Sources of recent tectonic stress in the Pannonian region:inferences from finite element modelling

Abstract

We present the results of finite element modelling of the recent stress field in the Pannonian basin and surrounding Alpine orogenic belt. Our results show that the recent, predominantly compressive, stress regime in the Alpine-Pannonian-Carpathian-Dinaric system is governed by distinct tectonic factors. Of great importance is the deformation of crustal blocks with different geometries and rigidities in an overall convergent setting associated with the Africa-Europe collision. The most important stress source appears to be the counterclockwise rotation of the Adriatic microplate at the southwest boundary of the Pannonian basin. This plate tectonic unit has been interpreted as moving independently of both the European plate and the African plate. Additional boundary conditions-active shortening and compression in the Vrancea zone and the Bohemian Massif, and the effect of the immobile Moesian Platformalso significantly influence the modelling results. The incorporation of additional stress sources such as crustal thickness variation and the presence of two main fault zones separating the primary tectonic units in the study area have only locally important effects but improve the fit between the calculated results and the observed stress pattern.

Attached or not attached—evidence from crustal stress observations for a weak coupling of the Vrancea slab in Romania

“…This corresponds also to the rapid change of along strike fault kinematics (Matenco et al, 2007). Our analysis thus differs from the analysis of Bada et al (1998) who see a uniform regional WNW stress trend in this region. According to Heidbach et al (2007a), there are three potential reasons for this difference: (a) the smaller number of stress data used by Bada et al (1998b) that cannot adequately represent a variable stress pattern, (b) different smoothing parameters that greatly emphasize the regional trend and show less data fidelity, and (c) Bada et al (1998) might have used the subcrustal intermediate depth Vrancea earthquakes in the smoothing, whereas our stress analysis is based on crustal stress data records from a depth between 0 and 40 km only.…”

“…In several papers the pattern of maximum compressive horizontal stress of Romania is described as a long wave-length pattern with preferred SW-NE orientation in western Romania, that is ascribed to a NE-push of the Adriatic plate, and a swing to NW-SE orientation in the Vrancea region believed to result from a NW-push from the Vrancea region (Morley, 1996;Bada et al, 1998;Gerner et al, 1999). Mantle processes in this region are dominated by subducted lithosphere beneath the SE corner of the Carpathian arc (Morley, 1993;Tomek and Hall, 1993;Nemcok et al, 1998).…”

Geokinematics of Central Europe: New insights from the CERGOP-2/Environment Project

“…This rigid block is flanked by units in the south and the east with a lower rheological strength. This rheology contrast is reflected by the radial stress pattern around the Southern Bohemian Massif (Reinecker and Lenhard, 1999;Bada et al, 1998). The stress trajectories are perpendicular to boundaries of high rheological contrast.…”

Seismic Hazard in the Pannonian Region

“…Deformation in the Pannonian basin system is ongoing (Bada et al 1998, Horváth andCloetingh 1996). One of the most direct pieces of evidence for the continuing deformation, in addition to GPS geodetic data (Grenerczy et al 2002), is current seismic activity ).…”