Mauna Kea ("white mountain") is the second largest volcano of the island and last erupted 3,500 years ago. Although Mauna Kea has not erupted in historical time, it probably will erupt again and is therefore considered dormant.Photograph by Jack Lockwood, U.S. Geological Survey, December 1, 1981.
Mauna Kea is in the capping stage and has slopes that are steeper than Mauna Loa's and Kilauea's. The lava and tephra from the capping stage filled any calderathat might have been present. There are no pronounced rift zones. The alignment of cinder cones suggests rift zones once extended to the west, south, and east. Gulches have developed on the northeast slope of the volcano. The other slopes are little affected by erosion. Light-colored areas on the upper slopes of the volcano are glacial deposits. Photograph of the southwest flank of Mauna Kea by Ed Wolfe, U.S. Geological Survey, 1988.
Cinder cones and astronomical observatories are located at the summit of the volcano. Photograph by Don Swanson, U.S. Geological Survey.