Hawaii's Mauna Loa, the world's largest active volcano, has started erupting for the first time since 1984, ending its longest quiet period in recorded history.
The night sky above Hawaii's largest island glowed a hellish red as bright, hot lava sprang forth at the volcano's summit at around 11:30pm local time on Sunday (Monday, 8:30pm AEDT).
The lava is contained within the summit and does not threaten Hawaiians living downslope for now, the United States Geological Service said.
Mauna Loa rises 4,169 metres above the Pacific Ocean, part of the chain of volcanoes that formed the islands of Hawaii. It last erupted in March and April of 1984, sending a flow of lava within about 8 kilometres of Hilo, the island's largest city.
Gaseous clouds rising from the crater of Mauna Loa volcano in 1984 — the last time it erupted. Source: AAP / John Swart
About half of all recorded eruptions of Mauna Loa had been confined to the summit, the agency said.
Experts also cautioned that winds could carry volcanic gas and fine ash downslope, as well as Pele's Hair — the name given to fine strands of volcanic glass formed when lava skeins cool quickly in the air.
Named after Pele, the Hawaiian goddess of volcanoes, the strands can be very sharp and pose potential danger to skin and eyes.
Authorities in Hawaii have not issued any evacuation orders, although the summit area and several roads in the region were closed, and two shelters have been opened as a precaution.
One of six active volcanoes on the Hawaiian islands, Mauna Loa has erupted 33 times since 1843.
Kilauea, a volcano on the southeastern flank of Mauna Loa, erupted almost continuously between 1983 and 2019, and a minor eruption there has been ongoing for months.
