Displacement and velocity records of P and SH body waves with broadband frequency content from 0.01 to 5.0 Hz are obtained either directly or through multichannel deconvolution of earthquake waveforms from digitally recording stations of the Global Digital Seismographic Network, the Regional Seismic Test Network, and the Graefenberg array. Source parameters of a deep focus earthquake are determined by modeling P waveforms with a dynamically realistic source model and a model of Qα that is allowed to be frequency-dependent. Because the phase behavior predicted by intrinsic attenuation often contrasts sharply with that predicted by realistic rupture models, there are strong constraints on source and attenuation operators. Using the rupture model derived from the P waves and neglecting the effects of scattering, a search is made for the minimum phase operators required to obtain matches to the observed S waves.

The variation in the inferred minimum phase operator between S and ScS phases and its behavior with increasing distance and frequency are used to estimate a depth- and frequency-dependent model of intrinsic Qβ. Strong constraints on the frequency dependence of Qβ are given by fine details in the shape and dispersion of the broadband displacements of the S waves. Rise times are most sensitive to the higher end of the frequency band (0.2--1.0 Hz), while the pulse width and tail are sensitive to the lower end of the frequency band (0.01--0.2 Hz). Although the frequency dependence of the derived gβ* is quite simple, having smooth decreases from 0.01 to 5.0 Hz, a relatively complex parameterization of the frequency and depth dependence of Q is required to match this frequency dependence. Either the power n in a frequency-dependent Q=Cfn varies with depth, the high-frequency cutoff in the relaxation spectrum varies with depth, or both. The midmantle between depths of 400 and 1600 km contributes primarily to the attenuation of low frequencies (0.01--0.1 Hz) of body waves.

Below the mantle depth of 2000 km the P and S waveforms for the paths investigated suggest that little or no attenuation exists in the band of 0.01--5 Hz.