# Integrated Earthquake Catalog II: The Western Sector of the Russian Arctic
## 3 Results
### Integrated Catalog of the Western Sector of the AZRF
#### 3.1.4 Stage 4. Exclusion of Explosions and Other Anthropogenic Events  
The preliminary exclusion of explosions and other anthropogenic events was performed based on the information on the nature of the events provided in the source catalogs. However, events marked as \"non-earthquake\" in one catalog may not be marked as such in other catalogs. We considered an event as a \"non-earthquake\" if it was marked as such in at least one of the input catalogs. In addition to the information from the ISC and VEP catalogs, data from the \"Earthquakes of Russia\" ER_EXP merged catalog (Table 1) were used.  
Figure 8: Distributions of the metric for the Morozov/ISC_RUS event pairs. The threshold value of metric \(Ro=20\) is indicated by a dashed line.  
Figure 7: Distribution of normalized \(DT\) and \(DR\) and contour line of metric (1). Colored dots represent ISC/RUS pairs (blue dots are duplicates, pink dots are unique events), and black dots are distances between RUS/RUS events in metric (1). The values of the metric for earthquakes in the RUS catalog are significantly larger than for ISC/RUS duplicates (blue dots). The contour line of metric (1) \(Ro=20\) provides a close to optimal separation of duplicates and naturally grouped events. Absolute duplicates are not shown.  
Explosions and other anthropogenic events presented in the ER_EXP, VEP_EXP, and ISC_EXP catalogs (Tables 1 and 3) were sequentially removed from the W_ARCTIC0 merged catalog obtained in the previous stage. Duplicate analysis was performed with standard distribution parameters \(\sigma_{\rm T}=0.05\) min, \(\sigma_{X}=\sigma_{\rm Y}=15\) km, and a threshold value of metric \(Ro=10\). A total of 380 duplicates were detected (Figure 9). These events were excluded from the W_ARCTIC0 catalog. The final integrated earthquake catalog, W_ARCTIC, for the western sector of the AZRF contains 4686 events. Table 3 provides statistics and parameters used at each step for excluding non-earthquake duplicates.  
The results of the analysis of the final W_ARCTIC catalog suggest that explosions were not completely excluded. The histogram of the number of events (Figure 10a) shows an abnormally large number of events in 1994-1997 and 2021-2022. The spatial and spatiotemporal distribution of events (Figure 10b,c) also indicates an incomplete removal of explosions during these years. In this sense, the period of 1989-1993 also raises some suspicions. We were unable to find reliable sources of information on explosions during these periods.  
In the area of the Severouralsk bauxite deposit (coordinates 60\({}^{\circ}\) N, 60\({}^{\circ}\) E) in the Northern Urals, there is a significant cluster of 57 events. According to [32], this area experiences a large number of technological explosions and rock bursts (hundreds per year). Therefore, we assume that most of the events in this cluster are not earthquakes, although this is not indicated in the catalogs used (Table 1). All 46 events that occurred in 2021-2022 are highly likely to be explosions (the information about explosions has not yet been published for this period). The other 11 events, if not explosions or rock bursts, are likely to be triggered earthquakes. Based on this, a decision was made to exclude events from the catalog that are part of the identified Urals cluster. The final integrated W_ARCTIC catalog contains 4629 events.