View of Pu‘u ‘Ō‘ō's west flank in 1999, after crater overflows, con...

In June 1997, lava flows poured from the main Pu‘u ‘Ō‘ō crater for the first time since high lava fountains ended in 1986, spilling through the west gap and west of the shield on Pu‘u ‘Ō‘ō's flank. The episode-55 spatter cone began to collapse in August 1998; by April 1999, a pit 60 x 100 m (200 x 330 ft) in diameter had largely consumed the spatter cone.