The world’s largest active volcano has erupted in Hawaii for the first time in nearly four decades, officials said.
Mauna Loa erupted at 11:30 p.m. local time (4:30 a.m. ET Monday) on Sunday, according to the U.S. Geological Survey. It was the first eruption since 1984, according to the Hawaii Volcano Observatory’s daily update.
The eruption began in Moku’āweoweo, the caldera at the top of Mauna Loa, in Hawaii Volcanoes National Park, the agency said, as it upgraded the volcano’s alert level from an “advisory” to a “warning.”
“Currently, the lava flows are in the summit area and do not pose a threat to downstream communities,” the agency said in a press release. “Winds can carry volcanic gas and possibly fine ash and Pele’s hair downwind,” it said, referring to a type of lava.
Residents at risk from Mauna Loa’s lava flows were advised to “review preparedness and consult Hawai’i County Civil Defense information for further guidance.”
“Based on past events, the early stages of a Mauna Loa eruption can be very dynamic and the location and progression of lava flows can change rapidly,” the agency warned. It said if the eruption at Mokuʻāweoweo continues, lava flows would most likely be contained. “However, if the eruptive vents migrate beyond the walls, lava flows could go down quickly,” he said.
The most recent eruption followed weeks of warnings from officials that an eruption was possible given a recent spike in earthquakes at the volcano’s summit and that residents of the Big Island should be prepared to evacuate, Hawaii’s NBC affiliate KHNL reported.
The USGS said the “heightened unrest” began in mid-September, when the number of earthquakes below the summit increased from 10 to 20 a day to 40 to 50 a day. That unrest prompted Hawaii Volcanoes National Park to close the summit hinterland until further notice, KHNL reported.
Ken Hon of the Hawaiian Volcano Observatory said the quakes were mainly caused by the mountain’s weight slowly sliding toward the ocean, KHNL reported.
The volcano, whose name means “Long Mountain,” occupies half of the island, according to the US Geological Survey. Prior to its most recent eruption, it erupted 33 times starting in 1843, making it one of the world’s most active volcanoes. According to the US Geological Survey, it is one of six volcanoes in the state of Hawaii.
About half of those previous eruptions remained in the summit region — which rises about 17,000 feet above the base, according to the U.S. Geological Survey — and most of the others migrated from the summit into one of the rift zones, creating lava flows that covered broad areas on the mountain . the volcano’s lower slopes, according to the USGS.
“Hawaiian lava flows have rarely caused human fatalities, but they can wreak havoc by blanketing, burning and crushing everything in their path, or starting secondary fires,” the USGS said, adding that interactions between water and lava “also can sometimes be explosive in coastal environments.”
When the northeastern flank of the volcano erupted in 1984, residents had time to prepare, as the eruption occurred in a “higher slope area” and the lava took longer to travel to the city of Hilo – the city in the northeastern region from the island and home to the Hilo International Airport — former Hawaii mayor Harry Kim, who was the administrator of civil defense at the time, told KHNL. That eruption lasted three weeks, according to the US Geological Survey.