Mt. Pelée, Martinique; the 1980-1986 eruption of Mount St. Helens, USA; and the 1991 eruption of Mt. Pinatubo, Philippines all demonstrate the destructive power of VEI ≥ 4 dome-forming eruptions. Global historical analysis is a powerful tool for decision-making as well as for scientific discovery. In the absence of monitoring data or a knowledge of a volcano's eruptive history, global analysis can provide a method of understanding what might be expected based on similar eruptions. This study investigates the relationship between large explosive eruptions and lava dome growth and develops DomeHaz, a global database of dome-forming eruptions from 1000 AD to present. It is currently hosted on VHub (https://vhub.org/groups/domedatabase/), a community cyberinfrastructure for sharing data, collaborating, and modeling. DomeHaz contains information about 367 dome-forming episodes, including duration of dome growth, duration of pauses in extrusion, extrusion rates, and the timing and magnitude of associated explosions. Data sources include the The Smithsonian Institution Global Volcanism Program (GVP), Bulletin of the Global Volcanism Network, and all relevant published review papers, research papers, and reports. This database builds upon previous work (e.g Newhall and Melson, 1983) in light of newly available data for lava dome eruptions. There have been 46 new dome-forming eruptions, 13 eruptions that continued past 1982, 151 new dome-growth episodes, and 8 VEI ≥ 4 events since Newhall and Melson's work in 1983. Analysis using DomeHaz provides useful information regarding the

  9. The lunar Gruithuisen silicic extrusive domes: Topographic configuration, morphology, ages, and internal structure

    NASA Astrophysics Data System (ADS)

    Ivanov, M. A.; Head, J. W.; Bystrov, A.

    2016-07-01

    alternated with possible explosive activity (fine-grained materials). The spatial association of the Gruithuisen domes with the highland lava plains resembles the situation in which bimodal volcanism occur on Earth. The terrestrial association can be due to either fractional crystallization in basaltic magma reservoirs or remelting of high-silica crustal materials. In the first case, the evolved melts appear in later stages of volcanic activity and in the second case these melts are formed near the beginning of evolution of the magmatic systems. The age estimates of the Gruithuisen domes and the surrounding volcanic plains are more consistent with the crustal remelting scenario. However, remelting of primary anorthositic crust cannot readily produce the silica-rich melts and requires the presence of pre-existing granite-like materials. Formation of the domes by fractional crystallization avoids this difficulty but requires explanation of the older age of the domes relative to the volcanic plains in the surroundings. A third option is that the domes are unrelated genetically to the mare deposits.

  10. Autonomous thermal camera system for monitoring the active lava lake at Erebus volcano, Antarctica

    NASA Astrophysics Data System (ADS)

    Peters, N.; Oppenheimer, C.; Kyle, P.

    2014-02-01

    In December 2012, the Mount Erebus Volcano Observatory installed a thermal infrared camera system to monitor the volcano's active lava lake. The new system is designed to be autonomous, and capable of capturing images of the lava lake continuously throughout the year. This represents a significant improvement over previous systems which required the frequent attention of observatory researchers and could therefore only be operated during a few weeks of the annual field campaigns. The extreme environmental conditions at the summit of Erebus pose significant challenges for continuous monitoring equipment, and a custom-made system was the only viable solution. Here we describe the hardware and software of the new system in detail and report on a publicly available online repository where data will be archived. Aspects of the technical solutions we had to find in order to overcome the challenges of automating this equipment may be relevant in other environmental science domains where remote instrument operation is involved.

  11. Autonomous thermal camera system for monitoring the active lava lake at Erebus volcano, Antarctica

    NASA Astrophysics Data System (ADS)

    Peters, N.; Oppenheimer, C.; Kyle, P.

    2013-10-01

    In December 2012, the Mount Erebus Volcano Observatory installed a thermal infrared camera system to monitor the volcano's active lava lake. The new system is designed to be autonomous, and capable of capturing images of the lava lake continuously throughout the year. This represents a significant improvement over previous systems which required the frequent attention of observatory researchers and could therefore only be operated during a few weeks of the annual field campaigns. The extreme environmental conditions at the summit of Erebus pose significant challenges for continuous monitoring equipment, and a custom made system was the only viable solution. Here we describe the hardware and software of the new system in detail and report on a publicly-available online repository where data will be archived. Aspects of the technical solutions we had to find in order to overcome the challenges of automating this equipment may be relevant in other environmental science domains where remote instrument operation is involved.

  12. Observations of the effect of wind on the cooling of active lava flows

    USGS Publications Warehouse

    Keszthelyi, L.; Harris, A.J.L.; Dehn, J.

    2003-01-01

    We present the first direct observations of the cooling of active lava flows by the wind. We confirm that atmospheric convective cooling processes (i.e., the wind) dominate heat loss over the lifetime of a typical pahochoe lava flow. In fact, the heat extracted by convection is greater than predicted, especially at wind speeds less than 5 m/s and surface temperatures less than 400??C. We currently estimate that the atmospheric heat transfer coefficient is about 45-50 W m-2 K-1 for a 10 m/s wind and a surface temperature ???500??C. Further field experiments and theoretical studies should expand these results to a broader range of surface temperatures and wind speeds.

  13. Constraints on Determining the Eruption Style and Composition of Terrestrial Lavas from Space

    NASA Technical Reports Server (NTRS)

    Wright, Robert; Glaze, Lori; Baloga, Stephen M.

    2011-01-01

    The surface temperatures of active lavas relate to cooling rates, chemistry, and eruption style. We analyzed 61 hyperspectral satellite images acquired by the National Aeronautics and Space Administration s Earth Observing-1 (EO-1) Hyperion imaging spectrometer to document the surface temperature distributions of active lavas erupted at 13 volcanoes. Images were selected to encompass the range of common lava eruption styles, specifically, lava fountains, flows, lakes, and domes. Our results reveal temperature distributions for terrestrial lavas that correlate with composition (i.e., a statistically significant difference in the highest temperatures retrieved for mafic lavas and intermediate and felsic lavas) and eruption style. Maximum temperatures observed for mafi c lavas are approx.200 C higher than for intermediate and felsic lavas. All eruption styles exhibit a low-temperature mode at approx.300 C; lava fountains and 'a' a flows also exhibit a higher-temperature mode at approx.700 C. The observed differences between the temperatures are consistent with the contrasting rates at which the lava surfaces are thermally renewed. Eruption styles that allow persistent and pervasive thermal renewal of the lava surface (e.g., fractured crusts on channel-fed 'a' a flows) exhibit a bimodal temperature distribution; eruption styles that do not (e.g., the continuous skin of pahoehoe lavas) exhibit a single mode. We conclude that insights into composition and eruption style can only be gained remotely by analyzing a large spatio-temporal sample of data. This has implications for determining composition and eruption style at the Jovian moon Io, for which no in situ validation is available.

  14. Dome Schools.

    ERIC Educational Resources Information Center

    Cirulli, Carol

    1999-01-01

    Back in 1988, Emmett, Idaho, built the first monolithic dome school. Now, school boards in Arizona, Missouri, Florida, Minnesota, and New Mexico are among those that have voted to build domed school buildings. A monolithic dome is a steel- reinforced, concrete structure with a smooth, round surface that is inspired by the shape of an egg. (MLF)

  15. A Model for Variable Levee Formation Rates in an Active Lava Flow

    NASA Technical Reports Server (NTRS)

    Glaze, L. S.; Baloga, S. M.; Mouginis-Mark, P.; Crisp, J.

    2004-01-01

    Channelized lava flows on Mars and the Earth often feature levees and collateral margins that change in volume along the path of the flow. Consistent with field observations of terrestrial flows, this suggests that the rate of levee formation varies with distance and other factors. Previous models have assumed a constant rate of levee growth, specified by a single parameter, lambda. The rate of levee formation for lava flows is a good indicator of the mass eruption rate and rheology of the flow. Insight into levee formation will help us better understand whether or not the effusion rate was constant during an eruption, and once local topography is considered, allows us to look at cooling and/or rheology changes downslope. Here we present a more realistic extension of the levee formation model that treats the rate of levee growth as a function of distance along the flow path. We show how this model can be used with a terrestrial flow and a long lava flow on Mars. The key statement of the new formulation is the rate of transfer from the active component to the levees (or other passive components) through an element dx along the path of the flow. This volumetric transfer equation is presented.

  16. A sinuous tumulus over an active lava tube at Kīlauea Volcano: Evolution, analogs, and hazard forecasts

    NASA Astrophysics Data System (ADS)

    Orr, Tim R.; Bleacher, Jacob E.; Patrick, Matthew R.; Wooten, Kelly M.

    2015-01-01

    Inflation of narrow tube-fed basaltic lava flows (tens of meters across), such as those confined by topography, can be focused predominantly along the roof of a lava tube. This can lead to the development of an unusually long tumulus, its shape matching the sinuosity of the underlying lava tube. Such a situation occurred during Kīlauea Volcano's (Hawai'i, USA) ongoing East Rift Zone eruption on a lava tube active from July through November 2010. Short-lived breakouts from the tube buried the flanks of the sinuous, ridge-like tumulus, while the tumulus crest, its surface composed of lava formed very early in the flow's emplacement history, remained poised above the surrounding younger flows. At least several of these breakouts resulted in irrecoverable uplift of the tube roof. Confined sections of the prehistoric Carrizozo and McCartys flows (New Mexico, USA) display similar sinuous, ridge-like features with comparable surface age relationships. We contend that these distinct features formed in a fashion equivalent to that of the sinuous tumulus that formed at Kīlauea in 2010. Moreover, these sinuous tumuli may be analogs for some sinuous ridges evident in orbital images of the Tharsis volcanic province on Mars. The short-lived breakouts from the sinuous tumulus at Kīlauea were caused by surges in discharge through the lava tube, in response to cycles of deflation and inflation (DI events) at Kīlauea's summit. The correlation between DI events and subsequent breakouts aided in lava flow forecasting. Breakouts from the sinuous tumulus advanced repeatedly toward the sparsely populated Kalapana Gardens subdivision, destroying two homes and threatening others. Hazard assessments, including flow occurrence and advance forecasts, were relayed regularly to the Hawai'i County Civil Defense to aid their lava flow hazard mitigation efforts while this lava tube was active.

  17. A sinuous tumulus over an active lava tube at Kīlauea Volcano: evolution, analogs, and hazard forecasts

    USGS Publications Warehouse

    Orr, Tim R.; Bleacher, Jacob E.; Patrick, Matthew R.; Wooten, Kelly M.

    2015-01-01

    Inflation of narrow tube-fed basaltic lava flows (tens of meters across), such as those confined by topography, can be focused predominantly along the roof of a lava tube. This can lead to the development of an unusually long tumulus, its shape matching the sinuosity of the underlying lava tube. Such a situation occurred during Kīlauea Volcano's (Hawai'i, USA) ongoing East Rift Zone eruption on a lava tube active from July through November 2010. Short-lived breakouts from the tube buried the flanks of the sinuous, ridge-like tumulus, while the tumulus crest, its surface composed of lava formed very early in the flow's emplacement history, remained poised above the surrounding younger flows. At least several of these breakouts resulted in irrecoverable uplift of the tube roof. Confined sections of the prehistoric Carrizozo and McCartys flows (New Mexico, USA) display similar sinuous, ridge-like features with comparable surface age relationships. We contend that these distinct features formed in a fashion equivalent to that of the sinuous tumulus that formed at Kīlauea in 2010. Moreover, these sinuous tumuli may be analogs for some sinuous ridges evident in orbital images of the Tharsis volcanic province on Mars. The short-lived breakouts from the sinuous tumulus at Kīlauea were caused by surges in discharge through the lava tube, in response to cycles of deflation and inflation (DI events) at Kīlauea's summit. The correlation between DI events and subsequent breakouts aided in lava flow forecasting. Breakouts from the sinuous tumulus advanced repeatedly toward the sparsely populated Kalapana Gardens subdivision, destroying two homes and threatening others. Hazard assessments, including flow occurrence and advance forecasts, were relayed regularly to the Hawai'i County Civil Defense to aid their lava flow hazard mitigation efforts while this lava tube was active.

  18. Paleoflow directions of a subaqueous lahar deposit around the Miocene Keserűs Hill lava dome complex (North Hungary) as constrained by photo-statistics and anisotropy of magnetic susceptibility (AMS)

    NASA Astrophysics Data System (ADS)

    Biró, T.; Karátson, D.; Márton, E.; Józsa, S.; Bradák, B.

    2015-09-01

    A twofold fabric analysis by using photo-statistics on rock surfaces and low-field anisotropy of magnetic susceptibility (AMS) is presented, making it possible to infer paleoflow directions, which in turn helps to constrain the primary volcanic geomorphology of a deeply eroded mid-Miocene field (Keserűs Hill lava dome group, Visegrád Mountains, North Hungary). The analyses were carried out on the Rám Hill Pumiceous Sandstone (RHPS) that, based on its petrographic features, is considered as a subaqueously emplaced laharic deposit. The observed anisotropic frequencies of clast a-axis azimuths, the good agreement of fabric directions obtained for all and most elongated samples (elongation > 2.5), the good clustering of the declinations of the K1 susceptibilities largely corresponding with the result of image analysis, allow to infer reliable flow directions. The obtained large-scale paleoflow paths show a quasi-radial pattern around the central part of the Visegrád Mountains, which quantitatively confirms the previous hypothesis on the volcanic structure, namely a central edifice-topped syn-eruptive topography. The RHPS is characterized by a clast fabric (revealed by photostatistics on cutted rock surfaces considering the lapilli-sized fraction) as strong as in subaerial PDC deposits, but by a significantly weaker magnetic fabric. The weak magnetic fabric is supposed to be the result of rock heterogeneity, thus the weakening effect of abundant lithic clasts with strong internal magnetic susceptibility anisotropy, different from the shape anisotropy of the clasts and the flow-related magnetic fabric of the fine-grained matrix.

  19. Emplacement Scenarios for Volcanic Domes on Venus

    NASA Technical Reports Server (NTRS)

    Glaze, Lori S.; Baloga, Steve M.; Stofan, Ellen R.

    2012-01-01

    One key to understanding the history of resurfacing on Venus is better constraints on the emplacement timescales for the range of volcanic features visible on the surface. A figure shows a Magellan radar image and topography for a putative lava dome on Venus. 175 such domes have been identified with diameters ranging from 19 - 94 km, and estimated thicknesses as great as 4 km. These domes are thought to be volcanic in origin and to have formed by the flow of viscous fluid (i.e., lava) on the surface.

  20. Photogrammetric and Global Positioning System Measurements of Active Pahoehoe Lava Lobe Emplacement on Kilauea, Hawaii

    NASA Technical Reports Server (NTRS)

    Hamilton, Christopher W.; Glaze, Lori S.; James, Mike R.; Baloga, Stephen M.; Fagents, Sarah A.

    2012-01-01

    Basalt is the most common rock type on the surface of terrestrial bodies throughout the solar system and -- by total volume and areal coverage -- pahoehoe flows are the most abundant form of basaltic lava in subaerial and submarine environments on Earth. A detailed understanding of pahoehoe emplacement processes is necessary for developing accurate models of flow field development, assessing hazards associated with active lava flows, and interpreting the significance of lava flow morphology on Earth and other planetary bodies. Here, we examine the active emplacement of pahoehoe lobes along the margins of the Hook Flow from Pu'u 'O'o on Kilauea, Hawaii. Topographic data were acquired between 21 and 23 February 2006 using stereo-imaging and differential global positing system (DGPS) measurements. During this time, the average discharge rate for the Hook Flow was 0.01-0.05 cubic m/s. Using stereogrammetric point clouds and interpolated digital terrain models (DTMs), active flow fronts were digitized at 1 minute intervals. These areal spreading maps show that the lava lobe grew by a series of breakouts tha t broadly fit into two categories: narrow (0.2-0.6 m-wide) toes that grew preferentially down-slope, and broad (1.4-3.5 m-wide) breakouts that formed along the sides of the lobe, nearly perpendicular to the down-flow axis. These lobes inflated to half of their final thickness within approx 5 minutes, with a rate of inflation that generally deceased with time. Through a combination of down-slope and cross-slope breakouts, lobes developed a parabolic cross-sectional shape within tens of minutes. We also observed that while the average local discharge rate for the lobe was generally constant at 0.0064 +/- 0.0019 cubic m/s, there was a 2 to 6 fold increase in the areal coverage rate every 4.1 +/- 0.6 minutes. We attribute this periodicity to the time required for the dynamic pressurization of the liquid core of the lava lobe to exceed the cooling-induced strength of the

  1. Source mechanism of very-long-period signals accompanying dome growth activity at Merapi volcano, Indonesia

    USGS Publications Warehouse

    Hidayat, D.; Chouet, B.; Voight, B.; Dawson, P.; Ratdomopurbo, A.

    2002-01-01

    Very-long-period (VLP) pulses with period of 6-7s, displaying similar waveforms, were identified in 1998 from broadband seismographs around the summit crater. These pulses accompanied most of multiphase (MP) earthquakes, a type of long-period event locally defined at Merapi Volcano. Source mechanisms for several VLP pulses were examined by applying moment tensor inversion to the waveform data. Solutions were consistent with a crack striking ???70?? and dipping ???50?? SW, 100m under the active dome, suggest pressurized gas transport involving accumulation and sudden release of 10-60 m3 of gas in the crack over a 6s interval.

  2. THEMIS Observations of Domes and Associated Lineaments in Arcadia Planitia

    NASA Astrophysics Data System (ADS)

    Milam, K. A.; McSween, H. Y.

    2003-12-01

    lineaments, 3 domes area appear to be cross-cut by lineaments. No laterally extensive flows have been detected as emanating from lineaments, nor have similar lineaments been detected immediately outside the study area. The association of domes and lineaments is consistent with observations of volcanic constructs along open fissures in many terrestrial volcanic fields. Assuming a volcanic origin, the dome-lineament relationship suggests localized, structurally-controlled eruptions along open fissures. Initial extension caused the opening of fractures, which was followed by localized extrusions. Such localized development can provide information about eruption rates, magma compositions, or the physical properties of erupted lava. Either during or after volcanic activity, continued extension led to several domes being dissected by fissures.

  3. Thermal radiance observations of an active lava flow during the June 1984 eruption of Mount Etna

    SciTech Connect

    Pieri, D.C.; Glaze, L.S.; Abrams, M.J. )

    1990-10-01

    The thermal budget of an active lava flow observed on 20 June 1984 from the Southeast crater of Mount Etna, Sicily, Italy, was analyzed from data taken by the Landsat Thematic Mapper. The Thematic Mapper images constitute one of the few satellite data sets of sufficient spatial and spectral resolution to allow calibrated measurements on the distribution and intensity of thermal radiation from active lava flows. Using radiance data from two reflective infrared channels, we can estimate the temperature and areas of the hottest parts of the active flow, which correspond to hot (>500{degree}C) fractures or zones at the flow surface. Using this techniques, we estimate that only 10%-20% of the total radiated thermal power output is emitted by hot zones or fractures, which constitute less than 1% of the observed surface area. Generally, it seems that only where hot fractures or zones constitute greater than about 1% of the surface area of the flow will losses from such features significantly reduce internal flow temperatures. Using our radiance observations as boundary conditions for a multicomponent thermal model of flow interior temperature, we infer that, for the parts of this flow subject to analysis, the boundary layer and flow thickness effects dominate over radiant zones in controlling the depression of core temperature.

  4. Emplacement of Volcanic Domes on Venus and Europa

    NASA Technical Reports Server (NTRS)

    Quick, Lynnae C.; Glaze, Lori S.; Baloga, Steve M.

    2015-01-01

    Placing firmer constraints on the emplacement timescales of visible volcanic features is essential to obtaining a better understanding of the resurfacing history of Venus. Fig. 1 shows a Magellan radar image and topography for a putative venusian lava dome. 175 such domes have been identified, having diameters that range from 19 - 94 km, and estimated thicknesses as great as 4 km [1-2]. These domes are thought to be volcanic in origin [3], having formed by the flow of a viscous fluid (i.e., lava) onto the surface. Among the unanswered questions surrounding the formation of Venus steep-sided domes are their emplacement duration, composition, and the rheology of the lava. Rheologically speaking, maintenance of extremely thick, 1-4 km flows necessitates higher viscosity lavas, while the domes' smooth upper surfaces imply the presence of lower viscosity lavas [2-3]. Further, numerous quantitative issues, such as the nature and duration of lava supply, how long the conduit remained open and capable of supplying lava, the volumetric flow rate, and the role of rigid crust in influencing flow and final morphology all have implications for subsurface magma ascent and local surface stress conditions. The surface of Jupiter's icy moon Europa exhibits many putative cryovolcanic constructs [5-7], and previous workers have suggested that domical positive relief features imaged by the Galileo spacecraft may be volcanic in origin [5,7-8] (Fig. 2). Though often smaller than Venus domes, if emplaced as a viscous fluid, formation mechanisms for europan domes may be similar to those of venusian domes [7]. Models for the emplacement of venusian lava domes (e.g. [9-10]) have been previously applied to the formation of putative cryolava domes on Europa [7].

  5. Late Holocene phases of dome growth and Plinian activity at Guagua Pichincha volcano (Ecuador)

    NASA Astrophysics Data System (ADS)

    Robin, Claude; Samaniego, Pablo; Le Pennec, Jean-Luc; Mothes, Patricia; van der Plicht, Johannes

    2008-09-01

    Since the eruption which affected Quito in AD 1660, Guagua Pichincha has been considered a hazardous volcano. Based on field studies and twenty 14C dates, this paper discusses the eruptive activity of this volcano, especially that of the last 2000 years. Three major Plinian eruptions with substantial pumice discharge occurred in the 1st century, the 10th century, and in AD 1660. The ages of organic paleosols and charcoal from block-and-ash flow and fallout deposits indicate that these eruptions occurred near the end of 100 to 200 year-long cycles of discontinuous activity which was comprised of dome growth episodes and minor pumice fallouts. The first cycle took place from ~ AD 1 to 140. The second one developed during the 9th and 10th centuries, lasted 150-180 yr, and included the largest Plinian event, with a VEI of 5. The third, historic cycle, about 200 yr in duration, includes pyroclastic episodes around AD 1450 and AD 1500, explosive activity between AD 1566 and AD 1582, possible precursors of the 1660 eruption in the early decades of the 17th century, and finally the 1660 eruption (VEI 4). A fourth event probably occurred around AD 500, but its authenticity requires confirmation. The Plinian events occurred at the end of these cycles which were separated by repose periods of at least 300 yr. Older volcanic activity of similar type occurred between ~ 4000 and ~ 3000 yr BP. Because ash fallout and related mudflows represent a serious hazard for Quito's metropolitan area, the significance of the increasing phreatic activity observed from 1981 to 1998, and the 1999-2001 magmatic episode of dome growth and collapse are discussed. These probably represent a short step in a longer evolution which may result in a major Plinian event in the future decades or in the next century, comparable to that which occurred during the 1st, 10th, and 17th centuries.

  6. Holocene block-and-ash flows from summit dome activity of Citlaltépetl volcano, Eastern Mexico

    NASA Astrophysics Data System (ADS)

    Carrasco-Núñez, Gerardo

    1999-01-01

    A major eruption produced several block-and-ash flows about 4,100 years B.P. at Citlaltépetl volcano (Pico de Orizaba), an ice-capped, 5670-m-high, andesitic, active stratovolcano located at the eastern end of the Mexican Volcanic Belt. Repetitive gravitational collapse of a dacitic dome at the summit crater produced a series of block-and-ash flows, lahars, and floods, which were channeled through two main river-valleys on the west and south flanks of the volcano. The total erupted volume is estimated to be at least 0.27 km 3. The deposits in both areas are similar in composition, and size, but they differ in the area covered, distribution, and structure. The western deposits form a large fan, cover a larger area, and include numerous laharic and fluviatile deposits. In contrast, the southern deposits form prominent terraces where confined in narrow channels, and have associated laharic units in distal areas, where the flows reach a maximum distance of 30 km from the vent. Directed disruptions of a central summit dome occurred, possibly first to the west and then to the southeast, perhaps due to minor modifications of the summit dome morphology, producing the voluminous block-and-ash flow deposits documented here. The flows were strongly controlled by topography, influencing the deposition of the moving particles. Grain-size variations along the flow paths are hardly detectable suggesting no evident lateral downstream transformations. Because sudden changes in dome morphology may cause significant variations in the direction of future dome collapse, specific areas of potential affectation cannot be predicted. Therefore, about 350,000 inhabitants living within a radius of 35-km from the vent could be potentially impacted if catastrophic block-and-ash flows were to recur in the future from similar summit dome activity. Recognition of these deposits is therefore important for hazard assessment because some seemingly safe areas may be at high risk.

  7. Cryovolcanic emplacement of domes on Europa

    NASA Astrophysics Data System (ADS)

    Quick, Lynnae C.; Glaze, Lori S.; Baloga, Stephen M.

    2017-03-01

    Here we explore the hypothesis that certain domes on Europa may have been produced by the extrusion of viscous cryolavas. A new mathematical method for the emplacement and relaxation of viscous lava domes is presented and applied to putative cryovolcanic domes on Europa. A similarity solution approach is applied to the governing equation for fluid flow in a cylindrical geometry, and dome relaxation is explored assuming a volume of cryolava has been rapidly emplaced onto the surface. Nonphysical singularities inherent in previous models for dome relaxation have been eliminated, and cryolava cooling is represented by a time-variable viscosity. We find that at the onset of relaxation, bulk kinematic viscosities may lie in the range between 103 and 106 m2/s, while the actual fluid lava viscosity may be much lower. Plausible relaxation times to form the domes, which are linked to bulk cryolava rheology, are found to range from 3.6 days to 7.5 years. We find that cooling of the cryolava, while dominated by conduction through an icy skin, should not prevent fluids from advancing and relaxing to form domes within the timescales considered. Determining the range of emplacement conditions for putative cryolava domes will shed light on Europa's resurfacing history. In addition, the rheologies and compositions of erupted cryolavas have implications for subsurface cryomagma ascent and local surface stress conditions on Europa.

  8. Cryovolcanic Emplacement of Domes on Europa

    NASA Technical Reports Server (NTRS)

    Quick, Lynnae C.; Glaze, Lori S.; Baloga, Stephen M.

    2016-01-01

    Here we explore the hypothesis that certain domes on Europa may have been produced by the extrusion of viscous cryolavas. A new mathematical method for the emplacement and relaxation of viscous lava domes is presented and applied to putative cryovolcanic domes on Europa. A similarity solution approach is applied to the governing equation for fluid flow in a cylindrical geometry, and dome relaxation is explored assuming a volume of cryolava has been rapidly emplaced onto the surface. Nonphysical sin- gularities inherent in previous models for dome relaxation have been eliminated, and cryolava cooling is represented by a time-variable viscosity. We find that at the onset of relaxation, bulk kinematic viscosities may lie in the range between 10(exp 3) and 10(exp 6) sq m/s, while the actual fluid lava viscosity may be much lower. Plausible relaxation times to form the domes, which are linked to bulk cryolava rheology, are found to range from 3.6 days to 7.5 years. We find that cooling of the cryolava, while dominated by conduction through an icy skin, should not prevent fluids from advancing and relaxing to form domes within the timescales considered. Determining the range of emplacement conditions for putative cryolava domes will shed light on Europa's resurfacing history. In addition, the rheologies and compositions of erupted cryolavas have implications for subsurface cryomagma ascent and local surface stress conditions on Europa.

  9. Lava lakes on Io: Observations of Io's volcanic activity from Galileo NIMS during the 2001 fly-bys

    USGS Publications Warehouse

    Lopes, R.M.C.; Kamp, L.W.; Smythe, W.D.; Mouginis-Mark, P.; Kargel, J.; Radebaugh, J.; Turtle, E.P.; Perry, J.; Williams, D.A.; Carlson, R.W.; Doute, S.

    2004-01-01

    Galileo's Near-Infrared Mapping Spectrometer (NIMS) obtained its final observations of Io during the spacecraft's fly-bys in August (I31) and October 2001 (I32). We present a summary of the observations and results from these last two fly-bys, focusing on the distribution of thermal emission from Io's many volcanic regions that give insights into the eruption styles of individual hot spots. We include a compilation of hot spot data obtained from Galileo, Voyager, and ground-based observations. At least 152 active volcanic centers are now known on Io, 104 of which were discovered or confirmed by Galileo observations, including 23 from the I31 and I32 Io fly-by observations presented here. We modify the classification scheme of Keszthelyi et al. (2001, J. Geophys. Res. 106 (E12) 33 025-33 052) of Io eruption styles to include three primary types: promethean (lava flow fields emplaced as compound pahoehoe flows with small plumes 200 km high plumes and rapidly-emplaced flow fields), and a new style we call "lokian" that includes all eruptions confined within paterae with or without associated plume eruptions). Thermal maps of active paterae from NIMS data reveal hot edges that are characteristic of lava lakes. Comparisons with terrestrial analogs show that Io's lava lakes have thermal properties consistent with relatively inactive lava lakes. The majority of activity on Io, based on locations and longevity of hot spots, appears to be of this third type. This finding has implications for how Io is being resurfaced as our results imply that eruptions of lava are predominantly confined within paterae, thus making it unlikely that resurfacing is done primarily by extensive lava flows. Our conclusion is consistent with the findings of Geissler et al. (2004, Icarus, this issue) that plume eruptions and deposits, rather than the eruption of copious amounts of effusive lavas, are responsible for Io's high resurfacing rates. The origin and longevity of islands within ionian

  10. Satellite Measurements of Lava Extrusion Rate at Volcán Reventador, Ecuador

    NASA Astrophysics Data System (ADS)

    Arnold, D. W. D.; Biggs, J.; Ebmeier, S. K.; Vallejo Vargas, S.; Naranjo, M. F.

    2015-12-01

    The extrusion rate of lava at active volcanoes provides a principle control on the style of eruptive behavior and the extent of lava flows, while also providing information about magma supply to the volcano. Measurements of extrusion rate at active volcanoes are therefore important for assessing hazard, and improving understanding of volcanic systems. Volcán Reventador is an asymmetric stratovolcano in the Cordillera Real of Ecuador. The largest historically observed eruption at Reventador in 2002 has been followed by several periods of eruptive activity. Eruptions are characterised by effusion of andesitic to basaltic-andesitic lava flows, and Vulcanian explosions. The ongoing eruption at Reventador therefor provides an excellent target for investigating the link between effusion rate, explosivity, and lava flow behaviour. Satellite InSAR provides regular observations of the volcano, even during night or periods of cloud cover. We use a dataset of Radarsat-2 and TanDEM-X imagery, with intervals of 11 to 192 days, over the period 2011 to 2014 to measure the extent, thickness and volume of new lava flows at Reventador. We use radar amplitude and inteferometric coherence to map 25 individual lava flows, as well as pyroclastic deposits and changes in lava dome morphology. We observe 43 Mm3 of deposits over a three year period, giving an average effusion rate of 0.5 m3s-1. We do not observe any ground deformation due to magmatic sources at Reventador, therefore variations in lava effusion rate can be interpreted as changes in the magma supply to the volcano. We investigate the link between variations in effusion rate and the length, area, thickness, and aspect ratio of lava flows, and the explosive-effusive transition. We also characterise the relationship between lava flow age, thickness, and subsidence rate.

  11. Ibu volcano, a center of spectacular dacite dome growth and long-term continuous eruptive discharges

    NASA Astrophysics Data System (ADS)

    Saing, Ugan Boyson; Bani, Philipson; Kristianto

    2014-08-01

    Ibu is one of the most isolated and least accessible volcanoes of Indonesia, located on Halmahera Island, in the province of Maluku, East Indonesia. This volcano is one of the most active volcanoes in Indonesia, but remains poorly studied. Since its resuming activity in 1998, Ibu has injected around 0.7 Tg of SO2 into the atmosphere through 60-100 daily eruptive discharges. This long-term eruptive activity is very well retraced by seismic signals that highlight the progressive dome growth and the supply of new magma into Ibu reservoir. The lava dome which is of dacite composition is developing at a rate of 3182 m3 per day. This decadal dome growth of Ibu requires further attention and warrants monitoring as it is a hazard and risk concern.

  12. Broadband seismic measurements of degassing activity associated with lava effusion at Popocatépetl Volcano, Mexico

    USGS Publications Warehouse

    Arciniega-Ceballos, Alejandra; Chouet, Bernard A.; Dawson, Phillip; Asch, Guenter

    2008-01-01

    exhalations”). Eruptive activity increased in intensity in February, coinciding with an increasing occurrence of Type-II LP events. Type-III events were first observed at the end of February and during March, in coincidence with the formation of a new lava dome. Vulcanian eruptions occurred in April and May. These events typically exhibit broadband signatures extending over the full period range of the sensors and lasting 30–80 min.

  13. Lava Flow Dynamics

    NASA Technical Reports Server (NTRS)

    Taylor, G. Jeffrey

    1996-01-01

    This grant originally had four major tasks, all of which were addressed to varying extents during the course of the research: (1) Measure the fractal dimensions of lava flows as a function of topography, substrate, and rheology; (2) The nature of lava tube systems and their relation to flow fields; (3) A quantitative assessment of lava flow dynamics in light of the fractal nature of lava flow margins; and (4) Development and application of a new remote sensing tool based on fractal properties. During the course of the research, the project expanded to include the following projects: (1) A comparison of what we can-learn from remote sensing studies of lava flow morphology and from studies of samples of lava flows; (2) Study of a terrestrial analog of the nakhlites, one of the groups of meteorites from Mars; and (3) Study of the textures of Hawaiian basalts as an aid in understanding the dynamics (flow rates, inflation rates, thermal history) of flow interiors. In addition, during the first year an educational task (development and writing of a teacher's guide and activity set to accompany the lunar sample disk when it is sent to schools) was included.

  14. Dome growth, collapse, and valley fill at Soufrière Hills Volcano, Montserrat, from 1995 to 2013: Contributions from satellite radar measurements of topographic change

    USGS Publications Warehouse

    Arnold, D. W. D.; Biggs, J.; Wadge, G.; Ebmeier, S. K.; Odbert, H. M.; Poland, Michael P.

    2016-01-01

    Frequent high-resolution measurements of topography at active volcanoes can provide important information for assessing the distribution and rate of emplacement of volcanic deposits and their influence on hazard. At dome-building volcanoes, monitoring techniques such as LiDAR and photogrammetry often provide a limited view of the area affected by the eruption. Here, we show the ability of satellite radar observations to image the lava dome and pyroclastic density current deposits that resulted from 15 years of eruptive activity at Soufrière Hills Volcano, Montserrat, from 1995 to 2010. We present the first geodetic measurements of the complete subaerial deposition field on Montserrat, including the lava dome. Synthetic aperture radar observations from the Advanced Land Observation Satellite (ALOS) and TanDEM-X mission are used to map the distribution and magnitude of elevation changes. We estimate a net dense-rock equivalent volume increase of 108 ± 15M m3 of the lava dome and 300 ± 220M m3 of talus and subaerial pyroclastic density current deposits. We also show variations in deposit distribution during different phases of the eruption, with greatest on-land deposition to the south and west, from 1995 to 2005, and the thickest deposits to the west and north after 2005. We conclude by assessing the potential of using radar-derived topographic measurements as a tool for monitoring and hazard assessment during eruptions at dome-building volcanoes.

  15. Chronology of Vesuvius' activity from A.D. 79 to 1631 based on archeomagnetism of lavas and historical sources

    NASA Astrophysics Data System (ADS)

    Principe, Claudia; Tanguy, Jean Claude; Arrighi, Simone; Paiotti, Anna; Goff, Maxime Le; Zoppi, Ugo

    2004-12-01

    The activity of Vesuvius between A.D. 79 and 1631 has been investigated by means of precise archaeomagnetic dating of primary volcanic deposits and taking into account the stratigraphy of lavas and tephra, historical written accounts, archaeological evidence related to the developing urbanisation, and radiocarbon ages. We found that the historical records are highly useful in constraining the timing of the main events, even if the data are often too scarce and imprecise for ascertaining the details of all phases of activity, especially their magnitude and emplacement of all the deposit types. In addition, some eruptions that took place in the 9th and 10th centuries appear to be unnoticed by historians. The archaeomagnetic study involved 26 sites of different lavas and 2 pyroclastic deposits. It shows that within the 15 centuries which elapsed between A.D. 79 and 1631, the effusive activity of Vesuvius clustered in the relatively short period of time between A.D. 787 and 1139 and was followed by a 5-century-long repose period. During this time Vesuvius prepared itself for the violent explosive eruption of 1631. The huge lavas shaping the morphology of the coast occurred largely through parasitic vents located outside the Mount Somma caldera. One of these parasitic vents is located at low elevation, very close to the densely inhabited town of Torre Annunziata. Among the various investigated lavas, a number of which were previously attributed to the 1631 eruption, none is actually younger than the 12th century. Therefore it is definitively concluded that the destructive 1631 event was exclusively explosive.

  16. A Radar Survey of Lunar Dome Fields

    NASA Technical Reports Server (NTRS)

    Carter, Lynn M.; Campbell, Bruce A.; Hawke, B. Ray; Bussey, Ben

    2011-01-01

    The near side of the Moon has several areas with a high concentration of volcanic domes. These low relief structures are considerably different in morphology from terrestrial cinder cones, and some of the domes may be similar to some terrestrial shields formed through Hawaiian or Strombolian eruptions from a central pipe vent or small fissure [1]. The domes are evidence that some volcanic lavas were more viscous than the mare flood basalts that make up most of the lunar volcanic flows. It is still not known what types of volcanism lead to the creation of specific domes, or how much dome formation may have varied across the Moon. Prior work has shown that some domes have unusual radar polarization characteristics that may indicate a surface or subsurface structure that is different from that of other domes. Such differences might result from different styles of late-stage volcanism for some of the domes, or possibly from differences in how the erupted materials were altered over time (e.g. by subsequent volcanism or nearby cratering events). For example, many of the domes in the Marius Hills region have high circular polarization ratios (CPRs) in S-band (12.6 cm wavelength) and/or P-band (70 cm wavelength) radar data [2]. The high CPRs are indicative of rough surfaces, and suggest that these domes may have been built from overlapping blocky flows that in some cases have been covered by meters of regolith [2, 3]. In other cases, domes have low circular polarization ratios indicative of smooth, rock-poor surfaces or possibly pyroclastics. The 12 km diameter dome Manilius 1 in Mare Vaporum [1], has a CPR value of 0.20, which is significantly below values for the surrounding basalts [4]. To better understand the range of surface properties and styles of volcanism associated with the lunar domes, we are currently surveying lunar dome fields including the Marius Hills, Cauchy/Jansen dome field, the Gruithuisen domes, and domes near Hortensius and Vitruvius.

  17. Lava Lamp

    ERIC Educational Resources Information Center

    Leif, Todd R.

    2008-01-01

    This past semester I brought a Lava Lite[R] Lamp into my classroom. Why bring such a thing into class? Many of today's students are part of the "retro" movement. They buy clothes from the '60s, they wear their hair like people did in the '60s, and they look for the ideals and themes related to living in the 1960s. Physics education reform is also…

  18. Lava Flows

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03054 Lava Flows

    The lava flows in this image are only a very small part of the voluminous lava erupted from the Arsia Mons volcano.

    Image information: VIS instrument. Latitude 19.1S, Longitude 244.5E. 17 meter/pixel resolution.

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

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

  19. Volcano dome dynamics at Mount St. Helens: Deformation and intermittent subsidence monitored by seismicity and camera imagery pixel offsets

    NASA Astrophysics Data System (ADS)

    Salzer, Jacqueline T.; Thelen, Weston A.; James, Mike R.; Walter, Thomas R.; Moran, Seth; Denlinger, Roger

    2016-11-01

    The surface deformation field measured at volcanic domes provides insights into the effects of magmatic processes, gravity- and gas-driven processes, and the development and distribution of internal dome structures. Here we study short-term dome deformation associated with earthquakes at Mount St. Helens, recorded by a permanent optical camera and seismic monitoring network. We use Digital Image Correlation (DIC) to compute the displacement field between successive images and compare the results to the occurrence and characteristics of seismic events during a 6 week period of dome growth in 2006. The results reveal that dome growth at Mount St. Helens was repeatedly interrupted by short-term meter-scale downward displacements at the dome surface, which were associated in time with low-frequency, large-magnitude seismic events followed by a tremor-like signal. The tremor was only recorded by the seismic stations closest to the dome. We find a correlation between the magnitudes of the camera-derived displacements and the spectral amplitudes of the associated tremor. We use the DIC results from two cameras and a high-resolution topographic model to derive full 3-D displacement maps, which reveals internal dome structures and the effect of the seismic activity on daily surface velocities. We postulate that the tremor is recording the gravity-driven response of the upper dome due to mechanical collapse or depressurization and fault-controlled slumping. Our results highlight the different scales and structural expressions during growth and disintegration of lava domes and the relationships between seismic and deformation signals.

  20. Use of digital aerophotogrammetry to determine rates of lava dome growth, Mount St. Helens, Washington, 2004-2005: Chapter 8 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Schilling, Steve P.; Thompson, Ren A.; Messerich, James A.; Iwatsubo, Eugene Y.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    Successful application of aerophotogrammetry was possible during the critical earliest parts of the eruption because we had baseline data and photogrammetric infrastructure in place before the eruption began. The vertical aerial photographs, including the DEMs and calculations derived from them, were one of the most widely used data sets collected during the 2004-5 eruption, as evidenced in numerous contributions to this volume. These data were used to construct photogeologic maps, deformation vector fields, and profiles of the evolving dome and glacier. Extruded volumes and rates proved to be critical parameters to constrain models and hypotheses of eruption dynamics and thus helped to assess volcano hazards.

  1. Combining very-long-range terrestrial laser scanner data and thermal imagery for analysis of active lava flow fields

    NASA Astrophysics Data System (ADS)

    James, Mike; Pinkerton, Harry; Applegarth, Jane

    2010-05-01

    In order to increase our understanding of the processes involved in the evolution of lava flow fields, detailed and frequent assessments of the activity and the topographic change involved are required. Although topographic data of sufficient accuracy and resolution can be acquired by airborne lidar, the cost and logistics generally prohibit repeats at the daily (or more frequent) intervals necessary to assess flow processes. More frequent surveys can be carried out using ground-based terrestrial laser scanners (TLSs) but on volcanic terrain such instruments generally have ranges of only several hundreds of metres, with long range variants extending to ~1100 m. Here, we report preliminary results from the use of a new, ground-based Riegl LPM-321 instrument with a quoted maximum range of 6000 m. The LPM-321 was deployed at Mount Etna, Sicily during July 2009. At this time, active lava flows from the waning 2008-9 eruption were restricted to the upper region of a lava delta that had accumulated over the course of the eruption. Relatively small (a few hundreds of metres in length) and short lived (of order a few days) flows were being effused from a region of tumuli at the head of the delta. The instrument was used from three locations, Schiena dell' Àsino, the head of the Valle del Bove and Pizzi Deneri. From Schiena dell' Àsino, most of the 2008-9 lava flows could be observed, but, due to low reflectivities and viewing distances of ~4500 m, the active regions of the flows were out of range. The longest return was acquired from a range of 3978 m, but successful returns at this range were sparse; for dense topographic data, data were best acquired over distances of less than ~3500 m. The active flows were successfully imaged from the head of the Valle del Bove (9 and 12 July, 2009) and Pizzi Deneri (6 July, 2009). Despite low effusion rates (~1 m3s-1), topographic change associated with the emplacement and inflation of new flows and the inflation of a tumulus was

  2. Monitoring active volcanism using ASTER satellite remote sensing: Volcan de Colima, Colima, Mexico

    NASA Astrophysics Data System (ADS)

    Silvertooth, Maggie Lin

    Scope and Method of Study. ASTER satellite data was collected and analyzed in order to quantify changes in temperature, vesicularity, and morphology of the dome and crater that support evidence of constructive and destructive phases of lava dome growth and destruction cycles. These cycles are characterized by sporadic growth of a lava dome that is subsequently destroyed by a Vulcanian or Pelean style eruption. Activity reports were compared with ASTER images and new deposits were mapped along the flanks of the volcano. There is no way to distinguish between pyroclastic material, rockfall deposits, lahar deposits or lava flows therefore all new flows were mapped. Findings and Conclusions. During a constructive phase, magma that is low in volatiles rises and forms a new dome. The low amount of volatiles leads to a decrease in vesicularity. Therefore during a destructive phase vesicularity is increased. Examining changes in temperature on the dome, it appears that temperatures are at a maximum before an eruptive event, such as incandescent material being extruded at the edge of the dome. Immediately after the lava dome is removed by an explosive event, a decrease in temperature is observed. Once activity resumes, increase in temperature is seen. Morphological changes on the dome can be due to explosive events, gravitational collapse, and factors affecting the endogenous and exogenous growth of the dome. Satellite data provides a synoptic view allowing for observation of new activity to be observed earlier than ground based data may allow. In the case of the Volcan de Colima, satellite remote sensing provided insight to the constructive and destructive phases of the lava dome and current activity.

  3. Growth of the 2004-2006 lava-dome complex at Mount St. Helens, Washington: Chapter 9 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Vallance, James W.; Schneider, David J.; Schilling, Steve P.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    The chief near-surface controls on spine extrusion during 2004-6 have been vent location, relict topographic surfaces from the 1980s, and spine remnants emplaced previously during the present eruption. In contrast, glacier ice has had minimal influence on spine growth. Ice as thick as 150 m has prevented formation of marginal angle-of-repose talus fans but has not provided sufficient resistance to stop spine growth or slow it appreciably. Spines initially emerged along a relict south-facing slope as steep as 40° on the 1980s dome. The open space of the moat between that dome and the crater walls permitted initial southward migration of recumbent spines. An initial spine impinged on the opposing slopes of the crater and stopped; in contrast, recumbent whaleback spines of phase 3 impinged on opposing walls of the crater at oblique angles and rotated eastward before breaking up. Once spine remnants occupied all available open space to the south, spines thrust over previous remnants. Finally, with south and east portions of the moat filled, spine growth proceeded westward. Although Crater Glacier had only a small influence on the growing spines, spine growth affected the glacier dramatically, initially dividing it into two arms and then bulldozing it hundreds of meters, first east and then west, and heaping it more than 100 m higher than its original altitude.

  4. Dome collapse eruption in Tatun Volcanic Group near metropolitan Taipei, Taiwan at ~6 kyrs

    NASA Astrophysics Data System (ADS)

    Chen, C.; Lee, T.

    2010-12-01

    The Tatun Volcanic Group (TVG) is located in the north of metropolitan Taipei, Taiwan. Over 6 million inhabitants are living in Taipei City and suburban area. Another critical issue is an international airport and two nuclear power plants are lying at the foot of the TVG. If the TGV will be re-active, the serious hazard for human lives and economies in this area will definitely occur. Understanding the youngest eruption history of the TVG will be much important for prediction the future activity of eruption. The core was collected from the Dream Lake at the eastern slop of Cising Mt.. Total 21 samples from depth 190 cm to 231.5 cm have been tested. Comparison of chemical compositions of glass and minerals in the volcanic clasts with those of lava around TVG, they clearly showed that the volcanic clasts can be correlated with the eruption of the closest Cising Mt. According to the radiocarbon (C-14) age of core sample at the depth 225 cm, the age was extrapolated around 6150 yrs ca. C-14 B.P.. Moreover, the respiratory cristobalite in the volcanic clasts were firstly identified by the identical morphology, chemical composition and Laser Raman Spectrometry (LRS). The crystalline silica was produced by vapor-phase crystallization and devitrification in the andesite lava dome and volcanic ash generated by pyroclastic flows formed by lava dome collapse in Soufriere Hills volcano, Montserrat (Baxter et al.,1999). These new evidence demonstrated that there would probably have the lava dome collapse eruptions in the TVG in the last 6 kyrs. The result in this paper also sustained that the landslide caused by the weak phreatic eruption within the last 6000 yrs in the TVG (Belousov et al., 2010). It must further be noted that an efficient program of the volcanic hazard reduction should be practiced for the metropolitan Taipei and suburban area.

  5. Lava Flows

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03658 Lava Flows

    These relatively young lava flows are part of Arsia Mons.

    Image information: VIS instrument. Latitude -22.5N, Longitude 242.3E. 17 meter/pixel resolution.

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

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

  6. Processes active in mafic magma chambers: The example of Kilauea Iki Lava Lake, Hawaii

    USGS Publications Warehouse

    Helz, R.T.

    2009-01-01

    Kilauea Iki lava lake formed in 1959 as a closed chamber of 40??million m3 of picritic magma. Repeated drilling and sampling of the lake allows recognition of processes of magmatic differentiation, and places time restrictions on the periods when they operated. This paper focuses on evidence for the occurrence of lateral convection in the olivine-depleted layer, and constraints on the timing of this process, as documented by chemical, petrographic and thermal data on drill core from the lake. Lateral convection appears to have occurred in two distinct layers within the most olivine-poor part of the lake, created a slightly olivine-enriched septum in the center of the olivine-depleted section. A critical marker for this process is the occurrence of loose clusters of augite microphenocrysts, which are confined to the upper half of the olivine-poor zone. This process, which took place between late 1962 and mid-1964, is inferred to be double-diffusive convection. Both this convection and a process of buoyant upwelling of minimum-density liquid from deep within the lake (Helz, R.T., Kirschenbaum H. and Marinenko, J.W., 1989. Diapiric melt transfer: a quick, efficient process of igneous differentiation: Geological Society of America Bulletin, v. 101, 578-594) result from the fact that melt density in Kilauea Iki compositions decreases as olivine and augite crystallize, above the incoming of plagioclase. The resulting density vs. depth profile creates (1) a region of gravitationally stable melt at the top of the chamber (the locus of double-diffusive convection) and (2) a region of gravitationally unstable melt at the base of the melt column (the source of upwelling minimum-density melt, Helz, R.T., Kirschenbaum H. and Marinenko, J.W., 1989. Diapiric melt transfer: a quick, efficient process of igneous differentiation: Geological Society of America Bulletin, v. 101, 578-594). By contrast the variation of melt density with temperature for the 1965 Makaopuhi lava lake does

  7. Investigation of Volcanic Seismo-Acoustic Signals: Applying Subspace Detection to Lava Fountain Activity at Etna Volcano

    NASA Astrophysics Data System (ADS)

    Sciotto, M.; Rowe, C. A.; Cannata, A.; Arrowsmith, S.; Privitera, E.; Gresta, S.

    2011-12-01

    The current eruption of Mount Etna, which began in January, 2011, has produced numerous energetic episodes of lava fountaining, which have bee recorded by the INGV seismic and acoustic sensors located on and around the volcano. The source of these events was the pit crater on the east flank of the Southeast crater of Etna. Simultaneously, small levels of activity were noted in the Bocca Nuova as well, prior to its lava fountaining activity. We will present an analysis of seismic and acoustic signals related to the 2011 activity wherein we apply the method of subspace detection to determine whether the source exhibits a temporal evolution within or between fountaining events, or otherwise produces repeating, classifiable events occurring through the continuous explosive degassing. We will examine not only the raw waveforms, but also spectral variations in time as well as time-varying statistical functions such as signal skewness and kurtosis. These results will be compared to straightforward cross-correlation analysis. In addition to classification performance, the subspace method has promise to outperform standard STA/LTA methods for real-time event detection in cases where similar events can be expected.

  8. Lunar mare domes - Classification and modes of origin

    NASA Technical Reports Server (NTRS)

    Head, J. W.; Gifford, A.

    1980-01-01

    In this paper, lunar mare domes (LMDs) are classified according to morphologic and morphometric (primarily diameter) characteristics, and consideration is given to their origin and role in lunar surface processes. In general, they occur either as low, flat, circular structures with convex shapes, slopes less than about 5 deg, and display summit craters, or as irregular structures often adjacent to highland regions and rarely containing summit craters. It is found that LMDs originate through extrusion of lavas through vents to produce low lava shields, or through flooding and draping of preexisting topography to produce kipukas and irregular domes. Smooth, vent-related mare domes range from about 3-17 km in diameter and up to several hundred meters in elevation; they are similar in morphology to small terrestrial lava shields.

  9. Introduction to special section: Long lava flows

    NASA Astrophysics Data System (ADS)

    Cashman, Katharine; Pinkerton, Harry; Stephenson, Jon

    1998-11-01

    Long lava flows are traditionally considered to form when low-viscosity lava is erupted at high effusion rates. However, this view has recently been challenged. Detailed field measurements on active lava flows on Kilauea have shown that inflation of lava flows after emplacement can result in reactivation and continued lengthening of flows. Inflated sheets can thus act a insulated conduits (lava tubes) that permit the transport of lava over great distances at near isothermal conditions. Detailed observations of long lava flows in the Columbia River Basalt Group and in the Cenozoic Volcanic Provinces in northern Queensland confirm that this mechanism is not restricted to recent flows on Hawaii. These findings have led to a search for evidence of inflation in flows in other parts of the world and have stimulated theoretical and laboratory research on the emplacement and cooling of lava in flows and in tubes. Understanding the formation of long submarine and planetary lava flows presents an additional challenge. Current evidence supports high effusion rates for some, possibly all, long planetary lava flows, and improved resolution from the Mars Global Surveyor will undoubtedly lead to either a confirmation or a rejection of this view. In this review, we discuss the geological importance and distribution of long lava flows, we investigate diametrically opposed views on the formation of long lava flows, and we stress the need for an interdisciplinary approach to improve our understanding of these enigmatic geological features.

  10. Retrieval of lava and SO2 fluxes during long-lived effusive eruptions using MSG-SEVIRI: the case of Bárdarbunga 2014 activity

    NASA Astrophysics Data System (ADS)

    Gouhier, Mathieu; Gauthier, Pierre-Jean; Haddadi, Baptiste; Moune, Séverine; Sigmarsson, Olgeir

    2015-04-01

    During effusive events, such as that of the 2014 Holuhraun eruption in the Bárdarbunga Volcanic System, Iceland, the lava and SO2 fluxes can be very large and possibly last for several months. However, the magma effusion rate as well as the gas flux may vary. The monitoring of any changes is essential as it informs on the dynamics of the eruption, and possibly reflects modifications of deeper mechanisms at the origin of the eruption. Geostationary satellite sensors turns out to be particularly relevant to record rapid changes of surface activity by the continuous acquisition of infrared data at time resolution of up to one image every five minutes. However, the long time-series generated cannot easily be analyzed and interpreted using conventional techniques, and require automated processing. Here we present a new method, hereafter called the "gradient method", which can be applied for the quantification of both lava volume and gas mass fluxes during long-lived effusive eruptions using infrared geostationary satellite data. The retrieval scheme comprises the following steps: firstly, the instantaneous lava volume and SO2 cloud mass must be calculated from each image. Then, we apply the "gradient method" to retrieve the lava and gas fluxes, leading to estimates of the true lava volume and gas mass. For the lava, the 3.9µm and 12µm wavebands are used to detect thermal anomalies and calculate related lava areas from the dual "pixel integrated temperature" method. Then, assuming the lava flow thickness, it gives an instantaneous lava volume. The SO2 column abundance is retrieved from the 8.7µm waveband using a linear regression derived from a least square fit procedure between satellite sensor measurements and simulated radiances. It leads to an instantaneous SO2 cloud mass. These calculations are made at each time step, generating time series of these two parameters. The actual lava volume and SO2 mass cannot be estimated through the integration of the total time

  11. A Rare Window Into Magmatic Conduit Processes: Time Series Observations From Active Lava Lakes

    NASA Astrophysics Data System (ADS)

    Lev, E.; Ruprecht, P.; Patrick, M.; Oppenheimer, C.; Peters, N.; Spampinato, L.; Hernandez Perez, P. A.; Unglert, K.; Barreyre, T.

    2015-12-01

    Time-lapse thermal images of the lake surface are used to investigate the circulation and cooling patterns of three lava lakes: Kilauea's Halema'uma'u crater, Mount Erebus, and Nyiragongo. We report results for the time-dependent, two-dimensional velocity and temperature fields of the lake surface. These data sets constrain the locations of flow divergence (upwelling) and convergence (downwelling), the distribution of distinct "plates" and "rifts", the dominant time scales for changes in flow pattern at each lake, and the physical properties of the magma. Upwelling and downwelling locations are strikingly different between the three lakes. Upwelling at Nyiragongo and Erebus occurs dominantly in the interior of the lake, where it is occasionally interrupted by catastrophic downwellings. At Halema'uma'u upwelling and downwelling occur consistently along the perimeter. It remains to be seen whether these differences are dictated merely by the system's geometry or are indicative of intrinsic factors such as melt viscosity, temperature and volatile and crystal content, or of conduit processes such as gas pistoning or slug flow. The availability of high resolution data at Halema'uma'u allows as us to document the evolution of crustal plates and rifts and to investigate the physical properties of the lava and the crust. The physical properties of the lake's surface control lake cooling rates, and thus need to be included in lake circulation and thermal evolution models. We produce time-temperature cooling curves from surface temperature profiles normal to surface rifts and by tracking the cooling of intra-plate bubble bursts. By comparing observations to analytical cooling models, we estimate a porosity of > 80% during the high stand of the lake, slightly higher than estimates of 70% for the upper 120 meters based on gravity data, and close to the porosity of clasts ejected from the lake during recent minor explosions. Furthermore,we find that the number of surface plates

  12. Lava Lakes on Io?

    NASA Astrophysics Data System (ADS)

    Lopes, R. M. C.; Kamp, L. W.; Smythe, W. D.; Howell, R.; Mouginis-Mark, P.; Kargel, J. S.; Radebaugh, J.; Turtle, E. P.; Perry, J.; Williams, D. A.; Carlson, R. W.; Doute, S.; Galileo NIMS Team

    2003-05-01

    At least 152 active volcanic centers have been identified on Jupiter's moon Io [Lopes et al., 2003, submitted to Icarus]. Eruptions at these centers include lava flows (``Promethean" type eruptions), explosive ``Pillanian" eruptions [Keszthelyi et al., 2001, JGR 106, 33,025-52] and volcanism confined within patera walls (``Lokian", Lopes et al., 2003). Understanding the Lokian eruption mechanism is particularly important because paterae are the most ubiquitous volcanic constructs on Io's surface [Radebaugh et al. 2001, JGR, 106, 33,005-33,020] and patera volcanism is the most common eruption type on Io. We use observations from Galileo's Near-Infrared Mapping Spectrometer (NIMS) and compare them with images from Galileo's Solid State Imaging system (SSI) to map the distribution of thermal emission at several Ionian paterae. This allows us to examine how thermal emission correlates with visible features, and to investigate how thermal emission varies with time. Galileo's close fly-bys of Io from 1999 to 2001 allowed NIMS to observe the volcanoes at relatively high spatial resolution (1-30 km pixel). At these scales, observations of the several paterae reveal that the greatest thermal emission occurs at the edges. This can be explained as the crust of a lava lake breaking up against the base of the patera (caldera) walls, similar to what has been observed at lava lakes on Earth. Comparison with terrestrial analogs shows that several Ionian active paterae, such as Loki, Tupan, and Emakong, have thermal properties consistent with relatively inactive lava lakes on Earth. We discuss these results and their implications for eruption styles and resurfacing on Io. This work was supported in part by NASA's Planetary Geology and Geophysics Program.

  13. 238U-230Th crystallization ages for the oldest domes of the Mono Craters, eastern California

    NASA Astrophysics Data System (ADS)

    Marcaida, M.; Vazquez, J. A.

    2014-12-01

    The Mono Craters volcanic chain is one of the youngest areas of rhyolitic volcanism in the Mono Lake-Long Valley region of eastern California. Located just south of Mono Lake, the Mono Craters comprise at least 28 individual domes and flows (numbered 3-30, north to south); however, the timing and frequency of eruptions remain poorly resolved. The earliest signs of volcanic activity are preserved as numerous tephra layers (Ashes 1-19, top to bottom) in the late Pleistocene Wilson Creek formation of ancestral Mono Lake, which indicate that rhyolitic volcanism from Mono Craters began by at least ca. 62 ka [1]. Although the current chronology indicates that most of the Mono Craters are younger than ca. 20 ka [2-4], similar compositions of titanomagnetite from both pumice and lava potentially correlate several Wilson Creek tephras to porphyritic biotite-bearing domes 11, 24, and 19 of the Mono Craters [5], suggesting that multiple domes in the Mono Craters chain reflect volcanism older than ca. 20 ka. Ash 3 is correlated to dome 11 based on similar ca. 20 ka ages and titanomagnetite compositions [6]. More recently, we performed ion microprobe 238U-230Th dating of unpolished rims of allanite and zircon from domes 24 and 19, yielding isochron ages of ca. 38 ka and ca. 42 ka, respectively. The age of dome 24 is consistent with the ca. 38 ka age of its potential correlative tephra layers [1, 5], indicating that dome 24 is likely the extrusive equivalent of Ashes 9-10. Dome 19 has titanomagnetite crystals with similar bimodal chemistry to titanomagnetites from Ash 15 [5]. The age of dome 19 is indistinguishable from the 238U-230Th age of Ash 15 [1], which erupted during a prominent geomagnetic excursion, originally designated as the "Mono Lake" excursion. Combining geochronological and titanomagnetite compositional data confirms that Ash 15 and its extrusive equivalent, dome 19, erupted during the Laschamp excursion. [1] Vazquez, J.A. and Lidzbarski, M.I. (2012) EPSL 357

  14. Physical volcanology of a voluminous rhyolite lava flow: The Badlands lava, Owyhee Plateau, southwestern Idaho

    NASA Astrophysics Data System (ADS)

    Manley, Curtis R.

    1996-05-01

    This paper describes an extraordinarily well preserved example of a large, high-SiO 2 rhyolite unit that by its exposed physical features can be demonstrated to be an effusive lava flow, not a rheomorphic ignimbrite. The Badlands lava flow of southwestern Idaho shows a multi-lobate form, with flow lobes that advanced along several azimuths from a long fissure vent. The lava flowed around one of its tephra ridges and a bedrock topographic high, creating a kipuka in the middle of the flow; the other tephra ridge was shoved aside by the lava. The lava itself is everywhere flow foliated, with foliation horizontal at the base, steepening toward the top, and convex in the direction of flow advance. The foliation parallels the margins of the flow lobes and reveals the position and orientation of the vent. Many samples of the lava flow's dense upper vitrophyre show one or more fragmental textures that formed by the settling of pumiceous and glassy debris into open fractures and the debris' subsequent welding into a rock that in many respects resembles welded tuff. By this process, the lava flow mimics an ignimbrite at the scale of an outcrop or thin section. Identical textures in other units have been cited as indicative of ash-flow emplacement mechanisms. The Badlands eruption tapped a stratified magma chamber, in which a large volume of phenocryst-rich (30 vol.%) magma underlay a small volume of magma more evolved and nearly aphyric. The lava flow shows mingling relations between the two magmas, with minor volumes of the aphyric magma occurring as early, small lava lobes and as individual layers in the dominant phenocryst-rich lava. Effusion of the 15 km 3 of rhyolite lava may have continued for as short as 6 or as long as 16 years, with effusion rates comparable to those observed at the Mount St. Helens dome. The Badlands lava had a pre-eruptive volatile content of about 2.75 wt.% H 2O or less, and erupted at approximately 830 °C, much lower than the temperatures of

  15. Lava flows and volcanic landforms

    NASA Astrophysics Data System (ADS)

    Tarquini, Simone

    2016-04-01

    Lava flows constitute a large portion of the edifice of basaltic volcanoes. The substantial difference existing between the emplacement dynamics of different basaltic lava flows suggests a relation between the dominant flow dynamic and the overall shape of the ensuing volcano. Starting from the seminal works of Walker (1971, 1973) it is proposed that the rate of heat dissipation per unit volume of lava can be the founding principium at the roots of the emplacement dynamics of lava flows. Within the general framework of the thermodynamics of irreversible processes, a conceptual model is presented, in which the dynamic of lava flows can evolve in a linear or in a nonlinear regime on the basis of the constraint active on the system: a low constraint promotes a linear dynamic (i.e. fluctuations are damped), a high constraint a nonlinear one (i.e. fluctuations are enhanced). Two cases are considered as end-members for a linear and a nonlinear dynamic in lava flows: the typical "Hawaiian" sheet flow and the classic "Etnean" channelized flow (respectively). In lava flows, the active constraint is directly proportional to the slope of the topography and to the thermal conductivity and thermal capacity of the surrounding environment, and is inversely proportional to the lava viscosity and to the supply rate. The constraint indicates the distance from the equilibrium conditions of the system, and determines the rate of heat dissipation per unit volume. In subaerial flows, the heat dissipated during the emplacement is well approximated by the heat lost through radiation, which can be retrieved through remote-sensing techniques and can be used to correlate dynamic and dissipation. The model presented recombines previously unrelated concepts regarding the dynamics and the thermal regimes observed in different lava flows, providing a global consistent picture. References Walker GPL (1971) Compound and simple lava flows and flood basalts. Bull Volcanol 35:579-590 Walker GPL (1973

  16. Multiple Uses of Hydrogen Isotopes as a Tracer of Rehydration Processes in Glassy Lavas

    NASA Astrophysics Data System (ADS)

    Cameron, B. I.; Fink, J. H.; Guan, Y.; Leshin, L. A.

    2001-12-01

    Silicic lava flows contain zones of enhanced vesicularity with high total H2O contents. This relationship between volatile content and vesicularity has promoted the monitoring of active lava domes using remote sensing techniques in an effort to forecast explosive activity. A persistent complication in attempts to relate surface texture to H2O content and explosivity was the confounding effect of meteoric H2O. Glassy and vesicular lavas exposed at the surface of the Earth for prolonged periods readily interact with meteoric H2O. Rehydration is a time-, temperature-, and porosity-dependent process governed by the slow diffusion of molecular H2O into the glass. This inevitable addition of secondary H2O obscures the spatial distribution of juvenile H2O in lava flows. The ability to distinguish magmatic from meteoric H2O in glassy lavas would help identify regions of overpressure on active domes and thereby improve hazard assessment. Three types of hydrogen isotopic studies of glassy lavas have been utilized to disentangle rehydration processes from primary magmatic ones. First, bulk hydrogen isotopic data on variably textured lava flows reveal enrichments in both δ D and total H2O as vesicularity increases. Mixing between a degassed magmatic and a partially evaporated meteoric H2O best explains the observed trend from lower δ D values in the interior massive obsidian samples to higher δ D in the most surficial vesicular pumice. Second, step-heated hydrogen isotopic analyses further prove that the vesicular samples contain a high percentage of meteoric H2O. Whereas dense massive obsidian samples release a large fraction of deuterium-depleted H2O at temperatures above 600° C, the bubble-rich pumiceous samples lose a majority of their H2O at temperatures below 400° C. Lastly, the Cameca 6f ion microprobe at ASU was used to measure hydrogen isotope transects into the vesicle-melt interface. The gradation from depleted δ D values in the glassy interstices to more

  17. Shapes of Venusian 'pancake' domes imply episodic emplacement and silicic composition

    NASA Astrophysics Data System (ADS)

    Fink, J. H.; Bridges, N. T.; Grimm, R. E.

    1993-02-01

    The main evidence available for constraining the composition of the large circular 'pancake' domes on Venus is their gross morphology. Laboratory simulations using polyethylene glycol show that the height to diameter (aspect) ratios of domes of a given total volume depend critically on whether their extrusion was continuous or episodic, with more episodes leading to greater cooling and taller domes. Thus without observations of their emplacement, the compositions of Venusian domes cannot be uniquely constrained by their morphology. However, by considering a population of 51 Venusian domes to represent a sampling of many stages during the growth of domes with comparable histories, and by plotting aspect ratio versus total volume, we find that the shapes of the domes are most consistent with episodic emplacement. On Earth this mode of dome growth is found almost exclusively in lavas of dacite to rhyolite composition, strengthening earlier inferences about the presence of evolved magmas on Venus.

  18. Shapes of Venusian 'pancake' domes imply episodic emplacement and silicic composition

    NASA Technical Reports Server (NTRS)

    Fink, Jonathan H.; Bridges, Nathan T.; Grimm, Robert E.

    1993-01-01

    The main evidence available for constraining the composition of the large circular 'pancake' domes on Venus is their gross morphology. Laboratory simulations using polyethylene glycol show that the height to diameter (aspect) ratios of domes of a given total volume depend critically on whether their extrusion was continuous or episodic, with more episodes leading to greater cooling and taller domes. Thus without observations of their emplacement, the compositions of Venusian domes cannot be uniquely constrained by their morphology. However, by considering a population of 51 Venusian domes to represent a sampling of many stages during the growth of domes with comparable histories, and by plotting aspect ratio versus total volume, we find that the shapes of the domes are most consistent with episodic emplacement. On Earth this mode of dome growth is found almost exclusively in lavas of dacite to rhyolite composition, strengthening earlier inferences about the presence of evolved magmas on Venus.

  19. A Volume Flux Approach to Cryolava Dome Emplacement on Europa

    NASA Technical Reports Server (NTRS)

    Quick, Lynnae C.; Fagents, Sarah A.; Hurford, Terry A.; Prockter, Louise M.

    2017-01-01

    We previously modeled a subset of domes on Europa with morphologies consistent with emplacement by viscous extrusions of cryolava. These models assumed instantaneous emplacement of a fixed volume of fluid onto the surface, followed by relaxation to form domes. However, this approach only allowed for the investigation of late-stage eruptive processes far from the vent and provided little insight into how cryolavas arrived at the surface. Consideration of dome emplacement as cryolavas erupt at the surface is therefore pertinent. A volume flux approach, in which lava erupts from the vent at a constant rate, was successfully applied to the formation of steep-sided volcanic domes on Venus. These domes are believed to have formed in the same manner as candi-date cryolava domes on Europa. In order to gain a more complete understanding of the potential for the emplacement of Europa domes via extrusive volcanism, we have applied this new volume flux approach to the formation of putative cryovolcanic domes on Europa. Assuming as in that europan cryolavas are briny, aqueous solutions which may or may not contain some ice crystal fraction, we present the results of this modeling and explore theories for the formation of low-albedo moats that surround some domes.

  20. Emplacement and composition of steep-sided domes on Venus

    NASA Astrophysics Data System (ADS)

    Stofan, Ellen R.; Anderson, Steven W.; Crown, David A.; Plaut, Jeffrey J.

    2000-11-01

    Steep-sided domes on Venus have surface characteristics that can provide information on their emplacement, including relatively smooth upper surfaces, radial and polygonal fracture patterns, and pits. These characteristics indicate that domes have surface crusts which are relatively unbroken, have mobile interiors after emplacement, and preserve fractures from only late in their history in response to endogenous growth or sagging of the dome surface. We have calculated the time necessary to form a 12-cm-thick crust for basalt and rhyolite under current terrestrial and Venusian ambient conditions. A 12-cm-thick crust will form in all cases in <10 hours. Although Venusian lava flows should develop a brittle carapace during emplacement, only late-stage brittle fractures are preserved at steep-sided domes. We favor an emplacement model where early-formed surface crusts are entrained or continually annealed as they deform to accommodate dome growth. Entrainment and annealing of fractures are not mutually exclusive processes and thus may both be at work during steep-sided dome emplacement. Our results are most consistent with basaltic compositions, as rhyolitic lavas would quickly form thick crusts which would break into large blocks that would be difficult to entrain or anneal. However, if Venus has undergone large temperature excursions in the past (producing ambient conditions of 800-1000 K [e.g., Bullock and Grinspoon, 1996, 1998]), rhyolitic lavas would be unable to form crusts at high surface temperatures and could produce domes with surface characteristics consistent with those of Venusian steep-sided domes.

  1. Tectonic events, continental intraplate volcanism, and mantle plume activity in northern Arabia: Constraints from geochemistry and Ar-Ar dating of Syrian lavas

    NASA Astrophysics Data System (ADS)

    Krienitz, M.-S.; Haase, K. M.; Mezger, K.; van den Bogaard, P.; Thiemann, V.; Shaikh-Mashail, M. A.

    2009-04-01

    New 40Ar/39Ar ages combined with chemical and Sr, Nd, and Pb isotope data for volcanic rocks from Syria along with published data of Syrian and Arabian lavas constrain the spatiotemporal evolution of volcanism, melting regime, and magmatic sources contributing to the volcanic activity in northern Arabia. Several volcanic phases occurred in different parts of Syria in the last 20 Ma that partly correlate with different tectonic events like displacements along the Dead Sea Fault system or slab break-off beneath the Bitlis suture zone, although the large volume of magmas and their composition suggest that hot mantle material caused volcanism. Low Ce/Pb (<20), Nb/Th (<10), and Sr, Nd, and Pb isotope variations of Syrian lavas indicate the role of crustal contamination in magma genesis, and contamination of magmas with up to 30% of continental crustal material can explain their 87Sr/86Sr. Fractionation-corrected major element compositions and REE ratios of uncontaminated lavas suggest a pressure-controlled melting regime in western Arabia that varies from shallow and high-degree melt formation in the south to increasingly deeper regions and lower extents of the beginning melting process northward. Temperature estimates of calculated primary, crustally uncontaminated Arabian lavas indicate their formation at elevated mantle temperatures (Texcess ˜ 100-200°C) being characteristic for their generation in a plume mantle region. The Sr, Nd, and Pb isotope systematic of crustally uncontaminated Syrian lavas reveal a sublithospheric and a mantle plume source involvement in their formation, whereas a (hydrous) lithospheric origin of lavas can be excluded on the basis of negative correlations between Ba/La and K/La. The characteristically high 206Pb/204Pb (˜19.5) of the mantle plume source can be explained by material entrainment associated with the Afar mantle plume. The Syrian volcanic rocks are generally younger than lavas from the southern Afro-Arabian region, indicating

  2. Tephra on Lava Flows Promotes Vegetation Development: Case Studies From Recent Holocene Lava Flows

    NASA Astrophysics Data System (ADS)

    Deligne, N. I.; Cashman, K. V.

    2011-12-01

    Volcanic eruptions re-surface landscapes rapidly with lava flows, pyroclastic deposits, or a combination of both. Whereas explosive deposits are generally fine grained and share many characteristics with fertile soil, lava does not - it is massive, fractured, and sterile rock. As such, barren lava presents a formidable challenge for plant colonization. However, most lava-forming eruptions have an explosive component, albeit often in the early stages of activity prior to lava emplacement when the magma still has a considerable gas fraction. Tephra from the explosive stage of an eruption blankets local and downwind areas, and tephra thickness decreases exponentially with distance from the vent. We examine several sites of Holocene volcanism in the United States, Mexico, and Italy and find that in the absence of tephra or external sources of soil, vegetation establishment and growth on lava flows is exceptionally slow. Conversely, lava flows with late stage syn-eruptive explosive activity or lava flows in areas with subsequent repeat volcanism have considerable vegetation development. Although thick tephra blankets hinder plant establishment, it appears that tephra deposits on lava flows provide a growth medium and enhances water retention, promoting plant colonization and vegetation development. Our results caution against the common practice of mapping lava flows based on vegetation, and provide new insights on key factors in plant establishment and growth on lava flows.

  3. Lava-snow interactions at Tolbachik 2012-13 eruption: comparison to recent field observations and experiments

    NASA Astrophysics Data System (ADS)

    Edwards, B. R.; Belousov, A.; Belousova, M.; Izbekov, P. E.; Bindeman, I. N.; Gardeev, E.; Muravyev, Y. D.; Melnikov, D.

    2013-12-01

    More than a dozen volcanic eruptions in the past twenty years have produced lava interaction with snow or ice, some of which have produced damaging floods/lahars. However, the factors controlling melting during lava-snow/ice interactions is not well understood. Recent observations from the presently ongoing eruption at Tolbachik, Kamchatka confirm some general observations from large-scale experiments, and recent eruptions (2010 Fimmvorduhals; Edwards et al, 2012), but also show new types of behavior not before described. The new observations provide further constraints on heat transfer between ice/snow and three different lava morphologies: ';a'a, pahoehoe, and toothpaste. ';A'a flows at Tolbachik commonly were able to travel over seasonal snow cover (up to 4 m thick), especially where the snow was covered by tephra within 1.5 km of the vent area. Locally, heated meltwater discharge events issued from beneath the front of advancing lava, even though snow observation pits dug in front of advancing ';a'a flows also showed that in some areas melting was not as extensive. Once, an ';a'a flow was seen to collapse through snow, generating short-lived phreatomagmatic/phreatic activity. Closer to the vent, pahoehoe flow lobes and sheet flows occasionally spilled over onto snow and were able to rapidly transit snow with few obvious signs of melting/steam generation. Most of these flows did melt through basal snow layers within 24 hours however. We were also able to closely observe ';toothpaste' lava flows ';intruding' into snow in several locations, including snow-pits, and to watch it pushing up through snow forming temporary snow domes. Toothpaste lava caused the most rapid melting and most significant volumes of steam, as the meltwater drained down into the intruding lava. Behaviour seen at Tolbachik is similar to historic (e.g., Hekla 1947; Einarrson, 1949) and recent observations (e.g. Fimmvorduhals), as well as large-scale experiments (Edwards et al., 2013). While

  4. Project LAVA.

    ERIC Educational Resources Information Center

    Nelson, Cheryl

    1998-01-01

    Describes a summer program for teachers in the Hawaii Volcanoes National Park in which teachers share in hands-on activities that demonstrate volcanic processes including volcanic hazards, plate tectonics, and earthquakes. (DDR)

  5. Emplacement of submarine lava flow fields: A geomorphological model from the Niños eruption at the Galápagos Spreading Center

    NASA Astrophysics Data System (ADS)

    McClinton, J. Timothy; White, Scott M.

    2015-03-01

    In the absence of any direct observations of an active submarine eruption at a mid-ocean ridge (MOR), our understanding of volcanic processes there is based on the interpretation of eruptive products. Submarine lava flow morphology serves as a primary indicator of eruption and emplacement processes; however, there is typically a lack of visual observations and bathymetric data at a scale and extent relevant to submarine lava flows, which display meter to submeter-scale morphological variability. In this paper, we merge submersible-based visual observations with high-resolution multibeam bathymetry collected by an autonomous underwater vehicle (AUV) and examine the fine-scale geomorphology of Niños, a submarine lava flow field at the Galápagos Spreading Center (GSC).We identify separate morphological facies (i.e., morphofacies) within the lava flow field, each having distinct patterns of lava flow morphology and volcanic structures. The spatial and stratigraphic arrangement of morphofacies suggests that they were emplaced sequentially as the eruption progressed, implying that the Niños eruption consisted of at least three eruptive phases. We estimate eruption parameters and develop a chronological model that describes the construction of the Niños lava flow field. An initial phase with high effusion rates emplaced sheet flows, then an intermediate phase emplaced a platform of lobate lavas, and then an extended final phase with low effusion rates emplaced a discontinuous row of pillow lava domes. We then compare this model to mapped lava flow fields at other MORs. Despite disparities in scale, the morphological similarities of volcanic features at MORs with different spreading rates suggest common emplacement processes that are primarily controlled by local magma supply.

  6. Chlorine degassing during the lava dome-building eruption of Mount St. Helens, 2004-2005: Chapter 27 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Edmonds, Marie; McGee, Kenneth A.; Doukas, Michael P.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    O is magmatic, and (or) (2) some Cl present as alkali chloride (NaCl and KCl) in the gas phase. The mean molar Cl/S is similar to gases measured at other silicic subductionzone volcanoes during effusive activity; this may be due to the influence of Cl in the vapor on S solubility in the melt, which produces a solubility maximum for S at vapor Cl/S ~1.

  7. Location and extent of recently active lava flows on the eastern flank of Idunn Mons on Venus

    NASA Astrophysics Data System (ADS)

    D'Incecco, Piero; Mueller, Nils; Helbert, Joern; D'Amore, Mario

    2016-10-01

    The eastern flank of Idunn Mons, Imdr Regio's single large volcano, was identified in VIRTIS data as one of the regions with relatively high values of thermal emissivity at 1 μm wavelength. Our study intends to identify location and extent of the sources of such anomalies, thus the lava flows responsible for the relatively high emissivity observed by VIRTIS over the eastern flank of Idunn Mons. We perform a simulation iterating the geologic mapping made over Magellan radar images of the same area with modeling of the blurring caused by the scattering of the 1 μm radiation in the atmosphere. At every iteration, we map the lava flow units in the surroundings of Idunn Mons and we assign each unit an assumed value of emissivity. We observed a good match between the mapped flows and the clusters resulting from the consistency of the mapped lava flows through the ISO clustering analysis. We tested eight different configurations, calculating the total RMS error compared to VIRTIS observations. The best-fit configuration is that where we assigned high values of emissivity to the flank lava flows. Results also show a correlation between the ISO clustering analysis and the best-fit configuration. We reconstructed the post-eruption stratigraphy of the eastern flank of Idunn Mons, displaying the three flank lava flows units likely responsible for the relatively high 1 μm emissivity anomalies observed by VIRTIS. The average microwave emissivity provides a further evidence of the basaltic composition of the mapped lava flows.

  8. Lunar Lava Tube Sensing

    NASA Technical Reports Server (NTRS)

    York, Cheryl Lynn; Walden, Bryce; Billings, Thomas L.; Reeder, P. Douglas

    1992-01-01

    Large (greater than 300 m diameter) lava tube caverns appear to exist on the Moon and could provide substantial safety and cost benefits for lunar bases. Over 40 m of basalt and regolith constitute the lava tube roof and would protect both construction and operations. Constant temperatures of -20 C reduce thermal stress on structures and machines. Base designs need not incorporate heavy shielding, so lightweight materials can be used and construction can be expedited. Identification and characterization of lava tube caverns can be incorporated into current precursor lunar mission plans. Some searches can even be done from Earth. Specific recommendations for lunar lava tube search and exploration are (1) an Earth-based radar interferometer, (2) an Earth-penetrating radar (EPR) orbiter, (3) kinetic penetrators for lunar lava tube confirmation, (4) a 'Moon Bat' hovering rocket vehicle, and (5) the use of other proposed landers and orbiters to help find lunar lava tubes.

  9. Introducing Kansas Lava

    NASA Astrophysics Data System (ADS)

    Gill, Andy; Bull, Tristan; Kimmell, Garrin; Perrins, Erik; Komp, Ed; Werling, Brett

    Kansas Lava is a domain specific language for hardware description. Though there have been a number of previous implementations of Lava, we have found the design space rich, with unexplored choices. We use a direct (Chalmers style) specification of circuits, and make significant use of Haskell overloading of standard classes, leading to concise circuit descriptions. Kansas Lava supports both simulation (inside GHCi), and execution via VHDL, by having a dual shallow and deep embedding inside our Signal type. We also have a lightweight sized-type mechanism, allowing for MATLAB style matrix based specifications to be directly expressed in Kansas Lava.

  10. Modular combustor dome

    NASA Technical Reports Server (NTRS)

    Glynn, Christopher Charles (Inventor); Halila, Ely Eskenazi (Inventor); Bibler, John David (Inventor); Morris, David Byron (Inventor)

    2001-01-01

    A combustor dome module includes a mixer tube having a hollow heat shield sealingly joined around the outlet end thereof. The modules may then be assembled in an array for defining the combustor dome, with each module being individually removable therefrom.

  11. Fast foldable tent domes

    NASA Astrophysics Data System (ADS)

    Jägers, Aswin P. L.; Sliepen, Guus; Bettonvil, Felix C. M.; Hammerschlag, Robert H.

    2008-07-01

    In the near future ELTs (Extreme Large Telescopes) will be built. Preferably these telescopes should operate without obstructions in the near surrounding to reach optimal seeing conditions and avoid large turbulences with wind-gust accelerations around large obstacles. This applies also to future large solar telescopes. At present two foldable dome prototypes have been built on the Canary Islands: the Dutch Open Telescope (DOT, La Palma) and the GREGOR Telescope (Tenerife), having a diameter of 7 and 9 meter, respectively. The domes are usually fully retracted during observations. The research consists of measurements on the two domes. New camera systems are developed and placed inside the domes for precise dome deformation measurements within 0.1 mm over the whole dome size. Simultaneously, a variety of wind-speed and -direction sensors measure the wind field around the dome. In addition, fast sensitive air-pressure sensors placed on the supporting bows measure the wind pressure. The aim is to predict accurately the expected forces and deformations on up-scaled, fully retractable domes to make their construction more economically. The dimensions of 7 and 9 meter are large enough for realistic on-site tests in gusty wind and will give much more information than wind tunnel experiments.

  12. Lava Flow at Kilauea, Hawaii

    NASA Technical Reports Server (NTRS)

    2007-01-01

    On July 21, 2007, the world's most active volcano, Kilauea on Hawaii's Big Island, produced a new fissure eruption from the Pu'u O'o vent, which fed an open lava channel and lava flows toward the east. Access to the Kahauale'a Natural Area Reserve was closed due to fire and gas hazards. The two Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) nighttime thermal infrared images were acquired on August 21 and August 30, 2007. The brightest areas are the hottest lava flows from the recent fissure eruption. The large lava field extending down to the ocean is part of the Kupaianaha field. The most recent activity there ceased on June 20, but the lava is still hot and appears bright on the images. Magenta areas are cold lava flows from eruptions that occurred between 1969 and 2006. Clouds are cold (black) and the ocean is a uniform warm temperature, and light gray in color. These images are being used by volcanologists at the U.S. Geological Survey Hawaii Volcano Observatory to help monitor the progress of the lava flows.

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

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

    The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud

  13. Use of thermal infrared imaging for monitoring renewed dome growth at Mount St. Helens, 2004: Chapter 17 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Schneider, David J.; Vallance, James W.; Wessels, Rick L.; Logan, Matthew; Ramsey, Michael S.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    A helicopter-mounted thermal imaging radiometer documented the explosive vent-clearing and effusive phases of the eruption of Mount St. Helens in 2004. A gyrostabilized gimbal controlled by a crew member housed the radiometer and an optical video camera attached to the nose of the helicopter. Since October 1, 2004, the system has provided thermal and video observations of dome growth. Flights conducted as frequently as twice daily during the initial month of the eruption monitored rapid changes in the crater and 1980-86 lava dome. Thermal monitoring decreased to several times per week once dome extrusion began. The thermal imaging system provided unique observations, including timely recognition that the early explosive phase was phreatic, location of structures controlling thermal emissions and active faults, detection of increased heat flow prior to the extrusion of lava, and recognition of new lava extrusion. The first spines, 1 and 2, were hotter when they emerged (maximum temperature 700-730°C) than subsequent spines insulated by as much as several meters of fault gouge. Temperature of gouge-covered spines was about 200°C where they emerged from the vent, and it decreased rapidly with distance from the vent. The hottest parts of these spines were as high as 500-730°C in fractured and broken-up regions. Such temperature variation needs to be accounted for in the retrieval of eruption parameters using satellite-based techniques, as such features are smaller than pixels in satellite images.

  14. Early life recorded in archean pillow lavas.

    PubMed

    Furnes, Harald; Banerjee, Neil R; Muehlenbachs, Karlis; Staudigel, Hubert; de Wit, Maarten

    2004-04-23

    Pillow lava rims from the Mesoarchean Barberton Greenstone Belt in South Africa contain micrometer-scale mineralized tubes that provide evidence of submarine microbial activity during the early history of Earth. The tubes formed during microbial etching of glass along fractures, as seen in pillow lavas from recent oceanic crust. The margins of the tubes contain organic carbon, and many of the pillow rims exhibit isotopically light bulk-rock carbonate delta13C values, supporting their biogenic origin. Overlapping metamorphic and magmatic dates from the pillow lavas suggest that microbial life colonized these subaqueous volcanic rocks soon after their eruption almost 3.5 billion years ago.

  15. Kaguyak dome field and its Holocene caldera, Alaska Peninsula

    USGS Publications Warehouse

    Fierstein, J.; Hildreth, W.

    2008-01-01

    Kaguyak Caldera lies in a remote corner of Katmai National Park, 375??km SW of Anchorage, Alaska. The 2.5-by-3-km caldera collapsed ~ 5.8 ?? 0.2??ka (14C age) during emplacement of a radial apron of poorly pumiceous crystal-rich dacitic pyroclastic flows (61-67% SiO2). Proximal pumice-fall deposits are thin and sparsely preserved, but an oxidized coignimbrite ash is found as far as the Valley of Ten Thousand Smokes, 80??km southwest. Postcaldera events include filling the 150-m-deep caldera lake, emplacement of two intracaldera domes (61.5-64.5% SiO2), and phreatic ejection of lakefloor sediments onto the caldera rim. CO2 and H2S bubble up through the lake, weakly but widely. Geochemical analyses (n = 148), including pre-and post-caldera lavas (53-74% SiO2), define one of the lowest-K arc suites in Alaska. The precaldera edifice was not a stratocone but was, instead, nine contiguous but discrete clusters of lava domes, themselves stacks of rhyolite to basalt exogenous lobes and flows. Four extracaldera clusters are mid-to-late Pleistocene, but the other five are younger than 60??ka, were truncated by the collapse, and now make up the steep inner walls. The climactic ignimbrite was preceded by ~ 200??years by radial emplacement of a 100-m-thick sheet of block-rich glassy lava breccia (62-65.5% SiO2). Filling the notches between the truncated dome clusters, the breccia now makes up three segments of the steep caldera wall, which beheads gullies incised into the breccia deposit prior to caldera formation. They were probably shed by a large lava dome extruding where the lake is today.

  16. Kaguyak dome field and its Holocene caldera, Alaska Peninsula

    NASA Astrophysics Data System (ADS)

    Fierstein, Judy; Hildreth, Wes

    2008-10-01

    Kaguyak Caldera lies in a remote corner of Katmai National Park, 375 km SW of Anchorage, Alaska. The 2.5-by-3-km caldera collapsed ~ 5.8 ± 0.2 ka ( 14C age) during emplacement of a radial apron of poorly pumiceous crystal-rich dacitic pyroclastic flows (61-67% SiO 2). Proximal pumice-fall deposits are thin and sparsely preserved, but an oxidized coignimbrite ash is found as far as the Valley of Ten Thousand Smokes, 80 km southwest. Postcaldera events include filling the 150-m-deep caldera lake, emplacement of two intracaldera domes (61.5-64.5% SiO 2), and phreatic ejection of lakefloor sediments onto the caldera rim. CO 2 and H 2S bubble up through the lake, weakly but widely. Geochemical analyses ( n = 148), including pre-and post-caldera lavas (53-74% SiO 2), define one of the lowest-K arc suites in Alaska. The precaldera edifice was not a stratocone but was, instead, nine contiguous but discrete clusters of lava domes, themselves stacks of rhyolite to basalt exogenous lobes and flows. Four extracaldera clusters are mid-to-late Pleistocene, but the other five are younger than 60 ka, were truncated by the collapse, and now make up the steep inner walls. The climactic ignimbrite was preceded by ~ 200 years by radial emplacement of a 100-m-thick sheet of block-rich glassy lava breccia (62-65.5% SiO 2). Filling the notches between the truncated dome clusters, the breccia now makes up three segments of the steep caldera wall, which beheads gullies incised into the breccia deposit prior to caldera formation. They were probably shed by a large lava dome extruding where the lake is today.

  17. New approaches to inferences for steep-sided domes on Venus

    NASA Astrophysics Data System (ADS)

    Quick, Lynnae C.; Glaze, Lori S.; Baloga, Stephen M.; Stofan, Ellen R.

    2016-06-01

    New mathematical approaches for the relaxation and emplacement of viscous lava domes are presented and applied to steep-sided domes on Venus. A similarity solution approach is applied to the governing equation for fluid flow in a cylindrical geometry for two distinct scenarios. In the first scenario, dome relaxation is explored assuming a constant volume of fluid (i.e. lava) has been rapidly emplaced onto the surface. Cooling of lava is represented by a time-variable viscosity and singularities inherent in previous models for dome relaxation have been eliminated. At the onset of relaxation, bulk dynamic viscosities lie in the range between 1010-1016 Pa s, consistent with basaltic-andesite to rhyolitic compositions. Plausible relaxation times range from 5 to 5000 years, depending on initial lava viscosity. The first scenario, however, is only valid during the final stages of dome relaxation and does not consider the time taken for lava to be extruded onto the surface. In the second scenario, emplacement and growth of a steep-sided dome is considered when the volume of lava on the surface increases over time (i.e. time-variable volume approach). The volumetric flowrate may depend on an arbitrary power of the dome thickness, thus embracing Newtonian as well as other rheologies for describing terrestrial and planetary mass flows. The approach can be used to distinguish between basic flowrate models for fluid emplacement. The formalism results in radial expansion of a dome proportional to t1/2, consistent with the diffusive nature of the governing equation. The flow at the front is shown to thicken as the front advances for a constant rate of lava supply. Emplacement times are intimately correlated with the bulk rheology. Comparison of the theoretical profiles with the shape of a typical dome on Venus indicates that a Newtonian bulk rheology is most appropriate, consistent with prior studies. However, results here suggest a bulk dynamic viscosity of 1012-1013 Pa s and

  18. Improvement of a 2D numerical model of lava flows

    NASA Astrophysics Data System (ADS)

    Ishimine, Y.

    2013-12-01

    I propose an improved procedure that reduces an improper dependence of lava flow directions on the orientation of Digital Elevation Model (DEM) in two-dimensional simulations based on Ishihara et al. (in Lava Flows and Domes, Fink, JH eds., 1990). The numerical model for lava flow simulations proposed by Ishihara et al. (1990) is based on two-dimensional shallow water model combined with a constitutive equation for a Bingham fluid. It is simple but useful because it properly reproduces distributions of actual lava flows. Thus, it has been regarded as one of pioneer work of numerical simulations of lava flows and it is still now widely used in practical hazard prediction map for civil defense officials in Japan. However, the model include an improper dependence of lava flow directions on the orientation of DEM because the model separately assigns the condition for the lava flow to stop due to yield stress for each of two orthogonal axes of rectangular calculating grid based on DEM. This procedure brings a diamond-shaped distribution as shown in Fig. 1 when calculating a lava flow supplied from a point source on a virtual flat plane although the distribution should be circle-shaped. To improve the drawback, I proposed a modified procedure that uses the absolute value of yield stress derived from both components of two orthogonal directions of the slope steepness to assign the condition for lava flows to stop. This brings a better result as shown in Fig. 2. Fig. 1. (a) Contour plots calculated with the original model of Ishihara et al. (1990). (b) Contour plots calculated with a proposed model.

  19. Martian Lava Flows

    NASA Technical Reports Server (NTRS)

    2005-01-01

    19 October 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows lava flows at the southeast base of the giant volcano, Olympus Mons. The flat plain in the south-southeast (bottom/lower right) portion of the image is younger than and cuts off the ends of many of the lava flows that came from the northwest (upper left). Many of the lava flows in this image exhibit channels with levees bounding their margins. As each lava flow was advancing, its outer margins cooled and hardened, forming a channel or tube through which the molten rock continued to advance.

    Location near: 17.2oN, 129.0oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Winter

  20. Pressure Dome for High-Pressure Electrolyzer

    NASA Technical Reports Server (NTRS)

    Norman, Timothy; Schmitt, Edwin

    2012-01-01

    A high-strength, low-weight pressure vessel dome was designed specifically to house a high-pressure [2,000 psi (approx. = 13.8 MPa)] electrolyzer. In operation, the dome is filled with an inert gas pressurized to roughly 100 psi (approx. = 690 kPa) above the high, balanced pressure product oxygen and hydrogen gas streams. The inert gas acts to reduce the clamping load on electrolyzer stack tie bolts since the dome pressure acting axially inward helps offset the outward axial forces from the stack gas pressure. Likewise, radial and circumferential stresses on electrolyzer frames are minimized. Because the dome is operated at a higher pressure than the electrolyzer product gas, any external electrolyzer leak prevents oxygen or hydrogen from leaking into the dome. Instead the affected stack gas stream pressure rises detectably, thereby enabling a system shutdown. All electrical and fluid connections to the stack are made inside the pressure dome and require special plumbing and electrical dome interfaces for this to be accomplished. Further benefits of the dome are that it can act as a containment shield in the unlikely event of a catastrophic failure. Studies indicate that, for a given active area (and hence, cell ID), frame outside diameter must become ever larger to support stresses at higher operating pressures. This can lead to a large footprint and increased costs associated with thicker and/or larger diameter end-plates, tie-rods, and the frames themselves. One solution is to employ rings that fit snugly around the frame. This complicates stack assembly and is sometimes difficult to achieve in practice, as its success is strongly dependent on frame and ring tolerances, gas pressure, and operating temperature. A pressure dome permits an otherwise low-pressure stack to operate at higher pressures without growing the electrolyzer hardware. The pressure dome consists of two machined segments. An O-ring is placed in an O-ring groove in the flange of the bottom

  1. Basaltic Lava Channels

    NASA Astrophysics Data System (ADS)

    Cashman, K. V.; Griffiths, R. W.; Kerr, R. C.

    2004-12-01

    In Hawaii, the mode of lava transport - through open channels or through insulating lava tubes - determines the thermal, rheological, and emplacement history of a lava flow. Most Hawaiian lavas are erupted at near-liquidus temperatures and are therefore crystal-poor; lava transport through open channels allows rapid cooling and consequent rapid increases in lava crystallinity. Solidified aa flows resulting from channelized flow are typically fine-grained throughout their thickness, indicating cooling of the entire flow thickness during transport. In contrast, transport of lava through insulating tubes permits flow over long distances with little cooling. Flows emerging from such tubes typically have pahoehoe flow surfaces with glassy crusts. Groundmass textures that coarsen from the flow rind to the interior reflect rates of post-emplacement, rather than syn-emplacement, cooling. To distinguish eruption conditions that result in lava channels from those that allow formation of lava tubes, we have performed a series of laboratory experiments involving injection of PEG 600 (a wax with a Newtonian rheology and freezing temperature of 19ºC) into cold water through both uniform and non-uniform sloping channels. In uniform channels, tube formation can be distinguished from open channel flow using a dimensionless parameter based on a solidification time scale, an advection time scale, and a Rayleigh number that describes convection by heat loss from crust-free shear zones. Theoretical analysis predicts that in the open channel regime, the width of the crust (dc) will vary with the channel width (W) as dc = W5/3. Crustal coverage of non-uniform channels in both laboratory experiments and field examples from Kilauea Volcano, Hawaii, is consistent with this prediction. However, experiments in non-uniform channels illustrate additional controls on the surface coverage of lava channels. Most important is crustal extension resulting from flow acceleration through constrictions

  2. Petrology and Mineralogy of Lava and Ash Erupted From Colima Volcano (Mexico) During 1999-2005

    NASA Astrophysics Data System (ADS)

    Luhr, J. F.; Navarro-Ochoa, C.; Savov, I.

    2005-12-01

    Lava (n=8) and bulk ash samples (n=6) erupted between July 1999 and June 2005 were investigated to extend time-series compositional and textural studies of the products erupted from Volcán Colima since 1869. In particular, we seek to evaluate the possibility that the current activity will culminate in a major explosive Plinian-style event similar to that in 1913 (VEI=4). Lava samples continue to show relatively heterogeneous whole-rock compositions with some significant mafic spikes (1999, 2001) as have prevailed since 1976. Groundmass SiO2 contents continue trends to lower levels that have prevailed since 1961, in the direction of the still lower groundmass SiO2 contents found in 1913 scoriae. Importantly, ash samples from investigated Vulcanian-style explosive eruptions in 2005 are devoid of particles with micro-vesiculated groundmass textures; such textures characterized the 1913 scoriae, signifying expansion of in-situ magmatic gas as the propellant of the 1913 eruption. All magmas erupted since 1913 appear to have arrived in the upper volcanic conduit system in a degassed state. The small to moderate Vulcanian-style explosive eruptions, which have been common since 1999, have blasted ash clouds as high as 11 km a.s.l. and sent pyroclastic flows out to distances of 5 km. These eruptions do not appear to be powered by expansion of in-situ magmatic gas. New small lava domes have been observed in the crater prior to many explosive eruptions. These plugs of degassed lava may temporarily seal the conduit and allow build-up of magmatic gases streaming upward from below ahead of rising and degassing magma. In this interpretation, when gas pressure exceeds the strength of the plug seal in the upper conduit, an explosive Vulcanian-style eruption occurs.

  3. Rapid dome growth at Montagne Pelée during the early stages of the 1902 1905 eruption: a reconstruction from Lacroix's data

    NASA Astrophysics Data System (ADS)

    Tanguy, Jean-Claude

    2004-10-01

    Information obtained from various parts of the two books on Montagne Pelée by Lacroix enables an estimate to be made of the size of l’Etang Sec summit crater, the volume of the 1902 1905 lava dome and its growth rate at various stages of development. During the week preceding the 8 May nuée ardente, dome growth was between 28 and 38 m3 s 1, leading to a volume of 17 23×106 m3 on the morning of the catastrophe. Considering that significant parts of the dome (~1/3?) were removed by the 8 and 20 May climactic eruptions, a high magmatic flux could have continued until at least 27 May, when the total remaining volume was estimated to 53×106 m3. After moderate activity in June July (of order 10 m3 s 1), vigorous dome growth resumed dramatically, leading to the third climactic eruption of 30 August (a true calculation for this period being not feasible because of poor quality of the data). From November 1902 to July 1903 most of the effusive activity was concentrated in the great spine (erupted volume ~15×106 m3, magma flux 1.2 m3 s 1), which was eventually destroyed by collapse and minor nuées ardentes. The end of the eruption was characterized by a very low effusion rate, <1 m3 s 1 in average from August 1903 to October 1905.

  4. Pancakelike domes on Venus

    NASA Technical Reports Server (NTRS)

    Mckenzie, Dan; Ford, Peter G.; Liu, Fang; Pettengill, Gordon H.

    1992-01-01

    The shape of seven large domes on the plains of Venus, with volumes between 100 and 1000 cu km, is compared with that of an axisymmetric gravity current spreading over a rigid horizontal surface. Both the altimetric profiles and the horizontal projection of the line of intersection of domes on the SAR images agree well with the theoretical similarity solution for a newtonian fluid, but not with the shape calculated for a rigid-plastic rheology, nor with that for a static model with a strong skin. As a viscous current spreads, it generates an isotropic strain rate tensor whose magnitude is independent of radius. Such a flow can account for the randomly oriented cracks that are uniformly distributed on the surface of the domes. The stress induced by the flow in the plains material below is obtained, and is probably large enough to produce the short radial cracks in the surface of the plains beyond the domes. The viscosity of the domes can be estimated from their thermal time constants if spreading is possible only when the fluid is hot, and lies between 10(exp 14) and 10(exp 17) Pa s. Laboratory experiments show that such viscosities correspond to temperatures of 610 - 690 C in dry rhyolitic magmas. These temperatures agree with laboratory measurements of the solidus temperature of wet rhyolite. These results show that the development of the domes can be understood using simple fluid dynamical ideas, and that the magmas involved can be produced by wet melting at depths below 10 km, followed by eruption and degassing.

  5. The 2013-2014 Effusive Eruption of Sinabung Volcano, Sumatra, Indonesia: Satellite Thermal Observations and Ground-Based Photogrammetry of a Growing Lava Lobe

    NASA Astrophysics Data System (ADS)

    Carr, B. B.; Vanderkluysen, L.; Clarke, A. B.

    2014-12-01

    Sinabung is a 2460 m high andesitic volcano located in northern Sumatra, Indonesia. Sinabung had no confirmed historical activity until a small (VEI 2) explosive eruption in August-September 2010. In September 2013, explosions began again and were accompanied by lava dome growth and subsequent dome-collapse generated pyroclastic flows (Bulletin of the Global Volcanism Network 35:07; 39:01). The Center for Volcanology and Geological Hazard Mitigation (Indonesia) estimated dome growth at 3.5 m3/s in late December 2013. From January to March 2014 lava extrusion continued and formed a lobe down Sinabung's south flank. As of this writing, effusion and growth of the lava lobe continues, but at a much slower rate. Pyroclastic flows generated by collapse of the steep sides of the lobe remain a hazard. We use thermal infrared (TIR) images from the Moderate Resolution Imaging Spectroradiomter (MODIS) to observe volcanic activity at Sinabung during the 2013-2014 eruption and estimate effusion rates following the methods of Harris & Ripepe (2007, Geophys. Res. Let. 34). We also use new analysis of those thermal images to characterize style of activity, distinguishing pyroclastic flow activity from pure lava lobe growth. Preliminary results from satellite images show an average effusion rate of 1.1 m3/s during January-March 2014, with peak effusion rates from individual TIR images of 4-7 m3/s in mid-January. These numbers are in good agreement with the ground-based estimates, and they provide improved temporal resolution of the activity as it evolved. Since March, effusion rates have decreased to below 0.01 m3/s on average. Using the MODIS images, we estimate the maximum possible total erupted volume to be 7 million m3, and have constrained the accuracy of this estimate using Structure-from-Motion (SfM) photogrammetry from ground-based visual images of the lava lobe. Following explosions in 2010 and 2013 and high effusion rates from January to March 2014, the ongoing slow

  6. The mechanics of ground deformation precursory to dome-building extrusions at Mount St. Helens 1981-1982.

    USGS Publications Warehouse

    Chadwick, W.W.; Archuleta, R.J.; Swanson, D.A.

    1988-01-01

    Detailed monitoring at Mount St. Helens since 1980 has enabled prediction of the intermittent eruptive activity (mostly dome growth) with unprecedented success. During 1981 and 1982, accelerating deformation of the crater floor around the vent (including radial cracks, thrust faults, and ground tilt) was the earliest indicator of impending activity. The magnitude of the shear stress required to match observed dipslacements (1-7 MPa) is inversely proportional to the conduit diameter (estimated to be 25-100 m). The most probable source of this shear stress is the flow of viscous magma up to the conduit and into the lava dome. A model is proposed in which the accelerating deformation, beginning as much as 4 weeks before extrusions, is caused by the increasing velocity of ascending magma in the conduit. This model is examined by using deformation data of the dome before four extrusions in 1981 and 1982 to estimate the volumetric flow rate through the conduit. This flow rate and an estimate of the effective viscosity of the magma enable calculation of an ascent velocity and an applied shear stress that, again, depend on the conduit diameter. The results of these calculations are consistent with the finite element experiments and show that the proposed model is feasible. Precursory deformation like that measured at Mount St. Helens should be observable at similar volcanoes elsewhere because it is caused by the fundamental process of magma ascent.-from Authors

  7. The foaming of lavas

    NASA Technical Reports Server (NTRS)

    Okeefe, J. A.; Walton, W.

    1976-01-01

    Foaming is of great practical and theoretical significance for volcanic processes on the earth, the moon, and perhaps the meteorite parent bodies. The theory of foams agrees with steelmaking experience to indicate that their presence depends on the existence of solutes in the lavas which reduce the surface tension, and are not saturated. These solutes concentrate at the surface, and are called surfactants. The surfactant responsible for the formation of volcanic ash was not identified; it appears to be related to the oxygen partial pressure above the lava. This fact may explain why lunar and meteoritic melts are not observed to foam. Experimental studies are needed to clarify the process.

  8. Rigidity of lattice domes

    NASA Technical Reports Server (NTRS)

    Savelyev, V. A.

    1979-01-01

    The means of ensuring total rigidity of lattice domes, using comparison with solid shells of 1-3 layers are discussed. Irregularities of manufacture, processing, and other factors are considered, as they relate to diminution of rigidity. The discussion uses the concepts of upper and lower critical loads on the structure in question.

  9. Lava Flows in Eastern Tharsis

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 31 May 2002) This image may at first appear somewhat bland -- there is little contrast in the surface materials due to dust cover, and there are few impact craters -- but there are some very interesting geologic features here. The great Tharsis volcanoes have produced vast fields of lava flows, such as those shown in this image, to the east of Tharsis Tholus. The flows in this image have moved from west to east, down the regional topographic slope. The lobate edges of the flows are distinctive, and permit the discrimination of many overlapping individual flows that may represent tens, hundreds, thousands, or even millions of years worth of volcanic activity (overlapping relationships are especially evident at the bottom of the image). Viewed at full resolution, the image reveals interesting patterns and textures on the top surfaces of these flows. In particular, at the top of the image, there are numerous parallel curved ridges visible on the upper surfaces of the lava flows. These ridges make the flow surface look somewhat ropy, and at smaller scales this flow might be referred to as pahoehoe, indicative of a relatively fluid type of lava flow. At the scales observed here, however, these features are probably better referred to as pressure ridges. Pressure ridges form on the surface of a lava flow when the upper part of the flow is exposed to air, freezing it, but the insulated unfrozen interior of the flow continues to move down slope (and more material is pushed forward from behind), causing the surface to compress and pile up like a rug. Rough-looking flows with less distinct (more random) patterns on their surfaces may be flows that are more like terrestrial a'a flows, which are distinguished from pahoehoe flows by their higher viscosities and effusion rates. Near the center of the image there is an east-west trending, smooth-floored depression. The somewhat continuous width of this depression suggests that it is not simply formed by the edges of two

  10. High-resolution Digital Mapping of Historical Lava Flows as a Test-bed for Lava Flow Models

    NASA Astrophysics Data System (ADS)

    Pyle, D. M.; Parks, M.; Nomikou, P.; Mather, T. A.; Simou, E.; Kalnins, L. M.; Paulatto, M.; Watts, A. B.

    2013-12-01

    Quantitative analysis of high-resolution lava flow morphology can improve our understanding of past effusive eruptions by providing insight into eruptive processes and the rheological properties of erupted magmas. We report the results of an ongoing investigation into the young dacite lava flows of the Kameni islands, Santorini volcano, Greece, which were emplaced during both subaerial and shallow submarine eruptions over the past 3000 years. Historical eruptions of the Kameni islands since 1866 have been very carefully documented in contemporaneous scientific reports. Eruptions since 1573 appear to be time-predictable, with a close relationship between eruption length, the size of extruded lava domes, and the time elapsed since the previous eruption. A new NERC - Airborne Survey and Research Facility LiDAR survey of the Kameni islands was completed in May 2012, using a Leica ALS50 Airborne Laser Scanner mounted on a Dornier 228 aircraft. The topographic surface was mapped at an average point density of 2.1 points per square metre, and covers the entire extent of the youngest subaerial lava flow fields on Santorini. A 2-m DEM derived from the 2012 LiDAR dataset was merged with a 5-m resolution bathymetric grid, based on multibeam surveys carried out by the Hellenic Centre for Marine Research, during cruises in 2001 and 2006, using a SEABEAM 2120 hull-mounted swath system. The resultant grid provides the first high resolution map of both subaerial and submarine historic lava flows emplaced in the centre of the Santorini caldera, and includes several previously unidentified submarine flows and cones. Attribute maps were used to delineate and identify discrete lava flows both onshore and offshore; and morphometric profiles were used to compute accurate volumetric estimates for each of the historic flows, and to determine bulk rheological properties of the lavas, assuming a Bingham rheology. This ongoing work will improve our analysis of the relationship between

  11. Venus - Complex Lava Flows at Sif Mons

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This is a full resolution mosaic centered at 25 degrees north latitude, 351 east longitude. The region is approximately 160 kilometers (100 miles) across. It shows a series of complex lava flows which emerge from the northern flank of Sif Mons, a large volcano just to the south. Several of the flows occupy narrow troughs formed by long fractures. A sequence of events that can be inferred from this image is the formation of the dark background plains by eruptions of extremely fluid volcanic material, and the formation of the small shield volcanoes on the plains surface that can be seen in the upper left part of the image. Next, the region was domed upward probably by heat from the interior of Venus that ultimately caused magmas to break out from the surface near the summit regions forming the Sif volcanic structure and its associated flank eruptions which can be seen in this image.

  12. Flood lavas on Earth, Io and Mars

    USGS Publications Warehouse

    Keszthelyi, L.; Self, S.; Thordarson, T.

    2006-01-01

    Flood lavas are major geological features on all the major rocky planetary bodies. They provide important insight into the dynamics and chemistry of the interior of these bodies. On the Earth, they appear to be associated with major and mass extinction events. It is therefore not surprising that there has been significant research on flood lavas in recent years. Initial models suggested eruption durations of days and volumetric fluxes of order 107 m3 s-1 with flows moving as turbulent floods. However, our understanding of how lava flows can be emplaced under an insulating crust was revolutionized by the observations of actively inflating pahoehoe flows in Hawaii. These new ideas led to the hypothesis that flood lavas were emplaced over many years with eruption rates of the order of 104 m3 s-1. The field evidence indicates that flood lava flows in the Columbia River Basalts, Deccan Traps, Etendeka lavas, and the Kerguelen Plateau were emplaced as inflated pahoehoe sheet flows. This was reinforced by the observation of active lava flows of ??? 100 km length on Io being formed as tube-fed flow fed by moderate eruption rates (102-103 m3 s-1). More recently it has been found that some flood lavas are also emplaced in a more rapid manner. New high-resolution images from Mars revealed 'platy-ridged' flood lava flows, named after the large rafted plates and ridges formed by compression of the flow top. A search for appropriate terrestrial analogues found an excellent example in Iceland: the 1783-1784 Laki Flow Field. The brecciated Laki flow top consists of pieces of pahoehoe, not aa clinker, leading us to call this 'rubbly pahoehoe'. Similar flows have been found in the Columbia River Basalts and the Kerguelen Plateau. We hypothesize that these flows form with a thick, insulating, but mobile crust, which is disrupted when surges in the erupted flux are too large to maintain the normal pahoehoe mode of emplacement Flood lavas emplaced in this manner could have

  13. Shape and thermal modeling of the possible cryovolcanic dome Ganesa Macula on Titan: Astrobiological implications

    NASA Astrophysics Data System (ADS)

    Neish, C. D.; Lorenz, R. D.; O'Brien, D. P.; Cassini RADAR Team

    2005-08-01

    Observations of Titan by the Cassini spacecraft have revealed to us a world with an intricate and varied geology. In particular, there is evidence of extensive cryovolcanism. The 180 km structure Ganesa Macula observed in SAR imaging from Cassini's TA encounter in October 2004 resembles the pancake domes seen on Venus by the Magellan spacecraft and is comparable (in terms of years of planetary heatflow required to melt the lava volume) with the Deccan Traps on Earth. Cryovolcanism has important astrobiological implications, as it provides a means of exposing surface organics to liquid water. Aqueous chemistry permits Titan's hydrocarbons and nitriles to form more evolved and oxidized prebiotic species, such as amino acids and pyrimidines. In this work, we use Titan's observed backscatter function to model the radar appearance of domes of various shapes and heights to compare with the image of Ganesa: the SAR data are better fit by a ``spreading viscous drop" (``Huppert") shape than by one constrained by a skin strength (``Nye"). We then model the freezing of the model dome using a finite-element heat conduction code. Estimation of the dome height is presently underway, but even a dome only 1 km in height takes some 5 x 103 years to freeze for lava made entirely of liquid water, and 12 x 103 years for lava made of ammonia dihydrate. These timescales open a window for prebiotic chemistry far wider than can be explored in terrestrial laboratory experiments. This work was supported by the Cassini project.

  14. LAVA Applications to Open Rotors

    NASA Technical Reports Server (NTRS)

    Kiris, Cetin C.; Housman, Jeff; Barad, Mike; Brehm, Christoph

    2015-01-01

    Outline: LAVA (Launch Ascent Vehicle Aerodynamics); Introduction; Acoustics Related Applications; LAVA Applications to Open Rotor; Structured Overset Grids; Cartesian Grid with Immersed Boundary; High Speed Case; High Speed Case with Plate Low Speed Case.

  15. Eruptive behavior of the Marum/Mbwelesu lava lake, Vanuatu and comparisons with lava lakes on Earth and Io

    NASA Astrophysics Data System (ADS)

    Radebaugh, Jani; Lopes, Rosaly M.; Howell, Robert R.; Lorenz, Ralph D.; Turtle, Elizabeth P.

    2016-08-01

    Observations from field remote sensing of the morphology, kinematics and temperature of the Marum/Mbwelesu lava lake in the Vanuatu archipelago in 2014 reveal a highly active, vigorously erupting lava lake. Active degassing and fountaining observed at the 50 m lava lake led to large areas of fully exposed lavas and rapid ( 5 m/s) movement of lava from the centers of upwelling outwards to the lake margins. These rapid lava speeds precluded the formation of thick crust; there was never more than 30% non-translucent crust. The lava lake was observed with several portable, handheld, low-cost, near-infrared imagers, all of which measured temperatures near 1000 °C and one as high as 1022 °C, consistent with basaltic temperatures. Fine-scale structure in the lava fountains and cooled crust was visible in the near infrared at 5 cm/pixel from 300 m above the lake surface. The temperature distribution across the lake surface is much broader than at more quiescent lava lakes, peaking 850 °C, and is attributed to the highly exposed nature of the rapidly circulating lake. This lava lake has many characteristics in common with other active lava lakes, such as Erta Ale in Ethiopia, being confined, persistent and high-temperature; however it was much more active than is typical for Erta Ale, which often has > 90% crust. Furthermore, it is a good analogue for the persistent, high-temperature lava lakes contained within volcanic depressions on Jupiter's moon Io, such as Pele, also believed from spacecraft and ground-based observations to exhibit similar behavior of gas emission, rapid overturn and fountaining.

  16. After-Hours Science: Gee, A Dome!

    ERIC Educational Resources Information Center

    Santos, John G.

    1984-01-01

    Nature's Classroom (Southbridge, MA), which provides field experiences, academic classes, and activities in the natural sciences, has been recognized as an outstanding program by the National Science Teachers Association's Search for Excellence in Science Education project. Various program activities (including building a geodesic dome) are…

  17. Felsic lavas of Terceira Island, Azores: distribution, morphology and mode of emplacement

    NASA Astrophysics Data System (ADS)

    Pimentel, Adriano

    2010-05-01

    Terceira Island in the Azores archipelago is a remarkable example of effusive felsic volcanism. It is located in a geodynamic setting dominated by the WNW-ESE slow-spreading Terceira Rift that separates the Eurasian and Nubia plates, east of the Mid-Atlantic Ridge. Terceira differs from the other islands of the archipelago for the abundance of peralkaline felsic domes and coulees, which are the product with the largest volumetric expression (4.1 km3 DRE) in the recent eruptive history of the island (< 20 ka). These lavas fill and overflow the calderas of Pico Alto and Santa Bárbara volcanoes, but also occur along the flanks of the two volcanoes. Morphological, morphometric and geological analysis provided the means to constraint the emplacement modes of these peralkaline felsic lavas. From the spatial distribution of the eruptive centres it was possible to determine the presence of extensive WNW-ESE, NW-SE and ENE-WSW alignments, suggesting that these lavas were fed from depth by dykes strongly influenced by regional stress fields, although sometimes locally subjugated by magmatic stress. Lavas from both volcanoes are peralkaline trachytes and comendites very uniform in appearance with black, scoriaceous, rubbly surfaces, ranging from almost aphyric to porphyritic. They show surface morphologies typical of viscous magmas such as ogive-like rigdes, convex in the direction of flow, high levees, lava channels and spines. The lava domes are 14-183 m in height, with radius of 50-372 m, ranging in volume from 7x104 to 4x107 m3. Coulees can reach lengths in excess of 2800 m, with widths ranging from 110 to 900 m and thicknesses of 15-70 m. The calculated volumes range from about 3x105 to 108 m3. The morphometric analysis indicate that domes follow a geometrical growth pattern of low domes (H = 0,36R), dominated essentially by an endogenous regime, although exogenous growth involving extrusions of small lobes is also present. This suggests a low magma viscosity at time of

  18. Noble gas isotopic ratios from historical lavas and fumaroles at Mount Vesuvius (southern Italy): constraints for current and future volcanic activity

    NASA Astrophysics Data System (ADS)

    Tedesco, Dario; Nagao, Keisuke; Scarsi, Paolo

    1998-12-01

    Helium, neon and argon isotope ratios have been analysed from phenocrysts of eleven lava samples belonging to the last eruptive cycle of Mount Vesuvius (1631 until 1944). The phenocrysts separates include pyroxene ( N=10) and olivine ( N=1). All phenocryst samples show similarly low gas contents (He, Ne and Ar ˜10 -10 cm 3/g). 3He/ 4He ratios, 5.3-2.11 Ra, are generally low if compared to those typical of the MORB and those of the European Subcontinental Mantle (ESCM), respectively R/ Ra 8.5±1 and 6.0-6.5. A decreasing trend is found from 1631 to 1796, while a more homogeneous set of data is obtained for more recent eruptions, as evidenced by an average R/ Ra value of 2.85. Neon ratios ( 21Ne/ 22Ne and 20Ne/ 22Ne) strongly differ from those typically found on volcanoes and suggest that a crustal component has been added in the source region to Mt. Vesuvius magmas. Argon ratios ( 40Ar/ 36Ar and 38Ar/ 36Ar) have values similar to the atmosphere and are well correlated. The low 40Ar/ 36Ar ratio (max. 302) is, however, in the range of the 40Ar/ 36Ar ratios obtained from several lava samples at other Italian volcanoes and might be considered to have a deep origin. Two hypothesis have been discussed: (1) a deep argon-like-air source, due to subduction of air-rich sediments and/or (2) a preferential loss of Ar, in comparison to lighter noble gases, from silicic melts. Helium isotopic analysis of gas samples recently collected from crater and submarine fumaroles are similar to those of lavas belonging to the final part of this eruptive cycle. This result supports the idea that no new juvenile fluids from the source region have been injected into the magmatic reservoir during the 1631-1944 eruptive cycle and, more importantly, until 1993. Both sets of data help to understand the genesis of these fluids and to constrain the current activity of the volcano.

  19. Lava tubes - Potential shelters for habitats. [on moon

    NASA Technical Reports Server (NTRS)

    Horz, F.

    1985-01-01

    Natural caverns occur on the moon in the form of 'lava tubes', which are the drained conduits of underground lava rivers. The inside dimensions of these tubes measure tens to hundreds of meters, and their roofs are expected to be thicker than 10 meters. Consequently, lava tube interiors offer an environment that is naturally protected from the hazards of radiation and meteorite impact. Further, constant, relatively benign temperatures of -20 C prevail. These are extremely favorable environmental conditions for human activities and industrial operations. Significant operational, technological, and economical benefits might result if a lunar base were constructed inside a lava tube.

  20. The Payun-Matru lava field: a source of analogues for Martian long lava flows

    NASA Astrophysics Data System (ADS)

    Giacomini, L.; Pasquarè, G.; Massironi, M.; Frigeri, A.; Bistacchi, A.; Frederico, C.

    2007-08-01

    'Accademia dei Lincei, 9, 16 (3), 127-135.[2]Pasquaré G., Bistacchi A., Francalanci L.. Gigantic self-confined pahoehoe inflated lava flows in Argentina. Submitted to Terra Nova. [3]Self, S., Keszthelyi, L., Thordarson, Th., 1998. The Importance of Pahoehoe. Annual Review of Earth and Planetary Science, 26, 81-110. [4]Anderson T., 1910. The volcano of Matavanu in Savaii. Geological Society of London Quarterly Journal, 66, 621-639. [5] Walker, G.P.L., 1991. Structure and origin by injection of lava under surface crust, of tumuli, "lava rises", "lava rise pits", and "lava inflation clefts" in Hawaii. Bulletin of Volcanology, 53, 546-558. [6] Hon, K, Kauahikaua, J., Denlinger, R., Mackay, K., 1994. Emplacement and inflation of pahoehoe sheet flows: Observations and measurements of active lava flows on Kilauea Volcano, Hawaii. Geological Society of America Bulletin, 106, 351-370. [7] Llambias, E., 1966. Geología y petrográfica del Volcán Payún-Matru. Acta Geológica Lill., VIII: 265-310. Instituto Lillo, Universidad Nacional Tucumán. Tucumán. [8] Zimbelman, J. R., 1998. Emplacement of long lava flows on planetary surface. J. Geophys. Res., 103, 27503- 27516. [9] Smith, D. E. et al., 1999. The global topography of Mars and implications for surface evolution. Science, 284, 1495-1503. [10] Glaze L.S., Anderson S.W., Stofan E.R., Baloga S., Smrekar S. E, 2005. Statistical distribution of tumuli on pahoehoe flow surfaces: analysis of examples in Hawaii and Iceland and potential application to lava flows on Mars. Journal of Geophysical Research, v. 110, B08202, doc: 10.1029/2004JB003564. [11] MacDonald, 1972. Volcanoes. Prentice-Hall Inc., Englewood Cliffs. 510 pp.

  1. Catalog of Mount St. Helens 2004-2007 Dome Samples with Major- and Trace-Element Chemistry

    USGS Publications Warehouse

    Thornber, Carl R.; Pallister, John S.; Rowe, Michael C.; McConnell, Siobhan; Herriott, Trystan M.; Eckberg, Alison; Stokes, Winston C.; Cornelius, Diane Johnson; Conrey, Richard M.; Hannah, Tammy; Taggart, Joseph E.; Adams, Monique; Lamothe, Paul J.; Budahn, James R.; Knaack, Charles M.

    2008-01-01

    Sampling and analysis of eruptive products at Mount St. Helens is an integral part of volcano monitoring efforts conducted by the U.S. Geological Survey?s Cascades Volcano Observatory (CVO). The objective of our eruption sampling program is to enable petrological assessments of pre-eruptive magmatic conditions, critical for ascertaining mechanisms for eruption triggering and forecasting potential changes in eruption behavior. This report provides a catalog of near-vent lithic debris and new dome-lava collected during 34 intra-crater sampling forays throughout the October 2004 to October 2007 (2004?7) eruptive interval at Mount St. Helens. In addition, we present comprehensive bulk-rock geochemistry for a time-series of representative (2004?7) eruption products. This data, along with that in a companion report on Mount St. Helens 2004 to 2006 tephra by Rowe and others (2008), are presented in support of the contents of the U.S. Geological Survey Professional Paper 1750 (Sherrod and others, eds., 2008). Readers are referred to appropriate chapters in USGS Professional Paper 1750 for detailed narratives of eruptive activity during this time period and for interpretations of sample characteristics and geochemical data. The suite of rock samples related to the 2004?7 eruption of Mount St. Helens and presented in this catalog are archived at the David A. Johnson Cascades Volcano Observatory, Vancouver, Wash. The Mount St. Helens 2004?7 Dome Sample Catalogue with major- and trace-element geochemistry is tabulated in 3 worksheets of the accompanying Microsoft Excel file, of2008-1130.xls. Table 1 provides location and sampling information. Table 2 presents sample descriptions. In table 3, bulk-rock major and trace-element geochemistry is listed for 44 eruption-related samples with intra-laboratory replicate analyses of 19 dacite lava samples. A brief overview of the collection methods and lithology of dome samples is given below as an aid to deciphering the dome sample

  2. Observations on lava, snowpack and their interactions during the 2012-13 Tolbachik eruption, Klyuchevskoy Group, Kamchatka, Russia

    NASA Astrophysics Data System (ADS)

    Edwards, Benjamin R.; Belousov, Alexander; Belousova, Marina; Melnikov, Dmitry

    2015-12-01

    Observations made during January and April 2013 show that interactions between lava flows and snowpack during the 2012-13 Tolbachik fissure eruption in Kamchatka, Russia, were controlled by different styles of emplacement and flow velocities. `A`a lava flows and sheet lava flows generally moved on top of the snowpack with few immediate signs of interaction besides localized steaming. However, lavas melted through underlying snowpack 1-4 m thick within 12 to 24 h, and melt water flowed episodically from the beneath flows. Pahoehoe lava lobes had lower velocities and locally moved beneath/within the snowpack; even there the snow melting was limited. Snowpack responses were physical, including compressional buckling and doming, and thermal, including partial and complete melting. Maximum lava temperatures were up to 1355 K (1082 °C; type K thermal probes), and maximum measured meltwater temperatures were 335 K (62.7 °C). Theoretical estimates for rates of rapid (e.g., radiative) and slower (conductive) snowmelt are consistent with field observations showing that lava advance was fast enough for `a`a and sheet flows to move on top of the snowpack. At least two styles of physical interactions between lava flows and snowpack observed at Tolbachik have not been previously reported: migration of lava flows beneath the snowpack, and localized phreatomagmatic explosions caused by snowpack failure beneath lava. The distinctive morphologies of sub-snowpack lava flows have a high preservation potential and can be used to document snowpack emplacement during eruptions.

  3. Venus steep-sided domes: Relationships between geological associations and possible petrogenetic models

    NASA Technical Reports Server (NTRS)

    Pavri, B.; Head, James W., III

    1992-01-01

    Venus domes are characterized by steep sides, a circular shape, and a relatively flat summit area. In addition, they are orders of magnitude larger in volume and have a lower height/diameter ratio than terrestrial silicic lava domes. The morphology of the domes is consistent with formation by lava with a high apparent viscosity. Twenty percent of the domes are located in or near tessera (highly deformed highlands), while most other (62 percent) are located in and near coronae (circular deformational features thought to represent local mantle upwelling). These geological associations provide evidence for mechanisms of petrogenesis and several of these models are found to be plausible: remelting of basaltic or evolved crust, differentiation of basaltic melts, and volatile enhancement and eruption of basaltic foams. Hess and Head have shown that the full range of magma compositions existing on the Earth is plausible under various environmental conditions on Venus. Most of the Venera and Vego lander compostional data are consistent with tholeiitic basalt; however, evidence for evolved magmas was provided by Venera 8 data consistent with a quartz monzonite composition. Pieters et al. have examined the color of the Venus surface from Venera lander images and interpret the surface there to be oxidized. Preliminary modeling of dome growth has provided some interpretations of lava rheology. Viscosity values obtained from these models range from 10(exp 14) - 10(exp 17) pa*s, and the yield strength has been calculated to be between 10(exp 4) and 10(exp 6) Pa, consistent with terrestrial silicic rocks. The apparent high viscosity of the dome lavas suggests that the domes have a silicic composition or must augment their viscosity with increased visicularity or crystal content. Sixty-two percent of the Venus domes are associated with coronae, circular features that have been proposed as sites of mantle upwelling, and 20 percent of the domes are located near tessera, relatively

  4. Lava Tube Collapse Pits

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    We will be looking at collapse pits for the next two weeks. Collapse pits on Mars are formed in several ways. In volcanic areas, channelized lava flows can form roofs which insulate the flowing lava. These features are termed lava tubes on Earth and are common features in basaltic flows. After the lava has drained, parts of the roof of the tube will collapse under its own weight. These collapse pits will only be as deep as the bottom of the original lava tube. Another type of collapse feature associated with volcanic areas arises when very large eruptions completely evacuate the magma chamber beneath the volcano. The weight of the volcano will cause the entire edifice to subside into the void space below it. Structural features including fractures and graben will form during the subsidence. Many times collapse pits will form within the graben. In addition to volcanic collapse pits, Mars has many collapse pits formed when volatiles (such as subsurface ice) are released from the surface layers. As the volatiles leave, the weight of the surrounding rock causes collapse pits to form.

    These collapse pits are found in the southern hemisphere of Mars. They are likely lava tube collapse pits related to flows from Hadriaca Patera.

    Image information: VIS instrument. Latitude -36.8, Longitude 89.6 East (270.4 West). 19 meter/pixel resolution. Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space

  5. Lava emplacements at Shiveluch volcano (Kamchatka) from June 2011 to September 2014 observed by TanDEM-X SAR-Interferometry

    NASA Astrophysics Data System (ADS)

    Heck, Alexandra; Kubanek, Julia; Westerhaus, Malte; Gottschämmer, Ellen; Heck, Bernhard; Wenzel, Friedemann

    2016-04-01

    As part of the Ring of Fire, Shiveluch volcano is one of the largest and most active volcanoes on Kamchatka Peninsula. During the Holocene, only the southern part of the Shiveluch massive was active. Since the last Plinian eruption in 1964, the activity of Shiveluch is characterized by periods of dome growth and explosive eruptions. The recent active phase began in 1999 and continues until today. Due to the special conditions at active volcanoes, such as smoke development, danger of explosions or lava flows, as well as poor weather conditions and inaccessible area, it is difficult to observe the interaction between dome growth, dome destruction, and explosive eruptions in regular intervals. Consequently, a reconstruction of the eruption processes is hardly possible, though important for a better understanding of the eruption mechanism as well as for hazard forecast and risk assessment. A new approach is provided by the bistatic radar data acquired by the TanDEM-X satellite mission. This mission is composed of two nearly identical satellites, TerraSAR-X and TanDEM-X, flying in a close helix formation. On one hand, the radar signals penetrate clouds and partially vegetation and snow considering the average wavelength of about 3.1 cm. On the other hand, in comparison with conventional InSAR methods, the bistatic radar mode has the advantage that there are no difficulties due to temporal decorrelation. By interferometric evaluation of the simultaneously recorded SAR images, it is possible to calculate high-resolution digital elevation models (DEMs) of Shiveluch volcano and its surroundings. Furthermore, the short recurrence interval of 11 days allows to generate time series of DEMs, with which finally volumetric changes of the dome and of lava flows can be determined, as well as lava effusion rates. Here, this method is used at Shiveluch volcano based on data acquired between June 2011 and September 2014. Although Shiveluch has a fissured topography with steep slopes

  6. Lava tube shatter rings and their correlation with lava flux increases at Kīlauea Volcano, Hawai‘i

    USGS Publications Warehouse

    Orr, T.R.

    2011-01-01

    Shatter rings are circular to elliptical volcanic features, typically tens of meters in diameter, which form over active lava tubes. They are typified by an upraised rim of blocky rubble and a central depression. Prior to this study, shatter rings had not been observed forming, and, thus, were interpreted in many ways. This paper describes the process of formation for shatter rings observed at Kīlauea Volcano during November 2005–July 2006. During this period, tilt data, time-lapse images, and field observations showed that episodic tilt changes at the nearby Pu‘u ‘Ō‘ō cone, the shallow magmatic source reservoir, were directly related to fluctuations in the level of lava in the active lava tube, with periods of deflation at Pu‘u ‘Ō‘ō correlating with increases in the level of the lava stream surface. Increases in lava level are interpreted as increases in lava flux, and were coincident with lava breakouts from shatter rings constructed over the lava tube. The repetitive behavior of the lava flux changes, inferred from the nearly continuous tilt oscillations, suggests that shatter rings form from the repeated rise and fall of a portion of a lava tube roof. The locations of shatter rings along the active lava tube suggest that they form where there is an abrupt decrease in flow velocity through the tube, e.g., large increase in tube width, abrupt decrease in tube slope, and (or) sudden change in tube direction. To conserve volume, this necessitates an abrupt increase in lava stream depth and causes over-pressurization of the tube. More than a hundred shatter rings have been identified on volcanoes on Hawai‘i and Maui, and dozens have been reported from basaltic lava fields in Iceland, Australia, Italy, Samoa, and the mainland United States. A quick study of other basaltic lava fields worldwide, using freely available satellite imagery, suggests that they might be even more common than previously thought. If so, this confirms that episodic

  7. Nornahraun lava morphology and mode of emplacement

    NASA Astrophysics Data System (ADS)

    Pedersen, Gro B. M.; Höskuldsson, Armann; Riishuus, Morten S.; Jónsdóttir, Ingibjörg; Gudmundsson, Magnús T.; Sigmundsson, Freysteinn; Óskarsson, Birgir V.; Drouin, Vincent; Gallagher, Catherine; Askew, Rob; Moreland, William M.; Dürig, Tobias; Dumont, Stephanie; Þórdarson, Þór

    2015-04-01

    The ongoing Nornahraun eruption is the largest effusive eruption in Iceland since the Laki eruption in 1783-84, with an estimated lava volume of ~1.15 km3 covering an area of ~83.4 km2 (as of 5 JAN 2015). The eruption provides an unprecedented opportunity to study i) lava morphologies and their emplacement styles, ii) the transition from from open to closed lava pathways and iii) lava pond formation. Tracking of the lava advancement and morphology has been performed by GPS and GoPro cameras installed in 4×4 vehicles as well as video footage. Complimentary observations have been provided from aircraft platforms and by satellite data. Of particular importance for lava morphology observations are 1-12 m/pixel airborne SAR images (x-band). The Nornahraun flow field comprises a continuum of morphologies from pāhoehoe to 'a'ā, which have varied tem-porally and spatially. At the onset of the eruption 31 AUG, lava flows advanced rapidly (400-800 m/hr) from the 1.5 km long fissure as large slabby pāhoehoe [1-3] sheet lobes, 100-500 m wide and 0.3-1 m thick at the flow fronts. By 1 SEPT, the flows began channeling towards the NE constrained by the older Holuhraun I lava field and the to-pography of flood plain itself. A central open channel developed, feeding a 1-2 km wide active 'a'ā frontal lobe that advanced 1-2 km/day. In addition to its own caterpillar motion, the frontal lobe advanced in a series of 30-50 m long breakouts, predominantly slabby and rubbly pāhoehoe [4,5]. These breakouts had initial velocities of 10-30 m/hr and reached their full length within tens of minutes and subsequently inflated over hours. With the continuous advancement of the 'a'ā flow front, the breakouts were incorporated into the 'a'ā flow fronts and seldom preserved. At the margins of the frontal lava lobe, the breakouts were more sporadic, but predominantly rubbly pāhoehoe and slabby pāhoehoe, as at the flow front. The lava flow advanced ENE into Jökulsá á Fjöllum on 7 SEPT

  8. Formation of lunar mare domes along crustal fractures: Rheologic conditions, dimensions of feeder dikes, and the role of magma evolution

    NASA Astrophysics Data System (ADS)

    Wöhler, Christian; Lena, Raffaello; Phillips, Jim

    2007-08-01

    In this study we examine a set of lunar mare domes located in the Hortensius/Milichius/T. Mayer region and in northern Mare Tranquillitatis with respect to their formation along crustal fractures, their rheologic properties, the dimensions of their feeder dikes, and the importance of magma evolution processes during dome formation. Many of these domes display elongated summit vents oriented radially with respect to major impact basins, and several dome locations are also aligned in these preferential directions. Analysis of Clementine UV/VIS and Lunar Prospector gamma ray spectrometer data reveals that the examined mare domes formed from low-Si basaltic lavas of high FeO and low to moderate TiO 2 content. Based on their morphometric properties (diameter, height, volume) obtained by photoclinometric and shape from shading analysis of telescopic CCD images, we derive rheologic quantities (lava viscosity during eruption, effusion rate, duration of the effusion process, magma rise speed) and the dimensions of the feeder dikes. We establish three rheologic groups characterised by specific combinations of rheologic properties and dike dimensions, where the most relevant discriminative parameter is the lava viscosity η. The first group is characterised by 10 Pas<η<10 Pas and contains the domes with elongated vents in the Milichius/T. Mayer region and two similar domes in northern Mare Tranquillitatis. The second group with 10 Pas<η<10 Pas comprises the very low aligned domes in northern Mare Tranquillitatis, and the third group with 10 Pas<η<10 Pas the relatively steep domes near Hortensius and in the T. Mayer region. The inferred dike dimensions in comparison to lunar crustal thickness data indicate that the source regions of the feeder dikes are situated within the upper crust for six of the domes in northern Mare Tranquillitatis, while they are likely to be located in the lower crust and in the upper mantle for the other examined domes. By comparing the time scale

  9. Inverse differentiation pathway by multiple mafic magma refilling in the last magmatic activity of Nisyros Volcano, Greece

    NASA Astrophysics Data System (ADS)

    Braschi, Eleonora; Francalanci, Lorella; Vougioukalakis, Georges E.

    2012-07-01

    Based on detailed field, petrographic, chemical, and isotopic data, this paper shows that the youngest magmas of the active Nisyros volcano (South Aegean Arc, Greece) are an example of transition from rhyolitic to less evolved magmas by multiple refilling with mafic melts, triggering complex magma interaction processes. The final magmatic activity of Nisyros was characterized by sub-Plinian caldera-forming eruption (40 ka), emplacing the Upper Pumice (UP) rhyolitic deposits, followed by the extrusion of rhyodacitic post-caldera domes (about 31-10 ka). The latter are rich in magmatic enclaves with textural and compositional (basaltic-andesite to andesite) characteristics that reveal they are quenched portions of mafic magmas included in a cooler more evolved melt. Dome-lavas have different chemical, isotopic, and mineralogical characteristics from the enclaves. The latter have lower 87Sr/86Sr and higher 143Nd/144Nd values than dome-lavas. Silica contents and 87Sr/86Sr values decrease with time among dome-lavas and enclaves. Micro-scale mingling processes caused by enclave crumbling and by widespread mineral exchanges increase from the oldest to the youngest domes, together with enclave content. We demonstrate that the dome-lavas are multi-component magmas formed by progressive mingling/mixing processes between a rhyolitic component ( post-UP) and the enclave-forming mafic magmas refilling the felsic reservoir (from 15 wt.% to 40 wt.% of mafic component with time). We recognize that only the more evolved enclave magmas contribute to this process, in which recycling of cumulate plagioclase crystals is also involved. The post-UP end-member derives by fractional crystallization from the magmas leftover after the previous UP eruptions. The enclave magma differentiation develops mainly by fractional crystallization associated with multiple mixing with mafic melts changing their composition with time. A time-related picture of the relationships between dome-lavas and

  10. Lava-Filled Craters

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 12 June 2003

    Craters and hills form high standing streamlined plateaus or islands in a channeled area. The plateaus are rounded in the upstream direction and taper to a point in the downstream direction, indicating that the direction of flow in this area was roughly south to north, or bottom to top. The channels appear to be filled with lava flow deposits that are raised above the channel in some areas. A lava flow diverges around a small streamlined hill near the bottom of the image and then merges again around the northern end of it. Near the top of the image is a crater with a breach on the east (right) side that allowed the lava to flow in, leaving a lobate, high standing deposit. The channels may have been formed by the lava flows that currently fill them or there may have been flow of liquid water that created them before the lava was emplaced.

    Image information: VIS instrument. Latitude 16, Longitude 183 East (177 West). 19 meter/pixel resolution.

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

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

  11. A New Perspective on Mount St. Helens - Dramatic Landform Change and Associated Hazards at the Most Active Volcano in the Cascade Range

    USGS Publications Warehouse

    Ramsey, David W.; Driedger, Carolyn L.; Schilling, Steve P.

    2008-01-01

    Mount St. Helens has erupted more frequently than any other volcano in the Cascade Range during the past 4,000 years. The volcano has exhibited a variety of eruption styles?explosive eruptions of pumice and ash, slow but continuous extrusions of viscous lava, and eruptions of fluid lava. Evidence of the volcano?s older eruptions is recorded in the rocks that build and the deposits that flank the mountain. Eruptions at Mount St. Helens over the past three decades serve as reminders of the powerful geologic forces that are reshaping the landscape of the Pacific Northwest. On May 18, 1980, a massive landslide and catastrophic explosive eruption tore away 2.7 cubic kilometers of the mountain and opened a gaping, north-facing crater. Lahars flowed more than 120 kilometers downstream, destroying bridges, roads, and buildings. Ash from the eruption fell as far away as western South Dakota. Reconstruction of the volcano began almost immediately. Between 1980 and 1986, 80 million cubic meters of viscous lava extruded episodically onto the crater floor, sometimes accompanied by minor explosions and small lahars. A lava dome grew to a height of 267 meters, taller than the highest buildings in the nearby city of Portland, Oregon. Crater Glacier formed in the deeply shaded niche between the 1980-86 lava dome and the south crater wall. Its tongues of ice flowed around the east and west sides of the dome. Between 1989 and 1991, multiple explosions of steam and ash rocked the volcano, possibly a result of infiltrating rainfall being heated in the still-hot interior of the dome and underlying crater floor. In September 2004, rising magma caused earthquake swarms and deformation of the crater floor and glacier, which indicated that Mount St. Helens might erupt again soon. On October 1, 2004, a steam and ash explosion signaled the beginning of a new phase of eruptive activity at the volcano. On October 11, hot rock reached the surface and began building a new lava dome immediately

  12. Documenting Chemical Assimilation in a Basaltic Lava Flow

    NASA Technical Reports Server (NTRS)

    Young, K. E.; Bleacher, J. E.; Needham, D. H.; Evans, C.; Whelley, P. L.; Scheidt, S.; Williams, D.; Rogers, A. D.; Glotch, T.

    2017-01-01

    Lava channels are features seen throughout the inner Solar System, including on Earth, the Moon, and Mars. Flow emplacement is therefore a crucial process in the shaping of planetary surfaces. Many studies have investigated the dynamics of lava flow emplacement, both on Earth and on the Moon [1,2,3] but none have focused on how the compositional and structural characteristics of the substrate over which a flow was emplaced influenced its final flow morphology. Within the length of one flow, it is common for flows to change in morphology, a quality linked to lava rheology (a function of multiple factors including viscosity, temperature, composition, etc.). The relationship between rheology and temperature has been well-studied [4,5,6] but less is understood about the relationship between a pre-flow terrain's chemistry and how the interaction between this flow and the new flow might affect lava rheology and therefore emplacement dynamics. Lava erosion. Through visual observations of active terrestrial flows, lava erosion has been well-documented [i.e. 7,8,9,10]. Lava erosion is the process by which flow composition is altered as the active lava melts and assimilates the pre-flow terrain over which it moves. Though this process has been observed, there is only one instance of where it was been geochemically documented.

  13. Field Detection of Chemical Assimilation in A Basaltic Lava Flow

    NASA Technical Reports Server (NTRS)

    Young, K. E.; Bleacher, J. E.; Needham, D. H.; Evans, C. A.; Whelley, P. L.; Scheidt, S. P.; Williams, D. A.; Rogers, A. D.; Glotch, T.

    2017-01-01

    Lava channels are features seen throughout the inner Solar System, including on Earth, the Moon, and Mars. Flow emplacement is therefore a crucial process in the shaping of planetary surfaces. Many studies, including some completed by members of this team at the December 1974 lava flow, have investigated the dynamics of lava flow emplacement, both on Earth and on the Moon and how pre-flow terrain can impact final channel morphology, but far fewer have focused on how the compositional characteristics of the substrate over which a flow was em-placed influenced its final flow morphology. Within the length of one flow, it is common for flows to change in morphology, a quality linked to rheology (a function of multiple factors including viscosi-ty, temperature, composition, etc.). The relationship between rheology and temperature has been well-studied but less is known about the relationship between an older flow's chemistry and how the interaction between this flow and the new flow might affect lava rheology and therefore emplacement dynamics. Lava erosion. Through visual observations of active terrestrial flows, mechanical erosion by flowing lava has been well-documented. Lava erosion by which flow composition is altered as the active lava melts and assimilates the pre-flow terrain over which it moves is also hypothesized to affect channel formation. However, there is only one previous field study that geochemically documents the process in recent basaltic flow systems.

  14. Petrology and geochemistry of lava and ash erupted from Volcán Colima, Mexico, during 1998 2005

    NASA Astrophysics Data System (ADS)

    Savov, Ivan P.; Luhr, James F.; Navarro-Ochoa, Carlos

    2008-07-01

    Lava ( n = 8) and bulk ash samples ( n = 6) erupted between July 1999 and June 2005 were investigated to extend time-series compositional and textural studies of the products erupted from Volcán Colima since 1869. In particular, we seek to evaluate the possibility that the current activity will culminate in major explosive Plinian-style event similar to that in 1913. Lava samples continue to show relatively heterogeneous whole-rock compositions with some significant mafic spikes (1999, 2001) as have prevailed since 1976. Groundmass SiO 2 contents continue trends to lower levels that have prevailed since 1961, in the direction of the still lower groundmass SiO 2 contents found in 1913 scoriae. Importantly, ash samples from investigated Vulcanian-style explosive eruptions in 2005 are devoid of particles with micro-vesiculated groundmass textures; such textures characterized the 1913 scoriae, signifying expansion of in-situ magmatic gas as the propellant of the 1913 eruption. All magmas erupted since 1913 appear to have arrived in the upper volcanic conduit system in a degassed state. The small to moderate Vulcanian-style explosive eruptions, which have been common since 1999 (> 16,000 events), have blasted ash clouds as high as 11 km a.s.l. and sent pyroclastic flows out to distances of 5 km. These eruptions do not appear to be powered by expansion of in-situ magmatic gas. New small lava domes have been observed in the crater prior to many explosive eruptions. These plugs of degassed lava may temporarily seal the conduit and allow the build-up of magmatic gases streaming upward from below ahead of rising and degassing magma. In this interpretation, when gas pressure exceeds the strength of the plug seal in the upper conduit, an explosive Vulcanian-style eruption occurs. Alternatively these explosive eruptions may represent interactions of hot rock and groundwater (phreato-magmatic).

  15. Fire, Lava Flows, and Human Evolution

    NASA Astrophysics Data System (ADS)

    Medler, M. J.

    2015-12-01

    Richard Wrangham and others argue that cooked food has been obligate for our ancestors since the time of Homo erectus. This hypothesis provides a particularly compelling explanation for the smaller mouths and teeth, shorter intestines, and larger brains that separate us from other hominins. However, natural ignitions are infrequent and it is unclear how earlier hominins may have adapted to cooked food and fire before they developed the necessary intelligence to make or control fire. To address this conundrum, we present cartographical evidence that the massive and long lasting lava flows in the African Rift could have provided our ancestors with episodic access to heat and fire as the front edges of these flows formed ephemeral pockets of heat and ignition and other geothermal features. For the last several million years major lava flows have been infilling the African Rift. After major eruptions there were likely more slowly advancing lava fronts creating small areas with very specific adaptive pressures and opportunities for small isolated groups of hominins. Some of these episodes of isolation may have extended for millennia allowing these groups of early hominins to develop the adaptations Wrangham links to fire and cooked food. To examine the potential veracity of this proposal, we developed a series of maps that overlay the locations of prominent hominin dig sites with contemporaneous lava flows. These maps indicate that many important developments in hominin evolution were occurring in rough spatial and temporal proximity to active lava flows. These maps indicate it is worth considering that over the last several million years small isolated populations of hominins may have experienced unique adaptive conditions while living near the front edges of these slowly advancing lava flows.

  16. Geology and development history of Jennings salt dome 1901-1985: clue to future of Gulf Coast salt domes

    SciTech Connect

    Cook, J.C.; Harrison, F.W. Jr.

    1986-05-01

    Historically, salt domes have been the primary target of oil and gas exploration in the Texas and Louisiana Gulf Coast. In south Louisiana, the 89 piercement salt dome fields discovered since 1901 have produced 6,492,462,685 bbl of oil and condensate, representing approximately 60% of all oil and condensate produced in south Louisiana. Because of the tremendous volume of oil already extracted, there may be doubt about finding significant reserves on these features in the future. A current review of Jennings salt dome, the first Louisiana oil field, however, suggests that south Louisiana piercement domes still have large undiscovered reserves. Jennings dome, which has produced continuously since its discovery in 1901, has produced, as of 1985, 115 million bbl of oil and condensate. Its long and active exploration history is representative of many piercement domes in south Louisiana. A combination of characteristics explain why Jennings, as well as other domes, continues to be the focus of major exploration efforts. Piercement salt domes are generally complex both stratigraphically and structurally because of their geologic origin. Prolific high-angle faulting coupled with depositional unconformities and rapid stratigraphic changes make it difficult to determine accurately the precise nature and extent of existing hydrocarbon traps. Additional, the occurrence of multiple sand reservoirs and outstanding recovery rates of oil in place result in areally small reservoirs that contain substantial reserves.

  17. Geologic study of Kettle dome, northeast Washington. Final report

    SciTech Connect

    Not Available

    1980-10-01

    This geologic study of Kettle dome, northeast Washington, encompasses an area of approximately 800 square miles (2048 sq km). The evaluation of uranium occurrences associated with the igneous and metamorphic rocks of the dome and the determination of the relationship between uranium mineralization and stratigraphic, structural, and metamorphic features of the dome are the principal objectives. Evaluation of the validity of a gneiss dome model is a specific objective. The principal sources of data are detailed geologic mapping, surface radiometric surveys, and chemical analyses of rock samples. Uranium mineralization is directly related to the presence of pegmatite dikes and sills in biotite gneiss and amphibolite. Other characteristics of the uranium occurrences include the associated migmatization and high-grade metamorphism of wallrock adjacent to the pegmatite and the abrupt decrease in uranium mineralization at the pegmatite-gneiss contact. Subtle chemical characteristics found in mineralized pegmatites include: (1) U increase as K/sub 2/O increases, (2) U decreases as Na/sub 2/O increases, and (3) U increases as CaO increases at CaO values above 3.8%. The concentration of uranium occurrences in biotite gneiss and amphibolite units results from the preferential intrusion of pegmitites into these well-foliated rocks. Structural zones of weakness along dome margins permit intrusive and migmatitic activity to affect higher structural levels of the dome complex. As a result, uranium mineralization is localized along dome margins. The uranium occurrences in the Kettle dome area are classified as pegmatitic. Sufficient geologic similarities exist between Kettle dome and the Rossing uranium deposit to propose the existence of economic uranium targets within Kettle dome.

  18. Lava Flows on Io: Modelling Cooling After Solidification

    NASA Technical Reports Server (NTRS)

    Davies, A. G.; Matson, D. L.; Veeder, G. J.; Johnson, T. V.; Blaney, D. L.

    2003-01-01

    We have modeled the cooling of lava bodies on Io after solidification of the lava, a process that has been little explored since Carr (1986). With recent estimates of lava flow thicknesses on Io ranging from 1 m to 10 m, the modeling of thermal emission from active volcanism must take into account the cooling behaviour after the solidification of the lava, which we model using a finite-element model. Once a lava body is fully solidified, the surface temperature decreases faster, as heat loss is no longer buffered by release of latent heat. This is significant as observed surface temperature is often the only clue available to determine lava surface age. We also find that cooling from the base of the lava is an important process that accelerates the solidification of a flow and therefore subsequent cooling. It is necessary to constrain the cooling process in order to better understand temperature-area relationships on Io's surface and to carry out stochastic modelling of lava flow emplacement.

  19. The LSST Dome final design

    NASA Astrophysics Data System (ADS)

    DeVries, J.; Neill, D. R.; Barr, J.; De Lorenzi, Simone; Marchiori, Gianpietro

    2016-07-01

    The Large Synoptic Survey Telescope (LSST) is a large (8.4 meter) wide-field (3.5 degree) survey telescope, which will be located on the Cerro Pachón summit in Chile 1. As a result of the Telescope wide field of view, the optical system is unusually susceptible to stray light 2. In addition, balancing the effect of wind induced telescope vibrations with Dome seeing is crucial. The rotating enclosure system (Dome) includes a moving wind screen and light baffle system. All of the Dome vents include hinged light baffles, which provide exceptional Dome flushing, stray light attenuation, and allows for vent maintenance access from inside the Dome. The wind screen also functions as a light screen, and helps define a clear optical aperture for the Telescope. The Dome must operate continuously without rotational travel limits to accommodate the Telescope cadence and travel. Consequently, the Azimuth drives are located on the fixed lower enclosure to accommodate glycol water cooling without the need for a utility cable wrap. An air duct system aligns when the Dome is in its parked position, and this provides air cooling for temperature conditioning of the Dome during the daytime. A bridge crane and a series of ladders, stairs and platforms provide for the inspection, maintenance and repair of all of the Dome mechanical systems. The contract to build the Dome was awarded to European Industrial Engineering in Mestre, Italy in May 2015. In this paper, we present the final design of this telescope and site sub-system.

  20. The giant Shakhdara migmatitic gneiss dome, Pamir, India-Asia collision zone: 2. Timing of dome formation

    NASA Astrophysics Data System (ADS)

    Stübner, Konstanze; Ratschbacher, Lothar; Weise, Carsten; Chow, Judy; Hofmann, Jakob; Khan, Jahanzeb; Rutte, Daniel; Sperner, Blanka; Pfänder, Jörg A.; Hacker, Bradley R.; Dunkl, István.; Tichomirowa, Marion; Stearns, M. A.

    2013-09-01

    Cenozoic gneiss domes—exposing middle-lower crustal rocks—cover ~30% of the surface exposure of the Pamir, western India-Asia collision zone; they allow an unparalleled view into the deep crust of the Asian plate. We use titanite, monazite, and zircon U/Th-Pb, mica Rb-Sr and 40Ar/39Ar, zircon and apatite fission track, and zircon (U-Th)/He ages to constrain the exhumation history of the ~350 × 90 km Shakhdara-Alichur dome, southwestern Pamir. Doming started at 21-20 Ma along the Gunt top-to-N normal-shear zone of the northern Shakhdara dome. The bulk of the exhumation occurred by ~NNW-ward extrusion of the footwall of the crustal-scale South Pamir normal-shear zone along the southern Shakhdara dome boundary. Footwall extrusion was active from ~18-15 Ma to ~2 Ma at ~10 mm/yr slip and with vertical exhumation rates of 1-3 mm/yr; it resulted in up to 90 km ~N-S extension, coeval with ~N-S convergence between India and Asia. Erosion rates were 0.3-0.5 mm/yr within the domes and 0.1-0.3 mm/yr in the horst separating the Shakhdara and Alichur domes and in the southeastern Pamir plateau; rates were highest along the dome axis in the southern part of the Shakhdara dome. Incision along the major drainages was up to 1.0 mm/yr. Thermal modeling suggests geothermal gradients as high as 60°C/km along the trace of the South Pamir shear zone and their strong N-S variation across the dome; the gradients relaxed to ≤40-45°C/km since the end of doming.

  1. Pyroclastic density currents from the May 2008 eruption of Chaitén volcano (Chile) and subsequent dome collapse

    NASA Astrophysics Data System (ADS)

    Major, J. J.; Pierson, T. C.; Pallister, J. S.; Hoblitt, R. P.; Moreno, H.; Swanson, F. J.

    2010-12-01

    Explosive activity at Chaitén volcano in May 2008 and subsequent dome collapse nine months later triggered pyroclastic density currents (PDCs) that choked proximal reaches of channels draining the volcano with as much as 10 m of sediment. A north-directed, 1-km-wide, blast-like PDC, probably occurring between 6-12 May, cut a swath about 2 km long through forest, leaving a disturbance gradient from total tree removal near the volcano’s rim through tree toppling to minor abrasion and leaf kill at its distal limit. The PDC left a decimeters-thick friable deposit grading upward from poorly sorted pumiceous coarse ash and fine lapilli to a mixture of pumiceous and lithic coarse ash. Fragments of both charred and uncharred twigs are concentrated in the basal half of the deposit, but vegetation protruding above the deposit is uncharred. The PDC removed or abraded epiphytes on upslope sides of large standing trees up to ~5 m above the ground. To the south in the Río Chaitén valley, deposits of two PDCs are preserved. At least 6 m of massive, poorly sorted, slightly compacted, matrix-supported, brown-gray diamict, having a coarse ash matrix and containing clasts predominantly of gray and banded red rhyolite with minor black rhyolite, obsidian, and greenschist, lies in erosional contact over fall deposits from waning plinian columns of 7 May 2008. The diamict envelopes lightly charred tree trunks at its margin and contains detrital charred wood fragments. It was emplaced by a lithic pyroclastic flow that traveled an undetermined distance downvalley, apparently triggered by explosions of hot juvenile material combined with fragmentation or partial collapse of the pre-2008 lava dome between 7-12 May 2008 (a new dome started growing on 9 May). Over the next months, runoff from heavy rainfall eroded much of this deposit. On 19 February 2009 part of the large (500 million m3) new lava dome collapsed and produced a lithic pyroclastic flow that traveled 7 km, filling R

  2. Drilling investigation of a young magmatic intrusion beneath Inyo Dome, Long Valley Caldera, California. Progress report

    SciTech Connect

    Vogel, T.A.

    1985-01-01

    Progress to date indicates: (1) the conduit and lava flow at Obsidian Dome consist of two magma types; (2) the more mafic magma occurs at the base of Obsidian Dome and at the margins of the conduit and was emplaced first; (3) the more silicic magma occurs in the center of the conduit and in the dike; (4) the ilmenite-magnetite and orthopyroxene-augite geothermometers have not reequilibrated in the conduit or dike; (5) the more mafic magma's emplacement temperature was 974/sup 0/C compared to the silicic magma's 951/sup 0/C; and (6) trace elements are characteristic of each magma type. (ACR)

  3. The Effect of Lava Texture on LiDAR Attributes and Full Waveform

    NASA Astrophysics Data System (ADS)

    Anderson, S. W.; Finnegan, D. C.; LeWinter, A.

    2013-12-01

    The distribution of glassy, vesicular, and crystalline textures on lava flow and dome surfaces provides insights regarding the physical and chemical processes occurring during emplacement. For silicic flows, these textures may reflect variations in the volatile content of lava upon eruption. To assess the efficacy of texture detection with our terrestrial full waveform LiDAR system capable of measuring ~125,000 topographic points/second, we analyzed attribute and full waveform data from a variety of lava textures displayed on recent rhyolitic obsidian flows of the Inyo Dome chain (California) and pahoehoe and aa flows at Kilauea volcano (Hawaii). We find that attributes such as intensity, amplitude and deviation of the returned 1550nm laser pulse fall into discrete ranges associated with glassy, pumiceous and crystalline textures on both the rhyolitic and basaltic surfaces. This enables detection of vesicularity at ranges in excess of 500 m, making LiDAR a useful tool for remotely determining lava texture. Scan times using our Riegl VZ1000 and VZ400 systems require only minutes, allowing for repeated scans over a short time period, and processing times are <1 hour. We have also analyzed the full digitized waveforms of LiDAR pulses returned from these surfaces, and find that they also have unique signatures related to texture. We therefore suggest that LiDAR can provide reliable information on lava texture during eruption, aiding in the interpretation of eruption hazards from increasing volatile contents.

  4. Eroding Lava Flows

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    Today's image illustrates how radically the wind can affect the surface of Mars. The lava flows in this region have been covered by fine materials, and eroded by the sand blasting action of the wind. In this region the winds are blowing to the west, eroding the lava surface to form small east/west ridges and bumps. Given enough time the winds will change the appearance of the surface to such a large extent that all flow features will be erased.

    Image information: VIS instrument. Latitude -11.7, Longitude 220 East (140 West). 17 meter/pixel resolution.

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

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

  5. Lost Jim Lava Flow, Seward Peninsula, Alaska as an analog for lava-ice interactions on Mars

    NASA Astrophysics Data System (ADS)

    Marcucci, E.; Hamilton, C.; Herrick, R. R.

    2015-12-01

    On Mars, volcanism within Elysium Planitia may have occurred as recently as ~10 million years ago, which associated lava flows being emplaced with ice-bearing permafrost. On Earth, there are few active volcanic regions that are cold enough to support permafrost, but the Seward Peninsula in Alaska is a prime location to study recent volcano-ice interactions. In the early 2000s, J.E. Beget and J.S. Kargel explored two areas in Alaska that exhibit features characteristic of explosive volcanism that may be the result of lava-ice interaction. These locations include the Lost Jim Lava Flow (65°29'N, 163°17'W) and several large maars (66°23'N, 164°29'W). The work presented here focuses on the Lost Jim Lava Flow, emanating from Lost Jim Cone and flowing West and North. The flow was erupted 1000-2000 years ago, covers ~225 km2, and ranges 3-30 m in thickness. Previous fieldwork identified pits along the margins of the flow that were interpreted to be collapse features (i.e., thermokarst) that formed as ground-ice beneath the lava melted due to heat transfer from the overlaying lava flow. This investigation utilizes stereo photogrammetry to generate high-resolution digital terrain models (DTMs) of these flow features to assess if these pits are indeed the products of thermokarstification, or if they are lava-rise pits formed by lava flow inflation. The DTMs were generated from ALOS PRISM data and DigitalGlobe Worldview 1 and 2 panchromatic satellite images taken as stereo-pairs or -triplets. With these new models the extent and morphology of the flow and pits will be categorized across the entire flow. These results are also compared to young lava flows on Mars, which may have experienced lava-ice interactions. Understanding the expression of such interactions on Earth may aid in the identification and interpretation of analogous eruptions on Mars.

  6. The GREGOR dome, pathfinder for the EST dome

    NASA Astrophysics Data System (ADS)

    Hammerschlag, Robert H.; Kommers, Johannes N.; Visser, Simon; Bettonvil, Felix C. M.; van Schie, Anton G. M.; van Leverink, Simon J.; Sliepen, Guus; Jägers, Aswin P. L.

    2012-09-01

    The completely open-foldable dome of the GREGOR telescope is a further development of the DOT dome, respectively 9 and 7 meter in diameter. New technical developments are implemented and tested at the GREGOR dome, that are important for the design of the much larger dome for the EST, which will be 28 meter in diameter. The GREGOR dome is the first with more than one clamp working simultaneously for closing the dome and bringing the membranes on the required high tension for storm resistance. The storm Delta with 245 km/h 1-minute mean maximum at the location of the GREGOR gave no problems nor did the storms afterwards. Opening and closing experiences are up to wind speeds of 90 km/h without problems. Good observing circumstances never occur with higher wind speeds. A double layer of membranes is applied in the GREGOR construction whereas the DOT dome is equipped with a single layer. Simultaneous climate measurements inside and outside the dome have proven the thermal-insulation capability of this double-layer construction. The experiences with the GREGOR showed that the elongation by tensioning of the prestrained membrane material is much lower than originally expected. In the meantime, more strong and stiff membrane material is available and applied in the EST design. As a consequence, the clamps of the EST can have a relatively much shorter length and there is no need anymore for simultaneous operation of the clamps and the main actuators in low speed with help of a frequency inverter. The clamps can close after the main bow operation is finished, which simplifies the electrical control.

  7. Lava Flows in the Grand Canyon

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Over vast expanses of time, natural processes like floods and volcanoes deposit layers of rock on the Earth's surface. To delve down through layers of rock is to explore our planet's history. Sometimes rock layers are exposed through human activity, such as drilling or excavation. Other times, rivers carve through the rock. One of the best, and most well-known, examples of a river exposing ancient rocks is Colorado River in Arizona's Grand Canyon. What fewer people know is that the Grand Canyon also has a history of relatively recent (on geologic time scales) volcanism. The evidence--hardened lava--spills down the canyon walls all the way to the river. On June 22, 2003, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this image of the Grand Canyon, near 36.2 degrees north latitude and 113.2 degrees west longitude. ASTER detects light visible to human eyes as well as 'invisible' infrared light. Because different minerals reflect different portions of the light spectrum, ASTER can see varying mineral compositions of the rocks it observes, as well as detecting vegetation. In this three-dimensional visualization, lava fields appear brownish gray, darker than the layers of limestone, sandstone and other rock in the canyon. Vegetation appears green, and sparsely vegetated areas appear mustard. Water in the Colorado River is blue-purple. Geologists estimate that between 1.8 million and 400,000 years ago, lava flows actually dammed the Colorado River more than a dozen times. Some of the lava dams were as high as 600 meters (about 1,969 feet), forming immense reservoirs. Over time, enough water and sediment built up to push the river flow over the tops of these dams and eventually erode them away. Today, remnants of these lava dams remain throughout the area, along with the much older rock layers they cover. Among the most well known examples of these 'frozen' lava cascades is Lava Falls, which spills down to the

  8. Effusive silicic volcanism in the Central Andes: The Chao dacite and other young lavas of the Altiplano-Puna Volcanic Complex

    NASA Technical Reports Server (NTRS)

    De Silva, S. L.; Self, S.; Francis, P. W.; Drake, R. E.; Ramirez, Carlos R.

    1994-01-01

    The largest known Quaternary silicic lava body in the world is Cerro Chao in north Chile, a 14-km-long coulee with a volume of at least 26 cu km. It is the largest of a group of several closely similar dacitic lavas erupted during a recent (less than 100,000 year old) magmatic episode in the Altiplano-Puna Volcanic Complex (APVC; 21-24 deg S) of the Centra; Andean Volcanic Zone. The eruption of Chao proceeded in three phases. Phase 1 was explosive and produced approximately 1 cu km of coarse, nonwelded dacitic pumice deposits and later block and ash flows that form an apron in front of the main lava body. Phase 2 was dominantly effusive and erupted approximately 22.5 cu km of magma in the form of a composite coulee covering approximately 53 sq km with a 400-m-high flow front and a small cone of poorly expanded pumice around the vent. The lava is homogeneous with rare flow banding and vesicular tops and selvages. Ogives (flow ridges) reaching heights of 30 m form prominent features on its surface. Phase 3 produced a 6-km-long, 3-km-wide flow that emanated from a collapsed dome. Ogives are subdued, and the lava is glassier than that produced in previous phases. All the Chao products are crystal-rich high-K dacites and rhyodacites with phenocrysts of plagioclase, quartz, hornblende, biotite, sphene, rare snidine, and oxides. Phenocryst contents reach 40-60 vol % (vesicle free) in the main phase 2 lavas but are lower in the phase 1 (20-25%) and phase 3 (approximately 40%) lavas. Ovoid andesitic inclusions with vesicular interiors and chilled margins up to 10 cm are found in the later stages of phase 2 and compose up to 5% of the phase 3 lava. There is little evidence for preeruptive zonation of the magma body in composition, temperature (approximately 840 C), fO2 (19(exp -11), or water content, so we propose that eruption of the Chao complex was driven by intrusion of fresh, hot andesitic magma into a crystallizing and largely homogeneous body of dacitic magma

  9. Silica-rich lavas in the oceanic crust: experimental evidence for fractional crystallization under low water activity

    NASA Astrophysics Data System (ADS)

    Erdmann, Martin; Koepke, Jürgen

    2016-10-01

    We experimentally investigated phase relations and phase compositions as well as the influence of water activity ( aH2O) and redox conditions on the equilibrium crystallization path within an oceanic dacitic potassium-depleted system at shallow pressure (200 MPa). Moreover, we measured the partitioning of trace elements between melt and plagioclase via secondary ion mass spectrometry for a highly evolved experiment (SiO2 = 74.6 wt%). As starting material, we used a dacitic glass dredged at the Pacific-Antarctic Rise. Phase assemblages in natural high-silica systems reported from different locations of fast-spreading oceanic crust could be experimentally reproduced only in a relatively small range of temperature and melt-water content ( T ~950 °C; melt H2O < 1.5 wt%) at redox conditions slightly below the quartz-fayalite-magnetite buffer. The relatively low water content is remarkable, because distinct hydrothermal influence is generally regarded as key for producing silica-rich rocks in an oceanic environment. However, our conclusion is also supported by mineral and melt chemistry of natural evolved rocks; these rocks are only congruent to the composition of those experimental phases that are produced under low aH2O. Low FeO contents under water-saturated conditions and the characteristic enrichment of Al2O3 in high aH2O experiments, in particular, contradict natural observations, while experiments with low aH2O match the natural trend. Moreover, the observation that highly evolved experimental melts remain H2O-poor while they are relatively enriched in chlorine implies a decoupling between these two volatiles during crustal contamination.

  10. A Dome Amidst the Hexagons

    ERIC Educational Resources Information Center

    American School and University, 1976

    1976-01-01

    Describes the design of the gymnasium of York (South Carolina) Comprehensive High School, a circular 12,000 square foot structure with a prefabricated domed roof constructed of steel hubs and curved wooden beams. (JG)

  11. Dating transitionally magnetized lavas of the late Matuyama Chron: Toward a new 40Ar/39Ar timescale of reversals and events

    NASA Astrophysics Data System (ADS)

    Singer, Bradley S.; Hoffman, Kenneth A.; Chauvin, Annick; Coe, Robert S.; Pringle, Malcolm S.

    1999-01-01

    The K-Ar based geomagnetic polarity timescale was constructed using data from lavas and tuffs that bracketed, but rarely dated, the transitions between polarity intervals. Subsequent 40Ar/39Ar dating indicated that the ages of some polarity transitions had been underestimated by about 6%. Although the accepted ages of the polarity chron boundaries have increased, their precise temporal definition remained uncertain. We have taken a different approach and used incremental-heating techniques to obtain 18 new 40Ar/39Ar ages from basaltic lavas within flow sequences at Punaruu Valley, Tahiti, and Haleakala volcano, Hawaii. These lavas record transitional paleomagnetic directions corresponding to four mid-Pleistocene polarity reversals or events. Three lavas from Punaruu Valley previously thought to record the Cobb Mountain Normal Polarity Subchron (CMNS) gave a mean age of 1.105+/-0.005Ma, indicating that they were erupted about 76 kyr after the CMNS; this period of transitional field behavior is designated the Punaruu event. In addition, seven new 40Ar/39Ar ages from the Punaruu Valley indicate that the Jaramillo Normal Polarity Subchron (JNS) lasted about 67 kyr, starting at 1.053+/-0.006Ma and ending 0.986+/-0.005Ma. This agrees with astronomical estimates but conflicts with JNS ages proposed by Spell and McDougall [1992] and Izett and Obradovich [1994] on the basis of 40Ar/39Ar dating of rhyolite domes in the Valles Caldera. Indistinguishable 40Ar/39Ar ages of seven lavas, including one from Punaruu Valley and six from Haleakala that record broadly similar intermediate paleodirections, suggest that the Kamikatsura event occurred at 0.886+/-0.003Ma. Moreover, these data indicate that the Kamikatsura event occurred 20-40 kyr after another geomagnetic event, most probably taking place at 0.92 Ma. We designate this earlier field behavior the Santa Rosa event, adopting its name from that of a transitionally magnetized rhyolite dome which happened to figure prominently

  12. Dome: Distributed Object Migration Environment

    DTIC Science & Technology

    1994-05-01

    Best Available Copy AD-A281 134 Computer Science Dome: Distributed object migration environment Adam Beguelin Erik Seligman Michael Starkey May 1994...Beguelin Erik Seligman Michael Starkey May 1994 CMU-CS-94-153 School of Computer Science Carnegie Mellon University Pittsburgh, PA 15213 Abstract Dome... Linda [4], Isis [2], and Express [6] allow a pro- grammer to treat a heterogeneous network of computers as a parallel machine. These tools allow the

  13. The 13 ka Pelée-Type Dome Collapse at Nevado de Toluca Volcano, México.

    NASA Astrophysics Data System (ADS)

    D'Antonio, M.; Capra, L.; Sarocchi, D.; Bellotti, F.

    2007-05-01

    The Nevado de Toluca is an active volcano located in the central sector of the Trans-Mexican Volcanic Belt, 80 km southwest of Mexico City. Activity at this andesitic to dacitic stratovolcano began ca. 2.6 Ma ago. During the last 42 ka, the volcano has been characterized by different eruptive styles, including five dome collapses dated at 37, 32, 28, 26, and 13 ka and five Plinian eruptions at 42 ka, 36 ka, 21.7 ka, 12.1 ka and 10.5 ka. The 13 ka dome collapse is the youngest event of this type, and originated a 0.11 km3 block-and-ash flow deposit on the north-eastern sector of the volcano. The deposit consists of two facies: channel-like, 10 m thick, monolitologic, that is composed of up to five units, with decimetric dacitic clasts set in a sandy matrix; and a lateral facies that consists of a gray, sandy horizon, up to 4 m thick, with a 30 cm-thick surge layer at the base. The main component is a dacitic lava, with different degree of vesciculation, with mineral association of Pl-Hbl-Opx. Plagioclases show two different textures: in equilibrium, with normal zoning (core = An37-64.3, rim = An30.7-45.8) or with spongy cellular texture with inverse zoning (core = An38-43.5, rim = An45-51.2). Hornblende is normally light green, barren of oxidation. The rock matrix contains up to 53 perc. of glass with abundant microlites, indicating over-pressure on the crystallizing magma and a rapid expulsion. All these stratigraphic and petrographic features indicate that the dome was quickly extruded on the summit of the volcano, probably triggered by a magma mixing process, and its collapse was accompanied by an explosive component, being classified as a Pelée-type event.

  14. Benchmarking computational fluid dynamics models for lava flow simulation

    NASA Astrophysics Data System (ADS)

    Dietterich, Hannah; Lev, Einat; Chen, Jiangzhi

    2016-04-01

    Numerical simulations of lava flow emplacement are valuable for assessing lava flow hazards, forecasting active flows, interpreting past eruptions, and understanding the controls on lava flow behavior. Existing lava flow models vary in simplifying assumptions, physics, dimensionality, and the degree to which they have been validated against analytical solutions, experiments, and natural observations. In order to assess existing models and guide the development of new codes, we conduct a benchmarking study of computational fluid dynamics models for lava flow emplacement, including VolcFlow, OpenFOAM, FLOW-3D, and COMSOL. Using the new benchmark scenarios defined in Cordonnier et al. (Geol Soc SP, 2015) as a guide, we model viscous, cooling, and solidifying flows over horizontal and sloping surfaces, topographic obstacles, and digital elevation models of natural topography. We compare model results to analytical theory, analogue and molten basalt experiments, and measurements from natural lava flows. Overall, the models accurately simulate viscous flow with some variability in flow thickness where flows intersect obstacles. OpenFOAM, COMSOL, and FLOW-3D can each reproduce experimental measurements of cooling viscous flows, and FLOW-3D simulations with temperature-dependent rheology match results from molten basalt experiments. We can apply these models to reconstruct past lava flows in Hawai'i and Saudi Arabia using parameters assembled from morphology, textural analysis, and eruption observations as natural test cases. Our study highlights the strengths and weaknesses of each code, including accuracy and computational costs, and provides insights regarding code selection.

  15. Modeling deformation associated with the 2004-2008 dome-building eruption of Mount St. Helens

    NASA Astrophysics Data System (ADS)

    Lisowski, M.; Battaglia, M.

    2011-12-01

    0.010 ± 0.001 cubic km. The best-fitting source for the far-field inflation is a prolate spheroid of geometric aspect ratio 0.12 ± 0.2, a depth of 7.3 ± 0.6 km, and a cavity volume increase of 0.006 ± 0.001 cubic km. The source dips slightly to the north (dip angle: 75 ± 4; strike angle 357 ± 8). Both sources are located beneath the dome. These results suggest that the same deep magma source has been active beneath the volcano for the past 7 years. This source fed the dome eruption and is now slowly being filled. The shallow source controlling the near-field, post-eruption deformation is probably due to the cooling and contraction of the lava dome within the crater.

  16. Radar scattering properties of steep-sided domes on Venus

    NASA Technical Reports Server (NTRS)

    Ford, Peter G.

    1994-01-01

    More than 100 quasi-circular steep-sided volcanic domes, with diameters ranging from 6 to 60 km, have been observed on the surface of Venus by the Magellan radar mapper. Assuming that they have the shape of a solidified high-viscosity Newtonian fluid, their radar scattering properties can be studied in detail from Magellan images, since a typical radar swath resolves each dome into several tens of thousands of measurements of radar cross section at incidence angles varying fom 15 deg to 55 deg. Through examination of 20 domes in detail, it appears that many of those situated on lava plains scatter radar in a manner that is indistinguishable from that of the surrounding material, suggesting that either (1) they were formed of a relatively high-density high-viscosity material, e.g., andesite, rather than a lower-density one, e.g., rhyolite or dacite; or (2) that their surfaces share a common origin with those of their surroundings, e.g., through in situ weathering or aeolian deposition.

  17. Map Showing Lava Inundation Zones for Mauna Loa, Hawaii

    USGS Publications Warehouse

    Trusdell, F.A.; Graves, P.; Tincher, C.R.

    2002-01-01

    Introduction The Island of Hawaii is composed of five coalesced basaltic volcanoes. Lava flows constitute the greatest volcanic hazard from these volcanoes. This report is concerned with lava flow hazards on Mauna Loa, the largest of the island shield volcanoes. Hilo lies 58 km from the summit of Mauna Loa, the Kona coast 33 km, and the southernmost point of the island 61 km. Hawaiian volcanoes erupt two morphologically distinct types of lava, aa and pahoehoe. The surfaces of pahoehoe flows are rather smooth and undulating. Pahoehoe flows are commonly fed by lava tubes, which are well insulated, lava-filled conduits contained within the flows. The surfaces of aa flows are extremely rough and composed of lava fragments. Aa flows usually form lava channels rather than lava tubes. In Hawaii, lava flows are known to reach distances of 50 km or more. The flows usually advance slowly enough that people can escape from their paths. Anything overwhelmed by a flow will be damaged or destroyed by burial, crushing, or ignition. Mauna Loa makes up 51 percent of the surface area of the Island of Hawaii. Geologic mapping shows that lava flows have covered more than 40 percent of the surface every 1,000 years. Since written descriptions of its activity began in A.D. 1832, Mauna Loa has erupted 33 times. Some eruptions begin with only brief seismic unrest, whereas others start several months to a year following increased seismic activity. Once underway, the eruptions can produce lava flows that reach the sea in less than 24 hours, severing roads and utilities. For example, the 1950 flows from the southwest rift zone reached the ocean in approximately three hours. The two longest flows of Mauna Loa are pahoehoe flows from the 50-kilometer-long 1859 and the 48-kilometer-long 1880-81 eruptions. Mauna Loa will undoubtedly erupt again. When it does, the first critical question that must be answered is: Which areas are threatened with inundation? Once the threatened areas are

  18. Preliminary Results on the Mechanics of the Active Mai'iu Low Angle Normal Fault (Dayman Dome), Woodlark Rift, SE Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Little, T. A.; Boulton, C. J.; Mizera, M.; Webber, S. M.; Oesterle, J.; Ellis, S. M.; Norton, K. P.; Wallace, L. M.; Biemiller, J.

    2015-12-01

    Rapid slip on the Mai'iu low-angle normal fault (LANF) has exhumed a smooth, corrugated fault surface contiguous for >24 km up-dip, rising from near sea level to ~2900 m. The fault emerges from the ground dipping ~21° N and flattens over the crest of the dome to dip south. Geomorphic analysis reveals a progressive back-tilting of the surface during exhumation accompanied by cross-cutting antithetic-sense high-angle faults—features that we attribute to "rolling-hinge" deformation of a once more steeply-dipping fault. Near the scarp base, the footwall exposes mafic mylonites that deformed at ~400-450°C. The younger Mai'iu fault cross-cuts this ductile mylonite zone, with most brittle slip being localized into a ~20 cm-thick, gouge-filled core. Near the range front, active faults bite across both the hangingwall and footwall of the Mai'iu fault and record overprinting across a dying, shallow (<~1 km deep) part of the fault by more optimally oriented, steeper faults. Such depth-dependent locking up of the fault suggests it weakens primarily by friction reduction rather than cohesion loss. Outcrop-scale fractures in the exhumed footwall reflect formation in an Andersonian stress regime. Previous campaign GPS data suggest the fault slips at up to ~1 cm/yr. To improve resolution and test for aseismic creep, we installed 12 GPS sites across the fault trace in 2015. Quantitative XRD indicates the gouges were derived primarily from mafic footwall, containing up to 65% corrensite and saponite. Hydrothermal friction experiments on two gouges from a relict LANF strand were done at varying normal stresses (30-120 MPa), temperatures (50-200oC), and sliding velocities (0.3-100 μm/s). Results reveal very weak frictional strength (μ=0.13-0.15 and 0.20-0.28) and velocity-strengthening behavior conducive to fault creep. At the highest temperatures (T≥150oC) and lowest sliding velocities (<3 μm/s), a transition to velocity-weakening behavior indicates the potential for

  19. Cell confluency-induced Stat3 activation regulates NHE3 expression by recruiting Sp1 and Sp3 to the proximal NHE3 promoter region during epithelial dome formation.

    PubMed

    Su, Hsiao-Wen; Wang, Shainn-Wei; Ghishan, Fayez K; Kiela, Pawel R; Tang, Ming-Jer

    2009-01-01

    Activation of signal transducer and activator of transcription-3 (Stat3) during cell confluency is related to its regulatory roles in cell growth arrest- or survival-related physiological or developmental processes. We previously demonstrated that this signaling event triggers epithelial dome formation by transcriptional augmentation of sodium hydrogen exchanger-3 (NHE3) expression. However, the detailed molecular mechanism remained unclear. By using serial deletions, site-directed mutagenesis, and EMSA analysis, we now demonstrate Stat3 binding to an atypical Stat3-response element in the rat proximal NHE3 promoter, located adjacent to a cluster of Sp cis-elements (SpA/B/C), within -77/-36 nt of the gene. SpB (-58/-55 nt) site was more effective than SpA (-72/-69 nt) site for cooperative binding of Sp1/Sp3. Increasing cell density had no effect on Sp1/Sp3 expression but resulted in their increased binding to the SpA/B/C probe along with Stat3 and concurrently with enhanced nuclear pTyr705-Stat3 level. Immunoprecipitation performed with the nuclear extracts demonstrated physical interaction of Stat3 and Sp1/Sp3 triggered by cell confluency. Stat3 inhibition by overexpression of dominant-negative Stat3-D mutant in MDCK cells or by small interfering RNA-mediated knockdown in Caco-2 cells resulted in inhibition of the cell density-induced NHE3 expression, Sp1/Sp3 binding, and NHE3 promoter activity and in decreased dome formation. Thus, during confluency, ligand-independent Stat3 activation leads to its interaction with Sp1/Sp3, their recruitment to the SpA/B/C cluster in a Stat3 DNA-binding domain-dependent fashion, increased transcription, and expression of NHE3, to coordinate cell density-mediated epithelial dome formation.

  20. Support of LAVA Integration and Testing

    NASA Technical Reports Server (NTRS)

    Jackson, Marcus Algernon

    2014-01-01

    The Lunar Advanced Volatile Analysis (LAVA) subsystem is a part of the Regolith and Environment Science & Oxygen and Lunar Volatile Analysis (RESOLVE) Payload that will fly to the lunar pole on the Resource Prospector Mission (RPM) in 2019. The purpose of the mission is to characterize the water on the surface and subsurface of the moon in various locations in order to map the distribution. This characterization of water will help to understand how feasible water is as a resource that can be used for drinking water, breathable air, and propellants in future missions. This paper describes the key support activities performed during a 10 week internship; specifically, troubleshooting the Near Infrared Spectrometer for the Surge Tank (NIRST) instrument count loss, contributing to a clamp to be used in the installation of Resistive Temperature Detectors (RTDs) to tubing, performing a failure analysis of the LAVA Fluid Subsystem (FSS), and finalizing trade studies for release.

  1. Mount St. Helens erupts again: activity from September 2004 through March 2005

    USGS Publications Warehouse

    Major, Jon J.; Scott, William E.; Driedger, Carolyn; Dzurisin, Dan

    2005-01-01

    Eruptive activity at Mount St. Helens captured the world’s attention in 1980 when the largest historical landslide on Earth and a powerful explosion reshaped the volcano, created its distinctive crater, and dramatically modified the surrounding landscape. Over the next 6 years, episodic extrusions of lava built a large dome in the crater. From 1987 to 2004, Mount St. Helens returned to a period of relative quiet, interrupted by occasional, short-lived seismic swarms that lasted minutes to days, by months-to-yearslong increases in background seismicity that probably reflected replenishment of magma deep underground, and by minor steam explosions as late as 1991. During this period a new glacier grew in the crater and wrapped around and partly buried the lava dome. Although the volcano was relatively quiet, scientists with the U.S. Geological Survey and University of Washington’s Pacific Northwest Seismograph Network continued to closely monitor it for signs of renewed activity.

  2. Origin of phenocrysts and compositional diversity in pre-Mazama rhyodacite lavas, Crater Lake, Oregon

    USGS Publications Warehouse

    Nakada, S.; Bacon, C.R.; Gartner, A.E.

    1994-01-01

    Phenocrysts in porphyritic volcanic rocks may originate in a variety of ways in addition to nucleation and growth in the matrix in which they are found. Porphyritic rhyodacite lavas that underlie the eastern half of Mount Mazama, the High Cascade andesite/dacite volcano that contains Crater Lake caldera, contain evidence that bears on the general problem of phenocryst origin. Phenocrysts in these lavas apparently formed by crystallization near the margins of a magma chamber and were admixed into convecting magma before eruption. About 20 km3 of pre-Mazama rhyodacite magma erupted during a relatively short period between ~400 and 500 ka; exposed pre-Mazama dacites are older and less voluminous. The rhyodacites formed as many as 40 lava domes and flows that can be assigned to three eruptive groups on the basis of composition and phenocryst content. -from Authors

  3. Lava lakes on Io: New perspectives from modeling

    NASA Astrophysics Data System (ADS)

    Gregg, Tracy K. P.; Lopes, Rosaly M.

    2008-03-01

    Loki Patera (310° W, 12° N) is Io's largest patera at ˜180 km in diameter. Its morphology and distinct thermal behavior have led researchers to hypothesize that Loki Patera may either be an active lava lake that experiences periodic overturn, or a shallow depression whose floor is episodically resurfaced with thin flows. Using results from mathematical models, we suggest that a better model for Loki's behavior is the terrestrial superfast spreading East Pacific Rise (EPR), near 17°30 south. We propose that, like at the southern EPR, Loki Patera is underlain by a thin, persistent magma "lens" that feeds thin, temporary lava lakes within the patera. Also like the southern EPR, overspilling of the volcanic depression is rare, with most of the lava volume being emplaced via a subsurface network of lava tubes.

  4. Estimating dome seeing for LSST

    NASA Astrophysics Data System (ADS)

    Sebag, Jacques; Vogiatzis, Konstantinos

    2014-08-01

    Begin Dome seeing is a critical effect influencing the optical performance of ground based telescopes. A previously reported combination of Computational Fluid Dynamics (CFD) and optical simulations to model dome seeing was implemented for the latest LSST enclosure geometry. To this end, high spatial resolution thermal unsteady CFD simulations were performed for three different telescope zenith angles and four azimuth angles. These simulations generate time records of refractive index values along the optical path, which are post-processed to estimate the image degradation due to dome seeing. This method allows us to derive the distribution of seeing contribution along the different optical path segments that composed the overall light path between the entrance of the dome up to the LSST science camera. These results are used to recognize potential problems and to guide the observatory design. In this paper, the modeling estimates are reviewed and assessed relative to the corresponding performance allocation, and combined with other simulator outputs to model the dome seeing impact during LSST operations.

  5. Fracturing during ductile-brittle transition and development of flow banding in the Takanoobane Rhyolite lava of Aso volcano, Japan

    NASA Astrophysics Data System (ADS)

    Furukawa, K.; Uno, K.

    2014-12-01

    effusion. The continued lava effusion formed the large lava dome due to the high viscosity. The lava dome would be consequently squashed by its own weight. The lava was deformed by pure shear strain originated from the squashing. The highly vesicular parts formed by cavitation were flattened by the deformation and developed into the flow banding.

  6. Eruption and emplacement dynamics of a thick trachytic lava flow of the Sancy volcano (France)

    NASA Astrophysics Data System (ADS)

    Latutrie, Benjamin; Harris, Andrew; Médard, Etienne; Gurioli, Lucia

    2017-01-01

    A 70-m-thick, 2200-m-long (51 × 106 m3) trachytic lava flow unit underlies the Puy de Cliergue (Mt. Dore, France). Excellent exposure along a 400-m-long and 60- to 85-m-high section allows the flow interior to be accessed on two sides of a glacial valley that cuts through the unit. We completed an integrated morphological, structural, textural, and chemical analysis of the unit to gain insights into eruption and flow processes during emplacement of this thick silicic lava flow, so as to elucidate the chamber and flow dynamic processed that operate during the emplacement of such systems. The unit is characterized by an inverse chemical stratification, where there is primitive lava beneath the evolved lava. The interior is plug dominated with a thin basal shear zone overlying a thick basal breccia, with ramping affecting the entire flow thickness. To understand these characteristics, we propose an eruption model that first involves processes operating in the magma chamber whereby a primitive melt is injected into an evolved magma to create a mixed zone at the chamber base. The eruption triggered by this event first emplaced a trachytic dome, into which banded lava from the chamber base was injected. Subsequent endogenous dome growth led to flow down the shallow slope to the east on which the highly viscous (1012 Pa s) coulée was emplaced. The flow likely moved extremely slowly, being emplaced over a period of 4-10 years in a glacial manner, where a thick (>60-m) plug slid over a thin (5-m-thick) basal shear zone. Excellent exposure means that the Puy de Cliergue complex can be viewed as a case type location for understanding and defining the eruption and emplacement of thick, high-viscosity, silicic lava flow systems.

  7. Rhyolite domes in the Krafla area, North Iceland. Densities and deformation fields

    NASA Astrophysics Data System (ADS)

    Agustsdottir, T.; Einarsson, P.; Gudmundsson, M. T.

    2009-12-01

    Krafla is a central volcano in the Northern Volcanic Zone (NVZ) of Iceland. It began forming about 200 000 years BP, has a caldera, and is transected by a N10°A trending fissure swarm. Krafla’s products are mostly basaltic but rhyolite domes have formed around the caldera rims. Krafla’s products were mostly erupted during the last glacial period, 110 000 years BP to 10 000 years BP. Silicic rocks in Iceland are generally associated with central volcanoes and are often emplaced on or around caldera rims. Rhyolite magma can rise, due to buoyancy forces and either form a cryptodome in the shallow crust or rise to the surface, where it erupts. Due to its high viscosity and resistance to flow it often accumulates and forms a lava dome over the vent. A gravity survey was carried out in the area of Krafla in 2007 and 2008 to determine the mean bulk density values of rhyolite domes. Data on density and volumes is essential for meaningful modelling of the emplacement of cryptodomes and lava domes. Such data are scarce. Profiles were measured over three formations, ranging in size from Hlidarfjall (310 m high and 2 km long), formed under ice 90 000 years BP, to Hrafntinnuhryggur (80 m high and 2,5 km long) formed 24 000 years BP under a glacier to Hraunbunga (125 m high and 1,8 km long) formed 10 000 years BP. Mean bulk density for each formation was obtained by the Nettleton method. The results are that all the domes have low densities, reflecting both low grain-density and high porosity. The domes’s density values are significantly smaller than those of the surroundings, creating a density contrast possibly sufficient to drive the ascent of rhyolite magma. Furthermore, results from gravity data demonstrate that these formations are neither buried by younger volcanic eruptives nor are any roots detected. The domes studied were therefore emplaced as vent-forming domes. Additionally, we propose a model to describe the deformation field above a rising batch of magma

  8. Origin and deformation of high porosity bands in the Takanoobane Rhyolite lava of Aso volcano, Japan

    NASA Astrophysics Data System (ADS)

    Furukawa, K.; Uno, K.

    2015-10-01

    In rhyolite lavas, the high porosity bands are often developed. They potentially act as pathways for gas movement to the lava surface. Since explosive activities of lavas are generally considered to be controlled by degassing system, understanding the origin and deformation process of the high porosity bands is important to assessing volcanic hazards. The Takanoobane rhyolite lava in the middle of Kyushu Island in SW Japan is effused at 51 ± 5 ka. The volume, flow length, and thickness are 0.14 km3, > 2 km, and about 90 m, respectively. The central crystalline part of the lava is characterized by the light-colored bands defined by the high porosity zone (HPZ). On the basis of geological and petrographical studies, we revealed that the HPZ was primary formed by ductile-brittle tearing of the lava (known as cavitation). According to the AMS results, the HPZs were subsequently stretched and flattened laterally during the concentric spreading of the lava. This deformation process could stretch the HPZ not only radially but also laterally. This effective stretching developed the HPZ into pervasive thin bands. Since the HPZs act as degassing pathways to the lava surface, the pervasive HPZ bands may play a role in providing volcanic gasses to void spaces created in surface fold hinges of rhyolite lavas. Thus, this degassing system may promote explosive activity of the lava surface.

  9. Post-eruptive volcanic dome evolution as revealed by deformation and microgravity observations at Usu volcano (Hokkaido, Japan)

    NASA Astrophysics Data System (ADS)

    Jousset, Philippe; Okada, Hiromu

    1999-04-01

    Usu volcano (Hokkaido, Japan) is a dacitic volcano, known for its high production rate of lava domes and crypto-domes. It is thus a good target to study processes of volcanic dome evolution (upheaval and/or relaxation). We carried out repeated GPS and microgravity surveys on the three most recent domes of Mt. Usu (1910: Meiji Shinzan; 1943-1945: Showa-Shinzan and 1977-1982: Usu-Shinzan). The repeat period was 1 to 2 months and extended from October 1996 to June 1997. We also compare new data with results from former studies. More than 20 years after the start of Usu-Shinzan dome growth, there is still subsidence at a maximum rate of about 7 to 8 cm/year. The reasons for this subsidence are discussed. Repeated gravity surveys revealed an increase of gravity on the domes (about 60±10 microgal/year for Usu-Shinzan, about 15 microgal at Showa-Shinzan and 10 to 20 microgal for Meiji-shinzan); this gravity increase exceeds that expected due to subsidence. We discuss and interpret the excess gravity change in terms of a density increase in the edifice, caused by a combination of processes (contraction of the edifice, water level change, devesiculisation, cooling and magma intrusion). Quantification of these processes at Usu volcano may help to understand the processes of evolution at domes on other volcanoes such as Merapi (Indonesia), Unzen (Japan) or Montserrat (West Indies).

  10. Conceptual model for regional radionuclide transport from a salt dome repository: a technical memorandum

    SciTech Connect

    Kier, R.S.; Showalter, P.A.; Dettinger, M.D.

    1980-05-30

    Disposal of high-level radioactive wastes is a major environmental problem influencing further development of nuclear energy in this country. Salt domes in the Gulf Coast Basin are being investigated as repository sites. A major concern is geologic and hydrologic stability of candidate domes and potential transport of radionuclides by groundwater to the biosphere prior to their degradation to harmless levels of activity. This report conceptualizes a regional geohydrologic model for transport of radionuclides from a salt dome repository. The model considers transport pathways and the physical and chemical changes that would occur through time prior to the radionuclides reaching the biosphere. Necessary, but unknown inputs to the regional model involve entry and movement of fluids through the repository dome and across the dome-country rock interface and the effect on the dome and surrounding strata of heat generated by the radioactive wastes.

  11. Late Pleistocene zircon ages for intracaldera domes at Gölcük (Isparta, Turkey)

    NASA Astrophysics Data System (ADS)

    Schmitt, Axel K.; Danišík, Martin; Siebel, Wolfgang; Elitok, Ömer; Chang, Yu-Wei; Shen, Chuan-Chou

    2014-10-01

    Pleistocene to Quaternary volcanism in the Isparta region (SW Anatolia, Turkey) comprises potassic lavas and pyroclastic deposits, which are largely centered around Gölcük caldera. Trachytic intracaldera lava domes represent the latest eruptive event at Gölcük, and their eruption age is crucial for defining a minimum age for the preceding caldera-forming explosive eruption. Here, we present combined U-Th and (U-Th)/He zircon geochronological data for two intracaldera lava domes constraining their crystallization and eruption ages, respectively. U-Th zircon crystallization ages peak between ca. 15 and 25 ka. In rare instances U-Th zircon crystallization ages date back to ca. 59 and 136 ka. U-Th zircon crystallization ages also permit (U-Th)/He eruption ages from the same crystals to be individually corrected for uranium series decay chain disequilibrium, which is mainly due to the deficit of the intermediate daughter 230Th in zircon. Average disequilibrium-corrected (U-Th)/He zircon ages are 14.1 ± 0.5 and 12.9 ± 0.4 ka (1σ). These ages are indistinguishable within analytical uncertainties suggesting that both lavas erupted quasi simultaneously. This contradicts published K-Ar ages that suggest an extended hiatus from ca. 52 to 24 ka between intracaldera dome eruptions. Evidence for protracted zircon crystallization over several thousands of years prior to eruption indicates the presence of a long-lived magma reservoir underneath Gölcük caldera. Implications of the revised eruptive geochronology presented here include younger ages for the latest effusive eruptions at Gölcük, and potentially also a more recent explosive eruption than previously assumed.

  12. Using Landsat imagery and GIS to constrain late Miocene paleorelief and rates of erosion in the Hangay Dome, Mongolia

    NASA Astrophysics Data System (ADS)

    Smith, S. G.; Wegmann, K. W.; Bayasgalan, G.; Ancuta, L. D.; Gosse, J. C.

    2013-12-01

    Existing hypotheses maintain that the Hangay Dome of central Mongolia, situated significantly above continental freeboard and flanked by large strike-slip faults, is the result of relatively recent uplift, but ongoing geomorphological investigations of erosion rates, river incision, and paleotopography yield evidence to the contrary. For instance, Landsat Thematic Mapper (TM) imagery provides a unique opportunity to establish a 1st order approximation of local topographic relief at ~10 Ma. This age corresponds to the lowest layer in a thick (>600m) sequence of lava flows capping a 525 km2 area of high topography in the Hangay Dome (47.15°N, 100.05°E). The lava flows filled in and now preserve paleovalleys with ~700 m of local relief that are cut into basement. These paleovalleys exhibit similar relief to modern day, and are exposed along valley walls carved by Quaternary alpine glaciers. We quantify paleorelief in this remote mountain range by mapping the contact between basalt flows and granitic basement with ArcGIS and Landsat TM imagery. Spectral contrast between basalt and granite is maximized in a 1-5-6 band combination, and field mapping served to ground-truth the contact in certain areas. From this contact, a basal surface was interpolated and inferred to represent local topography at the time of the lowermost basalt flow (~10 Ma). Hypsometry, zonal statistics and topographic profile analysis indicate that relief of the relict surface is analogous to that of the present day. A similar GIS technique was applied to calculate the volume of rock removed since 6.13 Ma, which is the age for the uppermost, ridge-top basalt flow. In this experiment, a post-eruptive landscape was constructed by ';filling in' the post-lava flow valleys that are now incised into the upper lava flow surface. Subtracting the modern landscape from the post-eruptive surface yields the removal of 118 km3 of rock. Normalized for the study area, this results in a late Miocene to present net

  13. Lava flow hazard modeling during the 2014-2015 Fogo eruption, Cape Verde

    NASA Astrophysics Data System (ADS)

    Cappello, Annalisa; Ganci, Gaetana; Calvari, Sonia; Pérez, Nemesio M.; Hernández, Pedro A.; Silva, Sónia V.; Cabral, Jeremias; Del Negro, Ciro

    2016-04-01

    Satellite remote sensing techniques and lava flow forecasting models have been combined to enable a rapid response during effusive crises at poorly monitored volcanoes. Here we used the HOTSAT satellite thermal monitoring system and the MAGFLOW lava flow emplacement model to forecast lava flow hazards during the 2014-2015 Fogo eruption. In many ways this was one of the major effusive eruption crises of recent years, since the lava flows actually invaded populated areas. Combining satellite data and modeling allowed mapping of the probable evolution of lava flow fields while the eruption was ongoing and rapidly gaining as much relevant information as possible. HOTSAT was used to promptly analyze MODIS and SEVIRI data to output hot spot location, lava thermal flux, and effusion rate estimation. This output was used to drive the MAGFLOW simulations of lava flow paths and to continuously update flow simulations. We also show how Landsat 8 OLI and EO-1 ALI images complement the field observations for tracking the flow front position through time and adding considerable data on lava flow advancement to validate the results of numerical simulations. The integration of satellite data and modeling offers great promise in providing a unified and efficient system for global assessment and real-time response to effusive eruptions, including (i) the current state of the effusive activity, (ii) the probable evolution of the lava flow field, and (iii) the potential impact of lava flows.

  14. Compositionally Constraining Elysium Lava Fields

    NASA Astrophysics Data System (ADS)

    Karunatillake, S.; Button, N. E.; Skok, J. R.

    2013-12-01

    Chemical provinces of Mars defined recently [1-3] became possible with the maps of elemental mass fractions generated with Mars Odyssey Gamma and Neutron Spectrometer (GS) data [4,5]. These provide a unique perspective by representing compositional signatures distinctive of the regolith vertically at decimeter depths and laterally at hundreds of kilometer scale. Some provinces overlap compellingly with regions highlighted by other remote sensing observations, such as the Mars Radar Stealth area [3]. The spatial convergence of mutually independent data with the consequent highlight of a region provides a unique opportunity of insight not possible with a single type of remote sensing observation. Among such provinces, previous work [3] highlighted Elysium lava flows as a promising candidate on the basis of convergence with mapped geologic units identifying Elysium's lava fields generally, and Amazonian-aged lava flows specifically. The South Eastern lava flows of Elysium Mons, dating to the recent Amazonian epoch, overlap compellingly with a chemical province of K and Th depletion relative to the Martian midlatitudes. We characterize the composition, geology, and geomorphology of the SE Elysium province to constrain the confluence of geologic and alteration processes that may have contributed to its evolution. We compare this with the North Western lava fields, extending the discussion on chemical products from the thermal evolution of Martian volcanism as discussed by Baratoux et al. [6]. The chemical province, by regional proximity to Cerberus Fossae, may also reflect the influence of recently identified buried flood channels [7] in the vicinity of Orcus Patera. Despite the compelling chemical signature from γ spectra, fine grained unconsolidated sediment hampers regional VNTIR (Visible, Near, and Thermal Infrared) spectral analysis. But some observations near scarps and fresh craters allow a view of small scale mineral content. The judicious synthesis of

  15. Deformation and seismic precursors to dome-collapse and fountain-collapse nuées ardentes at Merapi Volcano, Java, Indonesia, 1994-1998

    USGS Publications Warehouse

    Voight, B.; Young, K.D.; Hidayat, D.; ,; Purbawinata, M.A.; Ratdomopurbo, A.; ,; ,; Sayudi, D.S.; LaHusen, R.; Marso, J.; Murray, T.L.; Dejean, M.; Iguchi, M.; Ishihara, K.

    2000-01-01

    Following the eruption of January 1992, episodes of lava dome growth accompanied by generation of dome-collapse nuées ardentes occurred in 1994–1998. In addition, nuées ardentes were generated by fountain-collapse in January 1997, and the 1998 events also suggest an explosive component. Significant tilt and seismic precursors on varying time scales preceded these events. Deformation about the summit has been detected by electronic tiltmeters since November 1992, with inflation corresponding generally to lava dome growth, and deflation (or decreased inflation) corresponding to loss of dome mass. Strong short-term (days to weeks) accelerations in tilt rate and seismicity occurred prior to the major nuées ardentes episodes, apart from those of 22 November 1994 which were preceded by steadily increasing tilt for over 200 days but lacked short-term precursors. Because of the combination of populated hazardous areas and the lack of an issued warning, about 100 casualties occurred in 1994. In contrast, the strong precursors in 1997 and 1998 provided advance warning to observatory scientists, enabled the stepped raising of alert levels, and aided hazard management. As a result of these factors, but also the fortunate fact that the large nuées ardentes did not quite descend into populated areas, no casualties occurred. The nuée ardente episode of 1994 is interpreted as purely due to gravitational collapse, whereas those of 1997 and 1998 were influenced by gas-pressurization of the lava dome.

  16. Newberry Volcano's youngest lava flows

    USGS Publications Warehouse

    Robinson, Joel E.; Donnelly-Nolan, Julie M.; Jensen, Robert A.

    2015-01-01

    The central caldera is visible in the lower right corner of the center map, outlined by the black dashed line. The caldera collapsed about 75,000 years ago when massive explosions sent volcanic ash as far as the San Francisco Bay area and created a 3,000-ft-deep hole in the center of the volcano. The caldera is now partly refilled by Paulina and East Lakes, and the byproducts from younger eruptions, including Newberry Volcano’s youngest rhyolitic lavas, shown in red and orange. The majority of Newberry Volcano’s many lava flows and cinder cones are blanketed by as much as 5 feet of volcanic ash from the catastrophic eruption of Mount Mazama that created Crater Lake caldera approximately 7,700 years ago. This ash supports abundant tree growth and obscures the youthful appearance of Newberry Volcano. Only the youngest volcanic vents and lava flows are well exposed and unmantled by volcanic ash. More than one hundred of these young volcanic vents and lava flows erupted 7,000 years ago during Newberry Volcano’s northwest rift zone eruption.

  17. Sinkholes, collapse structures and large landslides in an active salt dome submerged by a reservoir: The unique case of the Ambal ridge in the Karun River, Zagros Mountains, Iran

    NASA Astrophysics Data System (ADS)

    Gutiérrez, Francisco; Lizaga, Iván

    2016-02-01

    Ambal ridge, covering 4 km2, is a salt pillow of Gachsaran Formation with significant salt exposures in direct contact with the Karun River, Zagros Mountains. The highly cavernous salt dome is currently being flooded by the Gotvand Reservoir, second largest in Iran. Geomorphic evidence, including the sharp deflection of the Karun River and defeated streams indicate that Ambal is an active halokinetic structure, probably driven by erosional unloading. Around 30% of the salt dome is affected by large landslides up to ca. 50 × 106 m3 in volume. Slope oversteepening related to fluvial erosion and halokinetic rise seems to be the main controlling factor. A total of 693 sinkholes have been inventoried (170 sinkholes/km2), for which a scaling relationship has been produced. The depressions occur preferentially along a belt with a high degree of clustering. This spatial distribution is controlled by the proximity to the river, slope gradient and halite content in the bedrock. A large compound depression whose bottom lies below the normal maximum level of the reservoir will likely be flooded by water table rise forming a lake. The impoundment of the reservoir has induced peculiar collapse structures 220-280 m across, expressed by systems of arcuate fissures and scarps. Rapid subsurface salt dissolution is expected to generate and reactivate a large number of sinkholes and may reactivate landslides with a significant vertical component due to lack of basal support.

  18. Constraints on the source of resurgent doming inferred from analogue and numerical modeling - Implications on the current feeding system of the Yenkahe dome-Yasur volcano complex (Vanuatu)

    NASA Astrophysics Data System (ADS)

    Brothelande, E.; Peltier, A.; Got, J.-L.; Merle, O.; Lardy, M.; Garaebiti, E.

    2016-08-01

    Resurgence, defined as the post-collapse long-term uplift of a caldera floor, is commonly attributed to a renewed rise of magma. The Yenkahe dome (Vanuatu) exhibits a common morphology - elongated with a graben on top - among resurgent domes, and is also one of the most active structures of the kind. In this study, we performed a joint analysis based on analogue and finite element numerical models to (1) constrain the width and depth of the long-term deformation intrusive source of the Yenkahe dome and (2) discuss the close association between the Yenkahe dome and the active Yasur cone. We consider the resurgent deformation at the surface to be driven by the uplift of a magma reservoir roof in depth. As the edifice deformation response depends on the medium and the source properties, the mechanical behavior of the upper crust and the nature of the source are modeled using two very different sets of hypotheses. Analogue modeling uses silicone putty, an analogue for a large viscous magma body, intruding a sand-plaster mixture reproducing a Mohr-Coulomb behavior for the crust. Numerical models consider the vertical displacement of a rigid indenter, allowing the conservation of a flat-shaped roof, into an elastoplastic material. Numerical and analogue models show different resurgent dome structures at depth but similar dome and graben morphologies in the surface. Inverse faults - or equivalent shearing zones - delimiting the dome provide an explanation for the confined nature of resurgent doming and the persistent volcanic activity on the dome border represented by the Yasur volcano. Analogue and numerical models together provide an estimation range of 1-1.8 km for the intrusive deformation source depth, and 1.3-2 km for its width. The proposed association between the Yenkahe dome and the Yasur volcano is compatible with such a shallow depth of the magma reservoir, and argues for a discontinuous resurgence process.

  19. Identifying hazards associated with lava deltas

    USGS Publications Warehouse

    Poland, Michael P.; Orr, Tim R.

    2014-01-01

    Lava deltas, formed where lava enters the ocean and builds a shelf of new land extending from the coastline, represent a significant local hazard, especially on populated ocean island volcanoes. Such structures are unstable and prone to collapse—events that are often accompanied by small explosions that can deposit boulders and cobbles hundreds of meters inland. Explosions that coincide with collapses of the East Lae ‘Apuki lava delta at Kīlauea Volcano, Hawai‘i, during 2005–2007 followed an evolutionary progression mirroring that of the delta itself. A collapse that occurred when the lava–ocean entry was active was associated with a blast of lithic blocks and dispersal of spatter and fine, glassy tephra. Shortly after delta growth ceased, a collapse exposed hot rock to cold ocean water, resulting in an explosion composed entirely of lithic blocks and lapilli. Further collapse of the delta after several months of inactivity, by which time it had cooled significantly, resulted in no recognizable explosion deposit. Seaward displacement and subsidence of the coastline immediately inland of the delta was measured by both satellite and ground-based sensors and occurred at rates of several centimeters per month even after the lava–ocean entry had ceased. The anomalous deformation ended only after complete collapse of the delta. Monitoring of ground deformation may therefore provide an indication of the potential for delta collapse, while the hazard associated with collapse can be inferred from the level of activity, or the time since the last activity, on the delta.

  20. The role of lava erosion in the formation of lunar rilles and Martian channels

    USGS Publications Warehouse

    Carr, M.H.

    1974-01-01

    Lava tubes and channels develop around active sources of low viscosity lava. The channels normally form without erosion; however, sustained flow can result in the incision of a lava channel and simulation of fluvial erosion features. Lava erosion by means of thermal incision was modelled by computer, erosion rates calculated, and these compared with rates observed terrestrially. Lunar sinuous rilles are examined in light of the proposed lava erosion. The mechanism explains many features of lunar rilles that were heretofore puzzling and implies erosion rates comparable to terrestrial rates. Many Mars channels also appear to form by the action of lava; however, the larger, more spectacular Mars channels do not appear to have been formed by the same process. ?? 1974.

  1. Magmatic architecture of dome-building eruptions at Volcán de Colima, Mexico

    NASA Astrophysics Data System (ADS)

    Lavallée, Yan; Varley, N. R.; Alatorre-Ibargüengoitia, M. A.; Hess, K.-U.; Kueppers, U.; Mueller, S.; Richard, D.; Scheu, B.; Spieler, O.; Dingwell, D. B.

    2012-01-01

    Changes in the physical, chemical and rheological properties of ascending magma regulate the style of volcanic eruptions. Volcán de Colima's eruptive cycles of lava dome growth and explosions have been thoroughly monitored during the period 1998-2010 and provide a remarkable opportunity for deepening our understanding of the underlying processes responsible for the evolution of magma properties. Here, we integrate direct observation with analytical and experimental data to: (1) constrain the configuration of the shallow plumbing system and its influence on eruptive activity, (2) describe the rheological behaviour of the magma and (3) assess the conditions that lead to fragmentation and, ultimately, to explosive eruptions. The configuration of the shallow plumbing system was inferred from direct observation of extrusion sites and porosity of the erupted products. During the ongoing eruptive phase, magma was never extruded from a central vent: Both explosive and effusive activities were restricted to discrete vents inside the crater. Extensive field-based density measurements on 500 blocks in pyroclastic flow deposits reveal a bimodality of porosity at values of 12 and 26 vol.%. The least porous rocks tend to be altered, whereas the more porous rocks are pristine. This bimodal distribution, combined with the lack of a central vent, suggests the presence of a central, dense, altered plug, the fragments of which are entrained during explosive eruptions. During effusive periods, the plug appears to deflect the ascent of magma at a shallow depth and, consequently, the site of lava extrusion. The rheological properties and deformation-induced seismogenic behaviour of the magmas were investigated using a uniaxial deformation apparatus instrumented with acoustic sensors. The homogeneity in the physicochemical properties of the erupted magma permits the description of a flow law at eruptive temperature and strain rate conditions. The crystal-rich magma of Volcán de Colima

  2. Salt dome discoveries mounting in Mississippi

    SciTech Connect

    Ericksen, R.L.

    1996-06-17

    Exploratory drilling around piercement salt domes in Mississippi has met with a string of successes in recent months. Exploration of these salt features is reported to have been initiated through the review of non-proprietary, 2D seismic data and subsurface control. This preliminary data and work were then selectively upgraded by the acquisition of additional, generally higher quality, conventional 2D seismic lines. This current flurry of successful exploration and ensuing development drilling by Amerada Hess Corp. on the flanks of salt domes in Mississippi has resulted in a number of significant Hosston discoveries/producers at: Carson salt dome in Jefferson Davis County; Dry Creek salt dome in Covington County, Midway salt dome in lamar County, Monticello salt dome in Lawrence County, and Prentiss salt dome in Jefferson Davis County. The resulting production from these fields is gas and condensate, with wells being completed on 640 acre production units.

  3. Patterns of Volcanism Associated With Oligocene to Recent Dome Uplift, West Antarctic Rift System

    NASA Astrophysics Data System (ADS)

    Le Masurier, W. E.

    2005-12-01

    The Marie Byrd Land dome lies on the Pacific coast of the West Antarctic rift system. It is a structural dome defined by elevations of a low-relief erosion surface that is exposed in fault- block nunataks. The dome has roughly 3000 m of structural relief and is about 800 km in diameter.The growth of the dome has been closely associated with two rather unusual patterns of volcanic activity that provide keys to the timing and rate of uplift. (1) The ages of basaltic rocks that rest on the erosion surface become systematically older with increasing elevation of the surface, e.g. 6.27 Ma at 600 m elevation, 27 Ma at 2700 m, etc., suggesting that uplift began around 27 Ma and continued to 6 Ma at roughly 100m/m.y. (2) The oldest of 18 felsic shield volcanoes formed around 19 Ma at the dome crest. The remaining felsic volcanoes become systematically younger toward the distal flanks of the dome, along linear, fault-controlled, N-S and E-W chains. Late Pleistocene (active) volcanoes lie at the north, south, east, and west margins of the dome, suggesting that uplift proceeded systematically from 19 Ma to the present by centrifugal extension of relict fractures during uplift, accompanied by the rise of felsic magmas from crustal reservoirs. Teleseismic studies (Winberry and Anandakrishnan, 2004) show that the crust has been thinned over the dome crest, and that the dome is supported by low density mantle. Tomographic images near the dome (Sieminski, et al., 2003) show a low velocity column extending down to the transition zone. The Antarctic plate has been stationary at least since the Eocene. In the apparent absence of a mechanism driven by plate tectonics, it is reasonable to infer that mantle plume activity has produced these spatial and temporal patterns of volcanism focused around dome uplift, rather than the more familiar linear volcanic chains associated with moving plates.

  4. Acoustic emissions accompanying the compressive ductile-brittle transition in highly- crystalline lavas.

    NASA Astrophysics Data System (ADS)

    Lavallee, Y.; Meredith, P.; Hess, K.; Cordonnier, B.; Dingwell, D. B.

    2007-12-01

    Understanding of the ductile-brittle transition in dome lavas may well contain the key to an adequate description of dome growth and stability. To elucidate this transition in dome lavas, a series of experiments were performed to characterize microcracking during compressive deformation of crystal-rich lavas. Multiphase lavas behave as visco-elastic fluids with a strain-rate dependence of viscosity across the ductile-brittle field. In order to map out the onset of brittle failure across the transition, we have deformed large volume samples (80 mm long by 40 mm diameter) in a high-load, high-temperature uniaxial press equipped with acoustic emission (AE) monitoring sensors. Our apparatus has been calibrated using an NBS717a standard glass. The absence of cracking and associated AE during deformation of this standard, which behaves as a homogeneous viscous melt under our experimental conditions, allows us to calibrate and filter out extraneous background noise. Samples from each of the five volcanoes chosen for this study (Colima, Unzen, Bezimianny, Krakatau, and Tungurahua) were deformed at two temperatures (940 and 980°C) and at stresses from 1 to 50 MPa. At low stresses (1-10 MPa), only a few AE events were detected and the AE rate decreased with increasing strain. Occasional high-energy events were recorded, and attributed to cracking of single crystals. Increasing the stress to 20-30 MPa resulted in an increased AE rate that stayed essentially constant with increasing strain. Occasional high-energy events persisted. At 40 and 50 MPa, the AE rate was higher still, and increased with increasing strain (overwhelming the few high energy events that continued to occur). Preliminary evaluation of the seismic b-value shows a decreasing trend from >3.0 at low stress to <1.5 at high stress, suggesting a shift from distributed small-scale cracking to more localized larger-scale cracking as stress is increased. These results will be discussed in terms of the deformation

  5. Thermal anomaly at the Earth's surface associated with a lava tube

    NASA Astrophysics Data System (ADS)

    Piombo, Antonello; Di Bari, Marco; Tallarico, Andrea; Dragoni, Michele

    2016-10-01

    Lava tubes are frequently encountered in volcanic areas. The formation of lava tubes has strong implications on the volcanic hazard during effusive eruptions. The thermal dissipation of lava flowing in a tube is reduced in respect to the lava flowing in an open channel so the lava may threaten areas that would not be reached by flows in open channels: for this reason it is important to detect the presence of lava tubes. In this work we propose a model to detect the presence and the characteristics of lava tubes by their thermal footprint at the surface. We model numerically the temperature distribution and the heat flow, both in the steady and the transient state, and we take into account the principal thermal effects due to the presence of an active lava tube, i.e. the conduction to the ground and the atmosphere, the convection and the radiation in the atmosphere. We assume that lava fluid is at high temperature, in motion inside a sloping tube under the gravity force. The thermal profile across the tube direction, in particular the width of the temperature curve, allows to evaluate the depth of the tube. The values of maximum temperature and of tube depth allow to estimate the area of the tube section. The shape of the temperature curve and its asymmetry can give information about the geometry of the tube. If we observe volcanic areas at different times by thermal cameras, we can detect anomalies and evaluate their causes during an eruption; in particular, we can evaluate whether they are due to active lava flows or not and what is their state. For lava tubes, we can connect thermal anomalies with lava tube position, characteristics and state.

  6. Subglacial lava propagation, ice melting and heat transfer during emplacement of an intermediate lava flow in the 2010 Eyjafjallajökull eruption

    NASA Astrophysics Data System (ADS)

    Oddsson, Björn; Gudmundsson, Magnús T.; Edwards, Benjamin R.; Thordarson, Thorvaldur; Magnússon, Eyjólfur; Sigurðsson, Gunnar

    2016-07-01

    During the 2010 Eyjafjallajökull eruption in South Iceland, a 3.2-km-long benmoreite lava flow was emplaced subglacially during a 17-day effusive-explosive phase from April 18 to May 4. The lava flowed to the north out of the ice-filled summit caldera down the outlet glacier Gígjökull. The flow has a vertical drop of about 700 m, an area of ca. 0.55 km2, the total lava volume is ca. 2.5·107 m3 and it is estimated to have melted 10-13·107 m3 of ice. During the first 8 days, the lava advanced slowly (<100 m day-1), building up to a thickness of 80-100 m under ice that was initially 150-200 m thick. Faster advance (up to 500 m day-1) formed a thinner (10-20 m) lava flow on the slopes outside the caldera where the ice was 60-100 m thick. This subglacial lava flow was emplaced along meltwater tunnels under ice for the entire 3.2 km of the flow field length and constitutes 90 % of the total lava volume. The remaining 10 % belong to subaerial lava that was emplaced on top of the subglacial lava flow in an ice-free environment at the end of effusive activity, forming a 2.7 km long a'a lava field. About 45 % of the thermal energy of the subglacial lava was used for ice melting; 4 % was lost with hot water; about 1 % was released to the atmosphere as steam. Heat was mostly released by forced convection of fast-flowing meltwater with heat fluxes of 125-310 kWm-2.

  7. Foldable dome climate measurements and thermal properties

    NASA Astrophysics Data System (ADS)

    Sliepen, Guus; Jägers, Aswin P. L.; Hammerschlag, Robert H.; Bettonvil, Felix C. M.

    2010-07-01

    As part of a larger project for measuring various aspects of foldable domes in the context of EST and with support of the Dutch Technology Foundation STW, we have collected over a year of continuous temperature and humidity measurements, both inside and outside the domes of the Dutch Open Telescope (DOT) on La Palma5 and the GREGOR telescope on Tenerife.6 In addition, we have measured the wind field around each dome. Although the structure of both domes is similar, the DOT dome has a single layer of cloth, and is situated on top of an open tower. In contrast, the GREGOR dome has a double layer of cloth, and is situated on top of a tower-shaped building. These differences result in large differences in temperature and humidity insulation when the dome is closed. We will present the changes in temperature and humidity one can expect for each dome within one day, and the statistics for the variations throughout a year. In addition, we will show that the main advantage of a foldable dome is the near instantaneous equilibration of the air inside the volume originally enclosed by the dome and that of the environment outside the dome. This property allows one to operate a telescope without needing expensive air conditioning and dome skin temperature control in order to limit dome and shell seeing effects. The measurements give also information about the weather fluctuations at the sites of the domes. It was observed that on small time scales the temperature fluctuations are significantly greater during the day than during the night.

  8. Lava flow hazard at Fogo Volcano, Cabo Verde, before and after the 2014-2015 eruption

    NASA Astrophysics Data System (ADS)

    Richter, Nicole; Favalli, Massimiliano; de Zeeuw-van Dalfsen, Elske; Fornaciai, Alessandro; da Silva Fernandes, Rui Manuel; Pérez, Nemesio M.; Levy, Judith; Silva Victória, Sónia; Walter, Thomas R.

    2016-08-01

    Lava flow simulations help to better understand volcanic hazards and may assist emergency preparedness at active volcanoes. We demonstrate that at Fogo Volcano, Cabo Verde, such simulations can explain the 2014-2015 lava flow crisis and therefore provide a valuable base to better prepare for the next inevitable eruption. We conducted topographic mapping in the field and a satellite-based remote sensing analysis. We produced the first topographic model of the 2014-2015 lava flow from combined terrestrial laser scanner (TLS) and photogrammetric data. This high-resolution topographic information facilitates lava flow volume estimates of 43.7 ± 5.2 × 106 m3 from the vertical difference between pre- and posteruptive topographies. Both the pre-eruptive and updated digital elevation models (DEMs) serve as the fundamental input data for lava flow simulations using the well-established DOWNFLOW algorithm. Based on thousands of simulations, we assess the lava flow hazard before and after the 2014-2015 eruption. We find that, although the lava flow hazard has changed significantly, it remains high at the locations of two villages that were destroyed during this eruption. This result is of particular importance as villagers have already started to rebuild the settlements. We also analysed satellite radar imagery acquired by the German TerraSAR-X (TSX) satellite to map lava flow emplacement over time. We obtain the lava flow boundaries every 6 to 11 days during the eruption, which assists the interpretation and evaluation of the lava flow model performance. Our results highlight the fact that lava flow hazards change as a result of modifications of the local topography due to lava flow emplacement. This implies the need for up-to-date topographic information in order to assess lava flow hazards. We also emphasize that areas that were once overrun by lava flows are not necessarily safer, even if local lava flow thicknesses exceed the average

  9. Quaternary geology of Vacherie salt dome, north Louisiana salt dome basin. Volume II

    SciTech Connect

    Kolb, C.R.; Holmes, J.C.; Alford, J.J.

    1983-07-01

    This volume comprises 14 appendices: lineations on Vacherie and Rayburn's domes (1977); possible geomorphic influence of Vacherie salt dome on the Quaternary fluvial geomorphology of Bashaway Creek (1980); remote sensing and analysis of radar imagery (1978); uphole seismic survey at Vacherie salt dome (1977); electrical resistivity survey at Vacherie salt dome (1978); pedologic investigations (1977); ionium-thorium dating of ironstones from terrace deposits, Vacherie salt dome, North Louisiana (1978); grain-shape and grain-surface studies (1981); the terrace concept - Gulf Coastal Plain (1981); interpretation of Quaternary sediments along lines of seismic shot hole (1976); topographic lows above domes (1977); structural significance of topographic lows above North Louisiana salt domes (1981); diagnostic microfossils - Vacherie dome (1978); and development of stratigraphy above Vacherie dome from Cretaceous to Sparta times (1982).

  10. Chasing lava: a geologist's adventures at the Hawaiian Volcano Observatory

    USGS Publications Warehouse

    Duffield, Wendell A.

    2003-01-01

    A lively account of the three years (1969-1972) spent by geologist Wendell Duffield working at the Hawaiian Volcano Observatory at Kilauea, one of the world's more active volcanoes. Abundantly illustrated in b&w and color, with line drawings and maps, as well. Volcanologists and general readers alike will enjoy author Wendell Duffield's report from Kilauea--home of Pele, the goddess of fire and volcanoes. Duffield's narrative encompasses everything from the scientific (his discovery that the movements of cooled lava on a lava lake mimic the movements of the earth's crust, providing an accessible model for understanding plate tectonics) to the humorous (his dog's discovery of a snake on the supposedly snake-free island) to the life-threatening (a colleague's plunge into molten lava). This charming account of living and working at Kilauea, one of the world's most active volcanoes, is sure to be a delight.

  11. Measurement of air quality within storage domes in technical area 54, areas G and L

    SciTech Connect

    Anderson, E.

    1994-03-15

    The concentrations of volatile organic compounds (VOCs) and tritium inside of storage domes at TA-54 were measured to assess worker exposure and support the Area G site characterization, including the Radioactive Air Emissions Management (RAEM) program. Samples were collected at 2-3 locations within Domes 48, 49, and 153 on up to six days during the summer of 1994. Samples were collected to evaluate three scenarios: (1) normal working activities with the domes open; (2) after domes were closed overnight; and (3) after domes were closed for three days. Eight-hour integrated samples were collected and analyzed in Radian`s Austin laboratories. Tritium activities from 17.1 to 69,900 pCi/m{sup 3} were measured. About two dozen individual VOCs were identified in each sample, but most of the concentration levels were very low (e.g.; < 1 to 10 ppbv). The highest concentrations measured were bromomethane (56.5 ppbv), 1, 1,1-trichloroethane (75.4 ppbv), propane (958 ppbv), methylene chloride (1,450 ppbv), and toluene (22.8). The measured VOC concentrations were well below the action levels developed by the New Mexico Environment Department and the measured tritium concentrations were well below the DOE`s derived air concentration (DAC). The variability in concentration within a dome during a single sampling episode was small. The concentrations were about an order of magnitude (i.e., 10x) higher after the domes had been closed overnight compared with the domes when open. Closing the domes over the weekend did not result in significantly higher concentrations (e.g.; > 20%) than when the domes were closed only overnight. The data were used to generate estimated annual dome emission rates of 0.3 Ci/yr of tritium and less than 100 lbs/yr of VOCs. The measured VOC concentrations were collected during the warmest months of the year and therefore should represent worst-case air impacts.

  12. Volcan de Colima, Mexico Deformation Analysys of Recent Dome Extrusion 2009-2014 Using Tilt Meter Surveys Confronted with Deformations Registered during Period 1998-2007

    NASA Astrophysics Data System (ADS)

    Ramirez-Ruiz, J. J.

    2014-12-01

    Volcán de Colima, Mexico is considered one of the most active Volcano in Mexico and it is located between the states of Colima and Jalisco in the Central West part of the Country. During the period of 2009-2014 occurred one extrusion inside the dome that was growth in 2007 originating deformations that will be analysed and compared with deformations measured before during the period of 1998-2007. Four dome extrusions have occurred during the recent activity stage from 1998-2014. During period of domes growth we show deformation of the Volcano edifice with sequences of inflation- deflation registered with a Tiltmeter net composed of 5 sensors deployed around the edifice. Measurements of deformation tilt changes during the period 2004-2014 at Volcán de Colima were characterized by a sequence of effusive-explosive episodes. These sequences occurred on October 2004, February 2007 and January 2014 were registered by sequences of inflation-deflation principally. The tiltmeter net used in this study is composed of 5 sensors installed around the volcano edifice at altitudes of 3060 masl (COIA), 3200 masl (PCJ1), 2590 masl (PC02), 2200 masl (EHJ1) and 2070 masl (PC01). The activity of Volcán de Colima during this period 1998-2014 can be summarized by the occurrence of four lava domes formed in November 1998, October 2004, February 2007, and January 2014. During this activity phase explosive sequences occurred in years 2005, 2012 and 2014. After the extrusion on February 2007 a deflation phase is registered with the tilt sensors until 2012 which explain the low activity that characterize the behavior of the volcano during these periods of time. Here we show the analysis of the activity during the 2009-2014 and compare the deformations surveys during these period with the occurred during the complete recent period of activity 1998-2014. This comparison is important to forecast the developing of the activity and help to prevent the volcanic Risk of the Population located

  13. Coastal lava flows from Mauna Loa and Hualalai volcanoes, Kona, Hawaii

    USGS Publications Warehouse

    Moore, J.G.; Clague, D.

    1987-01-01

    A major carbonate reef which drowned 13 ka is now submerged 150 m below sea level on the west coast of the island of Hawaii. A 25-km span of this reef was investigated using the submersible Makali'i. The reef occurs on the flanks of two active volcanoes, Mauna Loa and Hualalai, and the lavas from both volcanoes both underlie and overlie the submerged reef. Most of the basaltic lava flows that crossed the reef did so when the water was much shallower, and when they had to flow a shorter distance from shoreline to reef face. Lava flows on top of the reef have protected it from erosion and solution and now occur at seaward-projecting salients on the reef face. These relations suggest that the reef has retreated shoreward as much as 50 m since it formed. A 7-km-wide "shadow zone" occurs where no Hualalai lava flows cross the reef south of Kailua. These lava flows were probably diverted around a large summit cone complex. A similar "shadow zone" on the flank of Mauna Loa volcano in the Kealakekua Bay region is downslope from the present Mauna Loa caldera, which ponds Mauna Loa lava and prevents it from reaching the coastline. South of the Mauna Loa "shadow zone" the - 150 m reef has been totally covered and obscured by Mauna Loa lava. The boundary between Hualalai and Mauna Loa lava on land occurs over a 6-km-wide zone, whereas flows crossing the - 150 m reef show a sharper boundary offshore from the north side of the subaerial transition zone. This indicates that since the formation of the reef, Hualalai lava has migrated south, mantling Mauna Loa lava. More recently, Mauna Loa lava is again encroaching north on Hualalai lava. ?? 1987 Springer-Verlag.

  14. Selected caves and lava-tube systems in and near Lava Beds National Monument, California

    USGS Publications Warehouse

    Waters, Aaron Clement; Donnelly-Nolan, Julie M.; Rogers, Bruce W.

    1990-01-01

    Much of the north and south flanks of the Medicine Lake shield were built from molten lava transmitted through lava tubes. These tubes formed beneath the congealing surface of basalt flows in somewhat the same way that a brook may continue to flow beneath a cover of its own winter ice. As molten lava emerges from a vent and flows downslope, congealing lava from the top and sides of the central channel often forms a bridge over the lava stream. The sticking together of bits of lava spatter and fragile lava crusts strengthens the bridge in the manner that thin crusts of floating ice raft together to cover a brook during early stages of a winter freeze. Eruption of basalt lava, however, is a much more violent and spasmodic process than the steady gathering of water that feeds a brook. If liquid lava stops rising from its source deep within the earth, the still-molten lava moving beneath the crusted-over top of a lava flow will continue to drain downhill and may ultimately leave an open lavatube cave-often large enough for people to walk through. It is rare, however, to find such a simple scenario recorded intact among the hundreds of lava-tube caves in the monument. Even before the top and walls of a lava flow have time to cool during a pause in lava supply, a new and violent eruption of lava may refill the open tube, overflow its upper end, and spread a new lava flow beside or on top of the first flow. Even if the original tube is large enough to contain the renewed supply of lava, this tube must deliver the new lava beyond the end of its original flow and thus the lava field extends farther and farther downslope. If the gradient of flow flattens, the tube may subdivide into a number of smaller distributaries, which spread laterally over the more gently sloping ground. 

  15. LavaSIM: the effect of heat transfer in 3D on lava flow characteristics (Invited)

    NASA Astrophysics Data System (ADS)

    Fujita, E.

    2013-12-01

    Characteristics of lava flow are governed by many parameters like lava viscosity, effusion rate, ground topography, etc. The accuracy and applicability of lava flow simulation code is evaluated whether the numerical simulation can reproduce these features quantitatively, which is important from both strategic and scientific points of views. Many lava flow simulation codes are so far proposed, and they are classified into two categories, i.e., the deterministic and the probabilistic models. LavaSIM is one of the former category models, and has a disadvantage of time consuming. But LavaSIM can solves the equations of continuity, motion, energy by step and has an advantage in the calculation of three-dimensional analysis with solid-liquid two phase flow, including the heat transfer between lava, solidified crust, air, water and ground, and three-dimensional convection in liquid lava. In other word, we can check the detailed structure of lava flow by LavaSIM. Therefore, this code can produce both channeled and fan-dispersive flows. The margin of the flow is solidified by cooling and these solidified crusts control the behavior of successive lava flow. In case of a channel flow, the solidified margin supports the stable central main flow and elongates the lava flow distance. The cross section of lava flow shows that the liquid lava flows between solidified crusts. As for the lava extrusion flow rate, LavaSIM can include the time function as well as the location of the vents. In some cases, some parts of the solidified wall may be broken by the pressure of successive flow and/or re-melting. These mechanisms could characterize complex features of the observed lava flows at many volcanoes in the world. To apply LavaSIM to the benchmark tests organized by V-hub is important to improve the lava flow evaluation technique.

  16. Insights into the dynamics of the Nyiragongo lava lake level

    NASA Astrophysics Data System (ADS)

    Smets, Benoît; d'Oreye, Nicolas; Geirsson, Halldor; Kervyn, Matthieu; Kervyn, François

    2016-04-01

    Nyiragongo volcano, in North Kivu, Democratic Republic of Congo, is among the most active volcanoes in Africa and on Earth. Since the first European observations in the late 19th Century, its eruptive activity mostly concentrated into its main crater, with the presence of a persistent lava lake from at least 1928 to 1977 and since 2002. The size, shape and elevation of this lava lake have evolved through time, modifying the topography of the main crater. In January 1977 and 2002, the uppermost magmatic system of Nyiragongo, including the lava lake, was drained during flank eruptions. These flank events caused major disasters, mostly due to the exceptionally fast-moving lava flows and the presence of a dense population living at foot of this volcano. Despite a large scientific interest and societal concern, the study of the eruptive activity of Nyiragongo remains limited by climate and vegetation conditions that, most of the time, limit use of satellite remote sensing techniques, and recurrent armed conflicts in the Kivu region, which sometimes prevent field access to the main crater. Here we focus on the dynamics of the Nyiragongo lava lake level and its relationship with the volcanic plumbing system by describing the historical and recent lava lake activity and presenting new quantitative observations using close-range photogrammetry, a Stereographic Time-Lapse Camera (STLC) system and high-resolution satellite SAR and InSAR remote sensing. Results highlight that, contrary to the interpretation found in some recent publications, the lava lake drainages appear to be the consequence and not the cause of the 1977 and 2002 flank eruptions. Two types of short-term lava lake level variations are observed. The first one corresponds to cyclic metre-scale variations attributed to gas piston activity. The STLC data recorded in September 2011 show hour-scale gas piston cycles reaching up to 3.8 m, which are interpreted to be related to gas accumulation and release in the

  17. Changing patterns of seismicity and ground deformation at the end of the Mount St. Helens 2004-2008 dome-building eruption

    NASA Astrophysics Data System (ADS)

    Lisowski, M.; Moran, S. C.; Dzurisin, D.; Anderson, K. R.

    2012-12-01

    The onset and character of the 2004-2008 dome-building eruption at Mount St. Helens has been reported in detail through 2006-2007; our purpose here is to describe activity near the end of the eruption in early 2008. Overall, seismicity, deformation, and extrusion rates progressively declined throughout the eruption. As measured from SEP, the continuously-running seismic station closest to the vent, the number of detected earthquakes declined from ~1000/day during January-October 2006 to hundreds per day by September 2007 and to near zero by late October 2007. Starting in December 2007 the seismicity rate increased slightly , culminating in a short-lived episode of about 500 events on January 12-13, most of which accompanied several tremor-like signals and a spasmodic burst of LPs. At this time, distinctive sawtooth-shaped tilt events that had accompanied dome growth ceased; these had been recorded throughout the earlier part of the eruption at three locations on the 1980s lava dome adjacent to the 2004-2008 vent. Seismicity rapidly declined back to rates of 10-20 per day for the next two weeks. The "last gasp" from the seismic perspective was on January 27-28, when a spasmodic burst of ~50 VT earthquakes occurred over the space of 3 hours early on January 27. This burst followed by a brief return of drumbeat-style earthquakes that had characterized much of the 2004-2008 eruption, with hybrid-style earthquakes occurring every 35-40 minutes through the end of January 28. By the end of January, seismicity had declined to 1-2 earthquakes per day, consistent with pre-2004-eruption background levels. In conjunction with the decline in seismicity rate, depths of locatable earthquakes increased from the 0-1 km depth range seen during the eruption to 2-3 km by the end of January 2008, a depth range typical of pre-2004-eruption seismicity. Remote-camera photography confirmed the cessation of dome growth and also the subsequent subsidence of the 2004-2008 dome as a result of

  18. Volcanic tremor location during the 2004 Mount Etna lava effusion

    NASA Astrophysics Data System (ADS)

    Di Grazia, G.; Falsaperla, S.; Langer, H.

    2006-02-01

    A lava emission started at Mt. Etna, Italy, on 7 September, 2004. Neither earthquake seismicity heralded or accompanied the opening of the fracture field from which the lava poured out, nor volcanic tremor changed in amplitude and frequency content at the onset of the effusive activity. To highlight long-term changes, we propose a method for the location of the tremor source based on a 3D grid search, using the amplitude decay of the seismic signal, from January to November 2004. We find the centroid of the tremor source within a zone close to and partially overlapped with the summit craters (pre-effusive phase), which extended up to 2 km south of them (effusive phase). The depths are of between 1698 and 2387 m a.s.l. We hypothesize the lava effusion stemmed from a degassed magma body, although we find evidence of temporary magma overpressure conditions, such as those documented on 25 September.

  19. Field-based density measurements as tool to identify preeruption dome structure: set-up and first results from Unzen volcano, Japan

    NASA Astrophysics Data System (ADS)

    Kueppers, Ulrich; Scheu, Bettina; Spieler, Oliver; Dingwell, Donald B.

    2005-03-01

    For an improvement in the quality of conduit flow and dome-related explosive eruption models, knowledge of the preeruption or precollapse density of the rocks involved is necessary. As close investigation is impossible during eruption, the best substitute comes from quantitative investigation of the eruption deposits. The porosity of volcanic rocks is of primary importance for the eruptive behaviour and, accordingly, a key-parameter for realistic models of dome stability and conduit flow. Fortunately, this physical property may be accurately determined via density measurements. We developed a robust, battery-powered device for rapid and reliable density measurements of dry rock samples in the field. The density of the samples (sealed in plastic bags at 250 mbar) is determined using the Archimedean principle. We have tested the device on the deposits of the 1990-1995 eruption of Unzen volcano, Japan. Short setup and operation times allow up to 60 measurements per day under fieldwork conditions. The rapid accumulation of correspondingly large data sets has allowed us to acquire the first statistically significant data set of clast density distribution in block-and-ash flow deposits. More than 1100 samples with a total weight of 2.2 tons were measured. The data set demonstrates that the deposits of the last eruptive episode at Unzen display a bimodal density distribution, with peaks at 2.0±0.1 and 2.3±0.1 g/cm 3, corresponding to open porosity values of 20 and 8 vol.%, respectively. We use this data set to link the results of laboratory-based fragmentation experiments to field studies at recently active lava domes.

  20. Compositional gradients surrounding spherulites in obsidian and their relationship to spherulite growth and lava cooling

    NASA Astrophysics Data System (ADS)

    Gardner, James E.; Befus, Kenneth S.; Watkins, James; Hesse, Marc; Miller, Nathan

    2012-10-01

    Spherical masses of crystal fibers (spherulites) crystalize from rhyolitic melt/glass mainly in response to significant undercooling while lava cools. Spherulite growth should induce compositional gradients in the surrounding glass from expulsion of incompatible constituents and diffusion of those constituents away from the spherulite. Finite-difference numerical modeling of one-dimensional diffusion, in which diffusivities are allowed to vary with temperature, is used to investigate how compositional gradients reflect spherulite growth and lava cooling. Overall, three forms of gradients are identified. Elements that diffuse quickly are expelled from the spherulite but then migrate away too quickly to become enriched at the boundary of the spherulite. Elements that diffuse slowly are trapped within the growing spherulite. Between those endmembers are elements that are not trapped, yet diffuse slow enough that they become enriched at the contact. Their slow diffusion away then elevates their concentrations in the surrounding glass. How enriched those elements are at the spherulite-matrix interface and how far their enrichments extend outwards into the glass reflect how spherulites grow and thermal conditions during growth. Concentrations of H2O, Rb, F, Li, Cl, Na, K, Sr, Cs, Ba, and Be were measured in and around spherulites in obsidian from a 4.7 ± 1 km3 rhyolite lava dome erupted from Tequila volcano, Mexico. Measurable concentration gradients are found for H2O, Rb, and F. Attributes of those gradients and the behaviors of the other elements are in accord with their experimentally constrained diffusivities. Spherulites appear to have grown following radial, rather than volumetric, growth. The observed gradients (and lack of others) are more consistent with growth mainly below the glass transition, which would necessitate the dome cooling at ca. 10-5 to 10-7 °C s-1. Such slow cooling is consistent with the relatively large volume of the dome.

  1. A structural outline of the Yenkahe volcanic resurgent dome (Tanna Island, Vanuatu Arc, South Pacific)

    NASA Astrophysics Data System (ADS)

    Merle, O.; Brothelande, E.; Lénat, J.-F.; Bachèlery, P.; Garaébiti, E.

    2013-12-01

    A structural study has been conducted on the resurgent Yenkahe dome (5 km long by 3 km wide) located in the heart of the Siwi caldera of Tanna Island (Vanuatu arc, south Pacific). This spectacular resurgent dome hosts a small caldera and a very active strombolian cinder cone - the Yasur volcano - in the west and exhibits an intriguing graben in its central part. Detailed mapping and structural observations make it possible to unravel the volcano-tectonic history of the dome. It is shown that, following the early formation of a resurgent dome in the west, a complex collapse (caldera plus graben) occurred and this was associated with the recent uplift of the eastern part of the present dome. Eastward migration of the underlying magma related to regional tectonics is proposed to explain this evolution.

  2. Relatively rapid emplacement of dome-forming magma inferred from strain analyses: The case of the acid Latian dome complexes (Central Italy)

    NASA Astrophysics Data System (ADS)

    Cimarelli, C.; de Rita, D.

    2006-11-01

    We have analysed the relationship between the volcanic substratum and magma body emplacement for the acid dome complexes of Latium, Central Italy. Our study shows that the volcanic edifices, which are mainly Pleistocene cryptodomes and related explosive products, were derived from mantle magmas contaminated by crustal materials. The Cimini, Tolfa and Cerite-Manziate dome complexes of Latium show the following characteristics: a shallow laccolith origin; emplacement in basins that have identical tectonic evolution and geological structure; the same magmatic composition and density contrast between magma and host rock; and geochronological data that are inconsistent with field evidence. In the Cimini and Tolfa dome complexes, the deformation induced by shallow intrusions was accompanied by ˜ 200 m uplift of the sedimentary cover. The estimated pluton infilling time for the Cimini and Tolfa domes is 10 2 years while the strain rate required to uplift their Pliocene overburden by 200 m is ɛm' ˜ 10 - 9 s - 1 . The rapid evolution of the dome complexes is consistent with field data that show no relevant interruptions in the volcanic activity and no significant compositional changes in the volcanic products related to the extrusion of the domes. For the Cerite-Manziate dome complex, the minimal input rate of magma favoured a monogenetic style of volcanism, independent of the regional stress conditions.

  3. Where lava meets the sea; Kilauea Volcano, Hawaii

    USGS Publications Warehouse

    Mattox, T.N.

    1993-01-01

    Seaside explosions of the type and magnitude of the event on November 24, 1992, are infrequent. the observation of this event represents a rare opportunity to enhance our understanding of the birth of littoral cones and the nature of explosive activity when lava enters the ocean. 

  4. Volcano dome dynamics at Mount St. Helens: Deformation and intermittent subsidence monitored by seismicity and camera imagery pixel offsets

    NASA Astrophysics Data System (ADS)

    Salzer, J. T.; Thelen, W. A.; James, M. R.; Walter, T. R.; Moran, S. C.; Denlinger, R. P.

    2015-12-01

    The morphology of a volcanic lava dome and its rate of change play key roles in the estimation of dome stability. While long term variations of dome morphology can be quantified using aerial remote sensing, changes over shorter time scales and smaller spatial scales are more difficult to determine. However, intermittent destabilization of the dome, in particular on flanks of the domes, can be significant. This study focuses on short term deformation associated with earthquakes and tremor at Mount St. Helens, observed over a 6 week period in the summer of 2006. We use Digital Image Correlation (DIC) to compute the displacement field between successive optical images acquired by multiple fixed cameras with clear views of the dome. The results of the these calculations are compared to the occurrence of seismic events. A systematic time-series DIC analysis of image pairs showed no sharp changes in the dome morphology during periods without seismic events. However, the results reveal that the steady dome growth at Mount St. Helens was interrupted by short term displacements reaching magnitudes on the order of a meter. These displacements are only observed in association with low frequency, large magnitude seismic events, followed by tremor with frequencies between 5 Hz and likely exceeding 30 Hz. For selected events that coincide with the timing of the acquisition of an accurate DEM of the crater floor, we reproject the displacement fields obtained from two cameras onto the topography. This enables 3D displacement vectors to be derived, showing that the co-seismic deformation is marked by subsidence of the dome in a segmented fashion, the central region displaying mainly vertical motion, while the displacements on the talus are more slope-parallel. The exact relationship between the recorded seismic energy and the observed deformation of the dome can not be resolved because the cameras were only sampling every 15 - 60 minutes. However, our analysis suggests that the

  5. Temporal evolution of magma flow and degassing conditions during dome growth, insights from 2D numerical modeling

    NASA Astrophysics Data System (ADS)

    Chevalier, Laure; Collombet, Marielle; Pinel, Virginie

    2017-03-01

    Understanding magma degassing evolution during an eruption is essential to improving forecasting of effusive/explosive regime transitions at andesitic volcanoes. Lava domes frequently form during effusive phases, inducing a pressure increase both within the conduit and within the surrounding rocks. To quantify the influence of dome height on magma flow and degassing, we couple magma and gas flow in a 2D numerical model. The deformation induced by magma flow evolution is also quantified. From realistic initial magma flow conditions in effusive regime (Collombet, 2009), we apply increasing pressure at the conduit top as the dome grows. Since volatile solubility increases with pressure, dome growth is then associated with an increase in magma dissolved water content at a given depth, which corresponds with a decrease in magma porosity and permeability. Magma flow evolution is associated with ground deflation of a few μrad in the near field. However this signal is not detectable as it is hidden by dome subsidence (a few mrad). A Darcy flow model is used to study the impact of pressure and permeability conditions on gas flow in the conduit and surrounding rock. We show that dome permeability has almost no influence on magma degassing. However, increasing pressure in the surrounding rock, due to dome loading, as well as decreasing magma permeability in the conduit limit permeable gas loss at the conduit walls, thus causing gas pressurization in the upper conduit by a few tens of MPa. Decreasing magma permeability and increasing gas pressure increase the likelihood of magma explosivity and hazard in the case of a rapid decompression due to dome collapse.

  6. Towards a new approach for generating probabilistic hazard maps for pyroclastic flows during lava dome eruptions.

    NASA Astrophysics Data System (ADS)

    Calder, E. S.; Pitman, B.; Wolpert, R.; Bayarri, S.; Spiller, E.; Berger, J.

    2009-05-01

    It is increasingly being understood that development of mathematical models of a geophysical phenomena, while a fundamental step, is only part of the process of modeling and predicting inundation limits for natural hazards. In this work we combine data from hundreds of observed pyroclastic flows at the Soufriere Hills Volcano, Montserrat, a geophysical flow model, and statistical modeling to derive a new methodology for generating probabilistic hazard maps. The initial step consists of estimating probabilities of inundation at particular discrete points of interest (e.g. airport and Plymouth). The methodology starts with a computer model of the geophysical process, in this case the TITAN2D model that has been developed for modeling geophysical mass flows. A key input to the computer model is the probability distribution for the initial volume and direction of the flows based on observed data. An important limitation is that for modeling purposes, the observations represent relatively scarce datasets, while from a volcanological perspective datasets such as those from the prolonged and relatively well-monitored eruption of the Soufriere Hills Volcano, are as complete as can be realistically obtained. By combining flow event data, probability modeling and statistical methods, a probability distribution of severity and frequency of flow events is derived. Understanding and predicting the effects of volcanic hazards involves understanding the extreme event tail (the largest flow events) but this is notoriously difficult, especially with the limited data and prohibitively expensive to compute.. Instead a statistical emulator (or surrogate of the computer model) is used, a computationally cheap response surface approximating the output of the flow simulations, which is constructed based on carefully chosen computer model runs. The speed of the emulator then allows to 'solve the inverse problem': that is, to determine regions of inputs values (characteristics of the flow) which result in a events of interest (such as one that that reaches a given critical point). The flow frequency distribution is then used to determine the probability of this region, that is, the probability that an event of a given magnitude will occur at a particular site. Using quantitative measures like these to solve for the probabilities across an area, zoned maps could be generated from which civil protection authorities can make more informed decisions about hazard mitigation.

  7. Lava flow hazard at Nyiragongo volcano, D.R.C.. 1. Model calibration and hazard mapping

    NASA Astrophysics Data System (ADS)

    Favalli, Massimiliano; Chirico, Giuseppe D.; Papale, Paolo; Pareschi, Maria Teresa; Boschi, Enzo

    2009-05-01

    The 2002 eruption of Nyiragongo volcano constitutes the most outstanding case ever of lava flow in a big town. It also represents one of the very rare cases of direct casualties from lava flows, which had high velocities of up to tens of kilometer per hour. As in the 1977 eruption, which is the only other eccentric eruption of the volcano in more than 100 years, lava flows were emitted from several vents along a N-S system of fractures extending for more than 10 km, from which they propagated mostly towards Lake Kivu and Goma, a town of about 500,000 inhabitants. We assessed the lava flow hazard on the entire volcano and in the towns of Goma (D.R.C.) and Gisenyi (Rwanda) through numerical simulations of probable lava flow paths. Lava flow paths are computed based on the steepest descent principle, modified by stochastically perturbing the topography to take into account the capability of lava flows to override topographic obstacles, fill topographic depressions, and spread over the topography. Code calibration and the definition of the expected lava flow length and vent opening probability distributions were done based on the 1977 and 2002 eruptions. The final lava flow hazard map shows that the eastern sector of Goma devastated in 2002 represents the area of highest hazard on the flanks of the volcano. The second highest hazard sector in Goma is the area of propagation of the western lava flow in 2002. The town of Gisenyi is subject to moderate to high hazard due to its proximity to the alignment of fractures active in 1977 and 2002. In a companion paper (Chirico et al., Bull Volcanol, in this issue, 2008) we use numerical simulations to investigate the possibility of reducing lava flow hazard through the construction of protective barriers, and formulate a proposal for the future development of the town of Goma.

  8. Features of lava lake filling and draining and their implications for eruption dynamics

    USGS Publications Warehouse

    Stovall, W.K.; Houghton, B.F.; Harris, A.J.L.; Swanson, D.A.

    2009-01-01

    Lava lakes experience filling, circulation, and often drainage depending upon the style of activity and location of the vent. Features formed by these processes have proved difficult to document due to dangerous conditions during the eruption, inaccessibility, and destruction of features during lake drainage. Kilauea Iki lava lake, Kilauea, Hawai'i, preserves many such features, because lava ponded in a pre-existing crater adjacent to the vent and eventually filled to the level of, and interacted with, the vent and lava fountains. During repeated episodes, a cyclic pattern of lake filling to above vent level, followed by draining back to vent level, preserved features associated with both filling and draining. Field investigations permit us to describe the characteristic features associated with lava lakes on length scales ranging from centimeters to hundreds of meters in a fashion analogous to descriptions of lava flows. Multiple vertical rinds of lava coating the lake walls formed during filling as the lake deepened and lava solidified against vertical faces. Drainage of the lake resulted in uneven formation of roughly horizontal lava shelves on the lakeward edge of the vertical rinds; the shelves correlate with stable, staggered lake stands. Shelves either formed as broken relict slabs of lake crust that solidified in contact with the wall or by accumulation, accretion, and widening at the lake surface in a dynamic lateral flow regime. Thin, upper lava shelves reflect an initially dynamic environment, in which rapid lake lowering was replaced by slower and more staggered drainage with the formation of thicker, more laterally continuous shelves. At all lava lakes experiencing stages of filling and draining these processes may occur and result in the formation of similar sets of features. ?? Springer-Verlag 2009.

  9. Lava Flow Hazard Modeling during the 2014-2015 Fogo eruption, Cape Verde

    NASA Astrophysics Data System (ADS)

    Del Negro, C.; Cappello, A.; Ganci, G.; Calvari, S.; Perez, N. M.; Hernandez Perez, P. A.; Victoria, S. S.; Cabral, J.

    2015-12-01

    Satellite remote sensing techniques and lava flow forecasting models have been combined to allow an ensemble response during effusive crises at poorly monitored volcanoes. Here, we use the HOTSAT volcano hot spot detection system that works with satellite thermal infrared data and the MAGFLOW lava flow emplacement model that considers the way in which effusion rate changes during an eruption, to forecast lava flow hazards during the 2014-2015 Fogo eruption. In many ways this was one of the major effusive eruption crises of recent years, since the lava flows actually invaded populated areas. HOTSAT is used to promptly analyze MODIS and SEVIRI data to output hot spot location, lava thermal flux, and effusion rate estimation. We use this output to drive the MAGFLOW simulations of lava flow paths and to update continuously flow simulations. Satellite-derived TADR estimates can be obtained in real time and lava flow simulations of several days of eruption can be calculated in a few minutes, thus making such a combined approach of paramount importance to provide timely forecasts of the areas that a lava flow could possibly inundate. In addition, such forecasting scenarios can be continuously updated in response to changes in the eruptive activity as detected by satellite imagery. We also show how Landsat-8 OLI and EO-1 ALI images complement the field observations for tracking the flow front position through time, and add considerable data on lava flow advancement to validate the results of numerical simulations. Our results thus demonstrate how the combination of satellite remote sensing and lava flow modeling can be effectively used during eruptive crises to produce realistic lava flow hazard scenarios and for assisting local authorities in making decisions during a volcanic eruption.

  10. Toothpaste lava from the Barren Island volcano (Andaman Sea)

    NASA Astrophysics Data System (ADS)

    Sheth, Hetu C.; Ray, Jyotiranjan S.; Kumar, Alok; Bhutani, Rajneesh; Awasthi, Neeraj

    2011-04-01

    Toothpaste lava is a basaltic lava flow type transitional between pahoehoe and aa and has been described from Paricutin, Kilauea and Etna volcanoes. Here we describe a spectacular example of toothpaste lava, forming part of a recent (possibly 1994-95) aa flow on the active volcano of Barren Island (Andaman Sea). This flow of subalkalic basalt shows abundant squeeze-ups of viscous toothpasate lava near its entry into the sea. The squeeze-ups are sheets and slabs, up to several meters across and tens of centimeters thick, extruded from boccas. They are often prominently curved, have striated upper surfaces with close-spaced, en echelon linear ridges and grooves, broad wave-like undulations perpendicular to the striations, and sometimes, clefts. Textural, geochemical, and Sr-Nd isotopic data on the squeeze-ups and the exposed aa flow core indicate very crystal-rich, viscous, and isotopically very homogeneous lava. We envisage that a greatly reduced speed of this viscous flow at the coastline, possibly aided by a shallowing of the basal slope, led to lateral spreading of the flow, which caused tension in its upper parts. This, with continued (albeit dwindling) lava supply at the back, led to widespread tearing of the flow surface and extrusion of the squeeze-ups. The larger slabs, while extruding in a plastic condition, curved under their own weight, whereas their surfaces experienced brittle deformation, forming the en echelon grooves. The extruded, detached, and rotated sheets and slabs were carried forward for some distance atop the very slowly advancing aa core, before the flow solidified.

  11. Ascent and emplacement dynamics of obsidian lavas inferred from microlite textures

    NASA Astrophysics Data System (ADS)

    Befus, Kenneth S.; Manga, Michael; Gardner, James E.; Williams, Matthew

    2015-10-01

    To assess the eruption and emplacement of volumetrically diverse rhyolite lavas, we measured microlite number densities and orientations from samples collected from nine lavas in Yellowstone Caldera and two from Mono Craters, USA. Microlite populations are composed of Fe-Ti oxides ± alkali feldspar ± clinopyroxene. Number densities range from 108.11 ± 0.03 to 109.45 ± 0.15 cm-3 and do not correlate with distance from the vent across individual flows and are remarkably similar between large- and small-volume lavas. Together, those observations suggest that number densities are unmodified during emplacement and that ascent rates in the conduit are similar between small domes and large lava flows. Microtextures produced by continuous decompression experiments best replicate natural textures at decompression rates of 1-2 MPa hr-1. Acicular microlites have a preferred orientation in all natural samples. Because the standard deviation of microlite orientation does not become better aligned with distance travelled, we conclude that microlites exit the conduit aligned and that strain during subaerial flow was insufficient to further align microlites. The orientations of microlite trend and plunge in near-vent samples indicate that pure shear was the dominant style of deformation in the conduit. We speculate that collapsing permeable foam(s) provides a mechanism to concurrently allow microlite formation and alignment in response to the combination of degassing and flattening by pure shear.

  12. Emplacement of Long Lava Flows: Detailed Topography of the Carrizozo Basalt Lava Flow, New Mexico

    NASA Technical Reports Server (NTRS)

    Zimbelman, J. R; Johnston, A. K.

    2000-01-01

    The Carrizozo flow in south-central New Mexico was examined to obtain detailed topography for a long basaltic lava flow. This information will be helpful in evaluating emplacement models for long lava flows.

  13. Dome cities for extreme environments

    NASA Technical Reports Server (NTRS)

    Leonard, Raymond S.; Schwartz, Milton

    1992-01-01

    Extreme environments whether they be the frigid nights of the polar regions, the burning sands of the desert, or the harsh environment of space pose interesting challenges to the architect, the engineer, and the constructor in their efforts to create habitats for mankind. In space, the goals are to provide radiation protection while also providing an aesthetic living environment for long duration missions. Because of the need to provide both radiation protection and options for expansion of base facilities, a unique structural system which separates the radiation protection systems from the pressure envelope of the habitats was created. The system uses cable networks in a tensioned structural system, which supports the lunar regolith used for shielding above the facilities. The system is modular, easily expandable, and simple to construct. Additional innovations include the use of rock melting perpetrators for piles and anchoring deadmen, and various sized craters to provide side shielding. The reflective properties of the fabric used in the membrane are utilized to provide diffuse illumination. The use of craters along with the suspended shielding allows the dome to be utilized in fashions similar to those proposed by various designers unaware of the Moon's hostile radiation environment. Additional topics addressed deal with construction techniques for large domes, i.e., on the order of 100's to 1000's of meters, thermal control, the integration of tertiary water treatment schemes with architectural design, human factors, and its implications for the design of habitats for long term use in extreme environments.

  14. Utility of Lava Tubes on Other Worlds

    NASA Technical Reports Server (NTRS)

    Walden, Bryce E.; Billings, T. L.; York, Cheryl Lynn; Gillett, S. L.; Herbert, M. V.

    1998-01-01

    On Mars, as on Earth, lava tubes are found in the extensive lava fields associated with shield volcanism. Lunar lava-tube traces are located near mare-highland boundaries, giving access to a variety of minerals and other resources, including steep slopes, prominent heights for local area communications and observation, large-surface areas in shade, and abundant basalt plains suitable for landing sites, mass-drivers, surface transportation, regolith harvesting, and other uses. Methods for detecting lava tubes include visual observations of collapse trenches and skylights, ground-penetrating radar, gravimetry, magnetometry, seismography, atmospheric effects, laser, lidar, infrared, and human or robotic exploration.

  15. Characterizing Lava Flows With LiDAR

    NASA Astrophysics Data System (ADS)

    Deligne, N. I.; Cashman, K. V.; Deardorff, N.; Dietterich, H. R.; House, P. K.; Soule, S.

    2009-12-01

    Digital elevation models (DEMs) have been used in volcanology in predictive modeling of lava flow paths, both for assessment of potential hazards and specific predictions of lava flow paths. Topographic analysis of a lava flow is potentially useful for mapping and quantifying flow surface morphologies, which in turn can be used to determine flow emplacement conditions, such as effusion rate, steadiness of flow, and interactions with pre-existing topography and surface water. However, this has been limited in application because of the coarse resolution of most DEMs. In recent years, use of Light Detection and Ranging (LiDAR) airborne laser altimetry, capable of producing high resolution (≤ 1 meter) DEMs, has become increasingly common in the geomorphic and mapping community. However, volcanologists have made little use of airborne LiDAR. Here we compare information obtained using field observations and standard (10 meter) DEMs against LiDAR high resolution DEMs to assess the usefulness, capabilities, and limitations of LiDAR as applicable to lava flows. We compare morphologic characteristics of five lava flows of different compositions, tectonic settings, flow extents, slopes, and eruption duration: (1) 1984 Mauna Loa lava flow, Hawaii; (2) December 1974 Kilauea lava flow, Hawaii; (3) c. 1600 ybp Collier Cone lava flow, central Oregon Cascades; (4) Holocene lava flows from the Sand Mountain volcanic chain, central Oregon Cascades; and (5) Pleistocene lava flows along the Owyhee River, eastern Oregon basin and range. These lava flows range in composition from basalt to andesite, and have eruption durations ranging from 6 hours (observed) to years (inferred). We measure channel width, levee and flow front heights, compression ridge amplitude, wavelength and tumuli dimensions, and surface roughness. For all but the smallest scale features, LiDAR is easily used to quantify these features, which often is impossible or technically challenging to do in the field, while

  16. The explosive origin of obsidian lava (Invited)

    NASA Astrophysics Data System (ADS)

    Castro, J. M.; Bindeman, I. N.; Tuffen, H.; Schipper, C.

    2013-12-01

    melt (higher D/H) deeper in the conduit fluxed through the tuffisite veins. The D/H ratios and bulk H2O contents of bomb glasses define a continuous array that terminates in the lavas at D/H of about -145 ‰ and <0.2 wt.% H2O. This degassing trend is well fit by a mixed closed-and-open system process, whereby 'batches' of exsolved vapour are repetitively formed and rapidly extracted in explosive pulses. The episodic and frequent release of gas from fragmental magma domains in otherwise coherently rising magma is shown to be time effective and consistent with observed timelines of explosive-effusive activity at Chaitén and Cordón Caulle.

  17. Hampton Butte, a 30-Ma rhyodacite basement high bounding the subsiding Miocene to Pliocene High Lava Plains of Oregon

    NASA Astrophysics Data System (ADS)

    Iademarco, M. J.; Grunder, A.

    2012-12-01

    Hampton Butte, a 30-Ma rhyodacite basement high bounding the subsiding Miocene to Pliocene High Lava Plains Michael J. Iademarco and Anita L. Grunder The Hampton Butte area of south central Oregon lies at the boundary between major volcanic and tectonic provinces. Hampton Butte is a large rhyodacite dome complex dated at 30.39 ± 0.13 Ma and is slightly older than the 28.63 ± 0.17 Ma dacite of Cougar Butte to the immediate southeast. They extend the known distribution of vent rocks of John Day age (~35-20 Ma) and are among the oldest rocks exposed in southeastern Oregon. Excepting a remnant of a Cretaceous pluton that intrudes metasedimentary rocks of uncertain age in southeasternmost Oregon, there are no pre-Oligocene basement rocks in the northwest corner of the Basin and Range. Hampton Butte is at least 70 km east of the inferred Oligocene arc indicating that, if it was part of early Cascade volcanism, the arc was much broader than today. Hampton Butte lies at the northern margin of the High Lava Plains, which extend from behind the Cascades arc ~300 km eastward and separate the northwest corner of the Basin a Range form relatively little extended Blue Mountains region to the north. Rocks of the High Lava Plains (HLP) range from ~10 to 0 Ma and are high alumina olivine tholeiites intercalated with tuffaceous sediments and thin widespread ash-flow tuffs; the HLP is punctuated by rhyolite dome complexes that are successively younger to the west. A stack of compound flows of HLP basalt are banked on the south flank of Hampton Butte and dip about 5 degrees south, toward the HLP. These basalts have an age of 7.75 ± 0.06 Ma and correlate with a tongue of basalt with an age of 7.81 ± 0.06, which is preserved in a paleovalley cut into Hampton Butte. These basalts are part of an HLP-wide episode of ~7.5-8 Ma basalt activity. The Hampton Tuff is also banked on the south flank of Hampton Butte, like the basalts dips 5-7 degrees south. The Hampton Tuff yields an age of 3

  18. Environmental assessment: Richton Dome site, Mississippi

    SciTech Connect

    none,

    1986-05-01

    In February 1983, the US Department of Energy (DOE) identified the Richton Dome site in Mississippi as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Richton Dome site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOE prepared the final EAs. The site is in the Gulf interior region, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains two other potentially acceptable sites--the Cypress Creek Dome site in Mississippi and the Vacherie Dome site in Louisiana. Although the Cypress Creek Dome and the Vacherie Dome sites are suitable for site characterization, the DOE has concluded that the Richton Dome site is the preferred site in the Gulf interior region. On the basis of the evaluations reported in this EA, the DOE has found that the Richton Dome site is not disqualified under the guidelines.

  19. Turning Norton's Dome Against Material Induction

    NASA Astrophysics Data System (ADS)

    Dawid, Richard

    2015-09-01

    John Norton has proposed a position of "material induction" that denies the existence of a universal inductive inference schema behind scientific reasoning. In this vein, Norton has recently presented a "dome scenario" based on Newtonian physics that, in his understanding, is at variance with Bayesianism. The present note points out that a closer analysis of the dome scenario reveals incompatibilities with material inductivism itself.

  20. Environmental assessment: Richton Dome Site, Mississippi

    SciTech Connect

    none,

    1986-05-01

    In February 1983, the US Department of Energy (DOE) identified the Richton Dome site in Mississippi as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Richton Dome site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOE prepared the final EAs. The site is in the Gulf interior region, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains two other potentially acceptable sites--the Cypress Creek Dome site in Mississippi and the Vacherie Dome site in Louisiana. Although the Cypress Creek Dome and the Vacherie Dome sites are suitable for site characterization, the DOE has concluded that the Richton Dome site is the preferred site in the Gulf interior region. On the basis of the evaluations reported in this EA, the DOE has found that the Richton Dome site is not disqualified under the guidelines.

  1. Lava Lakes on Io: New Perspectives from Modeling

    NASA Technical Reports Server (NTRS)

    Gregg, Tracy K. P.; Lopes, Rosaly M.

    2004-01-01

    Ionian paterae are a class of volcanic feature that are characterized by irregular craters with steep walls, flat floors, and arcuate margins that may or may not exhibit nesting. Loki (310 W, 12 N) is Io's largest patera at approx.200 km in diameter (Figure 1), and may account for 15% of Io's total heat flow. Earth-based infrared data, as well as information collected using the Galileo Near-Infrared Mapping Spectrometer (NIMS) and the Photopolarimeter Radiometer (PPR) have been used to interpret Loki s eruption style. Debate continues over whether Loki s occasional (periodic or not) temperature increases are due to an overturning lava lake within the patera, or to an eruption of surface flows on the patera floor. Interpretation of model results and comparisons with active terrestrial lava lakes suggest that Loki behaves quite differently from active lava lakes on Earth, and that surface flows (rather than an overturning lava lake) are a more likely explanation of Loki's thermal brightening.

  2. Imaging the structural changes and instability of the Merapi dome

    NASA Astrophysics Data System (ADS)

    Darmawan, Herlan; Walter, Thomas; Nikkhoo, Mehdi; Richter, Nicole; Troll, Valentin

    2016-04-01

    Actively growing volcano domes may gradually oversteepen, which can lead to catastrophic collapse and associated block and ash flows. Here we test how the structural architecture of such instability is initiated and gradual altered by volcanic activity. After the climactic 2010 eruption, the dome at Merapi volcano has been regrown and partially destroyed again during several eruptions that occurred between 2012 and 2014. At least 6 eruptions produced 1 to 2 km high ash columns and three major fractures formed that split the dome into several segments. Here we elaborate the geometric details of these structural continuing changes. We combine three methodologies (LiDAR-, image-, and thermal-analysis) in order to investigate the dynamic structures on the Merapi dome with a so far unprecedented level of detail. Fixed cameras first identified an unstable block that appeared after the Nov 18, 2013 eruption. We then identified a gradual augmentation of the fracture dimensions, associated with eruptions on March 10, March 24 and April 10, 2014. LiDAR surveys executed before and after these eruptions show structural details of this instability, which we compare with high resolution thermal imagery. We observe that the fractures form at pre-defined anisotropies, and that they concentrate the thermal signal. These thermal concentrations may point to zones of ongoing hydro-thermal mineralization and alteration processes. We therefore hypothesize that two mechanisms of destabilization are presently at play, one associated with small sized eruptions developing structural instability, and the other with continued hydro-thermal alteration and potential weakening along these newly developed structures. Close observation is therefore required at Merapi volcano, as the formation of block and ash flows is structurally initiated long before parts of the dome finally collapse.

  3. Gravity measurements on rhyolite domes near the Krafla volcano, North Iceland

    NASA Astrophysics Data System (ADS)

    Agustsdottir, T.; Gudmundsson, M. T.; Einarsson, P.

    2008-12-01

    Krafla is a central volcano in the Northern Volcanic Zone (NVZ) of Iceland. It began forming about 200 000 years BP, has a caldera, and is transected by a N10°A trending fissure swarm. Krafla's products are mostly basaltic but rhyolite domes have formed around the caldera rims. The Krafla area is both easily accessible and one of the most studied areas in northern Iceland due to the geothermal power plant situated above the caldera's shallow magma chamber and the recent volcano-tectonic episode, the Krafla fires in 1975-1984. Silicic rocks in Iceland are generally associated with central volcanoes. Rhyolite magma can rise due to buoyancy forces as a cryptodome to the surface where it erupts. Due to its high viscosity and resistance to flow it often accumulates and forms a lava dome over the vent. Data on density and volumes are essential for meaningful modelling of the emplacement of cryptodomes and lava domes. Such data is scarce. Therefore a gravity survey was carried out in the Krafla area in the autumn of 2007 to determine the mean bulk density values of rhyolite domes and their approximate mass and volume. Profiles were measured over three formations, ranging in size from Hlíðarfjall (310 m high and 2 km long), formed 60 000 years BP, to Hrafntinnuhryggur (80 m high and 2.5 km long) formed 30 000 years BP, to Hraunbunga (125 m high and 1.8 km long) formed 10 000 years BP. Mean bulk density for each formation was obtained by the Nettleton method and the volumes were calculated. Mean bulk density and volumes obtained were, Hlidarfjall: 1600- 1800 kg/m3, 0.14 ± 0.01 km3; Hrafntinnuhryggur: 1600-1900 kg/m3, 0.021 ± 0.002 km3; Hraunbunga: 1800-1900 kg/m3, 0.040 ± 0.004 km3. The mean bulk densities from rock samples collected at the survey area are in good agreement, supporting these findings. All the formations have low density values, reflecting both low grain density and high porosity. The Nettleton profiles demonstrate that these formations are neither

  4. Raman spectroscopy of volcanic lavas and inclusions of relevance to astrobiological exploration.

    PubMed

    Jorge-Villar, Susana E; Edwards, Howell G M

    2010-07-13

    Volcanic eruptions and lava flows comprise one of the most highly stressed terrestrial environments for the survival of biological organisms; the destruction of botanical and biological colonies by molten lava, pyroclastic flows, lahars, poisonous gas emissions and the deposition of highly toxic materials from fumaroles is the normal expectation from such events. However, the role of lichens and cyanobacteria in the earlier colonization of volcanic lava outcrops has now been recognized. In this paper, we build upon earlier Raman spectroscopic studies on extremophilic colonies in old lava flows to assess the potential of finding evidence of biological colonization in more recent lava deposits that would inform, first, the new colonization of these rocks and also provide evidence for the relict presence of biological colonies that existed before the volcanism occurred and were engulfed by the lava. In this research, samples were collected from a recent expedition to the active volcano at Kilauea, Hawaii, which comprises very recent lava flows, active fumaroles and volcanic rocks that had broken through to the ocean and had engulfed a coral reef. The Raman spectra indicated that biological and geobiological signatures could be identified in the presence of geological matrices, which is encouraging for the planned exploration of Mars, where it is believed that there is evidence of an active volcanism that perhaps could have preserved traces of biological activity that once existed on the planet's surface, especially in sites near the old Martian oceans.

  5. Propagation style controls lava-snow interactions.

    PubMed

    Edwards, B R; Belousov, A; Belousova, M

    2014-12-16

    Understanding interactions between volcanic eruptions and the cryosphere (a.k.a. glaciovolcanism) is important for climate reconstructions as well as for hazard mitigation at ice-clad volcanoes. Here we present unique field observations of interactions between snowpack and advancing basaltic lava flows during the 2012-13 eruption at Tolbachik volcano, Kamchatka, Russia. Our observations show that lava-snow heat transfer is slow, and that styles of lava propagation control snowpack responses. 'A'a and sheet lava flows advance in a rolling caterpillar-track motion on top of the rigid, snowpack substrate with minor lava-snow interaction. In contrast, pahoehoe lava propagates by inflation of lobes beneath/inside the snowpack, producing rigorous lava-snow interaction via meltwater percolation down into the incandescent lava causing production of voluminous steam, rapid surface cooling and thermal shock fragmentation. The textures produced by pahoehoe-snowpack interactions are distinctive and, where observed at other sites, can be used to infer syn-eruption seasonality and climatic conditions.

  6. Sustainable Outreach: Lessons Learned from Space Update and Discovery Dome

    NASA Astrophysics Data System (ADS)

    Reiff, P. H.; Sumners, C.; Law, C. C.

    2009-12-01

    A sustainable program lives on past its initial funding cycle, and develops a network of users that ensures continued life, either by fees, advertising revenue, or by making the program more successful in later sponsored grants. Teachers like free things, so having a sponsor for products such as lithographs or CD-Roms is key to wide distribution. In 1994 we developed “Space Update®”, under the NASA “Public Use of the Internet” program. It has new editions annually, with over 40,000 distributed so far (many purchased but most free at teacher and student workshops). In 1996 we created a special edition “Space Weather®”, which includes the space weather module from Space Update plus other resources. Initially developed with funding from the IMAGE mission, it is now sponsored by Cluster and MMS. A new edition is published annually and distributed in the “Sun-Earth Day” packet; total distribution now exceeds 180,000. “Earth Update” was created in 1999 under cooperative agreement “Museums Teaching Planet Earth”. It now has a total distribution of over 20,000. Both Earth Update and Space Update were developed to be museum kiosk software, and more than 15 museums have them on display. Over 4,000 users are active in our e-Teacher network and 577 in our museum educator network. Although these can certainly be considered successful because of their longevity and user base, we have had a far more dramatic sustainable program arise in the last six years… the “Discovery Dome®”. Invented at HMNS and developed under NASA Cooperative Agreement “Immersive Earth”, this dome was the first digital portable planetarium that also showed fulldome movies with an interactive interface (first shown to the public at the Dec 2003 AGU meeting). The Discovery Dome network (tinyurl.com/DiscDome) has spun those initial 6 NASA-funded domes into over 90 installations in 22 states and 23 countries. Creating high quality content is quite expensive and so needs

  7. Radiative temperature measurements at Kupaianaha lava lake, Kilauea Volcano, Hawaii

    NASA Technical Reports Server (NTRS)

    Flynn, Luke P.; Mouginis-Mark, Peter J.; Gradie, Jonathan C.; Lucey, Paul G.

    1993-01-01

    The radiative temperature of the surface of Kupaianaha lava lake is computed using field spectroradiometer data. Observations were made during periods of active overturning. The lake surface exhibits three stages of activity. Magma fountaining and overturning events characterize stage 1, which exhibits the hottest crustal temperatures and the largest fractional hot areas. Rifting events between plates of crust mark stage 2; crustal temperatures in this stage are between 100 C and 340 C, and fractional hot areas are at least an order of magnitude smaller than those in stage 1. Stage 3 is characterized by quiescent periods when the lake is covered by a thick crust. This stage dominates the activity of the lake more than 90 percent of the time. The results of this study are relevant for satellite and airborne measurement of the thermal characteristics of active volcanoes, and indicate that the thermal output of a lava lake varies on a time scale of seconds to minutes.

  8. Radar Observations of Nearside Lunar Domes

    NASA Astrophysics Data System (ADS)

    Carter, Lynn M.; Campbell, B. A.; Hawke, B. R.; Campbell, D. B.; Nolan, M. C.; Anderson, R. F.; Wells, K. S.

    2009-09-01

    Lunar domes display a broad range of sizes, surface textures, and morphologies. Some domes are thought to have formed via extrusive volcanism originating from a central vent or rift, while others are thought to have formed through non-extrusive processes (Head and Gifford, Moon and Plan., 22, 235,1980). Recent high-resolution (80 m/pixel) S-band (12.6 cm wavelength) radar data obtained using Arecibo Observatory and the Green Bank Telescope can be used to investigate the surface properties of the different classes of lunar domes. The domes Manilus 1 and Mons Rümker (Carter et al., JGR, submitted, 2009; Campbell et al., JGR, 114, E01001, doi:10.1029/2008JE003253, 2009) have low circular polarization ratio values that may indicate the presence of pyroclastics. Other domes in the Mare Vaporum region have polarization characteristics that are similar to surrounding mare basalts (Carter et al. JGR, submitted, 2009). Our current radar data include areas with significant dome concentrations in the Mare Vaporum, Marius Hills, and Rimae Cauchy regions. We present preliminary results comparing the radar polarization properties of different dome types and discuss possible implications for their surface properties and evolution.

  9. Cooling rate and thermal structure determined from progressive magnetization of the dacite dome at Mount St. Helens, Washington

    SciTech Connect

    Dzurisin, D. ); Denlinger, R.P. ); Rosenbaum, J.G. )

    1990-03-10

    The study suggests that the dome consists of a hot, nonmagnetized core surrounded by a cool magnetized carapace and flanking talus. Temporal changes in the magnetic anomaly indicate that the magnetized carapace thickened at an average rate of 0.03 {plus minus} 0.01 m/d from 1984 to 1986. Petrographic and rock magnetic properties of dome samples indicate that the dominant process responsible for these changes is magnetization of extensively oxidized rock at progressively deeper levels within the dome as the rock cools through its blocking temperature, rather than subsequent changes in magetization caused by further oxidation. Newly extruded material cools rapidly for a short period as heat is conducted outward in response to convective heat loss from its surface. The cooling rate gradually declines for several weeks, and thereafter the material cools at a relatively constant rate by convective heat loss from its interior along fractures that propagate inward. The rate of internal convective heat loss through fractures varies with rainfall, snowmelt, and large-scale fracturing during subsequent eruptive episodes. In accordance with a model for solidification of the 1959 lava lake at Kilauea Iki, Hawaii, the authors picture the dome's magnetized carapace as being a two-phase, porous, convective zone separated from the nonmagnetized core of the dome by a thin, single-phase conductive zone. As a consequence of the heat balance between the conductive and convective zones, the blocking-temperature isotherm migrates inward at a relatively constant rate. If the dome remains inactive, the time scale for its complete magnetization is estimated to be 18-36 years, a forecast which can be refined by shallow drilling into the dome and by continuing studies of its growing magnetic anomaly.

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

    Kelut volcano, East Java, is an active volcanic complex hosting a summit crater lake that has been the source of some of Indonesia's most destructive lahars. In November 2007, an effusive eruption lasting approximately 7 months led to the formation of a 260-m-high and 400-m-wide lava dome that displaced most of the crater lake. The 2007-2008 Kelut dome comprises crystal-rich basaltic andesite with a texturally complex crystal cargo of strongly zoned and in part resorbed plagioclase (An47-94), orthopyroxene (En64-72, Fs24-32, Wo2-4), clinopyroxene (En40-48, Fs14-19, Wo34-46), Ti-magnetite (Usp16-34) and trace amounts of apatite, as well as ubiquitous glomerocrysts of varying magmatic mineral assemblages. In addition, the notable occurrence of magmatic and crustal xenoliths (meta-basalts, amphibole-bearing cumulates, and skarn-type calc-silicates and meta-volcaniclastic rocks) is a distinct feature of the dome. New petrographical, whole rock major and trace element data, mineral chemistry as well as oxygen isotope data for both whole rocks and minerals indicate a complex regime of magma-mixing, decompression-driven resorption, degassing and crystallisation and crustal assimilation within the Kelut plumbing system prior to extrusion of the dome. Detailed investigation of plagioclase textures alongside crystal size distribution analyses provide evidence for magma mixing as a major pre-eruptive process that blends multiple crystal cargoes together. Distinct magma storage zones are postulated, with a deeper zone at lower crustal levels or near the crust-mantle boundary (>15 km depth), a second zone at mid-crustal levels (~10 km depth) and several magma storage zones distributed throughout the uppermost crust (<10 km depth). Plagioclase-melt and amphibole hygrometry indicate magmatic H2O contents ranging from ~8.1 to 8.6 wt.% in the lower crustal system to ~1.5 to 3.3 wt.% in the mid to upper crust. Pyroxene and plagioclase δ18O values range from 5.4 to 6.7 ‰, and 6

  11. Paleomagnetic and 40Ar/39Ar results from the Grant intrusive breccia and coparison to the Permian Downeys Bluff Sill; evidence for Permian igneous activity at Hicks Dome, southern Illinois Basin

    USGS Publications Warehouse

    Reynolds, Richard L.; Goldhaber, Martin B.; Snee, Lawrence W.

    1997-01-01

    Igneous processes at Hicks dome, a structural upwarp at lat 37.5 degrees N., long 88.4 degrees W. in the southern part of the Illinois Basin, may have thermally affected regional basinal fluid flow and may have provided fluorine for the formation of the Illinois-Kentucky Fluorspar district. The timing of both igneous activity and mineralization is poorly known. For this reason, we have dated an intrusive breccia at Hicks dome, the Grant intrusion, using 40Ar/39Ar geochronometric and paleomagnetic methods. Concordant plateau dates, giving Permian ages, were obtained from amphibole (272.1+or-0.7 [1 sigma] Ma) and phlogopite (272.7+or-0.7 [1 sigma] Ma). After alternating-field (AF) demagnetization, specimens that contain titanomagnetite-bearing igneous rock fragments give a mean remanent direction of declination (D)=168.4 degrees; inclination (I)=-8 degrees; alpha 95=8.6 degrees; number of specimens (N)=10; this direction yields a virtual geomagnetic pole (VGP) at lat 54.8 degrees N., long 119.0 degrees E., delta p=4.4 degrees, delta m=8.7 degrees, near the late Paleozoic part of the North American apparent pole wander path. A nearly identical magnetization was found for the nearby Downeys Bluff sill (previously dated at about 275+or-24 Ma by the Rb-Sr method), in southern Illinois. Both AF and thermal demagnetization isolated shallow, southeasterly remanent directions carried by magnetite in the sill and from pyrrhotite in the baked contact of the Upper Mississippian Downeys Bluff Limestone: D=158.6 degrees; I=-11.8 degrees; alpha 95=3.8 degrees; N=15, yielding a VGP at lat 53.0 degrees N., long 128.7 degrees E., delta p=2.0 degrees, delta m=3.9 degrees. The paleomagnetic results, isotopic dates, and petrographic evidence thus favor the acquisition of thermal remanent magnetization by the Grant breccia and the Downeys Bluff sill during the Permian. The isotopic dates record rapid cooling from temperatures greater than 550 degrees C to less than 300 degrees C (the

  12. Geothermal patterns of Louisiana salt domes

    SciTech Connect

    Kumar, M.B. )

    1989-09-01

    Seven salt domes of Louisiana, in the shallow to intermediate depth ranges, were selected for the investigation of geothermal patterns associated with them. Equilibrium geotemperatures were determined from the bottom hole temperatures of wells drilled in the salt dome areas. Isothermal contour mapping was attempted for various depth levels, namely, 8,000, 9,000, 10,000, 12,000, and 14,000 ft. Limited availability of data permitted construction of isothermal contour maps on some of the depth horizons for each of the domes.

  13. Autonomous Dome for a Robotic Telescope

    NASA Astrophysics Data System (ADS)

    Kumar, A.; Sengupta, A.; Ganesh, S.

    2016-12-01

    The Physical Research Laboratory operates a 50 cm robotic observatory at Mount Abu (Rajsthan, India). This Automated Telescope for Variability Studies (ATVS) makes use of the Remote Telescope System 2 (RTS2) for autonomous operations. The observatory uses a 3.5 m dome from Sirius Observatories. We have developed electronics using Arduino electronic circuit boards with home grown logic and software to control the dome operations. We are in the process of completing the drivers to link our Arduino based dome controller with RTS2. This document is a short description of the various phases of the development and their integration to achieve the required objective.

  14. Final report on decommissioning boreholes and wellsite restoration, Gulf Coast Interior Salt Domes of Mississippi

    SciTech Connect

    Not Available

    1989-04-01

    In 1978, eight salt domes in Texas, Louisiana, and Mississippi were identified for study as potential locations for a nuclear waste repository as part of the National Waste Terminal Storage (NWTS) program. Three domes were selected in Mississippi for ``area characterization`` phase study as follows: Lampton Dome near Columbia, Cypress Creek Dome near New Augusta, and Richton Dome near Richton. The purpose of the studies was to acquire geologic and geohydrologic information from shallow and deep drilling investigations to enable selection of sites suitable for more intensive study. Eleven deep well sites were selected for multiple-well installations to acquire information on the lithologic and hydraulic properties of regional aquifers. In 1986, the Gulf Coast salt domes were eliminated from further consideration for repository development by the selection of three candidate sites in other regions of the country. In 1987, well plugging and restoration of these deferred sites became a closeout activity. The primary objectives of this activity are to plug and abandon all wells and boreholes in accordance with state regulations, restore all drilling sites to as near original condition as feasible, and convey to landowners any wells on their property that they choose to maintain. This report describes the activities undertaken to accomplish these objectives, as outlines in Activity Plan 1--2, ``Activity Plan for Well Plugging and Site Restoration of Test Hole Sites in Mississippi.``

  15. Geochemical constraints on possible subduction components in lavas of Mayon and Taal Volcanoes, Southern Luzon, Philippines

    USGS Publications Warehouse

    Castillo, P.R.; Newhall, C.G.

    2004-01-01

    Mayon is the most active volcano along the east margin of southern Luzon, Philippines. Petrographic and major element data indicate that Mayon has produced a basaltic to andesitic lava series by fractional crystallization and magma mixing. Trace element data indicate that the parental basalts came from a heterogeneous mantle source. The unmodified composition of the mantle wedge is similar to that beneath the Indian Ocean. To this mantle was added a subduction component consisting of melt from subducted pelagic sediment and aqueous fluid dehydrated from the subducted basaltic crust. Lavas from the highly active Taal Volcano on the west margin of southern Luzon are compositionally more variable than Mayon lavas. Taal lavas also originated from a mantle wedge metasomatized by aqueous fluid dehydrated from the subducted basaltic crust and melt plus fluid derived from the subducted terrigenous sediment. More sediment is involved in the generation of Taal lavas. Lead isotopes argue against crustal contamination. Some heterogeneity of the unmodified mantle wedge and differences in whether the sediment signature is transferred into the lava source through an aqueous fluid or melt phase are needed to explain the regional compositional variation of Philippine arc lavas. ?? Oxford University Press 2004; all rights reserved.

  16. Io's Volcanism: Thermo-Physical Models of Silicate Lava Compared with Observations of Thermal Emission

    NASA Technical Reports Server (NTRS)

    Davies, Ashely G.

    1996-01-01

    Analyses of thermal infrared outbursts from the jovian satellite Io indicate that at least some of these volcanic events are due to silicate lava. Analysis of the January 9, 1990 outburst indicates that this was an active eruption consisting of a large lava flow (with mass eruption rate of order 10(exp 5) cubic m/sec) and a sustained area at silicate liquidus temperatures. This is interpreted as a series of fire fountains along a rift zone. A possible alternative scenario is that of an overflowing lava lake with extensive fire fountaining. The January 9, 1990 event is unique as multispectral observations with respect to time were obtained. In this paper, a model is presented for the thermal energy lost by active and cooling silicate lava flows and lakes on Io. The model thermal emission is compared with Earth-based observations and Voyager IRIS data. The model (a) provides an explanation of the thermal anomalies on Io's surface; (b) provides constraints on flow behavior and extent and infers some flow parameters; and (c) determines flow geometry and change in flow size with time, and the temperature of each part of the flow or lava lake surface as a function of its age. Models of heat output from active lava flows or inactive but recently emplaced lava flows or overturning lava lakes alone are unable to reproduce the observations. If the January 9, 1990 event is the emplacement of a lava flow, the equivalent of 27 such events per year would yield a volume of material sufficient, if uniformly distributed, to resurface all of Io at a rate of 1 cm/year.

  17. Dynamics of the Mount Nyiragongo lava lake

    NASA Astrophysics Data System (ADS)

    Burgi, P.-Y.; Darrah, T. H.; Tedesco, D.; Eymold, W. K.

    2014-05-01

    The permanent and presently rising lava lake at Mount Nyiragongo constitutes a major potential geological hazard to the inhabitants of the Virunga volcanic region in the Democratic Republic of Congo (DRC) and Rwanda. Based on two field campaigns in June 2010 and 2011, we estimate the lava lake level from the southeastern crater rim (~400 m diameter) and lava lake area (~46,550 m2), which constrains, respectively, the lava lake volume (~9 × 106 m3) and volume flow rate needed to keep the magma in a molten state (0.6 to 3.5 m3 s-1). A bidirectional magma flow model, which includes the characterization of the conduit diameter and funnel-shaped lava lake geometry, is developed to constrain the amount of magma intruded/emplaced within the magmatic chamber and rift-related structures that extend between Mount Nyiragongo's volcanic center and the city of Goma, DRC, since Mount Nyiragongo's last eruption (17 January 2002). Besides matching field data of the lava lake level covering the period 1977 to 2002, numerical solutions of the model indicate that by 2022, 20 years after the January 2002 eruption, between 300 and 1700 × 106 m3 (0.3 to 1.7 km3) of magma could have intruded/emplaced underneath the edifice, and the lava lake volume could exceed 15 × 106 m3.

  18. Three long lava flows in north Queensland

    NASA Astrophysics Data System (ADS)

    Stephenson, P. J.; Burch-Johnston, A. T.; Stanton, D.; Whitehead, P. W.

    1998-11-01

    The Kinrara, Toomba, and Undara basaltic lava flows are from 55 to 160 km long and range in age from 13 to 190 ka. The lavas were emplaced down low gradients (0.2° to 0.4°) with volumes ranging up to 30 km3. They were not unusually hot at eruption (1130°-1160°) nor unusually fluid. Gentle topography controlled the flows, and shallow drainage lines captured them. Lava tubes operated in places, and some drained to form caves. Injection under surface crust was widespread, producing inflation features ranging from tumuli and low plateaus to extensive ridges. Sustained eruption was essential for the development of the long flows, but each is composite, with pauses between successive pulses that partially covered the earlier, longer flows. The lava structures are mainly pahoehoe but some 'a'a lavas are present. Of the three volcanoes involved, Undara is a simple low-angle lava cone with a 200-m-wide crater, Toomba is a low-angled cone with several eruption centers, and Kinrara has a deep crater with evidence of strong fountaining. Effusion rates are not known but may have been relatively low, similar to those observed in Hawaiian volcanoes. Lava tubes, most of which remained undrained, are believed to have been of major importance in flow emplacement. Given the evidence of successive flows and the time needed to develop widespread inflation, it is suggested that the two long flows over 100 km involved many decades of eruption.

  19. Field-based description of rhyolite lava flows of the Calico Hills Formation, Nevada National Security Site, Nevada

    USGS Publications Warehouse

    Sweetkind, Donald S.; Bova, Shiera C.

    2015-01-01

    In the area south of the Rainier Mesa caldera, surface and subsurface geologic data are combined to interpret the overall thickness of the Calico Hills Formation and the proportion of lava flow lithology across the study area. The formation is at least 500 meters (m) thick and contains the greatest proportion of rhyolite lava flow to the northeast of Yucca Mountain in the lower part of Fortymile Canyon. The formation thins to the south and southwest where it is between 50 and 200 m thick beneath Yucca Mountain and contains no rhyolite lavas. Geologic mapping and field-based correlation of individual lava flows allow for the interpretation of the thickness and extent of specific flows and the location of their source areas. The most extensive flows have widths from 2 to 3 kilometers (km) and lengths of at least 5–6 km. Lava flow thickness varies from 150 to 250 m above interpreted source vents to between 30 and 80 m in more distal locations. Rhyolite lavas have length-to-height ratios of 10:1 or greater and, in one instance, a length-to-width ratio of 2:1 or greater, implying a tongue-shaped geometry instead of circular domes or tabular bodies. Although geologic mapping did not identify any physical feature that could be positively identified as a vent, lava flow thickness and the size of clasts in subjacent pyroclastic deposits suggest that primary vent areas for at least some of the flows in the study area are on the east side of Fortymile Canyon, to the northeast of Yucca Mountain.

  20. Ultrathin lava layers exposed near San Luis Obispo Bay, California

    NASA Astrophysics Data System (ADS)

    Moore, James G.; Charlton, Douglas W.

    1984-09-01

    Sequences of extraordinarily thin (1 5 cm thick) lava layers, resembling individual lava flows, are interbedded with Jurassic and Cretaceous pillowed lava flows near San Luis Obispo Bay on the California coast. Such layers are formed inside submarine pillowed lava pipes or flow lobes. As the lava surface in a pillow pipe falls to a lower level owing to diminished supply entering the pipe, water enters the upper compartment through cracks in the outer crust and chills a new crust on top of the lava stream. Repeated lowerings of the lava level in the pipe create a series of discrete lava shelves, each of which represents the upper crust of the lava stream flowing within the pipe. These crusts are supported at different levels on their edges at the side of the pipe. The weight of subsequent overlying lava flows collapses the partly hollow tube, creating a stacked sequence of ultrathin lava layers progressively younger downward.

  1. Environmental assessment overview: Richton Dome site, Mississippi

    SciTech Connect

    none,

    1986-05-01

    In February 1983, the US Department of Energy (DOE) identified the Richton Dome site in Mississippi as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Richton Dome site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. The site is in the Gulf interior region, which is one of five distinct geohydrologic settings considered for the first repository. On the basis of the evaluations reported in this EA, the DOE has found that the Richton Dome site is not disqualified under the guidelines. On the basis of these findings, the DOE is nominating the Richton Dome site as one of five sites suitable for characterization. 3 figs.

  2. Geochemistry and mineralogy of the phonolite lava lake, Erebus volcano, Antarctica: 1972 2004 and comparison with older lavas

    NASA Astrophysics Data System (ADS)

    Kelly, Peter J.; Kyle, Philip R.; Dunbar, Nelia W.; Sims, Kenneth W. W.

    2008-11-01

    Mount Erebus, Antarctica, is a large (3794 m) alkaline open-conduit stratovolcano that hosts a vigorously convecting and persistently degassing lake of anorthoclase phonolite magma. The composition of the lake was investigated by analyzing glass and mineral compositions in lava bombs erupted between 1972 and 2004. Matrix glass, titanomagnetite, olivine, clinopyroxene, and fluor-apatite compositions are invariant and show that the magmatic temperature (˜ 1000°C) and oxygen fugacity (ΔlogFMQ = - 0.9) have been stable. Large temperature variations at the lake surface (~ 400-500°C) are not reflected in mineral compositions. Anorthoclase phenocrysts up to 10 cm in length feature a restricted compositional range (An 10.3-22.9Ab 62.8-68.1Or 11.4-27.2) with complex textural and compositional zoning. Anorthoclase textures and compositions indicate crystallization occurs at low degrees of effective undercooling. We propose shallow water exsolution causes crystallization and shallow convection cycles the anorthoclase crystals through many episodes of growth resulting in their exceptional size. Minor variations in eruptive activity from 1972 to 2004 are decoupled from magma compositions. The variations probably relate to changes in conduit geometry within the volcano and/or variable input of CO 2-rich volatiles into the upper-level magma chamber from deeper in the system. Eleven bulk samples of phonolite lava from the summit plateau that range in age from 0 ± 4 ka to 17 ± 8 ka were analyzed for major and trace elements. Small compositional variations are controlled by anorthoclase content. The lavas are indistinguishable from modern bulk lava bomb compositions and demonstrate that Erebus volcano has been erupting lava and tephra from the summit region with the same bulk composition for ˜ 17 ka.

  3. Topical reports on Louisiana salt domes

    SciTech Connect

    Not Available

    1983-09-01

    The Institute for Environmental Studies at Louisiana State University conducted research into the potential use of Louisiana salt domes for disposal of nuclear waste material. Topical reports generated in 1981 and 1982 related to Vacherie and Rayburn's domes are compiled and presented, which address palynological studies, tiltmeter monitoring, precise releveling, saline springs, and surface hydrology. The latter two are basically a compilation of references related to these topics. Individual reports are abstracted.

  4. Lava Eruption and Emplacement: Using Clues from Hawaii and Iceland to Probe the Lunar Past

    NASA Technical Reports Server (NTRS)

    Needham, D. H.; Hamilton, C. W.; Bleacher, J. E.; Whelley, P. L.; Young, K. E.; Scheidt, S. P.; Richardson, J. A.; Sutton, S. S.

    2017-01-01

    Investigating recent eruptions on Earth is crucial to improving understanding of relationships between eruption dynamics and final lava flow morphologies. In this study, we investigated eruptions in Holuhraun, Iceland, and Kilauea, Hawaii to gain insight into the lava dynamics near the source vent, the initiation of lava channels, and the origin of down-channel features. Insights are applied to Rima Bode on the lunar nearside to deduce the sequence of events that formed this lunar sinuous rille system.These insights are crucial to correctly interpreting whether the volcanic features associated with Rima Bode directly relate to eruption conditions at the vent and, thus, can help us understand those eruption dynamics, or, alternatively, whether the features formed as a result of more localized influences on lava flow dynamics. For example, if the lava channel developed early in the eruption and was linked to pulses in vent activity, its morphology can be analyzed to interpret the flux and duration of the eruption. Conversely, if the lava channel initiated late in the eruption as the result of a catastrophic breaching of lava that had previously pooled within the vent [e.g., 1], then the final channel morphology will not indicate eruption dynamics but rather local dynamics associated with that breach event. Distinguishing between these two scenarios is crucial for correctly interpreting the intensity and duration of volcanic history on the Moon.

  5. Submarine lavas from Mauna Kea Volcano, Hawaii: Implications for Hawaiian shield stage processes

    NASA Astrophysics Data System (ADS)

    Yang, Huai-Jen; Frey, Frederick A.; Garcia, Michael O.; Clague, David A.

    1994-08-01

    The island of Hawaii is composed of five voluminous shields but only the youngest, active and well-exposed shields of Mauna Loa and Kilauea have been studied in detail. The shield lavas forming Kohala, Hualalai, and Mauna Kea are largely covered by postshield lavas with geochemical characteristics that differ from the shield lavas. In order to determine the geochemical characteristics of the Mauna Kea shield which is adjacent to the Kilauea and Mauna Loa shields, 12 Mauna Kea shield basalts dredged from the submarine east rift were analyzed for major and trace element contents and isotopic (Sr, Nd, and Pb) ratios. The lavas are MgO-rich (11 to 20%), submarine erupted, tholeiitic basalts, but they are not representative of crystallized MgO-rich melts. Their whole rock and mineral compositions are consistent with mixing of an evolved magma, less than 7% MgO, with a magma containing abundant olivine xenocrysts, probably disaggregated from a dunitic cumulate. At a given MgO content, some of the Mauna Kea whole rocks have lower abundances of CaO and higher abundances of incompatible elements. The evolved melt component in these lavas reflects significant fractionation of plagioclase and clinopyroxene and in some cases even the late crystallizing phases orthopyroxene and Fe-Ti oxide. Although these Mauna Kea lavas are not isotopically homogenous, in general their Sr, Nd, and Pb isotopic ratios overlap with the fields for lavas from Loihi and Kilauea volcanoes.

  6. Application of Bistatic TanDEM-X Interferometry to Measure Lava Flow Volume and Lava Extrusion Rates During the 2012-13 Tolbachik, Kamchatka Fissure Eruption

    NASA Astrophysics Data System (ADS)

    Kubanek, J.; Westerhaus, M.; Heck, B.

    2015-12-01

    Aerial imaging methods are a well approved source for mapping lava flows during eruptions and can serve as a base to assess the eruption dynamics and to determine the affected area. However, clouds and smoke often hinder optical systems like the Earth Observation Advanced Land Imager (EO-1-ALI, operated by NASA) to map lava flows properly, which hence affects its reliability. Furthermore, the amount of lava that is extruded during an eruption cannot be determined from optical images - however, it can significantly contribute to assess the accompanying hazard and risk. One way to monitor active lava flows is to quantify the topographic changes over time while using up-to-date high-resolution digital elevation models (DEMs). Whereas photogrammetric methods still fail when clouds and fume obstruct the sight, innovative radar satellite missions have the potential to generate high-resolution DEMs at any time. The innovative bistatic TanDEM-X (TerraSAR-X Add-on for Digital Elevation Measurements) satellite mission enables for the first time generating high-resolution DEMs from synthetic aperture radar satellite data repeatedly with reasonable costs and high resolution. The satellite mission consists of the two nearly identical satellites TerraSAR-X and TanDEM-X that build a large synthetic aperture radar interferometer with adaptable across- and along-track baselines aiming to generate topographic information globally. In the present study, we apply the TanDEM-X data to study the lava flows that were emplaced during the 2012-13 Tolbachik, Kamchatka fissure eruption. The eruption was composed of very fluid lava flows that effused along a northeast-southwest trending fissure. We used about fifteen bistatic data pairs to generate DEMs prior to, during, and after the eruption. The differencing of the DEMs enables mapping the lava flow field at different times. This allows measuring the extruded volume and to derive the changes in lava extrusion over time.

  7. The design research of a spinel dome

    NASA Astrophysics Data System (ADS)

    Zhao, Hongwei; Hou, Tianjin; Zhu, Bin; Huang, Qiu; Gao, Zhifeng

    2011-08-01

    Based on the aerodynamic heating simulated results of a spinel middle-infrared (Mid IR) image guide missile dome flying at supersonic speed, a series of experiments are made and some methods of eliminating aero-heating effect are carried out successfully. First, a simulation experiment on the ground discarding an outside protective shell of a spinel dome is accomplished in order to inspect the withstanding impact ability of the dome. Second, an arc wind tunnel experiment is fulfilled to obtain thermal mechanics characteristic of the spinel dome, and a method to buildup obviously mechanics intensity is approved which is coating diamond protective layer on the external wall of the spinel dome. Third, two heated dome imaging experiments on the ground are made to study the aero-optical phenomenon. Finally, a rocket sled experiment of a guide missile head is made successfully. Experimental results show that when the guide missile head flies in a supersonic, by adjusting the frame integration time of detector etc. the aero-optic effect would decrease greatly.

  8. Optical Measurements On Advanced Performance Domes

    NASA Astrophysics Data System (ADS)

    Archibald, P. C.; Burge, D. K.

    1984-12-01

    Sapphire, spinel, and ALON (aluminum oxynitride) have been identified as candidate dome materials for ultraviolet through 5 μm wavelength applications. They possess optical, mechanical, and thermal properties that are superior to those of currently used Irtran-1 domes. Optical performance of these materials in the visible wavelength region far exceeds that of Irtran-1, while infrared properties reported here vary from worse than to better than Irtran-1 domes. Reported in this paper are measurements of optical scatter and transmittance at 0.4762, 0.6471, and 3.39 μm, which represent a large range of values obtained on these materials in dome form. Processing changes over the last few years have produced improvements in both scatter and transmittance, provided that a good surface finish is maintained. Higher index of refraction will, of course, limit the ultimate transmittance for uncoated domes of these materials to slightly less than that of Irtran-1, which has also improved in the same time period. Calculations indicate maximum transmittance at 3.39 pm to be 0.95 to 0.96 for Irtran-1 and 0.87 to 0.88 for spinel, a difference of 0.08. Current measurements at the Naval Weapons Center confirm values of 0.88 for spinel, while the best Irtran-1 dome gave a value of less than 0.92.

  9. Mysterious Lava Mineral on Mars

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This graph or spectrum captured by the Moessbauer spectrometer onboard the Mars Exploration Rover Spirit shows the presence of three different iron-bearing minerals in the soil at the rover's landing site. One of these minerals has been identified as olivine, a shiny green rock commonly found in lava on Earth. The other two have yet to be pinned down. Scientists were puzzled by the discovery of olivine because it implies the soil consists at least partially of ground up rocks that have not been weathered or chemically altered. The black line in this graph represents the original data; the three colored regions denote individual minerals and add up to equal the black line.

    The Moessbauer spectrometer uses two pieces of radioactive cobalt-57, each about the size of pencil erasers, to determine with a high degree of accuracy the composition and abundance of iron-bearing minerals in martian rocks and soil. It is located on the rover's instrument deployment device, or 'arm.'

  10. Lava lake level as a gauge of magma reservoir pressure and eruptive hazard

    USGS Publications Warehouse

    Patrick, Matthew R.; Anderson, Kyle R.; Poland, Michael P.; Orr, Tim R.; Swanson, Donald A.

    2015-01-01

    Forecasting volcanic activity relies fundamentally on tracking magma pressure through the use of proxies, such as ground surface deformation and earthquake rates. Lava lakes at open-vent basaltic volcanoes provide a window into the uppermost magma system for gauging reservoir pressure changes more directly. At Kīlauea Volcano (Hawaiʻi, USA) the surface height of the summit lava lake in Halemaʻumaʻu Crater fluctuates with surface deformation over short (hours to days) and long (weeks to months) time scales. This correlation implies that the lake behaves as a simple piezometer of the subsurface magma reservoir. Changes in lava level and summit deformation scale with (and shortly precede) changes in eruption rate from Kīlauea's East Rift Zone, indicating that summit lava level can be used for short-term forecasting of rift zone activity and associated hazards at Kīlauea.

  11. Lunar lava tube radiation safety analysis

    NASA Technical Reports Server (NTRS)

    De Angelis, Giovanni; Wilson, J. W.; Clowdsley, M. S.; Nealy, J. E.; Humes, D. H.; Clem, J. M.

    2002-01-01

    For many years it has been suggested that lava tubes on the Moon could provide an ideal location for a manned lunar base, by providing shelter from various natural hazards, such as cosmic radiation, meteorites, micrometeoroids, and impact crater ejecta, and also providing a natural environmental control, with a nearly constant temperature, unlike that of the lunar surface showing extreme variation in its diurnal cycle. An analysis of radiation safety issues on lunar lava tubes has been performed by considering radiation from galactic cosmic rays (GCR) and Solar Particle Events (SPE) interacting with the lunar surface, modeled as a regolith layer and rock. The chemical composition has been chosen as typical of the lunar regions where the largest number of lava tube candidates are found. Particles have been transported all through the regolith and the rock, and received particles flux and doses have been calculated. The radiation safety of lunar lava tubes environments has been demonstrated.

  12. Taylor instability in rhyolite lava flows

    NASA Technical Reports Server (NTRS)

    Baum, B. A.; Krantz, W. B.; Fink, J. H.; Dickinson, R. E.

    1989-01-01

    A refined Taylor instability model is developed to describe the surface morphology of rhyolite lava flows. The effect of the downslope flow of the lava on the structures resulting from the Taylor instability mechanism is considered. Squire's (1933) transformation is developed for this flow in order to extend the results to three-dimensional modes. This permits assessing why ridges thought to arise from the Taylor instability mechanism are preferentially oriented transverse to the direction of lava flow. Measured diapir and ridge spacings for the Little and Big Glass Mountain rhyolite flows in northern California are used in conjunction with the model in order to explore the implications of the Taylor instability for flow emplacement. The model suggests additional lava flow features that can be measured in order to test whether the Taylor instability mechanism has influenced the flows surface morphology.

  13. Lunar lava tube radiation safety analysis.

    PubMed

    De Angelis, Giovanni; Wilson, J W; Clowdsley, M S; Nealy, J E; Humes, D H; Clem, J M

    2002-12-01

    For many years it has been suggested that lava tubes on the Moon could provide an ideal location for a manned lunar base, by providing shelter from various natural hazards, such as cosmic radiation, meteorites, micrometeoroids, and impact crater ejecta, and also providing a natural environmental control, with a nearly constant temperature, unlike that of the lunar surface showing extreme variation in its diurnal cycle. An analysis of radiation safety issues on lunar lava tubes has been performed by considering radiation from galactic cosmic rays (GCR) and Solar Particle Events (SPE) interacting with the lunar surface, modeled as a regolith layer and rock. The chemical composition has been chosen as typical of the lunar regions where the largest number of lava tube candidates are found. Particles have been transported all through the regolith and the rock, and received particles flux and doses have been calculated. The radiation safety of lunar lava tubes environments has been demonstrated.

  14. Long-Period and Very-Long-Period Seismicity Associated with Lava Extrusions and Volcanic Degassing at Popocatepetl Volcano, Mexico

    NASA Astrophysics Data System (ADS)

    Arciniega, A.; Chouet, B.; Dawson, P.; Asch, G.; Dietel, C.

    2003-12-01

    From November 1999 through July 2000 a broadband seismic experiment was carried out at Popocatepetl Volcano as part of an international cooperative program between the GeoForschungsZentrum in Potsdam, Germany, the U.S. Geological Survey, and the Institute of Geophysics at UNAM, Mexico. The goal of this experiment was to record seismic activity at Popocatepetl over a wide period range (0.04 to 100 s). The network deployed included 15 stations distributed along radial profiles on the upper flanks of Popocatepetl, and 7 stations at lower elevations on the volcano's western flank. All significant vulcanian events were well recorded by our network. Volcanic activity during the experiment was characterized by emissions of gas and ash, and by the formation of a lava dome within the summit crater. Ash emissions ranged from small short-lived plumes rising a few hundred meters above the crater rim, to larger plumes reaching up to 5 km above the crater. Resulting tephra falls dusted the entire summit area. Bursts of volcanic degassing were accompanied by long-period (LP) seismic signals observed as isolated events, or as sequences of discrete events with overall durations comparable to those of visible activity documented by video. Some gas emissions were accompanied by persistent or spasmodic tremor. LP events and tremor episodes increased in frequency and intensity in early February 2000. Individual LP signals, tremor, and swarms of hybrid events were frequently observed during intervals of active dome growth. Very-long-period (VLP) signals accompanying degassing activity were also clearly recorded at stations closest to the crater. The VLP signals exhibit quasi-identical pulse shapes with periods near 25 s from event to event. VLP signals with periods near 30 s and VLP tremor with periods in the range 15-22 s, lasting 20 min or more, clearly correlated with vulcanian processes. Preliminary locations of LP events based on phase picks, and particle-motion analyses of VLP

  15. Determination of eruption temperature of Io's lavas using lava tube skylights

    NASA Astrophysics Data System (ADS)

    Davies, Ashley Gerard; Keszthelyi, Laszlo P.; McEwen, Alfred S.

    2016-11-01

    Determining the eruption temperature of Io's dominant silicate lavas would constrain Io's present interior state and composition. We have examined how eruption temperature can be estimated at lava tube skylights through synthesis of thermal emission from the incandescent lava flowing within the lava tube. Lava tube skylights should be present along Io's long-lived lava flow fields, and are attractive targets because of their temporal stability and the narrow range of near-eruption temperatures revealed through them. We conclude that these skylights are suitable and desirable targets (perhaps the very best targets) for the purposes of constraining eruption temperature, with a 0.9:0.7-μm radiant flux ratio ≤6.3 being diagnostic of ultramafic lava temperatures. Because the target skylights may be small - perhaps only a few m or 10 s of m across - such observations will require a future Io-dedicated mission that will obtain high spatial resolution (< 100 m/pixel), unsaturated observations of Io's surface at multiple wavelengths in the visible and near-infrared, ideally at night. In contrast to observations of lava fountains or roiling lava lakes, where accurate determination of surface temperature distribution requires simultaneous or near-simultaneous (< 0.1 s) observations at different wavelengths, skylight thermal emission data are superior for the purposes of temperature derivation, as emission is stable on much longer time scales (minutes, or longer), so long as viewing geometry does not greatly change during that time.

  16. The structural stability of lunar lava tubes

    NASA Astrophysics Data System (ADS)

    Blair, David M.; Chappaz, Loic; Sood, Rohan; Milbury, Colleen; Bobet, Antonio; Melosh, H. Jay; Howell, Kathleen C.; Freed, Andrew M.

    2017-01-01

    Mounting evidence from the SELENE, LRO, and GRAIL spacecraft suggests the presence of vacant lava tubes under the surface of the Moon. GRAIL evidence, in particular, suggests that some may be more than a kilometer in width. Such large sublunarean structures would be of great benefit to future human exploration of the Moon, providing shelter from the harsh environment at the surface-but could empty lava tubes of this size be stable under lunar conditions? And what is the largest size at which they could remain structurally sound? We address these questions by creating elasto-plastic finite element models of lava tubes using the Abaqus modeling software and examining where there is local material failure in the tube's roof. We assess the strength of the rock body using the Geological Strength Index method with values appropriate to the Moon, assign it a basaltic density derived from a modern re-analysis of lunar samples, and assume a 3:1 width-to-height ratio for the lava tube. Our results show that the stability of a lava tube depends on its width, its roof thickness, and whether the rock comprising the structure begins in a lithostatic or Poisson stress state. With a roof 2 m thick, lava tubes a kilometer or more in width can remain stable, supporting inferences from GRAIL observations. The theoretical maximum size of a lunar lava tube depends on a variety of factors, but given sufficient burial depth (500 m) and an initial lithostatic stress state, our results show that lava tubes up to 5 km wide may be able to remain structurally stable.

  17. Sustaining persistent lava lakes: Observations from high-resolution gas measurements at Villarrica volcano, Chile

    NASA Astrophysics Data System (ADS)

    Moussallam, Yves; Bani, Philipson; Curtis, Aaron; Barnie, Talfan; Moussallam, Manuel; Peters, Nial; Schipper, C. Ian; Aiuppa, Alessandro; Giudice, Gaetano; Amigo, Álvaro; Velasquez, Gabriela; Cardona, Carlos

    2016-11-01

    Active lava lakes - as the exposed upper part of magmatic columns - are prime locations to investigate the conduit flow processes operating at active, degassing volcanoes. Persistent lava lakes require a constant influx of heat to sustain a molten state at the Earth's surface. Several mechanisms have been proposed to explain how such heat transfer can operate efficiently. These models make contrasting predictions with respect to the flow dynamics in volcanic conduits and should result in dissimilar volatile emissions at the surface. Here we look at high-frequency SO2 fluxes, plume composition, thermal emissions and aerial video footage from the Villarrica lava lake in order to determine the mechanism sustaining its activity. We found that while fluctuations are apparent in all datasets, none shows a stable periodic behaviour. These observations suggest a continuous influx of volatiles and magma to the Villarrica lava lake. We suggest that ascending volatile-rich and descending degassed magmas are efficiently mixed within the volcanic conduit, resulting in no clear periodic oscillations in the plume composition and flux. We compare our findings to those of other lava lakes where equivalent gas emission time-series have been acquired, and suggest that gas flux, magma viscosity and conduit geometry are key parameters determining which flow mechanism operates in a given volcanic conduit. The range of conduit flow regimes inferred from the few studied lava lakes gives a glimpse of the potentially wide spectrum of conduit flow dynamics operating at active volcanoes.

  18. Lava effusion rate definition and measurement--A review

    USGS Publications Warehouse

    Calvari, Sonia; Dehn, Jonathan; Harris, A.

    2007-01-01

    Measurement of effusion rate is a primary objective for studies that model lava flow and magma system dynamics, as well as for monitoring efforts during on-going eruptions. However, its exact definition remains a source of confusion, and problems occur when comparing volume flux values that are averaged over different time periods or spatial scales, or measured using different approaches. Thus our aims are to: (1) define effusion rate terminology; and (2) assess the various measurement methods and their results. We first distinguish between instantaneous effusion rate, and time-averaged discharge rate. Eruption rate is next defined as the total volume of lava emplaced since the beginning of the eruption divided by the time since the eruption began. The ultimate extension of this is mean output rate, this being the final volume of erupted lava divided by total eruption duration. Whether these values are total values, i.e. the flux feeding all flow units across the entire flow field, or local, i.e. the flux feeding a single active unit within a flow field across which many units are active, also needs to be specified. No approach is without its problems, and all can have large error (up to ∼50%). However, good agreement between diverse approaches shows that reliable estimates can be made if each approach is applied carefully and takes into account the caveats we detail here. There are three important factors to consider and state when measuring, giving or using an effusion rate. First, the time-period over which the value was averaged; second, whether the measurement applies to the entire active flow field, or a single lava flow within that field; and third, the measurement technique and its accompanying assumptions.

  19. Dome, Sweet Dome--Geodesic Structures Teach Math, Science, and Technology Principles

    ERIC Educational Resources Information Center

    Shackelford, Ray; Fitzgerald, Michael

    2007-01-01

    Today, geodesic domes are found on playgrounds, homes, over radar installations, storage facilities, at Disney's Epcot Center, and at World's Fairs. The inventor of the design, Buckminster Fuller, thought that geodesic domes could be used to cover large areas and even designed one to cover all of New York's Manhattan Island. This article details…

  20. Non-explosive lava-water interaction in Skaelingar, Iceland and the formation of subaerial lava pillars

    NASA Astrophysics Data System (ADS)

    Gregg, Tracy K. P.; Christle, Kenneth W.

    2013-08-01

    Hollow cylinders of basalt < 2.5 m tall and generally < 1 m in diameter were generated by non-explosive lava-water interactions during the emplacement of the Laki lava flow in Iceland during 1783-1784. We know of only one location within the Laki lava flow where these basalt formations occur: a valley called Skaelingar, located at ~ 64.0°N, 18.5°W, which contains a tributary stream to the Skafta River. Skaelingar was temporarily filled with Laki lava when the main body of the lava flow advancing down the Skafta River valley became blocked, forcing lava to flow upstream into tributary valleys along the north side of the river. After the blockage within the Skafta River valley was removed, the Laki lava mostly drained out of these tributary valleys. We refer to the remaining vertical hollow basalt pipes as lava pillars because they morphologically resemble subaerial lava trees and submarine lava pillars that have been observed at mid-ocean ridges. We propose that the subaerial pillars formed as an inflating lava flow advanced slowly over water-saturated ground, or perhaps into temporarily ponded water, causing heated columns of water to rise between adjacent advancing lava lobes. The subaerial pillars continued to grow in height and diameter as the lava flow inflated. When the lava drained back out of the valley, the lava pillars were left standing. Thus, the Icelandic subaerial pillars represent a non-explosive interaction between lava and water.

  1. Multi-scale heterogeneity in rhyolitic lava at Hrafntinnuhryggur, Krafla, Iceland

    NASA Astrophysics Data System (ADS)

    Tuffen, Hugh; Castro, Jonathan M.; Woodroffe, Nicola; Hounslow, Mark W.

    2010-05-01

    Small-volume rhyolitic lava flows and domes erupted through thin ice at Hrafntinnuhryggur, Krafla, Iceland[1] display remarkable textural heterogeneity over a range of spatial scales from microns to metres. As textures in the exposed feeder dyke are uniform and the aphyric magma was originally compositionally homogeneous, this heterogeneity must have emerged through strong spatial variations in deformation, vesiculation and crystallization within the lava bodies themselves. Metre-scale textural zonations occur between the margin and the interior of lava bodies. Spherulitic lava interiors are enveloped by concentric zones of lithophysae-rich obsidian, coarsely-vesicular obsidian in various stages of collapse and flow-banded, faulted obsidian[1]. These zonations reflect divergent pathways of lava evolution at different background cooling rates, which allow differing extents of late-stage crystallization and secondary vesiculation. The liberation of latent heat during spherulite crystallization[2] is an example of a feedback that can magnify the resultant textural diversity, as heat release can trigger both accelerated crystallization and vesiculation of the lava. Striking textural heterogeneities also occur on much smaller spatial scales within the lava. The flow-banded obsidian displays a broad spectrum of colours on a millimetre scale and different-coloured bands have distinct magnetic properties. This indicates that contrasting populations of sub-micron magnetite, haematite and clinoferrosilite grains are present in adjacent flow bands. Some flow bands contain remnants of now-collapsed vesicles, indicating that heterogeneous degassing may have led to highly-localised melt dehydration, redox conditions and resultant crystal nucleation. Strain localization is another feedback that can play a major role in emphasizing differences between neighbouring flow bands. Two other types of textural heterogeneity occur on still-smaller spatial scales. Firstly, individual

  2. Real-time satellite monitoring of Nornahraun lava flow NE Iceland

    NASA Astrophysics Data System (ADS)

    Jónsdóttir, Ingibjörg; Þórðarson, Þorvaldur; Höskuldsson, Ármann; Davis, Ashley; Schneider, David; Wright, Robert; Kestay, Laszlo; Hamilton, Christopher; Harris, Andrew; Coppola, Diego; Tumi Guðmundsson, Magnús; Durig, Tobias; Pedersen, Gro; Drouin, Vincent; Höskuldsson, Friðrik; Símonarson, Hreggviður; Örn Arnarson, Gunnar; Örn Einarsson, Magnús; Riishuus, Morten

    2015-04-01

    An effusive eruption started in Holuhraun, NE Iceland, on 31 August 2014, producing the Nornahraun lava flow field which had, by the beginning of 2015, covered over 83 km2. Throughout this event, various satellite images have been analyzed to monitor the development, active areas and map the lava extent in close collaboration with the field group, which involved regular exchange of direct observations and satellite based data for ground truthing and suggesting possible sites for lava sampling. From the beginning, satellite images in low geometric but high temporal resolution (NOAA AVHRR, MODIS) were used to monitor main regions of activity and position new vents to within 1km accuracy. As they became available, multispectral images in higher resolution (LANDSAT 8, LANDSAT 7, ASTER, EO-1 ALI) were used to map the lava channels, study lava structures and classify regions of varying activity. Hyper spectral sensors (EO-1 HYPERION), though with limited area coverage, have given a good indication of vent and lava temperature and effusion rates. All available radar imagery (SENTINEL-1, RADARSAT, COSMO SKYMED, TERRASAR X) have been used for studying lava extent, landscape and roughness. The Icelandic Coast Guard has, on a number of occasions, provided high resolution radar and thermal images from reconnaissance flights. These data sources compliment each other well and have improved analysis of events. Whilst classical TIR channels were utilized to map the temperature history of the lava, SWIR and NIR channels caught regions of highest temperature, allowing an estimate of the most active lava channels and even indicating potential changes in channel structure. Combining thermal images and radar images took this prediction a step further, improving interpretation of both image types and studying the difference between open and closed lava channels. Efforts are underway of comparing different methods of estimating magma discharge and improving the process for use in real

  3. Scientists Engage With the Public During Lava Flow Threat

    NASA Astrophysics Data System (ADS)

    McCarter, Tricia

    2014-11-01

    On 27 June, lava from Kīlauea, an active volcano on the island of Hawai`i, began flowing to the northeast, threatening the residents in Pāhoa, a community in the District of Puna, as well as the only highway accessible to this area. Scientists from the U.S. Geological Survey's Hawaiian Volcano Observatory (HVO) and the Hawai`i County Civil Defense have been monitoring the volcano's lava flow and communicating with affected residents through public meetings since 24 August. Eos recently spoke with Michael Poland, a geophysicist at HVO and a member of the Eos Editorial Advisory Board, to discuss how he and his colleagues communicated this threat to the public.

  4. Lava Flows On Ascraeus Mons Volcano

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Ascraeus Mons Volcano: Like Earth, Mars has many volcanoes and volcanic features. This high-resolution view shows some of the lava flows near the summit of Ascraeus Mons, one of the three giant shield volcanoes known as the 'Tharsis Montes'. Volcanoes form when magma (molten rock) erupts out onto the surface of a planet. Based on Viking-era observations, Ascraeus Mons is considered to be one of the tallest volcanoes on Mars... its summit is more than 11 km (6.8 miles) above the surrounding plain. The summit is more than 23 km (14 miles) higher in elevation than the place where Mars Pathfinder landed in July 1997.

    Description of MOC Image: This picture shows an area that is about 20 km (12 miles) higher in elevation than the Mars Pathfinder landing site. The picture shows three main features: (1) a crater at the center-right, (2) a sinuous, discontinuous channel across the upper half, and (3) a rough and pitted, elevated surface across the lower half of the image.

    (1) Crater at center right. Distinguishing meteor craters from volcanic craters can sometimes be a challenge on Mars. This particular crater was most likely formed by meteor impact because it has a raised rim and a faint radial ejecta pattern around the outside of it. This crater is 600 m (2000 feet) across, about 3/4 the size of the famous 'Meteor Crater' near Winslow, Arizona.

    (2) Sinuous channel. The type of discontinuous channel running across the upper half of the image is sometimes referred to as a 'sinuous rille'. These are common on the volcanic plains of the Moon and among volcanoes and volcanic plains on Earth. Such a channel was once a lava tube. It is running down the middle of an old lava flow. The 'tube' looks like a 'channel' because its roof has collapsed. The discontinuous nature of this channel is the result of the collapse, or 'cave-in' of what was once the roof of the lava tube. It is common for certain types of relatively fluid lavas to form

  5. Diversion of lava flows by aerial bombing — lessons from Mauna Loa volcano, Hawaii

    NASA Astrophysics Data System (ADS)

    Lockwood, J. P.; Torgerson, F. A.

    1980-12-01

    Lava flows from Mauna Loa volcano can travel the long distances from source vents to populated areas of east Hawaii only if heat-insulating supply conduits (lava channels and/or lava tubes) are constructed and maintained, so as to channelize the flow and prevent heat loss during transport. Lava is commonly directed into such conduits by horseshoe-or lyre-shaped spatter cones-loose accumulations of partially welded scoria formed around principal vents during periods of high fountaining. These conduit systems commonly develop fragile areas amenable to artificial disruption by explosives during typical eruptions. If these conduits can be broken or blocked, lava supply to the threatening flow fronts will be cut off or reduced. Explosives were first suggested as a means to divert lava flows threatening Hilo, Hawaii during the eruption of 1881. They were first used in 1935, without significant success, when the Army Air Force bombed an active pahoehoe channel and tube system on Mauna Loa’s north flank. Channel walls of a Mauna Loa flow were also bombed in 1942, but again there were no significant effects. The locations of the 1935 and 1942 bomb impact areas were determined and are shown for the first time, and the bombing effects are documented. Three days after the 1942 bombing the spatter cone surrounding the principal vent partially collapsed by natural processes, and caused the main flow advancing on Hilo to cease movement. This suggested that spatter cones might be a suitable target for future lava diversion attempts. Because ordnance, tactics, and aircraft delivery systems have changed dramatically since 1942, the U.S. Air Force conducted extensive testing of large aerial bombs (to 900 kg) on prehistoric Mauna Loa lavas in 1975 and 1976, to evaluate applicability of the new systems to lava diversion. Thirty-six bombs were dropped on lava tubes, channels, and a spatter cone in the tests, and it was verified that spatter cones are especially fragile. Bomb crater

  6. Coupled pulsing of lava fountains: Video monitoring reveals systematic height and velocity variations of adjacent vents

    NASA Astrophysics Data System (ADS)

    Witt, Tanja; Walter, Thomas R.

    2014-05-01

    Lava fountains are a common eruption form at basaltic volcanoes. Many of the lava fountains occur at fissure eruptions, associated with the alignment of active vents. We observed that the lava fountain pulses may occur in chorus at several adjacent vents, implying that activity at these vents is coupled. The mechanisms behind such a coupling of adjacent lava fountains and the underlying connection between the different craters are not fully understood, however. Here we employ video images to measure the height, width and velocity of the ejecta leaving the vent. With a Sobel edge-detection algorithm, our aim is to measure the height of the different fountains occurring along fissure eruptions. Video data acquired from Puu'oo (Hawaii) and from Eyjafjallajökull (Iceland) are showing major similarities in fountaining behavior. Based on the fountain activity times series we estimate the sign and degree of correlation of the different vents. We find that the height and velocity of adjacent lava fountains are often in chorus. The velocity is calculated by a correlation in the Fourier space of contiguous images. We observed that episodically and sporadically the correlation regime can change. Despite these changes, both the frequency of the lava pulses and the eruption and rest time between the pulses remain similar for adjacent lava fountains, implying, a controlling process in the magma feeder system itself. We interpret the initial vertical velocity at the vent to be proportional to the extent of bubbles, and layers of bubbles rising. Lateral migration of fountains and their dynamics, in turn, is associated to lateral magma and gas flow or inclined layers of bubbles developing along the fissure at depth. Systematic recording and analysis of video data from different volcanoes hence result in a better understanding of the mechanisms of parallel and non-parallel lava fountain pulses.

  7. Radially fractured domes: A comparison of Venus and the Earth

    NASA Technical Reports Server (NTRS)

    Janes, Daniel M.; Squyres, Steven W.

    1993-01-01

    Radially fractured domes are large, tectonic and topographic features discovered on the surface of Venus by the Magellan spacecraft. They are thought to be due to uplift over mantle diapirism, and to date are known to occur only on Venus. Since Venus and the Earth are grossly similar in size, composition and structure, we seek to understand why these features have not been seen on the Earth. We model the uplift and fracturing over a mantle diapir as functions of lithospheric thickness and diapir size and depth. We find that lithospheres of the same thickness on the Earth and Venus should respond similarly to the same sized diapir, and that radially fractured domes should form most readily in thin oceanic lithospheres on Earth if diapiric activity is similar on the two planets. However, our current knowledge of the Earth's oceanic floors is insufficient to confirm or deny the presence of radially fractured domes. We compute the expected dimensions for these features on the Earth and suggest a search for them to determine whether mantle diapirism operates similarly on the Earth and Venus.

  8. A magma reservoir prior to a Yellowstone supereruption: Constraints from the Mount Jackson Rhyolite and the Island Park dome series (Wyoming, USA)

    NASA Astrophysics Data System (ADS)

    Troch, Juliana; Ellis, Ben S.; Guillong, Marcel; Mark, Darren F.; Bindeman, Ilya N.; Bachmann, Olivier

    2014-05-01

    The Yellowstone volcanic field is one of the largest and best-studied centers of rhyolitic volcanism on Earth. The Mount Jackson rhyolite (MJR) and the Island Park dome (IPD) series represent a less extensively studied collection of rhyolitic lavas which were erupted in the 600,000 years following the second caldera-forming eruption of Yellowstone, the 280 km3 Mesa Falls Tuff (MFT, ~1.29 Ma). We present here an approach of detailed major and trace element compositional analyses of bulk and mineral chemistry coupled with high-resolution 40Ar/39Ar-dating to examine the evolution within the magmatic system that culminated in Yellowstone's last 'super' eruption, the 1,000 km3 Lava Creek Tuff (~0.64 Ma). The studied lavas are high-silica rhyolites and contain sanidine (~15o), quartz (~10o) and minor plagioclase, plus variable amounts of mafic minerals (

  9. Topographic and Stochastic Influences on Pahoehoe Lava Lobe Emplacement

    NASA Technical Reports Server (NTRS)

    Hamilton, Christopher W.; Glaze, Lori S.; James, Mike R.; Baloga, Stephen M.

    2013-01-01

    A detailed understanding of pahoehoe emplacement is necessary for developing accurate models of flow field development, assessing hazards, and interpreting the significance of lava morphology on Earth and other planetary surfaces. Active pahoehoe lobes on Kilauea Volcano, Hawaii, were examined on 21-26 February 2006 using oblique time-series stereo-photogrammetry and differential global positioning system (DGPS) measurements. During this time, the local discharge rate for peripheral lava lobes was generally constant at 0.0061 +/- 0.0019 m3/s, but the areal coverage rate of the lobes exhibited a periodic increase every 4.13 +/- 0.64 minutes. This periodicity is attributed to the time required for the pressure within the liquid lava core to exceed the cooling induced strength of its margins. The pahoehoe flow advanced through a series of down slope and cross-slope breakouts, which began as approximately 0.2 m-thick units (i.e., toes) that coalesced and inflated to become approximately meter-thick lobes. The lobes were thickest above the lowest points of the initial topography and above shallow to reverse facing slopes, defined relative to the local flow direction. The flow path was typically controlled by high-standing topography, with the zone directly adjacent to the final lobe margin having an average relief that was a few centimeters higher than the lava inundated region. This suggests that toe-scale topography can, at least temporarily, exert strong controls on pahoehoe flow paths by impeding the lateral spreading of the lobe. Observed cycles of enhanced areal spreading and inflated lobe morphology are also explored using a model that considers the statistical likelihood of sequential breakouts from active flow margins and the effects of topographic barriers.

  10. Gas-controlled seafloor doming on Opouawe Bank, offshore New Zealand

    NASA Astrophysics Data System (ADS)

    Koch, Stephanie; Berndt, Christian; Bialas, Joerg; Haeckel, Matthias; Crutchley, Gareth; Papenberg, Cord; Klaeschen, Dirk; Greinert, Jens

    2015-04-01

    The process of gas accumulation and subsequent sediment doming appears to be a precursory process in the development of methane seep sites on Opouawe Bank and might be a common characteristic for gas seeps in general. Seabed domes appear as unimpressive topographic highs with diameters ranging from 10-1000 m and exhibit small vertical displacements and layer thickness in comparison to their width. The dome-like uplift of the sediments results from an increase in pore pressure caused by gas accumulation in near-seabed sediments. In this context sediment doming is widely discussed to be a precursor of pockmark formation. Our results suggest that by breaching of domed seafloor sediments a new seep site can develop and contrary to ongoing discussion does not necessarily lead to the formation of pockmarks. There are clear differences in individual gas migration structures that indicate a progression through different evolutionary stages, which range from channeled gas flow and associated seismic blanking, to gas trapping beneath relatively low-permeability horizons, and finally overpressure accumulation and doming. We present high resolution sub-bottom profiler (Parasound) and 2D multichannel seismic data from Opouawe Bank, an accretionary ridge at the Hikurangi Margin, offshore New Zealand's North Island. Beneath this bank, methane migrates along stratigraphic pathways from a maximum source depth of 1500-2100 mbsf (meter below seafloor) towards active cold seeps at the seafloor. We show that, in the shallow sediment of the upper 100 mbsf, this primary migration mechanism changes into a process of gas accumulation leading to sediment doming. Modeling the height of the gas column necessary to create different dome geometries, shows that doming due to gas accumulation is feasible and consistent with field observations. The well-stratified, sub-horizontal strata that exist beneath Opouawe Bank provide favorable conditions for this type of seep development because shallow

  11. Holodeck: Telepresence Dome Visualization System Simulations

    NASA Technical Reports Server (NTRS)

    Hite, Nicolas

    2012-01-01

    This paper explores the simulation and consideration of different image-projection strategies for the Holodeck, a dome that will be used for highly immersive telepresence operations in future endeavors of the National Aeronautics and Space Administration (NASA). Its visualization system will include a full 360 degree projection onto the dome's interior walls in order to display video streams from both simulations and recorded video. Because humans innately trust their vision to precisely report their surroundings, the Holodeck's visualization system is crucial to its realism. This system will be rigged with an integrated hardware and software infrastructure-namely, a system of projectors that will relay with a Graphics Processing Unit (GPU) and computer to both project images onto the dome and correct warping in those projections in real-time. Using both Computer-Aided Design (CAD) and ray-tracing software, virtual models of various dome/projector geometries were created and simulated via tracking and analysis of virtual light sources, leading to the selection of two possible configurations for installation. Research into image warping and the generation of dome-ready video content was also conducted, including generation of fisheye images, distortion correction, and the generation of a reliable content-generation pipeline.

  12. Continuous magma recharge at Mt. Etna during the 2011-2013 period controls the style of volcanic activity and compositions of erupted lavas

    NASA Astrophysics Data System (ADS)

    Viccaro, Marco; Calcagno, Rosario; Garozzo, Ileana; Giuffrida, Marisa; Nicotra, Eugenio

    2015-02-01

    Volcanic rocks erupted during the January 2011 - April 2013 paroxysmal sequence at Mt. Etna volcano have been investigated through in situ microanalysis of mineral phases and whole rock geochemistry. These products have been also considered within the framework of the post-2001 record, evidencing that magmas feeding the 2011-2013 paroxysmal activity inherited deep signature comparable to that of the 2007-2009 volcanic rocks for what concerns their trace element concentration. Analysis performed on plagioclase, clinopyroxene and olivine, which are sensitive to differentiation processes, show respectively fluctuations of the An, Mg# and Fo contents during the considered period. Also major and trace elements measured on the whole rock provide evidence of the evolutionary degree variations through time. Simulations by MELTS at fixed chemical-physical parameters allowed the definition of feeding system dynamics controlling the geochemical variability of magmas during the 2011-2013 period. Specifically, compositional changes have been interpreted as due to superimposition of fractional crystallization and mixing in variable proportions with more basic magma ascending from intermediate to shallower levels of the plumbing system. Composition of the recharging end-member is compatible with that of the most basic magmas emitted during the 2007 and the early paroxysmal eruptions of 2012. Analysis of the erupted volumes of magma combined with its petrologic evolution through time support the idea that large volumes of magma are continuously intruded and stored in the intermediate plumbing system after major recharging phases in the deepest levels of it. Transient recharge from the intermediate to the shallow levels is then responsible for the paroxysmal eruptions.

  13. The influence of wind on the estimation of lava effusion rate from thermal remote-sensing

    NASA Astrophysics Data System (ADS)

    Garel, F.; Kaminski, E.; Tait, S.; Limare, A.

    2013-08-01

    Effusion rate is a key parameter to model lava flow advance and associated risks. Estimation of effusion rate from thermal remote-sensing using satellite data has matured to the point where it can be an operational monitoring tool, notably for volcanoes without a ground observatory. However, robust physical models, as required for quantitative interpretations, have not yet been adequately developed. The current and widely used method relates the satellite-measured radiated power to the flow effusion rate through the lava area, with an empirical fit that assumes a low surface cooling efficiency. Here we use novel fluid dynamic laboratory experiments and viscous flow theory to show that assuming low convective cooling at the surface of the flow leads to a systematic underestimation of the effusion rate. This result, obtained for the case of a hot isoviscous gravity current which cools as it flows, relies only on the respective efficiency of convection and radiation at the flow surface, and is independent of the details of the internal flow model. Applying this model to lava flows cooling under classical wind conditions, we find that the model compares well to data acquired on basaltic eruptions within the error bars corresponding to the uncertainties on natural wind conditions. Hence the thermal proxy deduced from the isoviscous model does not seem to require an additional fitting parameter accounting for internal flow processes such as crystallization. The predictions of the model are not correct however for thick lava flows such as highly viscous domes, because a thermal steady state is probably not reached for these flows. Furthermore, in the case of very large basaltic flows, extra cooling is expected due to self-induced convection currents. The increased efficiency of surface cooling for these large eruptions must be taken into account to avoid a gross - and dangerously misleading - underestimate of the effusion rate.

  14. Ambient Effects on Basalt and Rhyolite Lavas under Venusian, Subaerial, and Subaqueous Conditions

    NASA Technical Reports Server (NTRS)

    Bridges, Nathan T.

    1997-01-01

    Both subaerial and subaqueous environments have been used as analog settings for Venus volcanism. To assess the merits of this, the effects of ambient conditions on the physical properties of lava on Venus, the seafloor, and land on Earth are evaluated. Rhyolites on Venus and on the surface of Earth solidify before basalts do because of their lower eruption temperatures. Rhyolite crust is thinner than basalt crust at times less than about an hour, especially on Venus. At later times, rhyolite crust is thicker because of its lower latent heat relative to basalt. The high pressure on the seafloor and Venus inhibits the exsolution of volatiles in lavas. Vesicularity and bulk density are proportional, so that lavas of the same composition should be more dense on the seafloor and less dense on land. Because viscosity depends partly upon the fraction of unvesiculated water in a melt, basalts with the same initial volatile abundance will be least viscous on the seafloor and most viscous on land. Assuming the same preeruptive H2O contents, molten rhyolites on Venus will have viscosities approx. 10% that of rhyolites on land. Despite lower expected viscosities, under-water flows are more buoyant and should have heights like subaerial and Venusian lavas of the same composition and extrusive history. In cases where the influence of crust is insignificant, a volume of rhyolite will have a higher aspect ratio than the same volume of basalt, no matter what the environment. If flow rheology is dominated by the presence of strong crust, aspect ratios differ little among environments or between compositions. These analyses support a rhyolitic interpretation for the composition of Venusian festooned flows and a basaltic interpretation for the composition of Venusian steep-sided domes. Although ambient effects are significant, extrusion rate and eruption history must also be considered to explain analogous volcanic landforms on Earth and Venus.

  15. Geology, geochronology, and potential volcanic hazards in the Lava Ridge-Hells Half Acre area, eastern Snake River Plain, Idaho

    USGS Publications Warehouse

    Kuntz, Mel A.; Dalrymple, G. Brent

    1979-01-01

    The evaluation of volcanic hazards for the proposed Safety Test Reactor Facility (STF) at the Argonne National Laboratory-West (ANLW) site, Idaho National Engineering Laboratory (INEL), Idaho, involves an analysis of the geology of the Lava Ridge-Hells Half Acre area and of K-At age determinations on lava flows in cored drill holes. The ANLW site at INEL lies in a shallow topographic depression bounded on the east and south by volcanic rift zones that are the locus of past shield-type basalt volcanism and by rhyolite domes erupted along the ring fracture of an inferred rhyolite caldera. The K-At age data indicate that the ANLW site has been flooded by basalt lava flows at irregular intervals from perhaps a few thousand years to as much as 300,000-400,000 years, with an average recurrence interval between flows of approximately 80,000-100,000 years. At least five major lava flows have covered the ANLW site within the past 500,000 years.

  16. Extinction and Sky Brightness at Dome C

    NASA Astrophysics Data System (ADS)

    Faurobert, M.; Arnaud, J.; Vernisse, Y.

    2012-06-01

    We have installed a small telescope to monitor the sky brightness around the sun at the French-Italian station Concordia at Dome C in Antarctica. Previous campaigns have been performed with the same instrument at Haleakala in Hawai and Sunspot in New Mexico. We compare here the results of the first year of the campaign at Dome C (2008) to the purest sky observed at Haleakala. We show that Dome C is an outstanding site for coronal observations. Compared to Haleaka, it appears to be more transparent, and to contain less aerosols. Its water vapour content is also significantly smaller. These results still have to be confirmed by the analysis of the 2009 and 2010 data.

  17. Environmental assessment, Richton Dome site, Mississippi (US)

    SciTech Connect

    none,

    1986-05-01

    The Nuclear Waste Policy Act of 1982 (42 USC Sections 10101-10226) requires the environmental assessment of a potential site to include a statement of the basis for the nomination of a site as suitable for characterization. Volume 2 of this environmental assessment provides a detailed evaluation of the Richton Dome Site and its suitability as the site for a radioactive waste disposal facility under DOE siting guidelines, as well as a comparison of the Richton Dome site with other proposed sites. Evaluation of the Richton Dome site is based on the reference repository design, but the evaluation will not change if based on the Mission Plan repository concept. The comparative evaluation of proposed sites is required under DOE guidelines, but is not intended to directly support the subsequent recommendation of three sites for characterization as candidate sites. 428 refs., 24 figs., 62 tabs. (MHB)

  18. Map showing lava-flow hazard zones, Island of Hawaii

    USGS Publications Warehouse

    Wright, Thomas L.; Chun, Jon Y.F.; Exposo, Jean; Heliker, Christina; Hodge, Jon; Lockwood, John P.; Vogt, Susan M.

    1992-01-01

    This map shows lava-flow hazard zones for the five volcanoes on the Island of Hawaii. Volcano boundaries are shown as heavy, dark bands, reflecting the overlapping of lava flows from adjacent volcanoes along their common boundary. Hazard-zone boundaries are drawn as double lines because of the geologic uncertainty in their placement. Most boundaries are gradational, and the change In the degree of hazard can be found over a distance of a mile or more. The general principles used to place hazard-zone boundaries are discussed by Mullineaux and others (1987) and Heliker (1990). The differences between the boundaries presented here and in Heliker (1990) reflect new data used in the compilation of a geologic map for the Island of Hawaii (E.W. Wolfe and Jean Morris, unpub. data, 1989). The primary source of information for volcano boundaries and generalized ages of lava flows for all five volcanoes on the Island of Hawaii is the geologic map of Hawaii (E.W. Wolfe and Jean Morris, unpub. data, 1989). More detailed information is available for the three active volcanoes. For Hualalai, see Moore and others (1987) and Moore and Clague (1991); for Mauna Loa, see Lockwood and Lipman (1987); and for Kilauea, see Holcomb (1987) and Moore and Trusdell (1991).

  19. Preferential Weathering of Carbonatite Lava at Ol Doinyo Lengai, Tanzania

    NASA Astrophysics Data System (ADS)

    Robertson, C. H.; Harpp, K. S.; Geist, D.; Bosselait, M.

    2014-12-01

    Although carbonatites have been produced since the Archean and are preserved in the geologic record, the East African Rift is home to the only active carbonatite volcano, at Ol Doinyo Lengai. It has long been known that the natrocarbonatites become strongly weathered the first time they are exposed to rain. We studied the weathering patterns in the field and have determined the mineralogical transformations via petrography and XRD. Mass transport is assessed by XRF and ICP-MS analyses. Water preferentially dissolves specific minerals in the pristine lava, permeating through earlier layers of flow to form stalactites, which have differing mineralogical composition. These hang both from the host flow and from the bottom of underlying earlier flows. The weathering product is characterized by trona, a hydrated carbonate mineral, as well as the sodium sulfate mineral aphthitalite. Data from XRD analysis of the carbonatite lava confirm transformation of its original minerals, nyerereite and gregoryite, into secondary hydrated carbonate minerals gaylussite and pirssonite (e.g., Zaitsev and Keller, 2006). This transformation is attributed to the instability of the erupted minerals at atmospheric conditions. Data from XRF analysis indicate a 4-fold increase in the amount of sodium present in the stalactite as well as a 8-fold increase in potassium. Trace element analysis by ICP-MS indicates significantly elevated levels of vanadium, copper, and rubidium in the weathering product, whereas strontium, barium, lanthanum, and cesium are left behind in high concentrations in the carbonatite lava. Our results provide further evidence supporting the proposal by Dawson et al. (1987) that calcium carbonate dominated lava flows result from extensive weathering of sodic carbonatite flows.

  20. Mafic-crystal distributions, viscosities, and lava structures of some Hawaiian lava flows

    NASA Astrophysics Data System (ADS)

    Rowland, Scott K.; Walker, George P. L.

    1988-09-01

    The distribution patterns of mafic phenocrysts in some Hawaiian basalt flows are consistent with simple in situ gravitational settling. We use the patterns to estimate the crystal settling velocity and hence viscosity of the lava, which in turn can be correlated with surface structures. Numerical modeling generates theoretical crystal concentration profiles through lava flow units of different thicknesses for differing settling velocities. By fitting these curves to field data, crystal-settling rates through the lavas can be estimated, from which the viscosities of the flows can be determined using Stokes' Law. Lavas in which the crystal settling velocity was relatively high (on the order of 5 × 10 -4 cm/sec) show great variations in phenocryst content, both from top to bottom of the same flow unit, and from one flow unit to another. Such lava is invariably pahoehoe, flow units of which are usually less than 1 m thick. Lavas in which the crystal-settling velocity was low show a small but measurable variation in phenocryst content. These lavas are part of a progression from a rough pahoehoe to toothpaste lava to a'a. Toothpaste lava is characterized by spiny texture as well as the ability to retain surface grooves during solidification, and flow units are usually thicker than 1 m. In the thickest of Hawaiian a'a flows, those of the distal type, no systematic crystal variations are observed, and high viscosity coupled with a finite yield strength prevented crystal settling. The amount of crystal settling in pahoehoe indicates that the viscosity ranged from 600 to 6000 Pa s. The limited amount of settling in toothpaste lava indicates a viscosity greater than this value, approaching 12,000 Pa s. We infer that distal-type a'a had a higher viscosity still and also possessed a yield strength.

  1. Open-foldable domes with high-tension textile membranes: The GREGOR dome

    NASA Astrophysics Data System (ADS)

    Hammerschlag, R. H.; Kommers, J. N.; Visser, S.; Bettonvil, F. C. M.; van Schie, A. G. M.; van Leverink, S. J.; Sliepen, G.; Jägers, A. P. L.; Schmidt, W.; Volkmer, R.

    2012-11-01

    Double layers of high-tensioned textile membranes were applied to the completely open-foldable dome for the GREGOR telescope for the first time. Simultaneous climate measurements inside and outside the dome have proven the thermal-insulating capability of this double-layer construction. The GREGOR dome is the result of the continuation of the ESO research on open-foldable domes with textile structures, followed by the research for the DOT dome with high-tensioned textile membranes. It cleared the way to extreme stability required for astronomical practice on high mountain sites with heavy storms and ice formation. The storm Delta with 245 km/h 1-minute mean maximum at the location of the GREGOR caused no problems, nor did other storms afterwards. Opening and closing experiences up to wind speeds of 90 km/h were without problems. New technical developments were implemented and tested at the GREGOR dome, opening the way for application to much larger domes up to the 30 m diameter-class range.

  2. The eruption in Holuhraun, NE Iceland 2014-2015: Real-time monitoring and influence of landscape on lava flow

    NASA Astrophysics Data System (ADS)

    Jónsdóttir, Ingibjörg; Höskuldsson, Ármann; Thordarson, Thor; Bartolini, Stefania; Becerril, Laura; Marti Molist, Joan; Þorvaldsson, Skúli; Björnsson, Daði; Höskuldsson, Friðrik

    2016-04-01

    The largest eruption in Iceland since the Laki 1783-84 event began in Holuhraun, NE Iceland, on 31 August 2014, producing a lava flow field which, by the end of the eruption on February 27th 2015, covered 84,5 km2 with volume of 1,44 km3. Throughout the event, various satellite images (NOAA AVHRR, MODIS, SUOMI NPP VIIRS, ASTER, LANDSAT7&8, EO-1 ALI & HYPERION, RADARSAT-2, SENTINEL-1, COSMO SKYMED, TERRASAR X) were analysed to monitor the development of activity, identify active flow fronts and channels, and map the lava extent in close collaboration with the on-site field group. Aerial photographs and radar images from the Icelandic Coast Guard Dash 8 aircraft supported this effort. By the end of 2015, Loftmyndir ehf had produced a detailed 3D model of the lava using aerial photographs from 2013 and 2015. The importance of carrying out real-time monitoring of a volcanic eruption is: i) to locate sites of elevated temperature that may be registering new areas of activity within the lava or opening of vents or fissures. ii) To establish and verify timing of events at the vents and within the lava. iii) To identify potential volcanic hazard that can be caused by lava movements, eruption-induced flash flooding, tephra fallout or gas pollution. iv) to provide up-to-date regional information to field groups concerning safety as well as to locate sites for sampling lava, tephra and polluted water. v) to produce quantitative information on magma discharge and lava flow advance, map the lava extent, document the flow morphology and plume/tephra dispersal. During the eruption, these efforts supported mapping of the extent of the lava every 3-4 days on average underpinning the time series of magma discharge calculations. Digitial elevation models from before and after the event, combined with the real-time data series, supports detailed analysis of how landscape affects lava flow in a flat terrain (<0,4°), and provides important input to further developing lava flow models

  3. Table Mountain Shoshonite Porphyry Lava Flows and Their Vents, Golden, Colorado

    USGS Publications Warehouse

    Drewes, Harald

    2008-01-01

    South Table Mountain, lava flow 3 forms a low, broad dome that forced flow 4 into channels now restricted to the west and northeast flanks of that mesa. Mesa-capping lava flows 3 and 4 are broken by many small normal faults and are warped into open synclines, probably in response to local stresses associated with the settling of piedmont deposits into the Denver Basin. Mid-Tertiary deposits are inferred to have covered the upper part of the Denver Formation and its lavas; these deposits could thus have been instrumental in changing the stream flow direction to the east before the onset of Neogene uplift and consequent canyon cutting across the flows. Other younger deposits may also have covered the area, to be linked to this consequent canyon cutting.

  4. Littoral hydrovolcanic explosions: A case study of lava-seawater interaction at Kilauea Volcano

    USGS Publications Warehouse

    Mattox, T.N.; Mangan, M.T.

    1997-01-01

    A variety of hydrovolcanic explosions may occur as basaltic lava flows into the ocean. Observations and measurements were made during a two-year span of unusually explosive littoral activity as tube-fed pahoehoe from Kilauea Volcano inundated the southeast coastline of the island of Hawai'i. Our observations suggest that explosive interactions require high entrance fluxes (??? 4 m3/s) and are most often initiated by collapse of a developing lava delta. Two types of interactions were observed. "Open mixing" of lava and seawater occurred when delta collapse exposed the mouth of a severed lava tube or incandescent fault scarp to wave action. The ensuing explosions produced unconsolidated deposits of glassy lava fragments or lithic debris. Interactions under "confined mixing" conditions occurred when a lava tube situated at or below sea level fractured. Explosions ruptured the roof of the tube and produced circular mounds of welded spatter. We estimate a water/rock mass ratio of 0.15 for the most common type of littoral explosion and a kinetic energy release of 0.07-1.3 kJ/kg for the range of events witnessed.

  5. The Flow of the Gibbon LAVA Element Is Facilitated by the LINE-1 Retrotransposition Machinery

    PubMed Central

    Meyer, Thomas J.; Held, Ulrike; Nevonen, Kimberly A.; Klawitter, Sabine; Pirzer, Thomas; Carbone, Lucia; Schumann, Gerald G.

    2016-01-01

    LINE-Alu-VNTR-Alu-like (LAVA) elements comprise a family of non-autonomous, composite, non-LTR retrotransposons specific to gibbons and may have played a role in the evolution of this lineage. A full-length LAVA element consists of portions of repeats found in most primate genomes: CT-rich, Alu-like, and VNTR regions from the SVA retrotransposon, and portions of the AluSz and L1ME5 elements. To evaluate whether the gibbon genome currently harbors functional LAVA elements capable of mobilization by the endogenous LINE-1 (L1) protein machinery and which LAVA components are important for retrotransposition, we established a trans-mobilization assay in HeLa cells. Specifically, we tested if a full-length member of the older LAVA subfamily C that was isolated from the gibbon genome and named LAVAC, or its components, can be mobilized in the presence of the human L1 protein machinery. We show that L1 proteins mobilize the LAVAC element at frequencies exceeding processed pseudogene formation and human SVAE retrotransposition by > 100-fold and ≥3-fold, respectively. We find that only the SVA-derived portions confer activity, and truncation of the 3′ L1ME5 portion increases retrotransposition rates by at least 100%. Tagged de novo insertions integrated into intronic regions in cell culture, recapitulating findings in the gibbon genome. Finally, we present alternative models for the rise of the LAVA retrotransposon in the gibbon lineage. PMID:27635049

  6. The Flow of the Gibbon LAVA Element Is Facilitated by the LINE-1 Retrotransposition Machinery.

    PubMed

    Meyer, Thomas J; Held, Ulrike; Nevonen, Kimberly A; Klawitter, Sabine; Pirzer, Thomas; Carbone, Lucia; Schumann, Gerald G

    2016-10-30

    LINE-Alu-VNTR-Alu-like (LAVA) elements comprise a family of non-autonomous, composite, non-LTR retrotransposons specific to gibbons and may have played a role in the evolution of this lineage. A full-length LAVA element consists of portions of repeats found in most primate genomes: CT-rich, Alu-like, and VNTR regions from the SVA retrotransposon, and portions of the AluSz and L1ME5 elements. To evaluate whether the gibbon genome currently harbors functional LAVA elements capable of mobilization by the endogenous LINE-1 (L1) protein machinery and which LAVA components are important for retrotransposition, we established a trans-mobilization assay in HeLa cells. Specifically, we tested if a full-length member of the older LAVA subfamily C that was isolated from the gibbon genome and named LAVAC, or its components, can be mobilized in the presence of the human L1 protein machinery. We show that L1 proteins mobilize the LAVAC element at frequencies exceeding processed pseudogene formation and human SVAE retrotransposition by > 100-fold and ≥3-fold, respectively. We find that only the SVA-derived portions confer activity, and truncation of the 3' L1ME5 portion increases retrotransposition rates by at least 100%. Tagged de novo insertions integrated into intronic regions in cell culture, recapitulating findings in the gibbon genome. Finally, we present alternative models for the rise of the LAVA retrotransposon in the gibbon lineage.

  7. Basics of lava-lamp convection.

    PubMed

    Gyüre, Balázs; Jánosi, Imre M

    2009-10-01

    Laboratory experiments are reported in an immiscible two-fluid system, where thermal convection is initiated by heating at the bottom and cooling at the top. The lava-lamp regime is characterized by a robust periodic exchange process where warm blobs rise from the bottom, attach to the top surface for a while, then cold blobs sink down again. Immiscibility allows to reach real steady (dynamical equilibrium) states which can be sustained for several days. Two modes of lava-lamp convection could be identified by recording and evaluating temperature time series at the bottom and at the top of the container: a "slow" mode is determined by an effective heat transport speed at a given temperature gradient, while a second mode of constant periodicity is viscosity limited. Contrasting of laboratory and geophysical observations yields the conclusion that the frequently suggested lava-lamp analogy fails for the accepted models of mantle convection.

  8. Studies of fluid instabilities in flows of lava and debris

    NASA Technical Reports Server (NTRS)

    Fink, Jonathan H.

    1987-01-01

    At least two instabilities have been identified and utilized in lava flow studies: surface folding and gravity instability. Both lead to the development of regularly spaced structures on the surfaces of lava flows. The geometry of surface folds have been used to estimate the rheology of lava flows on other planets. One investigation's analysis assumed that lava flows have a temperature-dependent Newtonian rheology, and that the lava's viscosity decreased exponentially inward from the upper surface. The author reviews studies by other investigators on the analysis of surface folding, the analysis of Taylor instability in lava flows, and the effect of surface folding on debris flows.

  9. Evaluation of dome-input geometry for pyroelectric detectors

    NASA Astrophysics Data System (ADS)

    Zeng, J.; Hanssen, L. M.; Eppeldauer, G. P.

    2013-06-01

    Dome-input pyroelectric radiometers with different black coatings were developed to extend the spectral responsivity scale from near infrared (NIR) to 20 μm. The reflective dome with shiny gold-coating has been known to be an efficient light trap to enhance the detector absorptance and to minimize spectral responsivity variation. The enhancement of spectral responsivity using reflective dome relies on optical characterization of black coating on detector, reflectance of dome reflector, and input aperture dimension, etc. We report a comparison of spectral responsivity of dome-input pyroelectric radiometers measured with/without dome-trap from 2.4 μm to 14 μm using the Infrared Spectral Comparator Facility (IRSCF) at NIST. The results show 4 % to 8 % gain of responsivity for two dome-input pyroelectric detectors, with reduced structure of spectral responsivity. The uncertainty of dome-input pyroelectric radiometer calibrations is approximately 2 % (k = 2).

  10. Quenching and disruption of lunar KREEP lava flows by impacts

    NASA Technical Reports Server (NTRS)

    Ryder, Graham

    1988-01-01

    The results of a reexamination of petrography of the Apollo 15 KREEP basalts are reported. Several of the basalts contain yellow residual glasses which cross-cut the crystallized phases; some show more extreme disruption. The features of the glasses appear to be compatible only with impact disruption, ejection, and quenching from actively crystallizing flows, indicating a high impact flux immediately after the impact that formed the Imbrium basin. No other example of impacts into active lava flows is known in the solar system.

  11. Explosive lava-water interactions II: self-organization processes among volcanic rootless eruption sites in the 1783-1784 Laki lava flow, Iceland

    NASA Astrophysics Data System (ADS)

    Hamilton, Christopher W.; Fagents, Sarah A.; Thordarson, Thorvaldur

    2010-05-01

    We have applied quantitative geospatial analyses to rootless eruption sites in the Hnúta and Hrossatungur groups of the 1783-1784 Laki lava flow to establish how patterns of spatial distribution can be used to obtain information about rootless cone emplacement processes and paleo-environments. This study utilizes sample-size-dependent nearest neighbor (NN) statistics and Voronoi tessellations to quantify the spatial distribution of rootless eruption sites and validate the use of statistical NN analysis as a remote sensing tool. Our results show that rootless eruption sites cluster in environments with abundant lava and water resources, but competition for limited groundwater in these clusters can cause rootless eruption sites to develop repelled distributions. This pattern of self-organization can be interpreted within the context of resource availability and depletion. Topography tends to concentrate lava (fuel) and water (coolant) within topographic lows, thereby promoting explosive lava-water interactions in these regions. Given an excess supply of lava within broad sheet lobes, rootless eruption sites withdraw groundwater from their surroundings until there is insufficient water to maintain analogs to explosive molten fuel-coolant interactions. Rootless eruption sites may be modeled as a network of water extraction wells that draw down the water table in their vicinity. Rootless eruptions at locations with insufficient groundwater may either fail to initiate or terminate before explosive activity has ceased at nearby locations with a greater supply of water, thus imparting a repelled distribution to observed rootless eruption sites.

  12. Low-temperature thermochronology of the central and northwestern Pamir gneiss domes

    NASA Astrophysics Data System (ADS)

    Khan, Jahanzeb; Rutte, Daniel; Ratschbacher, Lothar; Stübner, Konstanze

    2013-04-01

    The Pamir—the western prolongation of the Tibet-Himalaya orogen—resulted from N-S convergence between India and Asia. In the Pamir, the Cenozoic orogeny formed a high-relief mountain knot of ~500 km N-S extent, which contrasts with the ~1000 km wide, low-relief Tibet Plateau. About ~30% of the surface exposure of the Pamir comprises high-grade, middle to lower crustal metamorphic rocks exhumed in Cenozoic syn-orogenic domes; understanding the evolution of these domes is central to understanding the behavior of the Himalaya-Tibet-Pamir orogen because the domes expose a range of shallow to deep structural levels. In the Central Pamir, the (from east to west) Shatput, Muskol, Sarez, and Yazgulem domes form a nearly continuous anticlinorium of greenschist- to mostly amphibolite-facies crystalline rocks, framed by mostly unmetamorphic volcano-sedimentary rocks. The crystalline rocks contain Mesozoic intrusives. The Cenozoic evolution shows a pre-~20 Ma prograde evolution and a post-~20 Ma retrograde evolution accompanied by N-S extension that is replaced since ~10 Ma by renewed N-S shortening. Cenozoic magmatic activity spans 40-15 Ma. Here, we focus on a characterization of the post~20 Ma exhumation history in the central Pamir domes, employing zircon and apatite fission-track and (U-Th)/He thermochronology. These domes yielded apatite fission-track ages between 15 and 6 Ma; there are several trends: (1) Younger ages occur in the west; this is interpreted as an effect of erosional exhumation along the deeply incised western Pamir. (2) Ages young toward the bounding normal shear zones. (3) Age versus elevation relationships indicate most rapid exhumation at ~10 Ma. In the Southern Pamir, low-temperature thermochronology records a longer extensional exhumation history, ending at ~5 Ma in the Alichur dome and ~2 Ma in the Shakhdara dome. In the Northern Pamir, the Triassic Kurgovat gneiss dome shows Cenozoic exhumation from less than 10 km depth; Cenozoic exhumation

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

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

  14. Geology of selected lava tubes in the Bend Area, Oregon

    NASA Technical Reports Server (NTRS)

    Greely, R.

    1971-01-01

    Longitudinal profiles representing 5872.5 m of mapped lava tubes and a photogeologic map relating lava tubes to surface geology, regional structure and topography are presented. Three sets of lava tubes were examined: (1) Arnold Lava Tube System (7km long) composed of collapsed and uncollapsed tube segments and lava ponds, (2) Horse Lava Tube System (11 km long) composed of parallel and anastomosing lava tube segments, and (3) miscellaneous lava tubes. Results of this study tend to confirm the layered lava hypothesis of Ollier and Brown (1965) for lava tube formation; however, there are probably several modes of formation for lava tubes in general. Arnold System is a single series of tubes apparently formed in a single basalt flow on a relatively steep gradient. The advancing flow in which the tubes formed was apparently temporarily halted, resulting in the formation of lava ponds which were inflated and later drained by the lava tube system. Horse System probably formed in multiple, interconnected flows. Pre-flow gradient appears to have been less than for Arnold System, and resulted in meandrous, multiple tube networks.

  15. Water recycling at the Millennium Dome.

    PubMed

    Hills, S; Smith, A; Hardy, P; Birks, R

    2001-01-01

    Thames Water is working with the New Millennium Experience Company to provide a water recycling system for the Millennium Dome which will supply 500 m3/d of reclaimed water for WC and urinal flushing. The system will treat water from three sources: rainwater--from the Dome roof greywater--from handbasins in the toilet blocks groundwater--from beneath the Dome site The treatment technologies will range from "natural" reedbeds for the rainwater, to more sophisticated options, including biological aerated filters and membranes for the greywater and groundwater. Pilot scale trials were used to design the optimum configuration. In addition to the recycling system, water efficient devices will be installed in three of the core toilet blocks as part of a programme of research into the effectiveness of conservation measures. Data on water usage and customer behaviour will be collected via a comprehensive metering system. Information from the Dome project on the economics and efficiency of on-site recycling at large scale and data on water efficient devices, customer perception and behaviour will be of great value to the water industry. For Thames Water, the project provides vital input to the development of future water resource strategies.

  16. Osteochondral Lesions of the Talar Dome.

    PubMed

    Stone

    1996-03-01

    Osteochondral lesions of the talar dome are relatively common causes of ankle pain and disability. Trauma is the most common cause, but ischemic necrosis, en-docrine disorders, and genetic factors may have etiologic significance. Medial lesions are usually located posteriorly on the dome of the talus, whereas lateral lesions are most frequently located anteriorly. Although the staging system described by Berndt and Harty remains popular, it may not accurately reflect the integrity of the articular cartilage. Small lesions of the talar dome may be present despite a normal appearance on plain radiography. Bone scintigraphy may show increased radionuclide uptake in the talar dome. Magnetic resonance imaging is also sensitive for identifying intraosseous abnormalities in the talus and has the added benefit of revealing other types of soft-tissue lesions not visible on routine radiographic studies. Computed tomography remains the imaging technique of choice when delineation of a bone fragment is desired. Nonoperative management of osteochondral lesions, including restricted weight-bearing and/or immobilization, is recommended unless a loose fragment is clearly present. Surgical options include drilling (usually reserved for intact lesions), debridement of the lesion with curettage or abrasion of the bone bed, internal fixation of the fragment, and bone grafting. Recent technical advances allow these procedures to be performed arthroscopically, with potential reduction of surgical trauma, length of hospital stay, and complication rates.

  17. The Urban Dust Dome: A Demonstration Model

    ERIC Educational Resources Information Center

    Cross, Ralph D.

    1973-01-01

    Working plans for an inexpensive urban dust dome model are presented together with some generalizations about urban atmosphere pollution. Theories and principles of atmospheric pollution which are introduced can be made meaningful to elementary students through classroom use of this model. (SM)

  18. Small domes on Venus - Characteristics and origin

    NASA Technical Reports Server (NTRS)

    Aubele, Jayne C.; Sliuta, E. N.

    1990-01-01

    The areal and size-frequency distribution, abundance, individual characteristics, and geologic and regional associations of small domes in the Venera data set are examined. It is noted that, because of their numbers and widespread occurence, regardless of origin, these structures will be important in the local and global geographic interpretation of the surface. It is concluded that small domes of 20 km in diameter occur in numbers of order 10,000 on the northern quarter of the surface of Venus, and that small domes are interpreted to be predominantly low shield volcanos and to represent multiple centralized effusive eruptions of discrete volumes over finite periods. It is noted that small domes occur throughout the northern latitudes, but attain maximum regional concentrations in two areas, one located north of Thetis Regio in Akkruva Colles, and another located on the northeast flanks of Beta Regio in Guinevere Planitia. The presence of two global concentrations implies that magma production and eruption were enhanced within these two areas.

  19. Small domes on Venus - Characteristics and origin

    NASA Astrophysics Data System (ADS)

    Aubele, Jayne C.; Sliuta, E. N.

    1990-12-01

    The areal and size-frequency distribution, abundance, individual characteristics, and geologic and regional associations of small domes in the Venera data set are examined. It is noted that, because of their numbers and widespread occurence, regardless of origin, these structures will be important in the local and global geographic interpretation of the surface. It is concluded that small domes of 20 km in diameter occur in numbers of order 10,000 on the northern quarter of the surface of Venus, and that small domes are interpreted to be predominantly low shield volcanos and to represent multiple centralized effusive eruptions of discrete volumes over finite periods. It is noted that small domes occur throughout the northern latitudes, but attain maximum regional concentrations in two areas, one located north of Thetis Regio in Akkruva Colles, and another located on the northeast flanks of Beta Regio in Guinevere Planitia. The presence of two global concentrations implies that magma production and eruption were enhanced within these two areas.

  20. Dome Storage of Farmer Stock Peanuts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The small-scale farmer stock storage research facility at the National Peanut Research Laboratory in Dawson, GA consisting of four warehouses and four monolithic domes was used to conduct a 3-yr study looking at the effects of storing peanuts through the summer months following harvest. The study wa...

  1. 49 CFR 178.255-3 - Expansion domes.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Expansion domes. 178.255-3 Section 178.255-3 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY... Specifications for Portable Tanks § 178.255-3 Expansion domes. (a) Expansion domes, if applied, must have...

  2. 49 CFR 178.255-3 - Expansion domes.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Expansion domes. 178.255-3 Section 178.255-3 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... Portable Tanks § 178.255-3 Expansion domes. (a) Expansion domes, if applied, must have a minimum...

  3. 49 CFR 178.255-3 - Expansion domes.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Expansion domes. 178.255-3 Section 178.255-3 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... Portable Tanks § 178.255-3 Expansion domes. (a) Expansion domes, if applied, must have a minimum...

  4. 49 CFR 178.255-3 - Expansion domes.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Expansion domes. 178.255-3 Section 178.255-3 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... Portable Tanks § 178.255-3 Expansion domes. (a) Expansion domes, if applied, must have a minimum...

  5. 49 CFR 178.255-3 - Expansion domes.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Expansion domes. 178.255-3 Section 178.255-3 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... Portable Tanks § 178.255-3 Expansion domes. (a) Expansion domes, if applied, must have a minimum...

  6. Structural analysis of flow-related textures in lavas

    NASA Astrophysics Data System (ADS)

    Smith, John V.

    2002-05-01

    The textures of coherent volcanic rocks, including lavas and volcanic intrusives, commonly contain features that are attributed to flowage. Previous applications of structural analysis to volcanic rocks are expanded here to provide a framework for analysis. Textures, defined as the crystallinity, granularity and shapes and arrangements of the components (crystals, glass and voids) of a rock, together with structures, defined as individual features composed of the disposition, attitude, arrangement or relative positions of the components of a rock, are first described. Second, the spatial fabrics (shapes and arrangements of the components of a rock and the orientation of textures and structures) are identified. Third, textures, structures and fabrics are placed in the spatial and temporal geological context. Finally, detailed interpretations of the kinematics and rheology of structures and fabrics is made, leading to an integrated flow history of the rock. Illustrative case studies include rhyolite from the basal part of the Tertiary Minyon Falls dome, northeastern New South Wales, Australia, which has a texture comprising planar domains of differing crystal abundance (flow bands), multiple folds of these domains, relatively homogeneous crystal alignment parallel to the fold axes and microfolding of these domains in the zone of interaction between phenocrysts and matrix, including retrorotation of phenocrysts on short limbs of inequant folds. Trachyte dykes on Fraser Island, Queensland, Australia have a texture comprising crystal alignment, planar concentration domains (banding), two planar domains of crystal alignment interpreted to be conjugate shear zones. Phenocrysts influence the spacing and distribution of the domains and interacted with shear zones by undergoing small amounts of rotation. The shear zones overprinted a homogeneous crystal alignment during the last stage of flow before solidification as a result of dilatant granular interactions. Lava from

  7. Development of lava tubes in the light of observations at Mauna Ulu, Kilauea Volcano, Hawaii

    USGS Publications Warehouse

    Peterson, D.W.; Holcomb, R.T.; Tilling, R.I.; Christiansen, R.L.

    1994-01-01

    During the 1969-1974 Mauna Ulu eruption on Kilauea's upper east rift zone, lava tubes were observed to develop by four principal processes: (1) flat, rooted crusts grew across streams within confined channels; (2) overflows and spatter accreted to levees to build arched roofs across streams; (3) plates of solidified crust floating downstream coalesced to form a roof; and (4) pahoehoe lobes progressively extended, fed by networks of distributaries beneath a solidified crust. Still another tube-forming process operated when pahoehoe entered the ocean; large waves would abruptly chill a crust across the entire surface of a molten stream crossing through the surf zone. These littoral lava tubes formed abruptly, in contrast to subaerial tubes, which formed gradually. All tube-forming processes were favored by low to moderate volume-rates of flow for sustained periods of time. Tubes thereby became ubiquitous within the pahoehoe flows and distributed a very large proportionof the lava that was produced during this prolonged eruption. Tubes transport lava efficiently. Once formed, the roofs of tubes insulate the active streams within, allowing the lava to retain its fluidity for a longer time than if exposed directly to ambient air temperature. Thus the flows can travel greater distances and spread over wider areas. Even though supply rates during most of 1970-1974 were moderate, ranging from 1 to 5 m3/s, large tube systems conducted lava as far as the coast, 12-13 km distant, where they fed extensive pahoehoe fields on the coastal flats. Some flows entered the sea to build lava deltas and add new land to the island. The largest and most efficient tubes developed during periods of sustained extrusion, when new lava was being supplied at nearly constant rates. Tubes can play a major role in building volcanic edifices with gentle slopes because they can deliver a substantial fraction of lava erupted at low to moderate rates to sites far down the flank of a volcano. We

  8. 9. CRATER RIM DRIVE NEAR THURSTON LAVA TUBE. VIEW OF ...

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

    9. CRATER RIM DRIVE NEAR THURSTON LAVA TUBE. VIEW OF CRENELATED LAVA STONE GUARD WALL AND ROCK CUT OPPOSITE. NOTE CATTLE GUARD ACROSS ROAD PARTIALLY PAVED OVER. - Crater Rim Drive, Volcano, Hawaii County, HI

  9. White Sands, Carrizozo Lava Beds, NM

    NASA Technical Reports Server (NTRS)

    1973-01-01

    A truly remarkable view of White Sands and the nearby Carrizozo Lava Beds in southeast NM (33.5N, 106.5W). White Sands, site of the WW II atomic bomb development and testing facility and later post war nuclear weapons testing that can still be seen in the cleared circular patterns on the ground.

  10. Finding and utilizing lunar lava tubes

    NASA Astrophysics Data System (ADS)

    Kuck, David L.

    Horz describes the evidence for lava tubes associated with rills in lunar photo-imaging. These tubes have terrestrial counterparts as described by Billings, et al., and Gillet. The widths of these tubes range from 10s to 100s of meters. Their roof thickness are at least 0.125 to 0.25 times their widths and stand unsupported on the Moon. To confine one atmosphere of internal pressure, static roof thickness must be at least 16 m. Favorable locations of lava tubes may be surveyed using roving gravity meters on Doodle Bugs, which consist of platforms containing equipment for communication with Earth-based control stations. The stable -20 C temperature of the lava tubes should provide a workable habitat environment. The greater than 16 m of basalt in the roof should give adequate radiation and impact protection. Typically, after clearing entries and grading ramps, habitats might be placed in tubes and inflated. Later, larger habitats might be built by enclosing tube sections with compacted-regolith dams. The interior can then be sealed to hold an atmosphere. The huge lava tubes inferred from the photographs are capable of providing habitats hundreds of meters wide, in lengths of kilometers.

  11. Toothpaste lava: Characteristics and origin of a lava structural type transitional between pahoehoe and aa

    NASA Astrophysics Data System (ADS)

    Rowland, Scott K.; Walker, George P. L.

    1987-08-01

    Toothpaste lava, an important basalt structural type which illustrates the transition from pahoehoe to aa, is particularly well displayed on the 1960 Kapoho lava of Kilauea Volcano. Its transitional features stem from a viscosity higher than that of pahoehoe and a rate of flow slower than that of aa. Viscosity can be quantified by the limited settling of olivine phenocrysts and rate of flow by field observations related to the low-angle slope on which the lava flowed. Much can be learned about the viscosity, rheologic condition, and flow velocity of lavas long after solidification by analyses of their structural characteristics, and it is possible to make at least a semiquantitative assessment of the numerical values of these parameters.

  12. Earthen barriers to control lava flows in the 2001 eruption of Mt. Etna

    NASA Astrophysics Data System (ADS)

    Barberi, F.; Brondi, F.; Carapezza, M. L.; Cavarra, L.; Murgia, C.

    2003-04-01

    Preceded by four days of intense seismicity and marked ground deformation, a new eruption of Mt. Etna started on 17 July and lasted until 9 August 2001. It produced lava emission and strombolian and phreatomagmatic activity from four different main vents located on a complex fracture system extending from the southeast summit cone for about 4.5 km southwards, from 3000 to 2100 m elevation (a.s.l.). The lava emitted from the lowest vent cut up an important road on the volcano and destroyed other rural roads and a few isolated country houses. Its front descended southwards to about 4 km distance from the villages of Nicolosi and Belpasso. A plan of intervention, including diversion and retaining barriers and possibly lava flow interruption, was prepared but not activated because the flow front stopped as a consequence of a decrease in the effusion rate. Extensive interventions were carried out in order to protect some important tourist facilities of the Sapienza and Mts. Silvestri zones (1900 m elevation) from being destroyed by the lava emitted from vents located at 2700 m and 2550 m elevation. Thirteen earthen barriers (with a maximum length of 370 m, height of 10-12 m, base width of 15 m and volume of 25 000 m 3) were built to divert the lava flow away from the facilities towards a path implying considerably less damage. Most of the barriers were oriented diagonally (110-135°) to the direction of the flow. They were made of loose material excavated nearby and worked very nicely, resisting the thrust of the lava without any difficulty. After the interventions carried out on Mt. Etna in 1983 and in 1991-1992, those of 2001 confirm that earthen barriers can be very effective in controlling lava flows.

  13. Monitoring eruptive activity at Mount St. Helens with TIR image data

    USGS Publications Warehouse

    Vaughan, R.G.; Hook, S.J.; Ramsey, M.S.; Realmuto, V.J.; Schneider, D.J.

    2005-01-01

    Thermal infrared (TIR) data from the MASTER airborne imaging spectrometer were acquired over Mount St. Helens in Sept and Oct, 2004, before and after the onset of recent eruptive activity. Pre-eruption data showed no measurable increase in surface temperatures before the first phreatic eruption on Oct 1. MASTER data acquired during the initial eruptive episode on Oct 14 showed maximum temperatures of ???330??C and TIR data acquired concurrently from a Forward Looking Infrared (FLIR) camera showed maximum temperatures ???675??C, in narrow (???1-m) fractures of molten rock on a new resurgent dome. MASTER and FLIR thermal flux calculations indicated a radiative cooling rate of ???714 J/m2/S over the new dome, corresponding to a radiant power of ???24 MW. MASTER data indicated the new dome was dacitic in composition, and digital elevation data derived from LIDAR acquired concurrently with MASTER showed that the dome growth correlated with the areas of elevated temperatures. Low SO2 concentrations in the plume combined with sub-optimal viewing conditions prohibited quantitative measurement of plume SO2. The results demonstrate that airborne TIR data can provide information on the temperature of both the surface and plume and the composition of new lava during eruptive episodes. Given sufficient resources, the airborne instrumentation could be deployed rapidly to a newly-awakening volcano and provide a means for remote volcano monitoring. Copyright 2005 by the American Geophysical Union.

  14. Monitoring Eruptive Activity at Mount St. Helens with TIR Image Data

    NASA Technical Reports Server (NTRS)

    Vaughan, R. G.; Hook, S. J.; Ramsey, M. S.; Realmuto, V. J.; Schneider, D. J.

    2005-01-01

    Thermal infrared (TIR) data from the MASTER airborne imaging spectrometer were acquired over Mount St. Helens in Sept and Oct, 2004, before and after the onset of recent eruptive activity. Pre-eruption data showed no measurable increase in surface temperatures before the first phreatic eruption on Oct 1. MASTER data acquired during the initial eruptive episode on Oct 14 showed maximum temperatures of similar to approximately 330 C and TIR data acquired concurrently from a Forward Looking Infrared (FLIR) camera showed maximum temperatures similar to approximately 675 C, in narrow (approximately 1-m) fractures of molten rock on a new resurgent dome. MASTER and FLIR thermal flux calculations indicated a radiative cooling rate of approximately 714 J/m(exp 2)/s over the new dome, corresponding to a radiant power of approximately 24 MW. MASTER data indicated the new dome was dacitic in composition, and digital elevation data derived from LIDAR acquired concurrently with MASTER showed that the dome growth correlated with the areas of elevated temperatures. Low SO2 concentrations in the plume combined with sub-optimal viewing conditions prohibited quantitative measurement of plume SO2. The results demonstrate that airborne TIR data can provide information on the temperature of both the surface and plume and the composition of new lava during eruptive episodes. Given sufficient resources, the airborne instrumentation could be deployed rapidly to a newly-awakening volcano and provide a means for remote volcano monitoring.

  15. Lava Flow Mapping and Change Detection in the Mt. Etna Volcano Between 2009-2012 Using Hyperion Hyperspectral Imagery

    NASA Astrophysics Data System (ADS)

    Karagiannopoulou, Catherine; Sykioti, Olga; Parcharidis, Issaak Briole, Pierre

    2016-08-01

    Mt. Etna is a young composite strato-volcano and one of the most active volcanoes in the world. Eruptions occur almost every year with a persistent degassing activity at the summit craters. In the last 100 years it has produced in average 107m3 of new lava per year. The main goal of our work is to detect land cover changes, including different lava flows, over the volcano that occurred between 2009 and 2012 using hyperspectral imagery (EO-1 Hyperion). For this purpose, we separated the volcano into three main land cover types: dense vegetation, urban and semi-urban areas and bare lava areas. For each area, a change detection map was produced. For the bare lava areas, two classification maps were produced based on (i) reflectance differences and (ii) chronology as proposed in bibliography. Results have shown changes in all three land cover types. In particular, for the bare lava areas, the most significant lava changes are observed in the northern and central part of the volcano, where several lava flows occurred during the 3-year study period.

  16. How voluminous rhyolite lavas mimic rheomorphic ignimbrites: Eruptive style, emplacement conditions, and formation of tuff-like textures

    NASA Astrophysics Data System (ADS)

    Manley, Curtis R.

    1995-04-01

    Silicic lavas of large volume and relatively great areal extent are not uncommon in association with the tracks of mantle plume hotspots across the continents. These units are commonly eroded and/or poorly exposed, and their interpretation as lavas has been controversial. The morphology of a 15 km-3 calc-alkalic rhyolitic unit (75 to 77 wt% SiO2) on the Owyhee Plateau of southwestern Idaho shows that it is a true lava flow emplaced by effusion. The eruption tapped a zoned magma chamber with a small volume of nearly aphyric magma underlain by a much larger volume of less-evolved, crystal-rich magma. Magmatic temperatures were about 830 ° C and H2O contents were about 2 to 2.75 wt%. Eruptive activity first involved explosive venting of the nearly aphyric magma, followed by effusion of the crystal-rich magma. Movement of the lava over and around the tephra deposits formed large, discrete lava lobes; one flow lobe reached 9 km from the vent. Though the unit is a true lava flow, a diverse suite of fragmental textures, including rock that closely resembles welded tuff, formed by lava flow processes during the time the flow was active.

  17. Fiber-optic gyro location of dome azimuth

    NASA Astrophysics Data System (ADS)

    Kuehne, John W.

    2016-07-01

    The 2.1-m Otto Struve Telescope, world's second largest in 1939, today has modern motion control and superb tracking, yet the 19-m-diameter Art Deco dome has resisted many attempts to record its azimuth electronically. Demonstrated in January 2016, a small tactical-grade fiber-optic gyro located anywhere on the rotating structure, aided by a few fiducial points to zero gyro drift, adequately locates the azimuth. The cost of a gyro is practically independent of dome size, offering an economical solution for large domes that cannot be easily encoded with conventional systems. The 100-Hz sampling is capable of revealing anomalies in the rotation rate, valuable for preventive maintenance on any dome. I describe software methods and time series analysis to integrate angular velocity to dome azimuth; transformation of telescope hour angle and declination into required dome azimuth, using a formula that accounts for a cross-axis mount inside an offset dome; and test results.

  18. Deformation associated with the extrusion of a dome at Galeras volcano, Colombia, 1990 1991

    NASA Astrophysics Data System (ADS)

    Ordón˜ez V, Milton I.; Rey G, Carlos A.

    1997-05-01

    During 1989-1992, two electronic tilt meters named Cráter and Peladitos, and a short level line named Las Piedras, were used for monitoring Galeras volcano. The two tilt meters detected considerable changes of uplift mainly from June to November 1991. The Cráter station showed cumulative values of more than 600 microradians, while the Peladitos station exhibited values of more than 100 microradians. The short level line showed inflationary tilt of more than 20 microradians in 1989. This behavior was related to increases in the daily occurrence of long-period seismic events during July-November 1991 caused by the rise and extrusion of a lava dome, which was subsequently destroyed in July 1992. At the end of 1990, the deformation source was located at a depth of 2-3 km. By December 1991, the source had migrated to less than 500 m in depth. The magma ascent rate was 1-4 m/day during this period. The dome emplaced in the crater had a volume between 300,000 to 400,000 m 3. Using a hydrodynamic model and the tilt changes registered by the Peladitos station, the volume of the magma body is estimated at approximately 2.8 × 10 6 m 3.

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

    NASA Technical Reports Server (NTRS)

    Allen, Carlton C.; Oehler, Dorothy

    2010-01-01

    Mud volcanoes are mounds formed by low temperature slurries of gas, liquid, sediments and rock that erupt to the surface from depths of meters to kilometers. They are common on Earth, with estimates of thousands onshore and tens of thousands offshore. Mud volcanoes occur in basins with rapidly-deposited accumulations of fine-grained sediments. Such settings are ideal for concentration and preservation of organic materials, and mud volcanoes typically occur in sedimentary basins that are rich in organic biosignatures. Domes and cones, cited as possible mud volcanoes by previous authors, are common on the northern plains of Mars. Our analysis of selected regions in southern Acidalia Planitia has revealed over 18,000 such features, and we estimate that more than 40,000 occur across the area. These domes and cones strongly resemble terrestrial mud volcanoes in size, shape, morphology, associated flow structures and geologic setting. Geologic and mineralogic arguments rule out alternative formation mechanisms involving lava, ice and impacts. We are studying terrestrial mud volcanoes from onshore and submarine locations. The largest concentration of onshore features is in Azerbaijan, near the western edge of the Caspian Sea. These features are typically hundreds of meters to several kilometers in diameter, and tens to hundreds of meters in height. Satellite images show spatial densities of 20 to 40 eruptive centers per 1000 square km. Many of the features remain active, and fresh mud flows as long as several kilometers are common. A large field of submarine mud volcanoes is located in the Gulf of Cadiz, off the Atlantic coasts of Morocco and Spain. High-resolution sonar bathymetry reveals numerous km-scale mud volcanoes, hundreds of meters in height. Seismic profiles demonstrate that the mud erupts from depths of several hundred meters. These submarine mud volcanoes are the closest morphologic analogs yet found to the features in Acidalia Planitia. We are also conducting

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

    NASA Astrophysics Data System (ADS)

    Allen, C.; Oehler, D.

    2010-12-01

    Mud volcanoes are mounds formed by low temperature slurries of gas, liquid, sediments and rock that erupt to the surface from depths of meters to kilometers. They are common on Earth, with estimates of thousands onshore and tens of thousands offshore. Mud volcanoes occur in basins with rapidly-deposited accumulations of fine-grained sediments. Such settings are ideal for concentration and preservation of organic materials, and mud volcanoes typically occur in sedimentary basins that are rich in organic biosignatures. Domes and cones, cited as possible mud volcanoes by previous authors, are common on the northern plains of Mars. Our analysis of selected regions in southern Acidalia Planitia has revealed over 18,000 such features, and we estimate that more than 40,000 occur across the area. These domes and cones strongly resemble terrestrial mud volcanoes in size, shape, morphology, associated flow structures and geologic setting. Geologic and mineralogic arguments rule out alternative formation mechanisms involving lava, ice and impacts. We are studying terrestrial mud volcanoes from onshore and submarine locations. The largest concentration of onshore features is in Azerbaijan, near the western edge of the Caspian Sea. These features are typically hundreds of meters to several kilometers in diameter, and tens to hundreds of meters in height. Satellite images show spatial densities of 20 to 40 eruptive centers per 1000 km2. Many of the features remain active, and fresh mud flows as long as several kilometers are common. A large field of submarine mud volcanoes is located in the Gulf of Cadiz, off the Atlantic coasts of Morocco and Spain. High-resolution sonar bathymetry reveals numerous km-scale mud volcanoes, hundreds of meters in height. Seismic profiles demonstrate that the mud erupts from depths of several hundred meters. These submarine mud volcanoes are the closest morphologic analogs yet found to the features in Acidalia Planitia. We are also conducting

  1. Crystallization Processes and Magma Chamber Dynamics at the Mount Erebus Volcano Lava Lake: The Mineralogic Message

    NASA Astrophysics Data System (ADS)

    Kelly, P. J.; Kyle, P. R.; Dunbar, N. W.

    2006-12-01

    Mount Erebus volcano, Antarctica, hosts a persistently convecting and degassing lake of crystal-rich (30-40 vol.% phenocrysts) phonolite magma, providing a direct view into an active, stable, upper-level magma chamber. Mineral phases in lava bombs ejected by small strombolian eruptions from the lava lake between 1972 and 2004 were examined. Detailed compositional profiles of Ti-magnetite and large (up to 10 cm) anorthoclase feldspar phenocrysts were obtained by electron microprobe (EMP). The EMP data provide insight into the controls on crystallization in the lava lake/shallow magmatic system as well as the processes occurring in the magma chamber. Ti-magnetite are uniform and unzoned. The anorthoclase are complexly compositionally zoned over a restricted range (An10.3-22.9Ab62.8-68.1Or11.4-27.2) and contain abundant melt inclusions (up to ~30 vol. %). Coupled, inverse variations of An and Or account for ~96% of major element compositional variability and independent Ab variations account for ~4%. The anorthoclase compositions and textures suggest crystallization proceeds at low degrees of effective undercooling and is controlled by decompression-induced degassing of water. Unlike microlites that form during a single episode of ascent and eruption, the anorthoclase phenocrysts record multiple episodes of decompression and rim growth due to shallow convection in the lava lake under variable PH2O conditions. Crystals contained within a single lava bomb do not have shared crystallization histories, suggesting that differential movement of crystals and melt occurs within the magma chamber and that lava bombs are a mechanical assembly of crystals brought together a short time before or during an eruption. Large temperature variations at the surface of the lava lake (~400°C) are not reflected in the crystal compositions. Apparently, the kinetics of mineral growth are too sluggish to record the transient cooling (estimated to be ~20 mins.) experienced by crystals at the

  2. Shallowly driven fluctuations in lava lake outgassing (gas pistoning), Kīlauea Volcano

    NASA Astrophysics Data System (ADS)

    Patrick, Matthew R.; Orr, Tim; Sutton, A. J.; Lev, Einat; Thelen, Wes; Fee, David

    2016-01-01

    Lava lakes provide ideal venues for directly observing and understanding the nature of outgassing in basaltic magmatic systems. Kīlauea Volcano's summit lava lake has persisted for several years, during which seismic and infrasonic tremor amplitudes have exhibited episodic behavior associated with a rise and fall of the lava surface (;gas pistoning;). Since 2010, the outgassing regime of the lake has been tied to the presence or absence of gas pistoning. During normal behavior (no gas pistoning), the lake is in a ;spattering; regime, consisting of higher tremor amplitudes and gas emissions. In comparison, gas piston events are associated with an abrupt rise in lava level (up to 20 m), during which the lake enters a ;non-spattering; regime with greatly decreased tremor and gas emissions. We study this episodic behavior using long-term multidisciplinary monitoring of the lake, including seismicity, infrasound, gas emission and geochemistry, and time-lapse camera observations. The non-spattering regime (i.e. rise phase of a gas piston cycle) reflects gas bubbles accumulating near the top of the lake, perhaps as a shallow foam, while spattering regimes represent more efficient decoupling of gas from the lake. We speculate that the gas pistoning might be controlled by time-varying porosity and/or permeability in the upper portions of the lava lake, which may modulate foam formation and collapse. Competing models for gas pistoning, such as deeply sourced gas slugs, or dynamic pressure balances, are not consistent with our observations. Unlike other lava lakes which have cyclic behavior that is thought to be controlled by deeply sourced processes, external to the lake itself, we show an example of lava lake fluctuations driven by cycles of activity at shallow depth and close to the lake's surface. These observations highlight the complex and unsteady nature of outgassing from basaltic magmatic systems.

  3. Sensibility analysis of VORIS lava-flow simulations: application to Nyamulagira volcano, Democratic Republic of Congo

    NASA Astrophysics Data System (ADS)

    Syavulisembo, A. M.; Havenith, H.-B.; Smets, B.; d'Oreye, N.; Marti, J.

    2015-03-01

    Assessment and management of volcanic risk are important scientific, economic, and political issues, especially in densely populated areas threatened by volcanoes. The Virunga area in the Democratic Republic of Congo, with over 1 million inhabitants, has to cope permanently with the threat posed by the active Nyamulagira and Nyiragongo volcanoes. During the past century, Nyamulagira erupted at intervals of 1-4 years - mostly in the form of lava flows - at least 30 times. Its summit and flank eruptions lasted for periods of a few days up to more than two years, and produced lava flows sometimes reaching distances of over 20 km from the volcano, thereby affecting very large areas and having a serious impact on the region of Virunga. In order to identify a useful tool for lava flow hazard assessment at the Goma Volcano Observatory (GVO), we tested VORIS 2.0.1 (Felpeto et al., 2007), a freely available software (http://www.gvb-csic.es) based on a probabilistic model that considers topography as the main parameter controlling lava flow propagation. We tested different Digital Elevation Models (DEM) - SRTM1, SRTM3, and ASTER GDEM - to analyze the sensibility of the input parameters of VORIS 2.0.1 in simulation of recent historical lava-flow for which the pre-eruption topography is known. The results obtained show that VORIS 2.0.1 is a quick, easy-to-use tool for simulating lava-flow eruptions and replicates to a high degree of accuracy the eruptions tested. In practice, these results will be used by GVO to calibrate VORIS model for lava flow path forecasting during new eruptions, hence contributing to a better volcanic crisis management.

  4. Generation of pyroclastic flows by explosive interaction of lava flows with ice/water-saturated substrate

    NASA Astrophysics Data System (ADS)

    Belousov, Alexander; Behncke, Boris; Belousova, Marina

    2011-04-01

    We describe a new type of secondary rootless phreatomagmatic explosions observed at active lava flows at volcanoes Klyuchevskoy (Russia) and Etna (Italy). The explosions occurred at considerable (up to 5 km) distances from primary volcanic vents, generally at steep (15-35°) slopes, and in places where incandescent basaltic or basaltic-andesitic lava propagated over ice/water-saturated substrate. The explosions produced high (up to 7 km) vertical ash/steam-laden clouds as well as pyroclastic flows that traveled up to 2 km downslope. Individual lobes of the pyroclastic flow deposits were up to 2 m thick, had steep lateral margins, and were composed of angular to subrounded bomb-size clasts in a poorly sorted ash-lapilli matrix. Character of the juvenile rock clasts in the pyroclastic flows (poorly vesiculated with chilled and fractured cauliflower outer surfaces) indicated their origin by explosive fragmentation of lava due to contact with external water. Non-juvenile rocks derived from the substrate of the lava flows comprised up to 75% in some of the pyroclastic flow deposits. We suggest a model where gradual heating of a water-saturated substrate under the advancing lava flow elevates pore pressure and thus reduces basal friction (in the case of frozen substrate water is initially formed by thawing of the substrate along the contact with lava). On steep slope this leads to gravitational instability and sliding of a part of the active lava flow and water-saturated substrate. The sliding lava and substrate disintegrate and intermix, triggering explosive "fuel-coolant" type interaction that produces large volume of fine-grained clastic material. Relatively cold steam-laden cloud of the phreatomagmatic explosion has limited capacity to transport upward the produced clastic material, thus part of it descends downslope in the form of pyroclastic flow. Similar explosive events were described for active lava flows of Llaima (Chile), Pavlof (Alaska), and Hekla (Iceland

  5. Trace-element analyses of core samples from the 1967-1988 drillings of Kilauea Iki lava lake, Hawaii

    USGS Publications Warehouse

    Helz, Rosalind Tuthill

    2012-01-01

    This report presents previously unpublished analyses of trace elements in drill core samples from Kilauea Iki lava lake and from the 1959 eruption that fed the lava lake. The two types of data presented were obtained by instrumental neutron-activation analysis (INAA) and energy-dispersive X-ray fluorescence analysis (EDXRF). The analyses were performed in U.S. Geological Survey (USGS) laboratories from 1989 to 1994. This report contains 93 INAA analyses on 84 samples and 68 EDXRF analyses on 68 samples. The purpose of the study was to document trace-element variation during chemical differentiation, especially during the closed-system differentiation of Kilauea Iki lava lake.

  6. Geochemistry of Axial seamount lavas: Magmatic relationship between the Cobb hotspot and the Juan de Fuca Ridge

    SciTech Connect

    Rhodes, J.M.; Morgan, C.; Lilas, R.A. )

    1990-08-10

    Axial seamount, located along the central portion of the Juan de Fuca Ridge axis and at the eastern end of the Cobb-Eickelberg seamount chain, is the current center of the Cobb hotspot. Lava chemistry and bathymetry indicate that Axial seamount is a discrete volcanic unit, with a more productive shallow magmatic plumbing system separate from the adjacent ridge segments. Despite this classic association of spreading center and hotspot volcanic activity, there is no evidence in the lavas for geochemical or isotopic enrichment typical of hotspot or mantle plume activity. The differences in composition between the Axial seamount lavas and the Juan de Fuca Ridge lavas are attributed to melting processes rather than to any fundamental differences in their mantle source compositions. The higher magma production rates, higher Sr, and lower silica saturation in the seamount lavas relative to the ridge lavas are thought to be a consequence of melt initiation at greater depths. The melting column producing the seamount lavas is thought to be initiated in the stability field of spinel peridotite, whereas the ridge lavas are produced from a melting column initiated at shallower levels, possibly within or close to the stability field of plagioclase peridotite. Implicit in this interpretation is the conclusion that the Juan de Fuca Ridge lavas, and by analogy most MORB, are generated at shallow mantle levels, mostly within the stability field of plagioclase peridotite. This interpretation also requires that for the upwelling mantle to intersect the solidus at different depths, the mantle supplying Axial seamount must be hotter than the rest of the Juan de Fuca Ridge. Axial seamount, therefore, reflects a thermal anomaly in the mantle, rather than a geochemically enriched ocean island basalt type mantle plume.

  7. Modelling the emplacement of compound lava flows

    NASA Astrophysics Data System (ADS)

    Blake, S.; Bruno, B. C.

    2000-12-01

    The physical variables controlling crust-dominated lava flow have been investigated using laboratory experiments in which molten polyglycol wax was extruded from a point source on to a horizontal plane under cold water. The wax initially spread axisymmetrically and a crust of solid wax grew. Eventually wax broke out from the flow's periphery, sending out a flow lobe which in turn cooled and produced another breakout. The process repeated itself many times, building a 'compound lava'. The time for the first breakout to form correlates well with the theoretically predicted time ( tc) required for cooling to form a crust thick enough for its strength to limit the flow's spreading rate. This time is proportional to the product of effusion rate ( Q) and initial magma viscosity ( μ) and inversely proportional to the square of the crust strength at the flow front. The number of flow units and the apparent fractal dimension of the flow perimeter increase with time normalised by tc. Our model illuminates the physical basis for the observation by Walker [G.P.L. Walker, Bull. Volcanol. 35 (1972) 579-590] that compound lava flows form by slow effusion of low viscosity magma, whereas faster effusion and higher viscosity favour lavas with fewer flow units. Because compound flows require t≫ tc, and given that tc∝ Qμ and the relationship between volume and effusion rate is V= Qt, simple and compound lava flows are predicted to fall in separate fields on a graph of μ against V/ Q2, all else being equal. Compound flows plot at small values of μ and large values of V/ Q2, with the position of the simple/compound boundary defined by field data implying a crust strength of order 10 4 Pa for basaltic to intermediate lavas. Whether a flow remains as a simple flow or matures into a compound flow field depends on the combined effect of viscosity, eruption rate and eruption duration (and hence volume) and these parameters need to be taken in to account when using morphology to infer

  8. Remote Control of the CFHT Dome Shutter

    NASA Astrophysics Data System (ADS)

    Look, Ivan; Roberts, Larry; Vermeulen, Tom; Taroma, Ralph; Matsushige, Grant

    2011-03-01

    Several years ago CFHT proposed developing a Remote Observing Environment aimed at producing Science Observations at their Facility on Mauna Kea from their Headquarters in Waimea, HI. This Remote Observing Project commonly referred to as OAP (Observatory Automation Project) was completed at the end of January 2011 and has been providing the majority of Science Data since. My poster will attempt to provide Design Information on the Dome Shutter, which is both Controlled and Monitored Remotely from Waimea. The Dome Shutter Control System incorporates an upgraded Allen-Bradley PLC processor (SLC 5/05), which provides Remote Operation and Monitoring of the existing System. Several earlier upgrade projects were integrated to provide improvement to the Shutter System such as PLC Control, System Feedback, and Safety Features. This particular upgrade provides Remote capability, CFHT developed Control GUI, and Remote monitoring that promise to deliver a more versatile, visual, and safer Shutter Operation. The Dome Shutter Control System provides three modes of Operation namely; Remote, Integration, and Local. The Control GUI is used to operate the Shutter remotely. Integration mode is provided to develop PLC software code and is performed by connecting a Laptop directly to the Shutter Control Panel. Local mode is retained to provide Remote Lockout (No Remote Control), which allows Shutter control ONLY via the existing Electrical Panel. This mode is primarily intended for Shutter maintenance and troubleshooting. The Dome Shutter remains the first Line-of-Defense for Telescope protection due to inclement weather and so special attention was considered during Remote development. The Shutter has been equipped with an Autonomous Shutdown sequence in the event of Power or Network failure. If Loss of HELCO Power or Start-up of our Stand-by Diesel Generator is detected; a planned timing sequence will Close the Shutter Automatically. Likewise, an internal CFHT Network heartbeat was

  9. MROI Array telescopes: the relocatable enclosure domes

    NASA Astrophysics Data System (ADS)

    Marchiori, G.; Busatta, A.; Payne, I.

    2016-07-01

    The MROI - Magdalena Ridge Interferometer is a project which comprises an array of up to 10 1.4m diameter mirror telescopes arranged in a "Y" configuration. Each of these telescopes will be housed inside a Unit Telescope Enclosure (UTE) which are relocatable onto any of 28 stations. EIE GROUP Srl, Venice - Italy, was awarded the contract for the design, the construction and the erection on site of the MROI by the New Mexico Institute of Mining and Technology. The close-pack array of the MROI - including all 10 telescopes, several of which are at a relative distance of less than 8m center to center from each other - necessitated an original design for the Unit Telescope Enclosure (UTE). This innovative design enclosure incorporates a unique dome/observing aperture system to be able to operate in the harsh environmental conditions encountered at an altitude of 10,460ft (3,188m). The main characteristics of this Relocatable Enclosure Dome are: a Light insulated Steel Structure with a dome made of composites materials (e.g. glass/carbon fibers, sandwich panels etc.), an aperture motorized system for observation, a series of louvers for ventilation, a series of electrical and plants installations and relevant auxiliary equipment. The first Enclosure Dome is now under construction and the completion of the mounting on site id envisaged by the end of 2016. The relocation system utilizes a modified reachstacker (a transporter used to handle freight containers) capable of maneuvering between and around the enclosures, capable of lifting the combined weight of the enclosure with the telescope (30tons), with minimal impacts due to vibrations.

  10. Underwater Calibration of Dome Port Pressure Housings

    NASA Astrophysics Data System (ADS)

    Nocerino, E.; Menna, F.; Fassi, F.; Remondino, F.

    2016-03-01

    Underwater photogrammetry using consumer grade photographic equipment can be feasible for different applications, e.g. archaeology, biology, industrial inspections, etc. The use of a camera underwater can be very different from its terrestrial use due to the optical phenomena involved. The presence of the water and camera pressure housing in front of the camera act as additional optical elements. Spherical dome ports are difficult to manufacture and consequently expensive but at the same time they are the most useful for underwater photogrammetry as they keep the main geometric characteristics of the lens unchanged. Nevertheless, the manufacturing and alignment of dome port pressure housing components can be the source of unexpected changes of radial and decentring distortion, source of systematic errors that can influence the final 3D measurements. The paper provides a brief introduction of underwater optical phenomena involved in underwater photography, then presents the main differences between flat and dome ports to finally discuss the effect of manufacturing on 3D measurements in two case studies.

  11. Fabric and texture at Siple Dome, Antarctica

    USGS Publications Warehouse

    Diprinzio, C.L.; Wilen, L.A.; Alley, R.B.; Fitzpatrick, J.J.; Spencer, M.K.; Gow, A.J.

    2005-01-01

    Preferred c-axis orientations are present in the firn at Siple Dome, West Antarctica, and recrystallization begins as shallow as 200 m depth in ice below -20??C, based on digital analysis of c-axis fabrics, grain-sizes and other characteristics of 52 vertical thin sections prepared in the field from the kilometer-long Siple Dome ice core. The shallowest section analyzed, from 22 m, shows clustering of c axes toward the vertical. By 200 m depth, girdle fabric and other features of recrystallized ice are evident in layers (or regions), separated by layers (regions) of typically finer-grained ice lacking evidence of recrystallization. Ice from about 700-780 m depth, which was deposited during the last ice age, is especially fine-grained, with strongly vertical c axes, but deeper ice shows much larger crystals and strong evidence of recrystallization. Azimuthal asymmetry of some c-axis fabrics, trends in grain-size, and other indicators reveal additional information on processes and history of ice flow at Siple Dome.

  12. Dome corrective osteotomy for cubitus varus deformity.

    PubMed

    Tien, Y C; Chih, H W; Lin, G T; Lin, S Y

    2000-11-01

    Between 1994 and 1998, 15 patients had corrective dome-shaped osteotomy of the humerus for posttraumatic cubitus varus deformity. Thirteen patients had surgery before puberty and two patients had surgery after puberty. In the prepuberty group, all the osteotomies were done by a posterior approach with triceps muscle splitting, and cross pins were used to fix the osteotomy. In the postpuberty group, the osteotomies were done by a posterior approach with olecranon osteotomy, and reconstructive plates were used for fixation. The average followup was 2 years and 4 months. Preoperative carrying angle ranged from 19 degrees to 31 degrees varus (average, 26.2 degrees) and postoperative carrying angle ranged from 7 degrees to 15 degrees valgus (average, 10.7 degrees). No loss of correction was observed and all osteotomies united. The preoperative and postoperative differences of the lateral condylar prominence index ranged from -67% to +6% (average, -30.1%). After reviewing these cases, a dome-shaped osteotomy was found to have the following advantages for correction of cubitus varus deformity: the osteotomy site is more stable than a lateral closing wedge osteotomy for maintaining the correction obtained; the domed osteotomy avoids having the lateral condyle becoming prominent; and the posterior scar is more cosmetically acceptable than the lateral scar in the lateral closing wedge osteotomy.

  13. Recent Flood Volcanism on Mars: Implications for Climate Change, Layered Deposits, and Lava-Water Interactions

    NASA Astrophysics Data System (ADS)

    Keszthelyi, L.; McEwen, A.

    2001-05-01

    . There is evidence from MOC and MOLA that recent floods of both water and lava originated from Cerberus Rupes, a fracture system which has been active very recently (it cuts the young lavas). This may be the very best place on Mars to search for current geothermal activity. Keszthelyi et al. (2000) JGR 105, 15027-15049. Hartmann and Berman (2000) JGR, 105, 15011-15025. Thordarson and Self (1996) JVGR 74, 49-73. Keszthelyi and Thordarson, (2000) GSA Ann. Meet. Abst. #5293. McSween, et al. (2001), Nature 409, 487-490. Lanagan et al., (submitted) GRL.

  14. Retrograded eclogite xenoliths from mid-Tertiary potassic lavas along the southwest margin of the Colorado Plateau

    NASA Astrophysics Data System (ADS)

    Schroeder, T. J.; Riggs, N.; Ort, M. H.

    2010-12-01

    A suite of xenolith-bearing, alkalic volcanic rocks erupted in small domes and plugs along the southwest margin of the Colorado Plateau (current Transition Zone) in Arizona between 30 Ma and 22 Ma. The onset of volcanic activity slightly precedes the earliest phase of mid-Tertiary extension and metamorphic core complex denudation in western/southern Arizona (27-25 Ma), which occurred along detachment faults that dip gently beneath the CP margin. Lavas are highly potassic (up to 6% Wt. K2O) and rich in incompatible trace elements (Ba up to 1900 ppm and Sr up to 1250 ppm), suggesting an enriched mantle melting source. Xenoliths are dominantly eclogite and pyroxenite that have been slightly to completely retrograded to amphibolite assemblages. The most common xenolith mineral assemblage consists of: 1) omphacite that has been completely replaced by an irregular symplectite of cpx and low-Ca plagioclase, 2) garnet that is partially replaced and rimmed by a fine, lamellar symplectite of high-Ca plagioclase, pargasitic amphibole, and Fe-Ti oxides, 3) coarse pargasitic amphibole that has overgrown or partially replaced the cpx-plag symplectite, 4) rutile that has been partially replaced by ilmenite and magnetite, and 4) apatite, zircon, and other accessory minerals. Xenoliths contain evidence for melt interaction prior to entrainment, including plagioclase veins containing hercynite and hogbomite that are cut by sharp contacts with the host lava. Results of this and other studies suggest that these veins formed by reactions between the eclogite assemblage (likely including spinel) and a locally derived melt. However, textural relations and geochemical differences suggest that this melt was not the host melt that entrained the xenoliths. Pyroxene and garnet thermobarometry from this and other studies on the primary eclogitic assemblages indicate temperatures from 500 to 900C at 11 to 20 kb. Mineral chemistry analyses of amphibole, plagioclase, hornblende, and garnet in the

  15. Voluminous submarine lava flows from Hawaiian volcanoes

    SciTech Connect

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

    1988-05-01

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

  16. Cooling of Kilauea Iki lava lake

    SciTech Connect

    Hills, R.G.

    1982-02-01

    In 1959 Kilauea Iki erupted leaving a 110 to 120 m lake of molten lava in its crater. The resulting lava lake has provided a unique opportunity to study the cooling dynamics of a molten body and its associated hydrothermal system. Field measurements taken at Kilauea Iki indicate that the hydrothermal system above the cooling magma body goes through several stages, some of which are well modeled analytically. Field measurements also indicate that during most of the solidification period of the lake, cooling from above is controlled by 2-phase convection while conduction dominates the cooling of the lake from below. A summary of the field work related to the study of the cooling dynamics of Kilauea Iki is presented. Quantitative and qualitative cooling models for the lake are discussed.

  17. Flow direction determination of lava flows.

    NASA Technical Reports Server (NTRS)

    Smith, E. I.; Rhodes, R. C.

    1972-01-01

    The flow direction technique, previously applied to ash-flow sheets, can be used to determine direction of movement and locate eruptive centers for lava flows. The method provides statistically stronger and more consistent flow direction data for lava than ash-flow tuff. The accuracy and reliability of the technique was established on the porphyritic basaltic andesite of Mount Taylor, New Mexico, which erupted from a known center, the Mount Taylor Amphitheater. The technique was then applied to volcanic units with unknown sources: the John Kerr Peak Quartz Latite and mid-Tertiary andesite flows in the Mogollon Mountains, both in southwestern New Mexico. The flow direction technique indicated flow patterns and suggested source areas for each rock unit. In the Mogollon Mountains flow direction measurements were supported by independent directional criteria such as dips of cross beds, stratigraphic thickening, facies changes, and megascopic textures.-

  18. Nitrogen Fixation (Acetylene Reduction) Associated with Decaying Leaves of Pond Cypress (Taxodium distichum var. nutans) in a Natural and a Sewage-Enriched Cypress Dome

    PubMed Central

    Dierberg, Forrest E.; Brezonik, Patrick L.

    1981-01-01

    Surface litter from a natural and a sewage-enriched cypress dome in north-central Florida showed a pronounced seasonal pattern of nitrogenase (acetylene reduction) activity associated with seasonal leaf fall from deciduous trees in the domes. Samples of peat from cores indicated negligible nitrogenase activity below the surface layer. Integrating the monthly rates of nitrogen fixation (based on the theoretical molar ratio of 3:2 for C2H4/NH3) yielded 0.39 and 0.12 g of N/m2 per year fixed in the litter of the natural and sewage-enriched domes, respectively. The nitrogen fixed in the first 3 months after leaf fall in the natural dome represented about 14% of the nitrogen increment in the decomposing cypress leaves, but fixation contributed a negligible amount of nitrogen (<1%) to decomposing litter in the sewage-enriched dome. PMID:16345796

  19. Kilauea Iki lava lake experiment plans

    SciTech Connect

    Dunn, J.C.; Hills, R.G.

    1981-01-01

    Twelve experimental studies are proposed to complete field laboratory work at Kilauea Iki lava lake. Of these twelve experiments, eleven do not require the presence of melt. Some studies are designed to use proven techniques in order to expand our existing knowledge, while others are designed to test new concepts. Experiments are grouped into three main categories: geophysics, energy extraction, and drilling technology. Each experiment is described in terms of its location, purpose, background, configuration, operation, and feasibility.

  20. Flow and convective cooling in lava tubes

    NASA Astrophysics Data System (ADS)

    Sakimoto, S. E. H.; Zuber, M. T.

    1998-11-01

    Tube-fed basaltic lava flows with lengths ranging from 10 to 200 km are inferred to exhibit similar amounts of cooling. To explain the wide range of implied cooling rates, we consider forced convection as a dominant cooling process in lava tubes and present solutions that express mean temperature versus distance down the tube as a function of flow rate and flow cross section. Our models treat forced convective thermal losses in steady laminar flow through a lava tube with constant temperature walls and constant material properties. We explore the effects of different wall temperature and heat flux rate boundary conditions for circular tube and parallel plate flows over a range of tube sizes, plate spacings, eruption temperatures, and volume flow rates. Results show that nonlinear cooling rates over distance are characteristic of constant wall temperature for a piecewise parallel plate/circular tube model. This provides the best fit to temperature observations for Hawaiian tubes. Such a model may also provide an explanation for the very low (˜10°C) cooling observed in ˜10 km long Hawaii tube flows and inferred in longer ˜50 to 150 km tube-fed flows in Queensland. The forced convective cooling model may also explain similar flow morphologies for long tube-fed basaltic lava flows in a wide variety of locations, since small variations in eruption temperature or flow rate can accommodate the entire range of flow lengths and cooling rates considered. Our results are consistent with previous suggestions that long basaltic flows may be a reflection of low slopes, a particularly steady moderate eruption rate, and well-insulated flow, rather than of high discharge rates.

  1. Geothermometry of Kilauea Iki lava lake, Hawaii

    USGS Publications Warehouse

    Helz, R.T.; Thornber, C.R.

    1987-01-01

    Data on the variation of temperature with time and in space are essential to a complete understanding of the crystallization history of basaltic magma in Kilauea Iki lava lake. Methods used to determine temperatures in the lake have included direct, downhole thermocouple measurements and Fe-Ti oxide geothermometry. In addition, the temperature variations of MgO and CaO contents of glasses, as determined in melting experiments on appropriate Kilauean samples, have been calibrated for use as purely empirical geothermometers and are directly applicable to interstitial glasses in olivine-bearing core from Kilauea Iki. The uncertainty in inferred quenching temperatures is ??8-10?? C. Comparison of the three methods shows that (1) oxide and glass geothermometry give results that are consistent with each other and consistent with the petrography and relative position of samples, (2) downhole thermo-couple measurements are low in all but the earliest, shallowest holes because the deeper holes never completely recover to predrilling temperatures, (3) glass geothermometry provides the greatest detail on temperature profiles in the partially molten zone, much of which is otherwise inaccessible, and (4) all three methods are necessary to construct a complete temperature profile for any given drill hole. Application of glass-based geothermometry to partially molten drill core recovered in 1975-1981 reveals in great detail the variation of temperature, in both time and space, within the partially molten zone of Kilauea Iki lava lake. The geothermometers developed here are also potentially applicable to glassy samples from other Kilauea lava lakes and to rapidly quenched lava samples from eruptions of Kilauea and Mauna Loa. ?? 1987 Springer-Verlag.

  2. Modeling steam pressure under martian lava flows

    USGS Publications Warehouse

    Dundas, Colin M.; Keszthelyi, Laszlo P.

    2013-01-01

    Rootless cones on Mars are a valuable indicator of past interactions between lava and water. However, the details of the lava–water interactions are not fully understood, limiting the ability to use these features to infer new information about past water on Mars. We have developed a model for the pressurization of a dry layer of porous regolith by melting and boiling ground ice in the shallow subsurface. This model builds on previous models of lava cooling and melting of subsurface ice. We find that for reasonable regolith properties and ice depths of decimeters, explosive pressures can be reached. However, the energy stored within such lags is insufficient to excavate thick flows unless they draw steam from a broader region than the local eruption site. These results indicate that lag pressurization can drive rootless cone formation under favorable circumstances, but in other instances molten fuel–coolant interactions are probably required. We use the model results to consider a range of scenarios for rootless cone formation in Athabasca Valles. Pressure buildup by melting and boiling ice under a desiccated lag is possible in some locations, consistent with the expected distribution of ice implanted from atmospheric water vapor. However, it is uncertain whether such ice has existed in the vicinity of Athabasca Valles in recent history. Plausible alternative sources include surface snow or an aqueous flood shortly before the emplacement of the lava flow.

  3. The eruptive history of the Tequila volcanic field, western Mexico: ages, volumes, and relative proportions of lava types

    NASA Astrophysics Data System (ADS)

    Lewis-Kenedi, Catherine B.; Lange, Rebecca A.; Hall, Chris M.; Delgado-Granados, Hugo

    2005-06-01

    The eruptive history of the Tequila volcanic field (1600 km2) in the western Trans-Mexican Volcanic Belt is based on 40Ar/39Ar chronology and volume estimates for eruptive units younger than 1 Ma. Ages are reported for 49 volcanic units, including Volcán Tequila (an andesitic stratovolcano) and peripheral domes, flows, and scoria cones. Volumes of volcanic units ≤1 Ma were obtained with the aid of field mapping, ortho aerial photographs, digital elevation models (DEMs), and ArcGIS software. Between 1120 and 200 kyrs ago, a bimodal distribution of rhyolite (~35 km3) and high-Ti basalt (~39 km3) dominated the volcanic field. Between 685 and 225 kyrs ago, less than 3 km3 of andesite and dacite erupted from more than 15 isolated vents; these lavas are crystal-poor and show little evidence of storage in an upper crustal chamber. Approximately 200 kyr ago, ~31 km3 of andesite erupted to form the stratocone of Volcán Tequila. The phenocryst assemblage of these lavas suggests storage within a chamber at ~2 3 km depth. After a hiatus of ~110 kyrs, ~15 km3 of andesite erupted along the W and SE flanks of Volcán Tequila at ~90 ka, most likely from a second, discrete magma chamber located at ~5 6 km depth. The youngest volcanic feature (~60 ka) is the small andesitic volcano Cerro Tomasillo (~2 km3). Over the last 1 Myr, a total of 128±22 km3 of lava erupted in the Tequila volcanic field, leading to an average eruption rate of ~0.13 km3/kyr. This volume erupted over ~1600 km2, leading to an average lava accumulation rate of ~8 cm/kyr. The relative proportions of lava types are ~22 43% basalt, ~0.4 1% basaltic andesite, ~29 54% andesite, ~2 3% dacite, and ~18 40% rhyolite. On the basis of eruptive sequence, proportions of lava types, phenocryst assemblages, textures, and chemical composition, the lavas do not reflect the differentiation of a single (or only a few) parental liquids in a long-lived magma chamber. The rhyolites are geochemically diverse and were likely

  4. Geologic and hydrologic summary of salt domes in Gulf Coast region of Texas, Louisiana, Mississippi, and Alabama

    USGS Publications Warehouse

    Anderson, R. Ernest; Eargle, Dolan H.; Davis, Beth O.

    1973-01-01

    There are 263 known or suspected onshore salt domes in the Texas-Louisiana-Mississippi-Alabama portion of the Gulf Coast geosyncline. The top of the salt in 148 of them is probably deeper than desirable for a waste repository site, and 79 of those that are shallow enough are probably unavailable for a site because of present use by industry for gas storage or production of oil, salt, or sulfur. In this report we have compiled the available geologic and hydrologic background data pertinent to the evaluation of the remaining 36 known or suspected salt domes as potential sites for waste storage. There are three parts to this compilations: 1) summaries of the geology and hydrology of the salt-dome province as a whole; 2) summaries of the physiography, climate, geology, and hydrology of each of the five salt-dome basins that occur within the province; and 3) an appendix of background data for each of the 36 potentially acceptable domes. The distribution of salt domes in the province is genetically related to areas of relative subsidence that formed basins or depocenters within the Gulf Coast geosyncline. In some cases, as in northeast Texas and south Louisiana, the locations of individual domes or groups of domes are related to deep movement of salt along axial trends. The salt domes in the interior salt-dome subprovince are probably more structurally stable than those of the coastal subprovince because salt diapirism is inferred to have ceased around Miocene time in the interior but may still be active in parts of the coastal subprovince. Although the size and shape of many domes is unknown or can only be roughly approximated, each of the five basins in the province appears to contain potentially acceptable domes of adequate size for a repository. We recognize no pattern to the distribution of salt-dome size. Caprock thicknesses vary greatly within each salt-dome basin,and we recognize no pattern to the variations. Among the potentially acceptable domes, the depths to

  5. The Energy Dome. Social Studies Packet-Grades 4, 5, 6.

    ERIC Educational Resources Information Center

    National Science Teachers Association, Washington, DC.

    This teacher's guide contains a unit of study for teaching about energy in grades four, five, and six. The guide is self-contained and includes the fact sheets students need to work out the activity problems. The unit is organized around the theme of the domed athletic stadium. The students begin by surveying the energy it takes to travel from…

  6. The Preservation of Organic Matter and its Signatures at Experimental Lava Flow Interfaces: Implications for Mars

    NASA Astrophysics Data System (ADS)

    Junium, C. K.; Karson, J. A.; Kahan, T.

    2015-12-01

    The oxidizing nature of Martian soils suggests that the preservation of organic molecules or any direct evidence for life at the surface may not be possible. Future rover missions will need to focus on a variety localitions including those that provide the best possibility for the preservation of organic matter. Volcanic glass and basalt flow surfaces are favored environments for microbial colonization on Earth and this may have been similar on an early Mars. Trace metals and nutrients from easily weathered surface would have provided nutrients as well as substrates for chemolithoautotrophs. In regions of igneous activity, successive flows could overrun microbial communities, trapping potential organic signatures between flows. Here we present experimental evidence for the preservation of organic matter between lava flows and that flow interfaces may be excellent sites for exploratory efforts in the search for Martian biosignatures. We performed a series of experiments using the infrastructure of the Syracuse Lava Project that allows for natural-scale lava flows of up to several hundred kilograms. We subjected cyanobacterial organic matter to overrun by lava under a variety of conditions. In all cases organic matter was preserved between lava flows as chars on the overrun 'colonized" lava and as thin shiny carbon coatings on the overriding flow. The carbon coatings are likely the result of rapid heating and pyrolysis of organic matter that sears to the underside of the overriding lava. Controls yielded no positive signatures for organic matter. We also tested the degree to which the organic matter could be detected remotely using technologies that are found on the Mars Science Laboratory or planned for future missions. We employed elemental and stable isotopes analysis, and Raman spectroscopy. Elemental analysis demonstrated that organic carbon and nitrogen remain in the charred material and that the carbon and nitrogen isotopes of the chars do not deviate

  7. Measuring Io's Lava Eruption Temperatures with a Novel Infrared Detector and Digital Readout Circuit

    NASA Astrophysics Data System (ADS)

    Davies, Ashley; Gunapala, Sarath; Rafol, B., Sir; Soibel, Alexander; Ting, David Z.

    2016-10-01

    One method of determining lava eruption temperature of Io's dominant silicate lavas is by measuring radiant flux at two or more wavelengths and fitting a black-body thermal emission function. Only certain styles of volcanic activity are suitable, those where thermal emission is from a restricted range of surface temperatures close to eruption temperature. Such processes include [1] large lava fountains; [2] fountaining in lava lakes; and [3] lava tube skylights. Problems that must be overcome are (1) the cooling of the lava between data acquisitions at different wavelengths; (2) the unknown magnitude of thermal emission, which often led to detector saturation; and (3) thermal emission changing on a shorter timescale than the observation integration time. We can overcome these problems by using the HOT-BIRD detector [4] and an advanced digital readout circuit [5]. We have created an instrument model that allows different instrument parameters (including mirror diameter, number of signal splits, exposure duration, filter band pass, and optics transmissivity) to be tested so as to determine eruption detectability. We find that a short-wavelength infrared instrument on an Io flyby mission can achieve simultaneity of observations by splitting the incoming signal for all relevant eruption processes and obtain data fast enough to remove uncertainties in accurate determination of the highest lava surface temperatures exposed. Observations at 1 and 1.5 μm are sufficient to do this. Lava temperature determinations are also possible with a visible wavelength detector [3] so long as data at different wavelengths are obtained simultaneously and integration time is very short. This is especially important for examining the thermal emission from lava tube skylights [3] due to rapidly-changing viewing geometry during close flybys. References: [1] Davies et al., 2001, JGR, 106, 33079-33104. [2] Davies et al., 2011, GRL, 38, L21308. [3] Davies et al., 2016, Icarus, in press. [4

  8. Studies of Young Hawai'ian Lava Tubes: Implications for Planetary Habitability and Human Exploration

    NASA Technical Reports Server (NTRS)

    McAdam, Amy; Bleacher, Jacob; Young, Kelsey; Johnson, Sarah Stewart; Needham, Debra; Schmerr, Nicholas; Shiro, Brian; Garry, Brent; Whelley, Patrick; Knudson, Christine; Andrejkovicova, Slavka

    2017-01-01

    Habitability: Subsurface environments may preserve records of habitability or biosignatures, with more stable environmental conditions compared to surface (e.g., smaller variations in temperature and humidity) and reduced exposure to radiation; Lava tubes are expected on Mars, and candidates are observed from orbit; Few detailed studies of microbial populations in terrestrial lava caves; Also contain a variety of secondary minerals; Microbial activity may play a role in mineral formation or be preserved in these minerals; Minerals can provide insight into fluids (e.g., pH, temperature).

  9. Plume composition changes during the birth of a new lava lake - Nyamulagira volcano, DR Congo

    NASA Astrophysics Data System (ADS)

    Bobrowski, Nicole; Giuffrida, Giovanni Bruno; Calabrese, Sergio; Scaglione, Sarah; Yalire, Mathieu; Liotta, Marcello; Brusca, Lorenzo; Arellano, Santiago; Rüdiger, Julian; Galle, Bo; Castro, Jonathan; Tedesco, Dario

    2016-04-01

    Nyamulagira, in the Virunga Volcanic Province (VVP), Democratic Republic of Congo, is one of the most active volcanoes in Africa. The volcano is located about 25 km north-northwest of Lake Kivu in the Western Branch of the East African Rift System (EARS) with a distance of only 15 km to Nyiragongo, which is well known for its decades-old active lava lake. Nyamulagira is a shield volcano with a 3058 m high and ~2000 m wide summit caldera. The volcano is characterized by frequent eruptions, which occur both from the summit crater and from the flanks (31 flank eruptions over the last 110 years). Due to the low viscosity lava, although significantly higher than the one of Nyiragongo, wide lava fields cover over 1100 km2 and lava flows often reach > 20 km length. More than 100 flank cones can be counted around the summit crater. A part from its frequent eruptions Nyamulagira had a long period of lava lake activity in the past, at least from 1912 to 1938. During the past decades, gas emissions from Nyamulagira have been only reported during eruptions. This changed in 2012, however, when Nyamulagira began emitting a persistent gas plume above its crater. By the end of 2014, and beginning in 2015, a lava lake was born, a feature that - as of the time of this writing - is still growing. To date, very little is known about gas emissions of Nyamulagira volcano with the only exception for SO2. Very few studies have been conducted regarding the volatile chemistry of Nyamulagira. We try to fill this gap by reporting gas composition measurements of Nyamulagira's volcanic plume during the birth of the lava lake, and in the first year of the lake's activity. Two field surveys have been carried out, the first one on November 1st, 2014 and the second one October 13th - 15th, 2015. Applying the broad toolbox of volcanic gas composition measurement techniques offered us the opportunity to characterize Nyamulagira's plume in excruciating detail. Nyamulagira is known to be a significant

  10. A New Approach to Inferences for Pancake Domes on Venus

    NASA Technical Reports Server (N