| A seismic hazard map proposed as part of a new building
code for Bulgaria is presented here on basis of the recommendations in
EUROCODE 8.
Seismic source zones within an area of about 200 km around Bulgaria were
constructed considering seismicity, neotectonic and geological development.
The most time consuming work was to establish a homogeneous earthquake
catalogue out of different catalogues.
The probabilistic seismic hazard assessment in terms of intensities is
performed following Cornell (1968) with the program EQRISK (see McGuire,
1976), modified by us for use of intensities. To cope with the irregular
isoseismals of the Vrancea intermediate depth earthquakes a special
attenuation factor is introduced (Ardeleanu et al., 2005), using detailed
macroseismic maps of three major earthquakes.
The final seismic hazard is the combination of both contributions, of zones
with crustal earthquakes and of the Vrancea intermediate depth earthquakes
zone. Calculations are done for recurrence periods of 95, 475 and 10 000
years. |