As far as I know, there's no such thing as quantum improbability. I think you must mean quantum uncertainty.
Quantum improbability is the stuff of science fiction. If you want to know about quantum improbability then read
The Hitchhiker's Guide to the Galaxy, but I don't think it has anyting to do with science.
Quantum uncertainty is a different beast from what your high school science teacher explained, and it has nothing to do with the probability of air molecules in the classroom suddenly moving in unison, which is a probabilistic/statistical issue. Quantum uncertainty says that we can't know both the momentum and position of an atomic or subatomic particle at the same time. The more precisely you measure the momentum the less precisely you can measure the position. And conversely, the more precisely you measure the position the less precisely you can measure the momentum.
Concerning mega-floods, if by "mega-flood" you mean a world wide flood, then there is no scientific evidence for any mega-flood ever, let alone multiple ones.
Concerning the possibility that many ancient catastrophes may have all happened at the same time, this is falsified by radiometric dating alone, not to mention simple stratigraphy.
--Percy