Landscape development and fault behavior in tectonically active areas

In this thesis, a variety of possible interactions between tectonic uplift and geomorphic processes, and the resulting topographic response is explored. The main tools used are field observations, high-resolution topographic data and analyses, and numerical models. First, the dissertation documents how fault segmentation affects surface slip distributions. Statistical methods were developed that use collected paleoseismic data to estimate fault properties. Using these statistical methods and numerical models, the Cholame segment of the San Andreas Fault, central California, is estimated to be 2/3–1/4 as strong as the Carrizo segment. In order to understand how fault morphology is affected by the presence of near-surface fractures, the second chapter used numerical models and field observations to demonstrate that topographic complexity of bedrock scarps increases with fracture density. The models show that slip along faults drives movement along near-surface fractures, which may slip in the same or opposite sense of the fault. In order to understand how fault scarp morphology may change with time, the third chapter reports results from a model of scarp degradation that examines the diffusive geomorphic response of scarps to uplift and the possible effects of bedrock exposure on the topography. The study shows that the topographic expression of faults is controlled by bedrock exposure, rate of regolith production, fault slip rate and geometry, and geomorphic transport rates. The fourth chapter combines field observations and numerical models of sites in Kyrgyzstan, Central Asia and Kenya, East Africa to show how large landscape characteristics (basins and rangefronts on the order of 10s of km) may strongly be affected by structural reorganization in tectonically active areas. In the last two chapters, landscape response to uplift was quantified along the Dragon's Back pressure ridge in the Carrizo Plain of central California. The study extends the threshold landscape model to include the effects of tectonic forcing and shows that local relief and fundamental landscape scale may only be weakly controlled by tectonic uplift in the types of areas investigated.; Landscape response to uplift is a complex phenomenon that cannot be encapsulated by a single existing theoretical model. This thesis extends existing simple models to consider the effects of uplift; however, many factors ( e.g., the effect of rock type and climatic variations over broad spatial scales) have yet to be adequately investigated. This points to the rich variety of interactions possible between tectonics, geomorphic transport and topography, and presents methods with which to understand this interaction.