Hawaii’s Mauna Loa is erupting for the first time in nearly 4 decades

The world’s largest active volcano, Hawaii’s Mauna Loa, erupted for the first time in nearly four decades, authorities said Monday.

Mauna Loa erupted Sunday at 11:30 p.m. local time in what was the first eruption since 1984, according to the Hawaii Volcano Observatory.

When the eruption began at Moku’āweoweo, Mauna Loa’s summit caldera in Hawaii Volcanoes National Park, the US Geological Survey upgraded the volcano’s alert level from advisory to warning.

“At this point, lava flows are contained in the summit area and do not threaten hillside communities,” the USGS said.

“Winds can carry volcanic gas and possibly fine ash and Pele’s hair downwind.”

The USGS warned that the early stages of the eruption “could be very dynamic and the location and encroachment of lava flows can change rapidly.”

“If the eruption stays in Moku’āweoweo, lava flows will most likely be trapped within the caldera walls,” the statement said. However, if the eruption spreads outside the walls of Mauna Loa’s summit caldera, “lava flows can flow rapidly down the slope.”

Residents at risk from Mauna Loa have been cautioned to read the preparedness guides and contact the Hawai’i County Civil Defense Information Center for further guidance.