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 is the highest and most active volcano on the Kamchatka Peninsula. Since its origin about 6,000 years ago, this symmetrical, basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during approximately the past 3,000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 and 3,600 m elevation. Eruptions recorded since the late 17th century have resulted in frequent changes to the morphology of the 700-m-wide summit crater. These eruptions over the past 400 years 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)