Magma buildup raises risk of intensified eruption or new fissures in Iceland’s Reykjanes Peninsula

The Icelandic Met Office reports ongoing magma accumulation and land rise in Svartsengi, indicating a heightened risk for intensified volcanic activity or the formation of new fissures in the Reykjanes Peninsula.

The Icelandic Met Office (IMO) released a new update on May 7, 2024, detailing the continued accumulation of magma and land rise in the Svartsengi region of Iceland’s Reykjanes Peninsula.

According to their latest observations, magma is building up at a steady pace, increasing pressure in the magma chamber beneath Svartsengi. The ongoing geological activity raises the likelihood of intensified eruptions or new fissure formations in the region.

The Sundhnúks crater series is still erupting, although lava is currently flowing only a short distance from the crater, and activity has diminished in recent days.

The southern portion of the lava bed, situated near defenses to the east of Grindavík, has seen little to no change over the last week. Despite this slowdown, magma continues to accumulate, and the pressure inside the magma chamber remains high, suggesting an ongoing buildup that could fuel further volcanic activity.

Micro-seismic activity in the surrounding areas has shown a gradual increase, particularly north of the current crater between Sundhnúk and Stóri Skógfell, and south of Þorbjörn in the large graben near Grindavík.

This activity, most of which involves small earthquakes less than magnitude 1, is indicative of rising tension in and around the magma passage due to increased pressure in the Svartsengi magma chamber. This trend is monitored closely, as it could foreshadow an uptick in volcanic activity.

The Icelandic Met Office outlined two likely scenarios for the immediate future:

New fissures may open between Stóra-Scógfell and Hagafell, or an existing fissure may expand, leading to a sudden surge in lava flow comparable to the initial phase of the last eruption. This increase could occur with minimal or no advance warning. Alternatively, magma flow from the Svartsengi chamber to the active Sundhnúks crater may gradually increase until an equilibrium is reached between inflow and outflow.

Both scenarios carry inherent risks of increased volcanic activity, and authorities have issued warnings to local communities accordingly.

The Met Office emphasized that sudden series of small earthquakes, rapid land deformation, and pressure changes in boreholes would be key indicators of significant magma movement. They also caution that the warning period before such events could be less than 30 minutes, or even nonexistent.

There is uncertainty about how the earthquakes will progress now that the eruption has lasted for over a month and magma continues to accumulate in the magma chamber beneath Svartsengi. Although the above scenarios are considered the most probable, close monitoring is being conducted to see if magma might shift towards areas other than the Sundhnúks crater series. Special attention is being paid to areas north of Stóra-Scógfell and south of Hagafell and Þorbjörn.

If magma were to break through to the surface in regions that have not yet erupted, the seismic warnings would be more pronounced, presenting as much stronger and more intense seismic activity than what was observed before the previous eruptions.

References:

¹ Kvikusöfnun og landris heldur áfram í Svartsengi – IMO – May 7, 2024

Featured image: Satellite image of a lava field in Reykjanes Peninsula on May 1, 2024. Credit: Copernicus EU/Sentinel-2, The Watchers. Acquired on May 1, 2024