A quick glance at the Icelandic Met Office front page showed a new article under the image of a line of fire fountains, and I figured the next eruption was on.
Not so much, it turned out as the translating wizard did its thing. That image was from last August, and IMO was saying that, yes, eruption #8 is likely, but they additionally had looked into the possibility of eruptions after that —
It is difficult to get a clear picture of the development of activity in the coming years on the Reykjanes Peninsula.
We need to expect that the forces of nature can surprise us.
21.3.2025
Based on available monitoring data and their interpretation (as of 21.03.2025), everything indicates that the volume of magma that has now accumulated under Svartsengi will eventually build up enough pressure to trigger a new magma flow and even an eruption at the Sundhnúk crater series. Here is a link to a summary of what to expect in the next eruption. [Autotranslated]
If it erupts for the eighth time at the Sundhnúk crater series, what will be the development of the scenario after that?
Possible developments in the coming months
If it is assumed that magma accumulation will continue after the next eruption, then the timing of the possible ninth eruption at the Sundhnúk crater series will depend on these two factors:
How much volume of magma flowed from the magma accumulation area under Svartsengi in the previous eruption
How fast magma flows from depth into the magma accumulation area following a volcanic eruption
Magma accumulation in the run-up to the last two eruptions was slower than that measured in the run-up to the eruptions in late 2023 and early 2024. A rough estimate of the rate of magma accumulation before the last eruption is about one-quarter of what it was at the beginning of the eruption cycle.
The graph shows the length of magma accumulation periods (blue bars) in the run-up to eruptions at the Sundhnúk crater series since December 2023 and the volume of lava flows (orange bars) that formed in them. The magma accumulation periods between the eruptions in January and February 2023 were between 27-25 days, but between 85-90 days for the eruptions in August and November 2024. A large part of the magma that erupted from Svartsengi in January 2024 went into forming a magma tunnel, so the lava flow that formed in the eruption was the smallest.
If the trend of gradually slowing magma accumulation continues, it will take increasingly longer to accumulate the volume in the magma accumulation chamber beneath Svartsengi that is thought to be needed to trigger a new magma flow and even an eruption at the Sundhnúk crater series.
When the rate of magma accumulation becomes this slow, it has two consequences:
Many months, even years, can pass before enough magma has accumulated to trigger a new eruption.
The slower the magma accumulation, the more difficult it is to estimate the timing of the next eruption with an accuracy greater than a few months – or whether it will erupt again at all.
It is important to realize, however, that nothing in the available data or model calculations gives reason to exclude the possibility that the rate of magma accumulation under Svartsengi will increase again in the future.
Examples from other volcanic systems and history
This process was evident in the Krafla eruptions (1975-1984), when a significant reduction in inflow rates between 1982-1984 led to a longer period/eruption hiatus between eruptions.
Despite this longer waiting period, an eruption still occurred in September 1984.
Following the last eruption in Krafla, in 1984, expansion in the area stopped between 1985-1988, but it then picked up again and lasted until 1990. This last expansion period did not end with an eruption.
During known volcanic periods on the Reykjanes Peninsula that have lasted for hundreds of years, activity has shifted between different volcanic systems. It is therefore likely that when the current volcanic activity at Svartsengi ends, it will shift to a nearby volcanic system, although with the possibility of it moving back and resuming its current location. It cannot be ruled out that volcanic activity will resume within the Svartsengi volcanic system after a few years of dormancy.
The image shows the interaction between magma tunnel formation and land elevation in the middle of the Krafla caldera. The lower image shows the land elevation of a measurement point within the Krafla caldera, while the upper one shows where the metamorphic zones were in each series. In the upper image, the red color represents an eruption. (Páll Einarsson and Bryndís Brandsdóttir, 2021)
We need to expect that the forces of nature can surprise us.
The above example shows how unpredictable the behavior of volcanic systems can be and highlights why it is not possible to predict the development of the Svartsengi volcanic system in the near future. Assuming that land uplift at Svartsengi continues, no matter at what rate, it must be considered likely that further magma formation or volcanic eruptions will occur in the future at the Sundhnúk crater series.
It is important to recall what has been previously stated in the discussion of scenarios that a new eruptive phase has begun on the Reykjanes Peninsula. Since 2021, activity has shifted between volcanic systems, and eruptions have occurred at two of the peninsula’s six volcanic systems, Svartsengi and Fagradalsfjall. The same thing happened during the last volcanic period, which ended about 800 years ago, when activity also shifted between nearby volcanic systems.
Therefore, it must be assumed that when magma accumulation ceases under Svartsengi, it may move to other systems on the peninsula. It must be assumed that several months will have to pass since the last measurable signs of land uplift before the magma accumulation that began under Svartsengi in October 2023 can be declared over.
Although a great deal of knowledge has been developed to warn of an impending eruption with a few hours’ notice, it is not possible to measure or interpret the available data to state how the activity on the Reykjanes Peninsula will develop in the coming years. Time will tell what the development will be, but in the meantime it is most important to continue intensive monitoring in order to be able to respond appropriately to the forces of nature, which can always surprise us.
Considering all of the above, residents and civil protection authorities need to be prepared and take measures for further volcanic activity within the Svartsengir volcanic system in the coming months and also elsewhere on the Reykjanes Peninsula in the coming years.
I don’t see any mention of this on the RUV, mbl.is, and Visir websites just now, but that’s not surprising when boffins set out a straightforward piece of science. It takes time to digest, and then editors might not be able to think of a way to present it to their readers.
This layperson thinks that the IMO article is a wonderfully clear and simple expression of volcanic uncertainty — one of the hardest parts of volcanology that we members of the general public really need to know.
Links
A 360° drone view of the Sundhnuks, Grindavik, and Svartsengi area on August 7, 2024, with labels.
Flight To Wonder 