Has ever been hit by a tsunami?
Crescent City, California was hit by a tsunami caused by the Good Friday Earthquake in Alaska back in 1964.
40 people were killed.
California gets many tsunami warnings a year, mostly when Japan has an earthquake. I have seen them on the local weather channel, and I feel that the next time they have to broadcast an alert there might be a different response than before.
The major thing with tsunami’s is that they can be anywhere from fractons of an inch high to 50, 100 feet high and there is no way to predict how high the tsunami will be.
So what I really think you are asking about is if any major tsunami has hit California. On Jan 26, 1700 there was a earthquake in the Cascadia subduction zone which caused a Tsunami as large as the recent INdian Ocean one. Scientists estimate it reached about 1 mile inland. Read more here