Scientists recently reported that molten rock, or magma, surged beneath an Icelandic fishing community at an unprecedented rate last year. This discovery coincides with the region’s most recent volcanic outburst, the third fissure to form on the Reykjanes peninsula since December. Icelandic authorities declared an emergency on Thursday after lava damaged a critical water infrastructure, exacerbating the crisis. Before 2021, the peninsula had not had an eruption in almost 800 years, implying a tremendous resurgence of volcanic activity.
Analyzing how magma flowed upward from a deep subterranean reservoir through a kilometre-long “vertical sheet” beneath the evacuated settlement of Grindavik in November, researchers warn that the action shows no signs of slowing. This prediction was sadly confirmed by the most recent rift on the Earth’s surface near the settlement, which occurred just hours before the paper was published in Science. Freysteinn Sigmundsson, the main author and researcher at the University of Iceland’s Nordic Volcanological Centre, acknowledged the difficulties of forecasting the duration of this newly discovered volcanic age. He warned that uncertainty could last for several months in the impacted region.
A large surge of magma beneath the Icelandic settlement of Grindavik occurred over six hours in November
Consider a massive underground fracture that is 15 kilometres long and 4 kilometres high, yet it is extremely thin, like a sheet of paper standing on end. According to a new study, a large surge of magma beneath the Icelandic settlement of Grindavik occurred over six hours in November. This “dyke,” as scientists refer to it, emerged when 6.5 million cubic meters of magma accumulated beneath Grindavik. And, guess what? It wasn’t Iceland’s only volcanic surprise; just a few days later, the region erupted! This study focuses on the extraordinary activity beneath the Reykjanes peninsula, which has not had an eruption in 800 years before 2021. So, while the dyke itself may be limited, the volcanic potential appears to be much wider!
According to Sigmundsson, the magma poured at a rate of 7,400 cubic meters per second, “a scale we have not measured before” in Iceland or elsewhere. For comparison, the average flow of the Seine River in Paris is only 560 cubic metres per second. The magma movement was similar to that of major rivers like the Danube and Yukon. According to Sigmundsson, the magma flow in November was 100 times larger than that seen before the latest eruptions on the peninsula from 2021 to 2023. “The activity is speeding up,” he remarked. The November magma flow caused more significant eruptions in December, last month, and again on Thursday.
The settlement, the nearby Svartsengi power plant and the well-known Blue Lagoon geothermal spa, have been evacuated several times due to eruption fears
Increasing subsurface pressure has also caused hundreds of earthquakes and pushed the ground up a few millimetres every day, resulting in massive fissures in the ground and damage to infrastructure in and around Grindavik. Sigmundsson believes the concealed crevasses that have plagued the town are more dangerous than the lava, citing one discovered in the middle of a sports pitch earlier this week. The settlement, as well as the nearby Svartsengi power plant and the well-known Blue Lagoon geothermal spa, have been evacuated several times due to eruption fears. The long-term viability of areas of the region situated on such hazardous terrain has become a source of contention.
Sigmundsson emphasized that such decisions were left to the authorities, but that this was undoubtedly “a period of uncertainty for the town of Grindavik”. “We need to be prepared for a lot more magma to come to the surface,” he went on to say. The researchers used seismic measurements and satellite data to simulate what was driving the magma flow.
Iceland is located on the Mid-Atlantic Ridge, a rift in the ocean floor that separates the Eurasian and North American tectonic plates. As these plates moved apart over the last eight centuries, “tectonic stress” built up, allowing magma to pour through the subsurface geological fracture, according to Sigmundsson. The researchers hope that their findings might help them understand what causes eruptions in different areas of the world.