Simulate motion along a transform fault with your hands. Press your palms together and move your hands in opposite directions, as shown in the figure. Notice that friction keeps them “locked” together...

Simulate motion along a transform fault with your hands. Press your palms together and move your hands in opposite directions, as shown in the figure. Notice that friction keeps them “locked” together until opposing forces no longer balance, friction no longer holds, and your palms slip suddenly past each other. This nicely models the sticking and slipping that occur along a transform fault.