Unless it happens at high tide....
Some of us were here on FR when the Japan earthquake struck and someone posted a link to live Japanese tv coverage. One station had an aircraft airborne over the coast when the tsunami rolled in and we watched it live as it rolled in over the land... And it rolled up the bays and rivers for I believe it was some 70 miles inland and we watched live here as people died trying to drive away from it... The more it rolled up the rivers the larger and thicker it go. It is not just people at the seashore who would die
Anyone without water for 3 days could be toast and beyond FEMA reach or help. A lot of urban and suburbanites have no idea how to fend for themselves