Three-component seismograms from two stations for an earthquake in cluster A. (a) Seismograms from station HR.MAS1. (b) Seismograms from station N.ANIH. The labels P, S, and X mark the arrival times of P- and S-waves and a phase of unknown origin, respectively. The horizontal components are rotated to show the radial (R) and tangential (T) components. The amplitude is normalized to the maximum of the three components.