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

Ólafur G. Flóvenz; Rongjiang Wang; Gylfi Páll Hersir; Torsten Dahm; Sebastian Hainzl; Magdalena Vassileva; Vincent Drouin; Sebastian Heimann; Marius Paul Isken; Egill Gudnason; Kristján Ágústsson; Thorbjörg Ágústsdóttir; Josef Horálek; Mahdi Motagh; Thomas R. Walter; Eleonora Rivalta; Philippe Jousset; Charlotte M. Krawczyk; Claus Milkereit

doi:10.1038/s41561-022-00930-5

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

Ólafur G. Flóvenz
, Rongjiang Wang
, Gylfi Páll Hersir
, Torsten Dahm
, Sebastian Hainzl
, Magdalena Vassileva
, Vincent Drouin
, Sebastian Heimann
, Marius Paul Isken
, Egill Gudnason
, Kristján Ágústsson
, Thorbjörg Ágústsdóttir
, Josef Horálek
, Mahdi Motagh
, Thomas R. Walter
, Eleonora Rivalta
, Philippe Jousset
, Charlotte M. Krawczyk
, Claus Milkereit

Engineering and Natural Sciences

University of Iceland

Research output: Contribution to journal › Article › peer-review

Abstract

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 km³ 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.

Original language	English
Pages (from-to)	397-404
Number of pages	8
Journal	Nature Geoscience
Volume	15
Issue number	5
DOIs	https://doi.org/10.1038/s41561-022-00930-5
Publication status	Published - May 2022

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Flóvenz, Ó. G., Wang, R., Hersir, G. P., Dahm, T., Hainzl, S., Vassileva, M., Drouin, V., Heimann, S., Isken, M. P., Gudnason, E., Ágústsson, K., Ágústsdóttir, T., Horálek, J., Motagh, M., Walter, T. R., Rivalta, E., Jousset, P., Krawczyk, C. M., & Milkereit, C. (2022). Cyclical geothermal unrest as a precursor to Iceland’s 2021 Fagradalsfjall eruption. Nature Geoscience, 15(5), 397-404. https://doi.org/10.1038/s41561-022-00930-5

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title = "Cyclical geothermal unrest as a precursor to Iceland{\textquoteright}s 2021 Fagradalsfjall eruption",

abstract = "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 km3 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.",

author = "Fl{\'o}venz, \{{\'O}lafur G.\} and Rongjiang Wang and Hersir, \{Gylfi P{\'a}ll\} and Torsten Dahm and Sebastian Hainzl and Magdalena Vassileva and Vincent Drouin and Sebastian Heimann and Isken, \{Marius Paul\} and Egill Gudnason and Kristj{\'a}n {\'A}g{\'u}stsson and Thorbj{\"o}rg {\'A}g{\'u}stsd{\'o}ttir and Josef Hor{\'a}lek and Mahdi Motagh and Walter, \{Thomas R.\} and Eleonora Rivalta and Philippe Jousset and Krawczyk, \{Charlotte M.\} and Claus Milkereit",

note = "Publisher Copyright: {\textcopyright} 2022, The Author(s), under exclusive licence to Springer Nature Limited.",

year = "2022",

month = may,

doi = "10.1038/s41561-022-00930-5",

language = "English",

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Flóvenz, ÓG, Wang, R, Hersir, GP, Dahm, T, Hainzl, S, Vassileva, M, Drouin, V, Heimann, S, Isken, MP, Gudnason, E, Ágústsson, K, Ágústsdóttir, T, Horálek, J, Motagh, M, Walter, TR, Rivalta, E, Jousset, P, Krawczyk, CM & Milkereit, C 2022, 'Cyclical geothermal unrest as a precursor to Iceland’s 2021 Fagradalsfjall eruption', Nature Geoscience, vol. 15, no. 5, pp. 397-404. https://doi.org/10.1038/s41561-022-00930-5

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T1 - Cyclical geothermal unrest as a precursor to Iceland’s 2021 Fagradalsfjall eruption

AU - Flóvenz, Ólafur G.

AU - Wang, Rongjiang

AU - Hersir, Gylfi Páll

AU - Dahm, Torsten

AU - Hainzl, Sebastian

AU - Vassileva, Magdalena

AU - Drouin, Vincent

AU - Heimann, Sebastian

AU - Isken, Marius Paul

AU - Gudnason, Egill

AU - Ágústsson, Kristján

AU - Ágústsdóttir, Thorbjörg

AU - Horálek, Josef

AU - Motagh, Mahdi

AU - Walter, Thomas R.

AU - Rivalta, Eleonora

AU - Jousset, Philippe

AU - Krawczyk, Charlotte M.

AU - Milkereit, Claus

PY - 2022/5

Y1 - 2022/5

N2 - 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 km3 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.

AB - 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 km3 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.

UR - https://www.scopus.com/pages/publications/85129252410

U2 - 10.1038/s41561-022-00930-5

DO - 10.1038/s41561-022-00930-5

M3 - Article

SN - 1752-0894

VL - 15

SP - 397

EP - 404

JO - Nature Geoscience

JF - Nature Geoscience

IS - 5

ER -

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

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