Reverse fault

Definition

A reverse fault is a type of fault where the hanging wall moves upward relative to the footwall due to compressional forces acting on the crust. This upward movement occurs because rocks are pushed together, causing one block of rock to be forced over another. Reverse faults are important for understanding geological structures, as they often occur in mountain-building regions and can be identified in geologic maps and cross-sections.

5 Must Know Facts For Your Next Test

1. Reverse faults are typically found in regions where tectonic plates collide, such as at convergent boundaries.
2. They can create significant geological features like mountain ranges and uplifted blocks of crust.
3. The angle of a reverse fault is usually steep, which distinguishes it from thrust faults that have a more shallow dip.
4. Reverse faults play a crucial role in earthquake generation, as the built-up stress from compressional forces is released during seismic events.
5. Identifying reverse faults in geological maps can help geologists understand the tectonic history and structural evolution of an area.

Review Questions

• What geological processes lead to the formation of reverse faults, and how do they differ from normal faults?
  • Reverse faults form primarily due to compressional forces acting on the Earth's crust, causing the hanging wall to move upward relative to the footwall. In contrast, normal faults are formed under extensional forces where the hanging wall moves downward. The key difference lies in the direction of stress; reverse faults are indicative of convergent plate boundaries, while normal faults occur at divergent boundaries.
• How can reverse faults be recognized in geologic maps and cross-sections, and what features should one look for?
  • In geologic maps and cross-sections, reverse faults can be recognized by their steeply dipping fault planes and the juxtaposition of older rock layers over younger ones. Observers should look for signs of deformation such as folded rock layers or displaced strata that indicate movement along the fault. The presence of certain mineral deposits along the fault line may also suggest past seismic activity related to reverse faults.
• Evaluate the role of reverse faults in earthquake mechanisms and their significance in assessing seismic hazards.
  • Reverse faults play a critical role in earthquake mechanisms as they accumulate stress from compressional forces until it is suddenly released, resulting in seismic events. Understanding reverse faulting is essential for assessing seismic hazards because areas with active reverse faults may experience stronger earthquakes due to the high-energy release associated with their movement. Consequently, identifying these faults can help inform risk assessments and improve building codes in vulnerable regions.

Related terms

Thrust fault: A specific type of reverse fault that has a low-angle fault plane, where the hanging wall moves up and over the footwall.

Normal fault: A fault where the hanging wall moves downward relative to the footwall, typically caused by extensional forces.

Strike-slip fault: A type of fault where two blocks of rock slide past one another horizontally, often associated with shear stress.