From yaoyixin1989 at 163.com  Mon Apr  2 07:04:20 2018
From: yaoyixin1989 at 163.com (yaoyixin1989 at 163.com)
Date: Mon, 2 Apr 2018 22:04:20 +0800
Subject: [CIG-SEISMO] using SPECFEM3D fot simulating gravity perturbation
Message-ID: <2018040222041938194616@163.com>

Dear prof.,
I am a PhD student of Institute of Geodesy and Geophysics, Chinese Academy of Sciences. I am interested in gravity perturbation caused by an earthquake, and I try to do the simulation by using SPECFEM3D software. These days, I have searched the manual clearly, but I didn't find the detailed discription about gravity perturbation. 
What should I do, is there a detailed manual about how to simulate the gravity perturbation?
Thank you very much for your kind consideration and I am looking forward to your reply!

Sincerely, yours
Yixin Yao


yaoyixin1989 at 163.com
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From petersson1 at llnl.gov  Mon Apr  2 12:21:10 2018
From: petersson1 at llnl.gov (Petersson, Anders)
Date: Mon, 2 Apr 2018 19:21:10 +0000
Subject: [CIG-SEISMO] SW4 installation error (weiyu chen)
Message-ID: <7C1973FA-5BB2-49AF-AF73-C4EC4D17215F@llnl.gov>

This looks like a linking error and it looks like you are using gnu compilers. You need to add -lgfortran to the EXTRA-LINK-FLAGS variable. Look in configs/make.linux for an example.
/Anders

On 4/2/18, 12:07 PM, "CIG-SEISMO on behalf of cig-seismo-request at geodynamics.org" <cig-seismo-bounces at geodynamics.org on behalf of cig-seismo-request at geodynamics.org> wrote:

    Send CIG-SEISMO mailing list submissions to
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    When replying, please edit your Subject line so it is more specific
    than "Re: Contents of CIG-SEISMO digest..."
    
    
    Today's Topics:
    
       1. SW4 installation error (weiyu chen)
       2. using SPECFEM3D fot simulating gravity perturbation
          (yaoyixin1989 at 163.com)
    
    
    ----------------------------------------------------------------------
    
    Message: 1
    Date: Thu, 29 Mar 2018 04:24:30 +0000
    From: weiyu chen <wyc1974 at hotmail.com>
    To: "cig-seismo at geodynamics.org" <cig-seismo at geodynamics.org>
    Subject: [CIG-SEISMO] SW4 installation error
    Message-ID:
    	<MWHPR15MB1935FDC30FACE6F6FC73D6BEA9A20 at MWHPR15MB1935.namprd15.prod.outlook.com>
    	
    Content-Type: text/plain; charset="utf-8"
    
    Hi,
    
    I am pretty new to Linux, so was following the SW4 installation step-
    by-step. I encountered following error messages when "make"
    
    xerror.o: In function `xersav_.constprop.2':
    xerror.f:(.text+0x12c): undefined reference to `_gfortran_st_write'
    xerror.f:(.text+0x140): undefined reference to
    `_gfortran_transfer_character_write'
    xerror.f:(.text+0x14a): undefined reference to
    `_gfortran_st_write_done'
    .....
    
    Can you please teach me how to install SW4 properly? Many thanks.
    
    weiyu
    
    
    ------------------------------
    
    Message: 2
    Date: Mon, 2 Apr 2018 22:04:20 +0800
    From: "yaoyixin1989 at 163.com" <yaoyixin1989 at 163.com>
    To: cig-seismo <cig-seismo at geodynamics.org>
    Subject: [CIG-SEISMO] using SPECFEM3D fot simulating gravity
    	perturbation
    Message-ID: <2018040222041938194616 at 163.com>
    Content-Type: text/plain; charset="utf-8"
    
    Dear prof.,
    I am a PhD student of Institute of Geodesy and Geophysics, Chinese Academy of Sciences. I am interested in gravity perturbation caused by an earthquake, and I try to do the simulation by using SPECFEM3D software. These days, I have searched the manual clearly, but I didn't find the detailed discription about gravity perturbation. 
    What should I do, is there a detailed manual about how to simulate the gravity perturbation?
    Thank you very much for your kind consideration and I am looking forward to your reply!
    
    Sincerely, yours
    Yixin Yao
    
    
    yaoyixin1989 at 163.com
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    ------------------------------
    
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    End of CIG-SEISMO Digest, Vol 123, Issue 1
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From komatitsch at lma.cnrs-mrs.fr  Tue Apr  3 07:38:58 2018
From: komatitsch at lma.cnrs-mrs.fr (Dimitri Komatitsch)
Date: Tue, 3 Apr 2018 16:38:58 +0200
Subject: [CIG-SEISMO] using SPECFEM3D fot simulating gravity perturbation
In-Reply-To: <2018040222041938194616@163.com>
References: <2018040222041938194616@163.com>
Message-ID: <83b17ee4-0f9f-e357-9a02-14dedf24ed9e@lma.cnrs-mrs.fr>


Dear Yixin Yao,

Thank you for your interest in our work on this. You are right, by lack 
of time the gravity integrals are not very well documented in the users 
manual, however they are explained in detail in this paper: 
http://komatitsch.free.fr/preprints/GJI_Martin_gravimetry_2017.pdf

You can also find the flags to use in file setup/constants.h.in, there 
is a section with flags about gravity integrals, called "gravity 
integral calculations".

Best regards,
Dimitri.

On 04/02/2018 04:04 PM, yaoyixin1989 at 163.com wrote:
> Dear prof.,
> I am a PhD student of Institute of Geodesy and Geophysics, Chinese 
> Academy of Sciences.I am interested in gravity perturbation caused by an 
> earthquake, and I try to do the simulation by using SPECFEM3D software. 
> These days, I have searched the manual clearly, but I didn't find the 
> detailed discription about gravity perturbation.
> What should I do, is there a detailed manual about how to simulate the 
> gravity perturbation?
> Thank you very much for your kind consideration and I am looking forward 
> to your reply!
> 
> Sincerely, yours
> Yixin Yao
> ------------------------------------------------------------------------
> yaoyixin1989 at 163.com
> 
> 
> _______________________________________________
> CIG-SEISMO mailing list
> CIG-SEISMO at geodynamics.org
> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo
> 

-- 
Dimitri Komatitsch, CNRS Research Director (DR CNRS)
Laboratory of Mechanics and Acoustics, Marseille, France
http://komatitsch.free.fr

From komatitsch at lma.cnrs-mrs.fr  Tue Apr  3 07:44:20 2018
From: komatitsch at lma.cnrs-mrs.fr (Dimitri Komatitsch)
Date: Tue, 3 Apr 2018 16:44:20 +0200
Subject: [CIG-SEISMO] using SPECFEM3D fot simulating gravity
 perturbation / PS
In-Reply-To: <83b17ee4-0f9f-e357-9a02-14dedf24ed9e@lma.cnrs-mrs.fr>
References: <2018040222041938194616@163.com>
 <83b17ee4-0f9f-e357-9a02-14dedf24ed9e@lma.cnrs-mrs.fr>
Message-ID: <4161e476-7f27-cc14-9414-5511b7c946f9@lma.cnrs-mrs.fr>


Dear Yixin Yao,

Please also make sure you get a recent version of the code, for instance 
by typing this:

git clone --recursive --branch devel 
https://github.com/geodynamics/specfem3d.git

because the current version of the users manual says this:

"OTHER ANNOUNCEMENT: SPECFEM3D can now perform gravity field 
calculations in addition (or instead of) seismic wave propagation only. 
See flag GRAVITY_INTEGRALS in file setup/constants.h.in.
Please also refer to 
http://komatitsch.free.fr/preprints/GJI_Martin_gravimetry_2017.pdf.
And yes, that is the reason why I added a falling apple on the cover of 
the manual :-)"

Best regards,
Dimitri.

On 04/03/2018 04:38 PM, Dimitri Komatitsch wrote:
> 
> Dear Yixin Yao,
> 
> Thank you for your interest in our work on this. You are right, by lack 
> of time the gravity integrals are not very well documented in the users 
> manual, however they are explained in detail in this paper: 
> http://komatitsch.free.fr/preprints/GJI_Martin_gravimetry_2017.pdf
> 
> You can also find the flags to use in file setup/constants.h.in, there 
> is a section with flags about gravity integrals, called "gravity 
> integral calculations".
> 
> Best regards,
> Dimitri.
> 
> On 04/02/2018 04:04 PM, yaoyixin1989 at 163.com wrote:
>> Dear prof.,
>> I am a PhD student of Institute of Geodesy and Geophysics, Chinese 
>> Academy of Sciences.I am interested in gravity perturbation caused by 
>> an earthquake, and I try to do the simulation by using SPECFEM3D 
>> software. These days, I have searched the manual clearly, but I didn't 
>> find the detailed discription about gravity perturbation.
>> What should I do, is there a detailed manual about how to simulate the 
>> gravity perturbation?
>> Thank you very much for your kind consideration and I am looking 
>> forward to your reply!
>>
>> Sincerely, yours
>> Yixin Yao
>> ------------------------------------------------------------------------
>> yaoyixin1989 at 163.com
>>
>>
>> _______________________________________________
>> CIG-SEISMO mailing list
>> CIG-SEISMO at geodynamics.org
>> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo
>>
> 

-- 
Dimitri Komatitsch, CNRS Research Director (DR CNRS)
Laboratory of Mechanics and Acoustics, Marseille, France
http://komatitsch.free.fr

From surendra at iith.ac.in  Wed Apr  4 11:23:38 2018
From: surendra at iith.ac.in (Surendra Nadh Somala)
Date: Wed, 4 Apr 2018 23:53:38 +0530
Subject: [CIG-SEISMO] using SPECFEM3D fot simulating gravity
 perturbation / PS
In-Reply-To: <4161e476-7f27-cc14-9414-5511b7c946f9@lma.cnrs-mrs.fr>
References: <2018040222041938194616@163.com>
 <83b17ee4-0f9f-e357-9a02-14dedf24ed9e@lma.cnrs-mrs.fr>
 <4161e476-7f27-cc14-9414-5511b7c946f9@lma.cnrs-mrs.fr>
Message-ID: <CAK6kgGiC08uuZf27NzE4tF9iqoZaRhaz-YTYYDe1YSTNhoNScg@mail.gmail.com>

Dear Dimitri,

I think Yixin Yao is looking for a feature that I had implemented during my
Caltech days (way back in 2013) but never made it to manual, although it is
still in the master github repository of Specfem3D.  We had a publication
eventually on it in 2015 whose link is given below:
https://authors.library.caltech.edu/58337/1/Geophys.%20J.%20Int.-2015-Harms-1416-25.pdf

The title of that article: "Transient gravity perturbations induced by
earthquake rupture" sounds more like what Yixin Yao asked for in the first
email.

The only documentation we currently have for this feature is in a
standalone README file that can be found here:
doc/how_to/README_gravityPerturbation_bis.txt
<https://github.com/geodynamics/specfem3d/blob/ff24d4062e223aa976c338b45fd4eb568ad1558a/doc/how_to/README_gravityPerturbation_bis.txt>

Could you please add a note about this new feature in the manual where you
may feel relevant (probably with a clarification that this differs from
Martin Roland's work on gravity integrals/field calculation) and request
the users of this feature to cite the following article.
Harms, J., J.-P. Ampuero, M. Barsuglia, E. Chassande-Mottin, J.-P.
Montagner, S. N. Somala and B. F. Whiting (2015)*Transient gravity
perturbations induced by earthquake rupture*, Geophysical Journal
International, 201 (3), 1416-1425 doi:10.1093/gji/ggv090

Regards,
Surendra





___________
*Surendra Nadh Somala*
Assistant Professor
Department of Civil Engineering (Block-E, 208)
Indian Institute of Technology (IIT) Hyderabad
Kandi, Sangareddy
Telangana, India - 502285
Phone : +91 (0)40 2301-8457
http://civil.iith.ac.in/surendra/

On Tue, Apr 3, 2018 at 8:14 PM, Dimitri Komatitsch <
komatitsch at lma.cnrs-mrs.fr> wrote:

>
> Dear Yixin Yao,
>
> Please also make sure you get a recent version of the code, for instance
> by typing this:
>
> git clone --recursive --branch devel https://github.com/geodynamics
> /specfem3d.git
>
> because the current version of the users manual says this:
>
> "OTHER ANNOUNCEMENT: SPECFEM3D can now perform gravity field calculations
> in addition (or instead of) seismic wave propagation only. See flag
> GRAVITY_INTEGRALS in file setup/constants.h.in.
> Please also refer to http://komatitsch.free.fr/prep
> rints/GJI_Martin_gravimetry_2017.pdf.
> And yes, that is the reason why I added a falling apple on the cover of
> the manual :-)"
>
> Best regards,
> Dimitri.
>
> On 04/03/2018 04:38 PM, Dimitri Komatitsch wrote:
>
>>
>> Dear Yixin Yao,
>>
>> Thank you for your interest in our work on this. You are right, by lack
>> of time the gravity integrals are not very well documented in the users
>> manual, however they are explained in detail in this paper:
>> http://komatitsch.free.fr/preprints/GJI_Martin_gravimetry_2017.pdf
>>
>> You can also find the flags to use in file setup/constants.h.in, there
>> is a section with flags about gravity integrals, called "gravity integral
>> calculations".
>>
>> Best regards,
>> Dimitri.
>>
>> On 04/02/2018 04:04 PM, yaoyixin1989 at 163.com wrote:
>>
>>> Dear prof.,
>>> I am a PhD student of Institute of Geodesy and Geophysics, Chinese
>>> Academy of Sciences.I am interested in gravity perturbation caused by an
>>> earthquake, and I try to do the simulation by using SPECFEM3D software.
>>> These days, I have searched the manual clearly, but I didn't find the
>>> detailed discription about gravity perturbation.
>>> What should I do, is there a detailed manual about how to simulate the
>>> gravity perturbation?
>>> Thank you very much for your kind consideration and I am looking forward
>>> to your reply!
>>>
>>> Sincerely, yours
>>> Yixin Yao
>>> ------------------------------------------------------------------------
>>> yaoyixin1989 at 163.com
>>>
>>>
>>> _______________________________________________
>>> CIG-SEISMO mailing list
>>> CIG-SEISMO at geodynamics.org
>>> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo
>>>
>>>
>>
> --
> Dimitri Komatitsch, CNRS Research Director (DR CNRS)
> Laboratory of Mechanics and Acoustics, Marseille, France
> http://komatitsch.free.fr
> _______________________________________________
> CIG-SEISMO mailing list
> CIG-SEISMO at geodynamics.org
> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo
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From ge.li2 at mail.mcgill.ca  Wed Apr  4 18:00:11 2018
From: ge.li2 at mail.mcgill.ca (Ge Li)
Date: Wed, 04 Apr 2018 21:00:11 -0400
Subject: [CIG-SEISMO] [Specfem3D Cartesian]- Using a CMTSOLUTION source to
 trigger a critically-stressed fault
Message-ID: <C8EAAA77-8EEE-48F1-945A-2CFDCF3C6AF6@contoso.com>

To Whom It May Concern:

 

I’m a PhD Candidate in geophysics at McGill University. Currently I’m using

Specfem3D Cartesian for my research. 

I’m wondering is it possible to trigger an earthquake on a fault using a CMTSOLUTION source?

I tried several simulations by setting a critically stressed fault and a CMTSOLUTION point source.

The source (Mw~6 Right-lateral strike slip) was located about only 1km away from the fault surface.

But it turned out the stresses on the fault surface(dynamic slip-weakening) remain unchanged. 

Based on these tests, I supposed that a CMTSOLUTION won’t change the stress level on a fault surface. Is it correct? 

Or did I miss something here?

 

Thanks! I’m looking forward to your reply!

 

 

-- 

Ge Li

Ph.D. Candidate

Department of Earth & Planetary Science, 

McGill University

3450 University Street

Montreal, QC, Canada 

H3A 0E8

ge.li2 at mail.mcgill.ca

 

 

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From INCHINP at my.erau.edu  Thu Apr  5 10:39:12 2018
From: INCHINP at my.erau.edu (Inchin, Pavel)
Date: Thu, 5 Apr 2018 17:39:12 +0000
Subject: [CIG-SEISMO] SPECFEM3D-Globe, near epicenter velocities
Message-ID: <1D5626F1-A72B-4725-80FC-7E97F619AAFD@my.erau.edu>

Good day,

I have a problem with simulation of velocities at close to the epicenter distances.
I need to obtain surface vertical velocities with 2 km step to the North (+3000 km) and South (-3000 km) from the epicenter along longitude of epicenter, so I just get synthetic seismograms for every such point from SPECFEM3D-Globe.

Here is a result of global simulation SPECFEM3D-Globe for NEX_XI=96 at some time of simulation (20mHz-example figure). The simulation looks good.

[cid:359B6E2D-CF72-4073-9B82-0C3F41DE4DA5 at db.erau.edu]

Now, I do the same simulation for NEX_XI=240 and I get a very slowly decreasing rise/drop near the epicenter. Here are several figures for different times (50mhz-1.32, 50mhz-2.23, 50mhz-4.02, 50mhz-6.22 files; time is shown on figures - minutes from event):

[cid:3A1F3E84-4D5B-4A5D-88F8-FA84951A2258 at db.erau.edu]

[cid:07AEA2D3-D8F6-492F-B7B9-B69421FAAFB3 at db.erau.edu]

[cid:B4FB22E9-6D51-42C0-8C9F-5D1B07AF74F5 at db.erau.edu]

[cid:DDD98173-74A2-4468-BEF0-AEF0E7BFE0C4 at db.erau.edu]

So it doesn’t look like sinusoid, but slowly decreasing rise/drop (to the left and right from epicenter respectfully). It takes about 10-12 minutes to fully suppress this.

I do not have it for NEX_XI=96 simulation, but for shorter period simulation it starts to appear. I tried different Earth models, but seems it doesn’t play any role.
Does it have physical nature?

And more general question - how appropriate SPECFEM3D-Globe to simulate velocities at the epicenter and positions very close to it?

Thank you in advance
Paul Inchin
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From komatitsch at lma.cnrs-mrs.fr  Mon Apr  9 03:01:59 2018
From: komatitsch at lma.cnrs-mrs.fr (Dimitri Komatitsch)
Date: Mon, 9 Apr 2018 12:01:59 +0200
Subject: [CIG-SEISMO] SPECFEM3D-Globe, near epicenter velocities
In-Reply-To: <1D5626F1-A72B-4725-80FC-7E97F619AAFD@my.erau.edu>
References: <1D5626F1-A72B-4725-80FC-7E97F619AAFD@my.erau.edu>
Message-ID: <8a575b92-fb52-7a6e-9e5f-10a387448e6a@lma.cnrs-mrs.fr>


Hi,

Yes, SPECFEM solves for the full wave equation and thus includes the 
near-field terms, computed accurately (see e.g. 
http://komatitsch.free.fr/preprints/GJI1_2002.pdf figure 20).

However, if you are in the mesh element of the source, or very close to 
it, you may get spurious Hourglass-like modes, see Schmicker et al. 2014 
(attached). When they are present, getting rid of them requires changing 
the mesh (for instance randomizing it) near the source.

Best regards,
Dimitri.

On 04/05/2018 07:39 PM, Inchin, Pavel wrote:
> Good day,
> 
> I have a problem with simulation of velocities at close to the epicenter 
> distances.
> I need to obtain surface vertical velocities with 2 km step to the North 
> (+3000 km) and South (-3000 km) from the epicenter along longitude of 
> epicenter, so I just get synthetic seismograms for every such point from 
> SPECFEM3D-Globe.
> 
> Here is a result of global simulation SPECFEM3D-Globe for NEX_XI=96 at 
> some time of simulation (20mHz-example figure). The simulation looks good.
> 
> 
> Now, I do the same simulation for NEX_XI=240 and I get a very slowly 
> decreasing rise/drop near the epicenter. Here are several figures for 
> different times (50mhz-1.32, 50mhz-2.23, 50mhz-4.02, 50mhz-6.22 files; 
> time is shown on figures - minutes from event):
> 
> 
> 
> 
> 
> So it doesn’t look like sinusoid, but slowly decreasing rise/drop (to 
> the left and right from epicenter respectfully). It takes about 10-12 
> minutes to fully suppress this.
> 
> I do not have it for NEX_XI=96 simulation, but for shorter period 
> simulation it starts to appear. I tried different Earth models, but 
> seems it doesn’t play any role.
> Does it have physical nature?
> 
> And more general question - how appropriate SPECFEM3D-Globe to simulate 
> velocities at the epicenter and positions very close to it?
> 
> Thank you in advance
> Paul Inchin

-- 
Dimitri Komatitsch, CNRS Research Director (DR CNRS)
Laboratory of Mechanics and Acoustics, Marseille, France
http://komatitsch.free.fr
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From komatitsch at lma.cnrs-mrs.fr  Mon Apr  9 03:06:20 2018
From: komatitsch at lma.cnrs-mrs.fr (Dimitri Komatitsch)
Date: Mon, 9 Apr 2018 12:06:20 +0200
Subject: [CIG-SEISMO] using SPECFEM3D fot simulating gravity
 perturbation / PS
In-Reply-To: <CAK6kgGiC08uuZf27NzE4tF9iqoZaRhaz-YTYYDe1YSTNhoNScg@mail.gmail.com>
References: <2018040222041938194616@163.com>
 <83b17ee4-0f9f-e357-9a02-14dedf24ed9e@lma.cnrs-mrs.fr>
 <4161e476-7f27-cc14-9414-5511b7c946f9@lma.cnrs-mrs.fr>
 <CAK6kgGiC08uuZf27NzE4tF9iqoZaRhaz-YTYYDe1YSTNhoNScg@mail.gmail.com>
Message-ID: <fc4fe4e3-2386-8b06-83bd-8c2b12f3daea@lma.cnrs-mrs.fr>


Dear Surendra, dear all,

Thanks a lot! I will add your paragraph below to the users manual in a 
few minutes. Very useful.

Best regards,
Dimitri.

On 04/04/2018 08:23 PM, Surendra Nadh Somala wrote:
> Dear Dimitri,
> 
> I think Yixin Yao is looking for a feature that I had implemented during 
> my Caltech days (way back in 2013) but never made it to manual, although 
> it is still in the master github repository of Specfem3D.  We had a 
> publication eventually on it in 2015 whose link is given below:
> https://authors.library.caltech.edu/58337/1/Geophys.%20J.%20Int.-2015-Harms-1416-25.pdf
> 
> The title of that article: "Transient gravity perturbations induced by 
> earthquake rupture" sounds more like what Yixin Yao asked for in the 
> first email.
> 
> The only documentation we currently have for this feature is in a 
> standalone README file that can be found here:
> doc/how_to/README_gravityPerturbation_bis.txt 
> <https://github.com/geodynamics/specfem3d/blob/ff24d4062e223aa976c338b45fd4eb568ad1558a/doc/how_to/README_gravityPerturbation_bis.txt>
> 
> Could you please add a note about this new feature in the manual where 
> you may feel relevant (probably with a clarification that this differs 
> from Martin Roland's work on gravity integrals/field calculation) and 
> request the users of this feature to cite the following article.
> Harms, J., J.-P. Ampuero, M. Barsuglia, E. Chassande-Mottin, J.-P. 
> Montagner,S. N. Somalaand B. F. Whiting (2015)/Transient gravity 
> perturbations induced by earthquake rupture/, Geophysical Journal 
> International, 201 (3), 1416-1425 doi:10.1093/gji/ggv090
> 
> Regards,
> Surendra
> 
> 
> 
> 
> 
> ___________
> *Surendra Nadh Somala*
> Assistant Professor
> Department of Civil Engineering (Block-E, 208)
> Indian Institute of Technology (IIT) Hyderabad
> Kandi, Sangareddy
> Telangana, India - 502285
> Phone : +91 (0)40 2301-8457
> http://civil.iith.ac.in/surendra/
> 
> On Tue, Apr 3, 2018 at 8:14 PM, Dimitri Komatitsch 
> <komatitsch at lma.cnrs-mrs.fr <mailto:komatitsch at lma.cnrs-mrs.fr>> wrote:
> 
> 
>     Dear Yixin Yao,
> 
>     Please also make sure you get a recent version of the code, for
>     instance by typing this:
> 
>     git clone --recursive --branch devel
>     https://github.com/geodynamics/specfem3d.git
>     <https://github.com/geodynamics/specfem3d.git>
> 
>     because the current version of the users manual says this:
> 
>     "OTHER ANNOUNCEMENT: SPECFEM3D can now perform gravity field
>     calculations in addition (or instead of) seismic wave propagation
>     only. See flag GRAVITY_INTEGRALS in file setup/constants.h.in
>     <http://constants.h.in>.
>     Please also refer to
>     http://komatitsch.free.fr/preprints/GJI_Martin_gravimetry_2017.pdf
>     <http://komatitsch.free.fr/preprints/GJI_Martin_gravimetry_2017.pdf>.
>     And yes, that is the reason why I added a falling apple on the cover
>     of the manual :-)"
> 
>     Best regards,
>     Dimitri.
> 
>     On 04/03/2018 04:38 PM, Dimitri Komatitsch wrote:
> 
> 
>         Dear Yixin Yao,
> 
>         Thank you for your interest in our work on this. You are right,
>         by lack of time the gravity integrals are not very well
>         documented in the users manual, however they are explained in
>         detail in this paper:
>         http://komatitsch.free.fr/preprints/GJI_Martin_gravimetry_2017.pdf
>         <http://komatitsch.free.fr/preprints/GJI_Martin_gravimetry_2017.pdf>
> 
>         You can also find the flags to use in file setup/constants.h.in
>         <http://constants.h.in>, there is a section with flags about
>         gravity integrals, called "gravity integral calculations".
> 
>         Best regards,
>         Dimitri.
> 
>         On 04/02/2018 04:04 PM, yaoyixin1989 at 163.com
>         <mailto:yaoyixin1989 at 163.com> wrote:
> 
>             Dear prof.,
>             I am a PhD student of Institute of Geodesy and Geophysics,
>             Chinese Academy of Sciences.I am interested in gravity
>             perturbation caused by an earthquake, and I try to do the
>             simulation by using SPECFEM3D software. These days, I have
>             searched the manual clearly, but I didn't find the detailed
>             discription about gravity perturbation.
>             What should I do, is there a detailed manual about how to
>             simulate the gravity perturbation?
>             Thank you very much for your kind consideration and I am
>             looking forward to your reply!
> 
>             Sincerely, yours
>             Yixin Yao
>             ------------------------------------------------------------------------
>             yaoyixin1989 at 163.com <mailto:yaoyixin1989 at 163.com>
> 
> 
>             _______________________________________________
>             CIG-SEISMO mailing list
>             CIG-SEISMO at geodynamics.org <mailto:CIG-SEISMO at geodynamics.org>
>             http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo
>             <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo>
> 
> 
> 
>     -- 
>     Dimitri Komatitsch, CNRS Research Director (DR CNRS)
>     Laboratory of Mechanics and Acoustics, Marseille, France
>     http://komatitsch.free.fr
>     _______________________________________________
>     CIG-SEISMO mailing list
>     CIG-SEISMO at geodynamics.org <mailto:CIG-SEISMO at geodynamics.org>
>     http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo
>     <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo>
> 
> 

-- 
Dimitri Komatitsch, CNRS Research Director (DR CNRS)
Laboratory of Mechanics and Acoustics, Marseille, France
http://komatitsch.free.fr

From INCHINP at my.erau.edu  Mon Apr  9 05:34:34 2018
From: INCHINP at my.erau.edu (Inchin, Pavel)
Date: Mon, 9 Apr 2018 12:34:34 +0000
Subject: [CIG-SEISMO] SPECFEM3D-Globe, near epicenter velocities
In-Reply-To: <8a575b92-fb52-7a6e-9e5f-10a387448e6a@lma.cnrs-mrs.fr>
References: <1D5626F1-A72B-4725-80FC-7E97F619AAFD@my.erau.edu>
 <8a575b92-fb52-7a6e-9e5f-10a387448e6a@lma.cnrs-mrs.fr>
Message-ID: <7FA93570-9F83-4F8F-AD53-7385A3AF255C@my.erau.edu>

Dr. Komatitsch

Thank you so much for help! I think this is what I need.

Yours faithfully,
Paul

> On Apr 9, 2018, at 6:01 AM, Dimitri Komatitsch <komatitsch at lma.cnrs-mrs.fr> wrote:
> 
> 
> Hi,
> 
> Yes, SPECFEM solves for the full wave equation and thus includes the near-field terms, computed accurately (see e.g. http://komatitsch.free.fr/preprints/GJI1_2002.pdf figure 20).
> 
> However, if you are in the mesh element of the source, or very close to it, you may get spurious Hourglass-like modes, see Schmicker et al. 2014 (attached). When they are present, getting rid of them requires changing the mesh (for instance randomizing it) near the source.
> 
> Best regards,
> Dimitri.
> 
> On 04/05/2018 07:39 PM, Inchin, Pavel wrote:
>> Good day,
>> I have a problem with simulation of velocities at close to the epicenter distances.
>> I need to obtain surface vertical velocities with 2 km step to the North (+3000 km) and South (-3000 km) from the epicenter along longitude of epicenter, so I just get synthetic seismograms for every such point from SPECFEM3D-Globe.
>> Here is a result of global simulation SPECFEM3D-Globe for NEX_XI=96 at some time of simulation (20mHz-example figure). The simulation looks good.
>> Now, I do the same simulation for NEX_XI=240 and I get a very slowly decreasing rise/drop near the epicenter. Here are several figures for different times (50mhz-1.32, 50mhz-2.23, 50mhz-4.02, 50mhz-6.22 files; time is shown on figures - minutes from event):
>> So it doesn’t look like sinusoid, but slowly decreasing rise/drop (to the left and right from epicenter respectfully). It takes about 10-12 minutes to fully suppress this.
>> I do not have it for NEX_XI=96 simulation, but for shorter period simulation it starts to appear. I tried different Earth models, but seems it doesn’t play any role.
>> Does it have physical nature?
>> And more general question - how appropriate SPECFEM3D-Globe to simulate velocities at the epicenter and positions very close to it?
>> Thank you in advance
>> Paul Inchin
> 
> -- 
> Dimitri Komatitsch, CNRS Research Director (DR CNRS)
> Laboratory of Mechanics and Acoustics, Marseille, France
> http://komatitsch.free.fr
> <Schmicker_et_al_SEM_spurious_Hourglass_oscillations_spurious_modes_and_explanation_2014_with_analysis_in_yellow_by_Dimitri.pdf>


From komatitsch at lma.cnrs-mrs.fr  Mon Apr  9 07:21:52 2018
From: komatitsch at lma.cnrs-mrs.fr (Dimitri Komatitsch)
Date: Mon, 9 Apr 2018 16:21:52 +0200
Subject: [CIG-SEISMO] [Specfem3D Cartesian]- Using a CMTSOLUTION source
 to trigger a critically-stressed fault
In-Reply-To: <C8EAAA77-8EEE-48F1-945A-2CFDCF3C6AF6@contoso.com>
References: <C8EAAA77-8EEE-48F1-945A-2CFDCF3C6AF6@contoso.com>
Message-ID: <191d01a8-6787-07b7-824d-0fe7960134bc@lma.cnrs-mrs.fr>


Dear Ge Li,

Thank you very much for your email and for your interest in the work of 
the community around the package.

Yes, if you want to mimic an extended source using a kinematic source 
model, you can use many CMTSOLUTION sources that are triggered at 
different times and at slightly different locations (see e.g. the 
discussion about extended sources around equation (A12) of 
http://komatitsch.free.fr/preprints/GJI_1999_figure16_error_fixed_equation3_typo_fixed.pdf, 
and the way we mimic a Hamming quasi-plane wave using 1000 such sources 
in http://komatitsch.free.fr/preprints/Ultrasonics_Moysan_2016.pdf 
figure 5).

If you want a dynamic rupture source model, i.e. something more 
sophisticated, the package can do that based on the great work of 
Jean-Paul Ampuero, Surendra Nadh Somala, Kangchen Bai and other people 
in the community, they can give you more details (they will know much 
more about this than I do :-)
Let me thus cc them.

Best regards,
Dimitri.

On 04/05/2018 03:00 AM, Ge Li wrote:
> To Whom It May Concern:
> 
> I’m a PhD Candidate in geophysics at McGill University. Currently I’m using
> 
> Specfem3D Cartesian for my research.
> 
> I’m wondering is it possible to trigger an earthquake on a fault using a 
> CMTSOLUTION source?
> 
> I tried several simulations by setting a critically stressed fault and a 
> CMTSOLUTION point source.
> 
> The source (Mw~6 Right-lateral strike slip) was located about only 1km 
> away from the fault surface.
> 
> But it turned out the stresses on the fault surface(dynamic 
> slip-weakening) remain unchanged.
> 
> Based on these tests, I supposed that a CMTSOLUTION won’t change the 
> stress level on a fault surface. Is it correct?
> 
> Or did I miss something here?
> 
> Thanks! I’m looking forward to your reply!
> 
> -- 
> 
> *Ge Li*
> 
> /Ph.D. Candidate/
> 
> /Department of Earth & Planetary Science, /
> 
> /McGill University/
> 
> /3450 University Street/
> 
> /Montreal, QC, Canada /
> 
> /H3A 0E8/
> 
> /ge.li2 at mail.mcgill.ca <mailto:ge.li2 at mail.mcgill.ca>/
> 
> 
> 
> _______________________________________________
> CIG-SEISMO mailing list
> CIG-SEISMO at geodynamics.org
> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo
> 

-- 
Dimitri Komatitsch, CNRS Research Director (DR CNRS)
Laboratory of Mechanics and Acoustics, Marseille, France
http://komatitsch.free.fr

From kbai at caltech.edu  Mon Apr  9 10:12:14 2018
From: kbai at caltech.edu (Kangchen Bai)
Date: Mon, 9 Apr 2018 10:12:14 -0700
Subject: [CIG-SEISMO] [Specfem3D Cartesian]- Using a CMTSOLUTION source
 to trigger a critically-stressed fault
In-Reply-To: <191d01a8-6787-07b7-824d-0fe7960134bc@lma.cnrs-mrs.fr>
References: <C8EAAA77-8EEE-48F1-945A-2CFDCF3C6AF6@contoso.com>
 <191d01a8-6787-07b7-824d-0fe7960134bc@lma.cnrs-mrs.fr>
Message-ID: <CAA87xUuKdqNkk99nKh6ai_d1L4K1w0CCtH2cSyQ2uai-3Fewzg@mail.gmail.com>

Hi Ge,

Triggering a dynamic rupture with a point source is do-able with the code.
You should see dynamic stress changes as the wave goes across the fault.
 I actually did similar things before by mistake --- I forgot to turn off
the point source when doing a dynamic rupture simulation and see the
circular stress pattern on the fault.

We also did the work of one fault rupture triggering another using the code
(See Bai & Ampuero 2017
https://doi.org/10.1002/2017JB014848
 ), the stress transfer is not a problem as is shown in Fig 6 & 7.

If you do not see stress changes, there must be something wrong with the
settings.
I suspect the most plausible scenario is that the fault node is not split
in which case the stress remain constant anyhow.
Let me know if you have more questions.

Best,
Kangchen

On Mon, Apr 9, 2018 at 7:21 AM, Dimitri Komatitsch <
komatitsch at lma.cnrs-mrs.fr> wrote:

>
> Dear Ge Li,
>
> Thank you very much for your email and for your interest in the work of
> the community around the package.
>
> Yes, if you want to mimic an extended source using a kinematic source
> model, you can use many CMTSOLUTION sources that are triggered at different
> times and at slightly different locations (see e.g. the discussion about
> extended sources around equation (A12) of http://komatitsch.free.fr/prep
> rints/GJI_1999_figure16_error_fixed_equation3_typo_fixed.pdf, and the way
> we mimic a Hamming quasi-plane wave using 1000 such sources in
> http://komatitsch.free.fr/preprints/Ultrasonics_Moysan_2016.pdf figure 5).
>
> If you want a dynamic rupture source model, i.e. something more
> sophisticated, the package can do that based on the great work of Jean-Paul
> Ampuero, Surendra Nadh Somala, Kangchen Bai and other people in the
> community, they can give you more details (they will know much more about
> this than I do :-)
> Let me thus cc them.
>
> Best regards,
> Dimitri.
>
> On 04/05/2018 03:00 AM, Ge Li wrote:
>
>> To Whom It May Concern:
>>
>> I’m a PhD Candidate in geophysics at McGill University. Currently I’m
>> using
>>
>> Specfem3D Cartesian for my research.
>>
>> I’m wondering is it possible to trigger an earthquake on a fault using a
>> CMTSOLUTION source?
>>
>> I tried several simulations by setting a critically stressed fault and a
>> CMTSOLUTION point source.
>>
>> The source (Mw~6 Right-lateral strike slip) was located about only 1km
>> away from the fault surface.
>>
>> But it turned out the stresses on the fault surface(dynamic
>> slip-weakening) remain unchanged.
>>
>> Based on these tests, I supposed that a CMTSOLUTION won’t change the
>> stress level on a fault surface. Is it correct?
>>
>> Or did I miss something here?
>>
>> Thanks! I’m looking forward to your reply!
>>
>> --
>>
>> *Ge Li*
>>
>> /Ph.D. Candidate/
>>
>> /Department of Earth & Planetary Science, /
>>
>> /McGill University/
>>
>> /3450 University Street/
>>
>> /Montreal, QC, Canada /
>>
>> /H3A 0E8/
>>
>> /ge.li2 at mail.mcgill.ca <mailto:ge.li2 at mail.mcgill.ca>/
>>
>>
>>
>> _______________________________________________
>> CIG-SEISMO mailing list
>> CIG-SEISMO at geodynamics.org
>> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo
>>
>>
> --
> Dimitri Komatitsch, CNRS Research Director (DR CNRS)
> Laboratory of Mechanics and Acoustics, Marseille, France
> http://komatitsch.free.fr
>
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From komatitsch at lma.cnrs-mrs.fr  Mon Apr  9 15:11:10 2018
From: komatitsch at lma.cnrs-mrs.fr (Dimitri Komatitsch)
Date: Tue, 10 Apr 2018 00:11:10 +0200
Subject: [CIG-SEISMO] using SPECFEM3D fot simulating gravity
 perturbation / PS
In-Reply-To: <fc4fe4e3-2386-8b06-83bd-8c2b12f3daea@lma.cnrs-mrs.fr>
References: <2018040222041938194616@163.com>
 <83b17ee4-0f9f-e357-9a02-14dedf24ed9e@lma.cnrs-mrs.fr>
 <4161e476-7f27-cc14-9414-5511b7c946f9@lma.cnrs-mrs.fr>
 <CAK6kgGiC08uuZf27NzE4tF9iqoZaRhaz-YTYYDe1YSTNhoNScg@mail.gmail.com>
 <fc4fe4e3-2386-8b06-83bd-8c2b12f3daea@lma.cnrs-mrs.fr>
Message-ID: <d3682a3a-eef4-2767-9320-38c32006e01e@lma.cnrs-mrs.fr>


Done!

Dimitri.

On 04/09/2018 12:06 PM, Dimitri Komatitsch wrote:
> 
> Dear Surendra, dear all,
> 
> Thanks a lot! I will add your paragraph below to the users manual in a 
> few minutes. Very useful.
> 
> Best regards,
> Dimitri.
> 
> On 04/04/2018 08:23 PM, Surendra Nadh Somala wrote:
>> Dear Dimitri,
>>
>> I think Yixin Yao is looking for a feature that I had implemented 
>> during my Caltech days (way back in 2013) but never made it to manual, 
>> although it is still in the master github repository of Specfem3D.  We 
>> had a publication eventually on it in 2015 whose link is given below:
>> https://authors.library.caltech.edu/58337/1/Geophys.%20J.%20Int.-2015-Harms-1416-25.pdf 
>>
>>
>> The title of that article: "Transient gravity perturbations induced by 
>> earthquake rupture" sounds more like what Yixin Yao asked for in the 
>> first email.
>>
>> The only documentation we currently have for this feature is in a 
>> standalone README file that can be found here:
>> doc/how_to/README_gravityPerturbation_bis.txt 
>> <https://github.com/geodynamics/specfem3d/blob/ff24d4062e223aa976c338b45fd4eb568ad1558a/doc/how_to/README_gravityPerturbation_bis.txt> 
>>
>>
>> Could you please add a note about this new feature in the manual where 
>> you may feel relevant (probably with a clarification that this differs 
>> from Martin Roland's work on gravity integrals/field calculation) and 
>> request the users of this feature to cite the following article.
>> Harms, J., J.-P. Ampuero, M. Barsuglia, E. Chassande-Mottin, J.-P. 
>> Montagner,S. N. Somalaand B. F. Whiting (2015)/Transient gravity 
>> perturbations induced by earthquake rupture/, Geophysical Journal 
>> International, 201 (3), 1416-1425 doi:10.1093/gji/ggv090
>>
>> Regards,
>> Surendra
>>
>>
>>
>>
>>
>> ___________
>> *Surendra Nadh Somala*
>> Assistant Professor
>> Department of Civil Engineering (Block-E, 208)
>> Indian Institute of Technology (IIT) Hyderabad
>> Kandi, Sangareddy
>> Telangana, India - 502285
>> Phone : +91 (0)40 2301-8457
>> http://civil.iith.ac.in/surendra/
>>
>> On Tue, Apr 3, 2018 at 8:14 PM, Dimitri Komatitsch 
>> <komatitsch at lma.cnrs-mrs.fr <mailto:komatitsch at lma.cnrs-mrs.fr>> wrote:
>>
>>
>>     Dear Yixin Yao,
>>
>>     Please also make sure you get a recent version of the code, for
>>     instance by typing this:
>>
>>     git clone --recursive --branch devel
>>     https://github.com/geodynamics/specfem3d.git
>>     <https://github.com/geodynamics/specfem3d.git>
>>
>>     because the current version of the users manual says this:
>>
>>     "OTHER ANNOUNCEMENT: SPECFEM3D can now perform gravity field
>>     calculations in addition (or instead of) seismic wave propagation
>>     only. See flag GRAVITY_INTEGRALS in file setup/constants.h.in
>>     <http://constants.h.in>.
>>     Please also refer to
>>     http://komatitsch.free.fr/preprints/GJI_Martin_gravimetry_2017.pdf
>>     <http://komatitsch.free.fr/preprints/GJI_Martin_gravimetry_2017.pdf>.
>>     And yes, that is the reason why I added a falling apple on the cover
>>     of the manual :-)"
>>
>>     Best regards,
>>     Dimitri.
>>
>>     On 04/03/2018 04:38 PM, Dimitri Komatitsch wrote:
>>
>>
>>         Dear Yixin Yao,
>>
>>         Thank you for your interest in our work on this. You are right,
>>         by lack of time the gravity integrals are not very well
>>         documented in the users manual, however they are explained in
>>         detail in this paper:
>>         
>> http://komatitsch.free.fr/preprints/GJI_Martin_gravimetry_2017.pdf
>>         
>> <http://komatitsch.free.fr/preprints/GJI_Martin_gravimetry_2017.pdf>
>>
>>         You can also find the flags to use in file setup/constants.h.in
>>         <http://constants.h.in>, there is a section with flags about
>>         gravity integrals, called "gravity integral calculations".
>>
>>         Best regards,
>>         Dimitri.
>>
>>         On 04/02/2018 04:04 PM, yaoyixin1989 at 163.com
>>         <mailto:yaoyixin1989 at 163.com> wrote:
>>
>>             Dear prof.,
>>             I am a PhD student of Institute of Geodesy and Geophysics,
>>             Chinese Academy of Sciences.I am interested in gravity
>>             perturbation caused by an earthquake, and I try to do the
>>             simulation by using SPECFEM3D software. These days, I have
>>             searched the manual clearly, but I didn't find the detailed
>>             discription about gravity perturbation.
>>             What should I do, is there a detailed manual about how to
>>             simulate the gravity perturbation?
>>             Thank you very much for your kind consideration and I am
>>             looking forward to your reply!
>>
>>             Sincerely, yours
>>             Yixin Yao
>>             
>> ------------------------------------------------------------------------
>>             yaoyixin1989 at 163.com <mailto:yaoyixin1989 at 163.com>
>>
>>
>>             _______________________________________________
>>             CIG-SEISMO mailing list
>>             CIG-SEISMO at geodynamics.org 
>> <mailto:CIG-SEISMO at geodynamics.org>
>>             
>> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo
>>             
>> <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo>
>>
>>
>>
>>     --     Dimitri Komatitsch, CNRS Research Director (DR CNRS)
>>     Laboratory of Mechanics and Acoustics, Marseille, France
>>     http://komatitsch.free.fr
>>     _______________________________________________
>>     CIG-SEISMO mailing list
>>     CIG-SEISMO at geodynamics.org <mailto:CIG-SEISMO at geodynamics.org>
>>     http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo
>>     <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo>
>>
>>
> 

-- 
Dimitri Komatitsch, CNRS Research Director (DR CNRS)
Laboratory of Mechanics and Acoustics, Marseille, France
http://komatitsch.free.fr

From ge.li2 at mail.mcgill.ca  Mon Apr  9 12:38:45 2018
From: ge.li2 at mail.mcgill.ca (Ge Li)
Date: Mon, 09 Apr 2018 15:38:45 -0400
Subject: [CIG-SEISMO] [Specfem3D Cartesian]- Using a CMTSOLUTION source
 to trigger a critically-stressed fault
In-Reply-To: <CAA87xUuKdqNkk99nKh6ai_d1L4K1w0CCtH2cSyQ2uai-3Fewzg@mail.gmail.com>
References: <C8EAAA77-8EEE-48F1-945A-2CFDCF3C6AF6@contoso.com>
 <191d01a8-6787-07b7-824d-0fe7960134bc@lma.cnrs-mrs.fr>
 <CAA87xUuKdqNkk99nKh6ai_d1L4K1w0CCtH2cSyQ2uai-3Fewzg@mail.gmail.com>
Message-ID: <B4D69DEA-A452-4815-8A68-4B448F7F5739@mail.mcgill.ca>

Hi Kangchen and Dimitri,

Thanks for your reply!

Kangchen, can you give me more explanations on ‘fault-node splitting’?

Do you mean the split-node technique used during the mesh process? I followed the 

instructions provided in the specfem3d manual to create a Cubit mesh file. The 

mesh works well for a ‘step-over’ scenario and I did observe the  dynamic stress transfer.

Back to the test mentioned in my previous email, where I put a point source 

(Mw~6 Right-lateral strike slip) about only 1km away from the fault surface. I also observed

 stress changes, but with a magnitude of ~  0.0682Pa. Considering the initial stress level of 

82.1MPa, I suspected these stress changes are numerical?

 

Also is it possible to implement both dynamic and kinematic fault in a model, i.e. one fault is

Kinematic and the other one is dynamic.

 

Thanks !

Best regards,

Ge

 

 

From: Kangchen Bai <kbai at caltech.edu>
Date: Monday, April 9, 2018 at 1:12 PM
To: Dimitri Komatitsch <komatitsch at lma.cnrs-mrs.fr>
Cc: <cig-seismo at geodynamics.org>, Ge Li <ge.li2 at mail.mcgill.ca>, Surendra Nadh Somala <surendra at iith.ac.in>, <ampuero at geoazur.unice.fr>
Subject: Re: [CIG-SEISMO] [Specfem3D Cartesian]- Using a CMTSOLUTION source to trigger a critically-stressed fault

 

Hi Ge,

 

Triggering a dynamic rupture with a point source is do-able with the code. You should see dynamic stress changes as the wave goes across the fault.

 I actually did similar things before by mistake --- I forgot to turn off the point source when doing a dynamic rupture simulation and see the circular stress pattern on the fault. 

 

We also did the work of one fault rupture triggering another using the code (See Bai & Ampuero 2017 

https://doi.org/10.1002/2017JB014848 

 ), the stress transfer is not a problem as is shown in Fig 6 & 7.

 

If you do not see stress changes, there must be something wrong with the settings. 

I suspect the most plausible scenario is that the fault node is not split in which case the stress remain constant anyhow.

Let me know if you have more questions.

 

Best,

Kangchen

 

On Mon, Apr 9, 2018 at 7:21 AM, Dimitri Komatitsch <komatitsch at lma.cnrs-mrs.fr> wrote:


Dear Ge Li,

Thank you very much for your email and for your interest in the work of the community around the package.

Yes, if you want to mimic an extended source using a kinematic source model, you can use many CMTSOLUTION sources that are triggered at different times and at slightly different locations (see e.g. the discussion about extended sources around equation (A12) of http://komatitsch.free.fr/preprints/GJI_1999_figure16_error_fixed_equation3_typo_fixed.pdf, and the way we mimic a Hamming quasi-plane wave using 1000 such sources in http://komatitsch.free.fr/preprints/Ultrasonics_Moysan_2016.pdf figure 5).

If you want a dynamic rupture source model, i.e. something more sophisticated, the package can do that based on the great work of Jean-Paul Ampuero, Surendra Nadh Somala, Kangchen Bai and other people in the community, they can give you more details (they will know much more about this than I do :-)
Let me thus cc them.

Best regards,
Dimitri.

On 04/05/2018 03:00 AM, Ge Li wrote:

To Whom It May Concern:

I’m a PhD Candidate in geophysics at McGill University. Currently I’m using

Specfem3D Cartesian for my research.

I’m wondering is it possible to trigger an earthquake on a fault using a CMTSOLUTION source?

I tried several simulations by setting a critically stressed fault and a CMTSOLUTION point source.

The source (Mw~6 Right-lateral strike slip) was located about only 1km away from the fault surface.

But it turned out the stresses on the fault surface(dynamic slip-weakening) remain unchanged.

Based on these tests, I supposed that a CMTSOLUTION won’t change the stress level on a fault surface. Is it correct?

Or did I miss something here?

Thanks! I’m looking forward to your reply!

-- 

*Ge Li*

/Ph.D. Candidate/

/Department of Earth & Planetary Science, /

/McGill University/

/3450 University Street/

/Montreal, QC, Canada /

/H3A 0E8/

/ge.li2 at mail.mcgill.ca <mailto:ge.li2 at mail.mcgill.ca>/



_______________________________________________
CIG-SEISMO mailing list
CIG-SEISMO at geodynamics.org
http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo


-- 
Dimitri Komatitsch, CNRS Research Director (DR CNRS)
Laboratory of Mechanics and Acoustics, Marseille, France
http://komatitsch.free.fr

 

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From surendra at iith.ac.in  Tue Apr 10 00:01:41 2018
From: surendra at iith.ac.in (Surendra Nadh Somala)
Date: Tue, 10 Apr 2018 12:31:41 +0530
Subject: [CIG-SEISMO] [Specfem3D Cartesian]- Using a CMTSOLUTION source
 to trigger a critically-stressed fault
In-Reply-To: <B4D69DEA-A452-4815-8A68-4B448F7F5739@mail.mcgill.ca>
References: <C8EAAA77-8EEE-48F1-945A-2CFDCF3C6AF6@contoso.com>
 <191d01a8-6787-07b7-824d-0fe7960134bc@lma.cnrs-mrs.fr>
 <CAA87xUuKdqNkk99nKh6ai_d1L4K1w0CCtH2cSyQ2uai-3Fewzg@mail.gmail.com>
 <B4D69DEA-A452-4815-8A68-4B448F7F5739@mail.mcgill.ca>
Message-ID: <CAK6kgGj5SB5MYn0U2JDwi_pXLmbVEDTBFGFTZv_nJoRGJVrnkw@mail.gmail.com>

Dear Ge,

Currently, the implementation is such that all the fault in a particular
simulation should be either Kinematic or Dynamic.
Nevertheless, you can run a kinematic simulation, observe the stress
changes on the other fault and setup a dynamic rupture simulation based on
the updated stresses.

Btw, what is the magnitude of the point source (CMTSOLUTION) you have put
in your simulation?

Best,
Surendra


___________
*Surendra Nadh Somala*
Assistant Professor
Department of Civil Engineering (Block-E, 208)
Indian Institute of Technology (IIT) Hyderabad
Kandi, Sangareddy
Telangana, India - 502285
Phone : +91 (0)40 2301-8457
http://civil.iith.ac.in/surendra/

On Tue, Apr 10, 2018 at 1:08 AM, Ge Li <ge.li2 at mail.mcgill.ca> wrote:

> Hi Kangchen and Dimitri,
>
> Thanks for your reply!
>
> Kangchen, can you give me more explanations on ‘fault-node splitting’?
>
> Do you mean the split-node technique used during the mesh process? I
> followed the
>
> instructions provided in the specfem3d manual to create a Cubit mesh file.
> The
>
> mesh works well for a ‘step-over’ scenario and I did observe the  dynamic
> stress transfer.
>
> Back to the test mentioned in my previous email, where I put a point
> source
>
> (Mw~6 Right-lateral strike slip) about only 1km away from the fault
> surface. I also observed
>
> stress changes, but with a magnitude of ~  0.0682Pa. Considering the
> initial stress level of
>
> 82.1MPa, I suspected these stress changes are numerical?
>
>
>
> Also is it possible to implement both dynamic and kinematic fault in a
> model, i.e. one fault is
>
> Kinematic and the other one is dynamic.
>
>
>
> Thanks !
>
> Best regards,
>
> Ge
>
>
>
>
>
> *From: *Kangchen Bai <kbai at caltech.edu>
> *Date: *Monday, April 9, 2018 at 1:12 PM
> *To: *Dimitri Komatitsch <komatitsch at lma.cnrs-mrs.fr>
> *Cc: *<cig-seismo at geodynamics.org>, Ge Li <ge.li2 at mail.mcgill.ca>,
> Surendra Nadh Somala <surendra at iith.ac.in>, <ampuero at geoazur.unice.fr>
> *Subject: *Re: [CIG-SEISMO] [Specfem3D Cartesian]- Using a CMTSOLUTION
> source to trigger a critically-stressed fault
>
>
>
> Hi Ge,
>
>
>
> Triggering a dynamic rupture with a point source is do-able with the code.
> You should see dynamic stress changes as the wave goes across the fault.
>
>  I actually did similar things before by mistake --- I forgot to turn off
> the point source when doing a dynamic rupture simulation and see the
> circular stress pattern on the fault.
>
>
>
> We also did the work of one fault rupture triggering another using the
> code (See Bai & Ampuero 2017
>
> https://doi.org/10.1002/2017JB014848
> <https://doi.org/10.1002/2017JB014848%20>
>
>  ), the stress transfer is not a problem as is shown in Fig 6 & 7.
>
>
>
> If you do not see stress changes, there must be something wrong with the
> settings.
>
> I suspect the most plausible scenario is that the fault node is not split
> in which case the stress remain constant anyhow.
>
> Let me know if you have more questions.
>
>
>
> Best,
>
> Kangchen
>
>
>
> On Mon, Apr 9, 2018 at 7:21 AM, Dimitri Komatitsch <
> komatitsch at lma.cnrs-mrs.fr> wrote:
>
>
> Dear Ge Li,
>
> Thank you very much for your email and for your interest in the work of
> the community around the package.
>
> Yes, if you want to mimic an extended source using a kinematic source
> model, you can use many CMTSOLUTION sources that are triggered at different
> times and at slightly different locations (see e.g. the discussion about
> extended sources around equation (A12) of http://komatitsch.free.fr/
> preprints/GJI_1999_figure16_error_fixed_equation3_typo_fixed.pdf, and the
> way we mimic a Hamming quasi-plane wave using 1000 such sources in
> http://komatitsch.free.fr/preprints/Ultrasonics_Moysan_2016.pdf figure 5).
>
> If you want a dynamic rupture source model, i.e. something more
> sophisticated, the package can do that based on the great work of Jean-Paul
> Ampuero, Surendra Nadh Somala, Kangchen Bai and other people in the
> community, they can give you more details (they will know much more about
> this than I do :-)
> Let me thus cc them.
>
> Best regards,
> Dimitri.
>
> On 04/05/2018 03:00 AM, Ge Li wrote:
>
> To Whom It May Concern:
>
> I’m a PhD Candidate in geophysics at McGill University. Currently I’m using
>
> Specfem3D Cartesian for my research.
>
> I’m wondering is it possible to trigger an earthquake on a fault using a
> CMTSOLUTION source?
>
> I tried several simulations by setting a critically stressed fault and a
> CMTSOLUTION point source.
>
> The source (Mw~6 Right-lateral strike slip) was located about only 1km
> away from the fault surface.
>
> But it turned out the stresses on the fault surface(dynamic
> slip-weakening) remain unchanged.
>
> Based on these tests, I supposed that a CMTSOLUTION won’t change the
> stress level on a fault surface. Is it correct?
>
> Or did I miss something here?
>
> Thanks! I’m looking forward to your reply!
>
> --
>
> *Ge Li*
>
> /Ph.D. Candidate/
>
> /Department of Earth & Planetary Science, /
>
> /McGill University/
> <https://maps.google.com/?q=University/+/3450+University+Street/+/Montreal,+QC,+Canada+/+/H3A&entry=gmail&source=g>
>
> /3450 University Street/
> <https://maps.google.com/?q=University/+/3450+University+Street/+/Montreal,+QC,+Canada+/+/H3A&entry=gmail&source=g>
>
> /Montreal, QC, Canada /
> <https://maps.google.com/?q=University/+/3450+University+Street/+/Montreal,+QC,+Canada+/+/H3A&entry=gmail&source=g>
>
> /H3A
> <https://maps.google.com/?q=University/+/3450+University+Street/+/Montreal,+QC,+Canada+/+/H3A&entry=gmail&source=g>
> 0E8/
>
> /ge.li2 at mail.mcgill.ca <mailto:ge.li2 at mail.mcgill.ca>/
>
>
>
> _______________________________________________
> CIG-SEISMO mailing list
> CIG-SEISMO at geodynamics.org
> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo
>
>
> --
> Dimitri Komatitsch, CNRS Research Director (DR CNRS)
> Laboratory of Mechanics and Acoustics, Marseille, France
> http://komatitsch.free.fr
>
>
>
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From ge.li2 at mail.mcgill.ca  Tue Apr 10 07:08:31 2018
From: ge.li2 at mail.mcgill.ca (Ge Li)
Date: Tue, 10 Apr 2018 10:08:31 -0400
Subject: [CIG-SEISMO] [Specfem3D Cartesian]- Using a CMTSOLUTION source
 to trigger a critically-stressed fault
In-Reply-To: <CAK6kgGj5SB5MYn0U2JDwi_pXLmbVEDTBFGFTZv_nJoRGJVrnkw@mail.gmail.com>
References: <C8EAAA77-8EEE-48F1-945A-2CFDCF3C6AF6@contoso.com>
 <191d01a8-6787-07b7-824d-0fe7960134bc@lma.cnrs-mrs.fr>
 <CAA87xUuKdqNkk99nKh6ai_d1L4K1w0CCtH2cSyQ2uai-3Fewzg@mail.gmail.com>
 <B4D69DEA-A452-4815-8A68-4B448F7F5739@mail.mcgill.ca>
 <CAK6kgGj5SB5MYn0U2JDwi_pXLmbVEDTBFGFTZv_nJoRGJVrnkw@mail.gmail.com>
Message-ID: <6C032A0C-E5BC-4DDB-B699-58FA36841F4F@mail.mcgill.ca>

Thank you, Surendra!

I figured out how to deal with it after talking to Kangchen.

I put a Mw 6.2 Right-lateral EQ 1km away from a dynamic fault.

This scenario results in a dynamic stress changes of ~0.5MPa 

The results look reasonable to me.

Best,

Ge

From: Surendra Nadh Somala <surendra at iith.ac.in>
Date: Tuesday, April 10, 2018 at 3:01 AM
To: Ge Li <ge.li2 at mail.mcgill.ca>
Cc: Kangchen Bai <kbai at caltech.edu>, Dimitri Komatitsch <komatitsch at lma.cnrs-mrs.fr>, <cig-seismo at geodynamics.org>, <ampuero at geoazur.unice.fr>
Subject: Re: [CIG-SEISMO] [Specfem3D Cartesian]- Using a CMTSOLUTION source to trigger a critically-stressed fault

 

Dear Ge,

 

Currently, the implementation is such that all the fault in a particular simulation should be either Kinematic or Dynamic.

Nevertheless, you can run a kinematic simulation, observe the stress changes on the other fault and setup a dynamic rupture simulation based on the updated stresses.

 

Btw, what is the magnitude of the point source (CMTSOLUTION) you have put in your simulation?

 

Best,

Surendra

 


___________

Surendra Nadh Somala

Assistant Professor
Department of Civil Engineering (Block-E, 208)
Indian Institute of Technology (IIT) Hyderabad

Kandi, Sangareddy
Telangana, India - 502285

Phone : +91 (0)40 2301-8457 

http://civil.iith.ac.in/surendra/ 

 

On Tue, Apr 10, 2018 at 1:08 AM, Ge Li <ge.li2 at mail.mcgill.ca> wrote:

Hi Kangchen and Dimitri,

Thanks for your reply!

Kangchen, can you give me more explanations on ‘fault-node splitting’?

Do you mean the split-node technique used during the mesh process? I followed the 

instructions provided in the specfem3d manual to create a Cubit mesh file. The 

mesh works well for a ‘step-over’ scenario and I did observe the  dynamic stress transfer.

Back to the test mentioned in my previous email, where I put a point source 

(Mw~6 Right-lateral strike slip) about only 1km away from the fault surface. I also observed

stress changes, but with a magnitude of ~  0.0682Pa. Considering the initial stress level of 

82.1MPa, I suspected these stress changes are numerical?

 

Also is it possible to implement both dynamic and kinematic fault in a model, i.e. one fault is

Kinematic and the other one is dynamic.

 

Thanks !

Best regards,

Ge

 

 

From: Kangchen Bai <kbai at caltech.edu>
Date: Monday, April 9, 2018 at 1:12 PM
To: Dimitri Komatitsch <komatitsch at lma.cnrs-mrs.fr>
Cc: <cig-seismo at geodynamics.org>, Ge Li <ge.li2 at mail.mcgill.ca>, Surendra Nadh Somala <surendra at iith.ac.in>, <ampuero at geoazur.unice.fr>
Subject: Re: [CIG-SEISMO] [Specfem3D Cartesian]- Using a CMTSOLUTION source to trigger a critically-stressed fault

 

Hi Ge,

 

Triggering a dynamic rupture with a point source is do-able with the code. You should see dynamic stress changes as the wave goes across the fault.

 I actually did similar things before by mistake --- I forgot to turn off the point source when doing a dynamic rupture simulation and see the circular stress pattern on the fault. 

 

We also did the work of one fault rupture triggering another using the code (See Bai & Ampuero 2017 

https://doi.org/10.1002/2017JB014848 

 ), the stress transfer is not a problem as is shown in Fig 6 & 7.

 

If you do not see stress changes, there must be something wrong with the settings. 

I suspect the most plausible scenario is that the fault node is not split in which case the stress remain constant anyhow.

Let me know if you have more questions.

 

Best,

Kangchen

 

On Mon, Apr 9, 2018 at 7:21 AM, Dimitri Komatitsch <komatitsch at lma.cnrs-mrs.fr> wrote:


Dear Ge Li,

Thank you very much for your email and for your interest in the work of the community around the package.

Yes, if you want to mimic an extended source using a kinematic source model, you can use many CMTSOLUTION sources that are triggered at different times and at slightly different locations (see e.g. the discussion about extended sources around equation (A12) of http://komatitsch.free.fr/preprints/GJI_1999_figure16_error_fixed_equation3_typo_fixed.pdf, and the way we mimic a Hamming quasi-plane wave using 1000 such sources in http://komatitsch.free.fr/preprints/Ultrasonics_Moysan_2016.pdf figure 5).

If you want a dynamic rupture source model, i.e. something more sophisticated, the package can do that based on the great work of Jean-Paul Ampuero, Surendra Nadh Somala, Kangchen Bai and other people in the community, they can give you more details (they will know much more about this than I do :-)
Let me thus cc them.

Best regards,
Dimitri.

On 04/05/2018 03:00 AM, Ge Li wrote:

To Whom It May Concern:

I’m a PhD Candidate in geophysics at McGill University. Currently I’m using

Specfem3D Cartesian for my research.

I’m wondering is it possible to trigger an earthquake on a fault using a CMTSOLUTION source?

I tried several simulations by setting a critically stressed fault and a CMTSOLUTION point source.

The source (Mw~6 Right-lateral strike slip) was located about only 1km away from the fault surface.

But it turned out the stresses on the fault surface(dynamic slip-weakening) remain unchanged.

Based on these tests, I supposed that a CMTSOLUTION won’t change the stress level on a fault surface. Is it correct?

Or did I miss something here?

Thanks! I’m looking forward to your reply!

-- 

*Ge Li*

/Ph.D. Candidate/

/Department of Earth & Planetary Science, /

/McGill University/

/3450 University Street/

/Montreal, QC, Canada /

/H3A 0E8/

/ge.li2 at mail.mcgill.ca <mailto:ge.li2 at mail.mcgill.ca>/



_______________________________________________
CIG-SEISMO mailing list
CIG-SEISMO at geodynamics.org
http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo


-- 
Dimitri Komatitsch, CNRS Research Director (DR CNRS)
Laboratory of Mechanics and Acoustics, Marseille, France
http://komatitsch.free.fr

 

 

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From ampuero at geoazur.unice.fr  Tue Apr 10 07:39:57 2018
From: ampuero at geoazur.unice.fr (AMPUERO Jean-Paul)
Date: Tue, 10 Apr 2018 16:39:57 +0200
Subject: [CIG-SEISMO] [Specfem3D Cartesian]- Using a CMTSOLUTION source
 to trigger a critically-stressed fault
In-Reply-To: <6C032A0C-E5BC-4DDB-B699-58FA36841F4F@mail.mcgill.ca>
References: <C8EAAA77-8EEE-48F1-945A-2CFDCF3C6AF6@contoso.com>
 <191d01a8-6787-07b7-824d-0fe7960134bc@lma.cnrs-mrs.fr>
 <CAA87xUuKdqNkk99nKh6ai_d1L4K1w0CCtH2cSyQ2uai-3Fewzg@mail.gmail.com>
 <B4D69DEA-A452-4815-8A68-4B448F7F5739@mail.mcgill.ca>
 <CAK6kgGj5SB5MYn0U2JDwi_pXLmbVEDTBFGFTZv_nJoRGJVrnkw@mail.gmail.com>
 <6C032A0C-E5BC-4DDB-B699-58FA36841F4F@mail.mcgill.ca>
Message-ID: <20180410163957.Horde.kxzPDAgfiLLyMOZZGsCI81S@webmail.geoazur.fr>

Dear Ge,

You may find in the following paper some insight on the conditions  
required to trigger an earthquake in your simulations:

M. Galis, J. P. Ampuero, P. M. Mai and F. Cappa (2017)
Induced seismicity provides insight into why earthquake ruptures stop
Science Advances, 3 (12), eaap7528, doi:10.1126/sciadv.aap7528
http://dx.doi.org/10.1126/sciadv.aap7528

Static triggering can be directly addressed with the analytical theory  
developed therein. Dynamic triggering maybe not, but at least the  
result can serve as reference.

Best,

JP Ampuero

Quoting Ge Li <ge.li2 at mail.mcgill.ca>:

> Thank you, Surendra!
>
> I figured out how to deal with it after talking to Kangchen.
>
> I put a Mw 6.2 Right-lateral EQ 1km away from a dynamic fault.
>
> This scenario results in a dynamic stress changes of ~0.5MPa
>
> The results look reasonable to me.
>
> Best,
>
> Ge
>
> From: Surendra Nadh Somala <surendra at iith.ac.in>
> Date: Tuesday, April 10, 2018 at 3:01 AM
> To: Ge Li <ge.li2 at mail.mcgill.ca>
> Cc: Kangchen Bai <kbai at caltech.edu>, Dimitri Komatitsch  
> <komatitsch at lma.cnrs-mrs.fr>, <cig-seismo at geodynamics.org>,  
> <ampuero at geoazur.unice.fr>
> Subject: Re: [CIG-SEISMO] [Specfem3D Cartesian]- Using a CMTSOLUTION  
> source to trigger a critically-stressed fault
>
>
>
> Dear Ge,
>
>
>
> Currently, the implementation is such that all the fault in a  
> particular simulation should be either Kinematic or Dynamic.
>
> Nevertheless, you can run a kinematic simulation, observe the stress  
> changes on the other fault and setup a dynamic rupture simulation  
> based on the updated stresses.
>
>
>
> Btw, what is the magnitude of the point source (CMTSOLUTION) you  
> have put in your simulation?
>
>
>
> Best,
>
> Surendra
>
>
>
>
> ___________
>
> Surendra Nadh Somala
>
> Assistant Professor
> Department of Civil Engineering (Block-E, 208)
> Indian Institute of Technology (IIT) Hyderabad
>
> Kandi, Sangareddy
> Telangana, India - 502285
>
> Phone : +91 (0)40 2301-8457
>
> http://civil.iith.ac.in/surendra/
>
>
>
> On Tue, Apr 10, 2018 at 1:08 AM, Ge Li <ge.li2 at mail.mcgill.ca> wrote:
>
> Hi Kangchen and Dimitri,
>
> Thanks for your reply!
>
> Kangchen, can you give me more explanations on ‘fault-node splitting’?
>
> Do you mean the split-node technique used during the mesh process? I  
> followed the
>
> instructions provided in the specfem3d manual to create a Cubit mesh  
> file. The
>
> mesh works well for a ‘step-over’ scenario and I did observe the   
> dynamic stress transfer.
>
> Back to the test mentioned in my previous email, where I put a point source
>
> (Mw~6 Right-lateral strike slip) about only 1km away from the fault  
> surface. I also observed
>
> stress changes, but with a magnitude of ~  0.0682Pa. Considering the  
> initial stress level of
>
> 82.1MPa, I suspected these stress changes are numerical?
>
>
>
> Also is it possible to implement both dynamic and kinematic fault in  
> a model, i.e. one fault is
>
> Kinematic and the other one is dynamic.
>
>
>
> Thanks !
>
> Best regards,
>
> Ge
>
>
>
>
>
> From: Kangchen Bai <kbai at caltech.edu>
> Date: Monday, April 9, 2018 at 1:12 PM
> To: Dimitri Komatitsch <komatitsch at lma.cnrs-mrs.fr>
> Cc: <cig-seismo at geodynamics.org>, Ge Li <ge.li2 at mail.mcgill.ca>,  
> Surendra Nadh Somala <surendra at iith.ac.in>, <ampuero at geoazur.unice.fr>
> Subject: Re: [CIG-SEISMO] [Specfem3D Cartesian]- Using a CMTSOLUTION  
> source to trigger a critically-stressed fault
>
>
>
> Hi Ge,
>
>
>
> Triggering a dynamic rupture with a point source is do-able with the  
> code. You should see dynamic stress changes as the wave goes across  
> the fault.
>
>  I actually did similar things before by mistake --- I forgot to  
> turn off the point source when doing a dynamic rupture simulation  
> and see the circular stress pattern on the fault.
>
>
>
> We also did the work of one fault rupture triggering another using  
> the code (See Bai & Ampuero 2017
>
> https://doi.org/10.1002/2017JB014848
>
>  ), the stress transfer is not a problem as is shown in Fig 6 & 7.
>
>
>
> If you do not see stress changes, there must be something wrong with  
> the settings.
>
> I suspect the most plausible scenario is that the fault node is not  
> split in which case the stress remain constant anyhow.
>
> Let me know if you have more questions.
>
>
>
> Best,
>
> Kangchen
>
>
>
> On Mon, Apr 9, 2018 at 7:21 AM, Dimitri Komatitsch  
> <komatitsch at lma.cnrs-mrs.fr> wrote:
>
>
> Dear Ge Li,
>
> Thank you very much for your email and for your interest in the work  
> of the community around the package.
>
> Yes, if you want to mimic an extended source using a kinematic  
> source model, you can use many CMTSOLUTION sources that are  
> triggered at different times and at slightly different locations  
> (see e.g. the discussion about extended sources around equation  
> (A12) of  
> http://komatitsch.free.fr/preprints/GJI_1999_figure16_error_fixed_equation3_typo_fixed.pdf, and the way we mimic a Hamming quasi-plane wave using 1000 such sources in http://komatitsch.free.fr/preprints/Ultrasonics_Moysan_2016.pdf figure  
> 5).
>
> If you want a dynamic rupture source model, i.e. something more  
> sophisticated, the package can do that based on the great work of  
> Jean-Paul Ampuero, Surendra Nadh Somala, Kangchen Bai and other  
> people in the community, they can give you more details (they will  
> know much more about this than I do :-)
> Let me thus cc them.
>
> Best regards,
> Dimitri.
>
> On 04/05/2018 03:00 AM, Ge Li wrote:
>
> To Whom It May Concern:
>
> I’m a PhD Candidate in geophysics at McGill University. Currently I’m using
>
> Specfem3D Cartesian for my research.
>
> I’m wondering is it possible to trigger an earthquake on a fault  
> using a CMTSOLUTION source?
>
> I tried several simulations by setting a critically stressed fault  
> and a CMTSOLUTION point source.
>
> The source (Mw~6 Right-lateral strike slip) was located about only  
> 1km away from the fault surface.
>
> But it turned out the stresses on the fault surface(dynamic  
> slip-weakening) remain unchanged.
>
> Based on these tests, I supposed that a CMTSOLUTION won’t change the  
> stress level on a fault surface. Is it correct?
>
> Or did I miss something here?
>
> Thanks! I’m looking forward to your reply!
>
> --
>
> *Ge Li*
>
> /Ph.D. Candidate/
>
> /Department of Earth & Planetary Science, /
>
> /McGill University/
>
> /3450 University Street/
>
> /Montreal, QC, Canada /
>
> /H3A 0E8/
>
> /ge.li2 at mail.mcgill.ca <mailto:ge.li2 at mail.mcgill.ca>/
>
>
>
> _______________________________________________
> CIG-SEISMO mailing list
> CIG-SEISMO at geodynamics.org
> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo


-- 
Jean-Paul Ampuero
Directeur de Recherche
Géoazur, Institut de Recherche pour le Développement / Université Côte d'Azur
http://geoazur.oca.eu
@DocTerremoto

From ljhwang at ucdavis.edu  Mon Apr 16 09:29:05 2018
From: ljhwang at ucdavis.edu (Lorraine Hwang)
Date: Mon, 16 Apr 2018 09:29:05 -0700
Subject: [CIG-SEISMO] CIG Webinar 4/17 *** TOMORROW ***: New developments in
 AxiSEM/Instaseis for seismic wave propagation on local scales
Message-ID: <4E8E32ED-3C2A-4BEE-8519-587DC1DCBBB0@ucdavis.edu>

TUESDAY, APRIL 17 @11A PT 
New developments in AxiSEM/Instaseis for seismic wave propagation on local scales

Lion Krischer, Tarje Nissen-Meyer, Simon Staehler, and Martin van Driel, ETH Zurich

Instaseis (http://instaseis.net <http://instaseis.net/> <http://instaseis.net/ <http://instaseis.net/>) is a Python tool to quickly extract high-frequency seismograms for any source-receiver geometry from databases generated with AxiSEM (http://axisem.info/ <http://axisem.info/>). So far it has been limited to global datasets, which in turn limited the maximum frequencies due to exploding storage requirements; a number of global databases are hosted by the IRIS DMC (http://ds.iris.edu/ds/products/syngine/ <http://ds.iris.edu/ds/products/syngine/>). We recently expanded the AxiSEM/Instaseis combination to additionally handle local scale simulations as well as databases, which enables much higher frequencies. 

In this webinar, we present a short overview of the theory behind AxiSEM/Instaseis, highlight the new extensions for local scale simulations and databases, and show a short practical tutorial on how to use it. 

Click the link below to join the webinar using zoom on your PC, Mac, Linux, iOS or Android:

https://zoom.us/j/384711375 <https://zoom.us/j/384711375>
Registration is required. Please log in early.

For more information on this and other CIG webinars, please visit us at: https://geodynamics.org/cig/events/webinars/ <https://geodynamics.org/cig/events/webinars/>




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From avinash07guddu at gmail.com  Mon Apr 16 14:21:13 2018
From: avinash07guddu at gmail.com (Avinash Nayak)
Date: Mon, 16 Apr 2018 16:21:13 -0500
Subject: [CIG-SEISMO] CIG Webinar 4/17 *** TOMORROW ***: New
 developments in AxiSEM/Instaseis for seismic wave propagation on local
 scales
In-Reply-To: <4E8E32ED-3C2A-4BEE-8519-587DC1DCBBB0@ucdavis.edu>
References: <4E8E32ED-3C2A-4BEE-8519-587DC1DCBBB0@ucdavis.edu>
Message-ID: <CA+ebHSeSujsrSJxL3z=zPJQNx4jLKQVstDH64JO2Dd3fzjpUHw@mail.gmail.com>

Hi Lorraine,
Sorry for this email. Can you please confirm the time of the meeting. The
email says 11 AM Pacific Time but when I click on the zoom link it shows
the option of 2 PM Pacific Time. There might be something wrong with my
computer.
Thanks.
Avinash

On Mon, Apr 16, 2018 at 11:29 AM, Lorraine Hwang <ljhwang at ucdavis.edu>
wrote:

>
> *TUESDAY, APRIL 17 @11A PT New developments in AxiSEM/Instaseis for
> seismic wave propagation on local scales*
>
> *Lion Krischer, Tarje Nissen-Meyer, Simon Staehler, and Martin van Driel,
> ETH Zurich*
>
> Instaseis (http://instaseis.net <http://instaseis.net/) is a Python tool
> to quickly extract high-frequency seismograms for any source-receiver
> geometry from databases generated with AxiSEM (http://axisem.info/). So
> far it has been limited to global datasets, which in turn limited the
> maximum frequencies due to exploding storage requirements; a number of
> global databases are hosted by the IRIS DMC (http://ds.iris.edu/ds/
> products/syngine/). We recently expanded the AxiSEM/Instaseis combination
> to additionally handle local scale simulations as well as databases, which
> enables much higher frequencies.
>
> In this webinar, we present a short overview of the theory behind
> AxiSEM/Instaseis, highlight the new extensions for local scale simulations
> and databases, and show a short practical tutorial on how to use it.
>
> Click the link below to join the webinar using zoom on your PC, Mac,
> Linux, iOS or Android:
>
> https://zoom.us/j/384711375
> Registration is required. Please log in early.
>
> For more information on this and other CIG webinars, please visit us at:
> https://geodynamics.org/cig/events/webinars/
>
>
>
>
>
> _______________________________________________
> CIG-SEISMO mailing list
> CIG-SEISMO at geodynamics.org
> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo
>



-- 
Avinash Nayak,
Research Associate,
Department of Geoscience,
University of Wisconsin, Madison
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From ljhwang at ucdavis.edu  Mon Apr 16 14:51:38 2018
From: ljhwang at ucdavis.edu (Lorraine Hwang)
Date: Mon, 16 Apr 2018 14:51:38 -0700
Subject: [CIG-SEISMO] CIG Webinar 4/17 *** TOMORROW ***: New
 developments in AxiSEM/Instaseis for seismic wave propagation on local
 scales
In-Reply-To: <CA+ebHSeSujsrSJxL3z=zPJQNx4jLKQVstDH64JO2Dd3fzjpUHw@mail.gmail.com>
References: <4E8E32ED-3C2A-4BEE-8519-587DC1DCBBB0@ucdavis.edu>
 <CA+ebHSeSujsrSJxL3z=zPJQNx4jLKQVstDH64JO2Dd3fzjpUHw@mail.gmail.com>
Message-ID: <9B21A8DD-5DFE-4553-9328-C54387E1FE67@ucdavis.edu>

Thanks for pointing this out. I was wondering where that  was being generated.

It should be corrected. The webinar will be at 11A PT

Thanks.

Best,
-Lorraine

*****************************
Lorraine Hwang, Ph.D.
Associate Director, CIG
530.752.3656



> On Apr 16, 2018, at 2:21 PM, Avinash Nayak <avinash07guddu at gmail.com> wrote:
> 
> Hi Lorraine,
> Sorry for this email. Can you please confirm the time of the meeting. The email says 11 AM Pacific Time but when I click on the zoom link it shows the option of 2 PM Pacific Time. There might be something wrong with my computer.
> Thanks.
> Avinash
> 
> On Mon, Apr 16, 2018 at 11:29 AM, Lorraine Hwang <ljhwang at ucdavis.edu <mailto:ljhwang at ucdavis.edu>> wrote:
> TUESDAY, APRIL 17 @11A PT 
> New developments in AxiSEM/Instaseis for seismic wave propagation on local scales
> 
> Lion Krischer, Tarje Nissen-Meyer, Simon Staehler, and Martin van Driel, ETH Zurich
> 
> Instaseis (http://instaseis.net <http://instaseis.net/> <http://instaseis.net/ <http://instaseis.net/>) is a Python tool to quickly extract high-frequency seismograms for any source-receiver geometry from databases generated with AxiSEM (http://axisem.info/ <http://axisem.info/>). So far it has been limited to global datasets, which in turn limited the maximum frequencies due to exploding storage requirements; a number of global databases are hosted by the IRIS DMC (http://ds.iris.edu/ds/products/syngine/ <http://ds.iris.edu/ds/products/syngine/>). We recently expanded the AxiSEM/Instaseis combination to additionally handle local scale simulations as well as databases, which enables much higher frequencies. 
> 
> In this webinar, we present a short overview of the theory behind AxiSEM/Instaseis, highlight the new extensions for local scale simulations and databases, and show a short practical tutorial on how to use it. 
> 
> Click the link below to join the webinar using zoom on your PC, Mac, Linux, iOS or Android:
> 
> https://zoom.us/j/384711375 <https://zoom.us/j/384711375>
> Registration is required. Please log in early.
> 
> For more information on this and other CIG webinars, please visit us at: https://geodynamics.org/cig/events/webinars/ <https://geodynamics.org/cig/events/webinars/>
> 
> 
> 
> 
> 
> _______________________________________________
> CIG-SEISMO mailing list
> CIG-SEISMO at geodynamics.org <mailto:CIG-SEISMO at geodynamics.org>
> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo>
> 
> 
> 
> -- 
> Avinash Nayak,
> Research Associate,
> Department of Geoscience,
> University of Wisconsin, Madison
> _______________________________________________
> CIG-SEISMO mailing list
> CIG-SEISMO at geodynamics.org
> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo

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From johanna.lehr at ifg.uni-kiel.de  Mon Apr 16 02:17:57 2018
From: johanna.lehr at ifg.uni-kiel.de (Johanna Lehr)
Date: Mon, 16 Apr 2018 11:17:57 +0200
Subject: [CIG-SEISMO] Specfem3d for volcano simulation?
Message-ID: <39265d6e-65f9-ef2c-ec4f-26a4501cd3eb@ifg.uni-kiel.de>

Hello,

I consider using Specfem3d to run some simulations of wave propagation 
in a volcanic environment. I would like to know if it is possible to run 
such an experiment on a normal desktop PC and if there is a chance to do 
the meshing with a free tool like Gmsh.

I look forward to hearing back from you,

Johanna Lehr

-- 
Msc. Johanna Lehr
Institute of Geosciences, Kiel University
Otto-Hahn-Platz 1
24118 Kiel
Tel. +49 (0)431 880 3913


From INCHINP at my.erau.edu  Thu Apr 19 05:53:27 2018
From: INCHINP at my.erau.edu (Inchin, Pavel)
Date: Thu, 19 Apr 2018 12:53:27 +0000
Subject: [CIG-SEISMO] SPECFEM3D-Globe, near epicenter velocities
In-Reply-To: <7093fafb-1d04-8f15-8258-52d63c5bccfe@lma.cnrs-mrs.fr>
References: <1D5626F1-A72B-4725-80FC-7E97F619AAFD@my.erau.edu>
 <8a575b92-fb52-7a6e-9e5f-10a387448e6a@lma.cnrs-mrs.fr>
 <7FA93570-9F83-4F8F-AD53-7385A3AF255C@my.erau.edu>
 <7093fafb-1d04-8f15-8258-52d63c5bccfe@lma.cnrs-mrs.fr>
Message-ID: <93E582E3-F4BA-4816-B997-DFA08C280A93@my.erau.edu>

Good day!

Backing to my question, there are a couple of simulation in the attachments: NEX_XI=96 and NEX_XI=336. (x,y - 1000x1000 km grid). Both videos are velocities.
There are definitely hour-glass looking like effect for low resolution simulation in the vicinity of the epicenter, but no in NEX_XI=336. Thanks!

NEX_XI=96:

NEX_XI=336:

However, I backed to my initial question. You can find in NEX_XI=336 simulation long decaying pattern very close to the epicenter showing constant velocities. It doesn’t look like hour-glass effect, so I am not sure whether this is of real nature or not.

Thank you in advance.

Yours faithfully,
Paul



On Apr 9, 2018, at 10:02 AM, Dimitri Komatitsch <komatitsch at lma.cnrs-mrs.fr<mailto:komatitsch at lma.cnrs-mrs.fr>> wrote:


Dear Pavel,

You are welcome!

Best regards,
Dimitri.

On 04/09/2018 02:34 PM, Inchin, Pavel wrote:
Dr. Komatitsch
Thank you so much for help! I think this is what I need.
Yours faithfully,
Paul
On Apr 9, 2018, at 6:01 AM, Dimitri Komatitsch <komatitsch at lma.cnrs-mrs.fr<mailto:komatitsch at lma.cnrs-mrs.fr>> wrote:


Hi,

Yes, SPECFEM solves for the full wave equation and thus includes the near-field terms, computed accurately (see e.g. http://komatitsch.free.fr/preprints/GJI1_2002.pdf figure 20).

However, if you are in the mesh element of the source, or very close to it, you may get spurious Hourglass-like modes, see Schmicker et al. 2014 (attached). When they are present, getting rid of them requires changing the mesh (for instance randomizing it) near the source.

Best regards,
Dimitri.

On 04/05/2018 07:39 PM, Inchin, Pavel wrote:
Good day,
I have a problem with simulation of velocities at close to the epicenter distances.
I need to obtain surface vertical velocities with 2 km step to the North (+3000 km) and South (-3000 km) from the epicenter along longitude of epicenter, so I just get synthetic seismograms for every such point from SPECFEM3D-Globe.
Here is a result of global simulation SPECFEM3D-Globe for NEX_XI=96 at some time of simulation (20mHz-example figure). The simulation looks good.
Now, I do the same simulation for NEX_XI=240 and I get a very slowly decreasing rise/drop near the epicenter. Here are several figures for different times (50mhz-1.32, 50mhz-2.23, 50mhz-4.02, 50mhz-6.22 files; time is shown on figures - minutes from event):
So it doesn’t look like sinusoid, but slowly decreasing rise/drop (to the left and right from epicenter respectfully). It takes about 10-12 minutes to fully suppress this.
I do not have it for NEX_XI=96 simulation, but for shorter period simulation it starts to appear. I tried different Earth models, but seems it doesn’t play any role.
Does it have physical nature?
And more general question - how appropriate SPECFEM3D-Globe to simulate velocities at the epicenter and positions very close to it?
Thank you in advance
Paul Inchin

--
Dimitri Komatitsch, CNRS Research Director (DR CNRS)
Laboratory of Mechanics and Acoustics, Marseille, France
http://komatitsch.free.fr
<Schmicker_et_al_SEM_spurious_Hourglass_oscillations_spurious_modes_and_explanation_2014_with_analysis_in_yellow_by_Dimitri.pdf>

--
Dimitri Komatitsch, CNRS Research Director (DR CNRS)
Laboratory of Mechanics and Acoustics, Marseille, France
http://komatitsch.free.fr

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From INCHINP at my.erau.edu  Thu Apr 19 05:47:35 2018
From: INCHINP at my.erau.edu (Inchin, Pavel)
Date: Thu, 19 Apr 2018 12:47:35 +0000
Subject: [CIG-SEISMO] SPECFEM3D-Globe, near epicenter velocities
In-Reply-To: <7FA93570-9F83-4F8F-AD53-7385A3AF255C@my.erau.edu>
References: <1D5626F1-A72B-4725-80FC-7E97F619AAFD@my.erau.edu>
 <8a575b92-fb52-7a6e-9e5f-10a387448e6a@lma.cnrs-mrs.fr>
 <7FA93570-9F83-4F8F-AD53-7385A3AF255C@my.erau.edu>
Message-ID: <6D25B3B2-19F7-4885-84E3-39CB23D37AD8@my.erau.edu>

Good day!

Backing to my question, there are a couple of simulation in the attachments: NEX_XI=96 and NEX_XI=336. (x,y - 1000x1000 km grid). Both videos are velocities.
There are definitely hour-glass looking like effect for low resolution simulation in the vicinity of the epicenter, but no in NEX_XI=336. Thanks!






However, I backed to my initial question. You can find in NEX_XI=336 simulation long decaying pattern very close to the epicenter showing constant velocities. It doesn’t look like hour-glass effect, so I am not sure whether this is of real nature or not.

Thank you in advance.

Yours faithfully,
Paul


> On Apr 9, 2018, at 8:34 AM, Inchin, Pavel <INCHINP at my.erau.edu> wrote:
>
> Dr. Komatitsch
>
> Thank you so much for help! I think this is what I need.
>
> Yours faithfully,
> Paul
>
>> On Apr 9, 2018, at 6:01 AM, Dimitri Komatitsch <komatitsch at lma.cnrs-mrs.fr> wrote:
>>
>>
>> Hi,
>>
>> Yes, SPECFEM solves for the full wave equation and thus includes the near-field terms, computed accurately (see e.g. http://komatitsch.free.fr/preprints/GJI1_2002.pdf figure 20).
>>
>> However, if you are in the mesh element of the source, or very close to it, you may get spurious Hourglass-like modes, see Schmicker et al. 2014 (attached). When they are present, getting rid of them requires changing the mesh (for instance randomizing it) near the source.
>>
>> Best regards,
>> Dimitri.
>>
>> On 04/05/2018 07:39 PM, Inchin, Pavel wrote:
>>> Good day,
>>> I have a problem with simulation of velocities at close to the epicenter distances.
>>> I need to obtain surface vertical velocities with 2 km step to the North (+3000 km) and South (-3000 km) from the epicenter along longitude of epicenter, so I just get synthetic seismograms for every such point from SPECFEM3D-Globe.
>>> Here is a result of global simulation SPECFEM3D-Globe for NEX_XI=96 at some time of simulation (20mHz-example figure). The simulation looks good.
>>> Now, I do the same simulation for NEX_XI=240 and I get a very slowly decreasing rise/drop near the epicenter. Here are several figures for different times (50mhz-1.32, 50mhz-2.23, 50mhz-4.02, 50mhz-6.22 files; time is shown on figures - minutes from event):
>>> So it doesn’t look like sinusoid, but slowly decreasing rise/drop (to the left and right from epicenter respectfully). It takes about 10-12 minutes to fully suppress this.
>>> I do not have it for NEX_XI=96 simulation, but for shorter period simulation it starts to appear. I tried different Earth models, but seems it doesn’t play any role.
>>> Does it have physical nature?
>>> And more general question - how appropriate SPECFEM3D-Globe to simulate velocities at the epicenter and positions very close to it?
>>> Thank you in advance
>>> Paul Inchin
>>
>> --
>> Dimitri Komatitsch, CNRS Research Director (DR CNRS)
>> Laboratory of Mechanics and Acoustics, Marseille, France
>> http://komatitsch.free.fr
>> <Schmicker_et_al_SEM_spurious_Hourglass_oscillations_spurious_modes_and_explanation_2014_with_analysis_in_yellow_by_Dimitri.pdf>
>

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From komatitsch at lma.cnrs-mrs.fr  Thu Apr 19 09:14:53 2018
From: komatitsch at lma.cnrs-mrs.fr (Dimitri Komatitsch)
Date: Thu, 19 Apr 2018 18:14:53 +0200
Subject: [CIG-SEISMO] Specfem3d for volcano simulation?
In-Reply-To: <39265d6e-65f9-ef2c-ec4f-26a4501cd3eb@ifg.uni-kiel.de>
References: <39265d6e-65f9-ef2c-ec4f-26a4501cd3eb@ifg.uni-kiel.de>
Message-ID: <0d21d7c8-a477-b5de-5c51-6d130390478f@lma.cnrs-mrs.fr>


Hi Johanna,

Yes, see e.g. 
http://komatitsch.free.fr/preprints/GJI_SPECFEM3D_version2_2011.pdf 
Figure 2  or http://komatitsch.free.fr/preprints/bssa_Taipei_2008.pdf 
Figure 2.

Whether you can run on a desktop will depend on your max frequency; 
usually realistic 3D runs require a small parallel machine, or a large 
desktop (we have one here with 192 GB of RAM on which we run small 3D 
cases).

Best regards,
Dimitri.

On 04/16/2018 11:17 AM, Johanna Lehr wrote:
> Hello,
> 
> I consider using Specfem3d to run some simulations of wave propagation 
> in a volcanic environment. I would like to know if it is possible to run 
> such an experiment on a normal desktop PC and if there is a chance to do 
> the meshing with a free tool like Gmsh.
> 
> I look forward to hearing back from you,
> 
> Johanna Lehr
> 

-- 
Dimitri Komatitsch, CNRS Research Director (DR CNRS)
Laboratory of Mechanics and Acoustics, Marseille, France
http://komatitsch.free.fr

From LHU004 at e.ntu.edu.sg  Thu Apr 26 20:17:34 2018
From: LHU004 at e.ntu.edu.sg (#HU LEI#)
Date: Fri, 27 Apr 2018 03:17:34 +0000
Subject: [CIG-SEISMO] ask for help: Any codes that deal with the area/volume
 integral of kernel in the case of external meshing
Message-ID: <SIXPR01MB0302B0AE7D1B17BF831F12CFFB8D0@SIXPR01MB0302.apcprd01.prod.exchangelabs.com>

Hi, to whom it may concern,


I am a phd student from NANYANG TECHNOLOGICAL UNIVERSITY. I am wondering if you have codes dealing with area/volume integral of kernel in the case of external meshing. I really appreciate it if you can help me with that.


Regards，


Hu Lei


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