In today's comments we watched NASA's website go (temporarily?) dark, talked about the off-screen deaths of our favorite characters, and learned the theory behind your pet's curious pre-earthquake behavior.
USGS geophysicist John Bellini joined us today for a Q&A on the inner life and effects of earthquakes, and shared with us this tidbit on why your cat may seem to sense an earthquake before you do:
The two main "flavors" of earthquake waves are P waves and S waves. P waves arrive first followed by the S waves. The most important aspects of P waves is that they travel very well through the body of the Earth while S waves travel well along the surface of the Earth. They both can be detected at the surface but the S waves tend to exhibit larger surface amplitudes than the P waves for shallow, damaging earthquakes. It its theorized that animals, being closer to the ground and more attuned to vibrations in general, (we humans have learned to ignore so much noise we create in our environments) have felt the lower amplitude P waves, which can come several seconds to many 10's of seconds before the S waves for large distant earthquakes. So of course this gets attributed to animals predicting them...in reality is seems they just sense them before people do. That said...In my experience, cats tend to be very unpredictable.
Cats: Unpredictable, but clever.
Image: Tony Campbell/ Shutterstock