Volcanic mountains

See Iceland go up in flames in volcanic eruptions

Breaking more than seven months of calm, the Reykjanes peninsula in western Iceland once again exploded into volcanic flames. After a swarm of earthquakes in late July and early August rocked the region, lava erupted from the Fagradalsfjall volcano in the Meradalir Valley – not far from barely cooled lava from the same volcano’s 2021 eruption – offering tourists and researchers the vibrant red-orange glow of cool molten rock at just 20 miles from the Icelandic capital of Reykjavk.

Such striking volcanic displays are relatively common in Iceland. The whole country, which is one of the geologically youngest landmasses in the world, is the product of millions of years of eruptions and is perfectly placed for ongoing volcanic activity.

Iceland straddles the boundary between two of Earth’s tectonic plates: huge fragments of crust that fit together like puzzle pieces to form the rocky outer shell of our planet. The North American and Eurasian plates are moving apart by one to two inches per year, gradually decompressing the bottom of the Atlantic Ocean to form a mid-ocean ridge. This divergence leaves a gap that attracts material from the Earth’s mantle, a hot layer of rock sandwiched between the crust (the layer we live on) and our planet’s metallic core.

As it rises, this material partially melts, supplying Icelandic volcanoes with magma, but it is not the only source of molten rock in the region. Iceland, like Hawaii, is perched above a “hot spot”, a column of hot rock that rises through the mantle, driven by its own buoyancy, adding even more fuel to volcanic fires. of the island.

In Iceland, this combination of magma sources results in several different types of volcanoes. The towering Hekla cone to the south is closer to the mantle hotspot, while the chains of small craters and fissures currently forming in the Reykjanes volcanic systems are where the plate boundary comes ashore.

“The kind of volcanic eruptions that take place in this region [Reykjanes] come not from the typical cone-shaped mountain, but rather from openings in the crust,” says Sara Barsotti, volcanic hazard coordinator at the Icelandic Meteorological Office (IMO). These openings occur because the area is located along a bend in the mid-ocean ridge and the cracks form as a result of the two plates pulling apart at an odd angle. Some of these fissures fill with magma, which can eventually erupt, while others allow pieces of crust to slide past each other causing earthquakes. Magma moving through the crust can also cause seismic activity as new cracks form or widen to accommodate molten rock.

As the mid-ocean ridge expands, Reykjanes goes through quiet periods, typically lasting 800 to 1,000 years, followed by two or three centuries of dramatic eruptions, which scientists studying the Iceland suspect to start now. During the 1990s, long before Fagradalsfjall erupted in 2021, geophysicist Sigrun Hreinsdóttir, now at New Zealand geoscience research and consultancy company GNS Science, Te Pū Ao, installed GPS stations throughout the peninsula to watch for slow moving, bending and buckling, accompanied by small earthquakes. At the time, there were no active eruptions.

In hindsight, however, Hreinsdóttir says, these measurements may have captured the first signs of new volcanic action in the region. “There was a lot of activity in [the mountain] Hengill, on the edge of the Reykjanes peninsula – lots of earthquakes,” she explains. All of this action led scientists to suspect that a magma chamber was filling deep beneath the surface, and “we wondered if this was somehow the first sign that Reykjanes might be on the verge of coming to life.”

Now, it seems, the peninsula is really waking up. Since the late 2000s, magma injected below the surface has caused the area to periodically bulge and deflate, bulging to match the movements of molten rock underground. Barsotti and his colleagues at IMO are tracking the locations of these reservoirs using earthquakes, GPS and satellite imagery to try to anticipate which parts of Reykjanes are primed for future eruptions. The latest warning sign was a cluster of large earthquakes that shook western Iceland before the first fissures opened in 2021.

After dreaming of seeing an eruption every day from her fieldwork on the peninsula some 30 years ago, Hreinsdóttir could only watch her dream come true from afar, as COVID kept her at home in New Zealand in 2021. In August, however, she went on a pilgrimage to get her hands on last year’s cooled lava, and her six-year-old son was knocked down by a magnitude 4.5 earthquake. That August 2 quake turned out to be a warning for an eruption the next day that would turn out to be even bigger and more spectacular than the one it missed. “It was a pretty nice feeling for me,” she says. “It was like Fagradalsfjall just saying ‘Hello!'”

On August 3, Hreinsdóttir traveled to Meradalir with her colleagues from the University of Iceland, where she was previously affiliated, and some 1,800 other visitors to see the fluorescent orange glow of lava erupting between the rocks of her former study zone. As with the Fagradalsfjall eruption in 2021, volcanologists expect new lava to continue to emerge here for several months.

The eruption is already a hotspot for hikers and photographers. So far, it’s “pretty safe,” says Barsotti, who closely monitors volcanic activity for potential hazards. “But I think we also have to know that there is always uncertainty about what we can anticipate next.” The current eruption is just an hour’s drive from Reykjavík. IMO volcanologists are therefore using data and models to assess current and future risks to infrastructure, water quality and human health from lava and gases emanating from the new fissure.

Although the eruption itself presents certain dangers for tourists, including noxious fumes and incredibly hot molten rock, perhaps the biggest challenge facing those who want to see it is the two-hour hike to s get there. “It is important to check IMO website because the expected conditions because we are going towards the fall — it could be very cold; it could be very windy,” says Barsotti. Accordingly, children 12 and under and pets are prohibited from entering the eruption area.

Those who succeed, however, are treated to an enviable spectacle. “I’m jealous of myself, to be honest,” says Hreinsdóttir, although flares can happen as often as every few years now that Reykjanes has woken from his roughly 800-year-old slumber. “How lucky was I to be alive when this happened?”