[CIG-SEISMO] Mineos problem
Jeroen Tromp
jtromp at princeton.edu
Thu Mar 3 08:03:27 PST 2016
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.
>
>
>
> _______________________________________________
> CIG-SEISMO mailing list
> CIG-SEISMO at geodynamics.org
> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.geodynamics.org/pipermail/cig-seismo/attachments/20160303/f1c89785/attachment.html>
More information about the CIG-SEISMO
mailing list