Analysis of results of interpretation of elastic parameters of solid core of the Earth from the standpoint of current geomechanics
Keywords:Earth's core, high pressure, instability, elastic waves with actual velocity
It follows from the basic principles of mechanics of deformable solids relating to the strength, stability and propagation of elastic waves that the inner core of the Earth cannot exist in the form of a spherical structure in the assumed thermobaric conditions and calculation values of physico-mechanical parameters. Pressure level reaches a value that is significantly greater than the theoretical limit of medium strength in the model approximations at the surface of the sphere of the inner core. On the other hand, equilibrium state of the sphere is unstable by the geometric forming at much lower loads under the influence of the "dead" surface loads. In case of the action of "follower" loads, the assumed pressure value on the surface of the sphere is comparable with the value of the critical load of "internal" instability. In these cases, due to the instability of the equilibrium state, propagation of homogeneous deformations becomes uneven in the sphere. Moreover, the elastic waves with actual velocity cannot propagate in such conditions in solid medium. Violation of these fundamental conditions of mechanics needed in determining the physical and mechanical properties of the medium must be taken into account in the integrated interpretations of seismic and laboratory (experimental) data. In this situation, application of linear elasticity theory and elastic waves, despite compliance with the required integral conditions on the mass, moment of inertia and natural oscillations of the Earth, does not ensure the reliability of results on the structure and composition of the Earth's core.
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