" Weekend effect, or, more generally, a specific weekly cycle (septan variation) were found in the magnetosphere [Guglielmi and Zotov, 2007] (Pc1 wave activity) and lithosphere [Zotov, 2007] (global seismic activity) ...
... The main conclusion is that the weekend effect is the real geophysical phenomena, and evidently human in origin. This effect indicates that there is some nontrivial impact caused by industrial activity on the natural processes in the lithosphere."