The damping of core waves

Attenuation in the core is examined by using spectral ratios of seismic core waves. In the outer core a Qα of 5000–10,000 is obtained from the amplitude radio P7KP/P4KP. From the PKIKP/PKP amplitude ratio, Qα in the inner core has a value between 120 and 400. An unusual result is that P7KP is consistently higher in frequency than P4KP, which may indicate frequency-dependent reflection and transmission coefficients at the mantle-core boundary for rays that nearly graze the core.