19 January 2010

Landslides from the Haiti earthquake – not many!

Posted by Dave Petley

NASA has today released an image, partly obscured by cloud, of the upland area to the south of Port-au-Prince. This is the area that received the highest levels of shaking and, given the terrain, was most likely to have suffered slides. The image is available here:


and a comparison with an image taken in 2008 is here:


Note that this area suffered heavy rainfall in the 2008 hurricane season.

This is a close-up of a part of the area, close to, and just to the south of, the fault:

Clearly there are landslides visible, but the number is comparatively low and for the most part the slides are small. Note that NASA has, understandably, marked them as being “potential landslides”. The terminology used here might be interpreted as indicating the possible existance of a landslide, rather than an area in which a future landslide may occur. The big unknown is whether there is a higher likelihood of sliding in the next heavy rainfall event. This can only be addressed with fieldwork, but I am not sure who will do this (maybe the USGS?). It is also essential that refugee camps are located away from potential mudflow and debris flow tracks (the worse structure to be in during a debris flow is a tent – they offer no protection, but the ropes and pegs make rapid escape difficult). I hope that this will be taken into account as the situation stabilises.

Finally, servir.net has produced an erosion potential map for the earthquake-affected area, which is available here: