Less certainty on the timing of the next dike intrusion and possible eruption
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Updated 15 March at 14:30 UTC
Likely sequence of events in the next few days:
Main changes in activity:
Note:
Higher uncertainty than before about the timing of the next dike intrusion and possible eruption.
GNSS displacements and recent interferograms show continued inflation of the Svartsengi magma reservoir – at a similar rate to that observed before the diking event on 2 March 2024. Geodetic modeling using these datasets confirms the inflation source is also at a similar location and depth as that observed during previous inflation episodes.
The models indicate a recharge volume of approximately 4 million cubic meters to the Svartsengi reservoir since 3 March.
For the diking events from 14 January to 2 March, the failure limit calculated to trigger these dike intrusions and/or eruptions was consistently estimated at around 10 million cubic meters. This enabled longer-term forecasts based on the volume loss from the magma reservoir during the diking events and then estimating the time window when this amount would be fully recharged, triggering the next event.
However, on 2 March it is estimated that a much smaller volume was lost from the magma reservoir during this event (approx. 1.3 million m3) which triggered a small dike intrusion that did not result in an eruption.
A larger volume, compared with the amount lost from the Svartsengi reservoir on 2 March, has now been recharged, yet a new dike intrusion/eruption has not yet occurred. This indicates a possible change in the magma plumbing system and greater uncertainty in the new failure limit that now needs to be reached, and thus the timing, of the next dike intrusion and/or eruption.
When this new limit is reached, the most likely scenario is another dike intrusion within the existing diking area – between Stóra-Skogfell to Grindavík – which may or may not culminate in an eruption.
Seismicity NW of Grindavík not a sign of dike intrusion there
We cannot rule out the possibility of an eruption occurring within an adjacent area or volcanic system -- for example, west of Mt Þorbjörn or in Eldvörp -- however, before this occurs a new dike will first need to be intruded in the corresponding area.
There is no evidence of a dike intrusion within these areas. Such an intrusion in a new area is expected to be characterized by a strong earthquake sequence and large amounts of ground deformation detected on both the GNSS network and interferograms. None of these monitoring datasets show any evidence of this.
There has been an increase in seismicity (all earthquakes < M1.5) to the northwest of Grindavík. It is likely that the continued inflation of the Svartsengi magma reservoir is now triggering small movements on pre-existing faults in this area that were activated during the 10 November 2023 diking event.