The volatile stratovolcano erupts twice in under five hours, sending ash 18 km into the sky and prompting new alerts and evacuations.

Mount Lewotobi Laki‑laki erupted twice within hours over the weekend, launching ash columns as high as 18 kilometres and coating nearby villages in thick volcanic debris. The double eruption marks one of Indonesia’s most powerful volcanic events in recent years — and one that has reignited concerns across the region.

The first eruption occurred late Friday evening, with fiery lava lighting up the sky and ash soaring 10 km high. Not long after, an early Saturday morning blast launched volcanic material even higher into the stratosphere. Despite the dramatic displays, no casualties were immediately reported.

Indonesia’s Geology Agency confirmed that pyroclastic flows — deadly fast-moving clouds of hot gas, rock, and ash — cascaded up to 5 km down the volcano’s slopes. Drone surveillance revealed deep magma movement beneath the surface, and tremors from the activity were picked up by regional seismic sensors. Volcanic gravel, some the size of a thumb, was reportedly hurled up to 8 km from the crater.

Villages near the base of the mountain were quickly coated in ash, with local authorities warning residents to be on high alert for heavy rain, which could trigger lahars — destructive mudflows formed when volcanic ash and debris mix with water.

Saturday’s event ranks among Indonesia’s most intense eruptions since Mount Merapi’s deadly blast in 2010, which killed more than 350 people on the densely populated island of Java.

Lewotobi Laki‑laki is part of a twin-volcano complex located at the southeastern tip of Flores Island in Indonesia’s East Nusa Tenggara province. It stands at 1,584 metres and is the more active of the two peaks, the other being Lewotobi Perempuan.

Indonesia sits along the Pacific Ring of Fire — a horseshoe-shaped zone notorious for earthquakes and volcanic eruptions. The country is home to around 120 active volcanoes and sees regular tectonic activity.

This latest series of eruptions is the most powerful seen at Lewotobi since it entered an active phase last year. The volcano has been at the highest alert level since June 18, with authorities maintaining an exclusion zone around the crater, recently expanded to a 7 km radius.

Just weeks earlier, on July 7, an eruption at the same volcano forced the cancellation or delay of numerous flights at Bali’s Ngurah Rai International Airport and left surrounding areas covered in thick ash and volcanic mud.

The Indonesian government has already relocated thousands of residents following multiple eruptions at Lewotobi since late 2024. A particularly destructive event in November claimed nine lives and damaged thousands of homes.

According to the Geology Agency, Saturday’s eruption ejected volcanic gases and ash that are likely to affect air quality and aviation in the region. No-fly advisories were issued for nearby airspace, and regional disaster authorities are monitoring conditions closely.

Geologists note that Lewotobi’s magma is andesitic in composition, which typically produces explosive eruptions and high ash plumes. While some volcanoes release basaltic magma with quieter lava flows, Lewotobi’s profile makes it especially prone to dramatic and hazardous activity.

Residents in downstream areas have been advised to stay clear of rivers and valleys connected to the volcano, as lahars can travel quickly and unpredictably during and after rainfall. Relief teams are on standby, and temporary shelters remain in place for those evacuated.

While Saturday’s event caused no immediate loss of life, officials have made it clear that the danger is far from over. Volcanic activity remains high, and seismic readings suggest more eruptions are possible in the coming days or weeks.

Whether this marks the peak or just the beginning of a new cycle of activity remains to be seen — but if Lewotobi’s recent behaviour is any indication, it’s not going quiet anytime soon.