Uplift and fault slip during the 2016 Kaikōura Earthquake and Late Quaternary, Kaikōura Peninsula, New Zealand

Abstract

ABSTRACT The Kaikōura Earthquake uplifted Kaikōura Peninsula by ≤∼1 m. Uplift in 2016 mainly resulted from slip on an offshore thrust fault (OSTF), modelled to splay from the plate-interface, and was further influenced by slip on two newly identified faults (Armers Beach Fault, ABF; Te Taumanu Fault, TTF) mapped onshore from differential lidar (D-lidar). Forward dislocation modelling indicates that 2016 peninsula uplift can be reproduced by mean slip of ∼2.3 m on the OSTF and 0.25–0.5 m on the ABF and TTF. The variable co-seismic uplift recorded during the 2016 earthquake differs from the near-uniform (1.2 ± 0.2°) northwest tilting of MIS5c (96 ± 5 ka) and MIS5e (123 ± 5 ka) marine terraces; these ages are constrained by Optically Stimulated Luminescence (OSL) dating and correlation to sea-level curves. Tilting of Late Quaternary marine terraces can be primarily reproduced by slip rates of ∼0.8–2.7 mm/yr on the OSTF and 0.3–0.6 mm/yr on the ABF. Slip on the TTF is not required to produce tilting of the marine terraces, suggesting that it may have ruptured less frequently than the OSTF and ABF in the Late Quaternary. The OSTF links 2016 ruptures north and south of Kaikōura, with the earthquake rupturing an interconnected network of faults.