Title: Artillery Infrasound and Acoustic Site Response in a Dynamic Snowpack at Little Cottonwood Canyon, Utah Program: Geophysics MS Committee Chair: Jeffrey B. Johnson Committee: Jeffrey B. Johnson, Jacob Anderson, Scott Havens Abstract: Snow cover strongly modulates the amplitude and spectral content of infrasound recorded in snow-covered environments. Using howitzer avalanche mitigation detonations as repeatable impulsive sources in Little Cottonwood Canyon, Utah, we examine spatial and temporal variations in recorded infrasonic signals. We develop an automated explosion picker constrained by expected acoustic time-of-flight, azimuth migration, and deviations in peak signal amplitude relative to event averages to construct a catalog of 151 identified artillery ordinance detonations across 71 known target locations. Infrasonic waveforms recorded by two ground-based sensor arrays are analyzed over a 15-day period during the late 2022–2023 winter season and compared with snow depth measurements from a nearby SNOTEL station. Results show that sensor-specific attenuation and spectral filtering occurs at scales less than 30 meters when sensors are buried by 2+ meters of snow. We speculate that snowpack heterogeneity can obscure true source characteristics and location accuracy over small spatial scales. Consequently, amplitude-based interpretations from individual buried microphones may misrepresent explosive yield or source intensity if snow-mediated site effects are not considered. Wind and temperature effects on acoustic time-of-flight contribute additional signal variability, though their influence cannot be fully resolved due to limited meteorological data. Furthermore, we demonstrate that dynamic snowpack conditions exert first-order control on infrasonic observations and provide recommendations therein to mitigate the influence of snow on recorded infrasound.
