Which type of fault forms when the hanging wall rotates, the fault plane is curved, and the dip decreases with depth?

Which type of fault forms when the hanging wall rotates, the fault plane is curved, and the dip decreases with depth?

• A. Normal Fault
• B. Listric Normal Fault
• C. Thrust Fault
• D. Strike-slip Fault

Answer: (B)

When extension is accommodated by a curved fault surface, the hanging wall tends to rotate as slip accumulates. This creates a listric normal fault, which is a normal fault with a curved plane that dips more steeply near the surface and becomes shallower with depth. The hanging wall rotation comes from the geometry of the curved plane: as the block moves down along a progressively flattening surface, different parts of the hanging wall rotate relative to the footwall, producing the observed change in dip with depth. Because the fault plane is curved and the dip decreases with depth, this shape is characteristic of a listric normal fault. By contrast, thrust faults arise from compression with a low-angle, relatively flat plane, and strike-slip faults involve mostly horizontal motion with little vertical displacement, so they don’t show this curved, dipping-with-depth pattern.

When extension is accommodated by a curved fault surface, the hanging wall tends to rotate as slip accumulates. This creates a listric normal fault, which is a normal fault with a curved plane that dips more steeply near the surface and becomes shallower with depth. The hanging wall rotation comes from the geometry of the curved plane: as the block moves down along a progressively flattening surface, different parts of the hanging wall rotate relative to the footwall, producing the observed change in dip with depth. Because the fault plane is curved and the dip decreases with depth, this shape is characteristic of a listric normal fault. By contrast, thrust faults arise from compression with a low-angle, relatively flat plane, and strike-slip faults involve mostly horizontal motion with little vertical displacement, so they don’t show this curved, dipping-with-depth pattern.