A tsunami refers to powerful and destructive waves. When the earthquake occurs at the bottom of the sea, forcing by shock waves, the sea water rises violently, forming powerful waves and flooding the coatal areas. This is called tsunami.
Tsunamis are usually caused by earthquakes at the bottom of the sea within 50 km of the ocean floor and on the magnitude of 6.5. The wave length of tsunami is larger than the ocean’s maximum depth and it doesn’t have much hindering at the bottom of the sea. No matter the depth of the sea, waves can always be transmitted.
The propagation speed in the ocean of tsunami is about 500~1000 kilometers and the distance between two waves may be as far as 500-650 kilometers. When the tsunami waves come into land, because the depth becomes shallow, the wave height increases suddenly. The ocean wave caused by this kind of motion can reach tens of meters, forming “water wall”.
This wall breaks the dam, floods the land and submerges towns, villages and fields in an overwhelming way. After that, the sea water suddenly exits and always pours in again. Sometimes it will happen several times, causing huge loss of life and property in the coastal area.
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