Earth's Central Density

Abstract

IN a paper to be published elsewhere, I have derived the ormula: where η is a measure of departure from chemical homogeneity at depth z in the Earth (here treated as spherically symmetrical); k, p and g denote the adiabatic incompressibility, pressure and intensity of gravitational attraction, and Φ is a function of the P and S seismic velocities. The index η is equal to unity where the Earth is chemically homogeneous, in accordance with a simpler formula¹ developed in 1949; η exceeds unity where the chemical composition is varying with the depth z. An important property of η is that it is equal to the ratio of the actual value of dρ/dz (where ρ denotes density) to the value dρ/dz would take if the composition were unvarying.