Figure 3. Intake Port, Exhaust Port and In-cylinder Pressures with Poor Tuning. The timing of the arrival of the negative wave at the back (port) side of the exhaust valve is determined by the engine RPM, the speed of sound in the pipe and the distance from the valve to the relevant change in area.
Fault (geology) In geology, a fault is a planar fracture or discontinuity in a volume of rock, across which there has been significant displacement as a result of rock-mass movement.
Fault Zone. An area of rock that has numerous fractures of similar trend and dip. Rocks usually do not fail with a clean break, instead they fail through the formation of numerous fractures along a zone of failure. As a result, many named faults are actually zones of fractured rock. The term also has a regulatory use.