View of Pu‘u ‘Ō‘ō's west flank in 1997, after collapse of the crate...

Hours before the fissures of episode 54 erupted on January 30, 1997, the lava pond in Pu‘u ‘Ō‘ō drained as magma was diverted to the area beneath Napau Crater, about 3 km uprift. The withdrawal of magma led to the collapse of the Pu‘u ‘Ō‘ō crater and west rim. A prominent a notch formed in the rim about 150-200 m (490-660 ft) wide and 75-100 m (250-330) deep. Note growth of shield at base of west flank since 1992. The prominent spatter cone atop the shield to the right of the collapsed rim began erupting on March 28, 1997.