The Holocene beach ridges at Turakirae Head, New Zealand, are remarkable because the fault that caused their uplift is accessible to paleoseismic trenching. Based on 40 14 C samples from eight trenches, we identify fi ve surface-rupturing earthquakes since ca. 5.2 ka (mean earthquake recurrence of 1230 ± 190 yr). The paleoearthquake record includes two more events than were recorded by the uplift and stranding of beach ridges at Turakirae Head. We conclude that beach ridges may provide an incomplete record of paleoearthquakes on oblique-reverse faults. The southern end of the Wairarapa fault includes several splays in the near surface at variable distances from Turakirae Head. Variable partitioning of slip between these splays (and perhaps the subduction interface down-dip of them) is inferred to have caused variable magnitudes of coseismic uplift at the coast, where at least one <3 m throw is not recorded by preservation of a ridge. Variations in wave climate or sediment supply (or interseismic subsidence) may also infl uence the number of beach ridges preserved by governing the morphology of the storm berm and controlling its extent of landward retreat. Such retreat may cause a berm to overwhelm, or amalgamate with, the next-highest beach ridge, resulting in the omission of one ridge, as probably happened at Turakirae Head at least once. Our 14 C data support the view that a widespread post-Last Glacial Maximum aggradational terrace in southern North Island, New Zealand, was abandoned soon after 12.1 cal yr B.P. From this, we infer that the Wairarapa fault has a late Quaternary slip rate of 11 ± 3 mm/yr.

We analyse a flight of post-Last Glacial Maximum terraces at Waiohine River, New Zealand that are progressively displaced by the dextral-slip Wairarapa Fault. The Waiohine River is shown to have smoothed its faulted river banks after each earthquake so that riser displacements are only recorded after abandonment of their lower bounding terrace tread. Digital elevation models produced from newly collected high-precision topographic data allowed us to precisely measure the cumulative dextral displacement of five risers and two palaeochannels, and the vertical displacement of six treads. The ratio of horizontal to vertical slip at the terraces ranges from 5.0 to 10.2 (average of 6.993.5 (2s)). Combining our new displacements for the 'Waiohine' aggradation terrace and next younger terrace with new and previous optically stimulated luminescence (OSL) ages for Waiohine terrace silts, we calculate Late Quaternary dextral slip rates for this central part of the Wairarapa Fault of 11.992.9 mm a (1 (2s) and !9.291.3 mm a(1 (2s). Based on the smallest and next smallest observed offsets, the magnitudes of the inferred 1855 (smallest) and penultimate (next-smallest) single-event displacements are 12.490.8 m (2s) and 9.791.7 m (2s), respectively.

We provide a summary of the surface fault ruptures produced by the Mw7.8 14 November 2016 Kaikōura earthquake, including examples of damage to engineered structures, transportation networks and farming infrastructure produced by direct fault surface rupture displacement. We also provide an overview of the earthquake in the context of the earthquake source model and estimated ground motions from the current (2010) version of the National Seismic Hazard Model (NSHM) for New Zealand. A total of 21 faults ruptured along a c.180 km long zone during the earthquake, including some that were unknown prior to the event. The 2010 version of the NSHM had considered multi-fault ruptures in the Kaikōura area, but not to the degree observed in the earthquake. The number of faults involved a combination of known and unknown faults, a mix of complete and partial ruptures of the known faults, and the non-involvement of a major fault within the rupture zone (i.e. the Hope Fault) makes this rupture an unusually complex event by world standards. However, the strong ground motions of the earthquake are consistent with the high hazard of the Kaikōura area shown in maps produced from the NSHM.

New information on the timing of past ruptures, size of single-event displacements and Holocene dextral slip rate of the Wairarapa and Ō hariu faults has become available from recent geological studies. This information is used to evaluate the conditional probability of rupture over the next 100 yr using four different recurrenceÁtime models, allowing for data and parameter uncertainties. The sensitivity of estimates to data and distributional assumptions is examined. The southern Wairarapa Fault has a probability of rupture in the next 100 yr of c. 7.7, 1.3, 2.3 and 4.3% under the exponential, lognormal, Weibull and inverse Gaussian models, respectively, based on preferred data inputs. Corresponding estimates for the Ō hariu Fault are c. 4.3, 5.1, 3.9 and 5.1%. A logic tree with subjectively assigned weights is suggested to combine such differing time-dependent estimates. This gives a 100-yr conditional probability of rupture of c. 3.0% for the southern Wairarapa Fault and c. 4.9% for the Ō hariu Fault.

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