В работе впервые рассмотрен широкий круг вопросов, связанных с историей развития рельефа Курило-Камчатской области. Проводится анализ истории образования различных типов морфоструктур в новейшее время. Особое внимание уделено анализу динамики образо­вания морфоструктур под действием тектонических процессов и специфике формирования рельефа вулканических областей. Выделены основные тектонические эпохи.

This study is concerned with the structure of Nemo III caldera which came into being 24.500-25.000 B.P. in the north of Onekotan Island, Northern Kurils. We describe the pyroclastics of the caldera- generating eruption sequence, and estimate its volume (9-11 km3) and weight (12-14) * 10^9 t. The composition of juvenile products was found to vary in an antidromous manner during the eruptions from dacytes to basaltic andesites. The pre-caldera rocks and the pyroclastics of the caldera-generating eruption belong to the tholeiitic series, while the post-caldera rocks to the calc-alkalic. Evidence was found in the pumice discharged by the terminal eruption to indicate mixed magmas of dacyte and basaltic andesite (basaltic?) composition. The caldera-generating eruption sequence is supposed to have been caused by a "fresh" basic magma injected into a pre-existing acid magma chamber produced by fractionation of the magma which had been supplied to the pre-caldera volcanic structures.

The present paper, the first in the serives "The 300 Years of Kamchatka Volcanoes", examines the 350-year eruptive history of Young Shiveluch Volcano, which is the northernmost of the active volcanic edifices in Kamchatka; the history was reconstructed from historical documents and evidence, results of geological volcanological research and tephrochronologic dating using the 14C method. The results include the types, parameters, geologic-geomorphologic effect of the volcano's eruptions, environmental impact, estimated volume and weight of erupted and displaced material, the volcano's discharge rate. Since 1964 the dimensions of the new volcanic forms, the dynamics of their growth and decay, and the volume of ejecta were found using photogrammetric techniques. Part I. 1650-1964.

The first paper in the series “The 300 Years of Kamchatka Volcanoes” has examined the 350-year eruptive history of Young Shiveluch Volcano, which is the northernmost of the active volcanic edifices in Kamchatka: the history was reconstructed from historical documents and evidences, results of geological volcanological research and tephrochronologic dating as well as the 14C method. The results include the types, parameters, geologic-geomorphologic effect of the volcano’s eruptions, environmental impact, estimated volume and weight of erupted and redeposited material, the volcano’s discharge rate. Since 1964 the sizes of the new volcanic forms, the dynamics of their growth and destruction, and the volume of ejecta were calculated using photogram-metric techniques. Part II. 1965-2000.

The eruptive history of Ebeko since its arising about 2400 years ago to the beginning of the 17th century was reconstructed based on data of special geological, gecmorphological, tephrochronological researches using the 14С dating (more than 20 dates). Six stages of increased activity with the duration of 200-300 years were recognized. These stages are divided by quiet periods of the same duration. It is shown that the eruption of juvenile material (lava and pyroclastic) took place only at the first stage (420-200 years before our era). All the next eruptions were phreatic, but of different power. Large-scale maps and lopoplans of the Ebeko volcanic group (Ebeko, Neozhidanhy, Nezametny) with the nearest areas were compiled and the present-day morphology of the Ebeko summit part was described m detail based on ariborne materials of 1987, 1988, 1990. It is presented that, not considering the first eruptive stage, the main volcanic hazard for the Ebeco region and the town of Severo-Kurilsk situated near the volcano came from the moving of large lahars and tephra fall.

Consequences of the Ebeko eruptions in 17-20 centuries were reconstructured in detail based on history information and data of tephrochronoSogical investigations and air photography of 1960, 1987, 1988, 1990. It is shown that all the eruptions were phreatic and conditionally phreatomagmatic with thermal alimentation as a very heated dike-sill complex with volume of more than 1 km , in the zone of extension NNW (Az. 25°), where volcanoes of the Vernadsky ridge are located (Paramushir island). It is supposed that the main future hazard for the Severo-Kurilsk town and the nearest areas is expecting from the moving of lahars of large-volume along the Kuzminka and the Matrosskaya rivers originated from the Ebeko volcano. Lesser hazard is expecting from ashfalls produced by the Ebeko and other volcanoes of the North Kuril and the Souih Kamchatka. It is proved that a big hazard for the may arise from the future eruption of the Ebeko similar to those eruptions of 1934-1935. It is recommended some ways for defence of the town.

This study revealed that the giant cirque of Bakening Volcano had been produced by its eruption ca. 8000-8500 carbon-14 year ago. The eruption is supposed to have been heralded by a large earthquake (M > 7) resulting in the collapse and slide of the SE sector of the cone. The landslide unroofed the hydrothermal system and triggered an explosion which was followed by an ash-and-block pyroclastic flow. A rockslide avalanche rolled down into the valley of the Srednyaya Avacha River and travelled as far as 10-11 km along it. The avalanche deposited its debris material over an area of 18-20 km2 measuring 0.4-0.5 km3 in volume. These deposits dammed the river, produced two lakes (Bezymyannoe and Verkhneavacha), and gave birth to a large lahar which traveled along the valley much farther.

В работе впервые рассмотрен широкий круг вопросов, связанных с историей развития рельефа Курило-Камчатсхой области. Проводится анализ истории образования различных типов морфоструктур в новейшее время. Особое внимание уделено анализу динамики образования морфоструктур под действием тектонических процессов и специфике формирования рельефа вулканических областей. Выделены основные тектонические эпохи.