Bright, burning lava surging from a fissure on Iceland's Reykjanes Peninsula is so voluminous that it's easily visible to orbiting satellites.
The image above, which is about three and a half miles across, was created using data acquired by the Landsat 9 satellite on November 24th. If you look carefully at the left-most extension of the flowing lava you can make out a couple of turquoise-colored spots. This is Iceland's iconic Blue Lagoon, a geothermal spa that attracts tourists from around the world.
Lava from the ongoing eruption nearby has coursed across a parking lot at the spa and scorched a service building.
The eruption is the latest in a series of seven that began in December of 2023. It was heralded on the evening of Nov. 20 by a swarm of earthquakes. About five hours later, the Suomi NPP satellite acquired the nighttime image of Iceland below. The light streaming up from the lava flows to the satellite sensor was so intense that it appears even brighter than the Icelandic capital of Reykjavík.
Here's a different version of the Landsat 9 satellite showing more of the surrounding landscape of the Reykjanes Peninsula:
The Landsat image combines a natural color scene with an infrared signal to help reveal the lava’s heat signature. A plume of gas consisting mostly of sulfur dioxide is also seen streaming from the lava.
Iceland lies along a giant seam in Earth's crust running roughly down the middle of the North and South Atlantic Oceans. The seam is marked by a ~10,000-foot-high undersea mountain range known as the Mid-Atlantic Ridge. And along it, tectonic plates are pulling apart, including in Iceland. Here, the North American plate is moving roughly west by southwest, while the Eurasian Plate is pulling toward the east.
Tectonic Forces and a Giant Plume of Magma
As these tectonic plates diverge, fissures in Earth's crust crack open, allowing magma to well up and spew lava onto the surface. This phenomenon is not unique to Iceland — it happens all along the 10,000-mile-long Mid-Atlantic Ridge. But Iceland is one of the only places where you can actually walk along the ridge and witness processes than ordinarily take place thousands of feet below the sea surface. Why is that?
Along most of the ridge, molten lava pours out onto the seafloor, cools, and is then pulled away from the seam in the crust. Because of that movement, there's not enough time for lava to accumulate sufficiently to punch up above sea level.
But Iceland is located not just at the Mid-Ocean Ridge. It's also right above a "hot spot" — a huge plume of magma rising from the depths. Between both sources, the eruptions of lava have been sufficient to build Iceland up above sea level.
Volcanic activity in Iceland is episodic. During a quiet phase, tectonic forces cause strain to accumulate in the crust. After a period lasting 600 to 1,200 years, the strain is enough to wrench the crust apart, allowing lava to pour out in eruption pulses that last between 200 and 500 years.
"We are now in one of these pulses," David Pyle, a volcanologist at the University of Oxford, told Live Science. "Each eruption releases just a bit more of the stored-up strain, and eventually, when all of that strain has been released, then the eruptions will stop."
Bottom line: What we're seeing now on the Reykjanes peninsula could continue, off and on, for many centuries.
