A research paper led by Professor Tsutomu Yamanaka of the Division of Environmental Dynamics Prediction has been featured in a University of Tsukuba press release.
A research team investigated magmatic water contained in hot springs and volcanic fumaroles around the Kussharo Caldera in Hokkaido. By comparing numerical simulations of isotopic changes in water during the subduction of the oceanic plate with observed isotopic data, the study demonstrated that the magmatic water originates from the Pacific Plate subducted to a depth of approximately 125 km beneath the Kuril Trench.
The study also estimated the total amount of slab-derived water supplied over the past 400,000 years and showed that isotopic compositions of magmatic water in volcanic fumaroles can be modified by vapor–liquid phase separation. Reanalysis of historical isotopic data from Showa-Shinzan further confirmed that its magmatic water is also derived from the Pacific Plate.
These findings provide new insights into the relationship between deep Earth water cycling and volcanic activity.
For further details, please refer to the press release and the published paper below.
Press Release
- University of Tsukuba (June 29, 2026)
https://www.tsukuba.ac.jp/journal/biology-environment/20260629140000.html - Press release document （PDF 5.19MB）
Paper
- Isotopic evidence for slab-derived magmatic water beneath the Kussharo Caldera, Japan.
Journal of Volcanology and Geothermal Research, DOI:10.1016/j.jvolgeores.2026.108678