KVERT reported that the explosive Strombolian eruption at Klyuchevskoy continued during 24-31 August and a daily bright thermal anomaly was identified in satellite images. A plume of ash resuspended by strong winds drifted 95 km E at 3-3.5 km (10,000-11,500 ft) a.s.l., prompting KVERT to raise the Aviation Color Code to Orange (the third level on a four-color scale) at 1240 on 4 September, local time. By 1940 the plume had drifted as far as 170 km E, remining at the same altitudes; the Aviation Color Code was lowered back to Yellow at 1954 (local time). The Aviation Color Code was again raised to Orange for a few hours, during 1532-1808 local time on 5 September, due to plumes of resuspended ash drifting 120 km ENE. KVERT noted that Strombolian activity continued, feeding a lava flow that advanced down the Kozyrevsky drainage on the SW flank. Dates are based on UTC times; 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.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)