Indeed, Earth’s biggest volcano lies submerged a mile below the ocean’s surface. Volcanoes can form on land or below the sea. So its volcano density would be about comparable to 90 continuously active volcanoes erupting across the United States.) Where do volcanoes form? (Fun fact: The surface of Io is small, only about 4.5 times the area of the United States. Indeed, Io has more than 400 volcanoes, some of which spew plumes of sulfur-rich material 500 kilometers (about 300 miles) into space. It’s the innermost of the four largest moons of Jupiter. And the most volcanically active orb in the solar system is not Earth, but Io. Mercury and Venus both show signs of past volcanism. Several large volcanoes rise above the surface of Mars. USGSīut volcanoes are not just an Earthly phenomenon. Many of the world’s volcanoes are located around the edge of the Pacific Ocean in an arc known as the “Ring Of Fire” (shown as deep orange band). Most of them exist in Alaska (particularly in the Aleutian Island chain), in Hawaii and in the Cascade Range of the Pacific Northwest. Of all volcanoes that have erupted in the past 10,000 years, roughly 10 percent reside in the United States. About 500 volcanoes have erupted since humans have been keeping records. Roughly 1,500 potentially active volcanoes exist across our planet, according to scientists at the U.S. (It’s still “lava” even after it’s cooled and solidified.)
Scientists call it lava once that liquid rock erupts from the ground - and may start flowing across Earth’s surface. Magma is the name for that molten rock when it’s below ground. A volcano is a spot in Earth’s crust where molten rock, volcanic ash and certain types of gases escape from an underground chamber.