[S07-P] Poster

[S07-P-14] Characteristics of Seismic Response of the Taipei Basin

^○Kou-Cheng Chen, Jeen-Hwa Wang (Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan)

The Taipei Metropolitan area is located on a triangular-shaped alluvium basin filled with the Quaternary unconsolidated sediments overlying the Tertiary basement. The sediments thicken northwestward from a thin basin margin in the southeast to about 700 m in the northwest corner of the basin. In order to investigate the characteristics of seismic response of the Taipei basin, the 5%-damped response spectral accelerations with periods, T, of 0.2 and 1 sec are calculated from the accelerograms recorded at the stations on the Taipei basin. The horizontal response spectra are calculated from the geometric mean of the spectral amplitudes of two horizontal components. Obviously, the spectral accelerations are higher in the Taipei basin than in the surrounding area due to the amplification of waves in the sedimentary basin. For the three Hualien offshore earthquakes, the maximum horizontal spectral accelerations are distributed near the eastern edge of the basin at T=0.2 sec and near the eastern and northern edges of the basin at T=1.0 sec. For two earthquakes occurred in central Taiwan, the maximum horizontal spectral accelerations at T=1.0 sec are distributed mainly near the eastern and western edges of the basin.