Mesoscopics of ultrasound and seismic waves: application to passive imaging

Abstract

This manuscript deals with different aspects of the propagation of acoustic and seismic waves in heterogeneous media, both simply and multiply scattering ones. After a short introduction on conventional imaging techniques, we describe two observations that demonstrate the presence of multiple scattering in seismic records: the equipartition principle, and the coherent backscattering effect (Chap. 2). Multiple scattering is related to the mesoscopic nature of seismic and acoustic waves, and is a strong limitation for conventional techniques like medical or seismic imaging. In the following part of the manuscript (Chaps. 3-5), we present an application of mesoscopic physics to acoustic and seismic waves: the principle of passive imaging. By correlating records of ambient noise or diffuse waves obtained at two passive sensors, it is possible to reconstruct the impulse response of the medium as if a source was placed at one sensor. This provides the opportunity of doing acoustics and seismology without a source. Several aspects of this technique are presented here, starting with theoretical considerations and numerical simulations (Chaps. 3, 4). Then we present experimental applications (Chap. 5) to ultrasound (passive tomography of a layered medium) and to seismic waves (passive imaging of California, and the Moon, with micro-seismic noise).

Generalized shot noise model for time-reversal in multiple-scattering media allowing for arbitrary inputs and windowing

“…These include biomedical engineering, 20 non-destructive testing and evaluation, 21,22 geophysics, [23][24][25] underwater acoustics, 26 imaging, 27,28 and ͑wireless͒ communication. [29][30][31] In many of these applications, one may be interested in sending not just a short pulse through the multiple-scattering medium but an extended pulse that could be used to contain extensive information or induce an effect.…”

Reconstruction of Rayleigh–Lamb dispersion spectrum based on noise obtained from an air-jet forcing

“…In the following, they are referred to as "active" experiments. Another idea has undergone a large development after the seminal experiments of Weaver and Lobkis (2001) (see for instance the review of Wapenaar and Fokkema (2006), Weaver and Lobkis (2006) or Larose (2006)). By cross-correlating the incoherent noise recorded by two passive sensors, Weaver and Lobkis demonstrated that one could reconstruct the impulse response of the medium as if a source was placed at one sensor.…”

Nonlinear reconstruction of bulk and shear moduli variations using the kazmarcz method

“…These results also demonstrate the morphology of reconstructed solid phantom geometrically correct. it can be inferred that this method may be used as an alternative for classical active seismic methods in order to reconstruct both interfaces between geological layers and velocity changes in each layer [27].…”