Last Update 05/27 2006
Research: My research field is petrology and geology of magmatic processes before and during eruption, especially during its ascent in the conduit, from the viewpoint of forecasting volcanic eruptions. The target volcanoes include Unzen, Asama, Miyakejima, Izu-Oshima, Fuji, Anatahan (Northern Marianas), Vesuvio (Italy) and so on. Efficiency of degassing controls the manner of volcanic explosivities. In the petrological tool, we can extract the information on time sequence of degassing and the resultant crystallization, both of which largely change properties of magma. Especially products of the 1991-1995 eruption at Unzen have been investigated petrologically in this decade, where magma with the potential of explosive eruption did not explode due to efficient degassing in the volcanic conduit. In order to understand the process of degassing, scientific drilling was carried out to penetrate into the volcanic conduit and to collect both samples of the conduit lava and the physical data around it (Unzen Scientific Drilling Project, USDP, during 1999-2004). We could successfully penetrate into the target and get the samples. In addition, geological monitoring and observation of on-going eruptions are our important task in the Volcano Research Center; that is, evaluation of the present state of eruption, forecasting the forthcoming eruptive phenomena, and minimizing volcanic disaster. This task is carried out jointly with geophysical and geochemical monitoring groups of VRC, ERI, and national universities. Unzen, Kuju, Usu, Miyakejima and Asamayama eruptions were investigated in thiese respects during these decades. Publications: Nakada, S., H. Shimizu, and K. Ohta, Overview of 1990-1995 eruptions at Unzen Volcano., Journal of Volcanology and Geothermal Research, 89, 1/4, 1--22, 1999. Nakada, S., M. Nagai, T. Kaneko, A. Nozawa, K. Suzuki-Kamata, Chronology and products of the 2000 eruption of Miyakejima Volcano, Japan, Bull. Volcanology, 67, 3, 205--218, 2005. Nakada, S., Matsushima, T., Yoshimoto, M., Sugimoto, T., Kato, T., Watanabe, T., Chong, R., Camacho, J.T., Geological aspects of the 2003-04 eruption of Anatahan Volcano, Northern Mariana Islands, J. Volcanol. Geotherm. Res., 146, 1-3, 226--240, 2005. Shimano, T., Nakada, S., Vesiculation path of ascending magma in the 1983 and the 2000 eruptions of Miyakejima volcano, Japan, Bull. Volcanol., 68, 6, 549--566, 2006. Nakada, S., Uto, K., Sakuma, S., Eichelberger, J.C., Shimizu, H., Scientific results of conduit drilling in the Unzen Scientific Drillin Project, Scientific Drilling, 1, 18--22, 2005. |
