@article{GreenfieldWinderRawlinsonetal.2022,
  author    = {Greenfield, Tim and Winder, Tom and Rawlinson, Nicholas and Maclennan, John and White, Robert S. and {\´A}g{\´u}stsd{\´o}ttir, Thorbj{\"o}rg and Bacon, Conor Andrew and Brandsd{\´o}ttir, Bryndis and Eibl, Eva P. S. and Glastonbury-Southern, Esme and Gudnason, Egill {\´A}rni and Hersir, Gylfi P{\´a}ll and Hor{\´a}lek, Josef},
  title     = {Deep long period seismicity preceding and during the 2021 Fagradalsfjall eruption, Iceland},
  series = {Bulletin of volcanology : official journal of the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI)},
  volume    = {84},
  journal   = {Bulletin of volcanology : official journal of the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI)},
  number    = {12},
  publisher = {Springer},
  address   = {Berlin ; Heidelberg ; New York},
  issn      = {0258-8900},
  doi       = {10.1007/s00445-022-01603-2},
  pages     = {20},
  year      = {2022},
  abstract  = {We use a dense seismic network on the Reykjanes Peninsula, Iceland, to image a group of earthquakes at 10-12 km depth, 2 km north-east of 2021 Fagradalsfjall eruption site. These deep earthquakes have a lower frequency content compared to earthquakes located in the upper, brittle crust and are similar to deep long period (DLP) seismicity observed at other volcanoes in Iceland and around the world. We observed several swarms of DLP earthquakes between the start of the study period (June 2020) and the initiation of the 3-week-long dyke intrusion that preceded the eruption in March 2021. During the eruption, DLP earthquake swarms returned 1 km SW of their original location during periods when the discharge rate or fountaining style of the eruption changed. The DLP seismicity is therefore likely to be linked to the magma plumbing system beneath Fagradalsfjall. However, the DLP seismicity occurred similar to 5 km shallower than where petrological modelling places the near-Moho magma storage region in which the Fagradalsfjall lava was stored. We suggest that the DLP seismicity was triggered by the exsolution of CO2-rich fluids or the movement of magma at a barrier to the transport of melt in the lower crust. Increased flux through the magma plumbing system during the eruption likely adds to the complexity of the melt migration process, thus causing further DLP seismicity, despite a contemporaneous magma channel to the surface.},
  language  = {en}
}
@article{FlovenzWangHersiretal.2022,
  author    = {Fl{\´o}venz, {\´O}lafur G. and Wang, Rongjiang and Hersir, Gylfi P{\´a}ll and Dahm, Torsten and Hainzl, Sebastian and Vassileva, Magdalena and Drouin, Vincent and Heimann, Sebastian and Isken, Marius Paul and Gudnason, Egill {\´A}. and {\´A}g{\´u}stsson, Kristj{\´a}n and {\´A}g{\´u}stsd{\´o}ttir, Thorbj{\"o}rg and Hor{\´a}lek, Josef and Motagh, Mahdi and Walter, Thomas R. and Rivalta, Eleonora and Jousset, Philippe and Krawczyk, Charlotte M. and Milkereit, Claus},
  title     = {Cyclical geothermal unrest as a precursor to Iceland's 2021 Fagradalsfjall eruption},
  series = {Nature geoscience},
  volume    = {15},
  journal   = {Nature geoscience},
  number    = {5},
  publisher = {Nature Research},
  address   = {Berlin},
  issn      = {1752-0894},
  doi       = {10.1038/s41561-022-00930-5},
  pages     = {397 -- 404},
  year      = {2022},
  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.},
  language  = {en}
}