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 US Geological Survey's Hawaiian Volcano Observatory says. USGS geologist Janet Babb compares the blast on Sunday to taking a hammer to the top of a bottle of champagne. "You look at the bottle and you see the liquid, but you don't see the gas," she says. "There's a lot of gas in the lava. And so, when that rockfall hits the lava lake, it's like the moment you knock the top of the champagne bottle off and that gas is released and it hurls molten lava and rock fragments."
Video of the event shows a wall of rocks sliding into a lava lake that last week rose to a record-high level. The slide caused an explosion that sent fist-size chunks of rock onto the closed Halemaumau visitor overlook, according to the USGS. The area has been closed since 2008, when the lava lake formed, and no one was injured. There could be fallout of ash and dust from this type of event, but it's very unlikely that anyone could be injured, Babb says. Wind direction dictates the amount of debris that lands in visitor areas, she says. A magnitude-3.6 earthquake was felt in the area early yesterday morning, according to the USGS. (Read more Hawaii stories.)