Strike-slip fault - a fault on which the two blocks slide past one another. The San Andreas Fault is an example of a right lateral fault.Ī left-lateral strike-slip fault is one on which the displacement of the far block is to the left when viewed from either side.Ī right-lateral strike-slip fault is one on which the displacement of the far block is to the right when viewed from either side. A right-lateral strike-slip fault is one on which the displacement of the far block is to the right when viewed from either side. An example of a dextral, right-lateral strike-slip fault is the San Andreas Fault, which denotes a transform boundary between the North American and Pacific plates. Finally, there are strike slip faults, which are faults that move sideways along a plane and are divided into two categories: left-lateral and right lateral, which are faults that shift to the. Reverse (thrust) fault - a dip-slip fault in which the upper block, above the fault plane, moves up and over the lower block. This type of faulting is common in areas of compression, such as regions where one plate is being subducted under another as in Japan. When the dip angle is shallow, a reverse fault is often described as a thrust fault. These right-lateral strike-slip faults are associated with the Alaskan subduction zone where the Pacific Plate subducts northwestward. 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. The following definitions are adapted from The Earth by Press and Siever. As opposed to the idealized linear movement of a strike-slip fault, the team demonstrated what geologists knew in theory, that shear strain has several stages before final movement along the fault.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. Faults may range in length from a few millimeters to thousands of kilometers. Most faults produce repeated displacements over geologic time. During an earthquake, the rock on one side of the fault suddenly slips with respect to the other. The fault surface can be horizontal or vertical or some arbitrary angle in between.Įarth scientists use the angle of the fault with respect to the surface (known as the dip) and the direction of slip along the fault to classify faults. Faults which move along the direction of the dip plane are dip-slip faults and described as either normal or reverse (thrust), depending on their motion. Faults which move horizontally are known as strike-slip faults and are classified as either right-lateral or left-lateral. Faults which show both dip-slip and strike-slip motion are known as oblique-slip faults. This is a similar trait we see in many systems on Earth, from rivers finding the easiest path to lower elevations to mammals taking the easiest path from point A to point B.Īs the faults propagate, the team measured how strain is transferred to different parts of the fault, a process that in real life takes millions of years and across many miles. The team found that the faults develop through a "Lazy Earth" hypothesis, whereby the fault propagation takes the easiest path.
In one boundary condition, there is a pre-existing fault along the two slabs, in another there is a pre-existing displacement beneath the clay slabs, and in the last example the displacement is in a wider shear zone.Īfter the models were setup, the team moved the two clay slabs in opposite directions in order to measure minute changes as the strike-slip faults developed. After creating two slabs of this kaolin clay, the team setup several boundary conditions on which to test the development of the strike-slip fault. The Maesters need to know the attitude (strike and dip) of rock units in this folded region. Given the offset of the axial trace of Fold 2 (F2), what type of fault is Fault 2 (Flt 2) a. The team made sure the length to depth was scaled appropriately to mimic that on Earth and with the correct viscosity. Fault 2 has a nearly vertical fault plane. The areas between the ends of adjacent segments are known as stepovers. Hatem built a miniature model of the Earth's crust using kaolin clay. Flower structures developed along minor restraining and releasing bends on a dextral (right-lateral) strike-slip fault Stepovers When strike-slip fault zones develop, they typically form as several separate fault segments that are offset from each other.
0 kommentar(er)
