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Volcanoes and Earthquakes

 

courtesy of Professor Dale Sawyer click on pic to link

Here is a picture of where the most actice Volcanoes are in different regions of the world. Most of the volcanos are on plate boundries and in clusters.

Magma is a molten mixture of rock forming substance, gases, and water vapor from the mantel. When magma coms to the surface, it is called lava. When lava cools down then it forms a solid rock. After a valcano erupts the lava comes and builds up the earths surface volcanic activity is a aconstructive force that adds new rock to land and then it forms a new island.

There are about 600 active volcanos on land and much more under water. Valcanoes occure in belts that extend across continents and oceans. The major volcanic belt is the Ring of Fire, which was formed by many volcanoes that rim the Pacific Ocean. Most volcanoes are along diverging plate boundaries.

Most volcanoes occure on islands near plate boundaries. The old and denser plates drives under teh other plates drives under the other plates creating deep ocean trench. Some volcanoes result from hotspots in the earths mantel. Hotspots normallylie in the middle of continental or oceanic plates plates fa away from the plate boundaries.

As magma rises twards the surface, its pressure decreases. The dissolved gases begin to separate which forms it to bubble. Durring a volcanic eruption, gases dissolved in magma rush out, carrying the magma with them. When the magma comes to the earth's surface and becomes lava, the gases bubble out.

courtesy of professor Dale Sawyer

Here is a picture of the eartquakes that happen around the world. We noticed most of them occur along plate boundries.
we have also notice that there is alot of volcanos in the same spots that is because of plate boundries

Because of friction plates cannot slide past each other easily they get stuck which builds up pressure when it slips loose or brakes it causes an earthquake.

When plates collide they hit at a side angle rather than head on that is why they get stuck and cause earth quakes if it hit head on it would make one plate go over and one plate go over.

Only the lithosphere has the stregth and brittle behavior to fracture in an earthquake.