[CIG-SEISMO] SPECFEM2D_USER QUESTION

[Dimitri Komatitsch]

Hi,

It is not possible to start at zero, the code (as any other code in the 
time domain) needs to shift the source in time in order to start with a 
medium at rest, and then subtract that shift when saving the seismograms.

Then, in postprocessing you can safely open the seismogram files and 
remove all the values before zero if you want. Or in your plotting 
software just use a time axis that starts at zero and they will be 
ignored automatically.

Best wishes,
Dimitri.

On 11/04/2014 10:15, 周小鹏 wrote:
> Hello,professor!
>         I am a beginner who are using your software SPECFEM2D 7.0, the
> simulation time in the OUTPUT_FILES always starts at a negative value,I
> want to start by zero.
>         I set USER_T0 in Par_file to a positive value but it is no use!I
> intend to modified USER_T0 to a positive one in constants.h which is
> advised in the manual_SPECFEM2D,but I didn't find USER_T0 in
> constants.h.What should I do?(I use the Ricker wavelet as the
> source-time function,the dominant source frequency f0 equals to 5Hz).
>        Thank you!
>
>
>
>
>
>
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-- 
Dimitri Komatitsch
CNRS Research Director (DR CNRS), Laboratory of Mechanics and Acoustics,
UPR 7051, Marseille, France    http://komatitsch.free.fr