NASA Image Reveals Lava 'River of Fire' on Snowy Mountain

In a true study in contrast, the course of a red-hot lava flow oozing down a snowy white mountainside has been mapped out in a newly-released NASA satellite image. Running down the slopes of Mount Etna on the Italian island of Sicily, the spectacular flow—which NASA has dubbed a "river of fire"—has become something of a tourist novelty, attracting crowds of hikers and skiers. The volcanic eruption on February 12 followed reports from Italy's National Institute of Geophysics and Volcanology five days earlier that Etna was showing "signs of unrest above its background level." Etna is one of the world's most active "stratovolcanoes;" these are cone-shaped volcanoes, built up by alternating layers of lava and erupted rock fragments, that are characterized by explosive eruptions. The eruption—which is ongoing, albeit now with decreasing explosive activity—has disrupted local flights, while authorities have warned sightseers to keep their distance from the lava flow.

"The OLI (Operational Land Imager) on the Landsat 8 satellite acquired this image of an ongoing eruption on February 13," NASA wrote on its Earth Observatory website. "The natural-color scene is overlaid with an infrared signal to distinguish the lava's heat signature on Etna's snowy slopes. On the day that the image was taken, the lava flow covered a two-mile-long course from the Bocca Nuova crater—one of five at Etna's summit—down the volcano's southwestern flank. Weak ash emissions were ongoing and the Landsat image also captures a volcanic plume drifting away from the summit in a northeasterly direction.

The eruption of ash from Etna has seen local authorities raise the aviation color code, with the airport in Catania, 20 miles south of the volcano, diverting flights in response to hazardous conditions. Administrators have also expressed concern that the crowds flocking to see the volcanic spectacle may endanger themselves as well as impede rescue efforts if needed. "Hundreds of people, almost all well-equipped and well-accompanied by alpine and volcanological guides, are observing the exceptional phenomenon," Salvo Cocina, director general of the Sicilian Region Civil Protection Department, wrote on Facebook on February 16. However, he warned, the "constant influx" of people, many parking on narrow streets, has led to traffic blockages that may impede rescue vehicles. Already, he noted, rescues have had to be undertaken for people who got lost on the slopes, and one individual who had a panic attack. Do you have a tip on a science story that Newsweek should be covering? Do you have a question about volcanoes? Let us know via science@newsweek.com.