Shaking GroundA rumble so low it can't be heard

...

A rumble so low it can't be heard
A strange sensation in a word
Ripples along the earth that stirred
Glass begins to shake

Sometimes so soft you barely feel
A movement of earth that's quite unreal
Unless it's powerful with such zeal
It causes you to wake

Plates of the tectonic kind
Some shift around, a shocking grind
Shivers until they're re-aligned
The echo of the quake