Skip to content

A geomorphological analysis of the 2021--2023 Fagradalsfjall eruption series

Madison Tuohy 1,2, Christopher W. Hamilton2, Brett Carr2, Birgir Vilhelm Óskarsson3, Joana Voigt4, Ármann Höskuldsson5,6, William Michael Moreland7, Ingibjorg Jonsdottir ^5,8 ^Þorvaldur Þórðarson8

  • Affiliations: 1Department of Geosciences, University of Arizona, Tucson, AZ, USA; 2Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA; 3Icelandic Institute of Natural History, Garðabær, Iceland; 4Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA; 5Institute of Earth Sciences, University of Iceland, Reykjavík, Iceland; 6Nordic Volcanological Center, Institute of Earth Sciences, University of Iceland, Reykjavík, Iceland; 7Icelandic Meteorological Office, Reykjavík, Iceland; 8Faculty of Earth Sciences, University ofIceland, Reykjavík, Iceland

  • Presentation type: Poster

  • Presentation time: Tuesday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 225

  • Programme No: 1.6.5

  • Theme 1 > Session 6

Abstract

Following a period of intense precursory activity, an eruption at Fagradalsfjall (Iceland) began on 19 March 2021. This eruption lasted six months, ending on 18 September 2021. A second eruption occurred 3--21 August 2022, and a third from 10 July to 5 August 2023. During these eruptions, we conducted numerous unoccupied aircraft system (UAS) flights, collecting high-resolution survey data for the active lava flows and resulting deposits. The UAS data provided exceptional spatial (cm-scale) and temporal resolution, enabling detailed analysis of lava emplacement dynamics, including channel flow and subsequent emplacement patterns through time-series digital elevation models (DEMs), orthomosaics, and videography. These data, combined with airplane surveys from Loftmyndir and the Icelandic Institute of Natural History, were used to generate high-resolution (1:600-scale) facies maps of the flow-field from multiple time steps for each eruption. These maps and subsequent analyses reveal the dynamic emplacement of basaltic lava flow-fields, shaped by complex topography, interactions with previously emplaced lava, and varying rheological behavior due to changes in cooling rate as open channels transitioned into thermally insulated internal pathways. Observations show that both 'a'ā and pāhoehoe lava types were common, but were typically associated with more complex "transitional" rubbly and spiny pāhoehoe units. The time-series of facies maps help to inform: (1) changes between cooling-limited and volume-limited emplacement styles in response to lava pathway evolution; and (2) the effects of surface disruption and lava cooling rate during "fill and spill" events that are characterized by sudden transitions in local effusion rate.