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Evolution of volcanic eruptions with environmental change at Katla and Eyjafjallajökull volcanoes

Rosie Cole1 , Magnús Tumi Gudmundsson1, Elisa Piispa1, Birgir Vilhelm Óskarsson2, Catherine Gallagher1, Brian Jicha3

  • Affiliations: 1Institute of Earth Sciences, University of Iceland, Reykjavík, Iceland; 2Natural Science Institute of Iceland, Garðabær, Iceland; 3WiscAr Laboratory, University of Wisconsin-Madison, Madison, USA.

  • Presentation type: Poster

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

  • Poster Board Number: 7

  • Programme No: 6.1.13

  • Theme 6 > Session 1

Abstract

The effect of climate-induced environmental change on eruptive style at glaciated volcanoes is poorly understood. Most studies of subglacial or ice-marginal volcanic eruptions focus on monogenetic volcanoes or individual eruptions where the environmental conditions are considered constant. Polygenetic volcanoes, however, erupt over millennial timescales and have the potential to record eruptive behaviour throughout climatic and environmental change. We present a new geological map of a >50-kyr sequence of volcanic products exposed in the dissected flanks of Katla and Eyjafjallajökull volcanoes. We use known stratigraphic markers, the Þórsmörk ignimbrite and Vedde-composition pumices to constrain the time interval of eruptions. Additionally, 40Ar/39Ar and paleomagnetic dating of lavas provide a more detailed chronology of eruptions and environmental change. The sequence consists of hyaloclastite-lava sheets, hyalotuffs, intrusions, pillow lavas, breccias and ice-confined lava flows. The variety of products reflects eruptions beneath a fluctuating ice sheet with temporal variations in meltwater accumulation. Subaerial lavas and ignimbrites indicate glacial cover was punctuated by locally ice-free conditions. The penultimate eruptive phase exposed is a lava delta that prograded into an englacial lake, coincident with retreat of the Icelandic Ice Sheet. In addition, glacial outburst floods associated with eruptions in a destabilising ice sheet helped to incise deep valleys that expose the sequence. We propose that climate-induced environmental change influenced eruption styles at Katla and Eyjafjallajökull. Given the ongoing reduction of glaciers at ice-capped volcanoes, it is critical to better understand how eruptive behaviour might evolve with changing glacial and hydrological conditions.