What to do if you're at the beach and there is a local earthquake
If you're at the beach in Hawaii and you feel a big earthquake, it didn't happen in California--it happened in Hawaii. If it was a small earthquake, you don't have to worry; those don't generate tsunamis. But if the quake was big enough that you have trouble standing up, that's big enough to produce a tsunami, and it's time to start running.
For earthquakes generated in Alaska, your warning will come from the Civil Defense sirens, and you will have time to evacuate in an orderly way. But for locally generated earthquakes, the earthquake itself is the warning. You have only a matter of minutes to get to higher ground. Don't worry about grabbing your swim fins and car and picnic basket--just get your family and start running as far inland and as high as you can go.
Two campers died at Halape in 1975 because they were caught near the shoreline during the magnitude 7.2 earthquake that generated a huge local tsunami.