An Earth Model Based on a Compressibility-Pressure Hypothesis

An Earth model, based on the compressibility-pressure hypothesis earlier put forward by the writer, is constructed. In this model there is a sharp density increase from 3.36 to 3.57 g./cm.3 at a depth of 80 km., and thereafter a fairly steady density gradient down to a depth of 2700 km.; the gradient increases sharply in the next 200 km., the density being 5.57 g./cm.3 at the base of the mantle. The density inside the central core ranges from 9.74 g./cm.2 to 12.00 g./cm.3 at a depth of 4980 km. and then rises sharply, reaching a value between 17 and 18 g./cm.2 at the centre. Seismic S waves would be transmitted through the inner core at speeds close to 5.0 km./sec. The distributions of the pressure p and certain other properties are shown in tables, and an equation is given connecting p and the incompressibility k for pressures between 0.4 and 3.2 × 1012dynes/cm.2. Various uncertainties are discussed, and also the relation of the new model to an earlier model.