The excitation strengths of high-frequency strong motions from intermediate depth earthquakes (IDE) are investigated from the peak ground accelerations (PGA) of 13 events occurring at Eastern Japan. 13 shallow earthquakes at the same region are also analyzed for comparison. The observed PGA's from IDE's show systematically larger amplitude than the empirical average obtained from shallow events by a factor of 1.6. These deviations show regional variation: the IDE's at the Hokkaido and the Kanto regions excite larger PGA than those at the Tohoku region. It is concluded that the focal depth is a key parameter to control the amplitude of PGA rather than focal mechanism and/or fault type.
