# Integrated Earthquake Catalog III: Gakkel Ridge, Knipovich Ridge, and Svalbard Archipelago
## 4 Conclusions  
In this paper, the data from seismic catalogs of various monitoring networks were generalized and integrated using the author's technique [26] based on statistic distribution analysis. The target was to create the most complete and representative earthquake catalog of the Gakkel and Knipovich ridges, as well as the Svalbard Archipelago. The magnitude estimates were unified in the obtained integrated catalog. The earthquake epicenter map of the integrated catalog is shown in Figure 20. The integrated catalog was made available to the public on the website of the World Data Center for Solid Earth Physics, Moscow, at [[http://www.wdcb.ru/arctic_antarctic/arctic_seism.html](http://www.wdcb.ru/arctic_antarctic/arctic_seism.html)]([http://www.wdcb.ru/arctic_antarctic/arctic_seism.html](http://www.wdcb.ru/arctic_antarctic/arctic_seism.html)) (accessed on 1 August 2023). Based on the conducted study and obtained results, the authors consider it possible to formulate the following conclusions:  
1. The earthquake catalogs of the studied region (the Gakkel and Knipovich mid-ocean ridges plus the Svalbard Archipelago) are a mixture of data from a large number of agencies. Moreover, the catalogs significantly vary over time. As a result, heavy tails appear in the \(DT\), \(DX\), and \(DY\) distributions. Therefore, determining the threshold value of the metric using the methodology applied in [27; 28] leads to an increased probability of missing duplicates. For this reason, in this study, we decided not to use a multivariate normal distribution model. Instead, the actual distribution of the metric for the nearest events from two combined catalogs was used. As a result, the estimated number of errors in the integrated catalog does not exceed 1%;
2. The integrated catalog contains 17,922 events; 16,933 are from the ISC and 989 events are from Russian catalogs. The latter were not presented in the ISC, while the information regarding 578 events from Russian catalogs was used as a part of the ISC data. In the Gakkel Ridge, Russian data accounts for more than a quarter of events, and more than half after 2012. In the sub-regions of Svalbard and Knipovich, the addition of ISC data with Russian catalogs is insignificant. However, an important aspect here is the unification of magnitude;
3. The ratios between local magnitudes \(ML\) with the reference magnitude \(MW^{\rm GCMT}\) and \(m\)\(l\)\(l\)\(l\)\(l\)\(l\) significantly differ in Svalbard and mid-ocean ridges. In Svalbard, the difference between the local and moment magnitudes is about 0.3 (Table 3). In the Knipovich and Gakkel ridges, the estimates of local magnitudes are significantly underestimated compared to the moment magnitude, with a difference exceeding 1.0 (Tables 4 and 5). Figure 25 shows the frequency-magnitude distributions constructed using original magnitudes. In Svalbard, noticeable discontinuities in the distribution are observed (Figure 25a). This can significantly affect the estimates of the b-value (the slope of the magnitude-frequency plot), which is an important parameter in seismic hazard assessment. The distribution in the Knipovich Ridge (Figure 25b) has a bimodal character, which contradicts the Gutenberg-Richter law. This is an independent confirmation of the inconsistency of magnitude estimates \(ML\) and \(MW^{\rm GCMT}\), \(m\)\(l\)\(l\)\(l\)\(l\)\(l\)\(l\)\(l\)\(l\). In the Gakkel Ridge (Figure 25c), the distribution weakly follows the Gutenberg-Richter law. After the proposed magnitude conversion, the magnitude-frequency plots acquired a common form (Figures 21b, 22b and 23b);
4. When creating the unified magnitude scale, ratios were used with three types of magnitude, \(MW^{\rm GCMT}\), \(m\)\(l\)\(l\)\(l\)\(l\)\(l\)\(l\)\(l\)\(l\), and \(ML^{\rm BER}\), which are well represented in the studied region. The shift-type ratios turned out to be very similar for most magnitudes of different types determined by various agencies.