Core Shadow Zone
Core Shadow Zone :
A gap in the emergence of P waves that have traveled directly through the Earth extending for short-period P waves from epicentral distances of about 103o to 114o. This gap or shadow of the core is caused by the sharp decrease in the P wave velocity at the core-mantle boundary. Note, however, that long-period mantle P waves may be diffracted around the curvature of that boundary, thus feeding mantle P-wave energy of strong earthquakes into this shadow beyond 140 (see diffracted P (Pdif), Figs. 11.59 and 11.63 of Chapter 11 in this Manual, and Kulhanek (2002, p. 340)
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