Several volcanoes along the Pacific Ring of Fire are heating up, prompting scientists to keep a close watch. This 25,000-mile (40,000-kilometer) horseshoe of seismic activity stretches from South America to New Zealand, tracing the edges of multiple tectonic plates that encircle the Pacific. Recently, four US volcanoes have rumbled to life, including Alaska’s Great Sitkin, which has been oozing lava into its summit crater for nearly four years, slow and steady, but active nonetheless.
With the scientific community on alert, the question remains: should we be worried? Click through the gallery to explore what’s stirring beneath the surface.