Iceland’s meteorological office reported Friday the Nordic Island nation’s southwestern Reykjanes Peninsula has been experiencing a “seismic swarm” of small earthquakes over the last three days, with at least 5,800 recorded since it began and around 1,000 since midnight Thursday.
In a series of reports on its website, the meteorological office — known as the “Met” office — said the vast majority of the quakes have been under magnitude 3, although two in the last three days were over 4.
The largest tremor, on Wednesday, measured 4.5 north of the town of Grindavík.
While small earthquakes are a daily occurrence in the nation, situated between the Eurasian and North American tectonic plates, the so-called seismic swarm is unusual.
The earthquakes prompted the national police commissioner to declare a Civil Protection “Level of Uncertainty,” encouraging residents to secure loose objects in their homes and noting that the earthquakes could trigger rocks or loose earth to slide in areas with steep slopes.
The Met office attributed the seismic swarm to stress changes in the earth’s crust induced by the flow of magma — molten rock — toward the surface beneath the Fagradalsfjall volcanic system.
In an interview with Reuters, Met Office Research division chief Matthew Roberts said the earthquakes are a warning sign for a volcanic eruption sometime in the next 12 months, although he added that predicting the timing of earthquakes is difficult.
Iceland’s last volcanic eruption, in July, occurred in an uninhabited part of the Reykjanes Peninsula after similar intense earthquake activity.
Some information for this report was provided by Reuters.