Wednesday 10 November 2021
Council staff are working alongside 24 households impacted by landslides following last week’s rain but for Dr Murry Cave the bigger concern is what has not yet been called in.
“Even though the rain has stopped, there can be a delayed response time,” says Council’s chief scientist. “The nature of the geology in our region is that it is made up of a lot of very soft young rocks and many houses have been built on potentially unstable hill sides.”
When the surface dries out, the wet beneath seeps into weak zones which can fail at any time. “This lag response is common the world over,” says Dr Cave.
He is urging those who live on hillsides or riverbanks to check their properties for cracks, slumps, or any unusual movement around trees. “Call it in, no matter how small it is. It is better to be safe than sorry.”
A geotechnical team from Auckland arrived on Tuesday to join the Council engineers in their continual assessment of earth movement and monitoring of the known affected properties.
Households on four of the 24 properties he and his team are working with remain evacuated. “We move them because of the risk from landslides from above them,” says Dr Cave. “We are always looking at what can be done to eliminate that risk and each situation is different. The safety of our community is of utmost importance to us, with the risk to properties the second tier.”
Last week’s storm was considered a one in 50-year event, but Dr Cave is quick to remind everyone there is a five per cent chance of an event like that one occurring in any year.
“This weather event was so unusual – ordinarily a relatively small tropical storm like this would have minimal effect on our region but it was caught by a blocking high over the South Island so had to turn around and come back to Tairāwhiti where it acted like a conveyor belt, dumping continual rain on coastal areas.”
Anyone with any concerns should contact Council on 0800 653 800, which is available 24/7.