Landslides Triggered by the 14 November 2016 Mw 7.8 Kaikōura Earthquake, New Zealand

Abstract

The MW7.8 14 November 2016 Kaikoura earthquake generated more than 10000 landslides over a total area of about 10000 km2, with the majority concentrated in a smaller area of about 3600 km2. The largest landslide triggered by the earthquake had an approximate volume of 20 (±2) M m3, with a runout distance of about 2.7 km, forming a dam on the Hapuku River. In this paper, we present version 1.0 of the landslide inventory we have created for this event. We use the inventory presented in this paper to identify and discuss some of the controls on the spatial distribution of landslides triggered by the Kaikoura earthquake. Our main findings are: 1) the number of medium to large landslides (source area 10000 m2) triggered by the Kaikoura earthquake is smaller than for similar sized landslides triggered by similar magnitude earthquakes in New Zealand; 2) seven of the largest eight landslides (from 5 to 20 x 106 m3) occurred on faults that ruptured to the surface during the earthquake; 3) the average landslide density within 200 m of a mapped surface fault rupture is three times that at a distance of 2500 m or more from a mapped surface fault rupture ; 4) the "distance to fault" predictor variable, when used as a proxy for ground-motion intensity, and when combined with slope angle, geology and elevation variables, has more power in predicting landslide probability than the PGA or PGV variables typically adopted for modelling; and 5) for the same slope angles, the coastal slopes have landslide point densities that are an order of magnitude greater than those in similar materials on the inland slopes, but their source areas are significantly smaller.

Tributary‐junction fans as buffers in the sediment cascade: a multi‐decadal study

“…For example, where region-wide landsliding has occurred (such as Kaikōura, New Zealand, after the 2016 earthquake (Massey et al, 2018)), a similar analysis could identify tributary-junction fans where sediment is most (or least) likely to be stored. For example, where region-wide landsliding has occurred (such as Kaikōura, New Zealand, after the 2016 earthquake (Massey et al, 2018)), a similar analysis could identify tributary-junction fans where sediment is most (or least) likely to be stored.…”

Earthquake‐Induced Chains of Geologic Hazards: Patterns, Mechanisms, and Impacts

“…Clustering of EQTLs near ridge crests and secondary clusters in colluvial slope toes and above inner gorges was observed by Meunier et al () for the 1994 Northridge, 1999 Chi‐Chi, and 1993 Finisterre earthquakes. Topography‐controlled landslide hot spots also were identified in the patterns of landslides triggered by the 2001 El Salvador, 2008 Wenchuan, 2010 Haiti, 2010–2011 Canterbury, 2013 Lushan, and 2017 Jiuzhaigou earthquakes (Evans & Bent, ; Fan, Scaringi, et al, ; Hough et al, ; Li et al, ; Massey et al, ; Xu, Xu, Shen, et al, ; Xu, Xu, Shyu, Gao, et al, ). The markedly uneven distribution of EQTLs along slopes differs from that of rainfall‐triggered landslides, which tend to be more evenly distributed along different parts of slopes (Meunier et al, ) because they are primarily controlled by the patterns of precipitation and by the coupling between slope geometry and the hydromechanical properties of the slope material.…”

Characteristics of landslides in forests and grasslands triggered by the 2016 Kumamoto earthquake

“…More recently, Massey et al . () demonstrated that the average density of landslides triggered by the 2016 Kaikōura earthquake (Mw = 7.8) in New Zealand was three times higher within 200 m of the detected surface fault rupture compared to outside of this zone. Khazai and Sitar () noted that 90% of landslides caused by the 1999 Chi‐Chi earthquake (Mw = 7.6) occurred on hillslopes steeper than 45°.…”