240,000 flee in Bali as volcano threatens to erupt

A local resident takes a picture of Mount Agung  smouldering from a monitoring station in Bali.
A local resident takes a picture of Mount Agung smouldering from a monitoring station in Bali. Photo credit: Reuters

Around 240,000 people are fleeing eastern Indonesia as Bali's Mount Agung threatens to erupt.

The warning was raised to its maximum level four on Friday night, signalling an "imminent" volcanic eruption.

This is the first time in 54 years the volcanic alert has reached this level, indicating an eruption is likely within days.

More than 11,000 people have already left their home. Many of them are staying in shelters across the districts of Karangasem, Klunngkung and Buleleng.

The Volcano Observatory Notice for Aviation said the volcano's seismic activity has increased dramatically.

"This number of seismicity is an unprecedented seismic observation at Agung volcano ever recorded by our seismic networks," it said in a statement.

Around 500 tremors were recorded in the region on Friday between 6am and 6pm (local time), with the highest measuring 3.6 magnitude.

National Disaster Management Agency spokesperson Sutopo Purwo Nugroho said volcanic activity remains high.

"There are indications of magma rising to the surface and causing tremors. There should be zero public activity within the specified radius in case there is an eruption."

Bali's airport is still operating, but would likely close in the event of a big eruption.

New Zealand's Ministry of Foreign Affairs and Trade updated its travel advice for Bali on Tuesday, when the alert level was raised to three. It said New Zealanders should reconfirm travel arrangements before heading to the airport.

Mount Agung last erupted in 1963, killing 1100 people.

The peak of the large volcano sits more than 3000 meters above sea level  that's 13 Sky Towers, or one Sky Tower plus Mount Ruapehu.

Indonesia straddles the "Pacific Ring of Fire", where several tectonic plates meet and cause 90 per cent of the world's seismic activity.

The country has nearly 130 active volcanoes, more than any other country.