JAKARTA – Indonesia’s Ruang volcano spewed explosive incandescent lava towards the night sky on April 30 as lightning flashes lit up its crater, prompting the authorities to raise the alert status and warn of a possible tsunami.

The country’s Centre for Volcanology and Geological Hazard Mitigation warned residents living on Tagulandang, the island closest to the volcano, that a tsunami could be triggered by volcanic material collapsing into the ocean.

The warning was issued on the morning of April 30, with an official from the centre Hetty Triastuty saying it remained in place in the afternoon.

The agency raised the alert status of Ruang to the highest level following the early morning eruption, urging residents not to go near the volcano.

The April 30 eruption follows a series of eruptions earlier in April that forced hundreds to evacuate, and the airport in the provincial capital of Manado to close.

That eruption also caused damage to some homes. At the time, a warning was also issued about the potential for a tsunami.

Footage shared by Indonesia’s disaster mitigation agency showed lightning flashing above Ruang’s crater, as lava and rocks were projected into the air and rained down around the island.

The agency said the eruption column reached 5km high, and urged any remaining residents within a 7km, previously 6km, radius to immediately evacuate, warning of possible further “explosive eruptions”.

Ruang island is about 100km from Manado, the capital of North Sulawesi province in the north-central region of the sprawling Indonesian archipelago. It is home to more than 800 residents, most of whom were evacuated following the recent eruptions.

The eruption corresponded with a spike in seismic activity and deep volcanic earthquakes, the disaster agency said.

The authorities closed Manado’s Sam Ratulangi airport again on April 30, citing the possible spread of volcanic ash, the airport operator said in an Instagram post.

The airport will remain closed until noon on May 1, the transport ministry said.

The authorities downgraded the status level to level three last week before bumping it up again to level four on April 30.

Indonesia straddles the so-called Pacific “Ring of Fire”, an area of high seismic activity where multiple tectonic plates meet. REUTERS