Why Not A Tsunami?

I was explaining to my skeptical prepper sister that Sacramento was unlikely to experience a tsunami because we are so far inland, but my argument wasn't particularly convincing, since my house is only 24 feet above sea level.

This map suggests that tsunamis are unlikely to penetrate past the Highway 580 bridge at Martinez, but I'm still bothered, because the terrain farther inland is as flat as a pancake. Why not penetrate further? Nothing to stop an energetic tsunami. 

The only thing I can think is that the close confines of the Carquinez Straits imposes additional contraints and much friction on intrusive tsunamis. 

 Or at least I hope so.