Indonesian authorities have raised the alert level for Mount Lokon in Tomohon, North Sulawesi to waspada (Level II) on Monday, November 5, 2017, amid increased volcanic activity detected under the volcano.
Residents and visitors are prohibited from coming within 1.5 km (0.93 miles) from the crater on Monday, after increased seismic activity marked by tremors since Thursday, November 2, 2017.
"The tremors from Mt. Lokon suggest that gas and magma are migrating, which means pressure has been accumulating," state volcanologist Farid said.
The intense seismic activity could be followed by an eruption, although when this would happen could not be predicted, Farid said, as reported by the Jakarta Post.
"We will keep monitoring the volcano and wait for developments. We hope the increased activity will not continue," he added.
Mando Manguleh, an official at the Tomohon branch of the Center for Volcanology and Geological Hazard Mitigation (PVMBG), said his office had recorded five small earthquakes since Thursday.
The twin volcanoes Lokon and Empung, rising about 800 m above the plain of Tondano, are among the most active volcanoes of Sulawesi. Lokon, the higher of the two peaks (whose summits are only 2.2 km / 1.3 miles apart), has a flat, craterless top.
The morphologically younger Empung volcano has a 400-m-wide (1 312 feet), 150-m-deep (492 feet) crater that erupted last in the 18th century, but all subsequent eruptions have originated from Tompaluan, a 150 x 250 m (492 x 820 feet) wide double crater situated in the saddle between the two peaks.
Historical eruptions have primarily produced small-to-moderate ash plumes that have occasionally damaged croplands and houses, but lava-dome growth and pyroclastic flows have also occurred. (GVP)
Featured image: Mount Lokon, Indonesia. Credit: Ariefrahman