[CIG-SEISMO] specfem input model

[Dimitri Komatitsch]

Dear Alejandro,

I agree. I was assuming that you wanted to propagate wave in the mantle 
and crust, underneath the ocean, taking into account the ocean load at 
periods that are not too short (i.e. above 20 seconds). Otherwise as 
Jeroen says you will need to mesh the ocean (i.e. the bathymetry model), 
which is another story: if you manage to create a good mesh, then 
computing it with SPECFEM3D (rather than SPECFEM3D_GLOBE) is easy; but 
creating a good mesh using e.g. CUBIT and a bathymetry model at high 
resolution can be difficult.

Best regards,
Dimitri.

On 12/08/2010 04:11 PM, Jeroen Tromp wrote:
> Dear Alejandro:
>
> If you are planning to simulate wave propagation "in the North Atlantic
> ocean", with an emphasis on "in", then you need to use the SPECFEM3D
> "Sesame" package, which accommodates fluid-solid coupling and actual
> wave propagation in the fluid. If you are interested in propagating
> surface waves with periods longer than, say, 20 s, in the solid Earth
> underneath the ocean, then you may use SPECFEM3D_GLOBE as is, with the
> OCEANS flag set to .true., simulating wave propagation based on the
> ocean-load approximation (Komatitsch & Tromp, 2002b). If you use the
> one-chunk option, you may still turn 3D model flags on, e.g., S20RTS or
> S362ANI.
>
> Jeroen Tromp
>
> On 12/8/10 9:32 AM, Dimitri Komatitsch wrote:
>>
>> Hi Alejandro,
>>
>> Thank you for your interest in the package. I think that
>> SPECFEM3D_GLOBE is more suitable for what you want to do (it can be
>> used directly as is, without any modification). I cc the other
>> developers, who can maybe confirm that (or not) (in particular Brian
>> Savage, Qinya, and people at Princeton).
>>
>> Our absorbing conditions on the edges of the mesh are not very good
>> yet, we are adding support for CPML absorbing layers but for technical
>> reasons that code is not ready yet therefore for now I suggest you
>> take a model that is larger than what you are interested in (for
>> instance adding 10 degrees to each side or something like that, to
>> avoid spurious edge effects). This will not be needed any more in the
>> next release with CPML absorbing layers but for now in the current
>> version it is safer.
>>
>> Thank you,
>> Best regards,
>>
>> Dimitri.
>>
>> On 12/08/2010 02:33 AM, Alejandro Gallego wrote:
>>> HI,
>>> I am postdoc student at the University of Hawaii and I am trying to
>>> use Specfem to model seismic waves in the North Atlantic ocean
>>> I am working in an area of 20 x 30 degrees. I have two main questions.
>>> 1) Should I use Specfem_Global or Regional to work with different
>>> mantle models.
>>> I think the regional doesn't include a mantle model. 2) How is the
>>> call of the function model_s20rts( ), I am not clear what kind of
>>> interval grid I need as an input and how can I modify this interval.
>>> Any advice in how to change mantle model will be very helpful.
>>>
>>> Thanks for this amaizing software
>>>
>>> Alejandro
>>> _______________________________________________
>>> CIG-SEISMO mailing list
>>> CIG-SEISMO at geodynamics.org
>>> http://geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo
>>>
>>
>
>

-- 
Dimitri Komatitsch - dimitri.komatitsch aT univ-pau.fr
Professor, University of Pau, Institut universitaire de France,
CNRS and INRIA Magique3D, France   http://www.univ-pau.fr/~dkomati1