CVGHM reported that pyroclastic flows and rockfall avalanches from Semeru detected by the seismic network declined in frequency during 22 May-3 June. On 22 May, four pyroclastic flows traveled a maximum distance of 2.5 km from the active crater. Visual observations of smaller rockfalls detected during the rest of the reporting period were inhibited by fog, but were observed to travel 200-300 m from the active crater. Based on visual observations and the decline in seismic activity, CVGHM lowered the Alert Level to 2 (on a scale of 1-4) on 5 June.
Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) – “Reports provided courtesy of the Smithsonian’s Global Volcanism Program and the US Geological Survey’s Volcano Hazards Program.”