[CIG-SHORT] problem definition for Landers-Hector Mine benchmark

[Brad Aagaard]

Hi all:

I would like to put the problem description together for the 
Landers-Hector Mine benchmark.

I have the following tidbits in my notes from the Golden workshop:

* Use mesh provided by Carl
* Use Landers slip model provided by Yuri
* Use layered material model provided by Brad
  - viscosity is 10^18 Pa-s in lower-crust and mantle
* Boundaries (lateral sides and bottom) are fixed displacements
* Solution is computed at 0, 5, 10, 15 years
* no gravity

Issues that need to be resolved (please comment):

1. How is the slip model going to be defined? Are people getting the 
slip model info from attributes embedded in the LaGriT output or is 
Yuri providing a separate data file?

2. What depth range are we using for the lower-crust and mantle? I am 
guessing that we will use a viscosity of 10^25 Pa-s in the upper 
crust as we did for the reverse and strike-slip benchmarks, so at 
what depth do we jump to a viscosity of 10^18 Pa-s?

3. What comprises the "solution"? I am guessing that we want 
displacements and velocities at all of the nodes as we have done for 
the other benchmarks. In this case, we have additional faults (i.e., 
Hector Mine faults), so we will want stress changes on those 
surfaces, right? I am guessing we want the traction vector computed 
at the quadrature points of the faces making up the Hector Mine 
faults.

Brad