Today (11. May 2023) there was a earthquake swarm in Þórðarhyrna volcano. This are small earthquakes, but their location and depth suggest that this is a dyke intrusion taking place at this location.
Þórðarhyrna volcano is part of Grímsfjall volcano fissure swarm, that connects to Laki eruption fissures. Last eruption in Þórðarhyrna volcano was in the year 1902 to 1904 and had the VEI=4 according to Global Volcanism Program report that can be read here.