Monsoon rains eroded and eventually collapsed the lava dome atop 12,060-foot (3,676-meter) Mount Semeru, causing the eruption, according to National Disaster Management Agency spokesman Abdul Muhari, citing information from Vulcanology and Geological Hazard Mitigation Agency at the Energy and Mineral Ministry of Resources.
Several villages were covered in ash that blotted out the sun, but no fatalities were reported. Thick columns of ash were detonated more than 1,500 meters into the sky, as incandescent gas and lava flowed down the slopes of Semeru, traveling towards a nearby river. People were advised to stay 5 kilometers (3.1 miles) from the crater mouth and keep away from the southeastern sector area along the Besuk Kobokan River located about 13 kilometers (8 miles) from the crater.
