Polar graphs of initial motions at an earthquake source

abstract A modified technique for fault-plane solutions is developed, using polar diagrams with the earthquake focus at the origin and with station azimuth and angle of incidence at the focus as co�nates. A figure is given illustrating the distribution of initial longitudinal motion in a perfectly general case for a plane fault source with rectilinear slip, together with all the special cases which can be derived from it. Formulas are given which combine all the quantities entering into the solution.