Investigating the evolution of fault scarps in jointed volcanic rock through field evidence, morphometric techniques and novel methods

Abstract

The morphology of fault scarps in jointed volcanic rock records information on the tectonics, volcanism and geomorphology of a region. The evolution of scarp form has been modeled to extract information varying from the age of faulting events and the recurrence time between earthquakes to variations in erosion rates between glacial cycles in other lithologies, but no similar model exists for jointed volcanic rock. In this thesis, I investigate the evolution of fault scarps in jointed volcanic rock. In chapter 2, I present field observations and synthesize previous work on fault scarps in jointed volcanic rock to produce a conceptual framework based on the along-strike variation in profile form through time depending on process. In chapter 3, I quantify the along-strike variations in profile form by defining morphologic classes, using a supervised learning algorithm to automatically classify profiles. I define the “morphologic variability metric” which calculates the number of classes and their proportions in a moving window along a fault scarp. In chapter 4, I apply the morphologic variability metric to a controlled experiment in which a single-age scarp cuts three lithologies and show that the metric reports different variability values along the scarp for each lithologic unit. In chapter 5, I adapt the metric to increase its suitability for large datasets and explore the most appropriate use cases and statistical methods with which to use it depending on the scale of the analysis.