ABSTRACT
Fill slopes present a higher risk of failure during large earthquakes than cutting slopes do. The degree of damage depends both on seismic intensity and the fill slope water contents at the time of the earthquake. The fill slope where the observation system was set up is located in a created housing area developed on hilly ground of northeastern Sendai City in the 1970s. The amount of water included in the fill soil material changes from time to time mainly because of rainfall. When the fill slope collapsed by the rainfall of typhoon in July, 2002, the maximum soil water index was about 170 mm and the maximum hourly rainfall was 32.5 mm/h. The seismic observation system array installed in the fill slope recorded four earthquakes during December 2006-April 2007 and verified seismic amplification caused by the fill and the difference of the primary predominant frequency attributable to the fill thickness.
