How could the earth rings?
According to the current theory, The earth has from the outer edge to the inside part a silicate solid crust, a higly viscous mantle, a liquid outer core much less viscous than the mantle and finally a solid inner core. Then, how could it be possible that the earth displays regular and rhythmic oscillations after a large earthquake due to the bouncing of seismic waves?
After the Sumatra earth quake in 2004, the earth kept ringing for several months!
In order to hear the ring special instruments are needed because the tone is very low about 1 cycle per hour.
There is no deep science behind the fact that a confined medium filled with liquid and moreover with molten materials dampens harmonic oscillations...You can easily make the test by yourself especially with a crystal glass.
If you hit the crystal glass with a nail it will ring harmonously; if you fill it with water up to the rim, it won't ring at all! and the sound will obviously be dampened further if you fill the glass with a denser medium such as soil...