Skip to main content
SpringerLink
Log in

Pre-existing fractures and eruptive vent openings during the 2021 Fagradalsfjall eruption, Iceland

  • Research Article
  • Published:
Bulletin of Volcanology Aims and scope Submit manuscript

Abstract

The Fagradalsfjall eruption commenced on 19 March 2021 on a ~180-m-long eruptive fissure, following a 23-day dike intrusion. New eruptive fissures opened northeast of the initial eruption site on 5, 6–7, 10, and 13 April 2021. The northernmost eruption occurred on 5 April, approximately 1 km northeast of the initial fissure, with the other fissure openings between this and the initial eruptive vents. Still images from web cameras and time-lapse cameras are available for five of the fissure openings. These data show that the eruptions were preceded by steam emitted from cracks in the exact locations where the eruptions started. The time between the first steam observations and the visual appearance of glowing lava ranged between 15 s and 1.5 min during night observations and from 9 to 23 min during daytime observations. The difference in observation time is likely explained by the different lighting conditions. The eruptive vents are located where the north-easterly oriented dike intersected pre-existing north-south-oriented fractures, inferred to be strike-slip faults. These fractures could be identified on a high-resolution ICEYE interferogram as well as on pre-existing aerial photographs and digital elevation models. This interferogram spanned the first day of the eruption (19–20 March 2021). It not only displays deformation related to the pre-eruptive dike intrusion but also shows lineations in locations where eruptive vent openings occurred later in April 2021. These findings demonstrate how Interferometric Synthetic Aperture Radar Analysis (InSAR) can be used to forecast likely locations of subsequent eruptive vent openings, which is of great importance for hazard assessment and defining exclusion zones during fissure eruptions.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9

Similar content being viewed by others

References

  • Abdallah A, Courtillot V, Kasser M, Ledain AY, Lepine JC, Robineau B, Ruegg JC, Tapponnier P, Tarantola A (1979) Relevance of Afar seismicity and volcanism to the mechanics of accreting plate boundaries. Nature 282(5734):17–23

    Google Scholar 

  • Adiyaman Ö, Chorowicz J, Köse O (1998) Relationships between volcanic patterns and neotectonics in Eastern Anatolia from analysis of satellite images and DEM. J Volcanol Geotherm Res 85(1-4):17–32

    Google Scholar 

  • Al Shehri A, Gudmundsson A (2018) Modelling of surface stresses and fracturing during dyke emplacement: application to the 2009 episode at Harrat Lunayyir, Saudi Arabia. J Volcanol Geotherm Res 356:278–303

    Google Scholar 

  • Árnadóttir T, Lund B, Jiang W, Geirsson H, Björnsson H, Einarsson P, Sigurðsson T (2009) Glacial rebound and plate spreading: results from the first countrywide GPS observations in Iceland. Geophys J Int 177(2):691–716

    Google Scholar 

  • Bagnardi M, Hooper A (2018) Inversion of surface deformation data for rapid estimates of source parameters and uncertainties: a Bayesian approach. Geochemistry, Geophys Geosystems 19(7):2194–2211

    Google Scholar 

  • Barsotti S, Parks MM, Pfeffer MA, Óladóttir BA, Barnie T, Titos MM, Jónsdóttir K, Pedersen G, Hjartardóttir ÁR, Stefansdóttir G, Jóhannsson T, Arason Þ, Gudmundsson MT, Oddsson B, Þrastarson RH, Ófeigsson BG, Vogfjörd K, Geirsson H, Hjörvar T, von Löwis S, Petersen GN, Sigurðsson EM (2023) The eruption in Fagradalsfjall (2021, Iceland): how the operational monitoring and the volcanic hazard assessment contributed to its safe access. Nat Hazards 116:3063–3092

  • Bazargan M, Gudmundsson A (2019) Dike-induced stresses and displacements in layered volcanic zones. J Volcanol Geotherm Res 384:189–205

    Google Scholar 

  • Biggs J, Amelung F, Gourmelen N, Dixon TH, Kim SW (2009) InSAR observations of 2007 Tanzania rifting episode reveal mixed fault and dyke extension in an immature continental rift. Geophys J Int 179(1):549–558

    Google Scholar 

  • Björnsson A, Sæmundsson K, Einarsson P, Tryggvason E, Grönvold K (1977) Current rifting episode in North Iceland. Nature 266:318–323

    Google Scholar 

  • Björnsson S, Einarsson P, Tulinius H, Hjartardóttir ÁR (2020) Seismicity of the Reykjanes Peninsula 1971–1976. J Volcanol Geotherm Res 391:106369

    Google Scholar 

  • Bruce PM, Huppert HE (1990) Solidification and melting along dykes by the laminar flow of basaltic magma. In: Ryan MP (ed) Magma transport and storage (chapter 6). John Wiley & Sons Ltd, pp 87–101

    Google Scholar 

  • Clifton AE, Kattenhorn SA (2006) Structural architecture of a highly oblique divergent plate boundary segment. Tectonophysics 419(1-4):27–40

    Google Scholar 

  • DeMets C, Gordon RG, Argus DF, Stein S (1994) Effect of recent revisions to the geomagnetic reversal time-scale on estimates of current plate motions. Geophys Res Lett 21(20):2191–2194

    Google Scholar 

  • Einarsson P (1991) Earthquakes and present-day tectonism in Iceland. Tectonophysics 189(1-4):261–279

    Google Scholar 

  • Einarsson P (2008) Plate boundaries, rifts and transforms in Iceland. Jökull 58:35–58

    Google Scholar 

  • Einarsson P, Brandsdóttir B (2021) Seismicity of the Northern Volcanic Zone of Iceland. Front Earth Sci 9:166

    Google Scholar 

  • Einarsson P, Eyjólfsson V, Hjartardóttir ÁR (2023) Tectonic framework and fault structures in the Fagradalsfjall segment of the Reykjanes Peninsula Oblique Rift, Iceland. Bull Volcanol 85(2):9

    Google Scholar 

  • Einarsson P, Hjartardóttir ÁR, Imsland P, Hreinsdóttir S (2020) The structure of seismogenic strike-slip faults in the eastern part of the Reykjanes Peninsula oblique rift. SW Iceland. J Volcanol Geotherm Res 391:106372

    Google Scholar 

  • Einarsson P, Sæmundsson K (1987) Earthquake epicenters 1982-1985 and volcanic systems in Iceland (map). In: Sigfússon ÞI (ed) Í hlutarins eðli, Festschrift for Þorbjörn Sigurgeirsson. Menningarsjóður, Reykjavík

    Google Scholar 

  • Eyjólfsson V (1998) Mapping of fractures and Holocene volcanic fissures at Fagradalsfjall in the western Reykjanes Peninsula (B.Sc. thesis, in Icelandic). In: Faculty of Earth Sciences. University of Iceland, Reykjavík, Iceland, p 70

    Google Scholar 

  • Gallagher CR (2021) The timing and mechanisms of sulfur release by Icelandic flood lava eruptions:Holuhraun 2014–15 CE and Laki 1783–84 CE a case study. In: Faculty of Earth Sciences. University of Iceland, Reykjavík

    Google Scholar 

  • Geirsson H, Parks M, Vogfjörd K, Einarsson P, Sigmundsson F, Jónsdóttir K, Drouin V, Ófeigsson BG, Hreinsdóttir S, Ducrocq C (2021) The 2020 volcano-tectonic unrest at Reykjanes Peninsula, Iceland: stress triggering and reactivation of several volcanic systems. EGU General Assembly Conference Abstracts: EGU21–E7534

    Google Scholar 

  • Gudmundsson A (2020) Volcanotectonics: understanding the structure, deformation and dynamics of volcanoes. Cambridge University Press, p 598

    Google Scholar 

  • Gudmundsson A (2022) The propagation paths of fluid-driven fractures in layered and faulted rocks. Geological Magazine, pp 1–24

    Google Scholar 

  • Guðmundsson Á (1987) Geometry, formation and development of tectonic fractures on the Reykjanes peninsula, southwest Iceland. Tectonophysics 139(3-4):295–308

    Google Scholar 

  • Halldórsson SA, Marshall EW, Caracciolo A, Matthews S, Bali E, Rasmussen MB, Ranta E, Robin JG, Guðfinnsson GH, Sigmarsson O, Maclennan J, Jackson MG, Whitehouse MJ, Jeon H, van der Meer QHA, Mibei GK, Kalliokoski MH, Repczynska MM , Rúnarsdóttir RH, Sigurðsson G, Pfeffer MA, Scott SW, Kjartansdóttir R, Kleine BI, Oppenheimer C, Aiuppa A, Ilyinskaya E, Bitetto M, Giudice G, Stefánsson A (2022) Rapid shifting of a deep magmatic source at Fagradalsfjall volcano, Iceland. Nature 609:529–534

  • Hjaltadóttir S, Vogfjörð KS (2006) Kortlagning sprungna í Fagradalsfjalli á Reykjanesskaga með smáskjálftum. Technical report, Iceland Meteorological Office, 2006a. Report VÍ-ES-01

    Google Scholar 

  • Hjartardóttir ÁR, Einarsson P, Gudmundsson MT, Högnadóttir T (2016) Fracture movements and graben subsidence during the 2014 Bárðarbunga dike intrusion in Iceland. J Volcanol Geotherm Res 310:242–252

    Google Scholar 

  • Hreinsdóttir S, Einarsson P, Sigmundsson F (2001) Crustal deformation at the oblique spreading Reykjanes Peninsula, SW Iceland: GPS measurements from 1993 to 1998. Journal of Geophysical Research: Solid Earth 106(B7):13803–13816

    Google Scholar 

  • Jakobsdóttir SS (2008) Seismicity in Iceland: 1994-2007. Jökull 58:75–100

    Google Scholar 

  • Jenness MH, Clifton AE (2009) Controls on the geometry of a Holocene crater row: a field study from southwest Iceland. Bull Volcanol 71(7):715–728

    Google Scholar 

  • Jónsson J (1978) Geological map of the Reykjanes Peninsula. Orkustofnun, report OS-JHD 7831:332

    Google Scholar 

  • Keiding M, Lund B, Árnadóttir T (2009) Earthquakes, stress, and strain along an obliquely divergent plate boundary: Reykjanes Peninsula, Southwest Iceland. J Geophys Res Solid Earth 114:B09306

  • Khodayar M, Einarsson P (2002) Strike-slip faulting, normal faulting, and lateral dike injections along a single fault: field example of the Gljúfurá fault near a Tertiary oblique rift-transform zone, Borgarfjörður, west Iceland. J Geophys Res 107(B5):ETG 5-1-ETG 5-16

    Google Scholar 

  • Klein FW, Einarsson P, Wyss M (1977) Reykjanes peninsula, Iceland, earthquake swarm of september 1972 and its tectonic significance. J Geophys Res 82(5):865–888

    Google Scholar 

  • Nakamura K (1977) Volcanoes as possible indicators of tectonic stress orientation — principle and proposal. J Volcanol Geotherm Res 2(1):1–16

    Google Scholar 

  • Neal CA, Brantley S, Antolik L, Babb J, Burgess M, Calles K, Cappos M, Chang J, Conway S, Desmither L (2019) The 2018 rift eruption and summit collapse of Kīlauea Volcano. Science 363(6425):367–374

    Google Scholar 

  • Okada Y (1985) Surface deformation due to shear and tensile faults in a half-space. Bull Seismol Soc Am 75(4):1135–1154

    Google Scholar 

  • Pedersen G, Grosse P (2014) Morphometry of subaerial shield volcanoes and glaciovolcanoes from Reykjanes Peninsula, Iceland: effects of eruption environment. J Volcanol Geotherm Res 282:115–133

    Google Scholar 

  • Pedersen GB, Belart JM, Óskarsson BV, Gudmundsson MT, Gies N, Högnadóttir T, Hjartardóttir ÁR, Pinel V, Berthier E, Dürig T, Reynolds HI, Hamilton CW, Valsson G, Einarsson P, Ben-Yehosua D, Gunnarsson A, Oddsson B (2022) Volume, effusion rate, and lava transport during the 2021 Fagradalsfjall eruption: results from near real-time photogrammetric monitoring. Geophys Res Lett 49(13):e2021GL097125

    Google Scholar 

  • Pollard DD, Delaney PT, Duffield WA, Endo ET, Okamura AT (1983) Surface deformation in volcanic rift zones. Tectonophysics 94(1):541–584

    Google Scholar 

  • Porter C, Morin P, Howat I, Noh MJ, Bates B, Peterman K, Keesey S, Schlenk M, Gardiner J, Tomko, K, Willis M, Kelleher C, Cloutier M, Husby E, Foga S, Nakamura H, Platson M, Wethington MJ, Williamson C, Bauer G, Enos J, Arnold G, Kramer W, Becker P, Doshi A, D'Souza C, Cummens P, Laurier F, Bojesen M (2018)  ArcticDEM, V1. https://doi.org/10.7910/DVN/OHHUK

  • Rossetti F, Storti F, Salvini F (2000) Cenozoic noncoaxial transtension along the western shoulder of the Ross Sea, Antarctica, and the emplacement of McMurdo dyke arrays. Terr Nova 12(2):60–66

    Google Scholar 

  • Ruch J, Wang T, Xu W, Hensch M, Jónsson S (2016) Oblique rift opening revealed by reoccurring magma injection in central Iceland. Nature Comm 7:12352

  • Sæmundsson K (1978) Fissure swarms and central volcanoes of the neovolcanic zones of Iceland. In: Bowes DR, Leake BE (eds) Crustal evolution in northwestern Britain and adjacent regions. Seel House Press, Liverpool, England, pp 415–432

    Google Scholar 

  • Sæmundsson K, Jóhannesson H, Hjartarson Á, Kristinsson SG, Sigurgeirsson MÁ (2010) Geological map of Southwest Iceland. Iceland Geosurvey

  • Sæmundsson K, Sigurgeirsson MÁ (2013) Reykjanesskagi. In: Sólnes J, Sigmundsson F, Bessason B (eds) Náttúruvá. Viðlagatrygging Íslands / Háskólaútgáfan, Reykjavík, pp 379–401

    Google Scholar 

  • Sæmundsson K, Sigurgeirsson MÁ, Friðleifsson GÓ (2020) Geology and structure of the Reykjanes volcanic system. Iceland. J Volcanol Geotherm Res 391:106501

    Google Scholar 

  • Sella GF, Dixon TH, Mao AL (2002) REVEL: a model for recent plate velocities from space geodesy. J Geophys Res-Solid Earth 107(B4):2081

  • Sigmundsson F, Hooper A, Hreinsdottir S, Vogfjord KS, Ofeigsson BG, Heimisson ER, Dumont S, Parks M, Spaans K, Gudmundsson GB, Drouin V, Arnadottir T, Jonsdottir K, Gudmundsson MT, Hognadottir T, Fridriksdottir HM, Hensch M, Einarsson P, Magnusson E, Samsonov S, Brandsdóttir B, White RS, Ágústsdóttir Th, Greenfield T, Green RG, Hjartardóttir ÁR, Pedersen R, Bennett RA, Geirsson H, La Femina PC, Björnsson H, Pálsson F, Sturkell E, Bean CJ, Möllhoff M, Braiden AK, Eibl EPS (2015) Segmented lateral dyke growth in a rifting event at Bardarbunga volcanic system, Iceland. Nature 517(7533):191–195

    Google Scholar 

  • Sigmundsson F, Parks M, Hooper A, Geirsson H, Vogfjörd KS, Drouin V, Ófeigsson BG, Hreinsdóttir S, Hjaltadóttir S, Jónsdóttir K (2022) Deformation and seismicity decline before the 2021 Fagradalsfjall eruption. Nature 609:23–528

  • Sigurdsson O (1980) Surface deformation of the Krafla fissure swarm in two rifting events. J Geophys-Zeitschrift Fur Geophysik 47(1-3):154–159

    Google Scholar 

  • Spacapan JB, Galland O, Leanza HA, Planke S (2016) Control of strike-slip fault on dyke emplacement and morphology. J Geol Soc 173(4):573–576

    Google Scholar 

  • The National Land Survey of Iceland, ÍslandsDEM, V1 (2020). https://gatt.lmi.is/geonetwork/srv/metadata/e6712430-a63c-4ae5-9158-c89d16da6361

  • Tibaldi A, Pasquarè F, Tormey D (2009) Volcanism in reverse and strike-slip fault settings. In: New frontiers in integrated solid earth sciences. Springer, pp 315–348

    Google Scholar 

  • Trippanera D, Acocella V, Ruch J, Abebe B (2015) Fault and graben growth along active magmatic divergent plate boundaries in Iceland and Ethiopia. Tectonics 34(11):2318–2348

    Google Scholar 

  • Villemin T, Bergerat F (2013) From surface fault traces to a fault growth model: the Vogar Fissure Swarm of the Reykjanes Peninsula, Southwest Iceland. J Struct Geol 51(0):38–51

    Google Scholar 

  • Wright TJ, Ebinger C, Biggs J, Ayele A, Yirgu G, Keir D, Stork A (2006) Magma-maintained rift segmentation at continental rupture in the 2005 Afar dyking episode. Nature 442(7100):291–294

    Google Scholar 

  • Wright TJ, Sigmundsson F, Ayele A, Belachew M, Brandsdóttir B, Calais E, Ebinger C, Einarsson P, Hamling I, Keir D, Lewi E, Pagli C, Pedersen R (2012) Geophysical constraints on the dynamics of spreading centres from rifting episodes on land. Nat Geosci 5:242–250

    Google Scholar 

Download references

Acknowledgements

We would like to express our gratitude to the Icelandic Coast Guard which assisted us and other scientists to get to areas which were difficult to access on land. We would also like to thank the Iceland Aviation Service and the Garðaflug Corp. as well as the pilots Ú. Henningsson, G. Halldórsdóttir, K. Kárason, G. Árnason, and J. Sverrisson for their assistance during the eruption. B. Abera, A. Bergþórsdóttir, and A. Blischke assisted us during field work. F. Sigmundsson provided an image of the eruption. We would also like to thank the Morgunblaðið newspaper and the Icelandic National Broadcasting Service (Ríkisútvarpið) for the data from their webcameras. The ArcticDEMs were provided by the Polar Geospatial Center under NSF-OPP awards 1043681, 1559691, and 1542736. We thank the editor and the two anonymous reviewers of this paper for their constructive comments. Á.R. Hjartardóttir was partly funded by the Icelandic Research Fund (grant number: 196226-052).

Author information

Authors and Affiliations

  1. Institute of Earth Sciences, University of Iceland, Reykjavík, Iceland

    Ásta Rut Hjartardóttir, Tobias Dürig, Vigfús Eyjólfsson, Hannah Reynolds, Páll Einarsson, Joaquín M. C. Belart & Gro B. M. Pedersen

  2. Icelandic Meteorological Office, Reykjavík, Iceland

    Michelle Parks, Vincent Drouin & Esther Hlíðar Jensen

  3. Icelandic Institute of Natural History, Garðabær, Iceland

    Birgir Vilhelm Óskarsson & Nils B. Gies

  4. National Land Survey of Iceland, Akranes, Iceland

    Joaquín M. C. Belart

  5. University of Geneva, Geneva, Switzerland

    Joël Ruch

  6. Institute of Geological Sciences, University of Bern, Bern, Switzerland

    Nils B. Gies

Authors
  1. Ásta Rut Hjartardóttir
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Tobias Dürig
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Michelle Parks
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Vincent Drouin
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Vigfús Eyjólfsson
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Hannah Reynolds
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Páll Einarsson
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Esther Hlíðar Jensen
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. Birgir Vilhelm Óskarsson
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. Joaquín M. C. Belart
    View author publications

    You can also search for this author in PubMed Google Scholar

  11. Joël Ruch
    View author publications

    You can also search for this author in PubMed Google Scholar

  12. Nils B. Gies
    View author publications

    You can also search for this author in PubMed Google Scholar

  13. Gro B. M. Pedersen
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Ásta Rut Hjartardóttir.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Á. Höskuldsson

This paper constitutes part of a topical collection:

Low intensity basalt eruptions: the 2021 Geldingadalir and 2022 Meradalir eruptions of the Fagradalsfjall Fires, SW Iceland.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Hjartardóttir, Á.R., Dürig, T., Parks, M. et al. Pre-existing fractures and eruptive vent openings during the 2021 Fagradalsfjall eruption, Iceland. Bull Volcanol 85, 56 (2023). https://doi.org/10.1007/s00445-023-01670-z

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doi.org/10.1007/s00445-023-01670-z

Keywords

Search

Navigation