Stationary phase approximation in focal mechanism determination
abstract Tests of the stationary phase approximation method applied to P waves for the determination of focal mechanisms have been carried through for eight earthquakes selected from different geographic locations and depth ranges. The results are found to be in close agreement with the solutions obtained from S-wave polarization data for four earthquakes and in reasonable agreement for three earthquakes. In general, however, the P polarities are more consistent with S-wave polarization solutions than with the solutions obtained by the present method. The stationary phase solutions agree with the P-wave spectrum solutions determined in a previous study. The method is applicable to shallow-focus earthquakes, and to earthquakes of large magnitude in which methods using S-wave polarization data and P-wave spectra are difficult to apply.