**1. Introduction**

The European sector of the Arctic region is an element of a geodynamic system that includes the ancient Eurasian continent and intensely developing younger Arctic Ocean. Seismic, gravity and geothermal fields establish a structural-density inhomogenuity of the crystalline basement and sedimentary cover, show the nature of the heterogeneous blocks compound of Earth's crust, etc. Deep crustal processes are marked by heat flow and peculiarities of stress-strain state reflected in parameters of the seismic regime. The great volume of collected geological and geophysical data has revealed complex and spatially heterogeneous structures of the Earth's crust and upper mantle in this region [1–8]. The peculiarities of lithosphere forms the causes in changes in thickness and "disappearance" of granitic-gneissic layer beneath deep basins; all of this is still disputable [3, 8].

Significantly, to date, the methodology of seismotectonic formation and its relationship with geodynamics that are investigated are not enough. Small attention is paid to the study of the relationship of weak seismicity and the deep structure, the definition of suture form zones of the crystalline basement, and the connection on structural places, primarily in the sedimentary cover.

The European sector of the Arctic region is considered aseismic; however, the number of seismic events recorded here in the period of 1998–2017 with respect to

**Figure 1.**

*Scheme showing locations of profiles A–B and C–D, geotraverses, and deep seismic profiles in water area (1-AR, 2-AR, 3-AR, 4-AR, DSS-82) and on land (Kvarts, Pechora, Rift, SW Vorkuta) in studied region.*

improvements of Arctic seismic networks suggests a need for revision. The contemporary seismicity and heat flow density are indicators of geodynamic processes [9]. Joint analysis of these fields will allow a better understanding of the regional geodynamics, and such analysis is the aim of this study.

For this, a unified seismic catalog based on data from seismic networks that monitor the studied region was compiled; we generalized data of deep geological and geophysical cross sections of the crust and upper mantle along geotraverses [10–13] (**Figure 1**) and employed data on the spatial heat flow distribution [14–17]. Based on an analysis of the geological and geophysical data, we summarized the cross sections along the A–B and C–D profiles, which reflect the main structural features of the lithosphere in the region and make it possible to consider the relationship between the seismicity, heat flow density, and tectonics.
