Researchers at the University of Tsukuba found that magmatic water in hot springs and volcanic gases around Kussharo Caldera originates from the subducting Pacific Plate [1].
This discovery provides a direct link between deep tectonic movements and the surface geothermal activity of Hokkaido, Japan. By identifying the specific origin of these fluids, scientists can better understand the chemical processes that drive volcanic systems, and the movement of water within the Earth's mantle.
The research team utilized numerical simulations and isotopic data to trace the signatures of the water [1]. Their findings indicate that the Pacific Plate descends from the Kuril Trench to a depth of 125 kilometers [1]. At this depth, the water is released and eventually rises to the surface, manifesting as the hot springs and volcanic gases observed around the caldera [1].
"Researchers at the University of Tsukuba used numerical simulations and isotopic data to show that magmatic water in hot springs and volcanic gases around Kussharo Caldera, Hokkaido, originates from the subducting Pacific Plate," a researcher said [1].
The study focuses on the complex interaction between the subducting slab and the overlying mantle wedge. The isotopic signatures serve as a chemical fingerprint, allowing the team to distinguish between water sourced from the surface, and water carried down by the tectonic plate [1]. This process is critical for the generation of magma in subduction zones, as the introduction of water lowers the melting point of the surrounding rock.
The depth of 125 kilometers—approximately 78 miles—marks the point where these volatile components are released from the descending plate [1]. This transport mechanism explains how deep-earth materials influence the geothermal landscape of the region.
“Magmatic water in hot springs and volcanic gases around Kussharo Caldera originates from the subducting Pacific Plate.”
The identification of the Pacific Plate as the source of magmatic water at Kussharo Caldera confirms the role of deep-slab dehydration in fueling surface volcanism. This provides a concrete geological map of how water travels from the ocean floor, through the mantle, and back to the surface, improving the scientific community's ability to model volcanic activity in subduction zones.
