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  1. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

    article title:  Ash from Eyjafjallajökull Volcano, Iceland Stretches over the North Atlantic   ... that occurred in late March 2010, the Eyjafjallajökull Volcano in Iceland began erupting again on April 14, 2010. The resulting ash ...

  2. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

    ... Eyjafjallajökull Volcano Ash Plume Particle Properties     View larger image ... background maritime particles are typically tiny spherical liquid droplets. In the last panel, the plume stands out relative to the ...

  3. A Tensor Hyperviscosity Model in Kull

    SciTech Connect

    Ulitsky, M

    2005-06-28

    A tensor artificial hyper-viscosity model has recently been added to the available list of artificial viscosities that one can chose from when running KULL. This model is based on the theoretical work of A. Cook and B. Cabot, and the numerical results of running the model in the high-order spectral/compact finite difference framework of the Eulerian MIRANDA code. The viscosity model is based on filtering a Laplacian or bi-Laplacian of the strain rate magnitude, and it was desired to investigate whether the formalism that worked so well for the MIRANDA research code could be carried over to an unstructured ALE code like KULL.

  4. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

    ... to capture a series of images of the Eyjafjallajökull volcano and its erupting ash plume. Figure 1 is a view from MISR's nadir ... The companion image, Figure 2, is a stereo anaglyph (see  Volcano Plume Heights Anaglyph ) generated from the nadir and 46-degree ...

  5. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

    ... height map   Ash from Iceland's Eyjafjallajökull volcano, viewed here in imagery from the Multi-angle Imaging SpectroRadiometer ... natural-color, nadir (vertical) view of the scene, with the volcano itself located outside the upper left corner of the image. The ash ...

  6. KULL Simulations of OMEGA Radiation Flow Experiments

    NASA Astrophysics Data System (ADS)

    Kallman, J.; MacLaren, S.; Baker, K.; Amala, P.; Lewis, K.; Zika, M.

    2012-10-01

    The problem of radiation flow in a right circular cylinder is of interest for the verification and validation of radiation codes, which utilize several mechanisms for determining radiation transport (diffusion, discrete ordinates, and Monte Carlo). This flow is analogous to free molecular flow in a similar geometry.footnotetextE. Garelis and T.E. Wainwright. Phys. Fluids. 16, 4 (1973) A series of experiments were conducted on the OMEGA laser in cases with a low-density heated cylindrical wall. The experiments consisted of a 1.6 mm diameter gold hohlraum containing an on-axis 700 μm diameter SiO2 cylinder contained in an 80 μm thick carbon foam tube. Five shots panning three test cases were used: the nominal geometry described above (heated wall), the carbon tube replaced with solid gold, and a gold cap placed on the laser end of the cylinder assembly to block axial radiation flow. Simulations of each experimental target type were run with the KULL radiation code, and were used to compare the different radiation transport packages in KULL by employing synthetic diagnostics to match the experimental DANTE cavity radiation temperature time history and soft x-ray images taken by a streak camera imaging the far end of the hohlraum.

  7. KULL: LLNL's ASCI Inertial Confinement Fusion Simulation Code

    SciTech Connect

    Rathkopf, J. A.; Miller, D. S.; Owen, J. M.; Zike, M. R.; Eltgroth, P. G.; Madsen, N. K.; McCandless, K. P.; Nowak, P. F.; Nemanic, M. K.; Gentile, N. A.; Stuart, L. M.; Keen, N. D.; Palmer, T. S.

    2000-01-10

    KULL is a three dimensional, time dependent radiation hydrodynamics simulation code under development at Lawrence Livermore National Laboratory. A part of the U.S. Department of Energy's Accelerated Strategic Computing Initiative (ASCI), KULL's purpose is to simulate the physical processes in Inertial Confinement Fusion (ICF) targets. The National Ignition Facility, where ICF experiments will be conducted, and ASCI are part of the experimental and computational components of DOE's Stockpile Stewardship Program. This paper provides an overview of ASCI and describes KULL, its hydrodynamic simulation capability and its three methods of simulating radiative transfer. Particular emphasis is given to the parallelization techniques essential to obtain the performance required of the Stockpile Stewardship Program and to exploit the massively parallel processor machines that ASCI is procuring.

  8. Kull ALE: II. Grid Motion on Unstructured Arbitrary Polyhedral Meshes

    SciTech Connect

    Anninos, P

    2002-02-11

    Several classes of mesh motion algorithms are presented for the remap phase of unstructured mesh ALE codes. The methods range from local shape optimization procedures to more complex variational minimization methods applied to arbitrary unstructured polyhedral meshes necessary for the Kull code.

  9. Earthshots: Satellite images of environmental change – Breiðamerkurjökull Glacier, Iceland

    USGS Publications Warehouse

    Adamson, Thomas

    2015-01-01

    In these false color Landsat images, vegetated land surfaces appear red. Snow and ice are white. The Vatnajökull glacier is the bright white area in the upper left. Outlet glaciers streak away from it toward the Atlantic Ocean in the lower right. Breiðamerkurjökull is the largest glacial tongue on Vatnajökull and is featured in the center of these images.

  10. Visualizing the Evolution of Eyjafjallajökull Ash Clouds

    NASA Astrophysics Data System (ADS)

    Realmuto, V. J.; Prata, F.

    2010-12-01

    The closure of European airspace due to Eyjafjallajökull ash clouds provoked strong reactions from the airlines, government officials, travelling public and news media. These reactions underscore the need for effective communication of scientific concepts, data products, and model results. Computer animation techniques are well-suited for the visualization of dynamic three-dimensional phenomena, such as the evolution of Eyjafjallajökull ash clouds over Europe, and a wide variety of animation tools are available to scientists. However, authors have little control over the distribution, modification, and display of animations once they are released to the public. It is incumbent on the scientific community to ensure that the original products strike an optimum balance between scientific accuracy, clarity of message, and artistic license. In this presentation we explore techniques for visualizing changes in the concentrations of ash and height of the Eyjafjallajökull ash clouds on 16 and 17 April 2010. We derived estimates of ash concentration and cloud height from data acquired with the Spinning Enhanced Visible and Infrared Imager (SEVIRI), which flies on the geostationary Meteosat-9 satellite. SEVIRI collects full-disk imagery every 15 minutes; and we used these data to track hourly changes in the composition and heights of the clouds. We compare map-based and volumetric visualizations of the Eyjafjallajökull clouds that portray the changes in the extent and configuration of restricted airspace resulting from changes in the guidelines governing the operations of commercial air traffic within volcanic ash clouds. Based on these comparisons, we evaluate the efficacy of these products for communication with technical and non-technical audiences.

  11. Electrical charging of volcanic ash from Eyjafjallajökull

    NASA Astrophysics Data System (ADS)

    Aplin, Karen; Nicoll, Keri; Houghton, Isobel

    2015-04-01

    Electrical charging of volcanic ash is important for both the generation of lightning and the detectability and lifetime of volcanic plumes, but remains poorly understood. Previous work showed that volcanic ash samples obtained from the 2011 Grímsvötn eruption were readily electrically charged by friction, a process known as contact charging or triboelectrification. The efficiency of charging depended on the span, or width, of the particle size distribution, with broader charge distributions charging more than narrower or more multimodal distributions. Here we report results of laboratory experiments investigating the charging of ash from Eyjafjallajökull, using samples collected from Sólheimaheithi, 22km from the crater, on 5 May 2010. A similar methodology to the earlier experiments with Grímsvötn ash was used, which involved letting small quantities of ash fall through a charge collection apparatus, and measuring the charge with a sensitive electrometer. The ash was sieved into different size bins, and artificial size distributions were also created to investigate the effect of the modality and span of the samples tested. Like the ash from Grímsvötn, the Eyjafjallajøkull ash charged more effectively when the size distribution was broader. Ash from Grímsvötn charged more readily, and with an opposite sign, than Eyjafjallajökull ash, with a median net charge of +630 pC/g compared to -116 pC/g. This difference in charging is not completely explained by the span effect described above, since the two unsieved ash samples had very similar overall spans, so would have been expected to have similar median net charges. We find that the charging may also be affected by the role of the smallest particles,

  12. Surges of outlet glaciers from the Drangajökull ice cap, northwest Iceland

    NASA Astrophysics Data System (ADS)

    Brynjólfsson, Skafti; Schomacker, Anders; Korsgaard, Niels J.; Ingólfsson, Ólafur

    2016-09-01

    Surface elevation and volume changes of the Drangajökull surge-type glaciers, Reykjarfjarðarjökull and Leirufjarðarjökull, were studied by comparing digital elevation models that pre-date and post-date their most recent surges. Annual glacier-frontal measurements were used to estimate average ice velocities during the last surge of the glaciers. The observations show a distinct ice discharge, most of which was from the upper reservoir areas, down to the receiving areas during the surges. The surface draw-down in the reservoir areas was usually 10-30 m during the surges, while the thickening of the receiving areas was significantly more variable, on the order of 10-120 m. Despite a negative geodetic net mass balance derived from the digital elevation models, the reservoir areas have been gaining mass since the surge terminations. This surface thickening along with considerable ablation of the receiving areas will most likely return the glacier surface profiles to the pre-surge stage. Our results indicate that (a) greatest surface thinning in the upper reservoir areas of Drangajökull rather than proximal to the equilibrium line during Vatnajökull surges and (b) development of Drangajökull surges that resembles Svalbard surge-type glaciers rather than Vatnajökull surge-type glaciers. The contrasting surge characteristics could be explained by differences in glacier geometry, topography and substratum of the Drangajökull and Vatnajökull surge-type glaciers.

  13. Laser-driven Implosion Simulations with the Kull Code

    NASA Astrophysics Data System (ADS)

    Kaiser, Thomas B.; Owen, J. Michael; Madsen, Niel K.

    1999-11-01

    We present results of two- and three-dimensional simulations of implosion of a gamma-law gas driven by absorption of energy from an external laser source. Laser light propagation and power deposition were modeled with a recently-developed package(T. B. Kaiser, J. L. Milovich, A. I. Shestakov, M. K. Prasad, Bulletin of the A.P.S. 43), paper R8Q 26 (1998). that uses geometrical optics and inverse-bremsstrahlung to model the relevant physical processes, while the hydrodynamics calculations used a finite-volume, staggered-grid ALE scheme, and electron heat transport was treated diffusively. The simulations were performed with Kull, an ASCI code currently being developed at LLNL to model ICF experiments and astrophysical phenomena.

  14. New START, Eyjafjallajökull, and Nuclear Winter

    NASA Astrophysics Data System (ADS)

    Robock, Alan

    2010-11-01

    On 8 April 2010, U.S. president Barack Obama and Russian president Dmitry Medvedev signed the Treaty Between the United States of America and the Russian Federation on Measures for the Further Reduction and Limitation of Strategic Offensive Arms, committing the United States and Russia to reducing their nuclear arsenals to levels less than 5% of the maximum during the height of the cold war in the 1980s. This treaty is called “New START,” as it is a follow-on to the 1991 Strategic Arms Reductions Treaty (START). On 14 April 2010 the Eyjafjallajökull volcano in Iceland began an explosive eruption phase that shut down air traffic in Europe for 6 days and continued to disrupt it for another month. What do these two events have in common? Nuclear weapons, when targeted at cities and industrial areas, would start fires, producing clouds of sooty smoke. Volcanic eruptions emit ash particles and sulfur dioxide (SO2), which forms sulfate aerosols in the atmosphere. Thus, both the use of nuclear weapons and volcanic eruptions produce particles that can be transported large distances from the source and can affect weather and climate.

  15. The Vetter-Sturtevant Shock Tube Problem in KULL

    SciTech Connect

    Ulitsky, M S

    2005-10-06

    The goal of the EZturb mix model in KULL is to predict the turbulent mixing process as it evolves from Rayleigh-Taylor, Richtmyer-Meshkov, or Kelvin-Helmholtz instabilities. In this report we focus on an example of the Richtmyer-Meshkov instability (which occurs when a shock hits an interface between fluids of different densities) with the additional complication of reshock. The experiment by Vetter & Sturtevant (VS) [1], involving a Mach 1.50 incident shock striking an air/SF{sub 6} interface, is a good one to model, now that we understand how the model performs for the Benjamin shock tube [2] and a prototypical incompressible Rayleigh-Taylor problem [3]. The x-t diagram for the VS shock tube is quite complicated, since the transmitted shock hits the far wall at {approx}2 millisec, reshocks the mixing zone slightly after 3 millisec (which sets up a release wave that hits the wall at {approx}4 millisec), and then the interface is hit with this expansion wave around 5 millisec. Needless to say, this problem is much more difficult to model than the Bejamin shock tube.

  16. NAME predictions of ash dispersion from Eyjafjallajökull

    NASA Astrophysics Data System (ADS)

    Devenish, B.

    2010-12-01

    NAME (Numerical Atmospheric-dispersion Modelling Environment) is the Met Office's operational dispersion model. It is a Lagrangian model which follows fluid particles through realistic flow fields provided by the Met Office's numerical weather prediction model. NAME was initially developed after the Chernobyl accident in 1986. It has evolved considerably since its inception, continues to do so and is now in its third version. Its functionality includes parameterisations of the subgrid variability; a variety of source types including dust and sea salt; sedimentation of solid particles; wet and dry deposition; buoyant plume-rise; chemical reactions; and radioactive decay. Concentration statistics are calculated by averaging over specified grid boxes. NAME is widely used both by the Met Office and other licensed users both operationally and as a research tool for applications ranging from pollution dispersion to the airborne spread of viruses such as bluetongue and foot-and-mouth disease. The Met Office is the London VAAC (Volcanic Ash Advisory Centre) with responsibility for the north-east Atlantic. As such, NAME was used to predict the evolution of the ash cloud from the recent eruption of Eyjafjallajökull in Iceland. In this presentation, NAME predictions are compared with a variety of observations including ground-based lidar measurements, aircraft measurements and satellite data. In addition, the results of a number of sensitivity studies will be presented including sensitivity to plume height, source strength, source shape, particle size and subgrid scale diffusion.

  17. Mapping the Variability of Winter Accumulation on the Hofsjökull Ice Cap, Central Iceland

    NASA Astrophysics Data System (ADS)

    Thorsteinsson, Th.; Jóhannesson, T.; Einarsson, B.; Gunnarsson, A.; Kjartansson, V.; Sigurðsson, O.

    2016-09-01

    The poster presents results from the mapping of winter accumulation on the Hofsjökull ice cap, Central Iceland, using a ground penetrating radar. The data are used to correct biases in older mass-balance data with more limited spatial coverage.

  18. The Drangajökull ice cap, northwest Iceland, persisted into the early-mid Holocene

    NASA Astrophysics Data System (ADS)

    Schomacker, Anders; Brynjólfsson, Skafti; Andreassen, Julie M.; Gudmundsdóttir, Esther Ruth; Olsen, Jesper; Odgaard, Bent V.; Håkansson, Lena; Ingólfsson, Ólafur; Larsen, Nicolaj K.

    2016-09-01

    Most glaciers and ice caps in Iceland experienced rapid deglaciation in the early Holocene, reaching a minimum extent during the Holocene Thermal Maximum. Here we present evidence of the Holocene glacial history from lake sediment cores retrieved from seven threshold lakes around the Drangajökull ice cap in the Vestfirðir peninsula, NW Iceland. The sediment cores show on/off signals of glacial meltwater activity, as minerogenic material deposited from glacial meltwater alternates with organic-rich material (gyttja) deposited without glacial meltwater. We base the chronology of the sediment cores on 14C ages and geochemical identification of key tephra layers with known ages. A 25-cm thick layer of the Saksunarvatn tephra in Lake Skorarvatn indicates that the northern part of the ice cap had reached a similar size as today or was smaller already by 10.2 cal kyr BP. However, 14C ages of lake sediment cores from the highlands southeast of Drangajökull suggest that this part of the ice cap was larger than today until 7.8-7.2 cal kyr BP. Even today, the Drangajökull ice cap has a different behavior than the main ice caps in Iceland, characterized by a very low glaciation limit. Because palaeoclimatic proxies show an early-mid Holocene temperature optimum in this part of Iceland, we suggest that the persistence of Drangajökull into the early Holocene and, possibly, also the entire Holocene was due to high winter precipitation.

  19. Dust events on Vatnajökull, Iceland: comparison between model results and measurements

    NASA Astrophysics Data System (ADS)

    Dragosics, Monika; Groot Zwaaftink, Christine; Thorsteinsson, Throstur; Stohl, Andreas

    2016-04-01

    Dust events in Iceland considerably influence the surface albedo and subsequently the energy balance of glaciers such as Vatnajökull. Here we study dust events on Vatnajökull based on model simulations and ground-based measurements. Possible sources of dust origin are proglacial areas and sandy deserts which cover more than 22% of Iceland. A newly developed scheme for dust mobilization is used to estimate dust emission from these sandy deserts. Driven with these emissions, a Lagrangian dispersion model, FLEXPART, is used to calculate dust concentration and deposition. The model simulations facilitate to distinguish main source areas of dust transported to the glacier. Meteorological conditions at the source locations as well as flows induced by topography will affect the spatial distribution of dust on the glacier, and not all are resolved by the meteorological data from ECMWF used to run FLEXPART (resolution 0.2 degrees or about 22 km). We aim to determine how important local effects are. Ground based data such as distributed snow samples from Vatnajökull with impurities were collected in October 2013 and 2015. Additionally, firn cores of about 8 meters depth from Brúarjökull (NE Vatnajökull), were taken in 2014 and 2015. The firn cores show pronounced dust layers in the years 2012, 2011, 2010 and 2008. These dust concentrations from firn cores and snow samples as well as time series of albedo measurements from automatic weather stations, were compared to model results. For this comparison we chose ablation seasons which are not influenced by volcanic eruptions. For these periods we explain variations in dust amounts and their spatial patterns.

  20. Structure and Tectonic Position of the Eyjafjallajökull Volcano, S-Iceland

    NASA Astrophysics Data System (ADS)

    Einarsson, P.; Hjartardóttir, R.

    2010-12-01

    The Eyjafjallajökull volcano, one of the oldest active volcanoes in Iceland, is located in the volcanic flank zone of South Iceland, a few tens of kilometers off the nearest branch of the mid-Atlantic plate boundary. The volcanic edifice is an elongated, flat cone of about 1650 m height. A 100-200 m thick glacier covers the upper part of the volcano and its elliptical 2.5-km-wide summit crater or caldera. Eyjafjallajökull products have an alkaline composition, similar to other off-rift volcanoes in Iceland. An E-W trending rift zone transects the volcano, most eruptive fissures and crater rows trend E-W, but occasional radial fissures are observed around the summit area. Eruptive fissures on the west flank are curved and tend to follow the topographic gradient. The E-W orientation of the rift zone suggests a tectonic control of a regional stress field with the least compressive stress oriented N-S. The strong influence of the topography suggests, however, that this intraplate stress field is weak. Dikes in the older parts of the volcano strike north-easterly and indicate a change in the stress orientation during the last 0.78 My. This change may be related to a southward propagation of the Eastern Rift Zone of Iceland and the transfer of spreading from the Western Rift Zone. The rather mild activity of Eyjafjallajökull (3 eruptions in 1100 years) stands in strong contrast to that of the neighbouring volcano Katla, which is one of Iceland‘s most active volcanoes. The eastern rift of Eyjafjallajökull extends into the western flank of Katla and the distance between the two volcanic centers is only 25 km. Their magmatic sources, however, appear to be chemically separated in spite of apparent sympathetic behaviour of the two volcanoes. The only well documented historical eruption of Eyjafjallajökull, 1821-1823, was followed by a moderately small eruption of Katla in 1823. There is evidence for similar behaviour in the two other known eruptions of Eyjafjallajökull

  1. Melt inclusion constraints on the magma source of Eyjafjallajökull 2010 flank eruption

    NASA Astrophysics Data System (ADS)

    Moune, S.; Sigmarsson, O.; Schiano, P.; Thordarson, T.; Keiding, J. K.

    2012-09-01

    The 2010 eruptive activity at the Eyjafjallajökull volcanic system began 20 March with a basaltic flank eruption on a 300 m long fissure on the Fimmvörðuháls Pass, in between Eyjafjallajökull and Mýrdalsjökull volcanoes. The magma expelled from the fissure is olivine- and plagioclase-bearing mildly alkali basalt that exhibits uniform and rather primitive whole-rock composition. This event provides a rare opportunity to assess deep magmatic processes in Iceland. Melt inclusions (MIs) hosted in olivine phenocrysts were analyzed for their major, trace and volatile element concentrations to enable identification of magmatic source(s) for Eyjafjallajökull volcano and to better constrain processes occurring at depth. The MIs, in particular those in Mg-rich olivines, record primary magma composition before homogenisation and differentiation during magma ascent. The olivine phenocrysts hosting the MIs have a large compositional range, extending from Fo73 to Fo87, reflecting changes in the magma characteristics from the source to the surface. The MI compositions exhibit significant variations with MgO ranging from 5.2 to 7.2 wt%. This compositional range was caused by a binary mixing of two basaltic end-members followed by fractional crystallization process. The sources of these end-members are identical to those of Katla and Surtsey basalts, with a dominant role of the Katla source. Trace element characteristics of the Fimmvörðuháls MIs suggest important proportions of recycled oceanic crust in their mantle sources.

  2. A preliminary geomorphological map from the Múlajökull drumlin field, Iceland

    NASA Astrophysics Data System (ADS)

    Jonsson, S. A.; Schomacker, A.; Benediktsson; Johnson, M.; Ingolfsson, O.

    2012-12-01

    The drumlin field in front of Múlajökull, a surge-type, outlet glacier from Hofsjökull in Iceland, is the only known active drumlin field (Johnson et al., 2010). The aim of this study is to further explore the distribution and formation of drumlins and drumlin fields in a modern glacial environment. We use data from Digital Elevation Models (DEMs), aerial imagery and field mapping. Here we present a preliminary geomorphological map based on remote sensing and fieldwork in 2010 and 2011. Geomorphological mapping of the drumlin field both with DEMs and ground proofing has revealed over 100 drumlins and a number of drumlinized ridges. The drumlins furthest from the present ice margin are broader and have lower relief than those closer to the ice. We suggest that this reflects an evolution of the drumlin form during recurrent surging. The drumlins farther away from the ice have experienced fewer surges than those that have just been uncovered due to present retreat of the ice margin. During successive surges, the drumlins become narrower and develop a higher relief. Reference: Johnson, M.D., Schomacker, A., Benediktsson, Í. Ö., Geiger, A. J., Ferguson, A. and Ingólfsson, Ó. 2010, Active drumlin field revealed at the margin of Múlajökull, Iceland: A surge-type glacier: Geology v. 38, p. 943-946.

  3. The Eyjabakkajökull glacial landsystem, Iceland: Geomorphic impact of multiple surges

    NASA Astrophysics Data System (ADS)

    Schomacker, Anders; Benediktsson, Ívar Örn; Ingólfsson, Ólafur

    2014-08-01

    A new glacial geomorphological map of the Eyjabakkajökull forefield in Iceland is presented. The map covers c. 60 km2 and is based on high-resolution aerial photographs recorded in August 2008 as well as field checking. Landforms are manually registered in a geographical information system (ArcGIS) based on inspection of orthorectified imagery and digital elevation models of the area. We mapped subglacially streamlined landforms such as flutes and drumlins on the till plain, supraglacial landforms such as ice-cored moraine, pitted outwash, and concertina eskers, and ice-marginal landforms such as the large, multi-crested 1890 surge end moraine and smaller single-crested end moraines. The glaciofluvial landforms are represented by outwash plains, minor outwash fans, and sinuous eskers. Extramarginal sediments were also registered and consist mainly of old sediments in wetlands or locally weathered bedrock. Eyjabakkajökull has behaved as a surge-type glacier for 2200 years; hence, the mapped landforms originate from multiple surges. Landforms such as large glaciotectonic end moraines, hummocky moraine, long flutes, crevasse-fill ridges, and concertina eskers are characteristic for surge-type glaciers. The surging glacier landsystem of Eyjabakkajökull serves as a modern analog to the landsystems of terrestrial paleo-ice streams.

  4. Seismic Tremor Generated by Multiple Processes, Vatnajökull Glacier, Iceland

    NASA Astrophysics Data System (ADS)

    Eibl, E. P. S.; Bean, C. J.; Vogfjord, K. S.

    2014-12-01

    Vatnajökull glacier in eastern Iceland covers five volcanic systems in which Bárdarbunga and Grimsvötn are the most active volcanoes. Whilst fluctuating ice cover mitigates against year-round near-field monitoring of the volcanoes, important information can be gleaned from stations deployed at the glacier's edge. Glacial cover significantly increases the complexity of and the solution space for observed seismic signals. For example tremor can be caused by magmatic activity, intra-glacier interactions, melt water flow or hydrothermal boiling. A better understanding of hazard requires a more indepth understanding of the signals generated by these processes at Vatnajökull. We augmented the sparse network in the region with two seven-element broad band seismometer arrays west of Vatnajökull, in Jökulheimar and near Laki respectively. Observed seismic tremor-like transients (< 2 Hz) originating from two cauldrons west of Grimsvötn are directly associated with small flooding events (jökulhaups), as subsequently confirmed by radar and hydrological observations. For larger longer duration floods dominant harmonic tremor frequencies of 2 to 4 Hz are observed, but they change in amplitude and frequency with time, likely reflecting variable feed and flow rates, associated with a moving source. Our aim is to 'fingerprint' these events such that they can be distinguished from seismic tremor signals associated with magmatic activity.

  5. The Last Days of the 2010 Eruption at Eyjafjallajökull Volcano

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    The 2010 eruption at Eyjafjallajökull ice-capped volcano (Iceland) was the most striking volcanological event occurred in Europe in the last years. Scientific data on the eruptive activity and emitted products have been reported from the Institute of Earth Sciences - Nordic Volcanological Center (http://www2.norvol.hi.is). The onset of the eruption was heralded on 20 March 2010 by the opening of an eruptive fissure at Fimmvorduhals, an area located between the Eyjafjallajökull and Mýrdalsjökull ice caps and bordering the Katla volcano, where the eruptive activity displayed mainly Hawaiian features until 12 April 2010. Two days later, new magma rose up again but shifted just under the summit caldera of the Eyjafjallajökull, where the ice-cap occurred. Since 14 April, the eruption was characterized by explosive phases of different style (from purely magmatic to phreatomagmatic), producing powerful eruption columns that heavily disrupted the international air traffic for several days. After 16 May 2010, the eruptive activity went by an unexpected waning phase characterized by marked decrease of the eruptive phenomena up to their almost total exhaustion on 23 May. We present field data collected during these final days of the eruption. Field surveys and observations were carried out covering an area of about 1200 km2 around the eruptive vents, allowing us to report on the decreasing height of the eruption column and the dispersal of the volcanic plume. PM10 concentrations were measured at ground level using a TSI DUSTTRAKTM aerosol monitor just below the eruption cloud, where we also account for aggregation phenomena of the falling ashes (see also Scarlato et al., this meeting). Values of sedimentation rate of the deposit were measured between 18 and 22 May. In this period we collected more than 15 samples, mainly ashy, from 6 different sites. We have determined grain-size, componentry, density and glass composition of collected samples. Preliminary results show

  6. Albedo changes on Vatnajökull associated with dust events, Iceland

    NASA Astrophysics Data System (ADS)

    Dragosics, Monika; Thorsteinsson, Throstur; Pálsson, Finnur

    2015-04-01

    Deposition of aerosols on the glacier surface changes the albedo, thus enhances melt rates and affects the glacier mass balance. There are extensive sources for particles in Iceland; volcanic sandy deserts and glacial outwash plains cover more than 22% of the country. (Arnalds et al., 2001) Particles from these sources get airborne and transported on to the ice caps in several dust storms in most years, causing changes in albedo and surface energy balance. Long-term observations of atmospheric dust over the last 60 years show a high frequency of dust events in Iceland, with more than 34 dust days per year (Dagsson-Waldhauserova et al., 2013). Volcanoes are sources of large quantities of particles during an eruption, and for some years (even decades or centuries) after, due to re-suspension. Volcanic eruptions are frequent in Iceland, often with subsequent deposition of volcanic tephra on glaciers. The most recent are the eruptions of Eyjafjallajökull and Grímsvötn in 2010 and 2011. The evolution of surface albedo is measured with in-situ automatic weather stations (AWS), during summer, on a few locations on icelandic ice-caps. To detect dust events on Brúarjökull outlet (NE Vatnajökull ice-cap), drops in albedo are compared with energy balance results from the measured values of the AWSs, temperature, dust storm occurrence (recorded at manned weather stations in the lowlands), and visible changes on satellite observations (MODIS images) as in-situ samples. A dust deposition event is detected by comparing the MODIS images of 20 May and 28 May 2012 and explains a drop in albedo on 21 May, lasting to June 4 from 0.86 to 0.51. The in-situ samples are: snow surface samples from Vatnajökull with impurities collected in October 2013, representing the deposition of one summer over the ice cap; and two firn cores of about 8 meters depth from Brúarjökull, taken in June 2014. The firn cores were analysed to detect dust layers and to measure mass, volume, density of

  7. The landscape architecture of the forefield of Eyjabakkajökull, a surge-type glacier in Iceland

    NASA Astrophysics Data System (ADS)

    Schomacker, A.; Benediktsson

    2012-12-01

    A new geomorphological map of the forefield of the Eyjabakkajökull surge-type glacier in Iceland is presented. The map is based on field mapping and aerial photography from 2008 that covers c. 58 km2, including the Eyjabakkajökull glacier tongue and its entire forefield. When viewed in the context of glacial landsystems, the map identifies landforms that can be regarded as characteristic of glacier surging; in particular, crevasse-fill ridges, concertina eskers, long flutings, hummocky and ice-cored moraines, pitted outwash plains, and glaciotectonic end moraines. In addition, landforms that are common for many glacial environments but less typical of surging, were also identified and mapped; specifically, kames, sinuous eskers, sandar, braided channels, and outwash fans. Eyjabakkajökull has experienced surges every 21-40 years during the past 2200 years; hence, the large-scale landscape architecture is likely a result of dozens of surges. However, the glacial sediments and landforms presently identified in the forefield result from the most recent and historically known surges of Eyjabakkajökull in 1890, 1931, 1938 and 1972. The association of sediments and landforms in the Eyjabakkajökull forefield is diagnostic of glacier surging and may serve as a modern analogue in palaeoglaciological reconstructions.

  8. The geomorphology and ground penetrating radar survey results of the Múlajökull and Þjórsárjökull surge-type glaciers, central Iceland

    NASA Astrophysics Data System (ADS)

    Karušs, Jānis; Lamsters, Kristaps; Běrziņš, Dāvids

    2015-04-01

    Múlajökull and Þjórsárjökull are surge-type outlet glaciers of the Hofsjökull ice cap, central Iceland (Björnsson et al., 2003). The forefield of Múlajökull comprises the active drumlin field of more than 110 drumlins (Johnson et al., 2010; Jónsson et al., 2014) and therefore is an excellent area for studies of glacial geomorphology, subglacial topography and ice structures. This work describes preliminary results obtained during the expedition to Múlajökull and Þjórsárjökull glaciers in August, 2014. In the research ground penetrating radar (GPR) Zond 12-e was used. GPR measurements were performed on both outlet glaciers using 38 MHz and 75 MHz antenna systems. During data acquisition 2000 ns time window was used, while length of profiles was determined using GPS device Garmin GPS-76. In total approximately 3 km of GPR profiles were recorded. GPR signals propagation speed in glacier ice was determined using reflections from internal meltwater channels of glacier. In obtained radarogramms it was possible to trace reflections from the glacier bed till depth of approximately 144 m as well as numerous prominent reflections from internal meltwater channels of glacier. In one of the obtained radarogramms possible subglacial channel below Múlajökull glacier was identified. Also feature of subglacial topography that resembles drumlin was identified. The area of abundant infiltrated water was distinguished close to the ice margin in the radarogramm obtained on Þjórsárjökull suggesting successive supraglacial meltwater infiltration towards glacier margin. During the field work numerous radial crevasses, supraglacial channels and moulins were observed in the marginal zone of Múlajökull. The forefield of Múlajökull mainly consist of subglacial landforms (drumlins, flutes and crevasse-fill ridges), end moraines and sandur plains. Flutes and crevasse-fill ridges were found superimposed on drumlins in places. Till macrofabric was measured close to the

  9. Coupling of Activity at Neighbouring Volcanoes in Iceland: Ground Deformation and Activity at the Bárðarbunga-Tungnafellsjökull and Eyjafjallajökull-Katla Volcano Pairs

    NASA Astrophysics Data System (ADS)

    Parks, M.; Heimisson, E. R.; Sigmundsson, F.; Hooper, A. J.; Ofeigsson, B.; Vogfjord, K. S.; Arnadottir, T.; Dumont, S.; Drouin, V.; Bagnardi, M.; Spaans, K.; Hreinsdottir, S.; Friðriksdóttir, H. M.; Jonsdottir, K.; Guðmundsson, G.; Hensch, M.; Hjaltadottir, S.; Hjartardottir, A. R.; Einarsson, P.; Gudmundsson, M. T.; Hognadottir, T.; Lafemina, P.; Geirsson, H.; Sturkell, E.; Magnússon, E.

    2015-12-01

    Interferometric Synthetic Aperture Radar (InSAR) techniques are used to generate a time series of high-resolution deformation measurements, in the vicinity of two pairs of closely spaced volcanoes in Iceland: Bárðarbunga and Tungnafellsjökull, as well as Eyjafjallajökull and Katla. Following the declaration of Icelandic Volcanoes as a Permanent Geohazard Supersite in 2013, a considerable amount of SAR data was made available for both past and future satellite acquisitions, including new X-band images and historic C-band images. InSAR time series have been formed using these data and compared to other geodetic and microseismic measurements to determine the most likely processes responsible for recently observed deformation and/or seismicity. A comprehensive network of seismometers and continuous GPS stations are already deployed at these volcanoes and a series of campaign GPS measurements have been undertaken since 2010. We present an overview of the temporal variation in InSAR observations and these complementary field based measurements at Bárðarbunga and Tungnafellsjökull from 2014-2015 (covering the recent eruption at Holuhraun and contemporaneous slow collapse of the Bárðarbunga caldera), and Eyjafjallajökull and Katla volcanoes from 2010 onwards, after the 2010 explosive eruption of Eyjafjallajökull. We undertake a joint InSAR-GPS inversion using a Markov-chain Monte Carlo approach. The best-fit source geometries responsible for both the inflation of a 50 km long dyke and simultaneous deflation of the Bárðarbunga central volcano during the 2014-2015 unrest and eruption are found. Using these we calculate the stress changes associated with the Bárðarbunga deformation events and compare our results to the location of earthquake swarms in the vicinity of neighbouring Tungnafellsjökull, where seismic activity increased significantly following the onset of unrest at Bárðarbunga in August 2014. We also determine the optimal source parameters for

  10. Modelling the 20th and 21st century evolution of Hoffellsjökull glacier, SE-Vatnajökull, Iceland

    NASA Astrophysics Data System (ADS)

    Aðalgeirsdóttir, G.; Guðmundsson, S.; Björnsson, H.; Pálsson, F.; Jóhannesson, T.; Hannesdóttir, H.; Sigurðsson, S. Þ.; Berthier, E.

    2011-04-01

    The Little Ice Age maximum extent of glaciers in Iceland was reached about 1890 AD and most glaciers in the country have retreated during the 20th century. A model for the surface mass balance and the flow of glaciers is used to reconstruct the 20th century retreat history of Hoffellsjökull, a south-flowing outlet glacier of Vatnajökull, which is located close to the southeast coast of Iceland. The bedrock topography was surveyed with radio-echo soundings in 2001. A wealth of data are available to force and constrain the model, e.g. surface elevation maps from ~1890, 1936, 1946, 1986, 2001, 2008 and 2010, mass balance observations conducted in 1936-1938 and after 2001, energy balance measurements after 2001, and glacier surface velocity derived by DGPS and correlation of SPOT5 images. The 21% volume loss of this glacier in the period 1895-2010 is realistically simulated with the model. After calibration of the model with past observations, it is used to simulate the future response of the glacier during the 21st century. The mass balance model was forced with an ensemble of temperature and precipitation scenarios from a study of the effect of climate change on energy production in the Nordic countries (the CES project). If the average climate of 2000-2009 is maintained into the future, the volume of the glacier is projected to be reduced by 30% with respect to the present at the end of this century, and the glacier will almost disappear if the climate warms as suggested by most of the climate change scenarios. Runoff from the glacier is predicted to increase for the next 30-40 years and decrease after that as a consequence of the diminishing ice-covered area.

  11. Array Analysis of Seismic Tremor from Different Sources, Vatnajökull Glacier, Iceland

    NASA Astrophysics Data System (ADS)

    Eibl, Eva P. S.; Bean, Christopher J.; Vogfjörd, Kristin

    2015-04-01

    The volcanic systems, including the central volcanoes Bárðarbunga and Grimsvötn in South-East Iceland lie beneath the Vatnajökull glacier and are covered by up to 700 m of ice. This affects the monitoring of the volcanic systems as it complicates a close-to-the-source installation and is the source of strong propagation effects. Monitoring efforts with a single station network include the location of earthquakes which becomes a difficult task when it comes to tremor. We aim to not only locate but also to characterize the source of tremor. We installed three arrays (antennas), each consisting of seven broadband instruments, to the northwest, west and southwest of Vatnajökull glacier (Urðarháls, Jökulheimar and Laki) to improve tremor locations. Another difficulty is that tremor can originate from hydro-thermal systems, the glacier itself or flowing water. Since the beginning of the installation we observed tremor pulses from a small flood (jökulhaup) in the Skaftá river and one at Þórðarhyrna - one of the volcanoes south of Grimsvötn. In August 2014 an effusive eruption started in Holuhraun north of Vatnajökull glacier. Magma is fed from Bárðarbunga and has caused eruptive and flood tremor since the onset of the (still ongoing) eruption. We apply a beamforming method to locate and compare tremor from different sources. Each tremor is analyzed in terms of their frequency content, amplitude, duration, wavefield and spatial and temporal locations in order to classify magmatic- and non-magmatic tremor origins.

  12. Charge Structure and Charging Mechanisms in the Plume of Eyjafjallajökull

    NASA Astrophysics Data System (ADS)

    Behnke, S. A.; Thomas, R. J.; Krehbiel, P. R.; Rison, W.; Edens, H. E.

    2012-12-01

    Three dimensional lightning mapping observations have been made of volcanic lightning during the magmatic phase of the 2010 eruption of Eyjafjallajökull in Iceland. From this data the charge structure in the plume has been inferred, providing insight into the charging mechanisms. During the magmatic phase (3-20 May) lightning was only observed from 11-20 May, except for a scant amount detected on the 6th of May. The observations from this period showed temporal variations in the charge structure, but at times a dipolar structure (negative over positive) was observed. Nearly all lightning discharges initiated low in altitude, between the positive charge layer and ground, and some may have initiated at the vent of the volcano itself. Of interest in volcanic lightning studies is the degree to which silica-based and water-based charging mechanisms influence electrification in volcanic plumes. In the case of the magmatic phase of the Eyjafjallajökull eruption the two charging mechanisms appear to have been complementary. During this part of the eruption charging on silicate particles due to the eruption process is not expected to have been as strong as it was in previous studies of Augustine and Redoubt volcanoes and water-based charging mechanisms like those involved in thunderstorms may have enhanced the electrification. Observations of the temporal variation of the atmospheric temperature structure around Eyjafjallajökull showed that colder temperatures in the latter part of May could have been a key to turning on the lightning activity. A simple charge structure model has been constructed that shows how water-based charging mechanisms could intensify the existing electrification from silicate particles and still allow for discharges to initiate below the lower charge layer. Overall the observations indicate that silica-based charging may not have been enough to initiate lightning during the magmatic phase and water-based charging mechanisms could have provided

  13. Impact of the Eyjafjallajökull ash cloud: A newspaper perspective

    NASA Astrophysics Data System (ADS)

    Harris, Andrew J. L.; Gurioli, Lucia; Hughes, Elizabeth E.; Lagreulet, Sandra

    2012-09-01

    We carried out a content analysis of eight national newspapers published during a 10-day period spanning Eyjafjallajökull's 2010 air space closure. Our intent was to understand the amount and type of material published, and the contribution of volcanologists and emergency responders to this material. We selected the best selling broadsheets and tabloids from the UK, France, Italy and USA. A total area of 135,000 cm2 was devoted to Eyjafjallajökull. Of this, 33% dealt with social themes, followed by volcanological (24%), economic (17%), response (13%) and airline (8%) issues. If, however, we examine the sources providing information we find a very different situation. Altogether, 669 sources were cited as giving quotes, of which 33% were credited to the air industry, followed by public (22%), politicians (12%), volcanologists (9%), responders (8%) and economists (2%). We also recorded all word descriptors for the ash cloud and its effects, with a total of 5380 words being logged. Negative words were the most common, with stranded having the highest frequency (180); chaos appearing 57 times. Coverage, thus, tended to feature quotes from the air industry, and carry a negative air; at times being confusing and contradictory. This, coupled with the fact that volcanological pieces tended to be placed well down the reporting order, meant that the message was of a chaotic situation and response, the performance of those who could be ascribed blame, i.e., responsible government agencies, thus likely being perceived in a negative light.

  14. An extreme wind erosion event of the fresh Eyjafjallajökull 2010 volcanic ash.

    PubMed

    Arnalds, Olafur; Thorarinsdottir, Elin Fjola; Thorsson, Johann; Waldhauserova, Pavla Dagsson; Agustsdottir, Anna Maria

    2013-01-01

    Volcanic eruptions can generate widespread deposits of ash that are subsequently subjected to erosive forces which causes detrimental effects on ecosystems. We measured wind erosion of the freshly deposited Eyjafjallajökull ash at a field site the first summer after the 2010 eruption. Over 30 wind erosion events occurred (June-October) at wind speeds > 10 m s(-1) in each storm with gusts up to 38.7 m s(-1). Surface transport over one m wide transect (surface to 150 cm height) reached > 11,800 kg m(-1) during the most intense storm event with a rate of 1,440 kg m(-1) hr(-1) for about 6½ hrs. This storm is among the most extreme wind erosion events recorded on Earth. The Eyjafjallajökull wind erosion storms caused dust emissions extending several hundred km from the volcano affecting both air quality and ecosystems showing how wind erosion of freshly deposited ash prolongs impacts of volcanic eruptions. PMID:23409248

  15. An extreme wind erosion event of the fresh Eyjafjallajökull 2010 volcanic ash

    PubMed Central

    Arnalds, Olafur; Thorarinsdottir, Elin Fjola; Thorsson, Johann; Waldhauserova, Pavla Dagsson; Agustsdottir, Anna Maria

    2013-01-01

    Volcanic eruptions can generate widespread deposits of ash that are subsequently subjected to erosive forces which causes detrimental effects on ecosystems. We measured wind erosion of the freshly deposited Eyjafjallajökull ash at a field site the first summer after the 2010 eruption. Over 30 wind erosion events occurred (June-October) at wind speeds > 10 m s−1 in each storm with gusts up to 38.7 m s−1. Surface transport over one m wide transect (surface to 150 cm height) reached > 11,800 kg m−1 during the most intense storm event with a rate of 1,440 kg m−1 hr−1 for about 6½ hrs. This storm is among the most extreme wind erosion events recorded on Earth. The Eyjafjallajökull wind erosion storms caused dust emissions extending several hundred km from the volcano affecting both air quality and ecosystems showing how wind erosion of freshly deposited ash prolongs impacts of volcanic eruptions. PMID:23409248

  16. Vatnajökull meltwater discharge variability: a Holocene climate sensor in the Nordic Seas

    NASA Astrophysics Data System (ADS)

    Striberger, J.; Björck, S.; Ingólfsson, Ó.; Kjær, K.; Sandgren, P.; Snowball, I.

    2009-04-01

    The Holocene glacial history of Vatnajökull and its many outlet glaciers is rather poorly known, even though it is one of the largest ice caps outside Antarctica and Greenland. Vatnajökull is positioned in the centre of the Nordic Seas, the region for North Atlantic Deep Water formation and it is influenced by humid-bearing cyclone systems from the southwest. Thus, it can be regarded as a sensor for a combination of different climatic driven processes. Lake Lögurinn (53 km2, 20 m a.s.l), situated northeast of Vatnajökull, is part of the drainage system of Eyjabakkajökull, one of the most conspicuous surging outlet glaciers of the ice cap. In addition to glacial meltwater, the lake also receives discharge from rivers that drain non-glaciated catchments. The mix of glacial and non-glacial suspension makes the sediments suitable for analyses of how the fluvial regime has varied over time and how this relates to meltwater discharge, fluvial discharge and general changes in climate and hydrology. A total of 17.8 m of sediment was obtained from the central part of the northernmost sub-basin in Lake Lögurinn at water depths of 38 and 16 m, respectively. The sediments are laminated in most parts of the sequence. 137Cs analyses of the surface core have confirmed that the laminated couplets are varves. Tephra horizons have been used as time markers throughout the sediments, and X-ray fluorescence and X-ray analyses as well as visual observations have been used in order to identify varves in the uppermost 3.8 m of the sequence. This section covers the time period AD 1262-2005. The sediment contains 610 varves for the periods AD 1262-1476 and AD 1603-2005 (a total of 618 years). A significant change in sedimentation rate is observed between AD 1477-1602 (from 5.9 mm/yr to 1.2 mm/yr). For this period only 18 varves are found. This abrupt change is likely related to a lower discharge rate, or to more turbulent conditions in the lake. The sedimentation rate of the

  17. Stress transfer between magma bodies: Influence of intrusions prior to 2010 eruptions at Eyjafjallajökull volcano, Iceland

    NASA Astrophysics Data System (ADS)

    Albino, F.; Sigmundsson, F.

    2014-04-01

    Stress transfer between separate magma bodies is evaluated by considering how pressure changes related to magma accumulation/propagation influence the stability of a separate nearby magma body. Three-dimensional numerical models are used to evaluate the stability evolution of a magma body through the calculation of two variables: (i) the variation of the threshold pressure needed to cause failure around the magma body and (ii) the magma pressure change. A parametric study indicates that stress interactions are strongly dependent on the distance between magma bodies as well as the body's shape. Such models are then applied to evaluate stress influence of intrusive activity in 1994, 1999, and 2010 at Eyjafjallajökull volcano, which preceded two eruptions there in 2010. Two cases are considered: influence of these intrusions on (i) a magma reservoir at 20 km distance under the Katla volcano and (ii) a silicic magma body under Eyjafjallajökull. The distance between the Eyjafjallajökull intrusions and the Katla reservoir is sufficiently long to reduce the stress interaction to insignificant levels, with an amplitude of the same order as Earth tides (a few kilopascals). However, cumulative stress transfer due to the intrusions to a remnant silicic shallow body situated below the Eyjafjallajökull is much larger (0.5-2.5 MPa). This mechanical transfer could have contributed to the failure of the silicic body and promoted the chemical mixing/mingling between different magma types, which is commonly interpreted as the main cause of the 2010 explosive eruption of Eyjafjallajökull.

  18. Health effects following the Eyjafjallajökull volcanic eruption: a cohort study

    PubMed Central

    Carlsen, Hanne Krage; Hauksdottir, Arna; Valdimarsdottir, Unnur Anna; Gíslason, Thorarinn; Einarsdottir, Gunnlaug; Runolfsson, Halldor; Briem, Haraldur; Finnbjornsdottir, Ragnhildur Gudrun; Gudmundsson, Sigurdur; Kolbeinsson, Thorir Björn; Thorsteinsson, Throstur; Pétursdóttir, Gudrun

    2012-01-01

    Objectives The study aimed to determine whether exposure to a volcanic eruption was associated with increased prevalence of physical and/or mental symptoms. Design Cohort, with non-exposed control group. Setting Natural disasters like volcanic eruptions constitute a major public-health threat. The Icelandic volcano Eyjafjallajökull exposed residents in southern Iceland to continuous ash fall for more than 5 weeks in spring 2010. This study was conducted during November 2010–March 2011, 6–9 months after the Eyjafjallajökull eruption. Participants Adult (18–80 years of age) eruption-exposed South Icelanders (N=1148) and a control population of residents of Skagafjörður, North Iceland (N=510). The participation rate was 72%. Main outcome measures Physical symptoms in the previous year (chronic), in the previous month (recent), General Health Questionnaire (GHQ-12) measured psychological morbidity. Results The likelihood of having symptoms during the last month was higher in the exposed population, such as; tightness in the chest (OR 2.5; 95% CI 1.1 to 5.8), cough (OR 2.6; 95% CI 1.7 to 3.9), phlegm (OR 2.1; 95% CI 1.3 to 3.2), eye irritation (OR 2.9; 95% CI 2.0 to 4.1) and psychological morbidity symptoms (OR 1.3; 95% CI 1.0 to 1.7). Respiratory symptoms during the last 12 months were also more common in the exposed population; cough (OR 2.2; 95% CI 1.6 to 2.9), dyspnoea (OR 1.6; 95% CI 1.1 to 2.3), although the prevalence of underlying asthma and heart disease was similar. Twice as many in the exposed population had two or more symptoms from nose, eyes or upper-respiratory tract (24% vs 13%, p<0.001); these individuals were also more likely to experience psychological morbidity (OR 4.7; 95% CI 3.4 to 6.5) compared with individuals with no symptoms. Most symptoms exhibited a dose–response pattern within the exposed population, corresponding to low, medium and high exposure to the eruption. Conclusions 6–9 months after the Eyjafjallajökull

  19. Using the Schur Complement to Reduce Runtime in KULL's Magnetic Diffusion Package

    SciTech Connect

    Brunner, T A; Kolev, T V

    2010-12-15

    Recently a Resistive Magnetohydrodynamics (MHD) package has been added to the KULL code. In order to be compatible with the underlying hydrodynamics algorithm, a new sub-zonal magnetics discretization was developed that supports arbitrary polygonal and polyhedral zones. This flexibility comes at the cost of many more unknowns per zone - approximately ten times more for a hexahedral mesh. We can eliminate some (or all, depending on the dimensionality) of the extra unknowns from the global matrix during assembly by using a Schur complement approach. This trades expensive global work for cache-friendly local work, while still allowing solution for the full system. Significant improvements in the solution time are observed for several test problems.

  20. Spatial distribution of erosion and deposition during a glacier surge: Brúarjökull, Iceland

    NASA Astrophysics Data System (ADS)

    Korsgaard, Niels J.; Schomacker, Anders; Benediktsson, Ívar Örn; Larsen, Nicolaj K.; Ingólfsson, Ólafur; Kjær, Kurt H.

    2015-12-01

    Time-series of digital elevation models (DEMs) of the forefield of the Brúarjökull surge-type glacier in Iceland were used to quantify the volume of material that was mobilized by the 1963-1964 surge. The DEMs were produced by stereophotogrammetry on aerial photographs from before the surge (1961) and after (1988 and 2003). The analysis was performed on two DEMs of Difference (DoDs), i.e., a 1961-2003 DoD documenting the impact of the surge and a 1988-2003 DoD documenting the post-surge modification of the juvenile surging glacier landsystem. Combined with a digital geomorphological map, the DoDs allow us to quantify the impact of the surge on a landsystem scale down to individual landforms. A total of 34.2 ± 11.3 × 106 m3 of material was mobilized in the 30.7-km2 study area as a result of the most recent surge event. Of these, 17.4 ± 6.6 × 106 m3 of the material were eroded and 16.8 ± 4.7 × 106 m3 were deposited. More than half of the deposited volume was ice-cored landforms. This study demonstrates that although the total mobilized mass volume is high, the net volume gain of ice and sediment deposited as landforms in the forefield caused by the surge is low. Furthermore, deposition of new dead-ice from the 1963-1964 surge constitutes as much as 64% of the volume gain in the forefield. The 1988-2003 DoD is used to quantify the melt-out of this dead-ice and other paraglacial modification of the recently deglaciated forefield of Brúarjökull.

  1. Numerical modeling of Drangajökull Ice Cap, NW Iceland

    NASA Astrophysics Data System (ADS)

    Anderson, Leif S.; Jarosch, Alexander H.; Flowers, Gwenn E.; Aðalgeirsdóttir, Guðfinna; Magnússon, Eyjólfur; Pálsson, Finnur; Muñoz-Cobo Belart, Joaquín; Þorsteinsson, Þorsteinn; Jóhannesson, Tómas; Sigurðsson, Oddur; Harning, David; Miller, Gifford H.; Geirsdóttir, Áslaug

    2016-04-01

    Over the past century the Arctic has warmed twice as fast as the global average. This discrepancy is likely due to feedbacks inherent to the Arctic climate system. These Arctic climate feedbacks are currently poorly quantified, but are essential to future climate predictions based on global circulation modeling. Constraining the magnitude and timing of past Arctic climate changes allows us to test climate feedback parameterizations at different times with different boundary conditions. Because Holocene Arctic summer temperature changes have been largest in the North Atlantic (Kaufman et al., 2004) we focus on constraining the paleoclimate of Iceland. Glaciers are highly sensitive to changes in temperature and precipitation amount. This sensitivity allows for the estimation of paleoclimate using glacier models, modern glacier mass balance data, and past glacier extents. We apply our model to the Drangajökull ice cap (~150 sq. km) in NW Iceland. Our numerical model is resolved in two-dimensions, conserves mass, and applies the shallow-ice-approximation. The bed DEM used in the model runs was constructed from radio echo data surveyed in spring 2014. We constrain the modern surface mass balance of Drangajökull using: 1) ablation and accumulation stakes; 2) ice surface digital elevation models (DEMs) from satellite, airborne LiDAR, and aerial photographs; and 3) full-stokes model-derived vertical ice velocities. The modeled vertical ice velocities and ice surface DEMs are combined to estimate past surface mass balance. We constrain Holocene glacier geometries using moraines and trimlines (e.g., Brynjolfsson, etal, 2014), proglacial-lake cores, and radiocarbon-dated dead vegetation emerging from under the modern glacier. We present a sensitivity analysis of the model to changes in parameters and show the effect of step changes of temperature and precipitation on glacier extent. Our results are placed in context with local lacustrine and marine climate proxies as well

  2. Stratigraphy and Morphology of Drumlins within the Múlajökull Active Drumlin Field, Iceland

    NASA Astrophysics Data System (ADS)

    Benediktsson, I. O.; Jonsson, S. A.; Schomacker, A.; Johnson, M. D.; Ingolfsson, O.

    2014-12-01

    Our current understanding of drumlin formation is largely based on investigations of individual drumlins either within Pleistocene drumlin fields or within the forefields of contemporary glaciers, showing variable composition and structure resulting in different models for drumlin genesis. The stratigraphy and morphology of drumlins within the active drumlin field at the Múlajökull surge-type piedmont glacier, Iceland, have been studied in order to shed light on their formation. A total of 110 drumlins where mapped and measured and their internal stratigraphy and composition were documented in three exposures. The exposures all revealed several till units where the youngest till truncates the older ones on the flanks of the drumlins and at the proximal side. A geomorphological study shows that drumlins within the 1992 surge end moraine are relatively long and narrow whilst drumlins further away from the current ice margin are wider and slightly shorter. Three models are proposed to explain the stratigraphy and morphological evolution of the drumlins within the Múlajökull drumlin field. Firstly, we suggest that radial crevasses in the glacier terminus lead to spatial differences in normal pressure at the base so that deposition is favoured beneath and erosion in between the crevasses and, consequently, the crevasse pattern of the glacier controls the location of the drumlins. Secondly, sediment accumulating beneath the crevasses acts as an obstacle to the ice, which decreases the ice flow and facilitates sedimentation. Simultaneously and subsequently, the accumulation of sediments is shaped by the ice flow into a drumlin. Thirdly we conclude that the drumlins are evolving from being wide and low to in the distal part to narrow and high in the proximal part. The drumlins are then maintained and their relief increases as the glacier erodes the sides and the proximal end of the drumlin and drapes new till layer over the landform.

  3. Intrusion triggering of the 2010 Eyjafjallajökull explosive eruption.

    PubMed

    Sigmundsson, Freysteinn; Hreinsdóttir, Sigrún; Hooper, Andrew; Arnadóttir, Thóra; Pedersen, Rikke; Roberts, Matthew J; Oskarsson, Níels; Auriac, Amandine; Decriem, Judicael; Einarsson, Páll; Geirsson, Halldór; Hensch, Martin; Ofeigsson, Benedikt G; Sturkell, Erik; Sveinbjörnsson, Hjörleifur; Feigl, Kurt L

    2010-11-18

    Gradual inflation of magma chambers often precedes eruptions at highly active volcanoes. During such eruptions, rapid deflation occurs as magma flows out and pressure is reduced. Less is known about the deformation style at moderately active volcanoes, such as Eyjafjallajökull, Iceland, where an explosive summit eruption of trachyandesite beginning on 14 April 2010 caused exceptional disruption to air traffic, closing airspace over much of Europe for days. This eruption was preceded by an effusive flank eruption of basalt from 20 March to 12 April 2010. The 2010 eruptions are the culmination of 18 years of intermittent volcanic unrest. Here we show that deformation associated with the eruptions was unusual because it did not relate to pressure changes within a single magma chamber. Deformation was rapid before the first eruption (>5 mm per day after 4 March), but negligible during it. Lack of distinct co-eruptive deflation indicates that the net volume of magma drained from shallow depth during this eruption was small; rather, magma flowed from considerable depth. Before the eruption, a ∼0.05 km(3) magmatic intrusion grew over a period of three months, in a temporally and spatially complex manner, as revealed by GPS (Global Positioning System) geodetic measurements and interferometric analysis of satellite radar images. The second eruption occurred within the ice-capped caldera of the volcano, with explosivity amplified by magma-ice interaction. Gradual contraction of a source, distinct from the pre-eruptive inflation sources, is evident from geodetic data. Eyjafjallajökull's behaviour can be attributed to its off-rift setting with a 'cold' subsurface structure and limited magma at shallow depth, as may be typical for moderately active volcanoes. Clear signs of volcanic unrest signals over years to weeks may indicate reawakening of such volcanoes, whereas immediate short-term eruption precursors may be subtle and difficult to detect. PMID:21085177

  4. Microbial communities in the subglacial waters of the Vatnajökull ice cap, Iceland

    PubMed Central

    Thór Marteinsson, Viggó; Rúnarsson, Árni; Stefánsson, Andri; Thorsteinsson, Thorsteinn; Jóhannesson, Tómas; Magnússon, Sveinn H; Reynisson, Eyjólfur; Einarsson, Bergur; Wade, Nicole; Morrison, Hilary G; Gaidos, Eric

    2013-01-01

    Subglacial lakes beneath the Vatnajökull ice cap in Iceland host endemic communities of microorganisms adapted to cold, dark and nutrient-poor waters, but the mechanisms by which these microbes disseminate under the ice and colonize these lakes are unknown. We present new data on this subglacial microbiome generated from samples of two subglacial lakes, a subglacial flood and a lake that was formerly subglacial but now partly exposed to the atmosphere. These data include parallel 16S rRNA gene amplicon libraries constructed using novel primers that span the v3–v5 and v4–v6 hypervariable regions. Archaea were not detected in either subglacial lake, and the communities are dominated by only five bacterial taxa. Our paired libraries are highly concordant for the most abundant taxa, but estimates of diversity (abundance-based coverage estimator) in the v4–v6 libraries are 3–8 times higher than in corresponding v3–v5 libraries. The dominant taxa are closely related to cultivated anaerobes and microaerobes, and may occupy unique metabolic niches in a chemoautolithotrophic ecosystem. The populations of the major taxa in the subglacial lakes are indistinguishable (>99% sequence identity), despite separation by 6 km and an ice divide; one taxon is ubiquitous in our Vatnajökull samples. We propose that the glacial bed is connected through an aquifer in the underlying permeable basalt, and these subglacial lakes are colonized from a deeper, subterranean microbiome. PMID:22975882

  5. An analysis of options available for developing a common laser ray tracing package for Ares and Kull code frameworks

    SciTech Connect

    Weeratunga, S K

    2008-11-06

    Ares and Kull are mature code frameworks that support ALE hydrodynamics for a variety of HEDP applications at LLNL, using two widely different meshing approaches. While Ares is based on a 2-D/3-D block-structured mesh data base, Kull is designed to support unstructured, arbitrary polygonal/polyhedral meshes. In addition, both frameworks are capable of running applications on large, distributed-memory parallel machines. Currently, both these frameworks separately support assorted collections of physics packages related to HEDP, including one for the energy deposition by laser/ion-beam ray tracing. This study analyzes the options available for developing a common laser/ion-beam ray tracing package that can be easily shared between these two code frameworks and concludes with a set of recommendations for its development.

  6. Array observations of seasonal seismic noise variations induced by glacier-fed rapids near Vatnajökull, Iceland

    NASA Astrophysics Data System (ADS)

    Möllhoff, Martin; Eibl, Eva P. S.; Bean, Christopher J.; Vogfjörd, Kristin S.

    2016-04-01

    We analyse semi-continuous noise observed in seismic data from an array installed close to Lakagigar southwest of the Vatnajökull ice cap in Iceland. The noise appears in several distinct frequencies bands between 1 and 10 Hz. The bands have different spectral widths suggesting that several sources are acting simultaneously. The back azimuths obtained from array fk-analysis suggest that the observed noise originates mainly from rapids and waterfalls in Hverfisfljot, a glacial river originating from the glacial tongue Sidujökull in the southwest of Vatnajökull. This observation is supported by stream gauge measurements. The seismic noise is only observed between May and September when the water level exceeds a threshold value that lies above the relatively constant lower water level during the winter months. A more detailed analysis of noise back azimuth, noise slowness and the correlation between seismic noise and river level are expected to improve the understanding of water-flow induced seismic noise. This noise source has to be kept in mind when searching for suitable array locations as this overlaps the typical frequency band of e.g. volcanic or flood related tremor. Additionally the observations demonstrate that seismic array data can be useful to infer river states remotely.

  7. The drumlin field and the geomorphology of the Múlajökull surge-type glacier, central Iceland

    NASA Astrophysics Data System (ADS)

    Jónsson, Sverrir Aðalsteinn; Schomacker, Anders; Benediktsson, Ívar Örn; Ingólfsson, Ólafur; Johnson, Mark D.

    2014-02-01

    Here we present a new geomorphological map of the active drumlin field and the forefield of Múlajökull, a surge-type outlet glacier, Iceland. The map is based on aerial photographs taken in 1995 and LiDAR data recorded in 2008. Mapping was done using ArcGIS 10 software on orthorectified imagery, LiDAR data and digital elevation models. The mapped landforms were initially identified on the aerial imagery and LiDAR and then ground-checked in the field. We mapped subglacial, supraglacial, ice-marginal, periglacial, and glaciofluvial landforms. The geomorphology of the Múlajökull forefield is similar to that of the forefields of other surge-type glaciers in Iceland: with a highly streamlined forefield, crevasse-fill ridges, and series of glaciotectonic end moraines. However, the large number (i.e., 110) of drumlins forming the drumlin field is unique for modern Icelandic surge-type glaciers and, as yet, unique for contemporary glaciers in general. Also apparent is that the drumlins are wider and shorter in the distal part of the drumlin field and narrower and longer in the proximal part. Hence, the mapping reveals a development of the drumlins toward a more streamlined shape of the proximal landforms that have experienced more surges. The drumlins in the drumlin field are active, i.e., they form during the modern surges of Múlajökull.

  8. The impacts of the Öræfajökull eruption in AD 1362 and climate change on cultural landscape dynamics in the province of Öræfi south of Vatnajökull glacier, Iceland

    NASA Astrophysics Data System (ADS)

    Sigurmundsson, F.; Gísladóttir, G.; Erlendsson, E.

    2013-12-01

    Environmental changes can be attributed to both natural processes and human influences. The aim of this study is to examine the effects of volcanism and climate change on the development of land quality and cultural landscapes in the province of Öræfi in the Austur-Skaftafellssýsla district, south of Vatnajökull glacier, over the last 1100 years. Few areas in Iceland are as vulnerable to climate changes and volcanic eruptions as the region south of Vatnajökull glacier. The region has been repeatedly affected by tephra fallout from explosive eruptions, most notably the Öræfajökull eruption in AD 1362. This research employs historical written sources to investigate changes in the cultural and natural landscape. Historical and palaeoenvironmental data will be accumulated and stored in a database designed for the research, allowing data to be analyzed and presented on maps. Preliminary results show that from the onset of the settlement in the late 9th century until AD 1362 Öræfi was a wealthy, densely populated farming society, with many large farm estates and large number of livestock (cattle and sheep) sustained by the natural vegetation. The farm estates were 40 by the mid 14th century and the churches were four. The first records of land ownership show that the Church had accumulated the most valuable holdings in Öræfi shortly before the Öræfajökull volcanic eruption in AD 1362. Out of the 40 farm estates 12 belonged to the Church and on a national scale the churches in Öræfi were richer in livestock, sacramentals and missals compared to churches in other parts of Iceland. The Öræfajökull volcanic eruption in AD 1362 had devastating long term impact on the settlement and terrestrial ecosystem in Öræfi. The area was abandoned following the eruption and in the early 15th century only eight out of the 40 farm estates prior to the eruption were settled. The values of the estates shrunk dramatically as did the arable land. The number of churches

  9. Optical, microphysical and compositional properties of the Eyjafjallajökull volcanic ash

    NASA Astrophysics Data System (ADS)

    Rocha-Lima, A.; Martins, J. V.; Remer, L. A.; Krotkov, N. A.; Tabacniks, M. H.; Ben-Ami, Y.; Artaxo, P.

    2014-05-01

    Microphysical, optical, and compositional properties of the volcanic ash from the April-May (2010) Eyjafjallajökull volcanic eruption are presented. Samples of the volcanic ash were taken on the ground in the vicinity of the volcano. The material was sieved, re-suspended, and collected on filters, separating particle sizes into coarse and fine modes. The spectral mass absorption efficiency αabs [m2 g-1] was determined for coarse and fine particles in the wavelength range from 300 to 2500 nm. Size distribution of particles on filters was obtained using a semi-automatic software to analyze images obtained by Scanning Electron Microscopy (SEM). The grain density of the volcanic ash was determined as 2.16(13) g cm-3 by measuring the variation of air volume in a system with volcanic ash and air under compression. Using Mie-Lorenz and T-matrix theories, the imaginary part of the refractive index was derived. Results show the spectral imaginary refractive index ranging from 0.001 to 0.005. Fine and coarse particles were analyzed by X-Ray fluorescence for elemental composition. Fine and coarse mode particles exhibit distinct compositional and optical differences.

  10. How accurate are volcanic ash simulations of the 2010 Eyjafjallajökull eruption?

    NASA Astrophysics Data System (ADS)

    Dacre, Helen; Harvey, Natalie; Webley, Peter; Morton, Don

    2016-04-01

    In the event of a volcanic eruption the decision to close airspace is based on forecast ash maps, produced using volcanic ash transport and dispersion models. In this paper we quantitatively evaluate the spatial skill of volcanic ash simulations using satellite retrievals of ash from the Eyjafjallajökull eruption during the period from 7-16 May 2010. We find that at the start of this period, 7-10 May, the model (FLEXPART) has excellent skill and can predict the spatial distribution of the satellite retrieved ash to within 0.5°× 0.5° lat/lon. However, on the 10 May there is a decrease in the spatial accuracy of the model, to 2.5°× 2.5° lat/lon, and between 11-12 May the simulated ash location errors grow rapidly. On the 11 May ash is located close to a bifurcation point in the atmosphere, resulting in a rapid divergence in the modeled and satellite ash locations. In general, the model skill reduces as the residence time of ash increases. However, the error growth is not always steady. Rapid increases in error growth are linked to critical points in the ash trajectories. Ensemble modeling using perturbed meteorological data would help to represent this uncertainty and assimilation of satellite ash data would help to reduce uncertainty in volcanic ash forecasts.

  11. Past, present and future glacier variations of southeast Vatnajökull, Iceland

    NASA Astrophysics Data System (ADS)

    Hannesdóttir, H.; Björnsson, H.; Pálsson, F.

    2009-04-01

    Icelandic glaciers are sensitive to climate change and provide important climatic information through variations in mass balance and extent. The small non-surging outlet glaciers in East-Skaftafellssýsla are located in the warmest and wettest area of Iceland. The documentary record of glacier variations and detailed information about glacier geometry is unique for studying the response of glaciers to climate change. Data on the extent, bedrock and surface topography of outlet glaciers of southeast Vatnajökull, along with meteorological data, will be used to study the connection of glacier variations and climate change and tune models. The response of the glaciers to prescribed climate scenarios will be modeled. Runoff changes of glacial rivers will be evaluated in relation to past, current and future changes in glacier geometry. The project is part of a research program at the Earth Science Institute which aims at modeling the response of glaciers in Iceland to climate change. The project involved mapping well-preserved glacial deposits from the Little Ice Age (LIA) maximum, including end and lateral moraines, trimlines and shorelines. It is evident that these glaciers have thinned 100-200 m since the LIA maximum. Historical accounts and personal communication indicate that the outlet glaciers were most extensive in the middle of the 18th century and in the period 1870-1890. Comparison of maps from the 20th century has revealed changes in volume and surface extent of the outlet glaciers.

  12. Aerosol formation in basaltic lava fountaining: Eyjafjallajökull volcano, Iceland

    NASA Astrophysics Data System (ADS)

    Ilyinskaya, Evgenia; Martin, Robert S.; Oppenheimer, Clive

    2012-10-01

    A short-lived episode of basaltic lava fountaining at Eyjafjallajökull volcano (March - April 2010) produced a low-altitude, ash-poor plume. We measured the composition of aerosol particles (sampled using a cascade impactor and filter packs), gases (sampled using filter packs), and volatile species scavenged by scoria and external water in order to investigate the formation and speciation of near-source aerosol (<2 min from emission). Samples were analyzed for volatile species (S, Cl and F) and metals (Na, K, Ca and Mg). The aerosol mass showed two unusual features: the prevalent size mode was finer than typically found in volcanic plumes (˜0.2μm, compared to >0.4 μm), and its composition was dominated by chloride rather than sulfate. We used two thermodynamic equilibrium models (E-AIM and HSC Chemistry v5.1) to show that the formation of particulate Cl- by condensation of HCl gas is more responsive to changes in ambient temperature than the oxidation of SO2 to SO42-, so that a low SO42-/Cl- ratio in aerosol particles is characteristic of volcanic emissions in cold climates. Field measurements suggested that the efficiency of SO2 to SO42- conversion inside the vent increased with lower explosivity. Volatiles adsorbed on the surface of scoria had significantly higher SO42-/halogen molar ratios than the aerosol samples. Several potential explanations for these differences are discussed.

  13. The 2010 eruption of Eyjafjallajökull: Lightning and plume charge structure

    NASA Astrophysics Data System (ADS)

    Behnke, S. A.; Thomas, R. J.; Edens, H. E.; Krehbiel, P. R.; Rison, W.

    2014-01-01

    Six Lightning Mapping Array (LMA) stations were deployed in April 2010 around Eyjafjallajökull volcano in southern Iceland. Single-station LMA observations were made during the first explosive period (14-18 April), and three-dimensional LMA observations were made during the second explosive period (5-22 May). The single-station observations revealed that continuous RF electrical activity caused by high rates of small vent discharges occurred during the first explosive period, but not the second, indicating that the strength of vent charging varied between the first and second explosive periods. During the second explosive period, very little lightning was detected between 5 and 10 May, while moderate rates of lightning were detected between 11 and 21 May, signaling that another change occurred on 11 May that affected plume electrification. The data do not make clear if it was changing eruptive activity or changing meteorological activity that resulted in the sudden onset of lightning. The plume charge structure during the second explosive period was inferred from the three-dimensional lightning data, showing that the dominant charge structure varied between a positive monopole and a negative-over-positive dipole. The predominance of a low-altitude region of positive charge and the observation that electrical activity was concentrated near the vent indicate that net positive vent charging was dominating the electrification.

  14. Variations in hydration within perlitised rhyolitic lavas—evidence from Torfajökull, Iceland

    NASA Astrophysics Data System (ADS)

    Denton, J. S.; Tuffen, H.; Gilbert, J. S.

    2012-04-01

    Perlitic fractures form due to the hydration of glassy, rhyolitic lavas. Perlitised lavas are also an important industrial commodity yet there has been little study on the mechanisms of outcrop perlitisation. Here the fracture populations, perlitisation and volatile concentrations of subglacial rhyolitic glassy facies have been studied adding a quantitative dimension to previous qualitative studies. Samples include hyaloclastite, perlitised and non-perlitised obsidian and microcrystalline rhyolite, which are all present in lava lobes at Torfajökull, Iceland. Fractures formed through cooling increase in spacing with increased distance inwards from the margins of lobes. The size distribution of perlitic beads is shown to follow a log-normal distribution. The degree of perlitisation and the total volatile content (measured using thermogravimetric analysis, TGA) of samples are shown to decrease with distance inwards from lobe margins. In general, increased perlitisation is accompanied by increased hydration although complexity exists within single outcrops. The elevated total volatile content of perlite is shown to be due to hydration by environmental water with the structural location of the water changing as total volatile content increases.

  15. The impact of volcanic aerosols on the energy- and mass balance of Langjökull ice cap, SW-Iceland

    NASA Astrophysics Data System (ADS)

    Gudmundsson, S.; Pálsson, F.; Björnsson, H.; Magnússon, E.; Thorsteinsson, T.; Haraldsson, H. H.

    2012-12-01

    The mass balance of the Langjökull ice cap in SW-Iceland has been monitored since 1997. Since the summer 2001 two automatic weather stations (AWSs) have been used to estimate the full energy balance of the glacier surface; one near to the terminus the other close to ELA. Following the subglacial eruptions in the Eyjafjallajökull volcano 14 April to 22 May 2010, and Grímsvötn volcano 21 - 28 May 2011, airborne tephra was deposited on the surface of all the major ice caps in Iceland. The mass balance and AWS records for Langjökull provide valuable data to study the impact of aerosol deposition on albedo and radiative forcing. Here we compare the mass- and energy balance of the Langjökull ice cap during the exceptional circumstances of 2010 and 2011 to the more climatically controlled mass- and energy balance of 1997-2009. Dark tephra from the 2010 Eyjafjallajökull eruption, deposited on Langjökull 18-19 May (3-4 days before the eruption stopped), produced a thin layer of fine grained dark trachyandesite tephra particles on the surface (fraction of a mm). This highly reduced the surface albedo and greatly enhanced melting, especially within the accumulation area, where up to three years of accumulation melted. The resulting negative net balance in 2010 was threefold the average during the preceding warm decade. In 2011, basalt tephra dust from the Grímsvötn eruption was deposited on Langjökull (on 11 June, 2 weeks after the end of the eruption, deposited by wind). The quantity of dust was less than in 2010, and the color of the basaltic tephra particles not as dark, hence smaller reduction in albedo. The weather during the summer 2011 was not favorable to ablation on Langjökull; exceptionally cold period from early May to mid June with occasional snowfall, delayed the start of the ablation season by 3 weeks compared to typical years. Thus, despite the lower albedo, causing fast melt rates after 11 June, the total summer ablation was close to the average

  16. THE 1890 SURGE END MORAINE AT EYJABAKKAJÖKULL, ICELAND: A RE-ASSESSMENT OF A CLASSIC GLACIOTECTONIC LOCALITY

    NASA Astrophysics Data System (ADS)

    Benediktsson, I.; Schomacker, A.; Lokrantz, H.; Ingolfsson, O.

    2009-12-01

    This study reveals the glaciotectonic architecture and sequential evolution of the Eyjabakkajökull 1890 surge end moraines in Iceland. Based on morphological, geological and geophysical data from terrain cross-profiles, cross-sections and ground penetrating radar profiles, we demonstrate that three different models are required to explain the genesis of the Eyjabakkajökull moraines. Firstly, a narrow, single crested moraine ridge at the distal end of a marginal sediment wedge formed in response to decoupling of the subglacial sediment from the bedrock and associated downglacier sediment transport. Secondly, large lobate end-moraine ridges with multiple, closely spaced, narrow asymmetric crests formed by proglacial piggy-back thrusting. Thirdly, a new model shows that moraine ridges with different morphologies may reflect different members of an end-moraine continuum. This is true for the eastern and western parts of the Eyjabakkajökull moraines as they show similar morphological and structural styles which developed to different degrees. The former represents an intermediate member with décollement at 4-5 m depth and 27-33% shortening through multiple open anticlines that are reflected as moderately spaced symmetric crests on the surface. The latter represents an end member with décollement at about 27 m depth and 39% horizontal shortening through multiple high amplitude, overturned and overthrusted anticlines, appearing as broadly spaced symmetric crests. We propose that the opposite end member would be a moraine of multiple symmetric, wide open anticlinal crests of low amplitude. Our data suggest that the glacier coupled to the foreland to initiate the end-moraine formation when it had surged to within 70-190 m of its terminal position. This indicates a time frame of 2-6 days for the formation of the end moraines.

  17. Dynamics of three outlet glaciers on the Vatnajökull ice cap reconstructed through landsystem analysis

    NASA Astrophysics Data System (ADS)

    Maclachlan, John; Lee, Rebecca; Eyles, Carolyn

    2016-04-01

    Landsystem analysis uses genetically related landform-sediment assemblages, known as landsystem tracts, as evidence in the reconstruction of the geomorphic evolution of a landscape and subsequently provides further insight into the morphogenetic record. When used in conjunction with sedimentological data, results from this methodology are used to inform models of the subglacial conditions through the movement characteristics of the overriding glacier. Ultimately landsystem analysis allows modern systems to be used as analogues for ancient systems, which in turn facilitates more accurate paleoenvironmental reconstruction of ancient glacial sediments. The proglacial till plains, consisting of subglacial, proglacial and supraglacial sediments and landforms of three outlet glaciers of the Vatnajökull Ice Cap in southeast Iceland were explored using a combination of remote sensing techniques, geospatial analysis and field investigations. The three glaciers selected for study (Svínafellsjökull, Skaftafellsjökull and Morsárjökull) are separated by small mountain ridges but lie within close spatial proximity, limiting climatic variability on their behavior but allowing for variability in local influences such as variability in valley morphology. Although the three glaciers are sourced by the same ice cap and are within close proximity there are wide variations in the type, distribution and scale of landforms in the proglacial region including the presence of streamlined features, the relative relief of the landforms, and sediment types. Initial mapping of the proglacial region of each glacier was performed using geospatial software to explore and analyze LiDAR data and aerial imagery obtained from the Icelandic Meteorological Office. A high-resolution digital elevation model (DEM) of the proglacial region of each glacier was created from these remotely sensed data to illustrate the spatial distribution and scale of landforms. These features were ground-checked using

  18. Observations of Eyjafjallajökull eruption's plume at Potenza EARLINET station

    NASA Astrophysics Data System (ADS)

    Mona, Lucia; Amodeo, Aldo; Boselli, Antonella; Cornacchia, Carmela; D'Amico, Guiseppe; Giunta, Aldo; Madonna, Fabio; Pappalardo, Gelsomina

    2010-05-01

    Eyjafjallajökull is one of the smallest glacier in Iceland. After seismic activity recorded during December 2009, a first eruption started on 20 March, between 22:30 and 23:30 UT. After a brief stop, a new phase of the Eyjafjallajökull eruption started around midnight on April 14, where melt penetrated its way to the central crater beneath the glacier. An eruption plume was observed in the early morning on 14 April. Ash loaded eruption plume rose to more than 8 km height, deflected to the East by westerly winds. Eruptive activity continued in the following days until 23 April with variable maximum height (between 8 and 2 km a.s.l.). Until 27 April, a plume is always visible in proximity of the volcano. On 15 April, the eruption plume reaches continental Europe with closure of airspace over large part of Northern Europe. In the following days, airspace was closed also in some regions of Southern Europe. On 15 April, 10:00 UT CNR-IMAA, Potenza distributed an alert to EARLINET stations informing about a large amount of ash is directing towards North-West of Europe. Even if EARLINET is not an operational, but research oriented, network, almost all the EARLINET stations followed the event performing measurements whenever weather conditions allow it. Because of their proximity to the source, England and Scandinavian countries are of course the most involved in the transported ash arrival. Accordingly to the MetOffice forecasts, the ash plume would have to reach Central Europe on 16 April. The transport toward South was almost blocked by the Alps. A different scenario is forecasted by MetOffice for 20-21 April when the arrival of the volcanic plume is forecasted down to the Southern Italy. At CNR-IMAA, the atmospheric observatory (CIAO) followed the event by means of all available instruments, including EARLINET multi-wavelength lidars, cloud-radar, microwave profiler and AERONET sun-photometer. Low clouds and rain did not permit measurements over Potenza for the period

  19. SEVIRI 4D-var assimilation analysing the April 2010 Eyjafjallajökull ash dispersion

    NASA Astrophysics Data System (ADS)

    Lange, Anne Caroline; Elbern, Hendrik

    2016-04-01

    We present first results of four dimensional variational (4D-var) data assimilation analysis applying SEVIRI observations to the Eulerian regional chemistry and aerosol transport model EURAD-IM (European Air Pollution Dispersion - Inverse Model). Optimising atmospheric dispersion models in terms of volcanic ash transport predictions by observations is especially essential for the aviation industry and associated interests. Remote sensing satellite observations are instrumental for ash detection and monitoring. We choose volcanic ash column retrievals of the Spinning Enhanced Visible and Infrared Imager (SEVIRI) because as infrared instrument on the geostationary satellite Meteosat Second Generation it delivers measurements with high temporal resolution during day and night. The retrieval method relies on the reverse absorption effect. In the framework of the national initiative ESKP (Earth System Knowledge Platform) and the European ACTRIS-2 (Aerosol, Clouds, and Trace gases Research InfraStructure) project, we developed new modules (forward and adjoint) within the EURAD-IM, which are able to process SEVIRI ash column data as observational input to the 4D-var system. The focus of the 4D-var analysis is on initial value optimisation of the volcanic ash clouds that were emitted during the explosive Eyjafjallajökull eruption in April 2010. This eruption caused high public interest because of air traffic closures and it was particularly well observed from many different observation systems all over Europe. Considering multiple observation periods simultaneously in one assimilation window generates a continuous trajectory in the phase space and ensures that past observations are considered within their uncertainties. Results are validated mainly by lidar (LIght Detection And Ranging) observations, both ground and satellite based.

  20. Changes in the southeast Vatnajökull ice cap, Iceland, between ~ 1890 and 2010

    NASA Astrophysics Data System (ADS)

    Hannesdóttir, H.; Björnsson, H.; Pálsson, F.; Aðalgeirsdóttir, G.; Guðmundsson, Sv.

    2015-03-01

    Area and volume changes and the average geodetic mass balance of the non-surging outlet glaciers of the southeast Vatnajökull ice cap, Iceland, during different time periods between ~ 1890 and 2010, are derived from a multi-temporal glacier inventory. A series of digital elevation models (DEMs) (~ 1890, 1904, 1936, 1945, 1989, 2002, 2010) are compiled from glacial geomorphological features, historical photographs, maps, aerial images, DGPS measurements and a lidar survey. Given the mapped basal topography, we estimate volume changes since the end of the Little Ice Age (LIA) ~ 1890. The variable volume loss of the outlets to similar climate forcing is related to their different hypsometry, basal topography, and the presence of proglacial lakes. In the post-LIA period, the glacierized area decreased by 164 km2 (or from 1014 to 851 km2) and the glaciers had lost 10-30 % of their ~ 1890 area by 2010 (anywhere from 3 to 36 km2). The glacier surface lowered by 150-270 m near the terminus and the outlet glaciers collectively lost 60 ± 8 km3 of ice, which is equivalent to 0.15 ± 0.02 mm of sea-level rise. The volume loss of individual glaciers was in the range of 15-50%, corresponding to a geodetic mass balance between -0.70 and -0.32 m w.e. a-1. The annual rate of mass change during the post-LIA period was most negative in 2002-2010, on average -1.34 ± 0.12 m w.e. a-1, which is among the most negative mass balance values recorded worldwide in the early 21st century.

  1. Characterization of Eyjafjallajökull volcanic ash particles and a protocol for rapid risk assessment

    PubMed Central

    Gislason, S. R.; Hassenkam, T.; Nedel, S.; Bovet, N.; Eiriksdottir, E. S.; Alfredsson, H. A.; Hem, C. P.; Balogh, Z. I.; Dideriksen, K.; Oskarsson, N.; Sigfusson, B.; Larsen, G.; Stipp, S. L. S.

    2011-01-01

    On April 14, 2010, when meltwaters from the Eyjafjallajökull glacier mixed with hot magma, an explosive eruption sent unusually fine-grained ash into the jet stream. It quickly dispersed over Europe. Previous airplane encounters with ash resulted in sandblasted windows and particles melted inside jet engines, causing them to fail. Therefore, air traffic was grounded for several days. Concerns also arose about health risks from fallout, because ash can transport acids as well as toxic compounds, such as fluoride, aluminum, and arsenic. Studies on ash are usually made on material collected far from the source, where it could have mixed with other atmospheric particles, or after exposure to water as rain or fog, which would alter surface composition. For this study, a unique set of dry ash samples was collected immediately after the explosive event and compared with fresh ash from a later, more typical eruption. Using nanotechniques, custom-designed for studying natural materials, we explored the physical and chemical nature of the ash to determine if fears about health and safety were justified and we developed a protocol that will serve for assessing risks during a future event. On single particles, we identified the composition of nanometer scale salt coatings and measured the mass of adsorbed salts with picogram resolution. The particles of explosive ash that reached Europe in the jet stream were especially sharp and abrasive over their entire size range, from submillimeter to tens of nanometers. Edges remained sharp even after a couple of weeks of abrasion in stirred water suspensions. PMID:21518890

  2. Glacier retreat and projected river regime changes in the hydrologically highly-coupled Virkisjökull catchment, Iceland

    NASA Astrophysics Data System (ADS)

    Flett, Verity; Kirkbride, Martin; Black, Andrew; Everest, Jez; MacDonald, Alan

    2016-04-01

    Virkisjökull, an outlet glacier of the Oræfajökull icecap in SE Iceland, currently has 60% glacier cover, though this is reducing due to glacier retreat. Intensive monitoring over the last 4 years includes measurement of measuring ice ablation, proglacial discharge, dye-tracing of flow pathways, and deployment of three automatic weather stations at altitudes up to 880 m. These data calibrate a distributed hydrological model (WaSIM) to project potential river regime during stages of glacier retreat. Results show: (1) glacier hypsometry sensitises the catchment to a disproportionately rapid increase in runoff as the snowline rises onto a gentle ice cap resulting in in a potential annual increase in river discharge of up to 37% (2) a dominantly channelized glacial drainage system in all seasons with a rapid runoff response to melt: englacial flow of 0.58 m s-1 is comparable to the proglacial river velocity; and (3) longer-term, reduced glacier cover and snow storage will lead to a discharge regime dominated by short-term precipitation events in all seasons, and a reduced influence of the seasonal meltwater discharge peak. The study demonstrates the importance of glacier hypsometry above the present ELA as an influence on catchment hydrological response to potential climate warming.

  3. Smectites and zeolites in ash from the 2010 summit eruption of Eyjafjallajökull volcano, Iceland

    NASA Astrophysics Data System (ADS)

    Paque, M.; Detienne, M.; Maters, E. C.; Delmelle, P.

    2016-09-01

    Hydrothermal alteration minerals are often incorporated in volcanic ash from phreatic and phreatomagmatic activity. Here we assess the presence and abundance of such minerals in the ash materials produced during the April-May 2010 initial phreatomagmatic ( phase I) and subsequent magmatic ( phases II and III) eruptions of Eyjafjallajökull volcano, Iceland. The results of X-ray diffraction analyses reveal significant quantities of smectites (up to 4 wt%, mainly as saponite) and zeolites (up to 7 wt%) in ash from phase I. While a minor amount of smectites (<0.5 wt%) is present in ash from the subsequent weak explosive activity ( phase II), both smectites and zeolites are absent in phase III ash. This material was generated following abrupt rejuvenation of explosive activity in the absence of magma-ice/water interaction. Smectites and zeolites in phase I ash result primarily from scouring of altered volcanic rocks in the subsurface, although some may derive also from water-rock interaction within the summit ice cauldrons through which fragmented magma was injected. We show that incorporation of smectites and zeolites in phase I ash can explain its anomalously high specific surface area. Further, the presence of these minerals in ash may enhance its ability to act as ice nuclei as well as favour particle aggregation processes in the volcanic plume/cloud. Finally, the Eyjafjallajökull eruption represents another case in which ash fallout acted as an exogenic source of 2:1-type clay minerals in volcanic soils.

  4. 3D-ambient noise Rayleigh wave tomography of Snæfellsjökull volcano, Iceland

    NASA Astrophysics Data System (ADS)

    Obermann, Anne; Lupi, Matteo; Mordret, Aurélien; Jakobsdóttir, Steinunn S.; Miller, Stephen A.

    2016-05-01

    From May to September 2013, 21 seismic stations were deployed around the Snæfellsjökull volcano, Iceland. We cross-correlate the five months of seismic noise and measure the Rayleigh wave group velocity dispersion curves to gain more information about the geological structure of the Snæfellsjökull volcano. In particular, we investigate the occurrence of seismic wave anomalies in the first 6 km of crust. We regionalize the group velocity dispersion curves into 2-D velocity maps between 0.9 and 4.8 s. With a neighborhood algorithm we then locally invert the velocity maps to obtain accurate shear-velocity models down to 6 km depth. Our study highlights three seismic wave anomalies. The deepest, located between approximately 3.3 and 5.5 km depth, is a high velocity anomaly, possibly representing a solidified magma chamber. The second anomaly is also a high velocity anomaly east of the central volcano that starts at the surface and reaches approximately 2.5 km depth. It may represent a gabbroic intrusion or a dense swarm of inclined magmatic sheets (similar to the dike swarms found in the ophiolites), typical of Icelandic volcanic systems. The third anomaly is a low velocity anomaly extending up to 1.5 km depth. This anomaly, located directly below the volcanic edifice, may be interpreted either as a shallow magmatic reservoir (typical of Icelandic central volcanoes), or alternatively as a shallow hydrothermal system developed above the cooling magmatic reservoir.

  5. Effects of Eyjafjallajökull Volcanic Ash on Innate Immune System Responses and Bacterial Growth in Vitro

    PubMed Central

    Baltrusaitis, Jonas; Powers, Linda S.; Borcherding, Jennifer A.; Caraballo, Juan C.; Mudunkotuwa, Imali; Peate, David W.; Walters, Katherine; Thompson, Jay M.; Grassian, Vicki H.; Gudmundsson, Gunnar; Comellas, Alejandro P.

    2013-01-01

    Background: On 20 March 2010, the Icelandic volcano Eyjafjallajökull erupted for the first time in 190 years. Despite many epidemiological reports showing effects of volcanic ash on the respiratory system, there are limited data evaluating cellular mechanisms involved in the response to ash. Epidemiological studies have observed an increase in respiratory infections in subjects and populations exposed to volcanic eruptions. Methods: We physicochemically characterized volcanic ash, finding various sizes of particles, as well as the presence of several transition metals, including iron. We examined the effect of Eyjafjallajökull ash on primary rat alveolar epithelial cells and human airway epithelial cells (20–100 µg/cm2), primary rat and human alveolar macrophages (5–20 µg/cm2), and Pseudomonas aeruginosa (PAO1) growth (3 µg/104 bacteria). Results: Volcanic ash had minimal effect on alveolar and airway epithelial cell integrity. In alveolar macrophages, volcanic ash disrupted pathogen-killing and inflammatory responses. In in vitro bacterial growth models, volcanic ash increased bacterial replication and decreased bacterial killing by antimicrobial peptides. Conclusions: These results provide potential biological plausibility for epidemiological data that show an association between air pollution exposure and the development of respiratory infections. These data suggest that volcanic ash exposure, while not seriously compromising lung cell function, may be able to impair innate immunity responses in exposed individuals. PMID:23478268

  6. Full Wavefield Numerical Simulations of Sub-glacial Seismic Tremor at Vatnajökull Glacier, Iceland

    NASA Astrophysics Data System (ADS)

    Ying, Yingzi; Eibl, Eva P. S.; Bean, Christopher J.; Vogfjörd, Kristin; Pálsson, Finnur

    2015-04-01

    The volcanic systems, including the central volcanoes Bárðarbunga and Grimsvötn in South-East Iceland lie beneath the Vatnajökull glacier and are covered by up to 700 m of ice. This ice layer inhibits the recording of the seismic signal close to the source and acts as a wave guide, significantly modifying the seismic wavefield. Recordings of local earthquakes or tremor will therefore be modified by a potentially strong and unknown path effect. We tackle this problem with full wavefield numerical simulations, (2D and 3D) using the Spectral Element method. This allows for the introduction of viscoelasticity in the sub-surface geology and captures all wave conversions and scattering. We employ a 3D model of the glacier thickness and subglacial topography and insert a source wavelet at different depths and locations in order to simulate the wavefield recorded at the location of the field seismometers, in the region of Vatnajökull. Furthermore we calculate sensitivity kernels which show us which part of the model creates a specific part of the simulated seismogram, yielding a deeper understanding of tremor seismogram composition. Our findings show that path effects play a very significant role in determining the overall character of the tremor wavefield and must be removed or suppressed in order to gain a better understanding of the tremor source process itself.

  7. A 300 Year Surge History of the Drangajökull Ice Cap, Northwest Iceland: Surge Frequency and Little Ice Age Maximum

    NASA Astrophysics Data System (ADS)

    Brynjolfsson, S.; Schomacker, A.; Ingolfsson, O.; Gudmundsdottir, E. R.

    2014-12-01

    Over the last 300 years, each of the three surge-type outlet glaciers of the Drangajökull ice cap in north-west Iceland has surged 2-4 times. There is valuable historical information available on the surge frequencies since the Little Ice Age (LIA) maximum because of the proximity of the surging outlets, Reykjarfjarðarjökull, Leirufjarðarjökull and Kaldalónsjökull to farms and pastures. We have reconstructed the surge history of the Drangajökull ice cap, based on geomorphological mapping, sedimentary studies and review of historical records. Geomorphological mapping of the glacier forefields revealed twice as many end-moraines than previously recognized. This indicates a higher surge frequency than previously perceived. A clear relationship between the surge frequency and climate cannot be established, however, surges were more frequent during the 19th century and the earliest 20th century compared to the cool 18th century and the warmer late part of the 20th century. We have estimated the magnitude of the LIA maximum surge events by reconstruction of Digital Elevation Models (DEMs) that can be compared with modern DEMs. As reference points for the digital elevation modelling we used the recently mapped lateral moraines and historical information on the exposure timing of nunataks. During the LIA maximum surge events the outlet glaciers extended 3-3.5 km further down-valley than at present. Their ice volumes were at least 2-2.5 km3 greater than after their most recent surges in the beginning of the 21st century.

  8. Geomorphology and the Little Ice Age extent of the Drangajökull ice cap, NW Iceland, with focus on its three surge-type outlets

    NASA Astrophysics Data System (ADS)

    Brynjólfsson, Skafti; Schomacker, Anders; Ingólfsson, Ólafur

    2014-05-01

    Detailed geomorphological maps from the forefields of three surging outlets of the Drangajökull ice cap, northwest Iceland, are presented. The maps are based on field studies in 2011-2013, high resolution orthorectified aerial photographs recorded in 2005-2006, and airborne LiDAR data from 2011. The maps cover an area of about 40-60 km2 each. Furthermore, we present an overview map that covers the area surrounding the Drangajökull ice cap. Landforms and sediments were manually registered in a geographic information system (ESRI ArcGIS 10). We mapped glacial landforms such as flutes, ice-sculpted bedrock, hummocky moraine, kame terraces, and moraines. Fluvial landforms include outwash plains/sandur, pitted sandur, and eskers. In addition raised beaches were mapped. The Little Ice Age (LIA) maximum extent of Drangajökull and its outlet glaciers are fingerprinted by surficial till deposits and freshly glacially scoured bedrock. Sediments distal to the LIA deposits were recorded and consist mainly of late Weichselian and early Holocene sediments and locally weathered bedrock. Periglacial activity is demonstrated by patterned ground, mainly occurring on the 500-700 m high plateaux, and three rock glaciers. At least 3-4 surge events are described from each of the outlet glaciers, occurring over the last three centuries. In contrast to most other surge-type outlets from Icelandic ice caps, the Drangajökull outlets are confined within valleys, which affect the forefield geomorphology. Glaciofluvial landforms, moraines, and a thin sheet of till with numerous boulders are characteristic for the forefields of the Drangajökull outlets.

  9. Seismogenic ';trapdoors' during magma intrusion at Eyjafjallajökull volcano, Iceland

    NASA Astrophysics Data System (ADS)

    White, R. S.; Tarasewicz, J.; Brandsdottir, B.; Schonnman, C.

    2013-12-01

    Relocated earthquake hypocentres for >1000 microearthquakes that occurred prior to and during the 2010 fissure and summit eruptions of Eyjafjallajökull volcano in Iceland map out magma conduits from the upper mantle (30 km depth) to the surface. During the two weeks prior to the first, flank eruption, hypocentre locations lie predominantly in horizontally separated clusters at 3-4 km below sea level. They represent the filling with magma of an inflating sill beneath the eastern flank of the volcano, from which feeder dykes propagated laterally and vertically toward the flank eruption site three days prior to the eruption onset. The majority of events within some clusters of up to >100 earthquakes exhibit similar waveforms and identical patterns of P-wave first-motion polarities recorded across the monitoring network. In the clearest example, 104 out of 105 events in a single cluster appear to have the same source mechanism based on P-wave first-motion polarities and waveform similarity. These observations suggest that the clusters of similar events may comprise many earthquakes generated by source processes that have the same orientation of failure, perhaps even on the same rupture plane, in fixed locations that are repeatedly active. The epicentral clustering and similarity of source mechanisms suggest that much of the seismicity was generated at approximately static constrictions to magma flow in an inflating sill. These constrictions may act as a form of pressure valve or ';trapdoor' in the country rock, which ruptures when the melt pressure exceeds a critical level, then reseals after a pulse of melt has passed through. We infer that the magmatic intrusion causing the seismicity was likely to be a laterally inflating sill at 3-4 km depth, with seismogenic pinch-points occurring between aseismic compartments of the sill, or between adjacent magma lobes as they inflate. A second eruption followed from the summit, 8 km west of the first eruption site. During the

  10. Optical, microphysical and compositional properties of the Eyjafjallajökull volcanic ash

    NASA Astrophysics Data System (ADS)

    Rocha-Lima, A.; Martins, J. V.; Remer, L. A.; Krotkov, N. A.; Tabacniks, M. H.; Ben-Ami, Y.; Artaxo, P.

    2014-10-01

    Better characterization of the optical properties of aerosol particles are an essential step to improve atmospheric models and satellite remote sensing, reduce uncertainties in predicting particulate transport, and estimate aerosol forcing and climate change. Even natural aerosols such as mineral dust or particles from volcanic eruptions require better characterization in order to define the background conditions from which anthropogenic perturbations emerge. We present a detailed laboratorial study where the spectral optical properties of the ash from the April-May (2010) Eyjafjallajökull volcanic eruption were derived over a broad spectral range, from ultra-violet (UV) to near-infrared (NIR) wavelengths. Samples of the volcanic ash taken on the ground in the vicinity of the volcano were sieved, re-suspended, and collected on filters to separate particle sizes into fine and mixed (coarse and fine) modes. We derived the spectral mass absorption efficiency αabs [m2g-1] for fine and mixed modes particles in the wavelength range from 300 to 2500 nm from measurements of optical reflectance. We retrieved the imaginary part of the complex refractive index Im(m) from αabs, using Mie-Lorenz and T-matrix theories and considering the size distribution of particles obtained by scanning electron microscopy (SEM), and the grain density of the volcanic ash measured as ρ = 2.16 ± 0.13 g cm-3. Im(m) was found to vary from 0.001 to 0.005 in the measured wavelength range. The dependence of the retrieval on the shape considered for the particles were found to be small and within the uncertainties estimated in our calculation. Fine and mixed modes were also analyzed by X-ray fluorescence, exhibiting distinct elemental composition supporting the optical differences we found between the modes. This is a comprehensive and consistent characterization of spectral absorption and imaginary refractive index, density, size, shape and elemental composition of volcanic ash, which will help

  11. A theoretical model of drumlin formation based on observations at Múlajökull, Iceland

    NASA Astrophysics Data System (ADS)

    Iverson, Neal R.; McCracken, Reba; Zoet, Lucas; Benediktsson, Ívar; Schomacker, Anders; Johnson, Mark; Finlayson, Andrew; Phillips, Emrys; Everest, Jeremy

    2016-04-01

    Theoretical models of drumlin formation have generally been developed in isolation from observations in modern drumlin forming environments - a major limitation on the empiricism necessary to confidently formulate models and test them. Observations at a rare modern drumlin field exposed by the recession of the Icelandic surge-type glacier, Múlajökull, allow an empirically-grounded and physically-based model of drumlin formation to be formulated and tested. Till fabrics based on anisotropy of magnetic susceptibility and clast orientations, along with stratigraphic observations and results of ground penetrating radar, indicate that drumlin relief results from basal till deposition on drumlins and erosion between them. These data also indicate that surges cause till deposition both on and between drumlins and provide no evidence of the longitudinally compressive or extensional strain in till that would be expected if flux divergence in a deforming bed were significant. Over 2000 measurements of till density, together with consolidation tests on the till, indicate that effective stresses on the bed were higher between drumlins than within them. This observation agrees with evidence that subglacial water drainage during normal flow of the glacier is through channels in low areas between drumlins and that crevasse swarms, which reduce total normal stresses on the bed, are coincident with drumlins. In the new model slip of ice over a bed with a sinusoidal perturbation, crevasse swarms, and flow of subglacial water toward R-channels that bound the bed undulation during periods of normal flow result in effective stresses that increase toward channels and decrease from the stoss to the lee sides of the undulation. This effective-stress pattern causes till entrainment and erosion by regelation infiltration (Rempel, 2008, JGR, 113) that peaks at the heads of incipient drumlins and near R-channels, while bed shear is inhibited by effective stresses too high to allow

  12. The Eyjafjallajökull eruption in April-May 2010; course of events, ash generation and ash dispersal (Invited)

    NASA Astrophysics Data System (ADS)

    Gudmundsson, M. T.; Thordarson, T.; Hoskuldsson, A.; Larsen, G.; Jónsdóttir, I.; Oddsson, B.; Magnusson, E.; Hognadottir, T.; Sverrisdottir, G.; Oskarsson, N.; Thorsteinsson, T.; Vogfjord, K. S.; Bjornsson, H.; Pedersen, G. N.; Jakobsdottir, S.; Hjaltadottir, S.; Roberts, M. J.; Gudmundsson, G. B.; Zophoniasson, S.; Hoskuldsson, F.

    2010-12-01

    The explosive eruption of the 1660 m high ice-capped Eyjafjallajökull volcano in April-May 2010 was of moderate size but due to high proportions of very fine-grained ash, its 39-day duration, and prevailing southeasterly jetstream, the ash was widely dispersed and caused unprecedented disruption to air traffic over Europe. After a prolonged period of intrusive activity, a small basaltic flank eruption took place on the northeast side of the volcano, lasting from March 20 to April 12, producing 25 million m3 of basalt. The trachyandesite summit eruption began at 1:30 on April 14. Despite thin glacier (200 m), the eruption was subglacial in the first few hours suggesting very low initial magma discharge. An eruption plume rose through the cloudcover above the volcano at 6 AM. Shortly before 7 AM meltwater from the craters in the 2.5 km wide ice-filled caldera emerged from the outlet glacier Gígjökull. Jokulhlaups occurred on April 14 and 15, but none were of sufficient magnitude to cause widespread damage. The intensity of the eruption increased steadily during April 14. Activity was phreatomagmatic, featured a distinctive Vulcanian character and sustained a 6-9 km high (a.s.l.) eruption plume for almost four days. This phase produced high proportions of extremely fine ash, such that the fallout on the surrounding lowlands contained up to 20 wt% of the <10 µm size fraction. In the first two days, a sizeable proportion of the eruption energy went into melting ice, but by April 16 ice melting had become insignificant. On April 17th fallout was especially heavy in the Eyjafjöll district 10-15 km south of the active vents. During this initial four-day period, ash was transported towards south-east and south, resulting in minor ash fallout in Europe. In the days that followed, magma discharge dropped and access of water to the vent was restricted, resulting to mixed magmatic eruption producing both lava and tephra. This phase of mild explosive activity and limited

  13. The resistivity structures around and beneath the Eyjafjallajökull volcano, Southern Iceland: first insides from electromagnetic investigations

    NASA Astrophysics Data System (ADS)

    Miensopust, M. P.; Jones, A. G.; Hersir, G. P.; Vilhjálmsson, A. M.

    2012-04-01

    Due to the recent eruptive and highly disruptive volcanic events in 2010 in Iceland, scientific and societal interest is overwhelming in gaining as much information as possible about the volcanic structures and processes to enhance the understanding of the partially glacier-covered Eyjafjallajökull and Katla volcanic systems. Due to their ice-caps the eruptions of these volcanoes are phreato-magmatic in type and are capable of producing jökulhlaups (or glacier bursts), i.e., sudden glacial outburst floods. Numerous petrological, geochemical and geophysical investigations of these systems have already been published. However, to date no electrical or electromagnetic data have been aquired on these two volcanoes to attempt to image the resistivity structure beneath and around them, although electromagnetic methods are far more sensitive to fluid distribution (in this case partial melt) than any other geophysical method. In July 2011, broadband magnetotelluric (MT) data were collected at 26 sites around the Eyjafjallajökull and the southern part of Mýrdalsjökull (i.e., the glacier covering Katla). Both horizontal electric field components were recorded using 100 m dipoles, and the vertical and both horizontal magnetic field components were measured using induction coils. At most sites the recording time was approximately 40 hours, and a distant remote reference site (about 150 km away) was recording during the whole survey. The obtained period range of good quality data is about 300 Hz to 1,000 - 2,000 s. In addition, at each MT site central loop transient electromagnetic (TEM) data were obtained using a transmitter loop of 200 m x 200 m and a 1 m2 receiver loop with 100 windings (effective area 100 m2). The TEM data are used to correct the MT data for static shift effects. State of the art data processing and analysis methods have been applied to the data and dimensionality and distortion analyses have been conducted. Induction arrow and phase tensor maps as

  14. Ice flow dynamics and mass balance of Vatnajökull outlet glaciers observed by X-band SAR Data

    NASA Astrophysics Data System (ADS)

    Nagler, T.; Rott, H.; Magnússon, E.; Floricioiu, D.; Mueller, F.; Scharrer, K.

    2012-04-01

    Several outlet glaciers of the major ice caps in Iceland are affected by sub-glacial outburst floods, so-called jökulhlaups. Sources of these outbreaks are water accumulations beneath the glacier due to geothermal or volcanic activity. One component of the project NorthHydrology, carried out within the ESA STSE (Support to Science Element) programme, addresses techniques and applications of satellite data for studying drainage mechanisms and water outbreaks of sub-glacial lakes in Iceland. Such events are usually related to surface deformation and changes in ice velocities, sometimes occurring already well ahead of the peak of the flood wave. High resolution repeat pass SAR data are able to deliver spatially detailed information on surface motion and displacement, which are highly relevant for advancing the understanding of glacier hydraulics and jökulhlaup processes. A template matching technique is applied to data stacks of TerraSAR-X and Cosmo-SkyMed amplitude images acquired between summer 2008 to summer 2010 in order to study the ice dynamics and mass balance of outlet glaciers of Vatnajökull in Iceland. This technique requires distinct and stable surface features, as usually available on ice surfaces of glaciers. Main outlet glaciers, investigated in the project, are Breidamerkurjökull and Skeiderarjökull, with the fronts terminating close to the coast. The lower terminus of these glaciers exhibits significant melting during summer, and sometimes even during winter. At these glaciers in-situ data on ice velocity and surface elevation changes have been recorded at in situ GPS stations, operated by University of Iceland. The ice motion field was derived using ascending and descending repeat pass SAR images. In order to retrieve the 3D ice motion vector, effects of surface melt are taken into account by modelling the ablation. Combining maps of displacement shifts from ascending and descending passes and compensating for surface lowering due to melt, maps

  15. New land, new opportunitites. Vegetation succession and soil formation within the heterogenous moraines formed by the Skaftafellsjökull and Breiðamerkurjökull outlet glaciers in Southeast Iceland.

    NASA Astrophysics Data System (ADS)

    Vilmundardóttir, Olga K.; Gísladóttir, Guðrún; Lal, Rattan

    2016-04-01

    Retreating glaciers expose heterogenous landscapes where primary vegetation succession becomes active. These glacier forelands are excellent sites to study the effects of landscape on vegetation establishment and the commencing soil formation. Where the location of the glacier terminus is known in time, a chronosequence can be established, thus allowing for assessing the role of time on both vegetation succession and soil development. In Iceland, glaciers have been more or less retreating since the end of the Little Ice Age in ~1890, exposing thick moraines mostly composed of ground basaltic material of volcanic origin. In a research from southeast Iceland, soil formation was studied in front of two outlet glaciers, Skaftafellsjökull and Breiðamerkurjökull, and the developing soil properties analyzed with regards to the age of the surface, vegetation, avifauna and topography. At Skaftafellsjökull, soils were sampled along three moraines of known age. The vegetation was dominated by mosses but dwarf shrubs and shrubs (willows and birch) characterized the older moraines. Vegetation cover and plant group cover was affected by the profile position (summit, shoulder, backslope, footslope, toeslope) and the shape of the topographic features (ridge, slope, depression). The cover was significantly greater in toeslopes and footslopes when compared to the backslopes and featured significantly more shrub cover. The vegetation cover was significantly denser in depressions than on ridges and slopes, predominantly comprising mosses and shrubs. On the other hand, macro-lichens predominated on ridges. The vegetation cover and soil properties showed the strongest relation between total vegetation cover, cover of mosses, macro-lichens and dwarf shrubs. The concentration of SOC, N and ammonium oxalate extractable Al increased significantly with increase in vegetation cover and showed similar trends of increase in the cover by mosses, macro-lichens and dwarf shrubs. Profile

  16. Fractionation and Mobility of Thallium in Volcanic Ashes after Eruption of Eyjafjallajökull (2010) in Iceland.

    PubMed

    Karbowska, Bozena; Zembrzuski, Wlodzimierz

    2016-07-01

    Volcanic ash contains thallium (Tl), which is highly toxic to the biosphere. The aim of this study was to determine the Tl concentration in fractions of volcanic ash samples originating from the Eyjafjallajökull volcano. A sequential extraction scheme allowed for a study of element migration in the environment. Differential pulse anodic stripping voltammetry using a flow measuring system was selected as the analytical method to determine Tl content. The highest average content of Tl in volcanic ash was determined in the fraction entrapped in the aluminosilicate matrix (0.329 µg g(-1)), followed by the oxidizable fraction (0.173 µg g(-1)). The lowest content of Tl was found in the water soluble fraction (0.001 µg g(-1)); however, this fraction is important due to the fact that Tl redistribution among all the fractions occurs through the aqueous phase. PMID:27209545

  17. Using a two-step matrix solution to reduce the run time in KULL's magnetic diffusion package

    SciTech Connect

    Brunner, T A; Kolev, T V

    2010-12-17

    Recently a Resistive Magnetohydrodynamics (MHD) package has been added to the KULL code. In order to be compatible with the underlying hydrodynamics algorithm, a new sub-zonal magnetics discretization was developed that supports arbitrary polygonal and polyhedral zones. This flexibility comes at the cost of many more unknowns per zone - approximately ten times more for a hexahedral mesh. We can eliminate some (or all, depending on the dimensionality) of the extra unknowns from the global matrix during assembly by using a Schur complement approach. This trades expensive global work for cache-friendly local work, while still allowing solution for the full system. Significant improvements in the solution time are observed for several test problems.

  18. The 2010 Eyjafjallajökull volcanic summit eruption: evidences from ash-leachates analysis and ground deposition fluxes

    NASA Astrophysics Data System (ADS)

    Bagnato, E.; Aiuppa, A.; Bertagnini, A.; Bonadonna, C.; Cioni, R.; Pedone, M.; Pistolesi, M.

    2012-04-01

    The Eyjafjallajökull 2010 eruption was an extraordinary event in that it led to widespread over Europe. Volcanic processes which lead to eruptions can be investigated by monitoring a variety of parameters, including the composition of ash leachates. Fine-grained tephra erupted from active vents, and transported through volcanic plumes, can adsorbs, and therefore rapidly scavenge, volatile elements such as S, halogens, and metal species in the form of soluble salts adhering to ash surfaces. Analysis of such water-soluble phases is a suitable complement for the remote sensing of volcanic gases at inaccessible volcanoes, like Eyjafjallajökull. The 2010 Eyjafjallajökull eruption developed in four main phases, whose difference in gas chemistry and products has been marked in ash-leachates data too. The recurrent ash fallout provided a unique opportunity to characterize the compositional features of ash leachates, and to identify their relation (if any) with the eruptive activity styles of the volcano. By these considerations, we report on the chemical composition of leachates of 20 volcanic ash samples deposited during the most explosive Eyjafjallajökull activities (from 14 April to 8 May) and during the lava fountaining event (on 26th March 2010). We found that ash-leachate solutions are dominated - among cations - by Na and Ca, while they display nearly equal S : Cl : F abundances (mean S/Cl and S/F molar ratios of 0.85 and 0.33, respectively), as characteristic of divergent-plate and within-plate volcanism. The strong correlations between leached Ca - F , Ca - SO4, and Na - Cl (r2 = 0.7 - 0.9), suggest that fluorite, anhydrite, and halite are the most likely soluble surface minerals formed in the plume (and therefore leached during our experiments), as also reported at many active volcanoes. Our data bring evidence for variations in S and halogens proportions, with samples from 5 - 8th May which show the highest S/Cl and lowest Cl/F ratios. By combining the

  19. Fractionation and Mobility of Thallium in Volcanic Ashes after Eruption of Eyjafjallajökull (2010) in Iceland.

    PubMed

    Karbowska, Bozena; Zembrzuski, Wlodzimierz

    2016-07-01

    Volcanic ash contains thallium (Tl), which is highly toxic to the biosphere. The aim of this study was to determine the Tl concentration in fractions of volcanic ash samples originating from the Eyjafjallajökull volcano. A sequential extraction scheme allowed for a study of element migration in the environment. Differential pulse anodic stripping voltammetry using a flow measuring system was selected as the analytical method to determine Tl content. The highest average content of Tl in volcanic ash was determined in the fraction entrapped in the aluminosilicate matrix (0.329 µg g(-1)), followed by the oxidizable fraction (0.173 µg g(-1)). The lowest content of Tl was found in the water soluble fraction (0.001 µg g(-1)); however, this fraction is important due to the fact that Tl redistribution among all the fractions occurs through the aqueous phase.

  20. Time Scale of Gas Accumulation before the 2010 Eyjafjallajökull Eruption (Iceland) from 210Po Radioactive Excess

    NASA Astrophysics Data System (ADS)

    Sigmarsson, O.

    2015-12-01

    The 2010 mildly explosive eruption at Eyjafjallajökull, Iceland, produced mingled tephra of benmoreitic and trachytic composition whereas alkali basalt was emitted during preceding flank eruption. Tephra of the first explosive phase are composed of three glass types, alkaline rhyolite, mixed benmoreite, and basalt. The early formed benmoreitic tephra (erupted on 15 and 17 April 2010) had large 210Po in excess of 210Pb [(210Po/210Pb)0= 1.88)] at the time of eruption, and possibly a small 210Pb excess over its parent 226Ra. In contrast, the preceding flank eruption produced basalt with (210Po)0 = 0, upon eruption, and the final trachyte (end of May 2010) had lost most of its 210Po during open-system degassing. The 210Po excess in the first erupted benmoreites is interpreted to result from 210Po degassing of basaltic magma and the accumulation of 210Po-enriched gas, either in the upper part of the basaltic intrusion, below the rhyolite-basalt interface, on in the pre-existing residual rhyolitic magma chamber. A model of radon and polonium accumulation in the rhyolitic reservoir, allows calculating the ratio of mass of basalt magma degassing over mass of magma accumulating excess gas. This ratio decreased from 20 to 15 over 2 days, implying zoned magma reservoir, with the uppermost and gas-richest part erupted first. The duration of pre-eruptive gas accumulation in this model is approximately one year. This corresponds closely to the initiation of a seismic swarm beneath Eyjafjallajökull, early June 2009, which was the first pre-eruptive signal detected. The coincidence between initiation of gas accumulation at relatively shallow depth and deeper seismicity strongly suggests that the excess gas phase originated from a basalt magma batch intruded at depth, and that this gas phase reached the surface approximately a year later.

  1. The 2010 Eyjafjallajökull and 2011 Grimsvötn ash plumes as seen by GPS

    NASA Astrophysics Data System (ADS)

    Grapenthin, R.; Hreinsdottir, S.; Gudmundsson, M. T.

    2015-12-01

    The injection of a volcanic plume introduces a dynamic, localized, short-term heterogeneity in the atmosphere. Satellite-imagery based remote sensing techniques provide good spatial coverage for the detection of such plumes, but slow satellite repeat times (>30 minutes) and cloud cover can delay, if not entirely prevent, the detection. GPS, in turn, provides excellent temporal coverage, but requires favorable satellite-station-geometry such that the signal propagates through the plume if it is to be used for plume detection and analysis. Two methods exist to detect / analyze ash plumes with GPS: (a) Ash-heavy plumes result in signal dispersion and hence a lowered signal-to-noise ratio (SNR). A lowered SNR, recorded by some receivers, can provide useful information about the plume, such as location and velocity of ascent. These data can be evaluated directly as they are recorded by the receiver; without the need of solving for a receiver's position. (b) Wet plumes refract the GPS signals piercing the plume and hence induce a propagation delay. When solving for a receiver position GPS analysis tools do not model this localized phase delay effect and solutions for plume-piercing satellites do not fit the data well. This can be exploited for plume analysis such as the estimation of changes to the atmospheric refractivity index. We analyze GPS data of the ~2 month 2010 Eyafjallajökull erption and the week-long 2011 Grímsvötn eruption to infer a first order estimate of plume geometry and its progression. Using SNR and phase delay information, we evaluate the evolution of the partitioning of wet versus dry parts of the plume. During the GPS processing we iteratively solve for phase-delay and position and fix other parameters, hence reducing the mapping of least-squares misfit into position estimates and other parameters. Nearly continuous webcam imagery provides independent observations of first-order plume characteristics for the Eyafjallajökull event.

  2. Seismogenic magma intrusion before the 2010 eruption of Eyjafjallajökull volcano, Iceland

    NASA Astrophysics Data System (ADS)

    Tarasewicz, J.; White, R. S.; Brandsdóttir, B.; Schoonman, C. M.

    2014-08-01

    We present relatively relocated earthquake hypocentres for >1000 microearthquakes (ML < 3) that occurred during the 2 weeks immediately prior to the 2010 March 20 fissure eruption at Fimmvörðuháls on the flank of Eyjafjallajökull volcano in Iceland. Our hypocentre locations lie predominantly in horizontally separated clusters spread over an area of 10 km2 and approximately 4 km below sea level (5 km below the surface). Seismic activity in the final 4 d preceding the eruption extended to shallower levels <2 km below sea level and propagated to the surface at the Fimmvörðuháls eruption site on the day the eruption started. We demonstrate using synthetic data that the observed apparent ˜1 km vertical elongation of seismic clusters is predominantly an artefact caused by only small errors (0.01-0.02 s) in arrival time data. Where the signal-to-noise ratio was sufficiently good to make subsample arrival time picks by cross-correlation of both P- and S-wave arrivals, the mean depth of 103 events in an individual cluster were constrained to 3.84 ± 0.06 km. Epicentral locations are significantly less vulnerable to arrival time errors than are depths for the seismic monitoring network we used. Within clusters of typically 100 recorded earthquakes, most of the arrivals exhibit similar waveforms and identical patterns of P-wave first-motion polarities across the entire monitoring network. The clusters of similar events comprise repetitive sources in the same location with the same orientations of failure, probably on the same rupture plane. The epicentral clustering and similarity of source mechanisms suggest that much of the seismicity was generated at approximately static constrictions to magma flow in an inflating sill complex. These constrictions may act as a form of valve in the country rock, which ruptures when the melt pressure exceeds a critical level, then reseals after a pulse of melt has passed through. This would generate recurring similar source

  3. Profiling of fine and coarse particle mass: case studies of Saharan dust and Eyjafjallajökull/Grimsvötn volcanic plumes

    NASA Astrophysics Data System (ADS)

    Ansmann, A.; Seifert, P.; Tesche, M.; Wandinger, U.

    2012-10-01

    The polarization lidar photometer networking (POLIPHON) method introduced to separate coarse-mode and fine-mode particle properties of Eyjafjallajökull volcanic aerosols in 2010 is extended to cover Saharan dust events as well. Furthermore, new volcanic dust observations performed after the Grimsvötn volcanic eruptions in 2011 are presented. The retrieval of particle mass concentrations requires mass-specific extinction coefficients. Therefore, a review of recently published mass-specific extinction coefficients for Saharan dust and volcanic dust is given. Case studies of four different scenarios corroborate the applicability of the profiling technique: (a) Saharan dust outbreak to central Europe, (b) Saharan dust plume mixed with biomass-burning smoke over Cape Verde, and volcanic aerosol layers originating from (c) the Eyjafjallajökull eruptions in 2010 and (d) the Grimsvötn eruptions in 2011. Strong differences in the vertical aerosol layering, aerosol mixing, and optical properties are observed for the different volcanic events.

  4. Post-Little Ice Age (1891-2011 AD) volume loss of Kotárjökull glacier, southeastern Iceland, as established from historical photography

    NASA Astrophysics Data System (ADS)

    Gudmundsson, Snaevarr; Hannesdóttir, Hrafnhildur; Björnsson, Helgi

    2013-04-01

    Kotárjökull is one of several outlet glaciers draining the ice-covered central volcano Öræfajökull in SE-Iceland. We estimate the average annual specific mass loss of the glacier, to be 0.22 m (water equivalent)over the post Little Ice Age period 1891-2011. The glacial recession corresponds to an areal decrease of 2.7 km2 (20%) and a volume loss of 0.4 km3 (30%). A surface lowering of 180 m is observed near the snout decreasing to negligible amounts above 1700 m elevation. This minimal surface lowering at high altitudes is supported by a comparison of the elevation of trigonometrical points on Öræfajökull's plateau from the Danish General Staff map of 1904 and a recent LiDAR-based digital elevation model. Our estimates are derived from a) three pairs of photographs from 1891 and 2011, b) geomorphological field evidence delineating the maximum glacier extent at the end of the Little Ice Age, and c) the high-resolution digital elevation model from 2010- 2011. The historical photographs of Frederick W.W. Howell from 1891 were taken at the end of the Little Ice Age in Iceland, thus providing a reference of the maximum glacier extent.

  5. Tracking the seismicity preceding and during the March 2010 Fimmvörduháls fissure eruption and April 2010 summit eruption of Eyjafjallajökull, Iceland

    NASA Astrophysics Data System (ADS)

    Tarasewicz, J.; Brandsdottir, B.; Hensch, M.; White, R. S.

    2010-12-01

    Using Coalescence Microseismic Mapping (CMM) we have located over 9,000 earthquakes in the period starting two weeks prior to the Fimmvörduháls fissure eruption at the northeastern margin of the Eyjafjallajökull stratovolcano, South Iceland. CMM is an automatic earthquake detection and location program developed at Cambridge University which performs a search in time and space for a best-fit earthquake location. This is done by migrating both P and S wave energy from each seismometer location back into the subsurface and finding an optimum event location where the back-projected energy coalesces within a specified search volume by fitting it to a grid for which P- and S-wave travel times have been calculated from each point in the grid to every seismometer. Following a prolonged period of escalating seismicity we deployed six temporary, three-component, broadband seismometers around the Eyjafjallajökull volcano on 5th March 2010. Data from these seismometers were augmented by data from the eight closest seismometers of the permanent network operated by the Icelandic Meteorological Office (IMO). During March 2010, sustained seismic activity was concentrated primarily between 3-6 km depth under the northeastern flank of the Eyjafjallajökull volcano. To first order, the seismicity migrated eastwards away from the Eyjafjallajökull caldera and towards the first eruption site at Fimmvörduháls during the two weeks prior to eruption. We attribute this to melt movement within the crust. However, clusters in three (or more) discrete locations on the northeastern flank are observed to have been active simultaneously, or with activity alternating between locations, suggesting that magma movement was more complex than a single dyke propagating towards the Fimmvörduháls eruption site. Seismic activity decreased markedly in the two days prior to the onset of the fissure eruption on March 20th. The fissure eruption continued until 12th April and was a pre-cursor to the

  6. Residents' attitudes and behaviour before and after the 2010 Eyjafjallajökull eruptions—a case study from southern Iceland

    NASA Astrophysics Data System (ADS)

    Bird, Deanne K.; Gísladóttir, Guðrún

    2012-08-01

    While the disruption to international air travel caused by the eruption of Iceland's Eyjafjallajökull volcano in 2010 has been well documented, the significant social impacts on local residents from ash fall to the south and east of the crater are less well-known. These impacts and attitudes of impacted residents and emergency managers are the foci of our present study. Prior to and during the eruption, officials worked to protect the local population from the glacial outburst floods (jökulhlaup) that were of primary concern. The success of these endeavours can in part be attributed to a regional evacuation exercise held in March 2006, an exercise that was carried out with respect to a possible eruption at another volcano, Katla, that is located 25 km to the east of Eyjafjallajökull. Eruptions at either volcano will impact the same communities. Our study here concentrates on Álftaver, a small farming community, located approximately 60 km east-southeast of Eyjafjallajökull and 30 km southeast of Katla. Álftaver has been the subject of longitudinal studies carried out in 2004, 2006, and 2008; these studies highlighted the difficulties that emergency managers face in developing appropriate response strategies acceptable to vulnerable communities. The 2010 Eyjafjallajökull eruptions presented an opportunity to re-assess residents' attitudes and behaviour in relation to volcanic risk management in the wake of their first-hand experiences with volcanic hazards. To achieve this, interviews were conducted with residents and emergency management officials and a questionnaire was distributed to residents. This paper presents the results of this survey and examines changes in attitudes towards volcanic risk management. It was apparent that the experience of ash fall from Eyjafjallajökull provided a better perspective of what could be expected from a Katla eruption and that attitudes towards emergency management had evolved accordingly. Importantly, officials

  7. Volcanic-Ash Hazards to Aviation—Changes and Challenges since the 2010 Eruption of Eyjafjallajökull, Iceland

    NASA Astrophysics Data System (ADS)

    Guffanti, M.; Tupper, A.; Mastin, L. G.; Lechner, P.

    2012-12-01

    In response to the severe disruptions to civil aviation that resulted from atmospheric transport of ash from the eruption of Eyjafjallajökull volcano in Iceland in April and May 2010, the International Civil Aviation Organization (ICAO) quickly formed the International Volcanic Ash Task Force (IVATF), charging it to support the accelerated development of a global risk-management framework for volcanic-ash hazards to aviation. Recognizing the need for scientifically based advice on best methods to detect ash in the atmosphere and depict zones of hazardous airspace, the IVATF sought input from the global scientific community, primarily by means of the Volcanic Ash Scientific Advisory Group which was established in May 2010 by the World Meteorological Organization (WMO) and International Union of Geodesy and Geophysics to serve as a scientific resource for ICAO. The IVATF finished its work in June 2012 (see http://www.icao.int/safety/meteorology/ivatf/Pages/default.aspx for a record of its results). A major science-based outcome is that production of charts depicting areas of airspace expected to have specific ash-concentration values (e.g. <0.2, 0.2-2, 2-4, >4 mg/cu. m) will not be required of the world's nine Volcanic Ash Advisory Centers (VAACs). The VAACs are responsible for issuing warning information to the aviation sector regarding ash-cloud position and expected movement. Forecast concentrations in these charts are based primarily on dispersion models that have at least an order of magnitude in uncertainty in their output and therefore do not delineate hazardous airspace with the level of confidence needed by the aviation sector. The recommended approach to improving model-forecast accuracy is to assimilate diverse observations (e.g., satellite thermal-infrared measurements, lidar, radar, direct airborne sampling, visual sightings, etc.) into model simulations; doing that during an eruption in the demanding environment of aviation operations is a substantial

  8. Why do models predict such large ash clouds? An investigation using data from the Eyjafjallajökull eruption, Iceland

    NASA Astrophysics Data System (ADS)

    Mastin, L. G.; Schwaiger, H.; Denlinger, R. P.

    2010-12-01

    The 2010 eruption of Eyjafjallajökull volcano, Iceland caused unprecedented disruption of European air operations and a rethinking of current practices on avoidance of volcanic ash by aircraft. During eruptions, Volcanic Ash Advisory Centers (VAACs) are responsible for tracking and communicating ash-cloud location and movement to the aviation community. VAACs rely on numerical models to forecast ash-cloud movement, but models tend to predict larger ash clouds than are observed in satellite images, suggesting sometimes unnecessarily large areas of hazard. This discrepancy led to controversy during the Eyjafjallajökull eruption as pressure to open airspace increased and sporadic airborne measurements failed to find ash at some locations where models predicted it. We compare ash-cloud model simulations from our new Eulerian finite-volume model, Ash3d, with satellite, air, and ground-based measurements obtained by others during the Eyjafjallajökull eruption. Our objective is to examine the discrepancy between observed and modeled ash-cloud size and to consider possible causes. We used wind data from the NOAA Global Forecast System model, and modeled the period April 14-16 2010 using a plume height of 10 km, eruption rate of 2.5×10^4 kg/s, and a single grain size having fall velocity of 0.01 m/s. We did not calculate diffusion, meaning that all downwind widening of the plume occurred through wind advection and “numerical diffusion”, an artifact in which ash is smeared across cells in the model. Our model results are similar to others that have been publicly released. On April 16, satellite images show the migration of an east-west-oriented crescent-shaped, concave-northward cloud from southern Norway and Sweden southward toward Poland and Germany. By 1800UT, the cloud extended from near the German-Dutch border across the Czech Republic toward the northeast corner of Poland—an area of ~1×10^5 km^2 where ash load exceeded 0.1 T/km^2. In contrast, the modeled

  9. Using the 2010 Eyjafjallajökull eruption as an example of citizen involvement in scientific research

    NASA Astrophysics Data System (ADS)

    Klemetti, E. W.

    2010-12-01

    With the dramatic increase in realtime data for volcano monitoring (and many other earth science data) available on the internet, the interest in data analysis and observation by untrained citizens is increasing rapidly. These volcanologic data sources include, but are not limited to, seismic information, webicorders, webcams, GPS, water and gas fluxes. The easy access to these data has allowed not only for the public to see the raw data that volcanologists use to assess and predict activity of a volcanic system, but also to actively participate in the process of volcano monitoring. This can be manifested in activities such observation of the changes in volcanic behavior via webcams to manipulation of seismic data to analyze for changes in the character of the seismicity. However, the biggest challenge for citizen analysis and participation in volcano monitoring is providing guidance and structure for these data as they are presented on the internet. The 2010 eruption of Eyjafjallajökull in Iceland provided an opportunity to observe and develop a community of “citizen scientists” interested in volcano monitoring on the internet. The readers of the volcano blog Eruptions followed the pre-, during and post-eruptive activity at Eyjafjallajökull while providing observations and data interpretations as time-stamped comments. During the eruption, the blog was viewed over 1,000,000 times and over 3,000 comments were left by readers. Many of these comments contained: (1) detailed descriptions of the current activity of the volcano as observed on the webcams; (2) observations on changes in seismicity as seen in realtime data provided by the Icelandic Meteorological Office and (3); reader-created compilations of various data in the form of images, tables of movies. By moderating the blog comments and providing corrections and insight to their observations, the readers felt that they were participating in an important way to the monitoring and recording of this historic

  10. Excess 210Po in 2010 Eyjafjallajökull tephra (Iceland): Evidence for pre-eruptive gas accumulation

    NASA Astrophysics Data System (ADS)

    Sigmarsson, Olgeir; Condomines, Michel; Gauthier, Pierre-Jean

    2015-10-01

    Excess gas phase in magmas erupting explosively is well known worldwide. However, the origin of this gas phase, in excess of what can be dissolved in the erupting magma at depth, and the rate of gas accumulation is less well defined. The 2010 mildly explosive eruption at Eyjafjallajökull, Iceland, produced mingled tephra of benmoreitic and trachytic composition whereas alkali basalt was emitted during preceding flank eruption. Tephra of the first explosive phase are composed of three glass types, alkaline rhyolite, mixed benmoreite, and basalt, which suggests that the basaltic magma intruded a pre-existing rhyolitic magma chamber, and ultimately triggered the eruption. The mixed benmoreitic tephra (erupted on 15 and 17 April 2010) had large 210Po in excess of 210Pb [(210Po /210Pb) 0 = 1.88 ] at the time of eruption, and possibly a small 210Pb excess over its parent 226Ra. In contrast, the preceding flank eruption produced basalt with (210Po) 0 = 0, upon eruption, and the final trachyte had lost most of its 210Po during open-system degassing. The 210Po excess in the first erupted benmoreites is interpreted to result from 210Po degassing of basaltic magma and the accumulation of 210Po-enriched gas, either in the upper part of the basaltic intrusion, below the rhyolite-basalt interface, or in the pre-existing residual rhyolitic magma chamber. From a simple model of radon and polonium accumulation in the rhyolitic reservoir, the ratio of the mass of basalt magma degassing over the mass of magma accumulating the excess gas decreased from 20 to 15 over 2 days, implying zoned magma reservoir, with the uppermost and gas-richest part erupting first. The duration of pre-eruptive gas accumulation in this model is approximately one year. This corresponds closely to the initiation of a seismic swarm beneath Eyjafjallajökull, early June 2009, which was the first pre-eruptive signal detected. The coincidence between initiation of gas accumulation at relatively shallow depth and

  11. Public and Media Communication of Volcanic Hazard Before and During the 2010 Eruption in Eyjafjallajökull, Iceland

    NASA Astrophysics Data System (ADS)

    Gylfason, A. G.; Gudmundsson, M. T.; Jakobsdottir, S.; Reynisson, V.

    2010-12-01

    The 39 day long explosive eruption in Eyjafjallajökull was the largest natural hazard event in Iceland for decades. It began with a small flank eruption in March, but the main event was the explosive summit eruption. The flooding that resulted from melting of ice at the eruption site posed considerable danger for the local population, fallout of ash made conditions south of the volcano difficult for several weeks, threatening the future of farming in this rural area, and lead to unprecedented disruption to air traffic in Europe and the North Atlantic. About 800 people were evacuated in a hurry three times during these events because of imminent flood hazard, but fortunately no dwellings were damaged and people could usually return to their homes the same day. These events called for extensive media coverage, both locally and internationally. Some staff at research institutes had for several days to devote their time exclusively to giving interviews to the international media. Scientific communication with the local population was mainly conducted through four channels: (1) the web pages of institutions, (2) the national media; (3) indirectly at meetings on the status of the eruption with local and national officials, and (4) public meetings in the affected areas. In addition the scientific community issued daily status reports to the Department of Civil Protection and Emergency Management, these reports served both national and local Civil Protection officials when preparing their statements on the eruption and answer basic questions from the media. During media communication, it is important to stick to facts, avoid speculation and use plain language without scientific jargon. However, the most critical part of the communication occurred in the years before the eruption through meetings with the local inhabitants. At these meetings the results of a detailed hazard assessment on eruptions in Eyjafjallajökull and the neighboring ice-filled Katla caldera where

  12. In situ physical and chemical characterisation of the Eyjafjallajökull aerosol plume in the free troposphere over Italy

    NASA Astrophysics Data System (ADS)

    Sandrini, S.; Giulianelli, L.; Decesari, S.; Fuzzi, S.; Cristofanelli, P.; Marinoni, A.; Bonasoni, P.; Chiari, M.; Calzolai, G.; Canepari, S.; Perrino, C.; Facchini, M. C.

    2014-01-01

    Continuous measurements of physical and chemical properties at the Mt. Cimone (Italy) GAW-WMO (Global Atmosphere Watch, World Meteorological Organization) Global Station (2165 m a.s.l.) have allowed the detection of the volcanic aerosol plume resulting from the Eyjafjallajökull (Iceland) eruption of spring 2010. The event affected the Mt. Cimone site after a transport over a distance of more than 3000 km. Two main transport episodes were detected during the eruption period, showing a volcanic fingerprint discernible against the free tropospheric background conditions typical of the site, the first from April 19 to 21 and the second from 18 to 20 May 2010. This paper reports the modification of aerosol characteristics observed during the two episodes, both characterised by an abrupt increase in fine and, especially, coarse mode particle number. Analysis of major, minor and trace elements by different analytical techniques (ionic chromatography, particle induced X-ray emission-particle induced gamma-ray emission (PIXE-PIGE) and inductively coupled plasma mass spectrometry (ICP-MS)) were performed on aerosols collected by ground-level discrete sampling. The resulting database allows the characterisation of aerosol chemical composition during the volcanic plume transport and in background conditions. During the passage of the volcanic plume, the fine fraction was dominated by sulphates, denoting the secondary origin of this mode, mainly resulting from in-plume oxidation of volcanic SO2. By contrast, the coarse fraction was characterised by increased concentration of numerous elements of crustal origin, such as Fe, Ti, Mn, Ca, Na, and Mg, which enter the composition of silicate minerals. Data analysis of selected elements (Ti, Al, Fe, Mn) allowed the estimation of the volcanic plume's contribution to total PM10, resulting in a local enhancement of up to 9.5 μg m-3, i.e. 40% of total PM10 on 18 May, which was the most intense of the two episodes. These results appear

  13. Origin of the active drumlin field at Múlajökull, Iceland: New insights from till shear and consolidation patterns

    NASA Astrophysics Data System (ADS)

    McCracken, Reba G.; Iverson, Neal R.; Benediktsson, Ívar Ö.; Schomacker, Anders; Zoet, Lucas K.; Johnson, Mark D.; Hooyer, Thomas S.; Ingólfsson, Ólafur

    2016-09-01

    Stratigraphic and morphologic data previously collected from the forefield of Múlajökull, Iceland, suggest that its recent surge cycles are responsible for the formation of drumlins there and that their relief reflects both deposition on drumlins and erosion between them. We have tested these ideas and aspects of leading models of drumlin formation by studying past patterns of bed deformation and effective stress in basal tills of the glacier's forefield. Patterns of till strain indicated by the anisotropy of magnetic susceptibility (AMS) of ∼2300 intact till samples indicate that till was deposited during shear deformation, with shearing azimuths and planes that conform to the drumlin morphology. Thus, till deposition occurred as drumlins grew, in agreement with LiDAR data indicating that the degree of aggradation of the glacier forefield is largest in areas subjected to the most surges. Previously described unconformities on the drumlin flanks, however, indicate that drumlin relief at Múlajökull has resulted, in part, from erosion. Given that the last surge deposited a till layer both on and between drumlins, a reasonable hypothesis is that erosion between drumlins occurred during normal (quiescent) flow of the glacier between surges. Densities of till samples, analyzed in conjunction with laboratory consolidation tests, indicate that effective stresses on the bed during such periods were on the order of 100 kPa larger between drumlins than within them, an observation consistent with subglacial channels at low water pressure occupying interdrumlin areas. Transport of sediment by turbulent flow in these channels or high effective stress adjacent to them causing enhanced till entrainment in ice or increased depths of bed deformation would promote the sediment flux divergence necessary to erode areas between drumlins. The observation that effective stresses were higher between drumlins than within them is the opposite of that presumed in leading models of

  14. Intrusion Triggering of Explosive Eruptions: Lessons Learned from EYJAFJALLAJÖKULL 2010 Eruptions and Crustal Deformation Studies

    NASA Astrophysics Data System (ADS)

    Sigmundsson, F.; Hreinsdottir, S.; Hooper, A. J.; Arnadottir, T.; Pedersen, R.; Roberts, M. J.; Oskarsson, N.; Auriac, A.; Decriem, J.; Einarsson, P.; Geirsson, H.; Hensch, M.; Ofeigsson, B. G.; Sturkell, E. C.; Sveinbjornsson, H.; Feigl, K.

    2010-12-01

    Gradual inflation of magma chambers often precedes eruptions at highly active volcanoes. During eruptions, rapid deflation occurs as magma flows out and pressure is reduced. Less is known about the deformation style at moderately active volcanoes, such as Eyjafjallajökull, Iceland, where an explosive summit eruption of trachyandesite beginning on 14 April 2010 caused exceptional disruption to air traffic. This eruption was preceded by an effusive flank eruption of olivine basalt from 20 March - 12 April 2010. Geodetic and seismic observations revealed the growth of an intrusive complex in the roots of the volcano during three months prior to eruptions. After initial horizontal growth, modelling indicates both horizontal and sub-vertical growth in three weeks prior the first eruption. The behaviour is attributed to subsurface variations in crustal stress and strength originating from complicated volcano foundations. A low-density layer may capture magma allowing pressure to build before an intrusion can ascend towards higher levels. The intrusive complex was formed by olivine basalt as erupted on the volcano flank 20 March - 12 April; the intrusive growth halted at the onset of this eruption. Deformation associated with the eruption onset was minor as the dike had reached close to the surface in the days before. Isolated eruptive vents opening on long-dormant volcanoes may represent magma leaking upwards from extensive pre-eruptive intrusions formed at depth. A deflation source activated during the summit eruption of trachyandesite is distinct from, and adjacent to, all documented sources of inflation in the volcano roots. Olivine basalt magma which recharged the volcano appears to have triggered the summit eruption, although the exact mode of triggering is uncertain. Scenarios include stress triggering or propagation of olivine basalt into more evolved magma. The trachyandesite includes crystals that can be remnants of minor recent intrusion of olivine basalt

  15. Ash generation and distribution from the April-May 2010 eruption of Eyjafjallajökull, Iceland.

    PubMed

    Gudmundsson, Magnús T; Thordarson, Thorvaldur; Höskuldsson, Armann; Larsen, Gudrún; Björnsson, Halldór; Prata, Fred J; Oddsson, Björn; Magnússon, Eyjólfur; Högnadóttir, Thórdís; Petersen, Guðrún Nína; Hayward, Chris L; Stevenson, John A; Jónsdóttir, Ingibjörg

    2012-01-01

    The 39-day long eruption at the summit of Eyjafjallajökull volcano in April-May 2010 was of modest size but ash was widely dispersed. By combining data from ground surveys and remote sensing we show that the erupted material was 4.8±1.2·10¹¹ kg (benmoreite and trachyte, dense rock equivalent volume 0.18±0.05 km³). About 20% was lava and water-transported tephra, 80% was airborne tephra (bulk volume 0.27 km³) transported by 3-10 km high plumes. The airborne tephra was mostly fine ash (diameter <1000 µm). At least 7·10¹⁰ kg (70 Tg) was very fine ash (<28 µm), several times more than previously estimated via satellite retrievals. About 50% of the tephra fell in Iceland with the remainder carried towards south and east, detected over ~7 million km² in Europe and the North Atlantic. Of order 10¹⁰ kg (2%) are considered to have been transported longer than 600-700 km with <10⁸ kg (<0.02%) reaching mainland Europe.

  16. Eyjafjallajökull and 9/11: the impact of large-scale disasters on worldwide mobility.

    PubMed

    Woolley-Meza, Olivia; Grady, Daniel; Thiemann, Christian; Bagrow, James P; Brockmann, Dirk

    2013-01-01

    Large-scale disasters that interfere with globalized socio-technical infrastructure, such as mobility and transportation networks, trigger high socio-economic costs. Although the origin of such events is often geographically confined, their impact reverberates through entire networks in ways that are poorly understood, difficult to assess, and even more difficult to predict. We investigate how the eruption of volcano Eyjafjallajökull, the September 11th terrorist attacks, and geographical disruptions in general interfere with worldwide mobility. To do this we track changes in effective distance in the worldwide air transportation network from the perspective of individual airports. We find that universal features exist across these events: airport susceptibilities to regional disruptions follow similar, strongly heterogeneous distributions that lack a scale. On the other hand, airports are more uniformly susceptible to attacks that target the most important hubs in the network, exhibiting a well-defined scale. The statistical behavior of susceptibility can be characterized by a single scaling exponent. Using scaling arguments that capture the interplay between individual airport characteristics and the structural properties of routes we can recover the exponent for all types of disruption. We find that the same mechanisms responsible for efficient passenger flow may also keep the system in a vulnerable state. Our approach can be applied to understand the impact of large, correlated disruptions in financial systems, ecosystems and other systems with a complex interaction structure between heterogeneous components. PMID:23950904

  17. Ash generation and distribution from the April-May 2010 eruption of Eyjafjallajökull, Iceland

    PubMed Central

    Gudmundsson, Magnús T.; Thordarson, Thorvaldur; Höskuldsson, Ármann; Larsen, Gudrún; Björnsson, Halldór; Prata, Fred J.; Oddsson, Björn; Magnússon, Eyjólfur; Högnadóttir, Thórdís; Petersen, Guðrún Nína; Hayward, Chris L.; Stevenson, John A.; Jónsdóttir, Ingibjörg

    2012-01-01

    The 39-day long eruption at the summit of Eyjafjallajökull volcano in April–May 2010 was of modest size but ash was widely dispersed. By combining data from ground surveys and remote sensing we show that the erupted material was 4.8±1.2·1011 kg (benmoreite and trachyte, dense rock equivalent volume 0.18±0.05 km3). About 20% was lava and water-transported tephra, 80% was airborne tephra (bulk volume 0.27 km3) transported by 3–10 km high plumes. The airborne tephra was mostly fine ash (diameter <1000 µm). At least 7·1010 kg (70 Tg) was very fine ash (<28 µm), several times more than previously estimated via satellite retrievals. About 50% of the tephra fell in Iceland with the remainder carried towards south and east, detected over ~7 million km2 in Europe and the North Atlantic. Of order 1010 kg (2%) are considered to have been transported longer than 600–700 km with <108 kg (<0.02%) reaching mainland Europe. PMID:22893851

  18. Ash generation and distribution from the April-May 2010 eruption of Eyjafjallajökull, Iceland.

    PubMed

    Gudmundsson, Magnús T; Thordarson, Thorvaldur; Höskuldsson, Armann; Larsen, Gudrún; Björnsson, Halldór; Prata, Fred J; Oddsson, Björn; Magnússon, Eyjólfur; Högnadóttir, Thórdís; Petersen, Guðrún Nína; Hayward, Chris L; Stevenson, John A; Jónsdóttir, Ingibjörg

    2012-01-01

    The 39-day long eruption at the summit of Eyjafjallajökull volcano in April-May 2010 was of modest size but ash was widely dispersed. By combining data from ground surveys and remote sensing we show that the erupted material was 4.8±1.2·10¹¹ kg (benmoreite and trachyte, dense rock equivalent volume 0.18±0.05 km³). About 20% was lava and water-transported tephra, 80% was airborne tephra (bulk volume 0.27 km³) transported by 3-10 km high plumes. The airborne tephra was mostly fine ash (diameter <1000 µm). At least 7·10¹⁰ kg (70 Tg) was very fine ash (<28 µm), several times more than previously estimated via satellite retrievals. About 50% of the tephra fell in Iceland with the remainder carried towards south and east, detected over ~7 million km² in Europe and the North Atlantic. Of order 10¹⁰ kg (2%) are considered to have been transported longer than 600-700 km with <10⁸ kg (<0.02%) reaching mainland Europe. PMID:22893851

  19. Untangling a crystal storm through time: how do 500 diffusion stopwatches inform our view of Eyjafjallajökull 2010?

    NASA Astrophysics Data System (ADS)

    Pankhurst, M. J.; Morgan, D. J.; Thordarson, T.; Loughlin, S.

    2014-12-01

    A new database of 500+ olivine crystal timescales from samples that encompass the duration of the 2010 Fimmvörðuháls-Eyjafjallajökull eruption is presented. We also integrate new petrologic, thermometric and barometric data to read a 4D narrative of the magmatic processes within this volcanic plumbing system preceding­­- and during- eruption. Using this perspective we can identify and semi-quantify magmatic componentry, detect new magmatic inputs, and 'watch' those crystal chemical populations age. We find that major crystal-liquid disequilibrium events occurred up to several years preceding the eruptions, and inputs fed the plumbing system during the eruption window (days - hours). We place timeframes upon processes including magma-mixing, mush remobilization and erosion, and final-ascent quenching and eruption. Fe-Mg binary diffusion in olivine modelling conducted upon this scale was made possible using new advances -also presented here- in both the gathering and processing of raw data, and extraction of timescale information. We demonstrate that this streamlined workflow can now produce statistically robust timescale data within an integrated petrologic and geochemical context that may be resolved alongside independent geophysical and other remote sensing data into a common dimension - time. Transposing petrologic information (record of past process) and geophysical observation (phenomenological in the present) into a common language is designed to produce new understanding of both active and palaeo- volcanic systems, the implications of which we discuss here using our case study as an example.

  20. Eyjafjallajökull and 9/11: The Impact of Large-Scale Disasters on Worldwide Mobility

    PubMed Central

    Woolley-Meza, Olivia; Grady, Daniel; Thiemann, Christian; Bagrow, James P.; Brockmann, Dirk

    2013-01-01

    Large-scale disasters that interfere with globalized socio-technical infrastructure, such as mobility and transportation networks, trigger high socio-economic costs. Although the origin of such events is often geographically confined, their impact reverberates through entire networks in ways that are poorly understood, difficult to assess, and even more difficult to predict. We investigate how the eruption of volcano Eyjafjallajökull, the September 11th terrorist attacks, and geographical disruptions in general interfere with worldwide mobility. To do this we track changes in effective distance in the worldwide air transportation network from the perspective of individual airports. We find that universal features exist across these events: airport susceptibilities to regional disruptions follow similar, strongly heterogeneous distributions that lack a scale. On the other hand, airports are more uniformly susceptible to attacks that target the most important hubs in the network, exhibiting a well-defined scale. The statistical behavior of susceptibility can be characterized by a single scaling exponent. Using scaling arguments that capture the interplay between individual airport characteristics and the structural properties of routes we can recover the exponent for all types of disruption. We find that the same mechanisms responsible for efficient passenger flow may also keep the system in a vulnerable state. Our approach can be applied to understand the impact of large, correlated disruptions in financial systems, ecosystems and other systems with a complex interaction structure between heterogeneous components. PMID:23950904

  1. Volcanic ash transport integrated in the WRF-Chem model: a description of the application and verification results from the 2010 Eyjafjallajökull eruption.

    NASA Astrophysics Data System (ADS)

    Stuefer, Martin; Webley, Peter; Grell, Georg; Freitas, Saulo; Kim, Chang Ki; Egan, Sean

    2013-04-01

    Regional volcanic ash dispersion models are usually offline decoupled from the numerical weather prediction model. Here we describe a new functionality using an integrated modeling system that allows simulating emission, transport, and sedimentation of pollutants released during volcanic activities. A volcanic preprocessor tool has been developed to initialize the Weather Research Forecasting model with coupled Chemistry (WRF-Chem) with volcanic ash and sulphur dioxide emissions. Volcanic ash variables were added into WRF-Chem, and the model was applied to study the 2010 eruption of Eyjafjallajökull. We evaluate our results using WRF-Chem with available ash detection data from satellite and airborne sensors, and from ground based Lidar measurements made available through the AeroCom project. The volcanic ash was distributed into 10 different bins according to the particle size ranging from 2 mm to less than 3.9 μm; different particle size distributions derived from historic eruptions were tested. An umbrella shaped initial ash cloud and an empirical relationship between mass eruption rates and eruption heights were used to initialize WRF-Chem. We show WRF-Chem model verification for the Eyjafjallajökull eruptions, which occurred during the months of April and May 2010. The volcanic ash plume dispersed extensively over Europe. Comparisons with satellite remote sensing volcanic ash retrievals showed good agreement during the events, also ground-based LIDAR compared well to the model simulations. The model sensitivity analysis of the Eyjafjallajökull event showed a considerable bias of ass mass concentrations afar from the volcano depending on initial ash size and eruption rate assumptions. However the WRF-Chem model initialized with reliable eruption source parameters produced good quality forecasts, and will be tested for operational volcanic ash transport predictions.

  2. Integrating Terrestrial Time-Lapse Photography with Laser Scanning to Distinguish the Drivers of Movement at Sólheimajökull, Iceland

    NASA Astrophysics Data System (ADS)

    How, P.; James, M. R.; Wynn, P.

    2014-12-01

    Glacier movement is attributed to a sensitive configuration of driving forces. Here, we present an approach designed to evaluate the drivers of movement at Sólheimajökull, an outlet glacier from the Myrdalsjökull ice cap, Iceland, through combining terrestrial time-lapse photography and laser scanning (TLS). A time-lapse camera (a dSLR with intervalometer and solar-recharged battery power supply) collected hourly data over the summer of 2013. The data are subject to all the difficulties that are usually present in long time-lapse sequences, such as highly variable illumination and visibility conditions, evolving surfaces, and camera instabilities. Feature-tracking software [1] was used to: 1) track regions of static topography (e.g. the skyline) from which camera alignment could be continuously updated throughout the sequence; and 2) track glacial surface features for velocity estimation. Absolute georeferencing of the image sequence was carried out by registering the camera to a TLS survey acquired at the beginning of the monitoring period. A second TLS survey (July 2013) provided an additional 3D surface. By assuming glacial features moved in approximately planimetrically straight lines between the two survey dates, combining the two TLS surfaces with the monoscopic feature tracking allows 3D feature tracks to be derived. Such tracks will enable contributions from different drivers (e.g. surface melting) to be extracted, even in imagery that is acquired not perpendicular to glacier motion. At Sólheimajökull, our aim is to elucidate any volcanic contribution to the observed movement.[1] http://www.lancaster.ac.uk/staff/jamesm/software/pointcatcher.htm

  3. Impact of Ashfalls from Eyjafjallajökull and Grímsvötn Volcanoes on Glacier Ablation on Iceland - a Field Experiment

    NASA Astrophysics Data System (ADS)

    Möller, R.; Möller, M.; Kukla, P. A.; Schneider, C.

    2015-12-01

    The albedo of glaciers may be altered by deposition of light-absorbing aerosols, which consequently has an impact on their energy- and mass balance. Icelandic volcanoes have produced frequent eruptions within the recent past that spread tephra over extensive areas. The glaciers of Iceland are thus an ideal location for studies related to the influence of supraglacial tephra layers on ablation. The two latest subglacial eruptions that induced considerable amounts of ashfall over major Icelandic ice caps were the one of Eyjafjallajökull in April and May 2010 and the one of Grímsvötn in May 2011. The different chemical compositions of the ashes produced by those two eruptions are also noticeable in their distinct thermal properties. In summer 2015, a field experiment was conducted on western Vatnajökull ice cap. In this experiment, the influence of volcanic tephra from both eruptions on surface ablation is monitored by automated measurements. Artificial plots with varying types and thicknesses of tephra were installed on the glacier. Two types of pristine tephra were compared. One was sampled from inside the caldera of Eyjafjallajökull volcano and one from rocky outcrops at the southern caldera rim of Grímsvötn volcano. Tephra thickness across the different artificial plots ranged from 0.5 to 200 mm. The surface ablation on the plots was continuously monitored by automated measurements. For selected plots, additionally changes of the albedo and the temperature profile through the tephra layer were measured. An automatic weather station was set up for continuous meteorological monitoring. We here present first results from this field experiment. Analyses of the overall variability of surface ablation with tephra thickness are shown alongside with indications of dependencies on meteorological conditions, mainly solar radiation and rainfall. Special emphasis is placed on highlighting differences between the effects of the two different types of tephra.

  4. Field constraints for modeling the emplacement of the 2010 Gigjökull lava flow, southern Iceland: interplay between subaqueous, ice contact and subaerial lava emplacement

    NASA Astrophysics Data System (ADS)

    Edwards, B.; Oddsson, B.; Gudmundsson, M. T.; Rossi, R.

    2012-04-01

    One of the least accessible products of the 2010 Eyjafjallajokull eruption is the trachyandesite lava that flowed north from the summit eruption site down through Gigjökull glacier. Based on numerous overflights during 2010, syn-eruption satellite imagery and two on-site investigations in 2011, we have developed a preliminary model to illustrate the progressive movement of the complex lava flow down through Gigjökull. Previous workers have documented the events surrounding the explosive summit eruptions, including the flow path for the majority of the water derived from melting ~0.1 cubic km of summit ice, which moved over, through and beneath Gigjökull producing a series of jokulhlaups during April and May 2010. Overflights in 2010 and 2011 show that most of the upper parts of the lava flow are surfaced by oxidized, blocky lava that appears very similar to what would be expected from an entirely subaerial lava flow. However, exposures at the lowest end of the flow preserve a record documenting lava emplacement in water and through ice tunnels. We describe 8 different components visible in this northernmost, lowest part of the lava flow, including: (1) upper subaerial levee-bounded lava flow, (2) subaerial blocky lava bench, (3) subaqueous/ice contact lava mounds, (4) subaqueous/ice contact sheet lava complex, (5) ponded, glaciolacustrine sediments, (6) subaerial slabby lava flow, (7) subaqueous pillow lava lobes, and (8) ice-tunnel confined lava flows. In combination these 8 components are consistent a model for lava emplacement through a valley glacier. We propose that the lava flow, which appears to have started moving down the glacier from a tephra cone immediately north of the main summit craters after the largest of the jokulhlaups, exploited newly formed and/or pre-existing sub-ice drainage systems along the base of Gigjökull. Initial meltwater from the eruption site created/enhanced basal ice drainage systems. Lava flows exploited these drainage systems

  5. Volcanic unrest primed by ice cap melting: A case study of Snæfellsjökull volcano, Western Iceland

    NASA Astrophysics Data System (ADS)

    Bakker, Richard; Lupi, Matteo; Frehner, Marcel; Berger, Julien; Fuchs, Florian

    2014-05-01

    The most dramatic effect of global warming is the water level rise due to rapid melting of ice sheets. In addition, recent studies suggest that accelerated glacial retreat and associated lithospheric relaxation may enhance upwelling of magmatic fluids through the crust. Here, we investigate whether, also at short geological timescales, shallow magmatic systems may be affected by rapid melting of ice caps. As a case study, we chose the Snæfellsjökull volcanic system in western Iceland, whose ice cap is rapidly melting with 1.25 m(w.e.)/year. To investigate the role of deglaciation in promoting volcanic unrest we use a cross-disciplinary approach integrating geophysical field data, laboratory rheological rock tests, and numerical finite-element analysis. Initial results from seismic data acquisition and interpretation in 2011 show seismic activity (occasionally in swarm sequences) at around a depth range of 8-13 km, indicating the presence of a magmatic reservoir in the crust. In addition, a temporary seismic network of 21 broad-band stations has been deployed in spring 2013 and continuously collected data for several months, which will help better constrain the subsurface geometry. During summer 2013 we collected samples of Tertiary basaltic bedrock from the flanks of Snæfellsjökull, which we assume to be representative for the subsurface volcanic system. Cores drilled from these samples were tri-axially deformed in a Paterson-type apparatus at a constant strain rate of 10-5 s-1, a confining pressure of 50 MPa (i.e. ~2 km depth), and a temperature ranging from 200 °C to 1000 °C (i.e. various proximities to magma chamber). From the obtained stress-strain curves the static Young's modulus is calculated to be around 35 (±2) GPa, which is not significantly influenced by increasing temperatures up to 800 °C. Beyond the elastic domain, cataclastic shear bands develop, accommodating up to 7% strain before brittle failure. The subsurface geometrical constraints from

  6. Airborne lidar observations of volcanic ash during the eruption of Eyjafjallajökull in Spring 2010

    NASA Astrophysics Data System (ADS)

    Marenco, F.; Johnson, B.; Turnbull, K.; Haywood, J.; Newman, S.; Webster, H.; Cooke, M.; Dorsey, J.; Ricketts, H.; Clarisse, L.

    2012-04-01

    The London Volcanic Ash Advisory Centre (VAAC), based at the Met Office, provided forecast guidance for the Civil Aviation Authority during the eruption of Eyjafjallajökull in April-May 2010. Besides providing daily forecasts using the Numerical Atmospheric-dispersion Modelling Environment (NAME), a series of observational activities were carried out by the Met Office, involving ground-based lidars, the exploitation of satellite data, and research flights using the Facility for Airborne Atmospheric Measurements BAe-146 research aircraft (FAAM, www.faam.ac.uk), on which this talk is focused. Due to safety restrictions, aircraft sampling has only been performed in areas where ash concentrations where forecasted to be less than 2000 μg/m3. Volcanic ash layers were observed using an elastic backscatter lidar on-board the FAAM aircraft operating at 355 nm, which allowed detailed mapping of the plumes. A flight on 4 May overpassed the ground-based lidar in Aberystwyth a few times. This provided ground truth validation of the on-board lidar and of its data inversion procedure. The ash layer during this flight was found to be in patches of short horizontal extent, but despite the strong horizontal inhomogeneity the two lidars showed excellent qualitative and quantitative agreement. Moreover, radiative transfer computations using the lidar-derived profiles of aerosol extinction led to a good reconstruction of observed radiance spectra with on-board spectrometers. Aircraft in situ measurements of the particle size-distribution permitted the evaluation of a coarse extinction fraction (ranging 0.5-1) and a coarse mode specific extinction (0.6-0.9 m2/g) for six research flights. These quantities were then used to convert the lidar-derived aerosol extinction to ash concentration (with an estimated uncertainty of a factor of two). The combination of lidar and in-situ sampling of aerosol properties has thus offered us the opportunity to compile a dataset of the airborne

  7. Practical depolarization-ratio-based inversion procedure: lidar measurements of the Eyjafjallajökull ash cloud over the Netherlands.

    PubMed

    Donovan, David Patrick; Apituley, Arnoud

    2013-04-10

    In this paper we present a technique for estimating optical backscatter and extinction profiles using lidar, which exploits the difference between the observed linear volume depolarization ratio at 355 nm and the corresponding expected aerosol-only depolarization ratio. The technique is specific to situations where a single strongly depolarizing species is present and the associated linear particulate depolarization ratio may be presumed to be known to within a reasonable degree of accuracy (on the order of 10%). The basic principle of the technique is extended to deal with situations where a depolarizing fraction is mixed with nondepolarizing aerosol. In general, since the relative depolarization interchannel calibration is much more stable than the absolute system calibration, the depolarization-based technique is easier to implement than conventional techniques that require a profile-by-profile calibration or, equivalently, an identification of aerosol-free altitude intervals. This in particular allows for unattended data analysis and makes the technique well-suited to be part of a broader (volcanic ash) surveillance system. The technique is demonstrated by applying it to the analysis of aerosol layers resulting from the 2010 eruptions of the Eyjafjallajökull volcano in Iceland. The measurements were made at the Cabauw remote-sensing site in the central Netherlands. By comparing the results of the depolarization-based inversion with a more conventional manual inversion procedure as well as Raman lidar results, it is demonstrated that the technique can be successfully applied to the particular case of 355 nm depolarization lidar volcanic ash soundings, including cases in which the ash is mixed with nondepolarizing aerosol. PMID:23670771

  8. Impact of meteorological clouds on detection of volcanic ash during the Eyjafjallajökull 2010 eruption: A modelling study

    NASA Astrophysics Data System (ADS)

    Kylling, Arve

    2014-05-01

    Volcanic ash is commonly detected by infrared detectors in space using various variations of the reverse absorption technique. The reverse absorption technique explores the brightness temperature difference (BTD) between the 10.8 and 12,0 μm regions of the thermal spectrum. Several factors affect the infrared detection of volcanic ash. For a cloudless sky (no ice nor liquid water clouds), the density, altitude (temperature), particle size and shape of the ash cloud and the surface temperature, impact the infrared volcanic ash signature. In the presence of ice and/or liquid water clouds the BTD between 10.8 and 12.0 μm may change. The effect of ice and liquid water clouds on detection of volcanic ash may not readily be made based on experimental methods due to the inherent problem in comparing overcast and cloudless cases and the need for in-situ ice and liquid water cloud information together with volcanic ash information. Thus a model based approach was adopted. Simulated 10.8 and 12.0 μm Spinning Enhanced Visible and Infrared Imager (SEVIRI) images for the full duration of the Eyjafjallajökull 2010 eruption were used as input to standard reverse absorption ash detection methods. Simulation of images were made both with and without realistic water and ice clouds taken from European Centre for Medium-Range Weather Forecast (ECMWF) analysis. The volcanic ash cloud fields were taken from simulations by the Langrangian particle dispersion Flexpart model. The effect of clouds on detection of volcanic ash was highly variable. For situations with large areas affected by ash, up to 40% of pixels with mass loading > 2g/m2 went undetected due to the presence of water and ice clouds.

  9. Ice-volcano interactions during the 2010 Eyjafjallajökull eruption, as revealed by airborne imaging radar

    NASA Astrophysics Data System (ADS)

    Magnússon, E.; Gudmundsson, M. T.; Roberts, M. J.; Sigurã°Sson, G.; HöSkuldsson, F.; Oddsson, B.

    2012-07-01

    During the eruption of the ice-covered Eyjafjallajökull volcano, a series of images from an airborne Synthetic Aperture Radar (SAR) were obtained by the Icelandic Coast Guard. Cloud obscured the summit from view during the first three days of the eruption, making the weather-independent SAR a valuable monitoring resource. Radar images revealed the development of ice cauldrons in a 200 m thick ice cover within the summit caldera, as well as the formation of cauldrons to the immediate south of the caldera. Additionally, radar images were used to document the subglacial and supraglacial passage of floodwater to the north and south of the eruption site. The eruption breached the ice surface about four hours after its onset at about 01:30 UTC on 14 April 2010. The first SAR images, obtained between 08:55 and 10:42 UTC, show signs of limited supraglacial drainage from the eruption site. Floodwater began to drain from the ice cap almost 5.5 h after the beginning of the eruption, implying storage of meltwater at the eruption site due to initially constricted subglacial drainage from the caldera. Heat transfer rates from magma to ice during early stages of cauldron formation were about 1 MW m-2 in the radial direction and about 4 MW m-2 vertically. Meltwater release was characterized by accumulation and drainage with most of the volcanic material in the ice cauldrons being drained in hyperconcentrated floods. After the third day of the eruption, meltwater generation at the eruption site diminished due to an insulating lag of tephra.

  10. Structure of the Grímsvötn central volcano under the Vatnajökull icecap, Iceland

    NASA Astrophysics Data System (ADS)

    Alfaro, Raimon; Brandsdóttir, Bryndís; Rowlands, Daniel P.; White, Robert S.; Gudmundsson, Magnús T.

    2007-02-01

    The subglacial Grímsvötn central volcano, lying within a volcanic zone directly above the core of the Iceland mantle plume, is one of the most active in Iceland. Local, regional and teleseismic earthquake data recorded on a temporary seismometer array across western Vatnajökull icecap during the summer of 1998 have provided a three-dimensional image of the shallow crustal structure of the volcano. Microearthquake activity at depths of 1-4 km along the Grímsvötn caldera rim coincided with inflation of a shallow magma chamber beneath the caldera, which culminated in a 0.1 km3 eruption in December 1998. Tomographic inversion of these earthquakes define the extent of a low-velocity body beneath Grímsvötn with a volume of ~20 km3 extending to ~3 km below the surface. This low-velocity body is flanked by high velocities under the caldera rim. Delays in the P-wave arrival times through the Grímsvötn caldera from regional and teleseismic earthquakes and from two detonations ~150 km east of Grímsvötn are 0.10-0.15 s greater than the delays through the uppermost 3-4 km of crust shown by local earthquake arrivals. This suggests the presence of a further low-velocity body at depths greater than 3-4 km beneath Grímsvötn, presumed to be due to the presence of melt. Using the distribution of local seismicity and shear wave attenuation we estimate the maximum lateral extent of the region containing partial melt to be 7-8 km E-W and 4-5 km N-S. P-wave delays require a thickness of less than 1 km of pure/high percentage partial melt, assuming a sill-like magma chamber.

  11. Complex circular subsidence structures in tephra deposited on large blocks of ice: Varða tuff cone, Öræfajökull, Iceland

    NASA Astrophysics Data System (ADS)

    Smellie, J. L.; Walker, A. J.; McGarvie, D. W.; Burgess, R.

    2016-08-01

    Several broadly circular structures up to 16 m in diameter, into which higher strata have sagged and locally collapsed, are present in a tephra outcrop on southwest Öræfajökull, southern Iceland. The tephra was sourced in a nearby basaltic tuff cone at Varða. The structures have not previously been described in tuff cones, and they probably formed by the melting out of large buried blocks of ice emplaced during a preceding jökulhlaup that may have been triggered by a subglacial eruption within the Öræfajökull ice cap. They are named ice-melt subsidence structures, and they are analogous to kettle holes that are commonly found in proglacial sandurs and some lahars sourced in ice-clad volcanoes. The internal structure is better exposed in the Varða examples because of an absence of fluvial infilling and reworking, and erosion of the outcrop to reveal the deeper geometry. The ice-melt subsidence structures at Varða are a proxy for buried ice. They are the only known evidence for a subglacial eruption and associated jökulhlaup that created the ice blocks. The recognition of such structures elsewhere will be useful in reconstructing more complete regional volcanic histories as well as for identifying ice-proximal settings during palaeoenvironmental investigations.

  12. Deep crescentic features caused by subglacial boulder point pressure on jointed rock; an example from Virkisjökull, SE Iceland

    NASA Astrophysics Data System (ADS)

    Krabbendam, M.; Bradwell, T.; Everest, J.

    2012-04-01

    A variety of subglacially formed, erosional crescentic features (e.g. crescentic gouges, lunate fractures) have been widely reported on deglaciated bedrock surfaces. They are characterised by a conchoidal fracture that dips in the same direction as the palaeo-ice flow direction, and a steeper fracture that faces against the ice flow. They are generally interpreted as being formed by point pressure exerted by large boulders entrained in basal ice. They are significant in that they record palaeo-ice flow even if shallower glacial striae are obliterated by post-glacial weathering [1, 2, 3]. This contribution reports on deep scallop-shaped, crescentic depressions observed on abraded surfaces of roche moutonnées and whalebacks recently (<10yrs) exposed beneath the actively retreating Virkisjökull, an outlet glacier of the Oraefajökull ice cap in southeast Iceland. The substrate comprises hard rhyolitic rock (relatively rare in Iceland compared to more common basalt and hyaloclastite) with polygonal, columnar jointing. The crescentic depressions at Virkisjökull are cut into smoothed, abraded surfaces festooned with abundant glacial striae. Differences with previously reported crescentic features are: • The scallop-shaped depressions are considerably deeper (5-20 cm); • The steep fracture facing ice flow coincides in all cases with a pre-existing joint that cuts the entire whaleback. The steep joints developed thus before the conchoidal fracture, whilst in reported crescentic features they develop after the conchoidal fracture. We suggest the following formation mechanism. A boulder encased in basal ice exerts continuous pressure on its contact point as it moves across the ice-bedrock contact. This sets up a stress field in the bedrock that does not necessarily exceed the intact rock strength (other crescentic features are rare to absent at Virkisjökull). However, as the stress field migrates (with the transported boulder) and encounters a subvertical, pre

  13. Unraveling the Eyjafjallajökull 2010 plumbing system and magma chamber dynamics through high-resolution geochemical investigations

    NASA Astrophysics Data System (ADS)

    Laeger, Kathrin; Petrelli, Maurizio; Andronico, Daniele; Scarlato, Piergiorgio; Cimarelli, Corrado; Misiti, Valeria; del Bello, Elisabetta; Perugini, Diego

    2016-04-01

    The April-May 2010 eruption of the Eyjafjallajökull volcano (EFJ, Iceland) was triggered by an intrusion of fresh magma coming from deeper portions of the crust migrating into shallower depth of 3-6 km in the magmatic system. Here, we present new EMPA and LA-ICP-MS analyses on groundmass glasses of ash particles erupted between 18 and 22 May 2010, the last days of the eruption. The glasses define two well separated groups. The first group is basaltic in composition with SiO2 ranging from 49.98 to 51.76 wt.% and a total alkali content (Na2O + K2O) in the range between 4.63 and 5.17 wt.%. The second group ranges between trachyandesitic and rhyolitic compositions with SiO2 ranging between 57.13 to 70.38 wt.% and a total alkali content from 7.21 to 10.90 wt.%. Least square modelling after Störmer and Nicholls (1978) discriminates best the origin of the basaltic glass by both fractional crystallization of a more primitive basalt or mixing of a basalt and a felsic magma. Furthermore, this model proves that the trachyandesitic range is the result of mixing of trachyandesite and trachyte magma. Magma mixing modeling after Langmuir (1978) and element concentration histograms indicate a probable incomplete magma mixing as the main process forming the great compositional variability observed in the erupted products. Finally, we estimated mixing end-members of intermediate (~59 wt.% SiO2) and felsic composition (~66-68 wt.% SiO2) with a felsic melt-proportion of 0.35-0.47. In the 90s, recorded seismicity and ground deformation indicated intrusions at shallow depth under the EFJ edifice probably forming separated sills. Therefore, the origin of the trachyandesite is presumably to find in a discrete magma batch that generated years before eruption. The rhyolite composition can be considered as the residual melt that remained in the plumbing system of EFJ since the last eruption in 1821-23. We suggest that these different magma batches formed the plumbing system of EFJ and have

  14. Science in Support of Aviation-Risk Management since the April 2010 Eruption of Eyjafjallajökull, Iceland

    NASA Astrophysics Data System (ADS)

    Guffanti, M.; Mastin, L. G.; Schneider, D. J.; Tupper, A.

    2010-12-01

    The nearly week-long airspace closure over large parts of Europe and the North Atlantic in April 2010 that resulted from dispersion of ash from the eruption of Eyjafjallajökull prompted a shift from the accepted global policy of strict avoidance by aircraft of ash-contaminated airspace to one of allowing flight through zones of dilute ash under some circumstances. This shift was made in a crisis environment of rapidly mounting economic losses and social disruptions extending well beyond the European region. To get the global air transportation system moving again, European aviation authorities and associated meteorological offices created a new type of advisory product depicting forecasted zones of low ash concentrations in Eyjafjallajökull’s clouds that could be transited with expectation of no or minimal risk of aircraft damage, under the condition of more frequent aircraft inspections and enhanced risk management by airlines. Preliminary data of the European Aviation Safety Agency indicate that transit through Eyjafjallajökull’s dilute ash clouds caused some wear (primarily abrasion) to a few aircraft, but not to the severity of degraded engine performance in flight; after inspections the aircraft were returned to service and continued to operate without problems. Following the crisis, recognizing that such a fundamental shift in risk management requires sound scientific and engineering bases, the International Civil Aviation Organization (ICAO) formed an International Volcanic Ash Task Force that, in conjunction with the World Meteorological Organization (WMO), will incorporate advice and recommendations from scientific, aviation, and engineering experts worldwide about ways to improve (1) situational awareness to aviation users of impending volcanic eruptions, (2) characterization of critical eruption source parameters for incorporation in forecast modeling, (3) detection and characterization of volcanic clouds, (4) accuracy of volcanic ash transport

  15. 35 yr of stratospheric aerosol measurements at Garmisch-Partenkirchen: from Fuego to Eyjafjallajökull, and beyond

    NASA Astrophysics Data System (ADS)

    Trickl, T.; Giehl, H.; Jäger, H.; Vogelmann, H.

    2013-05-01

    Lidar measurements at Garmisch-Partenkirchen (Germany) have almost continually delivered backscatter coefficients of stratospheric aerosol since 1976. The time series is dominated by signals from the particles injected into or formed in the stratosphere due to major volcanic eruptions, in particular those of El Chichon (Mexico, 1982) and Mt Pinatubo (Philippines, 1991). Here, we focus more on the long-lasting background period since the late 1990s and 2006, in view of processes maintaining a residual lower-stratospheric aerosol layer in absence of major eruptions, as well as the period of moderate volcanic impact afterwards. During the long background period the stratospheric backscatter coefficients reached a level even below that observed in the late 1970s. This suggests that the predicted potential influence of the strongly growing air traffic on the stratospheric aerosol loading is very low. Some correlation may be found with single strong forest-fire events, but the average influence of biomass burning seems to be quite limited. No positive trend in background aerosol can be resolved over a period as long as that observed by lidar at Mauna Loa. We conclude that the increase of our integrated backscatter coefficients starting in 2008 is mostly due to volcanic eruptions with explosivity index 4, penetrating strongly into the stratosphere. Most of them occurred in the mid-latitudes. A key observation for judging the role of eruptions just reaching the tropopause region was that of the plume from the Icelandic volcano Eyjafjallajökull above Garmisch-Partenkirchen (April 2010) due to the proximity of that source. The top altitude of the ash above the volcano was reported just as 9.3 km, but the lidar measurements revealed enhanced stratospheric aerosol up to 14.3 km. Our analysis suggests for two or three of the four measurement days the presence of a stratospheric contribution from Iceland related to quasi-horizontal transport, differing from the strong descent

  16. Duration of gas accumulation before the 2010 Eyjafjallajökull eruption constrained by 210Po-210Pb-226Ra disequilibria

    NASA Astrophysics Data System (ADS)

    Sigmarsson, Olgeir; Gauthier, Pierre-Jean; Condomines, Michel

    2014-05-01

    Excess gas phase in magmas erupting explosively is well known world-wide. However, the origin of this gas phase, in excess of what can be dissolved in the erupting magma at depth, and the duration of gas accumulation, is less well defined. The 2010 mildly explosive eruption at Eyjafjallajökull, Iceland, produced mingled tephra of benmoreiitic and trachytic composition whereas alkali basalt (MgO > 8 %) was emitted during the preceding flank eruption. The silicic tephra of the first explosive phase is composed of three glass types, alkaline rhyolite, mixed benmoreiite, and evolved basalt (MgO < 5 %). The rhyolitic glass is indistinguishable from tephra glass composition emitted during the penultimate eruption of Eyjafjallajökull in 1821-23 AD (Sigmarsson et al., 2011). Tephra from the first explosive phase, emitted on 15 and 17 April, had large 210Po in excess of 210Pb ((210Po/210Pb)0 as high as 2!) and a small, but significant, 210Pb excess over its parent 226Ra ((210Pb/226Ra)0= 1.05 and 1.04, respectively). These excesses suggest rapid accumulation of Po and Rn together with the major gas species in the residual rhyolitic magma from the 1821-23 eruption. The gas most likely originates from the basalt recharge that eventually provoked the eruption. Basalts emitted a month earlier during the flank eruption at Fimmvörðuháls lost all their Po upon eruption and had (210Po/210Pb)0 equal to 0). From a simple model of radon and polonium degassing and accumulation, the mass of basalt magma degassing over the mass of silicic magma accumulating the excess gas can be calculated. Moreover, the duration of gas accumulation can be shown to be close to 300 days. This duration suggests that gas was liberated from the basaltic magma since June 2009, a month that corresponds to the initial seismic swarm beneath Eyjafjallajökull preceding the explosive eruption of 14 April 2010.

  17. The Effects of Vegetation Succession and Landscape on the Evolution of Soil Properties: A Chronosequence Study Along the Proglacial Area of Skaftafellsjökull Glacier, SE Iceland

    NASA Astrophysics Data System (ADS)

    Vilmundardóttir, O. K.; Gísladóttir, G.; Lal, R.

    2014-12-01

    On young soils developing along the recessional path left by the Skaftafellsjökull glacier, SE-Iceland, we investigated the soil development, vegetation succession and landscape representing an age chronosequence of 120 years. In total, 54 sampling sites were distributed along three moraines representing surfaces exposed for 8, 65 and 120 years. For comparison, soil samples were collected from nearby birch woodlands, representing soils in a mature ecosystem likely to establish on the moraines in the future. The youngest moraines were sparsely vegetated with only 10% cover of mosses and grasses. The plant cover increased to 67% after 120 years, and was characterized by mosses (38%), dwarf shrubs (20%) and low growing birch (3.5%). Consequently, the soil formed over 120 years contained 1.1 kg C m-2 in the surface layer (0-10 cm), or about one third of the 3.2 kg C m-2 in soil under the woodlands. The N stock was estimated at 0.06 kg N m-2after 120 yrs, almost one fourth of that under the woodlands. The data suggest that landscape affects vegetation establishment and in turn, both landscape and vegetation affect soil development. Thus, concentrations of soil organic carbon (SOC), N and noncrystalline oxalate extractable Al and Fe were higher within depressions than on ridges and slopes. The comparison of SOC stock in the moraine-derived soils with that under the birch woodlands showed that the young proglacial soils still have a large potential to accrete SOC within the developing pedosphere. With the observed accrual rate of 9.1 g C m-2 yr-1in the top 10 cm, it may take the moraine soils an additional 220 yrs to accrue SOC stocks comparable with those under the birch forest. Given the fact that all Icelandic glaciers are receding, assessing SOC sequestration in new soil formation may be important to off-setting some of anthropogenic emissions. The research is funded by the University of Iceland Doctoral Fund, the University of Iceland Trust Fund, the Landsvirkjun

  18. Monitoring glaciers and indications of subglacial volcanic activity using small-scale Top-Hat reflectors - An IsViews experiment on Myrdalsjökull, Iceland

    NASA Astrophysics Data System (ADS)

    Minet, Christian; Duque Biarge, Sergi; Jaenicke, Julia; Münzer, Ulrich; Mayer, Christoph; Franke, Jonas; Guðmundsson, Águst; Parizzi, Alessandro; Fritz, Thomas; Eineder, Michael

    2014-05-01

    Subglacial volcanic eruptions often provide indications of activity some time before the actual catastrophic event. Surface undulations appear on top of the ice cap and meltwater torrents can occur at the glacier margin. Even large scale uplifts of ice caps have been observed. Within the project IsViews a processing chain, based on high spatially and temporally resolved remote sensing imagery, will be developed in order to automatically identify such early indications. The main data used for this analysis are acquired by the TerraSAR-X, TanDEM-X and RapidEye satellites. First investigations concerning the feasibility of the near real-time warning system and the general baseline conditions are carried out on two large plateau glaciers in southern Iceland, namely Mördalsjökull and Vatnajökull. Within the 2013 IsViews field work an experiment was started in order to test a new way of glacier monitoring. Two test sites were established on the Mördalsjökull ice cap (one at the equilibrium line and one below), each consisting of a permanent GPS station and two nearby RADAR reflectors. These RADAR reflectors are specially designed Top-Hat reflectors, which are cheap to manufacture, small (50 cm diameter) and lightweight and therefore easy to handle, transport and deploy. Their special design makes them visible in SAR images independent of orientation, so different acquisition geometries and even different sensors can be used. The drawback of the small, low reflecting Top-Hat can be overcome by using the newly implemented Staring Spotlight Mode of the German SAR Satellite TerraSAR-X, providing an unprecedented resolution of down to 20 cm in the azimuth direction. The reflectors, as point targets, allow absolute positioning within the cm-level in the TerraSAR-X data. Time series of SAR data can be used to derive position and altitude changes of the reflector itself and possibly even melting rates by exploiting the different signal paths. The visibility of the Top

  19. Production of mildly alkaline basalts at complex ocean ridge settings: Perspectives from basalts emitted during the 2010 eruption at the Eyjafjallajökull volcano, Iceland

    NASA Astrophysics Data System (ADS)

    Viccaro, Marco; Nicotra, Eugenio; Urso, Salvatore

    2015-11-01

    The early phase of the 2010 eruption at the Eyjafjallajökull volcano (Iceland) produced poorly evolved mildly alkaline basalts that have a signature more enriched with respect to the typically depleted basalts emitted at ocean ridges. The whole rock geochemistry of these basaltic magmas offers a great opportunity to investigate the mantle source characteristics and reasons leading to this enriched fingerprint in proximity of the ocean ridge system. Some basaltic products of Katla volcano, ∼25 km east of Eyjafjallajökull, have been chosen from the literature, as they display a similar mildly alkaline signature and can be therefore useful to explore the same target. Major and trace element variations of the whole rock suggest a very limited evolutionary degree for the 2010 Eyjafjallajökull products and the selected Katla magmas, highlighting the minor role played by differentiation processes such as fractional crystallization. Nevertheless, effects of the limited fractionation have been erased through re-equilibration of the major and trace element abundances at primary conditions. Concentrations of Th after re-equilibration have been assumed as indexes of the partial melting degree, given the high incompatibility of the element, and enrichment ratios calculated for each trace element. Especially for LILE (Rb, Ba, K, Sr), the pattern of resulting enrichment ratios well matches that obtained from fractional melting of peridotite bearing hydrous phases (amphibole/phlogopite). This put forward the idea that magmas have been generated through partial melting of enriched mantle domains where hydrous minerals have been stabilized as a consequence of metasomatic processes. Refertilization of the mantle has been attributed to intrusion of hydrous silicate melts and fractional crystallization of hydrous cumulates. These refertilizing melts, inherited from an ancient subducted oceanic crust, intruded into a depleted oceanic lithosphere that remained stored for a long time

  20. Governing the lithosphere: Insights from Eyjafjallajökull concerning the role of scientists in supporting decision-making on active volcanoes

    NASA Astrophysics Data System (ADS)

    Donovan, Amy; Oppenheimer, Clive

    2012-03-01

    The 2010 eruption of Eyjafjallajökull volcano, and the social consequences across the world, demonstrated some key issues in volcanological science and its application. Scientists in several nations were called upon to advise governments, to justify models and to give guidance about likely future activity. This is symptomatic of many other fields: scientists increasingly have a role in governance, and their work may be driven by questions that arise as a result. This article considers the role of scientists in different national contexts and the challenges faced in formulating scientific advice for policymakers. It concludes by assessing future challenges, and the key role that social scientific research can play. While this is a research paper and presents new data, it takes a commentary approach to elucidate some of the challenges involved in governing volcanic hazards.

  1. Profiling of fine and coarse particle mass: case studies of Saharan dust and Eyjafjallajökull/Grimsvötn volcanic plumes

    NASA Astrophysics Data System (ADS)

    Ansmann, A.; Seifert, P.; Tesche, M.; Wandinger, U.

    2012-05-01

    The lidar-photometer method introduced to separate volcanic coarse-mode and fine-mode particle properties is extended to cover Saharan dust events as well. A review of recently published mass-specific extinction coefficients for Saharan dust and volcanic dust is presented. These mass-specific extinction coefficients are required in the retrieval of particle mass concentration profiles. Case studies of four different scenarios corroborate the applicability of the profiling technique: (a) Saharan dust outbreak to Central Europe, (b) Saharan dust plume mixed with biomass-burning smoke over Cape Verde, and volcanic aerosol layers originating from (c) the Eyjafjallajökull eruptions in 2010 and (d) the Grimsvötn eruptions in 2011. Strong differences in the vertical aerosol layering, aerosol mixing, and optical properties are observed for the different volcanic events.

  2. Interactions between mafic eruptions and glacial ice or snow: implications of the 2010 Eyjafjallajökull, Iceland, eruption for hazard assessments in the central Oregon Cascades

    NASA Astrophysics Data System (ADS)

    McKay, D.; Cashman, K. V.

    2010-12-01

    The 2010 eruption of Eyjafjallajökull, Iceland, demonstrated the importance of addressing hazards specific to mafic eruptions in regions where interactions with glacial ice or snow are likely. One such region is the central Oregon Cascades, where there are hundreds of mafic vents, many of which are Holocene in age. Here we present field observations and quantitative analyses of tephra deposits from recent eruptions at Sand Mountain, Yapoah Cone, and Collier Cone (all <4 ka). These deposits differ from typical Cascade cinder cone deposits in several ways. Most significantly, the Sand Mountain eruption produced a relatively large tephra blanket (~1 km3) that is unusually fine-grained: average clast size is 0.063 - 0.5 mm, in contrast to tephra from typical Cascade cinder cones, which are dominated by small lapilli-sized clasts rather than ash. The eruption of Eyjafjallajökull earlier this year prompted us to investigate the role that ice or snow may have played in the production of unusually fine-grained tephra during the Sand Mountain eruption. The eruption date of Sand Mountain is not well constrained, but it likely occurred during the Neoglacial phase of ice advance, which lasted from ~2 to 8 ka in the central Oregon Cascades (Marcott et al., 2009). During the Neoglacial, winter snowfall was likely ~23% greater and summer temperatures ~1.4°C cooler than present (Marcott, 2009). Although ice did not advance to the elevation of the Sand Mountain vents during this time, the eruption could have occurred through several meters of snow. We have also seen very fine-grained tephra at Yapoah Cone, which is located at a higher elevation and may have interacted with glacial ice. In addition to being characterized by unusually fine grainsize, the Yapoah tephra blanket is deposited directly on top of hyaloclastite in several locations. Tephra from Collier Cone is not characterized by unusually fine grainsize, but several sections of the deposit exhibit features that suggest

  3. Applying 3D Dynamic Visualisation to (Palaeo) Geomorphic Reconstruction: Modelling a Tenth Century Jökulhlaup at Sólheimajökull Glacier, South Iceland.

    NASA Astrophysics Data System (ADS)

    Booth, Laura; Isaacs, John

    2014-05-01

    Jökulhlaup (glacial outburst floods) are caused by subglacial geothermal activity melting overlying ice, or by draining of ice-dammed lakes. They pose a recurring hazard along Iceland's south coast where volcano-glacial interactions create often unpredictable, high-magnitude floods. Gathering information about past floods is crucial for projecting findings to present day scenarios and developing future predictions for contemporary flood routes. Understanding the physical setting or surrounding environment is essential in palaeo-flood reconstruction as drainage routes are ultimately defined by local topography and changing ice cover. At Sólheimajökull glacier, which drains the southern portion of Mýrdalsjökull ice cap, field evidence has been collected of a Tenth Century flood, recorded in the Icelander's Landnámabók (Book of Settlements). It was an exceptional event in terms of generation, magnitude and geomorphic impact. Although now fragmented and piecemeal, many of its direct (and indirect) geomorphological and sedimentary markers are still relatively well preserved and have been identified, mapped and dated to unravel the sequence of events played out during this significant episode in the glacial history and complex regional flood chronology. VolcVis, an innovative, bespoke visualisation platform, is developed and applied for the first time in visualising volcanic jökulhlaup. The platform is created using the Microsoft XNA game development framework, which facilitates rapid game engine production by providing a set of tools utilising a managed runtime environment. VolcVis can render large amounts of data efficiently and still provide an extremely high level of interaction with the data being presented, including full freedom of motion. This enables synthesis and presentation of field results from Sólheimajökull in a novel way, creating an interactive, multi-perspective, three-dimensional (3D) prototype model. The platform combines Digital Elevation

  4. 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.

  5. A survey of early health effects of the Eyjafjallajökull 2010 eruption in Iceland: a population-based study

    PubMed Central

    Carlsen, Hanne Krage; Gislason, Thorarinn; Benediktsdottir, Bryndis; Kolbeinsson, Thorir Bjorn; Hauksdottir, Arna; Thorsteinsson, Throstur

    2012-01-01

    Objective To estimate physical and mental health effects of the Eyjafjallajökull volcanic eruption on nearby residents. Design Cross-sectional study. Setting The Icelandic volcano Eyjafjallajökull erupted on 14 April 2010. The eruption lasted for about 6 weeks and was explosive, ejecting some 8 million tons of fine particles into the atmosphere. Due to prevailing winds, the ash spread mostly to the south and south-east, first over the rural region to the south, later over the Atlantic Ocean and Europe, closing European air space for several days. Participants Residents (n=207) of the most ash-exposed rural area south and east of the volcano. Methods The study period was from 31 May to 11 June 2010. Participants were examined by a physician. To ascertain respiratory health, standardised spirometry was performed before and after the use of a bronchodilator. All adult participants answered questionnaires about mental and physical health, their children's health and the use of protective equipment. Results Every other adult participant reported irritation in eyes and upper airway when exposed to volcanic ash. Adults (n=26) and children (n=5) with pre-existing asthma frequently reported worsening of their symptoms. No serious health problems requiring hospitalisation could be attributed to the eruption. The majority of the participants reported no abnormal physical or mental symptoms to the examining physician. Compared to an age- and gender-matched reference group, the ash-exposed participants reported lower smoking rates and were less likely to have ventilation impairment. Less than 10% of the participants reported symptoms of stress, anxiety or depression. Conclusions Short-term ash exposure was associated with upper airway irritation symptoms and exacerbation of pre-existing asthma but did not contribute to serious health problems. The exposure did not impair respiratory function compared to controls. Outdoor use of protective glasses and face masks was

  6. Correlating Ground-Based Lightning Measurements with Ash Cloud Satellite Data from the 2010 Eruption of Eyjafjallajökull Volcano, Iceland

    NASA Astrophysics Data System (ADS)

    McMahon, N. D.; Thomas, R. J.; Pavolonis, M. J.; Sieglaff, J.; Aster, R. C.

    2012-12-01

    Airborne volcanic ash is a major aviation hazard. For example, the 2010 eruption of Eyjafjallajökull volcano in Iceland resulted in the largest air-traffic shutdown since World War II. More than 100,000 flights were grounded, stranding passengers in Europe and across the globe, and producing a multi-billion dollar economic impact. Because of the high impact on aviation, sophisticated tools are needed to provide real-time alerts, tracking, and forecasting of volcanic clouds. In an attempt address the 5-minute volcanic cloud warning criteria established by the international aviation community, an automated volcanic cloud alert system for the Geostationary Operational Environmental Satellite - R Series (GOES-R) built upon the automated ash cloud alert system for the Advanced Very High Resolution Radiometer (AVHRR) is in development. The new system will be capable of identifying ash and SO2 clouds with greater accuracy. One component of GOES-R will be a lightning mapper. To study the temporal, spatial, and physical relationships between ash clouds and lightning, and the utility of lightning detection in a real-time alert system, we analyze data collected by the Lightning Mapping Array, a ground-based lightning detection network, in conjunction with satellite data gathered by the Spinning Enhanced Visible and Infrared Imager (SEVIRI) instrument aboard Meteosat-9 during in the 2010 eruption of Eyjafjallajökull volcano. We correlate lightning characteristics, intensity, and distribution with plume location, height, mass loading, and effective particle radius. Lightning mapping in volcanic ash clouds potentially will allow for better characterization of the ash cloud and aid in forecasting the distribution of ash and its effects on aviation.

  7. Education and the New Disciplinarity: Surveillance, Spectacle, and the Case of SBER.

    ERIC Educational Resources Information Center

    Vinson, Kevin D.; Ross, E. Wayne

    This paper pursues the evolving relationships between Foucauldian understandings of surveillance (the disciplinary observation of the many by the few) and Debordian notions of spectacle (the disciplinary observation of the few by the many). It argues that education today must be understood according to a setting in which spectacle and surveillance…

  8. Long-term health effects of the Eyjafjallajökull volcanic eruption: a prospective cohort study in 2010 and 2013

    PubMed Central

    Hlodversdottir, Heidrun; Petursdottir, Gudrun; Gislason, Thorarinn; Hauksdottir, Arna

    2016-01-01

    Objectives To examine the long-term development of physical and mental health following exposure to a volcanic eruption. Design Population-based prospective cohort study. Setting In spring 2010, the Icelandic volcano Eyjafjallajökull erupted. Data were collected at 2 time points: in 2010 and 2013. Participants Adult residents in areas close to the Eyjafjallajökull volcano (N=1096), divided according to exposure levels, and a non-exposed sample (n=475), with 80% participation rate in 2013. Main outcome measures Physical symptoms in the previous year (chronic) and previous month (recent), and psychological distress (General Health Questionnaire-12-item version, GHQ-12), perceived stress (Perceived Stress Scale, PSS-4) and post traumatic stress disorder (PTSD) symptoms (Primary Care PTSD, PC-PTSD). Results In the exposed group, certain symptoms were higher in 2013 than in 2010, for example, morning phlegm during winter (OR 2.14; 95% CI 1.49 to 3.06), skin rash/eczema (OR 2.86; 95% CI 1.76 to 4.65), back pain (OR 1.45; 95% CI 1.03 to 2.05) and insomnia (OR 1.53; 95% CI 1.01 to 2.30), in addition to a higher prevalence of regular use of certain medications (eg, for asthma (OR 2.80; 95% CI 1.01 to 7.77)). PTSD symptoms decreased between 2010 and 2013 (OR 0.33; 95% CI 0.17 to 0.61), while the prevalence of psychological distress and perceived stress remained similar. In 2013, the exposed group showed a higher prevalence of various respiratory symptoms than did the non-exposed group, such as wheezing without a cold (high exposure OR 2.35; 95% CI 1.27 to 4.47) and phlegm (high exposure OR 2.81; 95% CI 1.48 to 5.55), some symptoms reflecting the degree of exposure (eg, nocturnal chest tightness (medium exposed OR 3.09; 95% CI 1.21 to 10.46; high exposed OR 3.42; 95% CI 1.30 to 11.79)). Conclusions The findings indicate that people exposed to a volcanic eruption, especially those most exposed, exhibit increased risk of certain symptoms 3–4 years after the eruption. PMID

  9. The Properties and Distribution of Eyjafjallajökull Volcanic Ash, as Observed with MISR Space-based Multi-angle Imaging, April-May 2010 (Invited)

    NASA Astrophysics Data System (ADS)

    Kahn, R. A.; Gaitley, B. J.; Nelson, D. L.; Garay, M. J.; Misr Team

    2010-12-01

    Although volcanic eruptions occur about once per week globally, on average, relatively few of them affect the daily lives of millions of people. Significant exceptions were two eruptions of the Eyjafjallajökull volcano in southern Iceland, which produced ash clouds lasting several weeks during each of April and May 2010. During the first eruption, air traffic over most of Europe was halted, severely affecting international transportation, trade, and economics. For the second ash cloud, space-based and suborbital observations, together with aerosol transport modeling, were used to predict ash plume distribution, making it possible to selectively close only the limited airspace in which there was actual risk of significant ash exposure. These events highlight the immense value of aerosol measurement and modeling capabilities when integrated and applied in emergency response situations. Geosynchronous satellite and continuous, ground-based observations played the most immediate roles in constraining model ash-cloud-extent predictions. However, the rich information content of large-scale though less frequent observations from instruments such as the NASA Earth Observing System’s Multi-angle Imaging SpectroRadiometer (MISR) are key to improving the underlying representations of processes upon which the plume transport models rely. MISR contributes to this pool of information by providing maps of plume height derived from stereo imaging that are independent of knowledge of the temperature structure of the atmosphere or assumptions that the ash cloud is in thermal equilibrium with the environment. Such maps are obtained primarily near-source, where features of the ash cloud can be observed and co-registered in the multi-angle views. A distribution of heights is produced, making it possible to report all-important layer extent rather than just a characteristic plume elevation. Results are derived at 1.1 km horizontal and about 0.5 km vertical resolution. In addition

  10. Observation of the volcanic plume of Eyjafjallajökull over continental Europe by Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS)

    NASA Astrophysics Data System (ADS)

    Yilmaz, S.; Friess, U.; Kern, C.; Vogel, L.; Hoermann, C.; Wagner, T.; Platt, U.

    2010-12-01

    The recent eruption of Eyjafjallajökull Volcano (Iceland) and the emitted ash plume which disrupted commercial air traffic over Europe for an extended period of time has led to an exhaustive debate on how to improve our ability to quantitatively determine the ash load in the atmosphere as a function of time and geographical location in the aftermath of future eruptions. A combination of satellite remote sensing instruments detecting ash and SO2 and ground-based LIDAR stations can help constrain atmospheric transport and meteorology models used to predict ash dispersion. However, multi-axis Differential Optical Absorption Spectroscopy (MAX-DOAS) represents an additional and often neglected tool with considerable potential for the quantitative detection of elevated volcanic ash and SO2 plumes. It performs especially well during weather conditions in which satellites and LIDARs are impeded in their effectiveness, e.g. in the case of dense clouds above or below the plume, respectively. Here, the advantages and disadvantages of the DOAS technique are discussed, and its potential for monitoring of volcanic ash hazards explored. Results of ash and SO2 measurements of the Eyjafjallajökull plume as it passed over the city of Heidelberg, Germany are presented as an example of a positive detection of a highly diluted volcanic plume. SO2 was detected on several days with differential slant column densities (dSCD) of up to (3.33 ± 0.35) × 1017 molec/cm2. The occurrence of these high dSCDs is in good agreement with model predictions (FLEXPART), in-situ background (Schauinsland, Germany) and remote sensing measurements (GOME-2). For cloud free conditions, also the aerosol optical depth at 350 nm was retrieved from the MAX-DOAS measurements. The retrieved values of up to 1.31 ± 0.02 are in good agreement with Sun photometer measurements. Their relatively low cost and complementary nature in respect to other SO2/ash detection techniques makes multi-axis DOAS a promising

  11. Fractures in a trachyandesitic lava at Öræfajökull, Iceland, used to infer subglacial emplacement in 1727-8 eruption

    NASA Astrophysics Data System (ADS)

    Forbes, A. E. S.; Blake, S.; Tuffen, H.; Wilson, A.

    2014-11-01

    We present detailed field observations of cooling fractures in a small-volume trachyandesitic lava, informally named the Slaga lava, on the south west flank of Öræfajökull volcano, south east Iceland. Columnar joints, pseudopillow fracture systems, and curved platy jointing occur in the lava, whose exposed section is approximately 600 m in length and generally 2-3 m in thickness. Columnar jointing may occur at the base of flow lobes, whereas pseudopillow fracture systems occur throughout the lava in an outer, glassy, fractured carapace, and curved platy fractures occur in the centres of larger flow lobes. Pseudopillow fracture systems, composed of a single master fracture and multiple subsidiary fractures formed normal to the master fracture, are of two types: G-type pseudopillow fracture systems have very narrow striae (chisel marks) on their master fractures, indicative of rapid cooling and brittle fracture; SR-type pseudopillow fracture systems display alternating smooth and rough master fracture surface textures, evidence of alternating brittle and ductile fracture propagation mechanisms. Subsidiary fractures in both types show curved striae on their fracture surfaces, which enable the determination of fracture propagation directions. Pseudopillow fracture systems are thought only to form in the presence of water, including water caused by the melting of ice and snow. The curved platy fractures display prominent river lines and may have resulted from cooling contraction, post-emplacement degassing, flow deflation or shearing in the flow against the outer solid crust of the flow during inflation. Due to recent advances in the understanding of the formation mechanisms of pseudopillow fracture systems they, and the other fractures present in the flow, can be used to reconstruct the cooling environment. The lava is inferred to have been emplaced within subglacial drainage channels incised into or beneath a thin alpine-type glacier, with coolant infiltrating the

  12. Aerial infrared surveys of Reykjanes and Torfajökull thermal areas, Iceland, with a section on cost of exploration surveys

    USGS Publications Warehouse

    Pálmason, G.; Friedman, J.D.; Williams, R.S.; Jónsson, J.; Saemundsson, K.

    1970-01-01

    In 1966 and 1968 aerial infrared surveys were conducted over 10 of 13 high-temperature thermal areas in Iceland. The surveys were made with an airborne scanner system, utilizing radiation in the 4.5–5.5 μm wavelength band. Supplementary ground geological studies were made in the Reykjanes and Torfajökull thermal areas to interpret features depicted on the infrared imagery and to relate zones of high heat flux to tectonic structure. In the Reykjanes area in southwestern Iceland a shallow ground temperature map was prepared for temperatures at a depth of 0.5 meters; comparison of this map with the infrared imagery reveals some striking similarities. It appears that aerial infrared surveys outline the surface thermal patterns of high-temperature areas and aid in relating these patterns to possible geological structures controlling the upflow of hot water. Amplitude-slicing techniques applied to the magnetically taped airborne scanner data permit an estimate to be made of the natural heat output on the basis of size of area and specific radiance. In addition to their value in preliminary studies of high-temperature areas, infrared surveys conducted at regular intervals over thermal area under exploitation can provide valuable data on changes that occur in surface manifestations with time.

  13. Impact of meteorological clouds on satellite detection and retrieval of volcanic ash during the Eyjafjallajökull 2010 and Grímsvötn 2011 eruptions: a modelling study

    NASA Astrophysics Data System (ADS)

    Kylling, A.; Kristiansen, N.; Stohl, A.; Buras-Schnell, R.; Emde, C.; Gasteiger, J.

    2014-11-01

    Volcanic ash is commonly observed by infrared detectors on board Earth orbiting satellites. In the presence of ice and/or liquid water clouds the detected volcanic ash signature may be altered. In this paper the effect of ice and liquid water clouds on detection and retrieval of volcanic ash is quantified by simulating synthetic equivalents to satellite infrared images with a 3-D radiative transfer model. The simulations were made both with and without realistic water and ice clouds taken from European Centre for Medium-Range Weather Forecast (ECMWF) analysis data. The volcanic ash cloud fields were taken from simulations by the Lagrangian particle dispersion model FLEXPART. The radiative transfer calculations were made for the geometry and channels of the Spinning Enhanced Visible and Infrared Imager (SEVIRI), for the full duration of the Eyjafjallajökull 2010 and Grímsvötn 2011 eruptions. The synthetic SEVIRI images were then used as input to standard reverse absorption ash detection and retrieval methods. Meteorological clouds were on average found to reduce the number of detected ash affected pixels by 6-12%. However, the effect was highly variable and for individual scenes up to 40% of pixels with mass loading > 0.2 g m-2 could not be detected due to the presence of water and ice clouds. The detection efficiency (detected ash pixels relative to Flexpart ash pixels with ash loading > 0.2 g m-2) was on average only 14.6% (22.1%) for the cloudy (cloudless) simulation for the Eyjafjallajökull 2010 eruption, and 3.6% (10.0%) for the Grímsvötn 2011 eruption. If only Flexpart ash pixels with ash loading > 1.0 g m-2 are considered the detection efficiency increase to 54.7% (74.7) for the Eyjafjallajökull 2010 eruption and to 4.8% (15.1%) for the Grímsvötn 2011 eruption. For coincident pixels, i.e., pixels where ash was both present in the Flexpart simulation and detected by the algorithm, the presence of meteorological clouds overall increased the retrieved

  14. Physicochemical and toxicological profiling of ash from the 2010 and 2011 eruptions of Eyjafjallajökull and Grímsvötn volcanoes, Iceland using a rapid respiratory hazard assessment protocol.

    PubMed

    Horwell, C J; Baxter, P J; Hillman, S E; Calkins, J A; Damby, D E; Delmelle, P; Donaldson, K; Dunster, C; Fubini, B; Kelly, F J; Le Blond, J S; Livi, K J T; Murphy, F; Nattrass, C; Sweeney, S; Tetley, T D; Thordarson, T; Tomatis, M

    2013-11-01

    The six week eruption of Eyjafjallajökull volcano in 2010 produced heavy ash fall in a sparsely populated area of southern and south eastern Iceland and disrupted European commercial flights for at least 6 days. We adopted a protocol for the rapid analysis of volcanic ash particles, for the purpose of informing respiratory health risk assessments. Ash collected from deposits underwent a multi-laboratory physicochemical and toxicological investigation of their mineralogical parameters associated with bio-reactivity, and selected in vitro toxicology assays related to pulmonary inflammatory responses. Ash from the eruption of Grímsvötn, Iceland, in 2011 was also studied. The results were benchmarked against ash from Soufrière Hills volcano, Montserrat, which has been extensively studied since the onset of eruptive activity in 1995. For Eyjafjallajökull, the grain size distributions were variable: 2-13 vol% of the bulk samples were <4 µm, with the most explosive phases of the eruption generating abundant respirable particulate matter. In contrast, the Grímsvötn ash was almost uniformly coarse (<3.5 vol%<4 µm material). Surface area ranged from 0.3 to 7.7 m2 g(-1) for Eyjafjallajökull but was very low for Grímsvötn (<0.6 m2 g(-1)). There were few fibre-like particles (which were unrelated to asbestos) and the crystalline silica content was negligible in both eruptions, whereas Soufrière Hills ash was cristobalite-rich with a known potential to cause silicosis. All samples displayed a low ability to deplete lung antioxidant defences, showed little haemolysis and low acute cytotoxicity in human alveolar type-1 like epithelial cells (TT1). However, cell-free tests showed substantial hydroxyl radical generation in the presence of hydrogen peroxide for Grímsvötn samples, as expected for basaltic, Fe-rich ash. Cellular mediators MCP-1, IL-6, and IL-8 showed chronic pro-inflammatory responses in Eyjafjallajökull, Grímsvötn and Soufrière Hills samples

  15. Physicochemical and toxicological profiling of ash from the 2010 and 2011 eruptions of Eyjafjallajökull and Grímsvötn volcanoes, Iceland using a rapid respiratory hazard assessment protocol.

    PubMed

    Horwell, C J; Baxter, P J; Hillman, S E; Calkins, J A; Damby, D E; Delmelle, P; Donaldson, K; Dunster, C; Fubini, B; Kelly, F J; Le Blond, J S; Livi, K J T; Murphy, F; Nattrass, C; Sweeney, S; Tetley, T D; Thordarson, T; Tomatis, M

    2013-11-01

    The six week eruption of Eyjafjallajökull volcano in 2010 produced heavy ash fall in a sparsely populated area of southern and south eastern Iceland and disrupted European commercial flights for at least 6 days. We adopted a protocol for the rapid analysis of volcanic ash particles, for the purpose of informing respiratory health risk assessments. Ash collected from deposits underwent a multi-laboratory physicochemical and toxicological investigation of their mineralogical parameters associated with bio-reactivity, and selected in vitro toxicology assays related to pulmonary inflammatory responses. Ash from the eruption of Grímsvötn, Iceland, in 2011 was also studied. The results were benchmarked against ash from Soufrière Hills volcano, Montserrat, which has been extensively studied since the onset of eruptive activity in 1995. For Eyjafjallajökull, the grain size distributions were variable: 2-13 vol% of the bulk samples were <4 µm, with the most explosive phases of the eruption generating abundant respirable particulate matter. In contrast, the Grímsvötn ash was almost uniformly coarse (<3.5 vol%<4 µm material). Surface area ranged from 0.3 to 7.7 m2 g(-1) for Eyjafjallajökull but was very low for Grímsvötn (<0.6 m2 g(-1)). There were few fibre-like particles (which were unrelated to asbestos) and the crystalline silica content was negligible in both eruptions, whereas Soufrière Hills ash was cristobalite-rich with a known potential to cause silicosis. All samples displayed a low ability to deplete lung antioxidant defences, showed little haemolysis and low acute cytotoxicity in human alveolar type-1 like epithelial cells (TT1). However, cell-free tests showed substantial hydroxyl radical generation in the presence of hydrogen peroxide for Grímsvötn samples, as expected for basaltic, Fe-rich ash. Cellular mediators MCP-1, IL-6, and IL-8 showed chronic pro-inflammatory responses in Eyjafjallajökull, Grímsvötn and Soufrière Hills samples

  16. The Impacts of Advancing Glaciers and Jökulhlaups on the 19th Century Farming Community in the Suðursveit District South of Vatnajökull Glacier, Iceland.

    NASA Astrophysics Data System (ADS)

    Sigurmundsson, F. S.; Gísladóttir, G.; Erlendsson, E.

    2014-12-01

    Few areas in Iceland were as vulnerable to climate changes during the 19th century as the region south of Vatnajökull glacier. The region was repeatedly affected by glacier advance and jökulhlaups (glacier outburst floods) during the Little Ice Age AD 1300-1900 (LIA). The land area between the glacier and the coast was occupied by farming community. The aim of this research is to quantify and map the size of lost vegetated area in the 19th century during the glacial advance in the climax of the LIA and the impact these events had on the community, land-use, ownership, value of estates and livelihood. This research employs historical written sources to investigate changes in the cultural and natural landscape. Historical data and field observations will be collected and stored in a GIS database designed for the research, allowing data to be analyzed and presented on maps. The first recorded impact on the settlement is from 1794 when the Breiðármerkurjökull outlet glacier advanced and devastated pastures and crofts belonging in west of the district. Seventy five years later, in 1868, the largest estate was completely destroyed by a jökulhlaup. In 1829 a farm site in the middle of the district was moved due to repeated jökulhlaup. The outlet glacier Brókarjökull initiated annual jökulhlaups during 1820 -1870, devastating pastures and hayfields and woodlands of a total of 3 prominent estates in the area (by 1200 ha), causing devaluation of 33-66% on these estates. In the eastern part extensive jökulhlaups changed the glacial river channel causing the river to flow over vast area devastating 80 % of the eastern most estate causing its abandonment in 1892. The climate change and accompanied hazards during the 19th century changed the landscape of the Suðursveit district significantly. By the turn of the 20thcentury the vegetated land in the district had been reduced by 35% and areas of sediments increased by 25% and glaciated area increased by 10%. These

  17. Geodetic mass balance record with rigorous uncertainty estimates deduced from aerial photographs and lidar data - Case study from Drangajökull ice cap, NW Iceland

    NASA Astrophysics Data System (ADS)

    Magnússon, E.; Muñoz-Cobo Belart, J.; Pálsson, F.; Ágústsson, H.; Crochet, P.

    2016-01-01

    In this paper we describe how recent high-resolution digital elevation models (DEMs) can be used to extract glacier surface DEMs from old aerial photographs and to evaluate the uncertainty of the mass balance record derived from the DEMs. We present a case study for Drangajökull ice cap, NW Iceland. This ice cap covered an area of 144 km2 when it was surveyed with airborne lidar in 2011. Aerial photographs spanning all or most of the ice cap are available from survey flights in 1946, 1960, 1975, 1985, 1994 and 2005. All ground control points used to constrain the orientation of the aerial photographs were obtained from the high-resolution lidar DEM. The lidar DEM was also used to estimate errors of the extracted photogrammetric DEMs in ice- and snow-free areas, at nunataks and outside the glacier margin. The derived errors of each DEM were used to constrain a spherical semivariogram model, which along with the derived errors in ice- and snow-free areas were used as inputs into 1000 sequential Gaussian simulations (SGSims). The simulations were used to estimate the possible bias in the entire glaciated part of the DEM and the 95 % confidence level of this bias. This results in bias correction varying in magnitude between 0.03 m (in 1975) and 1.66 m (in 1946) and uncertainty values between ±0.21 m (in 2005) and ±1.58 m (in 1946). Error estimation methods based on more simple proxies would typically yield 2-4 times larger error estimates. The aerial photographs used were acquired between late June and early October. An additional seasonal bias correction was therefore estimated using a degree-day model to obtain the volume change between the start of 2 glaciological years (1 October). This correction was largest for the 1960 DEM, corresponding to an average elevation change of -3.5 m or approx. three-quarters of the volume change between the 1960 and the 1975 DEMs. The total uncertainty of the derived mass balance record is dominated by uncertainty in the volume

  18. Investigation of the complex dynamics and structure of the 2010 Eyjafjallajökull volcanic ash cloud using multispectral images and numerical simulations

    NASA Astrophysics Data System (ADS)

    Spinetti, C.; Barsotti, S.; Neri, A.; Buongiorno, M. F.; Doumaz, F.; Nannipieri, L.

    2013-05-01

    investigated the structure and evolution of the 2010 Eyjafjallajökull volcanic cloud and its dispersal over Iceland and Europe integrating satellite multispectral images and numerical simulations. Data acquired by Medium Resolution Imaging Spectrometer (MERIS) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) have been analyzed to quantify the cloud extent and composition. The VOL-CALPUFF dispersal code was applied to reconstruct the transient and 3-D evolution of the cloud. Source parameters estimated on the base of available a posteriori volcanological data sets have been used. Quantitative comparisons between satellite retrievals and modeling results were performed for two selected instants of time during the first and third eruptive phases on a regional scale. Sensitivity of the model to initial volcanological conditions has been analyzed at continental scale. Several complex non intuitive features of cloud dynamics have been highlighted and strengths and limitations of the adopted methods identified. The main findings are: the level of quantitative agreement between satellite observations and numerical results depends on ash cloud composition (particle sizes and concentration) with better agreement for smaller particles and higher concentrations; the agreement between observations and modeling outcomes also depends on the temporal stability of volcanological conditions and the complexity of the meteorological wind field; the irregular dispersion of ash, as reconstructed from satellite data and numerical modeling, can be well explained by the different response of particle sizes to strong vertical wind-shear, and by resuspension processes acting at ground level; eruptive source conditions are the main source of uncertainty in modeling, especially during an ongoing crisis and at long-range scales.

  19. Area, volume and mass changes of southeast Vatnajökull ice cap, Iceland, from the Little Ice Age maximum in the late 19th century to 2010

    NASA Astrophysics Data System (ADS)

    Hannesdóttir, H.; Björnsson, H.; Pálsson, F.; Aðalgeirsdóttir, G.; Guðmundsson, S.

    2014-09-01

    Area and volume changes and the average geodetic mass balance of the non-surging outlet glaciers of southeast Vatnajökull ice cap, Iceland, during different time periods between ~1890 and 2010, are derived from a multi-temporal glacier inventory. A series of digital elevation models (DEMs) (∼1890, 1904, 1936, 1945, 1989, 2002, 2010) have been compiled from glacial geomorphological features, historical photographs, maps, aerial images, DGPS measurements and a LiDAR survey. Given the mapped bedrock topography we estimate relative volume changes since the end of the Little Ice Age (LIA) ~1890. The variable dynamic response of the outlets, assumed to have experienced similar climate forcing, is related to their different hypsometry, bedrock topography, and the presence of proglacial lakes. In the post-LIA period the glacierized area decreased by 164 km2 and the glaciers had lost 10-30% of their ~1890 area by 2010. The glacier surface lowered by 150-270 m near the terminus and the outlet glaciers collectively lost 60 ± 8 km3 of ice, which is equivalent to 0.154 ± 0.02 mm of sea level rise. The relative volume loss of individual glaciers was in the range of 15-50%, corresponding to a geodetic mass balance between -0.70 and -0.32 m w.e. a-1. The rate of mass loss was most negative in the period 2002-2010, on average -1.34 ± 0.12 m w.e. a-1, which lists among the most negative mass balance values recorded worldwide in the early 21st century. From the data set of volume and area of the outlets, spanning the 120 years post-LIA period, we evaluate the parameters of a volume-area power law scaling relationship.

  20. Area, Volume and Mass Changes of Southeast Vatnajökull Ice Cap, Iceland, from the Little Ice Age Maximum in the Late 19th Century to 2010

    NASA Astrophysics Data System (ADS)

    Hannesdóttir, H.; Bjornsson, H.; Pálsson, F.; Adalgeirsdottir, G.; Gudmundsson, S.

    2014-12-01

    Areal and volume changes and the average geodetic mass balance of the non-surging outlet glaciers of southeast Vatnajökull ice cap, Iceland, during different time periods between 1890 and 2010, are derived from a multi-temporal glacier inventory. A series of digital elevation models (DEMs) (1890, 1904, 1936, 1945, 1989, 2002, 2010) have been compiled from geomorphological features, historical photographs, maps, aerial images, DGPS measurements and a LiDAR survey. Given the mapped bedrock topography, relative volume changes since the end of the Little Ice Age (LIA) 1890 have been estimated. The variable dynamic response of the outlet glaciers to assumed similar climate forcing, is related to their different hypsometry, bedrock topography, and the presence of proglacial lakes. In the post-LIA period the glacierized area decreased by 164 km2 and the glaciers had lost 10-30% of their 1890 area by 2010. The glacier surface lowered by 150-270 m near the terminus and the outlet glaciers collectively lost 60±8 km3 of ice, which is equivalent to 0.154 mm of sea level rise. The relative volume loss of individual glaciers was in the range of 15-50%, corresponding to a geodetic mass balance between -0.70 and -0.32 m w.e. a-1. The rate of mass loss was most negative in 2002-2010, on average -1.34 m w.e. a-1, which lists among the most negative mass balance values recorded worldwide in the early 21st century. From the data set of volume and area of the outlet glaciers, spanning the whole 120 year post-LIA period, we estimate the parameters of a volume area power-law scaling relationship.

  1. Assessment of hydro-morphodynamic modelling and geomorphological impacts of a sediment-charged jökulhlaup, at Sólheimajökull, Iceland

    NASA Astrophysics Data System (ADS)

    Guan, Mingfu; Wright, Nigel G.; Sleigh, P. Andy; Carrivick, Jonathan L.

    2015-11-01

    Understanding of complex flood-riverbed interaction processes in large-scale (field) outburst floods remains incomplete, not least due to a lack of well-constrained field data on hydraulics and sediment transport, but also because consensus on an appropriate model framework has yet to be agreed. This study presents a novel full 2D hydro-morphodynamic model containing both bedload and suspended load capability. Firstly, the model design is presented with an emphasis on its design to simulate rapidly-varied sediment-laden outburst floods and also the associated geomorphological impacts. Secondly, the model is applied to a large-scale (field) glacier outburst flood or 'jökulhlaup' at Sólheimajökull, Iceland. For this real-world event, model scenarios with only water and with inclusion of sediment with different parameter setups were performed. Results indicated that grain size specifications affected resultant geomorphological changes, but that the sensitivity of the simulated riverbed changes to the empirical bedload transport formulae were insignificant. Notably, a positive feedback occurred whereby the jökulhlaup led to significant net erosion of the riverbed, producing an increase in flow conveyance capacity of the river channel. Furthermore, bulking effects of sediment entrainment raised the peak discharge progressively downstream, as well as the flood volume. Effects of geomorphological changes on flood water level and flow velocity were significant. Overall, despite the increased computational effort required with inclusion of sediment transport processes, this study shows that river morphological changes cannot be ignored for events with significant in-channel erosion and deposition, such as during outburst floods.

  2. High levels of particulate matter in Iceland due to direct ash emissions by the Eyjafjallajökull eruption and resuspension of deposited ash

    NASA Astrophysics Data System (ADS)

    Thorsteinsson, Throstur; Jóhannsson, Thorsteinn; Stohl, Andreas; Kristiansen, Nina I.

    2012-09-01

    The dangers to people living near a volcano due to lava and pyroclastic flows, and, on glacier- or snow-covered volcanoes, jökulhlaups, are well known. The level of risk to human health due to high concentrations of ash from direct emission and resuspension from the ground is, however, not as well known. The eruption at Eyjafjallajökull, 14 April to 20 May 2010, produced abundant particulate matter due to its explosive eruption style. Even after the volcanic activity ceased, high particulate matter (PM) concentrations were still measured on several occasions, due to resuspended ash. The 24 hour mean concentration of PM10 in the small town of Vík, 38 km SE of the volcano, reached 1230 μg m-3, which is about 25 times the health limit, on 7 May 2010, with 10 min average values over 13,000 μg m-3. Even after the eruption ceased, values as high as 8000 μg m-3 (10 min), and 900 μg m-3 (24 h), were measured because of resuspension of freshly deposited fine ash. In Reykjavík, 125 km WNW of the volcano, the PM10 concentration reached over 2000 μg m-3 (10 min) during an ash storm on 4 June 2010, which should have warranted airport closure. Summarizing, our study reveals the importance of ash resuspension compared to direct volcanic ash emissions. This likely has implications for air quality but could also have detrimental effects on the quality of ash dispersion model predictions, which so far generally do not include this secondary source of volcanic ash.

  3. Determination of time- and height-resolved volcanic ash emissions and their use for quantitative ash dispersion modeling: the 2010 Eyjafjallajökull eruption

    NASA Astrophysics Data System (ADS)

    Stohl, A.; Prata, A. J.; Eckhardt, S.; Clarisse, L.; Durant, A.; Henne, S.; Kristiansen, N. I.; Minikin, A.; Schumann, U.; Seibert, P.; Stebel, K.; Thomas, H. E.; Thorsteinsson, T.; Tørseth, K.; Weinzierl, B.

    2011-05-01

    The April-May, 2010 volcanic eruptions of Eyjafjallajökull, Iceland caused significant economic and social disruption in Europe whilst state of the art measurements and ash dispersion forecasts were heavily criticized by the aviation industry. Here we demonstrate for the first time that large improvements can be made in quantitative predictions of the fate of volcanic ash emissions, by using an inversion scheme that couples a priori source information and the output of a Lagrangian dispersion model with satellite data to estimate the volcanic ash source strength as a function of altitude and time. From the inversion, we obtain a total fine ash emission of the eruption of 8.3 ± 4.2 Tg for particles in the size range of 2.8-28 μm diameter. We evaluate the results of our model results with a posteriori ash emissions using independent ground-based, airborne and space-borne measurements both in case studies and statistically. Subsequently, we estimate the area over Europe affected by volcanic ash above certain concentration thresholds relevant for the aviation industry. We find that during three episodes in April and May, volcanic ash concentrations at some altitude in the atmosphere exceeded the limits for the "Normal" flying zone in up to 14 % (6-16 %), 2 % (1-3 %) and 7 % (4-11 %), respectively, of the European area. For a limit of 2 mg m-3 only two episodes with fractions of 1.5 % (0.2-2.8 %) and 0.9 % (0.1-1.6 %) occurred, while the current "No-Fly" zone criterion of 4 mg m-3 was rarely exceeded. Our results have important ramifications for determining air space closures and for real-time quantitative estimations of ash concentrations. Furthermore, the general nature of our method yields better constraints on the distribution and fate of volcanic ash in the Earth system.

  4. Validation of ash optical depth and layer height retrieved from passive satellite sensors using EARLINET and airborne lidar data: the case of the Eyjafjallajökull eruption

    NASA Astrophysics Data System (ADS)

    Balis, Dimitris; Koukouli, Maria-Elissavet; Siomos, Nikolaos; Dimopoulos, Spyridon; Mona, Lucia; Pappalardo, Gelsomina; Marenco, Franco; Clarisse, Lieven; Ventress, Lucy J.; Carboni, Elisa; Grainger, Roy G.; Wang, Ping; Tilstra, Gijsbert; van der A, Ronald; Theys, Nicolas; Zehner, Claus

    2016-05-01

    The vulnerability of the European airspace to volcanic eruptions was brought to the attention of the public and the scientific community by the 2010 eruptions of the Icelandic volcano Eyjafjallajökull. As a consequence of this event, ash concentration thresholds replaced the "zero tolerance to ash" rule, drastically changing the requirements on satellite ash retrievals. In response to that, the ESA funded several projects aiming at creating an optimal end-to-end system for volcanic ash plume monitoring and prediction. Two of them, namely the SACS-2 and SMASH projects, developed and improved dedicated satellite-derived ash plume and sulfur dioxide level assessments. The validation of volcanic ash levels and height extracted from the GOME-2 and IASI instruments on board the MetOp-A satellite is presented in this work. EARLINET lidar measurements are compared to different satellite retrievals for two eruptive episodes in April and May 2010. Comparisons were also made between satellite retrievals and aircraft lidar data obtained with the UK's BAe-146-301 Atmospheric Research Aircraft (managed by the Facility for Airborne Atmospheric Measurements, FAAM) over the United Kingdom and the surrounding regions. The validation results are promising for most satellite products and are within the estimated uncertainties of each of the comparative data sets, but more collocation scenes would be desirable to perform a comprehensive statistical analysis. The satellite estimates and the validation data sets are better correlated for high ash optical depth values, with correlation coefficients greater than 0.8. The IASI retrievals show a better agreement concerning the ash optical depth and ash layer height when compared with the ground-based and airborne lidar data.

  5. Long-range infrasound observations of eruptions April-May 2010 Eyjafjallajökull, Iceland and June 2009 Sarychev Peak, Kuril Islands

    NASA Astrophysics Data System (ADS)

    Matoza, R. S.; Le Pichon, A.; Vergoz, J.; Herry, P.; Lalande, J.; Ceranna, L.; Green, D. N.; Evers, L. G.; Marchetti, E.; Ripepe, M.; Campus, P.; Liszka, L. J.; Kvaerna, T.; Lee, H.; Che, I.; Rybin, A.

    2010-12-01

    During explosive volcanic eruptions, release of overpressure and rapid and sustained injection of mass into the atmosphere are typically significant sources of low-frequency sound. Acoustic waves with frequencies in the band ~0.01-20 Hz, or infrasound, can propagate over large distances in atmospheric waveguides with low attenuation. We present two case studies of long-range infrasound observations of volcanism producing significant ash clouds. The 2010 summit eruption of Eyjafjallajökull was recorded during April-May at 14 infrasound recording arrays across Europe and beyond, to a maximum range of >3,500 km. Such long-range propagation is remarkable considering the relatively modest level of explosive activity. The larger June 2009 Sarychev Peak (SP) eruption was recorded at six International Monitoring System (IMS) infrasound arrays of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) and several KIGAM infrasound arrays located at ranges of ~640-6,400 km from SP. Signals at the three closest recording stations IS44 (643 km, Petropavlovsk-Kamchatskiy, Kamchatka Krai, Russian Federation), IS45 (1,690 km, Ussuriysk, Russian Federation), and IS30 (1,774 km, Isumi, Japan) represent a detailed record of the explosion chronology that correlates well with an eruption chronology based on satellite data (TERRA, NOAA, MTSAT). The eruption chronology inferred from infrasound data has a higher temporal resolution than that obtained with satellite data. Atmosphere-corrected infrasonic source locations determined from backazimuth cross-bearings have a mean centroid ~15 km from the true location of SP. The air space above the Kuril Islands represents a major air corridor linking Europe, North America and northern Asia, yet seismic network coverage is sparse in the region. This study therefore highlights the significant potential of the IMS infrasound network for aiding with monitoring remote volcanic regions of the planet.

  6. MODIS-derived albedo changes of Vatnajökull (Iceland) due to tephra deposition from the 2004 Grímsvötn eruption

    NASA Astrophysics Data System (ADS)

    Möller, Rebecca; Möller, Marco; Björnsson, Helgi; Guðmundsson, Sverrir; Pálsson, Finnur; Oddsson, Björn; Kukla, Peter A.; Schneider, Christoph

    2014-02-01

    Occasionally, the surface albedo of glaciers may be abruptly altered by deposition of light-absorbing aerosols, which consequently has a sustained impact on their energy- and mass balance. Volcanic eruptions may spread tephra deposits over regional-scale glacierized areas. In November 2004, an explosive, phreatomagmatic eruption of the subglacial Grímsvötn volcano, located in the centre of the Icelandic ice cap Vatnajökull, produced ash fall covering an area of ∼1280 km2 in the northwestern part of the ice cap. This event affected the surface albedo of the glacier over several years after the eruption. We use MODIS surface-albedo data and an ash-dispersal dataset obtained from in situ measurements on the ice cap to develop a novel, empirically based modelling approach to describe the albedo decrease across the glacier surface caused by the deposited tephra. We present analyses of the temporal and spatial variability of the albedo pattern over the post-eruption period from November 2004 to December 2008. The tephra-induced albedo changes were largest and most widely distributed over the glacier surface during the summer season 2005. The observed albedo decrease reached 0.35 when compared to modelled, undisturbed conditions. In the low-lying ablation area, where strong surface melting takes place, the tephra influence on albedo diminished with time and completely faded out within four years after the eruption. In contrast, at the rim of the Grímsvötn caldera surrounding the eruption site the tephra influences on albedo considerably increased with time. Throughout the rest of the high-lying accumulation area, the influences were scattered in both space and time.

  7. Volcano-tectonic interactions revealed by inversion of focal mechanisms: stress field insight around and beneath the Vatnajökull ice cap in Iceland

    NASA Astrophysics Data System (ADS)

    Plateaux, Romain; Bethoux, Nicole; Bergerat, Françoise; Mercier de Lépinay, Bernard

    2014-05-01

    Volcano-tectonic processes in the central part of Iceland, covered by the Vatnajökull glacier, are investigated by inversion of focal mechanisms. Working on a large catalogue of focal mechanisms determined by the Icelandic Meteorological Office, we used a damped regional-scale stress inversion method to obtain an insight of kilometric variations of the stress field. To evaluate the resolution and the stability of this stress field solution, we computed checkerboard tests, stress field models and error propagation tests. Stress field models showed a continuous stress regime between normal and strike-slip faulting, associated with a high stress shape ratio (i.e.; σ1 ≈ σ2). Two main directions of σhmin were evidenced: the first one was in agreement with the regional spreading direction of Iceland and the second one was deviated, being almost perpendicular to the first one. The deviated stress direction is sustained through the 20 year time-span of the study around the Bárðarbunga and Grimsvötn central volcanoes while the spreading direction remains predominant around the Hamarinn volcano. This result supports the hypothesis that this volcano lacks collapse caldera and shares a fissure swarm with the larger Bárðarbunga volcano. On a smaller temporal scale, during the 1996 volcanic crisis, a bimodal distribution of σhmin showed two opposite strike-slip regimes where the deviated direction dominated. Because these two states of stress T1 and T2 show stress regimes away from the Andersonian positions, P, B and T axes, the rapid flip between these two regimes may be associated with the progressive melt intrusion of a dyke.

  8. Geochemical characterization of single atmospheric particles from the Eyjafjallajökull volcano eruption event collected at ground-based sampling sites in Germany

    NASA Astrophysics Data System (ADS)

    Schleicher, Nina; Kramar, Utz; Dietze, Volker; Kaminski, Uwe; Norra, Stefan

    2012-03-01

    Volcanic particles can be transported over long distances in the atmosphere and can cause severe problems for air traffic. This was the case over large areas of Europe in spring 2010 after the eruption of the Eyjafjallajökull (E15) volcano on Iceland. The scope of this work was to characterize these volcanic particles more in detail with regard to size and chemical composition in order to provide valuable information needed for a better estimation of the possible impact on airplane jet engines and cockpit windows. Another question of this study was which share of the overall atmospheric particles in Germany originated from the E15 eruption and whether this amount of volcanic particles could cause any adverse health effects to humans. To this end, single particle analysis by means of scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX) and synchrotron radiation based micro X-ray fluorescence analysis (μS-XRF) together with multivariate statistical methods were applied for samples collected on ground-level in Southwest Germany and Iceland. Based on the obtained chemical fingerprints combined with multivariate statistical methods it was possible to discrimate between the amount of volcanic particles from Iceland and other atmospheric particles from non-volcanic sources. This aspect distinguishes this single particle approach from most other studies. The results of the study showed that at least 40% of the analyzed particles between 2.5 and 10 μm size at the remote sampling sites in the Black Forest area and about 25% in the city of Freiburg were clearly of volcanic origin from the E15 volcano eruption event.

  9. Charge structure in volcanic plumes: a comparison of plume properties predicted by an integral plume model to observations of volcanic lightning during the 2010 eruption of Eyjafjallajökull, Iceland

    NASA Astrophysics Data System (ADS)

    Woodhouse, Mark J.; Behnke, Sonja A.

    2014-08-01

    Observations of volcanic lightning made using a lightning mapping array during the 2010 eruption of Eyjafjallajökull allow the trajectory and growth of the volcanic plume to be determined. The lightning observations are compared with predictions of an integral model of volcanic plumes that includes descriptions of the interaction with wind and the effects of moisture. We show that the trajectory predicted by the integral model closely matches the observational data and the model well describes the growth of the plume downwind of the vent. Analysis of the lightning signals reveals information on the dominant charge structure within the volcanic plume. During the Eyjafjallajökull eruption both monopole and dipole charge structures were observed in the plume. By using the integral plume model, we propose the varying charge structure is connected to the availability of condensed water and low temperatures at high altitudes in the plume, suggesting ice formation may have contributed to the generation of a dipole charge structure via thunderstorm-style ice-based charging mechanisms, though overall this charging mechanism is believed to have had only a weak influence on the production of lightning.

  10. Surface deformation versus eruption rates of the two Eyjafjallajökull 2010 eruptions; implications for the magma plumbing system and origin of melts

    NASA Astrophysics Data System (ADS)

    Pedersen, R.; Sigmundsson, F.; Hreinsdottir, S.; Arnadottir, T.; Hoskuldsson, A.; Gudmundsson, M. T.; Magnusson, E.

    2010-12-01

    Repeated geodetic measurements reveal how active volcanoes deform at the surface, and data inversion facilitates inferences about the related volume changes of underlying deformation sources. During an eruption, drainage from a shallow magma chamber can lead to direct correlation between magma flow rate and deformation rates, as observed previously in Iceland. In the simplest case, a constant scale factor relates magma flow rates, deformation rates on the surface, and inferred volume contraction of subsurface sources. The scale factor will depend on magma source geometry, compressibility of residing magma and rheological properties of the crustal rocks. During the two eruptions of the Eyjafjallajökull volcano, Iceland, in 2010 an entirely different behaviour was observed. This behaviour may be related to the rather unique plumbing system of this particular Icelandic volcano, which appears to have no shallow magma chamber. For the initial flank eruption, where olivine basalt were erupted during a period of about 3 weeks, the average eruption rate was comparable to the inferred flow rate during formation of a pre-eruptive network of intrusions. Detailed GPS and InSAR measurements have revealed a model for the subsurface magma plumbing system active prior to and during the events with multiple sills around 5 km depth. Such intrusions have occurred intermittently in this particular volcano for the past 18 years. During the subsequent explosive trachy-andesitic summit eruption, the relation between deformation rate and magma flow rate is more complex. A large discrepancy exists between the inferred erupted volume and the computed volume change based on the associated surface deformation. When recalculated to dense rock equivalent, the inferred volume change responsible for the main deformation is about one order of magnitude smaller than the sum of mapped erupted volumes. Furthermore, the spatial pattern of the deformation is complex, and not directly related to the

  11. Determination of time- and height-resolved volcanic ash emissions for quantitative ash dispersion modeling: the 2010 Eyjafjallajökull eruption

    NASA Astrophysics Data System (ADS)

    Stohl, A.; Prata, A. J.; Eckhardt, S.; Clarisse, L.; Durant, A.; Henne, S.; Kristiansen, N. I.; Minikin, A.; Schumann, U.; Seibert, P.; Stebel, K.; Thomas, H. E.; Thorsteinsson, T.; Tørseth, K.; Weinzierl, B.

    2011-02-01

    The April-May 2010 volcanic eruptions of Eyjafjallajökull, Iceland caused significant economic and social disruption in Europe whilst state of the art measurements and ash dispersion forecasts were heavily criticized by the aviation industry. Here we demonstrate for the first time that dramatic improvements can be made in quantitative predictions of the fate of volcanic ash emissions, by using an inversion scheme that couples a priori source information and the output of a Lagrangian dispersion model with satellite data to estimate the volcanic ash source strength as a function of altitude and time. From the inversion, we obtain a total fine ash emission of the eruption of 8.3 ± 4.2 Tg for particles in the size range of 2.8-28 μm diameter and extrapolate this to a total ash emission of 11.9 ± 5.9 Tg for the size range of 0.25-250 μm. We evaluate the results of our a posteriori model using independent ground-based, airborne and space-borne measurements both in case studies and statistically. Subsequently, we estimate the area over Europe affected by volcanic ash above certain concentration thresholds relevant for the aviation industry. We find that during three episodes in April and May, volcanic ash concentrations at some altitude in the atmosphere exceeded the limits for the "normal" flying zone in up to 14% (6-16%), 2% (1-3%) and 7% (4-11%), respectively, of the European area. For a limit of 2 mg m-3 only two episodes with fractions of 1.5% (0.2-2.8%) and 0.9% (0.1-1.6%) occurred, while the current "no-fly" zone criterion of 4 mg m-3 was rarely exceeded. Our results have important ramifications for determining air space closures and for real-time quantitative estimations of ash concentrations. Furthermore, the general nature of our method yields better constraints on the distribution and fate of volcanic ash in the Earth system.

  12. Observing the 2010 Eyjafjallajökull, Iceland, Eruptions with NASA's Earth Observing-1 Spacecraft - Improving Data Flow In a Volcanic Crisis Through Use of Autonomy

    NASA Astrophysics Data System (ADS)

    Chien, S.; Davies, A. G.; Doubleday, J.; Tran, D. Q.; Gudmundsson, M. T.; Jónsdóttir, I.; Hoskuldsson, A.; Thordarson, T.; Jakobsdottir, S.; Wright, R.

    2010-12-01

    Eyjafjallajökull volcano, Iceland, erupted from 20 March to 12 April 2010 (a flank eruption) and again from 14 April to 23 May 2010. The latter eruption heavily impacted air travel across much of northern Europe, and highlighted the need to monitor and quickly react to new eruptions. The NASA Earth Observing 1 spacecraft (EO-1), which is managed by the NASA Goddard Space Flight Center, obtained over 50 observation pairs with the Hyperion hyperspectral imager and ALI (Advanced Land Imager) multispectral camera. EO-1 is the remote-sensing asset of a globe-spanning Volcano Sensor Web [1], where low spatial resolution data (e.g., MODIS) or alerts of ongoing or possible volcanic activity are used to trigger requests for high resolution EO-1 data. Advanced resource management software, developed in part for flight onboard EO-1 as part of the Autonomous Sciencecraft [2, 3] is now used to task EO-1. This system allowed rapid re-tasking of EO-1 to obtain both day and night data at high temporal resolution (on average every 2 days), unusual for such high spatial resolution imagers (Hyperion and ALI at 30 m/pixel, with an ALI panchromatic band at 10 m/pixel). About 50% of the data were impacted by cloud. Advances in data handling and communications during the last two years means that Hyperion and ALI data are typically on the ground and ready for analysis within a few hours of data acquisition. Automatic data processing systems at the NASA’s Jet Propulsion Laboratory process Hyperion data to (1) correct for atmospheric adsorption; (2) remove the sunlight component in daytime data; (3) identify hot pixels; (4) fit unsaturated data to determine temperature and area of sub-pixel thermal sources; (5) calculate total thermal emission and, from this, an effusion rate; (6) generate geo-located data products. The entire process is autonomous. Data products, as well as images generated, were sent to volcanologists in the field to aid in eruption assessment. The JPL group is now

  13. Overview of the NAME model and its role as a VAAC atmospheric dispersion model during the Eyjafjallajökull Eruption April 2010

    NASA Astrophysics Data System (ADS)

    Leadbetter, Susan; Agnew, Paul; Burgin, Laura; Davis, Lucy; Hort, Matthew; Huggett, Lois; Jones, Andrew; Manning, Alistair; Redington, Alsion; Thomson, David; Webster, Helen

    2010-05-01

    The UK Met Office, in its role as one of nine Volcanic Ash Advisory Centres (VAACs) around the world, is responsible for advising international aviation authorities in all impacted countries of the location and movement of clouds of volcanic ash which originate from the London VAAC domain. VAACs only provide advice on extent of ash to the aviation regulators and it is the regulator's decision on whether to restrict air space. The Met Office delivers this capability through a world-leading atmospheric dispersion model, NAME. In addition to its role as an emergency response guidance tool the model is used for routine air quality forecasting and meteorological research activities. NAME is a Lagrangian particle model which calculates the dispersion of pollutants by tracking ‘particles' through a modelled atmosphere. Each model particle has its own characteristics, for example, particles can represent different chemical species and can represent real particulate sizes. NAME has the flexibility to specify sources at any location in the atmosphere. Once emitted, particles move in a manner determined by the meteorology obtained from the Met Office operational numerical weather prediction model, the Unified Model. Particles are advected according to three-dimensional winds with a random component used to represent the effects of atmospheric turbulence and can be removed from the model atmosphere by various processes. For modelling the dispersion of volcanic ash during the Eyjafjallajökull eruption, NAME is configured in the following manner. Material is released between the volcano summit and the plume rise height as estimated from observations taken by the Icelandic Met Office and measurements from radar and satellites. The particles are emitted following a prescribed size distribution with a density of 2300 kg/m3. The material is subjected to gravitational settling, and is deposited due to dry and wet deposition processes. There is no attempt in NAME to model volcano

  14. PS-InSAR measurements at the most active volcanoes in Iceland: role of the GEO supersite initiative in deformation monitoring at Bárðarbunga, Askja, Hekla, Katla and Eyjafjallajökull volcanoes

    NASA Astrophysics Data System (ADS)

    Parks, Michelle; Dumont, Stéphanie; Drouin, Vincent; Sigmundsson, Freysteinn; Spaans, Karsten; Hooper, Andrew; Ófeigsson, Benedikt; Árnadóttir, Þóra; Hreinsdóttir, Sigrún; Michalczewska, Karolina; Hjaltadóttir, Sigurlaug; María Friðriksdóttir, Hildur; Rut Hjartardóttir, Ásta; Magnússon, Eyjólfur; Vogfjörd, Kristín; Jónsdóttir, Kristín; Hensch, Martin; Guðmundsson, Gunnar; Geirsson, Halldór; Sturkell, Erik

    2015-04-01

    Analysis of a time series of ground deformation measurements at active volcanoes can provide an improved understanding of sub-volcanic and sub-aerial processes; including those related to magmatic, hydrothermal and structural development. Interpreting a long time series may also help determine background behavior, and identify any deviations from this, including the migration of new melt. We use Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) techniques to generate a time series of high-resolution deformation measurements, in the vicinity of the most active volcanoes in Iceland: Bárðarbunga, Askja, Hekla, Katla and Eyjafjallajökull and compare these to other geodetic measurements. A comprehensive network of continuous GPS stations is already deployed at these volcanoes and a series of campaign GPS measurements are routinely undertaken each summer. InSAR observations are complementary to these field based measurements and their high spatial resolution assists in resolving the geometry of the deformation field hence gaining improved constraints on the inferred source. The Committee on Earth Observation Satellites has recently declared Iceland a Permanent Geohazard Supersite, based on its propensity for relatively frequent eruptions and their potentially hazardous, long ranging effects. The recent Supersite award ensures a considerable amount of SAR data is made available for both past and future satellite acquisitions, including new X-band images (acquired by TerraSAR-X and Cosmo-SkyMed satellites), and historic C-band images from ERS and ENVISAT. We present a series of long-term deformation measurements for Hekla, Katla, Eyjafjallajökull and Askja volcanoes, derived using PS-InSAR techniques, and include recent interferograms spanning the 2014 unrest and eruption within the Bárðarbunga volcanic system. InSAR and tilt measurements at Hekla indicate renewed melt supply to a sub-volcanic reservoir after the last eruption in 2000. Recent

  15. Seismic tremor signals from Bárðarbunga, Grímsvötn and other glacier covered volcanoes in Iceland's Vatnajökull ice cap

    NASA Astrophysics Data System (ADS)

    Vogfjörd, Kristin S.; Eibl, Eva; Bean, Chris; Roberts, Matthew; Ófeigsson, Benedikt; Jóhannesson, Tómas

    2016-04-01

    Many of Iceland's most active volcanoes, like Grímsvötn and Bárðarbunga are located under glaciers giving rise to a range of volcanic hazards having both local and cross-border effects on humans, infrastructures and aviation. Volcanic eruptions under ice can lead to explosive hydromagmatic volcanism and generate small to catastrophic subglacial floods that may take hours to days to emerge from the glacier edge. Unrest in subglacial hydrothermal systems and the draining of subglacial meltwater can also lead to flood hazards. These processes and magma-ice interactions in general, generate seismic tremor signals that are commonly observed on seismic systems during volcanic unrest and/or eruptions. The tremor signals exhibit certain characteristics in frequency content, amplitude and behavior with time, but their characteristics overlap. Ability to discriminate between the different processes in real-time or near-real time can support early eruption and flood warnings and help mitigate their detrimental effects. One of the goals set forth in the FUTUREVOLC volcano supersite project was in fact to understand and discriminate between the different types of seismic tremor recorded at subglacial volcanoes. In that pursuit, the seismic network was expanded into the Vatnajökull glacier with four permanent stations on rock and in the ice, in addition to three seismic arrays installed at the ice margin, to enable location and possible tracking of the tremor sources. To track subglacial floods with better resolution three GPS receivers were also installed on the ice, one in an ice cauldron above the Skaftárkatlar geothermal melting area and two down glacier, above the track of the expected subglacial flood. During FUTUREVOLC this infrastructure has recorded all the types of process expected: Magmatic dyke intrusion and propagation from Bárðarbunga, subaerial fissure eruption of that magma at Holuhraun, two subglacial floods, one small and one large, draining from the

  16. Reply to the “Comment by Delmelle et al. (2013) on 'Scavenging of sulfur, halogens and trace metals by volcanic ash: The 2010 Eyjafjallajökull eruption' by Bagnato et al. (2013)”

    NASA Astrophysics Data System (ADS)

    Bagnato, E.; Aiuppa, A.; Bertagnini, A.; Bonadonna, C.; Cioni, R.; Pistolesi, M.; Pedone, M.; Hoskuldsson, A.

    2014-02-01

    With this short communication we address the principal issues raised by Delmelle et al. (2014) in relation to the work of Bagnato et al. (2013) concerning the 2010 eruption of Eyjafjallajökull, Iceland. The principal conclusions of the work of Bagnato et al. (2013) include the observation that protracted gas-aerosol interaction in the plume promotes selective leaching of cation species from ash, with alkalis and Ca (and, among trace elements, Zn and Cu) being more rapidly re-mobilized (and transferred to soluble surface salts) relative to more inert elements (Mg, Ti). They also observed that adsorption onto ash surfaces is a major atmospheric sink of volcanic acidic gases, with 282 tons of elemental sulfur and 605-691 tons of halogens being daily ground deposited via ash over Iceland in early May 2010. Acidic gas adsorption onto ash increases almost linearly with plume aging (e.g., upon increasing in-plume residence times of ash and gases), and is seen to proceed at about 3 time faster rates for HF than for SO2 and HCl. However, Delmelle et al. (2014) criticized our strategies for data acquisition, processing and interpretation. They also raised some objections concerning several key topics explored by Bagnato et al. (2013), with a special focus on the discussion of rates of interaction between ash particles and gases in a volcanic cloud, and the consequent formation of soluble salts on ash surfaces. They also considered incorrect the estimate of depositional fluxes and volatile budget for the Eyjafjallajökull eruption. While we appreciate the in-depth analysis of Delmelle et al. (2014), we show that most of their criticisms derive from a partial and sometimes incorrect understanding of the work of Bagnato et al. (2013), which overall led to unsupported conclusions and misleading analysis of the original results. Here, we present a detailed response to the comments of Delmelle et al. (2014), accompanied by additional explicative material. The principal

  17. Geodetic mass balance record with rigorous uncertainty estimates deduced from aerial photographs and LiDAR data - case study from Drangajökull ice cap, NW-Iceland

    NASA Astrophysics Data System (ADS)

    Magnússon, E.; Belart, J. M. C.; Pálsson, F.; Ágústsson, H.; Crochet, P.

    2015-09-01

    In this paper we describe how recent high resolution Digital Elevation Models (DEMs) can be used as constraints for extracting glacier surface DEMs from old aerial photographs and to evaluate the uncertainty of the mass balance record derived from the DEMs. We present a case study for Drangajökull ice cap, NW-Iceland. This ice cap covered an area of 144 km2 when it was surveyed with airborne LiDAR in 2011. Aerial photographs spanning all or most of the ice cap are available from survey flights in 1946, 1960, 1975, 1985, 1994 and 2005. All ground control points used to constrain the orientation of the aerial photographs were obtained from the high resolution LiDAR DEM (2 m × 2 m cell size and vertical accuracy < 0.5 m). The LiDAR DEM was also used to estimate errors of the extracted photogrammetric DEMs in ice and snow free areas, at nunataks and outside the glacier margin. The derived errors of each DEM were used to constrain a spherical variogram model, which along with the derived errors in ice and snow free areas were used as inputs into 1000 Sequential Gaussian Simulations (SGSim). The simulations were used to estimate the possible bias in the entire glaciated part of the DEM. The derived bias correction, varying in magnitude between DEMs from 0.03 to 1.66 m (1946 DEM) was then applied. The simulation results were also used to calculate the 95 % confidence level of this bias, resulting in values between ±0.21 m (in 2005) and ±1.58 m (in 1946). Error estimation methods based on more simple proxies would typically yield 2-4 times larger error estimates. The aerial photographs used were acquired between late June and early October. An additional bias correction was therefore estimated using a degree day model to obtain the volume change between the start of two hydrological years (1 October). This correction corresponds to an average elevation change of ~ -3 m in the worst case for 1960, or about ~ 2/3 of volume change between the 1960 and the 1975 DEMs. The

  18. The feeder system for the 2014 fissure eruption at Holuhraun, Bárðarbunga volcanic system, Iceland: Geodetic and seismic constraints on subsurface activity in the area north of the Vatnajökull ice cap

    NASA Astrophysics Data System (ADS)

    Dumont, Stéphanie; Parks, Michelle; Sigmundsson, Freysteinn; Hooper, Andy; Hreinsdóttir, Sigrun; Ófeigsson, Benedikt; Spaans, Karsten; Vogfjörd, Kristin; Jónsdóttir, Kristín; Hensch, Martin; Gudmundsson, Gunnar; Rafn Heimisson, Elias; Drouin, Vincent; Árnadóttir, Thóra; Pedersen, Rikke; Rut Hjartardóttir, Ásta; Magnússon, Eyjólfur

    2015-04-01

    An intense earthquake swarm began on 16 August 2014 at Bárðarbunga volcano under the Vatnajökull ice cap in Central Iceland. It marked the beginning of an intrusive activity, with a dyke propagating over 45 km northward. Such major magmatic activity has not been observed for the last three decades in Iceland, since the Krafla rifting episode 1975-1984. The dyke propagation stopped 15 days after the onset of the seismic activity, with the dyke distal end in the Holuhraun plain north of the Vatnajökull ice cap. A small 4 hour eruption marked the beginning of extrusive activity. A new fissure eruption opened up on 31 August at the northern dyke tip, with lava fountaining and feeding extensive lava flows. In January 2014 the surface covered by the lava had exceeded 80 km2, and the eruption activity does not show significant decline. We have carried out interferometric analysis of SAR data (InSAR) since the onset of the unrest. X-band satellite images from COSMO-SkyMed and TerraSAR-X satellites were acquired and analyzed to map ground surface deformation associated with the dyke emplacement. Despite most of the dyke propagation occurring under several hundreds meters of ice, the last 10 km were outside the ice cap, allowing better characterisation of the dyke-induced deformation. Here we focus on the deformation in the Holuhraun plain, in order to better understand the link between the surface deformation detected in the vicinity of the dyke by InSAR as well as GPS measurements, and the eruptive activity. The regular SAR acquisitions made over the Holuhraun area since the beginning of the unrest offer a unique opportunity to better understand the evolution of the intrusion feeding the fissure eruption. For that purpose, we focus on the faults and fissures forming the graben borders on the glacier as well as in the Holuhraun plain, initially mapped using high-resolution radar images, acquired by airborne radar. We extract movement along and perpendicular to these

  19. Airborne in-situ investigations of the Eyjafjallajökull volcanic ash plume on Iceland and over north-western Germany with light aircrafts and optical particle counters

    NASA Astrophysics Data System (ADS)

    Weber, K.; Eliasson, J.; Vogel, A.; Fischer, C.; Pohl, T.; van Haren, G.; Meier, M.; Grobéty, B.; Dahmann, D.

    2012-03-01

    During the time period of the eruption of the Icelandic volcano Eyjafjallajökull in April/May 2010 the Duesseldorf University of Applied Sciences has performed 14 research flights in situations with and without the volcanic ash plume over Germany. In parallel to the research flights in Germany three measurement flights have been performed by the University of Iceland in May 2010 over the western part of Iceland. During two of these flights the outskirts of the eruption plume were entered directly, delivering most direct measurements within the eruption plume during this eruptive event. For all the measurement flights reported here, light durable piston-motor driven aircrafts were used, which were equipped with optical particle counters for in-situ measurements. Real-time monitoring of the particle concentrations was possible during the flights. As different types of optical particle counters have been used in Iceland and Germany, the optical particle counters have been re-calibrated after the flights to the same standard using gravimetric reference methods and original Eyjafjallajökull volcanic ash samples. In-situ measurement results with high spatial resolution, directly from the eruption plume in Iceland as well as from the dispersed and several days old plume over Germany, are therefore presented here for the first time. They are normalized to the same ash concentration calibration standard. Moreover, airborne particles could be sampled directly out of the eruption plume in Iceland as well as during the flights over Germany. During the research flights over Iceland from 9 May 2011 to 11 May 2011 the ash emitted from the vent of the volcano turned out to be concentrated in a narrow well-defined plume of about 10 km width at a distance of 45-60 km away from the vent. Outside this plume the airborne ash concentrations could be proved to be below 50 μg m -3 over western Iceland. However, by entering the outskirts of the plume directly the research aircraft could

  20. Importance of nanoparticles and colloids from volcanic ash for riverine transport of trace elements to the ocean: evidence from glacial-fed rivers after the 2010 eruption of Eyjafjallajökull Volcano, Iceland.

    PubMed

    Tepe, Nathalie; Bau, Michael

    2014-08-01

    Volcanic ashes are often referenced as examples for natural nanoparticles, yet the particle size distribution <1000 nm is only rarely documented. We here report results of a geochemical study of glacial-fed rivers, glacial surface runoff, glacial base flow, and pure glacial meltwater from southern Iceland, that had been sampled 25 days after the explosive eruptions at Eyjafjallajökull in 2010. In addition to the dissolved concentrations of rare earth elements (REE), Zr, Hf, Nb, and Th in the 450 nm-filtered waters, we also studied the respective filter residues (river particulates >450 nm) and volcanic ash. In spite of the low solubilities and high particle-reactivities of the elements studied, most water samples show high dissolved concentrations, such as up to 971 ng/kg of Ce and 501 ng/kg of Zr. Except for the pure glacial meltwater and glacial base flow, all waters display the same shale-normalized REE patterns with pronounced light and heavy REE depletion and positive Eu anomalies. While such patterns are unusual for river waters, they are similar to those of the respective river particulates and the volcanic ash, though at different concentration levels. The distribution of dissolved Zr, Hf, Nb, and Th in the waters also matches that of filter residues and ash. This strongly suggests that in all 450 nm-filtered river waters, the elements studied are associated with solid ash particles smaller than 450 nm. This reveals that volcanic ash-derived nanoparticles and colloids are present in these glacial-fed rivers and that such ultrafine particles control the trace element distribution in the surface runoff. Subsequent to explosive volcanic eruptions, these waters provide terrigenous input from landmasses to estuaries, that is characterized by a unique trace element signature and that subsequent to modification by estuarine processes delivers a pulse of nutrients to coastal seawater in regions not affected by plume fall-out.

  1. Importance of nanoparticles and colloids from volcanic ash for riverine transport of trace elements to the ocean: evidence from glacial-fed rivers after the 2010 eruption of Eyjafjallajökull Volcano, Iceland.

    PubMed

    Tepe, Nathalie; Bau, Michael

    2014-08-01

    Volcanic ashes are often referenced as examples for natural nanoparticles, yet the particle size distribution <1000 nm is only rarely documented. We here report results of a geochemical study of glacial-fed rivers, glacial surface runoff, glacial base flow, and pure glacial meltwater from southern Iceland, that had been sampled 25 days after the explosive eruptions at Eyjafjallajökull in 2010. In addition to the dissolved concentrations of rare earth elements (REE), Zr, Hf, Nb, and Th in the 450 nm-filtered waters, we also studied the respective filter residues (river particulates >450 nm) and volcanic ash. In spite of the low solubilities and high particle-reactivities of the elements studied, most water samples show high dissolved concentrations, such as up to 971 ng/kg of Ce and 501 ng/kg of Zr. Except for the pure glacial meltwater and glacial base flow, all waters display the same shale-normalized REE patterns with pronounced light and heavy REE depletion and positive Eu anomalies. While such patterns are unusual for river waters, they are similar to those of the respective river particulates and the volcanic ash, though at different concentration levels. The distribution of dissolved Zr, Hf, Nb, and Th in the waters also matches that of filter residues and ash. This strongly suggests that in all 450 nm-filtered river waters, the elements studied are associated with solid ash particles smaller than 450 nm. This reveals that volcanic ash-derived nanoparticles and colloids are present in these glacial-fed rivers and that such ultrafine particles control the trace element distribution in the surface runoff. Subsequent to explosive volcanic eruptions, these waters provide terrigenous input from landmasses to estuaries, that is characterized by a unique trace element signature and that subsequent to modification by estuarine processes delivers a pulse of nutrients to coastal seawater in regions not affected by plume fall-out. PMID:24836133

  2. Mass eruption rates in pulsating eruptions estimated from video analysis of the gas thrust-buoyancy transition—a case study of the 2010 eruption of Eyjafjallajökull, Iceland

    NASA Astrophysics Data System (ADS)

    Dürig, Tobias; Gudmundsson, Magnús Tumi; Karmann, Sven; Zimanowski, Bernd; Dellino, Pierfrancesco; Rietze, Martin; Büttner, Ralf

    2015-11-01

    The 2010 eruption of Eyjafjallajökull volcano was characterized by pulsating activity. Discrete ash bursts merged at higher altitude and formed a sustained quasi-continuous eruption column. High-resolution near-field videos were recorded on 8-10 May, during the second explosive phase of the eruption, and supplemented by contemporary aerial observations. In the observed period, pulses occurred at intervals of 0.8 to 23.4 s (average, 4.2 s). On the basis of video analysis, the pulse volume and the velocity of the reversely buoyant jets that initiated each pulse were determined. The expansion history of jets was tracked until the pulses reached the height of transition from a negatively buoyant jet to a convective buoyant plume about 100 m above the vent. Based on the assumption that the density of the gas-solid mixture making up the pulse approximates that of the surrounding air at the level of transition from the jet to the plume, a mass flux ranging between 2.2 and 3.5 · 104 kg/s was calculated. This mass eruption rate is in good agreement with results obtained with simple models relating plume height with mass discharge at the vent. Our findings indicate that near-field measurements of eruption source parameters in a pulsating eruption may prove to be an effective monitoring tool. A comparison of the observed pulses with those generated in calibrated large-scale experiments reveals very similar characteristics and suggests that the analysis of near-field sensors could in the future help to constrain the triggering mechanism of explosive eruptions.

  3. Glacial and climatic evolution from the Little Ice Age last Maximum to the present in Tröllaskagi Peninsula (North Iceland): the case of Gljúlfurárjökull

    NASA Astrophysics Data System (ADS)

    María Fernández, Jose; Andres, Nuria; Tanarro, Luis Miguel; Palacios, David

    2015-04-01

    This paper presents the evolution of the Gljúlfurárjökull glacier (65°42'48'' N, 18°39'13'' W; 980 m), located at the headwall of the Skiðadalur valley, on the Tröllaskagi peninsula (N. Iceland). This is one of many small glaciers situated on the bottom of the Tröllaskagi valleys. This glacier is one of the few "clean" glaciers, i.e. not covered with boulders, as is the case with most of the glaciers on this peninsula. This makes the glacier especially sensitive to climate change, and it has retreated and advanced many times since its last maximum during the Little Ice Age (LIA) maximum in the mid- 19th century (Caseldine and Stötter, 1993), leaving a large number of moraine ridges. This paper analyses the change in this glacier from the LIA up to the present day, with reference to the variations in the surface, ELA and volume. Lichenometry and geomorphological field analysis were used to establish the exact limits of the glacier during the LIA last maximum. An aerial photo from 1946 and two orthophotos from 2000 and 2013 were also used. Using photointerpretation and Geographical Information Systems (GIS), the aerial photos were georeferenced to delimit the glacier in different years, analyse the surface and volume variations, and calculate the ELA for each date. The ELA analysis was carried out using the method: Accumulation Area Ratio (AAR 0.67). The results obtained with this method are: Little Ice Age Maximum: 945 m a.s.l. (almost the same ELA proposed by Caseldine and Stötter, 1993) 1946: 970 m a.s.l. 2000: 980 m a.s.l. 2013: 990 m a.s.l. The ice volume lost from LIA to 2000 was: 111.68 hm3 Reference Caseldine, C., Stötter, J., 1993. "Little Ice Age" glaciation of Tröllaskagi Peninsula, northern Iceland: Climatic implications for reconstructed equilibrium line altitudes (ELAs). Holocene 3: 357-366. Research funded by Cryocrisis project (CGL2012-35858), Government of Spain, and Nils Mobility projects (EEA GRANTS)

  4. Cosmogenic 36Cl exposure ages reveal a 9.3 ka BP glacier advance and the Late Weichselian-Early Holocene glacial history of the Drangajökull region, northwest Iceland

    NASA Astrophysics Data System (ADS)

    Brynjólfsson, Skafti; Schomacker, Anders; Ingólfsson, Ólafur; Keiding, Jakob K.

    2015-10-01

    We present twenty-four new cosmogenic isotope (36Cl) surface exposure ages from erratic boulders, moraine boulders and glacially eroded bedrock that constrain the late Weichselian to Holocene glacial history of the Drangajökull region, northwest Iceland. The results suggest a topographically controlled ice sheet over the Vestfirðir (Westfjords) peninsula during the last glaciation. Cold based non-erosive sectors of the ice sheet covered most of the mountains while fjords and valleys were occupied with erosive, warm-based ice. Old36Cl exposure ages from highlands and mountain plateaux (L8; 76.5 ka and H1; 41.6 ka) in combination with younger erratic boulders (L7; 26.2 and K1-K4; 15.0-13.8 ka) superimposed on such surfaces suggest the presence of non-erosive ice over uplands and plateaux in the Vestfirðir peninsula during the last glaciation. Glacially scoured terrain and erratic boulders yielding younger exposure ages (L1-L6; 11.3-9.1 ka and R1, R6-R7; 10.6-9.4 ka) in the lowland areas indicate that the valleys and fjords of the Vestfirðir peninsula were occupied by warm-based, dynamic ice during the last glaciation. The deglaciation of mountain Leirufjall by 26.2 ka BP suggests that ice thinning and deglaciation of some mountains and plateaux preceded any significant lateral retreat of the ice sheet. Subsequently this initial ice thinning was followed by break-up of the shelf based ice sheet off Vestfirðir about 15 ka BP. Hence, the new exposure ages suggest a stepwise asynchronous deglaciation on land, following the shelf break-up with some valleys and most of the highlands, ice free by 14-15 ka BP. The outermost moraine at the mouth of Leirufjörður is dated to 9.3 ka BP, and we suggest the moraine to be formed by a glacier re-advance in response to a cooler climate forced by the reduced Atlantic Meridional Overturning Circulation at around 9.3 ka BP. A system of moraines proximal to the 9.3 ka moraine in Leirufjörður as well as a 9.4 ka deglaciation age

  5. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

    ... to the earlier eruption, which began on April 14, 2010, the reaction to the new plume was better informed. Aircraft were diverted as needed ... that also accounts for wind-driven cloud motion during the time between image acquisitions. On the left (Figure 1) is a natural-color, ...

  6. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

    ... of the plume features between camera views. A quantitative computer analysis is necessary to separate out wind and height (see  Volcano ... NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Science Mission Directorate, Washington, D.C. The Terra spacecraft is managed ...

  7. Vigorous vent lightning observed during Eyjafjallajökull eruption

    NASA Astrophysics Data System (ADS)

    Wendel, JoAnna

    2014-04-01

    Volcanoes do more than spew rock and magma—they also produce electrical discharges. Various mechanisms, including high-energy silicate fracturing and boiling of water upon contact with magma, can produce electrical sparks near the vent of a volcano, whereas classic thunderstorm-like mixing in volcanic plumes can induce lightning kilometers above.

  8. A Model of Drumlin Growth at Múlajökull, Iceland

    NASA Astrophysics Data System (ADS)

    Iverson, N. R.; McCracken, R. G.; Zoet, L.; Schomacker, A.; Benediktsson, Í. Ö.; Johnson, M. D.; Hooyer, T.

    2015-12-01

    Observations at a rare, modern drumlin field—exposed by the recession of the Icelandic surge-type glacier, Múlajökull—allow a physically based model of drumlin formation to be formulated. These observations include the following: 1) drumlin relief resulted from basal till deposition on drumlins and erosion between them; 2) till deposition occurred during surges; 3) evidence of longitudinally compressive strain in till of the drumlins, as expected from negative flux divergence in a shearing bed, is absent; 4) during quiescent periods till was under higher effective normal stresses between drumlins than within them; 5) crevasse swarms are coincident with drumlins, and 6) water drainage at the glacier margin during the current quiescent state is through channels in low areas between drumlins. In the new model, basal sediment transport is controlled by patterns of effective stress that are different in the quiescent and surging states. During quiescent periods, slip of ice over a sinusoidally perturbed bed, crevasse formation, and flow of subglacial water toward R-channels that lie between drumlins result in effective stresses that increase toward channels and decrease from the stoss to the lee sides of drumlins. This effective-stress pattern causes till entrainment and erosion by regelation infiltration (Rempel, 2008, JGR, 113) that peaks at drumlin heads and near R-channels and is minimized on the lee sides of drumlins, while bed shear is inhibited by effective stresses too high to allow deformation. In contrast, during surges regelation infiltration cannot occur, and high rates of bed shear—assumed to be spatially uniform due to the lack of evidence for till flux divergence—cause basal melt rates sufficient to deposit, by lodgment, till layers of up to ~2.0 m in thickness during a single surge. With multiple surge cycles, drumlins grow in height and migrate downglacier, with resultant stratigraphy in broad agreement with field observations.

  9. Implications of Common Core State Standards on the Social Studies

    ERIC Educational Resources Information Center

    Kenna, Joshua L.; Russell, William B., III.

    2014-01-01

    Social studies teachers have often been on the outside looking in during much of the era billed as the standards-based educational reform (SBER), but with the adoption and implementation of the Common Core State Standards (CCSS), social studies teachers seem to have been invited back inside. Yet, how will the standards impact social studies…

  10. "Kull wahad la haalu": Feelings of isolation and distress among Yemeni immigrant women in San Francisco's Tenderloin.

    PubMed

    Volk, Lucia

    2009-12-01

    Recently arrived Yemeni immigrant women in San Francisco's Tenderloin neighborhood face a series of challenges as they go about living their everyday lives in a poor and crime-ridden neighborhood. They experience feelings of isolation and distress because of their limited English skills, their conservative Islamic dress that draws comments and unfriendly looks, and their household chores as mothers of often large families, which keep them busy at home. Despite living in close proximity to other Yemeni immigrants, these women feel profoundly lonely. In this study, based on interviews with 15 recently arrived Yemeni women, I show different "idioms of distress" that connect the women's emotional states to experiences of physical space and the body. I also raise methodological and epistemological questions about conducting anthropological work in communities whose members experience profound isolation.

  11. Physical characteristics of drumlins, with implications for their formation, at an active drumlin field, Múlajökull, Iceland

    NASA Astrophysics Data System (ADS)

    McCracken, R. G.; Iverson, N. R.; Benediktsson, Í. Ö.; Schomacker, A.; Johnson, M. D.; Zoet, L.; Hooyer, T.

    2015-12-01

    The forefield of Múlajökull—a warm-based, surge-type glacier in central Iceland—comprises the only known active drumlin field, with drumlins of similar morphometry to their Pleistocene counterparts but formed under better-known glaciological conditions. Study of till magnetic and till fabrics, till densities and preconsolidation stresses, and drumlin stratigraphy indicates that drumlin relief reflects both erosion and deposition: 1) the package of basal tills that constitutes the drumlins thickens where the forefield has experienced more surging, but uniformities are common on drumlin flanks, 2) attitudes of till layers and patterns of deformation within them indicate till deposition occurred on drumlin slopes rather than prior to drumlinization, and 3) past effective stresses during quiescent periods were highest in interdrumlin areas. These data suggest that erosion occurred during quiescence, rather than during surging, with erosion rates that increased under increasing effective stress. Stratigraphic evidence connecting specific till layers to surge moraines (Johnson et al., 2010, Geology 38, 943-6), on the other hand, indicates that deposition occurred during surges. Such deposition could have resulted from negative flux divergence in a shearing bed, but till fabrics provide no evidence for longitudinally compressive strain. A more likely origin for the basal till is that rapid, uniform bed shear during surging—consistent with the low and relatively uniform effective stresses expected during such periods—generated basal melt rates sufficient to release debris from ice and lodge it onto the bed. This conceptual model of alternating erosion and deposition implies drumlins formed by slow flowing ice elsewhere will be dominantly erosional, whereas drumlins with evidence of deposition may have experienced fast ice flow.

  12. Evaluating the Surface Conditions of Temperate Ice Cap Hofsjḋ {{o}}kull, Central Iceland, using H/A/barh {α } Decomposition of Fully-Polarimetric UAVSAR Data

    NASA Astrophysics Data System (ADS)

    Minchew, B. M.; Buckley, S. M.; Hensley, S.

    2010-12-01

    Fully-polarimetric SAR offers a means to study the dynamic changes in the near-surface of glaciers. Various decomposition methods can be used to relate the polarimetric signals to some general physical properties of the scattering mechanisms. Further research is needed to define the relationship between these polarimetric radar scattering properties, the radar penetration depth, and the near-surface properties (such as smoothness, contiguity, and moisture content). As a first step in establishing this relationship, we evaluate the scattering mechanisms of the temperate ice cap Hofsjḋokull, located in central Iceland, and compare them to the expected properties of the glacier. We decomposed fully-polarimetric L-band SAR data acquired from JPL's UAVSAR platform over Hofsjḋokull in the early mornings of June 10-12, 2009 using the Cloude-Pottier H/A/barh {α } eigenvector-based decomposition method. The three parameters of this method--entropy (H), anisotropy (A), and the scattering parameter (barh {α })--indicate if a dominant scattering mechanism exists and identify the mechanism of the most dominant scatterer(s)--surface, volumetric, or dihedral. We evaluate the three decomposed parameters as a function of elevation. These results show that the lowest elevation regions have mostly random scatterers in areas with steep topography and pseudo-random scatterers in areas with more moderate topographic slopes. Both terrain types show combinations of surface and volumetric scatterers but the dominant scatterer is indistinguishable. This behavior is consistent with the rough, wet surface of the ablation zone which should have little overlying snow cover in early summer. As the elevation increases towards the accumulation zone, surface scattering dominates. This dominance of surface scattering occurs at 1300-1500 m MSL: an area which has frequent freeze/thaw cycles and orographically-estimated air temperatures between -2 and 0 o C (based on data acquired at the nearby Hveravellir meteorological station at the time of data acquisition). At higher elevations the surface scatterer loses dominance as the probability of a secondary, volumetric scatterer increases. Above 1400 m MSL, both surface and volumetric scattering are present with approximately equivalent probabilities suggesting that the radar penetrates deepest in this area (volumetric scatterers) while being affected by ice lenses and snow layers (surface scatterers). We did not observe dihedral scattering anywhere on the glacier. To support the H/A/barh {α } results, we will present some Pauli decomposition results as well. The Pauli method yields three parameters: one which indicates surface scattering and two which show diplane scattering from scatterers with different corner orientations. The results of the Pauli method are consistent with those from the H/A/barh {α } method.

  13. Bacterial 16S diversity of basal ice, sediment, and the forefront of Svínafellsjökull glacier via isolation chips and classical culturing techniques

    NASA Astrophysics Data System (ADS)

    Toubes-Rodrigo, Mario; Cook, Simon; Elliott, David; Sen, Robin

    2016-04-01

    Sub-glacial microbes are receiving increased attention due to their central roles in storage and release of greenhouse gases, such as methane and CO2. Climate change driven warming and resulting glacier retreat exposes bedrock that can contribute to soil formation in which subglacial-released microorganisms may play a crucial role. Basal ice, which forms in the lowermost part of glaciers in the absence of light is characterised by a high debris concentration that can be regarded as a glacier niche that must be sustained by the utilisation of overridden organic matter or primary production based on chemolithotrophic metabolism. Compared to other glacial ecosystems, subglacial microbial ecology remains poorly understood, due to limited accessibility and difficulties associated with low microbial occupancy. In this study, different defined types of basal ice (cryofacies) were targeted, namely stratified cryofacies (highest sediment content, fine-grained), debris bands (intermediate debris content, coarse-grained) and dispersed cryofacies (low sediment content, polymodal). Debris bands have been suggested to form by the entrainment of sediment due to shearing forces near the bedrock. Internal glacial processes proceed to modify debris bands leading to the formation of dispersed cryofacies. Stratified cryofacies, result from a range of processes that confers high debris content with a characteristically layered appearance. Basal ice is involved in the creation of subglacial tills and therefore in moraine formation. Elemental analysis, using a portable X-ray fluorescence portable analyser (Olympus Delta), confirmed that debris bands and dispersed cryofacies were highly similar, and distinct from stratified cryofacies, which support the dispersed cryofacies formation hypothesis. Bacteria from basal ice, sediment and forefront soil were cultured via inserted isolation chips (ichips) and traditional extraction/dilution plating. Isolated bacteria were subsequently identified following 16S rRNA gene sequencing and phylogenetics. Basal ice communities comprised a mix of soil and glacial bacteria, with higher proportion of ice-related bacteria in dispersed cryofacies (Polaromonas sp, Flavobacterium xinjiangense) and a water (Arthrobacter agilis) and soil-related microorganisms (Pseudomonas sp) in the debris bands, similar to sub-glacial sediment. During debris band formation, microorganisms from bedrock and overridden soils can be entrained into the ice matrix and those which have adapted to icy conditions can proliferate, explaining the higher viable bacterial counts on dispersed ice as well as higher proportions of glacial isolated-related microorganisms. Once the subglacial sediment and basal ice are released from the glacier and as soil age increases, increased representation of soil-related microbiota (Arthrobacter alpinus, Stenotrophomonas rhizophila) were identified. The results in this study suggest cultivable communities shift in two directions: firstly, within the basal ice layer from subglacial sediment, dominated by soil and water communities towards dispersed ice with a high proportion of glacial communities. The other shift occurs when subglacial sediment is released into the forefront, where the composition changes towards a soil-like microbiota with increase in soil age.

  14. Geodetic observations of deep re-equilibration of magmatic systems accompanying the Hekla 2000 and Eyjafjallajökull 2010 eruptions, Iceland

    NASA Astrophysics Data System (ADS)

    Geirsson, Halldor; LaFemina, Peter; Sturkell, Erik; Ofeigsson, Benedikt; Arnadottir, Thora; Hreinsdottir, Sigrun; Hjaltadottir, Sigurlaug; Hooper, Andy; Lund, Bjorn; Schmidt, Peter; Sigmundsson, Freysteinn; Linde, Alan; Sacks, Selwyn

    2015-04-01

    Volcano geodesy most easily displays deformation from shallow deformation sources. However, with the expansion of geodetic networks and observations systems, there is growing evidence for far-field deformation at some volcanoes, indicating deeper processes within theses magmatic systems. We reflect here on crustal deformation from two recent eruptions in Iceland, the Hekla 2000 and Eyjafjallajokull 2010, which show signs of pressure changes at various crustal depths accompanying the eruptions. These eruptions were of similar eruptive volumes, approximately 0.2 km3, and were accompanied by crustal deformation relating to shallow dike and sill emplacements, in addition to more subtle and widespread crustal deformation caused by magma withdrawal. The crustal deformation associated with the Hekla 2000 eruption was captured by various geodetic methods, including continuous and episodic GPS, dry-tilt (i.e., short leveling lines), borehole strain, and InSAR. Continuous GPS data show deformation at >50 km from Hekla. We derive new deformation estimates from the episodic GPS network, and model the GPS displacements with previously published dry-tilt, InSAR, and borehole strain measurements in a formal joint inversion. While most of our data indicate a deep source of magma withdrawal (~20 km depth for a spherical source, or a pipe-like structure that reaches up to shallower depths), data from the borehole strain station closest to Hekla cannot be readily explained with a deep source. The borehole strain data at Hekla has good short-term resolution but poor long-term resolution, while the GPS, tilt, and InSAR measurements span a longer time interval. Therefore, we suggest the geodetic data from the Hekla 2000 eruption can best be interpreted with spatio-temporal progression of pressure changes in the magmatic system such that the co-eruptive signal was from a shallower (~10 km) source, which was followed by magma transport from deep to shallower depths before, during and after the eruption. For the Eyjafjallajokull 2010 eruption, we observe a wide-spread (>60 km from Eyjafjallajokull) deformation field with motion towards the volcano from an extensive network of episodic and continuous GPS stations. The distant continuous GPS stations clearly show that the time of deformation exceeds the eruptive period by several months, indicating that these stations are recording deep re-equilibration of the magmatic system under Eyjafjallajokull. Both volcanoes indicate a certain time-progression of deformation, where the deeper (>10 km) parts of the magmatic systems re-equilibrate in response to the shallower co-eruptive pressure decrease.

  15. Orbits of 10 interferometric binary systems calculated by using the improved Koval'skij method

    NASA Astrophysics Data System (ADS)

    Olević, D.; Cvetković, Z.

    2004-02-01

    Orbital elements are presented of 10 interferometric binary systems with no previous orbit determination: WDS 07143-2621 (FIN 323), WDS 12064-6543 (FIN 367Aa), WDS 12446-5717 (FIN 65), WDS 13320-6519 (FIN 369), WDS 13574-6229 (FIN 370), WDS 14189+5452 (CHR 137), WDS 14373-4608 (FIN 318 Aa), WDS 16115+0943 (FIN 354), WDS 17018-5108 (I 1306), WDS 17221-7007 (FIN 373). The method used (Koval'skij-Olević) is briefly described. Table 2 is only available in electronic form at http://www.edpsciences.org

  16. 75 FR 32987 - Orders Limiting Scheduled Operations at John F. Kennedy International Airport and Newark Liberty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-10

    ... for a period of five or more consecutive days. \\1\\ 74 FR 51648 (Oct. 7, 2009) (EWR); 74 FR 51650 (Oct... INFORMATION: Background On April 14, 2010, an eruption of the Eyjafjallaj kull volcano in Iceland began.... The Eyjafjallaj kull volcano is predicted to continue erupting over the next several months,...

  17. BAYONNE BRIDGE LOOKING EAST, BAYONNE TO THE LEFT (CONTACT PRINT ...

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

    BAYONNE BRIDGE LOOKING EAST, BAYONNE TO THE LEFT (CONTACT PRINT MADE FROM 5 1/4" X 4 1/2" NEGATIVE) - Bayonne Bridge, Spanning Kill Van Kull between Bayonne & Staten Island, Bayonne, Hudson County, NJ

  18. SPRINGING OF THE ARCH, SOUTH END OF BRIDGE, STATEN ISLAND ...

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

    SPRINGING OF THE ARCH, SOUTH END OF BRIDGE, STATEN ISLAND SIDE (CONTACT PRINT MADE FROM 5 1/4" X 4 1/2" NEGATIVE) - Bayonne Bridge, Spanning Kill Van Kull between Bayonne & Staten Island, Bayonne, Hudson County, NJ

  19. Comparison of satellite-derived with ground-based measurements of the fluctuations of the margins of Vatnajokull, Iceland, 1973-92

    USGS Publications Warehouse

    Williams, R.S.; Hall, D.K.; Sigurbsson, O.; Chien, J.Y.L.

    1997-01-01

    Vatnajo??kull, Iceland, is the Earth's most studied ice cap and represents a classical glaciological field site on the basis of S. Pa??lsson's seminal glaciological field research in the late 18th century. Since the 19th century, Vatnajo??kull has been the focus of an array of glaciological studies by scientists from many nations, including many remotesensing investigations since 1951. Landsat-derived positions of the termini of 11 outlet glaciers of Vatnajo??kull were compared with frontal positions of six of these 11 outlet glaciers determined by field observations during the period 1973-92. The largest changes during the 19 year period (1973-92) occurred in the large lobate, surge-type outlet glaciers along the southwestern, western, and northern margins of Vatnajo??kull. Tungnaa??rjo??kull receded - 1413 ?? 112 m (-1380 ?? l m from ground observations), and Bru??arjo??kull receded -1975 ?? 191 m (-2096 ?? 5 m from extrapolated ground observations) between 1973 and 1992. Satellite images can be used to delineate glacier margin changes on a time-lapse basis, if the glacier margin can be spectrally discriminated from terminal moraines and sandur deposits and if the advance/recession is larger than maximum image pixel size. "Local knowledge" of glaciers is critically important, however, in the accurate delineation of glacier margins on Landsat images.

  20. Surging glaciers in Iceland - research status and future challenges

    NASA Astrophysics Data System (ADS)

    Ingolfsson, Olafur

    2013-04-01

    Twenty six Icelandic outlet glaciers, ranging from 0.5-1.500 km2, are known to surge, with terminal advances ranging from of few tens of meters to about 10 km. The geomorphic signatures of surges vary, from large-scale folded and thrusted end moraine systems, extensive dead-ice fields and drumlinized forefields to drift sheets where fast ice-flow indicators are largely missing. Case studies from the forefields of Brúarjökull, Eyjabakkajökull and Múlajökull surging glaciers will be presented. At Brúarjökull, extremely rapid ice flow during surge was sustained by overpressurized water causing decoupling beneath a thick sediment sequence that was coupled to the glacier. The ice-marginal position of the 1890 surge is marked by a sedimentary wedge formed within five days and a large moraine ridge that formed in about one day ("instantaneous end-moraine"). Three different qualitative and conceptual models are required to explain the genesis of the Eyjabakkajökull moraines: a narrow, single-crested moraine ridge at the distal end of a marginal sediment wedge formed in response to decoupling of the subglacial sediment from the bedrock and associated downglacier sediment transport; large lobate end moraine ridges with multiple, closely spaced, asymmetric crests formed by proglacial piggy-back thrusting; moraine ridges with different morphologies may reflect different members of an end moraine continuum. A parallel study highlighting the surge history of Eyjabakkajökull over the last 4400 years suggests climate control on surge frequencies. The Múlajökull studies concern an active drumlin field (>100 drumlins) that is being exposed as the glacier retreats. The drumlins form through repeated surges, where each surge causes deposition of till bed onto the drumlin while similtaneously eroding the sides. Finally, a new landsystem model for surging North Iceland cirque glaciers will be introduced. References Benediktsson,I. Ö., Schomacker, A., Lokrantz, H. & Ing

  1. Colonization of maritime glacier ice by bdelloid Rotifera.

    PubMed

    Shain, Daniel H; Halldórsdóttir, Katrín; Pálsson, Finnur; Aðalgeirsdóttir, Guðfinna; Gunnarsson, Andri; Jónsson, Þorsteinn; Lang, Shirley A; Pálsson, Hlynur Skagfjörð; Steinþórssson, Sveinbjörn; Arnason, Einar

    2016-05-01

    Very few animal taxa are known to reside permanently in glacier ice/snow. Here we report the widespread colonization of Icelandic glaciers and ice fields by species of bdelloid Rotifera. Specimens were collected within the accumulation zones of Langjökull and Vatnajökull ice caps, among the largest European ice masses. Rotifers reached densities up to ∼100 individuals per liter-equivalent of glacier ice/snow, and were freeze-tolerant. Phylogenetic analyses indicate that glacier rotifers are polyphyletic, with independent ancestries occurring within the Pleistocene. Collectively, these data identify a previously undescribed environmental niche for bdelloid rotifers and suggest their presence in comparable habitats worldwide.

  2. 78 FR 28873 - Availability of Final Environmental Assessment and Finding of No Significant Impact for the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-16

    ... notice regarding our public dockets in the January 17, 2008, issue of the Federal Register (73 FR 3316... it, and announcing the dates and locations of two public meetings on the Draft EA (78 FR 740). On... for the Proposed Modification of the Bayonne Bridge Across the Kill Van Kull Between Bayonne,...

  3. Iceland Volcano

    Atmospheric Science Data Center

    2013-04-23

    ... layer of particles ranging in altitude from 6,000 to 21,000 feet. To compare its altitude and breadth, see the clouds over Northern Europe, ... of the Eyjafjallajökull cloud drifting as high as 30,000 feet above sea level. CALIPSO uses an innovative lidar, or pulsating laser, to ...

  4. Effects of present-day deglaciation in Iceland on mantle melt production rates

    NASA Astrophysics Data System (ADS)

    Schmidt, P.; Lund, B.; Hieronymus, C.; Maclennan, J.; Árnadóttir, T.; Pagli, C.

    2013-07-01

    Ongoing deglaciation in Iceland not only causes uplift at the surface but also increases magma production at depth due to decompression of the mantle. Here we study glacially induced decompression melting using 3-D models of glacial isostatic adjustment in Iceland since 1890. We find that the mean glacially induced pressure rate of change in the mantle increases melt production rates by 100-135%, or an additional 0.21-0.23 km3 of magma per year beneath Iceland. Approximately 50% of this melt is produced underneath central Iceland. The greatest volumetric increase is found directly beneath Iceland's largest ice cap, Vatnajökull, colocated with the most productive volcanoes. Our models of the effect of deglaciation on mantle melting predict a significantly larger volumetric response than previous models which only considered the effect of deglaciation of Vatnajökull, and only mantle melting directly below Vatnajökull. Although the ongoing deglaciation significantly increases the melt production rate, the increase in melt supply rate at the base of the lithosphere is delayed and depends on the melt ascent velocity through the mantle. Assuming that 25% of the melt reaches the surface, the upper limit on our deglaciation-induced melt estimates for central Iceland would be equivalent to an eruption the size of the 2010 Eyjafjallajökull summit eruption every seventh year.

  5. Iceland

    Atmospheric Science Data Center

    2013-04-17

    ... (visible in the lower right), and to several other lakes and geothermal areas. Hofsjökull (the Temple Glacier; 1760 meters) is the third ... the city, the "Bay of Smokes", is testimony to the region's geothermal activity. MISR was built and is managed by NASA's Jet Propulsion ...

  6. The Consortium of Advanced Residential Buildings (CARB) - A Building America Energy Efficient Housing Partnership

    SciTech Connect

    Robb Aldrich; Lois Arena; Dianne Griffiths; Srikanth Puttagunta; David Springer

    2010-12-31

    This final report summarizes the work conducted by the Consortium of Advanced Residential Buildings (CARB) (http://www.carb-swa.com/), one of the 'Building America Energy Efficient Housing Partnership' Industry Teams, for the period January 1, 2008 to December 31, 2010. The Building America Program (BAP) is part of the Department of Energy (DOE), Energy Efficiency and Renewable Energy, Building Technologies Program (BTP). The long term goal of the BAP is to develop cost effective, production ready systems in five major climate zones that will result in zero energy homes (ZEH) that produce as much energy as they use on an annual basis by 2020. CARB is led by Steven Winter Associates, Inc. with Davis Energy Group, Inc. (DEG), MaGrann Associates, and Johnson Research, LLC as team members. In partnership with our numerous builders and industry partners, work was performed in three primary areas - advanced systems research, prototype home development, and technical support for communities of high performance homes. Our advanced systems research work focuses on developing a better understanding of the installed performance of advanced technology systems when integrated in a whole-house scenario. Technology systems researched included: - High-R Wall Assemblies - Non-Ducted Air-Source Heat Pumps - Low-Load HVAC Systems - Solar Thermal Water Heating - Ventilation Systems - Cold-Climate Ground and Air Source Heat Pumps - Hot/Dry Climate Air-to-Water Heat Pump - Condensing Boilers - Evaporative condensers - Water Heating CARB continued to support several prototype home projects in the design and specification phase. These projects are located in all five program climate regions and most are targeting greater than 50% source energy savings over the Building America Benchmark home. CARB provided technical support and developed builder project case studies to be included in near-term Joule Milestone reports for the following community scale projects: - SBER Overlook at Clipper

  7. Iceland's Grímsvötn volcano erupts

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2011-05-01

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

  8. Zircon from historic eruptions in Iceland: Reconstructing storage and evolution of silicic magmas

    USGS Publications Warehouse

    Carley, T.L.; Miller, C.F.; Wooden, J.L.; Bindeman, I.N.; Barth, A.P.

    2011-01-01

    Zoning patterns, U-Th disequilibria ages, and elemental compositions of zircon from eruptions of Askja (1875 AD), Hekla (1158 AD), ??r??faj??kull (1362 AD) and Torfaj??kull (1477 AD, 871 AD, 3100 BP, 7500 BP) provide insights into the complex, extended, histories of silicic magmatic systems in Iceland. Zircon compositions, which are correlated with proximity to the main axial rift, are distinct from those of mid-ocean ridge environments and fall at the low-Hf edge of the range of continental zircon. Morphology, zoning patterns, compositions, and U-Th ages all indicate growth and storage in subvolcanic silicic mushes or recently solidified rock at temperatures above the solidus but lower than that of the erupting magma. The eruptive products were likely ascending magmas that entrained a zircon "cargo" that formed thousands to tens of thousands of years prior to the eruptions. ?? 2011 Springer-Verlag.

  9. Colonization of maritime glacier ice by bdelloid Rotifera.

    PubMed

    Shain, Daniel H; Halldórsdóttir, Katrín; Pálsson, Finnur; Aðalgeirsdóttir, Guðfinna; Gunnarsson, Andri; Jónsson, Þorsteinn; Lang, Shirley A; Pálsson, Hlynur Skagfjörð; Steinþórssson, Sveinbjörn; Arnason, Einar

    2016-05-01

    Very few animal taxa are known to reside permanently in glacier ice/snow. Here we report the widespread colonization of Icelandic glaciers and ice fields by species of bdelloid Rotifera. Specimens were collected within the accumulation zones of Langjökull and Vatnajökull ice caps, among the largest European ice masses. Rotifers reached densities up to ∼100 individuals per liter-equivalent of glacier ice/snow, and were freeze-tolerant. Phylogenetic analyses indicate that glacier rotifers are polyphyletic, with independent ancestries occurring within the Pleistocene. Collectively, these data identify a previously undescribed environmental niche for bdelloid rotifers and suggest their presence in comparable habitats worldwide. PMID:26932187

  10. Navigation study on improvements to existing federal navigation channels Arthur Kill Channel, Howland Hook Marine Terminal, Staten Island, New York

    SciTech Connect

    Not Available

    1985-06-01

    Improvements to the Arthur Kill Channel from the confluence of the Kill Van Kull Channel, the Arthur Kill Channel, and Newark Bay, along the Arthur Kill to the vicinity of Howland Hook Marine Terminal on Staten Island, New York are proposed. In addition, the study area was extended south from Howland Hook Terminal for approximately one mile in order to serve two oil terminals. The recommended improvements would include deepening to various depths down to 45 feet mean low water (MLW), widening the channel for unrestricted two-way traffic, and the creation of a turning basin. Specifically, a 41-foot MLW deep channel would be dredged in the previously authorized 35-foot MLW project in the Arthur Kill Channel from its confluence with the Newark Bay and Kill Van Kull channels to the Howland Hook Marine Terminal for a distance of approximately 2.1 miles. Also recommended are selected widenings and realignments of the channel at a depth of 41 feet in the interest of navigational safety. Additionally, a 40-foot MLW channel is proposed in the previously authorized 35-foot MLW project in the Arthur Kill Channel from the Howland Hook Marine Terminal to the Exxon Bayway and Gulfport facilities for a distance of approximately one mile. The channel would be selectively realigned to a 40-foot depth for navigational safety. No final determination has been made regarding the disposal of dredged material due to the uncertainty of available upland sites at this time. The turning basin would lie in the Kill Van Kull Channel at Bergen Point, where vessels turn from Kill Van Kull into Arthur Kill and Newark Bay. Total cost of the recommended plan is $49.4 million; the benefit-cost ratio is 4.35. The plan would take 4 years for completion and would have a projected life of 50 years.

  11. Characteristics of recessional moraines at a temperate glacier in SE Iceland: Insights into patterns, rates and drivers of glacier retreat

    NASA Astrophysics Data System (ADS)

    Chandler, Benjamin M. P.; Evans, David J. A.; Roberts, David H.

    2016-03-01

    Icelandic glaciers are sensitive to climate variability on short-term timescales owing to their North Atlantic maritime setting, and have been undergoing ice-marginal retreat since the mid-1990s. Recent patterns, rates and drivers of ice-frontal retreat at Skálafellsjökull, SE Iceland, are examined using small-scale recessional moraines as a geomorphological proxy. These small-scale recessional moraines exhibit distinctive sawtooth planform geometries, and are constructed by a range of genetic processes associated with minor ice-margin re-advance, including (i) combined push/squeeze mechanisms, (ii) bulldozing of pre-existing proglacial material, and (iii) submarginal freeze-on. Remote-sensing investigations and lichenometric dating highlight sequences of annually-formed recessional moraines on the northern and central parts of the foreland. Conversely, moraines are forming on a sub-annual timescale at the southeastern Skálafellsjökull margin. Using annual moraine spacing as a proxy for annual ice-margin retreat rates (IMRRs), we demonstrate that prominent periods of glacier retreat at Skálafellsjökull are coincident with those at other Icelandic outlet glaciers, as well as those identified at Greenlandic outlet glaciers. Analysis of IMRRs and climate data suggests summer air temperature, sea surface temperature and the North Atlantic Oscillation have an influence on IMRRs at Skálafellsjökull, with the glacier appearing to be most sensitive to summer air temperature. On the basis of further climate data analyses, we hypothesise that sea surface temperature may drive air temperature changes in the North Atlantic region, which in turn forces IMRRs. The increase in sea surface temperature over recent decades may link to atmospheric-driven variations in North Atlantic subpolar gyre dynamics.

  12. Unstructured Polyhedral Mesh Thermal Radiation Diffusion

    SciTech Connect

    Palmer, T.S.; Zika, M.R.; Madsen, N.K.

    2000-07-27

    Unstructured mesh particle transport and diffusion methods are gaining wider acceptance as mesh generation, scientific visualization and linear solvers improve. This paper describes an algorithm that is currently being used in the KULL code at Lawrence Livermore National Laboratory to solve the radiative transfer equations. The algorithm employs a point-centered diffusion discretization on arbitrary polyhedral meshes in 3D. We present the results of a few test problems to illustrate the capabilities of the radiation diffusion module.

  13. Effects of present day deglaciation in Iceland on the mantle melt production rate

    NASA Astrophysics Data System (ADS)

    Schmidt, Peter; Lund, Björn; Hieronymus, Christoph; Maclennan, John; Árnadóttir, Thora; Pagli, Carolina

    2013-04-01

    The ongoing deglaciation in Iceland not only causes uplift at the surface but also decompression of the mantle below, leading to increased magma production. Here we study glacially induced decompressional melting using 3D models of glacial isostatic adjustment in Iceland since 1890. We find that the mean glacially induced pressure rate of change in the mantle increases the melt production rate by 100-140%, or an additional 0.21-0.23 km3 of magma per year across Iceland. The greatest volumetric increase is found directly beneath the largest ice cap Vatnajökull, co-located with the most productive Icelandic volcanoes, where approximately 20% of the melt associated with glacial unloading is generated. If, in addition, melts are being channeled from the flanks of the melting region towards the central rift, up to 50% of the additional magma might reach the base of the elastic lithosphere beneath or close to the Vatnajökull ice cap, equivalent to more than half of the magma volume extruded during the 2010 Eyjafjallajökull summit eruption per year. Our results are significantly larger than previous estimates which considered only the effect of deglaciation of Vatnajökull and mantle melting directly beneath. Although the ongoing deglaciation in Iceland significantly increases the melt production rate in the mantle, the increase in melt supply rate (MSR) at the base of the lithosphere is delayed. If the melt ascent velocity is lower than 1,000 m/yr, the additional MSR caused by the last 120 years of deglaciation will continue to increase.

  14. Eyjabakkajokull Glacial Landsystem, Iceland: Geomorphic Impact of Multiple Surges

    NASA Astrophysics Data System (ADS)

    Ingolfsson, O.; Schomacker, A.; Benediktsson, I.

    2013-12-01

    A new glacial geomorphological map of the Eyjabakkajökull forefield in Iceland is presented. The map covers c. 60 km2 and is based on high-resolution aerial photographs recorded in August 2008 as well as field checking. Landforms are manually registered in a geographical information system (ArcGIS) based on inspection of orthorectified imagery and digital elevation models of the area. We mapped subglacially streamlined landforms such as flutes and drumlins on the till plain, supraglacial landforms such as ice-cored moraine, pitted outwash, and concertina eskers, and ice-marginal landforms such as the large, multi-crested 1890 surge end moraine and smaller single-crested end moraines. The glaciofluvial landforms are represented by outwash plains, minor outwash fans, and sinuous eskers. Extramarginal sediments were also registered and consist mainly of old sediments in wetlands or locally weathered bedrock. Eyjabakkajökull has behaved as a surge-type glacier for 2200 years; hence, the mapped landforms originate from multiple surges. Landforms such as large glaciotectonic end moraines, hummocky moraine, long flutes, crevasse-fill ridges, and concertina eskers are characteristic for surge-type glaciers. The surging glacier landsystem of Eyjabakkajökull serves as a modern analog to the landsystems of terrestrial paleo-ice streams.

  15. Using A Wireless In Situ Probe To Monitor Subglacial Processes

    NASA Astrophysics Data System (ADS)

    Hart, J. K.; Martinez, K.

    2010-12-01

    The Glacsweb system (http://envisense.org/glacsweb/) has been installed in two glaciers; Briksdalsbreen, Norway and Skalafellsjökull, Iceland. These are valley glaciers which show evidence of subglacial deformation in the foreland, with flutes and push moraines. Briksdalsbreen was calving into a glacial lake. This advanced 390m between 1987-1996 and then retreated over 460m between 1996 and 2008. Skalafellsjökull is landbased with a similar (but smaller scale) pattern of recent glacier marginal. Micro-sensors housed within the Glacsweb probes (0.16m long) measured water pressure, probe deformation, resistance, tilt and probe temperature within the ice or till. These data were recorded at a number of times during the day, and transmitted to a base station located on the glacier surface. Probe and meteorological data were sent once a day to a local mains powered computer, where it was forwarded to a web server in the UK. At Briksdalsbreen this operated from August 2004 to August 2006, and at Skalafellsjökull, it operated from August 2008 onwards (with periods when the system was disconnected). We compare the subglacial processes recorded throughout the year at the two sites. In particular, changes in water pressure, case stress, till water contents and till temperatures.

  16. Element variations in rhyolitic magma resulting from gas transport

    NASA Astrophysics Data System (ADS)

    Berlo, K.; Tuffen, H.; Smith, V. C.; Castro, J. M.; Pyle, D. M.; Mather, T. A.; Geraki, K.

    2013-11-01

    Tuffisite veins are glass-filled fractures formed when magma fragments during degassing within the conduit. These veins form transient channels through which exsolved gases can escape from magma. The purpose of this study is to determine the extent to which chemical heterogeneity within the melt results from gas transport, and assess how this can be used to study magma degassing. Two tuffisite veins from contrasting rhyolitic eruptions at Torfajökull (Iceland) and Chaitén (Chile) were studied in detail. The tuffisite vein from Torfajökull is from a shallow dissected conduit (∼70 ka) that fed a degassed lava flow, while the sample from Chaitén was a bomb ejected during the waning phases of Plinian activity in May 2008. The results of detailed in situ chemical analyses (synchrotron XRF, FTIR, LA-ICP-MS) show that in both veins larger vesiculated fragments are enriched in volatile elements (Torfajökull: H, Li, Cl; Chaitén: Li, Cl, Cu, Zn, As, Sn, Sb) compared to the host, while the surrounding smaller particles are depleted in the Torfajökull vein (Li, Cl, Zn, Br, Rb, Pb), but enriched in the Chaitén vein (K, Cu, Zn, As, Mo, Sb, Pb). The lifespans of both veins and the fluxes of gas and particles through them can be estimated using diffusion profiles and enrichment factors. The Torfajökull vein had a longer lifespan (∼a day) and low particle velocities (∼cm/s), while the Chaitén vein was shorter lived (<1 h) with a high gas velocity (∼m/s). These differences are consistent with the contrasting eruption mechanisms (effusive vs. explosive). The amount of magma that degassed through the Chaitén vein is more than ten times the volume of the vein itself, requiring the vein to tap into pre-exsolved gas pockets. This study highlights that tuffisite veins are highly efficient gas pathways and thereby impart chemical diversity in volatile elements on the melt.

  17. Can vesicle size distributions predict eruption intensity during volcanic activity?

    NASA Astrophysics Data System (ADS)

    LaRue, A.; Baker, D. R.; Polacci, M.; Allard, P.; Sodini, N.

    2013-06-01

    We studied three-dimensional (3-D) vesicle size distributions by X-ray microtomography in scoria collected during the relatively quiescent Phase II of the 2010 eruption at Eyjafjallajökull volcano, Iceland. Our goal was to compare the vesicle size distributions (VSDs) measured in these samples with those found in Stromboli volcano, Italy. Stromboli was chosen because its VSDs are well-characterized and show a correlation with eruption intensity: typical Strombolian activity produces VSDs with power-law exponents near 1, whereas larger and more energetic Vulcanian-type explosions and Plinian eruptions produce VSDs with power-law exponents near 1.5. The hypothesis to be tested was whether or not the samples studied in this work would contain VSDs similar to normal Strombolian products, display higher power-law exponents, or be described by exponential functions. Before making this comparison we tested the hypothesis that the phreatomagmatic nature of the Eyjafjallajökull eruption might have a significant effect on the VSDs. We performed 1 atm bubble-growth experiments in which the samples were inundated with water and compared them to similar, control, experiments without water inundation. No significant differences between the VSDs of the two sets of experiments were found, and the hypothesis is not supported by the experimental evidence; therefore, VSDs of magmatic and phreatomagmatic eruptions can be directly compared. The Phase II Eyjafjallajökull VSDs are described by power law exponents of ~ 0.8, typical of normal Strombolian eruptions. The comparable VSDs and behavior of Phase II of the Eyjafjallajökull 2010 eruption to Stromboli are interpreted to be a reflection of similar conduit systems in both volcanoes that are being constantly fed by the ascent of deep magma that mixes with resident magma at shallow depths. Such behavior implies that continued activity during Phase II of the Eyjafjallajökull eruption could be expected and would have been predicted

  18. Seismic unrest at Katla Volcano- southern Iceland

    NASA Astrophysics Data System (ADS)

    jeddi, zeinab; Tryggvason, Ari; Gudmundsson, Olafur; Bödvarsson, Reynir; SIL Seismology Group

    2014-05-01

    Katla volcano is located on the propagating Eastern Volcanic Zone (EVZ) in South Iceland. It is located beneath Mýrdalsjökull ice-cap which covers an area of almost 600 km2, comprising the summit caldera and the eruption vents. 20 eruptions between 930 and 1918 with intervals of 13-95 years are documented at Katla which is one of the most active subglacial volcanoes in Iceland. Eruptions at Katla are mainly explosive due to the subglacial mode of extrusion and produce high eruption columns and catastrophic melt water floods (jökulhlaups). The present long Volcanic repose (almost 96 years) at Katla, the general unrest since 1955, and the 2010 eruption of the neighbouring Eyjafjallajökull volcano has prompted concerns among geoscientists about an imminent eruption. Thus, the volcano has been densely monitored by seismologists and volcanologists. The seismology group of Uppsala University as a partner in the Volcano Anatomy (VA) project in collaboration with the University of Iceland and the Icelandic Meteorological Office (IMO) installed 9 temporary seismic stations on and around the Mýrdalsjökull glacier in 2011. Another 10 permanent seismic stations are operated by IMO around Katla. The project's data collection is now finished and temporary stations were pulled down in August 2013. According to seismicity maps of the whole recording period, thousands of microearthquakes have occurred within the caldera region. At least three different source areas are active in Katla: the caldera region, the western Godaland region and a small cluster at the southern rim of Mýrdalsjökull near the glacial stream of Hafursarjökull. Seismicity in the southern flank has basically started after June 2011. The caldera events are mainly volcano-tectonic, while western and southern events are mostly long period (lp) and can be related to glacial or magmatic movement. One motivation of the VA Katla project is to better understand the physical mechanism of these lp events. Changes

  19. Infrasound network implementation in Iceland - examples of volcano monitoring in an extreme environment

    NASA Astrophysics Data System (ADS)

    Jónsdóttir, Kristín; Ripepe, Maurizio; Barsotti, Sara; Björnsson, Halldór; Del Donne, Dario; Vogfjörð, Kristín

    2015-04-01

    The installation of a network of infrasound arrays for volcano monitoring has been initiated in Iceland. In collaboration with the University of Florence (UNIFI), The Icelandic Meteorological Office (IMO) has been operating infrasound arrays since the Eyjafjallajökull eruption in 2010. An important support came through the 26 partner FP7 FUTUREVOLC project which runs from 2012 - 2016. This project which is relevant to the EU "Supersite concept" for long term monitoring in geologically active regions of Europe, is led by the University of Iceland together with IMO which leads long-term monitoring of geohazards in Iceland and is responsible for maintaining instrument networks for this purpose. As a part of the ground based FUTUREVOLC network, infrasound arrays, are used to monitor volcanic eruptive activity. The arrays are composed of 4 elements with a triangular geometry and an aperture of 120 m where each element has a differential pressure transducer with a sensitivity of 25 mV/Pa in the frequency band 0.001-50 Hz and a noise level of 10-2 Pa. Infrasound is recorded on site at 100 Hz and 24 bits and transmitted via Internet link both to the IMO and UNIFI. Three arrays are installed in South Iceland, one in Gunnarsholt, one in Þjórsárdalur and one in Kirkjubæjarklaustur. These places were chosen with the aim to optimize wind noice reduction (onsite bushes and trees) and close proximity to volcanoes such as Hekla, Katla, Torfajökull, Eyjafjallajökull, Vestmannaeyjar and the Vatnajökull ice cap which covers four central volcanoes known for explosive eruptions. In September 2014, the fourth array was installed a few km north of Vatnajökull glacier, just north of the large effusive eruption in Holuhraun which started on 29 August 2014 and is still ongoing in January 2015. The eruption is associated with the ongoing Bárðarbunga volcanic unrest and caldera collapse which is being monitored closely by the IMO and FUTUREVOLC partners. The new array has the

  20. Ambient Noise Surface Wave Tomography of the volcanic systems of eastern Iceland

    NASA Astrophysics Data System (ADS)

    Green, R. G.; Priestley, K. F.; White, R. S.

    2015-12-01

    The Vatnajökull region of central-east Iceland lies above the head of the Iceland mantle plume where the crust is thickest due to enhanced melt supply. As a result the region contains a high density of volcanic rift systems, with six large subglacial central volcanoes. Due to the ice cover, the geological structure of the area and the location of past eruptions are poorly known. Imaging of the crustal velocity heterogeneities beneath the ice sheet aims to reveal much in terms of the structure of these volcanic plumbing systems. Mapping of significant velocity changes through time may also be indicative of movement of melt around the central volcanoes; one of which (Bárðarbunga) experienced a major rifting event in August 2014 (Sigmundsson et al. Nature 2015, Green et al. Nature Geosci. 2015). We present results from tomographic imaging of the volcanic systems in the region, using continuous data from a local broadband seismic network in central-east Iceland which provides excellent ray path coverage of the volcanic systems. This is supplemented by data from the HOTSPOT and ICEMELT experiments and the permanent monitoring stations of the Icelandic Meteorological Office. We process the continuous data following Benson et al. 2007 and automatic frequency-time analysis (FTAN) routines are used to extract more than 9000 dispersion measurements. We then generate Rayleigh wave group velocity maps which we present here. We find low velocity regions beneath the Vatnajökull icecap which are bounded by the surface expression of the volcanic rift systems. The lower velocities also extend north-west to the volcanic system under the Hofsjökull ice cap, and northwards towards Askja and the volcanic systems of the northern volcanic zone. We also produce locations and focal mechanisms of earthquakes caused by magmatic and hydrothermal activity to correlate structure with the activity of the volcanic systems.

  1. Satellite Monitoring of Ash and Sulphur Dioxide for the mitigation of Aviation Hazards: Part II. Validation of satellite-derived Volcanic Sulphur Dioxide Levels.

    NASA Astrophysics Data System (ADS)

    Koukouli, MariLiza; Balis, Dimitris; Dimopoulos, Spiros; Clarisse, Lieven; Carboni, Elisa; Hedelt, Pascal; Spinetti, Claudia; Theys, Nicolas; Tampellini, Lucia; Zehner, Claus

    2014-05-01

    The eruption of the Icelandic volcano Eyjafjallajökull in the spring of 2010 turned the attention of both the public and the scientific community to the susceptibility of the European airspace to the outflows of large volcanic eruptions. The ash-rich plume from Eyjafjallajökull drifted towards Europe and caused major disruptions of European air traffic for several weeks affecting the everyday life of millions of people and with a strong economic impact. This unparalleled situation revealed limitations in the decision making process due to the lack of information on the tolerance to ash of commercial aircraft engines as well as limitations in the ash monitoring and prediction capabilities. The European Space Agency project Satellite Monitoring of Ash and Sulphur Dioxide for the mitigation of Aviation Hazards, was introduced to facilitate the development of an optimal End-to-End System for Volcanic Ash Plume Monitoring and Prediction. This system is based on comprehensive satellite-derived ash plume and sulphur dioxide [SO2] level estimates, as well as a widespread validation using supplementary satellite, aircraft and ground-based measurements. The validation of volcanic SO2 levels extracted from the sensors GOME-2/MetopA and IASI/MetopA are shown here with emphasis on the total column observed right before, during and after the Eyjafjallajökull 2010 eruptions. Co-located ground-based Brewer Spectrophotometer data extracted from the World Ozone and Ultraviolet Radiation Data Centre, WOUDC, were compared to the different satellite estimates. The findings are presented at length, alongside a comprehensive discussion of future scenarios.

  2. Real time retrieval of volcanic cloud particles and SO2 by satellite using an improved simplified approach

    NASA Astrophysics Data System (ADS)

    Pugnaghi, Sergio; Guerrieri, Lorenzo; Corradini, Stefano; Merucci, Luca

    2016-07-01

    Volcanic plume removal (VPR) is a procedure developed to retrieve the ash optical depth, effective radius and mass, and sulfur dioxide mass contained in a volcanic cloud from the thermal radiance at 8.7, 11, and 12 µm. It is based on an estimation of a virtual image representing what the sensor would have seen in a multispectral thermal image if the volcanic cloud were not present. Ash and sulfur dioxide were retrieved by the first version of the VPR using a very simple atmospheric model that ignored the layer above the volcanic cloud. This new version takes into account the layer of atmosphere above the cloud as well as thermal radiance scattering along the line of sight of the sensor. In addition to improved results, the new version also offers an easier and faster preliminary preparation and includes other types of volcanic particles (andesite, obsidian, pumice, ice crystals, and water droplets). As in the previous version, a set of parameters regarding the volcanic area, particle types, and sensor is required to run the procedure. However, in the new version, only the mean plume temperature is required as input data. In this work, a set of parameters to compute the volcanic cloud transmittance in the three quoted bands, for all the aforementioned particles, for both Mt. Etna (Italy) and Eyjafjallajökull (Iceland) volcanoes, and for the Terra and Aqua MODIS instruments is presented. Three types of tests are carried out to verify the results of the improved VPR. The first uses all the radiative transfer simulations performed to estimate the above mentioned parameters. The second one makes use of two synthetic images, one for Mt. Etna and one for Eyjafjallajökull volcanoes. The third one compares VPR and Look-Up Table (LUT) retrievals analyzing the true image of Eyjafjallajökull volcano acquired by MODIS aboard the Aqua satellite on 11 May 2010 at 14:05 GMT.

  3. Experimental studies of heat transfer at the dynamic magma ice/water interface: Application to subglacially emplaced lava

    NASA Astrophysics Data System (ADS)

    Oddsson, Björn; Gudmundsson, Magnús T.; Sonder, Ingo; Zimanowski, Bernd; Schmid, Andrea

    2016-05-01

    Experiments simulating processes operating in volcano-ice interactions were carried out to explain and quantify lava thermal properties and processes of heat transfer from pure lava melt to water and ice and from hot crystalline lava to water. The samples used (70-200 g) were obtained from an intermediate lava flow (benmoreite-trachyte) that was emplaced under and within the outlet glacier Gígjökull in the 2010 eruption of Eyjafjallajökull. Experiments involved settings with direct contact between ice and lava, and settings where melt and ice were separated by a few centimeters. Direct contact involved melt being emplaced on ice and ice placed on melt. The direct contact experiments provided initial heat flux of up to 900 kW m-2 at an initially lava melt surface temperature of 1100°C, declining to <100 kW m-2 at 200-300°C within 1-2 min, while the experiments without melt-ice contact yielded an initial maximum of 100-180 kW m-2 dropping to 50-80 kW m-2 in 2-3 min. In other experiments, where cubes of hot crystalline lava were subjected to forced convection of water at initial temperature of 20-30°C, initial heat fluxes of 400-770 kW m-2 were followed by fast decline to <100 kW m-2 in 15-35 s, the rate depending on cube size. The hot rock experiments provided thermal conductivity values of 1.2-1.7 W m-1K-1 and diffusivity of about 9 × 10-7 m2s-1. Values for heat flux obtained in these experiments are in the same range as those obtained from field observations of the lava emplacement in the Eyjafjallajökull 2010 eruption.

  4. Dyke propagation mechanisms and the immediate pre- and syn-eruptive seismicity of the 2014 Holuhraun fissure eruption, Iceland

    NASA Astrophysics Data System (ADS)

    Woods, Jennifer; Ágústsdóttir, Thorbjörg; Greenfield, Tim; Green, Robert G.; White, Robert S.; Brandsdóttir, Bryndís; Steinthórsson, Sveinbjörn; Redfern, Simon

    2015-04-01

    We present data from our dense seismic array which captured the micro-seismicity associated with the propagating dyke intrusion from the subglacial Bárðarbunga volcano, during the 24 hours preceding and following the onset of effusive magmatism at the Holuhraun lava field in central Iceland. The Bárðarbunga volcano is located at the centre of the Iceland hot spot within the Eastern Rift Zone, beneath the Vatnajökull ice cap. Local magmatic intrusions can be tracked through the swarms of micro-seismicity accompanying dyke propagation, arising from crustal failure and fracture of both the country rock and solidifying magma plugs. August 2014 saw the beginning of a period of unrest of Bárðarbunga volcano during which a dyke propagated first out of the caldera and then towards the northeast. It continued north of the Dyngjujökull outlet glacier and resulted in a fissure eruption in the old Holuhraun lava field on 29 August 2014. At time of writing it has erupted ~1km3 of lava covering over 64km2, making this the largest eruption in Iceland for 150 years. Our extensive, local seismic network covers the numerous volcanic systems beneath the Vatnajökull glacier and their transecting fissure swarms (rifting units) along the divergent plate boundary. This work focusses on the immediate pre- and syn-eruptive seismicity of the 2014 Holuhraun fissure eruption. Rock fracture mechanisms are determined from fault plane solutions of these seismic events, produced as the magma migrated from beneath the surface to the eruption site.

  5. Assessing hazards to aviation from sulfur dioxide emitted by explosive Icelandic eruptions

    NASA Astrophysics Data System (ADS)

    Schmidt, Anja; Witham, Claire S.; Theys, Nicolas; Richards, Nigel A. D.; Thordarson, Thorvaldur; Szpek, Kate; Feng, Wuhu; Hort, Matthew C.; Woolley, Alan M.; Jones, Andrew R.; Redington, Alison L.; Johnson, Ben T.; Hayward, Chris L.; Carslaw, Kenneth S.

    2014-12-01

    Volcanic eruptions take place in Iceland about once every 3 to 5 years. Ash emissions from these eruptions can cause significant disruption to air traffic over Europe and the North Atlantic as is evident from the 2010 eruption of Eyjafjallajökull. Sulfur dioxide (SO2) is also emitted by volcanoes, but there are no criteria to define when airspace is considered hazardous or nonhazardous. However, SO2 is a well-known ground-level pollutant that can have detrimental effects on human health. We have used the United Kingdom Met Office's NAME (Numerical Atmospheric-dispersion Modelling Environment) model to simulate SO2 mass concentrations that could occur in European and North Atlantic airspace for a range of hypothetical explosive eruptions in Iceland with a probability to occur about once every 3 to 5 years. Model performance was evaluated for the 2010 Eyjafjallajökull summit eruption against SO2 vertical column density retrievals from the Ozone Monitoring Instrument and in situ measurements from the United Kingdom Facility for Airborne Atmospheric Measurements research aircraft. We show that at no time during the 2010 Eyjafjallajökull eruption did SO2 mass concentrations at flight altitudes violate European air quality standards. In contrast, during a hypothetical short-duration explosive eruption similar to Hekla in 2000 (emitting 0.2 Tg of SO2 within 2 h, or an average SO2 release rate 250 times that of Eyjafjallajökull 2010), simulated SO2 concentrations are greater than 1063 µg/m3 for about 48 h in a small area of European and North Atlantic airspace. By calculating the occurrence of aircraft encounters with the volcanic plume of a short-duration eruption, we show that a 15 min or longer exposure of aircraft and passengers to concentrations ≥500 µg/m3 has a probability of about 0.1%. Although exposure of humans to such concentrations may lead to irritations to the eyes, nose and, throat and cause increased airway resistance even in healthy individuals

  6. Discovery of the Largest Historic Silicic Submarine Eruption

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  7. Quantification of Sediment Transport During Glacier Surges and its Impact on Landform Architecture

    NASA Astrophysics Data System (ADS)

    Kjaer, K. H.; Schomacker, A.; Korsgaard, N. J.; Benediktsson, I. O.

    2008-12-01

    Multi-temporal DEMs (Digital Elevation Models) of glaciers and ice streams have successfully been used for extraction of changes in ice volume over time. In this study, we analysed DEMs of the Brúarjökull glacier forefield (Iceland) for 1945, prior to the last surge in 1964, and for 2003 in order to assess the effect of the surge on the sediment architecture in the forefield. The pre- and post-surge DEMs allow direct quantification of the sediment volumes that were re-distributed in the forefield by the surging ice mass in 1964. The surge-type glacier Brúarjökull has experienced six surges during the last four centuries; these are the largest surges known to have occurred in Iceland. During the most recent surge in 1963-64, the glacier advanced 8 km over a period of c. 3 months with a maximum ice flow velocity of 5 m/hr, and 700 km3 of ice were moved downglacier. The continued recession of Brúarjökull since the 1963-64 surge reveals a young landscape consisting of widely spaced and elongated bedrock hills interspaced with shallow sedimentary basins. The majority of the forefield is covered with a basal till sheet or glaciofluvial outwash fans. Mapping of the sediment thickness in the glacier forefield shows higher accumulation along ice marginal positions related to wedge formation during extremely rapid ice flow. Fast flow was sustained by overpressurized water causing sediment-bedrock decoupling beneath a thick sediment sequence that was coupled to the glacier. Elevation differences between the terrain surface in 1945 and 2003 confirm this scenario as huge quantities of sediment was eroded, deformed and transported during the last surge event. On the scale of individual landforms, it appears for a drumlin surface that is has been lowered 20 m from 1945-2003. Dead-ice melting can explain roughly 8 m of this lowering. Thus, the drumlin must have experienced 12 m of subglacial erosion during the 1964 surge. The imprint of at least four landform generations is

  8. Frequency, triggering factors and possible consequences of mass movements on outlet glaciers in Iceland.

    NASA Astrophysics Data System (ADS)

    Saemundsson, Thorsteinn; Margeirsson, Guðbjörn

    2016-04-01

    During the last 15 years several mass movements of various size and origin, e.g. rock avalanches, rock slides and debris slides have been observed to have fall on outlet glaciers in Iceland. This should not come as a surprise in this type of glacial environment, but in a way it does. When looking at the history only few mass movements are recorded to have fall on outlet glaciers in Iceland, during the decades before the year 2000 or since 1960. This "lack of mass movements" can be explained by the fact that fewer observations and monitoring were done in the past, but is it so or are we seeing increasing activity? Looking at the distribution of the known mass movements, two activity periods cam be identified. The former one around 1970 and the second one starting around 2000 and is still ongoing. Both of these periods are characterized by warmer climate leading to retreating phases of glaciers. Two larger mass movements are known from these two retreating periods. The former one occurred in January 1967. Then a large rockslide fell on the snout and into the glacial lake of the Steinholtsjökull outlet glacier in the northern side of the Eyjafjallajökull ice cap. The rockslide broke up the snout of the glacier and caused large floodwave bursting down the Steinholtsdalur valley transporting large volume of sediments down its path. The later one occurred in 2007, when a large rockavalanche fell on the Morsárjökull outlet glacier, in the southern side of the Vatnajökull ice cap. The avalanche debris covered around 1/5 of the glacier surface. Today the retreat and thinning of glaciers in Iceland are extremely rapid. The consequences of such a rapid retreat are e.g. unstable valley slopes surrounding the outlet glaciers, both in loose sediments and bedrock, thawing of mountain permafrost and not least formation of glacial lakes in front of the rapid retreating ice margins. Such conditions can become extremely hazardous, as seen by the above mentioned examples, both

  9. Soil evolution in the active enviroment of Öræfi district, S.E Iceland

    NASA Astrophysics Data System (ADS)

    Þorbjarnarson, Höskuldur; Gísladóttir, Guðrún; Erlendsson, Egill; Mankasingh, Utra

    2015-04-01

    Soil is a resource of critical importance to life on earth. It is the foundation for the growth of vegetation and therefore food production and our existence. Soil also regulates and distributes nutrients and water. Soils of Iceland are in many respects special; they are relatively young and have only been forming since the end of the Pleistocene when glaciers retreated from the land. To this date new soil is continually forming on land where glaciers are retreating or where new land is formed due to volcanic activity. Volcanic soils (andosol/andisol) generated from airborne volcanic ejecta (tephra) are the most common form of soils in Iceland. Windblown material also contributes to their formation. Rapid chemical weathering of tephra hastens soil genesis and the resulting soils tend to be fertile and can act as large carbon sinks. This research focuses on soil evolution, with emphasis on the role of tephra in soil formation, as well as climate and human utilization of the environment in the district of Öræfi in south east Iceland. The study area has been impacted numerous times by explosive volcanic eruptions in neighbouring central volcanoes Such as the Grímsvötn-Bárðarbunga systems and Öræfajökull. Of special importance to this area are the 1362 eruption in Öræfajökull and 1477 eruption in Vatnaöldur 1477 which originated in the Bárðarbunga system. The resulting tephra layers make it possible to ascertain the age of the soil and therefore calculate the soil accumulation rate. Five soil profiles were excavated and sampled at various distances from Öræfajökull glacier. In total 58 horizons were examined. The profiles and horizons were described using physical and chemical methods. Carbon and nitrogen content, bulk density, soil pH (H2O, KCl and NaF), clay content and weathering state were measured to describe soil properties and soil stability. Results show that the devastating eruption in Öræfajökull in 1362 and to a lesser extent the Vatna

  10. Continental crust beneath southeast Iceland.

    PubMed

    Torsvik, Trond H; Amundsen, Hans E F; Trønnes, Reidar G; Doubrovine, Pavel V; Gaina, Carmen; Kusznir, Nick J; Steinberger, Bernhard; Corfu, Fernando; Ashwal, Lewis D; Griffin, William L; Werner, Stephanie C; Jamtveit, Bjørn

    2015-04-14

    The magmatic activity (0-16 Ma) in Iceland is linked to a deep mantle plume that has been active for the past 62 My. Icelandic and northeast Atlantic basalts contain variable proportions of two enriched components, interpreted as recycled oceanic crust supplied by the plume, and subcontinental lithospheric mantle derived from the nearby continental margins. A restricted area in southeast Iceland--and especially the Öræfajökull volcano--is characterized by a unique enriched-mantle component (EM2-like) with elevated (87)Sr/(86)Sr and (207)Pb/(204)Pb. Here, we demonstrate through modeling of Sr-Nd-Pb abundances and isotope ratios that the primitive Öræfajökull melts could have assimilated 2-6% of underlying continental crust before differentiating to more evolved melts. From inversion of gravity anomaly data (crustal thickness), analysis of regional magnetic data, and plate reconstructions, we propose that continental crust beneath southeast Iceland is part of ∼350-km-long and 70-km-wide extension of the Jan Mayen Microcontinent (JMM). The extended JMM was marginal to East Greenland but detached in the Early Eocene (between 52 and 47 Mya); by the Oligocene (27 Mya), all parts of the JMM permanently became part of the Eurasian plate following a westward ridge jump in the direction of the Iceland plume. PMID:25825769

  11. Continental crust beneath southeast Iceland.

    PubMed

    Torsvik, Trond H; Amundsen, Hans E F; Trønnes, Reidar G; Doubrovine, Pavel V; Gaina, Carmen; Kusznir, Nick J; Steinberger, Bernhard; Corfu, Fernando; Ashwal, Lewis D; Griffin, William L; Werner, Stephanie C; Jamtveit, Bjørn

    2015-04-14

    The magmatic activity (0-16 Ma) in Iceland is linked to a deep mantle plume that has been active for the past 62 My. Icelandic and northeast Atlantic basalts contain variable proportions of two enriched components, interpreted as recycled oceanic crust supplied by the plume, and subcontinental lithospheric mantle derived from the nearby continental margins. A restricted area in southeast Iceland--and especially the Öræfajökull volcano--is characterized by a unique enriched-mantle component (EM2-like) with elevated (87)Sr/(86)Sr and (207)Pb/(204)Pb. Here, we demonstrate through modeling of Sr-Nd-Pb abundances and isotope ratios that the primitive Öræfajökull melts could have assimilated 2-6% of underlying continental crust before differentiating to more evolved melts. From inversion of gravity anomaly data (crustal thickness), analysis of regional magnetic data, and plate reconstructions, we propose that continental crust beneath southeast Iceland is part of ∼350-km-long and 70-km-wide extension of the Jan Mayen Microcontinent (JMM). The extended JMM was marginal to East Greenland but detached in the Early Eocene (between 52 and 47 Mya); by the Oligocene (27 Mya), all parts of the JMM permanently became part of the Eurasian plate following a westward ridge jump in the direction of the Iceland plume.

  12. Identification and characterization of individual airborne volcanic ash particles by Raman microspectroscopy.

    PubMed

    Ivleva, Natalia P; Huckele, Susanne; Weinzierl, Bernadett; Niessner, Reinhard; Haisch, Christoph; Baumann, Thomas

    2013-11-01

    We present for the first time the Raman microspectroscopic identification and characterization of individual airborne volcanic ash (VA) particles. The particles were collected in April/May 2010 during research aircraft flights, which were performed by Deutsches Zentrum für Luft- und Raumfahrt in the airspace near the Eyjafjallajökull volcano eruption and over Europe (between Iceland and Southern Germany). In addition, aerosol particles were sampled by an Electrical Low Pressure Impactor in Munich, Germany. As references for the Raman analysis, we used the spectra of VA collected at the ground near the place of eruption, of mineral basaltic rock, and of different minerals from a database. We found significant differences in the spectra of VA and other aerosol particles (e.g., soot, nitrates, sulfates, and clay minerals), which allowed us to identify VA among other atmospheric particulate matter. Furthermore, while the airborne VA shows a characteristic Raman pattern (with broad band from ca. 200 to ca. 700 cm(-1) typical for SiO₂ glasses and additional bands of ferric minerals), the differences between the spectra of aged and fresh particles were observed, suggesting differences in their chemical composition and/or structure. We also analyzed similarities between Eyjafjallajökull VA particles collected at different sampling sites and compared the particles with a large variety of glassy and crystalline minerals. This was done by applying cluster analysis, in order to get information on the composition and structure of volcanic ash. PMID:24121468

  13. Evaluation of remote-sensing techniques to measure decadal-scale changes of Hofsjokull ice cap, Iceland

    USGS Publications Warehouse

    Hall, D.K.; Williams, R.S.; Barton, J.S.; Sigurdsson, O.; Smith, L.C.; Garvin, J.B.

    2000-01-01

    Dynamic surficial changes and changes in the position of the firn line and the areal extent of Hofsjökull ice cap, Iceland, were studied through analysis of a time series (1973–98) of synthetic-aperture radar (SAR) and Landsat data. A digital elevation model of Hofsjökull, which was constructed using SAR interferometry, was used to plot the SAR backscatter coefficient (σ°) vs elevation and air temperature along transects across the ice cap. Seasonal and daily σ° patterns are caused by freezing or thawing of the ice-cap surface, and abrupt changes in σ° are noted when the air temperature ranges from ∼−5° to 0°C. Late-summer 1997 σ° (SAR) and reflectance (Landsat) boundaries agree and appear to be coincident with the firn line and a SAR σ° boundary that can be seen in the January 1998 SAR image. In January 1994 through 1998, the elevation of this σ° boundary on the ice capwas quite stable, ranging from 1000 to 1300 m, while the equilibrium-line altitude, as measured on the ground, varied considerably. Thus the equilibrium line may be obscured by firn from previous years. Techniques are established to measure long-term changes in the elevation of the firn line and changes in the position of the ice margin.

  14. Estimation of volcanic ash emissions from satellite data using trajectory-based 4D-Var

    NASA Astrophysics Data System (ADS)

    Lu, Sha; Lin, Haixiang; Heemink, Arnold; Segers, Arjo; Fu, Guangliang

    2016-04-01

    An accurate determination of emission parameters are crucial to the volcanic ash forecast for aviation, health and climate interests. In this study, we reconstruct the vertical profile of the volcanic ash emission from satellite ash mass loading data using trajectory-based 4D-Var (Trj4DVar) approach with Eyjafjallajökull 2010 eruptive event and the corresponding SEVIRI data as a study case. Since the Eyjafjallajökull eruption in April 2010, besides ash mass loadings retrieved from satellite data, the additional information of plume height and mass eruption rate is always available from volcanic ash detections and observations. Modifications is made in Trj4DVar to integrate the additional information into the data assimilation system to improve the estimation of volcanic ash emissions and achieve a better initial condition for quantitative predictions. The modified Trj4DVar has been tested in twin experiments designed based on the study case, and shows significant improvement on straightforward Trj4DVar since it has great correction impact to recognize the injection height and produce more accurate emission estimation and reliable initial field of volcanic ash loading. To apply the approach to the real case with SEVIRI data, two strategies was proposed: observational mask matrix and separate time windows. The results produced a better initial condition and predictive forecast that were more fitter the SEVIRI ash mass loading fields, which showed a great potential of applying the method in practice.

  15. A neural network approach for monitoring of volcanic SO2 and cloud height using hyperspectral measurements

    NASA Astrophysics Data System (ADS)

    Piscini, Alessandro; Carboni, Elisa; Del Frate, Fabio; Grainger, Roy Gordon

    2014-10-01

    In this study two neural networks were implemented in order to emulate a retrieval model and to estimate the sulphur dioxide (SO2) columnar content and cloud height from volcanic eruption. ANNs were trained using all Infrared Atmospheric Sounding Interferometer (IASI) channels in Thermal Infrared (TIR) as inputs, and the corresponding values of SO2 content and height of volcanic cloud obtained using the Oxford SO2 retrievals as target outputs. The retrieval is demonstrated for the eruption of the Eyjafjallajökull volcano (Iceland) occurred in 2010 and to three IASI images of the Grímsvötn volcanic eruption that occurred in May 2011, in order to evaluate the networks for an unknown eruption. The results of validation, both for Eyjafjallajökull independent data-sets, provided root mean square error (RMSE) values between neural network outputs and targets lower than 20 DU for SO2 total column and 200 mb for cloud height, therefore demonstrating the feasibility to estimate SO2 values using a neural network approach, and its importance in near real time monitoring activities, owing to its fast application. Concerning the validation carried out with neural networks on images from the Grímsvötn eruption, the RMSE of the outputs remained lower than the Standard Deviation (STD) of targets, and the neural network underestimated retrieval only where target outputs showed different statistics than those used during the training phase.

  16. Insulation effects of Icelandic dust and volcanic aerosols on snow and ice

    NASA Astrophysics Data System (ADS)

    Dragosics, Monika; Meinander, Outi; Jónsdóttir, Tinna; Dürig, Tobias; De Leeuw, Gerrit; Pálsson, Finnur; Dagsson-Waldhauserová, Pavla; Thorsteinsson, Throstur

    2016-04-01

    In the Arctic region, Iceland is an important source of dust due to ash production from volcanic eruptions. In addition dust is resuspended from the surface into the atmosphere as several dust storms occur each year. During volcanic eruptions and dust storms, material is deposited on the glaciers where it influences their energy balance. The effects of deposited volcanic ash on ice and snow melt were examined using laboratory and outdoor experiments. These experiments were made during the snow melt period using two different ash grain sizes (1 ϕ and 3.5 ϕ) from the Eyjafjallajökull 2010 eruption, collected on the glacier. Different amounts of ash were deposited on snow or ice after which the snow properties and melt were measured. The results show that a thin ash layer increases the snow and ice melt but an ash layer exceeding a certain critical thickness caused insulation. Ash with 1 ϕ in grain size insulated the ice below at a thickness of 9-15 mm. For the 3.5 ϕ grain size the insulation thickness is 13 mm. The maximum melt occurred at a thickness of 1 mm for the 1 ϕ and only 1-2 mm for 3.5 ϕ ash. A map of dust concentrations on Vatnajökull that represents the dust deposition during the summer of 2013 is presented with concentrations ranging from 0.2 up to 16.6 g m-2.

  17. Fieldwork report on conditions in the 2014 Holuhraun volcanic eruption Iceland

    NASA Astrophysics Data System (ADS)

    Bergsson, Baldur; Ófeigsson, Benedikt; Ingvarsson, Þorgils; Kjartansson, Vilhjálmur; Arngrímsson, Hermann; Yeo, Richard; Bergsson, Bergur; Erlendsson, Pálmi; Stefánsdóttir, Gerður; Sigurðardóttir, Guðmunda; Jónsdóttir, Kristín; Sigurðsson, Gunnar; Ólafsson, Haraldur; Gíslason, Ólafur; Hróðmarsson, Hilmar; Snorrason, Árni

    2015-04-01

    Since the start of the unrest at Bárðarbunga and the 2014 fissure eruption in Holuhraun Iceland, countless hours have been spent doing fieldwork. This presentation will focus on reporting the conditions that have been experienced by staff of the Icelandic Meteorological Office since the beginning of the unrest. The eruption is located north of Vatnajökull glacier on a floodplain. The area is very remote at an elevation of 700 meters, the nearest farm is about 100 km away. The Holuhraun site would be at risk of flooding should the eruption extend to the Vatnajökull ice-cap. The presentation will mainly focus on working conditions experienced during field installations and data gathering at different time stages of the eruption (August - present). Typical problems are mostly weather and gas related but a range of other challenges have been met. The presentation will focus on the following aspects; traveling to the field, glacier installations, working in a desert environment, the hazard of the gas plume, the effect that low temperatures has on equipment and working with helicopters. The aim of this report will be to get an open discussion about fieldwork related problems that may benefit us in the future, be it for the benefit of the presenter or the audience.

  18. Continental crust beneath southeast Iceland

    PubMed Central

    Torsvik, Trond H.; Amundsen, Hans E. F.; Trønnes, Reidar G.; Doubrovine, Pavel V.; Gaina, Carmen; Kusznir, Nick J.; Steinberger, Bernhard; Corfu, Fernando; Ashwal, Lewis D.; Griffin, William L.; Werner, Stephanie C.; Jamtveit, Bjørn

    2015-01-01

    The magmatic activity (0–16 Ma) in Iceland is linked to a deep mantle plume that has been active for the past 62 My. Icelandic and northeast Atlantic basalts contain variable proportions of two enriched components, interpreted as recycled oceanic crust supplied by the plume, and subcontinental lithospheric mantle derived from the nearby continental margins. A restricted area in southeast Iceland—and especially the Öræfajökull volcano—is characterized by a unique enriched-mantle component (EM2-like) with elevated 87Sr/86Sr and 207Pb/204Pb. Here, we demonstrate through modeling of Sr–Nd–Pb abundances and isotope ratios that the primitive Öræfajökull melts could have assimilated 2–6% of underlying continental crust before differentiating to more evolved melts. From inversion of gravity anomaly data (crustal thickness), analysis of regional magnetic data, and plate reconstructions, we propose that continental crust beneath southeast Iceland is part of ∼350-km-long and 70-km-wide extension of the Jan Mayen Microcontinent (JMM). The extended JMM was marginal to East Greenland but detached in the Early Eocene (between 52 and 47 Mya); by the Oligocene (27 Mya), all parts of the JMM permanently became part of the Eurasian plate following a westward ridge jump in the direction of the Iceland plume. PMID:25825769

  19. Meteorological Forcing of the Kills in New York / New Jersey Harbor

    NASA Astrophysics Data System (ADS)

    Rankin, K. L.; Chant, R. J.; Bruno, M. S.; Glenn, S.

    2002-12-01

    Hydrographic surveys of the New York / New Jersey Harbor complex were conducted in Newark Bay, the Arthur Kill, and Kill Van Kull as part of the "Contaminant Assessment and Reduction Program" to characterize salient physical processes in this estuarine system. Data collected for the study included shipboard and moored observations of currents, salinity, temperature and turbidity, with the aim of setting a dynamical context in which to interpret chemical data by providing insights into the mechanisms driving the transport pathways of dissolved and suspended contaminated material within the estuary. Analysis of collected data and former studies of the region indicate that the Kills system responds to a complex combination of forcing influences, including tide, wind, basin geometry and freshwater inflow. These influences are responsible for dramatic variations in hydrodynamic and sediment transport characteristics, including, for example, the direction and magnitude of the net, residual flow within the Newark Bay/Kills system. Here we sought to describe the relationship between the sub-tidal currents and the sea surface slope with meteorological forcing (wind/storm events) in the estuary. Measurements being made during the study included three (3) fixed bottom platform stations each equipped with a 1500kHz acoustic Doppler current profiler (ADP) to measure the vertical profile of horizontal currents. We also measured sea surface elevation data with three acoustic radiometric gauges that were deployed at the head of Newark Bay, at the mouth of the Arthur Kill, and at Constable Hook, in the Hudson River. Additional tide data at the Bayonne Bridge were provided by NOAA. Wind data from the Newark International Airport meteorological station (40o 40 57 N, 74o 10 10 W) were supplied by the Northeast Regional Climate Center. Sub-Tidal Motion: Current velocity data from the ADP was averaged over 30-minute intervals and low-pass filtered to remove the tidal component of the

  20. Fracture systems of the Western Volcanic Zone, Iceland

    NASA Astrophysics Data System (ADS)

    Rut Hjartardóttir, Ásta; Einarsson, Páll; Björgvinsdóttir, Sigríður

    2015-04-01

    The Western Volcanic Zone in Iceland is an approximately 120 km long and 30-40 km wide branch of the Mid-Atlantic plate boundary, extending towards the north from its triple junction with the Reykjanes Oblique Rift and the South Iceland Seismic Zone. The Western Volcanic Zone is an ultra-slow spreading part of the plate boundary, since the spreading in southern central Iceland is split between the Western and the Eastern Volcanic Zones. These volcanic zones, as well as the South Iceland Seismic Zone and the Hofsjökull volcanic system, form the boundary of the Hreppar microplate. In this study, fractures, including tensional fractures and faults, as well as eruptive fissures, were mapped in detail from aerial photographs. Orientation of the fractures was also calculated. This was done to study the extent of the volcanic zone, as well as its characteristics. The Western Volcanic Zone can be divided into several different fracture zones; The Hengill, Prestahnúkur, Kjölur, Hrómundartindur and Krákur fissure swarms, as well as an east-west oriented fracture system of unknown origin west of the Western Volcanic Zone. The Hengill fissure swarm is located in the southern part of the Western Volcanic Zone. It extends at least 30 km north of the Hengill central volcano. The Þingvellir graben is a part of the Hengill fissure swarm. The Prestahnúkur fissure swarm extends about 20 km towards the north and likely about 35 km towards the south from the Prestahnúkur central volcano. This fissure swarm is characterized by large-offset normal faults in Pleistocene formations. The Kjölur fissure swarm is located between the Western Volcanic Zone, and the Hofsjökull central volcano. We suggest that this fissure swarm, which is about 25 km long, likely belongs to the Hofsjökull volcanic system since its northern part bends towards the Hofsjökull central volcano. The Hrómundartindur fissure swarm extends towards the north from Hrómundartindur, which is located next to

  1. A model sensitivity study of the impact of clouds on satellite detection and retrieval of volcanic ash

    NASA Astrophysics Data System (ADS)

    Kylling, A.; Kristiansen, N.; Stohl, A.; Buras-Schnell, R.; Emde, C.; Gasteiger, J.

    2015-05-01

    Volcanic ash is commonly observed by infrared detectors on board Earth-orbiting satellites. In the presence of ice and/or liquid-water clouds, the detected volcanic ash signature may be altered. In this paper the sensitivity of detection and retrieval of volcanic ash to the presence of ice and liquid-water clouds was quantified by simulating synthetic equivalents to satellite infrared images with a 3-D radiative transfer model. The sensitivity study was made for the two recent eruptions of Eyjafjallajökull (2010) and Grímsvötn (2011) using realistic water and ice clouds and volcanic ash clouds. The water and ice clouds were taken from European Centre for Medium-Range Weather Forecast (ECMWF) analysis data and the volcanic ash cloud fields from simulations by the Lagrangian particle dispersion model FLEXPART. The radiative transfer simulations were made both with and without ice and liquid-water clouds for the geometry and channels of the Spinning Enhanced Visible and Infrared Imager (SEVIRI). The synthetic SEVIRI images were used as input to standard reverse absorption ash detection and retrieval methods. Ice and liquid-water clouds were on average found to reduce the number of detected ash-affected pixels by 6-12%. However, the effect was highly variable and for individual scenes up to 40% of pixels with mass loading >0.2 g m-2 could not be detected due to the presence of water and ice clouds. For coincident pixels, i.e. pixels where ash was both present in the FLEXPART (hereafter referred to as "Flexpart") simulation and detected by the algorithm, the presence of clouds overall increased the retrieved mean mass loading for the Eyjafjallajökull (2010) eruption by about 13%, while for the Grímsvötn (2011) eruption ash-mass loadings the effect was a 4% decrease of the retrieved ash-mass loading. However, larger differences were seen between scenes (standard deviations of ±30 and ±20% for Eyjafjallajökull and Grímsvötn, respectively) and even larger ones

  2. Neural-Network approach to hyperspectral data analysis for volcanic monitoring of sulphur dioxide

    NASA Astrophysics Data System (ADS)

    Piscini, Alessandro; Carboni, Elisa; Grainger, Roy Gordon; Del Frate, Fabio

    2014-05-01

    This study is about an Artificial Neural Network (ANN) algorithm that recognizes volcanic SO2 in the atmosphere using hyperspectral remotely sensed data from the Infrared Atmospheric Sounding Interferometer Instrument (IASI) instrument aboard the METOP-A satellite. The remote sensing of volcanic sulphur dioxide (SO2) is important because it is used as a proxy for volcanic ash which is dangerous to aviation and is generally more difficult to discriminate. The importance of this approach lies in its speed and its application to near real-time volcanic monitoring. In this paper an ANN algorithm is demonstrated on date of the eruption of the Eyjafjallajökull volcano (Iceland) during the months of April and May 2010, and on the Grímsvötn eruption occurring during May 2011. The algorithm consists of a two output neural network classifier trained with a time series consisting of some hyperspectral eruption images collected during Eyjafjallajökul 2010 and eruption and Grímsvötn 2011 eruption. The inputs were all channels (441) in the IASI ν3 band and the target outputs (truth) were the corresponding Oxford retrievals of SO2 amount. The classifier was validated on four independent IASI orbits, two that included observations of the Eyjafjallajökull eruption and two that included observations of the Grímsvötn volcanic eruption that occurred in May 2011. The validation results for the Eyjafjallajökull independent data-sets had an overall accuracy of 100%. The validation of the neural network classifier on images from the Grímsvötn eruption shown lower overall accuracies due to the presence of omission errors. Statistical analysis revealed that those false negatives lie near the detection threshold for discriminating pixels affected by SO2. This demonstrated that the accuracy in classification is strictly related to the sensitivity of the model. Nevertheless results obtained underlined that no commission errors were present at the validation stage (pixels

  3. Reconstructing Magma Degassing in the Katla 1918 Eruption through Vesicle Textures and Dissolved Volatile Contents

    NASA Astrophysics Data System (ADS)

    Owen, J.; Tuffen, H.; Coats, B.

    2014-12-01

    Iceland's Katla volcano frequently produces explosive eruptions (VEI 3-5) that generate large quantities of ash and powerful glacial floods (jökulhlaups). Its last eruption (VEI 4, basalt) was in 1918, but another may be imminent, given recent unrest and historic correlation with activity at Eyjafjallajökull, which erupted in 2010. Investigations of eruption products at nearby Torfajökull [1,2] have shown that volatiles are the primary control on the eruptive behaviour of subglacial rhyolite, rather than ice thickness. Explosive events are characterised by high pre-eruptive H2O contents (up to ~5 wt. %) and more closed system degassing, demonstrated by H2O-Cl ratios, microlite contents and vesiculation modelling. We have continued to develop the use of volatile degassing as an sensitive indicator of syn-eruptive pressure conditions [3,4]. We are now applying similar approaches to the basaltic Katla 1918 event, to determine the relative influence of volatiles and meltwater on eruption mechanisms. Sampling has included air-fall tephra from Mýrdalsjökull and jökulhlaup deposits from Múlakvísl. Infrared spectroscopy (FTIR) data reveals that airfall tephra have degassed to atmospheric conditions (0.07 wt % H2O), whereas jökulhlaup-carried juvenile clasts have elevated H2O contents (0.18 to 0.32 wt % H2O), consistent with quenching beneath a load of ice, water or tephra. Ongoing quantification of vesicle and crystal size distributions, together with experimental vesicle growth rates using hotstage microscopy, will help constrain rates and amounts of magma decompression, degassing and interactions with meltwater. We also aim to investigate chamber-to-surface degassing through analysis of volatile concentrations in melt inclusions. [1] Owen et al. 2013a Geology 41: 251-254 [2] Owen et al. 2013b J Volcanol Geoth Res 258: 143-162 [3] Tuffen et al. 2010 Earth Sci Rev 99: 1-18 [4] Owen et al. 2012 Bull Volcanol 74: 1355-1378

  4. The Hydration of Subglacial Rhyolite to Form Perlite

    NASA Astrophysics Data System (ADS)

    Denton, J. S.; Tuffen, H.; Gilbert, J. S.

    2009-12-01

    Subglacial rhyolite deposits at Torfajökull, Iceland encountered glacier meltwater as they cooled, leading to variable amounts of hydration. High-temperature lava-meltwater interactions are key to understanding jökulhlaup hazards, perlite formation, cooling rates and, ultimately, soil formation [Denton et al., 2009]. Perlite is a hydrated glass that contains abundant, intersecting, arcuate and gently curved cracks surrounding cores of intact glass. Knowledge of how perlite forms is required for us to better understand the way in which meltwater and lava interact during and after subglacial eruptions. The mechanism for perlite formation is currently poorly understood, it is not known whether cracking leads to hydration or vice versa. Different textural zones from effusively erupted lava lobes from Torfajökull, Iceland [Tuffen et al., 2001] have been studied using a combination of experimental and quantitative textural measurements to examine the processes of hydration and perlite formation. A differential scanning calorimetry - thermogravimetric analyser coupled to a mass spectrometer (DSC-TGA-MS) has been used to quantify the total volatile contents of a number of samples. A novel petrological technique has been used to quantify the concentration of fractures present in a sample which has then been related to the amount of hydration. Water content using infra-red microspectroscopy (FTIR) has been used to study the micro-scale variations of water content and how they relate to fractures in the rhyolitic glasses. The results indicate that progressive perlitisation at the margins of lava bodies is accompanied by an increase in the water content, from ~0.5 wt. % to ~2 wt. %. The speciation of the inwardly diffusing water changes from hydroxyl to molecular water with increasing total volatile content. The temperature of dehydration of samples during TGA experiments decreases with increasing volatile content, consistent with a change in the dominant H2O species from

  5. 50th Annual Scientific Meeting of the British Society for Haematology.

    PubMed

    Thomas, Angela E

    2010-08-01

    The 50th Annual Scientific Meeting of the British Society for Haematology was notable, not only for its golden anniversary, but also because it coincided with the eruption of the Icelandic volcano, Eyjafjallajökull, and the ensuing travel chaos. In total, 28 speakers from overseas were unable to reach Edinburgh, including a significant number of British speakers who were stranded. However, owing to the superb efforts of the conference organisers and Edinburgh International Conference Centre staff, teleconferencing equipment was installed and all speakers were contacted and able to give their talks on time. The program, consisting of simultaneous sessions and plenary lectures, covered not only recent advances in clinical and laboratory hematology, but also reflected on the contribution of British hematology to the international arena over the past 50 years.

  6. Spain as an emergency air traffic hub during volcanic air fall events? Evidence of past volcanic ash air fall over Europe during the late Pleistocene

    NASA Astrophysics Data System (ADS)

    Hardiman, Mark; Lane, Christine; Blockley, Simon P. E.; Moreno, Ana; Valero-Garcés, Blas; Ortiz, José E.; Torres, Trino; Lowe, John J.; Menzies, Martin A.

    2010-05-01

    Past volcanic eruptions often leave visible ash layers in the geological record, for example in marine or lake sedimentary sequences. Recent developments, however, have shown that non-visible volcanic ash layers are also commonly preserved in sedimentary deposits. These augment the record of past volcanic events by demonstrating that past ash dispersals have been more numerous and widely disseminated in Europe than previously appreciated. The dispersal ‘footprints' of some large late Pleistocene European eruptions are examined here in the light of the recent Eyjafjallajökull eruption. For example, the Vedde Ash which was erupted from Iceland around 12 thousand years ago, delivered distal (and non-visible) glass deposits as far south as Switzerland and as far east as the Ural Mountains in Russia, with an overall European distribution remarkably similar to the dominant tracks of the recent Eyjafjallajökull plumes. The Eyjafjallajökull eruption has demonstrated that relatively small amounts of distal volcanic ash in the atmosphere can seriously disrupt aviation activity, with attendant economic and other consequences. It has raised fundamental questions about the likelihood of larger or more prolonged volcanic activity in the near future, and the possibility of even more serious consequences than those experienced recently. Given that there are several other volcanic centres that could cause such disruption in Europe (e.g. Campania and other volcanic centres in Italy; Aegean volcanoes), a key question is whether there are parts of Europe less prone to ash plumes and which could therefore operate as emergency air traffic hubs during times of ash dispersal. Although not generated to answer this question, the recent geological record might provide a basis for seeking the answer. For example, four palaeo-records covering the time frame of 8 - 40 Ka BP that are geographically distributed across Spain have been examined for non-visible distal ash content. All four have

  7. LATIS3D: The Gold Standard for Laser-Tissue-Interaction Modeling

    SciTech Connect

    London, R.A.; Makarewicz, A.M.; Kim, B.M.; Gentile, N.A.; Yang, Y.B.; Brlik, M.; Vincent, L.

    2000-02-29

    The goal of this LDRD project has been to create LATIS3D--the world's premier computer program for laser-tissue interaction modeling. The development was based on recent experience with the 2D LATIS code and the ASCI code, KULL. With LATIS3D, important applications in laser medical therapy were researched including dynamical calculations of tissue emulsification and ablation, photothermal therapy, and photon transport for photodynamic therapy. This project also enhanced LLNL's core competency in laser-matter interactions and high-energy-density physics by pushing simulation codes into new parameter regimes and by attracting external expertise. This will benefit both existing LLNL programs such as ICF and SBSS and emerging programs in medical technology and other laser applications.

  8. Chemistry and fluxes of magmatic gases powering the explosive trachyandesitic phase of Eyjafjallajokull 2010 eruption: constraints on degassing magma volumes and processes

    NASA Astrophysics Data System (ADS)

    Allard, P.; Burton, M. R.; Oskarsson, N.; Michel, A.; Polacci, M.

    2010-12-01

    The 2010 Eyjafjallajökull eruption developed in two distinct phases, with initial lateral effusion of alkali basalt since March 20, followed by highly explosive extrusion of a quite homogenous and crystal-poor trachyandesitic magma [1] through the central volcano ice cap between April 14 and May 24. As usual, magmatic volatiles played a key role in the eruption dynamics. Here we report on the chemical composition and the mass output of magmatic gases powering intense explosive activity during the second eruptive phase in early May. On May 8 we could measure the composition of magmatic gases directly issuing from the eruptive vents, by using OP-FTIR spectroscopy from the crater rim (~900 m distance) and molten lava blocks as IR radiation source. FTIR spectra reveal a variable mixture between two gas components equally rich in H2O (91.3 mol%) and CO2 (8%) but differing in their SO2/HCl ratio (up to 3.5 for the main one and 0.5 for the Cl-richer second one). Analysis of S-Cl-F in ash leachates and in ash and lava bomb samples (pyrohydrolysis) show that this second component was generated by greater chlorine loss during extensive magma fragmentation into fine ash. S/Cl and Cl/F ratios from both these analyses and solar occultation FTIR plume sensing indicate a modest fluorine content in emitted gas and its preferential adsorption onto solid particles during plume transport. DOAS traverses under the volcanic plume (4-6 km height), though hampered by dense ash load, gave most reliable SO2 fluxes of 4500-6600 tons d-1 on May 9, consistent with OMI satellite data [2]. These imply the daily co-emission of 7.2x105 tons of H2O, 1.5x105 tons of CO2, 2000 tons of HCl and ≤200 tons of HF. Eyjafjallajökull thus produced more hydrous and relatively CO2-poorer gas, in much greater quantities, during that stage than during its first basaltic phase [3]. Linear variations of dissolved S with TiO2/FeO ratio in nearby Katla alkali magmas [4] suggest possible pre-eruptive S contents

  9. Anthropogenic radionuclides in atmospheric air over Switzerland during the last few decades.

    PubMed

    Alvarado, J A Corcho; Steinmann, P; Estier, S; Bochud, F; Haldimann, M; Froidevaux, P

    2014-01-01

    The atmospheric nuclear testing in the 1950s and early 1960s and the burn-up of the SNAP-9A satellite led to large injections of radionuclides into the stratosphere. It is generally accepted that current levels of plutonium and caesium radionuclides in the stratosphere are negligible. Here we show that those radionuclides are present in the stratosphere at higher levels than in the troposphere. The lower content in the troposphere reveals that dry and wet deposition efficiently removes radionuclides within a period of a few weeks to months. Since the stratosphere is thermally stratified and separated from the troposphere by the tropopause, radioactive aerosols remain longer. We estimate a mean residence time for plutonium and caesium radionuclides in the stratosphere of 2.5-5 years. Our results also reveal that strong volcanic eruptions like Eyjafjallajökull in 2010 have an important role in redistributing anthropogenic radionuclides from the stratosphere to the troposphere. PMID:24398434

  10. Magma types and mantle sources of the Bárðarbunga volcanic system, Iceland

    NASA Astrophysics Data System (ADS)

    Halldórsson, Sæmundur; Rubin, Ken; Sverrisdóttir, Guðrún; Sigurðsson, Gylfi

    2015-04-01

    The Bárðarbunga volcanic system (BVS) represents one of the largest volcanic systems in Iceland, extending ~190 km from the northern boundary of Torfajökull in the south to Dyngjufjöll Ytri in the north, and intersecting the largely ice-covered Bárðarbunga volcano. The extensive length of the BVS thus allows sampling of an unusually large section of the mantle underlying Iceland's Eastern rift zone. Perhaps surprisingly, the degree of mantle source heterogeneity beneath the BVS remains poorly known. We have recently undertaken a detailed study of the BVS because such data are fundamental for understanding the magmatic history and magma delivery system beneath of the BVS, including those that led to recent volcanism north of Dyngjujökull. Here, we present major and trace element analyses, as well as high-precision Pb isotope analyses, of several Holocene lava flows from the Dyngjuháls area and from rocks representing the basement, flanks and nunataks of the ice-free part of the Bárðarbunga volcano. We compare these data to those on a suite of recently collected fissure basalts from the Veiðivötn fissure swarm in the south and the new lava north of Dyngjujökull in order to study the geochemical characteristics of the BVS as a whole. The BVS has generated fairly primitive tholeiites (MgO ~6-9 wt.%) throughout the Holocene. Evolved basaltic compositions (MgO ≤6 wt.%) that are often associated with large and mature caldera systems in Iceland (e.g., Krafla and Askja), appear to be notably absent in the BVS within our current sample set (although might still exist in the largely ice-covered Bárðarbunga volcano). Significantly, no highly evolved rocks (dacite, rhyolite) have been associated with the BVS. It is therefore unlikely that a long-lived and relatively shallow (<5 km) magma chamber has existed beneath Bárðarbunga throughout the Holocene, and possibly longer. In Pb-Pb isotope plots, the three sections of the BVS form distinct trends. Notably

  11. Composition and evolution of volcanic aerosol following three eruptions in 2008 - 2010

    NASA Astrophysics Data System (ADS)

    Andersson, S. M.; Martinsson, B. G.; Friberg, J.; Brenninkmeijer, C. A. M.; Hermann, M.; Heue, K. P.; van Velthoven, P. F. J.; Zahn, A.

    2012-04-01

    Measurements of atmospheric aerosols by the CARIBIC (Civil Aircraft for Regular Investigation of the atmosphere Based on an Instrument Container) platform following the Kasatochi (Alaska), Sarychev (Russia) and Eyjafjallajökull (Iceland) eruptions in the period 2008-2010 are presented. The CARIBIC platform operates on a Lufthansa passenger aircraft usually on monthly inter-continental flights, measuring the atmospheric composition in the UT/LS at 8-12 km altitude (Brenninkmeijer et al., 2007). After the eruption of Kasatochi, analyses of the stratospheric aerosol composition showed enhanced concentrations of sulfur and carbon for several months. On the other hand the ash component, clearly seen in a sample seven days after the eruption, was not detected a month later (Martinsson et al., 2009). To further investigate the composition of the volcanic aerosol three flights trough the volcanic plume of the Eyjafjallajökull eruption were carried out on April 20, May 16 and May 19, 2010. Aerosol sampling was performed by an impaction technique with a cut-off diameter of 2 μm (Nguyen et al., 2006). Collected samples were analyzed by quantitative multi-elemental analysis by PIXE (Particle-Induced X-ray Emission), to obtain concentrations of elements with atomic number larger than 13, and PESA (Particle Elastic Scattering Analysis) for concentrations of hydrogen, carbon, nitrogen and oxygen (Nguyen and Martinsson, 2007). Three samples taken during the special flights to study the Eyjafjallajökull eruption contained unusually high concentrations of elements pointing to crustal origin. The composition of these samples was compared to ash from a fall out sample (Sigmundsson et al., 2010). The ratio of detected elements to iron in both sample types showed good agreement for most of the elements for all three aerosol samples. Volcanically influenced aerosol following the eruptions of Sarychev and Kasatochi were identified by high concentrations of sulfur and by using air mass

  12. A-Train Satellite Observations of Recent Explosive Eruptions in Iceland and Chile

    NASA Astrophysics Data System (ADS)

    Carn, S. A.; Yang, K.; Prata, A. J.

    2012-04-01

    The past few years have seen remarkable levels of explosive volcanic activity in Iceland and Chile, with four significant eruptions at Chaitén (May 2008), Eyjafjallajökull (April 2010), Grimsvötn (May 2011) and Cordón Caulle (June 2011 - ongoing). The tremendous disruption and economic impact of the Eyjafjallajökull eruption is well known, but each of these events had a significant impact on aviation, sometimes at great distances from the volcano. As of late 2011, volcanic ash from Cordón Caulle was still affecting airports in southern South America, highlighting the potential for extended disruption during long-lived eruptions. Serendipitously, this period of elevated volcanic activity has coincided with an era of unprecedented availability of satellite remote sensing data pertinent to volcanic cloud studies. In particular, NASA's A-Train satellite constellation (including the Aqua, CloudSat, CALIPSO, and Aura satellites) has been flying in formation since 2006, providing synergistic, multi- and hyper-spectral, passive and active observations. Measurements made by A-Train sensors include total column sulfur dioxide (SO2) by the Ozone Monitoring Instrument (OMI) on Aura, upper tropospheric and stratospheric (UTLS) SO2 column by the Atmospheric Infrared Sounder (AIRS) on Aqua and Microwave Limb Sounder (MLS) on Aura, ash mass loading from AIRS and the Moderate resolution Imaging Spectroradiometer (MODIS) on Aqua, UTLS HCl columns and ice water content (IWC) from MLS, aerosol vertical profiles from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument aboard CALIPSO, and hydrometeor profiles from the Cloud Profiling Radar (CPR) on CloudSat. The active vertical profiling capability of CALIPSO, CloudSat and MLS sychronized with synoptic passive sensing of trace gases and aerosols by OMI, AIRS and MODIS provides a unique perspective on the structure and composition of volcanic clouds. A-Train observations during the first hours of atmospheric

  13. Streaked radiography of an irradiated foam sample on the National Ignition Facility

    SciTech Connect

    Cooper, A. B. R.; Schneider, M. B.; MacLaren, S. A.; Young, P. E.; Hsing, W. W.; Seugling, R.; Foord, M. E.; Sain, J. D.; May, M. J.; Marrs, R. E.; Maddox, B. R.; Lu, K.; Dodson, K.; Smalyuk, V.; Moore, A. S.; Graham, P.; Foster, J. M.; Back, C. A.; Hund, J. F.

    2013-03-15

    Streaked x-ray radiography images of annular patterns in an evolving tantalum oxide foam under the influence of a driven, subsonic radiation wave were obtained on the National Ignition Facility. This is the first successful radiography measurement of the evolution of well-defined foam features under a driven, subsonic wave in the diffusive regime. A continuous record of the evolution was recorded on an x-ray streak camera, using a slot-apertured point-projection backlighter with an 8 ns nickel source (7.9 keV). Radiography images were obtained for four different annular patterns, which were corrected using a source-dependent flat-field image. The evolution of the foam features was well-modeled using the 3D KULL radiation hydrodynamics code. This experimental and modeling platform can be modified for scaled high-energy-density laboratory astrophysics experiments.

  14. From Operational Ceilometer Network to Operational Lidar Network

    NASA Astrophysics Data System (ADS)

    Adam, Mariana; Turp, Myles; Horseman, Andrew; Ordóñez, Carlos; Buxmann, Joelle; Sugier, Jacqueline

    2016-06-01

    During the eruption of Eyjafjallajökull in 2010, the Met Office ceilometers (Laser Cloud Based Recorders - LCBR) provided reasonable information about volcanic ash plumes over the United Kingdom [1]. This capability triggered the development of an operational system to provide quick looks of the range corrected signals (RCS) in near-real-time (NRT). Moreover, the Met Office acquired eleven Jenoptik ceilometers to supplement the operational ceilometer network. The combined network became operational in 2012 and currently comprises a total of 43 ceilometers reporting backscatter profiles in NRT. In 2013, Civil Aviation Authority (CAA) and the Department for transport (DfT) sponsored the acquisition of 9 fixed lidars and one mobile unit (each accompanied by a sunphotometer), to further improve the quantitative monitoring of volcanic ash. The current status of both ceilometer and lidar/sun-photometer networks is discussed and further developments are proposed.

  15. Remote Sensing of Volcanic ASH at the Met Office

    NASA Astrophysics Data System (ADS)

    Marenco, F.; Kent, J.; Adam, M.; Buxmann, J.; Francis, P.; Haywood, J.

    2016-06-01

    The eruption of Eyjafjallajökull in 2010 has triggered the rapid development of volcanic ash remote sensing activities at the Met Office. Volcanic ash qualitative and quantitative mapping have been achieved using lidar on board the Facility for Airborne Atmospheric Measurements (FAAM) research aircraft, and using improved satellite retrieval algorithms. After the eruption, a new aircraft facility, the Met Office Civil Contingencies Aircraft (MOCCA), has been set up to enable a rapid response, and a network of ground-based remote sensing sites with lidars and sunphotometers is currently being developed. Thanks to these efforts, the United Kingdom (UK) will be much better equipped to deal with such a crisis, should it happen in the future.

  16. The collapse of Bárðarbunga caldera, Iceland

    NASA Astrophysics Data System (ADS)

    Riel, B.; Milillo, P.; Simons, M.; Lundgren, P.; Kanamori, H.; Samsonov, S.

    2015-07-01

    Lying below Vatnajökull ice cap in Iceland, Bárðarbunga stratovolcano began experiencing wholesale caldera collapse in 2014 August 16, one of the largest such events recorded in the modern instrumental era. Simultaneous with this collapse is the initiation of a plate boundary rifting episode north of the caldera. Observations using the international constellation of radar satellites indicate rapid 50 cm d-1 subsidence of the glacier surface overlying the collapsing caldera and metre-scale crustal deformation in the active rift zone. Anomalous earthquakes around the rim of the caldera with highly nondouble-couple focal mechanisms provide a mechanical link to the dynamics of the collapsing magma chamber. A model of the collapse consistent with available geodetic and seismic observations suggests that the majority of the observed subsidence occurs aseismically via a deflating sill-like magma chamber.

  17. Electrical Properties Of Volcanic Ash Samples From Grímsvötn

    NASA Astrophysics Data System (ADS)

    Houghton, I. M.; Aplin, K. L.; Nicoll, K. A.; Green, O.; Mather, T. A.

    2012-12-01

    performed with pumice (a much more homogeneous material than ash) and compared to the results obtained with the volcanic ash samples. Arason P, Bennett A J and Burgin L E 2011 Charge mechanism of volcanic lightning revealed during the 2010 eruption of Eyjafjallajökull, J. Geophys. Res. 116 B00C03 Bennett A J, Odams P, Edwards D and Arason P 2010 Monitoring of lightning from the April-May 2010 Eyjafjallajökull volcanic eruption using a very low frequency lightning location network, Environ. Res. Lett. 5 044013 Harrison R G, Nicoll K A, Ulanowksi Z and Mather T A 2010 Self-charging of the Eyjafjallajökull volcanic ash plume Environ. Res. Lett. 5 024004 James M R, Wilson L, Lane S J , Gilbert J S, Mather T A, Harrison R G and Martin R S 2008 Electrical charging of volcanic plumes, Space Science Reviews 137 399-418 Lacks D J and Levandovsky A, 2007, Effect of particle size distribution on the polarity of triboelectric charging in granular insulator systems, J. Electrostatics, 65, 107-112 Mather T A and Harrison R G 2006 Electrification of volcanic plumes, Surveys in Geophysics 27 4 387-432 Piper I M, Aplin K L and Nicoll K A 2012 Electrical properties of volcanic ash samples from Eyjafjallajökull and Grímsvötn, Proceedings of Annual Aerosol Society Conference 2012, arXiv 1207.6733

  18. Risk, interest groups and the definition of crisis: the case of volcanic ash.

    PubMed

    Hutter, Bridget M; Lloyd-Bostock, Sally

    2013-09-01

    This paper considers a key aspect of the 'risk society' thesis: the belief that we should be able to manage risks and control the world around us. In particular it focuses on the interface between risk and risk events as socially constructed and the insights that 'critical situations' give us into 'the routine and mundane', the otherwise taken for granted assumptions underlying risk regulation. It does this with reference to the events precipitated by the April 2010 volcanic eruption in the Eyjafjallajökull area of Iceland. The resulting cloud of volcanic ash spread across Europe and much of Europe's airspace was closed to civil aviation for six days, with far reaching consequences including huge financial losses for airlines. The social processes of defining and reacting to risk and crisis both reveal and generate dilemmas and challenges in regulation. This paper examines the role of different interest groups in defining risk expectations and thereby redefining the ash crisis as a regulatory crisis.

  19. Artificial cloud test confirms volcanic ash detection using infrared spectral imaging.

    PubMed

    Prata, A J; Dezitter, F; Davies, I; Weber, K; Birnfeld, M; Moriano, D; Bernardo, C; Vogel, A; Prata, G S; Mather, T A; Thomas, H E; Cammas, J; Weber, M

    2016-01-01

    Airborne volcanic ash particles are a known hazard to aviation. Currently, there are no means available to detect ash in flight as the particles are too fine (radii < 30 μm) for on-board radar detection and, even in good visibility, ash clouds are difficult or impossible to detect by eye. The economic cost and societal impact of the April/May 2010 Icelandic eruption of Eyjafjallajökull generated renewed interest in finding ways to identify airborne volcanic ash in order to keep airspace open and avoid aircraft groundings. We have designed and built a bi-spectral, fast-sampling, uncooled infrared camera device (AVOID) to examine its ability to detect volcanic ash from commercial jet aircraft at distances of more than 50 km ahead. Here we report results of an experiment conducted over the Atlantic Ocean, off the coast of France, confirming the ability of the device to detect and quantify volcanic ash in an artificial ash cloud created by dispersal of volcanic ash from a second aircraft. A third aircraft was used to measure the ash in situ using optical particle counters. The cloud was composed of very fine ash (mean radii ~10 μm) collected from Iceland immediately after the Eyjafjallajökull eruption and had a vertical thickness of ~200 m, a width of ~2 km and length of between 2 and 12 km. Concentrations of ~200 μg m(-3) were identified by AVOID at distances from ~20 km to ~70 km. For the first time, airborne remote detection of volcanic ash has been successfully demonstrated from a long-range flight test aircraft. PMID:27156701

  20. Sensitivity of dispersion model forecasts of volcanic ash clouds to the physical characteristics of the particles

    NASA Astrophysics Data System (ADS)

    Beckett, F. M.; Witham, C. S.; Hort, M. C.; Stevenson, J. A.; Bonadonna, C.; Millington, S. C.

    2015-11-01

    This study examines the sensitivity of atmospheric dispersion model forecasts of volcanic ash clouds to the physical characteristics assigned to the particles. We show that the particle size distribution (PSD) used to initialise a dispersion model has a significant impact on the forecast of the mass loading of the ash particles in the atmosphere. This is because the modeled fall velocity of the particles is sensitive to the particle diameter. Forecasts of the long-range transport of the ash cloud consider particles with diameters between 0.1 μm and 100 μm. The fall velocity of particles with diameter 100 μm is over 5 orders of magnitude greater than a particle with diameter 0.1 μm, and 30 μm particles fall 88% slower and travel up to 5× further than a 100 μm particle. Identifying the PSD of the ash cloud at the source, which is required to initialise a model, is difficult. Further, aggregation processes are currently not explicitly modeled in operational dispersion models due to the high computational costs associated with aggregation schemes. We show that using a modified total grain size distribution (TGSD) that effectively accounts for aggregation processes improves the modeled PSD of the ash cloud and deposits from the eruption of Eyjafjallajökull in 2010. Knowledge of the TGSD of an eruption is therefore critical for reducing uncertainty in quantitative forecasts of ash cloud dispersion. The density and shape assigned to the model particles have a lesser but still significant impact on the calculated fall velocity. Accounting for the density distribution and sphericity of ash from the eruption of Eyjafjallajökull in 2010, modeled particles can travel up to 84% further than particles with default particle characteristics that assume the particles are spherical and have a fixed density.

  1. Satellite Monitoring of Ash and Sulphur Dioxide for the mitigation of Aviation Hazards: Part I. Validation of satellite-derived Volcanic Ash Levels.

    NASA Astrophysics Data System (ADS)

    Koukouli, MariLiza; Balis, Dimitris; Simopoulos, Spiros; Siomos, Nikos; Clarisse, Lieven; Carboni, Elisa; Wang, Ping; Siddans, Richard; Marenco, Franco; Mona, Lucia; Pappalardo, Gelsomina; Spinetti, Claudia; Theys, Nicolas; Tampellini, Lucia; Zehner, Claus

    2014-05-01

    The 2010 eruption of the Icelandic volcano Eyjafjallajökull attracted the attention of the public and the scientific community to the vulnerability of the European airspace to volcanic eruptions. Major disruptions in European air traffic were observed for several weeks surrounding the two eruptive episodes, which had a strong impact on the everyday life of many Europeans as well as a noticable economic loss of around 2-3 billion Euros in total. The eruptions made obvious that the decision-making bodies were not informed properly and timely about the commercial aircraft capabilities to ash-leaden air, and that the ash monitoring and prediction potential is rather limited. After the Eyjafjallajökull eruptions new guidelines for aviation, changing from zero tolerance to newly established ash threshold values, were introduced. Within this spirit, the European Space Agency project Satellite Monitoring of Ash and Sulphur Dioxide for the mitigation of Aviation Hazards, called for the creation of an optimal End-to-End System for Volcanic Ash Plume Monitoring and Prediction . This system is based on improved and dedicated satellite-derived ash plume and sulphur dioxide level assessments, as well as an extensive validation using auxiliary satellite, aircraft and ground-based measurements. The validation of volcanic ash levels extracted from the sensors GOME-2/MetopA, IASI/MetopA and MODIS/Terra and MODIS/Aqua is presented in this work with emphasis on the ash plume height and ash optical depth levels. Co-located aircraft flights, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation [CALIPSO] soundings and well as European Aerosol Research Lidar Network [EARLINET] measurements were compared to the different satellite estimates for the those two eruptive episodes. The validation results are extremely promising with most satellite sensors performing quite well and within the estimated uncertainties compared to the comparative datasets. The findings are

  2. Ash dispersal dynamics: state of the art and perspectives

    NASA Astrophysics Data System (ADS)

    Sulpizio, R.

    2013-05-01

    Volcanic ash, during dispersal and deposition, is among the major hazards from explosive eruptions. Volcanic ash fallout can disrupt communities downwind, interrupt surface transportation networks and lead to closure of airports. Airborne ash seriously threatens modern jet aircraft in flight. In several documented cases, encounters between aircraft and volcanic clouds have resulted in engine flameout and near crashes, so there is a need to accurately predict the trajectory of volcanic ash clouds in order to improve aviation safety and reduce economic losses. The ash clouds affect aviation even in distal regions, as demonstrated by several eruptions with far-range dispersal. Recent examples include Crater Peak 1992, Tungurahua 1999-2001, Mount Cleveland 2001, Chaitén 2008, Eyjafjallajökull 2010, Grimsvötn 2011, and Cordón-Caulle 2011. Amongst these, the April-May 2010 eruption of Eyjafjallajökull in Iceland provoked the largest civil aviation breakdown. Accumulation of tephra can produce roof collapse, interruption of lifelines (roads, railways, etc.), disruption to airport operations, and damage to communications and electrical power lines. Deposition of ash decreases soil permeability, increases surface runoff, and promotes floods. Ash leaching can result in the pollution of water resources, damage to agriculture, pastures, and livestock, impinge on aquatic ecosystems, and alteration of the geochemical environment on the seafloor. Despite the potential big impact, the dispersal dynamics of volcanic ash is still an unsolved problem for volcanologists, which claims for fiture high level research. Here, a critical overview about models (field, experimental and numerical) for inversion of field data to gain insights on physics of dispersal of volcanic ash is proposed. A special focus is devoted to some physical parameters that are far from a satisfactory inversion (e.g. reconstruction of total grain size distribution), and clues for future research are suggested.

  3. Preservation potential of subtle glacial landforms based on detailed mapping of recently exposed proglacial areas: application of unmanned aerial vehicle (UAV) and structure-from-motion (SfM)

    NASA Astrophysics Data System (ADS)

    Ewertowski, Marek; Evans, David; Roberts, David; Tomczyk, Aleksandra; Ewertowski, Wojciech

    2016-04-01

    Ongoing glacier retreat results in the continuous exposure of proglacial areas. Such areas contain invaluable information about glacial process-form relationships manifest in specific landform assemblages. However, preservation potential of freshly exposed glacial landforms is very low, as proglacial terrains are one of the most dynamic parts of the landscape. Therefore, rapid mapping and geomorphological characterisation of such areas is important from a glaciological and geomorphological point of view for proper understanding and reconstruction of glacier-landform dynamics and chronology of glacial events. Annual patterns of recession and relatively small areas exposed every year, mean that the performing of regular aerial or satellite survey is expensive and therefore impractical. Recent advances in technology enables the development of low-cost alternatives for traditional aerial surveys. Small unmanned aerial vehicles (UAV) can be used to acquire high-resolution (several cm) low-altitude photographs. The UAV-based photographs can be subsequently processed through the structure-from-motion process to generate detailed orthophotomaps and digital elevation models. In this study we present case studies from the forelands of various glaciers on Iceland and Svalbard representing different types of proglacial landscapes: Fláajökull (annual push moraines); Hofellsjökul (bedrock bedforms and push moraines); Fjallsjökull (marginal drainage network); Rieperbreen (crevasse squeeze ridges and longitudinal debris stripes); Ayerbreen (transverse debris ridges); Foxfonna (longitudinal debris stripes);Hørbyebreen (geometric ridge network); Nordenskiöldbreen (fluted till surface); Ebbabreen (controlled moraine complex). UAV campaigns were conducted using a low-cost quadcopter platform. Resultant orthophotos and DEMs enabled mapping and assessment of recent glacial landscape development in different types of glacial landsystems. Results of our study indicate that

  4. Which observations are necessary to estimate ash injection in the atmosphere by volcanic plumes? The case of the Eyjafjöll 2010 eruption

    NASA Astrophysics Data System (ADS)

    Kaminski, E.; Tait, S.; Ferrucci, F.

    2010-12-01

    On the 14th april of 2010, after about a month of effusive lateral eruption, the Eyjafjallajökull volcano, Iceland, changed to a more violent sub-glacial explosive eruption. The eruption produced a powerful volcanic plume that stunned air traffic above Europe for a few weeks. During this "sub-Plinian" activity, the key issue was the necessity for volcanologists to provide robust estimates of the ash content of the plume, a parameter required to correctly estimate the dispersion of ash in the atmosphere, and the related necessity to close (or not) the airports. 1D models of convective plumes show that the classical method relating the mass flux to the plume height, provides a satisfying estimate of the ash flux and ash concentration in the plume only for Plinian eruptions in which the magma is very finely fragmented. For "intermediate" silicic and basaltic eruptions, in which both a convective plume and an effusive lava flow or pyroclastic flows are produced, the "plinian" framework yields an over-estimation of the ash content of the plume. As a consequence, a correct estimation of ash concentration in a volcanic plume required a complementary knowledge of the partitioning of the mass flux between ground and atmospheric flow. A reference abacus is provided as a tool for a real time estimate of both the ash flux and ash concentration in the volcanic plume as a function of the ground and atmospheric fluxes. In the case of the Eyjafjallajökull eruption, the use of the "Plinian" model yielded an overestimation of the ash content in the plume of a factor 2, an acceptable error due to the interaction of water that enhanced magma fragmentation. In a dry basaltic eruption, the plinian model may overestimate the ash content by more than two orders of magnitude, and a knowledge of the ground flux is essential.

  5. Ash mists and brown snow: Remobilization of volcanic ash from recent Icelandic eruptions

    NASA Astrophysics Data System (ADS)

    Liu, E. J.; Cashman, K. V.; Beckett, F. M.; Witham, C. S.; Leadbetter, S. J.; Hort, M. C.; Gudmundsson, S.

    2014-08-01

    Recent eruptions in Iceland and Chile have demonstrated that volcanic ash problems persist long after an eruption. For this reason, ash dispersion models are being extended to include ash remobilization. Critical to these models is knowledge of the ash source and the particle sizes that can be mobilized under different wind and moisture conditions. Here we characterize the physical and chemical characteristics of ash deposited on new snow in Reykjavík, Iceland, following a blizzard on 6 March 2013. Morphological, textural, and compositional analyses indicate resuspension from multiple eruptive deposits, including both Grímsvötn (2011) and Eyjafjallajökull (2010) eruptions. Grain size measurements show a mode of 32-63 µm, with particles as large as 177 µm; there is little mass in the very fine fraction, ≤10 µm (PM10). We compare our observations to predictions using the Lagrangian particle dispersion model, NAME (UK Met Office). The model output is consistent with observations in that it forecasts resuspension from both Eyjafjallajökull and Grímsvötn source regions, and shows ash deposition coincident with the timing of observed deposition in Reykjavík. The modeled deposit in Reykjavík predicts, however, a substantially lower proportion of Grímsvötn ash than observed. This discrepancy has highlighted the need to reassess the assumptions used in the simulations, particularly regarding the source area and precipitation thresholds. Furthermore, we suggest that modification of ash deposits in the form of erosion, redeposition, compaction, or cementation may influence the dynamics of resuspension over time, thus influencing the ability of model simulations to accurately forecast remobilization events.

  6. Eruption rates in explosive eruptions: Ground truth and models

    NASA Astrophysics Data System (ADS)

    Tumi Gudmundsson, Magnus; Durig, Tobias; Höskuldsson, Ármann; Thordarson, Thorvaldur; Larsen, Gudrún; Óladóttir, Bergrún A.; Högnadóttir, Thórdís; Oddsson, Björn; Björnsson, Halldór; Gudmundsdóttir, Esther R.

    2015-04-01

    Estimations of eruption rates in explosive eruptions are difficult and error margins are invariably high. In small to moderate sized eruptions effects of wind on plume height can be large and in larger eruptions observations are often difficult due to masking of source by low cloud, pyroclastic density currents and monitoring system saturation. Several medium-sized explosive eruptions in recent years have been an important in sparking off intense research on e.g. atmosphere-plume interaction and associated effects of wind on plume height. Other methods that do not rely on plume height are e.g. infrared satellite monitoring of atmospheric loading of fine tephra, infrasound, analysis of video recordings from vents, and it has been suggested that co-eruptive tilt-meter deformation data can predict eruption intensity. The eruptions of Eyjafjallajökull in 2010 and Grímsvötn in 2011 provided a wealth of data that potentially can be of use in developing constraints of eruption rates in explosive eruptions. A key parameter in all such comparisons between models and data is as detailed knowledge as possible on tephra fallout. For both Eyjafjallajökull and Grímsvötn intensive field efforts took place to map out the deposits during and immediately after the eruptions. The resulting maps cover both individual phases as well as total fallout. Comparison of these data with plume-based and other models of mass discharge rates is presently work in progress. A desirable future aim is near real time estimates of mass eruption rates based several of the parameters mentioned above. This type of work is currently ongoing within the framework of the EU-funded supersite project FUTUREVOLC.

  7. Gravity current model of the volumetric growth of volcanic clouds: remote assessment with satellite imagery and estimation of mass eruption rate

    NASA Astrophysics Data System (ADS)

    Pouget, S.; Bursik, M. I.; Sparks, R. S.; Hogg, A. J.; Johnson, C. G.; Singh, T.; Pavolonis, M. J.

    2013-12-01

    The eruption of Eyjafjallajökull, Iceland in April and May, 2010, brought to light the hazards of airborne volcanic ash and the importance of being able to estimate the concentration of ash with time. This can be done using Volcanic Ash Transport and Dispersion models (VATD). These models require Eruption Source Parameters (ESP) such as the mass eruption rate (MER), as input. MER can be estimated from volumetric flux assuming gravity current behavior of the atmospheric intrusion. We used a gravity current model for the umbrella cloud and downwind plume in which the predominantly horizontal spreading through the atmosphere is driven by buoyancy forces and wind drag. Ash is advected by these atmospheric motions and settles out relatively slowly under the action of gravity. Given the importance of knowing ESP for VATD, we explored the use of the gravity current model applied to satellite imagery, using the geometric characteristics of ash clouds. To test the gravity current model on the use of satellite imagery, we estimated ESP from five well-studied and well-characterized historical eruptions: Mount St. Helens, 1980; Pinatubo, 1991, Redoubt, 1990; Hekla, 2000 and Eyjafjallajökull, 2010. These tests show that the methodologies yield results comparable to currently accepted methodologies of ESP estimation. We then applied the methodology to umbrella clouds produced by the eruptions of Okmok, 12 July 2008, and Sarychev Peak, 12 June 2009, and to the downwind plume produced by the eruptions of Hekla, 2000; Kliuchevsko'i, 1 October 1994; Kasatochi 7-8 August 2008 and Bezymianny, 1 September 2012; none of which had previous estimates of MER.

  8. Long-period seismic events with strikingly regular temporal patterns on Katla volcano's south flank (Iceland)

    NASA Astrophysics Data System (ADS)

    Sgattoni, Giulia; Jeddi, Zeinab; Gudmundsson, Ólafur; Einarsson, Páll; Tryggvason, Ari; Lund, Björn; Lucchi, Federico

    2016-09-01

    Katla is a threatening volcano in Iceland, partly covered by the Mýrdalsjökull ice cap. The volcano has a large caldera with several active geothermal areas. A peculiar cluster of long-period seismic events started on Katla's south flank in July 2011, during an unrest episode in the caldera that culminated in a glacier outburst. The seismic events were tightly clustered at shallow depth in the Gvendarfell area, 4 km south of the caldera, under a small glacier stream at the southern margin of Mýrdalsjökull. No seismic events were known to have occurred in this area before. The most striking feature of this seismic cluster is its temporal pattern, characterized by regular intervals between repeating seismic events, modulated by a seasonal variation. Remarkable is also the stability of both the time and waveform features over a long time period, around 3.5 years. We have not found any comparable examples in the literature. Both volcanic and glacial processes can produce similar waveforms and therefore have to be considered as potential seismic sources. Discerning between these two causes is critical for monitoring glacier-clad volcanoes and has been controversial at Katla. For this new seismic cluster on the south flank, we regard volcano-related processes as more likely than glacial ones for the following reasons: 1) the seismic activity started during an unrest episode involving sudden melting of the glacier and a jökulhlaup; 2) the glacier stream is small and stagnant; 3) the seismicity remains regular and stable for years; 4) there is no apparent correlation with short-term weather changes, such as rainstorms. We suggest that a small, shallow hydrothermal system was activated on Katla's south flank in 2011, either by a minor magmatic injection or by changes of permeability in a local crack system.

  9. Artificial cloud test confirms volcanic ash detection using infrared spectral imaging

    PubMed Central

    Prata, A. J.; Dezitter, F.; Davies, I.; Weber, K.; Birnfeld, M.; Moriano, D.; Bernardo, C.; Vogel, A.; Prata, G. S.; Mather, T. A.; Thomas, H. E.; Cammas, J.; Weber, M.

    2016-01-01

    Airborne volcanic ash particles are a known hazard to aviation. Currently, there are no means available to detect ash in flight as the particles are too fine (radii < 30 μm) for on-board radar detection and, even in good visibility, ash clouds are difficult or impossible to detect by eye. The economic cost and societal impact of the April/May 2010 Icelandic eruption of Eyjafjallajökull generated renewed interest in finding ways to identify airborne volcanic ash in order to keep airspace open and avoid aircraft groundings. We have designed and built a bi-spectral, fast-sampling, uncooled infrared camera device (AVOID) to examine its ability to detect volcanic ash from commercial jet aircraft at distances of more than 50 km ahead. Here we report results of an experiment conducted over the Atlantic Ocean, off the coast of France, confirming the ability of the device to detect and quantify volcanic ash in an artificial ash cloud created by dispersal of volcanic ash from a second aircraft. A third aircraft was used to measure the ash in situ using optical particle counters. The cloud was composed of very fine ash (mean radii ~10 μm) collected from Iceland immediately after the Eyjafjallajökull eruption and had a vertical thickness of ~200 m, a width of ~2 km and length of between 2 and 12 km. Concentrations of ~200 μg m−3 were identified by AVOID at distances from ~20 km to ~70 km. For the first time, airborne remote detection of volcanic ash has been successfully demonstrated from a long-range flight test aircraft. PMID:27156701

  10. Artificial cloud test confirms volcanic ash detection using infrared spectral imaging

    NASA Astrophysics Data System (ADS)

    Prata, A. J.; Dezitter, F.; Davies, I.; Weber, K.; Birnfeld, M.; Moriano, D.; Bernardo, C.; Vogel, A.; Prata, G. S.; Mather, T. A.; Thomas, H. E.; Cammas, J.; Weber, M.

    2016-05-01

    Airborne volcanic ash particles are a known hazard to aviation. Currently, there are no means available to detect ash in flight as the particles are too fine (radii < 30 μm) for on-board radar detection and, even in good visibility, ash clouds are difficult or impossible to detect by eye. The economic cost and societal impact of the April/May 2010 Icelandic eruption of Eyjafjallajökull generated renewed interest in finding ways to identify airborne volcanic ash in order to keep airspace open and avoid aircraft groundings. We have designed and built a bi-spectral, fast-sampling, uncooled infrared camera device (AVOID) to examine its ability to detect volcanic ash from commercial jet aircraft at distances of more than 50 km ahead. Here we report results of an experiment conducted over the Atlantic Ocean, off the coast of France, confirming the ability of the device to detect and quantify volcanic ash in an artificial ash cloud created by dispersal of volcanic ash from a second aircraft. A third aircraft was used to measure the ash in situ using optical particle counters. The cloud was composed of very fine ash (mean radii ~10 μm) collected from Iceland immediately after the Eyjafjallajökull eruption and had a vertical thickness of ~200 m, a width of ~2 km and length of between 2 and 12 km. Concentrations of ~200 μg m‑3 were identified by AVOID at distances from ~20 km to ~70 km. For the first time, airborne remote detection of volcanic ash has been successfully demonstrated from a long-range flight test aircraft.

  11. Artificial cloud test confirms volcanic ash detection using infrared spectral imaging.

    PubMed

    Prata, A J; Dezitter, F; Davies, I; Weber, K; Birnfeld, M; Moriano, D; Bernardo, C; Vogel, A; Prata, G S; Mather, T A; Thomas, H E; Cammas, J; Weber, M

    2016-05-09

    Airborne volcanic ash particles are a known hazard to aviation. Currently, there are no means available to detect ash in flight as the particles are too fine (radii < 30 μm) for on-board radar detection and, even in good visibility, ash clouds are difficult or impossible to detect by eye. The economic cost and societal impact of the April/May 2010 Icelandic eruption of Eyjafjallajökull generated renewed interest in finding ways to identify airborne volcanic ash in order to keep airspace open and avoid aircraft groundings. We have designed and built a bi-spectral, fast-sampling, uncooled infrared camera device (AVOID) to examine its ability to detect volcanic ash from commercial jet aircraft at distances of more than 50 km ahead. Here we report results of an experiment conducted over the Atlantic Ocean, off the coast of France, confirming the ability of the device to detect and quantify volcanic ash in an artificial ash cloud created by dispersal of volcanic ash from a second aircraft. A third aircraft was used to measure the ash in situ using optical particle counters. The cloud was composed of very fine ash (mean radii ~10 μm) collected from Iceland immediately after the Eyjafjallajökull eruption and had a vertical thickness of ~200 m, a width of ~2 km and length of between 2 and 12 km. Concentrations of ~200 μg m(-3) were identified by AVOID at distances from ~20 km to ~70 km. For the first time, airborne remote detection of volcanic ash has been successfully demonstrated from a long-range flight test aircraft.

  12. The chemistry and element fluxes of the July 2011 Múlakvísl and Kaldakvísl glacial floods, Iceland

    NASA Astrophysics Data System (ADS)

    Galeczka, Iwona; Oelkers, Eric H.; Gislason, Sigurdur R.

    2014-03-01

    This study describes the chemical composition and fluxes of two ~ 2000 m3/s glacial floods which emerged from the Icelandic Mýrdalsjökull and Vatnajökull glaciers into the Múlakvísl and Kaldakvísl rivers in July 2011. Water samples collected during both floods had neutral to alkaline pH and conductivity from 100 to 900 μS/cm. The total dissolved inorganic carbon (DIC), present mostly as HCO3-, was ~ 9 mmol/kg during the flood peak in the Múlakvísl but stabilized at around 1 mmol/kg; a similar behaviour was observed in the Kaldakvísl. Up to 1.5 μmol/kg of H2S was detected. Concentrations of most of the dissolved constituents in the flood waters were comparable to those commonly observed in these rivers. In contrast, the particulate suspended material concentration increased dramatically during the floods and dominated chemical transport during these events. Waters were supersaturated with respect to a number of clays, zeolites, carbonates, and Fe hydroxides. The most soluble elements were Na, Ca, K, Sr, Mn, and Mg, whereas the least soluble were Ti, Al, and REE. This is consistent with the compositions of typical surface waters in basaltic terrains and the compositions of global rivers in general. The toxic metal concentrations were below drinking water limits, suggesting that there was no detrimental effect of flood waters chemistry on the environment. Increased concentration of DOC, formate, and acetate in the flood waters suggests substantial subglacial microbiological activity in the melt water prior to the floods. Reaction path modelling of the flood water chemical evolution suggests that it experienced subglacial water-rock interaction for at least a year in the presence of limited amounts of acid gases (e.g. SO2, HCl and HF). This suggests that the heat source for glacier melting was geothermal rather than volcanic.

  13. Time needed for first lichen colonization of terminal moraines in the Tröllaskagi peninsula (North Iceland)

    NASA Astrophysics Data System (ADS)

    Andres, Nuria; Palacios, David; Brynjólfsson, Skafti; Sæmundsson, Þorsteinn

    2015-04-01

    The Tröllaskagi peninsula is located in Central North Iceland. The peninsula belong to the Tertiary basaltic areas in Iceland and is characterised by numerous glacially eroded valleys and fjords. The altitude ranges from sea level to 1500 m. Around 150 glaciers, debris covered glaciers and clean glaciers exist in the cirques of the Tröllaskagi peninsula. Lichenometric techniques were applied to date moraines formed by some of these glaciers, especially from 1970-90, establishing growth rates for some species, e.g. 0.5 mm/year for Rizocarpon geographicum. However there is no information available on how long the lichens take to colonize the boulders in a moraine once it has become detached from the retreating glacier. The aim of this paper is to observe how long it takes for the boulders on the moraines to be colonized by lichens in the Tröllaskagi peninsula, where the separation date of a moraine from the retreating glacier tongue is known. Two case studies were used. The first was the surging glacier Búrfellsjökull, in the Búrfelllsdalur valley, an affluent of the Svarfaðardalur valley. The Búrfellsjökull glacier surged in 2001-2004 and the glacial terminus advanced 150-240 m, overrunnig a moraine formed around 1955 and formed a new moraine. About 2-3 years after the surge termination in 2004 the glacial terminus was already retreating and had left the moraine isolated (Brynjólfsson et al. 2012). The other case is the Gljúlfurárjökull glacier, in the Gljúlfurárdalur valley, an affluent of the Skíðadalur valley. It can be seen from the series of aerial photographs that the glacier terminus advanced during the 1990s until the year 2000. In 2004 the glacial terminus was already retreating and had separated from a small moraine formed during the previous advance. Thus, two different glaciers halted and formed one moraine each which they separated from almost similar time. During the detailed field work carried out in August 2014 on both moraines

  14. Thermal Stability of Volcanic Ash versus Turbine Ingestion Test Sands: an Experimental Investigation

    NASA Astrophysics Data System (ADS)

    Cimarelli, C.; Kueppers, U.; Hess, K.; Dingwell, D. B.; Rickerby, D. S.; Madden, P. C.

    2010-12-01

    Volcanic eruptions are an inevitable natural threat. The range of eruptive styles is large and short term fluctuations of explosivity or vent position pose a large risk not necessarily confined to the immediate vicinity of a volcano. Explosive eruptions rather may also affect aviation, infrastructure and climate, regionally as well as globally. The recent eruption of Eyjafjallajökull drastically brought into common awareness how volcanic activity can affect every day’s life and disrupt air traffic. The presence of solid particles in the air ingested in jet turbines may cause harm as it 1) may deposit on surfaces upon being heated up and 2) abrade upon impact. Particles suspended in the atmosphere may have different origins, including volcanic ash, aeolian sand, or incineration residues, each of them having different chemical and physical characteristics. To date, aircraft turbine operability has been investigated - amongst other tests - through the ingestion of sands whose grains have different mineralogical nature. Due to high cooling rates, volcanic ash is usually made up of glass, i.e. an amorphous phase lacking crystallographic order. Glass and crystal behave very differently to heating up. Glass will soften - and accordingly change shape or stick to surfaces - at temperatures as low as 700 °C, depending on the chemical composition. Crystals however need higher melting temperatures; quartz for example has a melting point at around 1700 °C. Accordingly, the effect of ash on the operational reliability of aircraft turbines may not be judged solely based on knowledge commonly derived from mineral sand ingestion testing. In order to investigate the behaviour upon heating, we performed a series of experiments at ten temperature steps between 700 and 1600 °C. We used three different samples: 1) Ash from the explosive phase of Eyjafjallajökull; 2) MIL E-5007C test sand (MTS), and 3) Arizona Test Dust (ATD). MTS and ATD are commonly used for aircraft turbine

  15. Volcano-Ice Interactions and the Exploration for Extant Martian Life

    NASA Astrophysics Data System (ADS)

    Payne, M. C.; Farmer, J. D.

    2001-12-01

    Introduction: Recent discoveries revealed terrestrial colonies of microbes both in 349 K geothermal groundwater located at a depth of 2800 m, beneath glaciers in the Canadian Arctic and subglacial lakes in Antarctica at a depth >3 km. The existence of extremophiles in these subsurface environments has opened up important new directions in the exploration for Martian life. Consistent with NASA's programmatic initiative to``follow the water'' exploration for extant life has focused on the search for zones of subsurface water. Previous authors identified environments for liquid water in the region of the Martian North Polar Cap of Mars, including the melting at the base of ice sheets and magma-ice interactions. Such magma-ice interactions in Iceland have created landforms that may serve as possible analogs for Martian landforms observed in some Viking and MOC images. Volcano-Ice Interactions in Iceland as Analogs for Mars: Subglacial volcanism, associated jökulhlaup outflood events, and pseudocraters/rootless cones are examples of volcano-ice interactions observed in Iceland that could also exist on Mars. The Grímsvötn geothermal area located on the Vatnajökull Glacier boasts a network of active subglacial volcanoes and fissures. The extensive geothermal system that has developed beneath the ice cap is thought to be responsible for repeated jökulhlaup (glacial outflood) events in the Vatnajökull region. In addition, pseudocraters (or ``rootless cones'') are also present in periglacial areas where lava flows have been extruded over ground ice or shallow aquifers. In such regions, dense fields of small volcanic cones form by phreatic (steam) explosions. The potential for identifying similar geomorphic features on Mars using MOC-scale imaging is great. Furthermore, lava-ocean and lava-ice interactions in Iceland and elsewhere on Earth have frequently resulted in an altered (palagonitized) glass product forming on the exposed surfaces of pillow basalts. It has been

  16. The May 2011 eruption of Grímsvötn

    NASA Astrophysics Data System (ADS)

    Gudmundsson, M. T.; Höskuldsson, Á.; Larsen, G.; Thordarson, T.; Oladottir, B. A.; Oddsson, B.; Gudnason, J.; Högnadottir, T.; Stevenson, J. A.; Houghton, B. F.; McGarvie, D.; Sigurdardottir, G. M.

    2012-04-01

    Grímsvötn is the most active volcano in Iceland with >60 known eruptions in the last 800 years. Grímsvötn is located in the centre of the 8100 km2 Vatnajökull glacier and typically produces basalts in phreatomagmatic eruptions. Magma-water interaction occurs as the eruptions quickly melt their way through 50-200 m thick ice covering a subglacial caldera lake. Most of these eruptions have been relatively modest in size (0.01-0.1 km3 DRE) causing relatively minor fallout of tephra outside Vatnajökull. After a relative quiet second half of the 20th century, a period of increased volcanic activity in Grímsvötn started in the 1990s, with basaltic phreatomagmatic eruptions occurring within the caldera in 1998 and 2004. The 2011 eruption was therefore expected. It began at 19 UTC on 21 May. The plume quickly rose to 15-20 km, forming a 50-100 km wide umbrella cloud that was maintained until late on 22 May. Heavy fallout occurred in the districts 70-100 km south of the volcano, where periods of total darkness with drifting ash closed roads and caused distress to the local population. Wind directions and plume transport varied somewhat during the eruption. After 23 May, the eruption was relatively minor, with fallout mostly confined to the Vatnajökull glacier. The eruption ended on May 28. Most of the magma was erupted in the first two days. During this period strong northerly winds were dominant at low altitude, carrying the tephra towards south as a 2-4 km high cloud, while the top part of the plume first drifted eastwards and later northwards. Most of the fallout after the first few hours came from the low southwards drifting cloud while the high plume was white in colour and with apparently low concentration of ash leading to only minor fallout. This eruption falls into a class of events that seem to happen once every 100-200 years, with previous large historical eruptions including 1619 and 1873. Preliminary estimates indicate that the eruption produced 0

  17. The Bárðarbunga central volcano, crustal structure and eruption history

    NASA Astrophysics Data System (ADS)

    Larsen, Gudrun; Gudmundsson, Magnús T.; Einarsson, Páll; Óladóttir, Bergrún A.; Thordarson, Thorvaldur

    2015-04-01

    The Bárðarbunga central volcano is located in the northwestern part of Vatnajökull, the largest ice cap in Iceland. The volcano forms the centre of the largest volcanic system in Iceland, about 190 km long. Bárðarbunga rises 1000-1200 metes above the bedrock around it and is heavily ice covered. The caldera is fully subglacial and none of the inner rims are exposed. The caldera is elliptical in shape with the long axis trending roughly E-W. The area within the topographic rims is 65 km2 and the bottom of the caldera lies 600-700 m below the subglacial rims while the ice is 700-850 m thick in the caldera. Bárðarbunga has a positive Bouguer gravity anomaly of about 20 mGals, caused by dense intrusions in the uppermost 4-5 km of the crust. Superimposed on this gravity high is a smaller relative gravity low caused by a shallow body in the uppermost 2-3 km, with a center sligthly to the southeast of the midpoint of the caldera. Minor geothermal activity has been detected as small ice cauldrons over the subglacial caldera rim in two places. Seismic activity was relatively high in Bárðarbunga for decades before the present unrest, with M5 events occurring annually for over two decades prior to 1996, but displaying a more varied activity between 1996 and 2014. Tephrochronology has revealed the Holocene volcanic history of the Bárðarbunga system. Holocene products have been almost exclusively basaltic. During the period since the settlement of Iceland (the last ~1100 years) the Bárðarbunga system has been highly active. The historical activity includes sizable effusive eruptions occurring in the fissure swarm to the north of Vatnajökull, the largest being the 4 km3 Frambruni lava field formed before the 13th century. It also includes two large basaltic explosive eruptions (VEI 5 and VEI 5-6) on the fissure swarm to the southwest of Vatnajökull. Several moderate-sized subglacial to explosive phreatomagmatic eruptions have occurred on the ice covered part of

  18. Detection and estimation of volcanic eruption onset and mass flow rate using weather radar and infrasonic array

    NASA Astrophysics Data System (ADS)

    Marzano, Frank S.; Mereu, Luigi; Montopoli, Mario; Picciotti, Errico; Di Fabio, Saverio; Bonadonna, Costanza; Marchetti, Emanuele; Ripepe, Maurizio

    2015-04-01

    The explosive eruption of sub-glacial Eyjafjallajökull volcano in 2010 was of modest size, but ash was widely dispersed over Iceland and Europe. The Eyjafjallajökull pulsating explosive activity started on April 14 and ended on May 22. The combination of a prolonged and sustained ejection of volcanic ash and persistent northwesterly winds resulted in dispersal the volcanic cloud over a large part of Europe. Tephra dispersal from an explosive eruption is a function of multiple factors, including magma mass flow rate (MFR), degree of magma fragmentation, vent geometry, plume height, particle size distribution (PSD) and wind velocity. One of the most important geophysical parameters, derivable from the analysis of tephra deposits, is the erupted mass, which is essential for the source characterization and assessment of the associated hazards. MFR can then be derived by dividing the erupted mass by the eruption duration (if known) or based on empirical and analytical relations with plume height. Microwave weather radars at C and X band can provide plume height, ash concentration and loading, and, to some extent, PSD and MFR. Radar technology is well established and can nowadays provide fast three-dimensional (3D) scanning antennas together with Doppler and dual polarization capabilities. However, some factors can limit the detection and the accuracy of the radar products aforementioned. For example, the sensitivity of microwave radar measurements depends on the distance between the radar antenna and the target, the transmitter central wavelength, receiver minimum detachable power and the resolution volume. In addition, radar measurements are sensitive to particle sizes larger than few tens of microns thus limiting the radar-based quantitative estimates to the larger portion of the PSD. Volcanic activity produces infrasonic waves (i.e., acoustic waves below 20 Hz), which can propagate in the atmosphere useful for the remote monitoring of volcanic activity. Infrasound

  19. Investigating the use of the Saharan dust index as a tool for the detection of volcanic ash in SEVIRI imagery

    NASA Astrophysics Data System (ADS)

    Taylor, Isabelle; Mackie, Shona; Watson, Matthew

    2015-10-01

    Despite the similar spectral signatures of ash and desert dust, relatively little has been done to explore the application of dust detection techniques to the problem of volcanic ash detection. The Saharan dust index (SDI) is routinely implemented for dust monitoring at some centres and could be utilised for volcanic ash detection with little computational expense, thereby providing a product that forecasters already have some familiarity with to complement the suite of existing ash detection tools. We illustrate one way in which the index could be implemented for the purpose of ash detection by applying it to three scenes containing volcanic ash from the 2010 Eyjafjallajökull eruption, Iceland and the 2011 eruption of Puyehue, Chile. It was also applied to an image acquired over Etna in January 2011, where a volcanic plume is clearly visible but is unlikely to contain any ash. These examples demonstrate the potential of the SDI as a tool for ash monitoring under different environmental and atmospheric conditions. In addition to presenting a valuable qualitative product to aid monitoring, this work includes a quantitative assessment of the detection skill using a manually constructed expert ash mask. The optimum implementation of any technique is likely to be dependent on both atmospheric conditions and on the properties of the imaged ash (which is often unknown in a real-time situation). Here we take advantage of access to a 'truth' rarely available in a real-time situation and calculate an ash mask based on the optimum threshold for the specific scene, which is then used to demonstrate the potential of the SDI. The SDI mask is compared to masks calculated from a simplistic implementation of the more traditional split window method, again exploiting our access to the 'truth' to set the most appropriate threshold for each scene, and to a probabilistic method that is implemented without reference to the 'truth' and which provides useful insights into the likely

  20. Testing hypotheses for the use of Icelandic volcanic ashes as low cost, natural fertilizers

    NASA Astrophysics Data System (ADS)

    Seward, W.; Edwards, B.

    2012-04-01

    Andisols are soils derived from tephra/volcanic bedrock and are generally considered to be fertile for plant growth (cf. University of Hawaii at Manoa, CTAHR). However, few studies have been published examining the immediate effects of the addition of volcanic ash to soils immediately after an eruption. Our research is motivated by unpublished accounts from Icelandic farmers that the growing season following the 2010 Eyjafjallajökull eruption ended with unusually high yields in areas that were covered by ash from the eruption early in the spring. To test the hypothesis that addition of volcanic ash to soil would have no immediate effect on plant growth, we conducted a ~6 week growth experiment in at controlled environment at the Dickinson College Farm. The experiment used relatively fast growing grain seeds as a test crop, controlled watering, known quantities of peat as an organic base, and the following general experimental design: peat was mixed in known but systematically differing proportions with 1) commercial quartz sand, 2) basaltic ash from the 2004 Grimsvötn eruption, and 3) trachyandesite ash from the 2010 Eyjafjallajökull eruption. For all experiments, the seeds growing in the simulated soil created with the two different composition volcanic ash had higher germination rates, higher growth rates, and produced plants that were healthier in appearance than the soil made from peat mixed with quartz sand. Some differences were also noted between the germination and grow rates between the basaltic and trachyandesitic ash experiments as well. Working hypotheses to explain these results include (1) shard shapes and vesicles from volcanic ash provide better water retention than quartz, allowing water to be stored longer and increasing average soil moisture, and (2) chemical nutrients from the ash facilitate germination and growth of plants. Documenting the potential benefits of fresh volcanic ash as a fertilizer is important as use of fresh ash fertlizer

  1. Photogrammetric Retrieval of Etna's Plume Height from SEVIRI and MODIS

    NASA Astrophysics Data System (ADS)

    Zaksek, K.; Ganci, G.; Hort, M. K.

    2013-12-01

    Even remote volcanoes can impact the modern society due to volcanic ash dispersion in the atmosphere. A lot of research is currently dedicated to minimizing the impact of volcanic ash on air traffic. But the ash transport in the atmosphere and its deposition on land and in the oceans may also significantly influence the climate through modifications of atmospheric CO2. The emphasis of this contribution is the retrieval of volcanic ash plume height. This is important information for air traffic, to predict ash transport and to estimate the mass flux of the ejected material. The best way to monitor volcanic ash cloud top height (ACTH) on the global level is using satellite remote sensing. The most commonly used method for satellite ACTH compares brightness temperature of the cloud with the atmospheric temperature profile. Because of well-known uncertainties of this method we propose photogrammetric methods based on the parallax between data retrieved from geostationary (SEVIRI, HRV band; 1000 m spatial resolution) and polar orbiting satellites (MODIS, band 1; 250 m spatial resolution). The procedure works well if the data from both satellites are retrieved nearly simultaneously butMODIS does not retrieve the data at exactly the same time as SEVIRI. To compensate for advection in the atmosphere we use two sequential SEVIRI images (one before and one after the MODIS retrieval) and interpolate the cloud position from SEVIRI data to the time of MODIS retrieval. ACTH is then estimated by intersection of corresponding lines-of-view from MODIS and interpolated SEVIRI data. The proposed method has already been tested for the case of the Eyjafjallajökull eruption in April 2010. This case study had almost perfect conditions as the plume was vast and stretching over a homogeneous background - ocean. Here we show results of ACTH estimation during lava fountaining activity of Mount Etna in years 2011-2013. This activity resulted in volcanic ash plumes that are much smaller than

  2. Simulating the propagation of sulphur dioxide emissions from the fissure eruption in the Holuhraun lava field (Iceland) with the EURAD-IM

    NASA Astrophysics Data System (ADS)

    Fröhlich, Luise; Franke, Philipp; Friese, Elmar; Haas, Sarah; Lange, Anne Caroline; Elbern, Hendrik

    2015-04-01

    In the emergency case of a volcano eruption accurate forecasts of the transport of ash and gas emissions are crucial for health protection and aviation safety. In the frame of Earth System Knowledge Platform (ESKP) near real-time forecasts of ash and SO2 dispersion emitted by active volcanoes are simulated by the European Air pollution Dispersion Inverse Model (EURAD-IM). The model is driven by the Weather Research and Forecasting Model (WRF) and includes detailed gas phase and particle dynamics modules, which allow for quantitative estimates of measured volcano releases. Former simulations, for example related to the Eyjafjallajökull outbreak in 2010, were in good agreement with measurement records of particle number and SO2 at several European stations. At the end of August 2014 an fissure eruption has begun on Iceland in the Holuhraun lava field to the north-east of the Bardarbunga volcano system. In contrast to the explosive eruption of the Eyjafjallajökull in 2010, the Holuhraun eruption is rather effusive with a large and continuous flow of lava and a significant release of sulphur dioxide (SO2) in the lower troposphere, while ash emissions are insignificant. Since the Holuhraun fissure eruption has started, daily forecasts of SO2 dispersion are produced for the European region (15 km horizontal resolution grid) and published on our website (http://apps.fz-juelich.de/iek-8/RIU/vorhersage_node.php). To simulate the transport of volcanic emissions, realistic source terms like mass release rates of ash and SO2 or plume heights are required. Since no representative measurements are currently available for the simulations, rough qualitative assumptions, based on reports from the Icelandic Met Office (IMO), are used. However, frequent comparisons with satellite observations show that the actual propagation of the volcanic emissions is generally well reflected by the model. In the middle of September 2014 several European measurement sides recorded extremely high

  3. Simultaneous retrieval of volcanic sulphur dioxide and plume height from hyperspectral data using artificial neural networks

    NASA Astrophysics Data System (ADS)

    Piscini, Alessandro; Carboni, Elisa; Del Frate, Fabio; Grainger, Roy Gordon

    2014-08-01

    Artificial neural networks (ANNs) are a valuable and well-established inversion technique for the estimation of geophysical parameters from satellite images; once trained, they help generate very fast results. Furthermore, satellite remote sensing is a very effective and safe way to monitor volcanic eruptions in order to safeguard the environment and the people affected by those natural hazards. This paper describes an application of ANNs as an inverse model for the simultaneous estimation of columnar content and height of sulphur dioxide (SO2) plumes from volcanic eruptions using hyperspectral data from remote sensing. In this study two ANNs were implemented in order to emulate a retrieval model and to estimate the SO2 columnar content and plume height. ANNs were trained using all infrared atmospheric sounding interferometer (IASI) channels between 1000-1200 and 1300-1410 cm-1 as inputs, and the corresponding values of SO2 content and height of plume, obtained from the same IASI channels using the SO2 retrieval scheme by Carboni et al., as target outputs. The retrieval is demonstrated for the eruption of the Eyjafjallajökull volcano (Iceland) for the months of 2010 April and May and for the Grimsvotn eruption during 2011 May. Both neural networks were trained with a time series consisting of 58 hyperspectral eruption images collected between 2010 April 14 and May 14 and 16 images from 2011 May 22 to 26, and were validated on three independent data sets of images of the Eyjafjallajökull eruption, one in April and the other two in May, and on three independent data sets of the Grímsvötn volcanic eruption that occurred in 2011 May. The root mean square error (RMSE) values between neural network outputs and targets were lower than 20 Dobson units (DU) for SO2 total column and 200 millibar (mb) for plume height. The RMSE was lower than the standard deviation of targets for the Grímsvötn eruption. The neural network had a lower retrieval accuracy when the target

  4. Testing exposure of a jet engine to a dilute volcanic-ash cloud

    NASA Astrophysics Data System (ADS)

    Guffanti, M.; Mastin, L. G.; Schneider, D. J.; Holliday, C. R.; Murray, J. J.

    2013-12-01

    An experiment to test the effects of volcanic-ash ingestion by a jet engine is being planned for 2014 by a consortium of U.S. Government agencies and engine manufacturers, under the auspices of NASA's Vehicle Integrated Propulsion Research Program. The experiment, using a 757-type engine, will be an on-ground, on-wing test carried out at Edwards Air Force Base, California. The experiment will involve the use of advanced jet-engine sensor technology for detecting and diagnosing engine health. A primary test objective is to determine the effect on the engine of many hours of exposure to ash concentrations (1 and 10 mg/cu m) representative of ash clouds many 100's to >1000 km from a volcanic source, an aviation environment of great interest since the 2010 Eyjafjallajökull, Iceland, eruption. A natural volcanic ash will be used; candidate sources are being evaluated. Data from previous ash/aircraft encounters, as well as published airborne measurements of the Eyjafjallajökull ash cloud, suggest the ash used should be composed primarily of glassy particles of andesitic to rhyolitic composition (SiO2 of 57-77%), with some mineral crystals, and a few tens of microns in size. Collected ash will be commercially processed less than 63 microns in size with the expectation that the ash particles will be further pulverized to smaller sizes in the engine during the test. For a nominally planned 80 hour test at multiple ash-concentration levels, the test will require roughly 500 kg of processed (appropriately sized) ash to be introduced into the engine core. Although volcanic ash clouds commonly contain volcanic gases such as sulfur dioxide, testing will not include volcanic gas or aerosol interactions as these present complex processes beyond the scope of the planned experiment. The viscous behavior of ash particles in the engine is a key issue in the experiment. The small glassy ash particles are expected to soften in the engine's hot combustion chamber, then stick to cooler

  5. Modelling of Subglacial Volcanic and Geothermal Activity, during the 2014-15 Bárdarbunga-Holuhraun Eruption and Caldera Collapse

    NASA Astrophysics Data System (ADS)

    Reynolds, H. I.; Gudmundsson, M. T.; Hognadottir, T.

    2015-12-01

    Seismic unrest was observed within the subglacial caldera of Bárdarbunga on 16 August 2014, followed by seismicity tracing the path of a lateral dyke extending underneath the Vatnajökull glacier out to 45 km to the north east of the volcano. A short subaerial fissure eruption occurred at the site of the Holuhraun lavas, just north of the glacier edge on 29 August, before recommencing in earnest on 31 August with a large effusive eruption and accompanying slow caldera collapse, which lasted for approximately 6 months. The glacier surface around Bárdarbunga was monitored using aerial altimeter profiling. Several shallow depressions, known as ice cauldrons, formed around the caldera rim and on Dyngjujökull glacier above the dyke propagation path. The cauldrons range in volume from approximately 0.0003 km3 to 0.02 km3. Two types of melting were observed: high initial heat flux over a period of days which gradually disappears; and slower but more sustained melting rates. We present time series data of the development and evolution of these cauldrons, with estimates of the heat flux magnitudes involved.The nature of the heat source required to generate these cauldrons is not obvious. Two scenarios are explored: 1) small subglacial eruptions; or 2) increased geothermal activity induced by the dyke intrusion. We investigate these scenarios using numerical modelling, considering the surface heat flux produced, and timescales and spatial extent of associated surface anomalies. It is found that a magmatic intrusion into rocks where the groundwater is near the boiling point curve can cause rapid increase in geothermal activity, but even a shallow intrusion into a cold groundwater reservoir will have a muted thermal response. Thus, our results indicate that minor subglacial eruptions are the most plausible explanation for the observed rapid melting far from known geothermal areas. These results have implications for the interpretation of thermal signals observed at ice

  6. Extending Icelandic volcanological network operations into the ice caps

    NASA Astrophysics Data System (ADS)

    Vogfjord, Kristin; Bean, Chris; Roberts, Matthew; Ofeigsson, Benedikt; Guralp Systems Ltd.

    2013-04-01

    Many of Iceland's most active volcanoes are located under glaciers, with limited access for monitoring equipment. In the warming climate however, a few rock outcrops (nunataks) have emerged from the ice permitting some access improvement, but to properly monitor seismic signals from volcanoes deep inside the ice caps, instruments placed in the ice itself are needed. Continuous, real-time operation of monitoring equipment in harsh climate, heavy snow accumulation and icing conditions on a glacier is a considerable challenge. The FP7 project FUTUREVOLC, which focusses on Icelandic volcanoes, aims for the development of a multiparametric volcano monitoring and early warning system. One of the new developments in the project involves strengthening the existing real-time seismic monitoring and analysis systems by extending the permanent network into the Vatnajökull ice cap. The goal is to improve detection and location of seismic signals, such as microseismicity, LP events, ice-quakes and continuous tremor due to volcanic eruptions at the volcanoes under the ice cap. Real-time processing and discrimination of these signals could give early warnings of an imminent eruption. At subglacial volcanoes however, other processes, such as subglacial floods (jökulhlaup) and subglacial hydrothermal systems - boiling due to sudden drainage -also generate continuous tremor and can therefore lead to false eruption alarms. To minimise the number of false alarms, the network and processing will need to discriminate between the different tremor sources by determining their characteristics and track the temporal evolution and location of the source. For this purpose broad-band instruments will be placed on nunataks as well as in the ice and two short-period arrays will be located at the margin of Vatnajökull, close to subglacial flood paths from the Skaftár ice cauldrons. To record ice movements associated with the jökulhlaups, GPS receivers will be placed on outlet glaciers during

  7. Deformation derived from GPS geodesy associated with Bárðabunga 2014 rifting event in Iceland

    NASA Astrophysics Data System (ADS)

    Ofeigsson, B.; Hreinsdottir, S.; Parks, M.; Friðriksdóttir, H. M.; Sigmundsson, F.; Dumont, S.; Arnadottir, T.; Hooper, A. J.; Roberts, M. J.; Grapenthin, R.; Tung, S.; Guðmundsson, G.; Geirsson, H.; Jonsson, S.; Sturkell, E.; Lafemina, P.; Bennett, R. A.; Barsotti, S.; Jonsdottir, K.; Masterlark, T.

    2015-12-01

    On August 16, 2014 an intense seismic swarm started below the eastern part of Bárðarbunga caldera in the north-western corner of Vatnajökull ice-cap, Iceland. This marked the onset of the first rifting event in Iceland since the Krafla fires (1975-1982). The migration of the seismicity was corroborated by ground deformation suggesting lateral injection of magma, from the Bárðarbunga system, into a dyke. The seismicity migrated out of the caldera forming a dyke with roughly three segments, changing direction each time until August 28 when the migration stopped around 10 km south of Askja Volcano, eventually leading to a short lived eruption in Holuhraun north of Dyngjujökull. On the morning of August 31 a fissure eruption started in Holuhraun which lasted for roughly 6 months until February 27. Prior to the onset of the activity on August 16, at least since May 2014, subtle signs of inflation where observed on continuous GPS sites around the volcano indicating a volume increase in the roots of the Bárðarbunga volcanic system. When the activity started on August 16, the deformation pattern indicated a deflation centered within the caldera simultaneously with the lateral growth of the dyke also reflected in the migration of seismicity, along segments of variable strike. A maximum widening of 1.3 m occurred between stations on the opposite site of the dyke spaced 25 km apart. Displacements indicated the fastest rate of widening at any time in the most distal segment of the dyke throughout its evolution. After the dyke stopped propagating, the inflation continued decaying gradually. On September 4, five days into the second fissure eruption, the movements associated with the dyke where no longer detectable. As the fissure eruption continued the slowly decaying contraction was observed around the Bárðarbunga central volcano both in the piston like subsidence of the caldera floor, observed with a GPS instrument located on the ice surface within the caldera, as

  8. A new natural hazards data-base for volcanic ash and SO2 from global satellite remote sensing measurements

    NASA Astrophysics Data System (ADS)

    Stebel, Kerstin; Prata, Fred; Theys, Nicolas; Tampellini, Lucia; Kamstra, Martijn; Zehner, Claus

    2014-05-01

    Over the last few years there has been a recognition of the utility of satellite measurements to identify and track volcanic emissions that present a natural hazard to human populations. Mitigation of the volcanic hazard to life and the environment requires understanding of the properties of volcanic emissions, identifying the hazard in near real-time and being able to provide timely and accurate forecasts to affected areas. Amongst the many ways to measure volcanic emissions, satellite remote sensing is capable of providing global quantitative retrievals of important microphysical parameters such as ash mass loading, ash particle effective radius, infrared optical depth, SO2 partial and total column abundance, plume altitude, aerosol optical depth and aerosol absorbing index. The eruption of Eyjafjallajökull in April May, 2010 led to increased research and measurement programs to better characterize properties of volcanic ash and the need to establish a data-base in which to store and access these data was confirmed. The European Space Agency (ESA) has recognized the importance of having a quality controlled data-base of satellite retrievals and has funded an activity called Volcanic Ash Strategic Initiative Team VAST (vast.nilu.no) to develop novel remote sensing retrieval schemes and a data-base, initially focused on several recent hazardous volcanic eruptions. In addition, the data-base will host satellite and validation data sets provided from the ESA projects Support to Aviation Control Service SACS (sacs.aeronomie.be) and Study on an end-to-end system for volcanic ash plume monitoring and prediction SMASH. Starting with data for the eruptions of Eyjafjallajökull, Grímsvötn, and Kasatochi, satellite retrievals for Puyhue-Cordon Caulle, Nabro, Merapi, Okmok, Kasatochi and Sarychev Peak will eventually be ingested. Dispersion model simulations are also being included in the data-base. Several atmospheric dispersion models (FLEXPART, SILAM and WRF-Chem) are

  9. The impact of glacial fluctuations on the shallow proglacial groundwater systems of two SE Icelandic glaciers.

    NASA Astrophysics Data System (ADS)

    Levy, A.; Robinson, Z.; Krause, S.; Waller, R.

    2012-04-01

    Groundwater represents a key component of the complex hydrological processes of glaciated basins, where models project significant changes in glacial extent and mass balance. Exchange fluxes between groundwater and surface water can significantly impact discharge and stream level dynamics, biogeochemical cycling and aquifer and river habitat conditions. Understanding the spatial patterns and temporal dynamics of groundwater - surface water exchange fluxes is important for effective water resources management, especially considering the increasing pressures on groundwater and surface water systems resulting from environmental changes. This study investigates the shallow groundwater systems at two proglacial locations in SE Iceland. Impacted by the interaction between volcanic activity and glaciers, Skeiðarársandur is the world's largest active proglacial outwash plain (sandur). Skeiðarársandur contains an extensive unconfined aquifer whose thickness varies between 100-250m. Skaftafellsjökull, the second site of investigation, is a temperate valley glacier. This site is dominated by moraines and confined channels. Vegetation cover is higher than on the sandur. Groundwater seepage at both sites have potential impacts on eco-hydrological habitat conditions. Automated groundwater monitoring took place between July - mid August 2011. Preliminary results suggest strong coupling between rivers and the aquifer. This was illustrated by an increase in groundwater level following high, episodic increases in the discharge of the river Súla, western Skeiðarársandur. Results from the Skaftafellsjökull margin also suggest high river-aquifer coupling. A strong diurnal signal was detected in a well located between a large groundwater-fed lake and the glacial-fed river Skaftafellsà. Fluctuations in groundwater level, temperature and EC suggest strong response of the aquifer to changes in river level. This was illustrated during a flood event, in which an increase in

  10. Glacier discharge and climate variations

    NASA Astrophysics Data System (ADS)

    Dominguez, M. Carmen; Rodriguez-Puebla, Concepcion; Encinas, Ascension H.; Visus, Isabel; Eraso, Adolfo

    2010-05-01

    Different studies account for the warming in the polar regions that consequently would affect Glacier Discharge (GD). Since changes in GD may cause large changes in sensible and latent heat fluxes, we ask about the relationships between GD and climate anomalies, which have not been quantified yet. In this study we apply different statistical methods such as correlation, Singular Spectral Analysis and Wavelet to compare the behaviour of GD data in two Experimental Pilot Catchments (CPE), one (CPE-KG-62°S) in the Antarctica and the other (CPE-KVIA-64°N) in the Arctic regions. Both CPE's are measuring sub- and endo-glacier drainage for recording of glacier melt water run-off. The CPE-KG-62°S is providing hourly GD time series since January 2002 in Collins glacier of the Maxwell Bay in King George Island (62°S, 58°W). The second one, CPE-KVIA-64°N, is providing hourly GD time series since September 2003 in the Kviarjökull glacier of the Vatnajökull ice cap in Iceland (64°N, 16°W). The soundings for these measurements are pressure sensors installed in the river of the selected catchments for the ice cap (CPE-KG-62°S) and in the river of the glacier for (CPE-KVIA-64°N). In each CPE, the calibration function between level and discharge has been adjusted, getting a very high correlation coefficient (0.99 for the first one and 0.95 for the second one), which let us devise a precise discharge law for the glacier. We obtained relationships between GD with atmospheric variables such as radiation, temperature, relative humidity, atmospheric pressure and precipitation. We also found a negative response of GD to El Niño teleconnection index. The results are of great interest due to the GD impact on the climate system and in particular for sea level rise.

  11. Upper mantle viscosity and lithospheric thickness under Iceland determined from a microphysical modelling approach of mantle rheology

    NASA Astrophysics Data System (ADS)

    Barnhoorn, A.; van der Wal, W.; Drury, M. R.

    2012-04-01

    The Vatnajökull glacier, located in the south-east of Iceland is the largest ice cap of Iceland having a mean radius of ~50 km covering an area of ˜8100 km2. The Vatnajökull glacier is situated directly on top of the spreading axis in the eastern volcanic zone (EVZ) of the Icelandic mid-ocean ridge and near the inferred center of the Icelandic hotspot. Due to the vicinity of the glacier to the active tectonic area, the response of the solid earth to melting of the ice cap is strongly controlled by the properties of the hot newly formed upper mantle underneath the mid-ocean ridge. The relatively high temperatures in the mantle during rifting result in relatively low upper mantle viscosities and fast relaxation times in comparison with tectonically inactive glaciated areas such as in. In this study, estimates for lithospheric thickness and upper mantle viscosity under Iceland are produced by a microphysical modelling approach using the theoretical temperature distribution under mid-ocean ridges combined with olivine diffusion and dislocation creep flow laws. Large lateral variations in upper mantle viscosity and especially lithospheric thickness are expected for Iceland perpendicular to the ridge axis due to the large changes in temperatures away from the ridge axis. The lithospheric thickness (27-40 km) and upper mantle viscosity (2 × 1018-1019 Pa s) outcomes for the recent glaciation are consistent with previous reports of viscosity and lithospheric thickness from glacial isostatic adjustment studies. A combination of a 40 km thick elastic lithosphere and an average upper mantle viscosity of 5 × 1018 Pa s would suggest that the upper mantle under Iceland is most likely dry. Also, the results indicate that the presence of a plume under Iceland cannot explain the recent low viscosity values reported for Iceland. Using a larger extent and larger thickness of the Icelandic icecap during the Weichselian glaciation event (˜10,000 BP) this study predicts that during

  12. Subglacial melting associated with activity at Bárdarbunga volcano, Iceland, explored using numerical reservoir simulations

    NASA Astrophysics Data System (ADS)

    Reynolds, Hannah I.; Gudmundsson, Magnús T.; Högnadóttir, Thórdís

    2015-04-01

    Increased seismic activity was observed within the caldera of Bárdarbunga, a central volcano beneath Vatnajökull glacier, on 16 August 2014. The seismicity traced the path of a lateral dyke, initially propagating to the south east of the volcano, before changing course and continuing beyond the northern extent of the glacier. A short fissure eruption occurred at the site of the Holuhraun lavas on 29 August, lasting for approximately 5 hours and producing less than 1 million cubic meters of lava, before recommencing in earnest on 31 August with the large effusive eruption, which is still ongoing at the time of writing. The glacier surface has been monitored aerially since the onset of heightened seismic activity, and the caldera and dyke propagation path surveyed using radar profiling. Ice cauldrons are shallow depressions which form on the glacier surface due to basal melting, as a manifestation of heat flux from below; the melting ice acts as a calorimeter, allowing estimations of heat flux magnitude to be made. Several cauldrons were observed outside the caldera, two to the south east of Bárdarbunga, and three located above the path of the dyke under the Dyngjujökull outlet glacier. The cauldrons range in volume from approximately 0.001 km3 to 0.02 km3. We present time series data of the development and evolution of these cauldrons, with estimates of the heat flux magnitudes involved. The nature of the heat source required to generate the aforementioned cauldrons is not obvious and two scenarios are explored: 1) small subglacial eruptions; or 2) increased geothermal activity induced by the dyke intrusion. We investigate these scenarios using analytical and finite element modelling, considering the surface heat flux produced, and timescales and spatial extent of associated surface anomalies. A range of permeabilities has been explored. It is found that an intrusion of a dyke or sill into rocks where the groundwater is near or at the boiling point curve can

  13. Fracture movements and graben subsidence during the 2014 Bárðarbunga dike intrusion in Iceland

    NASA Astrophysics Data System (ADS)

    Hjartardóttir, Ásta Rut; Einarsson, Páll; Gudmundsson, Magnús Tumi; Högnadóttir, Thórdís

    2016-01-01

    A dike propagated ~ 48 km from the Bárðarbunga central volcano into one of its fissure swarms in August and early September 2014. The dike intrusion was accompanied by caldera subsidence in the ice-covered Bárðarbunga central volcano, as well as a propagating earthquake swarm, graben subsidence, and fissure eruptions in the fissure swarm. Most of the dike was emplaced in the glacier-covered part of the fissure swarm, but a 10 km long section at the distal (northern) end of the dike is ice-free. New ground fractures were observed in the ice-free part during the dike propagation and prior to the outbreak of a major lava-producing eruption. The fractures delineate two graben structures in direct continuation of each other. Here we show the extent and depth of the grabens and maps of fractures and eruptive fissures that were formed or reactivated north of the Vatnajökull glacier during the dike intrusion. The active graben subsidence was identified 3 days after seismicity reached the ice-free area. Then fractures delineated a 700-1000 m wide and 5 km long graben visible from the northern edge of the Vatnajökull glacier. Farther north a narrower, 250-450 m wide graben was seen. A short-lived minor eruption occurred between these grabens on the 29th of August 2014, 2 days after the grabens were identified. The northern graben was extended southwards during or before the eruption, and included the eruptive fissure. On the 31st of August 2014, a much larger eruption began on the same eruptive fissure. The fissure quickly obtained its maximum length of 2 km. This eruption lasted 6 months. A minor eruption, lasting 2 days or less, occurred on the southern graben on the 5th of September 2014. The first two eruptions took place on the same eruptive fissure that formed the pre-existing Holuhraun lava, presumably in the 18th century. Measurements in January 2015 show that the southern graben was 3.5-5.5 m deep, but the northern graben had been covered by lava. From the

  14. Triggered seismicity induced by stresses from the Bárðarbunga 2014 rifting event

    NASA Astrophysics Data System (ADS)

    Green, Robert; Greenfield, Tim; White, Robert

    2015-04-01

    From 16th August 2014 a rifting event at Bárðarbunga volcano in Iceland produced large surface deformation associated with rifting and the propagation of a 45 km long dyke northward away from the central volcano. Continuous GPS data from numerous sites recorded tens of centimetres displacements (Sigmundsson et al., Nature 2014) during the emplacement of this dyke, with a maximum widening between two stations of 1.3m. This continuous GPS data along with campaign GPS, InSAR and seismicity have been used to model the geometry and volume of the intruded dyke (Sigmundsson et al., 2014). The subsequent effect on the stress field caused by this intrusive volume was felt by the many volcanic centres in the surrounding area. Tungafellsjökull, Kistufell, Kverkfjöll and Askja all saw elevated levels of seismic activity during and following the intrusion of the dyke. The rapid final northward advance on 27th August also simultaneously caused a magnitude 4.2 earthquake in the geothermal field on the south-east side of Askja caldera, where recorded earthquakes have never previously exceeded a magnitude of two. Locations of earthquakes focussed at the leading edge of the dyke map out its northward propagation in short rapid bursts, and enable a temporal stressing history to be reconstructed. This can be correlated well with seismicity rates at the nearby Askja, Kistufell and Kverkfjöll volcanoes. We present both detailed seismic analysis and stress modelling which demonstrate triggering of increased seismicity and shut off in stress shadows, allowing us to test quantitative models of stress induced seismicity. Our local seismic array covers the numerous volcanic systems beneath the Vatnajökull glacier and surrounding areas in the Icelandic interior, and has been operating for many years leading up to this rifting event, providing excellent constraint on relative seismicity rate changes. We use automatic location routines to produce an extensive earthquake catalogue over

  15. Society's Growing Vulnerability to Natural Hazards and Implications for Geophysics Research (Invited)

    NASA Astrophysics Data System (ADS)

    Slingo, J.

    2010-12-01

    2010 is shaping up to be a year of unprecedented natural hazards - at least in living memory - which have raised our awareness of our vulnerability, challenged our scientific understanding and questioned our ability to predict and prepare for such events. This talk will take some examples from this year and use them to explore the implications for the research agenda in weather and climate modelling and prediction, and in how to translate our predictions into products and services that address user needs. Specific examples include the eruption of Eyjafjallajökull in Iceland, its impact on the aviation industry and the challenges that it posed to London Volcanic Ash Advisory Centre. The biblical proportions of the floods in Pakistan, and the Russian heat wave, wildfires and crop losses are examples of unprecedented events which have raised questions around climate change and the degree to which such events can be attributed or not to a warming world. The prospects of modelling and predicting these hazardous events and their impacts will be discussed in terms of our capabilities and what investments are needed in model development, supercomputing resources and the science of interdisciplinary impacts. Finally we live in an uncertain world, and preparedness requires us to take account of that uncertainty. The science challenges of moving towards more reliable and confident predictions that take us from uncertainty to probabilities and risk based assessments will be discussed.

  16. Living in the heart of a volcanic hazard zone and the issues that affect community vulnerability and resilience

    NASA Astrophysics Data System (ADS)

    Bird, Deanne; Gísladóttir, Guőrún; Dominey-Howes, Dale

    2010-05-01

    Volcanic risk mitigation strategies were revised for residents living in the eastern jökulhlaup hazard zone of Mýrdalsjökull, southern Iceland. These plans were trialled during a full-scale evacuation exercise on 25 March 2006. In order to assess residents' perception of and response to the exercise and proposed mitigation strategies a mixed methods survey was applied. This investigation consisted of field observations during the exercise and semi-structured interviews with emergency management officials and residents of a small rural community after the exercise. This community was the focus of this survey because these residents did not consider the previous plan appropriate to their beliefs and needs. The results of the survey revealed that residents are reluctant to evacuate and do not agree with the proposed strategies. Residents believe that the newly devised plans do not address the contextual issues of their community. Factors influencing the residents' perception are inherited knowledge, attachment to place and livelihood connections (i.e. concern for livestock). Residents' requests for alternative plans, in case adverse environmental conditions prevent evacuation, were ignored. Consequently, emergency managers failed to resolve residents' risk mitigation concerns prior to the evacuation exercise. We recommend that emergency managers should incorporate local knowledge and perceptions to ensure reduced vulnerability and enhanced community resilience.

  17. Local and remote infrasound from explosive volcanism

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  18. Eyjafjallajokull Volcano Plume Particle-Type Characterization from Space-Based Multi-angle Imaging

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph A.; Limbacher, James

    2012-01-01

    The Multi-angle Imaging SpectroRadiometer (MISR) Research Aerosol algorithm makes it possible to study individual aerosol plumes in considerable detail. From the MISR data for two optically thick, near-source plumes from the spring 2010 eruption of the Eyjafjallaj kull volcano, we map aerosol optical depth (AOD) gradients and changing aerosol particle types with this algorithm; several days downwind, we identify the occurrence of volcanic ash particles and retrieve AOD, demonstrating the extent and the limits of ash detection and mapping capability with the multi-angle, multi-spectral imaging data. Retrieved volcanic plume AOD and particle microphysical properties are distinct from background values near-source, as well as for overwater cases several days downwind. The results also provide some indication that as they evolve, plume particles brighten, and average particle size decreases. Such detailed mapping offers context for suborbital plume observations having much more limited sampling. The MISR Standard aerosol product identified similar trends in plume properties as the Research algorithm, though with much smaller differences compared to background, and it does not resolve plume structure. Better optical analogs of non-spherical volcanic ash, and coincident suborbital data to validate the satellite retrieval results, are the factors most important for further advancing the remote sensing of volcanic ash plumes from space.

  19. A Summary Case Report on the Health Impacts and Response to the Pakistan Floods of 2010

    PubMed Central

    Shabir, Omar

    2013-01-01

    In July 2010, Pakistan suffered nationwide floods after unprecedented monsoon rains overwhelmed the Indus basin. The ensuing floods claimed 1985 lives, injured 2946 people and affected over 20.2 million people. Seventy-eight out of 121 districts were affected and at one stage one-fifth of the country’s land was inundated with water. Indiscriminate damage was caused to housing, educational and health facilities, communication networks, power plants and grids, irrigation channels, agricultural land and livestock. Over 37 million medical consultations were reported within one year of the floods with acute respiratory infection, skin diseases, acute diarrhoea and suspected malaria forming the most common presentations. Rescue and relief operations were organised through the National Disaster Management Authority and a UN Cluster Approach was adopted for providing humanitarian assistance. The Office for the Coordination of Humanitarian Affairs (OCHA) played a pivotal role in coordinating relief efforts between cluster groups and providing communication platforms for identifying gaps and sharing information. This paper attempts to collate information available in the public domain into a summary report based on key principles described by Kulling et al. (2010) on health crisis reporting. PMID:23591385

  20. The bioreactivity of the sub-10 μm component of volcanic ash: Soufrière Hills volcano, Montserrat.

    PubMed

    Jones, Timothy; Bérubé, Kelly

    2011-10-30

    With the recent eruption of the Icelandic volcano Eyafallajökull and resulting ash cloud over much of Europe there was considerable concern about possible respiratory hazards. Volcanic ash can contain minerals that are known human respiratory health hazards such as cristobalite. Short-term ash exposures can cause skin sores, respiratory and ocular irritations and exacerbation of pre-existing lung conditions such as asthma. Long-term occupational level exposures to crystalline silicon dioxide can cause lung inflammation, oedema, fibrosis and cancer. The potential health effects would be dependent on factors including mineralogy, surface chemistry, size, and levels and duration of exposure. Bulk ash from the Soufrière Hills volcano was sourced and inhalable (<2.5 μm) ash samples prepared and physicochemically characterised. The fine ash samples were tested for bioreactivity by SDS-PAGE which determined the strength of binding between mineral grains and lung proteins. Selected proteins bound tightly to cristobalite, and bound loosely to other ash components. A positive correlation was seen between the amount of SiO(2) in the sample and the strength of the binding. The strength of binding is a function of the mineral's bioreactivity, and therefore, a potential geo-biomarker of respiratory risk. PMID:21872393

  1. The European air traffic management response to volcanic ash crises: towards institutionalised aviation crisis management.

    PubMed

    Dopagne, Jacques

    2011-06-01

    A cloud of ash drifting from the erupting Eyjafjallajökull volcano in Iceland in April and May 2010 covered Europe and created an unprecedented situation. It resulted in an almost complete lockdown of European airspace in the period from 15th to 21st April, 2010: more than 100,000 flights were cancelled, 10 million people were affected and over US$1.8bn was lost by airlines globally. This paper presents the air traffic management (ATM) view of the situation. Through an analysis of the evolution of the events in the affected region, the paper will provide more details on ATM planning, reaction and follow-up actions. Furthermore, the influence of this event on the identification of further improvements needed to advance volcanic procedures internationally will be discussed. Actions undertaken since the end of the event - the establishment of the European Aviation Crisis Coordination Cell, running of the International Civil Aviation Organization VOLCEX 11/01 volcanic ash exercise and European response to the Grimsvötn eruption in May 2011 - will be discussed at the end of the paper. PMID:21835749

  2. Emergency hospital visits in association with volcanic ash, dust storms and other sources of ambient particles: a time-series study in Reykjavík, Iceland.

    PubMed

    Carlsen, Hanne Krage; Gislason, Thorarinn; Forsberg, Bertil; Meister, Kadri; Thorsteinsson, Throstur; Jóhannsson, Thorsteinn; Finnbjornsdottir, Ragnhildur; Oudin, Anna

    2015-04-13

    Volcanic ash contributed significantly to particulate matter (PM) in Iceland following the eruptions in Eyjafjallajökull 2010 and Grímsvötn 2011. This study aimed to investigate the association between different PM sources and emergency hospital visits for cardiorespiratory causes from 2007 to 2012. Indicators of PM10 sources; "volcanic ash", "dust storms", or "other sources" (traffic, fireworks, and re-suspension) on days when PM10 exceeded the daily air quality guideline value of 50 µg/m3 were entered into generalized additive models, adjusted for weather, time trend and co-pollutants. The average number of daily emergency hospital visits was 10.5. PM10 exceeded the air quality guideline value 115 out of 2191 days; 20 days due to volcanic ash, 14 due to dust storms (two days had both dust storm and ash contribution) and 83 due to other sources. High PM10 levels from volcanic ash tended to be significantly associated with the emergency hospital visits; estimates ranged from 4.8% (95% Confidence Interval (CI): 0.6, 9.2%) per day of exposure in unadjusted models to 7.3% (95% CI: -0.4, 15.5%) in adjusted models. Dust storms were not consistently associated with daily emergency hospital visits and other sources tended to show a negative association. We found some evidence indicating that volcanic ash particles were more harmful than particles from other sources, but the results were inconclusive and should be interpreted with caution.

  3. Chemical and biological availability of hydrocarbons in urban harbor sediments

    USGS Publications Warehouse

    LeBlanc, L.A.; Brownawell, Bruce J.

    2002-01-01

    The degradation of saturated and aromatic hydrocarbons was studied in batch slurry experiments conducted with field-aged sediments, highly impacted by hydrocarbon pollution. Experiments focused on examining the effects of desorption limitations to hydrocarbon mineralization and degradation. Degradation of PAH (e.g., naphthalene, fluorene, acenaphthene) and saturated hydrocarbons was examined in field-aged sediments collected from four sites in greater NY Harbor and western Long Island Sound. The sites were Rikers Island in far western Long Island Sound, Williamsburg Bridge in the East River, Shooters Island in the Arthur Kill, and the Kill Van Kull off Bayonne, New Jersey. Patterns of hydrocarbon desorption and degradation in weathered sediments were complicated by the mixed combustion and oil-derived hydrocarbon sources, and differed markedly from patterns seen in sediments following an oil spill. Rates of degradation in experiments with spiked sediments, especially over short timescales, did not appear to be limited by rates of desorption. This is an abstract of a paper presented at the 224th ACS National Meeting (Boston, MA 8/18-22/2002).

  4. Evaluation of quantitative satellite-based retrievals of volcanic ash clouds

    NASA Astrophysics Data System (ADS)

    Schneider, D. J.; Pavolonis, M. J.; Bojinski, S.; Siddans, R.; Thomas, G.

    2015-12-01

    Volcanic ash clouds are a serious hazard to aviation, and mitigation requires a robust system of volcano monitoring, eruption detection, characterization of cloud properties, forecast of cloud movement, and communication of warnings. Several research groups have developed quantitative satellite-based volcanic ash products and some of these are in operational use by Volcanic Ash Advisory Centers around the world to aid in characterizing cloud properties and forecasting regions of ash hazard. The algorithms applied to the satellite data utilize a variety of techniques, and thus produce results that differ. The World Meteorological Organization has recently sponsored an intercomparison study of satellite-based retrievals with four goals: 1) to establish a validation protocol for satellite-based volcanic ash products, 2) to quantify and understand differences in products, 3) to develop best practices, and 4) to standardize volcanic cloud geophysical parameters. Six volcanic eruption cases were considered in the intercomparison: Eyjafallajökull, Grimsvötn, Kelut, Kirishimayama, Puyehue-Cordón Caulle, and Sarychev Peak. Twenty-four algorithms were utilized, which retrieved parameters including: ash cloud top height, ash column mass loading, ash effective radius, and ash optical depth at visible and thermal-infrared wavelengths. Results were compared to space-based, airborne, and ground-based lidars; complementary satellite retrievals; and manual "expert evaluation" of ash extent. The intercomparison results will feed into the International Civil Aviation Organization "Roadmap for International Airways Volcano Watch", which integrates volcanic meteorological information into decision support systems for aircraft operations.

  5. Assimilation of satellite-retrieved data to improve forecasts of volcanic ash concentrations

    NASA Astrophysics Data System (ADS)

    Fu, Guangliang; Lin, Haixiang; Heemink, Arnold; Segers, Arjo; Lu, Sha

    2016-04-01

    Since the 2010 Eyjafjallajökull volcano eruption caused a big problem to aviation and economy, improvement on volcanic ash forecast has been put onto the research agenda. Satellite-based measurements are considered as the most common and cheapest type of volcanic ash observations. However, due to its intrinsic functionality, satellite-retrived two-dimensional data can not be easily and directly combined with a three-dimensional volcanic ash model to improve volcanic ash forecasts continuously. Here we propose a satellite observational operator to transfer 2D volcanic ash mass loadings to 3D concentrations. The uncertainties of reconstructed 3D ash concentrations are also quantified. Sequential data assimilation is used to continuously assimilate the reconstructed volcanic ash concentrations. The results are evaluated in a multi-observational network including satellite-based measurements and aircraft in-situ measurements. Here we show for long-time assimilating satellite-based measurements, Ensemble Squre Root Filter (EnSR), as a common sequential data assimilation technique, is more efficient than Ensemble Kalman Filter (EnKF) because the ensemble size required for EnSR is considerable less than the ensemble size of EnKF for a comparable assimilation performance. Moreover, the forecast after assimilation is validated to be accurate and valid within 15 hours.

  6. Petroleum and hazardous chemical spills in Newark Bay, New Jersey, USA from 1982 to 1991.

    PubMed

    Gunster, D G; Gillis, C A; Bonnevie, N L; Abel, T B; Wenning, R J

    1993-01-01

    Newark Bay, New Jersey, is particularly vulnerable to ecological damage from petroleum and chemical spills, as a result of the enclosed nature and shallow depth of the bay, the high frequency of shipping traffic, and the numerous chemical and petroleum transfer terminals located alongs its shores. To evaluate the potential impacts to the natural resources of this coastal estuarine ecosystem, chemical and petroleum accidents reported to the US Coast Guard (USCG) between 1982 and 1991 were compiled to determine the frequency and volume of these incidents in Newark Bay and in each of its major tributaries. Records obtained from the USCG National Response Center's computerized database indicated that more than 1453 accidental incidents, resulting in the release of more than 18 million US gallons of hazardous materials and petroleum products, occurred throughout Newark Bay during this period of time. The bulk of the materials released to the aquatic environment consisted of petroleum products, specifically No. 6 Fuel Oil (103 spills, 12 829 272 US gal) and gasoline (207 spills, 48 816 US gal). The majority of the reported incidents occurred in the Arthur Kill and its tributaries, as well as in the Kill Van Kull and the Passaic River. The results of this study indicated that the accidental discharge of petroleum and hazardous chemicals represents a significant source of chemical pollution in Newark Bay. Based on the frequency of spills and the volume of materials released to the aquatic environment, it is likely that these events are having a deleterious effect on the Newark Bay ecosystem.

  7. Water vapour variability in the high-latitude upper troposphere - Part 2: Impact of volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Sioris, Christopher E.; Zou, Jason; McElroy, C. Thomas; Boone, Chris D.; Sheese, Patrick E.; Bernath, Peter F.

    2016-02-01

    The impact of volcanic eruptions on water vapour in the high-latitude upper troposphere is studied using deseasonalized time series based on observations by the Atmospheric Chemistry Experiment (ACE) water vapour sensors, namely MAESTRO (Measurements of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation) and the Fourier Transform Spectrometer (ACE-FTS). The two eruptions with the greatest impact on the high-latitude upper troposphere during the time frame of this satellite-based remote sensing mission are chosen. The Puyehue-Cordón Caulle volcanic eruption in June 2011 was the most explosive in the past 24 years and is shown to be able to account for the observed (50 ± 12) % increase in water vapour in the southern high-latitude upper troposphere in July 2011 after a minor adjustment for the simultaneous influence of the Antarctic oscillation. Eyjafjallajökull erupted in the spring of 2010, increasing water vapour in the upper troposphere at northern high latitudes significantly for a period of ˜ 1 month. These findings imply that extratropical volcanic eruptions in windy environments can lead to significant perturbations to high-latitude upper tropospheric humidity mostly due to entrainment of lower tropospheric moisture by wind-blown plumes. The Puyehue-Cordón Caulle eruption must be taken into account to properly determine the magnitude of the trend in southern high-latitude upper tropospheric water vapour over the last decade.

  8. Risk perceptions and trust following the 2010 and 2011 Icelandic volcanic ash crises.

    PubMed

    Eiser, J Richard; Donovan, Amy; Sparks, R Stephen J

    2015-02-01

    Eruptions at the Icelandic volcanoes of Eyjafjallajökull (2010) and Grimsvötn (2011) produced plumes of ash posing hazards to air traffic over northern Europe. In imposing restrictions on air traffic, regulators needed to balance the dangers of accidents or aircraft damage against the cost and inconvenience to travelers and industry. Two surveys examined how members of the public viewed the necessity of the imposed restrictions and their trust in different agencies as estimators of the level of risk. Study 1 was conducted with 213 British citizens (112 males, 101 females), who completed questionnaires while waiting for flights at London City Airport during May 2012. Study 2 involved an online survey of 301 Icelandic citizens (172 males, 127 females, 2 undeclared gender) during April 2012. In both samples, there was general support for the air traffic restrictions, especially among those who gave higher estimates of the likelihood of an air accident or mishap having otherwise happened. However, in both countries, the (minority of) respondents who had personally experienced travel disruption were less convinced that these restrictions were all necessary. Scientists, the International Civil Aviation Organization, and (in Iceland) the Icelandic Department of Civil Protection were all highly trusted, and seen as erring on the side of caution in their risk estimates. Airlines were seen as more likely to underestimate any risk. We conclude that perceptions of the balance between risk and caution in judgments under uncertainty are influenced by one's own motives and those attributed to others. PMID:25263505

  9. Different communities, different perspectives: issues affecting residents' response to a volcanic eruption in southern Iceland

    NASA Astrophysics Data System (ADS)

    Bird, Deanne K.; Gísladóttir, Guðrún; Dominey-Howes, Dale

    2011-11-01

    This research investigates residents' knowledge and perception of the Katla volcano and emergency response procedures in all rural and urban communities located in the eastern and southern Katla hazard zones. Using a questionnaire survey conducted in 2008, we demonstrate that there is an apparent difference between rural and urban communities' knowledge and perceptions, and identify some of the issues influencing residents' perspectives and behaviour. All rural and most urban residents have an accurate knowledge of Katla, the proposed warning system and emergency response plan. Urban residents perceived the emergency response plan to be appropriate. In comparison, rural residents did not perceive the emergency response plan as appropriate. Rural residents stated that they would personally assess the situation before deciding on a course of action independent of the proposed plan. Livelihood connections and inherited knowledge affect rural residents' ability and willingness to comply with the recommended procedures. Factors such as hazard knowledge, sense of community and attachment to place indicate that rural residents are more resilient to volcanic hazards. Based on our findings we recommend that emergency management agencies consider issues such as personal responsibility, neighbourliness and community involvement and cooperation, to develop and implement more appropriate volcanic risk mitigation strategies. In light of the recent Eyjafjallajökull eruptions, we provide a brief discussion on the 2010 emergency response. Although our findings are Iceland-specific, our recommendations may be applied internationally to other volcanic and disaster-prone regions.

  10. Functional Information: Towards Synthesis of Biosemiotics and Cybernetics

    PubMed Central

    Sharov, Alexei A.

    2012-01-01

    Biosemiotics and cybernetics are closely related, yet they are separated by the boundary between life and non-life: biosemiotics is focused on living organisms, whereas cybernetics is applied mostly to non-living artificial devices. However, both classes of systems are agents that perform functions necessary for reaching their goals. I propose to shift the focus of biosemiotics from living organisms to agents in general, which all belong to a pragmasphere or functional universe. Agents should be considered in the context of their hierarchy and origin because their semiosis can be inherited or induced by higher-level agents. To preserve and disseminate their functions, agents use functional information - a set of signs that encode and control their functions. It includes stable memory signs, transient messengers, and natural signs. The origin and evolution of functional information is discussed in terms of transitions between vegetative, animal, and social levels of semiosis, defined by Kull. Vegetative semiosis differs substantially from higher levels of semiosis, because signs are recognized and interpreted via direct code-based matching and are not associated with ideal representations of objects. Thus, I consider a separate classification of signs at the vegetative level that includes proto-icons, proto-indexes, and proto-symbols. Animal and social semiosis are based on classification, and modeling of objects, which represent the knowledge of agents about their body (Innenwelt) and environment (Umwelt). PMID:22368439

  11. In vitro evaluation of pulmonary deposition of airborne volcanic ash

    NASA Astrophysics Data System (ADS)

    Lähde, Anna; Sæunn Gudmundsdottir, Sigurbjörg; Joutsensaari, Jorma; Tapper, Unto; Ruusunen, Jarno; Ihalainen, Mika; Karhunen, Tommi; Torvela, Tiina; Jokiniemi, Jorma; Järvinen, Kristiina; Gíslason, Sigurður Reynir; Briem, Haraldur; Gizurarson, Sveinbjörn

    2013-05-01

    There has been an increasing interest in the effects of volcanic eruption on the environment, climate, and health following two recent volcanic eruptions in Iceland. Although health issues are mainly focused on subjects living close to the eruption due to the high concentration of airborne ash and gasses in close vicinity to the volcanoes, the ash may also reach high altitude and get distributed thousands of kilometers away from the volcano. Ash particles used in the studies were collected at the Eyjafjallajökull and Grímsvötn eruption sites. The composition, size, density and morphology of the particles were analyzed and the effect of particle properties on the re-dispersion and lung deposition were studied. The aerodynamic size and morphology of the particles were consistent with field measurement results obtained during the eruptions. Due to their size and structure, the ash particles can be re-suspended and transported into the lungs. The total surface area of submicron ash particles deposited into the alveolar and tracheobronchial regions of the lungs were 3-9% and 1-2%, respectively. Although the main fraction of the surface area is deposited in the head airways region, a significant amount of particles can deposit into the alveolar and tracheobronchial regions. The results indicate that a substantial increase in the concentration of respirable airborne ash particles and associated health hazard can take place if the deposited ash particles are re-suspended under dry, windy conditions or by outdoor human activity.

  12. Civil aviation management during explosive volcanic eruptions: A survey on the stakeholders' perspective on the use of tephra dispersal models

    NASA Astrophysics Data System (ADS)

    Scaini, Chiara; Bolić, Tatjana; Folch, Arnau; Castelli, Lorenzo

    2015-03-01

    Impacts of explosive volcanic eruptions on civil aviation were reconsidered after the 2010 Eyjafjallajökull eruption in Iceland, which caused unprecedented disruptions of air traffic operations in Europe. During and after the aviation breakdown of April-May 2010, communication between the involved stakeholders was recognized as a major concern. Due to the complexity and multidisciplinary nature of the topic, a great number of actors are involved, which often have little interaction outside these exceptional events. In this work, we aim at identifying the relationships between the stakeholders involved in aviation management during eruptions, as well as their needs and priorities. We perform an anonymous on-line survey, focused mainly on the use of tephra dispersal models for civil aviation purposes. We collect feedback on recent developments including our current impact assessment research, which produced a GIS-based software tool to estimate impacts on aviation based on tephra dispersal forecasts. Answers allow identifying stakeholders' requirements on ash dispersal forecasts and their use for aviation management purposes. We underline the main differences between three homogeneous groups (aviation managers and employees, modellers and field scientists, other stakeholders) and identify main end-user requirements for developing tools similar to ours. This work provides useful insights for the development of tools to support aviation stakeholders during volcanic eruptions.

  13. Investigation of boundary layer dynamics, dust and volcanic ash clouds with laser ceilometer

    NASA Astrophysics Data System (ADS)

    Münkel, Christoph; Schäfer, Klaus; Emeis, Stefan

    2013-10-01

    The main purpose of eye-safe laser ceilometers is regular reporting of cloud base height, vertical visibility, and cloud cover. These instruments operate unattended in harsh weather conditions. The application of state-of-the-art electronics increases the quality of backscatter profiles and thus qualifies modern ceilometers for applications beyond cloud base detection. The single lens optics of the ceilometers introduced in this paper results in a compact and robust design and enables their application in campaigns monitoring climate change effects. That is why three of the German Terrestrial Environmental Observatories (TERENO) run by the Karlsruhe Institute of Technology are equipped with a ceilometer. The Technical University of Denmark (DTU) utilizes such an instrument to study arctic cloud formation at Station Nord, Greenland. Recent applications include site assessment for solar energy applications in the Arabic Peninsula and monitoring of Sahara dust cloud and biomass burning plume events over Germany. Backward trajectory calculations with the HYSPLIT trajectory model provided by the NOAA Air Resources Laboratory have been carried out to investigate possible sources, including wood fires in southern France and eruptions of the Eyjafjallajökull and Puyehue- Cordón Caulle volcanoes.

  14. Emergency hospital visits in association with volcanic ash, dust storms and other sources of ambient particles: a time-series study in Reykjavík, Iceland.

    PubMed

    Carlsen, Hanne Krage; Gislason, Thorarinn; Forsberg, Bertil; Meister, Kadri; Thorsteinsson, Throstur; Jóhannsson, Thorsteinn; Finnbjornsdottir, Ragnhildur; Oudin, Anna

    2015-04-01

    Volcanic ash contributed significantly to particulate matter (PM) in Iceland following the eruptions in Eyjafjallajökull 2010 and Grímsvötn 2011. This study aimed to investigate the association between different PM sources and emergency hospital visits for cardiorespiratory causes from 2007 to 2012. Indicators of PM10 sources; "volcanic ash", "dust storms", or "other sources" (traffic, fireworks, and re-suspension) on days when PM10 exceeded the daily air quality guideline value of 50 µg/m3 were entered into generalized additive models, adjusted for weather, time trend and co-pollutants. The average number of daily emergency hospital visits was 10.5. PM10 exceeded the air quality guideline value 115 out of 2191 days; 20 days due to volcanic ash, 14 due to dust storms (two days had both dust storm and ash contribution) and 83 due to other sources. High PM10 levels from volcanic ash tended to be significantly associated with the emergency hospital visits; estimates ranged from 4.8% (95% Confidence Interval (CI): 0.6, 9.2%) per day of exposure in unadjusted models to 7.3% (95% CI: -0.4, 15.5%) in adjusted models. Dust storms were not consistently associated with daily emergency hospital visits and other sources tended to show a negative association. We found some evidence indicating that volcanic ash particles were more harmful than particles from other sources, but the results were inconclusive and should be interpreted with caution. PMID:25872017

  15. FPLUME-1.0: An integrated volcanic plume model accounting for ash aggregation

    NASA Astrophysics Data System (ADS)

    Folch, A.; Costa, A.; Macedonio, G.

    2015-09-01

    Eruption Source Parameters (ESP) characterizing volcanic eruption plumes are crucial inputs for atmospheric tephra dispersal models, used for hazard assessment and risk mitigation. We present FPLUME-1.0, a steady-state 1-D cross-section averaged eruption column model based on the Buoyant Plume Theory (BPT). The model accounts for plume bent over by wind, entrainment of ambient moisture, effects of water phase changes, particle fallout and re-entrainment, a new parameterization for the air entrainment coefficients and a model for wet aggregation of ash particles in presence of liquid water or ice. In the occurrence of wet aggregation, the model predicts an "effective" grain size distribution depleted in fines with respect to that erupted at the vent. Given a wind profile, the model can be used to determine the column height from the eruption mass flow rate or vice-versa. The ultimate goal is to improve ash cloud dispersal forecasts by better constraining the ESP (column height, eruption rate and vertical distribution of mass) and the "effective" particle grain size distribution resulting from eventual wet aggregation within the plume. As test cases we apply the model to the eruptive phase-B of the 4 April 1982 El Chichón volcano eruption (México) and the 6 May 2010 Eyjafjallajökull eruption phase (Iceland).

  16. Assimilating aircraft-based measurements to improve forecast accuracy of volcanic ash transport

    NASA Astrophysics Data System (ADS)

    Fu, G.; Lin, H. X.; Heemink, A. W.; Segers, A. J.; Lu, S.; Palsson, T.

    2015-08-01

    The 2010 Eyjafjallajökull volcano eruption had serious consequences to civil aviation. This has initiated a lot of research on volcanic ash transport forecast in recent years. For forecasting the volcanic ash transport after eruption onset, a volcanic ash transport and diffusion model (VATDM) needs to be run with Eruption Source Parameters (ESP) such as plume height and mass eruption rate as input, and with data assimilation techniques to continuously improve the initial conditions of the forecast. Reliable and accurate ash measurements are crucial for providing a successful ash clouds advice. In this paper, simulated aircraft-based measurements, as one type of volcanic ash measurements, will be assimilated into a transport model to identify the potential benefit of this kind of observations in an assimilation system. The results show assimilating aircraft-based measurements can significantly improve the state of ash clouds, and further providing an improved forecast as aviation advice. We also show that for advice of aeroplane flying level, aircraft-based measurements should be preferably taken from this level to obtain the best performance on it. Furthermore it is shown that in order to make an acceptable advice for aviation decision makers, accurate knowledge about uncertainties of ESPs and measurements is of great importance.

  17. Seasonal evolution of subglacial drainage pathways within a soft bedded anastomosing system

    NASA Astrophysics Data System (ADS)

    Hart, Jane; Young, David; Martinez, Kirk

    2016-04-01

    We have studied the dynamic annual subglacial behavior associated with Skálafellsjökull, Iceland, a temperate glacier resting on a deformable sediment layer, using subglacial wireless probes to measure till water pressure and tilt, surface installations to measure glacier motion, and a camera to measure river discharge. We argue that the subglacial hydrology system changes throughout the year from a fast connected system in the spring and autumn (with balanced inputs and outputs), to a duel system in summer with fast channels and slow moving storage (with greater inputs than outputs). In winter there is an episodic fast system associated with high meltwater input accompanied by changes in till water pressure and ice velocity and releases of water from a heterogeneous storage sources to produce some of the largest annual discharges. We develop models to relate the observed summer and winter discharges to daily ice surface melt. We demonstrate that there is a subglacial anastomosing system, consisting of water sheets at the ice-bed interface, bedrock cavities, braided channels with associated back-water reservoir areas, which has the ability to rapidly change channel form depending on melt-water inputs, and easily access water stored within a series of linked subglacial reservoirs.

  18. Estimation of eruption source parameters from umbrella cloud or downwind plume growth rate

    NASA Astrophysics Data System (ADS)

    Pouget, Solène; Bursik, Marcus; Webley, Peter; Dehn, Jon; Pavolonis, Michael

    2013-05-01

    We introduce a new method to estimate mass eruption rate (MER) and mass loading from the growth of a volcanic umbrella cloud or downwind plume using satellite images, or photographs where ground-based observations are available. This new method is compared with pre-existing models and documented mass eruption rate given in the research literature. We applied the method to five well-studied eruptions (Mount St. Helens, 1980; Redoubt, 1990; Pinatubo, 1991; Hekla, 2000 and Eyjafjallajökull, 2010) and to five less well-documented eruptions (Kliuchevsko'i, 1994; Okmok, 2008; Kasatochi, 2008; Sarychev Peak, 2009 and Bezymianny, 2012). The mass eruption rate is obtained by estimation of the radius of the umbrella cloud with time or by estimation of the width of the downwind plume with distance from the volcano. The results given by the new method show a more fully characterized MER as a function of time than do the results given by pre-existing methods, and allow a faster, remote assessment of the mass eruption rate, even for volcanoes that are difficult to study. The method thus may provide an additional important path to the estimation of source parameters and the forecasting of ash cloud propagation. In addition, in cases where numerous methods are available, use of the method yields new, independent measures of mass eruption rate, hence an ability to estimate uncertainty in mass eruption rate, which could be used in probabilistic estimations of ash cloud propagation.

  19. SO2 as a possible proxy for volcanic ash in aviation hazard avoidance

    NASA Astrophysics Data System (ADS)

    Sears, T. M.; Thomas, G. E.; Carboni, E.; Smith, A. J. A.; Grainger, R. G.

    2013-06-01

    Airborne volcanic ash poses a significant danger to aircraft, but is difficult to quantify accurately using satellite data, while sulphur dioxide is much easier to detect accurately, but is much less of a direct hazard to aviation. This paper investigates the reliability of using SO2 as a proxy for the location of volcanic ash, using an SO2 retrieval from the Infrared Atmospheric Sounding Interferometer (IASI) and ash detections from IASI and the Advanced Along Track Scanning Radiometer (AATSR). Using a numerical "missed ash fraction" applied to the eruptions of Eyjafjallajökull in 2010 and Puyehue-Cordón Caulle in 2011 reveals that the SO2 flag typically misses ˜30% of the detectable ash. Furthermore, the missed ash fraction is found to be highly variable, both between the two eruptions and over the course of each eruption, with values of over 80% found on some days. The detection threshold of the AATSR ash flag is also investigated using radiative transfer calculations, allowing the threshold of the IASI flag to be inferred, and these are related to the ash contamination levels.

  20. Aircraft and Volcanic Ash a Key Focus of EGU Meeting

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2010-05-01

    The erupting Eyjafjallajökull volcano in southern Iceland, which has intermittently disrupted European air traffic since 14 April, provided a dramatic backdrop for the recent European Geosciences Union (EGU) General Assembly in Vienna, Austria, about 2700 kilometers to the east. EGU organized several last-minute conference sessions about the eruption, and a number of scientists, including some from Iceland, discussed the latest situation, monitoring and assessment needs, and new guidance about flying through volcanic ash, which volcanologist and incoming EGU president-elect Donald Dingwell of the University of Munich, Germany, called “one of the ugliest cocktails nature throws up.” Although the eruption was small compared with those at Mount St. Helens in 1980 or Mount Pinatubo in 1991, the event produced an estimated 0.1 ± 0.05 cubic kilometer of tephra between 14 and 16 April, according to preliminary numbers from the Institute of Earth Sciences in Reykjavik, Iceland (see the related news item in this issue). An enormous amount of ash from the eruption got lofted into the jet stream toward the United Kingdom and the European mainland. European air traffic controllers, operating under the best guidance and guidelines available at that time—which indicated no flying in ash—shut down European air space to avoid a potential catastrophe if ash clogged up an aircraft's engines.

  1. Future developments in modelling and monitoring of volcanic ash clouds: outcomes from the first IAVCEI-WMO workshop on Ash Dispersal Forecast and Civil Aviation

    NASA Astrophysics Data System (ADS)

    Bonadonna, Costanza; Folch, Arnau; Loughlin, Susan; Puempel, Herbert

    2012-01-01

    As a result of the serious consequences of the 2010 Eyjafjallajökull eruption (Iceland) on civil aviation, 52 volcanologists, meteorologists, atmospheric dispersion modellers and space and ground-based monitoring specialists from 12 different countries (including representatives from 6 Volcanic Ash Advisory Centres and related institutions) gathered to discuss the needs of the ash dispersal modelling community, investigate new data-acquisition strategies (i.e. quantitative measurements and observations) and discuss how to improve communication between the research community and institutions with an operational mandate. Based on a dedicated benchmark exercise and on 3 days of in-depth discussion, recommendations have been made for future model improvements, new strategies of ash cloud forecasting, multidisciplinary data acquisition and more efficient communication between different communities. Issues addressed in the workshop include ash dispersal modelling, uncertainty, ensemble forecasting, combining dispersal models and observations, sensitivity analysis, model variability, data acquisition, pre-eruption forecasting, first simulation and data assimilation, research priorities and new communication strategies to improve information flow and operational routines. As a main conclusion, model developers, meteorologists, volcanologists and stakeholders need to work closely together to develop new and improved strategies for ash dispersal forecasting and, in particular, to: (1) improve the definition of the source term, (2) design models and forecasting strategies that can better characterize uncertainties, (3) explore and identify the best ensemble strategies that can be adapted to ash dispersal forecasting, (4) identify optimized strategies for the combination of models and observations and (5) implement new critical operational strategies.

  2. Validation of ASH Optical Depth and Layer Height from IASI using Earlinet Lidar Data

    NASA Astrophysics Data System (ADS)

    Balis, D.; Siomos, N.; Koukouli, M.; Clarisse, L.; Carboni, E.; Ventress, L.; Grainger, R.; Mona, L.; Pappalardo, G.

    2016-06-01

    The 2010 eruptions of the Icelandic volcano Eyjafjallajökull attracted the attention of the public and the scientific community to the vulnerability of the European airspace to volcanic eruptions. The European Space Agency project "Satellite Monitoring of Ash and Sulphur Dioxide for the mitigation of Aviation Hazards", called for the creation of an optimal End-to-End System for Volcanic Ash Plume Monitoring and Prediction. This system is based on improved and dedicated satellite-derived ash plume and sulphur dioxide level assessments, as well as an extensive validation, using among others ground-based measurements (Koukouli et al., 2014). The validation of volcanic ash levels and height extracted from IASI/MetopA is presented in this work with emphasis on the ash plume height and ash optical depth levels. European Aerosol Research Lidar Network [EARLINET] lidar measurements are compared to different satellite estimates for two eruptive episodes. The validation results are extremely promising within the estimated uncertainties of each of the comparative datasets.

  3. Model-based aviation advice on distal volcanic ash clouds by assimilating aircraft in situ measurements

    NASA Astrophysics Data System (ADS)

    Fu, Guangliang; Heemink, Arnold; Lu, Sha; Segers, Arjo; Weber, Konradin; Lin, Hai-Xiang

    2016-07-01

    The forecast accuracy of distal volcanic ash clouds is important for providing valid aviation advice during volcanic ash eruption. However, because the distal part of volcanic ash plume is far from the volcano, the influence of eruption information on this part becomes rather indirect and uncertain, resulting in inaccurate volcanic ash forecasts in these distal areas. In our approach, we use real-life aircraft in situ observations, measured in the northwestern part of Germany during the 2010 Eyjafjallajökull eruption, in an ensemble-based data assimilation system combined with a volcanic ash transport model to investigate the potential improvement on the forecast accuracy with regard to the distal volcanic ash plume. We show that the error of the analyzed volcanic ash state can be significantly reduced through assimilating real-life in situ measurements. After a continuous assimilation, it is shown that the aviation advice for Germany, the Netherlands and Luxembourg can be significantly improved. We suggest that with suitable aircrafts measuring once per day across the distal volcanic ash plume, the description and prediction of volcanic ash clouds in these areas can be greatly improved.

  4. The European air traffic management response to volcanic ash crises: towards institutionalised aviation crisis management.

    PubMed

    Dopagne, Jacques

    2011-06-01

    A cloud of ash drifting from the erupting Eyjafjallajökull volcano in Iceland in April and May 2010 covered Europe and created an unprecedented situation. It resulted in an almost complete lockdown of European airspace in the period from 15th to 21st April, 2010: more than 100,000 flights were cancelled, 10 million people were affected and over US$1.8bn was lost by airlines globally. This paper presents the air traffic management (ATM) view of the situation. Through an analysis of the evolution of the events in the affected region, the paper will provide more details on ATM planning, reaction and follow-up actions. Furthermore, the influence of this event on the identification of further improvements needed to advance volcanic procedures internationally will be discussed. Actions undertaken since the end of the event - the establishment of the European Aviation Crisis Coordination Cell, running of the International Civil Aviation Organization VOLCEX 11/01 volcanic ash exercise and European response to the Grimsvötn eruption in May 2011 - will be discussed at the end of the paper.

  5. Functional Information: Towards Synthesis of Biosemiotics and Cybernetics.

    PubMed

    Sharov, Alexei A

    2010-04-27

    Biosemiotics and cybernetics are closely related, yet they are separated by the boundary between life and non-life: biosemiotics is focused on living organisms, whereas cybernetics is applied mostly to non-living artificial devices. However, both classes of systems are agents that perform functions necessary for reaching their goals. I propose to shift the focus of biosemiotics from living organisms to agents in general, which all belong to a pragmasphere or functional universe. Agents should be considered in the context of their hierarchy and origin because their semiosis can be inherited or induced by higher-level agents. To preserve and disseminate their functions, agents use functional information - a set of signs that encode and control their functions. It includes stable memory signs, transient messengers, and natural signs. The origin and evolution of functional information is discussed in terms of transitions between vegetative, animal, and social levels of semiosis, defined by Kull. Vegetative semiosis differs substantially from higher levels of semiosis, because signs are recognized and interpreted via direct code-based matching and are not associated with ideal representations of objects. Thus, I consider a separate classification of signs at the vegetative level that includes proto-icons, proto-indexes, and proto-symbols. Animal and social semiosis are based on classification, and modeling of objects, which represent the knowledge of agents about their body (Innenwelt) and environment (Umwelt).

  6. Mafic intrusions triggering eruptions in Iceland

    NASA Astrophysics Data System (ADS)

    Sigmarsson, O.

    2012-04-01

    The last two eruptions in Iceland, Eyjafjallajökull 2010 and Grímsvötn 2011, were both provoked by an intrusion of more mafic magma into pre-existing magmatic system. Injection into the latter volcano, which is located in the main rift-zone of the island, above the presumed centre of the mantle plume and is the most active volcano of Iceland, has been gradual since the last eruption in 2004. In contrast, at Eyjafjallajökull volcano, one of the least active volcano in Iceland and located at the southern part of a propagating rift-zone where extensional tectonics are poorly developed, mafic magma intrusion occurred over less than a year. Beneath Eyjafjallajökull, a silicic intrusion at approximately 6 km depth was recharged with mantle derived alkali basalt that was injected into residual rhyolite from the penultimate eruption in the years 1821-23. The resulting magma mingIing process was highly complex, but careful sampling of tephra during the entire eruption allows the dynamics of the mingling process to be unravelled. Short-lived disequilibria between the gaseous nuclide 210Po and the much less volatile nuclide 210Pb, suggest that basalt accumulated beneath the silicic intrusion over approximately 100 days, or from early January 2010 until the onset of the explosive summit eruption on 14 April. Due to the degassing, crystal fractionation modified the composition of the injected mafic magma producing evolved Fe-and Ti-rich basalt, similar in composition to that of the nearby Katla volcano. This evolved basalt was intruded into the liquid part of the silicic intrusion only a few hours before the onset of the explosive summit eruption. The short time between intrusion and eruption led to the production of very heterogeneous (of basaltic, intermediate and silicic composition) and fine-grained tephra during the first days of explosive eruption. The fine grained tephra resulted from combined effects of magma fragmentation due to degassing of stiff magma rich in

  7. Drone based structural mapping at Holuhraun indicates fault reactivation and complexity

    NASA Astrophysics Data System (ADS)

    Mueller, Daniel; Walter, Thomas R.; Steinke, Bastian; Witt, Tanja; Schoepa, Anne; Duerig, Tobi; Gudmundsson, Magnus T.

    2016-04-01

    Accompanied by an intense seismic swarm in August 2014, a dike laterally formed, starting under Icelands Vatnajökull glacier, propagating over a distance of more than 45 km within only two weeks, leading to the largest eruption by volume since the 1783-84 Laki eruption. Along its propagation path, the dike caused intense surface displacements up to meters. Based on seismicity, GPS and InSAR, the propagation has already been analysed and described as segmented lateral dike growth. We now focus on few smaller regions of the dike. We consider the Terrasar-X tandem digital elevation map and aerial photos and find localized zones where structural fissures formed and curved. At these localized, regions we performed a field campaign in summer 2015, applying the close range remote sensing techniques Structure from Motion (SfM) and Terrestrial Laser Scanning (TLS). Over 4 TLS scan were collected, along with over 5,000 aerial images. Point clouds from SfM and TLS are merged and compared, and local structural lineaments analysed. As a result, we obtained an unprecedentedly high-resolution digital elevation map. With this map, we analyse the structural expression of the fissure eruption at the surface and improve understanding on the conditions that influenced the magma propagation path. We elaborate scenarios that lead to complexities of the surface structures and the link to the underlying dike intrusion.

  8. Simulating atmospheric transport of the 2011 Grímsvötn ash cloud using a data insertion update scheme

    NASA Astrophysics Data System (ADS)

    Wilkins, K. L.; Western, L. M.; Watson, I. M.

    2016-09-01

    Effective modelling of atmospheric volcanic ash dispersion is important to ensure aircraft safety, and has been the subject of much study since the Eyjafjallajökull ash crisis in Europe in 2010. In this paper, a novel modelling method is presented, where the atmospheric transport of the 2011 Grímsvötn ash cloud is simulated using a data insertion update scheme. Output from the volcanic ash transport and dispersion model, NAME, is updated using satellite retrievals and the results of a probabilistic ash, cloud and clear sky classification algorithm. A range of configurations of the scheme are compared with each other, in addition to a simple data insertion method presented in a previous study. Results show that simulations in which ash layer heights and depths are updated using the model output generally perform worse in relation to satellite derived ash coverage and ash column loading than simulations that use satellite-retrieved heights and an assumed layer depth of 1.0 km. Simulated ash column loading and concentration tends to be under-predicted using this update scheme, but the timing of the arrival of the ash cloud at Stockholm is well captured, as shown by comparison with lidar-derived mass concentration profiles. Most of the updated simulations in this comparison make small gains in skill on the simple data insertion scheme.

  9. A summary case report on the health impacts and response to the pakistan floods of 2010.

    PubMed

    Shabir, Omar

    2013-04-11

    In July 2010, Pakistan suffered nationwide floods after unprecedented monsoon rains overwhelmed the Indus basin. The ensuing floods claimed 1985 lives, injured 2946 people and affected over 20.2 million people. Seventy-eight out of 121 districts were affected and at one stage one-fifth of the country's land was inundated with water. Indiscriminate damage was caused to housing, educational and health facilities, communication networks, power plants and grids, irrigation channels, agricultural land and livestock. Over 37 million medical consultations were reported within one year of the floods with acute respiratory infection, skin diseases, acute diarrhoea and suspected malaria forming the most common presentations. Rescue and relief operations were organised through the National Disaster Management Authority and a UN Cluster Approach was adopted for providing humanitarian assistance. The Office for the Coordination of Humanitarian Affairs (OCHA) played a pivotal role in coordinating relief efforts between cluster groups and providing communication platforms for identifying gaps and sharing information. This paper attempts to collate information available in the public domain into a summary report based on key principles described by Kulling et al. (2010) on health crisis reporting.

  10. On the impact of additional spectral bands usage on RST-ASH performance in volcanic ash plume detected from space

    NASA Astrophysics Data System (ADS)

    Falconieri, Alfredo; Filizzola, Carolina; Marchese, Francesco; Pergola, Nicola; Tramutoli, Valerio

    2016-04-01

    RST-ASH is an algorithm developed for detecting and tracking volcanic ash clouds from space based on the Robust Satellite Technique (RST) multi-temporal approach. For the identification of ash affected areas RST-ASH uses two local variation indexes in combination. They analyse the Brightness Temperature Differences (BTD) of the signal measured at 11 μm and 12 μm and at around 3.5 and 11 μm wavelengths to detect ash in both nighttime and daytime conditions. RST-ASH was tested on Advanced Very High Resolution Radiometer (AVHRR) and on Moderate Resolution Imaging Spectroradiometer (MODIS) records and was then implemented on Spinning Enhanced Visible and Infrared Imager (SEVIRI) for studying and monitoring eruptions of different volcanoes. In this study, some experimental configurations of RST-ASH, analyzing signal also in other spectral bands (e.g. VIS, SO2) will be tested and assessed, studying recent ash plumes (e.g. Etna, Eyjafjallajökull, Grímsvötn) affecting different geographic areas. Results achieved using both polar and geostationary satellite data will be evaluated even for comparison with other state of the art methods. The work shows that when the extended spectral capabilities offered by high temporal resolution satellites are exploited an improvement of RST-ASH performance in some observational and plume conditions is achievable, making RST-ASH still more suited for identifying and monitoring ash clouds in the framework of possible operational scenarios.

  11. Tropospheric Volcanism and Air-Traffic

    NASA Astrophysics Data System (ADS)

    Zerefos, C. S.; Kapsomenakis, J.; Amiridis, V.; Solomos, S.; Eleftheratos, K.; Gerasopoulos, E.; Repapis, C.; Eskes, H.; Inness, A.; Cuevas, E.; Hedelt, P.

    2015-12-01

    Volcanic effects and their consequences have been observed in Europe originating either from European (Icelandic, Italy) or from distant large volcanic eruptions (e.g. Kasatochi in the Aleutians and Africa). The interference of the volcanic plumes with air traffic corridors have been noticed and studied thoroughly in the case of 2010 eruptions of Eyafallajökull. There have been similar eruptions that have not interfered with air traffic in the past decade such as the recent Bárðarbunga (September 2014) whose forward trajectories where below 6000m. The present study aims at looking for evidence of columnar SO2 amounts that have followed excursions from Icelandic and volcanic eruptions of importance to Europe in general. Columnar SO2 records from remote sensing spectrophotometers over Europe and from space as well as simulated by models have been compared. The columnar SO2 measurements are also compared with ground based SO2 monitors from the Airbase dataset. Finally the impact of the above mentioned volcanic eruptions in air traffic is assessed. The atmospheric effects when air traffic was shut down seem both inside and outside of major air corridors is studied and compared to both case studies and long-term changes in contrails.

  12. Satellite monitoring of African volcanoes by means of RSTVOLC

    NASA Astrophysics Data System (ADS)

    Pergola, Nicola; Coviello, Irina; Falconieri, Alfredo; Filizzola, Carolina; Lacava, Teodosio; Liuzzi, Mariangela; Marchese, Francesco; Paciello, Rossana; Tramutoli, Valerio

    2015-04-01

    RSTVOLC is an algorithm for volcanic hot spot detection from space based on the Robust Satellite Techniques (RST) multi-temporal approach. This algorithm was firstly tested on Mt. Etna area, analyzing a long-term time series of infrared Advanced Very High Resolution Radiometer (AVHRR) satellite records, and was then implemented on data provided by the Moderate Resolution Imaging Spectroradiometer (MODIS) to study a number of volcanoes in different geographic areas, including Asamayama (Japan) and Eyjafjallajökull (Iceland). Recently, RSTVOLC has been exported on data provided by geostationary sensors such as the Spinning Enhanced Visible and Infrared Imager (SEVIRI), onboard Meteosat Second Generation (MSG) satellites, allowing for the timely detection and real time monitoring of thermal volcanic phenomena. In this work, recent results achieved studying some important African volcanoes by means of polar and geostationary satellite data are presented. Outcomes and results achieved by RSTVOLC studying some past Ol Donyo Lengai (Tanzania) eruptions and the recent Nyamuragira (Congo) activity are reported and discussed, also for comparison with other independent hot spot detection techniques. This study confirms that RSTVOLC may be successfully used to monitor volcanoes at a global scale and to detect low level thermal activities, thanks to its intrinsic self-adaptivity to different observational/environmental conditions as well as to its high sensitivity to sublte hot spots, contributing to volcanic risk mitigation.

  13. Grimsvotn ash plume detection by ground-based elastic Lidar at Dublin Airport on May 2011

    NASA Astrophysics Data System (ADS)

    Lolli, S.; Martucci, G.; O'Dowd, C.; sauvage, L.; Nolan, P.

    2011-12-01

    Volcanic emissions comprising steam, ash, and gases are injected into the atmosphere and produce effects affecting Earth's climate. Volcanic ash is composed of non-spherical mineral and metal (particles spanning a large size range. The largest ones are likely to sediment quickly close to the eruption site. The ash component, and sulphate formed by subsequent oxidation of the SO2 occurring in clouds, poses a variety of hazards to humans and machinery on the ground, as well as damage to the aircrafts which fly through the ash layers. To mitigate such hazards the Irish Aviation Authority (IAA) equipped with an ALS Lidar, produced by LEOSPHERE, deployed at Dublin Airport, which provides real-time range-corrected backscatter signal and depolarization ratio profiles allowing the detection and monitoring of ash plumes. On May, 21st 2011, the Grimsvotn Icelandic volcano erupted, sending a plume of ash, smoke and steam 12 km into the air and causing flights to be disrupted at Iceland's main Keflavik airport and at a number of North European airports. Due to upper level global circulation, the ash plume moved from Iceland towards Ireland and North of Scotland, and was detected a number of times by the ALS Lidar above Dublin Airport between May, 21st and 25th. A preliminary analysis of the detected volcanic plume is presented here as well as a preliminary intercomparison of the microphysical and optical characteristics with the Eyjafjallajökull eruption in 2010.

  14. Probabilistic detection of volcanic ash using a Bayesian approach

    NASA Astrophysics Data System (ADS)

    Mackie, Shona; Watson, Matthew

    2014-03-01

    Airborne volcanic ash can pose a hazard to aviation, agriculture, and both human and animal health. It is therefore important that ash clouds are monitored both day and night, even when they travel far from their source. Infrared satellite data provide perhaps the only means of doing this, and since the hugely expensive ash crisis that followed the 2010 Eyjafjalljökull eruption, much research has been carried out into techniques for discriminating ash in such data and for deriving key properties. Such techniques are generally specific to data from particular sensors, and most approaches result in a binary classification of pixels into "ash" and "ash free" classes with no indication of the classification certainty for individual pixels. Furthermore, almost all operational methods rely on expert-set thresholds to determine what constitutes "ash" and can therefore be criticized for being subjective and dependent on expertise that may not remain with an institution. Very few existing methods exploit available contemporaneous atmospheric data to inform the detection, despite the sensitivity of most techniques to atmospheric parameters. The Bayesian method proposed here does exploit such data and gives a probabilistic, physically based classification. We provide an example of the method's implementation for a scene containing both land and sea observations, and a large area of desert dust (often misidentified as ash by other methods). The technique has already been successfully applied to other detection problems in remote sensing, and this work shows that it will be a useful and effective tool for ash detection.

  15. Iceland Dust Storms Linked to Glacial Outwash Deposits and to Sub-Glacial Flood (Jökulhlaup) Events

    NASA Astrophysics Data System (ADS)

    Prospero, J. M.; Arnalds, Ó.; Olafsson, H.; Bullard, J.; Hodgkins, R.

    2008-12-01

    two major glaciers, Mýrdalsjökull and Vatnajökull, the latter being the largest glacier in Europe. In our presentation we review the Iceland dust aerosol data and show the relationship to these six satellite- captured dust outbreaks along with other environmental data associated with these events. We point out that the synoptic events associated with these dust outbreaks could carry dust into the high latitudes and to Europe. We also note that glaciers on Iceland have been retreating in recent decades and that this trend is expected to continue with changing climate. Thus dust activity from newly-exposed glacial deposits will most likely increase in the future on Iceland and possibly from other glacial terrains in the Arctic.

  16. Small volcanic eruptions and the stratospheric sulfate aerosol burden

    NASA Astrophysics Data System (ADS)

    Pyle, David M.

    2012-09-01

    (Rampino and Self 1984, Pyle et al 1996, Self and Rampino 2012). But as yet, there is little evidence for the consequences of this scale of eruption for the climate system (Miles et al 2004), and few data against which to test simulations of stratospheric sulfur-injection 'geoengineering' scenarios of a similar scale and frequency (e.g. English et al 2012). A hint of the new volcano-observing capability came during the eruption of Eyjafjallajökull, Iceland. For a few days in April 2010 meteorological conditions, coupled with a dramatic increase in volcanic ash production, led to the wide dispersal of fine volcanic particles across northern Europe; an event which was widely tracked by ground-based and satellite-borne instruments, augmented by in situ measurements from balloons and aircraft (Bennett et al 2010, Flentje et al 2010, Harrison et al 2010, Stohl et al 2011). Despite the interest in Eyjafjallajökull at the time, this was, geologically, only a very modest eruption with limited sulfur emissions and an impact restricted mainly to the regional troposphere (e.g. Thomas and Prata 2011, Walker et al 2012). Then, in June 2011, a previously dormant volcano in north-east Africa began to erupt violently. Little is known about Nabro, which is a partially collapsed volcano that straddles the Eritrea-Ethiopia border, and has had no known historical activity (Wiart and Oppenheimer 2005). Despite the remote location, and lack of prior warning, the event and its aftermath were remarkably well captured by remote-sensing instruments, as demonstrated in the new letter by Sawamura et al (2012). Using both ground-based and satellite-borne laser-ranging (lidar) data, Sawamura et al (2012) were able to extract detailed information about the nature of the volcanic aerosol layer, and its spread around the globe. The eruption started strongly, with substantial ash plumes for the first 48 h, rising to 9-14 km altitude (Smithsonian Institution 2011, Bourassa et al 2012), that carried at

  17. The future of volcanic ash-aircraft interactions from technical and policy perspectives

    NASA Astrophysics Data System (ADS)

    Casadevall, T. J.; Guffanti, M.

    2010-12-01

    Since the advent of jet-powered flight in the 1960s, the threat of volcanic ash to aviation operations has become widely recognized and the mitigation of this threat has received concerted international attention. At the same time the susceptibility to operational disruption has grown. Technical improvements to airframes, engines, and avionic systems have been made in response to the need for improved fuel efficiency and the demand for increased capacity for passenger and freight traffic. Operational demands have resulted in the growth of extended overseas flight operations (ETOPS), increased flight frequency on air traffic routes, and closer spacing of aircraft on heavily traveled routes. The net result has been great advances in flight efficiency, but also increased susceptibility to flight disruption, especially in heavily traveled regions such as North Atlantic-Europe, North America, and the North Pacific. Advances in ash avoidance procedures, pilot and air manager training, and in detection of ash-related damage and maintenance of aircraft and engines have been spurred by noteworthy eruptions such as Galunggung, Indonesia, 1982; Redoubt, Alaska, 1989-1990; and Pinatubo, Philippines, 1991. Comparable advances have been made in the detection and tracking of volcanic ash clouds using satellite-based remote sensing and numerical trajectory forecast models. Following the April 2010 eruption of Eyjafjallajökull volcano, Iceland, the global aviation community again focused attention on the issue of safe air operations in airspace affected by volcanic ash. The enormous global disruption to air traffic in the weeks after the Eyjafjallajökull eruption has placed added emphasis for the global air traffic management system as well as on the equipment manufacturers to reevaluate air operations in ash-affected airspace. Under the leadership of the International Civil Aviation Organization and the World Meteorological Organization, efforts are being made to address this

  18. European collaboration for improved monitoring of Icelandic volcanoes: Status of the FUTUREVOLC project after the initial 18 months

    NASA Astrophysics Data System (ADS)

    Dumont, Stéphanie; Parks, Michelle; Sigmundsson, Freysteinn; Vogfjörð, Kristín; Einarsdóttir, Heiðveig Maria; Tumi Gudmundsson, Magnús; Kristinsson, Ingvar; Loughlin, Sue; Ilyinskaya, Evgenia; Hooper, Andrew; Kylling, Arve; Witham, Claire; Bean, Chris; Braiden, Aoife; Ripepe, Maurizio; Prata, Fred; Pétur Heiðarsson, Einar; Other Members Of The Futurevolc Team

    2014-05-01

    The FUTUREVOLC project funded by the European Union (FP7) is devoted to volcanic hazard assessment and establishing an integrated volcanological monitoring procedure through a European collaboration. To reach these objectives the project combines broad expertise from 26 partners from 10 countries, focusing on the four most active volcanoes of Iceland: Grímsvötn, Katla, Hekla and Bárdarbunga. The geological setting of Iceland, the high rate of eruptions and the various eruption styles make this country an optimal natural laboratory to study volcanic processes from crustal depths to the atmosphere. The project, which began on 1 October 2012, integrates advanced monitoring and analytical techniques in an innovative way, focusing on (i) detailed monitoring to improve our understanding of the seismic/magmatic unrest, in order to estimate the amount of magma available for an eruption and to provide early warnings (ii) the dynamics of magma in the conduit and a near real time estimation of the mass eruption rate and (iii) observing and modelling the plume dynamics. The project design considers effective collaboration between partners and aims for efficient cross-disciplinary workflows. A major step during the first 18 months of the project was the installation of additional equipment in the volcanic regions of Iceland to reinforce and complement the existing monitoring. The instruments include: seismometers, GPS stations, MultigGAS detectors, DOAS, infrasonic arrays, electric field sensors, radars, and optical particle sizers. Data streaming is designed to withstand extreme weather conditions. The FUTUREVOLC project has an open data policy for real and near-time data. Implementation of a data hub is currently under way, based on open access to data from the 2010 Eyjafjallajökull eruption. Access to volcano monitoring data through a common interface will allow timely information on magma movements facilitated through combined analysis. A key part of the project is to

  19. Monitoring of jökulhlaups and element fluxes in proglacial Icelandic rivers using osmotic samplers

    NASA Astrophysics Data System (ADS)

    Jones, Morgan T.; Gałeczka, Iwona M.; Gkritzalis-Papadopoulos, Athanasios; Palmer, Martin R.; Mowlem, Matthew C.; Vogfjörð, Kristín; Jónsson, Þorsteinn; Gislason, Sigurður R.

    2015-01-01

    The quantification of volatile emissions from volcanoes is an integral part of understanding magmatic systems, with the exsolution and extent of volcanic degassing having a large impact on the nature of an eruption. Measurements of volatiles have traditionally focused on gas emissions into the atmosphere, but volatiles can also become dissolved in proximal water bodies en route to the surface. Thus the monitoring of rivers draining active volcanic areas can provide insights to identifying changes in activity. This process is particularly important for sub-glacial volcanoes in Iceland, where much of the volatile release is transported within glacial outbreak floods, termed jökulhlaups. Monitoring and characterising these phenomena is hampered by the dependence on spot sampling of stochastic events under challenging field conditions, which often leads to bias in the collected data. A recent technological advance is the osmotic sampler, an electricity-free pump that continuously collects water that can subsequently be divided into time-averaged samples. This technique allows for continued and unsupervised deployment of a sampler for weeks to months, representing a cost-efficient form of chemical monitoring. In this study we deployed osmotic samplers in two rivers in southern Iceland. Skálm is a proglacial river from Mýrdalsjökull glacier and Katla volcano, while Skaftá is a larger drainage system from the western part of Vatnajökull glacier. Both rivers are prone to jökulhlaups from geothermal and volcanic sources, and a small jökulhlaup of geothermal origin occurred during the second deployment in Skaftá in January 2014. The two deployments show that osmotic samplers are capable of delivering accurate chemical data in turbulent conditions for several key elements. Total dissolved fluxes for the deployment at Skaftá are calculated to be Na = 9.9 tonnes/day, Mg = 10.5 t/d, Si = 34.7 t/d, Cl = 11.0 t/d, Ca = 31.6 t/d, DIC = 50.8 t/d, and SO4 = 28.3 t/d, with

  20. Unrest at Bárdarbunga: Preparations for possible flooding due to subglacial volcanism

    NASA Astrophysics Data System (ADS)

    Hardardottir, Jorunn; Roberts, Matthew; Pagneux, Emmanuel; Einarsson, Bergur; Thorarinsdottir, Tinna; Johannesson, Tomas; Sigurdsson, Oddur; Egilson, David; Sigurdsson, Gunnar; Imo hydrological-monitoring-team

    2015-04-01

    Located partly beneath northwest Vatnajökull, Iceland, the Bárdarbunga volcanic system comprises an ice-capped central volcano and a fissure swarm extending beyond the ice margin. During the last 1100 years the volcano has erupted on at least 26 occasions. Outburst floods (jökulhlaups) on a scale of >100,000 m3 s-1 are known to have occurred during major explosive eruptions. Repeated jökulhlaups from Bárdarbunga have inundated the Jökulsá á Fjöllum River, which drains over 200 km northwards from the Dyngjujökull outlet glacier to the north coast of Iceland. Depending on the location of the eruption within the 80 km2 caldera, jökulhlaups could also flow northwards along Skjálfandafljót River and towards west and southwest into present-day tributaries of the extensively hydropower-harnessed Thjórsá River. On 16 August 2014, an intense earthquake swarm began within the Bárdarbunga caldera. Seismicity propagated from the caldera, extending ~10 km northwards of the ice margin where a fissure eruption developed in late August and remains ongoing in early January 2015. In connection with the lateral migration of magma from the caldera, the ice surface of Bárdarbunga has lowered by over 60 m; also associated with increased geothermal heat on the caldera rim, as manifested by the development of ice-surface depressions. In preparation for a subglacial eruption in the Bárdarbunga volcanic system, the Icelandic Meteorological Office (IMO) has made several assessments of likely hydrological hazards. Assessments were undertaken on Jökulsá á Fjöllum and Skjálfandafljót at key locations where preliminary evacuation plans for populated areas were made in cooperation with the local police. Floodwater extent was estimated for key infrastructures, such as bridges, telecommunication and power lines for maximum discharge levels ranging from 3,000 to 20,000 m3 s-1. The estimations were made using either simple Manning's calculations or HEC-RAS modelling

  1. Deformation derived from GPS geodesy associated with Bárðarbunga 2014 rifting event in Iceland

    NASA Astrophysics Data System (ADS)

    Ofeigsson, Benedikt Gunnar; Hreinsdóttir, Sigrún; Sigmundsson, Freysteinn; Friðriksdóttir, Hildur; Parks, Michelle; Dumont, Stephanie; Árnadóttir, Þóra; Geirsson, Halldór; Hooper, Andrew; Roberts, Matthew; Bennett, Rick; Sturkell, Erik; Jónsson, Sigurjón; Lafemina, Peter; Jónsson, Þorsteinn; Bergsson, Bergur; Kjartansson, Vilhjálmur; Steinþórsson, Sveinbjörn; Einarsson, Páll; Drouin, Vincent

    2015-04-01

    On August 16, 2014 an intense seismic swarm started below the eastern part of Bárðarbunga Caldera in the north-western corner of Vatnajökull ice-cap, Iceland, marking the onset of the first rifting event in Iceland since the Krafla fires (1975-1984). The migration of the seismicity was corroborated by ground deformation in areas outside the ice cap and on nunataks within the ice cap suggesting a lateral propagation of magma, from the Bárðabunga system. The sesimicity migrated out of the caldera forming a dyke with roughly three segments, changing direction each time until August 28 when the migration stopped around 10 km south of Askja Volcano, eventually leading to a short lived eruption in Holuhraun north of Dyngjujökull. A second fissure eruption started in Holuhraun on August 31 which is still ongoing at the time of this writing. In the months prior to the onset of the activity, subtle signs of inflation where observed on continuous GPS sites around the Bárðarbunga indicating a volume increase in the roots of the volcanic system. When the activity started on August 16, the deformation pattern indicated a simultaneous deflation centered within the caldera and a lateral growth of a dyke also reflected in the migration of seismicity along segments of variable strike. A maximum widening of 1.3 m occurred between stations on opposite sides of the dyke spaced 25 km apart. Significant movements where detected on GPS site more then 80 km away from the tip of dyke. Displacements indicated the fastest rate of widening at any time in the most distal segment of the dyke throughout its evolution. After the dyke stopped propagating, the inflation continued, decaying exponentialy with time. On September 4, five days into the second fissure eruption, the movements associated with the dyke where no longer significant. As the fissure eruption continues, a slowly decaying contraction is observed around the Bárðarbunga central volcano, both shown in the piston like

  2. The Effects of Volcano-Induced Ozone Depletion on Short-lived Climate Forcing in the Arctic

    NASA Astrophysics Data System (ADS)

    Ward, P. L.

    2012-12-01

    Photodissociation of oxygen maintains the stratopause ~50°C warmer than the tropopause. Photodissociation of ozone warms the lower stratosphere, preventing most of this high-energy DNA-damaging solar radiation from reaching the troposphere. Ozone depletion allows more UV energy to reach the lower troposphere causing photodissociation of anthropogenic ozone and nitrogen dioxide. UV energy also penetrates the ocean >10 m where it is absorbed more efficiently than infrared radiation that barely penetrates the surface. Manmade chlorofluorocarbons caused ozone depletion from 1965 to 1994 with slow recovery predicted over the next 50+ years. But the lowest levels of ozone followed the eruptions of Pinatubo (1991 VEI=6), Eyjafjallajökull (2010 VEI=4), and Grímsvötn (2011 VEI=4). Each of the relatively small, basaltic eruptions in Iceland caused more ozone depletion than the long-term effects of chlorofluorocarbons, although total ozone appears to return to pre-eruption levels within a decade. Ozone depletion by 20% increases energy flux thru the lowermost troposphere by 0.7 W m-2 for overhead sun causing temperatures in the lower stratosphere to drop >2°C since 1958 in steps after the 3 largest volcanic eruptions: Agung 1963, El Chichón 1982, and Pinatubo. Temperatures at the surface increased primarily in the regions and at the times of the greatest observed ozone depletion. The greatest warming observed was along the Western Antarctic Peninsula (65.4°S) where minimum temperatures rose 6.7°C from 1951 to 2003 while maximum temperatures remained relatively constant. Minimum total column ozone in September-October was 40-56% lower than in 1972 almost every year since 1987, strongly anti-correlated with observed minimum temperatures. Sea ice decreased 10%, 7 ice shelves separated, 87% of the glaciers retreated and the Antarctic Circumpolar Current warmed. Elsewhere under the ozone hole, warming of continental Antarctica was limited by the high albedo (0.86) of

  3. Formation of minor moraines in high-mountain environments independent of a primary climatic driver

    NASA Astrophysics Data System (ADS)

    Wyshnytzky, Cianna; Lukas, Sven

    2016-04-01

    compelling discrepancy requires further investigation. References Beedle, M.J., Menounos, B., Luckman, B.H., and Wheate, R., 2009, Annual push moraines as climate proxy: Geophysical Research Letters, v. 36, no. 20, p. L20501, doi: 10.1029/2009GL039533. Boulton, G.S., 1986, Push-moraines and glacier-contact fans in marine and terrestrial environments: Sedimentology, v. 33, p. 677-698. Bradwell, T., 2004, Annual Moraines and Summer Temperatures at Lambatungnajökull, Iceland: Arctice, Antarctic, and Alpine Research, v. 36, no. 4, p. 502-508. Hewitt, K., 1967, Ice-Front Deposition and the Seasonal Effect: A Himalayan Example: Transactions of the Institute of British Geographers, v. 42, p. 93-106. Lukas, S., 2012, Processes of annual moraine formation at a temperate alpine valley glacier: insights into glacier dynamics and climatic controls: Boreas, v. 41, no. 3, p. 463-480, doi: 10.1111/j.1502-3885.2011.00241.x. Ono, Y., 1985, Recent Fluctuations of the Yala (Dakpatsen) Glacier, Langtang Himal, Reconstructed From Annual Moraine Ridges: Zeitschrift für Gletscherkunde und Glazialgeologie, v. 21, p. 251-258. Sharp, M., 1984, Annual moraine ridges at Skálafellsjökull, south-east Iceland: Journal of Glaciology, v. 30, no. 104, p. 82-93.

  4. Extending permanent volcano monitoring networks into Iceland's ice caps

    NASA Astrophysics Data System (ADS)

    Vogfjörd, Kristín S.; Bergsson, Bergur H.; Kjartansson, Vilhjálmur; Jónsson, Thorsteinn; Ófeigsson, Benedikt G.; Roberts, Matthew J.; Jóhannesson, Tómas; Pálsson, Finnur; Magnússon, Eyjólfur; Erlendsson, Pálmi; Ingvarsson, Thorgils; Pálssson, Sighvatur K.

    2015-04-01

    The goals of the FUTUREVOLC project are the establishment of a volcano Supersite in Iceland to enable access to volcanological data from the country's many volcanoes and the development of a multiparametric volcano monitoring and early warning system. However, the location of some of Iceland's most active volcanoes inside the country's largest ice cap, Vatnajökull, makes these goals difficult to achieve as it hinders access and proper monitoring of seismic and deformation signals from the volcanoes. To overcome these obstacles, one of the developments in the project involves experimenting with extending the permanent real-time networks into the ice cap, including installation of stations in the glacier ice. At the onset of the project, only one permanent seismic and GPS site existed within Vatnajökull, on the caldera rim of the Grímsvötn volcano. Two years into the project both seismic and GPS stations have been successfully installed and operated inside the glacier; on rock outcrops as well as on the glacier surface. The specific problems to overcome are (i) harsh weather conditions requiring sturdy and resilient equipment and site installations, (ii) darkness during winter months shutting down power generation for several weeks, (iii) high snow accumulation burying the instruments, solar panels and communication and GPS antennae, and in some locations (iv) extreme icing conditions blocking transmission signals and connection to GPS satellites, as well as excluding the possibility of power generation by wind generators. In 2013, two permanent seismic stations and one GPS station were installed on rock outcrops within the ice cap in locations with 3G connections and powered by solar panels and enough battery storage to sustain operation during the darkest winter months. These sites have successfully operated for over a year with mostly regular maintenance requirements, transmitting data in real-time to IMO for analysis. Preparations for two permanent seismic

  5. Morpho-Sedimentary Impacts By The Late-Pleistocene - Holocene Jökulhlaups In The Þjórsá-Tungnaá Fluvio-Glacial System

    NASA Astrophysics Data System (ADS)

    Schneider, Jean Luc; van Vliet-Lanoe, Brigitte; Naaim, Mohamed; Salles, Tristan; Bjornsson, Helgi; Palsson, Finnur

    2013-04-01

    In Iceland, jökulhlaups correspond to glacial outburst floods that are generally related to sublagial volcanic and hydrothermal activities. They affect the main fluvial outwash plains around the ice caps. They result of the sudden outflow of a large volume of melt water with variable sediment charges drained from a (sub)glacial or an ice-dammed marginal lake that feeds short (hours to days) cataclysmic floods with peak discharges (103 to 107 m3.s-1), up to 10-100 times the magnitude of classical hydrometeorological fluvial floods. Despite their short duration, and because of large peak discharges, they have important erosive and sediment transport capacities. Consequently, repeated events have a strong morpho-sedimentary impact on the inundated areas. The connected watersheds of the Þjórsá and Tungnaá rivers (200 km long; ˜5000 km2, South Island), west of Vatnajökull, correspond to the largest periglacial fluvial system in Iceland. It has drained numerous jökulhlaup floods during the Late Pleistocene deglaciation and the Holocene during periods of increase of the volcanic activity and heat flow. Jökulhlaups were emitted from at least two outlets along the western edge of Vatnajökull that fed the Kaldakvísl and Tungnaá rivers. The subglacial depressions (calderas) of the Bárðarbunga-Hamarinn volcanic system are favorable to the storage of large volumes of water that can feed major jökulhlaups. The Þjórsá-Tungnaá jökulhlaup system can be subdivided into three parts: (1) the source located at the outlets of the subglacial hydraulic network, (2) a proximal transit zone along which erosional processes are dominant (erosively incised rocky substratum - scablands, abraded scoria cones, scour structures, residual buttes of the sedimentary cover) with minor lateral slackwater deposits, flood overflow ponded lakes, and hydraulic dunes along constrictions of the fluvial network, and (3) a distal depositional zone that corresponds to the coastal sandur, the

  6. The chemistry and element fluxes of the July 2011 Múlakvísl and Kaldakvísl glacial floods, Iceland

    NASA Astrophysics Data System (ADS)

    Galeczka, Iwona; Oelkers, Eric H.; Gislason, Sigurdur R.

    2014-05-01

    The glacial floods, called 'jökulhlaups', are common in Iceland and are of interest to geologists for several reasons. Firstly, the heat source origin - subglacial volcanic eruption or/and subglacial geothermal activity - determines the potential environmental impact of the floods. For example, if the heat was sourced by a volcanic eruption, acid gas input might lead to acidic flood waters and toxic metal release from the host rock. In contrast, geothermal heat melts the ice slowly allowing long-term fluid-rock interaction to neutralize the flood waters, limiting their toxicity. The chemical composition of the flood waters is often the only indicator of the flood triggering mechanism in volcanic and geothermal areas. As such river water chemistry monitoring might be an effective method to predict an upcoming volcanic eruption. Secondly, glacial floods may play an important role in global cycle of elements. Due to high discharge during the events, flood waters can transport large amounts of particulate material. This particulate material has large surface areas, making it especially reactive once it arrives in estuaries. Slow dissolution of particulate material releases micro- and macronutrients which could enhance primary productivity along the coast and in lakes. In July 2011, two ~2000 m3/s glacial floods from the Icelandic Mördalsjökull and Vatnajökull glaciers emerged into the Múlakvísl and Kaldakvísl rivers, respectively. Water samples collected during both floods had neutral to alkaline pH and conductivity from 100 to 900 μS/cm. The total dissolved inorganic carbon (DIC), present mostly as HCO3-, was ~9 mmol/kg during the flood peak in the Múlakvísl river but stabilized at around 1 mmol/kg; a similar trend was observed in the Kaldakvísl river. Concentrations of most dissolved elements in the flood waters were comparable to those commonly observed in these rivers. The concentration of suspended particulate material however, increased dramatically

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  8. Surface fracturing and graben subsidence during the 2014 Bárdarbunga dike intrusion in Iceland

    NASA Astrophysics Data System (ADS)

    Rut Hjartardóttir, Ásta; Einarsson, Páll; Tumi Gudmundsson, Magnús; Högnadóttir, Thordís

    2015-04-01

    A dike propagated laterally away from the Bárdarbunga central volcano in August 2014. The dike propagated about 48 km towards the northeast and north-northeast, mostly beneath the Vatnajökull glacier. However, the farthest 8 km of the dike were located north of the glacier, where the ice-free area allowed surface fractures and graben subsidence to be observed. This dike intrusion was accompanied by eruptions, the most prominent ones occurring within the graben at the distal end of the dike. In this study, photographs taken from airplanes were rectified by using the ArcGIS software. This was done in order to map the fractures and eruptive fissures which were formed or reactivated during this dike intrusion, and to show the temporal evolution of the fracture pattern. Ground deformation across the graben was measured from an airplane with a radar altimeter and kinematic GPS. The propagation of the dike was shown by laterally propagating earthquakes and by ground deformation recorded by GPS geodetic network. Three days after the dike had propagated north of the Vatnajökull glacier, new and reactivated fractures were detected in this area, above the dike. The fractures delineated two grabens in direct continuation of each other. The southern graben extended 5 km northwards from the glacier boundary, and was 700-1000 m wide. Before the eruptions, the northern graben was seen ~6.6-7.5 km north of the glacier, and was only 250-450 m wide. Two days later, on the 29th of August, a four-hour long eruption took place on a 600 m long eruptive fissure 6 km north of the glacier. Then, the narrow northern graben was seen extending about 1-1.6 km farther to the south than before the eruption, with the new eruptive fissure in the middle of it. The eruption resumed again two days later, extending the same eruptive fissure towards the south and north, to a total of ~1900 m length. This eruption is still ongoing (in January 2014). On the 5th of September, three short (~100 to 250 m

  9. Deformation monitoring of the 2014 dyke intrusion and eruption within the Bárðarbunga volcanic system, and associated stress triggering at neighbouring volcanoes

    NASA Astrophysics Data System (ADS)

    Parks, Michelle; Árnadóttir, Thóra; Dumont, Stéphanie; Sigmundsson, Freysteinn; Hooper, Andrew; Drouin, Vincent; Ófeigsson, Benedikt; María Friðriksdóttir, Hildur; Hreinsdóttir, Sigrún; Rafn Heimisson, Elías; Vogfjörd, Kristín; Jónsdóttir, Kristín; Hensch, Martin; Guðmundsson, Gunnar; Magnússon, Eyjólfur; Einarsson, Páll; Rut Hjartardóttir, Ásta; Pedersen, Rikke

    2015-04-01

    The recent unrest and activity within the Bárðarbunga volcanic system, Iceland was initially identified by the onset of an intense earthquake swarm on the 16th August 2014 and concurrent movement registered at several nearby continuous GPS (cGPS) sites. Over the following weeks additional cGPS stations were installed, campaign sites were reoccupied and interferograms formed using X-band satellite images. Data were analysed in near real-time and used to map ground displacements associated with the initial dyke emplacement and propagation (NE of Bárðarbunga), responsible for the sudden unrest. On the 29th August 2014, a small fissure opened up just a few kilometers to the north of the Vatnajökull ice cap, at Holuhraun. The eruption lasted only a few hours, but was followed on 31st August by the onset of a fissure eruption, characterised by lava fountaining and the extrusion of extensive lava flows. The eruption continues at the time of writing (January 2015). We demonstrate how Interferometric Synthetic Aperture Radar (InSAR) analysis, in conjunction with GPS measurements and earthquake seismicity, has been instrumental in the continued monitoring of Bárðarbunga volcanic system since the onset of unrest. We also investigate how changes in the local stress field induced by the dyke intrusion and concurrent magma withdrawal may trigger seismicity and potentially renewed activity at neighbouring volcanoes. InSAR analysis has systematically been used throughout the eruption to monitor co-eruptive displacement in the vicinity of both the dyke and the eruption site, along with major co-eruptive subsidence occurring beneath the Bárðarbunga caldera - the latter is believed to have commenced shortly after the onset of the unrest and is associated with magma withdrawal beneath the central volcano, feeding the dyke and the ongoing eruption. We use Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) techniques to generate a time series of

  10. Earth rheology in Iceland: new constraints from InSAR observations and models of crustal deformation induced by glacial surge and GIA

    NASA Astrophysics Data System (ADS)

    Auriac, Amandine; Sigmundsson, Freysteinn; Hooper, Andy; Spaans, Karsten; Björnsson, Helgi; Pálsson, Finnur; Pinel, Virginie; Feigl, Kurt L.

    2014-05-01

    About 11% of Iceland is covered by glaciers. The largest ice cap, Vatnajökull, has an area of ~8100 km² with an average ice thickness of ~380 m. Climate changes since the late 19th century has induced significant ice loss at Icelandic glaciers, resulting in a broad Glacial Isostatic Adjustment (GIA) uplift signal in the country. Furthermore, many of the major outlets from Icelandic ice caps are known to surge with a quiescent period of a few to up to ~10 decades. During a surge (lasting only a few months) large quantities of ice are transported to the glacier and terminal region from the interior zone of the ice caps. Due to this large scale mass transport, a surge implies a local crustal subsidence. In 1993 to 1995, the major outlets from SW-Vatnajökull surged. Deformation due both to GIA and the surges was observed and used to infer the properties of the crust and mantle beneath Iceland through modelling. Interferometric Synthetic Aperture Radar (InSAR) data from 1992-2002, providing high resolution ground observations, were used to measure the GIA uplift and surge-induced subsidence with mm to cm accuracy. InSAR time series and velocity estimates reveal a GIA signal of up to 25-28 mm/yr close to the ice cap. We disentangled the near instantaneous surge-induced crustal signal from the long-term GIA by inverting for a step function at the time of the surge, superimposed on the assumed linear GIA deformation rate. This yielded a surge-induced deformation signal reaching up to 75 mm at the ice edge. Finite element modelling is performed to reproduce each signal and infer some of the Earth properties. Each model is compared to the observations and a probability distribution of our free parameters is obtained using a Bayesian approach. For the surge-induced deformation, we use elastic modelling with one or two elastic layers and a digital map of the ice mass distribution after the surge, created from surface elevation measurements and glacier surface DEMs prior to

  11. Density analysis of magmatic and phreatomagmatic phases of the 934 AD Eldgjá Eruption, southern Iceland

    NASA Astrophysics Data System (ADS)

    Moreland, William; Thordarson, Thorvaldur

    2014-05-01

    Eldgjá is a ~75 km long volcanic fissure vent system associated with the Katla volcanic system in southern Iceland, formed during an eruption in the mid-tenth century. The fissure is of the mixed-cone row type and produced both large lava fields and a widespread basaltic tephra deposit. Proximal tephra fall deposits are up to 4 m thick and contain numerous fall units of varying thickness which run parallel to the fissure, indicating many sources of eruption. The lower-most fall units thicken towards Mýrdalsjökull, demonstrating that the initial explosive phases took place within the glacier. Later fall units generally thicken towards the northeast with dispersal axes indicating origin at the more easterly segments of the Eldgjá vent system and a stepwise migration in an easterly direction. Both magmatic and phreatomagmatic explosive activity occurred along the vent system, where phreatomagmatic activity is confined to fissure segments within the Mýrdalsjökull glacier. Two key sections, chosen to represent magmatic and phreatomagmatic deposits, were logged and sampled for density analysis. A section at Skælingar, half a kilometre southeast of Eldgjá Proper was chosen to represent the magmatic products. It is 3.70 m thick and contains 9 fall-units including a distinct bomb-layer. The phreatomagmatic products are represented by a section from Stóragil, 20 km north-northeast of the Katla caldera and the sampled section is 1.12 m thick. Density analysis involves selecting 100 clasts 8-32 mm in diameter from <5 cm layers within the sub-units of each section. These clasts are then weighed, sealed and then weighed again in water to calculate their volume by Archimedes' principle and therefore their density, from which vesicularity can be calculated. The results were then plotted as histograms and compared with the section logs. The magmatic samples have unimodal, normal vesicularity distributions with typical modal values of 60-70% and a span of ~40%. Several of

  12. Estimation of volcanic ash emission profiles using ceilometer measurements and transport models

    NASA Astrophysics Data System (ADS)

    Chan, Ka Lok; Geiß, Alexander; Gasteiger, Josef; Wagner, Frank; Wiegner, Matthias

    2016-04-01

    In recent years, the number of active remote sensing systems grows rapidly, since several national weather services initiated ceilometer networks. These networks are excellent tools to monitor the dispersion of volcanic ash clouds and to validate chemical transport models. Moreover, it is expected that the can be used to refine model calculations to better predict situations that might be dangerous for aviation. As a ceilometer can be considered as a simple single-wavelength backscatter lidar, quantitative aerosol profile information, i.e., the aerosol backscatter coefficient (βp) profile, can be derived provided that the ceilometer is calibrated. Volcanic ash concentration profile can then be estimated by using prior optical properties of volcanic ash. These profiles are then used for the inverse calculation of the emission profile of the volcanic eruption, thus, improving one of the most critical parameters of the numerical simulation. In this study, the Lagrangian particle dispersion model FLEXPART (FLEXible PARTicle dispersion model) is used to simulate the dispersion of volcanic ash. We simulate the distribution of ash for a given time/height grid, in order to compute the sensitivity functions for each measurements. As an example we use ceilometer measurements of the German weather service to reconstruct the temporal and spatial emission profile of Eyjafjallajökull eruption in April 2010. We have also examined the sensitivity of the retrieved emission profiles to different measurement parameters, e.g., geolocation of the measurement sites, total number of measurement sites, temporal and vertical resolution of the measurements, etc. The first results show that ceilometer measurements in principle are feasible for the inversion of volcanic ash emission profiles.

  13. Circulation, chemistry, and biology of the subglacial lake beneath the Skaftárkatlar cauldron, Iceland

    NASA Astrophysics Data System (ADS)

    Gaidos, E.; Thorsteinsson, T.; Glazer, B.; Jóhannessen, T.; Skidmore, M.; Stefansson, A.; Elefsen, S.; Lanoil, B.; Marteinsson, V.; Einarsson, B.; Kjartansson, V.; Gíslason, S.; de Camargo, L.; Kristjánsson, J.; Miller, M.; Roberts, M. J.; Sigurdsson, G. J.; Sigurdsson, O.

    2006-12-01

    We used sterile hotwater drilling to penetrate 300~m of glacial ice and sample the volcanic lake beneath the western Skaftárkatlar cauldron on the Vatnajökull ice cap. The depth (115~m) and temperature profile of the lake were determined by pressure and temperature probes. Temperatures at the ice-water interface and throughout the upper water column were 4.6°C, falling to 3.4°C within a 30 m-thick layer near the bottom and rising again to ≥ 4°C within 1~m of the bottom. A sample obtained 2~m above the bottom using a specialized gas-tight bailer was anoxic and had a pH of 5.3, 1~mM HS-1 and >10~mM CO2. These and other dissolved species indicate significant hydrothermal input. Direct cell counts averaged 5× 105~ml-1, far higher than blanks or control samples of snow, ice, or drilling water. The inverted temperature profile suggests point-source heating and melting of basal glacial ice by hydrothermal plumes, and sinking of the melt water once its density exceeds the underlying water column. This indicates large-scale circulation and complete anoxia of the lake. The lake redox state is determined by the relative input of O2 via glacial meltwater and reaction with reduced volcanogenic compounds, i.e., HS-1 and Fe2+. Our findings suggests low input of external oxygenated waters, high rates of HS-1 production by SO2 disproportionation, and/or weathering of glassy basalts. The simultaneous presence of H2 and CH4 indicates the occurence of methanogenesis, an important anaerobic metabolism. Any redoxocline must occur near or at the ice-water interface where it may support metabolisms based on the oxidation of reduced sulfur compounds. We will discuss these and biomolecular-based results.

  14. Radar volcano monitoring system in Iceland

    NASA Astrophysics Data System (ADS)

    Arason, Þórður; Yeo, Richard F.; Sigurðsson, Geirfinnur S.; Pálmason, Bolli; von Löwis, Sibylle; Nína Petersen, Guðrún; Bjornsson, Halldór

    2013-04-01

    Weather radars are valuable instruments in monitoring explosive volcanic eruptions. Temporal variations in the eruption strength can be monitored as well as variations in plume and ash dispersal. Strength of the reflected radar signal of a volcanic plume is related to water content and droplet sizes as well as type, shape, amount and the grain size distribution of ash. The Icelandic Meteorological Office (IMO) owns and operates three radars and one more is planned for this radar volcano monitoring system. A fixed position 250 kW C-band weather radar was installed in 1991 in SW-Iceland close to Keflavík International Airport, and upgraded to a doppler radar in 2010. In cooperation with the International Civil Aviation Organization (ICAO), IMO has recently invested in two mobile X-band radars and one fixed position C-band radar. The fixed position 250 kW doppler C-band weather radar was installed in April 2012 at Fljótsdalsheiði, E-Iceland, and in June 2012 IMO received a mobile 65 kW dual-polarization doppler X-band radar. Early in 2013 IMO will acquire another mobile radar of the same type. Explosive volcanic eruptions in Iceland during the past 22 years were monitored by the Keflavík radar: Hekla 1991, Gjálp 1996, Grímsvötn 1998, Hekla 2000, Grímsvötn 2004, Eyjafjallajökull 2010 and Grímsvötn 2011. Additionally, the Grímsvötn 2011 eruption was mointored by a mobile X-band radar on loan from the Italian Civil Protection Authorities. Detailed technical information is presented on the four radars with examples of the information acquired during previous eruptions. This expanded network of radars is expected to give valuable information on future volcanic eruptions in Iceland.

  15. Controls on the surface chemical reactivity of volcanic ash investigated with probe gases

    NASA Astrophysics Data System (ADS)

    Maters, Elena C.; Delmelle, Pierre; Rossi, Michel J.; Ayris, Paul M.; Bernard, Alain

    2016-09-01

    Increasing recognition that volcanic ash emissions can have significant impacts on the natural and human environment calls for a better understanding of ash chemical reactivity as mediated by its surface characteristics. However, previous studies of ash surface properties have relied on techniques that lack the sensitivity required to adequately investigate them. Here we characterise at the molecular monolayer scale the surfaces of ash erupted from Eyjafjallajökull, Tungurahua, Pinatubo and Chaitén volcanoes. Interrogation of the ash with four probe gases, trimethylamine (TMA; N(CH3)3), trifluoroacetic acid (TFA; CF3COOH), hydroxylamine (HA; NH2OH) and ozone (O3), reveals the abundances of acid-base and redox sites on ash surfaces. Measurements on aluminosilicate glass powders, as compositional proxies for the primary constituent of volcanic ash, are also conducted. We attribute the greater proportion of acidic and oxidised sites on ash relative to glass surfaces, evidenced by comparison of TMA/TFA and HA/O3 uptake ratios, in part to ash interaction with volcanic gases and condensates (e.g., H2O, SO2, H2SO4, HCl, HF) during the eruption. The strong influence of ash surface processing in the eruption plume and/or cloud is further supported by particular abundances of oxidised and reduced sites on the ash samples resulting from specific characteristics of their eruptions of origin. Intense interaction with water vapour may result in a higher fraction of oxidised sites on ash produced by phreatomagmatic than by magmatic activity. This study constitutes the first quantification of ash chemical properties at the molecular monolayer scale, and is an important step towards better understanding the factors that govern the role of ash as a chemical agent within atmospheric, terrestrial, aquatic or biotic systems.

  16. Implications for future activity of Grímsvötn volcano, Iceland, from compositional time series of historical tephra

    NASA Astrophysics Data System (ADS)

    Carpentier, Marion; Sigmarsson, Olgeir; Larsen, Gudrun

    2014-05-01

    The nature of future eruptions of active volcanoes is hard to predict. Improved understanding of the past volcanic activity is probably the best way to infer future eruptive scenarios. The most active volcano in Iceland, Grímsvötn, last erupted in 2011 with consequences for habitants living close to the volcano and aviation in the North-Atlantic. In an effort to better understand the magmatic system of the volcano, we have investigated the compositions of 23 selected tephra layers representing the last 8 centuries of volcanic activity at Grímsvötn. The tephra was collected in the ablation area of outlet glaciers from Vatnajökull ice cap. The ice-conserved tephra are less prone to alteration than those exposed in soil sections. Major element analyses are indistinguishable and of quartz-normative tholeiite composition, and Sr and Nd isotope ratios are constant. In contrast, both trace element concentrations (Th range from 0.875 ppm to 1.37 ppm and Ni from 28.5 ppm to 56.6 ppm) in the basalts and Pb isotopes show small but significant variations. The high-precision analyses of Pb isotope ratios allow the identification of tephra samples (3 in total) with more radiogenic ratios than the bulk of the samples. The tephra of constant isotope ratios show linear increase in incompatible element concentrations with time. The rate of increasing concentrations permits exploring possible future scenarios assuming that the magmatic system beneath the volcano follows the established historical evolution. Assuming similar future behaviour of the magma system beneath Grímsvötn volcano, the linear increase in e.g. Th concentration suggests that the volcano is likely to principally produce basalts for the next 500-1000 years. Evolution of water concentration will most likely follow those of incompatible elements with consequent increases in explosiveness of future Grímsvötn eruptions.

  17. Science verification of operational aerosol and cloud products for TROPOMI on Sentinel-5 precursor

    NASA Astrophysics Data System (ADS)

    Lelli, Luca; Gimeno-Garcia, Sebastian; Sanders, Abram; Sneep, Maarten; Rozanov, Vladimir V.; Kokhanvosky, Alexander A.; Loyola, Diego; Burrows, John P.

    2016-04-01

    With the approaching launch of the Sentinel-5 precursor (S-5P) satellite, scheduled by mid 2016, one preparatory task of the L2 working group (composed by the Institute of Environmental Physics IUP Bremen, the Royal Netherlands Meteorological Institute KNMI De Bilt, and the German Aerospace Center DLR Oberpfaffenhofen) has been the assessment of biases among aerosol and cloud products, that are going to be inferred by the respective algorithms from measurements of the platform's payload TROPOspheric Monitoring Instrument (TROPOMI). The instrument will measure terrestrial radiance with varying moderate spectral resolutions from the ultraviolet throughout the shortwave infrared. Specifically, all the operational and verification algorithms involved in this comparison exploit the sensitivity of molecular oxygen absorption (the A-band, 755-775 nm, with a resolution of 0.54 nm) to changes in optical and geometrical parameters of tropospheric scattering layers. Therefore, aerosol layer height (ALH) and thickness (AOT), cloud top height (CTH), thickness (COT) and albedo (CA) are the targeted properties. First, the verification of these properties has been accomplished upon synchronisation of the respective forward radiative transfer models for a variety of atmospheric scenarios. Then, biases against independent techniques have been evaluated with real measurements of selected GOME-2 orbits. Global seasonal bias assessment has been carried out for CTH, CA and COT, whereas the verification of ALH and AOT is based on the analysis of the ash plume emitted by the icelandic volcanic eruption Eyjafjallajökull in May 2010 and selected dust scenes off the Saharan west coast sensed by SCIAMACHY in year 2009.

  18. Global Volcano Model

    NASA Astrophysics Data System (ADS)

    Sparks, R. S. J.; Loughlin, S. C.; Cottrell, E.; Valentine, G.; Newhall, C.; Jolly, G.; Papale, P.; Takarada, S.; Crosweller, S.; Nayembil, M.; Arora, B.; Lowndes, J.; Connor, C.; Eichelberger, J.; Nadim, F.; Smolka, A.; Michel, G.; Muir-Wood, R.; Horwell, C.

    2012-04-01

    Over 600 million people live close enough to active volcanoes to be affected when they erupt. Volcanic eruptions cause loss of life, significant economic losses and severe disruption to people's lives, as highlighted by the recent eruption of Mount Merapi in Indonesia. The eruption of Eyjafjallajökull, Iceland in 2010 illustrated the potential of even small eruptions to have major impact on the modern world through disruption of complex critical infrastructure and business. The effects in the developing world on economic growth and development can be severe. There is evidence that large eruptions can cause a change in the earth's climate for several years afterwards. Aside from meteor impact and possibly an extreme solar event, very large magnitude explosive volcanic eruptions may be the only natural hazard that could cause a global catastrophe. GVM is a growing international collaboration that aims to create a sustainable, accessible information platform on volcanic hazard and risk. We are designing and developing an integrated database system of volcanic hazards, vulnerability and exposure with internationally agreed metadata standards. GVM will establish methodologies for analysis of the data (eg vulnerability indices) to inform risk assessment, develop complementary hazards models and create relevant hazards and risk assessment tools. GVM will develop the capability to anticipate future volcanism and its consequences. NERC is funding the start-up of this initiative for three years from November 2011. GVM builds directly on the VOGRIPA project started as part of the GRIP (Global Risk Identification Programme) in 2004 under the auspices of the World Bank and UN. Major international initiatives and partners such as the Smithsonian Institution - Global Volcanism Program, State University of New York at Buffalo - VHub, Earth Observatory of Singapore - WOVOdat and many others underpin GVM.

  19. In Situ Sensing Guided Geotechnical Modelling of Subglacial Deformation

    NASA Astrophysics Data System (ADS)

    Clayton, A.; Brain, M.; Hart, J. K.; Roberts, D.; Martinez, K.; Rosser, N. J.

    2014-12-01

    Data collected by in situ subglacial probes has been used to guide a series of geotechnical tests on till. The testing provides an opportunity to develop a process-based understanding of movement patterns observed in the subglacial environment. The probes were deployed by the Glacsweb project at Skalafellsjökull, Iceland, in 2008 and 2012. They were emplaced in till below 80 m of ice and recorded a number of variables including pore pressure, case stress, movement and conductivity. During the winter of 2008-2009 cyclic pressure changes were recorded in the till. Repeated pore pressure increases of up to 20% occurred over a variable period of one to eight weeks. Each rise was followed by a sharp drop in pore pressure lasting up to a few days. A back pressure shear box was used to replicate the pore pressure changes whilst maintaining a constant horizontal shear stress and normal total stress to examine effects on deformation and strain rate. Till was collected for testing from the ice margin close to the probes in 2012 and remoulded for use in the back pressure shear box. General characterisation of the till was performed to benchmark it against previous work and then a series of pore pressure re-inflation tests were undertaken. These approximated the pore pressure variations observed in the field by linearly increasing pore pressure and so decreasing normal effective stress. The till displayed dilatancy-induced episodic increases in strain rate. These were regulated by consolidation that increased shear strength and so reduced strain rate. Strain rate variations were similar to ice velocity variations recorded by differential GPS deployed on the ice surface above the probes.

  20. FUTUREVOLC: A European volcanological supersite in Iceland, a monitoring system and network for the future (Invited)

    NASA Astrophysics Data System (ADS)

    Sigmundsson, F.; Vogfjord, K. S.; Gudmundsson, M. T.; Kristinsson, I.; Loughlin, S. C.; Ilyinskaya, E.; Hooper, A. J.; Kylling, A.; Witham, C. S.; Bean, C. J.; Braiden, A.; Ripepe, M.; Prata, F.; Jordan, C. J.; Team, F.

    2013-12-01

    FUTURVOLC is a collaborative project funded through a FP7 Environment 'supersite' call of the European Union, with 26 partners in 10 countries. The main objectives of FUTUREVOLC are to establish an integrated volcanological monitoring procedure, develop new methods to evaluate volcanic crises, increase scientific understanding of magmatic processes and improve delivery of relevant information to civil protection and authorities. To reach these objectives the project combines broad expertise in seismology, volcano deformation, volcanic gas and geochemistry, infrasound, eruption monitoring, physical volcanology, satellite studies of plumes, meteorology, ash dispersal forecasting, and civil protection. The consortium members together with a more extensive group of collaborators, has applied to CEOS for making the Iceland volcanoes a permanent geohazard supersite. In summer 2013 FUTUREVOLC partners improved volcano monitoring in Iceland by installing new equipment, including seismometers, GPS receivers, an infrasound array, and electrical sensors. A key element of the project is to combine Icelandic ground based monitoring data with satellite observations in an improved manner. This applies to different disciplines, including e.g. deformation from ground observations and InSAR, and quantification of volcanic ash clouds during eruptions by combining measurements from ground based infrared (IR) cameras and satellite microwave and IR detectors. The FUTUREVOLC project has open data policy for real-time data streams, near real-time data and science products. Implementation of a data hub will begin in 2013 with making available data for the 2010 Eyjafjallajökull eruption. Access of monitoring data through one common interface will allow timely information on magma movements from combined interpretation of relocated earthquake sources, magma sources inferred from ground and space geodetic data, and measurements of volcanic volatiles. For better response during eruptions, the

  1. Measurements of the complex refractive index of volcanic ash at 450, 546.7, and 650 nm

    NASA Astrophysics Data System (ADS)

    Ball, J. G. C.; Reed, B. E.; Grainger, R. G.; Peters, D. M.; Mather, T. A.; Pyle, D. M.

    2015-08-01

    The detection and quantification of volcanic ash is extremely important to the aviation industry, civil defense organizations, and those in peril from volcanic ashfall. To exploit the remote sensing techniques that are used to monitor a volcanic cloud and return information on its properties, the effective complex refractive index of the volcanic ash is required. This paper presents the complex refractive index determined in the laboratory at 450.0 nm, 546.7 nm, and 650.0 nm for volcanic ash samples from eruptions of Aso (Japan), Grímsvötn (Iceland), Chaitén (Chile), Etna (Italy), Eyjafjallajökull (Iceland), Tongariro (New Zealand), Askja (Iceland), Nisyros (Greece), Okmok (Alaska), Augustine (Alaska), and Spurr (Alaska). The Becke line method was used to measure the real part of the refractive index with an accuracy of 0.01. The values measured differed between eruptions and were in the range 1.51-1.63 at 450.0 nm, 1.50-1.61 at 546.7 nm, and 1.50-1.59 at 650.0 nm. A novel method is introduced to derive the imaginary part of the refractive index from the attenuation of light by ash. The method has a precision in the range 10-3-10-4. The values for the ash imaginary refractive index ranged 0.22-1.70 × 10-3 at 450.0 nm, 0.16-1.93 × 10-3 at 546.7 nm, and 0.15-2.08 × 10-3 at 650.0 nm. The accuracy of Becke and attenuation methods was assessed by measuring the complex refractive index of Hoya neutral density glass and found to have an accuracy of <0.01 and <2 × 10-5 for the real and imaginary parts of the refractive index, respectively.

  2. Characterization of Eyjafjallajokull volcanic ash particles and a protocol for rapid risk assessment.

    PubMed

    Gislason, S R; Hassenkam, T; Nedel, S; Bovet, N; Eiriksdottir, E S; Alfredsson, H A; Hem, C P; Balogh, Z I; Dideriksen, K; Oskarsson, N; Sigfusson, B; Larsen, G; Stipp, S L S

    2011-05-01

    On April 14, 2010, when meltwaters from the Eyjafjallajökull glacier mixed with hot magma, an explosive eruption sent unusually fine-grained ash into the jet stream. It quickly dispersed over Europe. Previous airplane encounters with ash resulted in sandblasted windows and particles melted inside jet engines, causing them to fail. Therefore, air traffic was grounded for several days. Concerns also arose about health risks from fallout, because ash can transport acids as well as toxic compounds, such as fluoride, aluminum, and arsenic. Studies on ash are usually made on material collected far from the source, where it could have mixed with other atmospheric particles, or after exposure to water as rain or fog, which would alter surface composition. For this study, a unique set of dry ash samples was collected immediately after the explosive event and compared with fresh ash from a later, more typical eruption. Using nanotechniques, custom-designed for studying natural materials, we explored the physical and chemical nature of the ash to determine if fears about health and safety were justified and we developed a protocol that will serve for assessing risks during a future event. On single particles, we identified the composition of nanometer scale salt coatings and measured the mass of adsorbed salts with picogram resolution. The particles of explosive ash that reached Europe in the jet stream were especially sharp and abrasive over their entire size range, from submillimeter to tens of nanometers. Edges remained sharp even after a couple of weeks of abrasion in stirred water suspensions. PMID:21518890

  3. Probabilistic detection of volcanic ash using a Bayesian approach

    PubMed Central

    Mackie, Shona; Watson, Matthew

    2014-01-01

    Airborne volcanic ash can pose a hazard to aviation, agriculture, and both human and animal health. It is therefore important that ash clouds are monitored both day and night, even when they travel far from their source. Infrared satellite data provide perhaps the only means of doing this, and since the hugely expensive ash crisis that followed the 2010 Eyjafjalljökull eruption, much research has been carried out into techniques for discriminating ash in such data and for deriving key properties. Such techniques are generally specific to data from particular sensors, and most approaches result in a binary classification of pixels into “ash” and “ash free” classes with no indication of the classification certainty for individual pixels. Furthermore, almost all operational methods rely on expert-set thresholds to determine what constitutes “ash” and can therefore be criticized for being subjective and dependent on expertise that may not remain with an institution. Very few existing methods exploit available contemporaneous atmospheric data to inform the detection, despite the sensitivity of most techniques to atmospheric parameters. The Bayesian method proposed here does exploit such data and gives a probabilistic, physically based classification. We provide an example of the method's implementation for a scene containing both land and sea observations, and a large area of desert dust (often misidentified as ash by other methods). The technique has already been successfully applied to other detection problems in remote sensing, and this work shows that it will be a useful and effective tool for ash detection. Key Points Presentation of a probabilistic volcanic ash detection scheme Method for calculation of probability density function for ash observations Demonstration of a remote sensing technique for monitoring volcanic ash hazards PMID:25844278

  4. The Effects of Ice on the Frictional Electrification of Plumes

    NASA Astrophysics Data System (ADS)

    Méndez Harper, J.; Courtland, L. M.; Dufek, J.

    2015-12-01

    Studies of the Redoubt (2009), Eyjafjallajökull (2010), and the Cordón Caulle (2011) eruptions and associated electrical activity suggest that ice is a catalyst for the generation of plume lightning [Behnke et al., 2012; Arason et al., 2011; Nicora et al., 2013]. Indeed, the number lightning flashes in the umbrella and convective regions of the plume seems to correlate with lower, ice-forming temperatures. As in conventional thunderstorms, electric charge accumulation and separation in cold plumes may arise from the interplay between ice grains and graupel. However, charging may also be driven by triboelectrification (frictional charging), resulting from collisions between ice and ash grains. Decades of research have shown that fluidized granular materials comprising species of distinct composition often produce more efficient electrification than the interaction of chemically identical particles under similar hydrodynamic regime [e.g. Forward et al., 2009]. Thus, tribocharging in a combined ice and silicate granular flow is likely to yield grains with higher charges than those encountered in a flow composed solely of silicate grains, facilitating the generation of lightning [Méndez Harper and Dufek, 2015, submitted]. To indagate this hypothesis, we have developed a novel methodology to measure the time-dependent charging of individual micron-sized particles in both dry, silicate flows and silicate plus ice flows. Pure ash runs are conducted in a dry (<1 % humidity) environment with a temperature variation of -40o to 25o C. Runs involving ice are performed between -40o and 2o C, permitting us to quantify charging in the mixture as water transmogrifies from solid ice to a more mush-like substance. Additionally, we report on how collisional energy and rates influence electrification in these granular materials. We show that, although the variations in ash composition (basalt to rhyolite) tend to be of little consequence for charging, the presence of a water phase

  5. An accelerated data assimilation approach for volcanic ash forecast

    NASA Astrophysics Data System (ADS)

    Fu, Guangliang; Lin, Haixiang; Heemink, Arnold; Segers, Arjo; Lu, Sha

    2016-04-01

    The 2010 Eyjafjallajökull volcano eruption had serious consequences to civil aviation. This has initiated a lot of research on volcanic ash forecast in recent years. Ensemble-based data assimilation uses the observation data to improve the parameter and state estimation and subsequently the volcanic ash forecast accuracy. Due to the computational complexity of ensemble-based algorithms and the large scale of real-life applications, application of these methods usually introduces a large computational cost, particularly in the analysis step of assimilation processes. Because the other time-consuming part in the single CPU case, the forecast step, can be efficiently and easily parallelized. In this study, we focus on speeding up of the analysis step. For volcanic ash assimilation of aircraft-based measurements, the most time-consuming part in the analysis step has been shown to be the computation of the Kalman gain matrix. After a careful study on the characteristics of ensemble ash states, we propose a model-reduced Kalman gain (MR-Gain) approach which transforms the ensemble state matrix into a low-rank matrix by a multiplication with an index matrix which recorded the sparsity information of the ensemble state matrix, and thus the computational cost of all the ensemble-related matrix multiplications are reduced. After the computation of Kalman gain, using the previously recorded state index, the full analyzed ensemble states are reconstructed. The result shows the MR-Gain approach is exact, which can be used to replace the original full matrix with a much low computation cost. Computer experiments show that the computing time for the analysis step with the new approach is a factor of ten times faster than the conventional analysis step. The result also shows that with the accelerated analysis step in volcanic ash assimilation system, the total amount of computing time for volcanic ash forecast can be significantly reduced by up to a factor of 5.

  6. Volcanic ash modeling with the online NMMB/BSC-ASH-v1.0: A novel multiscale meteorological model for operational forecast

    NASA Astrophysics Data System (ADS)

    Marti, Alejandro; Folch, Arnau; Jorba, Oriol; Janjic, Zavisa

    2016-04-01

    Volcanic ash forecast became a research priority and a social concern as a consequence of the severe air-traffic disruptions caused by the eruptions of Eyjafjallajökull (Iceland, 2010) and Cordón Caulle (Chile, 2011) volcanoes. Significant progress has taken place in the aftermath of these dramatic events to improve the accuracy of Volcanic Ash Transport and Dispersal (VATD) models and lessen its associated uncertainties. Various levels of uncertainties affect both the quantification of the source term and the driving meteorological inputs. Substantial research is being performed to reduce and quantify epistemic and aleatoric uncertainties affecting the source term. However, uncertainties arising from the driving NWPMs and its coupling offline with the VATDMs have received little attention, even if the experience from other communities (e.g. air quality) highlights the importance of coupling online dispersal and meteorological modeling. Consequently, the need for integrated predictions to represent these two-way feedback effects of the volcanic pollutants on local-scale meteorology is timely. The aim of this talk is to present the NMMB/BSC-ASH, a new on-line multi-scale meteorological model to simulate the emission, transport and deposition of tephra particles released from volcanic eruptions. The model builds on the NMMB/BSC Chemical Transport Model (NMMB/BSC-CTM), which we have modified to account for the specifics of volcanic particles. The final objective in developing the NMMB/BSC-ASH model is two-fold. On one hand, at a research level, we aim at studying the differences between the online/offline approaches and quantify the two-way feedback effect of dense volcanic ash clouds on the radiative budget and regional meteorology. On the other hand, at an operational level, the low computational cost of the NMMB dynamic core suggests that NMMB/BSC-ASH could be applied in a future for more accurate online operational forecasting of volcanic ash clouds.

  7. Mapping of magnetic chrons: paleomagnetic polarity map of East Iceland, 0-13 Myr

    NASA Astrophysics Data System (ADS)

    Helgason, Johann

    2016-04-01

    Through data on palaeomagnetism, stratigraphy and radiometric age dating an immense database on magnetic chrons has been established for the lava succession in Iceland (e.g. Kristjánsson, 2008). Correlation of magnetic chrons with the geomagnetic time scale provides a reasonable age estimate for vast stratigraphic sequences. The basalt lava succession in Iceland has a thickness of tens of kilometers. The magnetostratigraphic data offer, through the help of paleomagnetism and radiometric dating, a detailed timing of events in the evolution of the Iceland mantle plume region. Yet a magnetic polarity map for Iceland has been lacking but during the last 50 years, comprehensive stratigraphic mapping has paved the way for a magnetic polarity map in various parts of Iceland. Here, such a map is presented for a segment of East Iceland, i.e. for lavas ranging in age from 0 to 13 M yr. The map is a compilation based on various studies into the cliff section and stratigraphic work performed by numerous research initiatives, both in relation to hydroelectric research as well as academic projects. References: Kristjánsson, L., 2008. Paleomagnetic research on Icelandic lava flows. Jökull, 58, 101-116. Helgason, J., Duncan, R.A., Franzson, H., Guðmundsson, Á., and M. Riishuus., 2015. Magnetic polarity map of Akrafjall and Skarðsheiði and new 40Ar-39Ar age dating from West Iceland., Presentation at the spring conference of the Icelandic Geological Society, held on March 13th 2015 at the University of Iceland.

  8. Tectonic significance of the South Iceland Seismic Transform Zone

    NASA Astrophysics Data System (ADS)

    Luxey, Pascal; Blondel, Philippe; Parson, Lindsay M.

    1997-08-01

    The subaerial expression of the Mid-Atlantic Ridge on Iceland comprises two overlapping spreading axes, referred to as the West Volcanic Zone (WVZ) and the East Volcanic Zone (EVZ), respectively. The way the spreading rate is distributed on both volcanic zones has an important impact on the stress pattern in the overlap area. Our field data from the area trace the evolution of the stress direction as recorded by slip motion on fault planes. We found four different strike-slip stress phases. An early N-S compression phase (A) preceded a NE-SW compression phase (B). This phase was followed by a SE-NW compression phase (C). However, we cannot date an E-W compression, phase (D), relative to the other phases. Numerical modeling based on the assumption that the WVZ has been permanently active during the last 3 Myr and that the EVZ is propagating southward confirms that stress directions have rotated clockwise by more than 140°. These results fit perfectly with our field analysis, and we propose that phase A corresponds to initial EVZ ridge-tip propagation, phase B to emplacement of the EVZ southern tip near Torfajökull, and phase C to an extreme southern location near the Surtsey Islands of the EVZ southern tip. Phase D could correspond to an intermediate stage between phases B and C. We suggest that this sequence of tectonics, recorded in a regional overlapping ridge-tip setting, is directly analogous to smaller-scale and more common phenomena at second-order ridge discontinuities throughout the global mid-ocean ridge system.

  9. Lightning climatology of exoplanets and brown dwarfs guided by Solar system data

    NASA Astrophysics Data System (ADS)

    Hodosán, G.; Helling, Ch.; Asensio-Torres, R.; Vorgul, I.; Rimmer, P. B.

    2016-10-01

    Clouds form on extrasolar planets and brown dwarfs where lightning could occur. Lightning is a tracer of atmospheric convection, cloud formation and ionization processes as known from the Solar system, and may be significant for the formation of prebiotic molecules. We study lightning climatology for the different atmospheric environments of Earth, Venus, Jupiter and Saturn. We present lightning distribution maps for Earth, Jupiter and Saturn, and flash densities for these planets and Venus, based on optical and/or radio measurements from the World Wide Lightning Location Network and Sferics Timing and Ranging Network radio networks, the Lightning Imaging Sensor/Optical Transient Detector satellite instruments, the Galileo, Cassini, New Horizons and Venus Express spacecraft. We also present flash densities calculated for several phases of two volcano eruptions, Eyjafjallajökull's (2010) and Mt Redoubt's (2009). We estimate lightning rates for sample, transiting and directly imaged extrasolar planets and brown dwarfs. Based on the large variety of exoplanets, six categories are suggested for which we use the lightning occurrence information from the Solar system. We examine lightning energy distributions for Earth, Jupiter and Saturn. We discuss how strong stellar activity may support lightning activity. We provide a lower limit of the total number of flashes that might occur on transiting planets during their full transit as input for future studies. We find that volcanically very active planets might show the largest lightning flash densities. When applying flash densities of the large Saturnian storm from 2010/11, we find that the exoplanet HD 189733b would produce high lightning occurrence even during its short transit.

  10. Near Real Time Detection and Tracking of the EYJAFJÖLL (iceland) Ash Cloud by the RST (robust Satellite Technique) Approach

    NASA Astrophysics Data System (ADS)

    Tramutoli, V.; Filizzola, C.; Marchese, F.; Paciello, R.; Pergola, N.; Sannazzaro, F.

    2010-12-01

    Volcanic ash clouds, besides to be an environmental issue, represent a serious problem for air traffic and an important economic threat for aviation companies. During the recent volcanic crisis due to the April-May 2010 eruption of Eyjafjöll (Iceland), ash clouds became a real problem for common citizens as well: during the first days of the eruption thousands of flights were cancelled disrupting hundred of thousands of passengers. Satellite remote sensing confirmed to be a crucial tool for monitoring this kind of events, spreading for thousands of kilometres with a very rapid space-time dynamics. Especially weather satellites, thanks to their high temporal resolution, may furnish a fundamental contribution, providing frequently updated information. However, in this particular case ash cloud was accompanied by a sudden and significant emission of water vapour, due to the ice melting of Eyjafjallajökull glacier, making satellite ash detection and discrimination very hard, especially in the first few days of the eruption, exactly when accurate information were mostly required in order to support emergency management. Among the satellite-based techniques for near real-time detection and tracking of ash clouds, the RST (Robust Satellite Technique) approach, formerly named RAT - Robust AVHRR Technique, has been long since proposed, demonstrating high performances both in terms of reliability and sensitivity. In this paper, results achieved by using RST-based detection schemes, applied during the Eyjafjöll eruption were presented. MSG-SEVIRI (Meteosat Second Generation - Spinning Enhanced and Visible Infrared Imager) records, with a temporal sampling of 15 minutes, were used applying a standard as well as an advanced RST configuration, which includes the use of SO2 absorption band together with TIR and MIR channels. Main outcomes, limits and possible future improvements were also discussed.

  11. How To Promote Data Quality And Access? Publish It!

    NASA Astrophysics Data System (ADS)

    Carlson, D. J.; Pfeiffenberger, H.

    2011-12-01

    Started during IPY 2007-2008, the Earth System Science Data journal (Copernicus) has now 'tested the waters' of earth system data publishing for approximately 2 years with some success. The journal has published more than 30 data sets, of remarkable breadth and variety, all under a Creative Commons Attribution license. Users can now find well-described, quality-controlled and freely accessible data on soils, permafrost, sediment transport, ice sheets, surface radiation, ocean-atmosphere fluxes, ocean chemistry, gravity fields, and combined radar and web cam observations of the Eyjafjallajökull eruption plume. Several of the data sets derive specifically from IPY or from polar regions, but a large portion, including a substantial special issue on ocean carbon, cover broad temporal and geographic domains; the contributors themselves come from leading science institutions around the world. ESSD has attracted the particular interest of international research teams, particularly those who, as in the case of ocean carbon data, have spent many years gathering, collating and calibrating global data sets under long-term named programs, but who lack within those programs the mechanisms to distribute those data sets widely outside their specialist teams and to ensure proper citation credit for those remarkable collaborative data processing efforts. An in-progress special issue on global ocean plankton function types, again representing years of international data collaboration, provides a further example of ESSD utility to large research programs. We anticipate an interesting test case of parallel special issues with companion science journals - data sets in ESSD to accompany science publications in a prominent research journal. We see the ESSD practices and products as useful steps to increase quality of and access to important data sets.

  12. The Evolving Structure of Young Volcanic Eruption Clouds

    NASA Astrophysics Data System (ADS)

    Carn, S. A.; Bursik, M. I.

    2015-12-01

    Processes acting in nascent volcanic clouds within seconds to hours of eruption (e.g., ash aggregation, ice nucleation, gravity waves) set the stage for subsequent advection and diffusion of volcanic ash, hence strongly influence aviation hazards and atmospheric impacts, but are very difficult to observe. Young plumes initially spread by gravity in the crosswind direction due to density differences with the surrounding stratified atmosphere. Subsequently, plumes lose their density contrast with the atmosphere and are advected as lenses of aerosol and gas, slowly thinning, spreading and dispersing as shearing and small scale turbulence act at their margins, and as fine ash settles out. Since 2006, satellite observations from NASA's A-Train constellation, including the CALIOP lidar and CloudSat radar, have provided tantalizing glimpses of young volcanic clouds in the first few hours of atmospheric residence. These unique observations, although spatially limited, provide insight into the evolving structure of young volcanic clouds from an optically thick, vertically extensive initial state to thin layers confined to a limited altitude range. Layered volcanic clouds may develop due to the existence of alternating turbulent and stable layers in the free troposphere and stratosphere. Turbulent layers retain particles longer than do quiescent layers because the turbulence retains particles in suspension. Particles fall more rapidly through the quiescent layers by single particle settling, or more rapidly because of convective sedimentation. The result is a distinct, banded ash cloud structure. We present A-Train satellite observations of volcanic clouds at various stages of evolution from several recent eruptions (including Kelut, Redoubt, Chaitén, Eyjafjallajökull, Okmok and Kasatochi) and also show the results of preliminary model simulations of the development of volcanic cloud layering.

  13. Characterization of Eyjafjallajokull volcanic ash particles and a protocol for rapid risk assessment.

    PubMed

    Gislason, S R; Hassenkam, T; Nedel, S; Bovet, N; Eiriksdottir, E S; Alfredsson, H A; Hem, C P; Balogh, Z I; Dideriksen, K; Oskarsson, N; Sigfusson, B; Larsen, G; Stipp, S L S

    2011-05-01

    On April 14, 2010, when meltwaters from the Eyjafjallajökull glacier mixed with hot magma, an explosive eruption sent unusually fine-grained ash into the jet stream. It quickly dispersed over Europe. Previous airplane encounters with ash resulted in sandblasted windows and particles melted inside jet engines, causing them to fail. Therefore, air traffic was grounded for several days. Concerns also arose about health risks from fallout, because ash can transport acids as well as toxic compounds, such as fluoride, aluminum, and arsenic. Studies on ash are usually made on material collected far from the source, where it could have mixed with other atmospheric particles, or after exposure to water as rain or fog, which would alter surface composition. For this study, a unique set of dry ash samples was collected immediately after the explosive event and compared with fresh ash from a later, more typical eruption. Using nanotechniques, custom-designed for studying natural materials, we explored the physical and chemical nature of the ash to determine if fears about health and safety were justified and we developed a protocol that will serve for assessing risks during a future event. On single particles, we identified the composition of nanometer scale salt coatings and measured the mass of adsorbed salts with picogram resolution. The particles of explosive ash that reached Europe in the jet stream were especially sharp and abrasive over their entire size range, from submillimeter to tens of nanometers. Edges remained sharp even after a couple of weeks of abrasion in stirred water suspensions.

  14. FPLUME-1.0: An integral volcanic plume model accounting for ash aggregation

    NASA Astrophysics Data System (ADS)

    Folch, A.; Costa, A.; Macedonio, G.

    2016-02-01

    Eruption source parameters (ESP) characterizing volcanic eruption plumes are crucial inputs for atmospheric tephra dispersal models, used for hazard assessment and risk mitigation. We present FPLUME-1.0, a steady-state 1-D (one-dimensional) cross-section-averaged eruption column model based on the buoyant plume theory (BPT). The model accounts for plume bending by wind, entrainment of ambient moisture, effects of water phase changes, particle fallout and re-entrainment, a new parameterization for the air entrainment coefficients and a model for wet aggregation of ash particles in the presence of liquid water or ice. In the occurrence of wet aggregation, the model predicts an effective grain size distribution depleted in fines with respect to that erupted at the vent. Given a wind profile, the model can be used to determine the column height from the eruption mass flow rate or vice versa. The ultimate goal is to improve ash cloud dispersal forecasts by better constraining the ESP (column height, eruption rate and vertical distribution of mass) and the effective particle grain size distribution resulting from eventual wet aggregation within the plume. As test cases we apply the model to the eruptive phase-B of the 4 April 1982 El Chichón volcano eruption (México) and the 6 May 2010 Eyjafjallajökull eruption phase (Iceland). The modular structure of the code facilitates the implementation in the future code versions of more quantitative ash aggregation parameterization as further observations and experiment data will be available for better constraining ash aggregation processes.

  15. Revealing the aerosol radiative impact of volcanic ash on synoptic time scales

    NASA Astrophysics Data System (ADS)

    Walter, Carolin; Rieger, Daniel; Gasch, Philipp; Förstner, Jochen; Vogel, Bernhard

    2016-04-01

    Including the interactions of aerosols with radiation in weather forecast models often leads to perturbations of the temperature field even at locations not directly influenced by the regarded aerosols. They arise out of signals propagating with the speed of sound leading to abrupt changes in cloud cover. The temperature perturbations due to these changes hamper the quantification of the aerosol radiative impact as they can appear in the same order of magnitude. In order to reveal the aerosol radiative impact on synoptic time scales we introduce a new method to separate the aerosol induced temperature effect from atmospheric perturbations. We simulated the impact of volcanic ash aerosol on radiation with the new global to regional scale modelling system ICON-ART (ICOsahedral Nonhydrostatic - Aerosols and Reactive Trace gases; Rieger et al., 2015). Within ICON-ART the radiative fluxes and cooling rates are calculated with the RRTM (Rapid Radiative Transfer Model; Mlawer et al., 1997) for 30 longwave and shortwave bands. To determine the optical properties of the prognostic ash aerosol, Mie calculations were conducted for a compilation of ash refractive indices. We obtain a significant change in 2 m temperature of up to several Kelvin for the Puyehue-Cordon Caulle eruption in 2011. In addition to the temperature effect the atmospheric stability is modified and as a consequence the ash concentrations. The temperature effect during the Eyjafjallajökull eruption in 2010 over Europe is much less pronounced. Nevertheless, we are able to show the impact of volcanic ash on the state of the atmosphere by this eruption.

  16. Benefit of depolarization ratio at λ = 1064 nm for the retrieval of the aerosol microphysics from lidar measurements

    NASA Astrophysics Data System (ADS)

    Gasteiger, J.; Freudenthaler, V.

    2014-11-01

    A better quantification of aerosol properties is required for improving the modelling of aerosol effects on weather and climate. This task is methodologically demanding due to the diversity of the microphysical properties of aerosols and the complex relation between their microphysical and optical properties. Advanced lidar systems provide spatially and temporally resolved information on the aerosol optical properties that is sufficient for the retrieval of important aerosol microphysical properties. Recently, the mass concentration of transported volcanic ash, which is relevant for the flight safety of aeroplanes, was retrieved from measurements of such lidar systems in southern Germany. The relative uncertainty of the retrieved mass concentration was on the order of ±50%. The present study investigates improvements of the retrieval accuracy when the capability of measuring the linear depolarization ratio at 1064 nm is added to the lidar setup. The lidar setups under investigation are based on those of MULIS and POLIS of the Ludwig-Maximilians-Universität in Munich (Germany) which measure the linear depolarization ratio at 355 and 532 nm with high accuracy. The improvements are determined by comparing uncertainties from retrievals applied to simulated measurements of this lidar setup with uncertainties obtained when the depolarization at 1064 nm is added to this setup. The simulated measurements are based on real lidar measurements of transported Eyjafjallajökull volcano ash. It is found that additional 1064 nm depolarization measurements significantly reduce the uncertainty of the retrieved mass concentration and effective particle size. This significant improvement in accuracy is the result of the increased sensitivity of the lidar setup to larger particles. The size dependence of the depolarization does not vary strongly with refractive index, thus we expect similar benefits for the retrieval in case of measurements of other volcanic ash compositions and

  17. Deformation of Grímsvötn volcano, Iceland, 1992-2014: Constraints on magma flow in relation to eruptions in 1998, 2004 and 2011

    NASA Astrophysics Data System (ADS)

    Sigmundsson, Freysteinn; Hreinsdottir, Sigrun; Sturkell, Erik; Ofeigsson, Benedikt; Einarsson, Pall; Roberts, Matthew; Grapenthin, Ronni; Villemin, Thierry; Arnadottir, Thora; Geirsson, Halldor

    2014-05-01

    A time series of ground deformation at Grímsvötn volcano, Iceland from 1992 to 2014 reveals deformation due to plate movements, glacial-isostatic uplift in response to the melting of the Vatnajökull ice cap, annual changes due to snow loading and magma movements. GPS measurements have been made at one nunatak, conducted intermittently since 1992 and continuously since 2004. During this period eruptions have occurred at Grímsvötn in 1998, 2004 and 2011. The component of displacement related to magma movements is obtained after the time series are corrected for signals due to other processes. Uplift and displacement away from the caldera occurs between eruptions at a rate of few cm/yr, interrupted by sudden co-eruptive subsidence and displacement towards the caldera (up to half a meter). This inflation/deflation pattern suggests deformation driven by pressure change in an upper crustal magma chamber, similar to other highly active calderas in Iceland such as Askja and Krafla. A simple model of pressure change variation in a magma chamber at shallow depth, with variable inflow between eruptions and outflow during eruptions can explain the observed deformation pattern. The erupted volume of magma in the 2011 eruption is about 10 times larger than the inferred co-eruptive volume change, attributed to compressibility of magma in the chamber. The magma compressibility is inferred to have remained constant during the 2011 eruption, as about constant scale factor is found during that eruption between eruption rate and displacement rate. This scale factor is, however, about five times lower for the 2004 eruption. This difference implies higher compressibility of magma in the shallow Grímsvötn magma chamber during the 2011 eruption compared to 2004, assuming the active part of the Grimsvötn magma plumbing system remained the same in both eruptions.

  18. Detecting and Cataloging Global Explosive Volcanism Using the IMS Infrasound Network

    NASA Astrophysics Data System (ADS)

    Matoza, R. S.; Green, D. N.; LE Pichon, A.; Fee, D.; Shearer, P. M.; Mialle, P.; Ceranna, L.

    2015-12-01

    Explosive volcanic eruptions are among the most powerful sources of infrasound observed on earth, with recordings routinely made at ranges of hundreds to thousands of kilometers. These eruptions can also inject large volumes of ash into heavily travelled aviation corridors, thus posing a significant societal and economic hazard. Detecting and counting the global occurrence of explosive volcanism helps with progress toward several goals in earth sciences and has direct applications in volcanic hazard mitigation. This project aims to build a quantitative catalog of global explosive volcanic activity using the International Monitoring System (IMS) infrasound network. We are developing methodologies to search systematically through IMS infrasound array detection bulletins to identify signals of volcanic origin. We combine infrasound signal association and source location using a brute-force, grid-search, cross-bearings approach. The algorithm corrects for a background prior rate of coherent infrasound signals in a global grid. When volcanic signals are identified, we extract metrics such as location, origin time, acoustic intensity, signal duration, and frequency content, compiling the results into a catalog. We are testing and validating our method on several well-known case studies, including the 2009 eruption of Sarychev Peak, Kuriles, the 2010 eruption of Eyjafjallajökull, Iceland, and the 2015 eruption of Calbuco, Chile. This work represents a step toward the goal of integrating IMS data products into global volcanic eruption early warning and notification systems. Additionally, a better characterization of volcanic signal detection helps improve understanding of operational event detection, discrimination, and association capabilities of the IMS network.

  19. Emergency Hospital Visits in Association with Volcanic Ash, Dust Storms and Other Sources of Ambient Particles: A Time-Series Study in Reykjavík, Iceland

    PubMed Central

    Carlsen, Hanne Krage; Gislason, Thorarinn; Forsberg, Bertil; Meister, Kadri; Thorsteinsson, Throstur; Jóhannsson, Thorsteinn; Finnbjornsdottir, Ragnhildur; Oudin, Anna

    2015-01-01

    Volcanic ash contributed significantly to particulate matter (PM) in Iceland following the eruptions in Eyjafjallajökull 2010 and Grímsvötn 2011. This study aimed to investigate the association between different PM sources and emergency hospital visits for cardiorespiratory causes from 2007 to 2012. Indicators of PM10 sources; “volcanic ash”, “dust storms”, or “other sources” (traffic, fireworks, and re-suspension) on days when PM10 exceeded the daily air quality guideline value of 50 µg/m3 were entered into generalized additive models, adjusted for weather, time trend and co-pollutants. The average number of daily emergency hospital visits was 10.5. PM10 exceeded the air quality guideline value 115 out of 2191 days; 20 days due to volcanic ash, 14 due to dust storms (two days had both dust storm and ash contribution) and 83 due to other sources. High PM10 levels from volcanic ash tended to be significantly associated with the emergency hospital visits; estimates ranged from 4.8% (95% Confidence Interval (CI): 0.6, 9.2%) per day of exposure in unadjusted models to 7.3% (95% CI: −0.4, 15.5%) in adjusted models. Dust storms were not consistently associated with daily emergency hospital visits and other sources tended to show a negative association. We found some evidence indicating that volcanic ash particles were more harmful than particles from other sources, but the results were inconclusive and should be interpreted with caution. PMID:25872017

  20. Climate Throughout Geologic Time Was Cooled by Sequences of Explosive Volcanic Eruptions Forming Aerosols That Reflect and Scatter Ultraviolet Solar Radiation and Warmed by Relatively Continuous Extrusion of Basaltic Lava that Depletes Ozone, Allowing More Solar Ultraviolet Radiation to Reach Earth

    NASA Astrophysics Data System (ADS)

    Ward, P. L.

    2015-12-01

    Active volcanoes of all sizes and eruptive styles, emit chlorine and bromine gases observed to deplete ozone. Effusive, basaltic volcanic eruptions, typical in Hawaii and Iceland, extrude large lava flows, depleting ozone and causing global warming. Major explosive volcanoes also deplete ozone with the same emissions, causing winter warming, but in addition eject megatons of water and sulfur dioxide into the lower stratosphere where they form sulfuric-acid aerosols whose particles grow large enough to reflect and scatter ultraviolet sunlight, causing net global cooling for a few years. The relative amounts of explosive and effusive volcanism are determined by the configuration of tectonic plates moving around Earth's surface. Detailed studies of climate change throughout geologic history, and since 1965, are not well explained by greenhouse-gas theory, but are explained quite clearly at OzoneDepletionTheory.info. Ozone concentrations vary substantially by the minute and show close relationships to weather system highs and lows (as pointed out by Dobson in the 1920s), to the height of the tropopause, and to the strength and location of polar vortices and jet streams. Integrating the effects of volcanism on ozone concentrations and the effects of ozone concentrations on synoptic weather patterns should improve weather forecasting. For example, the volcano Bárðarbunga, in central Iceland, extruded 85 km2 of basaltic lava between August 29, 2014, and February 28, 2015, having a profound effect on weather. Most surprising, more than a week before the March 4 eruption of Eyjafjallajökull in 2010, substantial amounts of ozone were released in the vicinity of the volcano precisely when surface deformation showed that magma first began moving up from sills below 4 km depth. Ozone similarly appears to have been emitted 3.5 months before the Pinatubo eruption in 1991. Readily available daily maps of ozone concentrations may allow early warning of an imminent volcanic

  1. Advances in Monitoring, Modelling and Forecasting Volcanic Ash Plumes over the Past 5 Years and the Impact on Preparedness from the London VAAC Perspective

    NASA Astrophysics Data System (ADS)

    Lee, D. S.; Lisk, I.

    2015-12-01

    Hosted and run by the Met Office, the London VAAC (Volcanic Ash Advisory Centre) is responsible for issuing advisories on the location and likely dispersion of ash clouds originating from volcanoes in the North East Atlantic, primarily from Iceland. These advisories and additional guidance products are used by the civil aviation community to make decisions on airspace flight management. London VAAC has specialist forecasters who use a combination of volcano source data, satellite-based, ground-based and aircraft observations, weather forecast models and dispersion models. Since the eruption of the Icelandic volcano Eyjafjallajökull in 2010, which resulted in the decision by many northern European countries to impose significant restrictions on the use of their airspace, London VAAC has been active in further developing its volcanic ash monitoring, modelling and forecasting capabilities, collaborating with research organisations, industry, other VAACs, Meteorological Services and the Volcano Observatory in Iceland. It has been necessary to advance operational capabilities to address evolving requirements, including for more quantitative assessments of volcanic ash in the atmosphere. Here we summarise advances in monitoring, modelling and forecasting of volcanic ash plumes over the past 5 years from the London VAAC perspective, and the realization of science into operations. We also highlight the importance of collaborative activities, such as the 'VAAC Best Practice' Workshop, where information is exchanged between all nine VAACs worldwide on the operational practices in monitoring and forecasting volcanic ash, with the aim of working toward a more harmonized service for decision makers in the aviation community. We conclude on an evaluation of how better we are prepared for the next significant ash-rich Icelandic eruption, and the challenges still remaining.

  2. Bar deposition in glacial outburst floods: scaling, post-flood reworking, and implications for the geomorphological and sedimentary record

    NASA Astrophysics Data System (ADS)

    Marren, Philip

    2016-04-01

    The appearance of a flood deposit in the geomorphological and sedimentary record is a product of both the processes operating during the flood, and those that occur afterwards and which overprint the deposit with a record of 'normal' processes. This paper describes the creation and modification of jökulhlaup barforms in the Skeiðará river, relating the changes to post-flood fluvial processes and glacier retreat. Large compound bars formed from the amalgamation of unit bars up to 1.5 km long. Nearly half of the total discharge of the November 1996 jökulhlaup on Skeiðarársandur was discharged through the Skeiðará river. The flood deposits have been extensively reworked since, up until 2009 when the channel was abandoned, effectively leaving the Skeiðará as a terrace, when retreat of Skeiðarárjökull directed meltwater to the adjacent Gígjukvísl river system. Large compound bars formed in the flood channel, with their location governed by the macro-scale topography of the flood channel, and their size by upstream channel width in accordance with bar-scaling theory. Jökulhlaup bars are therefore scale invariant and formed in a similar fashion to braid bars in non-jökulhlaup braided rivers. Post-flood fragmentation and reworking of the bars consistently increased the length-width ratio of preserved bar fragments from approximately two and one half to over five. When combined with earlier work on the Skeiðará jökulhlaup bars, and studies of jökulhlaup deposits elsewhere on Skeiðarársandur these observations increase our understanding of the preservation potential and final form of jökulhlaup deposits and provide the basis for an improved model for the recognition of jökulhlaup deposits in the geomorphological and sedimentary record.

  3. Resident perception of volcanic hazards and evacuation procedures

    NASA Astrophysics Data System (ADS)

    Bird, D. K.; Gisladottir, G.; Dominey-Howes, D.

    2009-02-01

    Katla volcano, located beneath the Mýrdalsjökull ice cap in southern Iceland, is capable of producing catastrophic jökulhlaup. The Icelandic Civil Protection (ICP), in conjunction with scientists, local police and emergency managers, developed mitigation strategies for possible jökulhlaup produced during future Katla eruptions. These strategies were tested during a full-scale evacuation exercise in March 2006. A positive public response during a volcanic crisis not only depends upon the public's knowledge of the evacuation plan but also their knowledge and perception of the possible hazards. To improve the effectiveness of residents' compliance with warning and evacuation messages it is important that emergency management officials understand how the public interpret their situation in relation to volcanic hazards and their potential response during a crisis and apply this information to the ongoing development of risk mitigation strategies. We adopted a mixed methods approach in order to gain a broad understanding of residents' knowledge and perception of the Katla volcano in general, jökulhlaup hazards specifically and the regional emergency evacuation plan. This entailed field observations during the major evacuation exercise, interviews with key emergency management officials and questionnaire survey interviews with local residents. Our survey shows that despite living within the hazard zone, many residents do not perceive that their homes could be affected by a jökulhlaup, and many participants who perceive that their homes are safe, stated that they would not evacuate if an evacuation warning was issued. Alarmingly, most participants did not receive an evacuation message during the exercise. However, the majority of participants who took part in the exercise were positive about its implementation. This assessment of resident knowledge and perception of volcanic hazards and the evacuation plan is the first of its kind in this region. Our data can be used

  4. Reference dataset of volcanic ash physicochemical and optical properties for atmospheric measurement retrievals and transport modelling

    NASA Astrophysics Data System (ADS)

    Vogel, Andreas; Durant, Adam; Sytchkova, Anna; Diplas, Spyros; Bonadonna, Costanza; Scarnato, Barbara; Krüger, Kirstin; Kylling, Arve; Kristiansen, Nina; Stohl, Andreas

    2016-04-01

    Explosive volcanic eruptions emit up to 50 wt.% (total erupted mass) of fine ash particles (<63 microns), which individually can have theoretical atmospheric lifetimes that span hours to days. Depending on the injection height, fine ash may be subsequently transported and dispersed by the atmosphere over 100s - 1000s km and can pose a major threat for aviation operations. Recent volcanic eruptions, such as the 2010 Icelandic Eyjafjallajökull event, illustrated how volcanic ash can severely impact commercial air traffic. In order to manage the threat, it is important to have accurate forecast information on the spatial extent and absolute quantity of airborne volcanic ash. Such forecasts are constrained by empirically-derived estimates of the volcanic source term and the nature of the constituent volcanic ash properties. Consequently, it is important to include a quantitative assessment of measurement uncertainties of ash properties to provide realistic ash forecast uncertainty. Currently, information on volcanic ash physicochemical and optical properties is derived from a small number of somewhat dated publications. In this study, we provide a reference dataset for physical (size distribution and shape), chemical (bulk vs. surface chemistry) and optical properties (complex refractive index in the UV-vis-NIR range) of a representative selection of volcanic ash samples from 10 different volcanic eruptions covering the full variability in silica content (40-75 wt.% SiO2). Through the combination of empirical analytical methods (e.g., image analysis, Energy Dispersive Spectroscopy, X-ray Photoelectron Spectroscopy, Transmission Electron Microscopy and UV/Vis/NIR/FTIR Spectroscopy) and theoretical models (e.g., Bruggeman effective medium approach), it was possible to fully capture the natural variability of ash physicochemical and optical characteristics. The dataset will be applied in atmospheric measurement retrievals and atmospheric transport modelling to determine

  5. Computation of probabilistic hazard maps and source parameter estimation for volcanic ash transport and dispersion

    SciTech Connect

    Madankan, R.; Pouget, S.; Singla, P.; Bursik, M.; Dehn, J.; Jones, M.; Patra, A.; Pavolonis, M.; Pitman, E.B.; Singh, T.; Webley, P.

    2014-08-15

    Volcanic ash advisory centers are charged with forecasting the movement of volcanic ash plumes, for aviation, health and safety preparation. Deterministic mathematical equations model the advection and dispersion of these plumes. However initial plume conditions – height, profile of particle location, volcanic vent parameters – are known only approximately at best, and other features of the governing system such as the windfield are stochastic. These uncertainties make forecasting plume motion difficult. As a result of these uncertainties, ash advisories based on a deterministic approach tend to be conservative, and many times over/under estimate the extent of a plume. This paper presents an end-to-end framework for generating a probabilistic approach to ash plume forecasting. This framework uses an ensemble of solutions, guided by Conjugate Unscented Transform (CUT) method for evaluating expectation integrals. This ensemble is used to construct a polynomial chaos expansion that can be sampled cheaply, to provide a probabilistic model forecast. The CUT method is then combined with a minimum variance condition, to provide a full posterior pdf of the uncertain source parameters, based on observed satellite imagery. The April 2010 eruption of the Eyjafjallajökull volcano in Iceland is employed as a test example. The puff advection/dispersion model is used to hindcast the motion of the ash plume through time, concentrating on the period 14–16 April 2010. Variability in the height and particle loading of that eruption is introduced through a volcano column model called bent. Output uncertainty due to the assumed uncertain input parameter probability distributions, and a probabilistic spatial-temporal estimate of ash presence are computed.

  6. Requirements and Implementation Feasibility for a CubeSat Thermal Infrared Imaging System to Monitor the Structure of Volcanic Ash Clouds

    NASA Astrophysics Data System (ADS)

    Thorsen, D.; Carroll, R.; Webley, P.; Hawkins, J.

    2014-12-01

    The 2010 eruption of the Eyjafjallajökull volcano in Iceland caused the cancellation of approximately 108,000 flights over an 8-day period, disrupted air traffic worldwide, and cost the airline industry more than $400 million per day. The inconvenience and economic impact of this and similar events, such as Puyehue-Cordon-Caulle in 2011, have heightened the interest in developing improved satellite remote sensing techniques for monitoring volcanic plumes and drifting clouds. For aviation safety, the operational/research community has started to move towards classifying the concentrations within volcanic plumes and clouds. Additionally, volcanic ash transport and dispersion (VATD) models are often used for forecasting ash cloud locations and they require knowledge of the structure of the erupting column to improve their ash simulations and also downwind 3-D maps of the ash cloud to calibrate/validate their modeling output. Existing remote sensing satellites utilize a brightness temperature method with thermal infrared (TIR) measurements from 10 - 12 μm to determine mass loading of volcanic ash along a single line of sight, but they have infrequent revisit times and they cannot resolve the three-dimensional structure of the ash clouds. A cluster of CubeSats dedicated to the monitoring of volcanic ash and plumes could provide both more frequent updates and the multi-aspect images needed to resolve the density structure of volcanic ash clouds and plumes. In this presentation, we discuss the feasibility and requirements for a CubeSat TIR imaging system and the associated on-board image processing that would be required to monitor the structure of volcanic ash clouds from Low Earth Orbit.

  7. Influence of volcanic tephra on photovoltaic (PV)-modules: An experimental study with application to the 2010 Eyjafjallajokull eruption, Iceland

    NASA Astrophysics Data System (ADS)

    Zorn, Edgar; Walter, Thomas R.

    2016-04-01

    Large volcanic eruptions may lead to significant tephra dispersion, crossing borders and affecting distant and industrial societies in various ways. While the effects of volcanic ash clouds on the aviation industry have been recognized, damaging effects on the photovoltaic energy sector are poorly investigated. Here we describe the influence of volcanic tephra deposition on photovoltaic (PV) modules that we experimentally analyzed and evaluated. A systematic set of experiments was conducted under controlled conditions using an artificial light source and measuring the electrical power generated from the PV-modules with the aim to determine the dependency of the amount of tephra covering a module and its subsequent loss in power production (measured in voltage and current) as well as the influence of the tephra grain size. We find that a mass of fine tephra has a stronger influence on the PV-modules power generation than the same mass of coarser particles. An application to the fine-grained 2010 Eyjafjallajökull eruption in Iceland and the resulting ash-cloud reveals that the power produced by PV-modules in continental Europe might have been affected significantly. Deposits were thick enough to cause complete failures of PV-modules up to a distance of about 300 km downwind. Although this distance is largely over the ocean in this particular case, our results imply that similar and larger eruptions of other volcanoes elsewhere might harm commercial or private energy production at distances of hundreds to thousands of kilometers from the volcano. Given that volcanic eruptions are frequent and the fact that the PV-industry is growing rapidly, negative impacts are expected in the future, requiring close tephra dispersion monitoring and PV-maintenance strategies.

  8. Characterising Complex Ice-Tephra Spatial Feedbacks of Post-Volcanic Eruption Glacial Ablation Using Terrestrial Laser Scanning

    NASA Astrophysics Data System (ADS)

    Vircavs, L.; Nield, J. M.; Chiverrell, R. C.; Darby, S. E.; Leyland, J.; Jacobs, B.

    2012-12-01

    Volcanic eruptions in glacio-volcanic regions regularly deposit significant quantities of volcanic ash (tephra) over nearby glaciers. This ash debris can remain for decades as it is transported through the system and has the ability to alter surface albedo, thermal insulation and ultimately surface roughness which can significantly modify the glacial response to climate perturbations. We used terrestrial laser scanning (TLS) to measure daily ice-ash surface interactions for a week in July 2011 following tephra fallout from the May 2011 Grímsvötn eruption onto Svínafellsjökull, Iceland. TLS is well suited to process studies and enabled repeat measurements to be collected of ice surface topography and signal absorption at high spatial resolution in three dimensions rather than traditional transect type studies. Our data confirm ablation rates either reduce or increase under thick (insulating) and thin (reduced albedo) ash deposits, respectively. Fourier transform analysis of the TLS data identified that a three-fold increase in aerodynamic roughness was attributable to an increase in larger (>0.2m) surface features. These surface features include micro cryoconite holes, debris cones and meltwater channels. Moreover, the temporal sequence of TLS measurements revealed the importance of ash redistribution by meltwater in generating differential melting which then modifies roughness and ash patchiness, such that the net effect of these spatial ash-ice feedbacks was to reduce ablation rates by up to 59%. This reduction in ablation rates despite increases in temperature and solar radiation was confirmed by manual stake measurements and is the reverse of modelled ablation trends without surficial ash. The modulating effects of these previously undocumented ash-ice feedbacks on ablation rates are, therefore, significant and must be correctly parameterized if ash-covered glacier mass balances are to be predicted correctly.

  9. Properties of ash-infused hail during the Grímsvötn 2011 eruption and implications for radar detection of volcanic columns

    NASA Astrophysics Data System (ADS)

    Arason, Þórður; Þorláksdóttir, Svava B.; Sigurðsson, Geirfinnur S.; Yeo, Richard F.; Thorsteinsson, Thorsteinn

    2013-04-01

    The latest Grímsvötn volcanic eruption in Iceland lasted for a week, 21-28 May 2011, while most of the tephra was erupted in the first 24 hours. During the early hours the volcanic column rose to about 20-25 km altitude. The Grímsvötn caldera is within the Vatnajökull glacier and most of the tephra was deposited on the glacier. Fortunately, for our study of ash-infused hail deposited from the column, the surface air temperatures on the glacier were below freezing level during the first few weeks after the eruption. In early June 2011 the ash deposits around the eruption site were studied, with special focus on thick distinct intermittent layers of ash-infused hail. Close-up photographs of the in-situ hail layers were taken and hail samples collected, some were kept frozen while others were allowed to melt. Most of the hail had grain sizes between 1 and 2 mm with various visual grades of ash density, from almost clear hail to ice-glaced spherical balls of packed fine ash. Both the ash and hail grain size distributions of the samples were analyzed as well as their water content. The much larger grain size of the hail than of the ash has important implications for some effective physical properties and remote detection of ash in volcanic columns. These changes in effective grain size lead to increased precipitation of ash, and affect radar reflectivity. The influence of hail formation in volcanic columns on mass flux estimates based on radar measurements will be discussed.

  10. Quantifying small-scale temporal surface change on glaciers and salt pans using terrestrial laser scanning: implications for modelling ablation and dust emission

    NASA Astrophysics Data System (ADS)

    Nield, J. M.; Wiggs, G. F. S.; Leyland, J.; Darby, S. E.; King, J.; Eckardt, F. D.; Chiverrell, R. C.; Vircavs, L. H.; Jacobs, B.

    2012-04-01

    Physical surface roughness is important in glacial and desert environments as it influences aerodynamic roughness, which in turn determines the ability of the wind to contribute to the turbulent heat flux component of the energy balance for glacial ice ablation or the likelihood of a surface emitting dust. Surface microtopography has traditionally been quantified by single 2D transects, but little is known about how these surfaces vary over time and the feedback between surface properties and other geomorphic processes. Terrestrial laser scanning (TLS) is the perfect tool to examine geomorphic microtopography over large spatial areas relatively quickly with the opportunity for repeat temporal measurements. Here we present examples of daily and weekly surface change measured on the Sua Pan, Botswana and the Svínafellsjökull, Iceland with mm accuracy using TLS. For the first time it is possible to quantify salt crust plucking and extrusion events and elucidate links between surface and wind shear interactions, as well as possible changes in aerodynamic roughness over time as surfaces evolve. Clear patterning is evident, with crust expansion limited to topographic highs. Likewise, we illustrate examples of measured daily ablation rates and patterns, and allude to implications for energy balance modelling by improving estimates of aerodynamic roughness. Specific ice patterning includes melt water eroding channels, the unique interactions of surface debris (volcanic ash from the 21 - 30 May 2011 eruption of Grímsvötn) melting out from the glacier and surface water forming a diverse microtopography of debris cones, cryoconite holes and perched blocks. However, whilst TLS represents a step-change in our ability to move from small transect derived roughness measurements to complete 3D surface change, detecting change on mobile surfaces through time is challenging, and linking surface properties to other point-based process measurements can be problematic.

  11. The Icelandic volcanic aeolian environment: Processes and impacts - A review

    NASA Astrophysics Data System (ADS)

    Arnalds, Olafur; Dagsson-Waldhauserova, Pavla; Olafsson, Haraldur

    2016-03-01

    Iceland has the largest area of volcaniclastic sandy desert on Earth or 22,000 km2. The sand has been mostly produced by glacio-fluvial processes, leaving behind fine-grained unstable sediments which are later re-distributed by repeated aeolian events. Volcanic eruptions add to this pool of unstable sediments, often from subglacial eruptions. Icelandic desert surfaces are divided into sand fields, sandy lavas and sandy lag gravel, each with separate aeolian surface characteristics such as threshold velocities. Storms are frequent due to Iceland's location on the North Atlantic Storm track. Dry winds occur on the leeward sides of mountains and glaciers, in spite of the high moisture content of the Atlantic cyclones. Surface winds often move hundreds to more than 1000 kg m-1 per annum, and more than 10,000 kg m-1 have been measured in a single storm. Desertification occurs when aeolian processes push sand fronts and have thus destroyed many previously fully vegetated ecosystems since the time of the settlement of Iceland in the late ninth century. There are about 135 dust events per annum, ranging from minor storms to >300,000 t of dust emitted in single storms. Dust production is on the order of 30-40 million tons annually, some traveling over 1000 km and deposited on land and sea. Dust deposited on deserts tends to be re-suspended during subsequent storms. High PM10 concentrations occur during major dust storms. They are more frequent in the wake of volcanic eruptions, such as after the Eyjafjallajökull 2010 eruption. Airborne dust affects human health, with negative effects enhanced by the tubular morphology of the grains, and the basaltic composition with its high metal content. Dust deposition on snow and glaciers intensifies melting. Moreover, the dust production probably also influences atmospheric conditions and parameters that affect climate change.

  12. The 1874-1876 volcano-tectonic episode at Askja, North Iceland: Lateral flow revisited

    NASA Astrophysics Data System (ADS)

    Hartley, Margaret E.; Thordarson, Thor

    2013-07-01

    The Askja volcanic system, North Iceland, experienced a volcano-tectonic episode between 1874 and 1876, the climax of which was a rhyolitic, phreatoplinian to Plinian eruption at Askja central volcano on 28-29 March 1875. Fissure eruptions also occurred in 1875, producing the Nýjahraun lava, 45-65 km north of Askja. The Nýjahraun basalt is indistinguishable, in terms of whole-rock major elements, from the small-volume basaltic eruptions that took place at Askja in the early 20th century. It has been suggested that all of these basalts originated from a shallow magma chamber beneath Askja, with the Nýjahraun eruptions being fed by northward-propagating lateral dykes. It has also been conjectured that the Holuhraun lava, located at the southern tip of the Askja volcanic system 15-25 km south of Askja, was connected with the 1874-1876 Askja volcano-tectonic episode. We re-examine these interpretations in light of new whole-rock, glass and melt inclusion analyses from samples collected along the length of the Askja volcanic system. Glasses from Nýjahraun and the Askja 20th century eruptions are geochemically distinct. We suggest that the Askja 20th century basalts mixed with evolved melts in the crust, while the Nýjahraun magma evolved without such interactions. The Holuhraun basalt is more similar to lavas erupted on the Bárðarbunga-Veiðivötn volcanic system than to postglacial basalts from Askja, indicating that particular geochemical signatures are not necessarily confined to the tectonic or structural surface expression of single volcanic systems. This has important implications for the identification and delineation of individual volcanic systems beneath the northwest sector of Vatnajökull.

  13. Breaking the Seal: Tracking Eruptive and Flood Tremor in Iceland with Seismic Arrays

    NASA Astrophysics Data System (ADS)

    Eibl, E. P. S.; Vogfjord, K. S.; Bean, C. J.; Ying, Y.; Pálsson, F.

    2015-12-01

    Bárðarbunga volcano in Iceland is located beneath Vatnajökull glacier. It erupted from August 29th, 2014 to February 27th, 2015 outside the ice cap after a ca. 50 km long dike had formed, mainly in the subsurface beneath the ice. Both the dike formation and the following effusive eruption were accompanied by continuous, harmonic tremor and tremor bursts. During the eruption these tremor bursts were interpreted as magma-ice interaction, flowing water and magma. This analysis was mainly based on the seismic frequency content and amplitude distributions on the regional seismic network. It was sometimes supported by the detection of cauldrons in the ice on subsequent days. Here we analyse the tremor using three seven-element arrays south- and northwest of the glacier cap (Jökulheimar, Innri Eyrar and Urðarháls). Using array analysis we can better constrain event locations, estimate tremor migration speed and use wavefield slowness tohelp estimate the source depth which can help to constrain the source type. We show that the backazimuths of the main harmonic tremor with dominant energy around 1 Hz correlate well with the extent of the growing lavafield for at least 27 days. Another one day long harmonic tremor episode contained energy up to 5 Hz but dominant at 1 to 2 Hz. The source was located beneath the ice and moved upwards and horizontally (about 42 deg). We compare it to tremor during smaller floods underneath the glacier and discuss a moving water or magma front as source. Elastic full wavefield simulations in models including ice thickness and ice basal topography allow us to strip out path effects thus yielding information about the tremor sources. Indications are that (i) parts of the dike were still evolving well after it had been breached by advancing magma and (ii) that eruptive lava is a significant source of seismic tremor.

  14. Using Volcanic Lightning Measurements to Discern Variations in Explosive Volcanic Activity

    NASA Astrophysics Data System (ADS)

    Behnke, S. A.; Thomas, R. J.; McNutt, S. R.; Edens, H. E.; Krehbiel, P. R.; Rison, W.

    2013-12-01

    VHF observations of volcanic lightning have been made during the recent eruptions of Augustine Volcano (2006, Alaska, USA), Redoubt Volcano (2009, Alaska, USA), and Eyjafjallajökull (2010, Iceland). These show that electrical activity occurs both on small scales at the vent of the volcano, concurrent with an eruptive event and on large scales throughout the eruption column during and subsequent to an eruptive event. The small-scale discharges at the vent of the volcano are often referred to as 'vent discharges' and are on the order of 10-100 meters in length and occur at rates on the order of 1000 per second. The high rate of vent discharges produces a distinct VHF signature that is sometimes referred to as 'continuous RF' radiation. VHF radiation from vent discharges has been observed at sensors placed as far as 100 km from the volcano. VHF and infrasound measurements have shown that vent discharges occur simultaneously with the onset of eruption, making their detection an unambiguous indicator of explosive volcanic activity. The fact that vent discharges are observed concurrent with explosive volcanic activity indicates that volcanic ejecta are charged upon eruption. VHF observations have shown that the intensity of vent discharges varies between eruptive events, suggesting that fluctuations in eruptive processes affect the electrification processes giving rise to vent discharges. These fluctuations may be variations in eruptive vigor or variations in the type of eruption; however, the data obtained so far do not show a clear relationship between eruption parameters and the intensity or occurrence of vent discharges. Further study is needed to clarify the link between vent discharges and eruptive behavior, such as more detailed lightning observations concurrent with tephra measurements and other measures of eruptive strength. Observations of vent discharges, and volcanic lightning observations in general, are a valuable tool for volcano monitoring, providing a

  15. Volcanic Lightning in Eruptions of Sakurajima Volcano

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  16. Electrification of Ash in Icelandic Volcanic Plumes

    NASA Astrophysics Data System (ADS)

    Nicoll, K.; Aplin, K. L.; Houghton, I.

    2014-12-01

    Volcanic ash is known to charge electrically, producing some of the most spectacular displays of lightning on the planet. Lightning activity within volcanic plumes can be sensed remotely using systems such as the United Kingdom Met Office long-range lightning detection network, ATDnet, which recorded over 16 000 lightning strokes during the 2011 Grimsvötn eruption in Iceland. These remote sensing techniques can only be fully exploited if the charging mechanisms in volcanic plumes are well understood. Although the exact details of ash charging processes will vary from one eruption to another, triboelectrification, fractoemission, and the ''dirty thunderstorm'' mechanism are all thought to play a role in the electrification of ash near the vent. In addition to near-vent charging, observations show that charging can also occur in volcanic plumes up to hundreds of kilometres from the source region. The sustained nature of this charge in the presence of electrically conducting air suggests that a self-charging mechanism through the action of ash-to-ash contact charging (triboelectrification), may also play a role in the electrification of volcanic ash. This work describes a laboratory investigation into triboelectric charging of ash from the 2010 and 2011 volcanic eruptions of Eyjafjallajökull and Grímsvötn in Iceland respectively. Consistently with previous work, we find that the particle size distribution plays an important role in the magnitude of charging generated, specifically in terms of the normalized span of the particle size distribution. As well as triboelectrificiation, natural radioactivity in some volcanic ash could also contribute to self-charging of volcanic plumes, which is also examined here.

  17. Recent results from the UnderVolc project: from the detection of long-term volcanic unrest processes to the imaging of dike propagation

    NASA Astrophysics Data System (ADS)

    Brenguier, F.; Rivemale, E.; Clarke, D. S.; Taisne, B.; Shapiro, N. M.; Battaglia, J.; Got, J.; Ferrazzini, V.; Tait, S.

    2010-12-01

    The April 2010 Eyjafjallajökull volcano eruption and the resulting major disruption to air travel across Europe showed that there is a constant need to develop novel methods to prospect and monitor volcanic areas. The UnderVolc (Understanding Volcanic processes) project's main objective is to shed light on seismogenic and volcanic processes by developing and applying novel seismological and geodetic data mining methods. The project gathers a task force of more than 30 international seismologists, volcano-seismologists and volcanologists. It is funded by the French Research Agency (2009-2012). The main task of the project is to provide high quality, dense, continuous seismic and gps data to the scientific community from one of the most active volcanoes in the world, namely Piton de la Fournaise on La Réunion island. We will present the analysis of 10 years of microseismicity at Piton de la Fournaise volcano. By clustering about 30 000 Volcano-Tectonic events, we image seismic asperities that are strongly sensitive to magma pressurization and can thus be considered as markers of volcanic unrest. We also present results of temporal seismic velocity changes from noise cross-correlations. Interestingly, we observe strong changes of seismic velocity not associated with eruptions at Piton de la Fournaise (PdF) volcano. We propose that these transient processes can be associated with deep magma feeding or magma intrusions without eruptions. We finally present a new method to image dike propagation using associated seismo-acoustic amplitudes recorded at different sensors. We observe complex dike propagation dynamics at PdF volcano which strongly differ from models of constant velocity dike propagation. This can probably be interpreted as the effects of, the heterogeneous volcanic edifice, strong topography, magma inversion of buoyancy and solidification.

  18. FPLUME-1.0: An integral volcanic plume model accounting for ash aggregation

    NASA Astrophysics Data System (ADS)

    Folch, Arnau; Costa, Antonio; Macedonio, Giovanni

    2016-04-01

    Eruption Source Parameters (ESP) characterizing volcanic eruption plumes are crucial inputs for atmospheric tephra dispersal models, used for hazard assessment and risk mitigation. We present FPLUME-1.0, a steady-state 1D cross-section averaged eruption column model based on the Buoyant Plume Theory (BPT). The model accounts for plume bending by wind, entrainment of ambient moisture, effects of water phase changes, particle fallout and re-entrainment, a new parameterization for the air entrainment coefficients and a model for wet aggregation of ash particles in presence of liquid water or ice. In the occurrence of wet aggregation, the model predicts an "effective" grain size distribution depleted in fines with respect to that erupted at the vent. Given a wind profile, the model can be used to determine the column height from the eruption mass flow rate or vice-versa. The ultimate goal is to improve ash cloud dispersal forecasts by better constraining the ESP (column height, eruption rate and vertical distribution of mass) and the "effective" particle grain size distribution resulting from eventual wet aggregation within the plume. As test cases we apply the model to the eruptive phase-B of the 4 April 1982 El Chichón volcano eruption (México) and the 6 May 2010 Eyjafjallajökull eruption phase (Iceland). The modular structure of the code facilitates the implementation in the future code versions of more quantitative ash aggregation parameterization as further observations and experiments data will be available for better constraining ash aggregation processes.

  19. Climate Throughout Geologic Time Has Been Controlled Primarily by the Balance Between Cooling Caused by Major Explosive Eruptions of Evolved Magmas Typical of Island Arcs and Warming Caused by Voluminous Effusive Eruptions of Basaltic Magma Typical of Subaerial Ocean Ridges and Island Chains

    NASA Astrophysics Data System (ADS)

    Ward, P. L.

    2014-12-01

    Most volcanic eruptions deplete ozone ~6% for a few years, allowing more high-energy, ultraviolet-B radiation to warm earth. Record low levels of total column ozone followed the 1991 explosive eruption of Pinatubo. Yet 6% depletion also followed the smaller and more effusive eruptions of Eyjafjallajökull (2010) and Grímsvötn (2011) in Iceland. Explosive volcanoes also eject 10-20 megatons of sulfur dioxide into the lower stratosphere, forming sulfuric-acid aerosols that reflect and diffuse sunlight causing a net cooling of ~0.5°C for 3 years. High rates of explosive volcanos cool earth into ice ages while high rates of effusive basaltic volcanism in Iceland between 11,500 and 9,500 years ago clearly warmed Earth out of the last ice age depositing sulfate recorded in ice cores in Greenland. Basalts from these eruptions are observed as tuyas in Iceland dated during this period. The 25 Dansgaard-Oeschger abrupt warmings are contemporaneous with increased sulfate in Greenland and with the few older dates available for tuyas in Iceland. Extensive flood basalts were formed during the Paleocene Eocene Thermal Maximum and during times of most major mass extinctions when global temperatures rose substantially, with fossil evidence for ozone depletion. Greenhouse-gas theory assumes electromagnetic radiation travels through space as waves and therefore thermal energy reaching earth is proportional to the square of wave amplitude. Thus the change in energy reaching Earth due to ozone depletion is considered small compared to infrared energy absorbed by greenhouse gases. But waves travel in matter and there is no matter in space. Electromagnetic energy is transmitted as frequency, as shown by radio signals, where energy equals frequency times the Planck constant. Thus thermal energy reaching earth when ozone is depleted is 50 times thermal energy involved in greenhouse gases. Global warming from 1970 to 1998 was caused primarily by 3% ozone depletion due to anthropogenic

  20. Investigating tension in the laboratory: Implications for volcanic processes

    NASA Astrophysics Data System (ADS)

    Wall, Richard; Lavallée, Yan; Kendrick, Jackie; Iddon, Fiona; Hornby, Adrian; Lamur, Anthony; von Aulock, Felix; Wadsworth, Fabian; Kilburn, Christopher; Browning, John; Meredith, Philip

    2015-04-01

    Tensile fracturing is an important process that occurs at divergent plate boundaries and can also be observed at convergent plate boundaries, where it accommodates compression. Owing to the difficulty of simulating tensile loading in the laboratory very few data exist on how rock fails in this mode and how this process changes with temperature and strain rate. To address this issue we present the results from a range of experiments that examine direct tension under controlled conditions. Experiments have been undertaken using basalt from the base of Eyjafjallajökull volcano and use a novel methodology of inducing tension through cooling. Initially, samples are heated above their solidus temperature and are allowed to expand within the apparatus. The samples are then locked in place and cooled at rates between 0.1 and 10 ° C.min-1, inducing tension within the sample. We compare results from these direct tension test with indirect tension Brazilian tests, using the same rock type, at different temperatures (between room temperature and 900° C) and at a compaction rate of 4 x 10-4 mm.s-1. From Brazilian tests the tensile strengths of samples are between 10 and 20 MPa, with an overall increase in strength with increasing temperature. Cooling induced tension experiments show that direct tensile strength is commonly 50 to 75 % of the strength under indirect tension conditions and that an increase in cooling rate generally decreases the strength of the samples. These experiments show a complex stress history during cooling, from the onset to completion of fracturing. Complementary experiments have also been undertaken on Seljadur basalt from Iceland, where acoustic emissions and seismic velocities indicate that the magnitude of thermal cracking is greater during cooling than heating. These initial results have significant implications for understanding the conditions required for tensile failure in the field and the controls on the formation of the resulting fracture.

  1. Testing the accuracy of a 1-D volcanic plume model in estimating mass eruption rate

    USGS Publications Warehouse

    Mastin, Larry G.

    2014-01-01

    During volcanic eruptions, empirical relationships are used to estimate mass eruption rate from plume height. Although simple, such relationships can be inaccurate and can underestimate rates in windy conditions. One-dimensional plume models can incorporate atmospheric conditions and give potentially more accurate estimates. Here I present a 1-D model for plumes in crosswind and simulate 25 historical eruptions where plume height Hobs was well observed and mass eruption rate Mobs could be calculated from mapped deposit mass and observed duration. The simulations considered wind, temperature, and phase changes of water. Atmospheric conditions were obtained from the National Center for Atmospheric Research Reanalysis 2.5° model. Simulations calculate the minimum, maximum, and average values (Mmin, Mmax, and Mavg) that fit the plume height. Eruption rates were also estimated from the empirical formula Mempir = 140Hobs4.14 (Mempir is in kilogram per second, Hobs is in kilometer). For these eruptions, the standard error of the residual in log space is about 0.53 for Mavg and 0.50 for Mempir. Thus, for this data set, the model is slightly less accurate at predicting Mobs than the empirical curve. The inability of this model to improve eruption rate estimates may lie in the limited accuracy of even well-observed plume heights, inaccurate model formulation, or the fact that most eruptions examined were not highly influenced by wind. For the low, wind-blown plume of 14–18 April 2010 at Eyjafjallajökull, where an accurate plume height time series is available, modeled rates do agree better with Mobs than Mempir.

  2. The Staring OBservations of the Atmosphere (SOBA) Mission Concept

    NASA Technical Reports Server (NTRS)

    Knobelspiesse, Kirk; Johnson, Matthew S.; Chen, Rick; Quincy, Allison; Fladeland, Matthew

    2016-01-01

    The Staring OBservations of the Atmosphere (SOBA) Mission is a concept that was developed and matured under the guidance of the NASA Ames Project EXellence (APEX) program. If funded, it will provide an unprecedented opportunity to improve ash transport forecasts and climate model simulations associated with volcanic eruptions. NASA and National science objectives require a better understanding of volcanic aerosol and trace gas emissions, transport, chemical transformation, and deposition, since they impact Earth's climate and atmospheric composition, human health, and aviation safety. Natural hazards such as the 2010 eruption of the Eyjafjallajökull volcano in Iceland demonstrated how existing remote-sensing assets were inadequate for individual volcanic event monitoring. During this eruption, available instruments were unable to provide data necessary to initialize volcanic plume transport models so that they could accurately predict the quantity and location of volcanic ash. As a result, thousands of flights around the world were grounded unnecessarily, at great expense. Volcanoes can also play a large role in regulation of the Earth's climate, so SOBA observations will also be used to evaluate and improve volcanic aerosol and trace gas simulation in chemical transport models (CTMs) and global climate models (GCMs). We propose the development of an airborne remote sensing concept and field campaign that will respond to an eruption and provide near real time observations of a volcanic plume, specifically ash injection height, transport, aerosol microphysical physical properties, and the location and concentration of sulfur dioxide (SO2) (sulfate (SO42-) aerosol precursor). This airborne system will utilize a depolarization sensitive, downward looking Light Detection And Ranging (lidar) instrument and an ultraviolet (UV) imaging spectrometer, and will provide data to be ingested by volcanic ash advisory models. Furthermore, the lessons learned in the development

  3. Uncertainties in Initial Plume Modeling: What is needed prior to a volcanic eruption?

    NASA Astrophysics Data System (ADS)

    Webley, P. W.; Dehn, J.

    2015-12-01

    Low-probability high-intensity volcanic events are likely to have the greatest impact on us all. Pre-event scenario planning can help us to understand the likelihood of event type, size and duration while observational data can be used, once an event occurs, as calibration/validation to the pre-event modeling. During the 2010 Eyjafjallajökull eruption uncertainty in initial plume dynamics and ash mass lead to significant variability in modeling the downwind ash clouds. To forecast the potential dispersal patterns from volcanic eruptions assumptions are made on eruption start time; initial plume dynamics; erupted mass; and erupted/dispersing particle size distributions. There is a need for pre-event inputs to the dispersion models used in operational ash cloud forecasting. There are a number of different initial plume models available and each has its own set of defined inputs that are needed to model the eruption plume. There is a need for updated rapidly produced scenarios daily at time of unrest and updated as soon as the event occurs. While validation with satellite data is key, the models can forecast ash in locations that could be below detection limits that are still relevant for mitigation strategies and aviation safety. So, are we sufficiently prepared to perform the number of initial plume modeling simulations to capture all the potential variability in the dispersion model inputs? Can a systematic approach be developed for application within the operational environment and for use by the volcanic ash advisory centers? Here we will present approaches to building a real-time workflow that encompasses the initial plume uncertainties and discuss how we as a community can develop tools to be implemented in an operational environment. The aim is to a build a complete system to provide the simulations of the ash cloud location and concentrations along with confidence levels that can then be used by the aviation community in their decision support systems.

  4. CGPS as a Tool to Measure Short-Term Mass Balance Variations of Icelandic Ice Caps

    NASA Astrophysics Data System (ADS)

    Compton, K. C.; Bennett, R. A.; Hreinsdottir, S.; van Dam, T. M.; Spada, G.

    2015-12-01

    As the global climate changes, understanding the variations in water storage is increasingly important. In Iceland, glaciers cover approximately 11% of the land surface and comprise the country's largest reservoir of freshwater. Seasonal variations in winter snowfall and summer melting can impact river discharge and water availability for utilities such as hydropower. A dense network of continuously operating GPS sites record rapid crustal uplift exceeding 30 mm/year and accelerations up to 1-2 mm/yr2 reflecting the recent accelerating ice mass loss from the major Icelandic ice caps. Additionally, CGPS records seasonal motion: the elastic response to annual snow and melt seasons. Amplitudes of vertical seasonal motion approach 10 mm for those sites in the Central Highlands region in close proximity to the Vatnajökull ice cap. We demonstrate the utility of CGPS-measured displacements for estimating seasonal ice mass changes using a simple least squares inversion. We utilize all 3 components of motion, taking advantage of the seasonal motion recorded in the horizontal. We remove secular velocities and accelerations as well as seasonal motions due to atmospheric, hydrologic, and non-tidal ocean loading. We model GPS noise as a flicker process and set the standard deviation for that noise to be 1 mm for the horizontal components and 3 mm for the vertical. We calculate unit responses to each of the 5 largest ice caps in central Iceland at each of the 62 CGPS locations using both the RELAX and REAR codes and investigate the impact that Earth's structure has on our modeling results, noting here that the standard PREM Earth model results in calculated displacements smaller than the observations by a factor of two. Our preliminary inversion results match available summer and winter mass balance measurements well. We are often able to reproduce the year-to-year variations in loading and melting within our calculated 95% confidence bounds.

  5. Detailed sedimentology and geomorphology elucidate mechanisms of formation of modern and historical sequences of minor moraines in the European Alps

    NASA Astrophysics Data System (ADS)

    Wyshnytzky, Cianna; Lukas, Sven

    2016-04-01

    moraines here formed as push moraines in two groups separated by a former proglacial basin and are composed dominantly of pre-existing proglacial outwash gravel through efficient bulldozing of the glacier front (Lukas, 2012). These findings show a range of mechanisms responsible for moraine formation. Furthermore, basal freeze-on processes incorporating subglacial sediment (till) have not been recorded in high-mountain moraine formation, suggesting a commonality of seasonal climatic controls between the glacier dynamics of high-mountain glaciers and those in more lowland, maritime settings. References Andersen, J.L., and Sollid, J.L., 1971, Glacial Chronology and Glacial Geomorphology in the Marginal Zones of the Glaciers, Midtdalsbreen and Nigardsbreen, South Norway: Norsk Geografisk Tidsskrift - Norwegian Journal of Geography, v. 25, no. 1, p. 1-38, doi: 10.1080/00291957108551908. Beedle, M.J., Menounos, B., Luckman, B.H., and Wheate, R., 2009, Annual push moraines as climate proxy: Geophysical Research Letters, v. 36, no. 20, p. L20501, doi: 10.1029/2009GL039533. Boulton, G.S., 1986, Push-moraines and glacier-contact fans in marine and terrestrial environments: Sedimentology, v. 33, p. 677-698. Evans, D.J.A., and Benn, D.I., 2004, A Practical Guide to the Study of Glacial Sediments: Hodder Education, London, United Kingdom. Hewitt, K., 1967, Ice-Front Deposition and the Seasonal Effect: A Himalayan Example: Transactions of the Institute of British Geographers, v. 42, p. 93-106. Kjær, K.H., and Krüger, J., 2001, The final phase of dead-ice moraine development: processes and sediment architecture, Kötlujökull, Iceland: Sedimentology, v. 48, p. 935-952. Krüger, J., 1995, Origin, chronology and climatological significance of annual-moraine ridges at Myrdalsjökull, Iceland: The Holocene, v. 5, no. 4, p. 420-427. Lukas, S., 2012, Processes of annual moraine formation at a temperate alpine valley glacier: insights into glacier dynamics and climatic controls: Boreas, v

  6. Forecast communication through the newspaper Part 1: Framing the forecaster

    NASA Astrophysics Data System (ADS)

    Harris, Andrew J. L.

    2015-04-01

    This review is split into two parts both of which address issues of forecast communication of an environmental disaster through the newspaper during a period of crisis. The first part explores the process by which information passes from the scientist or forecaster, through the media filter, to the public. As part of this filter preference, omission, selection of data, source, quote and story, as well as placement of the same information within an individual piece or within the newspaper itself, can serve to distort the message. The result is the introduction of bias and slant—that is, the message becomes distorted so as to favor one side of the argument against another as it passes through the filter. Bias can be used to support spin or agenda setting, so that a particular emphasis becomes placed on the story which exerts an influence on the reader's judgment. The net result of the filter components is either a negative (contrary) or positive (supportive) frame. Tabloidization of the news has also resulted in the use of strong, evocative, exaggerated words, headlines and images to support a frame. I illustrate these various elements of the media filter using coverage of the air space closure due to the April 2010 eruption of Eyjafjallajökull (Iceland). Using the British press coverage of this event it is not difficult to find examples of all media filter elements, application of which resulted in bias against the forecast and forecaster. These actors then became named and blamed. Within this logic, it becomes only too easy for forecasters and scientists to be framed in a negative way through blame culture. The result is that forecast is framed in such a way so as to cause the forecaster to be blamed for all losses associated with the loss-causing event. Within the social amplification of risk framework (SARF), this can amplify a negative impression of the risk, the event and the response. However, actions can be taken to avoid such an outcome. These actions

  7. Real-time GPS Monitoring of the 2014-2015 Bárðarbunga Rifting Event in Iceland

    NASA Astrophysics Data System (ADS)

    Fridriksdóttir, H. M.; Hreinsdottir, S.; Ofeigsson, B.; Sigmundsson, F.; Guðmundsson, G.; Söring, J.; Arnadottir, T.; Heimisson, E. R.; Gudmundsson, M. T.; Pálsson, F.; Magnússon, E.; Parks, M.; Hooper, A. J.; Dumont, S.; Grapenthin, R.; Bergsson, B. H.; Jónsson, T.; Kjartansson, V. S.; Steinthórsson, S.; Hjartardottir, A. R.; Drouin, V.

    2015-12-01

    On August 16, 2014 an intense seismic swarm originated below the eastern part of Bárðarbunga caldera. The seismicity migrated 50 km NNE until August 28 when the migration stopped 10 km south of Askja Volcano. This eventually lead to an eruption in Holuhraun, north of Dyngjujökull, which lasted nearly six months. The migration of seismicity coincided with displacements of continuous GPS (cGPS) stations, suggesting a lateral dyke formation in the Bárðarbunga volcanic system. The volume of the dyke was estimated in near-real time by modeling of geodetic displacements of GPS stations in the vicinity of Bárðarbunga. At the beginning of the swarm, there was only one cGPS station located conveniently enough to observe the dyke propagation. It was therefore evident that more cGPS stations were needed in order to get reliable estimates of the magma volume being intruded into the upper crust. Between August 20th 2014 and July 10th 2015, 14 new cGPS stations were added in the vicinity of Bárðarbunga. 24 hour GPS solutions weren't suitable enough to monitor the rapidly evolving events during the dyke propagation, so 8 hour solutions were implemented, giving deformation estimates three times each day. For a better visualisation of the developing activity, a map on the Icelandic Meteorological Office's website was made public, showing the rapid development of geodetic displacements and seismicity in near-real time. The 8 hour solutions were used to estimate the volume change of the magma source under Bárðarbunga and the dyke. A few days before the eruption in Holuhraun began on August 31, large earthquakes (>M5.0) started occurring in the caldera of Bárðarbunga and soon after, an ongoing collapse of the caldera was discovered. To monitor this subsidence, which ended up being about 66 meters, a GPS device was placed within the caldera. For the purpose of monitoring significant changes in the rate of caldera subsidence, the volume change of a spherical source beneath

  8. Models for regionalizing economic data and their applications within the scope of forensic disaster analyses

    NASA Astrophysics Data System (ADS)

    Schmidt, Hanns-Maximilian; Wiens, rer. pol. Marcus, , Dr.; Schultmann, rer. pol. Frank, Prof. _., Dr.

    2015-04-01

    The impact of natural hazards on the economic system can be observed in many different regions all over the world. Once the local economic structure is hit by an event direct costs instantly occur. However, the disturbance on a local level (e.g. parts of city or industries along a river bank) might also cause monetary damages in other, indirectly affected sectors. If the impact of an event is strong, these damages are likely to cascade and spread even on an international scale (e.g. the eruption of Eyjafjallajökull and its impact on the automotive sector in Europe). In order to determine these special impacts, one has to gain insights into the directly hit economic structure before being able to calculate these side effects. Especially, regarding the development of a model used for near real-time forensic disaster analyses any simulation needs to be based on data that is rapidly available or easily to be computed. Therefore, we investigated commonly used or recently discussed methodologies for regionalizing economic data. Surprisingly, even for German federal states there is no official input-output data available that can be used, although it might provide detailed figures concerning economic interrelations between different industry sectors. In the case of highly developed countries, such as Germany, we focus on models for regionalizing nationwide input-output table which is usually available at the national statistical offices. However, when it comes to developing countries (e.g. South-East Asia) the data quality and availability is usually much poorer. In this case, other sources need to be found for the proper assessment of regional economic performance. We developed an indicator-based model that can fill this gap because of its flexibility regarding the level of aggregation and the composability of different input parameters. Our poster presentation brings up a literature review and a summary on potential models that seem to be useful for this specific task

  9. Development of the atmospheric volcanic monitoring system in Iceland

    NASA Astrophysics Data System (ADS)

    Petersen, G. N.; Bjornsson, H.; Arason, P.; von Löwis, S.; Sigurøsson, G. S.; Karlsdóttir, S.

    2012-04-01

    The development of the atmospheric volcanic plume monitoring system has escalated since the eruption of Eyjafjallajökull in 2010. Radars provide a near-real time capability to observe volcanic eruptions both day and night. At high latitudes this is important, over the darkest periods of winter when radar and satellite images are the only means of measurements. Also weather conditions can be such at any time of the year that they obscure observations from survey flights and even from satellites. Prior to and during the 39 days eruption in 2010 only one operational radar was installed in Iceland, the fixed C-band radar at Keflavík International Airport. The main purpose of this radar is weather monitoring but it can simultaneously be used for volcanic plume monitoring within a radius of 480 km. The radar has been used for plume monitoring since 1991 when an eruption started in Hekla, only a few days after the installation of the radar. Since November 2010 a X-band dual polarization radar has been on loan from the Italian Civil Protection Agency to the Icelandic Meteorological Office (IMO) and during the eruption in Grímsvötn in 2011 the combined system, together with visual observations, gave a good picture of the eruption. Also, in cooperation with the UK National Centre for Atmospheric Science (NCAS) a Lidar has been operating in South-Iceland since May 2011. The Lidar was moved to Keflavík airport during the Grímsvötn eruption to monitor the atmosphere above the airport and assist in decision making regarding openings and closures of the airport. In 2012 a second fixed position C-band weather radar will be installed in East-Iceland. This means that the geophysically active region in both south and northeast of Iceland will be covered. In addition, the International Civil Aviation Organization (ICAO) has financed two X-band mobile radars to be installed and used in Iceland, solely for volcanic plume monitoring, with the first one becoming operational in

  10. A space-borne, multi-parameter, Virtual Volcano Observatory for the real-time, anywhere-anytime support to decision-making during eruptive crises

    NASA Astrophysics Data System (ADS)

    Ferrucci, F.; Tampellini, M.; Loughlin, S. C.; Tait, S.; Theys, N.; Valks, P.; Hirn, B.

    2013-12-01

    Tair, Erta Ale, Manda Hararo, Dalafilla, Nabro, Ol Doinyo Lengai, Nyiamulagira, Nyiragongo, Etna, Stromboli, Eyjafjallajökull, Grimsvötn, Soufriere Hills) showing radiant fluxes above ~0.5 GW and/or SO2 columns in excess of ~6 DU. Porting of automated thermal algorithms on MTSAT's JAMI (orbiting at 145°E) was developed on the eruptions of Merapi, Semeru Kliuchevskoi, Bezymianny and Shiveluch in 2006-2007, calibrated on the frequent activity of Batu Tara, and demonstrated on the 2012-2013 large eruption of Tolbachik.

  11. Intraglacial volcanism in the Western Volcanic Zone, Iceland

    NASA Astrophysics Data System (ADS)

    Jakobsson, S. P.; Johnson, G. L.

    2012-07-01

    The Western Volcanic Zone in Iceland (64.19° to 65.22° N) has the morphological characteristics of a distinct Mid-Atlantic ridge segment. This volcanic zone was mapped at a scale of 1:36.000, and 258 intraglacial monogenetic volcanoes from the Late Pleistocene (0.01-0.78 Ma) were identified and investigated. The zone is characterized by infrequent comparatively large volcanic eruptions and the overall volcanic activity appears to have been low throughout the Late Pleistocene. Tholeiitic basaltic rocks dominate in the Western Volcanic Zone with about 0.5 vol. % of intermediate and silicic rocks. The basalts divide into picrites, olivine tholeiites, and tholeiites. Three main eruptive phases can be distinguished in the intraglacial volcanoes: an effusive deep-water lava phase producing basal pillow lavas, an explosive shallow-water phase producing hyaloclastites and an effusive subaerial capping lava phase. Three evolutionary stages therefore charcterize these volcanoes; late dykes and irregular minor intrusions could be added as the fourth main stage. These intrusions are potential heat sources for short-lived hydrothermal systems and may play an important role in the final shaping of the volcanoes. Substantial parts of the hyaloclastites of each unit are proximal sedimentary deposits. The intraglacial volcanoes divide into two main morphological groups, ridge-shaped volcanoes, i.e., tindars (including pillow lava ridges) and subrectangular volcanoes, i.e., tuyas and hyaloclastite or pillow lava mounds. The volume of the tuyas is generally much larger than that of the tindars. The largest tuya, Eiríksjökull, is about 48 km3 and therefore the largest known monogenetic volcano in Iceland. Many of the large volcanoes, both tuyas and tindars, show a similar, systematic range in geochemistry. The most primitive compositions were erupted first and the magmas then changed to more differentiated compositions. The ridge-shaped tindars clearly erupted from volcanic

  12. Multiple subglacial till deposition: A modern exemplar for Quaternary palaeoglaciology

    NASA Astrophysics Data System (ADS)

    Evans, David J. A.; Roberts, David H.; Evans, Sian C.

    2016-08-01

    The sedimentology of a vertical succession of alternating beds of massive and fissile diamictons on a þorisjökull plateau icefield outlet foreland is employed to assess the evolution of subglacial traction tills at the margins of active temperate glaciers with deformable substrates, where tills appear to form sub-marginal incrementally thickened wedges that display multiple till emplacement events, potentially of annual scale. Lodged boulders display strong A-axes and surface striae alignments which parallel surface flutings, indicating that fluting construction and till emplacement were related to moulding by consistent glacier flow from the SSW during the Little Ice Age. In contrast, clast macrofabrics at the sub-boulder size, not unlike those reported from other Icelandic tills, are not as strong as would be expected in a subglacially sheared medium, indicating shear strains too low for a steady state strain signature. This separation of fabric data has isolated the strain signatures of the lodgement and deformation components of subglacial traction till, whereby the orientations of the largest, lodged clasts record high cumulative shear strains and those of the sub-boulder sized clasts record greater susceptibility to deformation of their enclosing matrix. This is likely due to the effect of clast collisions in clast rich till and the perturbations set up by the numerous large boulders, consistent with observations on till fabrics in flutings and around lodged clasts. A/B plane macrofabric data display unusually high degrees of isotropy, reflective of the more variable orientations of A/B planes, which are thought to reflect A/B plane susceptibility to dip parallel or anastomosing shear planes. A wide range of clast angularity values reflects the localized input of freshly plucked and hence relatively highly angular blocks to the deforming layer, a characteristic of stepped bedrock profiles beneath the snouts of mountain glaciers. Finally, we hypothesize that

  13. Constraints on seasonal load variations and regional rigidity from continuous GPS measurements in Iceland, 1997-2014

    NASA Astrophysics Data System (ADS)

    Drouin, Vincent; Heki, Kosuke; Sigmundsson, Freysteinn; Hreinsdóttir, Sigrún; Ófeigsson, Benedikt G.

    2016-06-01

    Two types of signals are clearly visible in continuous GPS (cGPS) time-series in Iceland, in particular in the vertical component. The first one is a yearly seasonal cycle, usually sinusoid-like with a minimum in the spring and a maximum in the fall. The second one is a trend of uplift, with higher values the closer the cGPS stations are to the centre of Iceland and ice caps. Here, we study the seasonal cycle signal by deriving its average at 71 GPS sites in Iceland. We estimate the annual and semi-annual components of the cycle in their horizontal and vertical components using a least-squares adjustment. The peak-to-peak amplitude of the cycle of the vertical component at the studied sites ranges from 4 mm near the coastline up to 27 mm at the centre of the Vatnajökull, the largest ice cap in Iceland. The minimum of the seasonal cycle occurs earlier in low lying areas than in the central part of Iceland, consistent with snow load having a large influence on seasonal deformation. Modelling shows that the seasonal cycle is well explained by accounting for elastically induced surface displacements due to snow, atmosphere, reservoir lake and ocean variations. Model displacement fields are derived considering surface loads on a multilayered isotropic spherical Earth. Through forward and inverse modelling, we were able to reproduce a priori information on the average seasonal cycle of known loads (atmosphere, snow in non-glaciated areas and lake reservoir) and get an estimation of other loads (glacier mass balance and ocean). The seasonal glacier mass balance cycle in glaciated areas and snow load in non-glaciated areas are the main contributions to the seasonal deformation. For these loads, induced seasonal vertical displacements range from a few millimetres far from the loads in Iceland, to more than 20 mm at their centres. Lake reservoir load also has to be taken into account on local scale as it can generate up to 20 mm of vertical deformation. Atmosphere load and

  14. Integration between Satellite and Ground-Based Data for the Improvement of Volcanic Ash Retrievals and Eruption Characterization

    NASA Astrophysics Data System (ADS)

    Corradini, S.; Merucci, L.; Marzano, F. S.; Montopoli, M.; Vulpiani, G.; Ricci, M.; Guerrieri, L.; Pugnaghi, S.; Scollo, S.; Coltelli, M.; Stramondo, S.

    2014-12-01

    Due to the large emission of gas and ash particles into the atmosphere, volcanic eruptions are among the most important sources of natural pollution. The size, density and shape of volcanic ash particles determine their residence time in the atmosphere that varies from minutes (for particles with radius larger than 100 μm) to weeks (for particles smaller than 10 μm). The interest in determining the abundances of these particles is high because of their effects on the environment, climate, public health and aviation. A practical consequence after the recent 2010 Eyjafjallajökull (Iceland) eruption, was the introduction of a volcanic ash concentration threshold to reduce the level of flight disruption whilst ensuring the passenger safety. This requirement forces the scientific community to develop novel techniques to obtain reliable results in real time. On the other hand, from the research point of view, an accurate estimation of the volcanic ash emissions can also yield insights into magmatic processes which control volcanic activity during the eruptive phases.Worldwide volcanic activity is observed with a variety of ground and space-based instruments that offer advantages and drawbacks. Because doesn't exist a single system able to give a comprehensive description of a particular phenomenon, an integrated approach based on the use of different types of remote sensing data is required. This approach is the core of the Multi-platform volcanic Ash Cloud Estimation (MACE) procedure that will be developed within the European FP7-APHORISM project.In this is work the measurements obtained from the geostationary MSG-SEVIRI, the polar Terra/Aqua MODIS and the ground-based weather RADAR instruments are integrated thus blending infrared and microwave ash estimation techniques from space and ground platforms. The expected outcomes are the improvements of the volcanic ash retrievals (mass, aerosol optical depth, effective radius, concentration, size distribution, cloud

  15. Inter-Rifting and Inter-Seismic Strain Accumulation in a Propagating Ridge System: A Geodetic Study from South Iceland

    NASA Astrophysics Data System (ADS)

    Travis, M. E.; La Femina, P. C.; Geirsson, H.

    2012-12-01

    The Mid-Atlantic Ridge, a slow spreading (~19 mm/yr) mid-ocean ridge boundary between the North American and Eurasian plates, is exposed subaerially in Iceland as the result of ridge-hotspot interaction. Plate spreading in Iceland is accommodated along neovolcanic zones comprised of central volcanoes and their fissure swarms. In south Iceland plate motion is partitioned between the Western Volcanic Zone (WVZ) and Eastern Volcanic Zone (EVZ). The EVZ is propagating to the southwest, while the WVZ is dying out from the northeast. Plate motion across both systems has been accommodated by repeated rifting events and fissure eruptions. In this study we investigate whether the WVZ is active and accumulating strain, and how strain is partitioned between the WVZ and EVZ. We also test how strain is accumulating along fissure swarms within the EVZ (i.e. is strain accumulation localized to one fissure swarm, or are multiple systems active?). We use GPS data and elastic block models run using the program DEFNODE to investigate these issues. GPS data are processed using the GIPSY-OASIS II software, and have been truncated to the 2000.5-2011 time period to avoid co-seismic displacement from the two June 2000 South Iceland Seismic Zone earthquakes. We also truncate the time series for sites within 20 km of Eyjafjallajökull to the beginning of 2010 to eliminate deformation associated with the March 2010 eruption of that volcano. We correct for co-seismic displacement from the two May 2008 SISZ earthquakes, inflation at Hekla volcano and the horizontal component of glacial isostatic rebound (GIA). Our best-fit model for inter-rifting and inter-seismic elastic strain accumulation suggests 80-90% of spreading is accommodated in the EVZ with the other 10-20% accommodated by the WVZ. The best-fit location of the EVZ is between Veidivotn and Lakigigar in an area of no Holocene volcanic activity. We suggest the WVZ is only active at Hengill and its associated fissure swarm. Geologic and

  16. Putative eskers and new insights into glacio-fluvial depositional settings in southern Argyre Planitia, Mars

    NASA Astrophysics Data System (ADS)

    Bernhardt, H.; Hiesinger, H.; Reiss, D.; Ivanov, M.; Erkeling, G.

    2013-09-01

    We present new insights into possible formation mechanisms and implications for previously identified landforms of putative glacio-fluvial origin along the southern rim of the Argyre basin on Mars. We compiled a detailed geomorphologic map of the study area and conducted morphometric and stratigraphic analyses of specific features, e.g., esker-like sinuous ridges on layered terrain. Based on their morphology and orientations, we subdivided the sinuous ridges on the southern Argyre basin floor into two populations, which could reflect changing conditions of glacial retreat. With the transition and oblique path methods we quantified the ice thickness of the glacier under which the first, lesser degraded, population of ridges probably formed. Our results imply an ice sheet thickness of ~2 km and at least ~100,000-150,000 km³ of ice on the southern floor of the Argyre basin during the time those ridges were deposited (>30× the volume of Vatnajökull, Iceland). The second population of ridges is more degraded and shows layers occasionally extending into the surrounding layered terrain. Comparisons with the morphology surrounding the Piedmont-style Malaspina Glacier in Alaska show similarities, suggesting population II formed during a glacial retreat involving back- and downwasting of stagnant ice lying beneath fresh outwash sediments, creating degraded and layered lag deposits around the emerging eskers. If outwash sediments were fed by the same drainage source as the eskers, sections of layers can extend from a given ridge into the surrounding deposits. The differences between the two ridge populations are probably a result of the subglacial drainage direction changing from northward to north-eastward around 3.6 Ga ago. This was likely coupled with the deposition of less or no outwash sediments resulting in a decrease of lag deposits. A subsequent phase of stagnant glacial retreat left no terminal moraines and largely preserved the population I ridges, thus implying

  17. Development and validation of a 3D Lattice Boltzmann model for volcano aeroacoustics

    NASA Astrophysics Data System (ADS)

    Brogi, Federico; Bonadonna, Costanza; Ripepe, Maurizio; Chopard, Bastien; Malaspinas, Orestis; Latt, Jonas; Falcone, Jean-Luc

    2015-04-01

    for running more realistic simulations. 3D LB model simulations for turbulent jet aeroacoustics have been accurately validated. Both mean flow and acoustic results are in good agreement with theory and experimental data available in literature. Xu H., Sagaut P., (2013), Analysis of the absorbing layers for the weakly-compressible lattice Boltzmann methods. J. Comput. Physic 245, 14-42. Lagrava D., Malaspinas O., Lätt J. (2012), Advances in multi-domain lattice Boltzmann grid refinement. J. Comput. Physics 231, 14, 4808-4822. Ripepe, M., C. Bonadonna, A. Folch, D. Delle Donne, G. Lacanna, E. Marchetti, and A. Höskuldsson (2013), Ash-plume dynamics and eruption source parameters by infrasound and thermal imagery: The 2010 Eyjafjallajökull eruption, Earth Planet. Sci. Lett., 366, 112-12.

  18. Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS) experiment: design, execution and science overview

    NASA Astrophysics Data System (ADS)

    Palmer, P. I.; Parrington, M.; Lee, J. D.; Lewis, A. C.; Rickard, A. R.; Bernath, P. F.; Duck, T. J.; Waugh, D. L.; Tarasick, D. W.; Andrews, S.; Aruffo, E.; Bailey, L. J.; Barrett, E.; Bauguitte, S. J.-B.; Curry, K. R.; Di Carlo, P.; Chisholm, L.; Dan, L.; Forster, G.; Franklin, J. E.; Gibson, M. D.; Griffin, D.; Helmig, D.; Hopkins, J. R.; Hopper, J. T.; Jenkin, M. E.; Kindred, D.; Kliever, J.; Le Breton, M.; Matthiesen, S.; Maurice, M.; Moller, S.; Moore, D. P.; Oram, D. E.; O'Shea, S. J.; Owen, R. Christopher; Pagniello, C. M. L. S.; Pawson, S.; Percival, C. J.; Pierce, J. R.; Punjabi, S.; Purvis, R. M.; Remedios, J. J.; Rotermund, K. M.; Sakamoto, K. M.; da Silva, A. M.; Strawbridge, K. B.; Strong, K.; Taylor, J.; Trigwell, R.; Tereszchuk, K. A.; Walker, K. A.; Weaver, D.; Whaley, C.; Young, J. C.

    2013-02-01

    We describe the design and execution of the BORTAS (Quantifying the impact of BOReal forest fires on Tropospheric oxidants using Aircraft and Satellites) experiment, which has the overarching objective of understanding the chemical aging of airmasses that contain the emission products from seasonal boreal wildfires and how these airmasses subsequently impact downwind atmospheric composition. The central focus of the experiment was a two-week deployment of the UK BAe-146-301 Atmospheric Research Aircraft (ARA) over eastern Canada. The planned July 2010 deployment of the ARA was postponed by 12 months because of activities related to the dispersal of material emitted by the Eyjafjallajökull volcano. However, most other planned model and measurement activities, including ground-based measurements at the Dalhousie University Ground Station (DGS), enhanced ozonesonde launches, and measurements at the Pico Atmospheric Observatory in the Azores, went ahead and constituted phase A of the experiment. Phase B of BORTAS in July 2011 included the same measurements, but included the ARA, special satellite observations and a more comprehensive measurement suite at the DGS. The high-frequency aircraft data provided a comprehensive snapshot of the pyrogenic plumes from wildfires. The coordinated ground-based and sonde data provided detailed but spatially-limited information that put the aircraft data into context of the longer burning season. We coordinated aircraft vertical profiles and overpasses of the NASA Tropospheric Emission Spectrometer and the Canadian Atmospheric Chemistry Experiment. These space-borne data, while less precise than other data, helped to relate the two-week measurement campaign to larger geographical and longer temporal scales. We interpret these data using a range of chemistry models: from a near-explicit gas-phase chemical mechanism, which tests out understanding of the underlying chemical mechanism, to regional and global 3-D models of atmospheric

  19. The Role of Convective Instabilities from Ash Clouds in Proximal Deposition of Fine Ash

    NASA Astrophysics Data System (ADS)

    Manzella, I.; Bonadonna, C.; Phillips, J.; Monnard, H.

    2014-12-01

    Gravitational instabilities forming at the bottom of spreading volcanic clouds have been observed in many explosive eruptions. They can generate vertical fingers which have been observed to have higher concentrations than the associated plumes. Characterization of volcanic fingers only relies on qualitative observations and quantitative analysis of dedicated experiments. For the first time we present a quantitative description of volcanic fingers developed during the Eyjafjallajökull 2010 eruption (Iceland) as a combination of video imaging and deposit observations. We conclude that the observed fingers on May 4th, 2010 moved downwards at a speed of 1±0.5 m s-1 and were advected laterally by the local wind at a similar speed as the associated cloud (e.g. about 8.5±0.8 m s-1). They continuously formed at the base of the cloud from about 1.4 km from the vent, with an average width and spacing of 168±26 m and 180±60 m, respectively. We could also correlate the sedimentation of fingers with observations of various types of particles aggregates with calculated velocities ranging between 0.1 and 7 m/s. We conclude that the aggregates with the largest terminal velocities sedimented independently of the fingers, while smaller aggregates could form either in the cloud or in the fingers. We have complemented our field data with dedicated experiments in order to investigate the evolution of particle concentration in the mixing region that results from propagation of turbulent convective instabilities. The experimental configuration was similar to that of previous studies with an aqueous suspension of water and spherical glass beads initially overlying a lower density sugar solution. Experiments demonstrate that once fingers are developed, they control sedimentation. In fact, particles are embedded in the fluid and cannot settle individually. This confirms that when settling driven instabilities is the dominating dynamics, particles are likely to settle faster following

  20. The vertical distribution of volcanic SO2 plumes measured by IASI

    NASA Astrophysics Data System (ADS)

    Carboni, Elisa; Grainger, Roy; Mather, Tamsin A.; Pyle, David M.; Thomas, Gareth; Siddans, Richard; Smith, Andrew; Dudhia, Anu; Koukouli, MariLiza; Balis, Dimitris

    2015-04-01

    Sulphur dioxide (SO2) is an important atmospheric constituent that plays a crucial role in many atmospheric processes. For example the current hiatus in global warming has been suggested to be caused by low level (< 15 km) volcanic activity (Ridley et al., 2014). Volcanic eruptions are a significant source of atmospheric SO2 and its effects and lifetime depend on the SO2 injection altitude. In the troposphere SO2 injection leads to the acidification of rainfall while in the stratosphere it oxidises to form a stratospheric H2SO4 haze that can affect climate for several years. The Infrared Atmospheric Sounding Instrument (IASI) on the Metop satellite can be used to study volcanic emission of SO2 using high-spectral resolution measurements from 1000 to 1200 cm-1 and from 1300 to 1410 cm-1 (the 7.3 and 8.7 μm SO2 bands). The scheme described in Carboni et al. (2012) has been applied to measure volcanic SO2 amount and altitude for 14 explosive eruptions from 2008 to 2012. The work includes a comparison with independent measurements: (i) the SO2 column amounts from the 2010 Eyjafjallajökull plumes have been compared with Brewer ground measurements over Europe; (ii) the SO2 plumes heights have been compared with CALIPSO backscatter profile. The results of the comparisons show that IASI SO2 measurements are not affected by underling cloud and are consistent (within the retrieved errors) with the other measurements considered. The series of analysed eruptions (2008 to 2012) show that the biggest contributor of volcanic SO2 was Nabro, followed by Kasatochi and Grímsvötn. Our observations also show a tendency of the volcanic SO2 to be injected to the level of tropopause during many explosive eruptions. For the eruptions observed, this tendency was independent of the maximum amount of SO2 erupted (e.g., 0.2 Tg for Dalafilla compared with 1.6 Tg for Nabro) and of the volcanic explosive index (between 3 and 5).

  1. Reconstruction of flux and altitude of volcanic SO2 emissions from satellite observations: implications for volcanological and atmospherical studies.

    NASA Astrophysics Data System (ADS)

    Boichu, Marie; Clarisse, Lieven; Péré, Jean-Christophe; Herbin, Hervé; Goloub, Philippe; Thieuleux, François; Khvorostyanov, Dmitry; Ducos, Fabrice; Clerbaux, Cathy; Tanré, Didier

    2016-04-01

    Volcanic sulphur dioxide (SO2) degassing is a crucial indicator of the sub-surface volcanic activity, which is widely used today for volcano monitoring and hazard assessment purposes. Volcanic SO2 is also important regarding atmospherical studies. More easily detectable from space, SO2 can be used as a proxy of the presence of ash to anticipate air traffic issues caused by explosive eruptions. Moreover, volcanic SO2 strongly impacts air quality but also climate following its conversion to radiatively-active sulphate aerosols. However, the accurate assessment of these various impacts is currently hampered by the poor knowledge of volcanic SO2 emissions, which can substantially vary with time, in terms of flux and altitude. To fulfil this need, we propose a strategy relying on satellite observations, which consequently allows for monitoring the eruptive activity of any remote volcano. The method consists in assimilating snapshots of the SO2 load, provided by infrared or ultraviolet satellite observations, in an inversion scheme that involves the use of a chemistry-transport model to describe the dispersion of SO2 released in the atmosphere. Applied on Eyjafjallajökull (Iceland) and Etna (Italy) eruption case-studies, this procedure allows for retrospectively reconstructing both the flux and altitude of the SO2 emissions with an hourly resolution. We show the improvement gained in the simulations and forecasts of the location and mass load of volcanic SO2 clouds using such a detailed reconstruction of emissions. For calibration-validation purpose, we compared our satellite-derived time-series of the SO2 flux with ground-based observations available on Etna. This comparison indicates a good agreement during ash-poor phases of the eruption. However, large discrepancies are observed during the ash-rich paroxysmal phase as a result of enhanced plume opacity affecting ground-based ultraviolet spectroscopic retrievals. Therefore, the SO2 emission rate derived from the

  2. High-Resolution Multibeam Survey of glacier-dominated lake Hvitarvatn in Central Iceland

    NASA Astrophysics Data System (ADS)

    Geirsdottir, A.; Miller, G. H.; Wattrus, N.; Thors, K.

    2005-12-01

    Historical records document the dramatic impact of the Little Ice Age (LIA) cooling on Iceland where in most cases the LIA moraines represent the most advanced ice margins since regional deglaciation. One of the sites reflecting this cooling is lake Hvarvatn, which sits beneath Langjökull the second largest ice cap in Iceland. Little Ice age moraines are prominent around two Langjokull outlet glaciers that calved into the lake at the peak of the LIA. Long cores recovered from the lake with the GLAD-200 drill rig in 2003 show abundant ice-rafted debris during the latest Holocene, and seismic profiles surveyed in 2001 show evidence of large-scale mass movement associated with the LIA moraines. To better evaluate the impact of LIA outlet glaciers on sedimentation in the lake we collected high-resolution multibeam bathymetric data from Hvarvatn in 2005. Combined with seismic reflection profiles and sediment core data from the lake, the multibeam data enhance our understanding of sediment distribution and processes in the lake during the Holocene and particularly during the Little Ice Age. In the primary depositional center in the lake 55 m of sediment have accumulated since deglaciation. The Little Ice Age moraines form prominent ridges into the mid lake extending approx. 1500 m away from the current margin. The deepest part of the lake is between the extant glacier margin and the LIA moraines, although also featuring several morainal ridges, which reflect the stepwise retreat of the outlet glaciers in the 20th century. Packets of sediment gravity flows not present in the more distant deeper basin characterize the lake-ward side of the moraines. Beyond the moraines several bedrock ridges protrude from the lake bottom up to ca. 30 m water depth, and they are capped by 15 m of stratified sediment. The multibeam survey shows ice-berg scour marks, some up to 5 m deep in the upper sediment layers. The relatively smooth sediment cover of the shallower basin near the

  3. The Nd-isotopic fingerprinting of North Atlantic water masses and its influences from local sources such as Iceland

    NASA Astrophysics Data System (ADS)

    Frank, N.; Waldner, A.; Christophe, C.; Montagna, P.; Dubois-Dauphin, Q.; Wu, Q.

    2014-12-01

    The 143Nd/144Nd ratio of seawater has become a valuable tracer of north Atlantic circulation patterns, driven by continental runoff, boundary exchange and water mass advection and mixing. A region of particular interest is the overflow across the Iceland - Scotland Ridge injecting water from the Arctic Ocean into the Iceland basin. However, Iceland itself constitutes a singularity in terms of the release of radiogenic 143Nd/144Nd to seawater, due to leaching of young volcanic basalts, whereas the Atlantic is dominated by less radiogenic Nd inputs from old Canadian crustal rocks and the European continent. Hence, release of volcanic material may affect the Nd-isotopic composition of water masses recirculating throughout the sub-polar gyre. This is of major importance regarding the use of Nd isotopes in sediments and corals to trace changes of recirculation patterns in the past. Here, seawater was analysed on three transects (local to basin scale) to fingerprint advection patterns as well as local radiogenic Nd sources in the sub-polar gyre domain. The first local transect followed open ocean water on to the shelf near the outflow of the Vatnajökull glacier. It demonstrates that freshwater runoff modifies the open ocean Nd signature only very close to the shelf (<40km near the outflow) and thus reflects a very local feature unlikely possible to alter the predominant water mass composition of Northeast Atlantic water or the underlying Iceland-Scotland Overflow Water. The second transect follows the Iceland shelfbreak from north-east towards the Reykjanes ridge and includes seawater samples near the recently formed volcanic island of Surtsey. Again no major modification of the Atlantic water mass compositions is observed, besides samples in direct vicinity of Surtsey island where local release of Nd modifies seawater ɛNd (-14) to values as high as -6. Finally we have monitored the isotopic composition of water masses along a North-South transect from Iceland towards

  4. Ten Years Record of Decreasing Heat Output From the Hyaloclastite Ridge Formed in the 1996 Gjalp Eruption

    NASA Astrophysics Data System (ADS)

    Gudmundsson, M. T.; Jarosch, A. H.; Högnadottir, T.

    2006-12-01

    The Gjálp eruption in 1996 formed a 6 km long and 500 m high subglacial hyaloclastite ridge. During the eruption a large depression was formed in the surface of the Vatnajökull ice cap as ice was melted and the meltwater drained away from the eruption site. Ice flow measurements and surface depression mapping have been done annually since the eruption, allowing inflow of ice and volume changes of the depression to be monitored. Taking into account the surface mass balance, these data can be used to estimate heat output from the subglacial ridge. The inflow of ice into the depression mainly from the north is an important part of the overall mass balance budget and was estimated combining surface velocities measurements with numerical 2D, full Stokes, ice flow models. In the first year after the eruption a heat flux of several thousand megawatts was estimated. The heat output decreased to several hundred MW in 1998 and this order of magnitude persisted until 2002. However after 2002 the mountain cooled down and from 2002 to 2005 heat output of the order 101 MW was obtained. These results indicate a 5 - 6 years period with major geothermal activity in the ridge, while in the last 4 years the ridge appears to be much colder. Since the ridge is fully covered by ice, no direct measurements of observations are available to explain this thermal record. Ridges of similar size and shape to that of Gjálp are a prominent feature of the volcanic zones in Iceland. A prominent part of these ridges are consolidated hyaloclastite, formed by alteration of the volcanic glass into palagonite. The rate at which this alteration takes place for ridges formed in short-lived subglacial eruptions is unknown. However, in most cases they have acquired considerable consolidation before glacial erosion could remove the initially unconsolidated hyaloclastite pile. In the oceanic island of Surtsey formed in 1963-1967, the rate of alteration was temperature dependent and took a few years. It is

  5. Eruption Source Parameters for Recent Icelandic Eruptions and Their Implications for Duration and Termination of Events

    NASA Astrophysics Data System (ADS)

    Thordarson, T.

    2015-12-01

    Since 1947, Iceland has featured 26 volcanic eruptions (2.5 eruptions/year). These include events at the central volcanoes Hekla, Eyjafjallajökull, Grímsvötn and Askja and the fissure eruptions of Surtsey 1963-67 and Nornahraun 2014-15. Of these, 11 are effusive, 8 are mixed (explosive to effusive) and 6 are within-glacier events. Surtsey is the only emergent submarine event (1309 days; 1 km3). Duration of effusive eruptions spans 0.3 to 181 days, with volume, average and peak magma discharge ranging from 10-5-1.6 km3, 0.5-123 m3/s and 1-370 m3/s. Similarly, the mixed events have durations spanning 2.8 to 393 days with volume, average and peak magma discharge ranging from 0.03-0.87 km3, 14-617 m3/s and 50-35600 m3/s. Duration of within-glacier events spans 4.4 to 14 days with volume, average and peak magma discharge ranging from 0.05-0.27 km3, 9-440 m3/s and 400-14000 m3/s. The discharge profiles for these eruptions are highly variable. Mixed eruptions often feature intense discharge (1500 to 40000 m3/s) at the onset of eruption (lasting hours), but some start in a much more subdued manner (500-1000 m3/s). This initial phase is followed by low (3-20 m3/s) magma discharge lasting for weeks to months that normally terminates abruptly. The onset of effusive eruptions is typified by modest discharge (10's to 100's m3/s). They can be very abrupt (<1 day), or drawn out for weeks to months with discharge dropping steadily throughout. The within-glacier events are short-lived explosive events, although with highly varied intensity (see above), and appear to terminate rather abruptly. Plots of eruption duration against size or discharge exhibits no systematic correlation suggesting that none of the eruption source parameters exert principal control on eruption duration or termination. However, these parameters may play a role in conjunction with other factors such as the nature of the lithostratigraphic succession and the local stress field at the eruption site.

  6. Magma storage depths in the Eastern Volcanic Zone of Iceland: disentangling disequilibrium and tuning thermobarometers

    NASA Astrophysics Data System (ADS)

    Neave, D.; Maclennan, J.; Thordarson, T.; Hartley, M. E.; Buisman, I.; Namur, O.; Halldorsson, S. A.

    2015-12-01

    The Eastern Volcanic Zone (EVZ) is the most volcanically productive of Iceland's neovolcanic zones. In addition to being the source of numerous small but disruptive eruptions, such Eyjafjallajökull in 2010 and Grímsvötn in 2011, the EVZ is notable for generating very large eruptions such as the environmentally impacting Laki eruption in 1783-84 and the widely dispersed Saksunarvatn Ash. Thus, investigating the plumbing systems of volcanoes in the EVZ not only reveals information about magma reservoir behaviour and crustal structure, but also has important implications for hazard management. However, in order to obtain reliable estimates of pre-eruptive magma storage conditions and depths from minerals a number of conditions need to be met first. Firstly, all estimates of pre-eruptive conditions need to be placed into petrogenetic frameworks that consider the extensive disequilibrium that results not only from fractionation, but also from magma mixing and crystal mush entrainment. Secondly, it is important to verify that the mineral-melt equilibrium, i.e. thermobarometeric, models used are well calibrated at the expected conditions of magma storage. Using a range of techniques including QEMSCAN imaging, textural analysis and geochemical microanalysis of crystals, glasses and melt inclusions, we present internally consistent models of magma evolution and storage for a number of eruptions in the EVZ, including Laki and the 10ka Grímsvötn tephra series (i.e. Saksunarvatn Ash). All eruptions studied preserve evidence of mixing and crystallisation of primitive melts in the mid-crust (8-20 km) followed by crystallisation of evolved and, in general, more incompatible element-enriched melts in the shallow crust (0-8 km) shortly before eruption. Substantial uncertainties in storage depths nevertheless remain because of incomplete calibration of clinopyroxene-melt equilibria at mid-crustal pressures. As part of an ongoing experimental campaign on Icelandic magma

  7. Towards an operational lidar network across the UK

    NASA Astrophysics Data System (ADS)

    Adam, Mariana; Horseman, Andrew; Turp, Myles; Buxmann, Joelle; Sugier, Jacqueline

    2015-04-01

    The Met Office has been operating a ceilometer network since 2012. This network consists of 11 Jenoptik Nimbus ceilometers (operating at 1064 nm) and 32 Vaisala ceilometers (25 CL31, operating at 910 nm and 7 CT25 operating at 905 nm). The data are available in near real time (NRT) (15 min for Jenoptik and 1 h for Vaisala). In 2014, six additional stations from Met Éireann (Ireland) were added to the network (5 CL31 and 1 CT25). Visualisation of attenuated backscatter and cloud base height are available from http://www.metoffice.gov.uk/public/lidarnet/lcbr-network.html. The main customers are the Met Office Hazard Centre which provides a quick response to customers requiring forecast information to manage a wide variety of environmental incidents and the London Volcanic Ash Advisory Centre (VAAC), also based at the Met Office, which monitor volcanic ash events. As a response to the strong impact of the Eyjafjallajökull eruption in 2010, the UK Civil Aviation Authority (CAA) financed a lidar - sunphotometer network for NRT monitoring of the volcanic ash. This new network will consist of nine fixed sites and one mobile unit, each equipped with a lidar and a sunphotometer. The sunphotometers were acquired from Cimel Electronique (CE318-NE DPS9). The lidars were acquired from Raymetrics. They operate at 355 nm and have receiving channels at 355 nm (parallel and perpendicular polarization) and 387 nm (N2 Raman). The first two lidar systems were deployed in November 2014 at Camborne (SW England) and the data are under evaluation. The network is planned to be operational in 2016. Initially, the NRT data will consist of quick look plots of the total range corrected signal and volume depolarization ratio from lidar and aerosol optical depth from sunphotometer (including 355nm, through interpolation). During EGU presentation, the following features will be emphasized: IT considerations for the operational network, data quality assurance (including error estimates) for the

  8. Discovery of an Active Microbial Community in a Subglacial Volcanic Crater Lake, Iceland

    NASA Astrophysics Data System (ADS)

    Gaidos, E.; Lanoil, B.; Thorsteinsson, T.; Graham, A.; Skidmore, M.; Decarlo, E.; Popp, B.

    2002-12-01

    Grímsvötn, an active volcano beneath the Vatnajökull glacier in Iceland, hosts a subglacial caldera lake (Gudmundsson, Sigmundsson and Björnsson 1997 Nature 389, 954). Except for earlier geochemical measurements (Ágústsdóttir and Brantley 1994 J. Geophys. Res. 99, 9505), the lake and its possible biota have remained unexplored. In June 2002 we penetrated the 300-meter ice sheet over the lake using hot-water drilling and collected water and tephra sediment samples. The 85oC drilling water and chemical sterilization of equipment were used to minimize sample contamination. Samples of borehole water, glacial ice, and snow were also obtained. Lake water was at the freezing point and samples had no sulfidic smell indicative of anaerobic conditions. One sample from the borehole actively degassed after retrieval. Waters were slightly acidic (pH ≈ 5) and fresh ([Na] = 5 ppm) with low sulfate (2 ppm). Elevated transition metal levels measured by ICP-MS are being analyzed. Direct (DAPI stain) cell counts in water and sediment average 2 x 104 cells ml-1 and 4 x 107 cells ml-1, respectively. Counts on R2A plates incubated under aerobic conditions at 22oC and 6oC for one week were 1-2 x 104 and 5 x 103 CFU/ml, respectively. These values may reflect growth during sample shipment, however, growth at 6oC indicates the presence of psychrophilic or at least psychrotolerant organisms in the lake. Colonies from lake and post-penetration borehole samples were distinct from those of the borehole, ice and snow. Incubations of lake samples at 4oC showed incorporation of 14C (from bicarbonate). Incubations of other aliquots with a nitrogen-acetylene mixture indicated production of ethylene suggestive of nitrogenase activity. DNA will be extracted and analyzed to determine if the microbial community is distinct from that in the overlying snow and ice.

  9. Thermal analysis of hydrated volcanic glasses: can primary and secondary water be distinguished?

    NASA Astrophysics Data System (ADS)

    Tuffen, H.

    2012-12-01

    The overwhelming majority of glassy volcanic rocks have undergone extensive post-quenching hydration by meteoric water. In order to unlock the record of magma degassing in hydrated glasses we require techniques to characterise and separate primary (magmatic) and secondary (meteoric) water. Possible approaches include mapping of spatial heterogeneities with micro-analytical tools, determination of bulk degassing behaviour using thermal analysis, measurement of water speciation using infra-red spectroscopy, and measurement of isotopic compositions to separate endmembers. Here I provide an overview of thermal analysis (TGA-MS) carried out on variably hydrated volcanic glasses from Taupo, Torfajökull, Vesuvius and Chaitén. Glasses span a range of compositions (phonolitic, rhyodacitic and rhyolitic), grainsizes (metre-scale lava bodies to fine-grained ashes) and ages (~95 ka to 2008). Powdered samples were heated to 1250 °C at 5 °C/min and the patterns of weight loss determined, whilst exsolved gases were analysed by mass spectrometry. Degassing from samples is characterised by the dTGA and TGA curves (rate and total amount of weight loss during heating). The nature of the dTGA curve is determined by the spatial distribution of water within samples (distance to surfaces), its speciation, and the concentration-and temperature-dependent water diffusivity. Hydration experiments on fresh, non-hydrated ash collected directly after the 2008 Chaitén eruption illustrate how rapidly fresh glasses can become hydrated post-eruption. In TGA-MS measurements this secondary water is degassed at lower temperatures than magmatic water, allowing primary and secondary degassing peaks to be separated. This indicates that thermal analysis can allow determination of bulk magmatic water concentrations in young, incipiently hydrated glasses. Hydration in older glasses becomes far more pervasive, as demonstrated by SIMS mapping of water concentration heterogeneities in Taupo AD181 pumices

  10. A multi-scale risk assessment for tephra fallout and airborne concentration from multiple Icelandic volcanoes - Part 2: Vulnerability and impact

    NASA Astrophysics Data System (ADS)

    Scaini, C.; Biass, S.; Galderisi, A.; Bonadonna, C.; Folch, A.; Smith, K.; Hoskuldsson, A.

    2014-04-01

    We perform a multi-scale impact assessment of tephra fallout and dispersal from explosive volcanic activity in Iceland. A companion paper (Biass et al., 2014) introduces a multi-scale probabilistic assessment of tephra hazard from 4 Icelandic volcanoes (Hekla, Askja, Eyjafjallajökull and Katla) and presents probabilistic hazard maps for tephra accumulation in Iceland and tephra dispersal across Europe. Here, we present the subsequent vulnerability and impact assessment, that accounts the relevance of single features at national and European levels and considers several vulnerability indicators for tephra dispersal and deposition. At national scale, we focus on physical, systemic and economic vulnerability of Iceland to tephra fallout, whereas at European scale we focus on the systemic vulnerability of the air traffic system to tephra dispersal. Results include vulnerability maps for Iceland and European airspace and allow identifying the expected impacts of the different eruptive scenarios considered. Results at national scale show that tephra accumulation from the considered eruptive scenarios can disrupt main electricity network, in particular in case of eruption at Askja volcano. Results also show that if eruptive scenarios occurred at Hekla, Askja and Katla volcanoes, many power plants would be affected, causing a substantial systemic impact due to their importance for the Icelandic economy. Moreover, the considered scenarios at Askja and Katla could produce substantial impact on agricultural activities (crops and pastures). At European scale, tephra dispersal from explosive volcanic activity at Askja and Katla volcanoes is likely to produce substantial impacts at European level and, in particular, at Keflavik and London Flight Information Regions (FIRs), but also at FIRs above France, Germany and Scandinavia, in particular for long-lasting activity at Katla volcano. Explosive activity at Hekla volcano is likely to produce high impacts at Keflavik FIR and

  11. 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

    within the EU VETOOLS project, aiming to improve response to future events. Monitoring the site was carried out throughout 2015, including the cooling of the lava in relation to thickness and inflation history. This also included mapping of hydrology in the Dyngjujökull outwash plane, development of ponds where the lava blocked previous river channels.

  12. Estimation and propagation of volcanic source parameter uncertainty in an ash transport and dispersal model: application to the Eyjafjallajokull plume of 14-16 April 2010

    NASA Astrophysics Data System (ADS)

    Bursik, Marcus; Jones, Matthew; Carn, Simon; Dean, Ken; Patra, Abani; Pavolonis, Michael; Pitman, E. Bruce; Singh, Tarunraj; Singla, Puneet; Webley, Peter; Bjornsson, Halldor; Ripepe, Maurizio

    2012-12-01

    Data on source conditions for the 14 April 2010 paroxysmal phase of the Eyjafjallajökull eruption, Iceland, have been used as inputs to a trajectory-based eruption column model, bent. This model has in turn been adapted to generate output suitable as input to the volcanic ash transport and dispersal model, puff, which was used to propagate the paroxysmal ash cloud toward and over Europe over the following days. Some of the source parameters, specifically vent radius, vent source velocity, mean grain size of ejecta, and standard deviation of ejecta grain size have been assigned probability distributions based on our lack of knowledge of exact conditions at the source. These probability distributions for the input variables have been sampled in a Monte Carlo fashion using a technique that yields what we herein call the polynomial chaos quadrature weighted estimate (PCQWE) of output parameters from the ash transport and dispersal model. The advantage of PCQWE over Monte Carlo is that since it intelligently samples the input parameter space, fewer model runs are needed to yield estimates of moments and probabilities for the output variables. At each of these sample points for the input variables, a model run is performed. Output moments and probabilities are then computed by properly summing the weighted values of the output parameters of interest. Use of a computational eruption column model coupled with known weather conditions as given by radiosonde data gathered near the vent allows us to estimate that initial mass eruption rate on 14 April 2010 may have been as high as 108 kg/s and was almost certainly above 107 kg/s. This estimate is consistent with the probabilistic envelope computed by PCQWE for the downwind plume. The results furthermore show that statistical moments and probabilities can be computed in a reasonable time by using 94 = 6,561 PCQWE model runs as opposed to millions of model runs that might be required by standard Monte Carlo techniques. The

  13. Magma movements and Iceland's next eruptions (Invited)

    NASA Astrophysics Data System (ADS)

    Sigmundsson, F.; Ofeigsson, B.; Hreinsdottir, S.; Hensch, M.; Gudmundsson, G.; Vogfjord, K. S.; Roberts, M. J.; Geirsson, H.; La Femina, P. C.; Hooper, A. J.; Sturkell, E. C.; Einarsson, P.; Gudmundsson, M. T.; Brandsdottir, B.; Loughlin, S. C.; Team, F.

    2013-12-01

    Iceland, created by hotspot-ridge interaction, is characterized by higher magmatic input and more complicated plate boundary structure than other parts of the Mid-Atlantic rift system. It has 30+ volcanic systems, where 20 confirmed eruptions have occurred in the last 40 years, the most recent at Eyjafjallajökull in 2010 and Grimsvotn in 2011. Likely candidates for the next eruption include the four most active volcanoes in Iceland (Hekla, Katla, Grimsvotn, and Bardarbunga) and other areas of volcanic unrest (Askja region, the Krisuvik area). Present volcano monitoring and research, including the FUTUREVOLC project, aims at providing warnings of impending eruptions and their character. Earthquake monitoring and deformation studies have hereto provided the most relevant information. Hekla continuously accumulates magma at a rate of about 0.003-0.02 km3/yr, according to GPS and InSAR studies, in a magma chamber placed below 14 km depth. A sequence of M0.4-1 earthquakes early this year stands out from otherwise mostly aseismic character of Hekla during repose periods. The Hekla magma chamber does not fail at a constant amount of magma volume, rather a clear pattern is observed with eruption size scaling with the length of the preceding period of dormancy. The ice capped Katla volcano shows unusual annual deformation pattern, seismic activity, and hydrological variations depending on time of year, presumably related to ice load and water pressure variations. It may be in a critical stage and renewed inflow of magma may quickly move the volcano towards failure. Bardarbunga had major earthquake and magma transfer activity in 1996, and has been the site of deep low-frequency earthquakes. Grímsvötn volcano is the only volcano with a shallow magma chamber with ongoing confirmed recharging, and failure criteria closest to 'expected'. A large eruption occurred in 2011 compared to much smaller eruption in 2004. However, the amount of erupted magma did not scale with the

  14. Summary of activities for DOE Award DE-FG02-02ER63444 for "Modeling dynamic vegetation for decadal to multi-century climate change studies"

    SciTech Connect

    Nancy Y. Kiang

    2005-09-26

    This is a summary of all activities that were funded by the DOE Award DE-FG02-02ER63444, ''Modeling dynamic vegetation for decadal to multi-century climate change studies'', during the period 09/01/2001-11/30/2004. The goal of this research has been to produce a process-based vegetation activity model suitable for coupling with a general circulation model (GCM) of the atmosphere, to simulate the biophysics of vegetation transpiration and photosynthesis, seasonal growth, and vegetation cover change. The model was to be developed within the NASA Goddard Institute for Space Studies (GISS) GCM. The model as envisioned in the original proposal was to be an adaptation of Dr. Friend's previous well-known dynamic vegetation model, HYBRID (Friend, et.al., 1997; Friend and White, 2000). After examining the issues of GCM model coupling, Dr. Friend realized some of the complexities of HYBRID would not be computationally suitable for the GCM. He wrote a review paper on ''big-leaf'' modeling issues (Friend, 2001), and concentrated on developing a new vegetation biophysics approach, which involved a computationally simply canopy-level conductance scheme (thus avoiding the problem of leaf-to-canopy scaling) and photosynthesis based on the work of Kull and Kruijt (1998), which distinguished the portion of leaf nitrogen that is photosynthetic. Dr. Friend presented the results photosynthesis/conductance scheme coupled to the Model II version of the GISS GCM (Hansen, et.al., 1983) in a talk at the 2002 AGU Fall Meeting in San Francisco. After Dr. Kiang arrived in April 2003, she, Dr. Friend, and Dr. Aleinov implemented the new scheme in the Model E version of the GISS GCM (Schmidt, et.al., accepted), and published results of improved surface temperatures and cloud cover in the Journal of Climate (Friend and Kiang, 2005). Till the end of the award period, Dr. Friend continued to develop a new vegetation growth model involving nitrogen allocation to light-stratified canopy layers

  15. Glacial evolution of the Ampato Volcanic Complex (Peru)

    NASA Astrophysics Data System (ADS)

    Alcalá, J.; Palacios, D.; Zamorano, J. J.; Vázquez, L.

    2009-04-01

    Ice masses on the Western range of the Central Andes are a main source of water resources and act as a geoindicator of variations in the climate of the tropics (Mark, 2008). The study of their evolution is of particular interest since they are situated in the transition zone between the tropical and mid-latitude circulation areas of the atmosphere (Zech et al., 2007). The function of this transition area is currently under debate, and understanding it is essential for the development of global climate models (Kull et al, 2008; Mark, 2008). However our understanding of the evolution of glaciers and their paleoclimatic factors for this sector of the Central Andes is still at a very basic level. This paper presents initial results of a study on the glacial evolution of the Ampato volcanic complex (15°24´- 15° 51´ S, 71° 51´ - 73° W; 6288 m a.s.l.) located in the Western Range of the Central Andes in Southern Peru, 70 km NW of the city of Arequipa. The main objectives are to identify the number of glacial phases the complex has undergone using geomorphological criteria to define a time frame for each phase, based on cosmogenic 36Cl dating of a sequence of moraine deposits; and to estimate the glacier Equilibrium Line Altitude (ELA) of each phase. The Ampato volcanic complex is formed by 3 great andesitic stratovolcanoes, the Nevados HualcaHualca-Sabancaya-Ampato, which started forming between the late Miocene and early Quaternary (Bulmer et al., 1999), aligned N-S and with summits covered with glaciers. The Sabancaya volcano is fully active, with its latest eruption occurring in 2001. Glacial landforms were identified and mapped using photointerpretation of vertical aerial photographs from 1955 (1:35,000 scale, National Geographic Institute of Peru), oblique photographs from 1943 (Aerophotographical Service of Peru), and a geo-referenced high-resolution Mrsid satellite image from 2000 (NASA). This cartography was corrected and improved through fieldwork. It was

  16. Occupational Exposure to Endocrine-Disrupting Chemicals and Birth Weight and Length of Gestation: A European Meta-Analysis

    PubMed Central

    Birks, Laura; Casas, Maribel; Garcia, Ana M.; Alexander, Jan; Barros, Henrique; Bergström, Anna; Bonde, Jens Peter; Burdorf, Alex; Costet, Nathalie; Danileviciute, Asta; Eggesbø, Merete; Fernández, Mariana F.; González-Galarzo, M. Carmen; Hanke, Wojciech; Jaddoe, Vincent; Kogevinas, Manolis; Kull, Inger; Lertxundi, Aitana; Melaki, Vasiliki; Andersen, Anne-Marie Nybo; Olea, Nicolás; Polanska, Kinga; Rusconi, Franca; Santa-Marina, Loreto; Santos, Ana Cristina; Vrijkotte, Tanja; Zugna, Daniela; Nieuwenhuijsen, Mark; Cordier, Sylvaine; Vrijheid, Martine

    2016-01-01

    , Hanke W, Jaddoe V, Kogevinas M, Kull I, Lertxundi A, Melaki V, Andersen AM, Olea N, Polanska K, Rusconi F, Santa-Marina L, Santos AC, Vrijkotte T, Zugna D, Nieuwenhuijsen M, Cordier S, Vrijheid M. 2016. Occupational exposure to endocrine-disrupting chemicals and birth weight and length of gestation: a European meta-analysis. Environ Health Perspect 124:1785–1793; http://dx.doi.org/10.1289/EHP208 PMID:27152464

  17. Experimental generation of volcanic lightning

    NASA Astrophysics Data System (ADS)

    Cimarelli, Corrado; Alatorre-Ibargüengoitia, Miguel; Kueppers, Ulrich; Scheu, Bettina; Dingwell, Donald B.

    2014-05-01

    Ash-rich volcanic plumes that are responsible for injecting large quantities of aerosols into the atmosphere are often associated with intense electrical activity. Direct measurement of the electric potential at the crater, where the electric activity in the volcanic plume is first observed, is severely impeded, limiting progress in its investigation. We have achieved volcanic lightning in the laboratory during rapid decompression experiments of gas-particle mixtures under controlled conditions. Upon decompression (from ~100 bar argon pressure to atmospheric pressure), loose particles are vertically accelerated and ejected through a nozzle of 2.8 cm diameter into a large tank filled with air at atmospheric conditions. Because of their impulsive character, our experiments most closely represent the conditions encountered in the gas-thrust region of the plume, when ash is first ejected from the crater. We used sieved natural ash with different grain sizes from Popocatépetl (Mexico), Eyjafjallajökull (Iceland), and Soufrière Hills (Montserrat) volcanoes, as well as micrometric glass beads to constrain the influence of material properties on lightning. We monitored the dynamics of the particle-laden jets with a high-speed camera and the pressure and electric potential at the nozzle using a pressure transducer and two copper ring antennas connected to a high-impedance data acquisition system, respectively. We find that lightning is controlled by the dynamics of the particle-laden jet and by the abundance of fine particles. Two main conditions are required to generate lightning: 1) self-electrification of the particles and 2) clustering of the particles driven by the jet fluid dynamics. The relative movement of clusters of charged particles within the plume generates the gradient in electrical potential, which is necessary for lightning. In this manner it is the gas-particle dynamics together with the evolving particle-density distribution within different regions of

  18. Large, Moderate or Small? The Challenge of Measuring Mass Eruption Rates in Volcanic Eruptions

    NASA Astrophysics Data System (ADS)

    Gudmundsson, M. T.; Dürig, T.; Hognadottir, T.; Hoskuldsson, A.; Bjornsson, H.; Barsotti, S.; Petersen, G. N.; Thordarson, T.; Pedersen, G. B.; Riishuus, M. S.

    2015-12-01

    The potential impact of a volcanic eruption is highly dependent on its eruption rate. In explosive eruptions ash may pose an aviation hazard that can extend several thousand kilometers away from the volcano. Models of ash dispersion depend on estimates of the volcanic source, but such estimates are prone to high error margins. Recent explosive eruptions, including the 2010 eruption of Eyjafjallajökull in Iceland, have provided a wealth of data that can help in narrowing these error margins. Within the EU-funded FUTUREVOLC project, a multi-parameter system is currently under development, based on an array of ground and satellite-based sensors and models to estimate mass eruption rates in explosive eruptions in near-real time. Effusive eruptions are usually considered less of a hazard as lava flows travel slower than eruption clouds and affect smaller areas. However, major effusive eruptions can release large amounts of SO2 into the atmosphere, causing regional pollution. In very large effusive eruptions, hemispheric cooling and continent-scale pollution can occur, as happened in the Laki eruption in 1783 AD. The Bárdarbunga-Holuhraun eruption in 2014-15 was the largest effusive event in Iceland since Laki and at times caused high concentrations of SO2. As a result civil protection authorities had to issue warnings to the public. Harmful gas concentrations repeatedly persisted for many hours at a time in towns and villages at distances out to 100-150 km from the vents. As gas fluxes scale with lava fluxes, monitoring of eruption rates is therefore of major importance to constrain not only lava but also volcanic gas emissions. This requires repeated measurements of lava area and thickness. However, most mapping methods are problematic once lava flows become very large. Satellite data on thermal emissions from eruptions have been used with success to estimate eruption rate. SAR satellite data holds potential in delivering lava volume and eruption rate estimates

  19. Volcanic risk and tourism in southern Iceland: Implications for hazard, risk and emergency response education and training

    NASA Astrophysics Data System (ADS)

    Bird, Deanne K.; Gisladottir, Gudrun; Dominey-Howes, Dale

    2010-01-01

    This paper examines the relationship between volcanic risk and the tourism sector in southern Iceland and the complex challenge emergency management officials face in developing effective volcanic risk mitigation strategies. An early warning system and emergency response procedures were developed for communities surrounding Katla, the volcano underlying the Mýrdalsjökull ice cap. However, prior to and during the 2007 tourist season these mitigation efforts were not effectively communicated to stakeholders located in the tourist destination of Þórsmörk despite its location within the hazard zone of Katla. The hazard zone represents the potential extent of a catastrophic jökulhlaup (glacial outburst flood). Furthermore, volcanic risk mitigation efforts in Þórsmörk were based solely on information derived from physical investigations of volcanic hazards. They did not consider the human dimension of risk. In order to address this gap and provide support to current risk mitigation efforts, questionnaire surveys were used to investigate tourists' and tourism employees' hazard knowledge, risk perception, adoption of personal preparedness measures, predicted behaviour if faced with a Katla eruption and views on education. Results indicate that tourists lack hazard knowledge and they do not adopt preparedness measures to deal with the consequences of an eruption. Despite a high level of risk perception, tourism employees lack knowledge about the early warning system and emergency response procedures. Results show that tourists are positive about receiving information concerning Katla and its hazards and therefore, the reticence of tourism employees with respect to disseminating hazard information is unjustified. In order to improve the tourism sector's collective capacity to positively respond during a future eruption, recommendations are made to ensure adequate dissemination of hazard, risk and emergency response information. Most importantly education campaigns

  20. Satellite Derived Volcanic Ash Product Inter-Comparison in Support to SCOPE-Nowcasting

    NASA Astrophysics Data System (ADS)

    Siddans, Richard; Thomas, Gareth; Pavolonis, Mike; Bojinski, Stephan

    2016-04-01

    In support of aeronautical meteorological services, WMO organized a satellite-based volcanic ash retrieval algorithm inter-comparison activity, to improve the consistency of quantitative volcanic ash products from satellites, under the Sustained, Coordinated Processing of Environmental Satellite Data for Nowcasting (SCOPEe Nowcasting) initiative (http:/ jwww.wmo.int/pagesjprogjsatjscopee nowcasting_en.php). The aims of the intercomparison were as follows: 1. Select cases (Sarychev Peak 2009, Eyjafyallajökull 2010, Grimsvötn 2011, Puyehue-Cordón Caulle 2011, Kirishimayama 2011, Kelut 2014), and quantify the differences between satellite-derived volcanic ash cloud properties derived from different techniques and sensors; 2. Establish a basic validation protocol for satellite-derived volcanic ash cloud properties; 3. Document the strengths and weaknesses of different remote sensing approaches as a function of satellite sensor; 4. Standardize the units and quality flags associated with volcanic cloud geophysical parameters; 5. Provide recommendations to Volcanic Ash Advisory Centers (VAACs) and other users on how to best to utilize quantitative satellite products in operations; 6. Create a "road map" for future volcanic ash related scientific developments and inter-comparison/validation activities that can also be applied to SO2 clouds and emergent volcanic clouds. Volcanic ash satellite remote sensing experts from operational and research organizations were encouraged to participate in the inter-comparison activity, to establish the plans for the inter-comparison and to submit data sets. RAL was contracted by EUMETSAT to perform a systematic inter-comparison of all submitted datasets and results were reported at the WMO International Volcanic Ash Inter-comparison Meeting to held on 29 June - 2 July 2015 in Madison, WI, USA (http:/ /cimss.ssec.wisc.edujmeetings/vol_ash14). 26 different data sets were submitted, from a range of passive imagers and spectrometers and

  1. Analysis of aerosol optical properties from continuous sun-sky radiometer measurements at Halley and Rothera, Antarctica over seven years

    NASA Astrophysics Data System (ADS)

    Campanelli, Monica; Estellés, Victor; Colwell, Steve; Shanklin, Jonathan; Ningombam, Shantikumar S.

    2015-04-01

    back-trajectories were considered in order to understand the origin of these particles (if locally produced or due to large scale transport ) and to verify if the events in the two sites are related or not. In addition some single days' events, showing both high aerosol optical thickness and absorption, were also studied. References: Campanelli et al, 2012, "Monitoring of Eyjafjallajökull volcanic aerosol by the new European Skynet Radiometers (ESR) network", Atmospheric Environment 48 (2012) 33-45 Nakajima, T., Tonna, G., Rao, R., Boi, P., Kaufman, Y., Holben, B., 1996. Use of sky brightness measurements from ground for remote sensing of particulate polydispersions. Applied Optics 35, 2672- 2686.

  2. Strain Accumulation and Release in the South Iceland Seismic Zone (Invited)

    NASA Astrophysics Data System (ADS)

    Arnadottir, T.; Hreinsdottir, S.; Geirsson, H.; Ofeigsson, B.

    2013-12-01

    Iceland is located on the Mid-Atlantic ridge, straddling the plate boundary of the North-American and Eurasian plates. Several active volcanic zones and two main transforms accommodate the plate spreading across the island. In the South, the South Iceland Seismic Zone (SISZ) forms the active plate boundary between the Hengill triple junction in the west, and the Eastern Volcanic Zone. The SISZ translates the E-W left lateral shear at depth by faulting on numerous N-S oriented faults in the brittle crust forming the southern margin of the proposed Hreppar micro-plate in South Iceland. In June 2000 and May 2008, two sets of magnitude 6.5 and 6.0 main shocks struck the SISZ. Both earthquake episodes consisted of a pair of main shocks of similar size rupturing closely spaced faults, where static and dynamic stress changes generated by the first event triggered the second main shock further west. The June 2000 earthquakes occurred in the central part of the SISZ, and the May 2008 events in the western part, close to the Hengill triple junction. Since June 2000 annual GPS measurements have been conducted in a geodetic network in South Iceland and a number of continuous GPS stations have been installed. We report strain rate variations in South Iceland derived from GPS observations during 2000 to 2013. In addition to plate motion, and post-seismic signals, the surface deformation is complicated by magma accumulation under active volcanoes at the eastern border of the SISZ - Hekla, and Eyjafjallajökull - as well as subsidence and contraction in the Hengill area caused by fluid withdrawal for geothermal energy production. We also note an increase in strain rates in the epicentral area of the May 2008 main shocks during 2004 to 2007. Previous studies have indicated that the seismic moment released in the June 2000 and May 2008 earthquakes is only half of the accumulated stress since the last major earthquake sequence in 1896-1912. Thus, magnitude 6-7 events may be expected

  3. Looking Backward and Forward: A Decadal View of Volcanology

    NASA Astrophysics Data System (ADS)

    Fink, J. H.

    2010-12-01

    In many scientific fields, decades are the time intervals of choice for retrospective and prospective reflections and speculations. AGU Session V02 seeks to apply this perspective to the assessment of where volcanology has been since 2000 and where it is headed in the next ten years. Most sciences progress through incremental observational, experimental and theoretical steps, accelerated by the identification of new socially-relevant applications, technological breakthroughs or conceptual insights, and jolted by largely unanticipated events. Volcanology is unusual in the dominant role that unpredictable eruptive observations play in controlling the evolution of the discipline. As a result, the most important constraints on how the field will change are virtually unknowable. At a session at the Fall AGU meeting in 2000 on "Volcanology 2010" a dozen talks sought to forecast how volcano science and policy would change in the next ten years, focusing on such topics as seismology, petrology, remote sensing, deformation, volcano-tectonic interactions, communications, graduate education, international cooperation, numerical modeling, database querying, and networking of observatories. While progress occurred in many of these areas, what was perhaps the most important influence on volcanology was not mentioned: for the first 9.5 years of the decade, there were no eruptions disastrous or novel enough to garner global public or political attention, with associated prioritization by funding agencies. The notable exception was the eruption of Eyjafjallajökull in mid-2010, which captured the western world’s attention due to the magnitude of the disruption, the frustrating inability of scientists to provide guidance, and the fortunate lack of casualties. We can expect continuing technical advances in all aspects of geoscience to improve the understanding of volcanic processes in the coming decade. However, another natural disaster in 2010 might hold more relevance for how

  4. Toward an integrated Volcanic Ash Observing System in Europe

    NASA Astrophysics Data System (ADS)

    Lee, Deborah; Lisk, Ian

    2014-05-01

    Volcanic ash from the Icelandic eruption of Eyjafjallajökull in April and May of 2010 resulted in the decision by many northern European countries to impose significant restrictions on the use of their airspace. The eruption, extent and persistence of the ash revealed how reliant society now is on a safe and efficient air transport system and the fragility of that system when affected by the impact of complex natural hazards. As part of an EC framework programme, the 2011-2013 WEZARD (WEather HaZARD for aeronautics) consortium conducted a cross-industry volcanic ash capability and gap analyses, with the EUMETNET (network of 29 National Meteorological Services) led Work Package 3 focussing on a review of observational and monitoring capabilities, atmospheric dispersion modelling and data exchange. The review has revealed a patchwork of independent observing capabilities for volcanic ash, with some countries investing and others not at all, and most existing networks focus on space-based products. Existing capabilities do not provide the necessary detail on the geographical and vertical extent of volcanic ash and associated levels of contamination, which decision makers in the aviation industry require in order to decide where it is safe to fly. A resultant high priority was identified by WEZARD Work Package 3 for an enhanced observational network of complementary monitoring systems needed to initialise, validate and verify volcanic ash dispersion model output and forecasts. Thus a key recommendation is to invest in a major pre-operational demonstrator "European volcanic ash observing network", focussing on distal monitoring, and aiming to a) fill R&D gaps identified in instrumentation and algorithms and b) integrate data, where possible in near-real-time, from a range of ground-based, airborne and space-based techniques. Here we present a key WEZARD recommendation toward an integrated volcanic ash observing system in Europe, in context with other related projects

  5. Sulphide globules and their impact on sulphur degassing budget: the case of Grímsvötn volcano, Iceland.

    NASA Astrophysics Data System (ADS)

    Haddadi, Baptiste; Carn, Simon; Sigmarsson, Olgeir

    2014-05-01

    Volcanic eruptions are known to contribute sulphur to the atmosphere. Two different methods allow estimation of sulphur mass loading: remote satellite measurements and the petrologic method. Sulphur emission at subduction-related volcanoes is often underestimated by the latter method relative to the former whereas a fair agreement is found for hot spot-related volcanoes. The Grímsvötn 2011 eruption allows further comparison between these two methods. Grímsvötn is a basaltic subglacial volcano located under the Vatnajökull ice cap, above the Iceland mantle plume and the Mid-Atlantic Ridge. The May 2011 eruption lasted one week and took place inside the composite caldera of the volcano. During the first 24 hours, the column reached a height of more than 20 km and bulk of the magma was emitted. The basaltic tephra has quartz-normative tholeiite composition with 1-5% plagioclase, clinopyroxene, olivine, FeTi-oxide crystals and, noteworthy, sulphide globules present in the groundmass glass. Sulphur concentrations of twenty eight melt inclusions (MIs) were measured in plagioclase, clinopyroxene and olivine crystals extracted from the tephra produced during the most explosive phase. The difference between the mean sulphur content of both MIs and groundmass glass multiplied by the magma mass erupted, yields 0.73 ± 0.18 Tg of liberated sulphur. This is four times the estimated sulphur degassing by satellite measurements (0.19 ± 0.06 Tg). The contributions of different sulphur sinks were quantified. The geothermal system harvests approximately 0.037 Tg (5%), which are liberated during jökulhlaups. Sulphur adhering to the volcanic ash is approximately 0.12 Tg (15%). Added to the satellite measurements of sulphur entering the stratosphere, half of the S estimated by the petrologic method is still missing. Sulphur immiscibility forming sulphur globules in the magma chambers appears the most probable explanation for the missing 50% of sulphur. Due to elevated density of

  6. Effects of ice-cap unloading on shallow magmatic reservoirs

    NASA Astrophysics Data System (ADS)

    Bakker, Richard; Frehner, Marcel; Lupi, Matteo

    2015-04-01

    One of the effects of global warming is the increase of volcanic activity. Glacial melting has been shown to cause visco-elastic relaxation of the upper mantle, which in turn promotes upwelling of magmas through the crust. To date, the effects of ice-cap melting on shallow (i.e., less than 10 km depth) plumbing systems of volcanoes are still not clear. We investigate the pressure changes due to glacial unloading around a magmatic reservoir by combining laboratory and numerical methods. As a case study we focus on Snæfellsjökull, a volcano in Western Iceland whose ice cap is currently melting 1.25 meters (thickness) per year. Our approach is as follows: we obtain representative rock samples from the field, preform tri-axial deformation tests at relevant pressure and temperature (PT) conditions and feed the results into a numerical model in which the stress fields before and after ice cap removal are compared. A suite of deformation experiments were conducted using a Paterson-type tri-axial deformation apparatus. All experiments were performed at a constant strain rate of 10-5 s-1, while varying the PT conditions. We applied confining pressures between 50 and 150 MPa and temperatures between 200 and 1000 ° C. Between 200 and 800 ° C we observe a localized deformation and a slight decrease of the Young's modulus from 41 to 38 GPa. Experiments at 900 and 1000 ° C exhibit macroscopically ductile behavior and a marked reduction of the Young's modulus down to 4 GPa at 1000 ° C. These results are used to construct a numerical finite-element model in which we approximate the volcanic edifice and basement by a 2D axisymmetric half-space. We first calculate the steady-state temperature field in the volcanic system and assign the laboratory-derived temperature-dependent Young's modulus to every element of the model. Then the pressure in the edifice is calculated for two scenarios: with and without ice cap. The comparison between the two scenarios allows us estimate the

  7. Estimates of mass eruption rates in Icelandic eruptions 1913-2015

    NASA Astrophysics Data System (ADS)

    Tumi Gudmundsson, Magnus; Dürig, Tobias; Larsen, Gudrún

    2016-04-01

    the last 1200 years several eruptions have been much larger. For example the eruption of Laki in 1783 was an order of magnitude larger than the largest effusive eruptions of 1913-2015. The same applies to e.g. Öræfajökull in 1362, being an order of magnitude larger than the explosive eruptions that occurred in the period analysed here.

  8. Explosive-effusive rhyolitic eruption styles beneath an Icelandic glacier - volatile or pressure control?

    NASA Astrophysics Data System (ADS)

    Owen, J.; Tuffen, H.; McGarvie, D.

    2012-12-01

    Understanding eruption mechanisms and behavioral controls is of key importance for mitigating against volcanic hazards. This is especially true for subglacial rhyolitic eruptions which are poorly understood and yet potentially devastating. We have investigated a subglacial rhyolitic eruption at Dalakvísl in South Iceland (~0.2 km3, ~70 ka) that involved both explosive and effusive activity1, generating pumiceous pyroclastic deposits and vesicle-poor lava bodies. We have measured pre- and post-eruptive magmatic volatile contents using SIMS, infrared spectroscopy and electron microprobe analysis of melt inclusions and matrix glasses, and used results to track magma degassing from the chamber to the surface2,3. Dissolved H2O contents in matrix glasses additionally allow reconstruction of the changing pressure conditions during the eruption. The explosive phase is associated with high pre-eruptive H2O (≤4.8 wt %), a fast ascent rate, closed system degassing and low confining pressure, whilst the effusive phase corresponds to lower pre-eruptive H2O (≤2.9 wt %), a slower ascent rate, more open system degassing and higher confining pressure. Detailed reconstructions of quenching pressures using matrix glass H2O indicate that a substantial pressure decrease (~1.3 MPa) accompanied the transition from effusive to explosive activity. We speculate that this indicates meltwater drainage in a jökulhlaup. We conclude that the transition was from effusive to explosive, and linked with a change in source magma and degassing path which may have been triggered by the depressurisation associated with the jökulhlaup. This highlights the complexity of interactions in subglacial rhyolitic systems but suggests that ice does little to supress volatile induced explosivity, whilst it does add to the potential hazards such as jökulhlaups. 1: Tuffen, H. et al. (2008) An explosive-intrusive subglacial rhyolite eruption at Dalakvísl, Torfajökull, Iceland. Bull. Volcanol. 70, 841-860. 2

  9. Vesicle size analysis of magmatic and phreatomagmatic phases of the 934-40 AD Eldgjá fissure eruption, southern Iceland

    NASA Astrophysics Data System (ADS)

    Thordarson, T.; Moreland, W.; Houghton, B. F.

    2014-12-01

    Eldgjá is a ~75 km volcanic fissure which erupted in the middle of the 10th century. It belongs to the Katla volcanic system and is of the mixed-cone row type. The eruption lasted several years and produced two large lava fields (18.3 km3) and a widespread basaltic tephra deposit (4.5 km3 or 1.3 km3 DRE). Proximal tephra deposits are up to 5 m thick and contain as many as 10 sub-units which vary in thickness parallel to the fissure, indicating multiple points of origin. Many of the lowest units were produced by phreatomagmatic activity and dispersion of these units indicate an origin below the Mýrdalsjökull glacier. Two sections were chosen to represent magmatic and phreatomagmatic activity. A 3.7 m section at Skælingar, 0.5 km south-east of Eldgjá, represents the magmatic products. The phreatomagmatic products are represented by a 2.7 m thick section at Stóragil, located 10-15 km south and east of the vent system. The sampled phreatomagmatic part of the section is 1.12 m thick. These sections were logged and then each sub-unit was sampled for density analysis which involves picking 100 clasts in the 8 to 32 mm size range from horizons less than 5 cm thick. Thin-sections were then made from representative clasts of each sub-unit. Nested images of these thin-sections were analysed for vesicle size and shape. The magmatic clasts have unimodal, normal to moderately log-normal density distributions with a mean density of 7900-7500 kg.m-3 (60-70% vesicularity) and a range of around 8600 kg.m-3 (40% vesicularity). The log-normal distribution of some samples may be explained by the inclusion of previously degassed magma in the eruption. The section at Stóragil contains both phreatomagmatic and magmatic products. The phreatomagmatic samples have characteristic plateau-like distributions with a mean density of 7200-7500 kg.m-3 (70-80% vesicularity) and a range of around 8420 kg.m-3 (45% vesicularity). One layer shows a change from phreatomagmatic to magmatic

  10. Graben formation during the Bárðarbunga rifting event in central Iceland

    NASA Astrophysics Data System (ADS)

    Ruch, Joël; Jónsson, Sigurjón; Wang, Teng; Xu, Wenbin; Trippanera, Daniele

    2015-04-01

    On the 16th of August 2014, an intense seismic swarm was detected at the Bárðarbunga caldera (central Iceland), which migrated to the east and then to the northeast during the following days. The swarm, highlighting magma propagation pathway from the caldera, migrated laterally during the following two weeks over 40 km. By the end of August, a volcanic eruption had started along a north-south oriented fissure located ~45 km from the caldera. Here we focus on the near-field deformation related to the dike emplacement in the shallow crust, which generated in few days an 8 km long by 0.8 km wide graben (depression) structure. The new graben extends from the northern edge of the Vatnajökull glacier and to the north to the eruptive fissure. We analyze the temporal evolution of the graben by integrating structural mapping using multiple acquisitions of TerraSAR-X amplitude radar images, InSAR and ground-truth data with GPS and structural measurements. Pixel-offset tracking of radar amplitude images shows clearly the graben subsidence, directly above the intrusion pathway, of up to 6 meters in the satellite line-of-sight direction. We installed a GPS profile of 15 points across the graben in October 2014 and measured its depth up to 8 meters, relative to the flanks of the graben. Field structural observations show graben collapse structures that typically accompany dike intrusions, with two tilted blocks dipping toward the graben axis, bordered by two normal faults. Extensive fractures at the center of the graben and at the graben edges show a cumulative extension of ~8 meters. The formation of the graben was also accompanied by strong seismic activity locally, constraining the time frame period of the main graben formation subsidence. Our results show a rare case of a graben formation captured from space and from ground observations. Such structures are the dominant features along rift zones, however, their formation remain poorly understood. The results also provide

  11. A multidisciplinary approach to unravel hydrothermal explosions: a case-study from Gengissig lake (Kverkfjöll volcano, Iceland)

    NASA Astrophysics Data System (ADS)

    Montanaro, Cristian; Scheu, Bettina; Gudmundsson, Magnus T.; Reynolds, Hannah I.; Dürig, Tobias; Strehlow, Karen; Rott, Stefanie; Dingwell, Donald B.

    2015-04-01

    On August 15, 2013, a small jökulhlaup occurred when the Gengissig ice-dammed lake drained at Kverkfjöll, a central volcano with an active geothermal area located at the northern edge of Vatnajökull. The lake level dropped by approximately 30 m, decreasing pressure on the lake bed and triggering several steam-driven explosions. The explosions involved the surficial part of a hydrothermally altered glacio-lacustrine deposit mainly composed of pyroclasts, lava fragments and volcanic bombs, interbedded with clay-rich layers. Small fans of ejecta were formed, reaching a distance of 1 km north of the lake covering an area of approximately 0.3 km2, with a maximum thickness of 40 cm at the crater walls. The explosions, triggered by the rapid boiling in the surficial geothermal reservoir which followed the abrupt decrease in confining pressure, ejected approximately 104 m3 of mostly loose material. The thermal and craterization energy, calculated for the explosion areas, are on the order of 10^11 and 10^10J, respectively. Comparison of the calculated energies with those estimated by the volume of the ejecta and the crater sizes, yields a good agreement between models and field data. Morphological analyses (SEM) were used for a qualitative estimation of amount of freshly-fragmented clasts in the ejected material revealing that a low but significant energy consumption by fragmentation occurred. Decompression experiments were performed in the lab mimicking the conditions due to the drainage of the lake. A large amount of fine material was produced in these experiments possibly indicating active fragmentation. Furthermore, ejection velocities of the particles of 40-50 m/s, measured via high-speed videos, are consistent with those estimated from the field. This study demonstrates how the effective combination of field and lab data together with theoretical modeling can provide robust constraints on energy release and partitioning for such low-magnitude yet hazardous, steam

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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