Akiko Takeo
University of Tokyo
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Featured researches published by Akiko Takeo.
Geochemistry Geophysics Geosystems | 2018
Akiko Takeo; Hitoshi Kawakatsu; Takehi Isse; Kiwamu Nishida; Hajime Shiobara; Hiroko Sugioka; Aki Ito; Hisashi Utada
We conducted broadband dispersion survey by deploying two arrays of broadband ocean bottom seismometers in the northwestern Pacific Ocean at seafloor ages of 130 and 140 Ma. By combining ambient noise and teleseismic surface wave analyses, dispersion curves of Rayleigh waves were obtained at a period range of 5–100 s and then used to invert for one-dimensional isotropic and azimuthally anisotropic βV (VSV) profiles beneath each array. The obtained profiles show ~2% difference in isotropic βV in the low-velocity zone (LVZ) at a depth range of 80–150 km in spite of the small difference in seafloor ages and the horizontal distance of ~1,000 km. Forward dispersion-curve calculation for thermal models indicates that simple cooling models cannot explain the observed difference and an additional mechanism, such as sublithospheric small-scale convection, is required. In addition, the fastest azimuths of azimuthal anisotropy in the LVZ significantly deviate from the current plate motion direction. We infer that these observations are consistent with the presence of small-scale convection beneath the study area. As for azimuthal anisotropy in the Lid, the peak-to-peak intensity is 3–4% at the depth from Moho to ~40 km. The fastest direction is almost perpendicular to magnetic lineation in area A at 130 Ma and oblique to magnetic lineations in area B at 140 Ma, suggesting complex mantle flow beneath the infant Pacific Plate surrounded by three ridge axes. The intensity of azimuthal anisotropy in the LVZ is ~2%, indicating that radial anisotropy is stronger than azimuthal anisotropy therein.
Journal of Geophysical Research | 2013
Akiko Takeo; Kiwamu Nishida; Takehi Isse; Hitoshi Kawakatsu; Hajime Shiobara; Hiroko Sugioka; Toshihiko Kanazawa
Geophysical Journal International | 2014
Akiko Takeo; Donald W. Forsyth; Dayanthie S. Weeraratne; Kiwamu Nishida
Geophysical Research Letters | 2010
Akiko Takeo; Koki Idehara; R. Iritani; Takashi Tonegawa; Yutaka Nagaoka; Kiwamu Nishida; Hitoshi Kawakatsu; Satoru Tanaka; Koji Miyakawa; Takashi Iidaka; Masayuki Obayashi; Hiroshi Tsuruoka; Katsuhiko Shiomi; Kazushige Obara
Earth and Planetary Science Letters | 2016
Yuki Nakashima; Kosuke Heki; Akiko Takeo; Mokhamad Nur Cahyadi; Arif Aditiya; Kazunori Yoshizawa
Journal of Geophysical Research | 2016
Akiko Takeo; Hitoshi Kawakatsu; Takehi Isse; Kiwamu Nishida; Hiroko Sugioka; Aki Ito; Hajime Shiobara; Daisuke Suetsugu
Seismological Research Letters | 2018
Masayuki Kano; Naofumi Aso; Takanori Matsuzawa; Satoshi Ide; Satoshi Annoura; Ryuta Arai; Satoru Baba; Michael G. Bostock; Kevin Chao; Kosuke Heki; Satoshi Itaba; Yoshihiro Ito; Noriko Kamaya; Takuto Maeda; Julie Maury; Mamoru Nakamura; Takuya Nishimura; Koichiro Obana; Kazuaki Ohta; Natalia Poiata; Baptiste Rousset; Hiroko Sugioka; Ryota Takagi; Tsutomu Takahashi; Akiko Takeo; Yoko Tu; Naoki Uchida; Yusuke Yamashita; Kazushige Obara
Geophysical Research Letters | 2018
Satoru Baba; Akiko Takeo; Kazushige Obara; Aitaro Kato; Takuto Maeda; Takanori Matsuzawa
Japan Geoscience Union | 2014
Takehi Isse; Hajime Shiobara; Hiroko Sugioka; Aki Ito; Akiko Takeo; Hisashi Utada; Hitoshi Kawakatsu; Takashi Tonegawa; Satoru Tanaka
JAMSTEC Report of Research and Development | 2014
Takehi Isse; Akiko Takeo; Hajime Shiobara