The state-run Institute of Geology and Mines cautioned that Galeras, the country’s most active volcano, could erupt in a matter of days or weeks.
The mountain has produced five eruptions over the last two years.
Two eruptions within 24 hours during early June prompted nearly 8,000 nearby residents to flee their homes.
A comparable number of villagers were ordered to evacuate in February after Galeras expelled clouds of ash and steam.
Nevado del Huila volcano also remains unsettled, according to geologists. More than 1,000 tremors rumbled inside the mountain between October 21 and 27.
Ash from Huila has fallen on 17 nearby settlements in the Cauca, Valle and Huila departments in recent weeks.
Around 9,000 people living in the risk zones of the Galeras and Huila volcanos have ignored orders to evacuate the vicinity, national emergency services warned Tuesday.