Authorities in Indonesia have issued a tsunami alert after a volcano erupted several times in the province of North Sulawesi, spewing a column of smoke more than a mile into the sky and forcing the evacuation of hundreds of people from their homes.
Mount Ruang, a stratovolcano, first erupted at 9.45pm local time on Tuesday and then four times on Wednesday, Indonesia’s volcanology agency said.
Officials worry that part of the volcano could collapse into the sea and cause a tsunami, as happened in 1871. Tagulandang island to the volcano’s north-east is again at risk, and its residents are among those being told to evacuate.
The alert level for the volcano, which has a peak of 725 metres above sea level, was raised on Wednesday evening from three to four, the highest level in the four-tiered system.
“Based on the result of visual and instrumental observation that showed an increase in volcanic activity, Mount Ruang’s level was raised from level three to level four,” Hendra Gunawan, the head of Indonesia’s volcanology agency, said in a statement.
Authorities widened a 4km exclusion zone around the crater to 6km on Wednesday evening.
There were no reports of deaths or injuries, but more than 800 people were evacuated from two Ruang Island villages to nearby Tagulandang Island, located more than 60 miles north of the provincial capital, Manado, the state agency Antara reported.
The volcanology agency said residents of Tagulandang must be evacuated outside the 6km radius by Wednesday evening.
Indonesia’s national disaster mitigation agency said residents would be relocated to Manado, the nearest city, on Sulawesi island, a journey of six hours by boat.
In 2018 the eruption of Indonesia’s Anak Krakatau volcano caused a tsunami along the coasts of Sumatra and Java after parts of the mountain fell into the ocean, killing 430 people.
In a statement, Gunawan told people to “be on alert for the potential ejection of rocks, hot cloud discharges and tsunami caused by the collapse of the volcano’s body into the sea”.
Ruang’s initial eruption on Tuesday evening pushed a column of ash 1.2 miles into the sky, with the second eruption pushing it to 1.5 miles, Muhammad Wafid, the head of the geological agency, said in a statement.
The volcanology agency said on Tuesday that volcanic activity had increased at Ruang after two earthquakes in recent weeks.
Indonesia, a vast country of archipelagos, sees frequent seismic and volcanic activity due to its position on the Pacific’s Ring of Fire, an arc where tectonic plates collide, which stretches from Japan through south-east Asia and across the Pacific basin.