Collapse at the summit of the Puu Oo cone has created a crater. Compare this photo to the one above that was taken in 1986. Helicopter for scale. Photo by Steve Mattox, July, 1994. The Puu Oo cone is closed to visitors because it is falling apart.
Geologists minimize their time spent on the cone.
They visit briefly about once per week to change the film in a time-lapse camera and to make observations. Photo by Steve Mattox, September, 1991. Part of the base of the crater is filled by a lava pond. Helicopter for scale. Photo by Steve Mattox, January, 1992.