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Types of Stress that cause Earthquakes. Chapter 8. What is an Earthquake?. An Earthquake is the vibrations produced when a rock snaps and breaks under different types of stress. Types of Stress. Tensional – pulls rocks APART Compressional – pushes rocks TOGETHER
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Types of Stress that cause Earthquakes Chapter 8
What is an Earthquake? • An Earthquake is the vibrations produced when a rock snaps and breaks under different types of stress.
Types of Stress • Tensional – pulls rocks APART • Compressional – pushes rocks TOGETHER • Shearing – pulls rocks ALONG each other https://www.as.uky.edu/sites/default/files/elearning/module10swf.swf
The Elastic Rebound Theory • Rocks will bend until they reach their Elastic Limit. • Then they will break (crack) • This forms a Fault
How do Earthquakes Occur? • Rocks on a fault are jagged & get stuck when plates move. • Stress Builds • Rocks bend until they can’t & then snap back to their original position. (Elastic Rebound Theory)
Parts of a Fault Footwall Hanging Wall
Rocks/plates are pulled apart Tension causes the hanging wall to fall down. Divergent Boundary Caused by Tensional Stress
Caused by Compressional Stress • Rocks/plates are pushed together. • Causes the Hanging wall to move up. • Earthquakes!!!! • Convergent Boundary
Thrust Fault • A special Reverse fault • Angle of fault plane is shallow.
Caused by Shearing Stress • Rock/plates are sliding in opposite directions. • Movement is only horizontal. • EARTHQUAKES!!! • Transform Boundary
Oblique-Slip Fault • Horizontal and Vertical Movement • Caused by Tensional and Shear Stress. • Transform and Divergent Boundaries