Iceland Volcano: Magma Accumulation Continues

The volume is approaching the amount that flowed out during the last event

Iceland Met Office

Updated 23 September

• Around 10 million cubic meters of magma have accumulated under Svartsengi since the last eruption.
• The volume that flowed from Svartsengi during the last eruption was estimated at about 11–13 million cubic meters. The lower threshold of this volume is expected to be reached over the weekend.
• The hazard assessment remains unchanged but will be reassessed on Thursday.

Land uplift and magma accumulation continue under Svartsengi and have been at a steady rate in recent weeks. Since the last eruption, which began on 16 July, about 10 million cubic meters of magma have reaccumulated in the magma storage area beneath Svartsengi.

Based on previous events on the Sundhnúkur crater row, the likelihood of a new magma outflow and eruption increases once an amount of magma equal to the last event has accumulated beneath Svartsengi. The volume that flowed from the magma storage area during that eruption is estimated at about 11–13 million cubic meters. If the accumulation rate remains unchanged, the lower threshold of this volume is expected to be reached over the weekend.

Therefore, the hazard assessment will remain unchanged until this lower threshold is reached and will next be updated on Thursday, 25 September.

Experience shows, however, that the thresholds for when an event begins vary between eruptions. The uncertainty in the timing of the next event is therefore considerable, and the current period of magma accumulation could be prolonged.

Ongoing seismic activity and subsidence west of Kleifarvatn

Seismic activity around the Sundhnúkur crater row remains very low, with only occasional small earthquakes below magnitude 1.0.

Seismic activity near Kleifarvatn and to the west of it continues, with several tens of earthquakes measured there on most days. The majority of these earthquakes are small, below magnitude 2.0. Subsidence measured west of Kleifarvatn continues at a steady rate.