Relationships between ground motion parameters and landslides induced by Wenchuan earthquake

The MS8.0 Wenchuan earthquake induced severe landslide hazards.For the first time in China,large numbers of strong motion records were obtained during the Wenchuan earthquake,providing the opportunity to study the relationships between ground-motion parameters and the earthquake-induced landslides.Nearly 40 groups of records from the main shock distributed along the Longmenshan fault lines were used to carry out this study.The results appropriate to the Longmenshan area are as follows:1 The threshold of the peak ground acceleration(PGA) is about 0.7 m/s2.When the PGA reaches 2 m/s2,the landslide hazards are very serious;2 The threshold of the peak ground velocity(PGV) is about 0.5 m/s.When the PGV reaches 1.5 m/s,severe landslide hazards will be induced;3 The threshold for the Arias intensity(Ia) is about 0.2 m/s.When the Ia in one horizontal direction reaches 2 m/s,landslide hazards will be very serious;4 As for the relevance order of the parameters to earthquake-induced landslides,Ia is the leading parameter,followed by PGV,and finally PGA.The results presented in this paper are consistent with the results from other studies,indicating that the threshold of the ground motion parameters for strong earthquakes is of the same order of magnitude as that of moderate earthquakes.Landslide density of local sites fluctuated with the increase of ground motion intensity if the thresholds were reached.When the upper limits are exceeded,the landslide density remains at a certain level with relatively little variation.