(CNN) — Here's some background information about volcanoes, mountains that open downward to a reservoir of molten rock. Facts: More than 80% of the Earth's surface, both above and below sea level, is ...

Hawaii’s Kilauea volcano sent lava soaring 400 feet into the air last week, resuming an intermittent eruption that has been ongoing for the past year. This is the 37th time the volcano has erupted ...