Fault

noun

A crack in the Earth's crust where large pieces of rock have moved past each other. Most earthquakes happen along faults. Some faults are tiny; some run for thousands of kilometres.

Geotechnical Engineering — Cracker
Go Deeper For parents & teachers
A fracture in the lithosphere along which rock has moved relative to the rock on the other side. Faults are classified by motion: normal faults (hanging wall moves down — tensional), reverse or thrust faults (hanging wall moves up — compressional), and strike-slip faults (horizontal sliding, like the San Andreas). Earthquakes happen when stress accumulated along a locked fault is released suddenly; studying fault geometry and slip history is central to earthquake hazard assessment.

The Burning Mountain Chapter 3 — Trouble in the Ash

"… feed with the focus of someone already three steps ahead of the fault."