There were no reports of injuries, but residents gathered in the streets to keep a cautious eye on the rumbling mountain.
Lokon roared to life last July after 20 years of slumber. It has since produced similar eruptions in October and December.
The mountain is located just a few miles from the North Sulawesi provincial capital of Manado.
Previous eruptions have created fertile conditions that now support thriving businesses for those who grow coffee and cloves on Lokon's slopes.
But recent activity has prompted officials to establish a two-mile exclusion zone around the summit crater.
Photo: Volcanology Survey of Indonesia.