Collaborative Research: Normal-Fault Facets as Recorders of Erosion and Tectonics

点击翻译按钮获取中文摘要

Earthquakes are expensive and dangerous natural hazards. Managing the risk they represent requires estimating the size and frequency of earthquakes in the geologic past. Often, this knowledge, which relies on information about the past activity of particular faults, is difficult and costly to obtain. This project tests a new method for estimating past earthquake activity through detailed field measurements and a simple mathematical model. Because mountain topography in these settings is also a product of climate, the data collected will provide information on variations in rates of weathering and erosion during the past one to two ice ages. Such information about the relationship between climate and erosion is important for a variety of applications, including models of long-term sedimentation that the oil and gas industry uses to study the formation of sedimentary deposits. The project will also foster education by training a post-doctoral research associate, and it will broaden participation in science by providing an undergraduate summer research experience for a student from an under-represented minority group. The project has a strong international collaboration with the University of Bergen in Norway and the University of London in the UK. This research will contribute both to an understanding of climate control on natural rates and processes of erosion as well as paleoseismology. The project tests a new method for estimating past earthquake activity through detailed measurements of the shape and steepness of mountains that lie next to faults, and which were created by motion on those faults. The method relies on a simple mathematical model for mountain-front form that predicts a quantitative relationship between the average rate of fault motion and the steepness of the adjacent terrain. The project will test this model by studying two locations where independent estimates of fault-motion rate are already available: the Wasatch Mountains, Utah, and the central Apennines Mountains, Italy. Measuring in detail the landscape form adjacent to active faults in these two sites, and examining the processes of weathering and erosion that modify topography over time, will provide a test of how well this method works to reconstruct past fault activity. The research includes field surveys, digital topography analysis, cosmogenic nuclide analysis, and feasibility testing of facet-slope analysis as a paleoseismology tool. This project is jointly supported by the Geomorphology and Land Use Dynamics, Tectonics, and International Science and Engineering programs.