Analysis on the hill topography effect based on the strong ground motion records of Wenchuan M_S8.0 earthquake

It is important for the large-scale engineering seismic fortification in the mountain area to analyze the hill topography effect of the strong ground motion based on the earthquake records. In 2008 Wenchuan M_S8.0 earthquake， a lot of strong ground motion data were recorded by fixed and mobile observation arrays. By analyzing the root-mean-square (RMS) acceleration， this paper discusses 90% duration and spectrum characteristics， the hill topography effect characteristics and its influencing factors. As to the Xishan park topography array in Zigong city， with the altitude increasing， the RMS acceleration becomes larger， however， the 90% duration does not change obviously; the shape of the Fourier spectra is similar except the amplitude in the frequency bandwidth 2.0—5.0 Hz is amplified to some extent; the ground motion energy is amplified differently in the different frequency bandwidth by the soil site around the hill and the hill topography， which makes the ground motion different; the soil site around the hill makes the ground motion duration last longer compared with the hill.