@article{fdi:010094993,
  title = {{S}eafloor fibre optical cable repositioning using target motion analysis on distributed acoustic sensing of underwater acoustic noise},
  author = {{R}ivet, {D}. and {P}apotto, {L}. and de {C}acqueray, {B}. and {A}mpuero, {J}ean-{P}aul},
  editor = {},
  language = {{ENG}},
  abstract = {{D}istributed acoustic sensing ({DAS}) is a recent technology that turns optical fibres into multisensor arrays. {I}n the marine environment, it offers new possibilities for measuring seismic and environmental signals. {W}hile {DAS} can be applied to existing fibre optic cables used for communications, a major limitation of such efforts is that the position of the cable is not always known with sufficient accuracy. {I}n particular, for submarine telecommunication cables, the positioning accuracy decreases with increasing depth. {T}his problem affects the accuracy of earthquake locations and source parameters based on {DAS} signals. {T}his limitation calls for methods to retrieve the cable's position and orientation. {H}ere, we propose a method for relocating a linear section of cable-or multiple connected segments-using incidental acoustic sources, particularly boats moving in the vicinity of the cable. {T}he method is based on target motion analysis ({TMA}) for sources in uniform rectilinear motion. {W}e consider {B}earing-{O}nly {TMA} ({BO}-{TMA}) and the {B}earing and {F}requency {TMA} ({BF}-{TMA}), which respectively use changes in backazimuth (called bearing in navigation) and changes in both backazimuth and {D}oppler frequency shift as the source moves. {W}e adapt these methods to the 3-{D} case to account for the difference in depth between the fibre and the sources. {B}oth cases lead to a nonlinear inverse problem, which we solve by the {L}evenberg-{M}arquardt method. {O}n synthetic data, we test both {TMA} techniques on single and multiple source trajectories and evaluate their accuracy as a function of source trajectory and velocity. {W}e then test the {BO}-{TMA} on real {DAS} recordings of acoustic signals produced by passing ships near a 42 km-long fibre optic cable off the coast of {T}oulon, southeastern {F}rance. {I}n this study case, the position and characteristics of the acoustic source are known. {W}hile the {D}oppler frequency shift at low frequency (30 {H}z) is difficult to measure with sufficient accuracy (< 0 . 1 degrees), we demonstrate that effective cable location can be achieved by {BO}-{TMA} using multiple ship passages with a variety of trajectories. {O}nce the linear sections of the cable have been relocated, the stage is set to reconstruct the entire cable configuration. {M}ore generally, the 3-{D} {TMA} on linear antennas developed here can be used to locate either the sources or the antenna situated at different depths.},
  keywords = {{I}nverse theory ; {A}coustic emission ; {D}istributed acoustic sensing ; {FRANCE} ; {MEDITERRANEE}},
  booktitle = {},
  journal = {{G}eophysical {J}ournal {I}nternational},
  volume = {243},
  numero = {2},
  pages = {ggaf339 [15 ]},
  ISSN = {0956-540{X}},
  year = {2025},
  DOI = {10.1093/gji/ggaf339},
  URL = {https://www.documentation.ird.fr/hor/fdi:010094993},
}