World's Largest Active Volcano Just Erupted in Hawaii — What to Know

Hawaii’s Mauna Loa volcano erupted late Sunday evening for the first time in decades, bringing new attention to the world's largest active volcano.

The volcano, which sits inside Hawaii Volcanoes National Park on the Big Island, erupted at 11:30 p.m. HST (4:30 a.m. ET), according to the U.S. Geological Survey. The eruption — the first in nearly 40 years — is currently contained to the summit area and is not threatening nearby communities. 

The department upgraded its volcano alert level to a “warning.”

“At this time, lava flows are contained within the summit area and are not threatening downslope communities,” the U.S. Geological Survey posted Monday morning, but warned, “Winds may carry volcanic gas and possibly fine ash and Pele’s hair downwind… Based on past events, the early stages of a Mauna Loa eruption can be very dynamic and the location and advance of lava flows can change rapidly.”

The department said area residents “should review preparedness and refer to Hawai‘i County Civil Defense information for further guidance.”

The National Weather Service Honolulu issued an ashfall advisory and warned “Falling volcanic ash and debris can cause respiratory distress in people, and render engines or electronics inoperative.”

While the lava remains contained to the summit, it was visible from the town of Kona, the U.S. Geological Survey noted.

Southwest Airlines has issued a waiver for passengers traveling to Hawaii on Nov. 28 and Nov. 29. The airline is allowing travelers scheduled to travel to Hilo, Honolulu, Kahului, Kona, or Lihue to change their departure or origin for no additional charge due to the potential for the volcano to cause delays or interruptions, according to the airline.

Last month, the National Park Service had closed the volcano summit to visitors “due to elevated seismic activity on Mauna Loa and as a precautionary measure.” 

Mauna Loa has erupted a total of 33 times since 1843, averaging one eruption every five years. The volcano last erupted in 1984, marking the “longest quiet period since written records have been kept,” according to the NPS.

The eruption followed more than a dozen earthquakes of more than 2.5 magnitude, Reuters reported, including one that measured 4.2 in magnitude.