Severe earthquakes in the Krasnodar reservoir region ? New evaluations

Abstract

The Krasnodar reservoir, in the lower reaches of the Kuban' River, was constructed in a region which has been traditionally considered to be a zone of possible development of earthquakes of an intensity of up to 6 [1], However, during the process of review of data for historical earthquakes in the Northern Caucasus and preparation of a new alternative map of general seismic zoning, material was obtained which led to modification of the existing evaluation. It turned out that in the lower reaches of the Kuban' River there have been earthquakes of a substantially greater magnitude. Naturally enough, there arise the questions about which are the real manifestations of these earthquakes, the general seismic potential of the region, and to which degree the new data may affect the evaluation of the dam stability and the conditions of existence of the Krasnodar reservoir. From this viewpoint, the obtained factual material about earthquakes in the lower course of the Kuban' River in the reservoir vicinity is presented and examined. Information about earthquakes in the region began to be collected only since the time of settling there of the Cossacks and placing of the territory under Russian control, that is, since the end of the 18th Century. Over this two-century period, several intense local earthquakes have been recorded. The most intense and latest of them was the Kuban' earthquake of April 19, 1926, which took place when the period of instrumental observations had already begun; however, the instrumental information that it was possible to detect and process was scarce and of low quality. Subsequently, intense earthquakes in the lower course of the Kuban' River were not recorded; for this reason, it is necessary to be based on macroseismic information