Hundreds Evacuated as Indonesia Raises Mount Semeru to Highest Alert

Authorities say flight routes between Indonesia and Australia could be affected, as ash plumes rise from one of Java’s most active volcanic peaks.

A man looks at a pyroclastic flow during the eruption of Mount Semeru in Lumajang, East Java, Indonesia, on Nov. 19, 2025. Agus Harianto/AFP via Getty Images

The status of volcanic activity on Mount Semeru in East Java has been raised to a level four alert—the highest danger category—shortly after it erupted on Nov. 19, around 8 p.m.

Authorities ordered evacuations across three villages in two districts—Supit Urang and Oro-Oro Ombo in Pronojiwo District, and Penanggal in Candipuro District—within Lumajang Regency.

Local disaster agencies evacuated around 300 residents.

The Indonesian government has declared a seven-day state of emergency, instructing officials to assess the impact, including potential casualties, displacement, and infrastructure damage.

Hot clouds travelled less than 13 km, according to Indonesia’s Center for Volcanology and Geological Disaster Mitigation (PVMBG).

Residents were warned against visiting certain parts of the region, including some river banks, due to potential lava flow, and to stay at least eight kilometres from the volcano due to potential stone expulsion.

The incident prompted a warning from the Bureau of Meteorology in case of possible delays in flights between Denpasar and Australia, although at the time of publication, no rerouting or cancellations had been confirmed.

A Major Volcano in a Highly Active Region

Mount Semeru, locally known as Mahameru, is one of Indonesia’s most active and closely monitored volcanoes.

It rises over 3,600 metres in height and produces frequent eruptions, often sending ash columns into the atmosphere and triggering lava flows along its southern slopes.

Indonesia’s volcanology agency regularly issues alerts for nearby communities, and aviation warnings are common when ash clouds drift into regional flight paths.

Semeru’s eruptions are part of the powerful tectonic activity of the Sunda Arc, which makes Indonesia one of the most volcanically active regions in the world, with around 130 active volcanoes.

One of the most recent confirmed eruptions was on July 18, when the volcano erupted five times in a day and sent ash columns around 700 metres above its summit.