February 07, 2023
Slip risk known for hilly Auckland
An environmental scientist says the high number of slips in the Auckland area during the recent storms should not have been unexpected.
University of Auckland Associate Professor Martin Brooks says the region has hilly volcanic terrain, older rock and clay-rich soils on slopes which can fail when they become saturated with rain.
Auckland can expect about 1300 mls of rain in a normal year, and the soils are likely to slide.
“Winter 2008 we had quite a lot of landslides then and in fact GNS wrote a report saying much of Auckland is at moderate to high risk for landslides after that event and then 2017 we had the Tasman Tempest, one in 150-year storm in Hunua, and a lot of the eastern suburbs, Maraetai was badly hit then so we are prone to landslides,” he says.
Dr Brooks says Auckland has allowed people to build in high risk areas such as along cliff edges, and as a consequence there’s now a multi-million dollar question about who is going to foot the bill to fix the damage or relocate those at risk.