Geophysical processes and biosphere: article

Аnnotation: As a result of the performed review of methods for the allocation of group events, it is argued that to date there is no universal algorithm for detecting formations of physical nature in the structure of seismicity. Therefore, the method of catalog declasterization should be selected both for the existing structure of the source data and for a specific task. It is proposed to use the declasterization of earthquake catalogs with great caution, since such a procedure can significantly distort the magnitude of the seismic hazard assessment. A lot of work has been done to collect information about earthquakes in the Yano-Indigirskaya lowland in northern Yakutia that was practically not studied in seismic terms. The analysis of data of 43 seismological agencies resulted in the catalog of 3161 earthquakes from 1920 till 2020 that has been compiled with a representative magnitude of MW = 3.3. To distinguish the grouped events, the catalog was declasterized using different methods; the seismicity has been also divided into concentrated (group) and scattered (background) components. It is shown that these components significantly differ in recurrence plots and Mmax estimates, which significantly effects the seismic hazard assessment. Attention is drawn to the need to develop algorithms capable of identifying linear sequences of earthquake epicenters connected in space and time, marking elements of tectonic fracturing.