Kuril Lake
Kuril Lake was formed about 8,000 years ago as a result of a series of enormous volcanic explosions which shook southern Kamchatka. A vast territory was covered with volcanic ash. Even today, in Magadan, a thousand kilometers from the source, cross-sections displaying a five centimeter-thick layer of the characteristically yellow-tinted ash sediments from this eruption have been found, and on the Onekotan Island of the Kuril Island chain, 300 km from the center of the eruption, the ash layer is 10 cm thick. By the volume of pyroclastics (the materials blown into the atmosphere by volcanic activity), this eruption was seven or eight times more violent than the 1883 eruption of the Crakatoa Volcano in Indonesia and, most likely, resulted in serious climatic impacts on the planet. The volcano disgorged about 140–170 cubic kilometers of materials, and lava flows reached both the Pacific and Okhotsk Sea coasts of the peninsula. (Compare this with any of the well-known twentieth century-eruptions of the Ksudach, Bezimyanny, and Shiveluch volcanoes, during which “only” as much as two cubic kilometers of pyroclastics were disgorged).
In place of the gigantic gap formed during the eruption, a volcanic crater formed and gradually began to fill with water. Thus Kuril Lake was born. Over the next several thousand years, a series of recurrent events dramatically impacted the lake: other volcanoes in the vicinity erupted and new ones formed, the water level rose and fell, resulting in changes in the lake’s surface area. From the modern landscape, one can deduce that at one time the outlet from the lake flowed in the direction of the Pacific Ocean, where the valley of the Gavrushka Creek is today. Water gradually seeped out and then washed away massive pumiceous sediments near the foot of the Dikiy Greben Volcano, when the lake began to empty toward the Okhotsk Sea, creating what is known today as Ozernaya (Lake) River. The water level in the lake dropped in several stages from 250 meters above sea level to the current level of 104 meters, evidenced by the noticeable step-like terraces above the current lake.
Kuril Lake as we know it today covers 77 square kilometers, holds 15 cubic kilometers of water, and has an average depth of 195 meters. The area of the watershed is 392 square kilometers, and it takes 18 years for the water to completely replace itself. Average visibility in the water in summer is 10 meters deep. The maximum depth of the lake is 316 meters. The lake’s surface is 104 meters above sea level, which means that the lake bottom is over 200 meters below sea level! Half of the lake has a depth of more than 200 meters. This relatively small lake in surface size is the second deepest of all lakes in Russia after Baikal.
Serdse Alaida (Alaid’s Heart) is a small rocky island in the southern part of the lake, which looks like a heart. Four kilometers from the Ozernaya River outlet on the right side of its valley is an unique pumice outcropping called “Kutkhiny baty.”
S.P. Krashenninikovs writes about it: “in 9 versts from the Ozernaya River source, no one knows on which river side, there is a whitish rocky mountain, which seems to some like hooks, standing perpendicular, and because of this the local Kazaks call it Bathonian stone, and the local pagans say that the mountain was a stopping place for the God and creator of Kamchatka before he left. Heused these hooks to go fishing, and as he was leaving Kamchatka he left them standing so, and it is prohibited to approach the hooks.”
The pumice rocks are very typical for the area around the Kuril Lake. Their formation is related to powerful acidic volcanic activity in the early Holocene Period. The thickness of the pumice layer is between 70 and 110 m.
The largest population of sockeye salmon in Eurasia spawns in Kuril Lake. The optimal number of spawners for a viable population is between 1.5 and 3.5 millions fish. In some years, as many as six million fish come here to spawn, as was in the year 1990. Sockeye spawning lasts from July to March. 71% of the spawning grounds are in the lake, 26% are riverine and 3% are in brooks. A KamchatNIRO Research Statioin is located at the outlet of the lake.
The lasting abundance of sockeye is one of the most important characteristics of this natural ecosystem. To feed on the abundance, over 200 bears come here at the end of the summer. This is the best place for observing these beautiful animals. Foxes and otters also come here to feed on salmon.
The first Russian to visit Kuril Lake was likely R. Presnetsov with a group of Kazaks in 1703. The first researcher was G. Steller in 1740. A detailed description of the lake was recorded by A.N. Derzhavin, a member of the F.P. Ryabushinsky’s Interdisciplinary Kamchatka Expedition,who came here twice in 1908 and 1909. The first and most detailed archaeological studies were conducted by V. I. Jochelson in 1911.
