Acoustic noise contains valuable geophysical information

Dec 07, 2006

The proper processing of acoustic noise can provide a wealth of information. Geophysicists for example have used seismic background noise measurements to reconstruct the crustal structure under Southern California. The advantage of using existing acoustic noise is that signals only need to be recorded and not produced.

Researchers at TU Delft and the Colorado School of Mines have generalised the underlying theory and found that acoustic noise can be used for a much wider scale of physical applications than was previously thought possible. The researchers will publish their findings in Physical Review Letters on 8 December 2006.

As acoustic noise travels through a medium, such as the earth's crust, it compiles information. In recent years it was discovered that only a few simple processes (cross-correlation) were needed to extract a meaningful signal from acoustic noise. Geophysicists Kees Wapenaar and Evert Slob of TU Delft, and Roel Snieder of the Colorado School of Mines, have now developed a unified theory that extends the extraction of impulse responses from background noise for more general situations.

This theory includes electromagnetic noise in conducting media, acoustic noise in flowing and viscous media, and even diffusive transport phenomena. Moreover, the theory predicts that coupled processes, such as seismo-electric effect and the associated electrokinetic reflections, can also be retrieved from the background noise measurements.

It appears that background noise contains more information than one could possibly dream of several years ago. The theory can be used for 'remote sensing without a source' for a wide range of physical applications that include the determination of parameters of flowing media, viscous media, as well as the electrokinetic coupling parameters of porous reservoir rock. In partnership with Shell, the researchers have since created seismic reflection data from background noise that was recorded in a desert in the Middle East. Moreover, they expect their research methods to be applied in, for example, the LOFAR-project.

Source: Delft University of Technology

Explore further: Thermoelectric power plants could offer economically competitive renewable energy

add to favorites email to friend print save as pdf

Related Stories

Turning the tide for great white sharks

Oct 29, 2014

Spending up to 13 hours a day traversing shark-infested waters may be far from your notion of an ideal career. Not so for UConn alum Chris Perkins '12 (CLAS), co-founder and director of research for nonprofit ...

Scientific instruments of Rosetta's Philae lander

Sep 23, 2014

When traveling to far off lands, one packs carefully. What you carry must be comprehensive but not so much that it is a burden. And once you arrive, you must be prepared to do something extraordinary to make ...

Recommended for you

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.