While attention is focused on the potential imminent eruption of Mount Agung in Bali, another deadly Indonesian volcano has dramatically exploded.

Mount Sinabung, in northern Sumatra, spewed plumes of ash 2.5km into the air as it erupted at 1.23pm local time on Wednesday.

Thousands of villagers were evacuated from around the mountain, the most active of the country's 130 active volcanoes, and warned to stay at least 7km away.

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Deadly Indonesian volcano Mount Sinabung spewed plumes of ash 2.5km into the air as it exploded

Authorities feared lava flows could cascade down the mountain and destroy homes, as has happened several times.

The volcano explodes so frequently, warning signs are permanently stationed around it warning against going near it.

Only last month another eruption rocked the area, blasting ash 4.2km into the air and causing pyroclastic flows many kilometres across surrounding countryside.

Earlier in the year 10 people were killed in another eruption, with its death toll sitting at 20 in the past decade, including four high school students and their teacher on a school excursion.

Thousands of villagers were evacuated from around the mountain, the most active of the country's 130 active volcanoes, and warned to stay at least 7km away

A thermal image of Sinabung's eruption on Wednesday afternoon

Sinabung is located on the 'Ring of Fire', a volatile zone of seismic activity with hundreds of active volcanoes and 90 per cent of the world's earthquakes.

An even bigger eruption could be imminent 2,500km away in Bali where Mount Agung is on the highest alert level.

Scientists said there were 1,000 tremours around the island's highest peak in a single day and if they continue it could erupt in a matter of hours.

More than 75,000 people fled a 12km radius around Agung, fearing a repeat of its last eruption in 1963 when 1,000 died.

Sinabung is located on the 'Ring of Fire', a volatile zone of seismic activity with hundreds of active volcanoes and 90 per cent of the world's earthquakes

An even bigger eruption could be imminent 2,500km away in Bali where Mount Agung is on the highest alert level

Scientists said there were 1,000 tremours around the island's highest peak in a single day and if they continue it could erupt in a matter of hours

Photographer Steven Wright captured two images of fires which broke out on the side of Mount Agung (pictured) earlier this week

Airlines flying from Australia to Denpasar, including Jetstar and Virgin Australia, are taking on excess jet fuel in Darwin on the way in case the volcano erupts.

It has been smoking for almost a week since a 5.7 magnitude earthquake struck of the neighbourng island of Java last Thursday.

Indonesian President Joko Widodo visited the area on Tuesday, encouraging local residents to evacuate the area and seek safety in the 370 shelters set up for those without homes.

'While the government will continue to try to minimize the economic losses of the community, the most important priority is the safety of the people here,' Widodo said.

Australian Bali Nine member Scott Rush (pictured) is amoung the 166 prisoners moved from Karangasem jail which could be affected if Mount Agung volcano erupts

People wait inside an evacuation centre in Klungkung regency, on the Indonesian resort island of Bali

Villagers rests at a temporary evacuation centre, for people living near Mount Agung, Bali

'So I ask all people around Mount Agung to follow instructions from the officials and minimize the impact of this volcano.'

Australian Bali Nine member Scott Rush is among the 166 prisoners moved from the notorious Karangasem jail which could be affected if Agung erupts.

More than 50,000 Australian tourists are on the idyllic holiday island for their school holidays, but authorities insist the destination is safe.