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Dynamic Numerical Modelling of Volcanic Inflation at Bárðarbunga Volcanic System, Iceland, 2015-2024

Daniel John Christopher Manns1, James Hickey1 , Michelle Maree Parks2, Halldór Geirsson3, Freysteinn Sigmundsson3

  • Affiliations: 1Department of Earth and Environmental Sciences, University of Exeter, Penryn, UK; 2Icelandic Meteorological Office, Reykjavík, Iceland; 3Institute of Earth Sciences, University of Iceland, Reykjavík, Iceland 

  • Presentation type: Poster

  • Presentation time: Friday 16:30 - 18:00, Room Poster Hall

  • Poster Board Number: 41

  • Programme No: 2.3.27

  • Theme 2 > Session 3

Abstract

The 2014-2015 Holuhraun eruption was accompanied by ~65 metres of collapse of the ice-covered Bárðarbunga caldera, due to ~1.9 km3 of magma being extruded from beneath the caldera into a dyke. Post-eruptive observations indicate that the volcano began reinflating from July 2015. Deformation extends beyond the caldera, and outside the Vatnajökull ice cap. GNSS & InSAR data within a region up to ~20 km away from the caldera has been corrected for glacial isostatic adjustment and plate spreading, for the time period of July 2015 to September 2024. Vertical and horizontal deformation rates within this region range from 5 -- 20 mm/yr and 10 -- 50 mm/yr, respectively.  Unpublished data suggests >10 metres of uplift within the caldera. Here, we use dynamic poroelastic-reservoir finite element volcano deformation models to reproduce the observed post-eruptive deformation of the Bárðarbunga caldera system and constrain magma supply and storage characteristics. The models incorporate independent geochemical and geophysical data, and model simulation involves melt injection into a poroelastic reservoir within a heterogeneous elastic crust. Preliminary results show that incorporating a caldera ring fault into the model has a significant effect on the modelled deformation field, whereby the majority of the deformation occurs within the caldera. The likely deformation source is a sill-shaped magma reservoir ~10 kilometres beneath the caldera, which coincides with the base of the ring fault. The initial thickness of the sill reservoir is unknown, but has been modelled here as 10 metres, with an opening since 2015 of >10 metres.