Mount Semeru Erupts in Indonesia

Mount Semeru, located in Indonesia’s East Java province, experienced a series of eruptions on April 6, 2026, resulting in thick ash plumes and the establishment of expanded exclusion zones to protect the public from volcanic hazards.

According to the Center for Volcanology and Geological Hazard Mitigation, the volcano erupted several times on Monday morning. These events sent ash columns, ranging in color from white to gray, to heights of up to 1,100 meters above the summit.

An official at the Semeru monitoring post reported that the ash columns moved southward with moderate intensity. By the time of the report, the volcano had recorded at least seven eruptions since midnight on April 6.

The volcanic activity began at 00:38 a.m. Local time. The peak of this activity occurred at 6:51 a.m., when the ash plume reached its maximum height of 1,100 meters. The most recent blast was recorded at 9:29 a.m.

Safety Zones and Public Warnings

Authorities have issued warnings for the public to remain outside a 5-kilometer radius of the summit. In the southeastern sector, the exclusion zone is more extensive, extending 13 kilometers along the Besuk Kobokan river.

Further warnings have been issued regarding the potential for pyroclastic flows and lahars, which officials state could reach up to 17 kilometers from the peak.

Previous Volcanic Activity

This recent activity follows an eruption on March 10, 2026. During that event, Mount Semeru erupted on a Tuesday evening, sending an ash column approximately 1,000 meters above its summit.

The March 10 eruption produced a hot avalanche cloud that traveled approximately three kilometers to the southeast along the Besuk Kobokan river channel. Monitoring officials noted that thick gray ash drifted toward the northeast and east during that event.

The eruption on March 10 lasted nearly five minutes, with a maximum seismic amplitude of 12 mm. At that time, authorities had similarly urged residents to avoid the area within a five-kilometer radius of the crater and the southeastern sector along the Besuk Kobokan river channel up to 13 kilometers from the summit due to risks of lava avalanches, pyroclastic flows, and lahars.