SOURCES OF RECENT TECTONIC STRESS IN THE PANNONIAN REGION - INFERENCES FROM FINITE-ELEMENT MODELING

We present the results of finite element modelling of the recent stres s field in the Pannonian basin and surrounding Alpine orogenic belt. O ur results show that the recent, predominantly compressive, stress reg ime in the Alpine-Pannonian-Carpathian-Dinaric system is governed by d istinct tectonic factors. Of great importance is the deformation of cr ustal blocks with different geometries and rigidities in an overall co nvergent setting associated with the Africa-Europe collision. The most important stress source appears to be the counterclockwise rotation o f the Adriatic microplate at the southwest boundary of the Pannonian b asin. This plate tectonic unit has been interpreted as moving independ ently of both the European plate and the African plate. Additional bou ndary conditions-active: shortening and compression in the Vrancea zon e and the Bohemian Massif, and the effect of the immobile Moesian Plat form-also significantly influence the modelling results. The incorpora tion of additional stress sources such as crustal thickness variation and the presence of two main fault zones separating the primary tecton ic units in the study area have only locally important effects but imp rove the fit between the calculated results and the observed stress pa ttern.