TY  - JOUR
A1  - Greenfield, Tim
A1  - Winder, Tom
A1  - Rawlinson, Nicholas
A1  - Maclennan, John
A1  - White, Robert S.
A1  - Ágústsdóttir, Thorbjörg
A1  - Bacon, Conor Andrew
A1  - Brandsdóttir, Bryndis
A1  - Eibl, Eva P. S.
A1  - Glastonbury-Southern, Esme
A1  - Gudnason, Egill Árni
A1  - Hersir, Gylfi Páll
A1  - Horálek, Josef
T1  - Deep long period seismicity preceding and during the 2021 Fagradalsfjall eruption, Iceland
JF  - Bulletin of volcanology : official journal of the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI)
N2  - 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.
KW  - deep long-period earthquakes
KW  - magma plumbing system
KW  - Iceland
KW  - Reykjanes
KW  - low-frequency
KW  - Fagradalsfjall
Y1  - 2022
U6  - https://doi.org/10.1007/s00445-022-01603-2
SN  - 0258-8900
SN  - 1432-0819
VL  - 84
IS  - 12
PB  - Springer
CY  - Berlin ; Heidelberg ; New York
ER  -