Abstract:
A homogeneous earthquake catalogue for Bulgaria and adjacent areas covering the time span 1981–2019 (instrumental seismicity) is presented. The catalogues including instrumental seismicity of Solakov et al. (1993) and Botev et al. (2010), covering the time interval 1981-2000, were updated for the period 2001-2019 using instrumentally determined focal earthquake parameters.
Data for earthquake catalogues are from the Bulgarian seismological network (NOTSSI). At present the Bulgarian seismological network ensures reliable registration and high quality information for earthquakes occurred in Bulgaria and surroundings. Since 2005-2006, real-time data exchange between Bulgaria and Greece, Romania, Serbia, Northern Macedonia and Turkey was implemented. These data are also used in hypocentral location.
The here presented catalogue for the period 1981–2019 is homogenized concerning magnitude. Regression equations (presented in Solakov et al., 2018) are applied to convert magnitude scales used in Bulgarian seismological routine practice (Md and Mp) to the widely used moment magnitude. For stronger events are given moment magnitude estimation (if exist) from Global Centroid Moment Tensor Catalog (with priority) or EMSC catalogue.
The catalogue is processed in the sense that duplicated events and quarry blasts are removed. A comprehensive assessment of catalogue completeness indicates that no earthquake with moment magnitude, Mw 3.2 or greater has been omitted in the whole instrumental period (1981–2019).
The following information is given in the catalogue:
– Date: Year, month, day;
– Origin time in standardize GMT: Hour, minute and second;
– Epicenter coordinates: Latitude φ° N and Longitude λ° E;
– Focal depth in km;
– Estimated moment magnitude, Mw;
– Epicentral/Maximum intensity (European macroseismic scale – EMS-98)) I0/Imax (if available).
It should be stated that the catalogue will be updated annually.