Adam Dickson Thesis Proposal

Title: Mechanical Property Constraints and Seasonal Snow Structures Through Active Source Seismic Techniques

Abstract: In alpine regions, seasonal snow can exhibit significant variations in physical properties at spatial scales of tens of meters and temporal scales of hours. This variability suggests that the extrapolation of traditional in-situ point measurements may not best capture snow conditions at the watershed scale. Estimating snow’s mechanical properties through remotely sensed seismic measurements presents a new opportunity for snow research. My proposed approach uses surface and body wave seismic measurements, obtained in profile using a towed active source seismic system, to quantify snow mechanical properties. The novel streamer consists of 24 vertical and 24 horizontal 100 Hz geophones spaced 10 cm apart. Combined with a 12-volt, three-sensor push-pull solenoid seismic source, I can extract kHz-range compressional (P-wave) and shear (S-wave) seismic signals in profile to obtain cm-scale measurements. For my thesis, I will utilize direct first arrival and surface wave dispersion to estimate P-wave and S-wave velocities of snowpack layers. Using empirical, laboratory, and field-based measurements, I will then estimate mechanical properties from the seismic velocities. From seismic reflection profiles, I will explore and compare snow structure and high-density layers within the snowpack with snow pit measurements. Preliminary results from Mores Creek Summit, Idaho, and Grand Mesa, Colorado reveal measurable velocity differences over both space and time. These measurements, obtained during both early and late-season snow conditions, match bulk density estimates from independent in situ measurements. A reflection profile highlights decimeter-scale variations in reflection strength and depth to key seasonal snow layers. Through these studies I will explore vehicle mobility, avalanche, and water resource issues in snow science.

Advisor: Lee Liberty

Committee: Hans-Peter Marshall, Dylan Mikesell