Activity at Shiveluch continued above background levels during 12-19 January, with over 160 shallow earthquakes occurring daily. Based on seismic interpretation, ash plumes rose to 6.5 km (21,300 ft) a.s.l. and avalanches occurred throughout the reporting period. According to observation and video data, gas-and-ash plumes rose to an altitude of 3.5 km (11,500 ft) a.s.l. on 16 January. Plumes drifted SW, NW, and NE on 12 and 14-18 January. A large thermal anomaly over the dome was noted. Based on satellite imagery, the Tokyo VAAC reported that ash plumes rose to an altitude of 6.1 km (20,000 ft) a.s.l. on 22 and 23 January and drifted NW.

Geological Summary. The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1,300 km3 andesitic volcano is one of Kamchatka's largest and most active volcanic structures, with at least 60 large eruptions during the Holocene. The summit of roughly 65,000-year-old Stary Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera breached to the south. Many lava domes occur on its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large open caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. Widespread tephra layers from these eruptions have provided valuable time markers for dating volcanic events in Kamchatka. Frequent collapses of dome complexes, most recently in 1964, have produced debris avalanches whose deposits cover much of the floor of the breached caldera.

Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Tokyo Volcanic Ash Advisory Center (VAAC)