Post-earthquake monitoring of landslides along the Southern Kaikōura Transport Corridor, New Zealand

Abstract

The magnitude (Mw) 7.8 earthquake that struck North Canterbury on New Zealand’s South Island on the evening of 14 November 2016 caused widespread damage to infrastructure, in particular to road and rail within the South Kaikōura Transport Corridor (SKTC). This is the main transport corridor along the east coast of the South Island, and the coseismic landslides covered and destroyed parts of the State Highway 1 (SH1) road, as well as the railway lines. Post-earthquake aftershocks and significant rainfall events (e.g. Cyclones Debbie, Cook and Gita), further mobilised the de-stabilised greywacke rock mass and paleo-landslide debris that mantled the slopes. Indeed, the SKTC was affected by > 80 separate landslides that have impacted either the rail corridor, the road corridor, or both. A number of different landslide mechanisms occurred, including shallow translation slides of existing paleo-landslide debris and rotational slumping, as well as rock mass failure via wedge, planar or toppling. Here, we report on monitoring of three case study landslides, using multi-temporal analyses of digital elevation data (from LiDAR, TLS and UAV surveys), real-time extensometer and land deformation monitoring using GPS receivers, as well as survey prisms. These datasets provided important monitoring of near-surface movement, important for risk management along the transport corridor during the reinstatement works.