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

Researchers predict the most likely outcome of the unrest at Mt. Spurr is “one or more explosive events” that could last as long as a few hours and produce ash clouds carried for hundreds of miles.

Scientists warn that Alaska’s Mount Spurr is showing signs of increased activity and could erupt in the coming weeks or months. An eruption could lead to widespread ashfall in Anchorage and surrounding areas,