Tsunami alert in Indonesia as Mount Ruang volcano erupts

Authorities in Indonesia issued a tsunami alert after a volcano in the North Sulawesi Province erupted multiple times, prompting the closure of a provincial airport.

Thousands have been asked to evacuate after Mount Ruang, located on the Ruang island about 100km from the provincial capital Manado, threw a fiery-red column of lava, incandescent rock and ash around 3km into the sky.

The stratovolcano first erupted at 9.45pm (local time) on Tuesday and then four times on Wednesday, according to Indonesia's volcanology agency. Purple flashes of lightning rent the sky above the erupting volcano, videos on social media showed.

Officials worry that part of the volcano could collapse into the sea and cause a tsunami amid fears of a repeat of the 1871 disaster.

"We're running, guys," said one witness who filmed the eruption while scrambling to evacuate. "We are escaping because the ash is coming close."

The alert level for the volcano was raised to the highest on Wednesday evening. "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,” said Hendra Gunawan, the head of Indonesia’s volcanology agency.

Authorities have prohibited activities within a 6km distance from the crater and the island was no longer considered safe.

So far there have been no reports of any deaths or injuries but more than 800 people were evacuated from two villages to a nearby island. Tagulandang Island to the volcano's northeast is again at risk, and its residents are among those being told to evacuate.

Indonesia's National Disaster Mitigation Agency said residents will be relocated to Manado, the nearest city, on Sulawesi Island, a journey of six hours by boat.

About 1,500 of those in high-risk areas needed to be immediately evacuated, authorities said, while almost 12,000 more stand to be affected.

The airport in the provincial capital of Manado was shut on Wednesday to protect against the showers of ash from the eruption. Budget airline Air Asia canceled flights with nine airports in East Malaysia and Brunei after aviation authorities warned of a safety threat.

Indonesia is located on the “Pacific Ring of Fire” and has 142 volcanoes. The country has the largest global population living close to a volcano, with around 8.6 million Indonesians residing within 10km of a volcano.

Thousands of people were earlier forced to evacuate after the country’s most active volcano, Mount Merapi, erupted in January.

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.

Additional reporting by agencies