Mauna Loa on the archipelago’s Big Island began erupting late Sunday, putting emergency crews on alert.
Hawaii’s Mauna Loa, the world’s largest active volcano, erupted for the first time in nearly four decades, sending volcanic ash and debris falling nearby, officials said.
Lava flows remained contained within the caldera atop Mauna Loa in the US island state, but the eruption could pose a threat to nearby residents if conditions change, the United States Geological Survey said at 11:45 p.m. Sunday (09:45 GMT Monday ), about 15 minutes after the eruption in Hawaii Volcanoes National Park.
“Lava flows are currently contained to the summit area and do not threaten downslope communities,” the Geological Survey said on its website, noting that local residents on Hawaii’s Big Island should review preparedness procedures.
While the eruption on the Pacific nation’s main island remains confined to the volcano’s summit basin, “if vents migrate outside its walls, lava flows can move rapidly downslope,” according to the Geological Survey.
Hours later Monday morning, the survey’s volcano monitoring office tweeted: “Lava appears to have flowed outside the caldera, but vents remain confined to the caldera for now.”
Mauna Loa began erupting at 11:30 PM HST on Sunday. The eruption is currently confined to the summit and there is no indication that magma is moving into any rift zone. HVO is watching closely. I follow @USGSVolcanoes for updates. Find webcams here: https://t.co/PCmuqZqpcB pic.twitter.com/dv6vJBsASo
— USGS (@USGS) November 28, 2022
“However, lava flows in the summit area are visible from Kona,” the Hawaiian Volcano Observatory said in a statement. “There is currently no indication of migration of the eruption into a rift zone.”
A fault zone is where a mountain splits. The rock is fractured and relatively weak, and it is easier for magma to escape.
How long the volcano will erupt and whether it could cause lava to flow into populated areas is impossible to predict, said Miele Corbett, a spokesman for the Geological Survey.
“But I can tell you that we are in constant communication with Hawaii Civil Defense right now and they are providing updates to members of the community,” she said.
The Geological Survey said the Hawaiian Volcano Observatory is consulting with emergency management personnel and its personnel will conduct aerial reconnaissance over the 4,168-meter volcano as soon as possible.
Hawaii officials said no evacuation orders had been issued, although the summit area and several roads in the region were closed.
A Geological Survey webcam on the north rim of Mauna Loa’s summit showed long, bright eruption fissures in the crater.
Parts of the Big Island were under an ash fall warning issued by the National Weather Service in Honolulu, which said up to 0.6 centimeters (a quarter inch) of ash could accumulate in some areas.
The Hawaiian Islands are home to six active volcanoes. Mauna Loa, the largest on Earth, has erupted 33 times since 1843, according to the Geological Survey.
The last eruption, in 1984, lasted 22 days and produced lava flows that reached seven kilometers (four miles) from Hilo, a city of 44,000 today.
Last month, scientists said Mauna Loa was in a “state of heightened concern” after a series of earthquakes were felt in the area.
Mauna Loa is the much larger neighbor of the Kilauea volcano, which erupted in 2018 and destroyed 700 homes. Some of Mauna Loa’s slopes are much steeper than Kilauea’s, so when it erupts, the lava can flow much faster.
During an eruption in 1950, the mountain’s lava traveled 24 kilometers (15 mi) to the ocean in less than three hours.