# Integrated Earthquake Catalog II: The Western Sector of the Russian Arctic
## Materials and Methods  
The studied region covers a geographic area bounded by the coordinates: 60\({}^{\circ}\) N-84\({}^{\circ}\) N, 25\({}^{\circ}\) E-100\({}^{\circ}\) E (Figure 1). Five earthquake catalogs are used as input data (Table 1):  
1. The Arctic catalog from the annual journals _Earthquakes in the USSR_ 1962-1991, _Earthquakes in Northern Eurasia_ 1992-2017, and _Earthquakes in Russia_ 2018-2020 (hereafter ARC);
2. The merged earthquake catalog of the territory of the East European platform and its nearest surroundings from the annual journals _Earthquakes in the USSR_ 1962-1991, _Earthquakes in Northern Eurasia_ 1992-2017, and _Earthquakes in Russia_ 2018-2020 (hereafter VEP);
3. The ISC 1962-2022 catalog, which is a composite and contains data from many world and also Russian agencies (Table 2);
4. The catalog _Seismicity of the western sector of the Russian Arctic_[24] (hereinafter Morozov) 1962-2020;
5. The merged catalog of seismic events in the territory of the Russian Federation from the annual journals _Earthquakes in Russia_ 2003-2020. Only data on events that are non-earthquakes are used (hereinafter ER_EXP). As can be seen from Figure 1, a large number of earthquake epicenters are located in the southwestern part of the studied region on the Kola Peninsula and Karelia as well as in the northern part of the region on the shelf boundary of the Kara and Barents Seas. The peculiarity of the western sector of the AZRF is the large number of seismic events that are not tectonic earthquakes (explosions, rock bursts, and other anthropogenic events) [32; 33; 34]. All the catalogs used (Table 1) are divided into \"Earthquakes\" (the nature of the event is \"earthquake\" or \"possibly earthquake\") and other events. Events with unknown magnitude/class are excluded from the \"Earthquakes\" catalogs. The methodology of the sequential merging of earthquake catalogs with the identification of duplicates is described in detail in [1; 7]. A Euclidean metric (1) is used to find pairs of nearest events from two catalogs. After that, the classification of events into unique and duplicates is carried out using the threshold value of the metric. A basic three-parameter model is used, where the metrics for assessing the proximity between earthquakes take into account the time difference \(DT\), and epicenter difference in the longitude \(DX\) and latitude \(DY\). Depth information is not used, since the depth of hypocenters is often unknown or given as a fixed value for many events. Magnitudes are also not used, since earthquakes have magnitude estimates of different types from various agencies. \[Ro=\sqrt{\frac{DT^{2}}{\sigma_{T}{}^{2}}+\frac{DX^{2}}{\sigma_{X}{}^{2}}+\frac{ DY^{2}}{\sigma_{Y}{}^{2}}}, \tag{1}\]  
where \(\sigma_{T}\), \(\sigma_{X}\), and \(\sigma_{Y}\) are the standard deviations of time, longitude, and latitude differences between the closest events from two source catalogs. Before the merging process, each of the source catalogs (Table 1) was checked for internal duplicates. Statistical analysis did not reveal any anomalous groups of close events (Figure 2). It should be noted that duplicates typically have a metric value (1) \(Ro<10\)[1; 7]. The number of such close events within each catalog is small, and there are no statistical