Monitoring near surface seismic attenuation variations using train tremors

Passive seismic methods hold valuable information about the physical properties of the subsurface, enabling continuous, non-intrusive monitoring of groundwater dynamics. This study introduces a novel methodology for monitoring near-surface seismic attenuation variations using repetitive seismic noise sources. Our approach employs a single-station technique to quantify seismic attenuation variations by evaluating the linear relationship between the frequency and spectrum amplitude variations. We applied this method in the Lyon water catchment area, utilizing train tremors as a continuous and stable seismic source. The case study demonstrates that seismic attenuation variations correlate strongly with environmental factors such as rainfall and significant changes in the water table due to a flood event. This methodology offers an effective and practical means to continuously monitor the subsurface seismic attenuation using opportune noise sources, providing valuable insights into groundwater dynamics and subsurface processes.