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Seismic Detections of Small-Scale Heterogeneities in the Deep Earth

  • Sebastian Rost
  • Paul S. Earle
  • Peter M. Shearer
  • Daniel A. Frost
  • Neil D. Selby
Chapter
Part of the Springer Geophysics book series (SPRINGERGEOPHYS)

Abstract

We report the detection of coherent scattered energy related to the phase PKPPKP (PP′) 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.

Keywords

Seismic scattering Small-scale heterogeneity Mantle mixing Array seismology Core–mantle processes 

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Copyright information

© Springer International Publishing Switzerland 2015

Authors and Affiliations

  • Sebastian Rost
    • 1
  • Paul S. Earle
    • 2
  • Peter M. Shearer
    • 3
  • Daniel A. Frost
    • 1
  • Neil D. Selby
    • 4
  1. 1.Institute of Geophysics and Tectonics, School of Earth and EnvironmentUniversity of LeedsLeedsUK
  2. 2.United States Geological Survey, DFCDenverUSA
  3. 3.Institute of Geophysics and Planetary Physics, Scripps Institution of OceanographyUniversity of CaliforniaSan DiegoUSA
  4. 4.AWE BlacknestReadingUK

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