Fault zones are areas of the earth’s crust that are under stress and subject to movement. Earthquakes happen when two plates collide and rub against each other. The force of the collision creates an earthquake. A fault zone is a place where the rocks on either side of the fault have been broken and moved. The size of the fault zone depends on how much movement has taken place.
Most faults occur at depths less than 20 kilometers, although some extend to depths of more than 60 kilometers. The vast majority of earthquakes happen along faults that are less than 10 kilometers deep. Faults can be very large, however, such as the San Andreas Fault in California, which is more than 1,000 kilometers long.
Earthquakes happen when plates move and grind against each other. The force of the collision creates an earthquake. Most earthquakes happen along faults that are less than 10 kilometers deep.