Large debris avalanches and associated eruptions in the Holocene eruptive history of Shiveluch Volcano, Kamchatka, Russia

 Shiveluch Volcano, located in the Central Kamchatka Depression, has experienced multiple flank failures during its lifetime, most recently in 1964. The overlapping deposits of at least 13 large Holocene debris avalanches cover an area of approximately 200 km² of the southern sector of the volcano. Deposits of two debris avalanches associated with flank extrusive domes are, in addition, located on its western slope. The maximum travel distance of individual Holocene avalanches exceeds 20 km, and their volumes reach ∼3 km³. The deposits of most avalanches typically have a hummocky surface, are poorly sorted and graded, and contain angular heterogeneous rock fragments of various sizes surrounded by coarse to fine matrix. The deposits differ in color, indicating different sources on the edifice. Tephrochronological and radiocarbon dating of the avalanches shows that the first large Holocene avalanches were emplaced approximately 4530–4350 BC. From ∼2490 BC at least 13 avalanches occurred after intervals of 30–900 years. Six large avalanches were emplaced between 120 and 970 AD, with recurrence intervals of 30–340 years. All the debris avalanches were followed by eruptions that produced various types of pyroclastic deposits. Features of some surge deposits suggest that they might have originated as a result of directed blasts triggered by rockslides. Most avalanche deposits are composed of fresh andesitic rocks of extrusive domes, so the avalanches might have resulted from the high magma supply rate and the repetitive formation of the domes. No trace of the 1854 summit failure mentioned in historical records has been found beyond 8 km from the crater; perhaps witnesses exaggerated or misinterpreted the events. Received: 18 August 1997 / Accepted: 19 December 1997     

Rate of collisional deformation in Kamchatsky Peninsula,Kamchatka

Detailed data are discussed on the rate of Holocene horizontal and vertical movements along a fault in the southeastern Kamchatsky Peninsula, which is situated between the converging Aleutian and Kamchatka island arcs. The fault is the northern boundary of the block invading into the peninsula under pressure of the Komandorsky Block of the Aleutian arc. The rate of right-lateral slip along the fault was increasing in the Holocene and reached 18–19 mm/yr over the last 2000 years and 20 mm/yr by contemporary time. Comparison of these estimates with those that follow from offsets of older rocks also indicates acceleration of horizontal movements along the fault from the early Quaternary to the present. The results obtained from rates of GPS station migration show that about half the rate of the northwestern drift of the Komandorsky Block is consumed for movement of the block of the southern side of the fault. The remainder of movement of the Komandorsky Block is consumed for movements (probably, underthrusting) at the eastern continental slope of the Kamchatsky Peninsula.     

Formation of large-scale dust lanes in spiral arms of galaxies

We consider the interaction of interstellar dust grains with a galactic shock in the gaseous component. Typical parameters of dust grains and spiral density waves imply that the formation of large-scale dust lanes at the front of a galactic shock is possible only in models taking into account a self-focusing phenomenon. In the case of an isothermal flow of interstellar gas through a spiral arm in a model with a gaseous disk of variable thickness, dust lanes can be projected onto the region of increased gas density, although this is not associated with a galactic shock. The dust density peak derived from the classical model of a galactic shock (isothermal flow and a constant thickness of the gaseous disk) is appreciably shifted downstream of the gas flow, so that it does not outline the gas density maximum.     

Geological–Geophysical and Oceanographic Research in the Sea of Japan,Tatar Strait,on Cruise 61 of the R/V Akademik Oparin

Oceanology - The paper presents brief results of comprehensive studies of the water area of the Tatar Strait and Sea of Japan obtained on cruise 61 of the R/V “Akademik Oparin” in...     

Staurolite and associated minerals from rare-metal granite pegmatites

Staurolite has been found in rare-metal granite pegmatites for the first time. The mineral is formed as a metastable phase oversaturated with silica and transformed into the common staurolite with emulsion disseminations of quartz. Staurolite selectively concentrates d elements of the Fe group (from V to Zn) and LREE (La-Eu).     

The effect of atmospheric circulation on the evolution and radiative forcing of smoke aerosol over European Russia during the summer of 2010

The evolution of smoke plume over European Russia (ER) during the massive forest and peatbog fires of summer 2010 has been studied using observations of aerosol optical depth (AOD) from MODIS instruments (both Aqua and Terra platforms), objective analysis of meteorological fields performed at the Russian Hydrometeorological Research Center, NCEP/NCAR reanalysis, as well as upper air data. A relation between the structure inhomogeneities of the AOD field and regional atmospheric circulation has been found. It is shown that, on August 5–9, 2010, the maximum of smoke pollution did complete turn around Moscow, while remaining at a distance of 200 to 650 km from the megacity. Both regionally averaged shortwave aerosol radiative forcings (ARFs) at the top and the bottom of the atmosphere are estimated for the period of extreme smoke pollution over ER. The spatial distributions of ARF values over the territory of the region and the estimates of the local and spatially distributed thermal effects of smoke aerosol are given. It is shown that, on August 5–9, 2010, the spatial distribution of AOD and the calculated thermal effects of smoke aerosol were in agreement with the spatial distributions of air-temperature anomalies observed in the lower 1.5-km layer of the atmosphere. MODIS’s AOD data obtained during the wildfires were validated by AOD observations from the CIMEL sun photometer operated at the AERONET station Zvenigorod.