On the evening of January 29, 1997, a series of earthquakes struck Kīlauea's east rift zone. Deep within the rift zone, magma was escaping from the conduit leading to the Puu Ōō vent, cutting off the supply to the ongoing eruption. The lava pond at Puu Ōō drained, and residents away heard a low, rumbling roar as the crater floor dropped and the west wall of the Puu Ōō cone collapsed. A few hours later, as magma found a new path to the surface, the ground cracked in nearby Nāpau Crater, and lava fountains lit up the night sky. However, activity in this area was short-lived, and the center of activity soon shifted back to Puu Ōō.