[CIG-SHORT] long-term simulation of seismic cycles with rate and state friction law

[Brad Aagaard]

On 4/8/13 7:32 AM, Shaoyang Li wrote:
> Dear Brad,
>
> currently, I am trying to simulate how a kinematic fault affect a
> dynamic fault in one configuration, i.e. I prescribe kinematic slip on a
> main fault and see the difference of deformation fields between with and
> without secondary (frictional) dynamic fault.
>
> The secondary fault indeed change the deformation field. But when I
> change different friction components (laws) and their parameters, the
> deformation field turn out to be all exactly same. I try both explicit
> and implicit method, but the results are same.

Please explain in more detail what you are changing. If you change the 
friction parameters, the slip/tractions on the fault with spontaneous 
rupture will change, so I am not sure what you are doing.

> Why a kinematic fault cannot make a frictional fault move "coseismicly"
> but time-dependent boundary condition can make the frictional fault
> function? How can I apply non-linear solver in explicit method? Should
> two faults be both either kinematic or friction dynamic in Pylith?

Each fault can be assigned prescribed slip or spontaneous rupture 
independent of all other faults. Triggering rupture on one fault via 
static/dynamic stress changes from rupture of other faults is a complex 
problem. There have been a number of studies on this topic. Many 
suggests the faults must be in close proximity (< few km) to one another 
for dynamic triggering.

The nonlinear solver should not be needed for the explicit method, 
because it is using the central difference scheme and the Jacobian of 
the system is diagonal. For rate-state friction, the current frictional 
update routine is not robust and is currently being revised to correct 
this deficiency.

Regards,
Brad