What Causes Tidal Waves?
A tidal wave is a regularly reoccurring shallow water wave caused by effects of the gravitational interactions between the Sun, Moon, and Earth on the ocean. The term “tidal wave” is often used to refer to tsunamis; however, this reference is incorrect as tsunamis have nothing to do with tides.
A bulge also develops on the side of Earth opposite of the moon. Since Earth makes a complete rotation every 24 hours, one part of Earth is under a bulge at any given time, experiencing high tide every 6 1/2 hours. Semidiurnal tides are two high tides and two low tides each day.
A diurnal tide is one low tide and one high tide per day. During full moons and new moons, the sun, moon and Earth are lined up, and Earth experiences higher high tides and lower low tides. Called spring tides and neap tides, these occur twice a month.
Shore-based water-level gauges track tidal movements. These networks track tidal movements of certain locations to help determine future levels of low and high tides and when they will occur. The highest tidal range in the world happens in the Bay of Fundy in Nova Scotia, Canada. Ranging from 11 feet to 53 feet, these tides have created enormous cliffs through erosion.
Not all waves are caused by wind. The biggest waves are caused by disturbances under the sea. These huge waves are called “tsunami,” or tidal waves. Earthquakes and volcanic eruptions often shake the ocean floor. The jolt starts a huge wave moving rapidly across the sea.
When a tidal wave approaches land, the first sign is a fall in the sea level, as if it were very low tide. A big area of the ocean floor near the shore may be exposed. Then the big wave comes crashing in! The water can burst over the land, smashing houses and other things in its way.