View of Pu`u Pua`i cinder and spatter cone from the northeast rim of Kilauea Iki. Pu`u Pua`i was built on the southwest rim of Kilauea Iki by 17 episodes of high lava fountaining that erupted from a vent at the base (lower right base of cone) in November-December 1959. The prevailing trade wind blew the erupting spatter and pumice fragments southwestward (roughly from right to left), thereby building the cone and depositing a thick layer of tephra across the southeastern part of Kilauea Caldera and beyond.
This side of Pu`u Pua`i is marked by a series of cracks and slump features that developed as layers of agglutinated spatter and cinder plastered onto the cone during fountaining episodes slid down toward the vent. Note the prominent fracture or scarp at the top of the cone, which corresponds to the underlying crater rim of Kilauea Iki. The slumping of tephra has exposed the inner core of Pu`u Pua`i.
When viewed by geologists only three days after the last fountain episode, the vent was about 30 x 15 m at its top and about 60 m deep. The bottom of the vent was incandescent. Rock falls and slumps from the side of Pu`u Pua`i, however, quickly filled the vent with rock debris. A hiking trail crosses the floor of Kilauea Iki and provides close-up views of Puu Pua`i.