Landslides from the Kaikoura Earthquake part 2: the Hapuku landslide

The longest runout slide triggered by the Kaikoura Earthquake was the Hapuku landslide, which occurred high up in the catchmnet of the Hapuku River. This landslide is at -42.237, 173.664 if you want to take a look on Google Earth. This landslide is a long (2.7 km) rock avalanche with a volume of about 10-14 million cubic metres. The elevation change from the crown (which is at the ridge top) to the toe is about 1,900 metres. To get a full appreciation of this landslide the Google Earth imagery is helpful:-

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As the image shows, the landslide crown is at the ridge line (which is common for earthquake triggered landslides), whilst the debris at the toe has blocked the valley.

This is a helicopter image of the upper portion of the landslide:

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This suggests that the failure event in the upper portion of the landslide was complex, and that there is still some debris on the slope. The image below shows the track of the landslide to the toe:-

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Note the small remaining lake caused by the blockage of the channel (the breach is also visible). The landslide has left a large amount of bare rock. This image shows the landslide debris:-

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The landslide dam has breached – this image shows the breach channel clearly:

As with many other locations, this landslide has seen some secondary failures in periods of heavy rainfall since the Kaikoura earthquake:

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As with the Seaward landslide, one of the fault ruptures runs through the scar of the this landslide. It is therefore unsurprising that there are many other landslides triggered by the Kaikoura earthquake in this area: