Volcano near Grindavík likely to keep Iceland busy for a long time to come | Polarjournal
Magma has been erupting from the interior of the Fagradalsfjall volcano on the Reykjanes peninsula for the past two years. The nearby village of Grindavík has now been evacuated and will not be resettled for the foreseeable future. (Photo: Government of Iceland)

Because Iceland has always been a volcanically active area, the results of an international research team should not come as a surprise to the island’s population. The 10-person team found that the current volcanic eruptions on the Reykjanes peninsula are likely to continue for a long time, after more than 800 years of dormancy.

Researchers from Sweden, Iceland, the Czech Republic and the USA have concluded after three years of research that there is a magma accumulation zone below Fagradalsfjall, which is around 10 kilometers wide at a depth of 9-12 kilometers, and which is responsible for the eruptions east of Grindavík in the Geldingadalir area (2021) – Litli-Hrutur (2023) as well as for the new eruptions, the so-called Sundhnúkur eruptions north of the municipality since the end of 2023. Based on the results of the study, the team suspects that the source of the magma is located in the deeper layers of the Earth’s crust and not in the mantle, the more fluid part of the Earth’s interior.

The map on the left shows the formations that make up the Reykjanes Volcanic Belt (RVB, small image above). The map on the right shows the outbreaks that have been recorded on the peninsula since 2021, including this year. The research team discovered that the eruptions originate from the same magma source. (Graphic: Troll et al. (2024) Terra Nova)

Since the eruptions in 2021, the team has been examining samples of the lava for their geochemical composition in order to find out how the volcanism under the peninsula is structured. Until now, little was known about this, as the region had not recorded any volcanic activity for over 800 years. Although it was known that the Reykjanes volcanic belt, a structure consisting of 8 formations, lies beneath the peninsula and is responsible for the eruptions over the last 4,000 years, little was known about the internal structure of the magma zones and their location. Thanks to the eruptions that have taken place in the region since 2021, scientists were given a unique opportunity to literally gain a deep insight into the interior of the belt.

Although volcanic eruptions in themselves pose a great potential danger (a fact that many tourists are happy to forget for the sake of a Facebook selfie), such fissure eruptions, i.e. magma erupting through cracks, are somewhat less volatile and thus easier to sample and study. This enabled the team to obtain samples for a “fingerprint” analysis. This involved comparing the composition of the oxygen isotopes (substances with the same chemical properties but different masses) with geochemical material and the maps of seismic activity from the various eruptions. In the end, they found that the magma was located in the earth’s crust and not, as previously assumed, in the mantle, and that it was accumulating beneath Fagradalsfjall, a ridge on the peninsula. The research group concluded from the results that all the magma, with the exception of the early 2021 eruption at Geldingadalir, originated from the same source.

The continuous eruptions have damaged the infrastructure around Grindavík. The nearby “Blue Lagoon”, the geothermal power plant near Svartsengi and even Keflavik Airport could also be at risk if the eruptions continue for a longer period of time. (Image: after Lauren Dauphin / NASA 2 Earth Observatory)

When asked how long the eruptions will continue, the team writes in their paper, “Based on past eruptive behavior, this pattern is likely to continue for centuries to come.” Yet Dr. Ilya Bindemann, a volcanologist at the University of Oregon and co-author of the study, explains: “Nature is never regular. We don’t know how long and how frequently it will continue for the next ten or even hundred years. A pattern will emerge, but nature always has exceptions and irregularities.”

One thing is certain: the eruptions will also have an impact on the infrastructure on the peninsula. Since the start of the eruptions at Sundhnúkur, the town of Grindavík has had to be completely evacuated and the tourist attraction “Blue Lagoon” has had to be closed several times. Roads and power lines have been damaged. According to the team of authors, the large geothermal power plants at Svartsengi, Reykjanes, Hellisheiði and Nesjavellir, and even Keflavík International Airport, are also at risk. Even if the eruptions do not last as long as the scientists suspect, they will continue to impact Icelandic society, the economy and politics for a long time to come.

Dr. Michael Wenger, Polar Journal AG

Link to study: Trollet al (2024) Terra Nova June 26, The Fagradalsfjall and Sundhnúkur Fires of 2021-2024: A single magma reservoir under the Reykjanes Peninsula, Iceland?; DOI: doi.org/10.1111/ter.12733

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