Mauna Loa

Mauna Loa is the largest active volcano on the planet. Meaning "long mountain" in Hawaiian, it is the quintessential shield volcano in its shape— signified by broad, rounded slopes. The volcano makes up roughly 51% of Hawaiʻi Island and stands 13,681 feet (4,170 m) above sea level. More impressive, however, it rises an astonishing 30,000 feet (9,144 m) from the bottom of the sea, a greater height than Mount Everest. The ocean floor actually bends under the weight of this mammoth mountain. By itself, the land mass that Mauna Loa encompasses is almost equal twice all of the other Hawaiian islands combined.

Eruptions of Mauna Loa have historically been characterized by high volume flows that produce lava capable of travelling long distances, contributing to its shape. Scientists believe that 90 percent of the volcano's surface has been covered with flows that erupted within the past 4,000 years.

Timeline showing historic eruptions of Mauna Loa — Chart adapted from "Eruptions of Hawaiian Volcanoes— Past, Present, and Future" (2010) from the USGS Hawaiian Volcano Observatory

Map showing lava flows from Mauna Loa volcano, color coded by year — Map from the USGS Hawaiian Volcano Observatory showing lava flows of Mauna Loa by year and designated lava flow hazard zones (Click for full size photo)

Mauna Loa is comprised of a main summit caldera called Moku‘āweoweo and two rift zones to the northeast and southwest. The two rift zones are historically very active, sending out flows toward the city of Hilo in 1984 and South Kona in 1950 respectively. A series of 33 radial vents also extend to the northwest. Eruptions of Mauna Loa most often will begin in the summit caldera and then later migrate to a rift zone.

Mauna Loa has erupted 34 times since 1843— averaging once every five years. Over a longer period of time, the past 3,000 years, its estimated to have erupted once every six years.