Molten lava, rocks and gas went flying through the air on Hawaii's Kilauea volcano after an explosion was caused by the partial collapse of a crater wall. The collapse triggered a small explosion, spreading lava and debris around the rim of Kilauea's Halemaumau Crater, the U.S. Geological Survey's Hawaiian Volcano Observatory says. Janet Babb, a geologist with the USGS, compared the blast on Sunday to taking a hammer to the top of a bottle of champagne.