State of the acid crater lake of Gorelyi Volcano, Kamchatka, in the summer of 1996

New data are presented on the structure and present-day state of an active crater on Gorelyi Volcano (Kamchatka). The chemistry of water in its acid lake was investigated for the first time. In terms of its physicochemical parameters the water of the lake was found to resemble the water of lakes from many active volcanoes of the world, except for some hydrochemical differences. It is believed that in combination with seismic measurements and visual observations the monitoring of the lake water physicochemical variations will be useful for predicting Gorelyi eruptions.