KVERT reported that an explosive eruption at Chikurachki began at around 0310 on 16 October. A dense ash plume identified in satellite images rose to 4.5 km (14,800 ft) a.s.l. and drifted 240 km ESE. The Aviation Color Code was raised to Orange (the second highest level on a four-color scale). At 1011 and 1620 that same day ash plumes were visible in satellite images rising as high as 3.5 km (11,500 ft) a.s.l. and drifting ESE; by 1620 ash plumes from the eruption had extended as far as 523 km. KVERT noted that ash emissions were last seen at 0130 on 17 October and a thermal anomaly was visible at 0432. The Aviation Color Code was lowered to Yellow at 1223 on 18 October, and then to Green at 1428 on 19 October. Steam-and-gas emissions persisted. All times are local.

Geological Summary. Chikurachki, the highest volcano on Paramushir Island in the northern Kuriles, is a relatively small cone constructed on a high Pleistocene edifice. Oxidized basaltic-to-andesitic scoria deposits covering the upper part of the young cone give it a distinctive red color. Frequent basaltic Plinian eruptions have occurred during the Holocene. Lava flows have reached the sea and formed capes on the NW coast; several young lava flows are also present on the E flank beneath a scoria deposit. The Tatarinov group of six volcanic centers is located immediately to the south, and the Lomonosov cinder cone group, the source of an early Holocene lava flow that reached the saddle between it and Fuss Peak to the west, lies at the southern end of the N-S-trending Chikurachki-Tatarinov complex. In contrast to the frequently active Chikurachki, the Tatarinov centers are extensively modified by erosion and have a more complex structure. Tephrochronology gives evidence of an eruption around 1690 CE from Tatarinov, although its southern cone contains a sulfur-encrusted crater with fumaroles that were active along the margin of a crater lake until 1959.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)