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The Debunker: Are Most Volcanoes Mountains?

by Ken Jennings

We usually think of volcanic eruptions as sudden and dramatic events, but that's not always the case. The Hawaiian volcano of Kilauea, for example, has been erupting continuously since January 3, 1983, covering 48 square miles of the state's "big island" with new lava. In honor of the thirty-fifth anniversary of Earth's longest-erupting volcano, Jeopardy!'s Ken Jennings will be here all month providing explosive corrections to a lot of popular misinformation about volcanoes. The results might just rock your world.

The Debunker: Are Most Volcanoes Mountains?

Picture a volcano. I bet it looks more or less like the ones kids build for the fifth-grade science fair, right? Big smoking mountain, crater on top? Possibly located on a tropical island and all ready for Tom Hanks to hurl himself into?

The Debunker

In fact, that image is misleading on a few different levels. First and most obviously, volcanoes don't "smoke." They might spew clouds of ash, but nothing is ever burning. Secondly, volcanoes don't have to be tropical. Many of the world's most currently active volcanic zones are in tropical areas like Mexico and Indonesia, true, but there are also a dozen eruptions happening right now in non-tropical areas from Siberia to Antarctica.

Most surprisingly, volcanoes don't have to be mountains. In fact, hardly any of them are. The world's most iconic and photogenic volcanoes are lofty stratovolcanoes, sure—Etna, Fuji, Kilimanjaro, St. Helens—but they're the exception, not the rule. By definition, the word "volcano" doesn't have anything to do with elevation; a volcano is just a place in the earth's crust where heat is venting. The vast majority of the Earth's volcanoes aren't visible at all, because they're miles beneath the sea, on the "mid-oceanic ridges" where the Earth's plates spread apart. And even on dry land, the most abundant volcanoes are cinder cones—little piles of loose debris around a volcanic vent. A big volcano like Mauna Kea might have hundreds of cinder cones surrounding it, and they're usually around 300 to 1000 feet tall—medium-sized hills, in other words. But nobody ever won a science fair by making a medium-sized hill out of modeling clay.

Quick Quiz: The tallest volcano in the solar system, on Mars, is named after what iconic peak on Earth?

Ken Jennings is the author of eleven books, most recently his Junior Genius Guides, Because I Said So!, and Maphead. He's also the proud owner of an underwhelming Bag o' Crap. Follow him at or on Twitter as @KenJennings.