The Semeru, or Mount Semeru volcano erupted on Indonesia’s Java island killing at least one person and injuring dozens others.
Pictures showed giant ash clouds coming from Mt Semeru. Witnesses reported villages covered in debris, and thick smoke blocking the Sun, leaving them in pitch darkness.
The deputy chief of Lumajang district put the number of injured at 41, saying they had suffered burns.
Indah Masdar called for helicopters to help rescue at least 10 people trapped in buildings.
“We’re in big distress,” she said.
“It’s harrowing, their families are all crying.”
Indonesia’s disaster mitigation agency (BNPB) later said it knew of 35 people being treated at local medical facilities.
Evacuation efforts have been hampered by choking smoke, a power blackout, and rainstorms during the eruption which turned the debris into mud.
Several hundred people have been moved to shelters or to safer areas. The officials set up a restricted zone within 5km from the crater. Airlines have been warned of an ash cloud rising up to 15,000m.
The Volcanic Ash Advisory Center (VAAC) in Darwin, Australia said the ash appeared to have detached from the summit and was drifting south-west over the Indian Ocean.
The VAAC provides advice to the aviation industry about the location and movement of potentially hazardous volcanic ash.
Ash that solidifies on cooler parts of plane engines can disrupt airflow, which can lead to engines stalling or failing completely.
It also affects visibility for the pilots and can affect air quality in the cabin – making oxygen masks a necessity.
Mt Semeru was quite an active volcano that regularly spewed ash up to about 4,300m, so Saturday’s eruption was a “pretty significant increase in intensity”, Mr Biggs said.
Mt Semeru rises 3,676m above sea level and erupted last December, forcing thousands of residents to seek shelter.
It is among Indonesia’s nearly 130 active volcanoes.
Indonesia is on the Pacific “Ring of Fire” where continental plates meet, causing frequent volcanic and seismic activity.
BREAKING 🚨 Massive Mount Semeru eruption in Indonesia makes terrified locals flee pic.twitter.com/YgN6j6tkrg
— Insider Paper (@TheInsiderPaper) December 4, 2021