Vol 23, No 5 (2023)

A method for solving conjugation problems for the Poisson equation is implemented, which makes it possible to interpret potential fields (gravitational and stationary thermal fields) based on unified grid algorithms. A numerical algorithm has been developed for recalculating the mantle component of the heat flow from the level of the earth’s surface to the “crust–mantle” boundary through a layered medium inhomogeneous in thermal conductivity. Paleoclimate corrections were introduced into the measured values of the temperature gradient and heat flux for the northern territories. In the axial part of the Ural geosyncline, it was possible to exclude the negative depression of the mantle component of the heat flow, obtained from the results of geothermal modeling; taking into account the Pleistocene-Holocene warming of the preceding interglacial paleoclimate cycle leads to positive values of the heat flow recalculated to the “crust–mantle” boundary. It is shown that the use of heat flow data can significantly increase the geological information content of gravity modeling.

In recent years, active development of coal deposits and works related to the creation of appropriate infrastructure (ports, roads, etc.) have been carried out in the western part of the Taimyr peninsula. The main objects are the port Buhta Sever (oil loading terminal), the Syradasay coal deposit and the port Yenisei. Work is also underway in the Lembersk coal mine and the associated port Dixon. The single seismic station “KOLBA” of the Arkhangelsk seismic network installed in October 2020 near Dixson regularly registers local seismic events, the natural nature of which is questioned. From October 2020 to February 2023, 150 seismic events with a magnitude range of ML from 0.4 to 2.4 were registered at distances up to 200 km from the seismic station. The purpose of our research is to give a reasonable answer on the basis of selected criteria about the nature of registered local events: earthquakes or man-made events. Cleaning seismic catalogs from man-made events has always been an urgent task, especially after the installation of each new seismic station in a little-studied area of the Arctic. The difficulty in determining the event nature lies in the absence of a regional hodograph and any reference data such as samples of waveforms, reliable information about the place, time and methods of industrial explosions, the absence of these events on the records of other seismic stations. In this regard, we have defined a set of criteria for determining the nature of events, which are reduced to the consideration of indirect signs. These are the location of an event near an industrial facility, the analysis of spectral-time diagrams and waveforms of seismic events, the analysis of the amplitudes ratio of volume and / waves, the daily distribution of seismic events and the magnitude range of recorded events. Despite the fact that individually each criteria is not a direct proof of the man-made events nature, their totality can be taken as a decision to exclude the event from the seismic catalog. In the process of determining the epicenters of events, we identified several groups related to various industrial facilities. The daily distribution diagram shows that local seismic events were recorded in the daytime with peak values at 13–14 hours and at 19–20 hours, which indicates the technogenic nature of events. The / ratio is < 3.0 for all events, which most likely also indicates a technogenic nature, as with the presence of “bands” in the high frequency range on the spectral-time diagrams. The developed set of criteria for the identification of technogenic events allowed us to clean up the seismic catalog and attribute all 150 events to the manifestation of technogenic seismicity. The most effective criteria are the analysis of spectral-time diagrams, the / ratio and the daily distribution of events. In some cases, by the waveform types, it is also possible to determine whether an event belongs to a certain industrial facility (in particular, to the port of Buhta Sever).