British News Agency

Mount Ruang, a 725-meter volcano on Ruang Island in North Sulawesi, has erupted at least five times since Tuesday night, spewing clouds of fiery lava and ash thousands of meters into the sky, the country's volcanological agency said.

The agency's chief, Hendra Gunawan, said authorities had raised the volcano alert to the highest level and warned people not to come within 6 kilometres of the summit due to concerns that Mount Ruang could partially collapse into the water and cause a tsunami.

"The power of Mount Ruang's eruption is growing and releasing hot clouds about 1.7 kilometres high," Hendra Gunawan told national news agency Antara, adding that recent regional earthquakes triggered the eruptions.

Mount Ruang is a stratovolcano, typically conical, with relatively steep sides due to the formation of viscous, sticky lava that does not flow easily. According to volcanologists, stratovolcanoes usually produce eruptions due to gas accumulation in magma.

Dramatic footage of Wednesday's eruptions showed grey ash clouds and glowing lava flows rising skyward, accompanied by lightning strikes. The images also show that the villagers were evacuated.

According to officials, Ruang Island is home to about 800 residents who have temporarily moved to neighboring Tagulandang Island. Officials warned that people in Tagulandang should be careful of falling incandescent rocks and hot cloud billows.

No casualties were reported.