Dynamic coupling between faulting, rifting and magmatism during 2021-2025 unrest on Reykjanes Peninsula, Iceland

Geophysical Research Letters
By: , and 

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Abstract

Interactions among faulting, earthquakes, and eruptions are fundamental to plate tectonics and hazard forecasting yet rarely observed along mid-ocean ridges. On Iceland's Reykjanes Peninsula, seismotectonic–volcanic unrest resumed after nearly 800-year hiatus, providing an opportunity to observe these interactions during 2021–2025 activity. By integrating high-resolution seismicity, focal mechanisms, satellite geodesy, surface deformation, and eruption data, we document ∼4 m of total extension accommodated through 14 rifting episodes. The largest, in 2023, involved graben reactivation and diking, with seismic swarms and earthquake faulting that matched the surface ruptures, where strike-slip faulting preceded normal-faulting earthquakes and extension. The accrued extension was released by extension fractures triggered by magma accumulation. Long-term observations show no correlation between erupted magma volume, seismicity, and crustal extension. This highlights dynamic relation between rifting, faulting, and magmatism in transtensional settings and their implications for hazard assessment.

Suggested Citation

Fischer, T.J., Hrubcová, P., Vlček, J., de Pascale, G., Thordarson, T., Geirsson, H., Lomax, A., and Skoumal, R.J., 2026, Dynamic coupling between faulting, rifting and magmatism during 2021-2025 unrest on Reykjanes Peninsula, Iceland: Geophysical Research Letters, v. 53, no. 10, e2026GL122058, 10 p., https://doi.org/10.1029/2026GL122058.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Dynamic coupling between faulting, rifting and magmatism during 2021-2025 unrest on Reykjanes Peninsula, Iceland
Series title Geophysical Research Letters
DOI 10.1029/2026GL122058
Volume 53
Issue 10
Publication Date May 15, 2026
Year Published 2026
Language English
Publisher American Geophysical Union
Contributing office(s) Earthquake Science Center
Description e2026GL122058, 10 p.
Country Iceland
Other Geospatial Reykjanes Peninsula
Additional publication details