KVERT reported that during 9-16 July seismic activity from Gorely was above background levels, and gas-and-steam emissions rose from the crater most days. On 10 July, data suggested that the vent on the crater's inner NE wall, above the level of the lake, had grown by 2-3 times the original size. The lake level had also fallen. Analysis of satellite imagery showed a thermal anomaly over Gorely on 8, 10, 12, and 14 July, and gas-and-steam plumes that drifted 25-150 km SE, E, and S during 10 and 14-15 July. The Level of Aviation Color Code remained at Yellow.

Geological Summary. Gorely volcano consists of five small overlapping stratovolcanoes constructed along a WNW-ESE line within a large 9 x 13 km caldera. The caldera formed about 38,000-40,000 years ago accompanied by the eruption of about 100 km3 of tephra. The massive complex includes about 40 cinder cones, some of which contain acid or freshwater crater lakes; three major rift zones cut the complex. Another Holocene stratovolcano is located on the SW flank. Activity during the Holocene was characterized by frequent mild-to-moderate explosive eruptions along with a half dozen episodes of major lava extrusion. Early Holocene explosive activity, along with lava flows filled in much of the caldera. Quiescent periods became longer between 6,000 and 2,000 years ago, after which the activity was mainly explosive. About 600-650 years ago intermittent strong explosions and lava flow effusion accompanied frequent eruptions. Historical eruptions have consisted of moderate Vulcanian and phreatic explosions.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)