A fault line is an error in first-order logic resulting in Teutonic instability. Continental plates, while more expensive than regular plates, can better withstand the shifting and are thus often used when building planets. A few crackpot scientists believe these cause earthquakes, volcanoes, and that annoying "pizza-burn" on your plate when the cheese is too hot, but independent studies have failed to show any statistical meaningful correlation.
The line looks like this:
In reality, however, it is much smaller.