[Lmo56]

About 4,800 years ago, a large asteroid or comet impacted in the Indian Ocean, producing a tsunami at least 600 feet high. This may be the origin of the stories of both Gilgamesh and Noah.

Or possibly a glacial ice dam breaking up ???

Check this out:

http://www.glaciallakemissoula.org/

[Rockingham]

That seems to be a leading alternative. I am not sure though that it would produce in the Mideast the violent storms associated with Noah’s adventure.