New method of estimating regional stress orientations: application to focal mechanism data of recent British earthquakes

It is demonstrated how a recently devised graphical method for estimating palaeostresses from exposed striated fault planes can be adapted for use with earthquake focal mechanism data. Provided the data set includes one or more earthquakes for which the fault plane can be identified, the principal stress directions can be determined more precisely than by using the alternative Right Dihedra method. Using the new so-called Right Trihedra method stress directions are found which are compatible with recent British earthquakes. The method can also be used, in the case of some focal mechanisms, to resolve the ambiguity regarding which focal plane corresponds to the fault plane.