Abstract
The objective of this report is to evaluate the effect of the vibrating characteristics of the dike and the characteristics of earthquake ground motion on the difference of damage degree based on the seismic damage due to the Northern Miyagi earthquake, 2003 and the past earthquakes. The effect was made clear by use of the seismic records observed at the dike and 1 D seismic response analysis method proposed by the author. Microtremor was measured on the top of the dike to evaluate the vibration characteristics of the dike where the seismic observation has not been carried out. It is found that the intensity of earthquake ground motion at the natural frequency of a river dike-foundation soil system is one of the important factors to cause the difference of the damage degree from the earthquake.
