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Earthquakes Plate movements cause large forces The rock breaks, and this break can sometimes be tens of kilometers long Faults are fractures in the.

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Presentation on theme: "Earthquakes Plate movements cause large forces The rock breaks, and this break can sometimes be tens of kilometers long Faults are fractures in the."— Presentation transcript:

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2 Earthquakes

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4 Plate movements cause large forces The rock breaks, and this break can sometimes be tens of kilometers long Faults are fractures in the Earth’s surface When the rocks break, the rocks on either side of the fracture plane slide past one another, until the forces are relieved Strong vibrations are produced and these are felt as an earthquake

5 Earthquakes Lots of the biggest earthquakes are along subduction zones (where the plate is sliding downwards) A transform fault is found at a transform boundary If the fault is locked for a long time, and suddenly slips, a major earthquake happens If the fault slips all the time, there are lots of minor earthquakes San Andreas Fault, in California, is a long transform fault; it is locked around San Francisco and around Los Angeles

6 Earthquakes

7 Volcanoes

8 a volcano is a place where molten rock, and also solid volcanic fragments and volcanic gases are erupted as the Earth’s surface Sometimes rock that is deep in the Earth is melted, to form magma Magma rises upward because it is less dense than the surrounding rock It does not always reach the surface before it turns to rock again If it does reach the surface, it forms a volcano

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11 Volcanoes Volcanoes erupt for different reasons How much gas is in the magma will effect its eruption As magma gets close to the surface, the pressure decreases, and gas bubbles out of the magma Magma with low gas content does not have violent explosions, unlike that with high gas content Large, explosive volcanoes are the most dangerous

12 Volcanoes Most big volcanoes occur along subduction zones Hot spot volcanoes are caused by a hot spot in the mantle that will continue to generate magma for a long time Hot spots don’t move, so a line of volcanoes will form as the plate moves. The way the volcanoes form shows the direction and speed that the plate moved Eg. Hawaiian Islands are hot spot volcanoes

13 Subduction Zones There are plenty of major earthquakes and volcanoes Most of the Pacific Oceans has subduction zones, and so we see the “Ring of Fire”

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15 Subduction Zone

16 Tsunami tsunami is a series of water waves caused by the displacement of a large volume of a body of water approximately 195 have been recorded in Japan immense volumes of water and energy are involved, so tsunamis can devastate coastal regions. Casualties can be high because the waves move faster than humans can run. Earthquakes, volcanic eruptions and other large distubances can cause tsunamis

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