Abstract
The source process of the Japan Sea earthquake of May 26, 1983 is studied by using the long-period surface waves and tsunamis. The moment tensor inversion of Rayleigh waves which consider the lateral heterogeneity of the Earth is developed and applied to the IDA records of this event. The moment tensor solution and first-motion data indicate that the mechanism is dip-slip and the seismic moment is 7.6 × 10 27 dyne-cm. The fault is estimated to be 120 km in length, 40 km in width, and dips eastward with a dip angle of 30° from the aftershock distribution. Tsunami simulation for an actual topography is made to restrain the slip on the fault. The aftershock area and the tsunami records suggest that the fault is divided into two segments. The northern part strikes NNW and slips 4 m, while the southern part strikes NNE and slips 5 m. The fault geometry, the aspect ratio, and the stress drop of this event are similar to those of the 1964 Niigata earthquake, but differ from those of the earthquakes in the Pacific coast of Japan.
Published Version
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