Plate movements
Many scientists have developed a theory called plate tectonics to explain how the Earth is formed. This theory tells us that the crust is not an unbroken shell but consist of plates, or huge slabs of rock, that move. These plates are floating on top of liquid rock just below the crust. They move, but often in different directions.
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| How it looks today |
What happened is that millions of years ago, continents moved apart because of the tectonic movements. This movement is called continental drift. These plates are still moving but they move so slowly that we don't feel it.
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| Pangaea |
Sometimes the plates spread, or pull away from each other. That type of tectonic action separated South America and Africa.
When the plates crash against each other, they can produce mountain ranges, like the Himalaya in South Asia.
When they crash but it is a continental plate and an ocean plate, the continental one goes up the ocean one and this will cause molten rock to build up (magma) then, magma can erupt from volcanoes.
Another movement can be when they slide each other because of the pressure, the result is an earthquake.
Earthquakes can be very damaging to both physical structures and human lives, they can destroy buildings, bridges and even break apart underground water. When an earthquake is undersea, it can cause huge waves called Tsunami, waves can reach as high as 98 ft. (30 m)
Also, when plates slide, this movement creates faults, or cracks. One of the most famous faults in the US is San Andreas Fault located in California.
Watch the following videos from links.
http://youtu.be/CtBXTvtFaCU (earhquake)
Volcano Eruption
Tsunami- Japan 2011
