[CIG-SHORT] Time stepping to capture the growth of rate-and-state slip instability

[Ekaterina Bolotskaya]

Dear Pylith developers,

I have a quasi static 2D simulation with a planar horizontal fault with rate-and-state friction. My block is 9m by 6 m.
I apply y-compression and shear traction to the block as initial conditions and then try to observe the generation of rate-and-state slip instability on the fault (when slip rate increases to 10s of meters per second and then goes back to stable slip rate values).

I'm using adaptive time stepping:

[pylithapp.problem.formulation]
time_step = pylith.problems.TimeStepAdapt
[pylithapp.problem.formulation.time_step]
total_time = 0.008*s
max_dt = 0.00007*s
adapt_skip = 0
stability_factor = 1.5

But currently I don't think that my time step size ever changes: it seems like it keeps the max_dt value throughout the simulation. If I decrease max_dt further the simulation stops converging. Ideally I would like my time step to be ~inversely proportional to my slip rate on the fault, so that I can capture the instability in slip rate. Is there a way to implement this or something like this?
Should I create a file with prescribed time steps? Would that help?

Thanks!


Best regards,
Ekaterina Bolotskaya

PhD student in Geophysics,
Earth, Atmospheric and Planetary Science Department,
Massachusetts Institute of Technology
E-mail. bolee at mit.edu
Mob. +1 (857) 284-2805<tel:%2B1%20%28857%29%20284-2805>
         +7 (963) 995-36-33<tel:%2B7%20%28963%29%20995-36-33>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.geodynamics.org/pipermail/cig-short/attachments/20180308/c8965f80/attachment-0001.html>