Watching the Cryosphere thaw: Seismic monitoring of permafrost degradation using distributed acoustic sensing during a controlled heating experiment

Permafrost degradation is rapidly increasing in response to a warming Arctic climate, altering landscapes and damaging critical infrastructure. Solutions for monitoring permafrost thaw dynamics are essential to understand biogeochemical feedbacks as well as to issue warnings for hazardous geotechnical conditions. We investigate the feasibility of permafrost monitoring using permanently installed fiber-optic seismic networks. We conducted a 2-month seismic monitoring campaign during a controlled thaw experiment using a permanent surface orbital vibrator (SOV) and a 2D-array of distributed acoustic sensing (DAS) cables, and observed significant (15%) shear-wave velocity (V_s) reductions and approximately 2 m depression of the permafrost table beneath the heating zone. These observations were validated by time-lapse horizontal-to-vertical spectral ratio (HVSR) analysis from three co-located broadband seismometers. The combination of SOV and DAS provided unique seismic observations for permafrost monitoring at the field scale, as well as a basis for design and development of early warning systems for permafrost thaw.