Name : KAGIYAMA,  Tsuneomi
            Position : Associate Professor
            Division/Center : Volcano Research Center
            Research Area : Volocano Geophysics
            homepage : http://hakone.eri.u-tokyo.ac.jp/vrc/kagiyama/index.html
 
 
 
 

 Research:

       My group's research interest is determining the structure of volcanoes to understand volcanic processes including locations of magma
       reservoir, magma rising process before eruptions and causes of related phenomena. Since 1994, I have conducted joint experiments in
       several volcanoes in Japan to reveal the structure and the magma supply system. The experiments were carried out by seismological,
       electromagnetic and other geophysical methods. The experiment found some anomalous regions suggesting magmatic activity.
       According to the MT survey, volcanic areas such as Kirishima Volcanoes are characterized by a simple four-layer structure; relatively
       resistive overburden, very conducting second layer at the depth of a few hundred meters, resistive basement, and deep conductor. The
       low-resistivity second layer (Shallow Low Resistivity Region) is interpreted as a water-saturated porous layer, which is widely
       distributed throughout volcanic areas. This layer plays an important role in controlling types of eruption and in generating precursory
       phenomena of volcanic eruptions through interaction of the water with ascending magma. The deep conductor (Deep Low Resistivity
       Region) appears about 10 km below the surface in average, but shallower beneath the presently active volcanoes up to a few km in
       depth. Seismic explosion experiment found seismic reflectors, which is probably related to the Deep Low Resistivity Region, at 10 km
       beneath the volcanoes. Significance of the SLRR and DLRR is now examined by precise seismological and other geophysical
       observations. For example, an outbreak of earthquake swarm at the top of the DLRR beneath Shinmoe-Dake, Kirishima Volcanoes is
       followed by upward migration of seismic activity, dilatational crustal deformation in the resistive third layer, volcanic tremor and
       thermal demagnetization within the SLRR, and finally steam and ash emission from the crater. These results suggest a migration of
       magma.

 Publications:

Kagiyama, T., Utada, H. and Yamamoto, T., Magma ascent beneath Unzen Volcano, SW Japan, deduced from the electrical resistivity structure, Jour. Volcanol. Geotherm. Res., 89, 35--42, 1999.

Utada, H., Neki, M. and Kagiyama, T., Astudy of annual variations in the geomagnetic total intensity with special attention to detecting volcanomagnetic signals, Earth Planets Space, 52, 91--103, 2000.

Ichiki, M., Sumitomo, N. and Kagiyama, T., Resistivity structure of high-angle subduction zone in the southern Kyushu district, southwestern Japan, Earth Planets Space, 52, 539--548, 2000.