3 June 2008
There is a very good film (in Chinese) of the Tangjiashan landslide. It is available at:
The first 6 minutes or so are worth a look. Early in the video they fly a helicopter over Beichuan, which shows the damage caused by landslides there. They then land the helicopter on the landslide mass and the reporter goes into the channel. It appears to be about 5 m wide at the base with steep walls. The material is silt by the look of it, with just a few clasts.
The Chinese goivernment has done a fine job to build a channel at all, but this is not going to be able to contain the flow.