Hortus Botanicus (Dec 2021)
Satellite geodynamic monitoring in Karelia and adjacent regions
Abstract
A review of satellite navigation systems (GNSS) and their application in geodynamic studies is made. The results of studying geodynamic processes using GNSS performed by the staff of the IFZ RAS in the north-western region of Russia, including Karelia, in particular at the geodetic point BOTS in the Botanical Garden of Petrozavodsk State University, are analyzed. The results of calculating the velocities of horizontal and vertical movements, areal deformations, as well as their comparison with the seismicity of the region, are presented. Satellite geodetic points for observations of deformation processes in the region began in the 90s of the 20th century. The BOTS point was founded in 1999 as part of Karelian test-site. It is located on a rocky outcrop of bedrock, which excludes its landslide displacement with the upper layers of the soil. It is a concrete monument with a forced centering system. The duration of repeated continuous satellite measurements at the point is 5–7 days, which is a guarantee of the high quality of the measurements. The vertical and horizontal velocities of the earth's surface of the region reveal the postglacial uplift of the Baltic Shield at a rate up to 10.4 mm/year, not exceeding 5–6 mm/year for the Russian territory. Horizontal movements of the East-European tectonic plate have a NE direction and average 23 mm/year. Intraregional horizontal displacement velocities in Karelia and Leningrad region in the local reference system are mainly in SE direction and are about 3–4 mm/year, for the BOTS — 3.8 mm/year. In addition the velocities of points, much attention is paid to the study of areal deformations and the modern seismic regime. The method of analyzing the deformation of the Earth's crust revealed the presence of alternating zones of stretching and compression with deformations (–0.8)×10-8 – 1.6×10-8/year. The territory has weak seismic activity. Since 2000, about 200 seismic events with magnitudes (Ms) 0.7–4.1 have occurred within the territory under consideration. A large intensity of seismic events is inherent to the dome uplift of the Fennoscadia. Seismicity within the territory under consideration is rather heterogeneous, with areas timed to zones of transitioning from stretching to compression, or to zones of stretching; the Baltic-Ladoga region of seismic activity is identified, marking the transition zone from the dome to the platform. The results of the studies using GNSS technologies and seismicity analysis allow us to assess the current tectonic activity of Fennoscandia and the features of its manifestation in the first twenty years of the current century. The comparison of the velocities of displacements, deformations and seismicity determines the quantitative characteristics of the modern geodynamics of the studied region for a specific time interval. Further development of the geodetic observation network in the north-western part of the East European Platform will allow expanding and clarifying the available data on the geodynamic regime of this region.
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