In order to reveal the growth history, three-dimensional structure and magma ascending mechanism of the Unzen volcano, one of the most active volcano in Japan, we have initiated the six-year term international project "Unzen Scientific Drilling Project" sponsored by the Science and Technology Agency of Japan from FY1999-2005. I am a project reader and coordinating the project.
In order to understand the mechanism and the nature, the volcanological team of GSJ are conducting geological observation of ongoing volcanic eruptions. In 2000, Usu volcano in Hokkaido and Miyakejima volcano in Izu Islands have been continuing a large scale eruptions. I am a team leader of the GSJ team.
We have developed the 40Ar/39Ar age determination method by heating ~ 1mm-size mineral and rock samples by the continuous laser and have made it possible to precisely know the age of formation. We are now studying the Neogene-Quaternary volcanic history of Japanese Islands and volcanic islands of hotspot origin.
I am working to reveal the volcanic history and magma genesis on some volcanic islands of hotspot origin; i.e. Hawaiian Islands and in central Pacific, Polynesian Islands in south Pacific and Reunion and Mauritius Islands in Indian Ocean. I am now clarifying the existence of a few upwelling mechanism of magmas from the deep interior of the earth.
I am studying the temporal and spatial distribution of Neogene-Quaternary volcanism in Southwest Japan and their chemical characteristics, and am trying to clarify the tectonism generating such volcanism. I have revealed the tectonic magmatic processes in changing through time during and after the opening of the Japan Sea initiated in Early Miocene and terminated in Middle Miocene. I am now extending the study to the northwestern part of Kyushu Island where plume-type alkaline volcanism with calc-alkaline andesite and dacite have been active since Late Miocene unrelated to the subduction of the Philippine Sea Plate.
Sendai basalt in south Kyushu
Simcoe Mountain volcanic field in south central Washington, U.S.A.
Volcanic map"Kusatsu-Shirane volcano"
1/20 Quadrangle-series "Kagoshima"
1/20 Quadrangle-series "Karatsu (second edition)"
1/20 Quadrangle-series "Kanazawa"
Kusatsu-Shirane volcano（October, 1982）
Miyakejima volcano（October, 1983）
Izu Oshima volcano（November, 1986）
Teishi Knoll, Higashi-Izu （September, 1989）