[Publius]

With a large enough tsunami surge through the gulf of Mexico it might be possible. I doubt that much of California would go under in an earthquake.

Gulf of California.

One of Robert Heinlein's short stories, written during his pulp years, is about a tsunami sending the Gulf into the Imperial Valley and placing it all underwater.

[eldoradude]

Thank you gulf of Ca is correct! oops.

[WaltStuart]

The experts used to totally laugh at the idea that any significant part of California could “sink into the sea.”

Yet, when the Banda Acha tsunami killed so many thousands—and it was discovered that a part of the sea bed rose, in that case, as in a cliff face, say rose about 300-400’ in moments. The underwater pics afterwards were quite startling. That caused the tsunami.

Some folks willing to think outside the geologists’ orthodox cardinal doctrines box realized that just as dramatically, significant portions of the sea floor or on land could sink just that traumatically.