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.

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.

These photographs were taken by Ken Hon, Scientist in Charge of HVO from Waikoloa at about 1:27am. #MaunaLoa #MaunaLoaErupts

Lava is still erupting from the summit & is overflowing from the caldera. No threats to populated areas currently. https://t.co/yLBkg85jMa pic.twitter.com/vhScY3WGjR

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

Lava flows have been currently restricted to the summit area and do not threaten nearby communities.

The intervals between eruptions - of which a total of 33 have been recorded - have ranged from months to decades. It last erupted in 1984.

The Hawaiian Volcano Observatory (HVO) warned that: "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."

Their officials are planning to operate flights over the site to assess the state of the volcano and potential hazards.

Another US agency, the National Oceanic and Atmospheric Administration, has tweeted satellite images showing the heat from the eruption as it appeared from space, and sulphur dioxide it has been releasing.

Around 11:30 p.m. HST last night, @NOAA's #GOESWest ??? captured the eruption of Hawaii's #MaunaLoa volcano, inside @Volcanoes_NPS.

This imagery shows the heat signature and the sulfur dioxide released from the #volcano's summit caldera, Moku‘aweoweo. pic.twitter.com/gHEG63rbLb

— NOAA Satellites (@NOAASatellites) November 28, 2022

Mauna Loa is one of five volcanoes which make up Big Island, which is the southernmost island in the Hawaiian archipelago.

At 4169m above sea level it is much larger than the neighbouring Kilauea volcano, which erupted in 2018 and destroyed 700 homes.

During a 1950 eruption, Mauna Loa's lava travelled 24km to the ocean in less than three hours.

BBC