Lake Kipyashchee (Boiling) with an area of ~4.6 ha and a maximum depth of 25 m fills the explosion funnel near one of the extrusive domes of the Golovnin volcano caldera. The water of the lake is ultra-acid (рН = 2.2–2.5) of the chloride-sulfate type with a mineralization of 2.0–2.2 g/l. The water temperature on the surface varies from 30 to 100°C, the average is 37°C. The flow of the lake is carried out through the Protoka in the lake Goryachee (Hot) is 120 l/s (August 2021). The hydrothermal output of magmatic Cl and S (as SO4) from Lake Kipyashchee is 10 t/day and 5.4 t/day, respectively. For the first time, the total diffusive removal of carbon dioxide from the surface of Lake Kipyashchee was estimated as 5.4 tons/day. Obtained from the results of field work in 2020–2021 geochemical data indicate an increase (compared to 2015) in hydrothermal activity in the Golovnin volcano caldera.

The chronology, dynamics, and parameters of seven large eruptions of Avacha Volcano were reconstructed for its IAv andesitic period 7250-370014C years B.P., which began after a >2000-year period of relative quiescence. Their juvenile (andesitic pyroclastics) and resurgent products are described, and the geological and geomorphological consequences are evaluated. The largest eruption occurred 715014C years B.P. (8-10 km3 of erupted material). The subsequent events occurred 5700 (≥0.34 km3), 5600 (≥0.4 km3), 5500 (>1.34 km3), 5000 (≥0.5 km3), 4500 (>1.1 km3), and 4000 (≥0.6 km3) 14C years B.P. The erupted rocks were dominated by tephra; pyroclastic flows occurred only during the events of 5500 and 5000 years ago. It is believed that most of the eruptions produced acid peaks of varying intensity in the Greenland ice sheet.