Suppose rocks were displaced 200km along a strike-slip fault during a period of 5 million years. What was the

Question

average rate of movement per year? Is the average likely to represent the actual rate of displacement on this fault? Please explain.

Answer 1

200km/5,000,000yrs=4cm/yr average

No, because the rocks don't have a smooth, planar, lubricated contact along the fault.  Stresses build up and are released when the rock fails.  When the stress is released, the rocks abruptly shift or move.