CompuServe Messages

I saw your question and wanted to refer you to the definition for Richter magnitude I left under the topic "Richter Equation". I think it might give you a little insight. I think you are right to some extent about the TV "talking heads" but there are some other reasons for describing it the way we do. First the "Richter Scale" is a dimensionless ratio (very much like the decibel scale someone else mentioned) therefore it has no units. However, the Richter Scale has a very specific reference (see the Richter Equation message). There are also other measures of earthquakes that seismologists have used for a long time but the media doesn't grab ahold of. For instance, there is the "Modified Mercalli Scale" which is a precise way of describing the effects of an earthquake such as shaking, damage to structures, etc. Unfortunately Mercalli measures depend on the location of the observer and changes from place to place. Relating all of this to your question, since there are no units to the Richter scale and other scales exist you shouldn't just say an earthquake is a 6.6. If you want to be precise you should say it was a 6.6 of the Richter Scale.