Quote Originally Posted by NorrinRadd View Post
Someone -- maybe on The Weather Channel? -- said they're now technically viewing the 6.4 as a FORE-shock for the 7.1.

A bit of Googling suggests that because the magnitude scale is logarithmic, a 7.1 is over 5x as strong as a 6.4. (There's a somewhat more complicated calculation for comparing the energy released by each.)
Interesting. Even back when I was still in High School (oil lamps for lighting were just coming into vogue) it was known that after shocks could be stronger than the original earthquake.