Indonesia volcano eruption sends deadly ash cloud over nearby town
Mount Semeru erupted Wednesday afternoon, sending a 54,000-foot-tall ash plume and a fast-moving pyroclastic flow that swept over a bridge and nearby homes.
Mt. Semeru erupted in East Java, Indonesia, on Nov. 19, launching volcanic ash up to 54,000 feet into the air and spewing pyroclastic flows, including one that engulfed this bridge as locals fled.
A powerful volcanic eruption in Indonesia sent residents fleeing as Mount Semeru released a towering ash column and pyroclastic flow — a fast-moving, superheated cloud of dense volcanic gas, ash and debris capable of destroying nearly everything in its path.
The eruption began around 4 p.m. local time on Wednesday in East Java, producing what officials described as a “dense and towering” volcanic column, according to Indonesia’s Semeru Observation Post.
A man looks at a pyroclastic flow during the eruption of Mount Semeru in Lumajang, East Java, on November 19, 2025. (Photo credit: AGUS HARIANTO/AFP via Getty Images)
Authorities raised the volcano’s alert level to its highest tier and urged residents to evacuate as activity continued into Wednesday evening.
Video from the scene shows a gray pyroclastic flow surging down the slopes of Semeru, quickly overtaking a bridge as people recording the event scrambled to safety.
According to the U.S. Geological Survey (USGS), a pyroclastic flow consists of extremely hot volcanic gases, ash and rock fragments that can reach temperatures of up to 1,500 degrees Fahrenheit and travel at speeds of tens of meters per second. These dense flows can obliterate, bury or sweep away nearly all structures and objects in their path.
A man looks at a pyroclastic flow during the eruption of Mount Semeru in Lumajang, East Java, on November 19, 2025. (Photo credit: AGUS HARIANTO/AFP via Getty Images)
One of the deadliest recorded pyroclastic flows occurred in 1902, when the eruption of Mount Pelée on the Caribbean island of Martinique killed nearly 30,000 people.
Indonesia sits along the Pacific Ring of Fire, a region of intense seismic and volcanic activity. Mount Semeru is one of nearly 130 active volcanoes across the island nation.
