GROUND MOTION CHARACTERISTICS WITH REFERENCE TO DAMAGE BY THE PHILIPPINE EARTHQUAKE OF JULY ۱۶, ۱۹۹۰

The ۱۹۹۰ Philippine earthquake caused serious damage to human lives and properties. The cause and effect of the earthquake damage was investigated by means of microtremor measurements. Based on results of the measurements, vibration characteristics of Ambuklao Dam and the subsurface ground in Baguio City are described in detail with reference to the earthquake damage. Although damage to the dam was practically minor, big waves were reportedly induced in the reservoir. In Baguio City, amplification of ground motion was not susceptible on the hilltops or sloping ground surfaces, but many multistory reinforced concrete buildings were likely to display resonant response to the ground motion