• Tidal wave is the common name for a tsunami.
• Tsunami is a Japanese word meaning 'harbour wave'.
• A tsunami is a large ocean wave usually caused by an underwater earthquake or a volcanic explosion.
• Tidal waves aren’t really waves.
• They are ocean surface waves (wind waves) that move higher onto the shore because of the gravity of the moon.
• The Earth’s gravity helps us to stay on the Earth and not float up into space.
• The moon’s gravity pulls on the Earth’s water.
• When the moon is close to one side of the Earth, it pulls the water in the ocean towards it.
• When the water moves toward the moon, the ocean gets fuller on that side and move higher up on the beach bringing the waves closer to you. This is called high tide.
• When the water moves towards one part of the ocean, another part gets emptier and the waves don’t come as close to the shore. This is called low tide.
• On the side of the earth opposite the moon, it is high tide too. This is because the spinning of the earth causes the water to rush towards the outside of the earth.
• Because of this, there are two high tides every day and two low tides every day.
Causes of Tidal Waves:
• Tidal waves are caused by the forces of the moon, sun, and planets upon the tides, as well as the wind as it moves over the water.
• With typical waves, water flows in circles, but with a tsunami, water flows straight.
• This is why tsunamis cause so much damage.