Local news reported, "hot clouds" and incandescent material from Merapi travelling a distance of 1 km SE down the Gendol River on 23 May. People in the nearby village of Muntilan, about 16 km W, told about "hot clouds" & ashfall.
Based on a Significant Meteorological Information (SIGMET) advisory and satellite image observations, the Buenos Aires VAAC reported that ash plumes from Llaima rose to altitudes of 3-4.3 km (10,000-14,000 ft) a.s.l. on 26 May. The plumes were visible on satellite imagery drifting E. On 28 May, a pilot reported that an ash plume rose to 5.5-6.7 km (18,000-22,000 ft) a.s.l. and drifted E.
8-25 May: Seismic activity at Kliuchevskoi continued above background levels and a thermal anomaly in the crater was detected on satellite imagery....more [read all]
Scientists from PHIVOLCS conducted an aerial investigation of Bulusan and discovered lahar deposits and three steaming fissures. Scientists also observed steam plumes that rose to altitudes of 1.6-1.7 km.
INGEMMET reported that during 16-17 May, ash and gas plumes from Ubinas rose to altitudes of 5.8-7.7 km (19,000-25,300 ft) a.s.l. and drifted SW, SE, and E.Based on pilot reports and satellite imagery, the Buenos Aires VAAC reported that continuous emissions produced ash plumes that rose to altitudes of 5.6-9.1km (18,000-30,000 ft) a.s.l. during 17 and 19-22 May. Plumes drifted ESE, SE,and E.
During 15-22 May, IG reported that ash plumes intermittently visible from Tungurahua rose to altitudes of 5.1-7 km (16,700-23,000 ft) a.s.l. and drifted mainly W, NW, and E. Ashfall was reported from areas SW and W during 16-17 May, SW on 19 May, and W and NW during 20-21 May. Lahars and muddy waters traveled down W, NW, and N ravines during 15 and 17-19 May and caused the road to Bañosto close on 18 May. Lahars that traveled in the Bilbao sector and down NW ravines on 20 May blocked the Baños-Penipe highway and obstructed the route between Ambato and Baños for about 6 hours. Muddy waters traveled down ravinesto the N.
Data from deformation-monitoring instruments indicated that during 16-22 May lava-dome growth at Mount St. Helens continued. Seismicity persisted at low levels, punctuated by M 1.5-2.5, and occasionally larger, earthquakes. In some instances, clouds inhibited visual observations.
Based on visual observations, MVO reported that during 11-21 May lava-domegrowth at Soufrière Hills likely ceased and the overall structure of the dome changed very little. Low-level rockfall and pyroclastic flow activity continued. Seismic activity was very low. The Alert Level remained at 4 (on a scale of 0-5).
KVERT reported that seismic activity at Shiveluch continued above backgroundlevels during 11-18 May. Based on seismic interpretation, ash plumes possibly rose to an altitude of 6 km (19,700 ft) a.s.l. throughout the reporting period.A large thermal anomaly was visible on satellite imagery. The Level of Concern Color Code remained at Orange.
Based on information from JMA and a pilot report, the Tokyo VAAC reported that ash plumes from Sakura-jima rose to altitudes of 1.2-2.7 km (4,000-9,000 ft) a.s.l. during 16 and 20-22 May. Plumes drifted NW on 16 May and rose straight up during 20-22 May.