Hiroko Sugioka
University of Tokyo
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Featured researches published by Hiroko Sugioka.
Geochemistry Geophysics Geosystems | 2009
Daisuke Suetsugu; Takehi Isse; S. Tanaka; Masayuki Obayashi; Hajime Shiobara; Hiroko Sugioka; Toshihiko Kanazawa; Yoshio Fukao; Guilhem Barruol; D. Reymond
[1]xa0The South Pacific region is characterized by a broadly elevated seafloor known as the South Pacific superswell. This region has a concentration of midplate volcanoes that experienced massive eruptions in the mid-Cretaceous period (90–120 Ma). These characteristics suggest the presence of a large-scale mantle plume beneath the South Pacific, called the South Pacific superplume. The geometry, origin depth, temperature, and composition of the superplume remain controversial, however, mainly due to the lack of seismological data that documents the mantle structure beneath the South Pacific. Seismic stations are sparse in the area due to its remote ocean environment. To obtain a better seismic image of the superplume, we deployed temporary broadband seismographs on oceanic islands and the seafloor in the South Pacific, which made possible the highest spatial resolution that has ever been achieved for the mantle structure beneath the region. The seismic image obtained from this new seismic data indicates that large-scale low-velocity anomalies (on the order of 1000 km in diameter), indicative of the superplume, are located from the bottom of the mantle to a depth of 1000 km, and small-scale low-velocity anomalies (on the order of 100 km in diameter) are present above it. A comparison of the seismic image with recent mantle convection studies based upon laboratory and numerical experiments suggests that the superplume may be a hot and chemically distinct mantle dome, and that the small-scale anomalies may be narrow plumes generated from the top of the dome. This model may explain various characteristics of hot spots in the South Pacific, such as the seafloor swell, short-lived hot spot chains, and the periodicity of massive eruptions.
Bulletin of the Seismological Society of America | 2005
Daisuke Suetsugu; Masanao Shinohara; Eiichiro Araki; Toshihiko Kanazawa; Kiyoshi Suyehiro; Tomoaki Yamada; Kazuo Nakahigashi; Hajime Shiobara; Hiroko Sugioka; Kenji Kawai; Yoshio Fukao
We analyzed broadband waveform data recorded by a deep-sea borehole observatory (WP-1) and a long-term broadband ocean-bottom seismograph (NOT1) deployed in the west Philippine basin by the Ocean Hemisphere Project. We determined the depths of the 660-km discontinuity beneath the west Philippine basin using the receiver function method. The “660” depths determined from the WP-1 and NOT1 are consistent with each other, indicating that the estimated depths are reliable. The 660 depth determined using both WP-1 and NOT1 data was 669 ± 9 km, which is deeper by 9 km than the global averages, beneath the west Philippine basin. Interpreting the 660 depth in terms of temperature, the slightly deep 660 can be translated to mean lower temperatures by about 100 K at the 660, using the Clapeyron slope of the olivine to β -spinel and the post-spinel phase change. The cold temperature is qualitatively consistent with the tomographic image. When compared with previous regional studies of the 660 beneath the Philippine Sea, our results suggest the presence of significant topography on the mantle discontinuities beneath the Philippine Sea, which may be caused by a stagnant Pacific slab in the mantle transition zone. The present study demonstrates that data from deep-sea observations provide useful information for investigating deep Earth structure.
Physics of the Earth and Planetary Interiors | 2007
Daisuke Suetsugu; Hajime Shiobara; Hiroko Sugioka; Yoshio Fukao; Toshihiko Kanazawa
Archive | 2010
Hajime Shiobara; Toshihiko Kanazawa; Mitsuru Shinohara; Takehi Isse; Hiroko Sugioka; Akinori Ito
Archive | 2003
Nobuyuki Takahashi; Shuichi Kodaira; Akinori Ito; Hajime Shiobara; Hiroko Sugioka; Benjamin Kerr; Ion Vlad; Simon L. Klemperer; Y. Kaneda; Kiyoshi Suyehiro
Journal of physics of the earth | 1996
Hiroko Sugioka; Yoshio Fukao; Shin’ichi Sakai
Archive | 2010
Takashi Okamoto; Tatsuzo Nakamura; Hiroko Sugioka; Yoshiaki Ishihara; Akinori Ito; Kazuki Obana; Shuichi Kodaira; Daisuke Suetsugu; Masahiro Kinoshita; Yoshio Fukao
Archive | 2010
Kazuki Obana; Akinori Ito; Hiroko Sugioka; Yoshiaki Ishihara; Tetsushi Nakamura; Daisuke Suetsugu; Shuichi Kodaira; Masahiro Kinoshita; Eiichiro Araki; Y. Kaneda; Yoshio Fukao; Takashi Okamoto
Geochemistry Geophysics Geosystems | 2009
Daisuke Suetsugu; Takehi Isse; S. Tanaka; Masayuki Obayashi; Hajime Shiobara; Hiroko Sugioka; Toshihiko Kanazawa; Yoshio Fukao; Guilhem Barruol; D. Reymond
Archive | 2008
Eiichiro Araki; Katsuyoshi Kawaguchi; Hiroshi Matsumoto; Hiroko Sugioka; Akinori Ito; Daisuke Suetsugu; Y. Kaneda