Morphotectonics of the Imandra–Kolvitsky Fault and Parameters of the Focal Zone of Paleoearthquakes in the Luvenga Tundra (Kola Peninsula)

Abstract

Detailed paleoseismogeological studies have been carried out in the area of the Kandalaksha low-mountain massifs on the Kola Peninsula (northeast Fennoscandian Shield). In order to identify traces of paleoearthquakes, parametrization, and dating of events, a set of methods was used, including analysis of satellite images and digital elevation models (DEM), ground-based geological and geomorphological mapping, structural and tectonophysical studies, drilling of lakes in fault zones, and selection and radiocarbon (¹⁴C) dating of paleosols. The study of various groups of seismic disturbances in topography and rock massifs (seismotectonic, seismogravitational, seismovibrational), as well as morphotectonic data, allowed us to identify the large Imandra-Kolvitsky seismotectonic zone extending over 100 km in the southwest Kola Peninsula. As a result of the research, it was found that the zone inherited from the Precambrian showed activation in the Late Glacial and Holocene. The identified areas of seismic deformations, surveyed in the area of the Luvenga Tundra key site, allowed us to establish that there were epicenter zone of seismic fault, the intensity of which ranged from IX to VIII in the Late Glacial with a decrease in the Holocene. The seismic fault has a dextral strike-slip kinematics with a thrust component, implemented in the stress field of the meridional (NNE) maximum compression and wide-latitude (WNW) stretching. New data on estimating the age of paleoearthquakes indicate the four most likely events in the Holocene (ka cal BP): (1) ≈10.4; (2) ≈7.5; (3) ≈2.8–3.0; (4) ≈0.38. The conducted research can be used to develop scientific and methodological foundations for assessing the risks of catastrophic processes, updating earthquake catalogs and databases on active faults, as well as preventing seismic hazards of platform territories.