RRI.CO.ID, Lumajang – Residents near Indonesia's tallest volcano are on high alert after Mount Semeru, straddling Lumajang and Malang Regencies in East Java, erupted five times on Friday morning, May 8, 2026. Ash columns from the eruptions soared up to 1.2 kilometers above the summit.

The first eruption struck at 12:39 a.m. Jakarta time, followed by another at 12:52 a.m., both with unobserved visuals and activity ongoing at the time of reporting. The third blast occurred at 5:21 a.m. Jakarta time, producing a 1.2 km ash column that reached 4,876 meters above sea level.

The column drifted white to gray with medium intensity toward the northeast, according to an officer at the Semeru Observation Post, Liswanto, in a written report received in Lumajang.

A fourth eruption at 6:09 a.m. Jakarta time sent an ash column about 900 meters high (4,576 meters above sea level), white to gray with medium intensity heading north. The fifth came at 7:50 a.m., with a roughly 1 km column of thick gray ash directed north.

“Mount Semeru erupted again at 5:21 a.m. Jakarta time, with an observed eruption column height of 1.2 km above the summit, or 4,876 meters above sea level (masl), “ said Liswanto, as reported by Antara.

"Mount Semeru erupted again at 7:50 a.m. Jakarta time, with an observed eruption column height of approximately 1 km above the summit, and a thick gray ash column observed to the north," he added.

With volcanic activity at Level III (Alert) status, Liswanto advised the public to avoid the southeastern sector along Besuk Kobokan up to 13 km from the peak. Beyond that radius, activities are banned within 500 meters of the riverbanks along Besuk Kobokan due to risks of expanding hot clouds and lahars extending to 17 km.

"People are prohibited from carrying out activities within a 5 km radius of the crater/peak of Mount Semeru Volcano, due to the risk of being ejected incandescent rocks," he warned.

Communities should remain wary of hot ash clouds, lava avalanches, and lahars along rivers and valleys originating from the peak, particularly Besuk Kobokan, Besuk Bang, Besuk Kembar, and Besuk Sat. There is also a significant risk of secondary lahars in smaller tributaries branching from Besuk Kobokan. ***

Source: https://www.antaranews.com/berita/5559319/gunung-semeru-erupsi-lima-kali-dengan-tinggi-letusan-capai-12-km