Overview
- Darwin VAAC confirmed an ash column reaching about 16.5 km (54,000 ft) with a red aviation advisory in effect.
- Indonesia’s geology agency elevated Semeru to the highest alert level as eruptive activity and ash emissions persisted.
- Pyroclastic density currents moved through the Besuk Kobokan drainage; observation posts reported runouts around 7 km, with later accounts suggesting some pulses may have reached farther under assessment.
- Hazard rules include an 8 km exclusion along Besuk Kobokan, a 2.5 km summit radius, and a 500 m buffer from riverbanks beyond that due to risks from PDCs and lahars.
- Local disaster teams evacuated residents from Lumajang-area communities, ashfall covered nearby villages, and early reports noted no confirmed casualties.