Big Island, HAWAII — The largest active volcano in the world, Hawaii's Mauna Loa has erupted for the first time in nearly 40 years.

It erupted around 23:30 local time on Sunday (09:30 GMT Monday), and has created a spectacular spectacle of lava explosions and flows within its caldera and generated a bright red glow above the island.

Local authorities say the eruption currently doesn't pose an immediate threat but have warned residents to be prepared if conditions change. An advisory for ashfall has also been lifted.

"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 US Geological Service stated in an alert.

Mauna Loa, which is located in Hawaii County - better known as the "Big Island", is the largest island in Hawaii which last erupted in 1984. Over the last few weeks, a series of eruption warnings had been issued after a spate of recent earthquakes and tremors in the region.

"There have been warnings over the past couple of weeks that the volcano was showing signs that there would be an eruption, so it comes as no surprise", Floyd Takeuchi, a photographer in Honolulu, said.

Takeuchi said that much of the Hawaiian public has undergone emergency drills and that evacuation centres have been set-up, particularly in Hilo, the largest city in Hawaii Country. Hilo is located 59 kilometres from Mauna Loa.

"The concern was that there would be a lava flow into Hilo, but that doesn't seem to be the case at the moment....it's just another eruptive phase," Takeuchi said.

"If it does turn bad, there will be evacuations of people from the expected overflow areas to the evacuation centers."

Mauna Loa is a massive volcano, rising 13,679 feet above sea level and spans an area of more than 5,179 sq-km2, covering half of the Big Island.

"There is a constant state of volcanic activity on the Big Island, which has active volcanoes that have been erupting for some time...but this kind of incident doesn't happen very often," said Takeuchi.

"It's a concern, but it's part of life," he said.