The results of detailed seismic investigations during the period 1961 to 1964 are described. Accurate data of focus location for Kamchatka and the Commander Islands are cited. The majority of earthquakes are located in the Pacific focal zone and the others are found in such remarkable tectonic regions as the east Kamchatka ranges, the continental slope of the Commander Islands, etc. The focal zone seismic activity decreases with increasing depth. The seismic activity at a depth of 250 km is 100 times less than the activity at a depth of 0–20 km. Kamchatka earthquake locations in relation to the Kuril-Kamchatka Island arc and deep water trench are approximately the same as those of the south Kuril Island earthquakes. The Kamchatka active volcano belt coincides with the region of earthquakes having focal depths of 100–200 km, especially between 125 and 175 km. S-wave screening in the magma chambers under the volcanoes is observed. The Avacha volcanic cluster magma chamber at a depth of 20–80 km has the form of a column, 25 km in diameter. P-wave velocity in the upper mantle under the Pacific Ocean and between the Aleutian trench and the Kuril-Kamchatka trench is about 8.2 km/sec, and under Kamchatka 7.7 km/sec. Local velocity decreases to basaltic range (Vp = 72 km/sec) in the upper mantle at a depth near 70 km under the east Kamchatka active volcano belt.

Kamchatka is one of the most active volcanic regions on the planet. Large explosive volcanic eruptions, in which the ash elevates up to 8–15 km above sea level, occur here every 1.5 years. Study of eruptions precursors in order to reduce a volcanic risk for the population is an urgent problem of Volcanology. The available precursor of strong explosive eruptions of volcanoes, identified from satellite data (thermal anomaly), as well as examples of successful prediction of eruptions using this precursor, are represented in this paper.

An explosive eruption of Young Shiveluch Volcano occurred on September 22, 2005, discharging a pyroclastic flow about 20 km long in the Baidarnaya River valley and an ashfall in the area of the Northern group of volcanoes.

The sources of geothermal energy of Kamchatka are hydrothermal systems, local blocks of high heated rocks, and peripheral magma chambers of active volcanoes in particular. According to gravimetric, magnetic and seismic data, under the Avachinsky volcano there exists an anomalous zone which is suspected to be a peripheral magma chamber. It is localized at the boundary of the Upper Cretaceous basement and an overlying volcanogenous stratum at a depth of 1.5 km from sea level. Its geophysical data are as follows: the radius is 5.2±0.9 km; the density of rocks is 2.85 to 3.15 g/cm3, the velocity of longitudinal waves is 2200 m/sec, the viscosity of rocks is 105 to 108 poise. The temperature distribution in the near-chamber zone was calculated by clcctrointegrator at 0°C at the Earth's surface and 1000°C at the chamber surface for stationary and non-stationary (the period of 20 000 years) heating. Heat extraction may be possible if a system of artificial jointing iscreated. The capacity of a thermal reservoir with a volume of one cubic km at a depth of 5 km and a distance of 6 km from the volcano would be 2 x Ю14 kcal, extractable under non-stationary conditions, which could provide the work of power stations with a total capacity of 250 MW for a period of 100 years.

AAbstract—Numerous summit and parasitic eruptions of moderate potassium magnesian and high-alumina basalts and basaltic andesites, their mineralogic and geochemical features, and the composition of in situ chilled melt inclusions in the olivine of cinder lapilli discharged by Klyuchevskoi Volcano all provide evidence of the presence of magma chambers beneath the volcano. This is also supported by a dualism in the variation of CaO and A1203 concentrations in olivine and clinopyroxene during crystallization. The mineralogic features in the high-alumina basalts that were discharged by all parasitic eruptions of Klyuchevskoi provide evidence of magnesian magma being emplaced from a deeper chamber into a shallow high-alumina chamber. The distribution of incoherent elements in the volcano's magnesian and aluminiferous rocks shows that they came from a single mantle source. The geochemical and mineralogic data are in good agreement with the results of geophysical surveys that concern the structure and properties of the lithosphere beneath Klyuchevskoi.