Earthquake swarms are clusters of small quakes caused by complex fault systems and underground stress, and scientists say ...

The island of Hawaii is one of the most seismically active areas in the world, producing thousands of earthquakes every year. It also commonly produces a signal called tremor that can originate from ...

An active volcano near Alaska's most populated city could be on the brink of eruption, according to scientists who are constantly monitoring a potential threat. Signs of unrest at Mount Spurr -- ...