Title: Research Scientist
Country/Region: Russia
Period: 2024/7/1-2025/6/30
Theme: Study of the explosive eruption jets with the experimental and numerical approaches and comparison with real seismic data
Host: Mie ICHIHARA
Introduction: Dr. Nataliya Galina is a researcher from the Institute of Physics of the Earth, Russian Academy of Sciences. In 2023 she obtained her Ph.D. at University of Grenoble-Alpes, Institute of Earth Sciences. Her main research interest is volcano seismology, and the thesis was focused on volcanic earthquakes observed beneath the Klyuchevskoy volcano group in Kamchatka, Russia. Her main hard skill is data processing including machine learning in order to extract information from seismological data for further analysis. Then she uses different approaches, such as statistical analysis and numerical modelling, to understand the origin of deep long period earthquakes which are believed to be precursors of volcanic unrest. During her stay at ERI, Nataliya will study the behaviour of explosive eruption jets using experimental and numerical approaches. Combining and comparing them with field data should broaden the knowledge and understanding of volcanic systems.
Research Report:
Final report by Galina Nataliya
Although the initial research topic for the stay at ERI was linked with the study of eruptive volcanic jets, I also participated in another project run by Prof. Ichihara and dedicated to volcano monitoring. Thus, the summary of the results obtained during my stay can be summarized in the following way:
Refining the widespread model of eruptive jets [Brodsky et al., 1999] with the experimental approach;
Linking the experiment on eruptive jets with the seismological data from the 2022 Hunga Tonga–Hunga Haʻapai (HTHH) eruption;
Probing the seismic background level (SBL) technique using the data from the Klyuchevskoy volcano group (Kamchatka).
Refining the widespread model of eruptive jets [Brodsky et al., 1999] with the experimental approach.
The current model of eruptive jets proposed by Brodsky et al. (1999) links the reaction force F and the mass discharge rate as F=m ̇v (v is the exit velocity of the erupted material). However, Tada et al. (2023) theoretically predicted that the reaction forceF includes not only the momentum change but also the pressure difference between the interior and the vent, and the friction force on the vent wall. Thus, when the pressure difference and friction are considered, F=3/2 m ̇v [*].
Using the apparatus designed by Tada et al. (2023) (Fig. 1), we continued their series of experiments. With the obtained measurements of the reaction force and other parameters, we investigated the relation (*) with depending on the nozzle shapes and nozzle size (area). Also, we compared incompressible (water) and compressible (air) jets.
For water jets, the relationship F_jet ρA=3/2 m ̇^2 is satisfied for all nozzles (Fig. 2). However, not all air jets satisfy that ratio, especially for significant values of m ̇ (Fig. 3). We are going to revise the theory of compressible jets, and the series of experiments with the other nozzle shapes have been carried out.
The collaboration on this project will be continued. We are going to change the parameters of the fluid, such as density and viscosity, as well as the gas-liquid mixing ratio, and investigate the effect of these variables on the ratio [*].
The results from this part have been presented at the JpGU Meeting 2025 and the IAVCEI General Assembly 2025.
Although the initial research topic for the stay at ERI was linked with the study of eruptive volcanic jets, I also participated in another project run by Prof. Ichihara and dedicated to volcano monitoring. Thus, the summary of the results obtained during my stay can be summarized in the following way:
Refining the widespread model of eruptive jets [Brodsky et al., 1999] with the experimental approach;
Linking the experiment on eruptive jets with the seismological data from the 2022 Hunga Tonga–Hunga Haʻapai (HTHH) eruption;
Probing the seismic background level (SBL) technique using the data from the Klyuchevskoy volcano group (Kamchatka).
Refining the widespread model of eruptive jets [Brodsky et al., 1999] with the experimental approach.
The current model of eruptive jets proposed by Brodsky et al. (1999) links the reaction force F and the mass discharge rate as F=m ̇v (v is the exit velocity of the erupted material). However, Tada et al. (2023) theoretically predicted that the reaction forceF includes not only the momentum change but also the pressure difference between the interior and the vent, and the friction force on the vent wall. Thus, when the pressure difference and friction are considered, F=3/2 m ̇v [*].
Using the apparatus designed by Tada et al. (2023) (Fig. 1), we continued their series of experiments. With the obtained measurements of the reaction force and other parameters, we investigated the relation (*) with depending on the nozzle shapes and nozzle size (area). Also, we compared incompressible (water) and compressible (air) jets.
For water jets, the relationship F_jet ρA=3/2 m ̇^2 is satisfied for all nozzles (Fig. 2). However, not all air jets satisfy that ratio, especially for significant values of m ̇ (Fig. 3). We are going to revise the theory of compressible jets, and the series of experiments with the other nozzle shapes have been carried out.
The collaboration on this project will be continued. We are going to change the parameters of the fluid, such as density and viscosity, as well as the gas-liquid mixing ratio, and investigate the effect of these variables on the ratio [*].
The results from this part have been presented at the JpGU Meeting 2025 and the IAVCEI General Assembly 2025.
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Fiscal Year: 2024
Fiscal Year: 2024