Spokesman of the agency, Sutopo Nugroho, said Mount Agung has shown increased activity since last week.
Nugroho said the disaster prompted the government to warn people to stay away from an exclusion zone of 7.5 kilometres from the volcano’s crater.
“Over 11,000 residents around Mount Agung have sought refuge, hundreds of harmonic tremors have been detected,’’ Nugroho added.
The 3,030-metre Mount Agung last erupted in 1963 to 64, killing about 1,500 people.
The volcano is popular among local and foreign trekkers.
Indonesia sits on the Pacific Ring of Fire, an area known for frequent seismic upheavals and volcanic eruptions.
Report says the country is home to about 130 active volcanoes.