十万个为什么·科学启蒙30篇（3）

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大地震后会有巨浪涌来

Undersea earthquakes shift the ocean floor suddenly and push huge water columns upward.
This energy travels fast across deep water, forming long, low waves you can’t easily spot.
Near shore, the wave slows down but grows taller as water gets shallower.
Tsunamis aren’t like normal beach waves — they arrive as walls of churning water instead of curls.
Coastal warning systems use seismometers and ocean buoys to detect early signs of trouble.
People near beaches learn evacuation routes and meet at high ground when alarms sound.
Even small tsunamis can knock over cars or sweep away docks and fishing boats.
After a tsunami, volunteers help clean up broken homes and share clean water and food.
Some islands plant mangrove trees along shores because roots slow down incoming waves.
Always listen to local alerts — a tsunami may come minutes or hours after the first tremor.