Since December 2021 an earthquake swarm has been ongoing south-west of Langjökull glacier. This area is not part of any known fault zone or any volcano. This is just tectonic earthquakes and is outside of main earthquake areas. This intra-plate earthquakes happens sometimes in Iceland. Why that is remains unknown, but best idea is this happens because of stress changes because of tectonic movement. Earthquake magnitude can go up to Mw5,5 or larger. But such events are extremely rare, but do happen.
This is the second earthquake with magnitude Mw3,3 in this area, with the earlier one happening on 18th January 2022. The hill this earthquake swarm is happening in is called Húsafell.