View is from the northeast rim of Kilauea Iki toward the west. The low tree-covered area on the opposite side of the pit crater is Byron Ledge, a fault block related to the collapse of Kilauea Caldera (visible at top). The cinder and spatter cone left of Byron Ledge, Pu`u Pua`i, was built during a spectacular series of lava fountains from Kilauea Iki in November-December 1959. The crater is about 120 m deep.
Kilauea Iki consists of at least two pit craters (visible in image) that were formed by collapse of the ground and an older, small crater related to the `Aila`au lava shield active 350-400 years ago (this crater, at the east end of Kilauea Iki, is forested and largely filled with rock debris). Prior to the 1959 eruption, the deepest part of Kilauea Iki was about 240 m below the rim.
The 1959 eruption consisted of 17 episodes of high fountaining lasting from one week to about 23 hours. The highest lava fountain reached 580 m on December 19, the highest ever observed at Kilauea Volcano. Lava discharge varied from about 500,000 m3 per hour at the beginning of the eruption to 1,600,00 m3 per hour on December 19. These episodes filled the crater to a maximum depth of about 130 m.
Between the fountain episodes, however, some of the ponded lava drained back down the throat of the main vent at the base of Pu`u Pua`i. The partial draining of lava left high lava marks at the base of the crater wall; the highest lava mark visible along the north crater wall (right edge of lava surface at base of crater wall) is about 15 m above the crater floor.
Richter, D.H., Eaton, J.P., Murata, K.J., Ault, W.U., and Krivoy, H.L., 1970: Chronological narrative of the 1959-60 erution of Kilauea Volcano: U.S. Geological Survey Professional Paper 537-E, 73 p.