Actually, motion is one thing, power another: the multiplier for power is 30, not 10. So the 1940 quake was almost eight times more powerful than the 1986 one.

However, while I thought of the same as you, after some reading, the situation with the 1977 quake seems different, see my own reply to pereulok.

_{*Lunatic*, n.
One whose delusions are out of fashion.}