ASBOG Practice Exam

What tectonic environment do normal faults commonly characterize?

1. Compressional

2. Extensional

3. Transform

4. Isostatic

The correct answer is: Extensional

Normal faults are predominantly found in extensional tectonic environments, where the Earth's lithosphere is being pulled apart. This type of faulting occurs due to tectonic stress that stretches the crust, creating a situation where the hanging wall block moves down relative to the footwall block. In extensional settings, such as mid-ocean ridges or continental rift zones, the tension leads to the formation of large faults that accommodate the stretching of the crust. This is evident in regions where tectonic plates are diverging. In contrast, compressional environments typically feature reverse faults or thrust faults, where the crust is being pushed together. Transform environments, characterized by lateral movement of tectonic plates sliding past each other, involve strike-slip faults rather than normal faults. Lastly, isostatic adjustments relate to the balance of the Earth's crust and are not solely indicative of fault types. Therefore, normal faults serve as a key indicator of extensional stress within the geological context.