IMO reported that magma continued to accumulate beneath Svartsengi after the 8-9 February eruption and by 1230 on 29 February had reached an estimated 8.5-9 million cubic meters. The accumulated volume of magma before previous recent eruptions near the Sundhnúkar crater row was 8-13 million cubic meters. The rate of inflation had been relatively constant; the inflation had decreased just before the start of previous eruptions.

An intense seismic swarm began at 1555 on 2 March near the southern end of the fissure that formed on 18 December 2023. The seismic data suggested that magma was migrating S and not propagating to the surface. IMO raised the Aviation Color Code to Orange (the second highest level on a four-color scale) at 1651. According to a news article the Blue Lagoon tourist area and Grindavík were evacuated, though not many people were in Grindavík at the time. Deformation changes were noted by 1730, followed by a decline in seismicity around 1800 and the end of the swarm by 2000; the intrusion had stopped beneath Hagafell cone. The Aviation Color Code was lowered to Yellow at 0812 on 3 March. The volume of lava that propagated out of Svartsengi was small compared to previous episode that culminated in eruptions. The Blue Lagoon reopened to visitors on 4 March.

Geological Summary. The Reykjanes volcanic system at the SW tip of the Reykjanes Peninsula, where the Mid-Atlantic Ridge rises above sea level, comprises a broad area of postglacial basaltic crater rows and small shield volcanoes. The submarine Reykjaneshryggur volcanic system is contiguous with and is considered part of the Reykjanes volcanic system, which is the westernmost of a series of four closely-spaced en-echelon fissure systems that extend diagonally across the Reykjanes Peninsula. Most of the subaerial part of the system (also known as the Reykjanes/Svartsengi volcanic system) is covered by Holocene lavas. Subaerial eruptions have occurred in historical time during the 13th century at several locations on the NE-SW-trending fissure system, and numerous submarine eruptions dating back to the 12th century have been observed during historical time, some of which have formed ephemeral islands. Basaltic rocks of probable Holocene age have been recovered during dredging operations, and tephra deposits from earlier Holocene eruptions are preserved on the nearby Reykjanes Peninsula.

Sources: Icelandic Meteorological Office (IMO), Icelandic National Broadcasting Service (RUV)