"Creationists require" is likely to be too broad a claim, but I've
certainly seen claims of great violence from the flood. Scott Huse, in the
second edition of The Collapse of Evolution, claims that the violence of
the flood explains why fossil logs tend not to have branches on them.
Modern logs often lack branches as well, one of many facts overlooked by
Huse. He also claimed that the posture of many fossils shows their terror
as the flood killed them. I think he is referring to the open jaw and
backwards-bent neck that is the normal result of death and decay in
vertebrates. This flood also somehow explains the detailed preservation of
delicate fossils.
All YEC claims that I have encountered about the source of water
for a global flood and the amount of the geologic record formed during it
require a lot of violence. If the claim is made that most of the geologic
column was deposited during the flood, then a lot of plate motion,
volcanos, earthquakes, meteorite impacts, and other energy-releasing events
had to occur within a very short time. The laws of physics require that
something must happen to that energy. For example, Earth's plates would
have to move at over 45 miles per hour and change direction several times.
The energy powering this motion would produce lots of heat, the friction
would produce lots of heat, collisions would produce lots of heat, and the
motion of underwater continents in different directions would produce large
waves if the water had not boiled off yet. Thus, there is an indirect
claim for more violence than the ark could take.
David Campbell