KVERT reported that a Strombolian eruption at Klyuchevskoy continued during 2-9 September. Volcanic bombs that were ejected above the summit crater and the cinder cone landed in the Apakhonchich drainage on the E flank. A lava flow traveled down the Apakhonchich drainage and also down the SW flank. Satellite images showed a large and bright daily thermal anomaly at the volcano.

At 0943 and 1443 on 7 September explosions generated ash plumes that rose to altitudes of 6.5-7.5 km (21,300-24,600 ft) a.s.l. and drifted as far as 75 km SSW and ESE. The Aviation Color Code was raised to Red (the highest level on a four-color scale), and then lowered back to Orange within a few hours. Explosions at 1804 on 7 September produced ash plumes that rose as high as 7 km (23,000 ft) a.s.l. and drifted 45 km NE. At 0034, 0758, 1341, and 1850 on 8 September explosions generated ash plumes that rose to altitudes of 7-7.5 km (23,000-24,600 ft) a.s.l. and drifted as far as 145 km NE, NW, W, and SW. Ash plumes from explosions on 9 September did not go as high, rising to altitudes of 3-5 km (10,000-16,400 ft) a.s.l. and drifting 315-535 km SW. Minor ash deposits at Koryaksky and Avachinsky volcanoes were detected during 2100-2140; ash plumes continued to drift and dissipate over the Avachinsky bay.

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)