Skip to content

Deformation dynamics on a topographic high: Insights from Mount Thorbjörn, Southwest Iceland, during the 2023-2024 Svartsengi volcanic crisis

Maria Hurley 1,2, Nicolas Oestreicher3,4, Alina V. Shevchenko1, Benjamin F. De Jarnatt1,2, Egill Á. Gudnason5, Joël Ruch4, Alea Joachim2, Gylfi P. Hersir5, Gregory P. De Pascale6, Magnús T. Gudmundsson6, Fabio L. Bonali7, Thomas R. Walter1,2

  • Affiliations: 1GFZ German Research Centre for Geosciences, Potsdam, Germany; 2University of Potsdam, Institute of Geosciences, Potsdam, Germany; 3WSL-Institut für Schnee- und Lawinenforschung SLF, Davos, Switzerland; 4Department of Earth Sciences, University of Geneva, Geneva, Switzerland; 5Iceland GeoSurvey (ÍSOR), Kópavogur, Iceland; 6Institute of Earth Sciences, University of Iceland, Reykjavik, Iceland; 7University of Milano-Bicocca, Milano, Italy

  • Presentation type: Poster

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

  • Poster Board Number: 30

  • Programme No: 2.3.16

  • Theme 2 > Session 3

Abstract

Deep magmatic processes induce deformation patterns that depend on near-surface structural features. Topographic highs and pre-existing weaknesses tend to localise and amplify crustal deformation, making them essential factors to consider when applying geodetic methods and assessing related hazards. There are few studies detailing the link between topography and fracturing, therefore limited insights into this interplay. Real-time deformation monitoring at Mount Thorbjörn, a faulted and fractured 200-meter-high table mountain in the currently active Svartsengi Volcanic System, provides a unique opportunity to observe topography-fracturing interactions and evolution. We collected four drone photogrammetric datasets between 2022 and 2024, covering different stages of the volcanic unrest. We compare centimeter-resolution orthophotos and digital elevation models and identify the reactivation of pre-existing graben systems in November 2023, with individual faults showing dip-slip of up to ~80 cm and dextral strike-slip of up to ~30 cm. Vertical displacements are more pronounced in the southeastern sector, suggesting a local tilting of the edifice consistent with the main November 2023 graben. Orthophoto comparison allows us to map almost 10 km of new cumulative surface fractures and over 100 sinkholes, 88% of the fractures and 50% of the sinkholes formed during the November 2023 graben event. Statistical analyses and sandbox analogue experiments show how fracture density and geometry correlate with topography, with higher areas experiencing more and intense fault reactivation, surface cracking, sinkholes and slope instabilities. We provide a generalized conceptual model for fracture development in complex volcanic landscapes, helpful to anticipate potential impacts in volcanic systems elsewhere.