Leiyu He, Erdinc Saygin, David Lumley, Chaoying Bai

In order to explore the relationships between environmental subsurface changes and seismic velocities, we use nearly four years (2015-2018) of continuous ambient seismic noise data recorded in a multi-level borehole sensor array to measure relative seismic velocity changes at the SW Hub CO2 Geosequestration Site in Harvey, Western Australia using seismic noise interferometry. We find a direct correlation between seismic velocity and seasonal groundwater changes, where seismic velocity changes follow groundwater level changes. Our rock and fluid physics modeling are highly consistent with the observations suggesting the seismic velocity changes are a direct result of groundwater table fluctuations.