Fault restoration

Many workers have presented geometric and physical models of hanging-wall collapse along vertical or steeply dipping shear surfaces. There are a number of fault restoration methods described in the literature such as vertical shear, inclined shear, bedding plane slip, slip line, etc. In general, it is found that the vertical shear method is a good approximation.

BMT uses the vertical shear method for fault restoration for the following reasons

• it provides a good approximation to observed fault displacements

•  it is able to keep track of rock mass

• it greatly simplifies and accelerates calculation of compaction effects and tracking of mass

• it needs much less user interaction than the inclined shear method which requires that shear angles be defined on a fault-by-fault basis.

   

Illustration of vertical simple shear. During the reconstruction, the bars are translated up the fault system until the top timeline is continuous across the fault surface.  Once the bars have been moved horizontally, their vertical positions are determined by drawing upwards from their new positions along the fault plane.