Earth's biggest volcano is located in Hawaii

"Where is the biggest volcano?" asked Kate Anderson, 10, a fifth-grader at Butterfield School in Libertyville.

Half of the island of Hawaii is made up of the Earth's biggest volcano, Mauna Loa. It covers more than 2,000 square miles of rolling terrain and rises more than 2 miles above sea level.

That's only the visible part of the volcano -- Mauna Loa drops below the ocean's surface about 3 miles.

Mauna Loa also is one of Earth's most active volcanoes. Since 1843, lava has spewed from its depths 33 times. Its most recent eruption was in 1984.

There are more than 850 active volcanoes on Earth. They come in many shapes and sizes. Like the four other volcanoes on the island of Hawaii, Mauna Loa is a shield volcano.

Shield volcanoes are created when fairly fluid lava erupts over long periods of time, creating gently sloping layers. Mauna Loa's slopes have been in the works for one million years.

Darcy Bevens of the Center for the Study of Active Volcanoes at the University of Hawaii said, "Most people don't realize they are on the volcano because they are looking for something shaped like Mt. Fuji. Our volcanoes are shield-shaped, very gentle slopes."

There are volcanoes that are even bigger than Mauna Loa -- on Mars. Mauna Loa is a third the size of Olympus Mons, a giant shield volcano on Mars. Olympus Mons is much older, too, at more than a billion years old.