Abstract
Buildings and residential houses were severely damaged due to the ground motion at the downtown area of the Namie town, Fukushima prefecture during the 2011 off the Pacific coast of Tohoku Earthquake. Damages survey revealed that the damage ratio was not uniform even in the downtown area. In order to clarify the reason, we observed ground motions during aftershock events and microtremors in the downtown area of Namie town. The H/V spectral ratio obtained from single station observations imply that the peak frequencies uniformly distribute in the downtown area. S-wave velocity models obtained from array observations indicate low velocity in surface soil layer. Observed ground motions during the aftershocks also imply that the difference of ground motion amplification due to shallow soil layer is not significant within the downtown area.
