# Integrated Earthquake Catalog of the Ossetian Sector of the Greater Caucasus
## 3 Results  
### Merging Catalogs  
When merging catalogs, the preference is given to earthquake records from the ISC catalog that have magnitude definitions \(MW^{\text{CCMT}}\) and/or \(m\)\({}^{\text{DSC}}\) and/or \(m\)\({}^{\text{NEIC}}\)[4; 5; 6]. As shown in Table 1, in the region considered, a large majority of seismic events are registered by GS RAS seismic networks. The quantity of earthquake records in the ISC catalog is approximately four times smaller than the total number of events in the GS RAS catalogs. Thus, to merge earthquake catalogs, the following priority sources of earthquake data were chosen:  
1. Earthquakes from the ISC catalog that have magnitudes \(MW^{\text{GCMT}}\) and/or \(m\)\({}^{\text{DSC}}\) and/or \(m\)\({}^{\text{NEIC}}\) (ISC_CORE, 269 events);
2. Earthquakes from catalogs of GS RAS: ZEMSU (1258 events) and NC (12,399 events). These catalogs do not overlap in time;
3. Earthquakes from catalogs of Georgia (572 + 2412). These catalogs do not overlap in time;
4. Other earthquakes from ISC (ISC_OTHER, 3649). The sequence of merging catalogs is shown in the diagram (Figure 2). At each stage, the catalogs are merged in two steps. First, the parameters of metric (1) are determined. For this reason, the proximity function between the nearest events from the two input catalogs is calculated with standard parameters \(\sigma_{T}=0.05\) min, \(\sigma_{X}=\sigma_{Y}=15\) km. For the preliminary identification of duplicates, a threshold metric value of \(Ro=10\) is used. It corresponds to a difference in time and space of 0.5 min/150 km. If the number of duplicates is not enough or most of the duplicates are absolute, we limit ourselves to the first step. This happened at the first stage of this study when merging the ZEMSU and GEOR71 catalogs (Figure 2): 654 duplicates were identified. However, among them,  
Figure 2: The diagram for the assembly of the integrated catalog of the Ossetian sector of the Greater Caucasus. The main catalog is indicated with a bold frame at each stage. The numbers of stages are given in ellipses corresponding to Table 3.  
only 18 events had different epicenter definitions. Moreover, the difference in time for most events could be explained by different accuracies of data representation in the input catalogs. The distribution of the \(Ro\) metric is shown in Figure 3.  
If the number of predefined duplicates is sufficient, then we can move on to the second step. This was the case at stages 2, 4, and 5 of the assembly of the integrated catalog of the Ossetin sector of the Greater Caucas. For predefined duplicates, the standard deviations \(\sigma_{T}\), \(\sigma_{X}\), and, \(\sigma_{Y}\), of the variables \(DT\), \(DX\), and \(DY\) are calculated, respectively (Figures 4, 6 and 8). After this, the threshold value of the metric is determined and the final identification of duplicates occurs (Figures 5, 7 and 9). Figure 3: Stage 1: Merging of catalogs ZEMSU and GEOR71. Comparison of the metric distribution ZEMSU/GEOR71 pairs (blue histogram) and the same metric for GEOR71/GEOR71 earthquakes (red histogram). The dashed line represents the standard threshold value \(Ro=10\). \begin{table}
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Figure 4: Stage 2: Determination of numerical parameters of the metric (1) for merging the NC and GER04 catalogs. Distributions of variables _DT, DX, DY_, and the dependence of dispersion and mean values on the time and magnitude of events. Figure 5: _Cont._  
In the third stage, the ZEMSU_GEOR and NC_GEOR catalogs are merged. These catalogs do not overlap in time, so the GSR catalog (Figure 2) is obtained by a simple merging. The earthquake catalogs for the considered region (Figure 1) are a combination of data from a wide variety of agencies. This refers not only to the ISC catalog but also to the GSR catalogs, which combine data from regional networks of North Ossetia, Dagestan, Georgia, and the GS RAS teleseismic network.