"Каталог действующих вулканов Курильских островов" является сводкой наших знаний на 1 января 1957 г. по действующим вулканам Курильских островов.

Реконструирована плейстоценовая и голоценовая активность вулканического центра Эльбрус (Северный Кавказ, Россия). Выявлены и продатированы различными методами (К-Ar, С, ЭПР) крупная (14 X 17 км, площадь 230 км2) кальдера обрушения, мощные этапы эксплозивного вулканизма, катастрофические лахары, лавовые потоки, землетрясения и региональные пожары. Установлено, что в голоцене сильные эксплозивные и эксплозивно-эффузивные извержения происходили в 7200-7300, 5800-6000, 5200-5300, 4000, 2900, 2600 гг. до н.э. и в I-П вв. н.э. Показано, что вулкан Эльбрус является потенциально активным и что его извержения могут сопровождаться катастрофическими явлениями.

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.

Five major explosive eruptions discharging pyroclastic volumes of more than 1 km^3 have been identified in the Holocene eruptive history of Avacha Volcano. All of these were Plinian-type eruptions, three (of andesitic composition) occurring 7150, 5500 and 4500 14C B.P. Two eruptions (3500 and 3280 14C B.P.) that supplied andesitic basalts preceded or started the formation of Young Cone on Avacha Volcano. We have reconstructed the dynamics and parameters of the eruptions, assessed their geologic, geomorphic and ecologic effects, and provided a long-term forecast.

Four Plinian eruptions from Ksudach volcano ha' been reconstructed and dated by the 14C method. Three collapse calderas formed as a resu of these eruptions: KSi and caldera V 1700-1800 yrs ago; KS2 + KS3 and caldera IV 6000- 6100 yrs ago; KS4 and caldera III 8700-8800 yrs ago. KSi was the most voluminous eruptio with 18-19 km of pyroclastics and column height reaching 23 km. The volume of produci of KS2 + KS3 was 10-11 km3 and that of KS4, at least 1.5-1.7 km3. Sizes of calderas wer as follows: V - 4 X 6.5 km, IV - 5x5 km, III - presumably 2-3 km across. The juveni pyroclastics were supplied during eruptions rather rhythmically. Each rhythm began wil tephra ejection and completed with the formation of pyroclastic flows. The composition < products varied from andesited to rhyodacites: KS2 and KS4 - andesites dominated, KS3 - dacites and rhyodacites, and KSi - rhyodacites. It is possible that "the mechanism triggering onsets of all caldera-forming eruptions was the intrusion of very hot fresh magma of basi composition and its mixing with less hotter acid magma in the magma chamber existe previously. The eruptions, in accordance with their scales, may have had an impact on clima and ozone layer of the Earth. It is likely that the large acidity peaks in Greenland ice cor* result from these eruptions.

This paper discusses two catastrophic Plinian-type eruptions which occurred close enough in time (IIAV1 -3500 and IIAV3 - 3280 14C yrs B.P.) on Avacha Volcano and initiated the activity of its Young Cone. We studied the stratigraphy of the ejecta, reconstructed their chronology and parameters, assessed their environmental impact. The ejecta of both of these eruptions were dominated by tephra whose volume is >3 and >1.1 km3, respectively. The eruptive columns rose as high as 21-28 km. The IIAV1 ash layer can be followed for 300 km northeast of the volcano, the ashfall area enclosed within the 1 cm isopach being about 50000 km2. Both eruptions were accompanied by pyroclastic flows, surges, and catastro3phic lahars. The juvenile3pyroclastics is basaltic andesite. By the values of total discharge volume (>3.6 km3 for IIAV1 and >1.21 km3 for IIAV3), these eruptions must be among the largest to have occurred during the eruptive history of the Young Cone.