I even heard that nine-point-something is pretty much the limit because the rock just can’t store enough energy to go beyond ten, resulting in earthquakes before it hits that mark.
However, if you got the energy into the system from outside, it’s very possible to cross that line. The dinosaur asteroid supposedly resulted in a quake up to 11 on the Richter scale.
So… Is it likely? No. But the scale doesn’t end at 10.