Coda wave interferometry, a new method for monitoring change

Abstract

Multiply scattered waves are extremely sensitive to small changes of the medium through which these waves have propagated. Coda Wave Interferometry [Science 295, 2253–2255 (2002)] is a new technique that utilizes multiply scattered waves in the time domain to monitor small changes in media. This is applied to ultrasonic waves that were recorded in a granite sample that was subjected to a change in temperature. Velocity perturbations of about 0.1% can be detected with this technique with an accuracy of about 0.02%. A multiply scattered wave in an elastic medium has traveled part of its trajectory as a P-wave and part as an S-wave. A model for the equilibration of P- and S-waves is presented. This model is used to extend the theory of coda wave interferometry to include elastic wave propagation. [Work was partially supported by the NSF (EAR-0106668 and EAR-0111804), by the U.S. Army Research Office (DAAG55-98-1-0070), and by the sponsors of the Consortium Project on Seismic Inverse Methods for Complex Structures at the Center for Wave Phenomena.]

Robustness of computational time reversal imaging in media with elastic constant uncertainties

“…In all cases, the robustness of the TRP was extremely weakened by perturbations in the properties of the medium. Indeed, as proven by several studies in the field of coda wave interferometry, 31 multipathing in a medium increases the dependence of the wavefields on the medium structure, and a small change in the propagation medium implies a significant change in the signals recorded at a certain location due to the propagation. In the field of seismic imaging, this medium mismatch issue has been the object of an intense and thorough investigation.…”

MIIC: Monitoring and Imaging Based on Interferometric Concepts

“…A number of studies applied this technique to identify temporal changes in fault zones and volcanoes. Snieder et al (2002) presented some more theoretical consideration of this approach and coined the term Coda Wave Interferometry (CWI). Following this, CWI was applied to monitor velocity changes in the medium, movement of scatterers, and differences in source locations.…”

Locating a small change in a multiple scattering environment (LOCADIF): Application to monitoring concrete.

“…We observe that coda waves have decorrelated right after the hole was drilled. This feature is not new and forms the basis of original detection and characterization techniques 1,2,6,7,[11][12][13] .…”