f Natural hazard and technogenic changes in the Zlatitza-pirdop graben system, Bulgaria

The Zlatitza-Pirdop graben system is situated between the Balkan, the Sredna Gora, Galabets and Koznitsa mountain ridges. It includes three grabens formed during the Neogene and the Quaternary. The origin of the oldest of them was during the Middle Pontain. The contemporary outlook of the system was formed during the Plio-Pleistocene. The total area is 220 km2. In a regional plan the system represents a part of the Sub-Balkan graben system. It was formed as a result of a regional extension at the background of the Sub-Balkan listric fault zone (Tzankov et al., 1996). Rocks of diverse and rapid facial changeability (granites, diorites, Quaternary sediments, etc.) are observed in the grabens and along their periphery.