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.

Theories are presented about the time of origin, dynamics and formation mechanism of active volcanoes in the Kuril-Kamchatka zone during the Late Pleistocene-Holocene period. The study was based on more than 500 radiocarbon dates and the results of geological, geomorphological, tephrochronological and isotopic geochronological research. It is noted that there are different rhythms in the activity of the volcanoes and in the mechanisms and rates of formation of the volcanic structures. Periods of synchronous activity of the volcanoes on Kamchatka and the Kuril islands, and apparently, in other volcanic areas are identified, suggesting their global nature. The concept of "active volcano' is discussed. -P.Cooke

На основании палинологических исследований приводится возрастное расчленение вулканогенно-осадочных отложений Узон-Гейзерной кальдерной депрессии и палеогеографическая обстановка времени осадконакопления. Установлен позднеплейстоцен-голоценовый возраст отложений. Датированы основные события посткальдерной вулканической деятельности в кальдере Узон.

В течение 1997-1999 гг. вблизи вулкана Карымский (∆ = 1.5 км) в рамках Российско-Американской экспедиции (начальник экспедиции с Российской стороны А.Ю. Озеров, научный руководитель Е.И. Гордеев) проводились комплексные наблюдения за сейсмическими и инфразвуковыми волнами, сопровождавшими эксплозивную активность вулкана. Регистрация сигналов осуществлялась цифровой аппаратурой с частотой дискретизации сигнала 125 Гц, амплитудно-частотные характеристики аппаратуры и ее калибровка приведены в работе [13]. В данной статье сделан предварительный анализ особенностей генерации акустических сигналов (АС) в атмосфере, сопровождавших эксплозивную деятельность вулкана.

On March 24, 2017 Kambalniy Volcano started to erupt after a 500-year-long period of rest. The eruption continued till April 10, 2017. The paper provides the analysis of atmospheric wave disturbances as wavetrains of quasi-sinusoidal oscillations with a frequency of 8 Hz ("acoustic tremor" or AT), which occurred at certain moments during the eruption. Besides, the paper describes 3 strongest seismic signals registered at the initial stages of the eruptions simultaneously with AT, which was registered using an infrasound station IS44 installed 208 km NW far from the volcano. The nearest "Pauzhetka" seismic station installed 19 far from the volcano allowed monitoring the seismic build-up, which was short (2 days) and weak (Кmax = 8.6). Lack of definite discrete infrasound signals, which are usually caused by non-stationary process during explosive eruptions, gives evidence for peculiar pattern of formation and effusion of ash-and-gas emissions. Such uncommon acoustic radiations and seismic build-up prove the presumption that this eruption should be classified as a hydrothermal event.

Investigation of place of contact between the fresh lava flow from the 2012-2013 Tolbachik eruption and forest vegetation revealed an unusual phenomenon such as craters from explosions, partially destroyed old lava cover and soil-pyroclastic cover. Besides, traces of powerful scorching on the trunks of alder thickets adjacent to the craters were also found. Most likely, these craters have resulted from explosions that occurred due to the concentration of methane in the cracks and cavities in the old lava. The methan was caused by wood pyrolysis, buried by red-hot lava of 2012 eruption.

Eight-year (1996-2003) multidisciplinary biohydrochemical research provided data for this brief description of abiotic processes varying in time in Lake Karymskii and of simultaneous successions of plankton and benthic algae-bacterial communities following the 1996 catastrophic underwater eruption. One notes the well-ex-. pressed allochtonic character of plankton flora, a mosaic and local formation of benthic coenoses, the dominating influence of the volcanic factor on the overall evolution of limnic biocoenosis.