Updates on volcanic activity (Smithsonian)
The Smithsonian/USGS Weekly Volcanic Activity Report provides information about global volcanism on a weekly basis. Latest Semeru report has been published on 29 Dec 2021 07:05.
PVMBG reported that the eruption at Semeru continued during 21-28 December. Crater incandescence was visible overnight during 22-23 December and four block avalanches traveled 800 m down the Kobokan drainage on the SE flank. Two pyroclastic flows descended the Kobokan drainage a maximum distance of 5 km. Dense gray plumes rose 500 m above the summit during 23-24 December and three avalanches of material traveled 500 m down the SE flank. At 1706 on 25 December and at 0902 on 28 December ash plumes rose 300 m above the summit and drifted SW and N, respectively. The Alert Level remained at 3 (on a scale of 1-4). The public was warned to stay at least 500 m away from Kobokan drainages within 17 km of the summit, and other drainages originating on Semeru including the Bang, Kembar, and Sat, due to lahar, avalanche, and pyroclastic flow hazards.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)
See the detail here