The eruptive history of Ebeko Volcano is described since its origin about 2400 years ago until the beginning of the 17th century. Six stages of increased activity each lasting 200-300 years were separated by repose periods of the same duration. The eruption of juvenile material (lava and pyroclastics) took place at the first stage only (420-200 B.C.). All eruptions that followed were phreatic events of varying vigor. It is shown that, except for the first eruptive stage, the main volcanic hazard for the Ebeko area and the town of Severo-Kurilsk near by comes from large lahars and tephra fallout. -from Journal summary

По историческим сведениям, дополненным тефрохронологическими исследованиями и материалами аэрофотосъемок I960, 1987, 1988, 1990 гг. района в. Эбеко, детально восстановлены последствия его извержений XVII-XX вв. Показано, что все извержения были фреатическими и условно фреатомагматическими с источником теплового питания в виде сильно нагретого дайково-силлового комплекса объемом более 1 км . приуроченного к зоне растяжения ССВ (аз. 25°) простирания, вдоль которого расположены вулканы хр. Вернадского на о-в Парамушир. Предполагается, что в будущем главная опасность для г. Северо-Курильска и прилежащих участков связана с прохождением большеобъемных лахаров по рекам Кузьминка и Матросская, начинающихся на в. Эбеко, в меньшей степени - с пеплопадами этого и других вулканов Северных Курил и Южной Камчатки. Доказывается, что серьезная угроза городу может возникнуть при будущем извержении в. Эбеко типа его извержения 1934-1935 гг. Рекомендованы меры для защиты города.

Lava flows from sixteen sites at Gorely Volcano, Kamchatka were sampled. Initial analysis showed high within-site scatter for NRM specimen directions. Alternating field and thermal demagnetization of specimens showed single-component magnetization indicating that specimens had not moved or were not exposed to changes in the magnetic field during acquisition of a magnetic direction. Scatter is thought to be either due to movement of the specimen with respect to the magnetic field or change in the magnetic field with respect to the specimen. Four factors were found that would contribute to scatter in specimen directions. These are 1) cooling rate, 2) range of unblocking temperatures, 3) relative time of emplacement, and 4) how the specimen moved or was affected by changes in the magnetic field. Only two sites showed that scatter was due to movement of the specimen. It appears that scatter in other sites resulted from changes in the magnetic field generated from a magma-induced electrical current due to lava flowing in the earth’s magnetic field. These changes in the magnetic field are shown to have more affect on material sampled at the surface than on material sampled at depth because massive interiors of flows showed less dispersion in specimen directions than levees or pull-aparts.

The new mechanism of the edifice stability loss of stratovolcario have been suggested at the expence of the magma intrusive sheet development from the feeding system. On the base of (hat mechanism there have been considered the opportunity of the catastrophic slope collapse of the Klyuchevskov volcano and there have been given an estimation of ihc geometric parameters of landslide deposils.

Ages of most of the active volcanoes, calderas and craters of subcaldera eruptions in the Kurile-Kamchatka region were determined based on the results of geological, geomorphological, tephrochronological and isotope-geochronological studies using more than 600 l4C dates. It has been revealed that the active volcanoes are young, their maximum ages are 40 000 - 50 000 years. Most of the volcanoes that are active at present time started to form at the very end of the Late Pleistocene and in the Holocene. The l4C age was determined for the majority of volcanoes that started to form in the Holocene. It was found that all polygenic stratovolcanoes in Kamchatka formed in the Holocene only within the Eastern volcanic zone. The l4C age was determined for most of the Late Pleistocene calderas that formed within 30 000-40 000 years ago. All Holocene calderas and some craters of subcaldera eruptions were dated. The periods of synchronous intensified activity of volcanoes were determined in the Holocene between 7500 and 7800 years ago and between 1300 and 1800 years ago.

This paper gives data on the volcanic belts of Kamchatka. Recognition of !hc volcanic zone of the Central Kamchatka Depression as an independent, extensively developing structure is validated. Data available in the literature arc systematized and the quantitative characteristics are recalculated for all the active volcanoes of Kamchatka: the total volume of volcanic rocks, relative heights, absolute and relative volumes of rocks of basic, intermediate and acid composition, mean production rate of edifices, duration of formation (in thousands of years) etc. Their calculated mean statistical values for a Kamchatkan volcano for the entire region and for separate groups of edifice types have been obtained for the first time. This study shows that the basic volcanism plays the leading part in the formation of volcanic edifices.

На склонах Ключевского вулкана и вблизи него на площади 30x40 км изучены линейные формы рельефа (линеаменты) и тектоническая трещиноватость. Выделены зоны с преобладанием линеаментов различного направления. По пересечению одних зон другими установлен их относительный возраст (возраст последней активизации).
Показано, что наиболее молодой и активной в последние годы является линейная зона северо-западного простирания. Особо выделены две зоны, отличающиеся своеобразным структурным рисунком: дуговая, окаймляющая вулкан с востока на высотах 900—2500 м, и на крутом склоне конуса (выше 2500 м). В пределах последней выделена система дуговых трещин и сбросов, свидетельствующая о растяжении конуса («паукообразный» структурный рисунок). На основании анализа распространения подобных систем трещин и сбросов на других вулканах установлено, что они могут служить прогностическим
признаком, указывающим на процессы разрушения, происходящие на вулканах, и на места будущих побочных прорывов или обрушений склонов. Для Ключевского вулкана установлено, что наиболее опасен его юго-восточный склон, где в будущем возможны крупные обвалы или проседания.