Bet you thought that the biggest mountain was Mount Everest! Mount Everest does hold a world record, but not as the biggest mountain. Everest is the highest elevation on land, but it is only a single peak in an entire mountain range. The highest mountain is not necessarily the largest. Mauna Loa (4,169 m (13,678 ft)) is the largest mountain on Earth in terms of base area (about 2,000 sq mi/5,200 km2) and volume (about 10,000 cu mi/42,000 km3), although, due to the intergrades of lava from Kilauea, Hualalai and Mauna Kea, the volume can only be estimated based on surface area and height of the edifice). Mt. Kilimanjaro is the largest non-shield volcano in terms of both base area (245 sq mi/635 km2) and volume (1,150 cu mi/4,793 km3). Mount Logan is the largest non-volcanic mountain in base area (120 sq mi/311 km2).

Only about 13,448 ft/4100m of Mauna Loa are above sea level, so it may not seem like a very tall mountain. But, when you start measuring Mauna Loa from its true base on the bottom of the ocean, in the Hawaiian Trough, the total height exceeds that of Everest by over 3/4 of a mile. From its base on the ocean floor, Mauna Loa is 33,132 ft., or 10,099 m high. That's taller than Mt. Everest is high, and it's just a single mountain!

Mauna Loa is Hawaiian for "Long Mountain", probably because of its long, gently sloping shape. If you want to get really technical, Mauna Kea, a neighbor of Mauna Loa on the same island of Hawaii, is actually the tallest mountain in the world. Mauna Kea is about 350 ft/107m taller than Mauna Loa, but its mass doesn't compare to that of Mauna Loa. Mauna Loa takes up a lot of space because its mass is 9,700 cubic miles/40,000 cu km of mountain.

What makes Mauna Loa such a big mountain is the way it was formed. As part of the Hawaiian islands, Mauna Loa is a volcano, just like many others found on the island chain. The volcanoes in the Hawaiian islands are different from the cone-shaped, explosive, "fire breathing" dynamos that most of us think of when volcanoes come to mind. Mauna Loa is one of many shield volcanoes that make up the Hawaiian Islands. These are volcanoes that, compared to their more violent companions, erupt slowly and quietly. What really distinguishes a shield volcano is its shape - they are usually much wider than they are tall. Shield volcanoes are created when red hot lava oozes out from cracks, or fissures in the earth's crust.

The volcano has probably been erupting for at least 700,000 years and may have emerged above sea level about 400,000 years ago, although the oldest-known dated rocks do not extend beyond 200,000 years.[3] Its magma comes from the Hawaii hotspot, which has been responsible for the creation of the Hawaiian island chain for tens of millions of years. The slow drift of the Pacific Plate will eventually carry the volcano away from the hotspot, and the volcano will then become extinct within 500,000 to one million years from now.


Mauna Loa's most recent eruption occurred from March 24, 1984, to April 15, 1984. No recent eruptions of the volcano have caused fatalities, but eruptions in 1926 and 1950 destroyed villages, and the city of Hilo is partly built on lava flows from the late nineteenth century. In view of the hazards it poses to population centers, Mauna Loa is part of theDecade Volcanoes program, which encourages studies of the most dangerous volcanoes. Mauna Loa has been intensively monitored by the Hawaiian Volcano Observatory since 1912. Observations of the atmosphere are undertaken at the Mauna Loa Observatory, and of the Sun at the Mauna Loa Solar Observatory, both located near its summit. Hawaii Volcanoes National Park covers the summit and the southeastern flank of the volcano, including a separate volcano, Kilauea.