FWIW, the Richter scale of magnitude is no longer used.
Richter only goes to 10. Seismologists believe a quake of greater than 10 magnitude is possible.
Moment magnitude is similar.
Thanks IB.
After studying a bit I can see where the Moment of Magnitude scale more accurately measures the quakes energy. The scales are similar but different. The MofM scale would more accurately measure Big Ones.