Crustal Fluid Research Group

We conduct research on groundwater and fluid circulation from the Earth's surface to its deep interior under researchers specializing in geochemistry, volcanology, hydrology, and related fields. We are accumulating geoscientific knowledge through investigations into groundwater and hot spring water in volcanic and non-volcanic regions to elucidate the origins of deep fluids; studying water circulation in subduction zones such as the Japanese island arc; estimating volcanic volatiles and slab-derived water fluxes; reconstructing the hydrothermal activity history of island arcs; and examining groundwater fluctuations associated with volcanic and seismic activity. Additionally, we are conducting research on development of advanced technology for detecting deep-seated fluids, groundwater flow system, groundwater dating, and groundwater temperature/salinization for groundwater environmental assessments. These initiatives aim to support safety regulation for geological disposal through commissioned research from the Nuclear Regulation Authority, provide foundational information for disaster prevention by investigating the relationship between deep fluids and seismic/volcanic activity, and contribute to the sustainable utilization of resources in the deep Earth.

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

Member

Noritoshi Morikawa (Leader, Group)

I am studying the origin of deep fluids, as well as the residence time and origin of groundwater. By analyzing the concentration and isotope ratio variations of noble gases such as helium along with other isotopes and dissolved ion concentrations dissolved in groundwater and hot spring water. Additionally, to elucidate groundwater circulation in the shallow aquifer, I am attempting to estimate groundwater recharge temperatures from atmospheric noble gas concentrations and to date young groundwater using the tritium-helium-3 method.

Hitomi Nakamura (Chief Senior Researcher)

My research focuses on empirically elucidating the role of deep fluids in the Earth through systematic and wide-area surveys of volcanoes and hot spring waters, the development of analytical techniques for ultra-trace elements, and the application of forward numerical modeling and statistical analyses. By using geochemical data as key indicators, I aim to quantitatively link observations with models. With a foundation in geology and petrology, I integrate geochemical analyses with interdisciplinary and multifaceted perspectives to explore natural phenomena that remain unknown or poorly understood.

Hiroshi Takahashi (Senior Researcher)

The investigation about carbon species in groundwater is conducted inferred from the stable and radioactive carbon isotopes. Especially, radiocarbon groundwater age and the estimations of deep-seated carbon in groundwater and ascending geogenic fluid are focused in the present works.

Yoko Togo (Senior Researcher)

I specialize in geochemistry. I analyze iodine and bromine concentrations in groundwater across Japan, as well as the stable isotopic composition of water. In particular, I focus on estimating the origin of chlorine in saline water—such as seawater, formation water associated with oil and gas fields, and magmatic water—using halogen element ratios.

Akinobu Miyakoshi (Senior Researcher)

My current research interests focus on groundwater flow and subsurface thermal environment changes caused by human activities such as groundwater development, urbanization and deep underground development. Integrating observation data with model results is an also essential component of my research.  Results of my research are applicable for development sustainable usage of groundwater beneath an urban environment, and I am also conducting evaluation of deep groundwater environment using them.  My attempts can contribute to improvement of groundwater flow prediction which considers climate changes such as global warming.

Yuki Tosaki (Senior Researcher)

I specialize in isotope hydrology. My research focuses on using groundwater chemistry and isotopic data as indicators to determine the origin and age of groundwater. In addition, I assess groundwater flow through GIS-based analyses that integrate hydrogeological, chemical, and isotopic data.

Tsuyoshi Shintani (Researcher)

My primary research focuses on elucidating the origins of groundwater (particularly saline groundwater), using geochemical methods such as elemental concentrations and stable isotopes. In addition, I work on evaluating regional groundwater flow systems through three-dimensional visualization of water quality data using GIS, as well as on developing information platforms to support the sustainable use of groundwater resources. Recently, I have been focusing on saline groundwater systems that have traditionally been avoided as water resources, and I am conducting research on their potential applicability to inland aquaculture, based on changes in water quality and groundwater flow characteristics.

Miyu Hasegawa (Research Assistant)
Kohei Kazahaya (Invited Senior Researcher)

I have been working as volcanologist, geochemist and hydrologist focusing on: 1) degassing and diffusive mechanism of magmatic gases to the atmosphere and groundwater system for long-term prediction of volcanic activities based on monitoring of volcanic gas flux and groundwater surveys, and 2) quantitative estimate of slab-derived fluid contribution and flux to groundwater systems using isotopic and chemical tracers for the assessment of long-term groundwater stability on the safety disposal of nuclear waste.

Yuri Nakamura (Technical Staff)
Toru Shimizu (Senior Researcher) (concurrent)

I have been specialized in ore mineralogy and geology. Up to date I have focused hydrothermal metallic deposits (Hishikari, Toyoha and Koryu), in terms of ore petrography, fluid inclusion microthermometry and stable isotopes analysis. Hereafter, I will mainly engage in a fluid inclusion research on the hydrothermal minerals to understand the deep fluid convection system in Japanese island arc.

Mikio Takeda (Chief Senior Researcher) (concurrent)

Laboratory experiments to evaluate hydraulic properties of low permeability rocks, research interests are focused on the effective diffusivity evaluation with laboratory experiments and analytical solution model. Recent researches are about the chemiosmotic properties of sedimentary rocks which causes the hydraulic pressure anomalies. The laboratory experiments and analytical solution has been developed to evaluate osmotic parameters, as well as the numerical simulation with osmotic model to evaluate the duration of pressure anomalies and groundwater flow under osmotic pressure anomalies.

(concurrent) Tsutomu Sato (Senior Researcher)

I am investigating geochemical characteristics and behavior of hot spring water and groundwater. I hope to reveal groundwater fluctuations due to earthquakes and volcanic eruptions. My main survey fields are Ito and Iwaki Cities, Awaji Island, and Usu and Miyakejima volcanoes.