A matematical model is given of the formation of phreatic explosions in lava flows coming into contact with ice formations. Quantitative characteristics are derived for the various stages in the development of the explosion; by means of wich its strength and other parameters may be evaluated. The theoretical calculation results are in agreement with empirical data.

Построена теплофизическая модель стационарного состояния ледника в активном кратере Ушковского вулкана. Анализ составляющих баланса массы льда показал повышенный геотермический поток (среднее значение 10 Вт/м¤) в пределах вершинного конуса и слабую его изменчивость за последние 40 лет. По измеренной скорости аккумуляции и распределению температуры в снежнофирновой скорости аккумуляции и распределению температуры в снежно-фирновой толще в центре кратера Горшкова предполагается существование значительного поднятия (вложенного малого кратера), перекрытого ледником.
Полученные расчетные формулы помогут оценить параметры критических состояний нестационарных ледяных масс на склонах Ключевского вулкана.

Тефрохронологические исследования, проведенные в долине р. Левая Авача, позволили установить истинный возраст шлакового конуса Веер, который образовался примерно в 470 г. н.э. (1600 14 л.н.). Эти данные опровергают существовавшие до настоящего времени представления о дате его формирования в 1856 г. Моногенный конус Веер необходимо исключить из каталогов исторических извержений и действующих вулканов Камчатки. Извержение конуса явилось проявлением общекамчатской активизации эндогенных процессов, происходившей в 0-650 гг. н.э.

The ~16-ka-long record of explosive eruptions from Shiveluch volcano (Kamchatka, NW Pacific) is refined using geochemical fingerprinting of tephra and radiocarbon ages. Volcanic glass from 77 prominent Holocene tephras and four Late Glacial tephra packages was analyzed by electron microprobe. Eruption ages were estimated using 113 radiocarbon dates for proximal tephra sequence. These radiocarbon dates were combined with 76 dates for regional Kamchatka marker tephra layers into a single Bayesian framework taking into account the stratigraphic ordering within and between the sites. As a result, we report ~1,700 high-quality glass analyses from Late Glacial–Holocene Shiveluch eruptions of known ages. These define the magmatic evolution of the volcano and provide a reference for correlations with distal fall deposits. Shiveluch tephras represent two major types of magmas, which have been feeding the volcano during the Late Glacial–Holocene time: Baidarny basaltic andesites and Young Shiveluch andesites. Baidarny tephras erupted mostly during the Late Glacial time (~16–12.8 ka BP) but persisted into the Holocene as subordinate admixture to the prevailing Young Shiveluch andesitic tephras (~12.7 ka BP–present). Baidarny basaltic andesite tephras have trachyandesite and trachydacite (SiO2 < 71.5 wt%) glasses. The Young Shiveluch andesite tephras have rhyolitic glasses (SiO2 > 71.5 wt%). Strongly calc-alkaline medium-K characteristics of Shiveluch volcanic glasses along with moderate Cl, CaO and low P2O5 contents permit reliable discrimination of Shiveluch tephras from the majority of other large Holocene tephras of Kamchatka. The Young Shiveluch glasses exhibit wave-like variations in SiO2 contents through time that may reflect alternating periods of high and low frequency/volume of magma supply to deep magma reservoirs beneath the volcano. The compositional variability of Shiveluch glass allows geochemical fingerprinting of individual Shiveluch tephra layers which along with age estimates facilitates their use as a dating tool in paleovolcanological, paleoseismological, paleoenvironmental and archeological studies. Electronic tables accompanying this work offer a tool for statistical correlation of unknown tephras with proximal Shiveluch units taking into account sectors of actual tephra dispersal, eruption size and expected age. Several examples illustrate the effectiveness of the new database. The data are used to assign a few previously enigmatic wide-spread tephras to particular Shiveluch eruptions. Our finding of Shiveluch tephras in sediment cores in the Bering Sea at a distance of ~600 km from the source permits re-assessment of the maximum dispersal distances for Shiveluch tephras and provides links between terrestrial and marine paleoenvironmental records.