Detecting medium changes from coda by interferometry
Name
paper7_poliannikov_coda_2010.pdf
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1.61 MB
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Adobe PDF
Checksum (MD5)
26baa33a08890612a19f40516ab1fd1d
Author(s)
Poliannikov, Oleg V.
Malcolm, Alison E.
Date Issued
2010
Publisher
Massachusetts Institute of Technology. Earth Resources Laboratory
Series/Report no.
Earth Resources Laboratory Industry Consortia Annual Report;2010-07
Abstract
In many applications, sequestering CO[subscript 2] underground for example,
determining whether or not the medium has changed is
of primary importance, with secondary goals of locating and
quantifying that change. We consider an acoustic model of the
Earth as a sum of a smooth background velocity, isolated velocity
jumps and random small scale fluctuations. Although
the first two parts of the model can be determined precisely,
the random fluctuations are never known exactly and are thus
modeled as a realization of a random process with assumed
statistical properties. We exploit the so-called coda of multiply
scattered energy recorded in such models to monitor for
change and to localize and quantify that change, by examining
the shape and frequency content of correlations of the coda
produced by different parts in the medium. These ideas build
upon past work in time-reversal detection methods that have
often been limited to theoretical regimes in which the scales
of scattering and reflection are strictly separated. This results
in an application of time-reversal detection methods to non-theoretical
regimes in which the separation of scales is not
strictly satisfied, opening up the possibility, discussed here, of
using such techniques to monitor CO[subscript 2] sequestration sites for
leakage.
Subjects
Imaging
Interferometry
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