Magmatic Activity Research Group

Magmatic activity research group is conducting researches to model various volcanic phenomena for forecasting eruption and evolution of volcanic activity in cooperation with the volcanic activity research group.

For volcanic hazard mitigation, it is important to predict the eruption style and its evolution. Recent development of the monitoring tools enables detection of precursory phenomena, however it is still quite difficult to predict eruption style and its evolution. Therefore, we need to know more examples of past eruptive activities to extract common features of eruption style and its evolution and to understand their controlling process and mechanisms. We, magmatic activity research group conduct researches to model volcanic phenomena with various approaches including geochemical and petrological analyses of eruption products, observation of volcanic gas, electro-magnetic phenomena and ground deformation, various laboratory and numerical experiments, in order to develop methods to predict evolution of eruptive activities.

To group homepage https://unit.aist.go.jp/ievg/magma-rg1/index.html (in Japanese)

A resistivity structure was obtained from three-dimensional inversion of magnetotelluric data in and around Aso caldera (Crosses in the left figure are observation stations); a) horizontal section at depths of 5-6km, b) and c) east-west and north-south vertical sections through Naka-dake crater, respectively. Conspicuous low resistive body (< 1 Ω•m) northward dipping from Naka-dake crater, reveals a magma path associated with the recent active eruptions.

Member

Akiko Tanaka (Leader, Group)

I am interested in understanding the fundamental physical processes and mechanisms within the Earth system. My research interests are span (but are not limited to) the thermal and mechanical structure of the lithosphere and geodynamic applications of synthetic aperture radar interferometry.

Genji Saito (Senior Researcher)

Magma ascent, degassing, eruption processes on active volcanoes and present condition and evolution of their magma plumbing systems are investigated based on petrological studies of volcanic rocks and melt inclusion analyses.

Nobuo Matsushima (Senior Researcher)

I conduct geothermal and electromagnetic observations at active volcanoes. Main targets are surface temperature distribution, heat discharge rate, self-potential distribution and resistivity structure. These results are used as boundary conditions for numerical simulations, and modeling of magma-hydrothermal systems at various volcanoes is developed.

Akihiko Tomiya (Senior Researcher)

I am interested in the mechanism of volcanic eruptions, in particular the beginning and sequence. I am investigating pre-eruptive magmatic processes in magma chambers and volcanic conduits, using petrographical methods, such as: analyzing zoning profiles of phenocrysts (e.g., plagioclase and magnetite) to reveal changes in temperature and pressure or injection of mafic magma; high-pressure melting experiments for estimating pre-eruptive magmatic conditions or magma ascending processes.

HP: https://staff.aist.go.jp/a.tomiya/tomiyae.html

Ryunosuke Kazahaya (Senior Researcher)

My main interests are modeling of eruptive activities and/or movement of magma at a depth within a volcano by way of volcanic gases study. Degassing process of magma is crucial to get insights of volcanic activities. Recently I've focused on a linkage between volcanic gas and geophysical data in order to comprehend volcanic phenomena.

HP: https://staff.aist.go.jp/von.kazahaya/

Masaaki Morita (Researcher)

My research interests mainly lie on an evaluation of the degassing process based on measurements of volcanic gas compositions and emission rates. My skills are volcanic gas composition measurements using Multi-GAS (Multi-component Gas Analyzing System) and SO2 flux measurements using UV remote sensing techniques. I am also interested in migration of hydrothermal fluids focusing on diffuse degassing from volcano flanks.

HP: https://staff.aist.go.jp/aki.morita/

Kaori Seki (Researcher)

The mechanism of phreatic eruption has not been well understood yet, although we observed phreatic eruptions many times. Phreatic eruption is known to occur in the hydrothermal system developed within a volcanic edifice because the ejecta of phreatic eruptions often contain the hydrothermally altered minerals originated from the hydrothermal system. Therefore, an understanding of the hydrothermal system is essential to clarify the mechanism of phreatic eruption. The objective of my study is to reveal the hydrothermal system by resistivity exploration and geochemical analysis.

HP: https://sites.google.com/site/volcanokaoriseki/home

Takayuki Nakatani (Researcher)

 

Masashi Ushioda (AIST Postdoctoral Researcher)

Toshihiro Suzuki (Technical Staff)

Magma reservoirs exist at deep inside of the crust, and their pressure condition reaches to several thousand atmospheres. Under such elevated pressure conditions, the amount of water and carbon dioxide which dissolve in the magma, and the minerals which coexist with magma, are different from that found at the normal pressure condition. Therefore, using high pressure apparatus, I am performing melting experiments of rocks and investigating how the generated magma changes with pressure.

Hiroshi Shinohara (Prime Senior Researcher)

My main interest is to understand eruption and degassing processes based on surveillance of volcanic gases and volatiles in magmas. I recently developed Multi-GAS (a portable instrument to measure volcanic gas composition) and applied to active degassing plumes of various volcanoes in many countries as well as to conduct continuous monitoring. We evaluate the volcanic activity and model eruption and degassing processes based on the spatial and temporal variation of the volcanic gases. We also investigate volcanic activity with hydrothermal system based on the surveillance of fumarolic gases.