Horst and graben are formed when normal faults of opposite dip occur in pairs with parallel strike, and are always formed together. Each feature can range in size from a few centimeters up to tens of kilometers, and the vertical displacement can be up to several thousand meters.
Horst and Graben (valley and range) refers to a type of topography created when the earth's crust is pulled apart. This process, called extension, can stretch the crust up to 100% of its original size.
horst and graben, elongate fault blocks of the Earth's crust that have been raised and lowered, respectively, relative to their surrounding areas as a direct effect of faulting.
Earthquakes occur on faults - strike-slip earthquakes occur on strike-slip faults, normal earthquakes occur on normal faults, and thrust earthquakes occur on reverse or thrust faults. When an earthquake occurs on one of these faults, the rock on one side of the fault slips with respect to the other.
In physical geography and geology, a horst is a raised fault block bounded by normal faults. Horsts are typically found together with grabens. While a horst lifted or remains stationary, the grabens on either side subside. This is often caused by extensional forces pulling apart the crust.
A horst is a raised block of the Earth's crust that has lifted or stayed stationary while the land around it (graben) has sunk. Horst and Graben are found together in an extensional environment. The graben is the block that has been downthrown, while the horst is the block that has been upthrown next to the graben.
Thrust faults occur when one section of land slips over another at a low angle when the land is compressed. Thrust faults do not usually show on the surface of the Earth. A reverse fault forms when two landmasses are being compressed together like a thrust fault.
A thrust fault is a reverse fault with a dip of 45° or less, a very low angle. This animation shows a reverse fault which is a steeper-angle fault, but it moves the same way.
A fault that has a component of dip-slip and a component of strike-slip movement is termed an oblique-slip fault. Nearly all faults will have some component of both dip-slip and strike-slip, so a fault that is classified as oblique requires both dip and strike components to be significant and measurable.
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.
Reverse fault—the block above the inclined fault moves up relative to the block below the fault. This fault motion is caused by compressional forces and results in shortening. A reverse fault is called a thrust fault if the dip of the fault plane is small. [Other names: reverse-slip fault or compressional fault.]
There are three main types of fault which can cause earthquakes: normal, reverse (thrust) and strike-slip.