On the Detection Capabilities of Underwater Distributed Acoustic Sensing

作者：Itzhak Lior, Anthony Sladen, Diane Rivet, Jean‐Paul Ampuero, Yann Hello, Carlos Becerril, Hugo F. Martins, Patrick Lamare, Camille Jestin, Stavroula Tsagkli, C. Markou · 发表于：Journal of Geophysical Research Solid Earth · 年份：2021 · DOI：10.1029/2020jb020925 · 被引用次数：152 · 研究领域：Seismic Waves and Analysis、Seismology and Earthquake Studies、Geophysics and Sensor Technology

Abstract The novel technique of distributed acoustic sensing (DAS) holds great potential for underwater seismology by transforming standard telecommunication cables, such as those currently traversing various regions of the world’s oceans, into dense arrays of seismo‐acoustic sensors. To harness these measurements for seismic monitoring, the ability to record transient ground deformations is investigated by analyzing ambient noise, earthquakes, and their associated phase velocities, on DAS records from three dark fibers in the Mediterranean Sea. Recording quality varies dramatically along the fibers and is strongly correlated with the bathymetry and the apparent phase velocities of recorded waves. Apparent velocities are determined for several well‐recorded earthquakes and used to convert DAS S‐wave strain spectra to ground motion spectra. Excellent agreement is found between the spectra of nearby underwater and on‐land seismometers and DAS converted spectra, when the latter are corrected for site effects. Apparent velocities greatly affect the ability to detect seismic deformations: for the same ground motions, slower waves induce higher strains and thus are more favorably detected than fast waves. The effect of apparent velocity on the ability to detect seismic phases, quantified by expected signal‐to‐noise ratios, is investigated by comparing signal amplitudes predicted by an earthquake model to recorded noise levels. DAS detection capabilities on underwater fibers are fou...