I hope we are not talking UNscience fiction here:
"Between 1969 and 1977, seismometers installed on the Moon
by the Apollo missions recorded moonquakes. The Moon
was described as "ringing like a bell
" during some of those quakes, specifically the shallow ones. This phrase was brought to popular attention in March 1970, in an article in Popular Science." Google/Wiki
"The Hollow Moon concept is similar to the better-known Hollow Earth
hypothesis, which was a recurring plot device in pre-spaceflight science fiction
. The first discussion of a hollow Earth was by scientist Edmond Halley
in 1692, while the first publication to mention a hollow Moon was not until H. G. Wells'
1901 novel The First Men in the Moon
Apollo expeditions to the Moon 12.3:
"The best guess was that the Moon was composed of rubble a lot deeper below its surface than anybody had assumed. The internal structure, being fractured instead of a solid mass, could bounce the seismic energy from piece to piece for quite a while."
This effect is also known on Earth:
"Seismic waves from the biggest earthquakes
(over magnitude 8.3) can bounce around inside the earth for
up to a month. This makes the earth
". However, you need special instruments to hear the ring
because the tone is very low — about 1 cycle per hour." Wiki
Maybe geologists/seismologists have a different perspective on the word ring. Perhaps a synonym for vibrate - even at low frequencies. Sorry if this is bad news for any "hollow Earth" watchers.