When was the last time Mauna Loa erupted and when will it erupt again?

Mokuaweoweo caldera is at the summit of Mauna Loa Volcano. The caldera is 2.7 miles long by 1.6 miles wide (4.3 by 2.5 km). This photo is a view across Mokuaweoweo Caldera looking to the north. Photograph by Jack Lockwood, U.S. Geological Survey, December 1, 1981.

Mauna Loa is an active volcano and is due for an eruption. Flows have been generated outside the summit caldera 22 times in the last 150 years (note the production rate of lava has been lower after 1876). The last eruption was in 1984. Nearly all the eruptions begin at the summit. About half of these migrate down into a rift zone. To find out more about Mauna Loa click here.

Steve Mattox