| Description |
This thesis describes the development of software used to extract and analyze topographic profiles of normal fault scarps from high-resolution LiDAR (Light Detection and Ranging) digital elevation models. The software, `Scarp Offset Analysis' (SOA), consists of several scripts written in the Python computer language that partly automate the extraction of fault scarp parameters including surface offset, scarp asymmetry, location and magnitude of maximum scarp slope, far-field slopes, and the location of the scarp's base and crest. These parameters were calculated from 36,757 topographic profiles extracted every 1 m along ~37 km of the Nephi segment of the Wasatch fault. The profiles were extracted from bare earth digital elevation models (DEMs) derived from high-resolution (0.5-m horizontal posting) LiDAR elevation data. The scarp profiles provide information on individual scarps and as a whole, provide a dense network for analyzing spatial trends in fault offset along strike at scales from meters to tens of kilometers. The surface offset measurements are also utilized to produce a prototype 3D probability function (3D-PDF), which is an along strike graphical representation of trends in surface offset expressed as a probability density plot. The 3D-PDF function is used to evaluate several hypothetical models of fault displacement along strike, as a prototype application to illustrate the potential use of SOA software in paleoseismic studies. Application of the 3D-PDF to the Nephi segment suggests unique rupture profiles for the northern and southern fault strands; however, interpretation of the 3D-PDF is inhibited by the lack of detailed information concerning the age of alluvial surfaces offset by faulting. Ultimately, the SOA software is an important tool for studying fault scarp morphology, which can be applied to other LiDAR datasets and also adapted for use in the study of fluvial terraces, lacustrine and marine shoreline scarps, and similar geomorphic features. |
