Nearly 40 years later, Mauna Loa, the largest active volcano on the planet, has erupted on the Big Island, Hawaii’s main island. It started at 11:30pm local time on Sunday November 27 (10:30am on November 28 in Italy) and was quickly visible from Kona, one of the most popular resort towns on the island’s west coast.

There is no need to evacuate areas around the volcano, although some shelters have been activated as a precaution. Dust and gas from an explosion can travel for miles, requiring some extra caution.

The eruption initially affected the upper crater of Mauna Loa, 4,169 meters high, but in the following hours the United States Geological Institute (USGS) Informed Lava began to flow on the northeast side of the volcano.

According to experts, this should reduce the risk of lava flow in the direction of the west corner, since eruptions of Mauna Loa usually only affect one area of ​​the large volcano. The northeast slope is also not very steep, and as a result, it may take weeks for the lava to eventually reach populated areas: the coming days will depend on the amount of material produced by the eruption.

#long mountain Eruptions originate from vents in the northeast rift zone. The currents move down to the north. USGS photos from Civil Air Patrol combat. #Maunaloa is erupting @Volcanoes_NPS @Hwaii_EMA @civildefenceHI pic.twitter.com/kUYWYPdk4L

— USGS Volcanoes🌋 (@USGSVolcanoes) November 28, 2022

However, the situation is carefully controlled, because often the eruptions of Mauna Loa are accompanied by intense earthquakes. In 1868, the strongest earthquake ever recorded in Hawaii was traced to volcanic activity. In general, however, an explosion does not necessarily indicate an earthquake, and vice versa.

This short video shows thermal camera footage of the scene #long mountain Eruption from the summit of the volcano. The colored scale bar on the right shows the temperature in degrees Celsius. For more information visit: https://t.co/rfwkMVSJKM #Maunaloa is erupting pic.twitter.com/PhHXbq9nNa

— USGS Volcanoes🌋 (@USGSVolcanoes) November 28, 2022

According to USGS calculations, Mauna Loa has had 33 eruptions since 1843. Its name literally means “long mountain,” and it covers more than half of the entire Big Island. Its eruptions are usually of low viscosity, as a result of which the lava flows easily and there are no explosions in the vicinity of the crater.

Image from Mauna Loa Summit Webcam acquired at 11:46 PM HST.

Webcams for the volcano can be found here https://t.co/Vb49rS11OH. pic.twitter.com/BDNWWT3kjH

— USGS Volcanoes🌋 (@USGSVolcanoes) November 28, 2022

The most widely shared estimate among researchers is that Mauna Loa has been active for about 700,000 years and emerged from under the sea — just as lava built the volcanic edifice — about 400,000 years ago.