KEY POINTS:
Homeowners counting the cost of last month's storms are facing even more bad news.
Engineering experts estimate thousands of properties are at risk from landslips, and the Insurance Council says flood-prone homes may eventually be refused cover.
The warnings follow the storms that hammered New Zealand on July 26 and 30, killing three people. The Earthquake Commission has received more than 500 claims for damage, worth an estimated $5.2 million.
Commission insurance manager Lance Dixon said Wellington was hardest hit, with 140 claims, followed by Auckland with 125.
The Bay of Plenty and Coromandel each had 35 claims; Hawke's Bay, the Far North and Christchurch had 30 each ; and the Waikato and Dunedin 20.
Insurance Council insurance manager John Lucas said the final bill could reach $50m, but he warned homeowners in flood-prone areas might not get insurance in the future.
"This is when a property has been flooded year-on-year," he said.
Slips were responsible for many claims, and Doug Johnson, a geotechnical group manager for engineering consultants Tonkin and Taylor, said many homes were still under threat.
"The whole country is at risk of landslides - people are always building on hilly slopes and terrains."
He said the most slip-prone areas were the East Cape, Central North Island, Northland, Coromandel and the Southern Alps. In Auckland, which has hills with weak underlying rocks and soil, parts of Manukau, the North Shore and the Waitakeres were most at risk.
The increase in slips - about 300 were reported in Wellington last month - was caused by a build-up of water in the soil, making the ground more unstable.
Institute of Geological and Nuclear Science engineering geologist Grant Dallow said New Zealand had several thousand slips every year. "Every time there's a decent quake or a decent rainstorm, or they just happen out of the blue."
In the past 12 years, 10 people had died in slips, half of them in national parks or reserves.
Dallow said there was no coherent national approach to monitoring slip-prone areas, but the institute was "moving towards this".
The Ministry of the Environment funded landslide guidelines but planners and councils interpreted them in different ways.
