[Yuzurihara, Yamamura]

We found that interesting time variation in the inspiral range; only the range of BBH [30-30] decreased around 05/21 13:00~14:00. (SummaryPage)

There were no special features in ground motion, but we found the whitened spectrogram had some structures in low frequencies (15~50 Hz) at that time. (Fig.1~3)

Also, the Gaussianity was bad, and GauCh's plot looked similar. (Fig.4)

These might be the cause of time variation of the inspiral range.