Tracking shallow groundwater response to a pumping test using a dense passive seismic array

Facing the societal issues related to water resources management, the development of ambient noise-based seismology for monitoring fluids in the subsurface is promising but still challenging (1). In this study, we propose a seismological monitoring of shallow groundwater with high spatial resolution, by applying ambient noise interferometry techniques. On a glacio-alluvial plain containing a shallow aquifer near Grenoble (France), we installed a dense array of 50 seismic nodes settled during five days. A pumping test was performed in a borehole during the experiment, inducing a fast and heterogeneous response of the aquifer. We estimated relative changes in surface wave velocity (dV/V) from autocorrelations of ambient noise recorded by the 50 sensors. During the pumping phase, dV/V increases by more than 10% near the borehole, indicating a significant decrease in pore pressure. Mapping the seismological response to pumping suggests a high channelization of the hydrogeological paths. Poroelastic modeling combined with active seismic campaigns improves the interpretation of observations (2), paving the way to a high-resolution time-lapse 3D mapping of the water dome and potential fluxes. References 1 - GaubertBastide, T., Garambois, S., Bordes, C., Voisin, C., Oxarango, L., Brito, D., Roux, P. (2022). Highresolution monitoring of controlled water table variations from dense seismicnoise acquisitions. Water Resources Research,58(8), e2021WR030680. 2 - Voisin, C., Garambois, S., Massey, C., Brossier, R. (2016). Seismic noise monitoring of the water table in a deep-seated, slow-moving landslide. Interpretation,4(3), SJ67-SJ76.