Open AccessOn the visibility of the inner‐core shear wave phase PKJKP at long periods
Author(s) -
Shearer Peter M.,
Rychert Catherine A.,
Liu Qinya
Publication year - 2011
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.2011.05011.x
Subject(s) - seismogram , inner core , geology , classification of discontinuities , seismology , amplitude , attenuation , shear (geology) , mantle (geology) , geophysics , phase (matter) , seismic wave , earth model , geodesy , physics , optics , mathematics , mathematical analysis , petrology , quantum mechanics
SUMMARY 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.