Mon Prof Augmenté
Tsunami from Deep to Shallow
Age 14 · Physics
In the deep ocean, a tsunami wave moves fast but stays low and stretched out. As it reaches shallow coastal water, it slows down, bunches up, and rises into a tall wave.
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In the picture
- Low, broad crest in deep water: small height and wide spacing.
- Ship at the surface: it floats calmly while the long wave passes beneath.
- Upward-sloping seafloor: the water becomes shallower near the coast.
- Tall curling crest at the shore: the wave slows, shortens, and grows high.
Examples
- A long swell crossing the open sea after a distant undersea earthquake.
- A wave in a bathtub that rises when it reaches the shallow end.
Key takeaways
- Tsunami waves can cross deep ocean quickly while remaining barely noticeable at the surface.
- When the seafloor shallows, the same wave slows, compresses, and can rise into a destructive wall of water.
Quiz: Tsunami from Deep to Shallow (Age 14)
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In the deep ocean, how does a tsunami wave move?
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What is a tsunami wave like at the surface when it crosses the deep ocean?
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What happens to a tsunami wave when it enters shallow coastal water?
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