Landslides caused by the Mw7.8 Kaikōura earthquake and the immediate response

• DOI: 10.5459/bnzsee.50.2.106-116
• Publication Date: 2019-07-21T21:41:09Z
• Authors: Sally Dellow; Chris Massey; Simon Cox; Garth Archibald; John Begg; Zane Bruce; Jon Carey; Jonathan Davidson; Fernando Della Pa...; Phil Glassey; Matt Hill; Katie Jones; Barbara Lyndsell; Biljana Lukovic; Sam McColl; Mark Rattenbury; Stuart Read; Brenda Rosser; Corinne Singeisen; Dougal Townsend; Pilar Villamor; Marlene Villeneuve; Jonathan Godt; Randall Jibson; Kate Allstadt; Francis Rengers; Joseph Wartman; Ellen Rathje; Nick Sitar; Athanasopoulos-Ze...; John Manousakis; Michael Little
• Keywords: Rockfall; Basement; Earthquake rupture

Tens of thousands landslides were generated over 10,000 km2 North Canterbury and Marlborough as a consequence the 14 November 2016, Mw7.8 Kaikōura Earthquake. The most intense landslide damage was concentrated in 3500 around areas fault rupture. Given sparsely populated area affected by landslides, only few homes impacted there no recorded deaths due to landslides. Landslides caused major disruption with all road rail links being severed. affecting State Highway 1 (the main link South Island New Zealand) trunk railway extended from Ward way south Oaro Canterbury.
 majority occurred two geological geotechnically distinct materials reflective dominant rock types area. In Neogene sedimentary rocks (sandstones, limestones siltstones) Hurunui District, Cape Campbell Marlborough, first-time reactivated rock-slides rock-block slides type. These also tend have material strength values range 5-20 MPa. Torlesse ‘basement’ (greywacke sandstones argillite) Ranges, debris avalanches 20-50 MPa.
 A feature this earthquake is large number (more than 200) valley blocking it generated. This partly steep confined slopes widely distributed strong ground shaking. largest dam has an approximate volume 12(±2) M m3 travelled about 2.7 downslope where formed Hapuku River. long-term stability cracked dams future earthquakes rainstorms are ongoing concern central local government agencies responsible for rebuilding infrastructure. particular potential floods affect downstream assets infrastructure should some breach catastrophically.
 At least twenty-one faults ruptured surface or sea floor, these ruptures extending Emu Plain offshore Marlborough. mapped distribution reflects complexity across broad shaking elongate rupture, not clustered epicentre. triggered located either on adjacent that surface. Surface may provide plane weakness hydrological discontinuity adversely oriented be indicative location Their appears structural control. Initial results our investigations suggest predictive models relying ground-shaking estimates underestimate size occurred.