Imaging the Earth with Multiple Scattering Speckle

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This project focuses on the exploitation of multiple scattering of waves to make new inferences (statistical and deterministic) about earth materials, both in the laboratory and in the field. The project is a collaboration between the Physical Acoustics Laboratory and the Ultrafast Optics Laboratory at CSM and represents the first application of ultrafast optics to geophysics. New advances in laser technology (specifically mode-locked femtosecond lasers) mean that we can dramatically speed up our waveform data acquisition; so much so that "3D seismic surveys" (i.e., dense spatial measurement of particle motion time series) can potentially be done in real-time. The experiments involved in this project include both ultrasonic wave propagation in rocks, acoustic measurements in boreholes and surface measurements in field conditions. Key applications of these measurements include spatial fracture visualization in real-time, theability to unambiguously separate scattering attenuation from intrinsic attenuation as well as the retrieval of the effective Green's function of a random medium from multiple scattering speckle.