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north america from space

Shujuan Mao, M.I.T-Space-Time Monitoring of Groundwater Fluctuations Using InSAN (ISAN) Measurements

When:
Thursday, Apr 22, 2021 12:00 PM
Where:
https://stanford.zoom.us/j/92246012053 Passcode: 467202
Audience:
General Public
Sponsor:
Geophysics Department

Shujuan Mao

Dept. of Earth, Atmospheric and Planetary Sciences, M.I.T.

Space-Time Monitoring of Groundwater Fluctuations Using InSAN (Interferometry of Seismic Ambient Noise) Measurements

Relative changes in seismic velocity (Δv/v) reflect changes in rocks’ mechanical state and can be used to detect and quantify perturbations in stress field, rock fractures, and fluid content.  A seismological approach, which I refer to as InSAN (Interferometry of Seismic Ambient Noise), enables monitoring Δv/v continuously in time, with high sensitivity and at low cost. This approach has been successfully employed to study a wide variety of time-varying processes in the crust. In my work, I go one step further than the traditional protocol of this technique, by not only detecting the temporal changes but also imaging the spatial variations of Δv/v.  In this presentation I demonstrate how these space-time measurements of Δv/v can enhance the understanding of groundwater fluctuations. By investigating the Coastal Los Angeles Basins during 2000-2020, I show that Δv/v monitoring reveals the spatial patterns of groundwater fluctuations and that seasonal variability is most pronounced in confined aquifers. InSAN not only presents spatial patterns in Δv/v that are consistent with surface deformation inferred from InSAR, but also enables the characterization of aquifers and their hydrology at different depths. This pilot application illustrates the promise of using the spatio-temporal InSAN measurements of Δv/v to identify and decipher surface hydrologic processes. InSAN monitoring can be used in concert with other geophysical tools and has the potential to propel the knowledge of various dynamic processes.

https://stanford.zoom.us/j/92246012053  Passcode:  467202

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