Tsunamis have nothing to do with the tides.
They are trains of enormous waves that travel for thousands of miles across the sea and still have enough energy to cause damage. Tsunamis are large waves generated by seismic sea waves or an earthquake near the shore. When the ocean floor moves it creates waves which are sent outwards from the ground motion. This usually happens in subduction zones, fault lines, or by volcanic eruptions. If an earthquake is detected in Hawaii and creates a tsunami, hours later it can reach Alaska or Japan with devastating results.