You can go back in time and prevent a great catastrophe. Which one would you prevent?

Hmmmm. i think if i could prevent a disaster, et al, I would have prevented Mt. Vesuvius from erupting and destroying Pompii. The beauty and history of the period makes me weep.

None, we always think that all bad things have no good to come of it, but there is always a positive side to a negative event, for example, without many machines that were used for torture, there wouldn't be A LOT of things that would have not been invented.

You can go back in time and prevent a great catastrophe. Which one would you prevent?

The Gulf of Mexico

I'd stop...whoever said I could only stop one, then I'd go back again and stop them all.
Seriously though, I'd go for stopping the Wall Street Crash.

How would you do that? Go back to 1928 and tell everyone there was going to be a crash in 1929? That would cause panic and the crash would be pushed back to 1928!

I would prevent the dying out of dinosaurs. They would make cool movie props and the steaks off of an apatosaurus would feed a village for a long time.