[CIG-SHORT] Initial stresses for large model

[Demian Gomez]

Hi Brad,

Thanks for your answer. I was thinking of maybe making a two step problem
where at time 0 it would calculate the initial stress and then at time 1
put in the slip at the fault. Sort of a pseudo-earthquake cycle but with
two quasi-static simulations and no time dependent problem between them. Do
you think this might work?

Demián

On Fri, Jan 27, 2017 at 4:27 PM, Brad Aagaard <baagaard at usgs.gov> wrote:

> Demian,
>
> It sounds like you want an optimized spatial database for the case of
> using output as input. This is not implemented.
>
> I think the best you can do now is a dense SimpleGridDB that minimizes any
> interpolation errors.
>
> Regards,
> Brad
>
>
> On 01/26/2017 10:14 AM, Demian Gomez wrote:
>
>> Matt,
>>
>> There is no projection involved in my approach. I didn't follow Brad's
>> suggestion of using a topocentric coordinate system. I have a spherical
>> model constructed in a geocentric CS (ECEF) and my initial stress
>> spatial database in lat lon depth (i.e. cs-data = geographic and
>> is-geocentric = false). Therefore, the conversion from one type of
>> coordinate to the other shouldn't have any effect.
>>
>> Demián
>>
>> On Wed, Jan 25, 2017 at 9:26 PM, Matthew Knepley <knepley at rice.edu
>> <mailto:knepley at rice.edu>> wrote:
>>
>>     On Wed, Jan 25, 2017 at 6:55 PM, Demian Gomez <demiang at gmail.com
>>     <mailto:demiang at gmail.com>> wrote:
>>
>>         Dear all,
>>
>>         A few months ago I asked a question about strategies to assign
>>         the initial stresses for a large model. I was originally using a
>>         SimpleDB file and Brad suggested that a SimpleDbGrid provides a
>>         much faster interpolation. Here's the
>>         thread: http://lists.geodynamics.org/p
>> ipermail/cig-short/2016-November/002612.html
>>         <http://lists.geodynamics.org/pipermail/cig-short/2016-Novem
>> ber/002612.html>
>>
>>         I am now calculating the initial stresses on a first run (as
>>         explained
>>         here: https://wiki.geodynamics.org/_
>> media/software:pylith:tutorials:cdm2016:pylithtutorial2016_gravity.pdf
>>         <https://wiki.geodynamics.org/_media/software:pylith:tutoria
>> ls:cdm2016:pylithtutorial2016_gravity.pdf>)
>>         and I want to use them to compute quasi-static co-seismic
>>         deformation. I've looked at generate_statedb.py in the gravity
>>         examples, which uses a SimpleDB file to input the stresses into
>>         Pylith. This method, however, will generate a severe slow down,
>>         as discussed in the previous thread.
>>
>>         Is there another strategy to input the initial stresses
>>         calculated by the first Pylith run? I do not want to use a
>>         SimpleGridDb because this will require two interpolations: a
>>         first one to generate the grid and a second one to assign the
>>         stresses to each cell. I'm afraid this will lead to slightly
>>         unbalanced stresses generated by the two interpolations.
>>
>
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