# Integrated Earthquake Catalog III: Gakkel Ridge, Knipovich Ridge, and Svalbard Archipelago
## 3 Results
### Merging Catalogs
This applies not only to the ISC catalog but also to the ARC catalog, which combines data from several regional networks KOLA, FCIAR, and the GS RAS teleseismic network. In addition, catalogs significantly change over time: the diversity of sources (contributing agencies) and the number of events significantly increase starting from the mid-1990s and then in 2010. For this reason, metric parameters \(\sigma_{T}\), \(\sigma_{X}\), and, \(\sigma_{Y}\) change over time (Figure 8), and heavy tails appear in the distributions of \(DT\), \(DX\), and \(DY\). In this situation, using the methodology applied in [27; 28] to determine the threshold value of the metric leads to an increased probability of missing duplicates (Figure S4, see Supplementary). Therefore, in this paper, it was decided not to use a multivariate normal distribution model. Instead, the sampling distribution (without modeling by the normal distribution, as in the original method) of the metric for the nearest events from the two merged catalogs is used. We assume that the maximum value of the metric for events that can be duplicates is \(Ro=30\), which corresponds to a time and space difference of about 1.5 min and 600 km. We construct the distribution of such events \(F\)dub. The red lines in Figures 5b, 7b and 9b represent the value of \(1-F\)dub, which we consider as the probability of missing a duplicate (error of the first kind). The probability of a false duplicate (error of the second kind) is estimated in the same way as in [27; 28]. For this, we calculate the values of the metric (1) \(Ro\) between events within an additional catalog. The blue lines in Figures 5b, 7b and 9b represent the proportion of events with a proximity less than a given value of \(Ro\). The black lines show the estimate of the total probability of the first and the second kind errors. The threshold value of the metric minimizes the total number of errors. Figures 5c, 7c, and 9c show the distribution of normalized times and distances for the nearest events from the merged catalogs. The metric contour lines correspond to the chosen threshold value, which provides the optimal separation of duplicates and unique events. The numerical parameters of the catalog merging are given in Table 2. The integrated catalog contains 17,922 events. Figure 4: \(Cont.\)  
Figure 4: Stage 1. Determination of numerical parameters of the metric (1) for merging the ARC and SHB catalogs. Distributions of variables \(DT\), \(DX\), \(DY\), and the dependence of dispersion and mean values on time and magnitude of events. Figure 5: Stage 1: Merge of catalogs ARC and SHB. (**a**) Comparison of the metric distribution ARC/SHB pairs (blue histogram) and the same metric for SHB/SHB earthquakes (red histogram); (**b**) Threshold optimization: the red line shows the probability of missing a duplicate, the blue line shows the probability of a false duplicate, and the black line shows the total probability of the first and the second kind errors. The threshold value \(Ro=12\), which minimizes the total number of errors, approximately 0.7%, is shown by a dashed line; (**c**) Distribution of normalized \(DT\) and \(DR\), and the contour line of metric (1). Colored dots represent ARC/SHB pairs (pink dots are duplicates, blue dots are unique events), and black dots are distances between SHB/SHB events in metric (1). The values of the metric for earthquakes in the SHB catalog are significantly larger than for ARC/SHB duplicates (pink dots). The contour line of the metric (1) \(Ro=12\) provides close to optimal separation of duplicates and naturally grouped events. Absolute duplicates are not shown. Figure 6: Determination of numerical parameters of the metric (1) for merging the ARC_SHB and ARKH catalogs. Distributions of variables _DT, DX, DY_, and the dependence of dispersion and mean values on time and magnitude of events. Figure 7: _Cont_. Figure 8: _Cont_. Figure 3:0 Stage 2: Merge of catalogs ARC_SHB and ARKH.