2 September 2022

Heavy rain has triggered multiple landslides in New Zealand over the last two months

Posted by Dave Petley

Heavy rain has triggered multiple landslides in New Zealand over the last two months

Parts of New Zealand have suffered unusually intense rainfall through July and August, triggering multiple landslides.  For example, in Wellington, which is a city built on steep slopes, Geonet has reported that 294 mm of rainfall fell in July alone, the highest on record, with further heavy rainfall falling in August.  As of 18 August GNS had recorded 195 landslides in July and a further 148 in August.  For example, this landslide occurred on The Terrace on 8 August, threatening the house higher up the slope:-

The 8 August 2022 landslide on The Terrace in Wellington.

The 8 August 2022 landslide on The Terrace in Wellington. Image courtesy of GNS Science/ Wellington City Council.

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Other areas have also been affected, most notably Nelson in the northern part of South Island.  Perhaps most interestingly, a significant landslide occurred in the Atawhai area of Nelson, which was captured on a video https://www.youtube.com/watch?v=p70sOgxfa_g:-

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Stuff has an article that explains the context for this landslide:-

Gary Fieldes’ holiday in “sunny Nelson” took an unexpected turn when the bank opposite the home he was staying in began to slip.  Fieldes and his wife, from Cambridge, are staying on Sunnybank Rise in Nelson’s Atawhai, house sitting for friends travelling in the United States.  When the land opposite the home began to move on Thursday afternoon just after 2pm, Fieldes grabbed his phone.  The slip, which started slowly, gained momentum, taking trees with it as it slid over a retaining wall and onto the street.

The most substantial rain occurred a few days later though.  Geonet has an article about the landslides triggered between 17 and 22 August.  Some areas received over a metre of rainfall. This image shows multiple shallow landslides triggered in the Atawhai area:-

Multiple shallow landslides in the Atawhai area of New Zealand, triggered by heavy rainfall.

Multiple shallow landslides in the Atawhai area of New Zealand, triggered by heavy rainfall. Image by GNS Science.