Tsunami: Horror by Sea
The power of water is often underestimated
Tsunamis leave their signature
Watermarks and ancient fossilized trees obliterated high on an inland cliff in Greece show a time when the sea rose hundreds of feet and killed all vegetation.
Japanese history is full of stories about the ocean disappearing into the horizon and reappearing as a massive wall of water bent on destroying all who were in its terrible path.
Recent events have shown the world the power and destruction of tsunamis. Tsunamis are a frightening wave of ocean that wash away coastal communities in a violent flood that continues growing in volume until it seems the ocean should empty. Then the waves ebb back to the sea as though nothing happened.
How do tsunamis form? What makes them so powerful?
Building a wall of water
Deep under the sea the tectonic plates buckle, displacing tons of water. This displaced water rushes away from the buckling sea floor, taking more water with it as it builds speed and volume.
The deeper the water, the faster the water travels and the more water it carries. Tsunami waves travel up to 500 miles per hour after an earthquake of a 9.0 magnitude or more.
As a tsunami nears land, the front of the wave begins slowing as the water becomes shallower. The water at the back of the tsunami continues at high rates of speed. The faster moving water collides with the slower and the wave rises to make landfall.
Once on shore, the cycle continues as speeding water runs into the slow. This causes the wave to drive more water to shore and the deepening flood waters continue to run fast.
Contantly moving forces from below
The Earth's crust is a giant moving skin that, paired with gravity, holds land and water to Earth. The crust is broken into several sections that squeeze together and fight to move. One against the other, huge tectonic plates grind and push in opposite directions, as though in a hurry to get somewhere.
At times, one of the plates makes a mighty push and the crust buckles, forcing huge amounts of displaced water toward open seas and far away shores. This scenario plays out along subduction zones around the world.
The island of Japan is neighbor to one of the largest, and most active, subduction zones on Earth.
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The 2004 tsunami that killed more than 150,000 people worldwide, is the most destructive ever recorded by man.
The train of waves traveled 3,000 miles and caused destruction and death in 11 countries. It killed 400 people in Africa more than 7 hours after the initial quake and 3,000 miles from the epicenter.
The magnitude of the underwater earthquake, partnered with the depth and temperature of the water made conditions ideal for a wave larger and more destructive than any human could have imagined.
A 600-mile long rupture under the Indian Ocean sent out 60-mile long waves. On the surface, the waves look like mild turbulence with the real destructive power riding underneath, gaining speed until shallow waters slow it down.
Early warning; the only warning
Science cannot predict earthquakes on land or on the ocean floor. The only predictor comes with the history of any given subduction zone.
Seismometers positioned throughout earthquake prone areas signal seismologists of quakes no one feels. From there, tsunami warnings go out to islands that may sit in the path of one of the giant waves.
This early warning system remains the only way to warn people of a potential tsunami.