Sound propagation in solids...

[Externet]

Hello everyone...

Sound propagates in air at 340m/s by the sucessive compression/expansion of the highly compresible gas medium due to soundwaves;

¿ How do solids propagate sound with such diminished compressibility ?

 

¿ What is the typical range of sound progagation speed in plain soils ? Much faster ? And further ? and with less attenuation ?

¿ Are earthquakes detected by microphony or motion transducers or both ?

There was once a web site and group dedicated to sense underground noises, I would appreciate any clues to locate it.

Thanks,

Miguel