The Porters Pass Fault is a right-lateral strike-slip fault in the foothills of the Southern Alps west of Christchurch, running for roughly 40 kilometres through the Canterbury high country. It forms part of the Porters Pass-Amberley Fault Zone, a belt of active faults marking the eastern frontier of alpine deformation.
The fault takes up part of the transfer of motion between the Alpine Fault and the wider plate boundary, accumulating strain at a slow but steady rate of a few millimetres per year. Its trace is visible as offset ridges and scarps across the mountainous terrain near the mountain road of Porters Pass itself.
Palaeoseismic studies show the Porters Pass Fault has produced large surface-rupturing earthquakes roughly every one to two thousand years, with the most recent event several centuries ago. Because it lies within striking distance of Christchurch, it is regarded as a significant long-term seismic hazard for the Canterbury region.