Seismological and Geochemical Monitoring of Greenhouse Gas Emissions in the Lower Taylor Valley (McMurdo Dry Valleys, Antarctica)

The Lower Taylor Valley, owing to the McMurdo Dry Valleys, are one of the coldest and driest desert ecosystems on the planet and represent a key natural laboratory for investigating permafrost, glacier dynamics, and subsurface geochemical and geophysical processes. In recent years, a systematic and dense field measurements of soil gas concentrations and fluxes revealed an anomalous greenhouse gas concentration not randomly distributed, but forming an elongated E–W oriented zones that follow the main principal axes of the valley. To investigate the structure of the permafrost and shallower crustal layers, as well as the preferential path controlling the multigas emissions, the geochemical surveys have been complemented, for the first time in this area, by passive seismic observations. To do that, a passive seismic experiment was carried out between December 24, 2024, and January 23, 2025, using an array of 15 three-component nodal sensors deployed in the central portion of the Lower Taylor Valley. The array geometry was designed in a spiral configuration to enhance azimuthal coverage, reaching a maximum aperture of 1.5 km. Despite the severe Antarctic environmental conditions, we successfully recorded about 25 days of continuous seismic data, constructing thus a dataset of high-quality recordings. Preliminary analyses revealed coherent seismic arrivals consistently recorded across the array. The signals are characterized by regular, high-frequency repeating peaks in the seismograms and were interpreted as icequakes originating from the Commonwealth Glacier at the northern boundary of the valley. Additionally, we also identified a variation in signal amplitude and frequency content among stations, suggesting a possible difference in local environmental conditions or subsurface properties affecting the seismic signal.