Spherical Harmonic Oscillation
The earth rings like a bell after a large earthquake occurs. Very long wavelength surface waves circle the globe and interfere constructively to set up harmonic oscillations. The shape of an oscillation is determined by the wavelength of the waves, and the frequency of the oscillation by the internal velocity structure. The images below show the family of oscillations with an angular order number of l = 3.
Click on one of the names to activate one of the oscillations.