Fig. 7From: Long-duration seismicity and their relation to Copahue volcano unrestSeveral days of October 2015 on which a BB swarm occurred. a Energy of vertical component in the range 0.5–10 Hz. b Successive 20-min (b) PSD and c PD side by side. Vertical red horizontal bars represent the onset of the BBs. A periodicity of 26.7 ± 8.3 h characterized itBack to article page