More than 11,000 people have been told to evacuate and air travel in the region has been disrupted after a volcano in northern Indonesia erupted multiple times.

Mount Ruang, located in North Sulawesi Province, first erupted at 9:45pm (13:45 GMT) on Tuesday, sending billowing clouds of smoke and ash high into the sky.  After four more eruptions on Wednesday, Indonesia’s volcanology agency raised the alert level for the 725-metre (2,379-foot) high mountain to four, the highest on the scale.  They also widened the exclusion zone around the crater from four kilometres (2.5 miles) to six kilometres (3.7 miles).

More than 800 people were evacuated initially from Ruang to nearby Tagulandang Island, which is located more than 100 kilometres (62 miles) north of the provincial capital, Manado.

But officials said on Thursday morning that more people would need to be evacuated as a result of the widening exclusion zone, and would be taken to Manado.  “At least 11,615 residents who are in the risk area must evacuate to a safe place,” Abdul Muhari, the head of the disaster agency’s disaster data, communications and information centre was quoted as saying by the Kompas newspaper.

Officials also worry that part of the volcano could collapse into the sea and cause a tsunami as it did during a previous eruption in 1871.

Video footage showed flows of red lava streaming down the mountain, reflected in the waters below, and billowing clouds of grey ash above Ruang’s crater.

Muhammad Wafid, the head of Indonesia’s geological agency, earlier said Ruang’s initial eruption sent an ash column two kilometres (1.2 miles) into the sky, with the second eruption pushing it to 2.5 kilometres (1.6 miles).

Aviation authorities announced the closure of Sam Ratulangi International Airport in Manado until at least Thursday evening “due to the spread of volcanic ash which could endanger flight safety”. The airport has connections to countries including China, Singapore and South Korea.

There was also significant disruption to flights to and from Kota Kinabalu International Airport in neighbouring Malaysia. Kota Kinabalu is on the northern tip of Malaysian Borneo, just over 1,100 kilometres (688 miles) to the northwest of Ruang.

The volcanology agency said activity had increased at Ruang after two earthquakes in recent weeks.

Indonesia, which sits along the ‘Ring of Fire’, a horseshoe-shaped series of tectonic fault lines around the Pacific Ocean, has 120 active volcanoes.

In 2018, the eruption of Indonesia’s Anak Krakatoa volcano triggered a tsunami along the coasts of Sumatra and Java after parts of the mountain fell into the ocean. Hundreds of people were killed.

(Aljazeera)