Skip to content

Magma intrusion at Askja Caldera, Iceland, between 2021 and 2023 constrained by modelling of microgravity and deformation data

Josefa Sepúlveda-Araya1, Andrew Hooper1, Elske de Zeeuw - van Dalfsen2,3, Susanna Ebmeier1, Michelle Parks5, Freysteinn Sigmundsson4, Yilin Yang4, Milan Lazecky1, Rachel Bilsland1, Mathijs Koymans3, Chiara Lanzi5,4

  • Affiliations: 1COMET School of Earth and Environment, University of Leeds, Woodhouse Lane, Leeds LS29JT, West Yorkshire, United Kingdom 2Department of Seismology and Acoustics, Royal Netherlands Meteorological Institute, Utrechtseweg 297, De Bilt 3731 GA, Utrecht, the Netherlands 3Geoscience and Remote Sensing, Delft University of Technology, Stevinweg 1, Delft 2628 CN, Zuid-Holland, the Netherlands 4Nordic Volcanological Center, Institute of Earth Sciences, University of Iceland, Sturlugata 7 - Askja, Reykjavík 101, Iceland 5Icelandic Meteorological Office, Reykjavik, Iceland

  • Presentation type: Poster

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

  • Poster Board Number: 7

  • Programme No: 1.5.14

  • Theme 1 > Session 5

Abstract

We present results indicating that the uplift at Askja observed from 2022 to 2023 is consistent with the intrusion of magma into a sub-volcanic reservoir at 2.8 km depth. Askja, a volcano in the Northeast of Iceland, hosts three calderas, with the youngest having been formed during the 1875-1876 rift event. The last eruption was a Hawaiian-style event that occurred in 1961. Since then, Askja has been monitored using levelling, GNSS and InSAR, showing alternating periods of subsidence and uplift. After decades of subsidence, an uplift was observed in July 2021 at an initial rate of ~700 mm/yr, decreasing to ~350 mm/yr, briefly halting in 2023 and resuming in April 2024. Recent studies have concluded that a new intrusion of magma causes this uplift.  Here, we test the nature of the intrusion and the origin of the magma. Microgravity data collected in 2022 and 2023 indicate a mass increase of 9.2*1012 kg beneath the volcano during this period. Joint modelling of the microgravity and the deformation data, assuming an ellipsoidal intrusion into elastic crust, gives a mass intrusion density of 2350 ± 550 kg/m³, corresponding to a basaltic magma. To understand the influence of a non-elastic regime on the modelled microgravity and deformation, we have built a finite element model that consists of a melt reservoir surrounded by a poroelastic mush. We explore a realistic range of parameters for this model and compare them to the surface data.