KVERT reported that the Strombolian eruption at Klyuchevskoy continued during 11-16 October and fed lava flows the descended the Apakhonchichsky drainage on the SE flank. Activity was notable during 11-12 October, characterized by the presence of ash in gas-and-steam plumes and an increase in the lava effusion rate. KVERT raised the Aviation Color Code to Orange (the third level on a four-color scale) as a result. According to observers at the Kamchatka Volcanological Station, lava effusion was almost continuous and incandescent material was ejected as high as 300 m above the crater rim. On 16 October lava on the SE flank melted snow and ice, causing phreatic explosions and large collapses of material from the margins of the flow. Dates and times are in UTC; specific events are in local time where noted.

Geological Summary. Klyuchevskoy (also spelled Kliuchevskoi) is Kamchatka's highest and most active volcano. Since its origin about 6000 years ago, the beautifully symmetrical, 4835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of sharp-peaked Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during the past roughly 3000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 m and 3600 m elevation. The morphology of the 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters.

Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Kamchatka Volcanological Station