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2015 | OriginalPaper | Buchkapitel

12. Seismic Detections of Small-Scale Heterogeneities in the Deep Earth

verfasst von : Sebastian Rost, Paul S. Earle, Peter M. Shearer, Daniel A. Frost, Neil D. Selby

Erschienen in: The Earth's Heterogeneous Mantle

Verlag: Springer International Publishing

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Abstract

We report the detection of coherent scattered energy related to the phase PKPPKP (P′P′) in the data of medium aperture arrays. The scattered energy (P′•P′) is weak and requires array processing techniques to extract the signal from the noise. The arrival time window of P′•P′ is mostly free from other interfering body wave energy and can be detected over a large distance range. P′•P′ has been detected in the data of large aperture arrays previously, but the detection in the data of smaller arrays shows its potential for the study of the small-scale structure of the Earth. Here, we show that P′•P′ can detect scattering off small-scale heterogeneities throughout the Earth’s mantle from crust to core making this one of the most versatile scattering probes available. We compare the results of P′•P′ to a related scattering probe (PK•KP). The detected energy is in agreement with stronger scattering, i.e., more heterogeneous structure, in the upper mantle and in an approximately 800-km-thick layer above the core–mantle boundary. Lateral variations in heterogeneity structure can also be detected through differences in scattered energy amplitude. We use an application of the F-statistic in the array processing allowing us a precise measurement of the incidence angles (slowness and backazimuth) of the scattered energy. The directivity information of the array data allows an accurate location of the scattering origin. The combination of high-resolution array processing and the scattering of P′•P′ as probe for small-scale heterogeneities throughout the Earth’s mantle will provide constraints on mantle convection, mantle structure, and mixing related to the subduction process.

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Titel: Seismic Detections of Small-Scale Heterogeneities in the Deep Earth
verfasst von: Sebastian Rost
Paul S. Earle
Peter M. Shearer
Daniel A. Frost
Neil D. Selby
Verlag: Springer International Publishing
Buch: The Earth's Heterogeneous Mantle
Print ISBN: 978-3-319-15626-2

Electronic ISBN: 978-3-319-15627-9

Copyright-Jahr: 2015
DOI: https://doi.org/10.1007/978-3-319-15627-9_12