Through radiocarbon techniques we determir the age (30 000 yrs) of the latest in the Late Pleistocene directed blast at the Avachinsky volca and approximately calculated the age of the previous large catastrophic eruption of the same type (35 00( 40 000 yrs). Coarse debris deposits produced by the eruption originally covered the area of 400 km2 a their volume was 16-20 km3. As a result of these eruptions the relief cardinally changed to the south of t Avachinsky and the lower part of the Avacha river channel was transported to the distance of 6-10 km. 11 believed that in the nearest hundreds of years such blasts will not take place but this forecast does not apply the adjacently located Koryaksky volcano.

The 1645 B.C. oxygen peak in Dye 3 borehole (65.18 N, 43.49 W) drilled in the Greenland ice sheet is shown to have been the catastrophic caldera-generating Aniyakchak eruption (56.88 N, 158.17 W) on Alaska Peninsula, U.S. rather than the famous Minoan eruption (36.404 N, 25.396 E) on Santorin Island, Greece.

We studied the tectonic setting, morphology, geological structure, the history of eruptive activity and the evolution of the composition of the erupted material of Kizimen volcano (Kamchatka) from the moment of its origination (12-11 thousand years ago) to the present time. Four cycles 2-3,5 thousand years long each were distinguished that characterize the activity of the volcano. All largest eruptions were dated, their parameters determined. We also estimated the volume and the mase of the erupted products, volcanic intensity of evacuation of material during-periods of high activity and productivity of the volcano at different stages of its formation. It has been shown that evolution of the composition of the rocks erupted (from dacite to basaltic andesite) takes place as a result of mixing of dacitic and basaltic magma. It is proposed that future eruptions that may take place at Kizimen will be similar to those at Bandai (1888) and Mount St. Helens (1980) volcanoes.

For the first time, tracks from 5 catastrophic lahars associated with subsynchronously occurring rueptions of the Avachinsky (great explosions with a large volume ejections of juvenile pyroclastics) and Koryaksky (voluminous lateral lava effusions) volcanoes have been found, described and dated by the C-14 method. Their reconstruction has been conducted. The C-14 ages of lahars are from 3500 to 3200 yrs ago, the calendar ages are from 1900 to 1500 BP. These lahars were significantly greater in volume, degree of hazard, and intensity of impact on the natural environment than those triggered by historic (19th - 20th centuries) eruptions from the both volcanoes. In particular, they caused a considerable (1-3 km) SW migration of the Avacha river down-stream channel, the largest waterway in Southern Kamchatka.

Восстановлен ход извержения вулкана Опала (Южная Камчатка) около 500 г. нашей эры на основе изучения вещественного состава пирокластики, в первую очередь тефры. Объем изверженных продуктов (тефра, пирокластичеокие потоки, экструзивный купол) - около 10 км3. Центром извержения был Бараний амфитеатр - кратер размером 1,3х2,0 км в юго-восточном секторе подножия вулкана. Возраст тефры определен на основе многочисленных 14С датировок в восьми разрезах почвенно-пирокластического чехла по профилю от эруптивного центра до оз. Кроноцкое. Состав тефры (49 силикатных анализов) риолитовый; данные по содержанию в тефре малых, редких и рассеянных элементов свидетельствуют о незначительных вариациях ее состава на микроэлементном уровне. Показана зависимость содержания Аи в тефре от содержания в пробах тонкой фракции. По структурной приуроченности и типу эруптивного аппарата, значительным (близким к кальдерным) объемам однородной пирокластики, тефре, почти не испытывающей гравитационной эоловой дифференциации, извержение вулкана Опала 500 г. и генетические сходные с ним извержения предлагается выделить в особый тип субкальдерных (субкальдерообразующих) извержений типа Санта-Мария.