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Showing 1–7 of 7 results
Advanced filters: Author: Halldór Geirsson Clear advanced filters

  • The 2011 eruption of a 20-km-high volcanic plume from Grímsvötn Volcano, Iceland, led to the closure of northern European airspace. Geodetic measurements from the volcano reveal a correlation between plume height, surface deformation and magma-chamber pressure, with a delay of an hour, implying that volcanic-plume behaviour can be predicted before eruption onset.

    • Sigrún Hreinsdóttir
    • Freysteinn Sigmundsson
    • Bergrún Arna Óladóttir
    Research
    Nature Geoscience
    Volume: 7, P: 214-218

  • Retreating ice caps overlying volcanoes are thought to relieve surface pressure, causing enhanced magma generation and volcanic activity. Analysis of crustal stress during a dyke intrusion event associated with retreat of Iceland’s largest ice cap indicates that ice retreat could instead promote storage of magma in the crust, rather than eruption at the surface.

    • Andrew Hooper
    • Benedikt Ófeigsson
    • Erik Sturkell
    Research
    Nature Geoscience
    Volume: 4, P: 783-786

  • As observed for the 2021 Fagradalsfjall eruption in Iceland, a release of tectonic stress followed by a decline in deformation and seismicity rate may be a characteristic precursory activity for a certain class of eruptions.

    • Freysteinn Sigmundsson
    • Michelle Parks
    • Thorbjörg Ágústsdóttir
    ResearchOpen Access
    Nature
    Volume: 609, P: 523-528

  • Large-volume volcanic eruptions can occur despite only limited precursory activity. Here the authors show that modelling the combined effects of buoyant magma, viscoelastic earth behaviour, and sustained magma channels can explain such behaviour of volcanoes and gives an estimate of pressure evolution in magma bodies.

    • Freysteinn Sigmundsson
    • Virginie Pinel
    • Tadashi Yamasaki
    ResearchOpen Access
    Nature Communications
    Volume: 11, P: 1-11

  • Seismicity and ground deformation measurements show how a recent segmented dyke intrusion in the Bárðarbunga volcanic system in Iceland grew laterally for 45 kilometres over 14 days; dyke opening and seismicity were focused at the most distal segment, where lateral dyke growth with segment barrier breaking by pressure build-up occurred.

    • Freysteinn Sigmundsson
    • Andrew Hooper
    • Eva P. S. Eibl
    Research
    Nature
    Volume: 517, P: 191-195

  • The deformation style at moderately active volcanoes — such as Eyjafjallajökull, Iceland, which underwent an explosive summit eruption earlier this year — is little understood. These authors show that deformation associated with the eruptions at Eyjafjallajökull was unusual as it did not relate to pressure changes within a single magma chamber, and infer that this behaviour might be attributed to its off-rift setting with a 'cold' subsurface structure and limited magma at shallow depth.

    • Freysteinn Sigmundsson
    • Sigrún Hreinsdóttir
    • Kurt L. Feigl
    Research
    Nature
    Volume: 468, P: 426-430