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How do normal faults differ from reverse faults?
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valley
The rugged Atlas Mountains surround a valley in Morocco.
Normal faults and reverse faults are distinguished primarily by the direction of movement of the hanging wall relative to the footwall and the tectonic forces that create them.12
- Normal Faults: These are caused by tensional forces that lengthen or extend the Earth's crust. In this process, the hanging wall slides downward relative to the footwall. Normal faults are frequently associated with the formation of rift valleys, where the downward-sliding hanging walls become the valley floors.123
- Reverse Faults: These are generated by horizontal compressional forces that cause the crust to shorten or contract. Consequently, the hanging wall is forced upward and over the footwall. When a reverse fault has a dip of less than 45°, it is classified as a thrust fault.14
While normal faults are primary components of divergent plate boundaries and rift systems, reverse faults are characteristic of compressive tectonic environments, such as subduction zones and mountain-building belts.12