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The Icelandic Met Office has changed the aviation color code for Grímsvötn volcano from green to yellow. Volcanic activity at Grímsvötn has been gradually increasing over time as indicated by several regularly monitored geophysical and geochemical parameters that are now above the known background level.

Since the intense seismic swarm started in Fagradalsfjall on the 18th of July, the activity has been slowly decreasing over time. The acquisition of recent satellite images enabled mapping of new surface deformation in the area associated with the sequence of large earthquakes which occurred between the 18th and 20th of July. The satellite data processing clearly shows a deformation signal corresponding to approximately 3 centimeters of movement along a NE-SW oriented fault in the region of Fagradalsfjall.

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.

The meeting reviewed activity in Grímsvötn in the past months and discussed measurements made in and around Grímsvötn in early June. While seismic activity has been increasing over the past year, in June it was still lower than in the months leading up to the most recent eruptions in 2004 and 2011. Measurements of land deformation show that land continues to rise since the previous eruption with no significant changes in the last year. The biggest measurable change was that sulfur dioxide (SO₂) was detected close to the last eruption site. SO₂ emissions give a strong indication of magma degassing.