Seismogenic deformations in early holocene sediments of the Pechenga River Terrace (Kola Peninsula)

Abstract

The Kola Peninsula, an element of the northwestern Baltic Shield, is not a high-seismicity region at present. This has not always been the case, however, as is evident from seismic paleodeformations reflecting strong earthquakes. The latter were discovered in the course of geologic‐geomorphologic works and the analysis of air photos of mainly crystalline rocks [1]. Morphologic patterns and genetic aspects of deformations in incoherent sediments of the Kola region have yet to be sufficiently studied despite the fact that many researchers have reported such structures. Their origin is usually attributed to glaciotectonic and cryoturbation processes. Indeed, distortions of such kind are widespread in Quaternary sediments, because the region under consideration was repeatedly subjected to glacial impact. At the same time, deformations in incoherent sediments were also caused by other phenomena—those related to the strong seismic impact. Deformations in incoherent sediments provoked by modern earthquakes are known not only in seismoactive regions, but also in territories of moderate seismicity, such as Canada, Fennoscandia, and Russia [2‐5]. Recently, special studies were carried out to define different types of deformations in Quaternary sediments exposed in quarries and natural outcrops along river banks in the northwestern Kola region (Fig. 1) and to discriminate them from those related to the glacial impact.