Welcome to Takahito KAZAMA's website!
Assistant professor, Geodesy Laboratory, Graduate School of Science, Kyoto University
Adress: Sci. Bldg. 1-242, Kitashirakawa-oiwake-cho, Sakyo-ku, Kyoto, 606-8502 Japan
Tel & Fax: +81-75-753-3917
E-mail: takujin [at] kugi.kyoto-u.ac.jp
Photo: Lamplugh Glacier, Glacier Bay, SouthEast Alaska
My research interests
Gravity observation is one of the most useful methods to detect solid-earth tectonics (coseismic crustal deformation, magma transfer in volcanoes, and so on), but gravity is also sensitive to land-water re-distributions, which often obscure the solid-earth gravity signals. So I'm motivated to correct the hydrological gravity disturbances using the original software for the hydrological modeling, G-WATER [1] [2]. By applying G-WATER [3D] to Asama Volcano in the central Japan, we succeeded in retrieving the 5-microgal absolute gravity change associated with magma mass movement in the volcanic conduit [3].
I'm now also interested in gravity changes due to glacial isostatic adjustment (GIA). On the Antarctic Continent, we observed the absolute gravity value with the portable absolute gravimeter A10, for the first time as the Japanese Antarctic Research Expedition [4]. In Southeastern Alaska, we determined the gravity variation rate of -2 to -4 microGal/yr using the campaign absolute gravity measurement data from 2006 to 2015, and found that the gravity decrease can be quantitatively explained by GIA associated with past/present ice melting [5].
When I was a graduate student in Tokyo University, I studied the seismic attenuation structure in the inner core. We found using the data of the Japanese seismic array Hi-net, that there is a strong vertical hetergeneity of quality factor Q in the inner core below the northwestern America [6].
Photo: Parallel absolute gravity measurements in Ishioka, Ibaraki Prefecture
My research articles (See detail on Google Scholar)
[1] T. Kazama and S. Okubo (2009): Hydrological modeling of groundwater disturbances to observed gravity: Theory and application to Asama Volcano, Central Japan. J. Geophys. Res. (Solid Earth), 114 (B8), B08402, doi:10.1029/2009JB006391.
[2] T. Kazama, Y. Tamura, K. Asari, S. Manabe and S. Okubo (2012): Gravity changes associated with variations in local land water distributions: observations and hydrological modeling at Isawa Fan, northern Japan. Earth Planets Space, 64 (4), 309-331, doi:10.5047/eps.2011.11.003.
[3] T. Kazama, S. Okubo, T. Sugano, S. Matsumoto, W. Sun, Y. Tanaka, E. Koyama (2015): Absolute gravity change associated with magma mass movement in the conduit of Asama Volcano (Central Japan), revealed by physical modeling of hydrological gravity disturbances. J. Geophys. Res. (Solid Earth), 120 (2), 1263-1287, doi:10.1002/2014JB011563.
[4] T. Kazama, H. Hayakawa, T. Higashi, S. Ohsono, S. Iwanami, T. Hanyu, H. Ota, K. Doi, Y. Aoyama, Y. Fukuda, J. Nishijima, and K. Shibuya (2013): Gravity measurements with a portable absolute gravimeter A10 in Syowa Station and Langhovde, East Antarctica. Polar Science, 7 (3-4), 260-277, doi:10.1016/j.polar.2013.07.001.
[5] K. Naganawa, T. Kazama, Y. Fukuda, S. Miura, H. Hayakawa, Y. Ohta, J.T. Freymueller (2022): Updated absolute gravity rate of change associated with glacial isostatic adjustment in Southeast Alaska and its utilization for rheological parameter estimation. Earth Planets Space, 74, 116, doi:10.1186/s40623-022-01666-7.
[6] T. Kazama, H. Kawakatsu and N. Takeuchi (2008): Depth-dependent attenuation structure of the inner core inferred from short-period Hi-net data. Phys. Earth Planet. Int., 167 (3-4), 155-160, doi:10.1016/j.pepi.2008.03.001.
Photo: Absolute gravity measurement in Syowa Station, East Antarctica
Links
About Kyoto University:
- Geodesy Laboratory
- Department of Geophysics
- Division of Earth and Planetary Sciences
- Graduate School of Science
- Kyoto University
