Earthquake Is Nuclear?

Magnetite density $Fe_3O_4$ = 5175 kgm^-3

So,

$v_{boom\,\small{Fe_3O_4}}=3.4354*\cfrac{5175}{3*26+4*8}=161.62\,ms^{-1}$  or  $581.83\,kmh^{-1}$

but the speed of sound in magnetite $v_{\small{sound}}$ = 5890 ms^-1

The ratio,

$\cfrac{v_{boom}}{v_{\small{sound}}}=\cfrac{161.62}{5890}=0.0274$

Sound does not trigger earthquakes.  Had the above ratio been an integer, earthquake could be triggered by sound reaching a magnetite layer causing it to collapse and changing its nature (post "Magnetite, Earthquake Crystals" dated 17 Aug 2017 and post "Magnetic Bonds And Stir" dated 17 Aug 2017).  Earthquake would be much more frequent until magnetite is sufficiently far and insulated from sound on the ground level.

If instead of $Fe_3O_4$ we have $Fe_6O_8$ as a nucleus unit,

$v_{boom\,\small{Fe_6O_8}}=3.4354*\cfrac{5175}{6*26+8*8}=80.81\,ms^{-1}$  or  $290.91\,kmh^{-1}$

What would travel through the crystal strata at $80.81\,ms^{-1}$ (or an integer multiple lower) and trigger a collapse?

Speed of lightning is quoted at about 335.28 ms^-1, which is still too high compared to either $v_{boom}$'s above.