SVERT and KVERT reported that moderate eruptive activity continued at Chirinkotan during 14-23 August, characterized by explosions and ash plumes that rose to 2.5-4.5 km (4,900-9,800 ft) a.s.l. and drifted as far as 125 km S, E, SE, and SW. At 1110 on 18 August an explosion produced an ash plume, 20 x 27 km in size, that rose to 2-3 km (6,600-9,800 ft) a.s.l. and drifted 7 km NE and as far as 100 km SE. An explosion at 0935 on 23 August rose to 1.5-2.5 km (4,900-8,200 ft) a.s.l. and drifted 8 km SW and later, as far as 126 km W. The Tokyo VAAC reported ash plumes to 2.7-4.9 km (9,000-16,000 ft) a.s.l. that drifted S, NE, and SW during 18 and 23 August. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Geological Summary. The small, mostly unvegetated 3-km-wide island of Chirinkotan occupies the far end of an E-W volcanic chain that extends nearly 50 km W of the central part of the main Kuril Islands arc. It is the emergent summit of a volcano that rises 3000 m from the floor of the Kuril Basin. A small 1-km-wide caldera about 300-400 m deep is open to the SW. Lava flows from a cone within the breached crater reached the shore of the island. Historical eruptions have been recorded since the 18th century. Lava flows were observed by the English fur trader Captain Snow in the 1880s.

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