Anthropogenic deforestation increases rockfall hazard in southern Christchurch, New Zealand.

Developing a robust chronology for mass-movement events is of crucial importance to understanding triggering mechanisms and assessing hazards. We constrain the emplacement time of four palaeorockfall boulders near Christchurch, New Zealand, using optically stimulated luminescence (OSL) of quartz and infrared stimulated luminescence dating (IRSL) of K-feldspar from colluvial loess deposits underlying and upslope of individual boulders. The quartz OSL and K-feldspar pIRIR 290 ages are all consistent with the stratigraphy and in excellent agreement with each other, indicating that all the boulders that overlie the in-situ loess and oldest loess colluvium unit must have been emplaced < 13 ka ago. A comparison of luminescence ages with cosmogenic 3 He surface-exposure ages from the surfaces of each boulder shows that two out of four boulders contain pre-deposition 3 He inheritance.Overall, the optical ages are consistent with both a prehistoric rockfall event at ~8-6 ka and a possible preceding event at ~14-13 ka, although the temporal resolution of the time of emplacement of individual boulders is ca. 3-5 ka. This resolution is not limited by age uncertainties but rather by the stratigraphy. This study is the first to show a successful application of luminescence dating to New

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Optical and radiocarbon dating of loessic hillslope sediments in New Zealand's South Island is used to constrain the timing of prehistoric rockfalls and associated seismic events, quantify spatial and temporal patterns of landscape evolution, and examine hillslope responses to climatic and anthropogenic forcing. Exploratory trenches adjacent to prehistoric boulders enable stratigraphic analysis of loess and loesscolluvium pre-and post-boulder emplacement sediments. Luminescence ages from colluvial sediments constrain timing of boulder emplacement to between ~3.0 and ~12.5 ka, well before the arrival of Polynesians (c. AD 1280) and Europeans (c. AD 1800) in New Zealand. Three phases of colluviation are revealed at the Rapaki study site, reflecting natural and anthropogenic-driven shifts in sedimentation and landscape evolution. Sediment accumulation rates increased considerably (>15 factor increase) following human arrival and associated anthropogenic burning of hillslope vegetation. Phytolith results suggest paleo-vegetation at Rapaki was compositionally variable and persisted under a predominantly cool temperature environment with warm-temperate elements. Palm phytolith abundances imply maximum climate warming during early (~12-11 ka) and late (~3-2 ka) Holocene phases. This study provides insights into the spatial and temporal patterns of hillslope evolution, highlighting the roles of climate change, earthquakes, and humans on surface processes.Keywords: rockfall, paleoseismicity, hillslope response, OSL, radiocarbon 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 2 patterns of hillslope evolution, highlighting the roles of climate change, earthquakes, and humans on surface processes.

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.