Retraction to: Earth, Planets and Space (2017) 69:72 https://doi.org/10.1186/s40623-017-0657-8
The Editor-in-Chief is retracting this article (Hata et al. 2017) because an Investigation Committee established by Osaka University has found that data were fabricated by manipulation, and that theoretical calculation values were falsified to make the fabricated data look more convincing. Masayuki Yoshimi, Hiroyuki Goto, Takashi Hosoya, Hitoshi Morikawa and Takao Kagawa agree with this retraction. Yoshiya Hata is deceased.