Structure, elastic and rheological properties and density of the earth's interior, gravity and pressure

Abstract

The elastic and anelastic properties of the earth are determined from the travel times and amplitudes of body waves and the periods and decay of normal modes. The periods of the normal modes also depend on density. The mass and moment of inertia provide additional constraints on the radial variation of density. The pressure and gravity as a function of radius are determined from the density by integration. In the presence of anelastic dispersion the seismic velocities and elastic moduli are frequency dependent. For seismic data which are sensitive to the upper 200 km of the mantle a better fit is achieved by assuming that this region is anisotropic. The viscosity of the mantle can be estimated from postglacial rebound and other considerations but is known only approximately and the effect of stress is uncertain. This chapter gives tables for the radial variation of the elastic constants, density, and seismic quality factor Q. Pressure and gravity throughout the earth are also tabulated. Q is the best known anelastic property of the earth but its variation with frequency is uncertain. In the present model the quality factors are assumed to be independent of frequency.

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