KINEMATICS AND DEBRIS THICKNESS OF TIMPANOGOS ROCK GLACIER, UTAH USING InSAR AND ELECTRICAL RESISTIVITY TOMOGRAPHY

Documenting rock glacier ice content and movement is critical for assessing water resources in arid regions like Utah, where alpine ice can contribute significantly to the downstream water supply. This study focuses on Timpanogos Rock Glacier near Provo, Utah, using geophysical methods to characterize surface motion and the debris layer thickness. Preliminary InSAR analysis reveals approximately 10-20 cm of surface motion across most of the Rock Glacier, which we validated with repeated Real-Time Kinematic GPS surveys. The thickness of the debris layer above ice has a strong, dampening effect on ice melt rates and, therefore, the potential for ice melt to contribute to downstream water resources. Electrical Resistivity Tomography (ERT) provides further insights into the glacier’s subsurface structure. In Fall 2024, we collected data along two 72-meter-long transects, with 1-meter electrode spacing in dipole-dipole. Our inversions reveal the sub-surface resistivity structure down to twenty meters in high resolution. High resistivity values exceeding 50,000 Ω meters reveal the presence of significant ice, while lower resistivity values reveal the debris layer thickness overlying the ice. Our results illustrate that Timpanogos Rock Glacier is like a debris-covered glacier in that it has a single debris layer that covers an internal ice body primarily composed of sedimentary ice. Our findings and direct observations from a moulin, intermittently present on the rock glacier surface, suggest that the internal ice body formed from incorporating snow/firn layers into the rock glacier body: a process that likely continues in the modern climate despite rising temperatures. This work sets the stage for more accurate models of glacier response to climate change in arctic and alpine environments facing complete deglaciation.