Lecture 7 (September 18)

Lecture 7 (September 18) - What is an earthquake? o Shaking...

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What is an earthquake? o Shaking from the passage of seismic waves Seismic waves are generated by sudden and very fast (km/sec) slippage of the rocks on either side of a fault past each other What is a fault? o A fracture across which the blocks on either side of fault move past each other Fault is a 3-dimensional plane, it is not a line What causes earthquakes? o They occur in response to stresses within the Earth’s surface Diagrams in Notebook o Fault trace Intersection line between fault plane and Earth’s surface o Fault strike Angle between fault trace and north o Dip Angle between horizontal down to plane Stress o Force = mass x acceleration o Stress is a force divided by the area over which that force is acting Force = Stress Area o Stress acts in 3D o Isotropic stress Stress that is the same in all directions e.g., pressure in water due to amount of water above o Stresses inside the Earth are always positive (compressional, aka pushing
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This note was uploaded on 01/27/2009 for the course GEOL 240Lxg taught by Professor 12:30-01:50pm during the Fall '07 term at USC.

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Lecture 7 (September 18) - What is an earthquake? o Shaking...

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