Jakarta, Indonesia (CNN) -- Indonesian officials have gone on high alert and have started evacuations as they warily monitor Mount Merapi, a volatile volcano in central Java that might erupt at any time.
"The local government is coordinating to evacuate around 40,000 villagers to the pre-assigned shelters," Neulis Auliasari of the national disaster coordination board said Monday.
Seismic activity has intensified, signaling that an eruption is imminent, according to Indonesian volcanologists.
The 3,000-meter Merapi is famously unpredictable, though. A pyroclastic flow -- a fast-moving burst of blistering gases and rock fragments -- is a key concern.
One killed two people in 2006 and another killed more than 60 villagers in 1994. About 1,300 people died when Merapi erupted in 1930.