An eruption could happen any moment as the volcano in Indonesia's resort island, Bali, sends out a large amount of smoke. Officials sent out a warning on Monday, raising the alert to the highest level and expanding the exclusion zone.
Massive columns of thick grey smoke have been pouring out of Mount Agung since last week and, on Monday, shot more than 3km into the sky, prompting the island's international airport to be closed, leaving thousands of tourists stranded.
Mount Agung started rumbling again last week and so-called cold lava flows appeared on Monday, it is similar to mudflow and is often a prelude to the blazing orange lave seen during many volcanic eruptions.
"The volcano's alert level has been raised to the highest level," said senior state volcanologist Gede Suantika. "Constant tremors can be felt."
The last time the volcano erupted was in 1963 and killed about 1600 people, one of the deadliest eruptions in a country that has more than 120 active volcanoes.
About 25 000 people living nearby the mountain have already left their homes and evacuated since Agung first started to spew smoke on Tuesday. The exclusion zone around Agung, which is 75km from the tourist hub of Kuta, has been widened to 10km, with people living in that area being urged to evacuate.
"Continuous ash puffs are sometimes accompanied by explosive eruptions and a weak booming sound," the National Board for Disaster Management said in a statement.
"The rays of fire are increasingly observed at night. This indicates the potential that a larger eruption is imminent."
The airport on Lombok island – also a popular tourist destination east of Bali – has been closed since Sunday afternoon as the ash from Mount Agung headed into that direction, but it re-opened early on Monday.
The Australian government put out a travel advisory on Sunday instructing travellers to exercise a high degree of caution in Indonesia. Agung rumbled back to life in September and authorities raised the alert to the highest level, forcing 140 000 people living nearby to evacuate.
The volcano's activity decreased in late October and many people returned to their homes as the alert was lowered to the second-highest level.
Keep an eye out for updates on Mount Agung, Bali.