volcano erupting against a dark blue sky

Iceland eruption may be the start of decades of volcanic activity

A second outburst of lava in under a year strongly suggests that the country’s Reykjanes Peninsula will become one of the most volcanically dynamic parts of the planet for several generations.

After centuries of quiescence, Iceland's Reykjanes Peninsula has erupted twice in less than a year, sending up fountains of incandescent rock. The latest eruption, which started at 1:18 p.m. local time on August 3, opened up at a fissure only a few hundred feet away from the cone crafted by last year’s volcanic outburst.

Less than a year has passed since lava stopped sputtering from Iceland’s Reykjanes Peninsula following the first major volcanic outburst from this region in almost 800 years. But now the island is once again bleeding molten rock. The start of a new eruption so soon after unrest in 2021 seems to underscore that this once quiescent peninsula has awoken from its long slumber.

“This could herald the start of decades of occasional eruptions,” says Dave McGarvie, a volcanologist at Lancaster University.

The new eruption, which started at 1:18 p.m. local time on August 3, sent scarlet ribbons streaming from the base of a small mountain into the uninhabited Meradalir Valley. Located far from populations, the volcanic burbles likely pose little danger to the public, at least in the near term. And this relative safety allows scientists and tourists alike to marvel at the geologic majesty and get excited for a possible onslaught of new scientific knowledge.

After all, each volcanic eruption here provides a “window into the abyss,” McGarvie says. The 2021 event yielded revelations about the personality of the peninsula’s exuberant eruptions—from their physical behaviors to their quirky chemistries. This new eruption promises even more insights as the nascent volcano forges the world’s youngest land.

It’s still unclear how prolific or lengthy the eruption will be; this information will only come to light with more time and continued monitoring. But this week’s show of fireworks strongly hints the peninsula will become one of the most volcanically active parts of the planet for several generations.

“I am genuinely excited,” McGarvie says.

A volcanic double-bill

The Reykjanes Peninsula lies about 17 miles southwest of Iceland’s capital city Reykjavik. It sits atop the continually spreading Mid-Atlantic Ridge, where the North American plate to the west and the Eurasian plate to the east are gradually pulling apart. Superhot, gassy magma, which is less dense than the surrounding rock, can sometimes rise into the shallow crust from buoyancy alone, but all that regional stretching also creates cracks where molten rock can infiltrate.

The peninsula’s subterranean bedlam seems to manifest as periodic busts of volcanism. Historical accounts and studies of ancient volcanic rocks show that times of volcanic repose transition into loud seismic and eruptive awakenings in a cycle that’s transpired several times in the past few millennia.

While the flashes of scarlet were just spotted yesterday, scientists are already busy collecting their first samples of the rock, including volcanologist Helga Kristin, shown here (top). Seen below, crowds have also gathered to take in the stunning scenes, watching Earth forge new landscapes.

Although the region had been volcanically dormant for centuries, the tectonic sundering happening in the depths meant that last year’s eruption had long been in the works. And in recent years, several sheets of magma ascended toward the surface, indicated by the changing shape of the ground and swarms of earthquakes, says Tobias Dürig, a volcanologist at the University of Iceland. But for some time, these magmatic serpents failed to see sunlight—their escape was stymied either from the loss of their own upward momentum or because the resilient crust didn’t offer an escape hatch.

Nevertheless, as earthquakes began to crescendo in both frequency and strength from late 2019 onwards, scientists suspected that an eruption sometime in the future seemed inevitable. That was confirmed in dramatic fashion on March 19, 2021, when lava began gushing from a 1,650-foot-long fissure in a valley of the Geldingadalur region. Hundreds of thousands of visitors flocked to the region to watch that eruption, which built a vertiginous cone of magmatic splatter as it erupted over six months, causing no damage to infrastructure and no casualties.

 Then, since late July of this year, another cacophony of quakes and significant ground deformation plagued the region, pointing to the upward incursion of yet another magmatic sheet, according to the Icelandic Meteorological Service.

On July 31 a bone-rattling magntiude-5.5 earthquake struck the peninsula. This and other powerful temblors prior to the latest volcanic flare-up may have been so-called trigger earthquakes, says McGarvie. Stress builds as the intrusion of magma stretches the crust, until it fractures with a mighty jolt.

By August 2 magma was sitting just half a mile below the surface. Yet that same day the seismic activity and the ground deformation seemed to decline. Although this could suggest that the magma had more-or-less stopped in its tracks, this sequence of events also resembled the same pattern observed just before the 2021 eruption, which was the country’s longest in 50 years. Iceland’s uppermost crust can often stretch like a rubber band, accommodating magma without loudly cracking apart. So the most recent quietening may have been a precursor to an eruption—the calm before the magmatic storm.

On the other hand, there have been similar rises and falls in seismicity on the peninsula that did not end in eruptions, says Tom Winder, a volcano seismologist at the University of Cambridge. Further investigation is necessary to determine whether this pattern of sudden seismic silence is a reliable warning sign.

Still, by August 2 the available data led the Icelandic Meteorological Office to declare that the possibility of an eruption was “considered to be substantial.”

Just one day later, lava fountains screamed skyward from a fissure only a few hundred feet away from the cone crafted by last year’s eruption.

The land of future fires

Like its predecessor, the new eruption will likely pose little hazard to humans. The flows are currently confined to a series of empty valleys, with no major infrastructure nearby. Also absent are bodies of water or ice, which can sometimes trigger a series of violent, ash-heavy explosions. This is all good news for the region’s residents, particularly in the nearby fishing town of Grindavík that’s been riddled with quakes. Now that the eruption has started, the disruptive seismic shaking has all but vanished.

“It's still early days, but it looks like the eruption will be similar to 2021,” says Evgenia Ilyinskaya, a volcanologist at the University of Leeds.

 But similar doesn’t mean identical. Per local media reports, the lava is currently flowing with more vigor than it did during last year’s event. That could either mean the valley quickly fills up, or that the eruption could more rapidly run out of fuel, leading to a much faster end.

It’s extremely difficult to forecast how long the eruption will continue or how much lava it can produce. Ground deformation reveals the volume of magma available to feed the eruption in the short term, but it says nothing about additional surges that may arrive from below in the days to come. Will the lava remain confined to these valleys, or will it travel further afield? Will it reach the sea and produce pernicious plumes of noxious gas?

“It is a bit like watching the first hours of a Tour de France stage and trying to predict from that the future winner of the yellow jersey,” Dürig says. In this instance, though, he expects the eruption to follow a similar pattern to that of 2021’s magmatic showcase.

If this is indeed the start of a new era of Reykjanes volcanism, it’s difficult to predict what this may mean for those who live on the peninsula, and it’s currently impossible to say where—or when—the next eruption may emerge. Not every new eruption will necessarily lie far from population centers or vital infrastructure. Some might differ in style to the recent pair. Multiple eruptions might even happen at once. Scientists can extract only so much information from ancient volcanic rocks, the oldest of which are often buried under younger flows.

“Surprises are to be expected,” McGarvie says.

Regardless, these ferocious fires ultimately benefit everyone: They are gifting scientists with an unparalleled look at the connective tissue between the igneous abyss below and the lava-licked landscape above. Their efforts help improve our understanding of Earth’s viscera, of Iceland’s volcanic cadence, and of this peninsula’s volcanic dangers.

“Here, we have a fantastic natural experiment,” says Ilyinskaya. “It will for sure lead to many scientific discoveries.”

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