This study investigates evidence for linkages and fault interactions centred on the Cust Anticline in Northwest Canterbury between Starvation Hill to the southwest and the Ashley and Loburn faults to the northeast. An integrated programme of geologic, geomorphic, paleo-seismic and geophysical analyses was undertaken owing to a lack of surface exposures and difficulty in distinguishing active tectonic features from fluvial and/or aeolian features across the low-relief Canterbury Plains. LiDAR analysis identified surface expression of several previously unrecognised active fault traces across the low-relief aggradation surfaces of the Canterbury Plains. Their presence is consistent with predictions of a fault relay exploiting the structural mesh across the region. This is characterised by interactions of northeast-striking contractional faults and a series of re-activating inherited Late Cretaceous normal faults, the latter now functioning as E–W-striking dextral transpressive faults. LiDAR also allowed for detailed analysis of the surface expression of individual faults and folds across the Cust Anticline contractional restraining bend, which is evolving as a pop-up structure within the newly established dextral shear system that is exploiting the inherited, now re-activated, basement fault zone. Paleo-seismic trenches were located on the crest of the western arm of the Cust Anticline and across a previously unrecognised E–W-striking fault trace, immediately southwest of the steeply plunging Cust Anticline termination. These studies confirmed the location and structural style of north-northeast-striking faults and an E–W-striking fault associated with the development of this structural culmination. A review of available industry seismic reflection lines emphasised the presence of a series of common structural styles having the same underlying structural drivers but with varying degrees of development and expression, both in the seismic profiles and in surface elevations across the study area. Based on LiDAR surface mapping and preliminary re-analysis of industry seismic reflection data, four fault zones are identified across the restraining bend structural culminations, which together form the proposed Oxford–Cust–Ashley Fault System. The 2010–2012 Canterbury Earthquake Sequence showed many similarities to the structural pattern established across the Oxford–Cust–Ashley Fault System, emphasising the importance of identification and characterization of presently hidden fault sources, and the understanding of fault network linkages, in order to improve constraints on earthquake source potential. Improved understanding of potentially-interactive fault sources in Northwest Canterbury, with the potential for combined initial fault rupture and spatial and temporal rupture propagation across this fault system, can be used in probabilistic seismic hazard analysis for the region, which is essential for the suitability and sustainability of future social and economic development.

La mesure et la modélisation des concentrations en $^{36}$Cl accumulé au sein d'un plan de faille normal permet d'estimer l'âge et le glissement des forts séismes passés ayant successivement exhumé ce plan de faille. Si cette méthode présente l'avantage de fournir des enregistrements paléo-sismologiques continus sur des périodes de temps relativement longues (10 000 à 20 000 ans), la modélisation de données repose jusqu’à présent sur un modèle direct qui permet difficilement d'attester de l'unicité du scenario proposé, et d'estimer précisément les incertitudes associées, et ne tient pas compte de l'histoire long-terme du plan de faille, avant son exhumation post-glaciaire (héritage). Nous avons développé dans un premier temps un nouveau modèle qui inclut l’histoire d'héritage, et mis en place une procédure d'inversion des données permettant de 1) déterminer l'ensemble des paramètres de l'histoire sismique d'exhumation, 2) d’attester de l'unicité du scénario proposé, et 3) de contraindre précisément ses incertitudes. Nous appliquons notre méthode d’inversion à 11 failles des Apennins Centraux et montrons une grande variabilité dans leur activité sismique au cours des derniers 10 000 à 45 000 ans, avec des accélérations représentant 2 à 20 fois la vitesse long-terme de la faille. Nos résultats suggèrent en particulier que l'activité sismique des failles des Apennins Centraux pourrait être contrôlée par les propriétés intrinsèques des failles (vitesse long-terme, longueur, segmentation, état de maturité structurale), ainsi que par des processus d'interactions visco-élastiques agissant entre les failles. / The use of $^{36}$Cl cosmogenic nuclide as a paleo-seismological tool to determine the seismic history of normal faults provide continuous records over the past 10 000 to 20 000 yrs. The modeling of the $^{36}$Cl concentrations measured at the surface of an exhumed fault-plane allows determining the age and the displacement of the past seismic events that successively exhumed the fault-plane. The available modeling approach is however unable to attest for the unicity of the inferred scenario, which makes the estimate of the associated uncertainties difficult. An other limitation concerns the long-term history of the fault-plane prior its post-glacial exhumation (inheritance), that is not fully accounted for in this model (Schlagenhauf et al., 2010). We have developed a reappraisal of this model that accounts for the inheritance history, and includes a procedure of data inversion to 1) determine all parameters of the exhumation history at once, 2) attest for the unicity of the proposed scenario, and 3) precisely determine the associated uncertainties. Applying our new modeling to 11 normal faults previously studied in Central Apennines, we observe a large variability of their seismic activity over the last 10 000 - 45 000 yrs, with slip-rate acceleration reaching 2-20 times their long-term slip-rate. In particular, our results suggest that the seismic activity of normal faults in Central Apennines could be controlled by intrinsic properties of the faults (such as their long-term slip-rate, fault-length, segmentation, state of structural maturity), and by visco-elastic stress transfers between faults.