Fig. 6From: Tectonic tremors immediately after the 2011 Tohoku-Oki earthquake detected by near-trench seafloor seismic observationsTwo-hour spectrogram of the horizontal component at AO.S05 (top), with temporal variation of amplitude and spectral deviations (middle), and seismograms of two identified tremors, (1) and (2), (bottom). Horizontal red and black lines in the middle panel show the detection threshold of spectral and amplitude deviations, respectively. Vertical and horizontal component records are indicated by red and black traces, respectively, in the bottom panelBack to article page