What is it?
Plate Tectonics is the theory that the lithosphere (outer layer of the Earth) is split into many parts (7 major plates, 9 minor plates, and over 20 micro plates!), and they are continuously moving around, due to convection cells movement in the layer below, called the mantle. This theory was created by Alfred Wegener, in 1912. The only problem there was no one believed him, but now that researchers have the evidence, the theory has been proven correct.
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The three Types of Plate Boundary Movement
There are three types of Plate Boundary Movement:
- Convergent
- Divergent
- Transform
ConvergentKnown for being one of the more destructive boundary movements (and what caused the Great Sendai Earthquake), a convergent boundary, is when two different plates move into one another. Whichever one is the least thick starts pushing itself downwards, while the other one pushes upwards, and any force used for it gets turned into things like earthquakes and tsunamis.
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Diagram of Convergent Plate Boundary |
Diagram of Divergent Plate Boundary |
DivergentA divergent boundary is where two plates move apart from one another. While these two plates split, magma starts to rise from inside the earth, whilst pushing the crust aside. There's an example of this located in Iceland, where two plates (North American and the Eurasian Plate) are moving away from one another
Example of Divergent Plate Boundary in Iceland |
So how does this all link up to the great sendai earthquake?
First, let's talk about why Japan is so prone to Earthquakes.
For starters, Japan is located within The Ring of Fire, where the worlds strongest earthquakes occur, like the 1960 earthquake in Valdivia, Chile, which has become the biggest earthquake ever recorded, with a magnitude of 9.5. It also caused a tsunami which wiped out some residents in places as far Hawaii, Japan and the Philippines!
The same thing happened with Japan. The earthquake, with a magnitude of 9.0, was caused by the converging of the North American Plate (which is 75 900 000 km2!) and the Pacific Plate, and occurred on the 11 of March, 2011. This caused many aftershocks, and a huge tsunami, which hit not only to Japan, but to other parts of the world too! |