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Imanishi (this issue) commented that (1) the noise level at Matsushiro, Japan (MA) is much lower than at Syowa Station, Antarctica (SY), (2) oscillation signals are not observed at MA, and therefore (3) peaks below 3 mHz observed at SY are unlikely to be real signals of free oscillations. We point out that (1) he made a comparison between MA in the Japanese quiet month and SY in the Antarctic windy month, (2) the Matsushiro record does show up oscillation signals, and therefore (3) his assertion that peaks below 3 mHz observed at SY are unlikely to be real signals is not founded.


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Correspondence to Kazunari Nawa.

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Nawa, K., Suda, N., Fukao, Y. et al. Reply. Earth Planet Sp 50, 887–892 (1998).

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  • Free Oscillation
  • Real Signal
  • Seismic Noise
  • Superconducting Gravimeter
  • Syowa Station