Landslides triggered by the MW7.8 14 November 2016 Kaikōura earthquake: an update

In this study, we use version 2.0 of the digital inventory of landslides triggered by the MW 7.8 Kaikōura, New Zealand, earthquake of 14 November 2016 to revaluate some of the controls on their spatial distribution. Version 2.0 contains 29,557 hand-digitised landslides, whilst version 1.0 included only 10,195 mainly larger (> 10,000 m2) landslides. The main results from the re-analysis using version 2.0 of the inventory are the following: (1) the landslide frequency and density results indicate that the power laws fitted to version 1.0 and version 2.0 landslide inventories are similar; (2) the landslide densities decrease with increasing distance from the nearest fault that ruptured to the surface during the earthquake; (3) the larger landslides in the inventory occur on slopes with higher local slope relief; and (4) the results from logistic regression modelling using the version 2.0 inventory show that (a) the geological materials have a larger relative contribution to the fit of the overall model, when compared with the previous model based on the version 1.0 inventory, and (b) the “distance to fault” predictor variable continues to have more statistical power in predicting landslide probability than the modelled peak ground acceleration or peak ground velocity. These results suggest that future research on the Kaikōura earthquake landslide distribution—and the landslide distributions associated with other similar large earthquakes—might be directed towards investigating the interaction between surface fault rupture, fault damage-zone properties, earthquake-induced ground shaking, and the initiation of slope failures.