The vadose zone is an unsaturated superficial layer of the subsurface that precipitation must typically pass through before it can reach groundwater. As a result, modifications to the physical properties of this shallow layer may modulate groundwater recharge and discharge, as well as affecting vegetation. In-depth investigation of the vadose zone is often limited by the paucity of instrumentation. A tool that may achieve this objective with high temporal and spatial resolution as well as extensive regional coverage is distributed acoustic sensing (DAS). By repurposing fiber-optic cables into seismic sensors with meter-spacing, DAS offers unprecedented spatial density for high-frequency wavefield recordings that are sensitive to water in the shallow layers. With ambient noise interferometry, we can track ~2% seismic velocity changes in the vadose zone, including the seasonal variation from thermal effects and the transient changes from soil moisture. The results highlight the potential of using seismic velocity changes to study soil moisture and its response to climate changes.
Session: Understanding Earth Systems with Fiber-optic Cables
Type: Oral
Date: 4/19/2023
Presentation Time: 10:45 AM (local time)
Presenting Author: Yan Yang
Student Presenter: Yes
Invited Presentation:
Authors
Yan Yang
Presenting Author
Corresponding Author
yanyang@caltech.edu
California Institute of Technology
Zhichao Shen
zhichao.shen@whoi.edu
Woods Hole Oceanographic Institution
Xiaojing Fu
rubyfu@caltech.edu
California Institute of Technology
Kyra Adams
kyra.kim@jpl.nasa.gov
Jet Propulsion Laboratory
Zhongwen Zhan
zwzhan@caltech.edu
California Institute of Technology
Fiber-Optic Monitoring of the Vadose Zone
Category
Understanding Earth Systems with Fiber-optic Cables