Or you could detect it depending on the size. I have been on ships where we suddenly listed (in the middle of the ocean) for almost no apparent reason. I have also seen sea conditions were swells were regular but about a minute apart - very unusual.
The coast of California has the lowest level alert, but if I were on Pride of America in hawaii this right now I would be a little more concerned. The islands (Hawaii) have the highest level warning.
Pacific Coasts Facing Tsunami Warning, Watch and Advisories
In the aftermath of one of the strongest earthquakes in 100 years hitting Chile this morning, cruisers leaving from the West Coast on cruises to Mexico or elsewhere today may have a surprise in store.
The Pacific Tsunami Warning Center has issued a tsunami warning, watch and advisory for the entire Pacific Ocean, including Hawaii, California and even up through the Alaska coast. The three words represent different levels of severity.
The center has issued a tsunami "warning" (the highest alert) for Hawaii, where emergency response plans are already in place. Tourists in Waikiki and the Hilo International Airport have already been ordered to evacuate. The tsunami is expected to generate waves larger than any since 1964 throughout the islands.
The California coast received an advisory, the lowest level alert, but it still implies there should be strong waves and currents. However, officials said they do not expect "inundation." Cruise Ships can handle strong waves without any problem, but if you feel sea sick be sure to inquire at the passenger services desk for anti-nausea medication.