The diagrams show what happens when P waves and S waves pass through the Earth. S waves do not pass through the Earth's core S waves cannot pass through the liquid outer core, but P waves can.

Because the atrial rate is so fast, and the action potentials produced are of such low amplitude, P waves will not be seen ... when an atrial action potential does reach the ventricles will ...

Just as in atrial fibrillation, not all of the P waves are able to conduct through the atrioventricular node, and thus the ventricular rate will not be as fast as the atrial rate. Typically ...