4.1
11
Earthquakes occur Earthquakes occur along Faults along Faults http://neic.usgs.gov/neis/ http://neic.usgs.gov/neis/ qed/ qed/
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Transcript of 4.1
- 1. Earthquakes occur along Faults http://neic.usgs.gov/neis/qed/
2. Fault
- A fracture, or break, in Earths lithosphere, along which blocks of rock move past each other
3. Rocks bend as stress is put on them.
- Stress - the force exerted when an object presses on, pulls on, or pushes against another object.
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- Some parts of a fault, rock on either side may slide along slowly and constantly
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- Other parts the rocks may stick or lock together, putting stress on them
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- As stress increases, the rocks break free causing an earthquake
4. Earthquake
- Anearthquakeis a shaking of the ground caused by the sudden movement of large blocks of rock along a fault.
5. Most earthquakes occur along plate boundaries
- This is where faults occur.
- The blocks of rock that move during an earthquake are much smaller than the tectonic plates
6. Factors of the Strength of an Earthquake
- how much stress builds up before the rocks move.
- the distance the rocks move along the fault.
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- 80% of all earthquakes occur in abeltalong the edges of the Pacific Ocean
8. Fault Classification
- Faults are classified by the way the rocks move
- More than one type of fault may be present along a boundary
9. Normal Faults
- The block of rock above the fault plane slides down relative to the other block
- Earthquakes along normal faults are common near divergent boundaries.
10. Reverse Faults
- The block above the fault plane moves up relative to the other block.
- Occurs along convergent boundaires
11. Strike-Slip Faults
- Blocks of rock move sideways on either side on the of the fault plane.
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- Example: San Andreas fault in California