Sedimentary and volcanic-sedimentary rocks from natural exposures on the Phu-Qui and Katuik volcanic islands (Vietnam Shelf) have been analyzed for their elemental composition. Mineralogically and petrochemically, sandstone rocks of Phu-Qui Island are petrogenic compounds and refer to subarkose. Judging by the prevalence of quartz and feldspar, by the dominance of sialic association in the heavy mineral fraction as well as by the pattern of major, minor and rare-earth element distribution, the main sources of clasts were intrusive and metamorphic rocks of the mature continental crust, and sedimentation settings correspond to passive continental margins. The Middle Pleistocene volcanic-sedimentary rocks of the Phu-Qui – Katuik group of islands are composed of pyroclastic material of mafic composition close to the basalts from trachybasalt-trachytic and alkaline basaltic series of Vietnam, which possess intraplate characteristics and relate to the existing here extension settings. The sedimentation occurred in subaerial environment near the centers of volcanic eruptions.

Purpose. Ash clouds and plumes arising due to explosive eruptions of the volcanoes of Kamchatka and the Kuril Islands pose a great danger to aviation flights. In this regard, the urgent and important task is to predict and analyze distribution of volcanic ash in the atmosphere . To solve this task, AIS "Signal"was designed. It includes a modelling subsystem using the PUFF model. It allows predicting the direction, speed and height of the propagation of ash clouds and plumes in the atmosphere. At the same time, for more accurate assessment of the danger of ash clouds and plumes, it is necessary to determine not only their qualitative, but also quantitative characteristics, for example, the concentration of ash at the flight levels of aircrafts, the amount of ash deposited on the surface, etc. To solve this problem, research was done to expand the capabilities of the AIS "Signal"by integrating the Eulerian FALL3D model into it. The present article presents the results of this work.
Methodology. Implementation of system and user interfaces for automating the processes of collecting and preparing auxiliary data (reference information about volcanoes, meteorological data, etc.), performing numerical calculations in the FALL3D model and visualizing the obtained results both were carried out on the basis of similar interfaces created earlier in AIS “Signal” for the PUFF model. All these features significantly accelerate the process of integration the FALL3D model into the existing AIS modelling subsystem. Implementation of the operating modes of the subsystem and evaluating the efficiency of its functioning were carried out as part of the study of ash clouds and plumes propagation which are formed during explosive events of the Kamchatka volcanoes.
Findings. As part of the integration of the FALL3D model into the modelling subsystem, informational interaction of its software components with the services of AIS “Signal” was organized. Algorithms for the formation of collections of meteorological data necessary for the functioning of the model were proposed and implemented. User interfaces have been created that allow specialists to calculate the characteristics of ash clouds with the ability to set detailed initial parameters for an explosive event and model settings.
Originality. The integration of the FALL3D model in the AIS “Signal” significantly expands its ability to predict propagation of ash clouds and plumes formed during explosive eruptions of the volcanoes of Kamchatka and the Kuril Islands. In addition to the instruments for determining the direction, speed, and height of the spread of volcanic ash, tools have been developed to determine the ash concentration at the flight levels of aircrafts, as well as the thickness and mass of the ash falling on the surface of the Earth. Numerical experiments have showed a good agreement between Originality. The integration of the FALL3D model in the AIS “Signal” significantly expands its ability to predict propagation of ash clouds and plumes formed during explosive eruptions of the volcanoes of Kamchatka and the Kuril Islands. In addition to the instruments for determining the direction, speed, and height of the spread of volcanic ash, tools have been developed to determine the ash concentration at the flight levels of aircrafts, as well as the thickness and mass of the ash falling on the surface of the Earth. Numerical experiments have showed a good agreement between the obtained modelling results and the satellite data.the obtained modelling results and the satellite data.