Verified answer

Catastrophic plate tectonics says that all ocean floor should be essentially the same age. There is a lot of evidence that this is not true. Both radiometric dating and amounts of sedimentation indicate that the age changes gradually, from brand new to tens of millions of years old.

Island chains, such as the Hawaiian islands, indicate that the ocean floor moved slowly over erupting "hot spots." Radiometric dating and relative amounts of erosion both indicate that the older islands are very much older, not close to the same age as catastrophic tectonics would require.

As sea-floor basalt cools, it becomes denser and sinks. The elevation of sea floors is consistent with cooling appropriate for its age, assuming gradual spreading.

Seamounts, or guyots, are flat-topped underwater mountains. The tops were eroded flat from a long time at the ocean surface, and they sank with the sea floor. Catastrophic tectonics does not allow enough time for the sea mountain to form, erode, and sink.

Runaway subduction does not account for continent-continent collisions, such as between India and the Eurasian plate.

Catastrophic plate tectonics has no plausible mechanism. In particular, the greatly lowered viscosity of the mantle, the rapid magnetic reversals, and the sudden cooling of the ocean floor afterwards cannot be explained under conventional physics. Conventional plate tectonics accounts for the evidence already and does a much better job of it.

As the many telling points in Keith P's excellent answer explain, any scenario of a rapid worldwide flood is total B.S.

You just can't start with the assumption that a gigantic worldwide flood happened and then selectively try to fit evidence to it, leaving out all the gigantic mass of evidence that proves that it didnt happen. These ideas are not taken seriously by geophysicists and they never will be until the proponents agree to try to explain ALL the evidence and not just a few facts that can be twisted and distorted to fit preconceived notions....