Fig. 7From: Monitoring the instrument response of the high-sensitivity seismograph network in Japan (Hi-net): effects of response changes on seismic interferometry analysisAutocorrelation functions (ACFs) and noise level. a ACFs of the vertical component for the N.KMIH station. The ACFs were made from band-pass-filtered waveforms (passband = 1–3 Hz). The broken line indicates the date of the 2011 Tohoku-Oki earthquake. b Root mean square amplitude of waveforms for the duration of 1 h after band-pass filteringBack to article page