"So far the activity of Mount Agung remains high, the alert level is on level 4 - the highest", said Kasbani, head volcanologist at the centre who like many Indonesians has one name.
Officials at an evacuation centre in Klungkung district said 122,490 people had left their homes, taking refuge at almost 500 makeshift shelters or moving in with relatives.
Drone footage shot by Australia's ABC news network over the settlements dotting the lush, green paddy fields in the dangerzone backed up the reports, showing figures moving in and out of the buildings.
On February 18, 1963, local residents reported a loud explosion and smoke coming out of the mountain top.
He says more than 560 volcanic earthquakes were recorded on Monday, majority shallow.
It last erupted in 1963, spewing ash, gas, rock and miles of lava, killing more than 1,100 people and destroying numerous homes.
"Also the number of hoaxes on social media [about an eruption] adds to the level of fear felt by many people including people who live in safe zone".
"If my house is destroyed I don't know how to restart my life". Back then, there was no evacuation plan, people just "ran to save themselves", he said.
The mountain, about 70 kilometres to the northeast of the tourist hotspot of Kuta, is among more than 120 active volcanoes in Indonesia.
Numerous country's volcanoes show high levels of activity but it can be weeks or even months before an actual eruption.
The island attracts millions of tourists every year, many of them Australian.
"I am representing the Ministry of Transportation in expressing our deep concern and empathy to everyone being displaced from their homes due to the potential eruption of Mount Agung".
Both countries are evacuating amid fears of imminent volcanic eruptions and they urge several countries, including Australia and Singapore, to issue travel advisories.
The website said Indonesian authorities were on standby to divert flights in the event of an eruption.
The towering volcano's peak is the single highest point on the Pacific island of Bali, standing at 3,031 m (9,944 ft) tall.