This paper is concerned with the geological history and petrology of a major polygenic volcanic edifice dating back to Upper Pleistocene to Holocene time. This long-lived volcanic center is remarkable in that it combines basaltic and trachybasaltic magmas which are found in basaltic andesite and trachybasaltic– trachyandesite series. The inference is that the coexisting parent magmas are genetically independent and are generated at different sources at depth in an upper mantle volume. The associated volcanic rocks have diverse compositions, stemming from a multi-stage spatio–temporal crystallization differentiation of the magmas and mixing of these in intermediate chas.

Изучено строение подводного вулканического массива Рикорда, состоящего из четырех сливающихся по основанию вулканических построек, и имеющего, скорее всего, четвертичный возраст. На начальных этапах жизни вулканического массива изливались базальтовые и андезибазальтовые лавы. Высокие значения естественной остаточной намагниченности драгированных пород обусловлены большим содержанием однодоменных и псевдооднодоменных зерен титаномагнетита и магнетита. Установлены направления подводящих каналов и наличие периферических магматических очагов. Построена объемная модель центральной части вулканического массива Рикорда, в которой выделено десять крупных магнитовозмущающих блоков, которые, вероятнее всего, являются застывшими субвертикальными подводящими каналами.

The primary goal of this paper is to summarize all of the published data on the Tolbachik volcanic massif in order to provide a clear framework for the geochronologic, petrologic, geochemical and to a lesser extent the geophysical and tectonic characteristics of the Tolbachik system established prior to the 2012–2013 eruption. The Tolbachik massif forms the southwestern part of the voluminous Klyuchevskoy volcanic group in Kamchatka. The massif includes two large stratovolcanoes, Ostry (“Sharp”) Tolbachik and Plosky (“Flat”) Tolbachik, and a 70 km long zone of the basaltic monogenetic cones that form an arcuate rift-like structure running across the Plosky Tolbachik summit. The Tolbachik massif gained international attention after the 1975–1976 Great Tolbachik Fissure Eruption (GTFE), which was one of the largest eruptions of the 20th century and one of the six largest basaltic fissure eruptions in historical time. By the end of the GTFE, 2.2 km3 of volcanic products of variable basaltic compositions with MORB-like isotopic characteristics covered an area of > 1000 km2. During the following three decades more than 700 papers on various aspects of this eruption have been published both in national and international journals. Although the recent 2012–2013 eruption, which is the main topic of this volume, was not as long as the {GTFE} in duration or as large in area and volume of the erupted deposits, it brought to the surface a unique volcanic material never found before. In order to understand the data from new eruptions and make significant progress towards a better understanding of the Tolbachik magmatic system it is important to be able to put the new results into the historic context of previous research.

Annually, from 3 to 6 Kamchatkan volcanoes produce eruptions, during which the explosions eject ash to 10-15 km a.s.l., and ash clouds spread thousands of kilometers from volcanoes. Ash clouds pose a serious threat to the modern jet aviation. Scientists of KVERT have conduct daily monitoring of Kamchatka volcanoes since 1993, to mitigate volcanic hazards to airline operations and population. Since 2014, satellite monitoring of volcanoes they carried out with the VolSatView (Remote monitoring of active volcanoes of Kamchatka and the Kuril Islands) (http://volcanoes.smislab.ru) IS. The system utilize all the available satellite data, weather and video observations to ensure continues monitoring and study of volcanic activity in Kamchatka. The VolSatView work with distributed information resources and computation systems. This work was supported by the Russian Science Foundation, project No. 16-17-00042.