Add Yahoo as a preferred source to see more of our stories on Google. Smoke billows from the mouth of Mt. Shasta like a thunderous cough. Within moments, clear skies turn gray, and the sun vanishes ...

Scientists have just identified a group of small volcanoes that experts warn could be among the most dangerous on Earth.

Smoke billows from the mouth of Mt. Shasta like a thunderous cough. Within moments, clear skies turn gray, and the sun vanishes behind thick, shifting layers of volcanic gas and ash. Visitors snap ...