Long-term expected seismicity
The researches of the seismic hazard, i.e. of the long-term expected seismicity regarding the maximum magnitude or maximum intensity, are regularly performed in the Seismological Observatory at the Faculty of Natural Sciences and Mathematics in Skopje. In these researches, the Gutenberg–Richter law for earthquakes frequency with respect to magnitude is used, together with the empirical relations between the magnitude and the maximum intensity for the territory of the Republic of Macedonia and neighboring regions. The input data are the data for all observed historic and contemporary seismicity of this territory. The output data are the maximum magnitudes or maximum intensities which are expected in the particular areas of this territory within certain time period, the so-called return period.
The results of some of the above described investigations, namely two maps of seismic zonation regarding the maximum intensity and maximum magnitude, are given in Figs. 5 and 6.
Fig. 5. Map of expected maximum intensities (in degrees of the MSK-64 macroseismic scale) in the territory of the Republic of Macedonia for a return period of 500 years
Fig. 6. Map of expected maximum magnitudes in the territory of the Republic of Macedonia for a recurrence period . The three seismic zones (West Macedonia, Vardar zone and East Macedonia) are shown with parts with differently oriented lines. The empty parts present the bordering regions between the seismic zones, which do not show significant original seismicity (one of them, on the West, is the Pelagonia Anticlinorium). (Source: Seismological Observatory at the Faculty of Natural Sciences and Mathematics in Skopje.)