Seismic Scenario and People Exposure for Blagoevgrad Region, Bulgaria

Present research analyses the human exposure at one of the most dangerous earthquake zones in Bulgaria-Blagoevgrad region and propose a detailed seismic scenario for the main city. Seismic hazard is modelled using GIS and overlaid with one square kilometer grid of population distribution in order to determine the population exposure in the region. We define a parameter called “population exposure index” (PEI) which has five classes: Minor, Low, Moderate, High and Major. As was expected, the seismic hazard levels of Blagoevgrad region are in the upper part of the classification scale. The total population in the Blagoevgrad region (NUTS II) is around 323,000 people. Results show that more than 130,000 people are exposed to the highest level of seismic hazard. City of Blagoevgrad gathers nearly 22% of the population in the region. A specially developed seismic scenario for the city accounting the soil conditions as well is used for detailed assessment of the people exposed to seismic hazard. The obtained values of Peak Ground Acceleration (PGA) varying between 0.29 and 0.45 g are crossed with the population living in each building to determine the levels of population exposure. Our results show that people living in 398 buildings are majorly exposed to the seismic hazard in Blagoevgrad city. Another 1465 buildings are determined as highly exposed to this threat. Delineation of these buildings might be very important for the regional authority and focusing on the prevention of possible earthquake effects.