Description	These animations were created to illustrate the free oscillations of the Earth. This doesn't require a very accurate model. The periods which are displayed in the captions come from real measurements. The model used for calculating the animations assumes that the Earth is made of an homogeneous isotropic material, i.e., that it is made of the same material everywhere. This is wrong. The mass density and sound speeds which were used are averaged values. The calculation can be reproduced with the calculator for an isotropic sphere. Other refinements (gravity, Coriolis, ...) were not taken into account either. Earth non-sphericity was introduced to partially lift the m degeneracy. The Earth map is from NASA. It is the 2002 Blue Marble and is in the public domain. The animations were computed using POV-Ray.
Date	2008
Source	commons.wikimedia.org
Author	Lucien Saviot

Earth free oscillation spheroidal mode n=0 l=5 m=1 bis

Summary