21 September 2017
Landslides from the Kaikoura earthquake part 5 – other valley-blocking slips
In addition to the large valley-blocking slips that I featured in my earlier posts in this series, the Kaikoura Earthquake triggered many other valley-blocking landslides. Most of these were of a medium size, and breached soon after the earthquake without causing any major issues. This is a very spectacular example:-
This is quite a spectacular example of a rockslide on a planar surface that has destroyed a ridge. It clearly impeded the channel on the right of the image, and blocked the main drainage line. A small lake is visible. However, from above the head scarp it is clear that the landslide dam is not causing major issues:-
Further the south there are some reasonably large slumps that also blocked the valley:
Again the lakes created by the blockages are very clear, but they are neither large nor particularly troubling. Of course the impact on the farmers who owned these areas of land is large though.
In the higher areas there are some classic rockslides that have impeded the river. This very complex example had quite a large runout:
This appears to be a planar rockslide. The additional slide on the ridgeline, in a weathered material, is an interesting juxtaposition with the main slide. Given the location of the deposit, it seems likely that this happened after the main rockslide. The remains of the lake are visible. In this case there was significant incision through the fine-grained dam at the point of the breach.
Finally, some of the rockslides are actually quite simple:
This landslide briefly blocked the Clarence River, but has now comprehensively breached.
Landslides from the Kaikoura Earthquake
The earlier posts in this series are as follows:
- Landslides from the Kaikoura earthquake part 1: the Seafront landslide
- Landslides from the Kaikoura Earthquake part 2: the Hapuku landslide
- Landslides from the Kaikoura Earthquake part 3: the Leader 220 landslide
- Landslides from the Kaikoura Earthquake Part 4: partially failed slopes