How earthquake-safe is the southern coast?

The southern coast sits in the lowest seismic band of mainland Bulgaria. For the coast around Burgas, Sunny Beach, Nessebar, Pomorie and Sozopol, the seismic code (Eurocode 8 together with Наредба РД-02-20-2) assumes a reference ground acceleration of about 0.11 g. That is the most favourable figure on the entire Bulgarian Black Sea coast. The high-hazard zone lies on the northern coast around Kaliakra and Shabla, roughly 150 to 200 kilometres away, at about 0.23 to 0.32 g. For buyers this means new builds here are designed under Eurocode 8 for a lower hazard level, and the location away from the active Kaliakra fault keeps the long-term risk down. No region is earthquake-free. But among Bulgaria's coastal areas the south is one of the calmest. It is one of the reasons Svetlana works only south of the Balkan Mountains and not in the Varna and Dobrich provinces.