SURABAYA, INDONESIA — Mount Semeru, the tallest and one of the most active volcanoes on Java Island, erupted several times on Wednesday, November 19, 2025. The powerful eruptions forced authorities to raise the volcanic alert to Level IV (Awas), the highest on Indonesia’s four-tier warning system.
The eruption sent hot ash clouds and volcanic gas high into the atmosphere and generated fast-moving pyroclastic flows that raced down the volcano's slopes.
Pyroclastic Flows Force Immediate Evacuations
According to Indonesia’s National Disaster Mitigation Agency (BNPB), the main eruption happened in the early afternoon, prompting urgent evacuation orders. The pyroclastic flows — scorching clouds of ash, gas, and rock — traveled as far as 7 kilometers (4.3 miles) from the crater. Ash plumes reached up to 13 kilometers (8 miles) into the sky, according to some estimates.
Officials raised the alert level twice during the day as volcanic activity intensified, including strong tremors recorded throughout the afternoon.
More than 300 residents in high-risk zones around Lumajang district were evacuated to emergency shelters. The government expanded the exclusion zone, warning people to stay at least 8 kilometers (5 miles) from the crater. They were also told to avoid the Besuk Kobokan riverbanks, which often serve as channels for lava and debris flows.
Fortunately, there were no immediate reports of injuries or fatalities.
Flights Continue Despite Eruption
Despite the severity of the eruption, flights at Ngurah Rai International Airport in Bali remained operational. However, Australia’s Volcanic Ash Advisory Centre (VAAC) issued a red-level aviation warning due to the high ash cloud and the potential risk to aircraft in the region.
Indonesia’s Volcanic Risk
Mount Semeru, located in East Java about 310 kilometers (192 miles) west of Bali, is part of the Pacific "Ring of Fire," a zone of frequent seismic and volcanic activity. Indonesia is home to nearly 130 active volcanoes, making it one of the most volcanically active nations in the world.
Semeru has a long history of deadly eruptions. In 2021, the volcano erupted with little warning, killing more than 50 people and forcing the evacuation of thousands.
For more cases related to natural disasters and volcanic eruptions, check out our video here:
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