Space-Time Monitoring of Groundwater in the Coastal Los Angeles Basins via Seismic Interferometry

Shujuan Mao, Albanne Lecointre, Robert D. van der Hilst, & Michel Campillo

Submitted August 16, 2021, SCEC Contribution #11578, 2021 SCEC Annual Meeting Poster #234

Relative changes in seismic velocity (Δv/v) are associated with perturbations in mechanical properties of crustal materials. Interferometry of ambient noise enables the continuous monitoring of relative changes in seismic velocity (Δv/v), which have been used to study various time-evolving processes in the crust. Here we extend the applications of Δv/v monitoring by not only detecting the temporal changes but also imaging the spatial variations, based on newly-developed coda-wave sensitivity kernels. We use the space-time observations of Δv/v to investigate the hydrologic processes in the Coastal Los Angeles Basins during 2000-2020. Seasonal variability of Δv/v, related to the annual recharge and withdrawal of groundwater, appears most pronounced in confined zones. Cumulative Δv/v, indicating a long-term groundwater decline, extend to broader areas including the unconfined forebay. The spatial patterns of Δv/v agree with surface deformation inferred from InSAR, but also further enable the characterization of aquifers and their hydrology at different depths. This pilot application shows the promise of using Δv/v observations to propel the knowledge about the temporal behavior as well as spatial variations of aquifer systems. Integrated with other geophysical data, the new insight obtained from Δv/v via seismic interferometry allows a more comprehensive description and understanding of near-surface hydrologic processes.

Key Words
space-time monitoring, hydrologic process

Mao, S., Lecointre, A., van der Hilst, R. D., & Campillo, M. (2021, 08). Space-Time Monitoring of Groundwater in the Coastal Los Angeles Basins via Seismic Interferometry. Poster Presentation at 2021 SCEC Annual Meeting.

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