[CIG-SEISMO] SPECFEM2D code became unstable and blew up

[Parvathy Sindhu Nair]

Hi Dimtri,
I'm not very good at this software, so I'm not really sure what I am doing
wrong. But when I tried ./configure --enable-debug, I'm getting this message

## ---------------- ##
## Specfem 2D 7.0.0 ##
## ---------------- ##

./configure has completed and set up a default configuration to build.

You may wish to modify the following files before running a simulation:
  DATA/Par_file           Set parameters affecting the simulation.
  DATA/SOURCE             Set the source parameters before running the
solver.

And I've tried with amplitude 1.17e10 using this option
USE_CONSTANT_MAX_AMPLITUDE      = .true.        # by default the code
normalizes each image independently to its maximum; use this option to use
the global maximum below instead
CONSTANT_MAX_AMPLITUDE_TO_USE   = 1.17d10         # constant maximum
amplitude to use for all color images if the above
USE_CONSTANT_MAX_AMPLITUDE option is true

But I'm getting an error

Program received signal SIGFPE: Floating-point exception - erroneous
arithmetic operation.

Backtrace for this error:
#0  0x7F1E30192497
#1  0x7F1E30192ADE
#2  0x3996A358EF
#3  0x422E3A in check_stability_ at check_stability.F90:104 (discriminator
8)
#4  0x4991D1 in iterate_time_ at iterate_time.F90:1328
#5  0x401D6E in specfem2d at specfem2D.F90:383
#6  0x3996A21D64
Floating point exception (core dumped)
I'm not exactly sure what I am doing wrong with my Data/ files.

Thank you
Parvathy


On 13 February 2016 at 06:23, Dimitri Komatitsch <komatitsch at lma.cnrs-mrs.fr
> wrote:

>
> Hi Parvathy,
>
> Hard to tell, but this is either the time step that is a bit too high
> (unlikely, since the CFL you used (0.44) seems fine), or if the amplitude
> of the source you used is very high then the code can erroneously think
> that the run became unstable if amplitudes went above 1.e+25 (that is what
> we detect, since we have no way of detecting instabilities; instead we
> detect "very high values" that do not seem to make sense).
>
> If so, try reducing the amplitude of your source by 1.e+10 or so to see if
> the problem disappears (since the wave equation is linear, doing so is
> safe).
>
> Another thing you can do is configure the code with ./configure
> --enable-debug to see if the run then detects any bug (the 2D code was
> significantly restructured recently and thus we cannot exclude that; if so
> please let us know and we will fix it).
>
> Thanks,
> Dimitri.
>
>
> On 02/11/2016 09:46 PM, Parvathy Sindhu Nair wrote:
>
>> Hi
>> I'm a summer research student working with SPECFEM2D software and while
>> running the simulation I'm getting this error
>>
>> /Warning: failed creating color image, maximum value of amplitude in
>> image color is invalid
>>   amplitude max =    3.7316137641792927E+025  with threshold at
>> 1.0000000000000001E+025
>>   Please check your simulation setup...
>>   code became unstable and blew up (image_color_data)
>>   Error detected, aborting MPI... proc            0
>> STOP error, program ended in exit_MPI
>> /
>> I'm not sure why this is happening. I used source wave frequency of
>> 100Hz, with mesh file thickness to be 5m. My CFL stability condition was
>> 0.44 and my  histogram of min number of points per S wavelength in solid
>> regions and P wavelength in fluid region were in the normal region. But
>> in the output snapshot my wave suddenly disappears (I've attached my
>> snapshots here). Could someone help me with this?
>> Thanking you
>> Yours truly
>> Parvathy Sindhu Nair
>> University of Auckland
>>
>>
>> _______________________________________________
>> 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,
> UPR 7051, Marseille, France    http://komatitsch.free.fr
>
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