A fault that has moved recently or is likely to move in the future.

a fault that has moved recently and which is likely to again

A fault along which slip has occurred in recent geological time, or where earthquake foci are located.

A fault that is likely to have another earthquake sometime in the future. Faults are commonly considered to be active if they have moved one or more times in the last 10,000 years.

A fault along which slip has occurred, variously in historical, Holocene, or Quaternary time, or earthquake foci are located.

An active fault is a fault which has had displacement or seismic activity during the geologically recent period. In the United States, an active fault is generally defined as a fault which displaced earth materials during the Holocene Epoch (during the last 11,000 or so years before present). Active faults are the most common sources of earthquakes and tectonic movements.