Journal of Natural Disaster Science

ATTENTION CHARACTERISTICS OF PEAK AMPLITUDE IN THE HYOGOKEN-NAMBU EARTHQUAKE

Kojiro IRIKURA
Professor, Disaster Prevention Research Institute, Kyoto University
and
Yoshimitsu FUKUSHIMA
Researcher, Izumi Research Institute, Shimizu Corporation

(Received 27 February, 1995 and in revised form 16 June, 1995)

Abstract

The peak horizontal acceleration and velocity of observed records from the 1995 Hyogoken-nambu earthquake are compared with those predicted from empirical attenuation relations that were found applicable to the near-distance area. The observed peak values match well the existing empirical attenuation relations, although unpredictable severe damages occured due to strong ground motions in Kobe and adjacent cities close to the faulting zones. The observed peak vertical accelerations are about half the peak horizontal ones at less than 100 cm/s/s, as in the empirical relations, but they tend to be more than half at more than 100 cm/s/s. This suggests that the horizontal motions were more markedly affected by the horizontal non-linear behavior of the soils in the surface layers during strong horizontal motion than during vertical motions.

Key words

attenuation relation, peak horizontal acceleration, peak vertical acceleration, the 1995 Hyogoken-nambu earthquake