East Java’s Mount Semeru Erupts Nine Times with Ash Rising 1,000 Meters

RRI.CO.ID, Lumajang - Volcanic activity at Mount Semeru in East Java intensified again on Saturday, April 4, 2026, prompting heightened vigilance among nearby communities.

Within a few hours that morning, Java’s highest peak recorded nine eruptions, with ash columns rising as high as 1,000 meters above the summit. Officials said the series of eruptions reflected highly dynamic magma activity.

“The strongest eruption was recorded at 5:19 a.m. local time, with an ash column reaching about 1,000 meters above the summit, marking the eighth eruption,” reported Liswanto, an officer at the Mount Semeru Observation Post, as reported by Antara.

The ninth eruption followed at 6:22 a.m., producing a 700-meter ash column, or 4,376 meters above sea level.

He noted that the ash plume was gray and dense, drifting westward. Seismographs recorded a maximum amplitude of 22 millimeters and a duration of 141 seconds. Between midnight and 6 a.m., Semeru registered 17 eruption-related tremors, with amplitudes ranging from 12 to 22 millimeters and durations of 56 to 112 seconds.

The Center for Volcanology and Geological Hazard Mitigation (PVMBG) has maintained Semeru’s status at Level III, or Alert.

Authorities have designated hazard zones along the Besuk Kobokan stream, which is vulnerable to pyroclastic flows and lava. Residents are prohibited from conducting activities within a five-kilometer radius of the crater due to the risk of incandescent rock ejections.

Communities are also urged to remain cautious of pyroclastic flows, lava avalanches, and lahars along rivers and valleys originating at the summit, particularly Besuk Kobokan, Besuk Bang, Besuk Kembar, and Besuk Sat. Smaller tributaries of Besuk Kobokan also face lahar risks.

Officials emphasized that while eruptions are characteristic of Mount Semeru, the increased frequency and intensity demand strict preparedness. Both the government and the public are expected to continue monitoring developments and adhere to safety recommendations to minimize disaster risks. ***