Transform boundaries
Where plates are moving parallel course, but at different speeds, there are transform faults - grandiose shear violations are widespread in the oceans and rare on continents.
Transform Faults
In the ocean transform faults are perpendicular to the mid-ocean ridges (MOR) and divide them into segments of an average width of 400 km. Between segments of the ridge is part of the active transform fault. On this site are constant earthquakes and mountain building, around the fracture formed numerous offshooting structure - thrusts, folds and graben. As a result, in the fault zone are often exposed mantle rock.
On both sides of the segments of the MOR are inactive part of transform faults. Active movements are not happening, but they are clearly expressed in the topography of the oceans linear uplifts with a central depression.
Transform faults form a law-governed grid and, obviously, do not arise by chance, but due to objective physical causes. A collection of data of numerical simulation, thermal experiments and geophysical observations will reveal that mantle convection is three-dimensional structure. In addition to the main flow of COX, in the convective cell at the expense of cooling the upper part of the flow, there are longitudinal flow. This substance is cooled down rushes down along the main direction of flow of the mantle. In areas of the secondary sinking flux and are transform faults. This model agrees well with the data on heat flux: over transform faults observed him fall.
Shifts in the continents
Shear plate boundaries on continents are relatively rare. Perhaps, the only currently active example of this type of boundary is the San Andreas Fault that separates the North American Plate from the Pacific. 800-mile San Andreas fault - one of the most seismically active areas on the planet: a year plates shifted relative to each other at 0.6 cm, an earthquake with a magnitude greater than 6 units occur on average once every 22 years. City of San Francisco and much of the Bay Area of San Francisco were built in the vicinity of the fault.