Seismograms (a) and focal mechanisms (b) for earthquakes belonging to the same cluster (cluster 1). (a) All the seismograms were bandpass-filtered between 3.0 and 15.0 Hz. The gray shaded area represents the parent time window for P- and S-waves. The thick black bars are manually selected arrival times. The early portions of the seismograms are enlarged in the lower panel. (b) P- and T-axes for each focal mechanism projected onto the lower hemispheres with red and green circles, respectively. The underlying focal mechanisms are representative of the cluster.