Earthquake induced landslides

I have just received my copy of the New Zealand Society for Earthquake Engineering Bulletin volume 50, no. 2 (June 2017). It is a special issue on the 2016 Kaikoura earthquake that affected parts of both South and North Islands of New Zealand.

I live near Wellington, and the shaking at my house at 12:02am on November 14 was sufficient to wake me up. As the strong shaking continued over what seemed like a long time, it became clear that there had been a significant earthquake. This was quickly confirmed by checking the Geonet data (a government funded monitoring system).

The Bulletin is going to be a very useful reference covering all aspects of the earthquake from seismology through response and recovery activities. Of special interest to me was a paper by Dellow and 31 co-authors, titled “Landslides caused by the Mw 7.8 Kaikoura earthquake and the immediate response“.

The paper by Dellow et al. discusses the work that has been carried out to prepare an inventory of tens of thousands of landslides that were activated by the Kaikoura earthquake, and the studies carried out subsequent to initial reconnaissance. The landslides occurred in areas with steep topography, extending over an area more than 10,000 sq km.

The majority of landslides occurred in two geotechnically distinct materials; a geological map would have been a useful addition to the paper. One of the geological units “Torlesse ‘basement’ rocks (sandstones and argillites)” also underlies the Wellington region.

It is important that learnings from this earthquake are able to be applied to slopes in Wellington, as urban development has extended over and below what seem to be similar slopes to those that failed during the Kaikoura earthquake.

We would like to encourage and assist any group that is interested in carrying out research into well documented slope failures that were activated by the Kaikoura earthquake, and slopes that performed well. We can contribute our 3D slope stability program (TSLOPE) that is able to use the detailed data from LiDAR pre and post failure to accurately model the slope. As an example of how we use TSLOPE to learn from slope failures, visit our web site Case History pages, and refer to the Belmont Quarry example. The quarry is located in the Wellington region, and mines Torlesse ‘basement’ rocks, one of the two geotechnically distinct materials discussed in the paper by Dellow et al.

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