S U M M A R Y2-D elastic finite element models of the recent stress field of Central Europe are built to evaluate the loads exerted on the continental boundary and the magnitude of tectonic stresses within the continental part of the plate. The models comprise 24 tectonic blocks (their stiffness is either constant throughout the model or varies from block to block), 16 fault zones and 12 geologically significant boundary segments. We have obtained a relatively unique balance of external tectonic forces by (1) careful adjustment of calculated stress directions and regimes to complex pattern of stress from data and (2) by calibration with gravitational potential energy. A high level of compression (ca. 9 × 10 12 N m −1 ) exerted to the short Ionian side of the Adriatic indenter is crucial for the stress-field pattern in Central Europe. The Adria microplate rotates due to eccentricity between the Africa push from the south and the Alpine buttress to the north. A free boundary of the Apennines does not contribute significantly to this motion. Kinematics of this indenter is controlled by friction on the Dinaric suture, which, in turn is decisive for strain-energy distribution between the Alpine and the Pannonian domains. The predicted pronounced extension in the Greece-Aegean segment (2.5 × 10 12 N m −1 ) implies active pull transferred from the Hellenic subduction zone. This extension releases stress in the Balkan-Pannonian region and enables the eastward escape of tectonic blocks in front of advancing Adria. Significant changes of tectonic push trends are found along the Black SeaCaucasus boundary segment and at the European passive margin from the North Sea to the Arctic Ocean. Differential stresses in Central Europe are estimated in the range of 10-60 MPa when averaged over the 30-80-km-thick mechanically heterogeneous lithosphere. The maximum stiffness contrast across the model is predicted to be of one order of magnitude. Apparent friction coefficients of fault zones differ between the North European part of the plate (0.4-0.7), the Pannonian region (0.15-0.25) and the Dinaric suture (0.55).

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2 Pol ish Geo log i cal In sti tute -Na tional Re search In sti tute, Rakowiecka 4, 00-975 Warszawa, Po land Tomaszczyk, M., Jarosiñski, M., 2017. The Kock Fault Zone as an in di ca tor of tec tonic stress re gime changes at the mar gin of the East Eu ro pean Craton (Po land). Geo log i cal Quar terly, 61 (4): 908-925, doi: 10.7306/gq.1380 In te grated tec tonic in ter pre ta tion of seis mic data and core sam ples from bore holes in the vi cin ity of the Kock Fault Zone (KFZ) al lowed us to iden tify sev eral tec tonic de for ma tion events that were re spon si ble for cre at ing its com plex struc ture. The KFZ is an ex am ple of a me chan i cally weak re gional-scale tec tonic struc ture that ac cu mu lated de for ma tion over hun dreds of mil lions of years and there fore is a good in di ca tor of stress re gime changes in a broader area. The KFZ is here re garded as a com bi na tion and su per po si tion of two ge net i cally and tem po rally dif fer ent faults: the older Kock Fault, which is an in verted nor mal fault, and the youn ger, low-an gle Kock Thrust. The first, Si lu rian stage of KFZ evo lu tion oc curred in a ten sional stress re gime that gave rise to the ac ti va tion of a deeply rooted nor mal-slip pre cur sor to the Kock Fault. Sub se quently, this fault under went in ver sion dur ing the Late Famennian com pres sive/transpressive event. In the Early Car bon if er ous, the tec tonic stress re gime changed into ten sion/transtension, lead ing to ex tru sion of ba salt magma and abun dant mineralisation in the vicin ity of the in verted Kock Fault, fol lowed by tec toni cally re laxed sed i men ta tion of Car bon if er ous strata. The de po si tion was ter mi nated by a compressional event at the end of the Westphalian. Con trac tion re sulted in the for ma tion of the low-an gle Kock Thrust de coup led in Si lu rian shale that cut across the up per part of the Kock Fault and dis placed it to wards the NE, over the East Eu ro pean Craton fore land.

The paper concerns investigation of the credibility of tectonic interpretation of GNSS strain rates. The analysis was focused on stable regions, where the crustal deformations are small and the reliability of GNSS velocities is questionable. We are showing how the unreliable motion of stations affects calculated strains around them. We expressed distribution of local principal strains by a sinusoidal function and used them to investigate the significance of strain distortion. Then we used this method to investigate real motions of GNSS stations. As a test object we used Polish GNSS stations belonging to the ASG-EUPOS network. Station velocities were estimated on the basis of the 4.5 years of observations. The results let us identify stations that disturb the obtained local GNSS strain rate field. After verification and exclusion of some stations, the new GNSS strains show a much greater internal compatibility and also better fit to the directions of lithosphere stresses.