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plate tectonics - trench and arc of volcanoes or trench and...

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9/16/09 Overview of Plate Tectonics Nature of Plates Earth’s thin and brittle (5-50 km) solid crust and underlying uppermost mantle- what breaks during an earthquake. Plates move across more mobile part of mantle (asthenosphere) - it moves over time and the mantle can move and flow out. Most earthquakes and volcanoes at plate boundaries -Shallower earthquakes are more problematic because people feel the shaking Divergent Boundaries Plates pull apart- small, shallow earthquakes and new crust created- lithosphere is brittle Mid-ocean ridges are undersea ridges of active volcanoes such as Mid-Atlantic Ridge, East Pacific Rise (Saudi Arabia and Africa being pulled apart), Iceland Continental rifts such as East Africa Rift Convergent Boundaries Plates collide with one another Subduction: oceanic plate dives under a) oceanic or b) continental plate producing
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Unformatted text preview: trench and arc of volcanoes or trench and volcanic mountain range. The older colder denser plate gets pulled under. Continental collision: one continental plate collides with another, producing mountain range. An example would be Himalayan Mountains. All sizes of earthquakes but don’t go as deep as ocean ones. They are a mountain range without volcanoes.- All sizes of earthquakes including largest ever recorded. Earthquakes range from shallow to very deep. Oceanic crust is denser than continental crust. Example is Aleutian Islands and trench. Transform Fault Boundary Plates slip past one another: movement in the horizontal plane on vertical fault Short features on mid-ocean ridges of transform fault boundary’s Long continental transform (strike-slip) faults such as San Andreas Shallow earthquakes of all sizes No volcanoes...
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