A method for predicting co-seismic displacements of slopes for landslide hazard zonation

Abstract

Landslide hazard zonation based on co-seismic slope displacements has been applied in many regions. As there are a large number of slopes to be analyzed and it is impossible to obtain actual acceleration time histories for each of these slopes, the co-seismic displacements are often estimated by some simple empirical formulas, which are derived through regression analysis based on a certain set of acceleration time histories and can only be validly applied to regions similar to where the time history data were recorded. In this paper, treating the ground motion as a random process, a formula for calculating the expected value of Newmark displacement with the acceleration amplitude spectrum as input is derived. Since the formula is theoretically equivalent to the double integration procedure in a rigorous Newmark analysis, which has also been verified by careful comparisons of the calculated results, it can be applied for different regions. By combining the formula with ground motion simulations, a new method for estimating co-seismic slope displacements is proposed. The application of the method in the seriously struck area by Wenchuan earthquake shows that it is an effective tool for predicting co-seismic slope displacements as the predicted landslide distribution by using its estimated results agrees reasonably with the actual observations.