Home – Home – Jornals – Geography and Natural Resources 2019 number 4

New evidence for an active geological and geomorphological object, the Ksudach caldera complex, has been obtained: geomorphological and repeated bathymetric and thermal imaging surveys were conducted with a break of 25 years. For the first time, a geomorphological map of the coasts of the lakes was compiled, and detailed bathymetric schematics of their basins were drawn. Four morphogenetic types of coasts are identified, with a general predominance of abrasion processes (accumulation is dominant only in the mouths of the rivers). In Lake Stubel, an underwater extrusive dome was recorded instrumentally, about 40 m high and about 300 m in diameter of its base, with extensive underwater gas-hydrothermal vents. Most likely the morpho logical configuration of the extrusion in the relief of the bottom of the lake occurred after the surveys of 1991, and the analysis of modern gas-hydrothermal activity in the Ksudach caldera shows a relative stability of the post-volcanic processes that mani fest themselves as gas-hydrothermal vents both within the lake basins and on their shores. The depth of Lake Klyuchevoe and Lake Stubel decreased by 3 m over the last 25 years, while their linear and areal characteristics have remained almost unchanged. A gradual decrease in maximum depths can be caused by permanent input of detrital material to the deep-water part of the lakes, transported by rivers and as well as abrasion, and by planation of their bottoms. The depth of the crater part of Lake Stubel could also decrease due to the rise of the bottom areas during the formation of the extrusive domes.