KVERT reported that during 11-18 March seismic data at Shiveluch indicated that possible ash plumes rose to altitudes of 3.8-8 km (12,500-26,200 ft) a.s.l. Satellite imagery showed ash plumes drifting 312 km W and NW on 10 and 16 March, and thermal anomalies on the lava dome during 12-13 and 15-16 March. According to ground-based observations, an ash plume rose to an altitude of 6.5 km (21,300 ft) a.s.l. on 16 March. The Aviation Color Code remained at Orange. The Tokyo VAAC reported that on 19 March a possible eruption detected in satellite imagery produced a plume that rose to an altitude of 4.6 km (15,000 ft) a.s.l. Subsequent notices that day stated that ash continued to be detected, and then dissipated.

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