Normal fault

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A normal fault is classified as a type of dip-slip fault where the block above the fault slides downward when compared to the block below the fault.[1] The block above the fault is referred to as the hanging wall (if you're standing on the fault it "hangs" above your head), while the block below the fault is the foot wall (if you're standing on the fault your feet are on it).

Example of a normal fault in sandstone in Utah, USA. Note how the hanging wall has moved with respect to the foot wall. Image has been altered to show fault movement.[2]

Normal faults occur because of extensional forces that are "pulling apart" the surrounding area. To undo the motion, you would have to "push" the two fault blocks back together, essentially the opposite of extension.[3]

Following is a video from Incorporated Research Institutions for Seismology (IRIS) that shows how a normal fault moves:


Notable Normal Faults and Their Most Recent Earthquakes


References