Indonesia has raised the alert level for Mount Semeru, the highest volcano on Java island, to its highest after a series of eruptions sent clouds of hot ash and pyroclastic flows down its slopes. The volcano in East Java province erupted multiple times from midday to dusk on Wednesday, prompting authorities to evacuate more than 300 residents from the three most at-risk villages in Lumajang district.
The country's Geology Agency said the eruptions produced searing clouds of hot ash and a mixture of rock, lava and gas that travelled up to 7km down the slopes. A thick column of hot ash rose 2km into the air. The alert level was raised twice, from the third-highest to the highest.
No casualties have been reported, authorities said. The danger zone has been widened to 8km from the crater, and people have been advised to stay away from the Besuk Kobokan River path due to lava flows.
Local media reported that about 178 people, including 137 climbers, were stranded at the Ranu Kumbolo monitoring post on the mountain. However, the spokesperson for the Bromo-Tengger-Semeru national park, Endrip Wahyutama, confirmed they were safe and not in the path of the hot cloud flow. Bad weather and rain forced them to remain overnight.
Social media videos showed a dense ash cloud sweeping through a forested valley, with residents fleeing to shelters. Semeru, also known as Mahameru, has erupted numerous times over the past 200 years. Its last major eruption in December 2021 killed 51 people and forced thousands to evacuate.
