How do tsunami waves grow so large after an undersea earthquake?
Quick Answer
A tsunami starts when the seafloor suddenly moves and pushes a huge column of water. In deep ocean it may be low and fast, but it grows taller and more dangerous as it reaches shallow coastal water.
The Full Story
A tsunami usually begins when a powerful undersea earthquake lifts or drops the seafloor. That movement displaces water above it and sends long waves racing across the ocean. In deep water, the wave height may be only a few tens of centimeters, but the wave can travel at jetliner speeds. As the wave enters shallow water, it slows down and piles up, sometimes reaching many meters high. The 2004 Indian Ocean tsunami was triggered by a magnitude 9.1 earthquake and caused catastrophic flooding across multiple countries.
Key Facts
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