The world’s largest active volcano Mauna Loa in Hawaii, has erupted for the first time in 38 years

Videos showing Hawaii’s Big Island sky turning red and ash emitting into the air have surfaced online after the volcano erupted on Sunday.

The lava flow is mostly contained within the summit, but residents have been placed on alert and were earlier warned about the risk of falling ash, according to a BBC report.

The US Geological Service (USGS) has said the situation could change rapidly. The volcano’s alert level has also been upgraded from an “advisory” to a “warning” – the highest classification.

Mauna Loa, located inside Hawaii Volcanoes National Park, covers half of the US state’s Big Island. The volcano rises 13,679ft (4,169m) above sea level and spans an area of more than 2,000 sq miles (5,179 sq km).

An advisory for ashfall – which can contaminate water supplies, kill vegetation and irritate the lungs – was in effect for the surrounding area overnight but has since been lifted.

Mauna Loa has erupted 33 times since 1843. The previous eruption in 1984 sent lava flows within 5 miles of Hilo, the island’s most populous town.

But the Big Island’s population has more than doubled since 1980 to around 200,000 residents and Hawaii’s civil defence agency has warned residents could face a “lava disaster”.