Wobble Excitation by Earthquakes in Real Earth Models

Abstract

THERE have been several accounts recently^1–4 describing connexions between polar motion and earthquakes. Because a simple correlation is of little significance unless a physical mechanism can be produced to explain it, the most important point discussed in these articles is the question of the efficacy of the mass displacements associated with major earthquakes in exciting the observed polar motion. We wish to report here calculations based on realistic Earth models. The elasticity theory of dislocations⁵, used to model earthquake displacement fields, has been generalized to take account of self-gravitation, the radial variation of elastic properties, density and gravity, initial hydrostatic stress and the presence of the liquid core. We have already reported initial results, giving the effect of such realistic Earth model displacement fields on the rotation⁶. Results of a later independent study have been reported by Dahlen⁷ and our complete study will be published elsewhere⁸.