Which type of fault movement is most closely linked to tsunami generation?

• A. Normal faults
• B. Reverse faults
• C. Strike-slip faults
• D. Oblique-slip faults

Answer: (B)

Tsunamis arise when the seafloor moves rapidly in the vertical direction, abruptly displacing a huge column of seawater. The movement most closely linked to this is uplift of the seabed along thrust or reverse faults, which occur in compressional settings such as subduction zones. In a reverse fault, the hanging wall moves up relative to the footwall, lifting the seafloor and pushing water upward and outward to generate a long, propagating wave.

Normal faults involve subsidence rather than uplift, and strike-slip faults mostly slide horizontally with little vertical displacement, while oblique-slip faults can have some vertical motion but not as consistently large as reverse faults. Megathrust earthquakes at subduction zones are classic tsunami sources, producing the most significant tsunamis.