Gibralter did not collapse, the low land between Gibralter and Africa was overflooded and scoured away. While something severe appears to have happened regarding the Black Sea, the Persian Gulf is more likely, especially given that the Jews were taken away to Babylon around 500 bce, where stories from the Persian Gulf may have gone into their thinking and bible writing. Graham Hancock is a good source for theories on ruins found Underwater. Here is a very long link to various maps I promised to look for. It includes the map Fred Nerks kindly posted.
Morphology and structure of the Camarinal Sill from high-resolution bathymetry: evidence of fault zones in the Gibraltar Strait
The age of faulting is poorly constrained in both cases.LINK
Together with existing evidence of faults onland, the presence of these fault zones implies that they could be responsible for,
or have contributed to, the opening of the Gibraltar Strait.
gleeaikin: “Gibralter did not collapse, the low land between Gibralter and Africa was overflooded and scoured away.”
Granted, though what started as a slow trickle of Atlantic water ended as a mighty flood, eventually filling the Mediterranean in a matter of months.
Geologically, as sea & land levels rose & fell, bodies of water like the Mediterranean, Black Sea & Persian Gulf filled & dried up, apparently many times.
But the most recent filling of the Mediterranean was circa 5.3 million years ago, which makes it highly unlikely to have been the source for various Mesopotamian flood stories.
Both the Black Sea and Persian Gulf did, however, fill in historical times, and could easily be the origin, especially if filling corresponded to hurricane or monsoon level rains.