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

[Brad Aagaard]

Gravity works with 2-D. The default direction for the gravitational 
acceleration vector is [0,0,-1]. Assuming +y is up in your 2-D model, 
you would need to change it to [0,-1,0].

gravity_field = spatialdata.spatialdb.GravityField
gravity_field.gravity_dir = [0,-1,0]

Brad


On 4/9/13 8:36 AM, Shaoyang Li wrote:
> Dear Brad,
>
> thanks for your information. It works better when the two faults get closer.
>
> I have another question. I am trying to apply Gravity in 2D model by
> change the example of 3d/hex8, but the results are always zero. Can
> gravity be used in 2D model? thanks.
>
> best regards
> shaoyang
>
>
>
> On Mon, 8 Apr 2013 08:39:11 -0700
>   Brad Aagaard <baagaard at usgs.gov> wrote:
>  > 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
>  >
>