Skip to content

Investigating the Seasonal Snow and Hydrological Ground Deformation Signals at Katla Volcano, Iceland

Catherine O'Hara 1, Freysteinn Sigmundsson1, Fabien Albino2, Halldór Geirsson1, Michelle Parks3, Elisa Trasatti4, Benedikt Ófeigsson3

  • Affiliations: 1Institute of Earth Sciences, University of Iceland, Iceland; 2Institut des Sciences de la Terre, Université Grenoble-Alpes, France; 3Icelandic Meteorological Office, Iceland; 4Istituto Nazionale di Geofisica e Vulcanologia, Italy

  • Presentation type: Talk

  • Presentation time: Monday 14:45 - 15:00, Room R290

  • Programme No: 3.3.7

  • Theme 3 > Session 3

Abstract

Mass unloading at volcanic edifices has the potential to influence the stability of magma bodies---either bringing them closer or further from failure. Katla volcano in Iceland underlies Mýrdalsjökull, the fourth largest glacier in Iceland, but undergoes the largest seasonal deformation of all Icelandic volcanoes; up to 4 cm and 5 cm horizontally and vertically, respectively, at AUST GNSS station. The last confirmed eruption of Katla occurred in 1918, but there has been elevated seismicity and jökulhlaups recorded at the volcano in 1955, 1999, 2011, and 2024. A series of jökulhlaups have occurred at Katla since July 2024 which have caused up to 7 cm of horizontal deformation at AUST during one jökulhlaup. In this work, an elastic, 3D Finite Element (FE) model, using COMSOL Multiphysics, including realistic topography and ice unloading based on recent data from Mýrdalsjökull, was created to investigate the effects of seasonal load variations on the observed deformation signal and changes in failure threshold and failure location at a magma body. Seasonality in the hydrologic system is also modeled to see if it recreates the observed deformation during jökulhlaups at Katla. The predicted deformation from the FE model is compared to the observed GNSS time series from Katla to discern if seasonal snow loading and/or pressure modulation in a magma body can explain the deformation. 3D flat, homogenous, elastic FE models of a simple seasonal snow load can explain part of the observed deformation signal in both the horizontal and vertical components.