FAULTS

1. FAULTS By: Andrea Jimeno Martinez 4ºA

2. Introduction : • Definition • Types of faultswithexamples • Normal fault • Reverse fault • Strike - Slip fault • Parts of a fault

3. Definition: • A fault is a planar fracture or discontinuity in a volume of rock, across which there has been significant displacement along the fractures as a result of earth movement. Large faults within the Earth's crust result from the action of tectonic forces. Energy release associated with rapid movement on active faults is the cause of most earthquakes.

4. Types of faults • Normal fault (slide) • Reverse fault (jump) • Strik-slip

5. Normal fault A normal fault is a dip-slip fault in which the block above the fault has moved downward relative to the block below. The hanging wall has slipped down in comparison to the foot wall.  Gravity causes the hanging wall to slip down. Normal Faults are from layers being pulled apart. 

6. Examples Normal faults generally occur in places where the lithosphere is being stretched. Consequently they are the chief structural components of many sedimentary rift basins where they have major significance for hydrocarbon exploration. E.g. the North Sea.

7. Reverse fault A reverse fault is a dip-slip fault in which the upper block, above the fault plane, moves up and over the lower block. This type of faulting is common in areas of compression, such as regions where one plate is being sub ducted under another. The hanging wall has slipped up in comparison to the foot wall. When layers are pushed together this is the kind of fault that occurs.

8. Examples  A reverse fault occurs primarily across lithological units where as a thrust usually occurs within or at a low angle to lithological units. It is often hard to recognize thrusts because their deformation and dislocation can be difficult to detect when they occur within the same rocks without appreciable offset of lithological contacts. The Sierra Madre fault zone of southern California is an example of reverse-fault.

9. Strike-slip fault A strike-slip fault is a fault on which the two blocks slide past one another. These faults are identified as either right-lateral or left lateral depending on whether the displacement of the far block is to the right or the left when viewed from either side.

10. Examples Transform faults within continental plates include some of the best known examples of strike-slip structures, such as the San Andreas Fault, the Dead Sea Transform, the North Anatolian Fault and the Alpine Fault. The San Andreas Fault in California is an example of a right lateral fault:

11. Parts of a fault

12. Summary

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