After 38 years, Mauna Loa is rumbling again. The world’s largest volcano that isn't underwater has erupted with lava flowing first from Moku‘āweoweo (the caldera on the summit) before shifting to the Northeast Rift Zone. Mauna Loa is one of five volcanoes that make up the Island of Hawai'i and while it has not caused fatalities in recent years, it poses risks to population centers.

“At about 11:30 p.m. HST on Sunday, Nov. 27, 2022, Mauna Loa volcano on the island of Hawai‘i began erupting,” the United States Geological Survey (USGS) said in an initial statement.

It was then updated hours later when the eruption migrated from Moku‘āweoweo to the Northeast Rift Zone. Since then, the USGS has continued its close monitoring, stressing that the flow of lava from the confirmed fissure was not endangering any communities. 

Still, there are concerns that the wind could bring noxious gases, fine ash, and even Pele’s hair, downslope where the people are. Pele’s hair is a type of volcanic glass usually formed in lava fountains or cascades where lava is cooled in thin strands. They are very brittle and very sharp, and small broken pieces can enter the skin.

The latest update from the USGS mentions several lava fountains, with most of them being just a handful of meters tall. The tallest might reach 60 meters (200 feet) in height. The lava flows from two upper fissures have moved downslope. These two flows have now stopped as the level of lava in the volcano dropped following the eruption. There is currently a flow from a third fissure and more might open but the eruption continues to be contained just to the Northeast portion of the volcano.

“There is no active lava within Moku'āweoweo caldera, and there is no lava erupting from the Southwest Rift Zone. We do not expect any eruptive activity outside the Northeast Rift Zone. No property is at risk currently. There is a visible gas plume from the erupting fissure fountains and lava flows, with the plume primarily being blown to the Northwest,” the USGS wrote in a statement.

Mauna Loa is 4,170 meters (over 13,600 feet) above sea level, but counting its height from the bottom of the ocean, it would easily be taller than Mount Everest. Taking into consideration underwater volcanos, it is the second biggest volcano by mass and volume. The first is Tamu Massif. 

Mauna Loa last erupted in 1984, for almost a month between March 25 and April 15.