Journal of Natural Disaster Science

SYNTHESIS OF STRONG EARTHQUAKE MOTIONS OVER A WIDE FREQUENCY RANGE*

Ikuei MURAMATU
Professor, Faculty of Education, Gifu University
and
Kojiro IRIKURA
Associate Professor, Disaster Prevention Research Institute, Kyoto University

(Received 28 October, 1982 and in revised form 20 December, 1982)

Abstract

The Izu-Hanto-Toho-Oki Earthquake of 1980 (magnitude 6.7) and its foreshocks and aftershocks were observed at three stations near the source region using velocity-type strong-motion seismographs having a wide dynamic range (100 kines to 1 mkines) over a wide frequency range (0.02 Hz to 20 Hz). Applying a semi-empirical method we formulated a technique to synthesize the strong ground motions for the mainshock, and we were able to reproduce the mainshock seismograms at all stations for a wide frequency range. In this synthesis we used the seismograms of aftershocks or foreshocks as Green functions for computing the mainshock motions and the scaling law among the source parameters.

Key words

synthesis of strong motions, Izu-Hanto-Toho-Oki Earthquake of 1980, source spectrum of ω-2 model, velocity-type strong-motion seismograph