Abstract Gases and aerosols from the 2012–13 effusive eruption of Tolbachik basaltic volcano, Kamchatka, were sampled in February and May, 2013, from a lava tube window located 300 m from the eruptive crater; temperature at the sampling point was 1060–1070 °C. The chemical and isotopic compositions of the sampled gases (92.4 H2O, 3.5 CO2, 2.3 SO2 on average; δD from − 25.0 to − 38.6‰) correspond to a typical volcanic arc gas without dilution by meteoric or hydrothermal water. Halogen contents in the gases (1.37 HCl, 0.5 HF) were higher than average arc values. The total amount of analyzed metallic and metalloid (trace) elements in the gas exceeded 665 ppm. Six most abundant trace elements, K (250 ppm), Na (220 ppm), Si (74 ppm), Br (48 ppm), Cu (21 ppm) and Fe (12 ppm), accounted for 95 of the total content of trace elements in the gas. The gases contained 24 ppb Re, 12 ppb Ag, 4.9 ppb Au and 0.45 ppb Pt. Refractory rock-forming elements (Mg, Al, Ca) and some other elements such as Ba and Th were transported mainly in the form of silicate microspheres and altered rock particles. The concentrations of metals in the eruptive Tolbachik gases are higher than the corresponding concentrations in high-temperature fumaroles worldwide, although the mutual ratios of the elements are approximately the same. The gas/magma partition coefficients of eleven elements exceed unity, including the non-metals F, S, Cl, Br, As, Se and Te and the rare metals Cd, Re, Tl and Bi. Despite the relatively low concentrations of trace elements in the volcanic gases at the highest temperatures, superficial magma degassing provides information on the sources and sinks of metals.

Two volcanoes were tested using the titanomagnetite method in order to detect the magma chamber depth. Curie temperature of andesite tephra shows that the magmatic chamber was situated on the depth of 18±7 km under Avachinsky Volcano ~5 Ka ago, but one of the basalt-andesite tephra from Avachinsky results the chamber depth of 32±6 km ~3 Ka ago. This method applied to the lava from Tolbachik Fissure Eruption (TFE) shows a chamber depth of 47±5 km. This result is inconsistent slightly with the depth of 35±6 km obtained by our microzond analysing of element composition of titanomagnetite grains into lava sample from earlier phase of the same eruption. This two different results between TFE lava samples may occur from magma differentiation or this is a methodical or occasional error. To know true it needs a sample statistics. At present, more microzond data from Tolbachik Fissure Eruption are being analyzed.

Ландшафтно-ситуационный анализ описаний событий, приводимых С. П. Крашенинниковым, показывает, что в районе вулкана Плоский Толбачик произошло два самостоятельных — в январе 1739 и в декабре 1740 годов извержения. При этом мощное пароксизмальное извержение 1739 г. в центральном кратере вулкана Плоский Толбачик сопровождалось выпадением пепла на расстояниях до 50 вёрст от вершины вулкана. А двойное (Конус Красный и прорыв Звезда) извержение 1740 г. привело к выпадению пепла на расстояниях до 150 км, а также к погребению и возгоранию большого массива горной тайги в юго-юго-западной части Толбачинского дола. Помимо этого приводятся данные о ранее неизвестных извержениях Плоского Толбачика в 1728 и 1927 годах.

На основании наиболее общих распределений, характеризующих извержения вулканов (графиков их повторяемости, площадей, объемов изверженного материала), обосновывается гипотеза о постоянной, независимой от вулканического процесса, толщине магматического очага как свойстве земной коры. Гипотеза обсуждается в свете концепции блоковой геосреды и ее волновых геодинамических движений.