[CIG-SHORT] Fault direction in 3D fault

Sun May 4 14:56:28 PDT 2014

Hi Jiangzhi,

The up_dir is just used to help PyLith figure out how your coordinate system is set up.  Not specifying it for your slabbot fault may be causing some problems, but I also suspect there may be some inconsistencies between your boundary conditions and your applied fault slip.  Also, when you run the problem are you getting convergence in the linear solution?

Cheers,
Charles

On 5/05/2014, at 9:38 am, Jiangzhi Chen <jzchenjzarthur at gmail.com> wrote:

> Thanks for your advice, I am still trying to get the slab move correctly. The part I am confused is that the slab just sinks down, as shown in the gif figure in my previous email. Is this up_dir related to the fault type, i.e., reverse fault or normal fault? In my case, the slab top is a reverse fault, and slabbot is a normal fault. Maybe the reason is that I did not specify up_dir for the slabbot fault.
> 
> Jiangzhi
> 
> On May 4, 2014, at 2:20 PM, Charles Williams <willic3 at gmail.com> wrote:
> 
>> Hi Jiangzhi,
>> 
>> Did you make any more progress on this?  Were the strike_dir, dip_dir, etc., consistent with what you thought?  These are just direction cosines, so you can plot them as vectors to see what they look like.
>> 
>> Also, I noticed that you only specified up_dir for one of your faults.  I believe that the default is [0,0,1], but it’s probably a good idea to specify this as well for consistency.
>> 
>> Cheers,
>> Charles
>> 
>> 
>> On 3/05/2014, at 8:03 am, Jiangzhi Chen <jzchenjzarthur at gmail.com> wrote:
>> 
>>> Hi Brad and Charles,
>>> 
>>>  Thanks for your advice. First I tried Brad's suggestion, but the slab still went to wrong direction (screen1 and screen2). To be clear, the model simulates the Cascadia subduction zone, X is easting, Y is northing, and Z is up. Currently I have slabtop and slabbot both creeping at 8 cm/yr, and the slab is supposed to go down with slight rotation because of the geometry of the subduction boundary.
>>> 
>>>  Then I tried the suggestion from Charles, changed the bc_dof on the side to 1, and bc_dof on the bottom to 2, with up_dir [0,0,1]. This time, the slab did go down, but it just sank all way down (slab.gif).
>>> 
>>> Jiangzhi
>>> 
>>> On 05/01/2014 04:53 PM, Brad Aagaard wrote:
>>>> Jiangzhi,
>>>> 
>>>> If this is the same model you used a while ago, then I believe you use [0,1,0] as the up_dir for the domain. You need to set the up_dir to [0,1,0] for all faults and boundaries.
>>>> 
>>>> You should request that the fault orientation be information be written so that you can see the strike_dir, dip_dir, and fault normal directions for your geometry. This will help you debug the fault slip directions. See examples/3d/hex8/step06.cfg for how to request the fault directions be output.
>>>> 
>>>> Brad
>>>> 
>>>> 
>>>> On 5/1/14, 4:25 PM, Charles Williams wrote:
>>>>> Hi Jiangzhi,
>>>>> 
>>>>> One problem that I see is that I think you’ve mixed up the bc_dof for your bottom boundary (should be 2) compared to your front and back boundaries (should be 1).  Let me know if this helps.
>>>>> 
>>>>> Cheers,
>>>>> Charles
>>>>> 
>>>>> 
>>>>> On 2/05/2014, at 10:26 am, Jiangzhi Chen <jzchenjzarthur at gmail.com> wrote:
>>>>> 
>>>>>> Hi everyone,
>>>>>> 
>>>>>>  I have a 3D subduction model simulating the interseismic deformation, where I have both fault_slabtop and fault_slabbot creeping. I have set fault_slabtop with reverse_slip of 8 cm/yr and fault_slabbot with reverse_slip of -8 cm/yr, and used the up_dir parameter [0,0,1], but still the subduction is in wrong direction. I am not sure what is wrong. The configuration files are attached. Thanks.
>>>>>> 
>>>>>> Jiangzhi
>>>>>> <screen.png><pylithapp.cfg><interseismic.cfg><mat_conmantle.spatialdb><mat_oceanlitho.spatialdb><mat_oceanmantle.spatialdb><mat_conlitho.spatialdb>_______________________________________________ 
>>>>>> CIG-SHORT mailing list
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>>>>> 
>>>>> Charles A. Williams
>>>>> Scientist
>>>>> GNS Science
>>>>> 1 Fairway Drive, Avalon
>>>>> PO Box 30368
>>>>> Lower Hutt  5040
>>>>> New Zealand
>>>>> ph (office): 0064-4570-4566
>>>>> fax (office): 0064-4570-4600
>>>>> C.Williams at gns.cri.nz
>>>>> 
>>>>> _______________________________________________
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>>>>> 
>>>> 
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>>> 
>>> <screen1.png><screen2.png><slab.gif>_______________________________________________
>>> CIG-SHORT mailing list
>>> CIG-SHORT at geodynamics.org
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>> 
>> Charles A. Williams
>> Scientist
>> GNS Science
>> 1 Fairway Drive, Avalon
>> PO Box 30368
>> Lower Hutt  5040
>> New Zealand
>> ph (office): 0064-4570-4566
>> fax (office): 0064-4570-4600
>> C.Williams at gns.cri.nz
>> 
>> _______________________________________________
>> CIG-SHORT mailing list
>> CIG-SHORT at geodynamics.org
>> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-short
> 
> _______________________________________________
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Charles A. Williams
Scientist
GNS Science
1 Fairway Drive, Avalon
PO Box 30368
Lower Hutt  5040
New Zealand
ph (office): 0064-4570-4566
fax (office): 0064-4570-4600
C.Williams at gns.cri.nz