The Sea of Okhotsk is the southernmost area in the Northern Hemisphere where seasonal sea ice is produced every year. The formation of sea ice drives thermohaline circulation in the Sea of Okhotsk, and this circulation supports the high productivity in the region. However, recent reports have indicated that sea-ice production in the Sea of Okhotsk is decreasing, raising concern that the decreased sea ice will affect not only circulation but also biological productivity in the sea. To reconstruct climatic changes in the Sea of Okhotsk region, we analyzed an ice core obtained from Ichinskaya Sopka (Mount Ichinsky), Kamchatka. We assumed that the remarkable negative peaks of δD in the ice core were caused by expansion of sea ice in the Sea of Okhotsk. Melt feature percentage (MFP), which indicates summer snowmelt, showed high values in the 1950–60s and the mid-1990s–2000s. The high MFP in the 1950–60s was assumed to be caused by an increase in cyclone activity reaching Kamchatka during a negative period of the Pacific Decadal Oscillation index, and that in the 1990–2000s may reflect the increase in solar irradiation during a positive period of the summer Arctic Oscillation index.

Previous data are summarized and new evidence is presented on the Avacha eruptions of 1926-1927, 1938, and 1945. The last eruption of January 1991 is described. The dynamics of the Avacha eruptive activity is considered for a period of 1737-1991. The eruptions are classified into different types. The type and size of a future event are predicted and the related hazard is assessed. It is recommended that the southwestern and southern sectors of the Avacha surrounding should be declared forbidden for residential or industrial construction because of a high volcanic hazard. -Journal summary

Some of the previous views on the style of the Avacha eruptions during 1737-1909 are revised on the basis of new data obtained by the authors. The types of eruptions, their geological and geomorphological effects, and the related volcanic hazards are reassessed. All eruptions were explosive events, except for the 1894-1895 extrusive-explosive eruption. The eruptions of 1737, 1779, and 1827 are classified as large, the others, as mild or medium-size events. -from Journal summary

Реконструированы и датированы 14С-методом четыре плинианских извержения вулкана Ксудач, сформировавших три кальдеры обрушения: KCi и кальдеру V - 1700-1800 л. н.; КС2 + КС3 и кальдеру IV - 6000-6100 л. н.; КС4 и кальдеру III 8700-8800 л. н. Самым мощным было извержение KCi: 18-19 км3 пирокластики, высота эруптивной колонны до 23 км. Объем продуктов извержений КС2 + КС3 - 10-11 км3, КС4 - не менее 1,5-1,7 км3. Размеры кальдер: V - 4 X 6,5 км, IV - 5x6 км, поперечь III - предположительно 2-3 км. Вынос ювенильной пирокластики в ходе извержений было ритмичным. Каждый ритм начинался выбросом тефры, а завершался формированием пирокластических потоков. Состав продуктов варьировал от андезитов до риодацитов: КС2 и КС4 - преимущественно андезиты, КС3 - дациты и риодациты, KCi - риодацит. Предполагается, что "спусковой механизм" для начала всех кальдерообразующих извержений - внедрение свежей сильно нагретой магмы основного состава и смешение ее с остывающей кислой магмой существовавшего ранее очага. В соответствии со своими масштабами извержения должны были оказать влияние на климат и озоновый слой 3емли и найти отражение в виде кислотных пиков в Гренландском ледниковом щите.

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.

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