Seismic Responses of Three-Dimensionally Sediment-Filled Valleys due to Incident Plane Waves

It is a very important problem to study the effects of three-dimensional (3-D) topographical and geological irregularities on seismic motions. We first formulate this problem by introducing the Aki-Larner method (ALM) and check the validity and accuracy of our formulation by comparing with the results by the boundary integral equation method (BIEM). Secondly, we calculate the seismic responses of three-dimensionally sediment-filled valleys due to vertically incident plane SH-waves and compare them with those by 1-D and 2-D analyses. The 3-D responses both in the frequency and time domains show larger amplitudes and higher predominant frequencies than the 1-D and 2-D ones. We can find these amplification characteristics caused by 3-D irregularities even in thin valleys.