Abstract
Under complex geologic conditions, the Wenchuan Earthquake, with its high magnitude and unusually long duration of shock, has triggered massive landslides. Based on the field work of investigation and referring to the literature concerned, the present study concludes that the Zhengjiashan landslide is of type I mechanical failure. The Zhengjiashan landslide is triggered by the forceful dynamic shock of the “5.12” Wenchuan Earthquake. Over 2 million cubes slid at high speed caused by shattered and tension rock mass shearing the leading edge of the locking-up area, and rushed the school and farmhouses in the leading-edge body, causing 33 deaths including 12 students, 2 teachers and 19 farmers. It was, then, blocked by the opposite mountain mass when entering into the Ziku River and formed a barrier lake after the concussion and accumulation. The landslip is a typical earthquake-triggered tension-shearing landslide, characterized by high-speed slide-falling with strong dynamic force that can grow into smooth slide bed near the causative fault and bedding fault.
