I get to shake and dance with mother earth about once a month.
IIRC 'Magnitude' or 'X on the Richter Scale' is used to measure the energy of the earthquake. How much you can actually feel depends upon (among many other factors) how deep or shallow and how far or close the seismic shift occured. A M6 tremor deep down 80km under the earth's surface and 200km away may not cause much damage, but the same energy definitely will, if it occured just 10km right under you.
The Meteorological Agency in Japan has a
Seismic Intensity Scale which indicates how much it shook on the spot and surface where we humans dwell.
The strongest I have experienced was '5 upper' a few months ago in Nigata. I was outside and was quite stunned when I heard a distant boom and
everything (including myself) started to sway in slow motion. The first thing I did was run towards and old man who was standing directly under heavy power lines strung between some posts and get him out of the way should they collapse. After that I just watched all the dead leaves shaken from the trees falling (it was November) in a state of stupor thinking, how pretty.
Do you have a scale similar to this elsewhere in the world??