This type of secondary fault is set with opposite direction with respect to the primary fault.

This type of secondary fault is set with opposite direction with respect to the primary fault.

• A. Antithetic fault
• B. Synthetic fault
• C. Oblique fault
• D. Normal fault

Answer: (A)

When a main fault forms, secondary faults can develop with different dip directions. If a secondary fault dips in the opposite direction to the primary fault, it’s called an antithetic fault. This opposite dip helps accommodate the overall deformation by creating blocks that move in opposing senses relative to the main fault. This description matches an antithetic fault precisely because it defines the secondary fault by its opposite plunge direction compared to the primary one. A synthetic fault would dip the same way as the main fault, which isn’t what’s described. An oblique fault involves mixed slip components and isn’t defined by opposite dip relative to the primary. A normal fault describes vertical displacement due to extension, not the relationship between primary and secondary fault dips.

When a main fault forms, secondary faults can develop with different dip directions. If a secondary fault dips in the opposite direction to the primary fault, it’s called an antithetic fault. This opposite dip helps accommodate the overall deformation by creating blocks that move in opposing senses relative to the main fault.

This description matches an antithetic fault precisely because it defines the secondary fault by its opposite plunge direction compared to the primary one. A synthetic fault would dip the same way as the main fault, which isn’t what’s described. An oblique fault involves mixed slip components and isn’t defined by opposite dip relative to the primary. A normal fault describes vertical displacement due to extension, not the relationship between primary and secondary fault dips.