Iceland Volcano: New Event Expected At The End Of September

Hazard assessment unchanged, but will be reassessed in one week 

Iceland Met Office

Updated 16 September 2025

• Uplift and magma accumulation beneath Svartsengi continue.

• Approximately 8–9 million cubic meters of magma have accumulated beneath Svartsengi since the last eruption.

• The likelihood of a new event increases when around 11 million cubic meters have accumulated, expected towards the end of September. However, there remains considerable uncertainty.

• The hazard map remains unchanged but will be reassessed next week.

Uplift and magma accumulation

Measurements show that magma accumulation beneath Svartsengi continues at a similar rate as in recent weeks. Model calculations estimate that about 8–9 million cubic meters of magma have accumulated since the last eruption, which began on 16 July. The volume that drained from the accumulation area in that eruption was estimated at around 12 million cubic meters.

Likelihood of a new eruption

Based on previous events in the Sundhnúkur crater row, the likelihood of a new dike intrusion and eruption increases once a similar volume of magma has accumulated beneath Svartsengi as drained during the last event. If the accumulation rate remains unchanged, this volume will be reached in the latter part of September, as noted in the last hazard map update. However, experience shows that the thresholds for when an eruption begins vary between events. In some cases, eruptions have started at a lower volume, while in others a higher volume has been required. 

Hazard assessment

The hazard map remains unchanged at this time. Given that the same volume of magma as drained in the last eruption is expected to be reached by the end of September, the hazard map will be reassessed next week. It will therefore remain in effect from 16 September to 23 September.