Discussion on the Hazard Distance of Landslide-Debris Flow Triggered By Wenchuan Earthquake

To clarify the movement characteristics and predict the distance of landslide triggered by Wenchuan earthquake,this paper,using remote sensing image interpretation and field investigation data,discusses the correlation between the L and H to give the empirical formula and determines the key influence factors of earthquake landslides.The analysis of the difference between different types of landslides shows that:If H is known,total displacement can be preliminarily forecast by using the empirical formula L=aH+b or L=aH^b.It is applicable to treat 0.45 as the standard to measure high-speed and long runout avalanches in Wenchuan.The volume and the rupture area of the source region was positively correlated with the L,while H/L was negatively correlated with them.As earthquake landslide with ridgeline parallel to the rupture zone and perpendicular to the wave propagation direction is easy to occur,collapse-type landslide is much easier with the height range of 10 to 100m,with high-speed and long runout avalanches greater than 200 m.In the source region,the slope is generally distributed between 25ånd 51°.The slope of sliding bed changes between 0ånd 58°,while the slope of sliding bed of the high-speed and long runout avalanches is distribute in the range of 8°to 20°.The differences of the maximum movement distance is the result of the combined effects,such as distance effect,energy transfer and the baffle effect,rolling lubrication and air cushion effect,volume and rupture area effect,particle size distribution and particle flow effect,geological factors,the topography factor,etc.