A Richter 9 is 1000 x more energy released than Richter 7.
However, the swing amplitude is only 100x bigger. People get confused on the distinction.
(energy ratio) = (amplitude ratio)^3/2
amplitude ratio is 10^(difference of the Richter readings).
No quake at Richter 10 ever happened and it is alleged to be planet destroying. It's only about 32x more energy than the Japan quake.