[CIG-SEISMO] Mineos problem

[Dimitri Komatitsch]

Hi all,

I am not a Mineos expert myself but I know Li Zhao (cc'ed) worked on an 
optimized version back in 2007 (which he called Mineos2007), thus let me 
cc him to see if he knows how to fix that.

Best wishes,
Dimitri.

On 03/03/2016 17:03, Jeroen Tromp wrote:
> I think this is a known problem with the version of mineos available via
> CIG. In fact, I believe the main author of mineos, Guy Masters, advises
> against using it...
>
> My recommendation is reaching out to Guy.
>
> Best regards,
>
> Jeroen
>
> On 3/3/16 10:00 AM, Matthew Knepley wrote:
>> We have a problem with the eigenfunctions calculated by Mineos at near
>> degenerate eigenvalues.
>>
>> Mineos works fine to calculate the eigenfrequencies of normal modes,
>> but there is a problem for the eigenfunctions. For those different
>> modes with very close eigenfrequencies in the mathematical point of
>> view(see Figure f-l), Mineos regards them as degeneracy in the
>> numerical point of view, and therefore it gets a linear combination of
>> pure R mode's and pure Stoneley mode's eigenfunctions, i.e. the
>> eigenfunctions are not orthogonalized. For example, based on Okal's
>> classification [1], 2S25  and 3S25 should be Stoneley mode and R mode,
>> respectively. But the eigenfunctions from Mineos have both surface
>> oscillations (the feature of R modes) and exponentially decaying along
>> CMB (the feature of Stoneley modes).(see Figure 2S25 and 3S25)
>>
>> Since the eigenfunction is not calculated properly, the group velocity
>> is also not reliable. According to Okal's paper [1], for each branch
>> of R modes or Stoneley modes, the group velocity should be continuous.
>> And we notice that there are some "bad points" in the group velocity
>> picture, which are exactly the modes we mention before. (see Figure
>> groupV_R2)
>>
>> What eigensolver is being used inside Mineos? The standard symmetric
>> eigensolvers in LAPACK handle this problem I believe.
>>
>>   Thanks,
>>
>>     Jingchen and Matt
>>
>> References:
>>
>> [1] Okal, Emile A. "A physical classification of the earth's
>> spheroidal modes." Journal of Physics of the Earth 26.1 (1978): 75-103.
>>
>>
>>
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>
>
>
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-- 
Dimitri Komatitsch
CNRS Research Director (DR CNRS), Laboratory of Mechanics and Acoustics,
UPR 7051, Marseille, France    http://komatitsch.free.fr