[CIG-LONG] Brittle and Ductile deformation

[Walter Landry]

"Md. Tariqul Islam" <misl5790 at uni.sydney.edu.au> wrote:
>  Hi Walter,
> Thanks for your previous help. Now I would like to share some issues with you.
> One is the brittle deformation. As you mentioned in the user manual that if
> the crust has both yielding and viscus rheology it should deform half the
> crust ; but for my case it deformed until Moho and the surface did not
> subsided enough indicating it could be totally brittle ( attached a strain
> rate invariant image).

I do not quite see the problem.  Were you expecting the faults to not
reach down to the Moho?  You would have to fiddle with the parameters
a bit to get that to work.

> The other issue ( this is different model) is the change of viscosity - the
> mantle is showing high viscosity though I used low viscosity ( the input file
> and image for viscosity field is attached).
> As I am using non Newtonian viscosity it is very sensitive, can you suggest me
> how it can be consistent as it is crushing around thirty steps. 

You have set the maxViscosity of the mantle to 1.  My guess is that
your coefficients are off.  For example, your T_0 looks rather high
(62545).  I posted an input file with a working NonNewtonian Rheology
at

  http://www.geodynamics.org/pipermail/cig-long/2010-May/000376.html

It is for the as yet unreleased version of Gale, but you should be
able to use the same numbers for scaling.

> The other thing is I am using the direct solver, do you think that
> this is making any difference?

A direct solver works better than anything else, so you do not need to
change that.

Cheers,
Walter Landry
walter at geodynamics.org