Journal of Natural Disaster Science

ESTIMATION OF SEISMIC INTENSITY OF GROUND MOTION DURING THE 16 JULY 1990 PHILIPPINE EARTHQUAKE

Tadanobu SATO
and
Junji KIYONO
Disaster Prevention Research Institute, Kyoto University

(Received 29 April 1991 and in revised form 14 October 1992)

Abstract

No strong motion accelerographs were available for areas within 150 kilometers of the epicenter of the July 16, 1990 Philippine Earthquake. We therefore calculated the theoretical distribution of the maximum accelerations in the region near the earthquake source. A simplified analytical procedure with which to estimate the attenuation of the peak ground motion was developed that takes into account the fault extent. Peak acceleration near the fault region is expressed as a function of the fault parameters and the relative collocation between the fault and the observation site. The peak acceleration at bed rock level first was calculated, after which the damping effect of the path traveled and the amplification factor of the surface ground were introduced. To check the accuracy of the calculated maximum acceleration we surveyed fallen religious statues and rigid body-like objects, and estimated the maximum acceleration based on the aspect ratio.

Key words

Philippine Earthquake, ground motion intensity, source mechanism, survey of seismic intensity