Поводом к написанию публикуемой статьи послужили первые результаты полевого исследования последствий эксплозивного извержения вулкана Пик Сарычева на острове Матуа и сопутствующих ему явлений. Сотрудникам Дальневосточного отделения РАН удалось оперативно отреагировать на уникальное природное явление, изучив его в прямом смысле по горячим следам.

The preliminary results of surface expedition "Peak Sarychev Volcano-2010" in the islands Raikoke, Matua, Ekarma are shown. The estimation of modern state of active volcanoes on these islands is given. New data on history of the eruptive activity of the Peak Sarychev Volcano are cited.

The chronology, dynamics, and parameters of seven large eruptions of Avacha Volcano were reconstructed for its IAv andesitic period 7250-370014C years B.P., which began after a >2000-year period of relative quiescence. Their juvenile (andesitic pyroclastics) and resurgent products are described, and the geological and geomorphological consequences are evaluated. The largest eruption occurred 715014C years B.P. (8-10 km3 of erupted material). The subsequent events occurred 5700 (≥0.34 km3), 5600 (≥0.4 km3), 5500 (>1.34 km3), 5000 (≥0.5 km3), 4500 (>1.1 km3), and 4000 (≥0.6 km3) 14C years B.P. The erupted rocks were dominated by tephra; pyroclastic flows occurred only during the events of 5500 and 5000 years ago. It is believed that most of the eruptions produced acid peaks of varying intensity in the Greenland ice sheet.

The first results of tephrachronological researches of the Sarychev Peak volcano, the Matua Island, (Central Kuriles) are represented including the reconstruction of its eruptive history in the Holocene. Based on the study of the distribution of petrogenous oxides and microelements in the tephra sampled layer-by-layer from the reference section of soil-pyroclastic cover of Matua Island, a general trend of the geochemical evolution of the volcano products during the Holocene epoch is traced, their typification was made. The horizons of the transition ashes were identified.

Nineteen Holocene eruptive centers (cinder cones with lava flows and maars) were located and described in the Avacha horst and anticline zone west of the East Kamchatka volcanic area. A tephrochronological study and the carbon-14 dating of soil and plant remains ranked the eruptive centers into three age groups: 11 000-7700, 3000-2500, and 1200-600 carbon-14 years B. P. The eruptive centers of these groups are believed to have been operating roughly synchronously with the periods of active magma injection in the East Kamchatka volcanic area. Eruptive histories were reconstructed for some of the volcanic centers. The structural and tectonic settings, geographical positions, and elevations of the centers were analyzed. The volume (1.1 km3) and weight (1.8 X 10^9 metric tons) of the erupted rocks were evaluated. The productivity of the plateau basalt volcanism was found to be 10-100 times lower than the plateau basalt productivity in the area of grabens and synclines, possibly, because of the more shallow basement in the horsts and because of the fact that the compression of the crust under uplifting conditions hampered the magma rise toward the surface. Most of the lavas and pyroclastics are basalts of the medium-potassic series, some having medium (54-62) and some elevated (65-70) Kmg values.