27 April 2013

Landslide hazards in the aftermath of the Lushan earthquake in Sichuan

Posted by Dave Petley

A number of Chinese media outlets have articles about the threats posed by landslides in the aftermath of the 20th May 2013 Lushan earthquake in Sichuan Province.  It is clear from the imagery (such as the image below) that landslides have represented a very significant component of the costs of this earthquake, although at present it is not clear just how many of the deaths were caused by mass movements.  The next major threat is the upcoming rainy season – just weeks away – which will inevitably cause a combination of further first time failures and debris flows of released materials. Ya’an, the County in which Lushan sits, is nicknamed “the city of rain”.



In terms of costs, Xinhua are reporting 196 fatalities, 21 people missing and 13,484 injured.  The level of damage is very high – 86,300 buildings have collapsed in the quake and about 430,000 houses have been seriously damaged.

Eastday China reports that a team of 400 geohazards specialists are working to identify hazards, and are developing warning and evacuation plans.  Emphasis is rightly being placed on the emergency camps, which are often extremely vulnerable.  Meanwhile CRI English has an interesting report about landslides that have been deposited into river channels.  Whilst these are not valley blocking at present, the loss of flow capacity may allow a lake to develop during the high flow period.  Clearly this is unacceptably dangerous.  The army are undertaking controlled blasting to clear the blockage.