[CIG-SHORT] Problems report for Pylith's subduction example_KejingHuang

Wed Aug 8 15:42:45 PDT 2018

Dear Huang,

I will try to look at this in the next few days.  In the meantime, I suggest sending all requests such as this to the cig-short mailing list.  That will greatly increase your chances of getting a prompt reply.

Cheers,
Charles

On 8/08/2018, at 8:32 PM, hkj at mail.ustc.edu.cn<mailto:hkj at mail.ustc.edu.cn> wrote:

Dear Professor Williams

Sorry I thought the reply would send to my email address, I downloaded the cig-short mailing list and found your reply message.

Thank you for your answers. For problems with the step02 example, I think I misunderstood something and thought it should be more or less like the pattern of coseismic displacement field. Now the horizontal pattern makes more sense to me. But for vertical pattern, I'm curious why there's big subsidence near the lower end of rupture area.(The figures below show the results of mine mesh geometry.). Because comparing to previous study, the vertical pattern of viscoelastic relaxation near the rupture area should be dominantly uplift(The ground surface vertical component comparison is showed in figure 3).

Similar to your figure, the colors of rupture area represent displacement magnitude, and the vectors represent velocities.And viscous strain is also represented.

1. Coseismic displacement
<desc.png>

2.  30 to 40 year of velocity field of Viscoelastic relaxation
<desc.png>

3.  Ground surface: 30 to 40 year of velocity field of Viscoelastic relaxation comparison(vertical component)

ps: The black vectors are previous results, and the red vectors are mine, I have tried just the same material properties as previous study and also many other possible material properties/time period, there is always apparent subsidence in area where coseismic displacement is large.
<desc.png>
I greatly appreciate your time!

Kejing Huang

-----Original Messages-----
From:"Charles Williams" <C.Williams at gns.cri.nz<mailto:C.Williams at gns.cri.nz>>
Sent Time:2018-08-08 07:02:00 (Wednesday)
To: "hkj at mail.ustc.edu.cn<mailto:hkj at mail.ustc.edu.cn>" <hkj at mail.ustc.edu.cn<mailto:hkj at mail.ustc.edu.cn>>
Cc: cig-short <cig-short at geodynamics.org<mailto:cig-short at geodynamics.org>>
Subject: Re: Problems report for Pylith's subduction example_KejingHuang

Dear Huang,

Did you see my reply on the cig-short mailing list?  If so, have you turned on the output for ‘velocity’ and ‘viscous_strain’?  I think this will help you see what is going on.  I’m attaching a couple of figures to show what I mean.

As far as your difficulties using a spherical earth, it’s hard to say without knowing what errors you are getting.

As far as your problems with the step02 example, I’m not sure what you are expecting to see.  Can you clarify this?

Cheers,
Charles

p.s.  In the attached plots, the colors represent displacement magnitude, and the vectors represent velocities.

<disp_vel_t4.jpg><disp_vel_t42.jpg>

On 7/08/2018, at 7:22 PM, hkj at mail.ustc.edu.cn<mailto:hkj at mail.ustc.edu.cn> wrote:

Dear Professor Williams

My name is Kejing Huang. I’m a first-year graduate student at USTC working with Profs. Yan Hu and Jefferey Freymueller on the postseismic deformation of the 1964 Mw9.2 Alaska earthquake.

I'm learning Pylith now. Pylith is indeed very powerful, I do appreciate your efforts. However,  when I used step02 of 3d subduction example, problems showed up.

The first problem is, I saw the paper written by Prof. Pratama (attached to this email) used a spherical-earth model by local geographically referenced Cartesian system. I tried it with Pylith's subduction example, but it didn't work and always report error. I didn't find detailed introduction from the user manual or the website. Should I build the model in ECEF system initially with Trelis/Cubit ?

The second problem is much more disturbing, the files attached are modified from step02 of Pylith 3d subduction example, I just changed the material properties and calculation time, in this example:
I changed the body materials to a elastic slab, a elastic crust, a elastic wedge and a viscoelastic mantle.
The coseismic displacement is perfect and is consistent with OKADA results. But for postseismic deformation,it didn't give ideal result, it's totally different from the pattern I expected, I can't even see the elastic slab boundary in postseismic deformation.(The README file includes some more description.)

I have tried different model geometry, different time step, different slip distribution and different material properties, but none of them works. Other students of my research group are also facing with this problem, and we have been sticking in this step for half a month.

I sincerely hope you can find out where the problem is. Thank you very much!

Kejing Huang
University of Science and Technology of China

<modified_example_3d_subduction_step02.zip><Pratama_et_al_JAES_2017.pdf>

Charles Williams I Geodynamic Modeler
GNS Science I Te Pῡ Ao
1 Fairway Drive, Avalon 5010, PO Box 30368, Lower Hutt 5040, New Zealand
Ph 0064-4-570-4566 I Mob 0064-22-350-7326 I Fax 0064-4-570-4600
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Notice: This email and any attachments are confidential and may not be used, published or redistributed without the prior written consent of the Institute of Geological and Nuclear Sciences Limited (GNS Science). If received in error please destroy and immediately notify GNS Science. Do not copy or disclose the contents.

Charles Williams I Geodynamic Modeler
GNS Science I Te Pῡ Ao
1 Fairway Drive, Avalon 5010, PO Box 30368, Lower Hutt 5040, New Zealand
Ph 0064-4-570-4566 I Mob 0064-22-350-7326 I Fax 0064-4-570-4600
http://www.gns.cri.nz/ I Email: C.Williams at gns.cri.nz<mailto:your.email at gns.cri.nz>

Notice: This email and any attachments are confidential and may not be used, published or redistributed without the prior written consent of the Institute of Geological and Nuclear Sciences Limited (GNS Science). If received in error please destroy and immediately notify GNS Science. Do not copy or disclose the contents.
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