Fig. 1: Conceptual model for the vadose zone water dynamics and time-lapse seismology example on Ridgecrest DAS array.

a Vadose zone soil moisture can be readily replenished by precipitation (P) and lost due to evapotranspiration (ET) to the atmosphere or deep drainage (D) to recharge deeper aquifers. b Map view of Ridgecrest DAS array. The upper-left inset panel depicts the California (CA) map with Indian Wells Valley marked by a yellow box. The purple line represents the boundary of Indian Wells Valley. The lower-right inset panel shows a zoom-in view of the Ridgecrest DAS array, a nearby meteorological station (green triangle), and groundwater wells (green circles). The blue line and overlying red line represent the entire DAS cable and an 8-km DAS segment used in this study, respectively. The underlying street map is available from OpenStreetMap under the Open Database License (https://www.openstreetmap.org/copyright). c Record a section of weekly stacked seismic waveforms at 4.2 Hz from a virtual source (purple star) at a cable distance of 5.2 km. The blue waveform shows the seismogram received 60 channels away from the virtual source. d dv/v measurements (top panel) for the channel pair in (c). The bottom panel presents the temporal variation of direct surface waves. Vertical white strips are data gaps. Source data are provided as a Source Data file.