Thursday, January 27, 2011

Earthquakes around the world



Today, we were supposed to investigate the earthquakes around the world. The green lines show where eathquakes caused by compression occur. Compression is when the movement of tectonic plates causes the rocks to squeeze until they fold or break. As you can see, the compression earthuakes occur around the Euroasian and Philippine plate. There are also a bit of compression earthquakes around the Arabian plate. The orange/reddish lines represent tension. tension is a force that streches the rock, so that the rock becomes thinner in the middle. Earthquakes that cause tensions usually occur around the African plate, as well as the Indo-Australian plate. There is also a bit of earthquakes that cause tension around the Nazca plate (Pacific Ocean). The last type of stress that occurs due to earthquakes is shearing. Shearing is when the rocks push in two different directions. This can cause the rock to break, slip apart, or change it's shape. The earthquakes that cause shearing are usually cause some damage and are quite dangerous. Shearing does not occur often, and it does not occur in a lot of places. Shearing happens on the Western part of the United States, as well as a very small part of South America. Shearing also occurs in the Indian Ocean, near Australia.
From what I have researched, I can state that tension is the type of stress that occurs the most around the world. I think this because, since tension mostly happens in the Atlantic Ocean, and the Indian Ocean, it affects the lands that have shores on either sides of the oceans. That means that, if an earthquake causing tension happens in the middle of the Atlantic, it is most likely to affect both, Africa, as welll as South America. However, the most devastating earthquakes are the ones that cause compression. I have looked at the data we were given, and some of the most devastating earthquakes have happened around India, and the outline of South America.
Earthqaukes usually occur on tectonic boundaries, or fault lines.

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