EGU2020-6620
https://doi.org/10.5194/egusphere-egu2020-6620
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Interpreting Coda Wave Decorrelation from ambient seismic noise interferometry, inputs from laboratory experiments

Eric Larose1, Romain Thery2, Odile Abraham2, and Antoine Guillemot
Eric Larose et al.
  • 1Université Grenoble Alpes & CNRS, ISTerre - GRENOBLE, France (eric.larose@univ-grenoble-alpes.fr)
  • 2IFSTTAR-GERS, Laboratoire Géophysique et Évaluation Non Destructive, Bouguenais, France

Seismic and ultrasonic waves are sometimes used to track fluid injections, propagation, infiltrations in complex material, including geological and civil engineered ones. In most cases, one use the acoustic velocity changes as a proxy for water content evolution. Here we propose to test an alternative seismic or acoustic observable: the waveform decorrelation. We use a sample of compacted millimetric sand as a model medium of highly porous multiple scattering materials. We fill iteratively the sample with water, and track changes in ultrasonic waveforms acquired for each water level. We take advantage of the high sensitivity of diffuse coda waves (late arrivals) to track small water elevation in the material. We demonstrate that in the mesoscopic regime where the wavelength, the grain size and the porosity are in the same order of magnitude, Coda Wave Decorrelation (waveform change) is more sensitive to fluid injection than Coda Wave Interferometry (apparent velocity change). This observation is crucial to interpret fluid infiltration in concrete with ultrasonic record changes, as well as fluid injection in volcanoes or snow melt infiltration in rocky glaciers. In these applications, Coda Wave Decorrelation might be an extremely interesting tool for damage assessment and alert systems [1].

 

[1] R. Thery, A. Guillemot, O. Abraham, E. Larose, Tracking fluids in multiple scattering and highly porous materials: toward applications in non-destructive testing and seismic monitoring, Ultrasonics, 102, 106019 (2019).

How to cite: Larose, E., Thery, R., Abraham, O., and Guillemot, A.: Interpreting Coda Wave Decorrelation from ambient seismic noise interferometry, inputs from laboratory experiments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6620, https://doi.org/10.5194/egusphere-egu2020-6620, 2020

Comments on the presentation

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Presentation version 1 – uploaded on 01 May 2020
  • CC1: Comment on EGU2020-6620, Alison Malcolm, 05 May 2020

    Nice presentation Eric!  Do you think that the decorrelation is more sensitive because it is not inducing a bulk velocity change?

    • AC2: Reply to CC1, Eric Larose, 05 May 2020

      Decorrelation is performed after removing the (slight) apparent relative velocity change.

      • AC3: Reply to AC2, Eric Larose, 05 May 2020

        there is more wave propagation path changes (structure) than wave traveltime changes (average velocity). This is what I understand from the data.

        • CC2: Reply to AC3, Alison Malcolm, 05 May 2020

          Makes sense!

  • CC3: Comment on EGU2020-6620, Michael Dietze, 05 May 2020

    Hi Eric, sorry was not able to join the Jitsi meeting today, due to known issues. But the uploaded material is really cool. Any way, it appears that both dv/v and decorrelation are linked to damage evolution.

    Question 1) do these two damage proxies trace the same properties/mechanisms in the rock? Or do we see two different mechanisms that simply evolve in a similar direction? 

    Question 2) does decorrelation, as it appears to be more sensitive, also scale with stress imposed to a rock, for example due to diurnal temperature changes or increased load? You may guess the application ;)

    • CC4: Reply to CC3, Michael Dietze, 05 May 2020

      Sorry, I mean not damage but liquid in my first sentence