Dynamic response of the Daguangbao landslide triggered by the Wenchuan earthquake with a composite hypocenter

Abstract

To identify the correspondence between the different dynamic responses of the Daguangbao landslide and the different faulting mechanisms of the composite-hypocenter, the whole hypocenter of the Wenchuan earthquake was divided into four sub-hypocenters. On another hand, based on the location of the Dauangbao landslide, the composite-hypocenter was divided into the Initial Sub-hypocenter, the Approaching Sub-hypocenter, the Local Sub-hypocenter, the Receding sub-hypocenter and the Terminal sub-hypocenter. Subsequently, dynamic response of the landslide was modeled by using UDEC software. The results show that progressive damage and critical failure of the mega landslide are triggered by the second sub-hypocenter. Simutaneously, with respect to the second classification basis, its progressive damage is induced by the Approaching Hypocenter and the Local Hypocenter in time sequence. The Local Hypocenter triggers its critical failure. During the long-runout stage, besides the local topography, its self-gravity poses a dominant contribution to the dynamic responses of the landslide. Especially, the inertial seismic force is another key factor that triggers the ejection stage of the landslide. The following seismic forces triggered by the corresponding sub-hypocenter influence the long-runout stage slightly. The horizontal seismic force poses a dominant contribution to the progressive damage and critical failure of the mega landslide.

Keywords

• a composite hypocentre
• dip-slip faulting mechanism
• oblique-slip faulting mechanism
• strike-slip faulting mechanism
• initial sub-hypocenter
• local sub-hypocenter
• terminal sub-hypocenter