Seismic Ambient Noise Interferometry along Optical Fibers: What Insights can Distributed Acoustic Sensing provide?

• Main Authors: Isken, M., Baird, A., Sens-Schönfelder, C., Sebastian, H., Dahm, T.
• Format: Conference Object
• Language: English
• Published: 2023
• Subjects: Iceland
• Online Access: https://gfzpublic.gfz-potsdam.de/pubman/item/item_5021864

We explore the ambient noise wave field recorded on different optical fibers interrogated during distributed acoustic sensing (DAS) campaigns in Iceland and Germany. DAS is a relatively new technology that allows for measurements of acoustic strain signals at densely spaced observation points along buried optical fibers. Ambient noise interferometry, in particular single-channel auto-correlation, is potentially a powerful technique for resolving the structure of the subsurface medium and characterizing its properties below a seismic sensor. Combining these two techniques to extract the ambient noise auto-correlation functions from horizontal strain rates all along the densely spaced locations on the fiber we obtain coherent signals that correlate over multiple observation points. We are challenged by the separation of the super-positioned non-stationary ambient noise field and the seismic response of the subsurface. We test our processing workflow and results against independent methods. (1) A controlled vibro-seis experiment and (2) seismic ambient noise analysis of a large-N three-component seismic nodal array which was co-located with the optical fiber in Iceland.