Critical acceleration as a criterion in seismic landslide susceptibility assessment

• Critical acceleration is a good criterion to assess the stability of slopes.
• Horizontal critical acceleration is more important for steeper slopes.
• Critical acceleration and landslide maps can be referred to for determining PGA.

The 2008 Wenchuan earthquake in China triggered approximately 200,000 landslides. This study examined a detailed landslide inventory for the event. Based on Newmark's method, the correlation between critical acceleration and landslide occurrence was analyzed for the Beichuan region in Sichuan Province, where various kinds of geohazards occurred due to the earthquake. The results indicate that critical acceleration is a good and reliable criterion to assess slope stability, and that slope gradient and material component are important factors influencing landslide occurrences. It was found that external forces behave differently in different directions. Critical acceleration in horizontal direction is more important for assessing the stability of steeper slopes. This knowledge will help in the understanding of the mechanism of earthquake-triggered landslides and facilitate the combined use of critical acceleration and landslide distribution maps for determining peak ground acceleration in a region without abundant seismic instrument records.