Observations of core‐mantle boundary Stoneley modes

Core‐mantle boundary (CMB) Stoneley modes represent a unique class of normal modes with extremely strong sensitivity to wave speed and density variations in the D” region. We measure splitting functions of eight CMB Stoneley modes using modal spectra from 93 events with M w > 7.4 between 1976 and 2011. The obtained splitting function maps correlate well with the predicted splitting calculated for S20RTS+Crust5.1 structure and the distribution of S diff and P diff travel time anomalies, suggesting that they are robust. We illustrate how our new CMB Stoneley mode splitting functions can be used to estimate density variations in the Earth's lowermost mantle. Key Points We present CMB Stoneley mode splitting function measurements The CMB Stoneley mode splitting correlates well with diffracted body wave data Our measurements allow to constrain density variations in the lowermost mantlePeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/99080/1/figS2_plot_prem_freq_Q_stoneley_paperrotated.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/99080/2/grl50514.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/99080/3/figS1_plot_coef_stoneley_paper_deg2_newrotated.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/99080/4/README_suppl_mat_GRL.pd