Do earthquakes happen in one smooth slide or in sudden jolts? Real faults store energy like a stretched rubber band. When the stress gets too high, the rock snaps forward. You drag a heavy brick along a wooden track using an elastic cord. Even though you pull at a steady speed, the brick jerks forward and stops over and over. A vibration sensor connected to a computer records each jolt on screen. This stop-and-go motion is called elastic rebound. It mimics how fault zones build up stress and release it in bursts that we feel as earthquakes.