Dr. Henry Morris suggests a domino effect:

A. A secondary source of water is postulated, existing in vast subterranean reservoirs that were heated and pressurized in the earth’s mantle.

B. The actual trigger to unleash these stored waters may have been an earthquake.

C. This earthquake would not only allow the underground waters to surface through the fractured earth but would also result in immense amounts of dust blown skyward which would then initiate the condensation and precipitation of the water canopy.