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Mauna Loa, Earth's largest active volcano, has erupted 33 times since 1843, producing the lava flows shown in black. All of these historic eruptions started at the summit of the volcano. From there, the eruptions either stayed in the summit area or migrated down the volcano's Northeast or Southwest Rift Zones. Some Mauna Loa eruptions occurred at radial vents, indicated by red squares, scattered across the north and west flanks of the volcano.