Integrated Earthquake Catalog II: The Western Sector of the Russian Arctic

Abstract

The article is a continuation of the research on creating the most complete and representative earthquake catalogs by combining all available data from regional, national, and international seismological agencies and reducing magnitudes to a uniform scale. The task of identifying and removing duplicates that arise during the merging process is solved using the authors’ modification of the nearest neighbor method. It is evident that the intelligent merging of different earthquake catalogs for the same territory will improve the completeness and representativeness of events in the final integrated catalog. In this article, the earthquake catalog of the western sector of the Arctic zone of the Russian Federation (AZRF) covering the period 1962–2022 was created by merging three regional Russian catalogs and the ISC catalog. The ratio of magnitude types in the catalog for different seismic networks was analyzed, and magnitude estimates were unified based on the obtained ratios. For analyzing seismic activity in the western AZRF, it is recommended to use earthquakes from the period 1998–2020 when the catalog was significantly cleaned from explosions and other events of the “non-earthquake” type.

Integrated Earthquake Catalog of the Ossetian Sector of the Greater Caucasus

“…As noted above, the author's method, used in the present study to identify duplicates that arise when earthquake catalogs are sequentially merged, is described in detail in [1] (see Supplementary Materials). The application of this method to create the most complete earthquake catalog with a unified magnitude scale for the Arctic zone of the Russian Federation is given in [4][5][6]. For this reason, a description of the method is not provided in this article.…”

“…When merging catalogs, the preference is given to earthquake records from the ISC catalog that have magnitude definitions MW GCMT and/or mb ISC and/or mb 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.…”

“…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. In this situation, the application of the method used in [4,5] to determine the threshold value of the metric leads to an increased probability of missing duplicates. Therefore, in the present paper the actual distribution of the metric for the nearest events from the two catalogs being merged is used instead of the multivariate normal distribution model.…”

“…Red lines in Figures 5b, 7b and 9b show the value 1 − Fdub, which is considered to be the probability of missing a duplicate (error of the I kind). The probability of a false duplicate (error of the II kind) is estimated in the same way as in [4,5]. For this reason, the values of the metric (1) Ro between events inside the additional catalog are calculated: blue lines in Figures 5b, 7b and 9b show the fraction of events with proximity less than a given Ro value.…”

“…It allows the identification and removal of duplicate events that occur when the catalogs are merged. Previously, the integrated catalog was elaborated for the Arctic zone of the Russian Federation [4][5][6]. It is demonstrated that merging catalogs of various global, national, and regional seismic networks makes it possible to improve the completeness and representativeness of seismic events in the studied region [7][8][9][10].…”