Growth and seismic hazard of the Montserrat anticline in the North Canterbury fold and thrust belt, South Island, New Zealand

Fault-related fold growth is a seismic hazard in North Canterbury, New Zealand. The North Canterbury fold and thrust belt (NCFTB) is located at the southern end of the Hikurangi subduction zone, South Island, New Zealand where the Pacific plate transitions from subduction to transpression along the Alpine fault. Transpression causes shortening beneath the South Island, resulting in basement thrusts generating folds such as the Montserrat anticline. We focus on fault geometry and seismic hazard associated with this structure, exposed along the coast where Pleistocene marine terraces on the backlimb record tectonic uplift. To constrain parameters associated with evolution of this fault-related fold, we model the fold using several trishear kinematic models. A listric fault is most compatible with field and regional geophysical studies. Ages of marine terraces and inner edge elevations constrain uplift rate due to slip on the Glendhu fault to 1.1 ± 0.1 m(ka)−1. An ∼800 year recurrence interval is calculated for the Glendhu fault. Listric fault geometry lengthens the recurrence interval relative to other fault geometry models. An accurate understanding of subsurface fault geometry and kinematics is important for estimating seismic hazard in regions of fault-related folding such as the NCFTB because it affects recurrence interval estimations.