Atmosphere-groundwater modulated seismic velocity variations revealed by distributed acoustic sensing

Monitoring seismic velocity variations in Earth’s critical zone (CZ) provides crucial information on Earth’s environmental changes. However, monitoring of urban near-surface environments at high temporal resolution is still challenging. Combining distributed acoustic sensing (DAS) and seismic interferometry, we acquired hourly high-precision seismic velocity variations in downtown Hefei city, China, with amplitude up to . Velocity variations exhibit long-term and diurnal signals with amplitudes of . Sub-daily signals are also presented with amplitudes one order smaller. The long-term and diurnal variations of seismic velocity are well explained by thermoelastic effect modeling, and transient signals (~ 0.05%) are well fitted by hydraulic force modeling from groundwater data. The sub-daily variations are most likely driven jointly by thermal force and barometric pressure. This work demonstrates the capability of DAS to conduct hourly monitoring of Earth’s CZ in urban areas and cast insight into land-atmosphere coupling from a seismological perspective.