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The Richter scale is used to measure earthquake strength. The Richter scale is logarithmic. The Richter scale is logarithmic.  7.0 is 10 times stronger.

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Presentation on theme: "The Richter scale is used to measure earthquake strength. The Richter scale is logarithmic. The Richter scale is logarithmic.  7.0 is 10 times stronger."— Presentation transcript:

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2 The Richter scale is used to measure earthquake strength. The Richter scale is logarithmic. The Richter scale is logarithmic.  7.0 is 10 times stronger than 6.0  8.0 is 10 times stronger than 7.0  etc… Therefore 8.0 is 100 times stronger than 6.0. Question:  An 8.0 earthquake on the Richter scale releases ___________ times as much energy as a 2.0 earthquake

3 HOW ARE THEY ALL RELATED?

4 Several pieces of evidence support the theory of plate tectonics: Africa and South America were once part of a larger continent (called Pangaea) Africa and South America were once part of a larger continent (called Pangaea)  note similarities in continental shape  note similarities in continental shape  presence of Mesosaurus fossils  presence of Mesosaurus fossils

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7 Earthquakes and volcanoes Earthquakes and volcanoes  occur along plate boundaries **(where one plate is moving relative to another)

8 ** Side note Volcanoes also occur above “hot spots” in the middle of lithospheric plates.  The hot spot remains in the same location while the plate above moves overtop

9 Magnetism and spreading centres Magnetism and spreading centres  as plates spread apart, new rock* is formed and older rock moves away from the spreading plate boundary * The rock crystallizes and records the magnetic field of the earth at that particular time

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11 Volcanoes 1. Composite volcanoes - this is the stereotypical volcano, erupting and belching smoke and ash everywhere,  found along converging plate boundaries  Layers of ash and thick lava (magma) form a tall cone.  As magma reaches the surface, it cools, hardens and traps gases below.  Pressure builds, eventually there is an eruption. See pages

12 1. Shield volcanoes - these are NOT found at plate boundaries, but instead form over hot spots (a weak spot in the normal lithosphere). Flash Animation Flash Animation Flash Animation  Thin magma/lava flows out from a hot spot and forms a low, wide cone.  The Hawaiian Islands are an example of a chain of shield volcanoes. 3. Rift eruptions - these occur along long cracks in the lithosphere  Not explosive, but release massive amounts of lava.  Found at diverging plate boundaries

13 Classwork: Chapter 12 Quiz Chapter 12 Quiz Chapter 12 Review Worksheet Chapter 12 Review WorksheetHomework: Workbook Pages Workbook Pages


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