KVERT reported on 8 November that the number and energy of shallow earthquakes below Avachinsky increased during the previous month. A weak thermal anomaly near the volcano's summit was visible on satellite imagery on 7 November. KVERT reported that based on these changes the possibility of sudden ash explosions at Avachinsky had increased, so the Concern Color Code was raised from Green to Yellow on 8 November.

Geological Summary. Avachinsky, one of Kamchatka's most active volcanoes, rises above Petropavlovsk, Kamchatka's largest city. It began to form during the middle or late Pleistocene, and is flanked to the SE by Kozelsky volcano, which has a large crater breached to the NE. A large collapse scarp open to the SW was created when a major debris avalanche about 30,000-40,000 years ago buried an area of about 500 km2 to the south, underlying the city of Petropavlovsk. Reconstruction of the volcano took place in two stages, the first of which began about 18,000 years before present (BP), and the second 7,000 years BP. Most eruptions have been explosive, with pyroclastic flows and hot lahars being directed primarily to the SW by the collapse scarp, although there have also been relatively short lava flows. The frequent historical eruptions have been similar in style and magnitude to previous Holocene eruptions.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)