Fault Types to Know for Earthquake Engineering

Understanding fault types is essential in earthquake engineering. Each fault—normal, reverse, strike-slip, thrust, oblique-slip, transform, and dip-slip—affects how earthquakes occur and their potential impact on buildings and infrastructure, guiding engineers in creating safer designs.

1. Normal fault

   • Occurs when the crust is extended, causing the hanging wall to move down relative to the footwall.
   • Commonly found in regions experiencing tectonic plate divergence, such as mid-ocean ridges.
   • Associated with earthquakes that can be moderate to large in magnitude, impacting infrastructure and buildings.

2. Reverse fault

   • Formed when the crust is compressed, resulting in the hanging wall moving up relative to the footwall.
   • Typically found in convergent plate boundaries, where tectonic plates collide.
   • Can generate significant seismic activity, often leading to more destructive earthquakes.

3. Strike-slip fault

   • Characterized by horizontal movement of the fault blocks, with little to no vertical displacement.
   • Commonly associated with transform plate boundaries, where plates slide past each other.
   • Earthquakes can occur suddenly and may cause extensive damage to structures aligned with the fault.

4. Thrust fault

   • A type of reverse fault with a low-angle fault plane, causing the hanging wall to move over the footwall.
   • Often found in mountain ranges formed by continental collision, such as the Himalayas.
   • Can produce large earthquakes, posing significant risks to nearby communities and infrastructure.

5. Oblique-slip fault

   • Exhibits both vertical and horizontal movement, combining features of normal and strike-slip faults.
   • Typically occurs in complex tectonic settings where multiple forces act on the crust.
   • Earthquakes can vary in magnitude and impact, depending on the dominant movement direction.

6. Transform fault

   • A specific type of strike-slip fault that accommodates lateral movement between tectonic plates.
   • Often found along mid-ocean ridges and continental boundaries, playing a crucial role in plate tectonics.
   • Can generate powerful earthquakes, necessitating careful engineering considerations in affected areas.

7. Dip-slip fault

   • Involves vertical movement of the fault blocks, which can be either normal or reverse.
   • Important for understanding the mechanics of crustal deformation and earthquake generation.
   • Engineers must consider dip-slip faulting when designing structures in seismically active regions to ensure safety and resilience.