Exam 4 Review - H. Earthquakes and Earth's Interior Chapter...

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H. Earthquakes and Earth’s Interior Chapter 15 Def’n: Earthquake – vibrations (shaking or trembling) caused by the sudden release of energy, usually as a result of the displacement of rocks along faults. Def’n: Elastic Rebound – the mechanism by which energy is released during earthquakes. Def’n: Focus (hypocenter) – the point within Earth where fracturing begins, that is, the point at which energy is first released. Def’n: Epicenter – the point on Earth’s surface directly above the focus. Def’n: Seismology – the study of earthquakes Seismic Waves Def’n: a general term encompassing all waves generated by an earthquake. Types of Waves 1. Body – waves that travel through the solid body of the earth. a. P-waves (Primary) - Fast - Compressional (push-pull) - as the wave moves. - Travels through solid/liquid/gas b. S-waves (Secondary - somewhat slower than p-waves - shear waves. - Move material perpendicular to the direction of the wave travel. Produces shear stress in the material. - Travels through solid only 2. Surface Waves – waves that travel along the ground surface. Slower than body waves. In combination, these waves produce all the shaking, flexing, and damage of an earthquake.
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Measure size and strength of an earthquake Def’n: Intensity – a subjective measure of the kind of damage done as well as people’s reaction to it Most common intensity scale: Modified Mercalli Scale (Table 7.2) Def’n: Magnitude – the total amount of energy released by an earthquake at its source. Richter Magnitude Scale (Figure 7.17) Seismologist measure the maximum amplitude of the largest wave recorded on a seismograph (right-hand scale). The difference in arrival times of the P and S waves is plotted (left- hand scale). Connect these points, the center scale reading is the earthquake’s magnitude. Destructive Effects of Earthquakes 1. Ground shaking. Amount of damage that occurs depends on - magnitude - distance from epicenter - underlying geology (bedrock vs. unconsolidated or water-saturated sediment) - building construction and materials used 2. Fire – result of gas and electrical lines breaking 3. Tsunami – seismic sea wave The waves generated when large amounts of energy
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This note was uploaded on 04/16/2008 for the course GEOL 1403 taught by Professor Teague during the Spring '08 term at Tarrant County.

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Exam 4 Review - H. Earthquakes and Earth's Interior Chapter...

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