Abstract: In order to analyze the dynamic seismic response and topographic amplification effect of Kangding M_s6.3 and M_s5.8 earthquakes, we excavated adits at different altitudes and placed monitoring instruments on both sides of the slope at Mogangling segment of Dadu River. The monitoring data reveals that 1) the peak ground accelerations (PGA) in both horizontal and vertical directions at 1^# monitoring site are the biggest. In M_s6.3 earthquake, the PGA in horizontal and vertical direction is respectively 16.5-22.2 cm/s² and 8.9 cm/s², and in M_s5.8 earthquake the horizontal and vertical PGA is 9.9-11.8 cm/s² and 4.1 cm/s², respectively; 2) with the horizontal and vertical PGA at 2^# monitoring site as reference, the horizontal and vertical PGA amplification factors of 1^# monitoring site are the biggest, reaching 5.4 and 4.2 respectively in M_s6.3 earthquake and 3.7 and 2.2 respectively in M_s5.8 earthquake; 3) difference of predominant period of each monitoring site is not big in the same period frequency from Fourier spectrum in both earthquakes; 4) the acceleration response spectrum at each monitoring site shows that the horizontal and vertical amplitudes of 1^# monitoring site (which is in the highest altitude) are the biggest. For the same site, horizontal and vertical amplitudes of M_s6.3 earthquake are both larger than those of M_s5.8 earthquake. Studies suggest that under strong earthquake, seismic wave is amplified selectively in different parts of slope at different elevations, and topographic amplification effect of ground motion is bigger at higher altitude.

Key words: Kangding Earthquake, Mogangling, dynamic response of slope under earthquake, amplification coefficient of PGA, acceleration response spectrum