Iceland Volcano: About 14 Million Cubic Meters Of Magma Have Accumulated Beneath Svartsengi

Hazard assessment unchanged

Iceland Met Office

Updated 28 October 2025

Key points

• Uplift and magma accumulation beneath Svartsengi continue.
• The volume of magma that has left Svartsengi during each magma intrusion event has ranged between 12 and 31 million cubic meters.
• There is still considerable uncertainty regarding the timing of the next event.
• The hazard assessment remains unchanged and is valid until November 11.
• Ground subsidence continues near Krýsuvík, though it has slowed in recent weeks.

Deformation

About 14 million cubic meters of magma have accumulated beneath Svartsengi since the last eruption. Based on previous events in the Sundhnúkur crater row, the likelihood of a new magma intrusion and eruption increases once a similar volume of magma has recharged beneath Svartsengi as was released during the last event. Looking at eruptions in the Sundhnúkur crater row since March 2024, the amount of magma that was released from Svartsengi each time has varied considerably — from 12 million to 31 million cubic meters. Therefore, there is still considerable uncertainty about the exact timing of the next event.

Earthquake activity

Seismic activity near Grindavík and the Sundhnúkur crater row remains rather low, with only occasional small earthquakes of around or just above magnitude 1.0 being recorded. Most of these are located between Hagafell and Grindavík. A short swarm of small earthquakes occurred along the Sundhnúkur crater row on October 11th, when just over 20 earthquakes were detected, however since then, the number has mostly been five earthquakes per day.

Activity near Krýsuvík

Earthquake activity near Krýsuvík continues, with numerous small earthquakes recorded daily. On October 22, two earthquakes larger than magnitude 3 occurred west of Kleifarvatn, measuring M3.1 and M3.6. On that day, over 120 earthquakes were recorded in the area. Subsidence, observed since the summer, also continues in the region — amounting to about 55 mm at the Móhálsadalur GPS station west of Kleifarvatn since early June. However, the rate of subsidence has decreased in recent weeks.

Hazard assessment

The Icelandic Meteorological Office's hazard assessment has been updated and will remain unchanged until November 11, unless activity changes.