Summary: In the last two decades, the development of New Zealand prehistory has seen a movement away from a strong emphasis on archaeology to a growing concern with synthesis and theory. One aspect of this has been the prolonged discussion of the cultural status of the New Zealand Maori during the �Classic Maori Phase�. In part this was stimulated by an increase in knowledge of the earlier Archaic period (Duff, 1956:73-82). It was also influenced by a widespread interest in the records of early voyagers and travellers encouraged by the wealth of new editions available (for example, the Beaglehole editions of the journals of Cook and Banks). The inadequacies of the archaeological assemblages belonging to this phase were acknowledged at the Second Annual Conference of the New Zealand Archaeological Association (Golson, 1957:279). Consequently, many prehistorians began to regard these records as supplementary information. Observations made by Europeans, as visitors or residents in New Zealand were compiled in order to delineate the differences between the earlier and later phases of New Zealand prehistory (Golson, 1957:279-280; Golson and Gathercole, 1962:271). The past seven years have been seen a marked upsurge of interest in the precise details of culture contact between European and Maori during the late eighteenth and early nineteenth centuries. This period of initial contact was named the �protohistoric� period of Maori culture in line with the terminology adopted overseas (Golson and Gathercole, 1962:173). The French, who differentiated between the prehistoric period when writing was non-existent, and the historic period when cultural developments could be studied with the aid of written documents, introduced the term �protohistoric� to mark the early historic period when written documents were occasionally produced, but not on a universal scale (Hawkes, 1951: 1, 3)--Chapter One.

Summary: In the last two decades, the development of New Zealand prehistory has seen a movement away from a strong emphasis on archaeology to a growing concern with synthesis and theory. One aspect of this has been the prolonged discussion of the cultural status of the New Zealand Maori during the �Classic Maori Phase�. In part this was stimulated by an increase in knowledge of the earlier Archaic period (Duff, 1956:73-82). It was also influenced by a widespread interest in the records of early voyagers and travellers encouraged by the wealth of new editions available (for example, the Beaglehole editions of the journals of Cook and Banks). The inadequacies of the archaeological assemblages belonging to this phase were acknowledged at the Second Annual Conference of the New Zealand Archaeological Association (Golson, 1957:279). Consequently, many prehistorians began to regard these records as supplementary information. Observations made by Europeans, as visitors or residents in New Zealand were compiled in order to delineate the differences between the earlier and later phases of New Zealand prehistory (Golson, 1957:279-280; Golson and Gathercole, 1962:271). The past seven years have been seen a marked upsurge of interest in the precise details of culture contact between European and Maori during the late eighteenth and early nineteenth centuries. This period of initial contact was named the �protohistoric� period of Maori culture in line with the terminology adopted overseas (Golson and Gathercole, 1962:173). The French, who differentiated between the prehistoric period when writing was non-existent, and the historic period when cultural developments could be studied with the aid of written documents, introduced the term �protohistoric� to mark the early historic period when written documents were occasionally produced, but not on a universal scale (Hawkes, 1951: 1, 3)--Chapter One.

A programme of archaeological research was undertaken in the Wairarapa region on the northern shores of Cook Strait, New Zealand. Some 27 excavations conducted during a 3 year period were designed primarily to examine prehistoric economy and settlement pattern in the region. In addition, studies were made of early historical records of Maori life, Maori traditional history, and aspects of the modern and prehistoric enviroment. In the analysis of excavated material, particular attention was given to physical anthropology, subsistence economy, and the trading patterns revealed by the importation of a number of rock types from elsewhere in New Zealand. It was found that human occupation in Palliser Bay was most intense from about 1150AD to 1400AD, and that significant depopulation may have occurred by 1650AD. At least 6 kinship linked communities were resident in this early period, probably originating from further north. Over several centuries thay strengthened their social ties with other communities in Cook Strait, progressively losing contact with northern areas. A conjunctive picture is reconstructed of a typical community of 30 to 40 people, and aspects of their physical condition, economy, technology, settlement pattern, external social relationships and ideology described. Their economy was initially a balance between hunter-gatherer pursuits and kumara-based horticulture, but in the course of time their forest clearing activities set into motion a series of episodes of erosion which culminated in the development of broad shingle river beds and active fans. High riverine sediment loads led to the loss of much of the local marine fauna at river mouths. A general climatic deterioration about 1450AD and then from 1600 onwards accelerated this process to render the enviroment largely unsuitable to Polynesian habitation. It is argued that coupled to these changes are settlement pattern modifications and an increase in human disease and malnutrition.

L’objectif principal de cette thèse est de tirer de données LiDAR de télédétection à très haute résolution afin d’extraire une partie du traces tectono-géomorphiques imprimées dans la morphologie de grands tremblements de terre préhistoriques. Les informations consultées dans ces traces constituent l'historique des glissements cumulés de grands tremblements paléoséismique successifs le long d'une faille donnée. L'historique des glissements permet de déterminer le nombre d'événements et les glissements les plus importants produits par ces événements. La connaissance des plus grandes glissades produites par des grands séismes historiques et préhistoriques permettra de déduire l'ampleur potentielle des événements futurs. La caractérisation de la distribution du glissement superficiel fournit des informations importantes sur la mécanique des failles, les contrôles de la propagation de la rupture et la répétabilité de la rupture à certains points le long de la faille. Cependant, la caractérisation et la mesure correctes de la distribution des glissements à partir de formes de relief géomorphologiques déplacées par tectonisme sont accompagnées d'incertitudes considérables, résultant principalement de processus d'érosion et de dépôt. Ces incertitudes pourraient entraîner à la fois une sous-estimation et une surestimation du glissement, ainsi que des résultats contradictoires issus d'enquêtes différentes sur le même défaut. Par conséquent, nous avons développé une nouvelle technique basée sur MATLAB, 3D_Fault_Offsets, pour caractériser mathématiquement, et donc automatiquement, la géométrie 3D de marqueurs géomorphiques décalés (définie par 9 entités géométriques situées de part et d'autre de la faille), puis calculer composants latéraux et verticaux du glissement. Nous estimons que les incertitudes générées par cette technique définissent mieux la gamme des "véritables" compensations potentielles par rapport aux incertitudes plus libérales proposées dans d’autres études, pourtant ils se révèlent assez volumineux. Après vérification de l'efficacité du code en mesurant à nouveau 3 ensembles de données paléosismiques, nous avons l’appliqué à une faille de décrochement qui était historiquement capable d'un séisme de chute de contrainte importante (MW ~ 8,2 en 1855), la faille de Wairarapa. Nous avons identifié et analysé un total d'environ 700 marqueurs géomorphiques déplacés le long d'une zone de données LiDAR de 70 km, ce qui en fait l'un des ensembles de données paléosismiques les plus vastes et les plus denses. Les décalages latéraux mesurés vont de quelques mètres à environ 800 m, mais la majorité d'entre eux sont inférieurs à 80 m, ce qui permet d'examiner les plus récents glissements de faille latéraux. Les décalages verticaux varient entre 0 et ~ 30 m et suggèrent des rapports de glissement vertical / latéral généralement compris entre 10 et 20%. Nous avons effectué les analyses statistiques de la collection dense de décalages mesurés séparément le long des principaux segments successifs qui constituent l'étendue de la faille étudiée. Dans la plupart des segments, cette analyse a révélé la présence de 6 à 7 amas décalés dans la plage allant de 0 à 80 m, suggérant la rupture de la faille de Wairarapa lors de 6 à 7 grands séismes précédents. Les plus grandes glissades que nous déduisons pour ces tremblements de terre passés sont importantes, la plupart dans la plage 7-15 m. Chaque glissement sismique semble varier le long de la faille et généralement plus grand dans sa partie sud. La faille de Wairarapa a ainsi provoqué à plusieurs reprises d'importants séismes dus à la chute de contraintes au cours de la période préhistorique, ce qui souligne le risque sismique élevé qu'elle pose dans le sud de la Nouvelle-Zélande. Par conséquent, l'utilisation de notre nouveau code 3D_Fault_Offsets avec des données topographiques à haute résolution telles que LIDAR peut permettre de mieux évaluer le comportement futur des failles sismogènes. / The main scope of this PhD thesis is to utilize very high-resolution remote sensing LiDAR data to extract some of the tectono-geomorphic traces imprinted in the morphology from large prehistoric earthquakes. The information that is accessed in these traces is the cumulative slip history of successive large paleoearthquakes along a given fault. The slip history allows the determination of the number of events and the largest slips produced by those respective events. The knowledge of the largest slips produced by historic and prehistoric large earthquakes will enable some inference into the potential magnitude of future events. Characterizing the distribution of surface slip provides important insights into fault mechanics, controls on rupture propagation, and repeatability of rupture at certain points along the fault. However, properly characterizing and measuring the slip distribution from tectonically-displaced geomorphic landforms comes with considerable uncertainties mostly resulting from erosion and depositional processes. These uncertainties could lead to both underestimation and overestimation of the slip, and to conflicting results from different surveys of the same fault. Therefore, we have developed a new MATLAB-based technique, 3D_Fault_Offsets, to mathematically, and hence automatically, characterize the 3D geometry of offset geomorphic markers (defined by 9 geometric features either side of the fault), and then calculate the lateral and vertical components of slip. We believe that the uncertainties obtained from this technique better define the range of potential ‘true’ offsets compared to more liberal uncertainties offered in other studies, yet they reveal to be fairly large. Upon verification of the code efficacy by successfully re-measuring 3 paleoseismic datasets, we applied it to a strike-slip fault in New Zealand that was historically capable of a large stress drop earthquake (MW~8.2 in 1855), the Wairarapa fault. We identified and analyzed a total of ~700 displaced geomorphic markers along a 70-km stretch of LiDAR data, making this one of the largest and densest paleoseismic datasets. Measured lateral offsets range from a few meters to about 800 m, but the majority are lower than 80 m, providing the means to examine the most recent lateral fault slips. The vertical offsets range between 0 and ~30 m, and suggest vertical to lateral slip ratios commonly in the range 10-20%. We conducted the statistical analyses of the dense collection of measured offsets separately along the successive major segments that form the investigated fault stretch. In most segments, this analysis revealed 6-7 offset clusters in the range 0-80 m, suggesting the Wairarapa fault ruptured in 6-7 previous large earthquakes. The largest slips we infer for these past earthquakes are large, most in the range 7-15 m. Each earthquake slip seems to vary along the fault length, and be generally greater in its southern part. The Wairarapa fault has thus repeatedly produced large stress drop earthquakes in prehistoric time, which emphasizes the elevated seismic hazard it poses in Southern New Zealand. Therefore, the use of our new code 3D_Fault_Offsets with high resolution topographic data such as LIDAR can lead to better assessments of future behavior of seismogenic faults.