March 8, 1996

A weekly feature provided by scientists at the Hawaiian Volcano Observatory.

Crater Floor Falls Down! Kilauea In 1960

Monday, March 11, marks the anniversary of the last of a series of dramatic collapses at Kilauea summit. On three occasions in February and March 1960 the floor of Halemaumau Crater broke apart and collapsed inward, raising a roiling black column of steam and rock dust 500 feet in the air. Hundreds of shallow, small earthquakes rocked the summit in the days preceding each collapse, as cracks along the rim of Halemaumau widened and loose rock bounded down the steep crater walls. National Park Service ranger R.T. Haugen, patrolling Crater Rim Drive on the night of one event, provides this chilling account:

"Through the night and early morning the entire caldera region shuddered....the ground was in almost incessant motion. From the dark interior of the pit strange booming sounds accompanied the constant clatter of rocks raveling off the walls and the occasional jetlike roar of an avalanche spilling onto the floor...then, with a mounting roar and a voluminous rising cloud of steam and rock dust, a circular area 1000 feet in diameter...suddenly began to fall as though a gigantic plug had been pulled deep within the crater. In less than 9 minutes the huge pit collapsed [inwards] more than 200 feet."

Surprisingly, the collapse witnessed by Haugen was actually caused by eruptive activity some 40 miles east of Halemaumau near the town of Kapoho. At the start of the Kapoho eruption in January 1960, the great molten reservoir beneath Kilauea's summit drained away as magma shuttled down the east rift zone toward the new fissures. Spectacular lava fountains spawned in the cane fields in lower Puna, while back at the summit the ground above the emptying reservoir subsided rapidly. The subsidence intensified as the eruption progressed until the sagging floor of Halemaumau finally gave way in a series of violent collapses. Fortunately for the many visitors to the Halemaumau overlook, such events are relatively rare.

Volcano Update

The current eruption of Kilauea continues unabated, with flows entering the ocean at Kamokuna. There were two felt earthquakes this week. The first, a magnitude 3.6 located at a depth of ~ 5 miles below the south flank of Kilauea, occurred at 10:28 p.m. on March 2. The second, a magnitude 4.0 on March 5 at 1:07 a.m., occurred 13 miles beneath Volcano Village. No damage was reported.