University of Cambridge > Talks.cam > Bullard Laboratories Wednesday Seminars > Characterizing global small-scale heterogeneity in the mantle – Interrogating the high-frequency, scattered seismic wavefield

Characterizing global small-scale heterogeneity in the mantle – Interrogating the high-frequency, scattered seismic wavefield

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The high-frequency seismic wavefield is dominated by extended codas trailing the ballistic arrivals. These codas mainly consist of scattered energy due to the interaction of the seismic wavefield with heterogeneities in velocity and/or density that are on the order of the seismic wavelength. Interrogating this energy provides additional information on Earth structure on small-scale lengths that is not assessible with many other seismic imaging techniques such as traveltime tomography.

Most of the scattered energy originates from shallow heterogeneities close to source or receiver and has been used to characterize heterogeneities in crust and lithosphere using the codas of direct P- and S-waves, but a few seismic probes exist that allow us to sample the heterogeneity structure of the deep Earth (e.g. PKP and PKKP ). Using statistical and deterministic approaches with different datasets I will present the present day resolved heterogeneity structure of the mantle from the core-mantle boundary to the upper mantle and lithosphere. I will make links between the distribution of the detected small-scale heterogeneities and mantle structures detected using other imaging techniques (e.g. tomography) and geodynamic models. Using the frequency dependence of the scattering process allows us to estimate the dominant scale-lengths of the heterogeneities and modelling of the seismic wavefield provides some insight into the heterogeneity structure.

This talk is part of the Bullard Laboratories Wednesday Seminars series.

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