1987 Volume 35 Issue 2 Pages 171-190
A simple method is developed for rapid determination of fault parameters of a large shallow earthquake from the azimuthal dependence in duration of strong ground motion. The fault length and the direction of rupture propagation can be evaluated by this method within a short time after the earthquake origin time. As an example, the fault parameters are determined for the Tokachi-Oki earthquake of May 16, 1968. They are consistent with the main rupture process revealed by other investigators from far-field long-period seismic records, near-field strong motion records and aftershock distribution. Thus, the present method may be applicable to near-field tsunami warning, provided that a sufficient number of digital accelerographs are installed with a good azimuthal coverage.