P-wave Amplification by Near-Surface Deposits at Different Excitation Levels

Possible nonlinearity in the response of sedimentary layers to incident P waves is studied using the strong-motion data f rom a vertical array in Taiwan at the site where a significant nonlinear response to S waves had been found. Soil transfer functions are analyzed at different excitation levels with a maximum vertical acceleration at surface reaching 0 . 1 g, corresponding to the compressional strain of 7 × 10 -5. Weak-mot ion and strong-motion transfer functions are compared. No effects of reduced amplification or change in resonance frequencies with increasing strain level were observed, suggesting that the response remained linear in the range of strain under consideration.