Volcano eruption at Sundhnúkur. Photo taken 10. April 2024 by Jón Bjarni Friðriksson/IMO.
More uncertainty about the development of the activity in the coming days or weeks
Iceland Met Office
Updated 19. April at 15:30 UTC
Ground uplift in Svartsengi continues at a steady rate.
Since 5 April, only one crater has erupted and lava flow from it has remained relatively stable since then, just over 3 m3/s.
Continued hazard due to gas emissions. People are advised to monitor air quality.
The weather forecast for gas dispersion is here
Continued magma accumulation beneath Svartsengi at the current rate increases the likelihood of another magma propagation in the coming days or weeks, despite the ongoing eruption.
When the eruption started on the 16 March, ground uplift at Svartsengi slowed down considerably and almost stopped. This indicated an equilibrium between magma inflow into the magma reservoir below Svartsengi, and to the surface at the Sundhnúkur crater row (Figure 1).
At the beginning of April, ground uplift began to increase anew, and a similar volume of magma is now being erupted at Sundhnúkur as is accumulated in the reservoir beneath Svartsengi, causing increased magma pressure (Figure 2).
The current development is new, which is an ongoing volcanic eruption with a relatively stable lava flow at Sundhnúkur crater row at the same time as ground is uplifting in Svartsengi. Therefore, there is more uncertainty now than before about the possible development of the event.
(Image 1)
(Image 2)
Model calculations indicate that over 6 million m3 of magma has now been added to the magma reservoir beneath Svartsengi since 16 March. In previous events, magma has propagated from Svartsengi when between 8 and 13 million m3 has been added to the reservoir since the last event.
The graph shows the estimated amount of magma that has been added beneath Svartsengi between the volcanic eruptions and magma propagations that have occurred since November 2023.
More uncertainty concerning the development of the activity in the next days or weeks
Until recently, the general trend in the Sundhnúkur area has been an increased likelihood of magma propagation and even a subsequent eruption. Now, however, a new situation seems to be at hand where a magma propagation could occur during an ongoing eruption. Let's recall that magma propagation is a sudden and large flow of magma propagating out of a magma reservoir and can culminate with magma reaching the surface. After the magma propagation on 2 March, which did not end in an eruption, marked a change in the activity that had since December been somewhat cyclical.
If magma accumulation continues at a similar rate, the likelihood of another magma propagation increases in the coming days or weeks, even though an eruption is still ongoing. Magma propagation from the reservoir during an ongoing eruption has thus far not been seen before in the area. Therefore, more uncertainty is on the development of the activity in the next days or weeks.
Probable scenario if magma propagation coincides with the current eruption:
- Magma propagates from the magma reservoir beneath Svartsengi to the Sundhnúkur crater row, as has happened in the last six times.
- Following the magma propagation, new eruptive fissures could open in the area between Stóra-Skógfell and Hagafell and/or the current eruptive crater could be enlarged due to a sudden increase of lava flow. This could occur at very short or no notice.
- If magma propagation results in new volcanic fissures opening up elsewhere above the magma dike which formed on 10 November, much longer notice is expected, most likely intense seismic activity, deformation and pressure changes in boreholes.
- It is also possible that magma propagation will not occur, but that the flow of the current eruption will stop decreasing and begin to increase steadily until a new equilibrium between the inflow of magma from below and flow to the surface from the crater is reached.
- However, if magma propagation results in a new eruptive fissure opening elsewhere than in the area between Stóra-Skógfell and Hagafell, such a scenario would very likely be accompanied by intense seismicity and deformation with considerably more notice than previous eruptions.
Updated hazard assessment
In view of the uncertainty caused by increasing pressure in the magma reservoir beneath Svartsengi, the Icelandic Meteorological Office has increased the hazard due to possible opening of eruptive fissures in Zones 1, 4 and 7 from “low” to “considerable.”
However, the overall hazard (color) in the affected Zones does not change.
(click on the image to see it larger)
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