%0 Article %J Geophysical Journal International %D 2011 %T On the visibility of the inner-core shear wave phase PKJKP at long periods %A Shearer, Peter M. %A Rychert, Catherine A. %A Liu, Qinya %N 3 %P 1379-1383 %U https://doi.org/10.1111/j.1365-246X.2011.05011.x %V 185 %8 Jun %1 10.1111/j.1365-246X.2011.05011.x %K SPECEFEM3D_GLOBE %X Stacks of over 90 000 long-period seismograms recorded by the global seismic networks resolve many seismic phases but fail to detect the inner-core shear phase PKJKP. We compare these results to synthetic seismograms computed for PREM using the spectral-element method and show that expected PKJKP amplitudes are over 10 times smaller than signal-generated `noise' caused by high-order P surface multiples and reverberations from upper-mantle discontinuities. Indeed, PKJKP can only be seen in synthetic seismograms when differences are taken between two sets of synthetics generated from Earth models with slightly different inner-core shear velocities. These results suggest that routine observation of PKJKP is unlikely and that reported observations, if real, must have resulted from exceptional focusing effects or inner-core attenuation much less that current models.