Fig. 3
From: Long-duration seismicity and their relation to Copahue volcano unrest
Statistical analysis for the NB episode of Fig. 2. a The normalized PDF of the samples and weighted by their spectral energy. The peak centered at 1.4 Hz, which is the only peak above 0.6, is the characteristic peak of the episode. The normalized PDF of averaged rectilinearities R (b), horizontal azimuth \(\Theta _H\) (c), and vertical incidence \(\Theta _V\) (d) in the range \(\pm 0.1\) Hz around the characteristic peak. R, \(\Theta _H\), and \(\Theta _V\) characterize the polarization of the peak by extracting the mode and range of each distribution. The range is the width of the distribution at 0.5 (blue horizontal lines in b–d). The upper part of each plot gives the sample size of each PDF