Origins of the European regional stress field

We present a study of the origins of the European regional stress field. Intraplate stresses due to various plate boundary forces and intraplate stress sources were predicted using an elastic finite element analysis. The finite element mesh consists of about 1629 nodes in a network of 3117 triangular elements which provide a spatial resolution of about 1 degrees. The study builds on the previous modelling studies through consideration of a wide range of plausible forces acting along the collisional eastern and southern plate boundaries and, importantly, through the inclusion of forces due to other lateral density variations within the lithosphere, such as those associated with the continental margins and high topography. The modelling was constrained by more than 1800 stress indicators from the World Stress Map Project which provide information about the orientation of the observed maximum horizontal compressive stress, S-H. The torque associated with the ridge push force is well constrained and the principal source of uncertainty relates to the boundary conditions used to represent the collisional resistance acting along the eastern and southern boundaries. A gradient in the collisional resistance increasing in magnitude from west to east is assumed to act along the southern plate boundary, whereas the eastern boundary is modelled as a pinned margin at 46 degrees E. The S-H orientation and magnitude of the regional stress field was found to be largely invariant to the boundary conditions used to represent the tectonic forces acting along the eastern and southern margins, and is characterized by a nearly uniform NW-SE compression with a magnitude in the range of 10-20 MPa averaged over a 100 km thick lithosphere. Lateral density variations within the continental areas of Europe were found to reduce the magnitude of the predicted stresses but do not have a significant effect on the orientation of the regional stress field.