Crater collapses, lava explodes from Hawaii’s Kilauea

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.

"You look at the bottle, and you see the liquid, but you don't see the gas," she said. "There's a lot of gas in the lava. And so, when that rock fall 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."

Rocks overhanging the lava lake are altered by gases coming from the lava, Babb said. The rocks eventually give way and collapse into the lava, causing an explosion.

The material was hurled about 280 feet skyward, she said.

The Big Island of Hawaii is one of many islands in the Pacific Ocean that are active, dormant or extinct volcanoes, according to the USGS. The active volcanism is limited to a specific area, or hot spot.

The USGS calls Kilauea "among the world's most active volcanoes" and says it "may even top the list." The current eruption began in 1983 and last year threatened the town of Pahoa.  

Video of the most recent event shows a wall of rocks sliding into a lava lake, which 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 said. Wind direction dictates the amount of debris that lands in visitor areas, and it is relatively common, she said.

The last time lava was visible in the crater was in 1982, when a fissure erupted. The last time there was a lake similar to this one was in 1974.

The vent in Halemaumau Crater has been rising and falling since it opened, and it reached a record high last week. Even at its previous highest level in October 2012, the lake was too low for people to see. During the day, people could view the gas rising from the lake, and at night people could see the orange glow from the lava.

From the early 1800s up until 1924, there was a continuous lake of lava at Kilauea in Halemaumau. At that time, the crater was about half its current diameter.

In 1924 there was a huge eruption in the volcano that doubled the size of the crater. Since then, lava lakes have been present at different times. In 1967 and 1968, the entire crater was filled with lava. A ring on the walls of the crater where the lava had risen at that time remains visible.

A magnitude 3.6 earthquake was felt in the area early Monday morning, according to the USGS.

Last week Chile’s Calbuco volcano erupted for the third time in eight days, sending a new cloud of ash and gas high into the sky.

Al Jazeera with the Associated Press