FIGURE CAPTIONS

Fig. 1.  Structural sketch map of central west Bulgaria with station velocities (arrows) in West-Bulgarian reference frame.  Error ellipses represent 70% confidence regions for GPS (open ellipses, indicated with GPS-GPS in the legend) and GPS-Triangulation (shaded ellipses, indicated with GPS-Trig in the legend) velocities.
Tectonis symbols. Faults: I - normal; II – strike-slip with direction of relative motion; III – with unclear type of displacement. Shaded areas are grabens with Neogene-Quaternary sedimentary filling.
1 – Pernik fault zone; 2 – Vitosha fault zone; 3 – Sofia graben; 4 – Zheleznitsa fault zone.