23 November 2021

Large landslides at Beach Loop near Whareongaonga in New Zealand

Posted by Dave Petley

A large landslide at Beach Loop near Whareongaonga in New Zealand

Heavy rainfall earlier this month caused extensive flooding and landsliding in the Gisborne area of New Zealand.  Three large landslides were triggered on the coast in the Beach Loop area to the south of Whareongaonga, about 30 km from Gisborne.

The Gisborne Herald has some images of the failures, including this one, which gives a sense of the scale:-

The Beach Loop landslide 30 km south of Gisborne in New Zealand.

A Beach Loop landslide 30 km south of Gisborne in New Zealand. Image from the Gisborne Herald, posted to Facebook by Liam Clayton.

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But there is an even larger one a little further along the coast:

The largest landslide at Beach Loop, 30 km south of Gisborne in New Zealand.

The largest landslide at Beach Loop, 30 km south of Gisborne in New Zealand. Image from the Gisborne Herald, posted to Facebook by Liam Clayton.

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The railway line in the images is the Wairoa to Gisborne line, which was mothballed after a storm in 2012.  There is controversy as to whether the line should reopen – Kiwirail has argued that the economic cost is too high for the value that the line brings.  I would imagine that these landslides will be a further blow to those who argue for reinstatement.  It is interesting to note that the failures appear to have rear scarps along the alignment of the railway.

Planet Labs has captured good imagery of the landslides:-

Satellite imagery of the aftermath of the landslides at Beach Loop in New Zealand.

Satellite imagery of the aftermath of the landslides at Beach Loop in New Zealand. Image copyright Planet Labs, used with permission.

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The largest failure appears to be a slump, whilst the smallest of the three (the most northerly) is more of a rapid earthflow, I think. I am unsure as to the middle one.  The alignment of the railway is also visible.

Although this is a rural area, the Gisborne Herald reports that a number of sacred sites for the indigenous population of New Zealand have also been lost.

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Reference and acknowledgement

Planet Team (2021). Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/

Thanks to loyal reader Dr Murry Cave for highlighting these events to me.