Gunung Semeru erupts twice as tremor activity dominates

On Thursday 23 July 2026, Indonesia’s highest volcano, Gunung Semeru, erupted twice, first at 00:29 WIB and again at 05:48 WIB. No visible plume was reported, but volcanic tremors continued to dominate the activity. Monitoring stations recorded 19 eruption tremors between midnight and 06:00 WIB, each with amplitudes of 13‑22 mm, and the previous day saw 77 such tremors.

In the same 24‑hour period the volcano produced seven embusan tremors (3‑6 mm), a single harmonic tremor (7 mm), a distant tectonic tremor (18 mm), six rock‑fall tremors and twelve additional embusan events. The alert remains at Level III (Siaga). Authorities have prohibited any activity within a five‑kilometre radius of the crater and along river valleys up to 13 km from the summit because of the risk of hot ash clouds, lava flows and lahars.

The ongoing seismic activity is being closely monitored to assess further hazards for nearby communities.