With the use of the method of low-frequency microseismic sounding, the configuration of the magmatic feeding system of the Tolbachinsky Dol—a regional zone of areal basaltic volcanism in the southern part of the Klyuchevskoy volcano group in Kamchatka—is studied. The initial data are obtained by a step-by-step recording of the background microseismic noise in 2010–2015 within a thoroughly marked-out survey area covering the zones of fissure eruptions in 1975–1976 and 2012–2013 and, partly, the edifice of thePloskii (flat) Tolbachik volcano. The depth sections ref lecting the distributions of the relative velocities of seismic waves in the Earth’s crust are constructed. For a more reliable interpretation of the revealed deep anomalies, the results of independent geological and geophysical studies are used. The ascertained low-velocity structures are closely correlated to the manifestations of present-day volcanism. It is shown that the feeding structure of the Tolbachinsky Dol is spatially heterogeneous, incorporating subvertical and lateral pipe-shaped magma conduits, closely spaced magma feeding channels, and shallow magma reservoirs. A long-lived local transcrustal magma conducting zone is revealed, and regularities in the deep structure of the feeding systems of fissure eruptions are identified. The configuration of the established subvertical magma conduits permits basalts moving to rise to the surface by different paths, which, inter alia, explains the contrasting magma compositions observed during a single eruption. Thus, based on the instrumental data, it is shown that the magmatic feeding structure of the Tolbachinsky Dol has a number of specific peculiarities and is significantly more complicated than has been previously thought about the areal volcanic fields.

The paper shows that the abnormally low values of longitudinal wave velocities, typical even for dense differences, are an important feature of Holocene effusive rocks of medium-basic composition. In order to explain this phenomenon, a series of experiments was conducted to saturate the samples with a phosphor followed by a study of the structure of the pore-fractured space on a fluorescent microscope. The experiments showed that low P-wave velocities are caused by the network of the finest microcracks formed in the rock during cooling and crystallization of the magmatic melt.

The paper presents data on identified and described short-term local (1955−1976) enhanced volcanic activity within the Northern Group at the Central Kamchatka Depression and regional disasters (1907-1976), clearly revealed within Kamchatka Peninsular and the Kurile Islands. In scale (volume is about 9 km3, weight of erupted and replaced productswas calculated to be about 16×109 t), the local volcanic disaster was the most powerful in Kamchatka and Kurile Islands over the period of the last 2000 years. This volume exceeds 80% of ~19×109 t totally erupted by all volcanoes over the same period of time. Over the period 1907−1976, the Kamchatka and Kurile volcanoes erupted and transported about 29.5×109 t of juvenile and resurgent material while other volcanoes in the world erupted about 122×109 t.

Here we present the results of the successful application of VIIRS satellite data for monitoring and reconstruction of the eruption history of Snow volcano (Chirpoi Island, Kuriles) in 2012–2017. We used Nightfire algorithm to accomplish our tasks. This algorithm differs significantly from the other similar systems due to simultaneous usage of numerous diapasons of the infrared spectra (from near to long ranges) together with the data of the visible spectra, while most of the other algorithms (for example, MODVOLC and MIROVA) use one or two diapasons from the middle or long parts of the infrared spectra. Our research shows that the maximal thermal radiation power (MW) was observed from November 2012 to January 2013. During this period, first and most voluminous portion of lava flow was produced. There are four more well-distinguished periods of this eruption: September – October 2013; March – June 2014; August – November 2014; April – June 2015. All of them correspond to the impulses of the fresh lava eruptions, although the thickness of these lava flows is smaller compared to the first period.

Studies of Klyuchevskoy Volcano eruptions have revealed a new type of explosive activity classified as pulsating spouting of incandescent bombs. These are series of abrupt impulses of increased rate of bomb ejection which occur at fixed intervals of first few seconds and accompany the weaker spouting. Analyses of published data and video records has shown that the same type of eruptive activity is typical for Tolbachinsky, Kilauea and Etna volcanoes which produce liquid andesite-basaltic magmas. In order to investigate the mechanism of pulsating spouting, authors upgraded the Complex Apparatus for Modeling Basaltic Eruptions (KAMBE) that had been designed earlier. A series of laboratory experiments in a transparent column (h = 16.6 м, Ø = 50 mm) allowed us to reveal a new gas-hydrodynamic regime of foamy bubble clusters. Analysis of natural volcanic and laboratory processes allows assuming that pulsating spouting of incandescent bombs is preceded by the regime of foamy bubble clusters occurring in the gas-liquid magmatic flow ascending along a volcano conduit.

Fieldworks at Alaid volcano in 2018, Atlasov Island, the Kuriles