Overview
- The volcano produced a dense ash column about 3.5 km high when it erupted on Monday, a blast recorded on seismograms with a maximum amplitude of roughly 120 mm and a duration of about one hour.
- Authorities raised the alert level to 'Watch' and expanded safety zones—earlier prohibitions of 3 km and a 4.5 km sector were widened and some advisories reference up to 6 km from the summit.
- There were no immediate reports of deaths, mass evacuations or flight disruptions, but ash coated roads, vehicles and buildings in nearby Karo regency and local officials handed out masks.
- Officials and volcanologists warned people living near rivers that heavy rain could carry volcanic material downstream as lahars, and said a larger eruption remains possible so monitoring will continue.
- Sinabung has been active since 2010 with major eruptions in 2013–2014 and a deadly 2016 event, and repeated activity has forced about 30,000 people from their homes in recent years.