“It is also possible that an eruption could occur with little or no additional warning,” the Alaska Volcano Observatory stated. “This would be extremely hazardous for recreators on Mount Spurr or near its drainages as well as those overflying the volcano.”

The Alaska Volcano Observatory said signs indicated a Mount Spurr eruption was likely, though not certain, in the weeks or months ahead.

Mount Spurr is one of 53 volcanoes in Alaska that have been active within the last 250 years. It is roughly 80 miles northwest of Anchorage.