EN.malanginspirasi.com – Mount Semeru erupted again on Friday afternoon, 15 May 2026, at 11:57 a.m. Western Indonesian Time (WIB). The eruption produced pyroclastic flows, although the height of the volcanic ash column and the slide distance of the hot clouds could not be observed visually because the summit was shrouded in thick fog.
Semeru Observation Post officer Mukdas Sofian reported that the eruption was recorded on a seismogram with a maximum amplitude of 22 millimetres and an earthquake duration of around 4 minutes and 10 seconds.
From early morning at 00:53 WIB until midday, the highest mountain on Java Island had already erupted at least six times. Visual observation of those earlier eruptions was also impossible due to foggy conditions.
Mount Semeru, located on the border of Lumajang and Malang Regencies in East Java, remains at Alert Level III (Siaga). The Center for Volcanology and Geological Hazard Mitigation (PVMBG) has issued strict safety recommendations for residents and visitors.
People are prohibited from conducting any activities in the southeastern sector along Besuk Kobokan up to a distance of 13 kilometres from the summit. Beyond that radius, residents are asked to stay at least 500 metres away from the riverbanks along Besuk Kobokan, as they could be affected by the expansion of pyroclastic flows and lava flows potentially reaching 17 kilometres from the peak.
In addition, a safe radius of five kilometres from the crater or summit has been established to avoid hazards from ejected incandescent rocks.
Officers are also urging vigilance against potential lahars in rivers originating at Semeru’s peak, especially Besuk Kobokan, Besuk Bang, Besuk Kembar, Besuk Sat, and their tributaries.
Volcanic activity at Mount Semeru has remained on a high trend throughout May 2026. In the week leading up to Friday morning, dozens of eruptions were recorded, with effusive and explosive patterns that frequently generated pyroclastic flows and volcanic ash. The persistent thick fog around the summit often hinders visual observation, so monitoring relies heavily on seismographic data and other instruments.
As of the writing of this report, there have been no reports of casualties or infrastructure damage from the afternoon’s eruption. However, local authorities continue to monitor developments and urge the public to remain calm but alert, and to follow instructions from field officers.
PVMBG will continue to update information on Semeru’s volcanic activity through the MAGMA Indonesia app and other official channels. Communities in high-risk areas are advised to always have evacuation plans ready should volcanic activity increase significantly.
