2 December 2016
The North Canterbury Landslide Dams website
The aftermath of the Kaikoura Earthquake last month is increasingly becoming focused on the impact of the very large number (possibly over 80,000) landslides generated by the seismic event. In common with other major earthquakes in mountainous areas, the immediate concern is focused upon valley blocking landslides – also known as landslide dams or quake lakes. A small proportion of these can collapse rapidly, allowing the generation of a major flood / debris flow that can be devastating downstream. Unsurprisingly, the Kaikoura earthquake has generated a large number of landslide dams, although none pose an immediate high level of risk. The potentially more dangerous dams are being monitored by Environment Canterbury and GNS Science. My old friend Sally Dellow is providing much of the technical coordination; I know of no-one better to play this vital role.
Canterbury Maps have now put together a wonderful web resource to provide information about the landslide dams – North Canterbury Landslide Dams – this is exemplary risk communication. The site provides an interactive map of the location of the landslide dams, with the key dams being highlighted in red:
The site provides a table of information about the status of the key landslide dams as well, which will be updated as each reconnaissance flight is completed. For example, one of the dams, Linton 340, is described as follows:
Dam remains intact, but face starting to erode. High chance of failure. Could affect some areas around Inland Road.
This is the image of the dam that the site has provided:
These landslide dams are being managed in a very measured way. Unfortunately they will present a substantial challenge for some time to come.