A new volcanic dike under the surface of Iceland's Reykjanes Peninsula threatens to open up, officials have warned less than a month after a highly anticipated eruption, as signs point to another lava fissure breaking through.
The Icelandic Meteorological Office said on Tuesday that the land around a geothermal power plant at Svartsengi—which had been rising due to magma accumulation in a horizontal intrusion in the Earth's crust—had slowed in its inflation, indicating that "magma pressure is rising" and "increasing the chances of new dike intrusion and also [a] volcanic eruption."
When the last eruption occurred on December 18, the crustal uplift reduced by nearly 3 inches as pressure was released, having risen by nearly 14 inches since a nearby vertical magma intrusion formed on November 10.
The horizontal intrusion soon began rising again, with officials warning that while the most likely site of another eruption being that of the fissure that opened up near the fishing town of Grindavik, magma could propagate elsewhere and form a new potential eruption site.
Iceland sits on a rift between the North American and Eurasian plate, with a sudden shift in the former thought to have allowed magma to surge up from the Earth's mantle and intrude into the crust.
The Icelandic Met Office said the latest deceleration was "a similar change in ground displacement that was observed at the end of the day on December 15, which culminated in an eruption three days later," but expressed uncertainty as to whether the pattern would repeat itself.
It noted that the early warning sign of an impending eruption was a sudden increase in seismic activity.
Seismic swarms had been occurring on the peninsula since November 10 as magma built under the Earth's crust, before waning in early December. But hours before five volcanic vents opened up—shooting lava up to 650 feet into the air—a fresh swarm of earthquakes was recorded around the vertical dike as magma pushed toward the surface.
The Icelandic Met Office said that seismic activity in the region had been relatively consistent of late, with around 200 earthquakes a day recorded; many measured below a magnitude of 1, but around 30 had exceeded that since December 29.
Ben Edwards, an American volcanologist who has visited the Reykjanes Peninsula multiple times, previously told Newsweek that the December 18 eruption could mark the start of over a century of volcanic activity in the region.
His remarks came after a leading Icelandic volcanologist told Newsweek that after a dormant period, the activity leading up to the eruption could mark the start of an "intense" period of "rifting and volcanism" on the peninsula.
While Haraldur Sigurdsson, an emeritus professor of geophysics at the University of Rhode Island, expressed hopes following the eruption for a brief reprieve from volcanic activity, both he and Edwards noted much of Iceland's infrastructure—including the capital Reykjavík—is located in the region.
Icelandic officials evacuated the town of Grindavik early on, and have built earth walls and channels around it and the power plant at Svartsengi to divert any lava flows that might reach them. Currently, lava flows have spread across an uninhabited region of the peninsula.
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Aleks Phillips is a Newsweek U.S. News Reporter based in London. His focus is on U.S. politics and the environment. ... Read more
