A landslide in West Auckland's Karekare during 2023's Cyclone Gabrielle. Photo: RNZ / Leonard Powell
The first detailed mapping in almost three decades of Auckland areas prone to landslides will go on LIM reports later this year, Auckland Council says.
The council has done a study of the entire region, giving new information and putting an end to anecdotal information having to be used.
"So we've mapped the entire Auckland region all the way across the whole region, all the way from upper Warkworth all the way down to the bottom of Franklin.
"And so we've covered everywhere. If you live in Auckland, these maps apply to you," Auckland Council chief engineer Ross Roberts told Nine to Noon.
The mapping will be used by the likes of planners, developers, engineers and homeowners.
Roberts said it will also play a key part in the council stopping developments in areas susceptible to landslides.
He noted the information shows where there is a potential for a problem, rather than a definite problem.
"These give an indication of where people might want to investigate further, they are not saying that there is going to be a landslide here.
"We're not in a position yet with the science available to be able to forecast landslides. So it's giving people an indication. So they might want to dig further. They might need to get more information," Roberts said.
What the mapping shows
The biggest problem areas were not surprising, Roberts said and they were in areas with big hills.
"So you're looking at areas of the Hunua Ranges and you get up into parts of Rodney sort of north of Ōrewa, you see some of the bigger land sites.
Auckland's Hunua Ranges. (File photo) Photo: RNZ/ Olivia Allison
"Especially in some of the geology that's more vulnerable," Roberts told Nine to Noon.
He said the northern half of Auckland was "particularly vulnerable" to ongoing slow movements that could pose challenges.
The mapping also meant there was now consistency with information from across the Auckland region, he said.
"We're not just relying on the anecdotal evidence looking at this and saying this looks like a problem area.
"Now we've got a map that say, OK, now we could compare one place to another and say 'actually, we know that this is a higher susceptibility, we can start to do something about it'."
Roberts said including the new mapping on LIM reports was "the right thing to do".
"It's really important that people buying homes understand whether they should be looking harder to understand the problem.
"But also we have a legal obligation to, if we have any information about a hazard, we're legally advised to put that on them.
"They can look at it and say 'OK, there's a potential problem here, I'll get specialist advice, I'll get an expert to come and give me some information to make sure that in future my house is going to be safe'."
Sign up for Ngā Pitopito Kōrero, a daily newsletter curated by our editors and delivered straight to your inbox every weekday.
