Geometric Phase Sensing of Environmental Conditions Using Ambient Seismic Noise: An Application From Southwest Iceland

We leverage ambient seismic noise to implement a novel geometric phase sensing method for investigating the effects of environmental conditions on near-surface ground properties. The geometric phase, derived from topological acoustics, characterizes the geometry of a wavefield by incorporating cross-correlation information between seismic sensors. Changes in geometric phase, (Formula presented.), are expressed as changes in vectorial orientation, describing the wavefield evolution over time. To demonstrate the method, we designed an end-to-end workflow by applying an open access temporal high-resolution data from a seismic array in southwest Iceland and measured (Formula presented.) over a 2-year period. We observe that the seasonal fluctuations of (Formula presented.) are highly correlated with surface air temperature, reflecting changes in ground properties during the freeze-thaw cycle. We assess the seasonal stability of the noise source distribution and conduct a numerical test to verify that the seasonal pattern in (Formula presented.) is minimally affected by shifts in noise source direction. Several advantages of geometric phase measurements, including the elimination of lag window selection and reduced computational costs, suggest their strong effectiveness in monitoring changes in ground properties with time. We suggest that the geometric phase can play a significant role in the future of environmental monitoring.