According to the Alaska Volcano Observatory, the Aleutian Islands in Alaska are currently the site of a singular and unsettling natural occurrence. Three volcanoes are erupting, and a fourth seems to be on the verge.

Describing them as “restless,” the AVO has documented spewing ash and steam from the Great Sitkin, Pavlof, and Semisopochnoi volcanoes and declared them an “orange” level threat, which means they're erupting. The other, Cleveland, is set to “yellow” as it’s yet to erupt.

The AVO uses surveillance cameras as well as eyewitness accounts to monitor volcanic activity. The snow-covered stratovolcano Pavlof is presently the most active, with some minor explosions and ash that’s traveling roughly six miles before dissipating. It sits 35 miles from the town of Cold Bay, but no threat to the area has been detected.

A lava foundation is active at the Great Sitkin, which is near two small villages. The volcano on Semisopochnoi appears to be blowing ash up to 10,000 feet in the air.

Meanwhile, seismic activity has been detected in the Cleveland volcano, which erupted just last year. There have also been small earthquakes recorded at the Atka Volcanic Complex Volcano.

Geologists at the AVO aren’t overly concerned at the moment. While multiple active volcanoes warrant continued monitoring, the eruptions are not thought to be life-endangering. The AVO does caution that Pavlof has been known to increase the severity of its eruptions with little to no warning.

Alaska has the somewhat dubious honor of being host to the 20th century's most significant volcanic eruption, when Novarupta went up in 1912. Lasting three days with ash spreading for hundreds of miles, it created the Katmai Caldera and the appropriately named Valley of Ten Thousand Smokes.

[h/t Smithsonian]