Crustal deformations of the GPS polygon of the Ignalina NPP: application of finite element modelling for geodynamic implications

Abstract

The horizontal movements of the Earth’s surface were measured in a GPS polygon in the Ignalina NPP area. The network consists of ten GPS sites established in 1998. The network was designed according to the tectonic framework. Two cycles were carried out in September 1998 and September 1999. The average quadratic error does not exceed 1.2 mm. The modelling of crustal deformations and stresses was performed using a finite element modelling (FEM) technique (ANSYS). Significant tectonic strain was recognised in the INPP area. The stress field shows consistent variations in the polygon that is seemingly controlled by the large-scale Drūkšiai fault trending west-east. The most distinct disturbance of the regional stress field is recognised in the east close to the INPP, while the role of the fault is somewhat less in the west. The modelling results demonstrates the utility of the tensor method and the FEM technique for interpretation of the GPS measurements.