10_quakes_10_post

10_quakes_10_post - 10: Earthquakes & Earths I nterior...

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rthquakes: rthquakes: 1 Earth’s Interior Structure Fig. 10-29c: 1999 6.0 earthquake, Armenia; Photo: Reuters
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rthquakes: rthquakes: 2 Why this is important Earthquakes are a destructive, lethal natural hazard ( ~3.5 ~3.5 million deaths in last 2,000 years). million deaths in last 2,000 years). 2010 -- Haiti -- M7.0 -- 222,570 deaths (est.) 2010 -- Chile -- M8.8 -- 507 2008 -- China -- M7.9 -- 87,587 2005 -- Pakistan -- M7.6 -- 80,361 2004 -- Sumatra -- M9.1 -- 227,898 1989 -- Loma Prieta, CA -- M6.9 -- 65
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rthquakes: rthquakes: 3 Distribution of earthquakes defines plate boundaries Fig. 10.20 Fig. 10.20 Why this is important
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rthquakes: rthquakes: 4 Earthquake waves are somewhat like sonograms, allowing us to decipher internal structure of Earth Fig. D.10 Fig. D.10 Why this is important
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rthquakes: rthquakes: 5 What is an earthquake? Earth shaking produced by sudden release of energy, most commonly produced by movement along faults. Energy moves outward as an expanding sphere of waves Energy moves outward as an expanding sphere of waves
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rthquakes: rthquakes: 6 What causes earthquakes? Motion along new or existing faults Motion along new or existing faults Inflation / deflation of magma chamber Inflation / deflation of magma chamber Volcanic eruption Volcanic eruption Giant landslides Giant landslides Meteorite impacts Meteorite impacts Nuclear detonations Nuclear detonations
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rthquakes: rthquakes: 7 Elastic rebound theory : stress builds up, rock bends, reaches a critical value, and then breaks and moves suddenly while unbending Fig. 10.1 Fig. 10.1 What causes earthquakes along faults?
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rthquakes: rthquakes: 8 Stick-slip behavior Faults move in jumps. Faults move in jumps. Once motion starts, it quickly stops due to friction. Once motion starts, it quickly stops due to friction. Eventually, stress builds up again, causing failure. Eventually, stress builds up again, causing failure. Stick – friction prevents motion. Stick – friction prevents motion. Slip – friction briefly overwhelmed by motion. Slip – friction briefly overwhelmed by motion.
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rthquakes: rthquakes: 9 Focus (Hypocenter) : point of initial rupture or slip Epicenter : point on Earth’s surface above focus Fault-related earthquakes For large faults, entire fault surface does not slip at once; rather, smaller patches may slip at different times. Two slip patches (red) each have a focus and an epicenter; seismic waves only shown for earthquake A. Fig. 10.4 Fig. 10.4
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rthquakes: 10 10 Seismic waves Primary (P or push-pull) or compressional waves travel by alternately compressing and expanding rocks in the direction of propagation of the wave; similar to sound waves. Fig. 10.12
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This note was uploaded on 02/25/2012 for the course 460 100 taught by Professor Schlsche during the Spring '09 term at Rutgers.

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10_quakes_10_post - 10: Earthquakes & Earths I nterior...

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