Based on Tokyo VAAC data and satellite images, KVERT reported that at 1330 on 10 October an ash plume from Sarychev Peak rose to 1.7-2 km (5,600-6,600 ft) a.s.l. and drifted 95 km E. SVERT reported that on 15 October an ash plume rose 2.1 km (7,000 ft) a.s.l. and drifted 65-70 km E. The Aviation Color Code remained at Orange.

Geological Summary. Sarychev Peak, one of the most active volcanoes of the Kuril Islands, occupies the NW end of Matua Island in the central Kuriles. The andesitic central cone was constructed within a 3-3.5-km-wide caldera, whose rim is exposed only on the SW side. A dramatic 250-m-wide, very steep-walled crater with a jagged rim caps the volcano. The substantially higher SE rim forms the 1496 m high point of the island. Fresh-looking lava flows, prior to activity in 2009, had descended in all directions, often forming capes along the coast. Much of the lower-angle outer flanks of the volcano are overlain by pyroclastic-flow deposits. Eruptions have been recorded since the 1760s and include both quiet lava effusion and violent explosions. Large eruptions in 1946 and 2009 produced pyroclastic flows that reached the sea.

Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Sakhalin Volcanic Eruption Response Team (SVERT)