Deep-Seated Gravitational Slope Deformation in the Sawatch Range of Colorado
Maddie Festin, University of Utah

Faculty Mentor Jeffrey Moore, University of Utah

SESSION B 10:45-11:00AM
Dumke, Alumni House
Sciences

Deep-seated gravitational slope deformations (DSGSDs) are large-scale, creeping mass movements often involving entire mountain slopes. These enormous landslides may be on the order of kilometers in height and length, move a few millimeters to centimeters a year, and can generate secondary hazards from landslides and debris flows. While there have been many studies on DSGSD from the European Alps, few similar studies have been conducted in the United States. This research aims to identify DSGSD in an area of 2200 square kilometers in the Sawatch Range of Colorado, followed by mapping, geomorphic analysis, and comparison with satellite Interferometric Synthetic Aperture Radar (InSAR) displacement data. We used satellite imagery and Light Detection and Ranging (LiDAR) data to identify DSGSD across the mountain range, followed by a week-long field visit to collect ground data and imagery. Results show that DSGSD are relatively common across the Sawatch range, and many of these phenomena are actively moving. We identified 28 sites that exhibit physical characteristics of DSGSD, of which eight appeared to be moving with a downward velocity of 1-2 cm/y .  About half of the identified DSGSDs were west-facing. Almost all DSGSD occurred in granitic bedrock, with a few in metamorphosed rock. The largest DSGSD was over 8 km2, but most fall between .5-1 km2. This research provides insights into their distribution and geomorphology while contributing to the broader catalog of DSGSDs.

Albedo Evolution and the Shifting Arctic Ice Pack
David Gluckman, University of Utah

Faculty Mentor Ken Golden, University of Utah

SESSION B 11:05-11:20AM

Dumke, Alumni House
Sciences

During the late spring and summer, Arctic sea ice experiences some of its most drastic changes. As highly reflective snow and ice surfaces melt, they are replaced by darker, light-absorbing melt ponds and ocean water, lowering the overall albedo (the ratio of reflected to incident solar radiation) of the Arctic ice pack. Over the last 40 years, we have observed a dramatic decline of summer sea ice extent as well as a shift from a largely perennial to a more seasonal Arctic ice pack. Smoother seasonal ice, which forms during the winter and melts to open water during the summer, has significant topographical differences from rougher, hummocky multiyear ice. Using both levelset and temporal modeling approaches, we investigate the connection between sea ice surface topography and resulting albedo during melt pond evolution. Our findings suggest that surface topography is an important driver of ice-albedo feedback. In this talk, I will discuss these findings and how the significant differences in the albedo profiles of seasonal versus multiyear ice help drive the system toward the disappearance of multiyear ice.

Thermal Evolution of Brine Fractal Geometry in Sea Ice
Nash Ward, University of Utah

Faculty Mentor Kenneth Golden, University of Utah

SESSION B 11:25-11:40AM
Dumke, Alumni House
Sciences

The brine microstructure of sea ice and its strong dependence on temperature govern key processes critical to the role of sea ice in climate and the polar marine ecosystems. The brine phase also largely determines electromagnetic behavior in sea ice remote sensing. It has long been suspected that the brine microstructure displays fractal characteristics, a self-similar geometry over varying scales. Here I present the first comprehensive, quantitative study of the fractal dimension of brine in sea ice and how it depends on temperature and porosity. Using X-ray tomography data from Arctic sea ice, for both columnar and granular ice, we employ three different methods of computing the fractal dimension. We find all data agreed closely with a simple theoretical curve relating fractal dimension to porosity, which holds for exactly self-similar porous media, such as the famous Sierpinski triangle, as well as statistically self-similar porous media, like sandstones. Furthermore, we discovered there exists an ordinary differential equation model which accurately represents the evolution of the fractal dimension and porosity of the sea ice data through changes in temperature. This ODE has also been shown to hold for the porosity and fractal evolution of exactly self-similar geometries, namely the Sierpinski triangle and the Apollonian gasket. These findings open the door to sea ice applications of widely used theoretical models and tools for predicting the fluid and electromagnetic transport properties of composites with fractal microstructure. We also explore the influence of the fractal geometry of the brine phase on how microbial life is organized in this multiscale porous habitat.