[CIG-SHORT] Does normal traction perturbation affect normal fault traction

[Brad Aagaard]

Birendra,

The traction on the fault is the traction from deformation + traction 
perturbation. For example if you specify an initial normal traction 
perturbation of -100 MPa and a static coefficient of friction of 0.6, 
then the static friction on the fault would be 60 MPa in the absence of 
any deformation. In dynamic spontaneous rupture simulations with elastic 
materials, we generally impose a traction perturbation to generate 
initial (background) stresses on the fault rather than computing them 
from deformation imposed on the boundary.

Regards,
Brad

On 11/22/12 9:53 PM, Birendra jha wrote:
> Hi
>
> For a dynamic fault, I understand that user can specify traction
> perturbation on a fault surface to introduce fault slip. But does a
> normal traction perturbation also change the magnitude of normal
> fault traction used in the friction model calculation (i.e.
> tractionNormal in FaultCohesiveDyn::_constrainSolnSpace3D), such that
> making it easier to slip if the perturbation is compressive?
>
> If it is assumed that user supplied friction parameters (coeff of
> friction, cohesion etc) best represent the friction, hence traction
> perturbation does not change friction calculation explicitly, that's
> ok. Just wanted to understand.
>
> Thanks and regards Birendra
>
>
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