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.

The paper presents data on identified and described short-term local (1955−1976) enhanced volcanic activity within the Northern Group at the Central Kamchatka Depression and regional disasters (1907-1976), clearly revealed within Kamchatka Peninsular and the Kurile Islands. In scale (volume is about 9 km3, weight of erupted and replaced productswas calculated to be about 16×109 t), the local volcanic disaster was the most powerful in Kamchatka and Kurile Islands over the period of the last 2000 years. This volume exceeds 80% of ~19×109 t totally erupted by all volcanoes over the same period of time. Over the period 1907−1976, the Kamchatka and Kurile volcanoes erupted and transported about 29.5×109 t of juvenile and resurgent material while other volcanoes in the world erupted about 122×109 t.

It is shown that the cardinal revision, attempted in 1988 and 1998, of the G.S. Gorshkov hypothesis as to the explosive origin of the debris avalanche (“directional explosion agglomerate”) caused by the 30 March, 1956 culminating phase of the catastrophic eruption on Bezymiannyi Volcano, Kamchatka does not rest on a safe foundation. The hypothesis of a different (avalanche-landslide) origin, similar to the May 18, 1980 Mount St. Helens, U.S. event, must be rejected owing to an absence of necessary evidence. New arguments are adduced to support the Gorshkov hypothesis, corroborating that the main factor that caused the debris avalanche was a giant directional explosion.

Предложен новый вариант геолого-геоморфологического строения и истории формирования массива Вулканологов (МВ), расположенного в Командорской котловине Берингова моря. Основой для него послужили батиметрическая карта, созданная в 2009 г. по результатам многолучевого эхолотирования с борта экспедиционного судна «Зонне», и частично ревизованные материалы более ранних геолого-геофизических исследований этого района. Показано, что МВ перед началом формирования вулкана Пийпа был кардинально преобразован и разрушен катастрофическими магмо-тектоническими и обвально-взрывными процессами. Определены параметры МВ, активного вулкана Пийпа и открытого автором магматического суперпотока, оценен их возраст.