History of eruptive activity of Avachinsky volcano over the last 10 mln years has been reconstructed; age, frequency and parameters of the past eruptions, character and scale of potentially hazardous volcanic phenomena have been determined. Assessment of volcanic hazard has been given associated with the activity of Molodoi cone which began its formation 38000 years ago. Specific features of its eruption are used as the basis for the map of volcanic hazard for adjacent territories.

Based on detailed volcanological and tephrochronological investigations, parameters of catastrophic eruptions of the Molodoy Shiveluch volcano accompanied by formation of the giant debris avalanches in 1430, 1854, and 1964 have been evaluated and pre-history of their preparation has been reconstructed. Considerable attention has been given to the description of the 1964 explosive-collapse debris avalanche and a new mechanism of its formation is suggested. It is shown that similar mechanism was typical of the other two debris avalanches. Appearance of the giant debris avalanches was predetermined by various forms of andesite magma existence and by regularities of eruptive activity of the volcano in Holocene. Power and geologic-geomorphological effect of the 1854 eruption as well as size and volume of the associated debris avalanches have been revised and estimated as decreasing. Based upon productivity of the Molodoy Shiveluch volcano in XIX-XX centuries the next eruption of the 1964 type is supposed to happen in 60-90 years.