What's a Magnitude 15 Earthquakes Like?

Randall Munroe, of xkcd fame, has a new video series called What If? based on his books in which is gives "serious scientific answers to absurd hypothetical questions." Someone asked what an earthquake that measured 15 on the Richter scale would be like. The answer: pretty bad.

The thing to remember is that the Richter scale does not measure earthquakes in a constant series of units like, say, a yardstick measures in inches. It is a logarithmic scale, where each number is exponentially more powerful than the previous number. For example, a magnitude 5 earthquake is 100 times more powerful than a magnitude 3 quake. It's done this way to make the numbers more manageable, at least for those who understand the numbers. Most earthquakes we read about are between magnitude 5 and magnitude 9. Anything below that will barely make the news, and anything above the would disrupt communications. But I did not know that the Richter scale actually goes into the negative! (via Damn Interesting)