We report new electron microscopy and high-precision EMP data on tephra from five modern (2009-2011)
eruptions from Kamchatka and Kurile Islands volcanoes. All the studied tephra contain fresh volcanic glass.
Fresh magmatic material prevails in Kliuchevskoi and Sarychev Peak tephra as well as in tephra erupted from
Kizimen volcano in January 2011. Tephra from the initial eruptions of Kizimen volcano (December 2011)
and from Shiveluch and Koriaksky eruptions mainly consist of crystallized rock fragments and crystals
with subordinate amount of glass. Most of the analyzed volcanic glass shards have normal alkalinity and
moderate-K composition as the majority of Kamchatkan magmas. Composition of glasses from the 2010
eruptions of Kliuchevskoi and Shiveluch are consistent with the expected ones for the current period of
their evolution. Composition of volcanic glass from the 2010-2011 eruptions from Kizimen is identical to
that from its largest pre-historic eruptions. This fact implies that a magmatic chamber of stable rhyolitic
composition has been present under Kizimen volcano for at least 10 kyr.

Studies of melt inclusions in minerals of some Kamchatka volcanoes are reported. We studies andesite basalts and andesites in volcanoes situated in the Central Kamchatka Depression (Shiveluch and Bezymyannyi) and in the East Kamchatka Volcanic Belt (Avacha and Karymskii). In addition, we studied the basalts of the 1996 eruption in the Karymskii Volcanic Center and the dacites on Dikiy Greben Volcano, southern Kamchatka. We used homogenization of melt inclusions and the analysis of chilled glass in these inclusions with electron and ion microlog sondes. More than 200 melt inclusions have been studied in minerals from 25 volcanic rock samples. It was found that the compositions of melt inclusions in andesite phenocrysts strongly vary in basicity; the content of SiO 2 varies between 56 and 80% wt, increasing silica percentage going along with decreasing concentrations of Al2O3, FeO, MgO, CaO and increasing concentrations of Na2O and K2O. Most (about 80%) of glass in the inclusions have dacite and rhyolite compositions. However, the compositions of acid melts (SiO2 > 65% wt) which produce the andesites are significantly different from those which produce the dacites and rhyolites as to the content of TiO2, FeO, MgO, CaO and K2O. Comparison between the compositions of melt inclusions from andesite plagioclase on the four volcanoes showed considerable differences. The basic andesites (56-59% SiO2) of Bezymyannyi Volcano exhibit a large scatter in inclusion composition (SiO2 = = 56-81%). The more acid andesites (SiO2 = 61%) of Shiveluch Volcano show a lower scatter in inclusion composition (SiO2 = 67-79%). The melt inclusions in the Karymskii andesites are amore basic. They are enriched with Fe, Ti, Ca, Mg, P, Na and are considerably depleted in K. The melts that produce the Karymskii andesites are probably less differentiated. On the volcanoes under study we also found high-potassium melts (K 2O = 3.8-6.8% wt), independent of the concentrations of SiO2 in them (the range here is between 51.4 and 77.2% wt). The melts differ considerably between volcanoes as to the concentration of volatiles. The greatest concentrations of H2O are found in the Shiveluch melts (3.0 to 7.2% wt with the mean equal to 4.7% wt) and on Avacha (4.7-4.8% wt), lower concentrations being in the melts of Dikiy Greben (0.4-1.8% wt) and Bezymyanyi (<1% wt). Using fluid inclusions of CO2 found in andesite plagioclase of Shiveluch Volcano, we inferred a pressure of 350-1600 bars, which corresponds to the depth of the magma chamber equal to 1.5-6 km. We found the concentrations of 17 admixture elements in glass of melt inclusions sampled from the plagioclase of four volcanoes (Avacha, Bezymyannyi, Dikiy Greben, Shiveluch). Judging by the concentrations of these elements, the melts here studied are similar to the typical island arc magmas.