The deal with the Richter scale is it uses calculations to figure out how big “seismic waves” are.  There’s another scale called the Modified Mercalli Scale, which determines the effects on people.  It’s pretty much a way of describing the effects of an earthquake with as few words as possible, because “an X on the Modified Mercalli Scale” is sooo much easier than “da’guum! That there was a big’un!”

Also, it’s not like it caps out at 8. In 1960, a 9.5 magnitude earthquake hit Chili, for example.