Fig. 6
From: Ultra-low velocity zone heterogeneities at the core–mantle boundary from diffracted PKKPab waves
a Histogram of PKKPab diffraction ray parameters after ellipticity and mantle heterogeneity corrections. The seismograms are band-pass filtered between 0.9 and 2.1 Hz. The mean value of the ray parameters is 4.506 s/deg, and the standard deviation is 0.113 s/deg. The vertical black line denotes the theoretical ray parameter of PKKPab diffraction calculated for PREM. b, c same as a, but for the ray parameter distribution of PKKPab diffractions from 0.5–1.5 Hz and 0.5–2.1 Hz bands, respectively