engleski

Times of Increased Probability for Earthquakes in the Southern Part of External Dinarides

The southern part of external Dinarides is characterized by high seismicity if compared to the neighbouring regions of the Adriatic Sea and Internal Dinarides. In this century the catalogs list 23 earthquakes with magnitudes exceeding or equal to 5.6, while 7 of them were stronger than M=6.0. All of the earthquakes are shallow with foci in the upper crust. The analyses of the seismicity reported below are based on the Croatian Earthquake Catalogue that lists events in Croatia and neighbouring regions that occurred in the period BC-1996. The geographical borders of the area that define the subcatalog related to this study were chosen in accordance with results of recent seismic zoning of that region. The subcatalog of main-shocks for the study area was found to be reasonably complete for ML=3.5 in the period 1940-1996. After removing the aftershocks, the events prior to 1940, and those with magnitudes below the catalogue completeness threshold a total of 332 earthquakes were left for analyses. The CN algorithm was applied by using standard parameters that define the functions of the earthquake flow. The strong shocks (i.e. the earthquakes for which the prediction is attempted) were defined as having local magnitude exceeding or equal to 5.6. It was found that 8 out of 10 strong shocks in the period 1940-1996 were preceded by TIPs (time increased probability), with 5 false alarms. The total duration of TIPs was 38.8% of the total time. No clear relation between the TIP duration and magnitude is observed. The attemts to reduce the area considered resulted in poorer prediction results, thus confirming the validity of seismic zoning as used here.

Extrenal Dinarides; seismicity; Croatian Earthquake Catalogue; seismic zoning; time increased probability;

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