Based on visual observations, KVERT reported that on 17 September explosions at Zhupanovsky generated gas-and-steam plumes with small amounts of ash that rose to altitudes of 6-7 km (19,700-23,000 ft) a.s.l. and drifted 20 km SW. The Aviation Color Code was raised from Green to Orange, the second highest level on a 4-color scale. About 30 minutes later satellite images showed ash plumes drifting 10 km E. Later that day gas-and-steam plumes rose 4 km (13,100 ft) a.s.l. The Aviation Color Code was lowered to Yellow, and then on 20 September it was lowered to Green.

Geological Summary. The Zhupanovsky volcanic massif consists of four overlapping stratovolcanoes along a WNW-trending ridge. The elongated complex was constructed within a Pliocene-early Pleistocene caldera whose rim is exposed only on the eastern side. Three of the stratovolcanoes were built during the Pleistocene. An early Holocene stage of frequent moderate and weak eruptions from 7,000 to 5,000 years before present (BP) was followed by a period of infrequent larger eruptions that produced pyroclastic flows. The last major eruption took place about 800-900 BP. Recorded eruptions have consisted of relatively minor explosions from Priemysh, the third cone from the E about 2.5 km from the summit peak.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)