FAQ: What Is Normal Faulting?

normal fault – a dip-slip fault in which the block above the fault has moved downward relative to the block below. This type of faulting occurs in response to extension and is often observed in the Western United States Basin and Range Province and along oceanic ridge systems.

What is the explanation of normal fault?

Normal, or Dip-slip, faults are inclined fractures where the blocks have mostly shifted vertically. If the rock mass above an inclined fault moves down, the fault is termed normal, whereas if the rock above the fault moves up, the fault is termed a Reverse fault.

What is an example of a normal fault?

A normal fault is a fault in which the hanging wall moves down relative to the footwall. An example of a normal fault is the infamous San Andreas Fault in California. The opposite is a reverse fault, in which the hanging wall moves up instead of down.

What causes normal faulting?

A normal fault occurs when rocks break and move because they are being pulled apart. As the area is stretched, the rocks move along the fault. Each movement causes an earthquake. This model demonstrates how a block of rock is extended by a normal fault.

What is a normal fault called?

Normal faults, or extensional faults, are a type of dip-slip fault. They occur when the hanging wall drops down and the footwall drops down. Normal faults are the result of extension when tectonic plates move away from each other.

Which is the best description of normal fault?

noun Geology. a fault along an inclined plane in which the upper side or hanging wall appears to have moved downward with respect to the lower side or footwall (opposed to reverse fault).

Is a normal fault caused by compression?

Normal dip-slip faults are produced by vertical compression as Earth’s crust lengthens. The hanging wall slides down relative to the footwall. Normal faults are common; they bound many of the mountain ranges of the world and many of the rift valleys found along spreading margins of tectonic plates.

How do you identify a normal fault?

Strike-slip faults are vertical and thus do not have hanging walls or footwalls. If the hanging wall drops relative to the footwall, you have a normal fault. Normal faults occur in areas undergoing extension (stretching).

What are 3 types of faults?

There are three main types of fault which can cause earthquakes: normal, reverse (thrust) and strike-slip. Figure 1 shows the types of faults that can cause earthquakes. Figures 2 and 3 show the location of large earthquakes over the past few decades.

Do normal faults cause earthquakes?

Earthquakes occur on faults – strike-slip earthquakes occur on strike-slip faults, normal earthquakes occur on normal faults, and thrust earthquakes occur on thrust or reverse faults. When an earthquake occurs on one of these faults, the rock on one side of the fault slips with respect to the other.

Which stress is associated with normal fault?

Tensional stress, meaning rocks pulling apart from each other, creates a normal fault. With normal faults, the hanging wall and footwall are pulled apart from each other, and the hanging wall drops down relative to the footwall.

What does fault mean in earthquakes?

A fault is a fracture or zone of fractures between two blocks of rock. Faults allow the blocks to move relative to each other. This movement may occur rapidly, in the form of an earthquake – or may occur slowly, in the form of creep.

What stress causes normal faults?

Normal faults are produced by extensional stresses in which the maximum principal stress (rock overburden) is vertical. The faulting takes place at a point at depth when lithostatic pressure exceeds the rock strength and horizontal stress is reduced along an axis.

What is normal fault and reverse fault?

The main difference between normal fault and reverse fault is that normal fault describes the downward movement of one side of the fault with respect to the other side whereas reverse fault refers to the upward movement of one side of the fault with respect to the other side.

What are the types of faulting?

There are four types of faulting — normal, reverse, strike-slip, and oblique. A normal fault is one in which the rocks above the fault plane, or hanging wall, move down relative to the rocks below the fault plane, or footwall. A reverse fault is one in which the hanging wall moves up relative to the footwall.

What direction does a normal fault move?

In a normal fault, the hanging wall moves downward, relative to the footwall. A downthrown block between two normal faults dipping towards each other is a graben.