|Title||Scattered energy from a rough core-mantle boundary modeled by a Monte Carlo seismic particle method: Application to PKKP precursors|
|Publication Type||Journal Article|
|Year of Publication||2016|
|Authors||Mancinelli N., Shearer P.|
|Journal||Geophysical Research Letters|
|Type of Article||Article|
|Keywords||attenuation; boundary; core-mantle; deep earth; earths outer core; inhomogeneities; inner-core; interface topography; outer-core structure; scale heterogeneity; scattering; topography; travel-times; velocity structure; waves|
We stack a large global data set of 1Hz PKKP waveforms to constrain globally averaged properties of PKKP precursors. We find that the precursor observations are better explained by scattering from core-mantle boundary (CMB) topography than by scattering from the near surface, lower mantle, outer core, or inner core. However, as previously noted, simple models of CMB topography and standard 1-D seismic velocity models fail to model the range dependence of the relative amplitude between PKKPbc and its precursors. We find that this systematic mismatch is due, at least in part, to the assumed velocity gradient in the lowermost 250km of the outer core. Our globally averaged PKKP precursor observations are consistent with random CMB topography with RMS variations of approximate to 390m and a horizontal correlation length of approximate to 7km.