External Source Time Functions

SPECFEM
1

Hello,

I am interested in implementing an external source time function (STF) so I can model a Brune source pulse. I have a couple of questions about the format of the input STF:

  1. Is the input function supposed to be the slip rate, or the slip displacement? I ask because when I display the data in “plot_source_time_function.txt” for a default (Gaussian) STF used by specfem, I receive a curve that looks more like the integral of a Gaussian.

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  2. What is the significance of the amplitude of the STF? Does it matter, or is the shape/duration of the function more significant? For example, would it make any difference in my solution if I scaled this function by a factor of 10?

Thank you,

Ian