Teleseismic receiver functions (RFs) from a yearlong broadband seismological experiment in Kamchatka reveal regional variations in the Moho, anisotropy in the supra-slab mantle wedge, and, along the eastern coast, Ps converted phases from the steeply dipping slab. We analyze both radial- and transverse-component RFs in bin-averaged epicentral and backazimuthal sweeps, in order to detect Ps moveout and polarity variations diagnostic of interface depth, interface dip, and anisotropic fabric within the shallow mantle and crust. At some stations, the radial RF is overprinted by near-surface resonances, but anisotropic structure can be inferred from the transverse RF. Using forward modeling to match the observed RFs, we find Moho depth to range between 30 and 40 km across the peninsula, with a gradational crust –mantle transition beneath some stations along the eastern coast. Anisotropy beneath the Moho is required to fit the transverse RFs at most stations. Anisotropy in the lower crust is required at a minority of stations. Modeling the amplitude and backazimuthal variation of the Ps waveform suggests that an inclined axis of symmetry and 5 – 10% anisotropy are typical for the crust and the shallow mantle. The apparent symmetry axes of the anisotropic layers are typically trench-normal, but trench-parallel symmetry axes are found for stations APA and ESS, both at the fringes of the central Kamchatka depression. Transverse RFs from east-coast stations KRO, TUM, ZUP and PET are fit well by two anisotropic mantle layers with trench-normal symmetry axes and opposing tilts. Strong anisotropy in the supraslab mantle wedge suggests that the mantle ‘‘lithosphere’’ beneath the Kamchatka volcanic arc is actively deforming, strained either by wedge corner flow at depth or by trenchward suction of crust as the Pacific slab retreats.

Tyatya Volcano, situated in Kunashir Island at the southwestern end of Kuril Islands, is a large composite stratovolcano and one of the most active volcanoes in the Kuril arc. The volcanic edifice can be divided into the old and the young ones, which are composed of rocks of distinct magma types, low‐ and medium‐K series, respectively. The young volcano has a summit caldera with a central cone. Recent eruptions have occurred at the central cone and at the flank vents of the young volcano. We found several distal ash layers at the volcano and identified their ages and sources, that is, tephras of ad 1856, ad 1739, ad 1694 and ca 1 Ka derived from three volcanoes of Hokkaido, Japan, and caad 969 from Baitoushan Volcano of China/North Korea. These could provide good time markers to reveal the eruptive history of the central cone, which had continued intermittently with Strombolian eruptions and lava flow effusions since before 1 Ka. Relatively explosive eruptions have occurred three times at the cone during the past 1000 years. We revealed that, topographically, the youngest lava flows from the cone are covered not by the tephra of ad 1739 but by that of ad 1856. This evidence, together with a report of dense smoke rising from the summit in ad 1812, suggests that the latest major eruption with lava effusion from the central cone occurred in this year. In 1973, after a long period of dormancy, short‐lived phreatomagmatic eruptions began to occur from fissure vents at the northern flank of the young volcano. This was followed by large eruptions of Strombolian to sub‐Plinian types occurring from several craters at the southern flank. The 1973 activity is evaluated as Volcanic Explosivity Index = 4 (approximately 0.2 km3), the largest eruption during the 20th century in the southwestern Kuril arc. The rocks of the central cone are strongly porphyritic basalt and basaltic andesite, whereas the 1973 scoria is aphyric basalt, suggesting that magma feeding systems are definitely different between the summit and flank eruptions.

Basing on the analysis of the data of detailed geophysical investigations in the Unneivayam Paleogene volcanic field, Koryak Upland, linear systems (zones) of volcanic domal and caldera structures are distinguished and characterized. Their relationship with ore fields and structures is analyzed, and new ore targets are predicted.

Кратер Чаша находится на Южной Качатке в центральной части лавового плато Толмачев дол района интенсивного базальтового вулканизма в плейстоцене-голоцене. Кратер сформировался 4628 ± 90 14С лет назад [9] во время мощного одноактного извержения. Продукты извержения представлены вблизи кратера мощной стратифицированной пачкой тефры, на удалении мощность горизонта быстро убывает. Тефра этого извержения [9] распространялась на северо-восток и покрывала территорию более 15000 км2. Общий объем тефры около 1.0-1.1 км3, в пересчете на плотную породу - 0.7-0.8 км3. Внешний облик ювенильных продуктов колеблется от светло-желтой хрупкой, пористой пемзы до светло-серых плотных, невспененных обсидианоподобных обломков. Однако химический состав всех разностей довольно однороден - это риолиты (73-75 вес. % SiO2) с повышенным содержанием К2О (до 3.8 вес. %). Все разности содержат небольшое количество вкрапленников (около 1%), представленных плагиоклазом, биотитом и, возможно, амфиболом. Сравнение химических характеристик изверженных продуктов кратера Чаша и Бараньего Амфитеатра на северном подножии вулкана Опала дает нам основания предположить, что оба извержения питались из одного долгоживущего кислого магматического очага, сформировавшегося около 30000-40000 14С л.н., перед образованием кальдеры вулкана Опала.