Earthquake- and rainfall- induced movement patterns of landslides: a Nelson case study

This study investigates the movement patterns and future behaviour of the Tāhunanui landslide in Nelson, a large, active, and populated rotational/translational landslide in Port Hills Gravel.

Using a combination of historical records, advanced remote sensing (InSAR), geotechnical monitoring, and numerical modelling, the research explores how rainfall-induced pore water pressure changes and potential earthquake shaking influence landslide reactivation.

Findings indicate that while rainfall events trigger more frequent but smaller displacements, seismic events—though rarer—could cause significantly larger movements, especially under wet conditions. Climate change is expected to increase the frequency of triggering rainfall events, raising the risk of future reactivations.

The study also developed fragility and vulnerability functions linking ground displacement to building damage and conducted regional susceptibility analyses to identify other at-risk landslides in the Nelson area.