Thanks to Lynn Highland at the USGS for drawing my attention to this video of a debris flow in Costa Rica:

http://www.youtube.com/watch?v=-HK8wW4SkWY

This is a slightly strange event. It occurred on the Sarapiqui River in Costa Rica after the 16th January 2009 Cinchona earthquake. It is not all clear why the earthquake should have triggered such a debris flow given that there was no rainfall, but a suggestion is that there may have been mobilisation of shallow groundwater. Another possibility is the creation and then collapse of a barrier lake.

The same event also appears to have been captured in this video:

If anyone has any more information then I would be very interested in hearing about this event.

In Hong Kong last month I saw a video taken of a collapsing hillside during the Wenchuan earthquake. This appears to have been shot in the Wolong Panda Reserve area. The quality is poor, but the footage of the collapsing slope is dramatic: