Cyclical geothermal unrest as a precursor to Iceland’s 2021 Fagradalsfjall eruption

0557212 - GFÚ 2023 RIV GB eng J - Journal Article
Flóvenz, Ó. G. - Wang, R. - Hersir, G. P. - Dahm, T. - Hainzl, S. - Vassileva, M. - Drouin, V. - Heimann, S. - Isken, M. P. - Gudnason, E. Á. - Ágústsson, K. - Ágústsdóttir, T. - Horálek, Josef - Motagh, M. - Walter, T. R. - Rivalta, A. - Jousset, P. - Krawczyk, C. M. - Milkereit, C.
Cyclical geothermal unrest as a precursor to Iceland’s 2021 Fagradalsfjall eruption.
Nature Geoscience. Roč. 15, May (2022), s. 397-404. ISSN 1752-0894. E-ISSN 1752-0908
Institutional support: RVO:67985530
Keywords : surface deformation * Reykjanes peninsula * earthquakes
OECD category: Volcanology
Impact factor: 18.3, year: 2022
Method of publishing: Open access
https://www.nature.com/articles/s41561-022-00930-5

Understanding and constraining the source of geodetic deformation in volcanic areas is an important component of hazard assessment. Here, we analyse deformation and seismicity for one year before the March 2021 Fagradalsfjall eruption in Iceland. We generate a high-resolution catalogue of 39,500 earthquakes using optical cable recordings and develop a poroelastic model to describe three pre-eruptional uplift and subsidence cycles at the Svartsengi geothermal field, 8 km west of the eruption site. We find the observed deformation is best explained by cyclic intrusions into a permeable aquifer by a fluid injected at 4 km depth below the geothermal field, with a total volume of 0.11 +/- 0.05 km(3) and a density of 850 +/- 350 kg m(-3). We therefore suggest that ingression of magmatic CO2 can explain the geodetic, gravity and seismic data, although some contribution of magma cannot be excluded. Ingression of magmatic gas into a geothermal aquifer generated cyclical deformation and primed the system for the 2021 Fagradalsfjall eruption, Iceland, according to a catalogue of 39,500 precursory earthquakes combined with a poroelastic model.
Permanent Link: http://hdl.handle.net/11104/0331274