Journal of Natural Disaster Science

Analyses of Data Recorded by the Network System for Observations of Earthquake Responses in the Kyoto Area

Ikuo CHO, Yoko MURAMATSU, Reiji KOBAYASHI, Ichiro NAKANISHI, Kazuo OIKE,
Department of Geophysics, Kyoto University,
Yoshiyuki SUZUKI
Disaster Prevention Research Institute, Kyoto University
and
Teizo FUJIWARA
School of Environmental Science, University of Shiga Prefecture

(Received 30 April, 1998 and revised form 27 January, 1999)

Abstract

Since March 1996, a new array system, called the Network System for Observations of Earthquake Responses in the Kyoto Area (NSOERKA) is being used to record strong ground motions in Kyoto City. Its purpose is to investigate local site and building responses to the earthquakes in Kyoto and surrounding areas in order to provide a seismological data base for preventing urban disasters. Waveform data from NSOERKA for an earthquake which occurred beneath Kyoto on July 18, 1996 (JST) (MJMA3.6, magnitude determined by the Japan Meteorological Agency) was analyzed. After locating the earthquake, we determined the source mechanism using linear moment tensor inversion of the waveform data. The theoretical seismograms obtained explain the observed SH waves. We then compared the seismic intensities calculated from the observed and theoretical seismograms, because seismic intensity is a conventional, useful tool for estimating the local size of an earthquake disaster. The theoretical seismic intensity was systematically smaller than the observed value, probably because we ignored the sedimentary layers in the earth structure used to calculate the theoretical seismograms.

Key words

earthquake disaster mitigation, earthquakes in Kyoto, prediction of seismic intensity, strong-motion network, moment tensor inversion