“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.”

In the shadow of Alaska's bustling city, Mount Spurr whispers of its ancient power. Elevated gas emissions suggest a restless giant beneath the surface.

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