How Big Is the Largest Volcano on Earth?

Tamu Massif, the largest volcano on Earth, covers an area of more than 120,000 square miles (310,800 square kilometers). This is equivalent to about the size of New Mexico, US or Poland. The volcano is located underwater about 1,000 miles (1,609 kilometers) off the eastern shore of Japan in the Pacific Ocean. Tamu Massif is believed to be about 145 million years old. It has been inactive for more than 100 million years.

More about volcanoes:

• The largest active volcano on Earth is the Mauna Loa in Hawaii. It is less than 2% the size of Tamu Massif.
• Olympus Mons, the largest volcano on Mars and in our solar system, is only about 25% larger than the Tamu Massif and can be seen from Earth on a clear night with a backyard telescope.
• About 50 to 70 volcanoes erupt each year, many of them in the ocean.