Present crustal movement and strain distribution in Central Europe inferred from GPS measurements

Abstract

In 1992, an international collaboration was initiated to study the present‐day geodynamics of Central Europe. The primary tool of this research is the Global Positioning System (GPS) therefore the Central European GPS Geodynamic Reference Network was established in 1994. The network extends from the south in the Eurasian‐African plate boundary zone to the East European Pre‐Cambrian Platform in the northeast. During the first phase of the project four GPS campaigns were organized between 1994 and 1997. Analysis of GPS data provided RMS repeatabilities around 2 mm in the horizontal and 5–6 mm in the vertical component for each campaign. The velocities of GPS sites situated on the Eurasian plate were compared with those predicted by the NNR‐NUVEL‐1A plate velocity model. The intraplate velocity field shows that the northern part of Central Europe seems generally stable with velocities under 2 mm/yr. However, the southern sites close to the plate boundary zone show higher values and abrupt changes of velocities indicating the existence of narrow deformation zones. The primary feature revealed by the strain calculation in the Alpine‐Pannonian‐Dinaric system is the dominant north‐south contraction resulting from the collision of the African and Eurasian plates transmitted by the Adriatic microplate. However the direction of contraction in the Alpine‐Pannonian‐Dinaric junction zone changes from NW‐SE at the northeastern boundary of the Adriatic microplate to NE‐SW toward the Bohemian Massif. The magnitudes of these strain rates are similar, −8.0±5.3 ppb/yr and −8.6±2.5 ppb/yr, respectively over ∼200×350 km subnetworks. We observe E‐W oriented (93°±13°) right‐lateral shear (12±5 ppb/yr), between the Alpine‐North Pannonian unit and the southernmost sites in the Dinarides and Southern Alps, along with left‐lateral shear (97°±7°; 10±2 ppb/yr) relative to the stable Bohemian Massif in the north. Both the strain field and the intraplate velocities presented show that the Alpine‐North Pannonian unit is presently crushed out to the east with 2 mm/yr velocity on average along two main fault zones as a consequence of the compression caused by the Adria‐Alpine collision.