[J09-3] Geodesy and seismology general contributions III

[J09-3-04] About 38mHz (26 s) oscillation in northeastern Japan after the 2011 Tohoku megathrust earthquake

^○Yuta Mitsui¹, Kosuke Heki² (1.Shizuoka University, Shizuoka, Japan, 2.Hokkaido University, Sapporo, Japan)

By stacking high-rate GNSS data at north-eastern Japan, we find a peaky signal with frequency of about 38 mHz (26 s) following the 2011 Tohoku earthquake in the horizontal-to-vertical (H/V) spectral ratio. The signal appeared several minutes after the passing of surface wave fronts, and its duration was about 2 min. Since the frequency of 38 mHz was almost equal to the world-wide microseism (Oliver, 1962; Shapiro et al., 2006), we speculate that some features of the Earth's structure contributed the characteristic oscillation.