Why do some faults produce huge earthquakes while others creep quietly?

Fault behaviour depends on rock properties, temperature, fluids, and the geometry of the fault plane. If a fault section is locked by friction, stress accumulates over time until it is released in a sudden earthquake. If the fault is weak or lubricated by fluids, it may creep steadily without producing large quakes. The San Andreas Fault in California has both locked segments and creeping sections, which is why it behaves differently along its length. This contrast helps geologists understand why some faults are much more dangerous than others.