Technischer Bericht NTB 84-45
Comparison of focal mechanisms with local neotectonic structures in Northern Switzerland shows, in many cases, a good correlation between the orientation of nodal planes of the fault-plane solution and the orientation of fault-systems observed at the surface. Focal depths of 10 – 25 km indicate that some of these fault-systems cut deep into the crystalline basement. From the orientation of P-axes and T-axes it is concluded that the upper crust of Northern Switzerland undergoes a NNW-SSE maximum horizontal shortening and a WSW-ENE maximum horizontal extension. The stress field which causes the present seismicity in Northern Switzerland is very similar in its orientation to the stress field of the last 5 to 8 million years which produced the neotectonic deformation.