Why can a long active fault affect more river basins than a short one?

Answer: Longer fault, wider damage zone

Longer fault, wider damage zone ✓ — Correct! A long active fault creates a wide damage halo of fractured rock that fades outward. This zone can overlap many river basins, making erosion easier over a large area. The key is that fault length controls the spatial extent of the weakened rock, not just the number of earthquakes.

Longer fault, more earthquakes — Wrong. While longer faults can produce larger earthquakes, the effect on river basins comes from the permanent damage zone around the fault, not from seismic shaking alone. The damage halo exists regardless of recent earthquakes.

Longer fault, older rock — Wrong. Rock age is not directly related to fault length. A long fault can cut through both young and old rocks. The key factor is the extent of the fractured zone, which scales with fault length.