I think the first suspicion was raised during the prelim to the construction of the Aswan High Dam. Checking for the depth of the bedrock, the engineers found that the Nile runs atop a filled-in gorge, not unlike many a river gorge in our own southwest. When the Mediterranean was mostly dry land, the Nile flowed into it at quite a bit lower elevation. After the Atlantic surged in, the seawater backed up into the gorge for many miles, probably helped fill it in, and the rest was contributed by the silt-bearing Nile flood. :')
from a November 30, 2006 article linked at the source; probably has already appeared as a topic on FR, but if not...
Maximum wave crests heights predicted by a computer simulation of the ancient event. Blue lines are arrival times of the first tsunami waves. Credit: AGU
Still images from a computer animation showing the spread of the tsunami waves triggered by the Mt. Etna avalanche 8,000 years ago. Credit: Instito Nazionale di Geofisica e Vuocanologia
