>dogs and birds react before an earthquake Earthquakes have what are called primary (P) and secondary (S) waves. The primary is a sharp high frequency wave and

>dogs and birds react before an earthquake Earthquakes have what are called primary (P) and secondary (S) waves. The primary is a sharp high frequency wave and the secondary waves are a lower frequency rumble that you feel as the earthquake. The P wave propagates faster so if you're distant from the epicenter the P waves might arrive fractions of a minutes earlier. That's what you see in videos of dogs jumping up and running off or birds taking flight "right before" the earthquake.