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Episodic oblique rifting events on the Reykjanes Peninsula, Iceland (2016--2024), imaged and modeled using InSAR and seismicity time series

Xingjun Luo1, 2, Nicolas Oestreicher2, 3, 4, Joël Ruch2, Wenbin Xu^1^

  • Affiliations: 1 Lab of Volcano and Earthquake Research, School of Geosciences and Info-Physics, Central South University, 410083 Changsha, China 2 Department of Earth Sciences, University of Geneva, Geneva, Switzerland 3 WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland 4 Climate Change, Extremes and Natural Hazards in Alpine Regions Research Centre CERC, Davos, Switzerland 

  • Presentation type: Poster

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

  • Poster Board Number: 51

  • Programme No: 2.3.37

  • Theme 2 > Session 3

Abstract

An earthquake swarm started in July 2017 marked the beginning of a new tectonic cycle on the Reykjanes Peninsula, followed by the onset of the Fagradalsfjall- Sundhnúkur eruptions in 2021. The mechanisms of awakening and the tectonic evolution of the plate boundary are, however, still poorly understood. To study the spatial and temporal evolution of the deformation, we integrated InSAR time series, GNSS data, and seismicity, discretizing the datasets in three key periods from 2017 to 2024 (pre-eruption, Fagradalsfjall, and Sundhnúkur eruption). These observations, together with source modeling of seismogenic faults, sills and dikes, reveal local and widespread deformation affecting the entire Peninsula already some years before the onset of the eruption sequence. The Fagradalsfjall dike, originating at a depth of around 10 km, and the three subsequent eruptions show a gradual growth of the dike in a northeasterly direction. Magma was then intruded into the Sundhnúkur rift zone (from Oct 2023) and caused more frequent eruption cycles with a marked decreasing intensity of the seismic activity for subsequent eruptions. The Sundhnúkur eruptive fissure, connected to the Svartsengi sill underwent 6 cycles of inflations-dike intrusions during the studied period. This work presents the first continuous InSAR timeseries covering the entire rifting episode that includes rapid deformation during earthquakes and eruptions for the Reykjanes Peninsula. It demonstrates the great potential of continuous geodetic and seismological observations for analyzing complex, long-term evolving volcanic-tectonic events.