Deep long period seismicity preceding and during the 2021 Fagradalsfjall eruption, Iceland ...

• Main Authors: Greenfield, T, Winder, T, Rawlinson, N, Maclennan, J, White, RS, Ágústsdóttir, T, Bacon, CA, Brandsdóttir, B, Eibl, EPS, Glastonbury-Southern, E, Gudnason, EÁ, Hersir, GP, Horálek, J
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Science and Business Media LLC 2022
• Subjects: Deep long-period earthquakes; Magma plumbing system; Iceland; Reykjanes; Low-frequency; Fagradalsfjall
• Online Access: https://dx.doi.org/10.17863/cam.91556; https://www.repository.cam.ac.uk/handle/1810/344131

AbstractWe 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 ~ 5 km shallower than where petrological modelling places the near-Moho magma storage region in which the ...