During 8-15 February volcanism increased at Shiveluch and KVERT raised the Color Concern Code on 15 February from Yellow ("volcano is restless") to Orange ("volcano is in eruption or eruption may occur at any time"). During the report period seismicity was above background levels, thermal anomalies were visible on satellite imagery, and several gas-and-ash eruptions occurred. The highest rising gas-and-ash cloud was produced from an eruption on 14 February at 0835; it reached ~ 3 km above the volcano's dome. A short-lived eruption on 15 February at 1501 produced a gas-and-ash plume that rose to 2 km above the dome and pyroclastic flows that extended 2.5 km to the SE. During 1613-1725 the same day, a dense ash plume continuously rose to 2 km above the dome. The Tokyo VAAC received a report that an eruption on 19 February at 1443 produced an ash cloud that reached a height of ~6.7 km above the volcano and drifted to the ESE.

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)