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 13,681 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.

Current information:

 

Notable Eruptions of Mauna Loa

 
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

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 in Hawaiʻi

Black and white aerial photo of a bomb exploding on a lava flow

1935 Eruption of Mauna Loa

As the 1935 eruption began to close in on Hilo, aerial bombing was employed in an attempt to alter its course

Volcano erupting along its flank in a distance.

1942 Eruption of Mauna Loa

An eruption that was declared a "secret" during World War II.

Black and white aerial photo of lava flow entering the sea

1950 Eruption of Mauna Loa

In June 1950, Mauna Loa sent large lava flows to the sea with blazing speed.

Molten lava flowing down a mountain side with a silhouetted mountain beyond at sunrise

1975 Eruption of Mauna Loa

The brief but spectacular eruption of 1975 lasted less than 24 hours

Helicopter on the ground in front fountains of orange molten lava

1984 Eruption of Mauna Loa

The 1984 eruption of Mauna Loa that ended 4 miles away from the town of Hilo.

Lava fountaining along the flank of a volcano.

2022 Mauna Loa Eruption

Mauna Loa erupts for the first time in nearly 40 years.

Last updated: November 30, 2022

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