On 19th July at approximately 01:30 a.m. a seismic swarm commenced in Fagradalsfjall. Over 1700 earthquakes have occurred in this region since. The largest event occurred at 23:36 yesterday evening with a magnitude (M) of 5. Two other events greater than M4 occurred early this morning at 05:46 (M4.6) and 06:23 (M4.3), respectively. In addition, 22 earthquakes greater than M3 have occurred since midnight. Felt earthquakes have been reported by local residents as far Akranes in the west and Vík in the east. The seismic swarm is still ongoing with similar intensity.

A strong earthquake swarm started on 19th of June offshore North Iceland, NE of Siglufjörður. Three earthquakes above M5.0 have occurred since the swarm started. On 20th of June a M5.4 earthquake occurred at 15:05 and a M5.6 at 19:26. Both these earthquakes were located around 20 km NE of Siglufjörður. The largest earthquake of the swarm occurred on 21st of June at 19:07 and was M5.8.

During its active period, as it is since the eruption in 1996, Grímsvötn erupts on average each 5-10 years. The last eruption occurred in 2011 and it was a fairly large and powerful event. Between eruptions, the deformation data indicate the gradual accumulation of new magma at depth and the increased pressure in the system. In the last weeks scientists from the IMO measured SO₂ in the southwest corner of the caldera in Grímsvötn, close to where the last eruptions in 2004 and 2011 took place.