Mauna Loa

Mauna Loa volcano at sunrise
Mauna Loa rising from behind Kīlauea Caldera (NPS Photo/J. Wei)
 
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 13,678 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.

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 three rift zones to the northeast, northwest and southwest. The northeast and southwest rift zones are historically the most active, sending out flows toward the city of Hilo in 1984 and South Kona in 1950 respectively. The northwest rift is not a true “rift zone”, and is unusual in that it is comprised of at least 33 radial vents. Eruptions of Mauna Loa most often will begin in the summit caldera and then later migrate to a rift zone.

Mauna Loa has erupted 33 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. We are currently in the volcano's longest quiet period since written records have been kept, as it has not erupted since 1984.

Current information:

 

Notable Eruptions of Mauna Loa

 
Helicopter on the ground in front fountains of orange molten lava

1984 Eruption of Mauna Loa

The last eruption of Mauna Loa before its longest recorded period of quiet

Painting of an erupting volcano with a boat on the ocean in the foreground

1880- 1881 Eruption of Mauna Loa

An eruption that threatened the city of Hilo and saw the first known attempts at lava diversion

Black and white photograph of devastated houses in a field of rubble

1868 Eruption of Mauna Loa

One of the deadliest disasters in Hawaiian history

Last updated: June 13, 2020

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