Characteristics of Ground Motions and Building Responses Recorded during the 2001 Geiyo Earthquake
Seismic observation was carried out in the campus of the Hiroshima institute of technology. The vibration of the building and the ground motion were recorded during the 2001 Geiyo earthquake. The comparisons of seismograms obtained by the three accelerometers are performed by the spectrum analysis. A summary of the recorded results is presented as follows: 1) The horizontal component is excited by the third mode of the building and the vertical component becomes large at the natural frequency due to the vibration of the roof floor-girder. The horizontally and vertically natural frequency in the Geiyo earthquake becomes 0.7~0.8 times and 0.8~0.9 times that in the past small earthquakes, respectively. 2) As the characteristics of ground motions due to a basement, the horizontal component is shown as the surface deposit hardening. From comparison with the results of the past small earthquakes, the surface deposit is softening 1/1.25 times due to the Geiyo earthquake.
Departmental Bulletin Paper