Mineral formations from fumaroles localized in craters and on lava flows were collected by the winter during 1937—1938 eruption of the Klyuchevoskoy volcano (Kamchatka) when a number of adventive craters broke out on its slopes. These were investigated sublimates from craters at different distances from the central core, from their lava flows formed by portions of magma issuing from the core one after another; from flows at various stages of formation and cooling; from fumaroles with wide temperature range. This material allows to get an idea of the distribution of elements in space, time and their depending from temperature. The basaltic magma of the Klyuchevskoy volcano erupted in 1937— 1938 contains the greatest part of the elements Mendeleev’s periodical system, elements characteristic of basic magma as well as those considered as characteristic of acid magma.
During the crystallization of the products of mineral formation from the fumaroles, along with the carrying out of substance from the magma there is taking place an extraction of substance from rocks through which the gases escape, some peculiarities being noticed due to the action of gases of different composition.

Analysis of paleomagnetic variations along parallel sections across the Holocene soil-pyroclastic cover of Ма1уĭ Semyachek Volcano in Kamchatka has shown that directions of magnetization were similar during а period of 350 — 6000 В.P. This proves that magnetization is primary and applicable for reconstruction of the history of the Earth's magnetic field. Paleomagnetic variations that occurred in the interval of 1000 — 4000 В.P. have been investigated in the contemporaneous tephra section of Klyuchevskoĭ Volcano 240 km to the north.
It is known that since some of the tephra horizons may be missing in this section owing to specific conditions of tephra deposition, а more detailed knowledge of paleomagnetic variations requires the study of two or more parallel sections.

The actual collective monograph presents the results of both theoretical and experimental studies of the multi-disciplinary problem on volcanic hazard assessment and development of techniques for prediction of catastophic eruptions. The volcanism of Kamchatka and other regions of Russia has been analyzed. On the basis of geological, volcanological and tephrachronological studies including radiocarbon dating, there have been defined certain groups of volcanoes on different stages of evolution. At the same time the problem of determination of the internal structure of volcanic dome using modem theoretical methods and technologies is well investigated. The new techniques of estimation of volcanic hazard were developed. Whenever ti is required, theoretical approaches are confirmed by results of in-field observations.

The book will satisfy the needs of Earth sciences specialists from a variety of backgrounds, volcanology, geo-mechanics, ecology, industrial constuction applications and hazard assessment.